Fuel injection valve

In the present invention, two side-section side surfaces and each horizontal passage run along a fuel flow direction and have a linear section, and an end-section side surface formed between the two side-section side surfaces and forming an upstream-side end portion has a curved section connected to the side-section side surfaces and. When a fuel inlet and the horizontal passages are projected onto a plane perpendicular to a valve axial center, a projected line of the linear section of each of the horizontal passages extends to a place intersecting a projected line of the opening edge of the fuel inlet, and the upstream-side end portion of each of the horizontal passages extends toward the inside of the opening edge.

TECHNICAL FIELD

The present invention relates to a fuel injection valve which generates swirl fuel on the upstream sides of fuel injection holes and injects the swirl fuel from the fuel injection holes.

BACKGROUND TECHNOLOGY

As a background technology of the present technical field, a fuel injection valve has been known which is described in a Japanese Patent Application Publication No. 2012-215135 (patent document 1). This fuel injection valve includes: a valve body swingably provided; a valve seat member in which a valve seat on which the valve body is seated at the time of valve closing and which has an opening part on the downstream side of the valve seat; swirl imparting chambers for imparting swirling force to fuel by making swirl to the fuel inside them; injection holes which are formed on the bottoms of the swirl imparting chambers; and communication passages which communicate the swirl imparting chambers with the opening part of the valve seat member. When the diameter of the swirl imparting chamber is D, the width of the communication passage is W, they are formed to satisfy the equation 0.15 W/D<0.5 (see abstract). In addition, in this fuel injection valve, three sets of fuel passages each formed of a swirl imparting chamber, a communication passage and a fuel injection hole are provided in a nozzle plate, and each of three sets of fuel communication passages is connected to each other in a central chamber formed in the vicinity of the center of the nozzle plate (see paragraph [0015]).

In addition, in a Japanese Patent Application Publication No. 2014-173479, a fuel injection valve has been described which includes swirling chambers each having an inner peripheral wall whose curvature is gradually larger from upstream to downstream, paths for swirling each of which, having a fuel flow-in region formed along a valve axis direction, guides fuel to the associated one of the swirling chambers, and fuel injection orifices open into the associated swirling chambers, respectively, and a curved portion in the fuel injection valve is formed on the bottom of an inlet portion of each of the paths for swirling so as to change the fuel flow (see abstract). In this fuel injection valve, an orifice plate (corresponding to the nozzle plate of the patent document 1) has four paths for swirling which extend radially outwardly from the center of the orifice plate while being circumferentially equidistantly spaced from one another (to be 90 degrees apart) (see paragraphs [0023] and [0024]).

PRIOR ART DOCUMENT

Patent Document

Patent Document 1: Japanese Patent Application Publication 2012-215135Patent Document 2: Japanese Patent Application Publication 2014-173479

SUMMARY OF THE INVENTION

Task to be Solved by the Invention

In the fuel injection valve of the patent document 1, since the three sets of the communication passages are connected in the vicinity of the center of the nozzle plate, the passage length of each of the communication passages becomes long. Consequently, the dead volume of a fuel passage formed on the downstream side of the valve seat becomes large. In contrast to this, in the fuel injection valve of the patent document 2, four sets of the paths for swirling are formed independent of each other, and thereby the length of a fuel passage formed on the downstream side of the valve seat can be shortened.

In the fuel injection valve of the patent document 2, as shown in, for example,FIG. 4of the patent document 1, the end portion on the inlet side of each of the paths for swirling is formed in a arc shape. When the arc-shaped end portion (hereinafter, referred to as an arc-shaped portion), the paths for swirling and a fuel inlet (corresponding to the opening part of the valve member in the patent document 1) for introducing fuel into the paths for swirling are projected onto a plane perpendicular to a valve axis, the opening edge of the fuel inlet intersects the side walls of the paths for swirling at the connection parts in which the linear side wall of each of the paths for swirling is connected to the arc-shaped portion.

With this configuration, when the position between the valve seat member (in the patent document 2, it is referred to as a nozzle plate) formed with the fuel inlet and the orifice plate (nozzle plate) formed with the paths for swirling deviate is shifted, in a path for swirling, the opening edge of the fuel inlet intersects the arc-shaped portion, and the passage cross-sectional area of this path for swirling which faces the fuel inlet is changed at the arc-shaped portion. If the passage cross-sectional area facing the fuel inlet is changed at the arc-shaped portion, as compared with a case where it is changed at the linear section of the path for swirling, the rate of change in the passage cross-sectional area facing the fuel inlet to the amount of the position deviation between the valve seat and the nozzle plate becomes large, and variation in the flow amount of fuel flowing into a plurality of the paths for swirling (communication passages) becomes large.

An object of the present invention is to provide a fuel injection valve which is capable of suppressing variation in the fuel amount of fuel flowing into a plurality sets of communication passages (hereinafter, referred to as horizontal passages) even in a case where position variation occurs between a valve seat member and a nozzle plate.

Means for Solving the Task

To achieve above object, a fuel injection valve of the present invention includes:

fuel injection holes configured to inject fuel to an outside;

a valve body configured to open and close a fuel passage in cooperation with a valve seat, on upstream sides of the fuel injection holes;

a valve seat member formed with the valve seat; and

a nozzle plate in which a plurality of swirl passages are formed and which is connected to a distal end surface of the valve seat member, wherein the swirl passages each include:

a swirl chamber for allowing fuel to be swirled to flow to a corresponding one of the fuel injection holes; and

a horizontal passage which is connected to an upstream side of the swirl chamber and which supplies fuel to the swirl chamber, wherein the valve seat member is opened to the distal end surface to which the nozzle plate is connected and includes a fuel inlet which is connected to an upstream-side end portion of the horizontal passage and introduces fuel into the plurality of the swirl passages, wherein the horizontal passage includes two side-section side surfaces extending along a fuel flow direction and having a linear section, and includes, on an upstream side thereof, an end-section side surface which is formed between the two side-section side surfaces and which has a curved section connected to the linear section, wherein when the fuel inlet and the horizontal passage are projected onto a plane perpendicular to a valve axial center, a projected line of the linear section of the side-section side surfaces of the horizontal passage extends to a place intersecting a projected line of an opening edge of the fuel inlet, and the upstream-side end portion of the horizontal passage extends toward an inside of the opening edge, and wherein, in the plurality of the swirl passages, all of the swirl passages each have a distance dimension equal to 0 or larger between a connection place of the linear section and the curved section and the intersection place of the projected line of the opening edge of the fuel inlet and the projected line of the linear section, and at least one of the swirl passages has a distance dimension larger than 0 between the connection place of the linear section and the curved section and the intersection place of the projected line of the opening edge of the fuel inlet and the projected line of the linear section.

Effects of the Invention

According to the present invention, even if positional deviation occurs between the valve seat member and the nozzle plate, a change in the passage sectional area of the horizontal passages facing the fuel inlet can be small, and thereby a variation in the flow amount of the fuel flowing into a plurality of the horizontal passages can be suppressed.

MODE FOR IMPLEMENTING THE INVENTION

An embodiment of the present invention will be explained with reference to the drawings.

The whole configuration of a fuel injection valve1will be explained with reference toFIG. 1.FIG. 1is a sectional view showing a cross section along a valve axial center (central axis) la in the fuel injection valve1according to the present invention. The central axis1acorresponds to the axis (valve axial center) of a movable element27provided integrally with the after-mentioned valve body17, and to the central axis of the after-mentioned cylindrical body5. In addition, the central axis1aalso corresponds to the central axis of the after-mentioned valve seat15band nozzle plate21n.

The fuel injection valve1is provided with the cylindrical body5made of metal which extends from the upper end part to the lower end part of the fuel injection valve1. The cylindrical body5is formed with, in the inside thereof, a fuel passage3substantially along the central axis1a. InFIG. 1, the upper end part (upper end side) of the fuel injection valve1is referred as a base end part (base end side), and the lower end part (lower end side) of the fuel injection valve1is referred as a distal end part (distal end side). The terms “base end part (base end side)” and “distal end part (distal end side)” are based on the flow direction of fuel or on the fitting structure of the fuel injection valve1to a fuel pipe which is not shown in the drawings. That is, in the flow direction of fuel, the base end part is an upstream side and the distal end part is a downstream side. In addition, an up-and-down relation explained in the present specification is determined based onFIG. 1, and it is not related to a vertical direction of a mounting state of the fuel injection valve1on an internal combustion engine.

The cylindrical body5is provided with, at the base end part thereof, a fuel supply port2. This fuel supply port2is provided with a fuel filter13. The fuel filter13is a member to remove foreign substances mixed in fuel.

An O-ring11is disposed at the base end part of the cylindrical body5. The O-ring11functions as a seal material when the fuel injection valve1is connected to the fuel pipe.

The cylindrical body5is formed with, at the distal end part thereof, a valve part7formed of the valve body17and a valve seat member15. The valve seat member15is formed with a valve body accommodation hole15ahaving a step to accommodate the valve body17. A conical surface is formed in the middle of the valve body accommodation hole15a, and the valve seat (seal part)15bis formed on this conical surface. A guide surface15cto guide the movement of the valve body17in a direction along the central axis1ais formed at a part on the upstream side (base end side) more than the valve seat15bof the valve accommodation hole15a. The valve seat15bperforms the opening/closing of a fuel passage in cooperation with the valve body17. The valve body17comes in contact with the valve seat15b, and the fuel passage is closed. In addition, the valve body17is separated from the valve seat15b, and the fuel passage is opened.

The valve seat member15is inserted into the inside on the distal end side of the cylindrical body5, and is fixed to the cylindrical body5by laser welding. A laser welding19is formed over the entire circumference from the outer circumferential side of the cylindrical body5. The valve body accommodation hole15apenetrates through the valve seat member15in the direction along the central axis1a. A nozzle plate21nformed of a thin plate-shaped member is attached to the lower end surface (distal end surface, downstream-side end surface) of the valve seat member15. The nozzle plate21ncloses the opening of the valve seat member15which is formed by the valve accommodation hole15a.

In the present embodiment, the valve seat member15and the nozzle plate21nform a fuel injection part21configured to inject swirl fuel. The nozzle plate21nis fixed to the valve seat member15by laser welding. A laser welding portion23is formed around the circumference of an injection hole forming region at which fuel injection holes220-1,220-2,220-3and220-4(seeFIG. 3) are formed, so as to surround this injection hole forming region. The valve seat member15may be fixed to the cylindrical body5by the laser welding after being press-fitted into the inside on the distal end side of the cylindrical body5.

In the present embodiment, a ball valve having a spherical shape is used as the valve body17. In the valve body17, a part facing a guide surface15cis provided with a plurality of notched surfaces17aformed at intervals in a circumferential direction, and a gap is formed between the notched surfaces17aand the inner circumferential surface of the valve seat member15. By this gap, a fuel passage is formed. In addition, the valve body17can be formed by a valve body other than the ball valve. For example, a needle valve may be used.

In the present embodiment, the valve part7including the valve seat member15and the valve body17and the nozzle plate21nform a nozzle part configured to inject fuel. The nozzle plate21nin which the after-mentioned fuel injection holes220and passages210for swirl (horizontal passages211and swirl chambers212) are formed is joined to the distal end surface of a nozzle part main body (valve seat member15) at which the valve part7is formed.

A drive part9configured to drive the valve body17is disposed in the middle part of the cylindrical body5. The drive part9is formed by an electromagnetic actuator. Specifically, the drive part9is formed of a fixed iron core25, the movable element (movable member)27, an electromagnetic coil29and a yoke33.

The fixed iron core25is made of a magnetic metal material, and is press-fitted into and fixed to the inside of the middle part in the longitudinal direction of the cylindrical body5. The fixed iron core25is formed in a cylindrical shape, and has a through hole25apenetrating through the center part thereof in the direction along the central axis1a. The fixed iron core25may be fixed to the cylindrical body5by welding, or may be fixed to the cylindrical body5by using welding with press-fitting.

In the inside of the cylindrical body5, the movable element27is disposed on the distal end side with respect to the fixed iron core25. A movable iron core27ais provided on the base end side of the movable element27. The movable iron core27afaces the fixed iron core25via a minute gap6. A small diameter part27bis formed on the distal end side of the movable element27, and the valve body17is fixed to the distal end of this small diameter part27bby welding. In the present embodiment, although the movable iron core27aand the small diameter part27bare formed integrally with each other (one member made of the same material), they may be formed by joining two members. The movable element27is provided with the valve body17, and displaces the valve body17in a valve opening/closing direction. The valve body17comes in contact with the valve seat member15and the outer circumferential surface of the movable iron core27acomes in contact with the inner circumferential surface of the cylindrical body5, and the movement of the movable element27in the direction along the central axis1a(valve opening/closing direction) is guided by two points in a valve axial center direction.

A concave part27cis formed on the end surface of the movable iron core27awhich faces the fixed iron core25. A spring seat27eof a spring (coil spring)39is formed on the bottom surface of the concave part27c. A through hole27fwhich penetrates to the end portion on the distal end side of the small diameter part (connection part)27bis formed on the inner circumferential side of the spring seat27ealong the central axis1a. In addition, an opening part27dis formed on the side surface of the small diameter part27b. The through hole27fis opened to the bottom surface of the concave part27cand the opening part27dis opened to the outer circumferential surface of the small diameter part27b, and a fuel flow passage3is formed which communicates a fuel flow passage3formed in the fixed iron core25with the valve part7.

The electromagnetic coil29is fitted onto the outer circumferential side of the cylindrical body5at a position at which the fixed iron core25faces the movable iron core27avia the minute gap6. The electromagnetic coil29is wound around a cylindrical bobbin31made of a resin material, and is fitted onto the outer circumferential side of the cylindrical body5. The electromagnetic coil29is electrically connected to a connector pin43disposed in a connector41via a wiring member45. A drive circuit which is not shown in the drawings is connected to the connector41, and drive current is fed to the electromagnetic coil29via the connector pin43and the wiring member45.

The yoke33is made of a metal material having magnetism. The yoke33is disposed so as to cover the electromagnetic coil29on the outer circumferential side of the electromagnetic coil29, and also serves as a housing for the fuel injection valve1. In addition, the lower end part of the yoke33faces the outer circumferential surface of the movable iron core27avia the cylindrical body5, and the movable iron core27a, the fixed iron core25and the yoke33form a closed magnetic path through which a magnetic flux generated by energizing the electromagnetic coil29flows.

The coil spring39is set over the through hole25aof the fixed iron core25and the concave part27cof the movable iron core27ain a compressed state. The coil spring39functions as a biasing member for biasing the movable element27in the direction in which the valve body17comes in contact with the valve seat15b(valve closing direction). An adjuster (adjusting element)35is disposed on the inner side of the through hole25aof the fixed iron core25, and the end portion on the base end side of the coil spring39comes in contact with the end surface on the distal end side of the adjuster35. By adjusting the position of the adjuster35in the through hole25ain the direction along the central axis1a, the biasing force of the movable element27(that is, the valve body17) by the coil spring39is adjusted.

The adjuster35has a fuel flow passage3penetrating through the center part of the adjuster35in the direction along the central axis1a. After flowing through the fuel flow passage3of the adjuster35, fuel flows through the fuel flow passage3at the distal end side part of the through hole25aof the fixed iron core25, and then flows through the fuel flow passage3formed inside the movable element27.

An O-ring46is fitted onto the distal end part of the cylindrical body5. The O-ring46functions as a seal for securing liquid-tightness and airtightness between the inner circumferential surface of an insertion port109a(seeFIG. 5) formed in an internal combustion engine side and the outer circumferential surface of the yoke33, when the fuel injection valve1is attached to the internal combustion engine.

A resin cover47is molded in a range from the middle part to a part close to the end portion on the base end side of the fuel injection valve1. The end portion on the distal end side of the resin cover47covers a part on the base end side of the yoke33. In addition, the resin cover47covers the wiring member45, and the connector41is integrally formed by the resin cover47.

Next, operation of the fuel injection valve1will be explained.

When the electromagnetic coil29is in a non-energization state (that is, the drive current is not fed to the electromagnetic coil29), the movable element27is biased in the valve closing direction by the coil spring39, and the valve body17is in a state of being in contact with the valve seat15b(seating state). In this case, the gap6exists between the end surface on the distal end side of the fixed iron core25and the end surface on the base end side of the movable iron core27a. In the present embodiment, the distance of this gap6is equal to that of the stroke of the movable element27(that is, the valve body17).

When the electromagnetic coil29is energized, and the drive current is fed to the electromagnetic coil29, a magnetic flux is generated in the closed magnetic path formed by the movable iron core27a, the fixed iron core25and the yoke33. By this magnetic flux, magnetic attraction force is generated between the fixed iron core25and the movable iron core27awhich are opposed to each other with the gap6interposed therebetween. When this magnetic attraction force overcomes the resultant force of the biasing force by the coil spring39and fuel pressure acting on the movable element27in the valve closing direction, the movable element27starts moving in the valve opening direction. When the valve body17is separated from the valve seat15b, a gap (fuel passage) is formed between the valve body17and the valve seat15b, and fuel injection stars. In the present embodiment, when the movable element27moves by a distance equal to the gap6in the valve opening direction, and the movable iron core27acomes in contact with the fixed iron core25, the movement of the movable iron core27ain the valve opening direction is stopped, and the valve is opened, and then it becomes a stationary state.

When the energization to the electromagnetic coil29is stopped, the magnetic attraction force is lowered, and then disappears. At this stage in which the magnetic attraction force is lowered, when the magnetic attraction force becomes smaller than the biasing force of the coil spring39, the movable element27starts moving in the valve closing direction. When the valve body17comes in contact with the valve seat15b, the valve part7is closed and the valve body17becomes a stationary state.

As mentioned above, the valve body17and the valve seat15bcooperatively perform the opening/closing of the fuel passage on the upstream side of the fuel injection holes.

Next, with reference toFIG. 2andFIG. 3, the configuration of the valve part7and the fuel injection part21will be explained in detail.FIG. 2is an enlarged sectional view (corresponding to a sectional view ofFIG. 3when viewed from an arrow II-II) of the vicinity (nozzle part) of the valve part7and the fuel injection part21of the fuel injection valve1inFIG. 1.FIG. 3is a plan view of the nozzle plate21nwhen viewed from an arrow direction ofFIG. 1.

In addition,FIG. 3is a plan view when the nozzle plate21nis viewed from an inlet side of the fuel injection holes, and is a plan view on an upper end surface21nuside of the nozzle plate21n. This plan view is a drawing in which passages for swirl (fuel passages for swirl)210-1,210-2,210-3and210-4, fuel injection holes220-1,220-2,220-3and220-4and a fuel inlet300are projected onto a plane perpendicular to the central axis1a. The fuel inlet300is shown by a broken line. The upper end surface21nuis a surface facing a distal end surface15tof the valve seat member15. The end surface on the opposite side to the upper end surface21nuis referred as a lower end surface21nb.

As shown inFIG. 2, in the present embodiment, the nozzle plate21nis formed by a plate-shaped member whose both end surfaces are flat surfaces, and the upper end surface21nuand the lower end surface21nbare parallel to each other. That is, the nozzle plate21nis formed by a flat plate having uniform thickness. In the present embodiment, as shown inFIG. 3, the nozzle plate21nis configured such that the central axis1aintersects the nozzle plate21nat a center21noof the nozzle plate21n.

The distal end surface (lower end surface)15tof the valve seat member15is formed by a flat surface (plane surface) perpendicular to the central axis1a. The distal end surface15tof the valve seat member15is joined with the nozzle plate21n, and the distal end surface15tcomes in contact with the upper end surface21nuof the nozzle plate21n.

As shown inFIG. 3, the nozzle plate21nis formed with the horizontal passages (horizontal fuel passages)211-1,211-2,211-3and211-4, the swirl chambers (turning chambers)212-1,212-2,212-3and212-4, and with the fuel injection holes220-1,220-2,220-3and220-4.

The swirl chambers212-1,212-2,212-3and212-4are configured to allow fuel to flow into the fuel injection holes220-1,220-2,220-3and220-4respectively while swirling the fuel.

The horizontal passages211-1,211-2,211-3and211-4are fuel passages extending in a direction along the plate surface of the nozzle plate21n, are connected on the upstream sides of the swirl chambers212-1,212-2,212-3and212-4respectively, and are configured to supply fuel to the swirl chambers212-1,212-2,212-3and212-4respectively.

In addition, the components of the swirl passages210-1,210-2,210-3and210-4in the present embodiment are different from those of the swirl passages in the patent document 2.

Four sets of the swirl passage210-1and the fuel injection hole220-1, the swirl passage210-2and the fuel injection hole220-2, the swirl passage210-3and the fuel injection hole220-3and the swirl passage210-4and the fuel injection hole220-4are each configured similarly, and without distinguishing them, they are explained as swirl passages210, horizontal passages211, swirl chambers212and fuel injection holes220. In case where the configuration is changed in each of the sets, it will be explained appropriately.

As shown inFIG. 2, the valve seat member15is formed with the conical valve seat15bwhose diameter is reduced toward the downstream side. The downstream end of the valve seat15bis connected to the fuel inlet300. The downstream end of the fuel inlet300is opened to the distal end surface15tof the valve seat member15. The fuel inlet300forms a fuel passage for introducing fuel to the swirl passages210.

The swirl passages210are provided such that the end portions on the upstream sides of the horizontal passages211face the opening surface of the fuel inlet300to receive fuel supply from the fuel inlet300. In the present embodiment, as shown inFIG. 3, four sets of the horizontal passages211-1,211-2,211-3and211-4are independently configured, and the end portions (end portions on the inlet sides) on the upstream sides of the horizontal passages211-1,211-2,211-3and211-4are separated from each other inside the nozzle plate21n.

InFIG. 2, the nozzle plate21nformed by one plate-shaped member is formed with all of the horizontal passages211, the swirl chambers212and the fuel injection holes220. For example, the nozzle plate21ncan be formed by a plurality of plates by dividing it in a thickness direction. For example, the horizontal passages211and the swirl chambers212are formed to one plate, and the fuel injection holes220are formed to the other plate, and the nozzle plate21ncan be formed by stacking these two plates.

In addition, in the present embodiment, as shown inFIG. 2, although the fuel injection holes220are formed parallel to the central axis1a, they can be inclined at an angle larger than 0° with respect to the central axis1a. Moreover, they can be formed so as to inject fuel in a plurality of directions by making a difference in inclination direction.

In the present embodiment, as shown inFIG. 3, the swirl passage210-1and the fuel injection hole220-1form one fuel passage, the swirl passage210-2and the fuel injection hole220-2form one fuel passage, the swirl passage210-3and the fuel injection hole220-3form one fuel passage, and the swirl passage210-4and the fuel injection hole220-4form one fuel passage. The swirl passage210-1is formed of the horizontal passage211-1and the swirl chamber212-1, the swirl passage210-2is formed of the horizontal passage211-2and the swirl chamber212-2, the swirl passage210-3is formed of the horizontal passage211-3and the swirl chamber212-3, and the swirl passage210-4is formed of the horizontal passage211-4and the swirl chamber212-4.

In the embodiment, in total, four sets of the fuel passages formed of the swirl passages210and the fuel injection holes220are formed in the nozzle plate21n. Each of the four sets of the fuel passages is formed radially outward from the center21noside of the nozzle plate21ntoward outside. That is, the horizontal passages211are provided radially outward from the center21noside of the nozzle plate21toward outside and extend in the radial direction of the nozzle plate21n. In addition, the fuel passages are formed circumferentially so as to be spaced from one another at an angle interval of 90°. Moreover, in the four sets of the swirl passages210, each of the end portions on the upstream sides of the horizontal passages211is provided at an equal distance from the center21noof the nozzle plate21n.

The number of the sets of the swirl passages210and the fuel injection holes220is not limited to four, and it can be two or three, or five or more.

Here, with reference toFIG. 4, the relation between the swirl passages210and the fuel inlet300will be explained.FIG. 4is a plan view showing the relation between a swirl passage210and the fuel inlet300. This plan view is a drawing in which a swirl passage210, a fuel injection hole220and the fuel inlet300are projected onto a plane perpendicular to the central axis1a.

A horizontal passage211is connected to a swirl chamber212so as to be offset with respect to the center of the swirl chamber212. The inner circumferential wall (side wall) of the swirl chamber212is formed such that the curvature thereof becomes gradually large from the upstream side toward the downstream side in a flow direction of a swirling fuel. The inner circumferential wall (side wall) of the swirl chamber212can be formed with a fixed curvature from the upstream side toward the downstream side in the flow direction of the swirling fuel.

In the present embodiment, side wall sections (side-section side surfaces)211aand211bof the horizontal passage211is formed to extend linearly from the upstream side toward the downstream side. A side wall section (end-section side surface)211iof the end portion on the upstream side of the horizontal passage211is formed in a curved shape that is curved in the plane shown inFIG. 4. In particular, in the present embodiment, the side wall section211iis formed by a curve in a shape of a circular arc, and has a semicircular shape.

That is, in the horizontal passage211, two side surfaces (side-section side surfaces)211aand211bextending along the fuel flow direction have a linear section, and the side wall section211iformed between the two side-section side surfaces211aand211bon the upstream side has a curved section connected to the linear section of the side-section side surfaces211aand211b.

This side wall section211iis connected to the side-section side surfaces211aand211bat the place shown by a point210P1. The side wall section211iis formed with a fixed curvature (that is, a fixed curvature radius R) in a range between the end portion of the side wall section211iwhich is connected to the side-section side surface211aand the end portion of the side wall section211iwhich is connected to the side-section side surface211b. In addition, in the present embodiment, the side-section side surface211aand the side-section side surface211bof the horizontal passage211are parallel to each other from the upstream end side to the downstream end side. The diameter of the semicircle forming the side wall section211iis therefore equal to the distance between the side-section side surface211aand the side-section side surface211b, that is, equal to the passage width of the horizontal passage211.

In addition, for example, the side-section side surface211aand the side-section side surface211bcan be formed such that the distance therebetween decreases or increases from the upstream end side toward the downstream end side.

The fuel inlet300is formed in a circular shape having a center on the central axis1aof the valve. That is, the passage sectional shape of the fuel inlet300has a circular shape. In a plan view ofFIG. 4, the opening edge (broken line part shown by a reference number300) of the fuel inlet300intersects the side-section side surfaces211aand211bof the horizontal passage211at the place (point) shown by a reference sing210P2. That is, the place210P2shows a place at which the projection of the opening edge of the fuel inlet300intersects the projection of the side-section side surfaces211aand211b.

In this way, when the fuel inlet300and the horizontal passage211are projected onto a plane perpendicular to the central axis1aof the valve, the projected line of the linear section of the side-section side surfaces211aand211bof the horizontal passage211extends to the place intersecting the projected line of the opening edge of the fuel inlet300, and the upstream-side end portion of the horizontal passage211extends toward the inside of the opening edge.

Moreover, in the present embodiment, a distance dimension L1which is substantially larger than 0 (zero) is provided between the point210P1and the point210P2. The distance dimension L1of each of a plurality of the horizontal passages211-1,211-2,211-3and211-4may be different from each other. However, each of the all horizontal passages211-1,211-2,211-3and211-4has the distance dimension L1substantially larger than 0 (zero).

In a plan view shown inFIG. 4, a passage sectional area S1of the inlet opening surface of the horizontal passage211facing the fuel inlet300is larger than a passage sectional area (passage sectional area in a section taken along a line A-A ofFIG. 5) S2of the horizontal passage211on its downstream side. In the present embodiment, in a part at which the side-section side surfaces211aand211bof the horizontal passage211form a linear shape, the passage sectional area S2has a fixed size from the upstream end toward the downstream end. In case where the passage sectional area S2is changed, the passage sectional area S1is set so as to have a value (area) larger than the maximum value of the passage sectional area S2. In addition, the passage sectional area S1is a sectional area perpendicular to the valve axial center (central axis) la, and the passage sectional area S2is a sectional area perpendicular to the extending direction (direction along fuel flow) of the horizontal passage211.

FIG. 5is a plan view showing a variation of the shape of the end portion on the inlet side (end portion on the upstream side) of the horizontal passage211.

The side wall section211iof the upstream-side end portion of the horizontal passage211is not necessary to have a semicircular shape, and, for example, it may has a shape in which a linear section211icconnects a curved section211iaconnected to the side-section side surface211aand a curved section211ibconnected to the side-section side surface211b. That is, it may have a shape in which the linear section211icis connected to the side-section side surfaces211aand211bby chamfered sections having rounded shapes, or may have another shape. However, the horizontal passage211is configured on the premise that the side-section side surfaces211aand211bare formed in a linear shape and a shape section in which a passage width W211decreases toward the upstream side is included on the upstream sides of the side-section side surfaces211aand211b.

In the present variation, only the shapes of the curved section211ia, the curved section211iband the linear section211icare different from those of the above-mentioned embodiment, and the other configuration is formed similar to the above-mentioned embodiment.

The fuel inlet300is formed in the valve seat member15, and the swirl passages210are formed in the nozzle plate21n. In case where the valve seat member15and the nozzle plate21nare accurately machined without an error, and both of them are accurately attached to each other without an error, the passage sectional areas S1of a plurality of the swirl passages210are equal to each other. However, when an error occurs in the machining of the valve seat member15and the nozzle plate21n, or when an error occurs in the attachment of them, the passage sectional areas S1of a plurality of the swirl passages210are different in each of the swirl passages210, and the amount of fuel flow distributed into each of the swirl passages210becomes different.

With reference toFIG. 6andFIG. 7, an influence of a positional deviation between the valve seat member15and the nozzle plate21nwill be explained.

FIG. 6shows a plan view to explain a problem in the configuration (comparative embodiment with respect to the present embodiment) in which a plurality of swirl passages210are joined in the center part of a nozzle plate21n′.

In this comparative embodiment, four sets of horizontal passages211′ (211-1′,211-2′,211-3′,211-4′) of swirl passages210′ (210-1′,210-2′,210-3′,210-4′) are connected in the vicinity of the center of the nozzle plate21n′. Therefore the passage length of the horizontal passages211′ becomes long, and the dead volume of the fuel passage formed on the downstream side of the valve seat becomes large. However, in this comparative embodiment, even if a positional deviation occurs between the valve seat member15in which the fuel inlet300is formed and the nozzle plate21n′ in which the swirl passages210′ are formed, and the fuel inlet300deviates to a position shown by a dotted line300′ with respect to the nozzle plate21n′, it is possible to equally distribute fuel to the swirl passages210′ through the connection part of each of the swirl passages210′ which is located on the center part of the fuel inlet300.

FIG. 7is a plan view to explain a problem in the configuration (comparative embodiment with respect to the present embodiment) in which a plurality of swirl passages210″ are formed independently from each other.

In this comparative embodiment, four sets of horizontal passages211″ (211-1″,211-2″,211-3″ and211-4″) of swirl passages210″ (210-1″,210-2″,210-3″ and210-4″) are formed independently from each other on a nozzle plate21n″. However, the opening edge (broken line part shown by a reference number300) of the fuel inlet300intersects side wall sections211a″,211b″ and211i″ of each of the horizontal passages211″ at a connection place210P1″ of the side wall sections211a″ and211b″ having a linear shape and the side wall sections211i″ having a curved shape of each of the horizontal passages211″. That is, the distance dimension L1explained inFIG. 4is 0 (zero).

In this case, positional deviation occurs between the valve seat member15in which the fuel inlet300is formed and the nozzle plate21n″ in which the swirl passages210″ are formed, and when the fuel inlet300deviates to a position shown by a dotted line300′ relative to the nozzle plate21n″, in the swirl passages210-2″,210-3″ and210-4″, the opening edge of the fuel inlet300intersects the side wall sections211i″ having curved shapes of the horizontal passages211″. In the swirl passages210-2″,210-3″ and210-4″, when positional deviation occurs between the valve member15and the nozzle plate21n″, the position of the opening edge of the fuel inlet300is shifted in the region in which the side wall sections211i″ of the horizontal passages211″ are formed. In this case, as compared with a case where the opening edge position of the fuel inlet300is shifted in the side wall sections211a″ and211b″ of the horizontal passages211″, the rate of change of the passage sectional area of each of the horizontal passage211″ which faces the fuel inlet300to the amount of the positional deviation between the valve seat member15and the nozzle plate21n″ becomes large. Consequently, variation in the flow amount of fuel which flows to a plurality of the swirl passages210″ becomes large.

In the present embodiment, as explained inFIG. 4, by configuring the opening edge (a broken line part shown by a reference number300) of the fuel inlet300so as to intersect the linear-shaped side wall sections211aand211bof the horizontal passages211, even if positional deviation occurs between the valve seat member15and the nozzle plate21n, the rate of change of the passage sectional area of each of the horizontal passages211which faces the fuel inlet300can be small. That is, the rate of change of the facing surface area in each of the horizontal passages211which faces the fuel inlet300can be small. As this result, it is possible to evenly distribute fuel to a plurality of the swirl passages210formed in the nozzle plate21n, and thereby variation in in the flow amount of fuel flowing through each of the swirl passages210can be small.

In the present embodiment, in case where the severest design is performed in consideration of the positional deviation between the valve seat member15and the nozzle plate21n, there is a case where the distance dimension L1explained inFIG. 4becomes 0 (zero) in at least one swirl passage210. On the other hand, in at least one swirl passage210, a distance dimension L1substantially larger than 0 (zero) exists between the point P1and the point P2. In addition, the distance dimension L1between the point210P1and the point210P2has a value equal to 0 (zero) or larger in each of all of the swirl passages210.

That is, in a plurality of the swirl passages210in the present embodiment, all of the swirl passages210-1to210-4each have a distance dimension L1equal to 0 or larger between the connection place210P1that is a connection place of the side-section side surfaces (linear section)211aand211band the end portion side surface (curved section)211iand the intersection place210P2of the projected line of the opening edge of the fuel inlet and the projected line of the linear section. Moreover, at least one swirl passage has a distance dimension L1larger than 0 between the connection place210P1that is a connection place of the side-section side surfaces211aand211band the curved section211iand the intersection place210P2of the projected line of the opening edge of the fuel inlet and the projected line of the linear section.

All of a plurality of the horizontal passages221-1to211-4each have the distance dimension L1larger than 0 between the connection place210P1and the intersection place210P2, and consequently, it is possible to allow for a margin of machining accuracy of the nozzle plate12nand the valve seat member15, and to allow for a margin of assembling accuracy in an assembling process between the nozzle plate21nand the valve member15.

In addition, by setting the size of the passage sectional area S1to be larger than that of the passage sectional area S2, fuel can be distributed into each of the swirl passages210, and thereby variation in the flow amount of the fuel flowing to each of the swirl passages210can be small.

In the present embodiment, a configuration has been explained in which the horizontal passages211are provided radially outward from the center21noside of the nozzle plate21ntoward outside. Other than this configuration, a configuration may be applied, configuration in which the horizontal passages211extend from the outer circumferential side of the nozzle plate21ntoward the center21n, and the swirl chambers212are connected to the end portions of the horizontal passages211located at the center21noside of the nozzle plate21n. In this case, it is also configured such that the relation between the point210P1, the point210P2and the distance dimension L1explained inFIG. 4is applied to the connection state between the opening part (fuel inlet300) of the valve seat member15for introducing fuel into the horizontal passages211and the horizontal passages211.

An internal combustion engine on which a fuel injection valve according to the present invention is mounted will be explained with reference toFIG. 8.FIG. 8is a sectional view of the internal combustion engine on which the fuel injection valve1is mounted.

An engine block101of an internal combustion engine100is formed with a cylinder102, and an intake port103and an exhaust port104are provided at the top part of the cylinder102. The intake port103is provided with an intake valve105that opens and closes the intake port103, and the exhaust port104is provided with an exhaust valve106that opens and closes the exhaust port104. An intake pipe108is connected to an inlet side end part107aof an intake flow passage107communicating to the intake port103.

A fuel pipe110is connected to the fuel supply port2(seeFIG. 1) of the fuel injection valve1.

The intake pipe108is formed with an attaching part109for the fuel injection valve1, and the attaching part109is formed with an insertion port109ainto which the fuel injection valve1is inserted. The insertion port109apenetrates to the inner wall surface of the intake pipe108(intake flow passage), and the fuel injected from the fuel injection valve1inserted into the insertion port109ais injected into the intake flow passage. In a case of two-directional spray, in an internal combustion engine in which two intake ports103are provided in the engine block101, fuel injection sprays are injected toward the respective intake ports103(intake valves105).

In addition, the present invention is not limited to the above embodiment or variation, and a part of the configuration can be deleted and another configuration which is not described can be added. Moreover, the configurations described in the explanation of the above-mentioned embodiment and variation can be exchanged and added between the embodiment and the variation.

As a fuel injection valve based on the embodiment explained above, for example, the following aspects can be considered.

In a preferable aspect, a fuel injection valve includes: fuel injection holes configured to inject fuel to an outside; a valve body configured to open and close a fuel passage in cooperation with a valve seat, on upstream sides of the fuel injection holes; a valve seat member formed with the valve seat; and a nozzle plate in which a plurality of swirl passages are formed and which is connected to a distal end surface of the valve seat member, wherein the swirl passages each include: a swirl chamber for allowing fuel to be swirled to flow to a corresponding one of the fuel injection holes; and a horizontal passage which is connected to an upstream side of the swirl chamber and which supplies fuel to the swirl chamber, wherein the valve seat member is opened to the distal end surface to which the nozzle plate is connected and includes a fuel inlet which is connected to an upstream-side end portion of the horizontal passage and introduces fuel into the plurality of the swirl passages, wherein the horizontal passage includes two side-section side surfaces extending along a fuel flow direction and having a linear section, and includes, on an upstream side thereof, an end-section side surface which is formed between the two side-section side surfaces and which has a curved section connected to the linear section, wherein when the fuel inlet and the horizontal passage are projected onto a plane perpendicular to a valve axial center, a projected line of the linear section of the side-section side surfaces of the horizontal passage extends to a place intersecting a projected line of an opening edge of the fuel inlet, and the upstream-side end portion of the horizontal passage extends toward an inside of the opening edge, and wherein, in the plurality of the swirl passages, all of the swirl passages each have a distance dimension equal to 0 or larger between a connection place of the linear section and the curved section and the intersection place of the projected line of the opening edge of the fuel inlet and the projected line of the linear section, and at least one of the swirl passages has a distance dimension larger than 0 between the connection place of the linear section and the curved section and the intersection place of the projected line of the opening edge of the fuel inlet and the projected line of the linear section.

In a preferable aspect of the fuel injection valve, a passage sectional area of the horizontal passage facing the fuel inlet and connected to the fuel inlet is larger than a passage sectional area formed at the linear section of the side-section side surfaces of the horizontal passage of each of the swirl passages.

In another preferable aspect, in any of the aspects of the fuel injection valve, a shape of the fuel inlet which is projected onto the plane is a circular shape, and the upstream-side end portions of a plurality of the horizontal passages forming the plurality of the respective swirl passages are located at an equal distance from a center of the nozzle plate.

In another preferable aspect, in any of the aspects of the fuel injection valve, all of the plurality of the swirl passages each have the distance dimension larger than 0 between the connection place and the intersection place.

In another preferable aspect, in any of the aspects of the fuel injection valve, the curved section formed at the end-section side surface of each of the horizontal passages has a semicircular shape which connects the two side-section side surfaces.