Fuel injection valve

A fuel injection valve includes a valve body, a fixed core, a movable core, a holder, and a stopper. The movable core has an inner core that contacts the stopper, and an outer core press-fitted to an outer peripheral surface of the inner core. The outer core has, in a moving direction of the movable core, a press-fit region which is press-fitted to the outer peripheral surface of the inner core, and a non-press-fit region which is not press-fitted to the outer peripheral surface of the inner core and is adjacent to the press-fit region in the moving direction. Between the inner peripheral surface of the holder and the outer peripheral surface of the movable core, the smallest gap in the press-fit region is larger than the smallest gap in the non-press-fit region.

TECHNICAL FIELD

The present disclosure relates to a fuel injection valve that injects fuel.

BACKGROUND

A conventional fuel injection valve includes a fixed core that generates a magnetic attraction force upon energization of a coil, a movable core that is attracted and moved by the fixed core, and a valve body that is actuated by the moving movable core to open the valve such that fuel is jetted from a nozzle hole. In recent years, fuel pressure becomes high, and a valve closing force urging the valve body tends to increase. Hence, a large valve opening force is required in order to open the valve against the large valve closing force.

SUMMARY

According to at least one embodiment of the present disclosure, a fuel injection valve includes: a valve body that opens and closes a nozzle hole for injecting a fuel; a fixed core that generates a magnetic attraction force upon energization of a coil; a movable core that has a cylindrical shape and opens the nozzle hole by moving together with the valve body by the magnetic attraction force; a holder that has a movable chamber filled with the fuel, and accommodates the movable core movable in the movable chamber; and a stopper member that contacts the movable core to restrict movement of the movable core in a direction away from the nozzle hole. The movable core includes an inner core that contacts the stopper member, and an outer core that is press-fitted to an outer peripheral surface of the inner core. The outer core includes, in a moving direction of the movable core, a press-fit region in which the outer core is press-fitted to the outer peripheral surface of the inner core, and a non-press-fit region in which the outer core is not press-fitted to the outer peripheral surface of the inner core, the non-press-fit region being next to the press-fit region in the moving direction. Between an inner peripheral surface of the holder and an outer peripheral surface of the movable core, a smallest gap in the press-fit region is larger than a smallest gap in the non-press-fit region.

DETAILED DESCRIPTION

A general fuel injection valve includes a fixed core that generates a magnetic attraction force upon energization of a coil, a movable core that is attracted and moved by the fixed core, and a valve body that is actuated by the moving movable core to open the valve such that fuel is jetted from a nozzle hole. In recent years, fuel pressure becomes high, and a valve closing force urging the valve body tends to increase. Hence, a large valve opening force is required in order to open the valve against the large valve closing force.

As a countermeasure against the above, a core boost structure may be proposed as a comparative example. That is, for the valve opening operation of the valve body, first, movement of the movable core is started in a state in which the movable core is not engaged with the valve body. And thereafter, when the movable core is moved by a predetermined distance, the movable core is brought into contact with the valve body to start the valve opening operation.

According to the core boost structure described above, since the movable core is not yet engaged with the valve body immediately after a start of energization, the movable core which is not subjected to a force of a fuel pressure can quickly raise a moving speed of the movable core by an initial small magnetomotive force. Then, since the movable core comes into contact with the valve body and starts the valve opening operation when the moving speed becomes sufficiently high, that is, when the movable core is moved by the predetermined distance, the valve opening operation can be performed by the aid of a collision force of the movable core in addition to a magnetic attraction force. Therefore, the valve opening operation of the valve body can be performed even when the fuel pressure is high. Further, magnetic attraction force required for opening the valve can be reduced.

However, in the core boost structure described above, the movable core moves in two stages: a movement from the start of the energization to the contact with the valve body; and a subsequent movement while keeping contact with the valve body. For that reason, variation in time period from the start of the energization to the start of the valve opening operation is directly linked to variation in amount of injected fuel in one valve opening operation. Further, not only such variation in time period from the start of energization to opening of the valve, but also variation in time period from an end of the energization to closure of the valve can be considered.

In contrast to the comparative example, according to a first aspect of the present disclosure, a fuel injection valve includes: a valve body that opens and closes a nozzle hole for injecting a fuel; a fixed core that generates a magnetic attraction force upon energization of a coil; a movable core that has a cylindrical shape and opens the nozzle hole by moving together with the valve body by the magnetic attraction force; a holder that has a movable chamber filled with the fuel, and accommodates the movable core movable in the movable chamber; and a stopper member that contacts the movable core to restrict movement of the movable core in a direction away from the nozzle hole. The movable core includes an inner core that contacts the stopper member, and an outer core that is press-fitted to an outer peripheral surface of the inner core. The outer core includes, in a moving direction of the movable core, a press-fit region in which the outer core is press-fitted to the outer peripheral surface of the inner core, and a non-press-fit region in which the outer core is not press-fitted to the outer peripheral surface of the inner core, the non-press-fit region being next to the press-fit region in the moving direction. Between an inner peripheral surface of the holder and an outer peripheral surface of the movable core, a smallest gap in the press-fit region is larger than a smallest gap in the non-press-fit region.

In this example, a flow resistance received by the movable core from the fuel existing in the gap between the outer core outer peripheral surface and the holder inner peripheral surface is greatly influenced by the smallest gap when the size of the gap changes in accordance with the axial position. The gap in the press-fit region between the inner peripheral surface of the holder and the outer peripheral surface of the movable core is larger in variation among products than the gap in the non-press-fit region. Therefore, when the minimum gap in the press-fit region is smaller than the minimum gap in the non-press-fit region contrary to the above first aspect, the flow resistance is greatly affected by the gap in the press-fit region. As a result, a large variation in the flow resistance among products occurs.

In contrast, according to the first aspect, since the minimum gap in the press-fit region is larger than the minimum gap in the non-press-fit region, the influence on the flow resistance from the gap in the press-fit region can be reduced, and variation in moving speed of the movable core can be reduced. As a result, variation in valve opening response among products can be reduced, and consequently, variation in injection amount can be reduced.

According to a second aspect of the present disclosure, a fuel injection valve includes: a valve body that opens and closes a nozzle hole for injecting a fuel; a fixed core that generates a magnetic attraction force upon energization of a coil; a movable core that has a cylindrical shape and opens the nozzle hole by moving together with the valve body by the magnetic attraction force; a holder that has a movable chamber filled with the fuel, and accommodates the movable core movable in the movable chamber in a movable state; and a stopper member that contacts the movable core to restrict movement of the movable core in a direction away from the nozzle hole. The movable core includes an inner core that contacts the stopper member, and an outer core that is press-fitted to an outer peripheral surface of the inner core. The outer core includes, in a moving direction of the movable core, a press-fit region in which the outer core is press-fitted to the outer peripheral surface of the inner core, and a non-press-fit region which is next to the press-fit region in the moving direction. A portion of the press-fit region which has been expanded in the radial direction by press-fitting is removed such that a maximum outer diameter of the outer core in the press-fit region is same as a maximum outer diameter of the outer core in the non-press-fit region.

According to the second aspect, the minimum gap in the press-fit region and the minimum gap in the non-press-fit region are same, so that influence on the flow resistance from the gap in the press-fit region can be reduced, and variation in moving speed of the movable core can be reduced. As a result, variation in valve opening response among products can be reduced, and consequently, variation in injection amount can be reduced.

Hereinafter, multiple embodiments for implementing the present disclosure will be described referring to drawings. In the respective embodiments, a part that corresponds to a matter described in a preceding embodiment may be assigned the same reference numeral, and redundant explanation for the part may be omitted.

When only a part of a configuration is described in an embodiment, another preceding embodiment may be applied to the other parts of the configuration. The parts may be combined even if it is not explicitly described that the parts can be combined. The embodiments may be partially combined even if it is not explicitly described that the embodiments can be combined, provided there is no harm in the combination.

First Embodiment

A fuel injection valve1shown inFIG.1is attached to a cylinder head or a cylinder block of an ignition type internal combustion engine mounted on a vehicle. A gasoline fuel accumulated in a vehicle-mounted fuel tank is pressurized by a fuel pump (not shown) and supplied to a fuel injection valve1, and the supplied high-pressure fuel is directly injected into a combustion chamber of the internal combustion engine from nozzle holes11aprovided in the fuel injection valve1.

The fuel injection valve1includes a nozzle hole body11, a main body12, a fixed core13, a non-magnetic member14, a coil17, a support member18, a first spring member SP1, a second spring member SP2, a needle20, a movable core30, a sleeve40, a cup50, a guide member60, and the like. The nozzle hole body11, the main body12, the fixed core13, the support member18, the needle20, the movable core30, the sleeve40, the cup50, and the guide member60are made of metal.

As shown inFIG.2, the nozzle hole body11has the multiple nozzle holes11afor injecting a fuel. The needle20is located inside the nozzle hole body11, and a flow channel11bfor allowing a high-pressure fuel to flow to the nozzle holes11ais provided between an outer peripheral surface of the needle20and an inner peripheral surface of the nozzle hole body11. A body-side seat11son which a valve body-side seat20sformed on the needle20is separated and seated is formed on the inner peripheral surface of the nozzle hole body11. The valve body-side seat20sand the body-side seat11sare shaped to extend annularly around an axis line C of the needle20. When the needle20is separated and seated on the body-side seat11s, the flow channel11bis opened and closed, and the nozzle holes11aare opened and closed.

The main body12and the non-magnetic member14are cylindrical in shape. A cylindrical end portion of the main body12, which is closer to the nozzle holes11awith respect to the main body12(on a nozzle hole side), is fixed to the nozzle hole body11by welding. A cylindrical end portion of the main body12on a side facing away from the nozzle holes11awith respect to the main body12(on a side opposite to the nozzle holes), is fixed to a cylindrical end portion of the non-magnetic member14by welding. A cylindrical end portion of the non-magnetic member14on the side opposite to the nozzle hole is fixed to the fixed core13by welding.

A nut member15is fastened to a threaded portion13N of the fixed core13in a state of being locked to a locking portion12cof the main body12. An axial force generated by the fastening generates a surface pressure pressing the nut member15, the main body12, the non-magnetic member14, and the fixed core13against each other in a direction of the axis line C (in a vertical direction inFIG.1). Instead of generating such a surface pressure by fastening screws, the surface pressure may be generated by press-fitting.

The main body12is made of a magnetic material such as stainless steel, and has a flow channel12bfor allowing the fuel to flow in the nozzle holes11ainside. In the flow channel12b, the needle20is accommodated so as to be movable in the direction of the axis line C. The main body12and the non-magnetic member14correspond to a “holder” having a movable chamber12afilled with the fuel. A movable portion M (refer toFIGS.9and10) which is an assembly in which the needle20, the movable core30, the second spring member SP2, the sleeve40, and the cup50are assembled together is movably accommodated in the movable chamber12a. A gap L1ashown inFIG.9indicates a size of a gap between a valve closing contact surface21band a valve closing force transmission contact surface52cin the direction of the axis line C. The size of the gap L1ais the same as a gap L1shown in a column (a) ofFIG.4.

The flow channel12bis shaped to communicate with a downstream side of the movable chamber12aand extend in the direction of the axis line C. A center line of the flow channel12band the movable chamber12acoincides with a cylindrical center line (axis line C) of the main body12. A nozzle hole side portion of the needle20is slidably supported by an inner wall surface11cof the nozzle hole body11, and a portion of the needle20on a side opposite to the nozzle holes is slidably supported by an inner wall surface51bof the cup50(refer toFIGS.8and12). Two positions of an upstream end portion and a downstream end portion of the needle20are slidably supported in this manner, whereby the movement of the needle20in a radial direction is limited, and the inclination of the needle20relative to the axis line C of the main body12is limited.

The needle20corresponds to a “valve body” that opens and closes the nozzle holes11a, and is made of a magnetic material such as stainless steel, and has a shape extending in the direction of the axis line C. The valve body-side seat20sdescribed above is formed on a downstream-side end face of the needle20. When the needle20moves to the downstream side in the direction of the axis line C (valve closing operation), the valve body-side seat20sis seated on the body-side seat11sto close the flow channel11band the nozzle holes11a. When the needle20moves to the upstream side in the direction of the axis line C (valve opening operation), the valve body-side seat20sis separated from the body-side seat11sto open the flow channel11band the nozzle holes11a.

The needle20has an internal passage20aand lateral holes20bfor allowing the fuel to flow through the nozzle holes11a(refer toFIG.3). The multiple lateral holes20bare provided in a circumferential direction. The multiple lateral holes20bare provided at regular intervals in the circumferential direction. The internal passage20ahas a shape extending in the direction of the axis line C of the needle20. An inflow port is provided at an upstream end of the internal passage20a, and the lateral holes20bare connected to a downstream end of the internal passage20a. The lateral holes20bextend in a direction crossing the direction of the axis line C and communicate with the movable chamber12a.

As shown inFIG.7, the needle20has a contact portion21, a core sliding portion22, a press-fit portion23, an outflow portion24, a first large diameter portion25, a first small diameter portion26, a second large diameter portion27, a second small diameter portion28, and a nozzle hole-side support portion29in a stated order from the opposite side (upper end side) to the lower end side of the valve body-side seat20s. The contact portion21has the valve closing contact surface21bcontacting the valve closing force transmission contact surface52cof the cup50.

The cup50is slidably assembled to the contact portion21, and an outer peripheral surface of the contact portion21slides with an inner peripheral surface of the cup50. The movable core30is slidably assembled to the core sliding portion22, and an outer peripheral surface of the core sliding portion22slides with an inner peripheral surface of the movable core30. A sleeve40is press-fitted into the press-fit portion23. The lateral holes20bare provided in the outflow portion24.

An outer diameter D1of the contact portion21is set to be larger than an outer diameter D2of the core sliding portion22, the outer diameter D2of the core sliding portion22is set to be larger than an outer diameter D3of the press-fit portion23, and the outer diameter D3of the press-fit portion23is set to be larger than an outer diameter of the outflow portion24. A connection part22abetween the core sliding portion22and the press-fit portion23and a connection portion23abetween the press-fit portion23and the outflow portion24are each formed in a tapered shape. A diameter of an inner peripheral surface41aof the sleeve40in a state before press-fitting is set to be smaller than the outer diameter D3of the press-fit portion23, and press-fitting can be performed.

The outer diameters of the first large diameter portion25and the second large diameter portion27are larger than the outer diameters of the first small diameter portion26and the second small diameter portion28. The weight reduction is achieved by having the first small diameter portion26and the second small diameter portion28. The first large diameter portion25and the second large diameter portion27function as a support portion when the needle20is cut. The second small diameter portion28functions as an escape portion so that a cutting tool does not interfere with cutting of the nozzle hole-side support portion29. The nozzle hole-side support portion29is slidably supported by the inner wall surface11cof the nozzle hole body11.

The cup50has a circular plate portion52having a circular plate shape and a cylindrical portion51having a cylindrical shape. The circular plate portion52has a through hole52apenetrating in the direction of the axis line C. A surface of the circular plate portion52on a side opposite to the nozzle holes functions as a spring contact surface52bthat contacts the first spring member SP1. A surface of the circular plate portion52on a nozzle hole side functions as a valve closing force transmission contact surface52cthat contacts the needle20and transmits a first elastic force (a valve closing elastic force). The circular plate portion52corresponds to a “valve body transmission portion” that contacts the first spring member SP1and the needle20to transmit the first elastic force to the needle20. The cylindrical portion51has a cylindrical shape extending from an outer peripheral end of the circular plate portion52to the nozzle hole side. A nozzle hole-side end face of the cylindrical portion51functions as a core contact end face51athat contacts the movable core30. The inner wall surface51bof the cylindrical portion51slides with the outer peripheral surface of the contact portion21of the needle20.

The fixed core13is made of a magnetic material such as stainless steel, and has a flow channel13afor allowing the fuel to flow through the nozzle holes11a. The flow channel13acommunicates with the internal passage20aprovided inside the needle20(refer toFIG.3) and an upstream side of the movable chamber12a, and extends in the direction of the axis line C. The flow channel13aaccommodates the guide member60, the first spring member SP1, and the support member18.

The support member18has a cylindrical shape and is press-fitted into an inner wall surface of the fixed core13. The first spring member SP1is a coiled spring disposed on the downstream side of the support member18, and elastically deforms in the direction of the axis line C. An upstream-side end face of the first spring member SP1is supported by the support member18, and a downstream-side end face of the first spring member SP1is supported by the cup50. A force generated by the elastic deformation of the first spring member SP1(a first elastic force) urges the cup50toward the downstream side. The degree of press-fitting of the support member18in the direction of the axis line C is adjusted, to thereby adjust a magnitude of the elastic force for urging the cup50(first set load).

As shown inFIG.3, the guide member60has a cylindrical shape made of a magnetic material such as stainless steel, and is press-fitted into an enlarged diameter portion13cformed in the fixed core13. The enlarged diameter portion13chas a shape in which the flow channel13ais enlarged in the radial direction. The guide member60has a circular plate portion62having a circular plate shape and a cylindrical portion61having a cylindrical shape. The circular plate portion62has a through hole62apenetrating in the direction of the axis line C. A surface of the circular plate portion62on the side opposite to the nozzle holes contacts an inner wall surface of the enlarged diameter portion13c. The cylindrical portion61has a cylindrical shape extending from the outer peripheral end of the circular plate portion62to the nozzle hole side. A nozzle hole-side end face of the cylindrical portion61functions as a stopper contact end face61athat contacts the movable core30. An inner wall surface of the cylindrical portion51forms a sliding surface61bthat slides with an outer peripheral surface51dof the cylindrical portion51of the cup50(refer toFIG.12).

In short, the guide member60has a guide function of sliding the outer peripheral surface of the cup50moving in the direction of the axis line C, and a stopper function of contacting the movable core30moving in the direction of the axis line C and restricting the movable core30from moving to the side opposite to the nozzle holes. In other words, the guide member60corresponds to a “stopper member” that contacts the movable core30and restricts the movable core30from moving away from the nozzle holes11a.

A resin member16is provided on an outer peripheral surface of the fixed core13. The resin member16has a connector housing16a, and a terminal16bis accommodated in the connector housing16a. The terminal16bis electrically connected to the coil17. An external connector (not shown) is connected to the connector housing16a, and an electric power is supplied to the coil17through the terminal16b. The coil17is wound around a bobbin17ahaving an electrical insulation property to form a cylindrical shape, and is disposed on a radially outer side of the fixed core13, the non-magnetic member14, and the movable core30. The fixed core13, the nut member15, the main body12, and the movable core30form a magnetic circuit for flowing a magnetic flux generated accompanying a power supply (energization) to the coil17(refer to a dotted arrow inFIG.3).

As shown inFIG.3, the movable core30is disposed on the nozzle hole side with respect to the fixed core13, and is accommodated in the movable chamber12ain a state of being movable in the direction of the axis line C. The movable core30has an outer core31and an inner core32. The outer core31has a cylindrical shape made of a magnetic material such as stainless steel, and the inner core32has a cylindrical shape made of a nonmagnetic material such as stainless steel having a magnetic property. The outer core31is press-fitted into an outer peripheral surface of the inner core32.

The needle20is inserted into a cylindrical inner portion of the inner core32. The inner core32is assembled to the needle20so as to be slidable relative to the needle20in the axis line C. A gap (inner gap) between an inner peripheral surface of the inner core32and an outer peripheral surface of the needle20is set to be smaller than a gap (outer gap) between an outer peripheral surface of the outer core31and an inner peripheral surface of the main body12. Those gaps are set so that the outer core31does not contact the main body12while allowing the inner core32to contact the needle20.

The inner core32contacts the guide member60as a stopper member, the cup50, and the needle20. For that reason, a material having a higher hardness than that of the outer core31is used for the inner core32. The outer core31has a movable core facing surface31cfacing the fixed core13, and a gap is provided between the movable core facing surface31cand the fixed core13. Therefore, in a state in which a magnetic flux flows by energizing the coil17as described above, a magnetic attraction force attracted to the fixed core13acts on the outer core31by provision of the gap.

The sleeve40corresponds to a “fixed member” that is press-fitted into the needle20. The sleeve40is made of a cylindrical metal having a through hole40a(refer toFIG.7), and has an insertion cylindrical portion41, a connection portion42, and a support portion43. The insertion cylindrical portion41has a cylindrical shape, and is press-fitted into the press-fit portion23of the needle20. The connection portion42has a cylindrical shape in which the insertion cylindrical portion41is enlarged in the radial direction, and connects the insertion cylindrical portion41and the support portion43. The connection portion42guides the second spring member SP2to reduce a positional deviation of the second spring member SP2in the radial direction. The support portion43has an annular flange shape extending toward the radially outer side from the nozzle hole side end portion of the connection portion42. In other words, the support portion43has a plate shape extending toward the radially outer side from the nozzle hole side end portion of the connection portion42, and has an annular shape extending around the axis line C. A surface of the support portion43on the side opposite to the nozzle hole functions as a support surface43afor supporting the nozzle hole-side end face of the second spring member SP2.

The second spring member SP2is a coiled spring disposed on the side opposite to the nozzle holes with respect to the support portion43, and is elastically deformed in the direction of the axis line C. An end face of the second spring member SP2on the side opposite to the nozzle hole is supported by the movable core30, specifically, the outer core31. A nozzle hole-side end face of the second spring member SP2is supported by the support portion43. The force generated by the elastic deformation of the second spring member SP2(the second elastic force) urges the outer core31toward the side opposite to the nozzle holes. With adjustment of the degree of press-fitting of the insertion cylindrical portion41in the direction of the axis line C, a magnitude of the second elastic force for urging the movable core30(a second set load) at the time of closing the valve is adjusted. The second set load related to the second spring member SP2is smaller than the first set load related to the first spring member SP1. Further, not only when the valve is closed, but also when the movable core30is urged in another situation, the magnitude of the second elastic force may be set as the second set load adjusted by the degree of press-fitting.

Description of Operation

Next, the operation of the fuel injection valve1will be described with reference toFIGS.4and5.

As shown in a column (a) ofFIG.4, in a state in which the coil17is de-energized, no magnetic attraction force is generated, so that the magnetic attraction force urged toward the valve opening side does not act on the movable core30. The cup50urged toward the valve closing side by the first elastic force generated by the first spring member SP1contacts the valve closing contact surface21bof the needle20(refer toFIG.3) and the inner cores32to transmit the first elastic force.

The movable core30is urged toward the valve closing side by the first elastic force of the first spring member SP1transmitted from the cup50, and the movable core30is urged toward the valve opening side by the second elastic force of the second spring member SP2. Since the first elastic force is larger than the second elastic force, the movable core30is pushed by the cup50and is moved (lifted down) toward the nozzle holes. The needle20is urged to the valve closing side by the first elastic force transmitted from the cup50, and is pushed by the cup50to move (lift down) to the nozzle hole side, that is, seated on the body-side seat11sto close the valve. In the valve closed state, a gap is provided between the valve opening contact surface21a(refer toFIG.3) of the needle20and the movable core30(inner core32), and a length of the gap in the direction of the axis line C in the valve closed state is referred to as a gap L1.

As shown in a column (b) ofFIG.4, in a state immediately after the energization of the coil17has been switched from OFF to ON, the magnetic attraction force urged to the valve opening side acts on the movable core30, and the movable core30starts moving to the valve opening side. Then, when the movable core30moves while pushing up the cup50and the amount of movement reaches the gap L1, the inner core32collides with the valve opening contact surface21aof the needle20. At the time of the collision, a gap is provided between the guide member60and the inner core32, and the length of the gap in the direction of the axis line C is referred to as a lift L2.

Since the elastic force of the first spring member SP1does not act on the needle20until the time of the collision, the collision speed of the movable core30can be increased accordingly. Since such a collision force is added to the magnetic attraction force and used as the valve opening force of the needle20, the needle20can be operated to open the valve even with a high-pressure fuel while inhibiting an increase in the magnetic attraction force required for opening the valve. The elastic force of the first spring member SP1acts on the needle20toward the valve closing side in the state shown in the column (a), but does not act on the needle20in the state shown in the column (b). For that reason, an inhibition of the increase in the magnetic attraction force required for opening the valve can be further promoted.

After the collision, the movable core30continues to move further by the magnetic attraction force, and when the movement amount after the collision reaches the lift L2, the inner core32collides with the guide member60and stops moving as shown in the column (c) ofFIG.4. A separation distance between the body-side seat11sand the valve body-side seat20sin the direction of the axis line C at the time of stopping the movement corresponds to a full lift of the needle20, and corresponds to the lift L2described above.

When the operation described above will be described in detail with reference toFIG.5, first, when the energization is switched on at a time t1as shown in the column (a) ofFIG.5, a drive current flowing through the coil17starts to rise (refer to the column (b)), and the magnetic attraction force starts to rise with the rising of the drive current (refer to the column (c)). When a value obtained by subtracting the second elastic force from the first elastic force (valve closing elastic force) is defined as an actual valve closing elastic force F0, the movable core30starts moving to the valve opening side at a time t2when the magnetic attraction force rises to the actual valve closing elastic force F0. Before the drive current reaches a peak value, the movable core30starts moving. A boost voltage obtained by boosting a battery voltage is applied to the coil17until the drive current reaches the peak value, and the battery voltage is applied to the coil17after the drive current has reached the peak value.

Thereafter, at a time t3when the moving amount of the movable core30reaches the gap L1, the movable core30collides with the needle20, and the needle20starts the valve opening operation (refer to a column (d)). As a result, the fuel is injected from the nozzle holes11a. Thereafter, the movable core30lifts up the needle20against the valve closing elastic force, and at a time t4when the movable core30collides with the guide member60, the lift of the needle20reaches the full lift (lift L2). A zero point shown on a vertical axis of the column (d) indicates a collision position between the movable core30and the needle20at the time t3.

Thereafter, a full lift state of the needle20is maintained by the magnetic attraction force, and the fuel injection is continued. Thereafter, when the energization is switched off at a time t5, the magnetic attraction force also decreases with a decrease in the drive current. At a time t6when the magnetic attraction force reaches the actual valve closing elastic force F0, the movable core30starts moving to the valve closing side together with the cup50. The needle20is pushed by a pressure of the fuel filled between the needle20and the cup50to start the lift-down operation (the valve closing operation) simultaneously with the start of the movement of the movable core30.

Thereafter, at a time t7when the needle20is lifted down by the lift L2, the valve body-side seat20sis seated on the body-side seat11sto close the flow channel11band the nozzle holes11a. Thereafter, the movable core30continues to move to the valve closing side together with the cup50, and the movement of the cup50to the valve closing side is stopped at a time t8when the cup50contacts the needle20. Thereafter, the movable core30continues to move to the valve closing side (inertial movement) by an inertial force, and then the movable core30moves (rebounds) to the valve opening side by the elastic force of the second spring member SP2. Thereafter, the movable core30collides with the cup50at a time t9and moves (rebounds) to the valve opening side together with the cup50, but is quickly pushed back by the valve closing elastic force and converges to an initial state shown in the column (a) ofFIG.4.

Therefore, the smaller such rebound and the shorter the time required for convergence, the shorter the time from the end of injection to the return to the initial state. For that reason, when the multi-stage injection in which the fuel is injected multiple times per one combustion cycle of the internal combustion engine is executed, an interval between the injections can be shortened, and the number of injections included in the multi-stage injection can be increased. In addition, when the convergence time is shortened as described above, the injection amount when a partial lift injection to be described below is executed can be controlled with a high accuracy. The partial lift injection is injection of a small amount due to a short valve opening time by stopping the energization of the coil17and starting the valve closing operation before the needle20performing the valve opening operation reaches the full lift position.

Description of Manufacturing Method

Next, a method of manufacturing the fuel injection valve1will be described.

This manufacturing method includes the first set load adjustment process, the movable portion assembling process, the welding process, the fastening process and the resin molding process described below.

In a movable portion manufacturing process, the movable core30, the second spring member SP2, the sleeve40, and the cup50are assembled to the needle20to manufacture the movable portion M. As will be described later in detail, the movable portion M is manufactured so that the elastic force of the second spring member SP2urged by the movable core30becomes a target value of the second set load.

In the welding process to be executed next, first, the nozzle hole body11is welded and joined to the main body12. Next, the movable portion M is disposed in the movable chamber12aof the main body12, and thereafter, the fixed core13to which the support member18and the first spring member SP1are assembled, the main body12to which the movable portion M is disposed, and the non-magnetic member14are welded and coupled to each other.

In the fastening process to be executed next, the bobbin17ain a state in which the coil17is wound is disposed between the nut member15and the fixed core13. Thereafter, the nut member15is fastened to the fixed core13so that the main body12, the non-magnetic member14, and the fixed core13are assembled by generating a surface pressure.

In the resin molding process to be executed next, the resin member16having the connector housing16ais resin molded by pouring and solidifying molten resin on the outer peripheral surface of the fixed core13.

In the first set load adjusting process to be performed thereafter, first, the first spring member SP1is assembled to the flow channel13aof the fixed core13. Thereafter, the support member18is press-fitted into the flow channel13aof the fixed core13to a predetermined position. The predetermined position of the press-fit may be determined in accordance with variations in the elastic modulus of the first spring member SP1and the length in the direction of the axis line C, and variations in the dimensions of the respective portions of the fixed core13. In any case, the predetermined position (press-fit position) is set so that the first elastic force urged by the needle20becomes a target value of the first set load. The fuel injection valve1is manufactured by the manufacturing method including the above processes.

Detailed Description of Configuration Group A

Next, among the configurations of the fuel injection valve1according to the present embodiment, a configuration group A including at least the press-fit portion23formed on the needle20and the configuration related to the press-fit portion23will be described in detail.

The movable portion assembling process described above includes Steps S10to S15shown in detail inFIG.6. First, in Step S10, as shown inFIG.7, the movable core30, the second spring member SP2, and the sleeve40are inserted into the needle20from the side (the lower end side) of the valve body-side seat20s. In this Step S10, as shown inFIG.8, the insertion of the sleeve40is stopped at a position of the outflow portion24in front of the press-fit portion23.

In the subsequent Step S11, the needle20is pressed against the cup50in a state in which the cup50is assembled to the contact portion21of the needle20, and the valve closing force transmission contact surface52ccontacts the valve closing contact surface21b(refer toFIG.8). As a result, the core contact end face51ais positioned closer to the nozzle hole than the valve opening contact surface21aby the amount corresponding to the gap L1.

In the subsequent Step S12, the sleeve40is temporarily press-fitted into the press-fit portion23by a predetermined degree of press-fitting. For example, while the cup50is supported in the direction of the axis line C with the use of a support device J1, the press-fit load F2is applied to the load application surface43bof the sleeve40in the direction of the axis line C with the use of the load application device J2. In a temporary press-fitting, the movable core30contacts the cup50, the second spring member SP2contacts the sleeve40and the movable core30, and the second spring member SP2is in an elastically deformed state. Therefore, the support device J1exhibits a reaction force F1against the second elastic force by the second spring member SP2to support the cup50.

The temporary press-fit is a first press-fit, and thereafter, a second press-fit (main press-fit) is performed in Step S15(to be described later). The degree of press-fitting in the temporary press-fit is a predetermined amount regardless of a machine difference variation, and for example, the temporary press-fit is performed to a position separated from the nozzle hole side end portion of the press-fit portion23toward the side opposite to the nozzle holes by a predetermined length in the direction of the axis line C.

In the subsequent Step S13, the second elastic force by the second spring member SP2, that is, the second set load is measured. For example, a force (reaction force F1) by which the support device J1is pushed by the second elastic force is measured with the use of a measurement device (not shown). In this Step S13, the measurement is performed in a state in which the cup50is positioned above the needle20, that is, in a state in which the direction of the movable portion M is set in the direction of an arrow indicating the vertical direction inFIG.8.

In the subsequent Step S14, a shortage amount of the measured second set load with respect to a target second set load is calculated, and an additional degree of press-fitting corresponding to the deficit amount is calculated. For example, an elastic modulus of the second spring member SP2may be measured in advance, and the additional degree of press-fitting may be calculated based on the measured load shortage amount and the elastic modulus. Alternatively, the elastic modulus of the second spring member SP2may be regarded as a standard value, and the additional degree of press-fitting may be calculated based on the measured load shortage amount and the standard value.

In the subsequent Step S15, the sleeve40is further press-fitted (main press-fitted) into the press-fit portion23by the additional degree of press-fitting calculated in Step S14. As described above, the assembling of the movable portion M is completed. In short, the second set load is measured during the press-fitting, and a main press-fit is executed in accordance with the measured value. Each step described above is an example of the configuration group A described above.

As described above, the fuel injection valve1according to the present embodiment includes the needle20(valve body), the fixed core13, the movable core30, the first spring member SP1, the sleeve40(fixed member), and the second spring member SP2. The movable core30contacts the needle20at a point in time when the movable core30is attracted by the fixed core13and moved by a predetermined amount to the side opposite to the nozzle holes, and opens the needle20. The first spring member SP1is elastically deformed accompanying the opening operation of the needle20, and exhibits the first elastic force for closing the needle20. The sleeve40is fixed to the needle20. The second spring member SP2is sandwiched between the sleeve40and the movable core30and elastically deformed, and exerts the second elastic force for urging the movable core30toward the side opposite to the nozzle hole. The needle20has the press-fit portion23into which the sleeve40is press-fitted into the side opposite to the nozzle holes, and the sleeve40is fixed to the needle20by being press-fit into the press-fit portion23.

In short, the fuel injection valve1according to the present embodiment has the core boost structure in which the fuel injection valve1contacts the needle20at the time when the movable core30is moved by a predetermined distance to the side opposite to the nozzle holes to open the fuel injection valve1, and includes the sleeve40that supports the second spring member SP2that urges the movable core30toward the side opposite to the nozzle holes. The sleeve40is fixed to the needle20by press-fitting the sleeve40, and the press-fitting direction of the sleeve40is the urging direction of the second spring member SP2. This makes it possible to adjust and fix the degree of press-fitting while measuring the second elastic force which increases with the progress of the press-fit. Therefore, the second elastic force at the time of completion of press-fitting can be set to the target set load of the second spring member SP2with a high accuracy.

The set load is a second elastic force exerted by the elastic deformation of the second spring member in a state in which the second spring member is assembled to the fuel injection valve. Since the magnitude of the set load affects the valve opening and closing timing of the valve body, setting the set load to the target value with a high accuracy contributes to a reduction of the variation in the fuel injection amount. In contrast to the present embodiment in which the fixed member is press-fitted into the valve body, when a structure in which the fixed member is welded and fixed to the valve body is employed, the welded portion cannot be adjusted while measuring the second elastic force. For that reason, the set load varies due to variations among individuals such as variations in machine difference of the second spring member and variations in valve body length, and also due to thermal strain caused by welding.

On the other hand, in the present embodiment, since the fixed member is press-fitted into the valve body, the set load can be set to the target value with a high accuracy as described above. This makes it possible to reduce the variation of the fuel injection amount while adopting the core boost structure.

Further, in the fuel injection valve1according to the present embodiment, at least a portion of the sleeve40which is in contact with the press-fit portion23has a hardness different from that of the press-fit portion23. For example, metal base materials having different hardness may be used for the sleeve40and the needle20, or a surface treatment such as a thermal treatment may be performed on the metal base material of the sleeve40to locally make a portion of the sleeve40which is in contact with the press-fit portion23higher in hardness than the sleeve40.

In contrast to the present embodiment, when the sleeve40and the press-fit portion23have the same hardness, there is a concern that the sleeve40and the press-fit portion23adhere to each other when the press-fit is temporarily stopped when the degree of press-fitting is adjusted while measuring. When the adhesion occurs, a load required to restart the press-fitting increases, and the workability of the press-fitting deteriorates. Therefore, according to the present embodiment having the different hardness, the above-mentioned adhesion concern can be reduced and the workability of press-fitting can be improved. The needle20is preferably harder than sleeve40. The sleeve40preferably has a higher hardness than that of the movable core30. A specific example of the material of the needle20is martensitic stainless steel. A specific example of the material of the sleeve40is ferritic stainless steel.

Further, in the fuel injection valve1according to the present embodiment, at least a portion of the sleeve40which is in contact with the press-fit portion23has a lower hardness than that of the press-fit portion23.

In press-fitting, at least one of the two members to be press-fitted needs to be plastically deformed. As the hardness is lower, the member is more easily plastically deformed, and the press-fit load required for press-fitting can be reduced. In view of the above circumstance, since the needle20requires hardness to withstand the collision with the body-side seat11s(valve seat), there is a fear that the press-fit load required for press-fitting may be increased if the sleeve40is made harder than the hardness of the needle20to produce a hardness difference. Therefore, according to the present embodiment in which the sleeve40has a hardness lower than that of the press-fit portion23, the above-mentioned concern can be inhibited to improve the press-fit workability. Further, since the sleeve40according to the present embodiment is not in contact with the movable core30, a material softer than that of the inner core32or the like requiring the contact can be employed.

For example, solid lines A1and A2inFIG.11shows stress σ strain L diagrams of the needle20and the sleeve40obtained by a tensile test, respectively. As shown in the test result, a stress at a yield point (yield stress σ1) at which the sleeve40starts plastic deformation is lower than that of the needle20. In the case of the needle20, a test sample has broken as soon as the yield stress has been reached. The test result indicates that the yield stress al can be lowered by making the sleeve40low in hardness, and the press-fit load required for press-fitting can be lowered.

Further, in the fuel injection valve1according to the present embodiment, the sleeve40and the movable core30are separated from each other without contacting each other even when the movable core30is moved to the maximum relative movement toward the nozzle holes with respect to the needle20. For example, the movable core30moves further to the nozzle hole side after the valve has been closed, and rebound occurs as described above. A state in which the further movement of the movable core30after the closing of the valve occurs, and an interval between the lines of the second spring member SP2becomes zero, so that the elastic deformation amount of the second spring member SP2becomes maximum, is exemplified as a specific example of a case in which the relative movement is maximized.

In contrast to the present embodiment, in a structure in which the sleeve40and the movable core30are in contact with each other, since there is a need to strengthen the press-fit of the sleeve40, there is a need to set a large press-fit margin and increase the amount of plastic deformation caused by the press-fit. Therefore, according to the present embodiment of the structure in which the sleeve40and the movable core30do not contact each other, the necessity of strengthening the press-fit can be reduced, so that the press-fit load required for the press-fit can be reduced, and the workability of the press-fit can be improved.

Further, in the fuel injection valve1according to the present embodiment, the sleeve40has the insertion cylindrical portion41having the cylindrical shape inserted into the press-fit portion23, and the inner peripheral surface41aof the insertion cylindrical portion41is press-fitted into the outer peripheral surface of the press-fit portion23over the entire circumference. According to the above configuration, since the internal stress generated in the insertion cylindrical portion41can be dispersed over the entire circumference, damage to the sleeve40due to concentration of the internal stress can be reduced.

In the method of manufacturing the fuel injection valve1according to the present embodiment, the fuel injection valve1having the following structure is to be manufactured. In other words, the needle20(valve body) that opens and closes the nozzle holes11afor injecting the fuel is operated to close the valve by the first elastic force generated by the first spring member SP1that is elastically deformed and exhibited, and is operated to open the valve by the movable core30that are moved by the magnetic attraction force. In addition, the movable core30is urged to the side opposite to the nozzle holes by the second elastic force generated by the second spring member SP2elastically deformed by being sandwiched between the sleeve40(fixed member) fixed to the needle20and the movable core30. The above manufacturing method includes Steps S12and S15(press-fitting process) of press-fitting the sleeve40(fixed member) into the press-fit portion23of the needle20that presses-fit the sleeve40into the press-fit portion23formed in the needle20that contacts the movable core30and starts the valve opening operation when the movable core30is moved by a predetermined amount by the magnetic attraction force. In addition, the above manufacturing method includes Step S13(load measurement process) of measuring the second elastic force in a state in which the movable core30is made immovable during the press-fitting. In the press-fitting process, the degree of press-fitting is adjusted based on the measurement result to complete the press-fit.

In short, in the manufacturing method according to the present embodiment, the fuel injection valve1having the core boosting structure, which includes the sleeve40supporting the second spring member SP2for urging the movable core30toward the side opposite to the nozzle holes is to be manufactured. While the sleeve40is press-fitted into the press-fit portion23of the needle20, the second elastic force is measured while the movable core30is not moved, and the amount of press-fit is adjusted based on the measurement result to complete the press-fit. Therefore, the second elastic force at the time of completion of press-fitting can be set to the target set load of the second spring member SP2with a high accuracy.

As described above, since the magnitude of the set load influences the valve opening and closing timing of the needle20, setting the set load to the target value with a high accuracy contributes to the reduction of a variation in the fuel injection amount. For that reason, according to the present embodiment in which the set load can be set to the target value with a high accuracy as described above, the variation of the fuel injection amount can be reduced while employing the core boost structure.

Further, in the manufacturing method according to the present embodiment, the next fuel injection valve1is to be manufactured. The fuel injection valve1is disposed so as to be movable relative to the needle20, and includes the cup50that contacts the needle20by moving relative to the fuel nozzle holes and transmits the first elastic force from the first spring member SP1to the needle20. In the manufacturing method described above, in Step S13(load measurement process), the cup50is relatively moved to contact the needle20, and the cup50in the contacting state is in contact with the movable core30, thereby regulating the movement of the movable core30.

The magnitude of the second set load due to the second spring member SP2is important for inhibiting the movable core30from moving toward the nozzle hole after the valve has been closed, that is, important for quickly converging the rebound. Therefore, setting the second elastic force in the valve closed state as the second set load is advantageous for managing the rebound convergence. Therefore, since the second elastic force is measured by regulating the movement of the movable core30by contacting the cup50, which contacts the needle20, on the movable core30, the second elastic force in the valve closed state is measured. This makes it possible to easily manage the rebound convergence.

Detailed Description of Configuration Group B

Next, among the configurations of the fuel injection valve1according to the present embodiment, a configuration group B including at least the fuel storage chamber B1, which will be described below, and the configuration related to the fuel storage chamber B1will be described in detail with reference toFIGS.12to14. In addition, a modification of the configuration group B will be described later with reference toFIGS.15to23.

As shown inFIG.12, the fuel storage chamber B1is a portion in which the fuel is accumulated in a state surrounded by the movable core30, the cup50, and the needle20. In the following description, a surface of the inner core32on the side opposite to the nozzle hole, which contacts the needle20, is referred to as a first core contact surface32c, a surface of the inner core32, which contacts the cup50, is referred to as a second core contact surface32b, and a surface of the inner core32, which contacts the guide member60, is referred to as a third core contact surface32d.

Since the movable core30is urged to the cup50by the second elastic force, the movable core30is always in contact with the cup50except when the movable core30is inertially moved after the valve is closed and separated from the cup50. More specifically, the second core contact surface32bof the inner core32is always in contact with the core contact end face51aof the cup50. The cylindrical portion51of the cup50, which forms the core contact end face51a, separates the inside and the outside of the fuel storage chamber B1from each other. The outside is a region where the fuel exists radially outside the outer peripheral surface51dof the cup50, the first core contact surface32cis located inside the fuel storage chamber B1, and the third core contact surface32dis located outside the fuel storage chamber B1.

The fuel storage chamber B1is a region surrounded by the outer peripheral surface of the core sliding portion22of the needle20, the valve opening contact surface21a, the inner wall surface of the through hole32aof the inner core32, the first core contact surface32c, and the inner peripheral surface of the cylindrical portion51of the cup50. The fuel storage chamber B1is a region surrounded as described above in a state in which the movable core30and the cup50contact each other. The fuel storage chamber B1is a region surrounded as described above in a state in which the valve body-side seat20scontacts the body-side seat11sand the needle20is closed.

Communication grooves32eare provided in the first core contact surface32cand the second core contact surface32bof the inner core32. The communication grooves32ecommunicate the inside and the outside of the fuel storage chamber B1with each other in a state in which the second core contact surface32bcontacts the core contact end face51a. The outside is a space different from the fuel storage chamber B1when the cup50and the movable core30contact each other.

Here, the outside of the fuel storage chamber B1corresponds to a region which will be exemplified below. In other words, a first region between the stopper contact end face61aand the third core contact surface32dof the guide member60corresponds to an outside. The first region is a region formed in a state in which the cup50and the movable core30contact each other and the movable core30and the guide member60do not contact each other. A surface of the fixed core13facing the movable core30is referred to as a fixed side core facing surface13b. A surface of the outer core31facing the fixed core13is referred to as a movable core facing surface31c. A second region between the fixed side core facing surface13band the movable core facing surface31c, which is a region communicating with the first region, corresponds to the outside. A third region, which communicates with the second region, between the inner peripheral surfaces of the main body12(holder) and the non-magnetic member14(holder) and the outer peripheral surface of the outer core31corresponds to the outside.

As shown inFIG.13, the multiple (for example, four) communication grooves32eare provided, and the multiple communication grooves32eare arranged at regular intervals in the circumferential direction when viewed from the moving direction of the movable core30. The communication grooves32eeach have a shape linearly extending in the radial direction. Each of the multiple communication grooves32ehas the same shape. Positions in the circumferential direction of the communication grooves32eare different from positions in the circumferential direction of the through holes31a.

The inner core32corresponds to a “contact portion” in which the first core contact surface32cand the second core contact surface32bare formed. The outer core31corresponds to a “core body portion” made of a material different from that of the inner core32on which the movable core facing surface31cfacing the fixed core13is formed. The core body portion is outside a range in which the communication grooves32eextend. In other words, the communication grooves32eare provided in the inner core32but are not provided in the outer core31.

The communication grooves32eare provided over the entire area in the radial direction of the inner core32, and are provided over the inner peripheral surface to the outer peripheral surface of the inner core32. In other words, the communication grooves32eare provided over the entire area in the radial direction of the first core contact surface32c, the second core contact surface32b, and the third core contact surface32d.

As shown inFIG.14, the communication grooves32eeach have a bottom wall surface32e1, a vertical wall surface32e2, and a tapered surface32e3. The bottom wall surface32e1has a shape extending perpendicularly to the moving direction of the movable core30, the vertical wall surface32e2has a shape extending from the bottom wall surface32e1in the moving direction of the movable core30, and the tapered surface32e3has a shape extending from the vertical wall surface32e2toward the groove opening32e4while increasing a flow area. In an example shown inFIG.14, the tapered surface32e3has a shape linearly extending from an upper end of the vertical wall surface32e2.

Examples of the method of machining the communication grooves32einclude laser machining, electric discharge machining, cutting with an end mill, and the like. First, a groove having a rectangular cross-sectional shape including the vertical wall surface32e2and the bottom wall surface32e1is processed. At this point of time, a burr generated at the time of processing may remain in the peripheral portion of the groove opening32e4in the vertical wall surface32e2. After that, however, the tapered surface32e3having a trapezoidal cross-sectional shape is processed to remove the burr.

Now, when the fuel existing in the fuel storage chamber B1is compressed as the movable core30moves to the side opposite to the nozzle holes, the movement of the movable core30is hindered, so that the moving speed (collision speed) when the movable core30moves by a predetermined amount and contacts the needle20becomes low. As a result, the above-mentioned effect of the core boost structure, that is, the effect that the valve body can be operated to open even with the high-pressure fuel while reducing an increase in the magnetic attraction force required to open the valve, is reduced. In addition, since the movement of the movable core30is obstructed, a variation in the valve opening timing of the needle20becomes large, and a variation in the fuel injection amount becomes large.

On the other hand, the fuel injection valve1according to the present embodiment includes the needle20(valve body), the fixed core13, the movable core30, the first spring member SP1(spring member), and the cup50(valve closing force transmission member). The movable core30contacts the needle20at a point in time when the movable core30is attracted by the fixed core13and moved by a predetermined amount to the side opposite to the nozzle holes, and opens the needle20. The first spring member SP1is elastically deformed accompanying the valve opening operation of the needle20, and exhibits a valve closing elastic force for closing the needle20. The cup50is disposed so as to be movable relative to the needle20, and when the cup50is moved relative to the nozzle hole side, the cup50contacts the needle20to transmit the valve closing elastic force to the needle20. The movable core30has the first core contact surface32cand the second core contact surface32b, and the communication grooves32eare provided in the first core contact surface32cand the second core contact surface32bto communicate the inside and the outside of the fuel storage chamber B1with each other.

For that reason, when the movable core30moves to the side opposite to the nozzle holes, the fuel accumulated in the fuel storage chamber B1flows out to the outside through the communication grooves32e. Therefore, the compression of the fuel accumulated in the fuel storage chamber B1is inhibited, so that the movable core30easily moves. For that reason, the reduction in the collision speed of the movable core30can be inhibited, so that the effect of reducing the magnetic attraction force by the core boost structure can be promoted. In addition, since the movable core30easily moves, the variation in the valve opening timing of the needle20can be reduced, and consequently, the variation in the fuel injection amount can be reduced.

Further, in the fuel injection valve1according to the present embodiment, the multiple communication grooves32eare provided, and the multiple communication grooves32eare arranged at regular intervals in the circumferential direction when viewed from the moving direction of the movable core30.

According to the above configuration, the portions that easily flow out from the fuel storage chamber B1to the outside are present at regular intervals around the axial direction. For that reason, when the movable core30moves in the axial direction, a change in the inclination direction of the movable core30with respect to the axial direction can be reduced. Therefore, since the behavior of the movable core30can be inhibited from becoming unstable, the variation in the valve opening response can be further reduced. If three or more communication grooves32eare provided at regular intervals in the circumferential direction, the effect of inhibiting the behavior instability is promoted.

Further, in the fuel injection valve1according to the present embodiment, the movable core30includes the inner core32(contact portion) and the outer core31(core body portion) made of a material different from that of the inner core32. The inner core32is formed with the first core contact surface32cand the second core contact surface32b, and the outer core31is formed with the movable core facing surface31cfacing the fixed core13. The outer core31is excluded from a range in which the communication grooves32eare provided.

According to the above configuration, since the movable core facing surface31cof the outer core31can have a flat shape having no groove, the magnetic attraction force attracted to the fixed core13can be inhibited from being reduced by the communication grooves.

Further, in the fuel injection valve1according to the present embodiment, the third core contact surface32dof the movable core30which contacts the guide member60is located outside the fuel storage chamber B1. The communication grooves32eare also provided in the third core contact surface32din addition to the first core contact surface32cand the second core contact surface32b.

When the needle20is in the full lift position, the inner core32contacts the guide member60. In the above contact state, if the stopper contact end face61aof the guide member60and the third core contact surface32dof the inner core32are in close contact with each other, there is a concern that a phenomenon (linking phenomenon) occurs in which the third core contact surface32dis hardly separated from the stopper contact end face61a. In view of the above concern, in the present embodiment, since the communication grooves32eare also provided in the third core contact surface32d, when the movable core30starts moving to the nozzle hole side with the energization off, the fuel is supplied to the third core contact surface32din a state of contacting the stopper contact end face61a. For that reason, since the movable core30can be inhibited from coming into close contact with the guide member60and from becoming difficult to separate from the guide member60, the possibility that the start of the movement of the movable core30to the nozzle hole side is delayed due to the above-mentioned force of adhesion can be reduced. Therefore, a valve closing response time from when the energization is turned off to when the needle20closes the valve can be reduced, and the valve closing response can be improved.

Further, in the fuel injection valve1according to the present embodiment, the communication grooves32eeach have the bottom wall surface32e1extending perpendicularly to the moving direction of the movable core30, and the vertical wall surface32e2extending from the bottom wall surface32e1in the moving direction.

In order to remove burrs generated in the groove opening32e4of the communication grooves32e, it is desirable to polish the first core contact surface32cand the second core contact surface32b. For example, polishing is performed from a position indicated by a two-dot chain line inFIG.14to a position indicated by a solid line. In the present embodiment, after the inner core32has been assembled to the outer core31, the communication grooves32eand outer communication grooves31eare provided by cutting or the like, and thereafter, the above-mentioned polishing is performed on both the outer core31and the inner core32simultaneously.

Contrary to the present embodiment, in the case where the vertical wall surface32e2is not provided and the shape is shown by a one-dot chain line, a cross-sectional area of the communication grooves32ebecomes small, and a ratio of the cross-sectional area to be polished to the cross-sectional area of the communication grooves32ebecomes large. As a result, an influence of the variation in the polishing depth on the cross-sectional area of the communication grooves32ebecomes large, so that the variation in the cross-sectional area of the communication grooves32ebecomes large. For that reason, a variation in the degree of the fuel flowing out from the fuel storage chamber B1to the outside through the communication grooves32ebecomes large, and a variation in the ease of movement of the movable core30becomes large, which hinders a reduction of the variation in the valve opening timing of the needle20. On the other hand, according to the present embodiment, since the vertical wall surface32e2is provided, the ratio of the cross-sectional area to be polished becomes small, and the influence of the variation in a polishing depth on the cross-sectional area of the communication grooves32ebecomes small. For that reason, the variation in the degree of outflow of the fuel from the fuel storage chamber B1to the outside through the communication grooves32eis reduced, and the variation in the valve opening timing of the needle20can be promoted.

Although the communication grooves32eshown inFIG.12are not provided in the outer core31, as shown inFIG.15, in addition to the communication grooves32eprovided in the inner core32, communication grooves (outer communication grooves31e) may be provided in the outer core31. In an example shown inFIG.15, the inner diameter side end portion of the outer communication grooves31edirectly communicates with the outer diameter side end portion of the communication grooves32e.

As shown inFIG.16, the multiple (for example, four) outer communication grooves31eare provided and the multiple outer communication grooves31eare arranged at regular intervals in the circumferential direction when viewed from the moving direction of the movable core30. The outer communication grooves31eeach have a shape linearly extending in the radial direction. Each of the multiple outer communication grooves31ehas the same shape. The position of the outer communication grooves31ein the circumferential direction is different from the position of the through holes31ain the circumferential direction.

The outer communication grooves31eand the communication grooves32ehave the same position in the circumferential direction. In an example ofFIG.16, four outer communication grooves31eare arranged at regular intervals in the circumferential direction, but six outer communication grooves31emay be arranged at regular intervals in the circumferential direction. In that case, it is desirable to set the position of the through holes31ain the circumferential direction so that a circumferential distance to the adjacent outer communication grooves31eis the same.

The outer communication grooves31eare provided over the entire area of the outer core31in the radial direction, and is provided from the inner peripheral surface to the outer peripheral surface of the outer core31. In other words, the outer communication grooves31eare provided over the entire area of the movable core facing surface31cin the radial direction. The cross-sectional shape of the outer communication grooves31eis the same as the cross-sectional shape of the communication grooves32eshown inFIG.14, and the outer communication grooves31ehave the same bottom wall surface, vertical wall surface, and tapered surface as those of the communication grooves32e. As described above,FIG.14is a sectional view taken along a line XIV-XIV ofFIG.13, and shows the cross-sectional shape of the communication groove32eextending in the radial direction of the movable core30, which are taken perpendicularly to the extending direction. The cross-sectional shape of the outer communication grooves31eis the same as that of the communication grooves32e, and the cross-sectional shape has a bottom wall surface, a vertical wall surface, and a tapered surface in a cross-section of the outer communication grooves31etaken perpendicularly to the extending direction.

As described above, according to the present modification having the outer communication grooves31e, since the fuel flowing out from the outer diameter side end portion of the communication grooves32eis diffused through the outer communication grooves31e, an increase in a fuel pressure at the outer diameter side end portion of the communication grooves32ecan be inhibited, and the fuel flowing out through the communication grooves32ecan be promoted. This makes it possible to inhibit an increase in the fuel pressure between the guide member60and the inner core32.

Further, in the present modification, since the inner diameter side end portion of the outer communication grooves31edirectly communicates with the outer diameter side end portion of the communication grooves32e, the outflow of the fuel from the outer diameter side end portion can be further promoted.

Further, in the present modification, since the outer communication grooves31eare provided over the entire area of the movable core facing surface31cin the radial direction, the fuel flowing out from the outer diameter side end portion of the outer communication grooves31edirectly flows into the gap between the inner peripheral surface of the holder and the outer peripheral surface of the outer core31. For that reason, an increase in the fuel pressure at the outer diameter side end portion of the outer communication grooves31ecan be inhibited, and the fuel outflow through the communication grooves32eand the outer communication grooves31ecan be promoted.

Further, in the present modification, with respect to the dimension of the outer communication grooves31e, a width dimension (dimension in circumferential direction) of a portion of the outer communication grooves31ewhich opens toward the fixed core13is set to be smaller than a depth dimension (dimension in the axis line C) of the outer communication grooves31e. According to the above configuration, the flow channel cross-sectional area of the outer communication grooves31ecan be increased while a decrease in the area of the movable core facing surface31ccaused by the provision of the outer communication grooves31ecan be inhibited. The “flow channel cross-sectional area” is an area of a cross section perpendicular to the flow direction when the fuel in the fuel storage chamber B1flows radially outward through the outer communication grooves31e. In other words, since the width dimension is smaller than the depth dimension as described above, the fuel discharge from the fuel storage chamber B1at the time of the valve opening operation can be realized while inhibiting the reduction of the magnetic attraction force.

In the present modification shown inFIGS.17and18, a connection groove32ffor connecting the multiple communication grooves31eis provided. The connection groove32fhas a shape extending annularly around the through hole32a, and connects all (four in an example ofFIG.18) communication grooves31eto each other. The connection groove32fconnects the outer diameter side end portion of the communication grooves31e. The connection groove32fis provided by cutting the outer diameter side corner portion of the inner core32. Further, the inner diameter side corner portion of the outer core31is cut so that the connection groove32fis provided to extend over both the outer core31and the inner core32.

Also, in the embodiment shown inFIGS.15and16, the connection groove32fshown inFIGS.17and18may be provided, and each of the multiple communication grooves32eand the multiple outer communication grooves31emay be connected to each other by the connection groove32f.

As described above, according to the present modification having the connection groove32f, since the fuel flowing out from the outer diameter side end portion of the communication grooves32eis diffused through the connection groove32f, an increase in the fuel pressure at the outer diameter side end portion of the communication grooves32ecan be inhibited, and the fuel flowing out through the communication grooves32ecan be promoted.

Further, with the connection of the multiple communication grooves31e, since the fuel can be promoted to flow out uniformly from the multiple communication grooves31e, a change in the inclination direction of the movable core30with respect to the axial direction can be inhibited when the movable core30moves in the axial direction. Therefore, since the behavior of the movable core30can be inhibited from becoming unstable, the variation in the valve opening response can be further reduced.

The communication grooves32eshown inFIG.12are formed over the entire end face of the inner core32. On the other hand, communication grooves32gaccording to the present modification shown inFIGS.19and20are provided across a part of the first core contact surface32c, the entire area of the second core contact surface32b, and a part of the third core contact surface32d. More specifically, the communication grooves32gare not provided over the entire area of the first core contact surface32cin the radial direction, but are partially provided in a portion of the first core contact surface32cwhich is adjacent to the second core contact surface32b. The communication grooves32gare provided over the entire area of the second core contact surface32bin the radial direction. The communication grooves32gare not provided over the entire area of the third core contact surface32din the radial direction, and are partially provided in a portion of the third core contact surface32dwhich is adjacent to the second core contact surface32b.

The communication grooves32eshown inFIG.12have a shape linearly extending in the radial direction, whereas the communication grooves32gaccording to the present modification have a conical shape. In other words, as shown inFIG.20, the communication grooves32gare circular as seen from the direction of the axis line C, and as shown inFIG.19, the communication grooves32gare triangular in sectional view.

As described above, according to the present modification having the conical communication grooves32g, the communication grooves32gcan be provided only by pressing a tip of a drill blade against the movable core30, and therefore the communication grooves32gcan be easily processed.

In the embodiment shown inFIG.12, the communication grooves32eare provided in the contact surface of the movable core30, so that the inside and the outside of the fuel storage chamber B1communicate with each other. On the other hand, in the present modification shown inFIG.21, with the provision of communication holes20cin the needle20, the interior of the fuel storage chamber B1and the internal passage20aof the needle20are communicated with each other.

In a state in which the cup50contacts the valve closing contact surface21band in a state in which the cup50contacts the second core contact surface32b, the communication holes20care disposed at a position including the first core contact surface32cin the direction of the axis line C. Alternatively, the entirety of the communication holes20cis disposed on the side opposite to the nozzle holes with respect to the first core contact surface32c. The multiple communication holes20care provided, and the multiple communication holes20care arranged at regular intervals in the circumferential direction when viewed from the moving direction of the needle20. The communication holes20chave a shape linearly extending in the radial direction of the needle20.

As described above, according to the present modification in which the communication holes20care provided in the needle20, when the movable core30moves to the side opposite to the nozzle holes, the fuel accumulated in the fuel storage chamber B1flows out to the internal passage20a(the outside) of the needle20through the communication holes20c. Therefore, the compression of the fuel accumulated in the fuel storage chamber B1is inhibited, so that the movable core30easily moves. For that reason, the reduction in the collision speed of the movable core30can be inhibited, so that the effect of reducing the magnetic attraction force by the core boost structure can be promoted. In addition, since the movable core30easily moves, the variation in the valve opening timing of the needle20can be reduced, and consequently, the variation in the fuel injection amount can be reduced.

In the present modification shown inFIG.22, sliding surface communication grooves20dare provided in the needle20, so that the interior of the fuel storage chamber B1and the internal passage20aof the needle20communicate with each other. The sliding surface communication grooves20dare provided in the valve body-side sliding surface21c(refer toFIG.7) of the needle20on which the cup50slides.

The multiple sliding surface communication grooves20dare provided, and the multiple sliding surface communication grooves20dare arranged at regular intervals in the circumferential direction when viewed from the moving direction of the needle20. The sliding surface communication grooves20deach have a shape linearly extending in the direction of the axis line C of the needle20.

As described above, according to the present modification in which the sliding surface communication grooves20dare provided in the valve body-side sliding surface21cwhich is the sliding surface between the needle20and the cup50, when the movable core30moves to the side opposite to the nozzle holes, the fuel accumulated in the fuel storage chamber B1flows out to the outside through the sliding surface communication grooves20d. In the present specification, the outside is a gap between the valve closing contact surface21band the valve closing force transmission contact surface52c, and the internal passage20a. Therefore, the compression of the fuel accumulated in the fuel storage chamber B1is inhibited, so that the movable core30easily moves. For that reason, the reduction in the collision speed of the movable core30can be inhibited, so that the effect of reducing the magnetic attraction force by the core boost structure can be promoted. In addition, since the movable core30easily moves, the variation in the valve opening timing of the needle20can be reduced, and consequently, the variation in the fuel injection amount can be reduced.

In the present modification shown inFIG.23, second sliding surface communication grooves32hare provided in the inner core32, so that the inside of the fuel storage chamber B1and the movable chamber12aare communicated with each other. The second sliding surface communication grooves32hare provided on the surface of the inner core32on which the needle20slides, that is, on the inner peripheral surface of the inner core32.

The multiple second sliding surface communication grooves32hare provided, and the multiple second sliding surface communication grooves32hare arranged at regular intervals in the circumferential direction when viewed from the moving direction of the movable core30. The second sliding surface communication grooves32heach have a shape linearly extending in the direction of the axis line C of the movable core30.

As described above, according to the present modification in which the second sliding surface communication grooves32hare provided on the sliding surface between the needle20and the inner core32, when the movable core30moves to the side opposite to the nozzle holes, the fuel accumulated in the fuel storage chamber B1flows out to the movable chamber12a(the outside) through the second sliding surface communication grooves32h. Therefore, the compression of the fuel accumulated in the fuel storage chamber B1is inhibited, so that the movable core30easily moves. For that reason, the reduction in the collision speed of the movable core30can be inhibited, so that the effect of reducing the magnetic attraction force by the core boost structure can be promoted. In addition, since the movable core30easily moves, the variation in the valve opening timing of the needle20can be reduced, and consequently, the variation in the fuel injection amount can be reduced.

Detailed Description of Configuration Group C

Next, among the configurations of the fuel injection valve1according to the present embodiment, a configuration group C including at least a supply flow channel to be described below and a configuration related to the supply flow channel will be described in detail with reference toFIGS.24to26and12. In addition, a modification of the configuration group C will be described later with reference toFIGS.27to35.

As shown inFIG.24, main flow channels20ehaving grooves are provided in the valve closing contact surface21bof the needle20. As shown inFIG.25, the valve closing contact surface21bis formed in a region extending annularly as seen from the moving direction of the movable core30, and the main flow channels20eare each shaped to extend so as to connect an annular inner side and an annular outer side across an annular region in which the valve closing contact surface21bis formed. The main flow channels20eeach have a straight portion201extending linearly when viewed from the moving direction of the movable core. In the case of the present embodiment, the whole of the main flow channels20ematches the whole of the straight portion201.

The annular inner side corresponds to an internal passage20aof the needle20. The annular outer side corresponds to a gap B2(refer toFIG.12) between the inner surface of the cup50and the outer surface of the needle20, which is provided in a state in which the valve closing contact surface21bcontacts the cup50. Therefore, the main flow channels20ecommunicate the internal passage20aof the needle20with the gap B2in a state in which the valve closing contact surface21bcontacts the cup50.

The main flow channels20e(supply flow channels) each have a shape extending so as to connect an inner peripheral surface of the needle20that defines the internal passage20aand an outer peripheral surface of the needle20. The outer peripheral surface of the needle20functions as a wall surface of a passage through which the fuel flows through the nozzle holes11a. The fuel flowing through the passage provided by the gap between the outer peripheral surface of the needle20and the inner peripheral surface of the cylindrical portion51flows into the fuel storage chamber B1. Thereafter, the fuel flows into the movable chamber12athrough a gap between the inner peripheral surface of the movable core30and the outer peripheral surface of the needle20and a gap between the outer peripheral surface of the movable core30and the inner peripheral surface of the main body12, and flows into the nozzle holes11athrough the flow channel12b.

As shown inFIG.25, an inner peripheral edge portion201aand an outer peripheral edge portion201bof the valve closing contact surface21bin the needle20are chamfered. The main flow channels20e(supply flow channels) each have a shape connecting the inner peripheral edge portion201aand the outer peripheral edge portion201b.

As shown inFIG.25, a plurality of (e.g., four) main flow channels20eare provided, and the multiple main flow channels20eare arranged at regular intervals in the circumferential direction when viewed from the moving direction of the movable core30. In other words, the multiple main flow channels20eare arranged at regular intervals in the circumferential direction on the valve closing contact surface21bof the needle20. The main flow channels20eeach have a shape linearly extending in the radial direction. Each of the multiple main flow channels20ehas the same shape. As shown inFIG.26, the cross section of the straight portion201of the main flow channels20ehas a shape having an arc-shaped bottom surface convex toward the nozzle hole side. Corner portions of the outer peripheral portion and the inner peripheral portion of the contact portion21of the needle20are chamfered, and the outer peripheral portion and the inner peripheral portion of the contact portion21are formed in a tapered shape.

A depth dimension201hof the main flow channels20eis defined as a dimension of the main flow channels20ein the direction of the axis line C, and a width dimension201wof the main flow channels20eis defined as a dimension of the needle20around the direction of the axis line C (refer toFIG.24). The depth dimension201hof the main flow channels20eis set to be larger than the width dimension201wof the main flow channels20e.

Now, in the case of the core boost structure in which the cup50contacts the needle20at the time when the movable core30starts to move together with the cup50by a predetermined amount by the start of energization of the coil, the following concern arises. In other words, if the cup50and the needle20are in close contact with and contacts each other, a phenomenon that the cup50is difficult to separate from the needle20(linking phenomenon) occurs, as a result of which, the start of the movement of the movable core30by a predetermined amount is delayed, which leads to a concern that the valve opening response is deteriorated.

To cope with the above concern, the present embodiment includes the needle20(valve body), the fixed core13, the movable core30, the first spring member SP1(spring member), and the cup50(valve closing force transmission member). When the movable core30is attracted by the fixed core13and moved by a predetermined amount, the movable core30contacts the valve opening contact surface21a, which is formed on the needle20, and operates the needle20to open the valve. The first spring member SP1is elastically deformed accompanying the valve opening operation of the needle20, and exhibits a valve closing elastic force for closing the needle20. The cup50contacts the valve closing contact surface21bformed on the needle20, and transmits the valve closing elastic force to the needle20. When the movable core30starts to move together with the cup50by the predetermined amount, the cup50contacts the valve closing contact surface21b. The needle20has the main flow channels20e(supply flow channels) for supplying the fuel to the valve closing contact surface21bin a state of contacting the cup50.

Therefore, when the movable core30starts to move by the predetermined amount, the fuel is supplied to the valve closing contact surface21bin a state in which the movable core30contacts the cup50. For that reason, since the cup50can be inhibited from coming into close contact with the needle20and becoming difficult to separate from the needle20, the possibility that the start of the movement of the movable core30by the predetermined amount is delayed due to the above-mentioned force of close contact can be reduced. Therefore, the valve opening response time from the start of the energization of the coil17to the start of the valve opening of the needle20can be shortened, and the valve opening response can be improved. In addition, the variation in the valve opening timing due to the obstruction of the movement of the movable core30can be reduced, and the variation in the fuel injection amount can be reduced.

Further, in the fuel injection valve1according to the present embodiment, the main flow channels20e(supply flow channels) are provided by the grooves provided in the valve closing contact surface21bof the needle20. For that reason, the processing of the supply flow channels can be simplified and the supply flow channels can be easily provided as compared with the case where the through holes as the supply flow channels are provided in the needle20or the cup50.

Further, in the fuel injection valve1according to the present embodiment, the valve closing contact surface21bis formed in a region extending annularly as viewed from the moving direction of the movable core30, and the supply flow channels have the main flow channels20eextending so as to connect the annular inner side and the annular outer side across the region. For that reason, the fuel is supplied from both sides of the annular inner side and the annular outer side to the valve closing contact surface21b, so that the reduction of the linking phenomenon due to the above-mentioned close contact can be promoted.

Further, in the fuel injection valve1according to the present embodiment, the multiple main flow channels20eare provided, and the multiple main flow channels20eare arranged at regular intervals in the circumferential direction when viewed from the moving direction of the movable core30. According to the above configuration, the portions where a force of the cup50coming into close contact with the needle20is alleviated exist at regular intervals around the axial direction. For that reason, when the movable core30starts to move by the predetermined amount in the axial direction, the inclination direction of the movable core30with respect to the axial direction can be inhibited from changing. Therefore, since the behavior of the movable core30can be inhibited from becoming unstable, the variation in the valve opening response can be further reduced. If three or more main flow channels20eare provided at regular intervals in the circumferential direction, the effect reducing the behavior instability is promoted.

In this example, when the depth dimension201hof the main flow channels20eis excessively small, if the flow channel cross-sectional area of the main flow channels20ebecomes small as the wear of the valve closing contact surface21bprogresses, the flow rate of the fuel flowing through the main flow channels20ecannot be sufficiently ensured. Further, when the width dimension201wof the main flow channels20eis excessively large, the surface pressure when the cup50is pressed against the needle20by the valve closing elastic force becomes excessively large, and the pressure receiving area of the valve closing contact surface21bcannot be sufficiently secured. As a result, the progress of wear of the valve closing contact surface21bis accelerated.

In view of the above points, in the fuel injection valve1according to the present embodiment, the depth dimension201hof the main flow channels20eis set to be larger than the width dimension201wof the main flow channels20e. For that reason, the flow rate of the fuel flowing through the main flow channels20ecan be sufficiently ensured, and the progress of the wear of the valve closing contact surface21bdue to the excessive surface pressure can be inhibited.

In the present modification, the cross-sectional shape of the main flow channels20eis modified. In other words, the straight portion201of the main flow channels20eshown inFIG.26has a cross-sectional shape having an arc-shaped bottom surface. Alternatively, the straight portion201may have a triangular cross-sectional shape as shown inFIG.27, or may have a rectangular cross-sectional shape as shown inFIG.28.

As shown inFIG.29, the straight portion201may have a cross-sectional shape combining a rectangle with a trapezoid. Specifically, the main flow channels20eeach have a bottom wall surface20e1, a vertical wall surface20e2, and a tapered surface20e3. The bottom wall surface20e1has a shape extending perpendicularly to the moving direction of the movable core30, the vertical wall surface20e2has a shape extending from the bottom wall surface20e1in the moving direction, and the tapered surface20e3has a shape extending from the vertical wall surface20e2toward a groove opening20e4while increasing the flow area. In an example shown inFIG.29, the tapered surface20e3has a shape linearly extending from an upper end of the vertical wall surface20e2.

As a machining method of the main flow channels20eshown inFIG.29, laser machining, electric discharge machining, cutting machining by an end mill, and the like are exemplified. First, a groove having a rectangular cross-sectional shape including the vertical wall surface20e2and the bottom wall surface20e1is processed. At this point of time, burrs generated at the time of processing may remain in a peripheral portion of the groove opening20e4in the vertical wall surface20e2. After that, however, the above-mentioned burrs are removed by processing the tapered surface20e3having a trapezoidal cross-sectional shape.

In the present modification shown inFIG.30, the supply flow channel includes a branch flow channel205that branches from the main flow channels20eand connects the main flow channels20eto each other, in addition to the straight portions201that are the main flow channels20e. The branch flow channel205has a shape extending annularly when viewed from the moving direction of the movable core30. Specifically, the branch flow channel205has an annular shape surrounding the internal passage20a. The branch flow channel205has a groove shape having the same depth as that of the straight portion201. The branch flow channel205has a shape extending over the entire circumference so as to connect all the main flow channels20eto each other.

In an example ofFIG.25, four main flow channels20eare provided, but in the present modification, eight main flow channels20eare provided, and the multiple main flow channels20eare arranged at regular intervals in the circumferential direction when viewed from the moving direction of the movable core30. One branch flow channel205having an annular shape is provided.

In an example ofFIG.25, the valve closing contact surface21bis divided in the circumferential direction by the straight portion201. On the other hand, in the present modification shown inFIG.30, since the branch flow channel205is provided in addition to the straight portion201, the valve closing contact surface21bis divided in the radial direction in addition to the division in the circumferential direction.

In a state in which the needle20contacts the cup50, a part of the fuel flowing into the main flow channels20efrom both sides of the annular inner side and the annular outer side is supplied to the valve closing contact surface21bfrom the circumferential direction. Further, the fuel that has flowed into the branch flow channel205after having flowed into the main flow channels20eis supplied to the valve closing contact surface21bfrom the radial direction.

As described above, according to the present modification, the supply flow channel has the branch flow channel205branched from the main flow channels20ein addition to the main flow channels20econnecting the annular inner side and the annular outer side. For that reason, the fuel is supplied from both the main flow channels20eand the branch flow channel205to the valve closing contact surface21b. This makes it possible to promote a reduction of the linking phenomenon due to the above-mentioned close contact.

Further, in the fuel injection valve according to the present modification, the branch flow channel205has a shape extending annularly when viewed from the moving direction of the needle20. For that reason, both ends of the branch flow channel205communicate with the main flow channels20e, so that the inflow of the fuel from the main flow channels20eto the branch flow channel205can be promoted, and the supply of the fuel to the valve closing contact surface21bcan be promoted.

In the present modification shown inFIG.31, the main flow channels20eeach have the straight portions201and inflow portions202. The straight portions201each have a shape extending linearly when viewed from the moving direction of the movable core30. The inflow portion202communicates with the straight portion201to form an inflow port203for the fuel to the main flow channel20e. A flow channel cross section of the inflow portion202has a shape larger in area than a flow channel cross section of the straight portion201. Specifically, in the sectional view shown in (b) ofFIG.32, the inflow portion202has a shape in which the groove width increases toward the nozzle hole. In a top view shown inFIG.31, the inflow portion202has a shape in which the groove width increases toward the radially outer side.

Among the fuel inflow ports203and204provided at both ends of the main flow channels20e, the inflow port203located outside the above-mentioned annularly extending region is provided with the inflow portion202having an enlarged area. On the other hand, the inflow port204located inside the annularly extending region is not provided with an inflow portion having an enlarged area. Corner portions of the outer peripheral portion and the inner peripheral portion of the contact portion21of the needle20are chamfered, and the outer peripheral portion and the inner peripheral portion of the contact portion21are formed in a tapered shape.

The main flow channels20eare provided by laser processing. A one-dot chain line inFIG.32indicates a center of a laser beam. First, as shown in the column (a) ofFIG.32, a groove in a portion corresponding to the straight portion201is provided by a laser. More specifically, laser processing is started from the inside in the radial direction, and the laser beam is moved from the inside toward the outside. In the processing of the straight portion201, a focal point of the laser beam is made to coincide with a bottom surface of the groove.

After the laser beam has been moved to the outer end portion of the straight portion201to complete the processing of the straight portion201, the laser beam is further moved to the radially outer side, and the groove in the portion corresponding to the inflow portion202is processed by the laser as shown in the column (b) ofFIG.32. The focal point of the laser beam at the time of processing the inflow portion202is set to be the same as the focal point of the laser beam at the time of processing the straight portion201. Since the outer peripheral portion of the contact portion21is formed in a tapered shape, the bottom surface of the inflow portion202is cut at a position deviated from the focal point of the laser beam. As a result, since a cutting width at the bottom surface of the inflow portion202is made larger than a cutting width at the bottom surface of the straight portion201, the inflow portion202is formed in a shape in which the groove width is larger toward the nozzle hole side.

As described above, according to the present modification, the main flow channels20ehave the straight portion201extending linearly as viewed from the moving direction of the movable core30, and the inflow portion202communicating with the straight portion201to form the inflow port203of the fuel. The flow channel cross section of the inflow portion202has a shape in which the area is enlarged as compared with the flow channel cross section of the straight portion201. For that reason, as compared with the case where the inflow portion202is not provided, the fuel easily flows from the inflow port203into the straight portion201, and therefore, the fuel supply to the valve closing contact surface21bcan be promoted.

The supply flow channel shown inFIG.24is provided by the grooved main flow channel20eprovided in the needle20. In contrast, in the present modification shown inFIG.33, a through hole52dis provided in the cup50, and the through hole52dprovides a supply flow channel for supplying the fuel to the valve closing contact surface21b.

According to the above configuration, when the movable core30starts to move by a predetermined amount, the fuel of the flow channel13ais supplied to the valve closing contact surface21bin a state in which the movable core30contacts the cup50through the through hole52d. For that reason, similarly to the embodiment ofFIG.24, since the cup50can be inhibited from coming into close contact with the needle20and becoming difficult to separate from the needle20, the valve opening responsiveness can be improved and the variation in the fuel injection amount due to the variation in the valve opening timing can be reduced.

In the supply flow channel shown inFIG.24, the grooved main flow channels20eare provided in the needle20. On the other hand, in the present modification shown inFIGS.34and35, a groove-d main flow channel210eis provided in a plate210which will be described below.

The plate210is disposed between the needle20and the cup50and is circular plate-shaped and made of metal. In the illustrated example, the main flow channel210eis provided on the surface of the plate210on the nozzle hole side, alternatively may be formed on the surface of the plate210on the side opposite to the nozzle hole side. The multiple (for example, four) main flow channels210eare provided, and the multiple main flow channels210eare arranged at regular intervals in the circumferential direction when viewed from the moving direction of the movable core30. The main flow channels210eeach have a shape linearly extending in the radial direction. The multiple main flow channels210eeach have the same shape.

The main flow channels210eeach have a shape extending so as to connect the annular inner side and the annular outer side across the annular region in which the valve closing contact surface21bis formed in the same manner as the main flow channels20eshown inFIG.25. Therefore, the main flow channels210eeach communicate the internal passage20aof the needle20with the gap B2in a state in which the valve closing contact surface21bcontacts the cup50through the plate210.

The plate210is not coupled to the needle20and the cup50, but is defined as a part of the needle20or the cup50. A through hole52aof the cup50and a through hole210acommunicating with the internal passage20aof the needle20are provided in the plate210.

As described above, according to the present modification, when the movable core30starts to move by a predetermined amount, the fuel in the flow channel13ais supplied to the valve closing contact surface21bin a state in which the movable core30contacts the cup50through the plate210through the main flow channel210e. For that reason, similarly to the embodiment ofFIG.24, since the needle20can be inhibited from coming into close contact with the plate210and becoming difficult to separate from the plate210, the valve opening responsiveness can be improved and the variation in the fuel injection amount due to the variation in the valve opening timing can be reduced.

The supply flow channel shown inFIG.24is provided by the grooved main flow channel20eprovided in the valve closing contact surface21bof the needle20. On the other hand, in the present modification, the main flow channel20eis eliminated, and the supply flow channel is provided by unevenness which will be described below. In other words, shot blasting for causing an abrasive material to collide with the valve closing contact surface21bis performed to increase the surface roughness of the valve closing contact surface21b, whereby the valve closing contact surface21bis provided with unevenness. The unevenness is substituted for the main flow channel20ewhich provides the supply flow channel. In other words, the surface roughness of the valve closing contact surface21bis made rougher than that of the inner peripheral surface of the part forming the internal passage20aof the surface of the needle20. Alternatively, the surface roughness of the valve closing contact surface21bis made rougher than that of the outer peripheral surface of the needle20.

According to the supply flow channel by the unevenness, the hardness of the valve closing contact surface21bis increased by shot blasting. For that reason, the abrasion resistance of the valve closing contact surface21bcan be improved due to the repeated collision of the cup50with the needle20.

Instead of performing the shot blasting on the needle20to form the unevenness as described above, shot blasting may be performed on the valve closing force transmission contact surface52cof the cup50to form the unevenness. In that case, the supply flow channel is provided by the unevenness formed on the valve closing force transmission contact surface52c.

Detailed Description of Configuration Group D

Next, among the configurations of the fuel injection valve1according to the present embodiment, a configuration group D including at least a recessed surface60ato be described below and a configuration related to the recessed surface60awill be described in detail with reference toFIGS.36and37.

As described above, the inner peripheral surface of the cylindrical portion61of the guide member60forms the sliding surface61bthat slides with the outer peripheral surface51dof the cylindrical portion51of the cup50. The sliding surface61bslides the outer peripheral surface51dof the cup50so as to guide the movement of the cup50in the direction of the axis line C while restricting the movement of the cup50in the radial direction. The sliding surface61bis a surface having a shape extending in parallel with the direction of the axis line C.

The recessed surface60ais formed on a surface of the inner surface of the guide member60which is connected to the side opposite to the nozzle holes of the sliding surface61b. The recessed surface60ais shaped to be recessed in a direction in which the gap to the cup50is enlarged in the radial direction. The recessed surface60ahas a shape extending annularly around the axis line C, and has the same shape in any cross section in the circumferential direction.

An adjacent surface60a1of the recessed surface60aadjacent to the sliding surface61bis a surface connected to the sliding surface61bon the side opposite to the nozzle hole, and is shaped to gradually enlarge a gap CL1from the cup50in the radial direction as a distance from the sliding surface61bincreases. The adjacent surface60a1includes a tapered surface60a2extending linearly in a cross section including the axis line C. A boundary portion60bof the guide member60including a boundary between the adjacent surface60a1and the sliding surface61bhas a shape curved to be convex inward in the radial direction, that is, an R-shape. As a result, the cup50can be inhibited from being worn by the guide member60.

A chamfered portion61cformed in a tapered shape by chamfering is provided at a portion connecting the stopper contact end face61aand the sliding surface61b. The boundary portion including the boundary between the chamfered portion61cand the sliding surface61bhas a shape curved to be convex inward in the radial direction, and inhibits the cup50from being worn by the guide member60.

In the cup50, a corner portion51gconnecting the outer peripheral surface51dand the core contact end face51aand a corner portion51hconnecting the transmission member-side sliding surface51cand the core contact end face51aare chamfered so as to have a tapered shape or an R shape. A corner portion21dof the needle20, which connects the valve body-side sliding surface21cand the valve opening contact surface21a, is also chamfered so as to have a tapered shape or an R-shape. A boundary portion21eincluding a boundary between the chamfered portion formed on the side opposite to the nozzle hole with respect to the valve body-side sliding surface21cand the valve body-side sliding surface21chas a shape curved to be convex outward in the radial direction, and inhibits wear between the cup50and the needle20.

In the following description, a part of the surface of the cup50, which includes the outer peripheral surface51dof the cylindrical portion51of the cup50and extends in parallel with the direction of the axis line C, is referred to as a parallel surface. In an example ofFIG.36, the entire outer peripheral surface51dcorresponds to a parallel surface, and a range indicated by a symbol M1inFIG.37is a parallel surface in the surface of the cup50.

Further, a surface which is connected to the side opposite to the nozzle holes of the parallel surface and which is located in the radially inner side of the parallel surface is referred to as a connection surface51e. The connection surface51eis curved to be convex outward of the cup50in the radial direction. In the surface of the cup50, a range indicated by a symbol M2inFIG.37is the connection surface51e. The surface of the connection surface51econnected to the side opposite to the parallel surface is a spring contact surface to which the first elastic force is applied by contacting the first spring member SP1. The spring contact surface has a shape extending perpendicularly to the direction of the axis line C.

A boundary line between the parallel surface and the connection surface51eis referred to as a connection boundary line51f(refer to a circle inFIG.37). As the movable core30moves in the direction of the axis line C, the cup50also moves in the direction of the axis line C. A movable range M3of the connection boundary line51fin the direction of the axis line C by the above movement is entirely located within a range N1of the recessed surface60ain the direction of the axis line C.

The outer peripheral surface of the guide member60is press-fitted into the enlarged diameter portion13cof the fixed core13. In this manner, since the guide member60is press-fitted into the fixed core13, the guide member60is not tilted with respect to the fixed core13. However, a dimensional tolerance of the outer peripheral surface of the guide member60or the inner peripheral surface of the enlarged diameter portion13cis tilted. On the other hand, since the cup50is slidably disposed with respect to the guide member60, a gap CL1for sliding is provided between the cup50and the guide member60. Accordingly, the cup50can be tilted with respect to the fixed core13and the guide member60. In other words, the axis line C of the cup50may be tilted with respect to the axis line C of the fixed core13.

Since the needle20is slidably disposed on the cup50, a gap CL2for sliding is provided between the needle20and the cup50. Therefore, the needle20may be further tilted with respect to the inclinable cup50. In other words, the axis line C of the needle20may be further tilted relative to the axis line C of the inclinable cup50. Therefore, an angle (maximum inclination angle) at which the needle20is tilted to the maximum and the cup50is tilted to the maximum in the same direction as that of the needle20corresponds to the assumed maximum inclination angle θ2(refer toFIG.36) at which the cup50is tilted. The tapered surface60a2is formed so that an inclination angle θ1(refer toFIG.36) at which the tapered surface60a2is tilted with respect to the sliding surface61bof the guide member60is larger than the maximum inclination angle θ2of the cup50.

The gap CL1between the parallel surface of the cup50and the sliding surface61bof the guide member60is set to be larger than the gap CL2between the cup50and the needle20. Therefore, the inclination angle of the cup50when the gap CL2is zero is larger than the inclination angle of the needle20when the gap CL1is zero.

A sliding distance between the cup50and the guide member60in the gap CL1is set to be longer than a sliding distance between the cup50and the needle20in the gap CL2. In this example, the longer the sliding distance, the smaller the inclination caused by the gap. For example, the longer the sliding distance in the gap CL1, the smaller the inclination of the cup50with respect to the guide member60. The longer the sliding distance in the gap CL2, the smaller the inclination of the needle20with respect to the cup50. Even if both those inclinations are maximum, the connection surface51eis set so as not to contact the guide member60.

The guide member60is made of a magnetic material, and the cup50is made of a non-magnetic material. In general, a nonmagnetic material has a lower hardness than a magnetic material. Nevertheless, in the present embodiment, the cup50and the guide member60have the same hardness. In other words, a high hardness nonmagnetic material is used as the cup50instead of a general nonmagnetic material. The hardness of the cup50(cup hardness) and the hardness of the guide member60(guide member hardness) are, for example, values ranging from Vickers hardness HV600 to HV700. If the deviation of the guide member hardness with respect to the cup hardness falls within a range of −10% to +10% of the cup hardness, both the hardness are considered to have the same hardness.

When the wear progresses due to the sliding between the cup50and the guide member60, the cup50is largely tilted with respect to the guide member60, and consequently, the needle20is largely tilted together with the cup50. When the inclination of the needle20increases, the valve opening and closing timing of the needle20varies, and the variation in the fuel injection amount increases.

To cope with the above concern, the present embodiment includes the needle20(valve body), the fixed core13, the movable core30, the first spring member SP1(spring member), the cup50(valve closing force transmission member), and the guide member60.

The movable core30contacts the needle20at a point of time when the movable core30is attracted by the fixed core13and moved by a predetermined amount, and causes the needle20to perform the valve opening operation. The first spring member SP1is elastically deformed accompanying the valve opening operation of the needle20, and exhibits a valve closing elastic force for closing the needle20. The cup50has a valve body transmission portion (circular plate portion52) that contacts the first spring member SP1and the needle20to transmit the valve closing elastic force to the needle20, and a cylindrical portion51that urges the movable core30toward the nozzle holes. The guide member60has a sliding surface61bthat slides the outer peripheral surface51dof the cylindrical portion51so as to guide the movement of the cylindrical portion51in the direction of the axis line C while restricting the movement of the cylindrical portion51in the radial direction. The guide member60is provided with the recessed surface60awhich is a surface connected to the sliding surface61bon the side opposite to the nozzle hole and which is recessed in a direction in which the gap with the cup50is enlarged in the radial direction. The valve body transmission portion is a circular plate portion52having a circular plate shape, and the cylindrical portion51is a shape extending from the circular plate outer peripheral edge of the circular plate portion52to the nozzle hole side.

In the surface of the cup50, a surface that includes the outer peripheral surface of the cylindrical portion51and extends in parallel with the axis line C direction is the parallel surface, a surface that is connected to the parallel surface on the side opposite to the nozzle holes and is located on the radially inner side of the parallel surface is the connection surface51e, and a boundary line between the parallel surface and the connection surface51eis the connection boundary line51f. The movable range M3of the connection boundary line51fin the axial direction is entirely located within a range N1of the recessed surface60ain the axial direction. In other words, the position of the connection boundary line51fin the axial direction is in the range N1in which the recessed surface60ais provided, regardless of whether the needle20is fully lifted or closed.

For that reason, when the cup50moves in the axial direction while sliding on the guide member60, the connection boundary line51ffaces the recessed surface60aand does not contact the sliding surface61b. This makes it possible to inhibit the cup50from being pressed against the guide member60in a state where the surface pressure component in the axial direction is large, and makes it possible to reduce the wear of the cup50. For that reason, the inclination of the cup50can be reduced, and consequently the inclination of the needle20can be reduced, so that the variation in the fuel injection amount due to the variation in the valve opening and closing timing of the needle20can be reduced.

Further, in the fuel injection valve1according to the present embodiment, the adjacent surface60a1of the recessed surface60a, which is adjacent to the sliding surface61b, is shaped to gradually enlarge the gap CL1between the fuel injection valve1and the cup50in the radial direction as a distance from the sliding surface61bincreases. In this example, contrary to the present embodiment, in the case where the adjacent surface60a1has a shape in which the radial direction is enlarged in a stepped manner, the surface pressure when the corner portion of the stepped portion is pressed against the cup50moving toward the nozzle hole side is increased, and there is a concern that the wear is accelerated. In view of the above circumstances, since the adjacent surface60a1according to the present embodiment has a shape that gradually expands in the radial direction, the above-mentioned surface pressure can be alleviated, and the fear of promoting the wear between the cup50and the guide member60can be reduced.

Further, in the fuel injection valve1according to the present embodiment, the adjacent surface60a1includes the tapered surface60a2extending linearly in sectional view. The inclination angle θ1at which the tapered surface60a2is tilted with respect to the sliding surface61bis larger than the assumed maximum inclination angle θ2at which the cup50is tilted. For that reason, the possibility that the tilted cup50comes into contact with the tapered surface60a2can be reduced, and the fear of promoting the wear between the cup50and the guide member60can be reduced.

Further, in the fuel injection valve1according to the present embodiment, the boundary portion60bincluding the boundary between the adjacent surface60a1and the sliding surface61bhas a shape curved to be convex inward in the radial direction. In this example, contrary to the present embodiment, in the case where the boundary portion has a sharp shape, the surface pressure when the boundary portion is pressed against the cup50moving toward the nozzle hole side is increased, and there is a fear of promoting wear. In view of the above circumstances, in the present embodiment, since the boundary portion60bhas a shape curved to be convex inward in the radial direction, the surface pressure can be alleviated, and the fear of promoting wear can be reduced.

Further, in the fuel injection valve1according to the present embodiment, the guide member60is made of a magnetic material, and the cup50is made of a non-magnetic material. According to the above configuration, the parallel surface of the cup50can be prevented from being pressed against the sliding surface61bof the guide member60by the electromagnetic attraction force acting on the cup50in the radial direction. Therefore, the wear between the cup50and the guide member60can be reduced.

Further, in the fuel injection valve1according to the present embodiment, the cup50and the guide member60have the same hardness. In general, a nonmagnetic material has a lower hardness than a magnetic material. Nevertheless, in the present embodiment, as described above, a high-hardness nonmagnetic material is used as the cup50instead of a general nonmagnetic material. For that reason, the possibility that the wear of the member on the low hardness side is accelerated when there is a difference in hardness can be avoided while avoiding the electromagnetic attraction force acting on the cup50.

Further, in the fuel injection valve1according to the present embodiment, the gap CL1between the parallel surface of the cup50and the sliding surface61bof the guide member60is larger than the gap CL2between the cup50and the needle20.

In this example, the needle20may be opened and closed in a state of being tilted with respect to the direction of the axis line C. When the needle20is tilted, the cup50is tilted by a tilting force, and when the cup50is tilted, the force with which the cup50is pressed against the guide member60increases, which may cause wear. Therefore, according to the present embodiment in which the recessed surface60ais applied to a configuration in which wear is concerned as described above, the wear reduction effect by the recessed surface60acan be more effectively exhibited.

Detailed Description of Configuration Group E

Next, a configuration group E including at least the press-fit structure between the outer core31and the inner core32and the configuration related to the press-fit structure among the configurations of the fuel injection valve1according to the present embodiment will be described in detail with reference toFIGS.38and39. In addition, a modification of the configuration group E will be described later with reference toFIGS.40to42.

As shown inFIG.38, a press-fit surface31pformed on the inner peripheral surface of the outer core31and a press-fit surface32pformed on the outer peripheral surface of the inner core32are press-fitted to each other. Those press-fit surfaces31pand32pare not formed over the entire area in the direction of the axis line C, but are formed partially in the direction of the axis line C.

In the present embodiment, the press-fit surfaces31pand32pare formed on a part of the movable core30on the side opposite to the nozzle hole, and in the following description, a portion of the outer core31where the press-fit surface31pis formed and the entire portion in the direction of the axis line C including the press-fit surface31pis referred to as a press-fit region311. A portion of the outer core31where the press-fit surface31pis not formed and the entire portion in the radial direction which does not include the press-fit surface31pis referred to as a non-press-fit region312. In other words, in the direction of the axis line C, the outer core31is divided into a press-fit region311on a side opposite to the nozzle hole and a non-press-fit region312on the nozzle hole side adjacent to the press-fit region in the direction of the axis line C.

The non-press-fit region312is formed with a locking portion31bthat contacts a locking portion32iof the inner core32in the direction of the axis line C. The locking portion32iprevents the inner core32from being deviated toward the nozzle hole side with respect to the outer core31due to the collision of the inner core32with the guide member60and the like. In the inner peripheral surface of the non-press-fit region312, a gap B3from the inner core32is provided in a portion from the locking portion31bto the boundary of the press-fit region311. In other words, the gap B3is located at the boundary between the press-fit region311and the non-press-fit region312.

The gap B3functions as a region for confining burrs generated when the inner core32is press-fitted into the outer core31. Since the material of the outer core31is softer than that of the inner core32, the burrs are generated on the press-fit surface31pof the outer core31. More specifically, the above-mentioned burrs are generated when the nozzle hole side end portion of the press-fit surface32pof the inner core32scrapes off a part of the press-fit surface31pof the outer core31.

In the present embodiment, after the inner core32has been assembled to the outer core31, the communication grooves32eand the outer communication grooves31eare provided by cutting or the like, and then the first core contact surface32cand the second core contact surface32bare ground. As a result, the positions of the first core contact surface32cand the second core contact surface32bin the axis line C are aligned.

The outer peripheral surface of the outer core31indicated by a solid line inFIG.39shows a state before press-fitting with the inner core32, and is circular (perfect circle) in a top view. On the other hand, in the state after the press-fit with the inner core32, the outer peripheral surface of the press-fit region311of the outer core31expands outward in the radial direction as indicated by a dotted line inFIG.39. However, a portion where the through holes31aexist (small expansion portion311a) is less likely to expand than a portion where the through holes31ado not exist (large expansion portion311b). Therefore, the outer peripheral surface of the press-fit region311after the press-fit deformation is not a perfect circle, and the large expansion portion311bhas a shape with a diameter larger than that of the small expansion portion311a. In the state before press-fitting, the diameter of the outer peripheral surface of the press-fit region311is the same as that of the non-press-fit region312. Therefore, in the state after the press-fit, the outer peripheral surface of the press-fit region311has a diameter larger than that of the outer peripheral surface of the non-press-fit region312(refer toFIG.38).

The holder for movably accommodating the movable core30has the main body12, which is a magnetic member having magnetism, and the non-magnetic member14adjacent to the main body12in the moving direction, and an end face of the main body12and an end face of the non-magnetic member14are welded to each other. A portion of the holder facing the outer peripheral surface of the press-fit region311is defined as a press-fit facing portion H1, and a portion of the holder facing the outer peripheral surface of the non-press-fit region312is defined as a non-press-fit facing portion H2. A minimum gap in the radial direction between the inner peripheral surface of the press-fit facing portion H1and the outer peripheral surface of the press-fit region311is defined as a press-fit portion gap CL3, and a minimum gap in the radial direction between the inner peripheral surface of the non-press-fit facing portion H2and the outer peripheral surface of the non-press-fit region312is defined as a non-press-fit portion gap CL4. A minimum inner diameter of the press-fit facing portion H1is set to be larger than a minimum inner diameter of the non-press-fit facing portion H2so that the press-fit portion gap CL3is larger than the non-press-fit portion gap CL4.

The inner peripheral surface of the press-fit facing portion H1has a shape extending in parallel with the moving direction of the movable core30(in the direction of the axis line C). The inner peripheral surface of the non-press-fit facing portion H2has a parallel surface H2aextending in parallel with the moving direction, and a connection surface H2bconnecting the inner peripheral surface of the press-fit facing portion H1and the parallel surface H2a. The connection surface H2bhas a shape in which the inner diameter gradually decreases toward the parallel surface H2a. Although a part of the main body12is included in the non-press-fit facing portion H2, the non-magnetic member14is not included in the non-press-fit facing portion H2, and the parallel surface H2aand the connection surface H2bare formed by the main body12. In other words, the main body12has a shape having the parallel surface H2aand the connection surface H2bhaving different inner diameter dimensions. The non-press-fit portion gap CL4, which is the smallest gap between the non-press-fit facing portion H2and the non-press-fit region312, corresponds to a gap in the parallel surface H2aformed by the main body12.

More specifically, a flow channel cross-sectional area defined by the press-fit portion gap CL3is larger than a flow channel cross-sectional area defined by the non-press-fit portion gap CL4. Those flow channel cross-sectional areas are areas of a cross section perpendicular to the axis line C of the flow channel defined by the press-fit portion gap CL3and CL4.

The inner peripheral surface H1aof the press-fit facing portion H1has a shape extending in parallel with the moving direction. The press-fit facing portion H1includes a part of the non-magnetic member14and a part of the main body12. The non-magnetic member14is formed to have a uniform inner diameter dimension along the entire axis line C direction. The press-fit portion gap CL3, which is the smallest gap between the press-fit facing portion H1and the press-fit region311, corresponds to a gap at a portion of the main body12on the side opposite to the nozzle hole with respect to the connection surface H2b, or at the non-magnetic member14.

When the movable core30attracted to the fixed core13is configured by press-fitting the inner core32for collision with the guide member60and the like and the outer core31for the magnetic circuit, the outer diameter of the outer core31is slightly expanded by the press-fitting. As a result, the gap between the inner peripheral surface of the holder accommodating the movable core30and the outer peripheral surface of the outer core31becomes small, and a flow resistance received by the movable core30from the fuel existing in the gap becomes large. Since it is difficult to manage the amount by which the outer diameter expands due to press-fitting, a machine difference variation occurs in the magnitude of the flow resistance, resulting in a variation in the moving speed of the movable core30. As a result, the machine difference variation occurs in the valve opening responsiveness, resulting in a large variation in the injection amount.

On the other hand, the fuel injection valve1according to the present embodiment includes the needle20(valve body), the fixed core13, the movable core30, the main body12(holder) and the non-magnetic member14(holder), and the guide member60(stopper member). The movable core30has a cylindrical shape, and moves together with the needle20by the magnetic attraction force to open the nozzle holes11a. The holder has a movable chamber12afilled with fuel, and accommodates the movable core30in the movable chamber12ain a movable state. The guide member60contacts the movable core30and restricts the movable core30from moving away from the nozzle holes11a. The movable core30has the inner core32contacting the guide member60, and the outer core31press-fitted into the outer peripheral surface of the inner core32. The outer core31has the press-fit region311which is press-fitted into the outer peripheral surface of the inner core32in the moving direction of the movable core30, and the non-press-fit region312which is not press-fit into the outer peripheral surface of the inner core32and is adjacent to the press-fit region311in the moving direction. Among the gaps between the inner peripheral surface of the holder and the outer peripheral surface of the movable core30, the smallest gap CL3in the press-fit region311is larger than the smallest gap CL4in the non-press-fit region312.

In this example, the flow resistance received by the movable core30from the fuel existing in the gap between the outer core outer peripheral surface and the holder inner peripheral surface is greatly influenced by the smallest gap when the size of the gap changes in accordance with the axial position. The gap CL3in the press-fit region311in the gap between the inner peripheral surface of the holder and the outer peripheral surface of the movable cores is larger than the gap CL4in the non-press-fit region312. Therefore, contrary to the present embodiment, when the minimum gap CL3in the press-fit region311is smaller than the minimum gap CL4in the non-press-fit region312, the flow resistance is greatly affected by the gap CL3in the press-fit region311. As a result, a large variation in the flow resistance between machines occurs. In contrast, according to the present embodiment, the minimum gap CL3in the press-fit region311is larger than the minimum gap CL4in the non-press-fit region312. For that reason, the flow resistance can be inhibited from being affected by the gap CL3in the press-fit regions311, and the moving speed of the movable core30can be inhibited from varying. As a result, the machine difference variation in the valve opening response can be inhibited, and consequently, the injection amount variation can be reduced.

Further, in the fuel injection valve1according to the present embodiment, the inner peripheral surface H1aof the press-fit facing portion H1has a shape extending in parallel with the moving direction. The inner peripheral surface of the non-press-fit facing portion H2has a parallel surface H2aextending in parallel with the moving direction, and a connection surface H2bconnecting the inner peripheral surface of the press-fit facing portion H1and the parallel surface H2a. The connection surface H2bhas a shape in which the inner diameter gradually decreases toward the parallel surface H2a.

A boundary between a portion (large expansion portion311b) in which expansion is largely generated by press-fitting and a portion (small expansion portion311a) in which expansion is hardly generated is gradually expanded. In view of the above circumstances, according to the present embodiment having the connection surface H2bwhose inner diameter gradually decreases, the gap of the magnetic circuit provided by the portion of the connection surface H2bcan be made as small as possible. As shown inFIG.38, the connection surface H2bmay have a tapered shape in which the inner diameter changes linearly gradually, a curved shape in which the inner diameter changes in a curved manner, or a stepped shape in which the inner diameter changes in a stepped manner.

Further, in the fuel injection valve1according to the present embodiment, the holder has the main body12(magnetic member) having magnetism, and the non-magnetic member14adjacent to the main body12in the moving direction, and the end face of the main body12and the end face of the non-magnetic member14are welded to each other. This makes it possible to carry out a step of making the inner diameter of the holder large or small and a step of removing a weld mark from the inner peripheral surface of the holder in a series of operations, thereby being capable of reducing a labor required for making the inner diameter of the holder large or small.

Further, in the fuel injection valve1according to the present embodiment, three or more through holes31apenetrating in the moving direction are provided in the outer core31at regular intervals in the circumferential direction. According to the above configuration, there are three or more locations around the axial direction at regular intervals where the flow resistance received by the movable core30from the fuel in the movable chamber12ais low. For that reason, when the movable core30moves in the direction of the axis line C, a change in the inclination direction of the movable core30with respect to the direction of the axis line C can be reduced. Therefore, since the behavior of the movable core30can be inhibited from becoming unstable, the variation in the valve opening response can be further reduced.

In the present modification shown inFIG.40, a maximum outer diameter of the outer core31in the press-fit region311is smaller than a maximum outer diameter of the outer core31in the non-press-fit region312.

Specifically, the outer diameter of the press-fit region311is formed to be sufficiently smaller than the outer diameter of the non-press-fit region312before press-fitting, and the outer diameter of the press-fit region311is formed to be smaller than the outer diameter of the non-press-fit region312even when the press-fit region311is expanded by press-fitting. In short, in a state before press-fitting, the outer peripheral surface of the press-fit region311is cut to form a recess portion311c, and a cutting depth of the recess portion311cis set to be sufficiently large so that the recess portion311cremains even after expansion due to press-fitting. In addition, an inner diameter dimension of the non-press-fit facing portion H2is the same in the direction of the axis line C in the same manner as the press-fit facing portion H1.

As described above, since the outer peripheral surface of the press-fit region311is formed to be smaller than the non-press-fit region312and the inner peripheral surface of the non-press-fit facing portion H2is formed to be the same as the press-fit facing portion H1, the press-fit portion gap CL3is larger than the non-press-fit portion gap CL4. For that reason, the same effects as those of the fuel injection valve1shown inFIG.39are exhibited in the present modification.

In the present modification shown inFIG.41, all of the press-fit facing portion H1of the holder is made of the non-magnetic member14, and the main body12is not included in the press-fit facing portion H1. For example, a length of the press-fit surfaces31pand32pin the direction of the axis line C is shortened as compared with the structure ofFIG.39, so that the entire press-fit facing portion H1is made of the non-magnetic member14. Alternatively, as compared with the structure ofFIG.39, the length of the non-magnetic member14in the direction of the axis line C is made longer, so that the entire press-fit facing portion H1is made of the non-magnetic member14. Also, in the present modification, since the press-fit portion gap CL3is provided to be larger than the non-press-fit portion gap CL4, the same effects as those of the fuel injection valve1shown inFIG.39are exhibited.

In the present modification shown inFIG.42, a portion of the press-fit region311which is expanded in the radial direction by press-fit is removed, and the maximum outer diameter of the outer core31in the press-fit region311is formed to be the same as the maximum outer diameter of the outer core31in the non-press-fit region312.

More specifically, in a state before press-fitting with the inner core32, the outer core31whose outer peripheral surface is circular (perfect circle) in a top view is prepared (preparation process) and is press-fitted with the inner core32(press-fitting process). Thereafter, the large expansion portion311b(refer toFIG.39) expanded by press-fitting is cut after press-fitting (cutting process), whereby the outer core31is formed so that the outer peripheral surface becomes circular (perfect circle) in the top view. The inner diameter dimensions of the press-fit facing portion H1and the non-press-fit facing portion H2are the same in the direction of the axis line C. Therefore, the press-fit portion gap CL3and the non-press-fit portion gap CL4are the same. Therefore, the same effects as those ofFIG.39are exhibited by the present modification.

Second Embodiment

While the valve closing force transmission member according to the first embodiment is provided by the cup50, a valve closing force transmission member according to the present embodiment is provided by a first cup501, a second cup502, and a third spring member SP3(refer toFIG.43) which will be described below. Except for the configuration to be described below, the configuration of a fuel injection valve according to the present embodiment is the same as the configuration of the fuel injection valve according to the first embodiment.

The first cup501contacts a first spring member SP1and a needle20, and transmits a valve closing elastic force by the first spring member SP1to the needle20. In short, the first cup501exhibits the same function as the circular plate portion52of the cup50according to the first embodiment. The first cup501is formed with a through hole52asimilar to that of the first embodiment.

The third spring member SP3is an elastic member that is elastically deformed in the axial direction to exert an elastic force. One end of the third spring member SP3contacts a contact surface501aof the first cup501, and the other end of the third spring member SP3contacts a contact surface502aof the second cup502. As a result, the third spring member SP3is sandwiched between the first cup501and the second cup502and is elastically deformed in the axial direction, and exhibits an elastic force due to the elastic deformation.

The second cup502contacts the movable core30during the valve closing operation to urge the movable core30toward the nozzle holes. In short, the second cup502exhibits the same function as that of the cylindrical portion51of the cup50according to the first embodiment. The third spring member SP3exerts a function of transmitting a force in the axial direction between the first cup501and the second cup502.

The needle20has a main body portion2001and an enlarged diameter portion2002. A valve closing contact surface21bis formed at an end of the main body portion2001on the side opposite to the nozzle holes. The valve closing contact surface21bcontacts a valve closing force transmission contact surface52cof the valve closing force transmission member (first cup501) in the same manner as in the first embodiment.

The enlarged diameter portion2002is located closer to the nozzle hole side than the valve closing contact surface21b, and has a circular plate shape in which a diameter of the main body portion2001is enlarged. A valve opening contact surface21ais formed on a surface of the nozzle hole side of the enlarged diameter portion2002. The valve opening contact surface21acontacts the first core contact surface32cof the movable core30in the same manner as in the first embodiment. A length of a gap between the valve opening contact surface21aand the first core contact surface32cin the direction of the axis line C in a valve close state corresponds to a gap L1according to the first embodiment.

In a state immediately after the energization of a coil17has been switched from OFF to ON, a magnetic attraction force acts on the movable core30to start the movement of the movable core30toward the valve opening side. Then, when the movable core30moves while pushing up the second cup502and the moving amount reaches the gap L1, the first core contact surface32cof the movable core30collides with the valve opening contact surface21ain the needle20.

In the present embodiment, the guide member60is eliminated, and the movable core30contacts the fixed core13, thereby regulating the valve opening operation amount of the needle20. When the movable core30collides with the needle20as described above, a gap is provided between the fixed core13and the movable core30, and the length of the gap in the direction of the axis line C corresponds to a lift L2of the first embodiment.

The elastic force of the first spring member SP1also acts on the needle20until the time of the collision. After the collision, the movable core30continues to move further by the magnetic attraction force, and when the movement amount after the collision reaches a lift L2, the movable core30collides with the fixed core13and stops moving. A separation distance between the body-side seat11sand the valve body-side seat20sin the direction of the axis line C at the time of stopping the movement corresponds to a full lift of the needle20, and corresponds to the lift L2described above.

Third Embodiment

The valve closing force transmission member (cup50) according to the first embodiment has the cup shape having the cylindrical portion51and the circular plate portion52. On the other hand, a valve closing force transmission member according to the present embodiment has a circular plate shape configured by a circular plate portion52in which the cylindrical portion51is eliminated (refer toFIG.44). Except for the configuration to be described below, the configuration of a fuel injection valve according to the present embodiment is the same as the configuration of the fuel injection valve according to the first embodiment.

In the first embodiment, a surface (core contact end face51a) of the valve closing force transmission member, with which the contact surface (second core contact surface32b) of the movable core30is in contact, is formed in the cylindrical portion51. On the other hand, in the present embodiment, a surface of the circular plate portion52on the nozzle hole side functions as a core contact end face52e(refer toFIG.44) that contacts the movable core30.

Other Embodiments

The disclosure herein is not limited to the combinations of components and/or elements shown in the embodiments. The disclosure may have additional portions that may be added to the embodiments. The disclosure encompasses omission of components and/or elements of the embodiments. The disclosure encompasses the replacement or combination of components and/or elements between one embodiment and another. For example, the fuel injection valve1according to the first embodiment includes all of the configuration groups A, B, C, D, and E, but may be a fuel injection valve having any combination of the configuration groups A, B, C, D, and E.

In the first embodiment, the temporary press-fitting is performed once as shown inFIG.6, but the load measurement may be performed for each temporary press-fitting by performing the temporary press-fitting twice or more. According to the above configuration, the setting of the second set load to the target value can be realized with a high accuracy. In addition, since the load is measured every multiple of temporary press-fitting operations, the elastic modulus of the second spring member SP2can be measured, and the degree of press-fitting in this press-fitting operation can be calculated with a high accuracy.

In the press-fitting operation shown inFIG.6, the second set load is measured in a state where the progress of the press-fitting is stopped and the press-fitting is stopped, but the second set load may be measured while the press-fitting is performed. In other words, the press-fitting is performed while measuring the second set load, and the press-fitting is stopped and completed when the measured second set load reaches the target value.

In the press-fitting operation shown inFIG.6, the second set load is measured while the cup50in the state of contacting the needle restricts the movement of the movable core30, but the second set load may be measured while the contact portion21of the needle20restricts the movement of the movable core30.

The communication grooves32eshown inFIG.12are provided on the third core contact surface32din addition to the first core contact surface32cand the second core contact surface32b, but may not be provided on the third core contact surface32d. Although the communication grooves32eshown inFIG.12are provided over the entire area of the first core contact surface32cin the radial direction, it is sufficient that the communication grooves32eare provided in at least a portion of the first core contact surface32cadjacent to the second core contact surface32b.

Although the outer communication grooves31eshown inFIG.16are disposed so as not to communicate with the through holes31a, the outer communication grooves31emay be disposed so as to communicate with the through holes31a. The communication grooves32gshown inFIG.19are provided across the first core contact surface32c, the second core contact surface32b, and the third core contact surface32d, but may not be provided on the third core contact surface32d.

In the examples ofFIGS.21,22, and23, the communication grooves32eare eliminated, and instead of the communication grooves32e, the communication holes20c, the sliding surface communication grooves20d, and the second sliding surface communication grooves32hare provided. On the other hand, the fuel injection valve1may include any two or more of the communication grooves32e, the communication holes20c, the sliding surface communication grooves20d, and the second sliding surface communication grooves32h.

Although the sliding surface communication grooves20dare provided in the needle20in an example ofFIG.22, the sliding surface communication grooves may be provided in the transmission member-side sliding surface51c(refer toFIG.22) of the cup50on which the needle20slides. In an example ofFIG.23, the second sliding surface communication grooves32his formed in the inner core32, but the second sliding surface communication groove may be provided in the surface of the needle20that slides with the inner core32.

In an example ofFIG.24, the main flow channels20efor supplying the fuel to the valve closing contact surface21bin a state of contacting the cup50are provided by the grooves provided in the needle20, but may be provided by grooves provided in the cup50. Specifically, the supply flow channel may be provided by providing grooves in the core contact end face51aof the cylindrical portion51.

In the first embodiment, the movable portion M is supported in the radial direction at two points of the needle20, that is, the portion facing the inner wall surface11cof the nozzle hole body11(the needle tip portion), and the outer peripheral surface51dof the cup50. On the other hand, the movable portion M may be supported from the radial direction at two positions, that is, the outer peripheral surface of the movable core30and the needle tip portion.

In the first embodiment, the inner core32is made of a nonmagnetic material, but may be made of a magnetic material. When the inner core32is made of a magnetic material, the inner core32may be made of a weak magnetic material that is weaker in magnetism than the outer core31. Similarly, the needle20and the guide member60may be made of a weak magnetic material that is weaker than the outer core31.

In the first embodiment, the cup50is interposed between the first spring member SP1and the movable core30in order to realize a core boost structure in which the movable core30contacts the needle20to start the valve opening operation when the movable core30moves by a predetermined distance. On the other hand, the cup50may be eliminated, and a core boost structure in which a third spring member different from the first spring member SP1is provided, and the movable core30is urged toward the nozzle hole by the third spring member may be employed.

In the first embodiment, in order to avoid a magnetic short circuit between the fixed core13and the main body12, the non-magnetic member14is disposed between the fixed core13and the main body12. Instead of the non-magnetic member14, a magnetic member having a shape having a magnetic throttle portion for inhibiting the magnetic short-circuit may be disposed between the fixed core13and the main body12. Alternatively, the non-magnetic member14may be eliminated, and a magnetic throttle portion for inhibiting the magnetic short circuit may be formed in the fixed core13or the main body12.

The sleeve40according to the first embodiment has a shape in which the connection portion42extends on the upper side of the support portion43(on the side opposite to the nozzle holes) and the insertion cylindrical portion41extends on the upper side of the connection portion42. On the other hand, the sleeve40may have a shape in which the connection portion42extends below the support portion43(on the nozzle hole side) and the insertion cylindrical portion41further extends below the connection portion42. The sleeve40may also be a hollow shaped ring extending annularly around the needle20. In this instance, the upper surface of the ring supports the second spring member SP2, and the inner peripheral surface of the ring is press-fitted into the press-fit portion23.

The cup50according to the first embodiment has the cup shape having the circular plate portion52and the cylindrical portion51. On the other hand, the cup50may have a flat plate shape. In this instance, the upper surface (upper surface) of the flat plate contacts the first spring member SP1, and the lower surface (lower surface) of the flat plate contacts the movable core30.

The support member18according to the first embodiment has the cylindrical shape, but may have a C-shaped cross-sectional shape in which a slit extending in the direction of the axis line C is provided in a cylindrical shape.

The movable core30according to the first embodiment has the structure having two parts, that is, the outer core31and the inner core32. The inner core32is made of a material having a higher hardness than the outer core31, and has a surface that contacts the cup50and the guide member60, and a surface that slides with the needle20. On the other hand, the movable core30may have a structure in which the inner core32is eliminated.

When the movable core30has the structure in which the inner core32is eliminated as described above, it is preferable that the contact surface of the movable core30that contacts the cup50and the guide member60and the sliding surface that slides with the needle20are plated. One specific example of plating applied to the contact surface is chromium. One specific example of plating applied to the sliding surface is nickel phosphorus.

The fuel injection valve1according to the first embodiment has the structure in which the movable core30contacts the guide member60attached to the fixed core13. On the other hand, the movable core30may contact the fixed core13in which the guide member60is eliminated. In short, the inner core32may contact the guide member60, or the inner core32may contact the fixed core13in which the guide member60is eliminated. Further, the structure may be applied in which the movable core30in which the inner core32is abolished contacts the guide member60, or the structure may be applied in which the movable core30in which the inner core32is abolished contacts the fixed core13in which the guide member60is abolished.

In the case where the movable core30has the structure in which the inner core32is eliminated as described above, the surface of the movable core30on the side opposite to the nozzle hole, which contacts the needle20, corresponds to the first core contact surface32c. Further, in the case of the structure in which the guide member60is eliminated as described above, the surface of the movable core30that contacts the fixed core13corresponds to the third core contact surface32d.

In the first embodiment, the communication grooves32eare provided in the portion of the inner core32which contacts the guide member60. On the other hand, in the case of the structure in which the guide member60is eliminated as described above, the communication grooves32eare provided in the portion of the inner core32which contacts the fixed core13. When the movable core30has the structure in which the inner core32is eliminated as described above, the communication grooves32eare provided in the portion of the movable core30which contacts the fixed core13.

The cup50according to the first embodiment slides in the direction of the axis line C while contacting the inner peripheral surface of the guide member60. On the other hand, the cup50may be configured to move in the direction of the axis line C while defining a predetermined gap with the inner peripheral surface of the guide member60.

In the first embodiment, the inner peripheral surface of the second spring member SP2is guided by the connection portion42of the sleeve40. On the other hand, the outer peripheral surface of the second spring member SP2may be guided by the outer core31.

In the first embodiment, one end of the second spring member SP2is supported by the movable core30, and the other end of the second spring member SP2is supported by the sleeve40attached to the needle20. On the other hand, the sleeve40may be eliminated, and the other end of the second spring member SP2may be supported by the main body12.

While the present disclosure has been described with reference to embodiments thereof, it is to be understood that the disclosure is not limited to the embodiments and constructions. To the contrary, the present disclosure is intended to cover various modification and equivalent arrangements. In addition, while the various elements are shown in various combinations and configurations, which are exemplary, other combinations and configurations, including more, less or only a single element, are also within the spirit and scope of the present disclosure.