Patent Description:
As a fuel pump, there has been known a fuel pump described in PTL <NUM>, for example. The high-pressure fuel supply pump described in PTL <NUM> includes a housing, an intake valve, a discharge valve, and a relief valve.

The housing has a cylinder in which a stepped cylindrical space is formed where a cylinder liner that slidably holds a plunger is accommodated and a pressurizing chamber is formed The intake valve is opened in a state where a current is not supplied to an electromagnetic solenoid, and when the current is supplied to the electromagnetic solenoid, the intake valve is opened so that a fuel is sucked into the pressurizing chamber.

The discharge valve is assembled to a discharge valve accommodating portion of the housing, and the discharge valve accommodating portion communicates with a pressurizing chamber through a fuel discharge hole. The high-pressure fuel obtained by pressurizing fuel in the pressurizing chamber is supplied to the discharge valve. The discharge valve is opened when the pressure of the supplied fuel becomes equal to or higher than a predetermined pressure, and the fuel that has passed through the discharge valve is pressure-fed to an accumulator.

A relief valve is assembled in a relief valve accommodating portion of the housing. The relief valve accommodating portion communicates with a high-pressure region on a downstream side of the discharge valve, and communicates with the pressurizing chamber through a communication passage. The relief valve is opened when the pressure of the fuel in the high-pressure region becomes equal to or higher than a specific pressure, and returns the high-pressure fuel to the pressurizing chamber.

<CIT> discloses a fuel feed pump with a relief valve mechanism having a relief valve between the pressurizing chamber and the relief chamber. A further related fuel pump is disclosed in <CIT>.

However, in the high-pressure fuel supply pump described in PTL <NUM>, a communication passage for making the discharge valve and the pressurizing chamber communicate with each other and a communication passage for making the relief valve and the pressurizing chamber communicate with each other are independently provided. As a result, in the high-pressure fuel supply pump described in PTL <NUM>, a dead volume when the pressurizing chamber is filled with the fuel is increased and hence, volumetric efficiency of the pump is lowered.

The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to provide a fuel pump capable of enhancing volumetric efficiency.

In order to solve the above problems and to achieve the object of the present invention, the fuel pump defined in Claim <NUM> is suggested. Further advantageous features are set out in the dependent claims.

According to the fuel pump having the above configuration, volumetric efficiency can be improved.

Problems, configurations, and advantageous effects other than those described above will be clarified by the following description of embodiments.

A high-pressure fuel supply pump according to a first embodiment of the present invention is described hereinafter. In the respective drawings, the identical members are denoted by the same reference numerals.

A fuel supply system that uses a high-pressure fuel supply pump (fuel pump) according to a first embodiment will be described with reference to <FIG>.

<FIG> is a view illustrating an overall configuration of the fuel supply system that uses the high-pressure fuel supply pump according to the first embodiment of the present invention.

As illustrated in <FIG>, the fuel supply system includes a high-pressure fuel supply pump (fuel pump) <NUM>, an engine control unit (ECU) <NUM>, a fuel tank <NUM>, a common rail <NUM>, and a plurality of injectors <NUM>. Components of the high-pressure fuel supply pump <NUM> are integrally incorporated in the pump body <NUM>.

Fuel in the fuel tank <NUM> is pumped up by a feed pump <NUM> that is driven in response to a signal from the ECU <NUM>. The pumped-up fuel is pressurized to an appropriate pressure by a pressure regulator (not illustrated) and is supplied to a low-pressure fuel intake port <NUM> of the high-pressure fuel supply pump <NUM> through a low-pressure pipe <NUM>.

The high-pressure fuel supply pump <NUM> pressurizes the fuel supplied from the fuel tank <NUM>, and pressure-feeds the fuel to the common rail <NUM>. A plurality of injectors <NUM> and a fuel pressure sensor <NUM> are mounted on the common rail <NUM>. The plurality of injectors <NUM> are mounted corresponding to the number of cylinders (combustion chambers), and inject fuel in response to a drive current outputted from the ECU <NUM>. The fuel supply system of the present embodiment is a so-called direct injection engine system where each injector <NUM> directly injects fuel into each cylinder of the engine.

The fuel pressure sensor <NUM> outputs detected pressure data to the ECU <NUM>. The ECU <NUM> calculates an appropriate injection fuel amount (target injection fuel length), an appropriate fuel pressure (target fuel pressure), and the like based on quantities of states of the engine (for example, a crank rotation angle, a throttle opening, an engine rotational speed, a fuel pressure, and the like) obtained from various sensors.

In addition, the ECU <NUM> controls driving of the high-pressure fuel supply pump <NUM> and driving of the plurality of injectors <NUM> on the basis of a calculation result of a fuel pressure (target fuel pressure) and the like. That is, the ECU <NUM> includes: a pump control unit that controls the high-pressure fuel supply pump <NUM>; and an injector control unit that controls the injector <NUM>.

The high-pressure fuel supply pump <NUM> includes a pressure pulsation reduction mechanism <NUM>, an electromagnetic intake valve mechanism <NUM> that is a variable capacity mechanism, a relief valve mechanism <NUM> (see <FIG>), and a discharge valve mechanism <NUM>. The fuel that flows from the low-pressure fuel intake port <NUM> reaches an intake port 31b of the electromagnetic intake valve mechanism <NUM> through the pressure pulsation reduction mechanism <NUM> and the intake passage 10b.

The fuel that flows into the electromagnetic intake valve mechanism <NUM> passes through a valve element <NUM>, flows through an intake passage 1d formed in the pump body <NUM>, and then flows into a pressurizing chamber <NUM>. A plunger <NUM> is inserted into the pressurizing chamber <NUM> in a reciprocating manner. Power is transmitted to the plunger <NUM> by way of a cam (not illustrated) of the engine, and the plunger <NUM> reciprocates.

In the pressurizing chamber <NUM>, fuel is sucked from the electromagnetic intake valve mechanism <NUM> in a downward stroke of the plunger <NUM>, and the fuel is pressurized in an upward stroke. When the fuel pressure in the pressurizing chamber <NUM> exceeds a predetermined value, the discharge valve mechanism <NUM> is opened, and the high-pressure fuel is pressure-fed to the common rail <NUM> through a discharge passage 12a. The discharge of the fuel by the high-pressure fuel supply pump <NUM> is operated by opening and closing the electromagnetic intake valve mechanism <NUM>. The opening and closing of the electromagnetic intake valve mechanism <NUM> is controlled by the ECU <NUM>.

Next, the configuration of the high-pressure fuel supply pump <NUM> will be described with reference to <FIG>.

<FIG> is a longitudinal cross-sectional view (part <NUM>) of the high-pressure fuel supply pump <NUM> as viewed in cross section orthogonal to the horizontal direction. <FIG> is a longitudinal cross-sectional view (part <NUM>) of the high-pressure fuel supply pump <NUM> as viewed in cross section orthogonal to the horizontal direction. <FIG> is a horizontal-direction cross-sectional view of the high-pressure fuel supply pump <NUM> as viewed in cross section orthogonal to a vertical direction of the high-pressure fuel supply pump <NUM>. <FIG> is a perspective cross-sectional view with a part broken away of the high-pressure fuel supply pump <NUM>.

As illustrated in <FIG>, a pump body <NUM> of the high-pressure fuel supply pump <NUM> is formed in a substantially circular columnar shape. As illustrated in <FIG> and <FIG>, the pump body <NUM> includes a first chamber 1a, a second chamber 1b, a third chamber 1c, and an intake passage 1d.

The first chamber 1a is a circular columnar space portion formed in the pump body <NUM>. A center line 1A of the first chamber 1a agrees with a center line of the pump body <NUM>. One end portion of the plunger <NUM> is inserted into the first chamber 1a. The plunger <NUM> reciprocates in the first chamber 1a. The first chamber 1a and one end of the plunger <NUM> form a pressurizing chamber <NUM>.

The second chamber 1b is a circular columnar space portion formed in the pump body <NUM>, and a center line of the second chamber 1b is orthogonal to the center line of the pump body <NUM> (first chamber 1a). The relief valve mechanism <NUM> is disposed in the second chamber 1b. Therefore, the second chamber 1b illustrates a specific example of a relief chamber according to the present invention. A diameter of the second chamber 1b is smaller than a diameter of the first chamber 1a.

The first chamber 1a and the second chamber 1b communicate with each other through a circular communication hole 1e. A diameter of the communication hole 1e is equal to the diameter of the first chamber 1a. The communication hole 1e is formed by extending one end of the first chamber 1a. A diameter of the communication hole 1e is larger than an outer diameter of the plunger <NUM>. A center line 1A of the communication hole 1e agrees with the center line of the pump body <NUM>. The center line of the communication hole 1e is orthogonal to the center line of the second chamber 1b. As illustrated in <FIG>, a diameter of the communication hole 1e is larger than a diameter of the second chamber 1b.

A third chamber 1c is a circular columnar space portion formed in the pump body <NUM>. The third chamber 1c is continuously formed with the other end of the first chamber 1a. A center line 1A of the third chamber 1c agrees with the center line 1A of the first chamber 1a and the center line of the pump body <NUM>. A diameter of the third chamber 1c is larger than the diameter of the first chamber 1a. A cylinder <NUM> that guides the reciprocation of the plunger <NUM> is disposed in the third chamber 1c.

The cylinder <NUM> is formed in a cylindrical shape, and an outer peripheral side of the cylinder <NUM> is press-fitted into the third chamber 1c of the pump body <NUM>. One end of the cylinder <NUM> is brought into contact with a top surface of the third chamber 1c (step portion formed between the first chamber 1a and the third chamber 1c). The plunger <NUM> is in brought into contact with an inner peripheral surface of the cylinder <NUM> in a slidable manner. The plunger <NUM> is guided by the cylinder <NUM> and reciprocates in the axial direction.

An O-ring <NUM> that illustrates a specific example of a seat member is interposed between a fuel pump mounting portion (not shown) and the pump body <NUM>. The O-ring <NUM> prevents engine oil from leaking to the outside of an engine (internal combustion engine) through between the fuel pump mounting portion and the pump body <NUM>.

A tappet (not illustrated) is mounted on a lower end of the plunger <NUM>. The tappet converts a rotational motion of a cam mounted on a cam shaft of the engine into a vertical motion and transmits the vertical motion to the plunger <NUM>. The plunger <NUM> is biased toward a cam (not illustrated) side by a spring <NUM> by way of a retainer <NUM>. The tappet reciprocates due to the rotation of the cam. The plunger <NUM> reciprocates together with the tappet. As a result of the reciprocation of the plunger, a volume of the pressurizing chamber <NUM> changes.

A seal holder <NUM> is disposed between the cylinder <NUM> and the retainer <NUM>. The seal holder <NUM> is formed in a cylindrical shape so as to allow the insertion of the plunger <NUM> into the seal holder <NUM>. An auxiliary chamber 17a is formed in an upper end portion of the seal holder <NUM> on a cylinder <NUM> side. In addition, the seal holder <NUM> holds a plunger seal <NUM> at a lower end portion of the seal holder <NUM> on a retainer <NUM> side.

The plunger seal <NUM> is brought into contact with an outer periphery of the plunger <NUM> in a slidable manner. The plunger seal <NUM> seals fuel in the auxiliary chamber 17a. With such a configuration, when the plunger <NUM> reciprocates, it is possible to prevent the fuel in the auxiliary chamber 17a from flowing into the engine. In addition, the plunger seal <NUM> also prevents lubricating oil (including engine oil) that lubricates sliding portions in the engine from flowing into the pump body <NUM>.

In <FIG> and <FIG>, the plunger <NUM> reciprocates in the vertical direction. When the plunger <NUM> descends, the volume of the pressurizing chamber <NUM> is increased, and when the plunger <NUM> ascends, the volume of the pressurizing chamber <NUM> is decreased. That is, the plunger <NUM> is disposed so as to reciprocate in directions of enlarging and reducing the volume of the pressurizing chamber <NUM>.

The plunger <NUM> has a large diameter portion 2a and a small diameter portion 2b. When the plunger <NUM> reciprocates, the large diameter portion 2a and the small diameter portion 2b are positioned in the auxiliary chamber 17a. Accordingly, the volume in the auxiliary chamber 17a is increased or decreased by the reciprocation of the plunger <NUM>.

The auxiliary chamber 17a communicates with a low-pressure fuel chamber <NUM> through a fuel passage 10c (see <FIG>). When the plunger <NUM> descends, fuel flows from the auxiliary chamber 17a to the low-pressure fuel chamber <NUM>, and when the plunger <NUM> ascends, fuel flows from the low-pressure fuel chamber <NUM> to the auxiliary chamber 17a. As a result, in an intake stroke or a return stroke of the high-pressure fuel supply pump <NUM>, a flow rate of fuel into and out of the pump can be reduced and hence, the pressure pulsation generated in the high-pressure fuel supply pump <NUM> can be reduced.

As illustrated in <FIG>, an intake joint <NUM> is mounted on a side surface portion of the pump body <NUM>. The intake joint <NUM> is connected to the low-pressure pipe <NUM> through which fuel supplied from the fuel tank <NUM> (see <FIG>) passes. The fuel in the fuel tank <NUM> is supplied from the intake joint <NUM> to the inside of the pump body <NUM>.

The intake joint <NUM> includes: the low-pressure fuel intake port <NUM> that is connected to the low-pressure pipe <NUM>; and an intake flow passage <NUM> that communicates with the low-pressure fuel intake port <NUM>. The fuel that has passed through the intake flow passage <NUM> passes through an intake filter <NUM> disposed in the pump body <NUM> and is supplied to the low-pressure fuel chamber <NUM>. The intake filter <NUM> removes foreign substances present in the fuel thus preventing the foreign substances from entering the high-pressure fuel supply pump <NUM>.

As illustrated in <FIG> and <FIG>, the low-pressure fuel chamber <NUM> is formed on an upper portion of the pump body <NUM> of the high-pressure fuel supply pump <NUM>. The low-pressure fuel chamber <NUM> includes a low-pressure fuel flow passage 10a and an intake passage 10b (see <FIG>). The low-pressure fuel flow passage 10a includes the pressure pulsation reduction mechanism <NUM>. When the fuel that flows into the pressurizing chamber <NUM> is again returned to the intake passage 10b through the electromagnetic intake valve mechanism <NUM> in a valve open state, the pressure pulsation occurs in the low-pressure fuel chamber <NUM>. The pressure pulsation reduction mechanism <NUM> reduces the propagation of the pressure pulsation generated in the high-pressure fuel supply pump <NUM> to the low-pressure pipe <NUM>.

The pressure pulsation reduction mechanism <NUM> is formed of a metal diaphragm damper in which an inert gas such as argon is filled. The metal diaphragm damper is formed by laminating outer peripheries of two corrugated disk-shaped metal plates to each other. The metal diaphragm damper of the pressure pulsation reduction mechanism <NUM> expands and contracts so as to absorb or reduce the pressure pulsation.

The intake passage 10b communicates with the intake port 31b (see <FIG>) of the electromagnetic intake valve mechanism <NUM>, and fuel that passes through the low-pressure fuel flow passage 10a reaches the intake port 31b of the electromagnetic intake valve mechanism <NUM> through the intake passage 10b.

As illustrated in <FIG> and <FIG>, the electromagnetic intake valve mechanism <NUM> is inserted into a lateral hole formed in the pump body <NUM>. The electromagnetic intake valve mechanism <NUM> includes: an intake valve seat <NUM> that is press-fitted into a lateral hole formed in the pump body <NUM>; a valve element <NUM>; a rod <NUM>; a rod biasing spring <NUM>; an electromagnetic coil <NUM>; and an anchor <NUM>.

The intake valve seat <NUM> is formed in a cylindrical shape, and a seating portion 31a is formed on an inner peripheral portion. An intake port 31b that reaches an inner peripheral portion from an outer peripheral portion is also formed in the intake valve seat <NUM>. The intake port 31b communicates with the intake passage 10b in the low-pressure fuel chamber <NUM> described above.

A stopper <NUM> that faces the seating portion 31a of the intake valve seat <NUM> is disposed in the lateral hole formed in the pump body <NUM>. The valve element <NUM> is disposed between the stopper <NUM> and the seating portion 31a. A valve biasing spring <NUM> is interposed between the stopper <NUM> and the valve element <NUM>. The valve biasing spring <NUM> biases the valve element <NUM> toward a seating portion 31a side.

When the valve element <NUM> is brought into contact with the seating portion 31a, the valve element <NUM> closes a communicating portion formed between the intake port 31b and the pressurizing chamber <NUM>. As a result, the electromagnetic intake valve mechanism <NUM> assumes a valve closing state. On the other hand, when the valve element <NUM> is brought into contact with the stopper <NUM>, the valve element <NUM> opens the communicating portion formed between the intake port 31b and the pressurizing chamber <NUM>. As a result, the electromagnetic intake valve mechanism <NUM> assumes a valve open state.

The rod <NUM> penetrates a cylinder hole of the intake valve seat <NUM>. One end of the rod <NUM> is brought into contact with the valve element <NUM>. The rod biasing spring <NUM> biases the valve element <NUM> in the valve opening direction which is a stopper <NUM> side by way of the rod <NUM>. One end of the rod biasing spring <NUM> engages with the other end of the rod <NUM>. The other end of the rod biasing spring <NUM> engages with a magnetic core <NUM> disposed so as to surround the rod biasing spring <NUM>.

The anchor <NUM> faces an end surface of the magnetic core <NUM>. The anchor <NUM> also engages with a flange mounted on an intermediate portion of the rod <NUM>. The electromagnetic coil <NUM> is disposed around the whole circumference of the magnetic core <NUM>. A terminal member <NUM> is electrically connected to the electromagnetic coil <NUM>, and a current flows to the electromagnetic coil <NUM> through the terminal member <NUM>.

In a non-energized state where a current is not supplied to the electromagnetic coil <NUM>, the rod <NUM> is biased in a valve opening direction by a biasing force of the rod biasing spring <NUM>. As a result, the rod <NUM> pushes the valve element <NUM> in the valve opening direction. As a result, the valve element <NUM> is separated from the seating portion 31a and is brought into contact with the stopper <NUM> and hence, the electromagnetic intake valve mechanism <NUM> assumes a valve open state. That is, the electromagnetic intake valve mechanism <NUM> is a normally open type valve that opens in a non-energized state.

When the electromagnetic intake valve mechanism <NUM> is in a valve open state, fuel in the intake port 31b passes between the valve element <NUM> and the seating portion 31a, and flows into the pressurizing chamber <NUM> passing through a plurality of fuel passing holes (not illustrated) formed in the stopper <NUM> and the intake passage 1d. In the valve open state of the electromagnetic intake valve mechanism <NUM>, the valve element <NUM> comes into contact with the stopper <NUM>, so that the position of the valve element <NUM> in the valve opening direction is restricted. In a valve open state of the electromagnetic intake valve mechanism <NUM>, a gap existing between the valve element <NUM> and the seating portion 31a is a movable range of the valve element <NUM>. That is, in a valve open state of the electromagnetic intake valve mechanism <NUM>, the gap existing between the valve element <NUM> and the seating portion 31a is a valve opening stroke.

When a current is supplied to the electromagnetic coil <NUM>, the anchor <NUM> is attracted in a valve closing direction by a magnetic attractive force of the magnetic core <NUM>. As a result, the anchor <NUM> moves against a biasing force of the rod biasing spring <NUM>, and is brought into contact with the magnetic core <NUM>. When the anchor <NUM> moves in the valve closing direction on a magnetic core <NUM> side, the rod <NUM> moves together with the anchor <NUM>. As a result, the valve element <NUM> is released from a biasing force in the valve opening direction, and moves in the valve closing direction by a biasing force of the valve biasing spring <NUM>.

Then, when the valve element <NUM> is brought into contact with the seating portion 31a of the intake valve seat <NUM>, the electromagnetic intake valve mechanism <NUM> assumes a valve closing state.

As illustrated in <FIG> and <FIG>, the discharge valve mechanism <NUM> is connected to an outlet side (downstream side) of the pressurizing chamber <NUM>. The discharge valve mechanism <NUM> includes: a discharge valve seat <NUM> that communicates with the pressurizing chamber <NUM>, a valve element <NUM> that is brought into contact with and is separable from the discharge valve seat <NUM>; a discharge valve spring <NUM> that biases the valve element <NUM> toward a discharge valve seat <NUM> side; and a discharge valve stopper <NUM> that determines a stroke (moving distance) of the valve element <NUM>.

The discharge valve seat <NUM> is formed in a substantially cylindrical shape. The discharge valve seat <NUM> has a seat passage 8a which is a shaft hole. The seat passage 8a forms a passage on a pressurizing chamber <NUM> side in the discharge valve mechanism <NUM>. A discharge valve inlet passage 1f that allows the pressurizing chamber <NUM> and the seat passage 8a to communicate with each other is formed in the pump body <NUM>. The discharge valve inlet passage 1f also communicates with the second chamber 1b (relief chamber) besides the pressurizing chamber <NUM>.

The valve element <NUM> faces an end surface of the discharge valve seat <NUM> on a side opposite to a pressurizing chamber <NUM> side.

The valve element <NUM> is biased toward a discharge valve seat <NUM> side and is pressed against the discharge valve seat <NUM> by the discharge valve spring <NUM>. When the valve element <NUM> is separated from the discharge valve seat <NUM>, fuel in the pressurizing chamber <NUM> can pass through between the valve element <NUM> and the discharge valve seat <NUM>. As a result, the discharge valve mechanism <NUM> assumes a valve open state.

The discharge valve mechanism <NUM> includes a plug <NUM> that blocks leakage of fuel to the outside. The discharge valve stopper <NUM> is press-fitted into the plug <NUM>. The plug <NUM> is joined to the pump body <NUM> by welding at a welded portion <NUM>. As illustrated in <FIG>, the discharge valve mechanism <NUM> communicates with a discharge chamber <NUM> that is opened and closed by the valve element <NUM>. The discharge chamber <NUM> is formed in the pump body <NUM>.

A lateral hole that communicates with the second chamber 1b (see <FIG>) is formed in the pump body <NUM>, and a discharge joint <NUM> is inserted into the lateral hole. The discharge joint <NUM> includes: the above discharge passage 12a that communicates with the lateral hole formed in the pump body <NUM> and the discharge chamber <NUM>; and a fuel discharge port 12b that forms one end of the discharge passage 12a. The fuel discharge port 12b of the discharge joint <NUM> communicates with the common rail <NUM>. The discharge joint <NUM> is fixed to the pump body <NUM> by welding by a welded portion 12c.

In a state where there is no difference in fuel pressure (fuel differential pressure) between the pressurizing chamber <NUM> and the discharge chamber <NUM>, the valve element <NUM> is brought into pressure contact with the discharge valve seat <NUM> by a biasing force of the discharge valve spring <NUM>. As a result, the discharge valve mechanism <NUM> assumes a valve closing state. When the fuel pressure in the pressurizing chamber <NUM> becomes larger than the fuel pressure in the discharge chamber <NUM>, the valve element <NUM> moves against the biasing force of the discharge valve spring <NUM>. As a result, the discharge valve mechanism <NUM> assumes a valve open state.

The moving direction of the valve element <NUM> in the discharge valve mechanism <NUM> is orthogonal to the direction that the plunger <NUM> reciprocates. The direction that the plunger <NUM> reciprocates corresponds to the first direction according to the present invention. The moving direction of the valve element <NUM> in the discharge valve mechanism <NUM> corresponds to the third direction according to the present invention.

When the discharge valve mechanism <NUM> is brought into a valve closed state, the (high-pressure) fuel in the pressurizing chamber <NUM> passes through the discharge valve mechanism <NUM>, and reaches the discharge chamber <NUM>. Then, the fuel that has reached the discharge chamber <NUM> is discharged to the common rail <NUM> (see <FIG>) through the fuel discharge port 12b of the discharge joint <NUM>. With the above configuration, the discharge valve mechanism <NUM> functions as a check valve that restricts the flowing direction of the fuel.

When any problem occurs in the common rail <NUM> or a member succeeding to the common rail <NUM> so that the pressure in the common rail <NUM> becomes higher than a predetermined pressure, the relief valve mechanism <NUM> illustrated in <FIG> is operated so as to return the fuel in the discharge passage 12a to the pressurizing chamber <NUM>. As described in <FIG>, the relief valve mechanism <NUM> is disposed at the position higher than the discharge valve mechanism <NUM> (see <FIG>) in the direction (vertical direction) that the plunger <NUM> reciprocates.

As illustrated in <FIG>, the relief valve mechanism <NUM> includes a relief spring <NUM>, a relief valve holder <NUM>, a valve element <NUM>, and a seat member <NUM>. The relief valve mechanism <NUM> is inserted into the pump body <NUM> from the discharge joint <NUM> and is disposed in the second chamber 1b. One end portion of the relief spring <NUM> is brought into contact with the pump body <NUM> (one end of the second chamber 1b), and the other end portion of the relief valve <NUM> is brought into contact with the relief valve holder <NUM>.

The relief valve holder <NUM> engages with the valve element <NUM>. A biasing force of the relief spring <NUM> acts on the valve element <NUM> by way of the relief valve holder <NUM>.

The valve element <NUM> is pressed by the biasing force of the relief spring <NUM> so that the valve element <NUM> closes the fuel passage in the seat member <NUM>. The moving direction of the valve element <NUM> (relief valve holder <NUM>) is orthogonal to the direction that the plunger <NUM> reciprocates. The center line of the relief valve mechanism <NUM> (the center line of the relief valve holder <NUM>) is orthogonal to the center line of the plunger <NUM>. The moving direction of the valve element <NUM> in the relief valve mechanism <NUM> corresponds to the second direction according to the present invention.

The seat member <NUM> has a fuel passage that faces the valve element <NUM>. A portion of the fuel passage formed in the seat member <NUM> on a side opposite to the valve element <NUM> communicates with the discharge passage 12a. The valve element <NUM> is brought into contact (close contact) with the seat member <NUM> so as to close the fuel passage. With such a configuration, the movement of fuel between the pressurizing chamber <NUM> (upstream side) and the seat member <NUM> (downstream side) is blocked.

When the pressure in the common rail <NUM> or a member succeeding to the common rail <NUM> is increased, a difference between a pressure of the fuel on a seat member <NUM> side (discharge chamber <NUM>) and a pressure of the fuel in the pressurizing chamber <NUM> exceeds a set value. Accordingly, the fuel on the seat member <NUM> side presses the valve element <NUM>, and moves the valve element <NUM> against a biasing force of the relief spring <NUM>. As a result, the relief valve mechanism <NUM> is opened so that the fuel in the discharge chamber <NUM> and the discharge passage 12a returns to the pressurizing chamber <NUM> through the fuel passage formed in the seat member <NUM>. In this manner, the pressure for opening the valve element <NUM> is determined based on a biasing force of the relief spring <NUM>.

Next, the positional relationship among the relief valve mechanism <NUM>, the discharge valve mechanism <NUM>, and the pressurizing chamber <NUM> will be described.

As illustrated in <FIG> and <FIG>, as viewed from the direction that the plunger <NUM> reciprocates, the moving direction of the valve element <NUM> (see <FIG>) in the relief valve mechanism <NUM> differs from the moving direction of the valve element <NUM> in the discharge valve mechanism <NUM>. That is, as viewed from the direction that the plunger <NUM> reciprocates, the moving direction of the valve element <NUM> in the relief valve mechanism <NUM> intersects with the moving direction of the valve element <NUM> in the discharge valve mechanism <NUM>. As a result, the discharge valve mechanism <NUM> and the relief valve mechanism <NUM> can be disposed at positions that do not overlap with each other in the direction that the plunger <NUM> reciprocates. Accordingly, downsizing of the pump body <NUM> can be realized by effectively making use of the space in the pump body <NUM>.

As illustrated in <FIG>, the moving direction of the valve element <NUM> in the discharge valve mechanism <NUM> is the first radial direction of the pump body <NUM>, and the moving direction of the valve element <NUM> in the relief valve mechanism <NUM> is the second radial direction that differs from the first radial direction of the pump body <NUM>. An angle at which the first radial direction and the second radial direction illustrated in <FIG> intersect with each other is smaller than <NUM> degrees. However, the angle at which the first radial direction and the second radial direction intersect with each other may be approximately <NUM> degrees. As viewed from the direction along which the plunger <NUM> reciprocates, the discharge valve mechanism <NUM> and the relief valve mechanism <NUM> are disposed in a direction where the moving direction of the valve element <NUM> and the moving direction of the valve element <NUM> intersect with each other.

As illustrated in <FIG> and <FIG>, the relief valve mechanism <NUM> is disposed at the position that overlaps with the pressurizing chamber <NUM> in the reciprocating direction of the plunger <NUM> and the moving direction of the valve element <NUM> of the relief valve mechanism <NUM>. With such a configuration, it is unnecessary to form a passage for making the relief valve mechanism <NUM> and the pressurizing chamber <NUM> communicate with each other. As a result, a dead volume of the pressurizing chamber <NUM> can be reduced compared with a case where it is necessary to form a passage for making the relief valve mechanism <NUM> and the pressurizing chamber <NUM> communicate with each other. Accordingly, the volumetric efficiency of the pressurizing chamber <NUM> can be improved.

The volumetric efficiency is a ratio of a discharge amount of fuel discharged from the discharge valve mechanism <NUM> with respect to a moving distance from a bottom dead center of the plunger <NUM> where a volume of the pressurizing chamber <NUM> becomes the largest to a top dead center of the plunger <NUM> where the volume of the pressurizing chamber <NUM> becomes the smallest. The bottom dead center of the plunger <NUM> is the position where the plunger <NUM> is at the lowermost end (cam side of the engine). The top dead center of the plunger is the position where the plunger <NUM> is at the uppermost end.

As illustrated in <FIG>, as viewed from the direction that the plunger <NUM> reciprocates and the direction that is orthogonal to the moving direction of the valve element <NUM> of the relief valve mechanism <NUM>, the relief valve mechanism <NUM> overlaps with the entire region of the pressurizing chamber <NUM> parallel to the moving direction of the valve element <NUM> of the relief valve mechanism <NUM>. With such a configuration, fuel that passes through the relief valve mechanism <NUM> can be efficiently returned to the pressurizing chamber <NUM>.

As illustrated in <FIG> and <FIG>, the discharge valve mechanism <NUM> is disposed at the position that overlaps with the relief valve mechanism <NUM> as viewed in the moving direction of the valve element <NUM> of the discharge valve mechanism <NUM>. With such a configuration, a length of the pump body <NUM> in the direction that the plunger <NUM> reciprocates (a length of the pump body <NUM> in the axial direction) can be shortened. Accordingly, downsizing of the pump body <NUM> can be realized.

Further, a lower end L1 of the second chamber 1b (relief chamber) in which the relief valve mechanism <NUM> is disposed is arranged at a position closer to the plunger <NUM> in the reciprocating direction of the plunger <NUM> than the upper end L2 of the seat passage 8a in the discharge valve mechanism <NUM>. Further, an upper end of the seat passage 8a in the discharge valve mechanism <NUM> is higher than an upper surface of the plunger <NUM> (see <FIG>) that is positioned at the top dead center.

As illustrated in <FIG>, an upper end of the relief valve mechanism <NUM> is disposed at a position remoter from the plunger <NUM> than an upper end of the discharge valve mechanism <NUM> in the reciprocating direction of the plunger <NUM>. Further, as illustrated in <FIG>, the relief valve mechanism <NUM> is disposed at the position that overlaps with the discharge valve mechanism <NUM> as viewed in the horizontal direction orthogonal to the reciprocating direction of the plunger <NUM>. With such a configuration, a length of the pump body <NUM> in the direction that the plunger <NUM> reciprocates (a length of the pump body <NUM> in the axial direction) can be shortened. Accordingly, downsizing of the pump body <NUM> can be realized.

In the present embodiment, the first chamber 1a and the second chamber 1b formed in the pump body <NUM> partially overlap with each other. The discharge valve inlet passage 8a directly communicates with the first chamber 1a and the second chamber 1b. As a result, the dead volume of the pressurizing chamber <NUM> can be reduced, and the downsizing of the pump body <NUM> can be realized.

Conventionally, the discharge valve inlet passage communicates only with the first chamber. In this case, if the plunger that is positioned at the top dead center blocks the discharge valve inlet passage, a sufficient amount of fuel does not flow into the discharge valve mechanism. Therefore, conventionally, it is necessary to secure a space in the pump body in the direction that the plunger reciprocates, and to dispose the discharge valve inlet passage at the position where the discharge valve inlet passage is not closed by the plunger located at the top dead center.

On the other hand, in the high-pressure fuel supply pump <NUM> according to the present embodiment, the discharge valve inlet passage 8a communicates with not only the first chamber 1a but also the second chamber 1b. Accordingly, even if a space is not secured in the direction that the plunger <NUM> reciprocates in the pump body <NUM>, it is possible to allow a sufficient amount of fuel to flow into the discharge valve mechanism. In addition, the configuration of the passage that communicates with the first chamber 1a can be simplified and hence, a working cost can be reduced. Furthermore, the discharge valve inlet passage 8a can be formed with a large diameter, a pressure loss is reduced. Accordingly, this configuration can also contribute to the enhancement of performance.

When holes such as the first chamber 1a, the second chamber 1b, the communication hole 1e and the like are formed in the pump body <NUM> by working, undesired protrusions (burrs) are formed on worked surfaces. If the protrusions (burrs) are left as it is, a dimensional error occurs with respect to the holes and hence, adverse effects such as a defect that a component cannot be mounted or an operator is injured when the operator touches the protrusion (burr). Therefore, it is necessary to remove the protrusions (burrs). In the above-described embodiment, the diameter of the communication hole 1e is equal to the diameter of the first chamber 1a. Therefore, the working of the communication hole 1e can be performed easily, and the protrusions (burrs) can be easily removed. In addition, it is possible to prevent the shape of the pump body <NUM> from becoming complicated. Therefore, the productivity of the pump body <NUM> and the high-pressure fuel supply pump <NUM> can be improved, and a cost can be reduced. By increasing the diameter of the discharge valve inlet passage 8a, the hole (passage) can be easily worked and, at the same time, the burrs can be easily removed. As a result, the quality of the high-pressure fuel supply pump <NUM> can be improved.

The diameter of the communication hole 1e is equal to the diameter of the first chamber 1a. Accordingly, it is possible to allow the fuel to easily flow from the relief valve <NUM> into the pressurizing chamber <NUM> and hence, the relief performance can be improved. Furthermore, the relief valve is directly incorporated in the second chamber 1b formed in the pump body <NUM>. Accordingly, a housing (seat member) for housing components that form the relief valve can be omitted and hence, the number of components can be reduced whereby a cost can be reduced.

Next, the manner of operation of the high-pressure fuel pump according to the present embodiment will be described with reference to <FIG> and <FIG>.

In <FIG>, when the plunger <NUM> descends and the electromagnetic intake valve mechanism <NUM> is opened, the fuel flows from the intake passage 1d into the pressurizing chamber <NUM>. Hereinafter, a stroke in which the plunger <NUM> descends is referred to as an intake stroke. On the other hand, when the plunger <NUM> ascends and the electromagnetic intake valve mechanism <NUM> is closed, the fuel in the pressurizing chamber <NUM> is pressurized, passes through the discharge valve mechanism <NUM>, and is pressure-fed to the common rail <NUM> (see <FIG>). Hereinafter, a stroke in which the plunger <NUM> ascends is referred to as a rising stroke.

As described above, when the electromagnetic intake valve mechanism <NUM> is closed during the rising stroke, the fuel sucked into the pressurizing chamber <NUM> is pressurized during the intake stroke. As a result, the discharge valve mechanism <NUM> is opened, and the fuel in the pressurizing chamber <NUM> is discharged to a common rail <NUM> side. On the other hand, when the electromagnetic intake valve mechanism <NUM> is opened during the rising stroke, the fuel in the pressurizing chamber <NUM> is pushed back toward an intake passage 1d side. Therefore, the fuel in the pressurizing chamber <NUM> is not discharged to the common rail <NUM> side. In this manner, the discharge of the fuel by the high-pressure fuel supply pump <NUM> is operated by opening and closing the electromagnetic intake valve mechanism <NUM>. The opening and closing of the electromagnetic intake valve mechanism <NUM> is controlled by the ECU <NUM>.

In the intake stroke, the volume of the pressurizing chamber <NUM> is increased, and the fuel pressure in the pressurizing chamber <NUM> is decreased. As a result, a fluid differential pressure between the intake port 31b and the pressurizing chamber <NUM> (hereinafter, referred to as a "fluid differential pressure before and after the valve element <NUM>") is decreased. When the biasing force of the rod biasing spring <NUM> becomes larger than the fluid differential pressure before and after the valve element <NUM>, the rod <NUM> moves in the valve opening direction. Then, the valve element <NUM> is separated from the seating portion 31a of the intake valve seat <NUM>, and the electromagnetic intake valve mechanism <NUM> assumes a valve open state.

When the electromagnetic intake valve mechanism <NUM> assumes a valve open state, fuel in the intake port 31b passes between the valve element <NUM> and the seating portion 31a, and flows into the pressurizing chamber <NUM> after passing through a plurality of fuel passing holes (not illustrated) formed in the stopper <NUM>. In a valve open state of the electromagnetic intake valve mechanism <NUM>, the valve element <NUM> is brought into contact with the stopper <NUM> and hence, the position of the valve element <NUM> in the valve opening direction is restricted. A gap existing between the valve element <NUM> and the seating portion 31a in a valve open state of the electromagnetic intake valve mechanism <NUM> is a movable range of the valve element <NUM>. This movable range is referred to as a valve open stroke.

After the intake stroke is completed, the process proceeds to the rising stroke. At this stage of the operation, the electromagnetic coil <NUM> remains in a non-energized state and hence, a magnetic attractive force does not act between the anchor <NUM> and the magnetic core <NUM>. To the valve element <NUM>, a biasing force in the valve opening direction corresponding to a difference in biasing force between the rod biasing spring <NUM> and the valve biasing spring <NUM>, and a pressing force in the valve closing direction by a fluid force generated when the fuel flows back from the pressurizing chamber <NUM> to the low-pressure fuel flow passage 10a act.

In this state, in order to allow the electromagnetic intake valve mechanism <NUM> to maintain a valve open state, the difference between the biasing force of the rod biasing spring <NUM> and the biasing force of the valve biasing spring <NUM> is set larger than the fluid force. The volume of the pressurizing chamber <NUM> decreases as the plunger <NUM> ascends. Therefore, the fuel sucked into the pressurizing chamber <NUM> passes again between the valve element <NUM> and the seating portion 31a and is returned to the intake port 31b. Accordingly, there is no possibility that the pressure in the pressurizing chamber <NUM> is increased. This stroke is referred to as a return stroke.

In the return stroke, when a control signal from the ECU <NUM> (see <FIG>) is applied to the electromagnetic intake valve mechanism <NUM>, a current flows into the electromagnetic coil <NUM> via the terminal member <NUM>. When a current flows into the electromagnetic coil <NUM>, a magnetic attractive force acts between the magnetic core <NUM> and the anchor <NUM>, and the anchor <NUM> (rod <NUM>) is attracted to the magnetic core <NUM>. As a result, the anchor <NUM> (rod <NUM>) moves in the valve closing direction (direction away from the valve element <NUM>) against a biasing force of the rod biasing spring <NUM>.

When the anchor <NUM> (rod <NUM>) moves in the valve closing direction, the valve element <NUM> is released from a biasing force in the valve opening direction. As a result, the valve element <NUM> moves in the valve closing direction by a biasing force of the valve biasing spring <NUM> and a fluid force generated by the fuel that flows into the intake passage 10b. Then, when the valve element <NUM> is brought into contact with the seating portion 31a of the intake valve seat <NUM> (when the valve element <NUM> is seated on the seating portion 31a), the electromagnetic intake valve mechanism <NUM> assumes a valve closing state.

After the electromagnetic intake valve mechanism <NUM> assumes a valve closing state, the fuel in the pressurizing chamber <NUM> is pressurized as the plunger <NUM> ascends. When the fuel in the pressurizing chamber <NUM> reaches or exceeds a predetermined pressure, the fuel passes through the discharge valve mechanism <NUM> and is discharged to the common rail <NUM> (see <FIG>). This stroke is referred to as a discharge stroke. That is, the upward stroke from the bottom dead center to the top dead center of the plunger <NUM> includes a return stroke and a discharge stroke. By controlling the timing of energizing the electromagnetic coil <NUM> of the electromagnetic intake valve mechanism <NUM>, an amount of high-pressure fuel to be discharged can be controlled.

If the timing of energizing the electromagnetic coil <NUM> is made earlier, the ratio of the return stroke during the rising stroke becomes smaller, and the ratio of the discharge stroke becomes larger. As a result, an amount of fuel returned to the intake passage 10b is decreased, and an amount of fuel discharged at a high pressure is increased. On the other hand, if the timing of energizing the electromagnetic coil <NUM> is delayed, a ratio of the return stroke during the rising stroke is increased, and a ratio of the discharge stroke is decreased. As a result, an amount of fuel that is returned to the intake passage 10b is increased, and an amount of fuel discharged at a high pressure is decreased. By controlling the timing of energizing the electromagnetic coil <NUM>, an amount of fuel to be discharged at a high pressure can be controlled to an amount that an engine (internal combustion engine) requires.

A high-pressure fuel supply pump according to a second embodiment of the present invention is described hereinafter. A point that makes the high-pressure fuel supply pump according to the second embodiment differ from the high-pressure fuel supply pump <NUM> according to the first embodiment is the position at which a discharge valve mechanism <NUM> is disposed. Therefore, in the description made hereinafter, the position of the discharge valve mechanism <NUM> is described, and the description of the configurations and the manner of operation common to the high-pressure fuel supply pump <NUM> according to the first embodiment is omitted.

Next, the positional relationship among a relief valve mechanism <NUM>, a discharge valve mechanism <NUM>, and a pressurizing chamber <NUM> is described with reference to <FIG> and <FIG>. <FIG> is a longitudinal cross-sectional view of the high-pressure fuel supply pump according to the second embodiment as viewed in cross section orthogonal to the horizontal direction. <FIG> is a perspective cross-sectional view with a part broken away of the high-pressure fuel supply pump according to the second embodiment.

The high-pressure fuel supply pump <NUM> according to the second embodiment has the same configuration as the high-pressure fuel supply pump <NUM> according to the first embodiment. As illustrated in <FIG>, as viewed from the direction that a plunger <NUM> reciprocates, the moving direction of a valve element <NUM> in a relief valve mechanism <NUM> differs from the moving direction of a valve element <NUM> in a discharge valve mechanism <NUM>. That is, as viewed from the direction that the plunger <NUM> reciprocates, the moving direction of the valve element <NUM> in the relief valve mechanism <NUM> intersects with the moving direction of the valve element <NUM> in the discharge valve mechanism <NUM>.

As illustrated in <FIG>, the relief valve mechanism <NUM> is disposed at the position that overlaps with the pressurizing chamber <NUM> in the reciprocating direction of the plunger <NUM> and the moving direction of the valve element <NUM> of the relief valve mechanism <NUM>. As illustrated in <FIG> and <FIG>, the discharge valve mechanism <NUM> is disposed at the position that overlaps with the relief valve mechanism <NUM> as viewed in the moving direction of the valve element <NUM> of the discharge valve mechanism <NUM>.

As illustrated in <FIG>, an upper end of the relief valve mechanism <NUM> and an upper end of the discharge valve mechanism <NUM> are set substantially at the same height in the reciprocating direction of the plunger <NUM>. Further, as illustrated in <FIG>, the relief valve mechanism <NUM> is disposed at the position that overlaps with the discharge valve mechanism <NUM> as viewed in the horizontal direction orthogonal to the reciprocating direction of the plunger <NUM>.

Further, as viewed from the moving direction of the valve element <NUM> of the relief valve mechanism <NUM>, the discharge valve mechanism <NUM> overlaps with an entire region of the relief valve mechanism <NUM> in a direction that the plunger <NUM> reciprocates. With such a configuration, a length of the pump body <NUM> in the direction that the plunger <NUM> reciprocates (a length of the pump body <NUM> in the axial direction) can be more shortened than the length of the pump body <NUM> in the first embodiment. Accordingly, downsizing of the pump body <NUM> can be realized.

As described above, the high-pressure fuel supply pump (fuel pump) according to the above-described embodiments includes: the pump body <NUM> (pump body) that has the pressurizing chamber <NUM> (pressurizing chamber) and the discharge chamber <NUM> (discharge chamber); the plunger <NUM> (plunger) that reciprocates in the pressurizing chamber <NUM>; and the discharge valve mechanism <NUM> (discharge valve mechanism) that discharges the fuel in the pressurizing chamber <NUM> to the discharge chamber <NUM>. Further, the high-pressure fuel supply pump includes a relief valve mechanism <NUM> (relief valve mechanism) that opens when a difference between a pressure of fuel in the discharge chamber <NUM> and a pressure of fuel in the pressurizing chamber <NUM> exceeds a predetermined value, and returns the fuel in the discharge chamber <NUM> to the pressurizing chamber <NUM>. As viewed from the first direction along which the plunger <NUM> reciprocates, the discharge valve mechanism <NUM> and the relief valve mechanism <NUM> are disposed in a direction where the moving directions of the respective valve elements <NUM>, <NUM> (valves) intersect with each other.

The relief valve mechanism <NUM> is disposed at the position that overlaps with the pressurizing chamber <NUM> in the first direction and in the second direction that is the moving direction of the valve element <NUM> of the relief valve mechanism <NUM>.

As a result, the discharge valve mechanism <NUM> and the relief valve mechanism <NUM> can be disposed at positions that do not overlap with each other in the first direction. As a result, the space in the pump body <NUM> can be effectively used, and the downsizing of the pump body <NUM> can be realized. Further, it is unnecessary to form a passage for making the relief valve mechanism <NUM> and the pressurizing chamber <NUM> communicate with each other. As a result, a dead volume of the pressurizing chamber <NUM> can be reduced compared with a case where a passage for making the relief valve mechanism <NUM> and the pressurizing chamber <NUM> communicate with each other is provided. Accordingly, the volumetric efficiency of the pressurizing chamber <NUM> can be improved.

In the high-pressure fuel supply pumps (fuel pumps) according to the above-described embodiments, the discharge valve mechanism <NUM> is disposed at the position that overlaps with the relief valve mechanism <NUM> (relief valve mechanism) as viewed from the third direction that is the moving direction of the valve element <NUM> (valve) in the discharge valve mechanism <NUM> (discharge valve mechanism). With such a configuration, a length of the pump body <NUM> (pump body) in the first direction (a length of the pump body <NUM> in the axial direction) can be shortened. Accordingly, downsizing of the pump body <NUM> can be realized.

In the high-pressure fuel supply pump (fuel pump) according to the above-described embodiment, the lower end L1 of the second chamber 1b (relief chamber) in which the relief valve mechanism <NUM> (relief valve mechanism) is disposed is disposed at the position closer to the plunger <NUM> (plunger) in the first direction than the upper end L2 of the seat passage 8a (passage on the pressurizing chamber side) in the discharge valve mechanism <NUM> (discharge valve mechanism). With such a configuration, a length of the pump body <NUM> (pump body) in the first direction (a length of the pump body <NUM> in the axial direction) can be shortened. Accordingly, downsizing of the pump body <NUM> can be realized.

In the high-pressure fuel supply pump (fuel pumps) according to the above-described embodiments, the discharge valve mechanism <NUM> (discharge valve mechanism) and the relief valve mechanism <NUM> (relief valve mechanism) may be disposed such that the moving directions of the respective valve elements <NUM>, <NUM> (valves) are disposed approximately orthogonal to each other as viewed from the first direction. As a result, the discharge valve mechanism <NUM> and the relief valve mechanism <NUM> can be disposed in a spaced-apart manner from each other thus preventing the interference between the discharge valve mechanism <NUM> and the relief valve mechanism <NUM> As a result, the space in the pump body <NUM> can be effectively used and hence, the downsizing of the pump body <NUM> can be realized.

In the high-pressure fuel supply pumps (fuel pumps) according to the above-described embodiments, the relief valve mechanism <NUM> (relief valve mechanism) is disposed at the position that overlaps with the discharge valve mechanism <NUM> ( discharge valve mechanism) as viewed from the horizontal direction orthogonal to the first direction. With such a configuration, a length of the pump body <NUM> (pump body) in the first direction (a length of the pump body <NUM> in the axial direction) can be shortened. Accordingly, downsizing of the pump body <NUM> can be realized.

In the high-pressure fuel supply pump (fuel pump) according to the above-described second embodiment, the discharge valve mechanism <NUM> ( discharge valve mechanism) overlaps with the entire region of the relief valve mechanism <NUM> (relief valve mechanism) in the first direction as viewed from the second direction. With such a configuration, a length of the pump body <NUM> in the first direction (a length of the pump body <NUM> in the axial direction) can be more shortened than the length of the pump body <NUM> in the first embodiment. Accordingly, downsizing of the pump body <NUM> can be realized.

In the high-pressure fuel supply pump (fuel pump) according to the above-described first embodiment, the upper end of the relief valve mechanism <NUM> (relief valve mechanism) is disposed remoter from the plunger (<NUM>) (plunger) than the upper end of the discharge valve mechanism <NUM> (discharge valve mechanism) in the first direction. As a result, the discharge valve mechanism <NUM> is disposed closer to the plunger <NUM> side in the first direction than the relief valve mechanism <NUM>. It is necessary to set the relief valve mechanism <NUM> at the position higher than the top dead center of the plunger <NUM> in order to avoid the interference between the relief valve mechanism <NUM> and the plunger <NUM>. Therefore, by disposing the discharge valve mechanism <NUM> on the plunger <NUM> side in the first direction than the relief valve mechanism <NUM>, it is possible to suppress the pump body <NUM> from becoming elongated in the first direction.

In the high-pressure fuel supply pumps (fuel pumps) according to the above-described embodiments, the relief valve mechanism <NUM> (relief valve mechanism) overlaps with the entire region of the pressurizing chamber <NUM> (pressurizing chamber) in the second direction as viewed from the direction orthogonal to the first direction and the second direction. With such a configuration, fuel that passes through the relief valve mechanism <NUM> can be efficiently returned to the pressurizing chamber <NUM>.

In the high-pressure fuel supply pump (fuel pump) according to the above-described embodiment, the upper end of the seat passage 8a (passage on the pressurizing chamber side) in the discharge valve mechanism <NUM> (discharge valve mechanism) is higher than the upper surface of the plunger <NUM> positioned at the top dead center. With such a configuration, it is possible to prevent the plunger <NUM> positioned at the top dead center from clogging the seat passage 8a. As a result, it is possible to prevent the plunger <NUM> from blocking the discharge of the fuel by the discharge valve mechanism <NUM>.

The embodiments of the fuel pump of the present invention have been described above including the manners of operation and the advantageous effects. However, the fuel pump of the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the invention described in the claims. Further, the above-described embodiments have been described in detail for facilitating the understanding of the present invention. However, the embodiments are not necessarily limited to the fuel pump that includes all configurations described above.

For example, in the above-described embodiment, the moving direction of the valve element <NUM> in the electromagnetic intake valve mechanism <NUM> is set to the second radial direction that is equal to the moving direction of the valve element <NUM> in the relief valve mechanism <NUM> (see <FIG>). However, the moving direction of the valve element in the relief valve according to the present invention may be different from the moving direction of the valve element in the electromagnetic intake valve. For example, in the fuel pump according to the present invention, the moving direction of the valve element in the relief valve, the moving direction of the valve element in the electromagnetic intake valve, and the moving direction of the valve element in the discharge valve may all be set different from each other.

Claim 1:
A fuel pump comprising:
a pump body (<NUM>) including a pressurizing chamber (<NUM>), a discharge chamber (<NUM>) and a relief chamber (1b);
a plunger (<NUM>) adapted to reciprocate in the pressurizing chamber;
a discharge valve mechanism (<NUM>) adapted to discharge fuel in the pressurizing chamber to the discharge chamber; and
a relief valve mechanism (<NUM>) disposed in the relief chamber (1b) and adapted to open and return fuel in the discharge chamber to the pressurizing chamber when a difference between a pressure of the fuel in the discharge chamber and a pressure of the fuel in the pressurizing chamber exceeds a set value,
wherein
the discharge valve mechanism and the relief valve mechanism are arranged in a direction that moving directions of a valve (<NUM>) of the discharge valve mechanism and a valve (<NUM>) of the relief valve mechanism intersect with each other as viewed from a first direction that is a direction in which the plunger reciprocates, and
the relief valve mechanism is disposed at a position that overlaps with the pressurizing chamber in the first direction and in a second direction that is a moving direction of the valve in the relief valve mechanism,
characterized in that
the discharge valve mechanism comprises a discharge valve inlet passage (1f) directly communicating with the pressurizing chamber and the relief chamber.