WO2018225479A1

WO2018225479A1 - High-pressure fuel pump

Info

Publication number: WO2018225479A1
Application number: PCT/JP2018/019239
Authority: WO
Inventors: 雅史根本; 山田　裕之; 悟史臼井; 高橋　由起夫
Original assignee: 日立オートモティブシステムズ株式会社
Priority date: 2017-06-09
Filing date: 2018-05-18
Publication date: 2018-12-13
Also published as: JP2020128700A

Abstract

The purpose of the present invention is to provide a high-pressure fuel pump configured so that pressure pulsation occurring in low-pressure piping can be reduced using a low-cost structure. This high-pressure fuel pump comprises: a pressurizing chamber for pressurizing fuel; an electromagnetic suction valve mechanism disposed upstream of the pressurizing chamber and regulating the rate of flow supplied to the pressurizing chamber; and a pump housing provided with suction piping. The high-pressure fuel pump further comprises a valve which is disposed upstream of the electromagnetic suction valve mechanism, is mounted to the outlet surface of a low-pressure flow passage for allowing fuel flowing thereinto from the suction piping to flow therethrough, and is configured so that the fuel flows in the downstream direction.

Description

High pressure fuel pump

The present invention relates to a high-pressure fuel pump that pumps fuel to a fuel injection valve of an internal combustion engine, and more particularly, to a high-pressure fuel pump that includes an electromagnetic intake valve mechanism that adjusts the amount of fuel to be discharged.

Among internal combustion engines such as automobiles, in a direct injection type in which fuel is directly injected into a combustion chamber, a high-pressure fuel pump having an electromagnetic intake valve mechanism for increasing the pressure of the fuel and discharging a desired fuel flow rate is widely used. It is used.

In the following Patent Document 1, a damper as a pressure pulsation reducing mechanism for reducing low pressure pulsation in a high pressure fuel pump, and a check valve provided on the upstream side of the damper to prevent the pressure pulsation from spreading to the low pressure pipe are disclosed. Disclosure. The pressure pulsation on the low pressure side is generated by a reciprocating sliding movement of the pressurizing member (plunger) in the cylinder.

WO2016-056333

However, the above prior art has the following problems.
A low pressure pipe that connects the fuel tank of the vehicle and the inlet (intake joint) of the high pressure fuel pump and a low pressure passage that houses the pressure pulsation reducing mechanism are always hydraulically connected. Therefore, the pressure pulsation reducing mechanism cannot absorb all the pressure pulsations in the low pressure passage, and in order to prevent the pressure pulsation from propagating in the low pressure pipe, the fuel flow in one direction ( There is provided a check valve that restricts the direction from the low-pressure pump side to the inside of the high-pressure fuel pump.

However, in Patent Document 1, there is a problem that the check valve has a large volume and cannot be installed depending on the shape and size of the suction joint. Here, if the check pipe cannot be installed in the case where the metal pipe part and the rubber hose or the resin hose are used together in the low pressure pipe, the strength of the connection part may not be able to withstand pressure pulsation. Or in order to ensure the intensity | strength of a connection part, there existed a possibility that production cost might increase.

An object of the present invention is to provide a high-pressure fuel pump that reduces pressure pulsation generated in low-pressure piping with an inexpensive structure.

In order to solve the above problems, according to the present invention, a pressurizing chamber that pressurizes fuel, an electromagnetic suction valve mechanism that is disposed upstream of the pressurizing chamber and controls a flow rate supplied to the pressurizing chamber, and an intake A high-pressure fuel pump including a pump housing provided with a pipe, disposed on the upstream side of the electromagnetic suction valve mechanism, and attached to an outlet surface of a low-pressure flow path through which the fuel flowing in from the suction pipe flows. And a valve configured to allow fuel to flow.

According to the present invention configured as described above, it is possible to provide a high-pressure fuel pump that reduces pressure pulsation generated in low-pressure piping with an inexpensive structure. Other configurations, operations, and effects of the present invention will be described in detail in the following examples.

1 is a longitudinal sectional view of a high-pressure fuel pump according to a first embodiment of the present invention. 1 is a cross-sectional view of a high-pressure fuel pump according to a first embodiment of the present invention. It is another longitudinal cross-sectional view of the high pressure fuel pump by the 1st Example of this invention, and has shown the state which the check valve is closed. It is another longitudinal cross-sectional view of the high pressure fuel pump by the 1st Example of this invention, and has shown the state in which the non-return valve is open. 1 is an overall configuration diagram of a high-pressure fuel system to which a high-pressure fuel pump according to the present embodiment is applied. 1 is an example of a reed valve according to a first embodiment of the present invention. It is a longitudinal cross-sectional view of the high pressure fuel pump by 2nd Example of this invention, and has shown the state which the non-return valve has closed. It is a longitudinal cross-sectional view of the high pressure fuel pump by 2nd Example of this invention, and has shown the state in which the non-return valve is open.

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

FIG. 5 shows an overall configuration diagram of a high-pressure fuel system to which the high-pressure fuel pump of this embodiment is applied. The configuration and operation of the high pressure fuel system will be described with reference to FIG. The portion surrounded by a broken line indicates a main body of a high-pressure fuel pump (hereinafter referred to as a high-pressure fuel pump), and the mechanisms and components shown in the broken line indicate that they are incorporated in the pump housing 1. The fuel in the fuel tank 20 is pumped up by the feed pump 21 based on a signal from the engine control unit 27 (hereinafter referred to as ECU), pressurized to an appropriate feed pressure, and passed through the suction pipe 28 to the low pressure fuel inlet of the high pressure fuel pump. 10a. The fuel that has passed through the suction joint 10a reaches the suction port 31b of the electromagnetic suction valve 300 constituting the variable capacity mechanism via the damper chamber (10b, 10c) formed by the pressure pulsation reduction mechanism 9 and the suction passage 10d.

The fuel that has flowed into the electromagnetic suction valve 300 passes through the suction valve 30 and flows into the pressurizing chamber 11. The reciprocating power of the plunger 2 is given to the plunger 2 by the cam mechanism 93 of the engine, and the reciprocating motion of the plunger 2 sucks fuel from the suction valve 30 part during the downward stroke of the plunger 2 and pressurizes the fuel during the upward stroke. Then, the fuel is pumped through the discharge valve mechanism 8 to the common rail 23 to which the pressure sensor 26 is mounted, and the injector 24 injects the fuel into the engine based on a signal from the ECU 27.

The high-pressure fuel pump discharges the fuel flow rate so as to obtain a desired supply fuel by a signal from the ECU 27 to the electromagnetic suction valve.
The configuration and operation of the high-pressure fuel pump will be described with reference to FIGS. FIG. 1 is a longitudinal sectional view of the fuel supply pump, and FIG. 2 is a horizontal sectional view of the fuel supply pump as viewed from above. FIG. 3 is a longitudinal sectional view of the fuel supply pump as viewed from a different direction from FIG. 1 and shows a state where the check valve is closed. FIG. 4 is the same cross section as FIG. 3, but shows a state where the check valve is open.

As shown in FIG. 1, the fuel supply pump is attached to a metal damper 9, a pump housing 1 (pump main body) in which a damper chamber (10 b, 10 c) that houses the metal damper 9 is formed, and the pump body 1. The damper cover 14 that covers the damper chamber (10b, 10c) and holds the metal damper 9 between the pump body 1 and the holder that is fixed to the damper cover 14 and holds the metal damper 9 from the opposite side of the damper cover 14 And a member 9a. The holding member 9 a is disposed between the metal damper 9 and the pump body 1, and holds the metal damper 9 from the pump body 1 side.

Generally, a high-pressure fuel pump is in close contact with the plane of a cylinder head 90 of an internal combustion engine using a flange 1e provided in the pump housing 1, and is fixed with a plurality of bolts (not shown). As shown in FIG. 1, an O-ring 61 is fitted into the pump housing 1 for sealing between the cylinder head 90 and the pump housing 1 to prevent engine oil from leaking to the outside.

The pump housing 1 is provided with a cylinder 6 which guides the reciprocating motion of the plunger 2 and has an end formed in a bottomed cylindrical shape so as to form a pressurizing chamber 11 therein. Further, the pressurizing chamber 11 is annularly formed on the outer peripheral side so as to communicate with an electromagnetic suction valve mechanism 300 (see FIG. 2) for supplying fuel and a discharge valve mechanism 8 for discharging fuel from the pressurizing chamber 11 to the discharge passage. And a plurality of communicating holes 6b for communicating the annular groove and the pressurizing chamber.

The cylinder 6 is press-fitted with the pump housing 1 on the outer peripheral side thereof, and is sealed so that the fuel pressurized in the pressurizing chamber 11 does not leak to the low pressure side. Further, the pump housing 1 is deformed radially inward so as to come into contact with the large-diameter portion bottom surface 6a of the large-diameter portion from the lower side, and the cylinder 6 is pressed upward in the drawing to fix the cylinder 6.

At the lower end of the plunger 2, there is provided a tappet 92 that converts the rotational motion of the cam mechanism 93 attached to the camshaft of the internal combustion engine into vertical motion and transmits it to the plunger 2. The plunger 2 is pressure-bonded to the tappet 92 by the spring 4 through the retainer 15. Thereby, the plunger 2 can be reciprocated up and down with the rotational movement of the cam mechanism 93.

Further, the plunger seal 13 held at the lower end of the inner periphery of the seal holder 7 is installed in a state in which the plunger 2 is slidably in contact with the outer periphery of the plunger 2 in the lower part of the cylinder 6 in the figure, and the plunger 2 has slid. At this time, the fuel in the sub chamber 7a is sealed to prevent the fuel from flowing into the internal combustion engine. At the same time, lubricating oil (including engine oil) for lubricating the sliding portion in the internal combustion engine is prevented from flowing into the pump housing 1.

A suction joint 51 is attached to the pump housing 1. The suction joint 51 is connected to a low-pressure pipe that supplies fuel from the fuel tank 20 of the vehicle, and the fuel is supplied from here to the inside of the high-pressure fuel pump. The suction filter 52 in the suction joint 51 or the pump housing 1 serves to prevent foreign matter existing between the fuel tank 20 and the low pressure fuel inlet 10a from being absorbed into the high pressure fuel pump by the flow of fuel.

The electromagnetic suction valve mechanism 300 includes a coil 43 through which a drive current flows when energized from a terminal 46. When the coil 43 is energized, a magnetic circuit is formed by the magnetic core 39 and the anchor portion 36, and a magnetic attractive force is generated between the magnetic core 39 and the anchor portion 36, thereby generating a force attracted to each other. The movable part rod 35 and the anchor part 36 are configured as separate members. The rod 35 is slidably held in the axial direction on the inner peripheral side of the rod guide, and the inner peripheral side of the anchor portion 36 is slidably held on the outer peripheral side of the rod 35. The anchor portion 36 has one or more through holes 36a penetrating in the axial direction of the component in order to move freely and smoothly in the axial direction in the fuel, and eliminates the restriction of movement due to the pressure difference before and after the anchor portion as much as possible. .

A rod urging spring 40 is disposed on the inner peripheral side of the fixed core 39 and urges the rod 35 in the valve opening direction (right direction in FIGS. 1 and 2). Since the rod 35 contacts the suction valve 30 on the side opposite to the rod biasing spring 40, a biasing force is applied in the direction in which the suction valve is pulled away from the suction valve seat portion 31a, that is, in the valve opening direction of the suction valve.

The anchor portion biasing spring 41 is inserted into a central bearing portion having a cylindrical diameter provided on the center side of the rod guide, and is arranged to apply a biasing force to the anchor portion 36 in the direction of the rod collar portion while maintaining the same axis.

The fuel that has passed through the low pressure fuel suction port 10a reaches the suction port 31b of the electromagnetic suction valve 300 via the pressure pulsation reducing mechanism 9 and the low pressure fuel flow path 10d.

As shown in FIG. 2, a discharge valve mechanism 8 is provided at the outlet of the pressurizing chamber 11. The discharge valve mechanism 8 includes a discharge valve sheet 8a, a discharge valve 8b that contacts and separates from the discharge valve sheet 8a, a discharge valve spring 8c that biases the discharge valve 8b toward the discharge valve sheet 8a, a discharge valve 8b, and a discharge valve sheet 8a. The discharge valve seat 8a and the discharge valve holder 8d are joined by welding at a contact portion 8e to form an integral discharge valve mechanism 8. A stepped portion for forming a stopper for regulating the stroke of the discharge valve 8b is provided inside the discharge valve holder 8d.

As shown in FIG. 2, the discharge valve mechanism 8 provided at the outlet of the pressurizing chamber 11 has a discharge valve sheet 8a, a discharge valve 8b that contacts and separates from the discharge valve sheet 8a, and a discharge valve 8b toward the discharge valve sheet 8a. And a discharge valve stopper 8d that determines the stroke (movement distance) of the discharge valve 8b. The discharge valve stopper 8d and the pump housing 1 are joined by welding at the contact portion 8e to shut off the fuel and the outside.

When there is no fuel differential pressure in the pressurizing chamber 11 and the discharge valve chamber 12a, the discharge valve 8b is pressed against the discharge valve seat 8a by the urging force of the discharge valve spring 8c and is in a closed state. Only when the fuel pressure in the pressurizing chamber 11 becomes higher than the fuel pressure in the discharge valve chamber 12a, the discharge valve 8b opens against the discharge valve spring 8c. The high-pressure fuel in the pressurizing chamber 11 is discharged to the common rail 23 through the discharge valve chamber 12a, the fuel discharge passage 12b, and the fuel discharge port 12.

When the discharge valve 8b is opened, it comes into contact with the discharge valve stopper 8d, and the stroke is limited. Accordingly, the stroke of the discharge valve 8b is appropriately determined by the discharge valve stopper 8d. As a result, the stroke is too large, and it is possible to prevent the fuel discharged at high pressure into the discharge valve chamber 12a from flowing back into the pressurization chamber 11 again due to the delay in closing the discharge valve 8b. Can be suppressed. Further, when the discharge valve 8b repeats opening and closing movements, the discharge valve 8b is guided by the outer peripheral surface of the discharge valve stopper 8d so that the discharge valve 8b moves only in the stroke direction. By doing so, the discharge valve mechanism 8 becomes a check valve that restricts the flow direction of fuel.

The pressurizing chamber 11 includes a pump housing 1 (pump body 1), an electromagnetic suction valve mechanism 300, a plunger 2, a cylinder 6, and a discharge valve mechanism 8.

When the plunger 2 moves in the direction of the cam 93 due to the rotation of the cam 93 and is in the suction stroke state, the volume of the pressurizing chamber 11 increases and the fuel pressure in the pressurizing chamber 11 decreases. If the fuel pressure in the pressurizing chamber 11 becomes lower than the pressure in the suction passage 10d in this process, the suction valve 30 is in an open state, and therefore the communication hole provided in the pump housing 1 passes through the opening portion of the suction valve 30. 1a passes through the cylinder outer peripheral passage 6b and flows into the pressurizing chamber 11.

After the plunger 2 completes the intake stroke, the plunger 2 starts to move upward and moves to the upward stroke. Here, the electromagnetic coil 43 remains in a non-energized state and no magnetic biasing force acts. The rod biasing spring 40 is set to have a biasing force necessary and sufficient to keep the suction valve 30 open in a non-energized state. The volume of the pressurizing chamber 11 decreases with the compression movement of the plunger 2. In this state, the fuel once sucked into the pressurizing chamber 11 passes through the opening of the intake valve 30 in the valve opening state again, and the suction passage 10 d. Therefore, the pressure in the pressurizing chamber does not increase. This process is called a return process.

In this state, when a control signal from the engine control unit 27 (hereinafter referred to as ECU) is applied to the electromagnetic intake valve 300, a current flows through the electromagnetic coil 43 via the terminal 46. Then, the magnetic biasing force overcomes the biasing force of the rod biasing spring 40 and the rod 35 moves away from the suction valve 30. As a result, the suction valve 30 is closed by the biasing force of the suction valve biasing spring 33 and the fluid force caused by the fuel flowing into the suction passage 10d. After closing the valve, the fuel pressure in the pressurizing chamber 11 rises with the upward movement of the plunger 2, and when the pressure exceeds the pressure at the fuel discharge port 12, high-pressure discharge of fuel is performed via the discharge valve mechanism 8, and to the common rail 23. Supplied. This stroke is called a discharge stroke.

That is, the ascending stroke while the plunger 2 moves from the lower starting point to the upper starting point includes a returning stroke and a discharging stroke. And the quantity of the high-pressure fuel discharged can be controlled by controlling the energization timing to the coil 43 of the electromagnetic suction valve 300. If the timing of energizing the electromagnetic coil 43 is advanced, the ratio of the return stroke during the compression stroke is small and the ratio of the discharge stroke is large. That is, the amount of fuel returned to the suction passage 10d is small and the amount of fuel discharged at high pressure is large. On the other hand, if the energization timing is delayed, the ratio of the return stroke during the compression stroke is large and the ratio of the discharge stroke is small. That is, the amount of fuel returned to the suction passage 10d is large, and the amount of fuel discharged at high pressure is small. The energization timing to the electromagnetic coil 43 is controlled by a command from the ECU 27.
With the configuration described above, the amount of fuel discharged at high pressure can be controlled to the amount required by the internal combustion engine by controlling the energization timing to the electromagnetic coil 43.

In the damper chamber (10b, 10c), which is a low pressure fuel chamber, a pressure pulsation reducing mechanism 9 for reducing and reducing the pressure pulsation generated in the high pressure fuel pump from spreading to the fuel pipe 28 is installed. When the fuel flowing into the pressurizing chamber 11 is returned to the suction passage 10d (suction port 31b) again through the opened valve body 30 for capacity control, the fuel returned to the suction passage 10d causes the damper chamber ( 10b, 10c) pressure pulsations occur. The pressure pulsation reduction mechanism 9 provided in the damper chamber (10b, 10c) is formed of a metal diaphragm damper in which two corrugated disk-shaped metal plates are bonded together on the outer periphery and an inert gas such as argon is injected therein. The pressure pulsation is absorbed and reduced by the expansion and contraction of the metal damper. The holder 9 a is a mounting bracket for fixing the metal damper to the inner peripheral portion of the pump housing 1.

The plunger 2 has a large-diameter portion 2a and a small-diameter portion 2b, and the volume of the sub chamber 7a increases or decreases as the plunger reciprocates. The sub chamber 7a communicates with the damper chamber (10b, 10c) through the fuel passage 1d. When the plunger 2 descends, fuel flows from the sub chamber 7a to the damper chamber (10b, 10c), and when it rises, fuel flows from the damper chamber (10b, 10c) to the sub chamber 7a.

As a result, the flow rate of fuel into and out of the pump during the intake stroke or return stroke of the pump can be reduced, and the pressure pulsation generated inside the high-pressure fuel pump is reduced.
Hereinafter, the generation mechanism of the pulsation (hereinafter referred to as low pressure pressure pulsation) on the low pressure side (low pressure side and upstream from the pressurizing chamber 11) generated along with the reciprocating motion of the plunger 2 and the mechanism for reducing it will be described in detail. To do.

In the suction stroke, the volume of the pressurizing chamber 11 is increased by the downward movement of the plunger 2, and the volume of the sub chamber 7a is decreased. Therefore, the fuel flows into the pressurizing chamber 11 and flows out from the sub chamber 7a. The high-pressure fuel pump must inhale fuel by this difference. In the return stroke / discharge stroke (pressurization stroke), the volume of the pressurizing chamber 11 decreases and the volume of the sub chamber 7a increases due to the upward movement of the plunger 2. In the return stroke, a part of the fuel flowing out from the pressurizing chamber 11 flows into the sub chamber 7a, and the high pressure fuel pump must return the rest. In the discharge stroke (pressurization stroke), the fuel in the pressurizing chamber 11 is pressurized and discharged. Since the fuel flows into the sub chamber 7a, the high-pressure fuel pump must suck in the fuel for the inflow.

The pressure pulsation reducing mechanism 9 has a function of reducing the low pressure pulsation generated by the above three strokes. However, since the pressure pulsation reducing mechanism 9 and the low pressure fuel inlet 10a are completely hydraulically connected, the pressure pulsation reducing mechanism 9 is low in pressure. Part or most of the pressure pulsation propagates to the vehicle side via the low-pressure fuel inlet 10a.

Therefore, as shown in FIG. 3, in this embodiment, a reed valve 71 is disposed in the suction joint 51 through which the fuel flowing in from the fuel pipe 28 flows, and the low pressure flow path 73 to which the suction joint 51 is connected. A pressure pulsation propagation preventing mechanism including a pin 72 for fixing the reed valve is provided. As described above, the high-pressure fuel pump of this embodiment includes the pressurizing chamber 11 that pressurizes the fuel, and the electromagnetic suction valve mechanism 300 that is disposed upstream of the pressurizing chamber 11 and controls the flow rate supplied to the pressurizing chamber 11. And a pump housing 1 provided with a suction pipe (suction joint 51). The high-pressure fuel pump is disposed on the upstream side of the electromagnetic suction valve mechanism 300, and is attached to the outlet surface 73a of the low-pressure channel 73 through which the fuel flowing in from the suction pipe (suction joint 51) flows, so that the fuel flows in the downstream direction. Equipped with a valve. In this embodiment, the reed valve 71 is employed as a valve, but the present invention is not necessarily limited to this. In the axial sectional view (FIG. 3) of the high-pressure fuel pump, the reed valve 71 is preferably arranged so as to be flush with the bottom surface of the pump housing 1 that forms the damper chamber (10b, 10c).

As shown in FIG. 4, when the fuel flows in, the reed valve 71 is opened and fuel is supplied into the pump. When the fuel inflow is finished, the reed valve 71 is closed as shown in FIG. 3, and the fuel is prevented from flowing back from the inside of the pump through the suction joint 51 to the fuel pipe 28.
FIG. 6 is a view for explaining the structure of the reed valve 71 of this embodiment. The reed valve 71 provided with a fixing hole 71c is fixed to a recess (1b, 1d) provided in the pump housing 1 by a pin 72 in FIGS. In the fixed state, the reed valve is pressed against the pump housing 1. The valve of the present embodiment is made of a thin plate having elasticity, and one end 71d is fixed to an outlet surface 73a of a low-pressure channel 73 formed inside the pump housing 1, so that the other end 71b opens and closes. It is.
More specifically, the above-described valve is a reed valve 71 that includes a first circular portion 71d and a second circular portion 71b, and the second circular portion 71b opens and closes when the first circular portion 71d is fixed. It is desirable. The above-described valve is a reed valve 71 in which the first circular portion 71d and the second circular portion 71b are formed of an integral member, and the second circular portion 71b is opened and closed by fixing the first circular portion 71d. desirable. In addition, in this valve, the first circular portion 71d and the second circular portion 71b are formed as an integral member, and a fixing portion (pin 72) is inserted into a hole portion 71c formed in the central portion of the first circular portion 71d. Therefore, the reed valve 71 is preferably fixed. Here, the pin 72 is adopted as the fixing portion, but a screw may be used instead, or the pin 72 may be fixed by a method such as welding.

Further, as described above, this valve is fixed by the fixing portion (pin 72) being disposed in the recess portion 1b formed in the pump housing 1, and the protrusion of the fixing portion (pin 72) being inserted into the recess portion 1d. It is desirable that the reed valve 71 be used. 3 and 4, the recesses (1b, 1d) are formed so as to be recessed downward on the upper surface (bottom surface) of the pump housing 1. Specifically, the recesses (1b, 1d) are formed to be recessed downward with respect to the upper end 1c of the pump housing 1. The recesses (1 b, 1 d) are formed so as to be recessed downward on the upper surface (bottom surface) of the pump housing 1, and the flow path of the low pressure flow path 73 in which the second circular portion 71 b is formed inside the pump housing 1. It is desirable that they be arranged so as to overlap the center and the low-pressure channel axis direction.

As described above, in this embodiment, since the valve structure is composed of the reed valve 71, the pin 72, and the pump housing 1, the pump housing 1 also serves as a seat portion necessary for constituting the valve structure. Therefore, it is not necessary to increase the number of parts, and the pulsation reducing mechanism can be configured at low cost. Further, since the open / close valve of the reed valve 71 is regulated by the valve itself, a valve guide mechanism is not required, and since the reed valve 71 itself is a thin plate, the valve structure can be configured compactly.

When the fuel tries to flow from the low pressure fuel inlet 10a toward the pressure pulsation reducing mechanism 9, the reed valve 71 is opened and the fuel flows into the high pressure fuel pump. At this time, if the elasticity of the reed valve is excessive, the reed valve 71 does not open or the pressure loss may increase even if the reed valve is opened. The valve opening pressure is determined by the elasticity of the reed valve, but it is desirable that the valve opening pressure be small. Therefore, the shape and material must be set so that the elastic force matches the valve opening pressure.

When fuel is about to flow from the pressure pulsation reducing mechanism 9 toward the low pressure fuel inlet 10a, the reed valve 71 comes into contact with the pump housing 1 and closes the outlet 73 of the low pressure flow path serving as a fuel passage provided in the pump housing 1. To do. With such a structure, the reed valve 71 functions as a check valve that allows the flow of fuel only from the low-pressure fuel intake port 10a toward the pressure pulsation reducing mechanism 9.

In this embodiment, since it is necessary to suck fuel from the low pressure fuel suction port 10a in the suction stroke and the discharge stroke, the reed valve 71 which is a pressure pulsation propagation preventing mechanism is opened. In the return stroke, fuel tends to flow out from the low-pressure fuel inlet 10a to the low-pressure pipe outside the high-pressure fuel pump. However, the reed valve 71 closes due to its elastic force, thus preventing the fuel from flowing out. The fuel that could not flow out is absorbed by the pressure pulsation reducing mechanism 9. With the configuration as described above, it is possible to prevent part or most of the low-pressure pressure pulsation from propagating to the vehicle side outside the high-pressure fuel pump through the low-pressure fuel inlet 10a.

Further, at the timing of shifting from the suction stroke to the return stroke (timing at which the plunger 2 shifts from the downward movement to the upward movement), the fuel in the low-pressure fuel inlet 10a and the low-pressure pipe flows in the direction of flowing into the high-pressure fuel pump. Have momentum. Therefore, immediately after the start of the return stroke (immediately after the plunger 2 starts to move up), the fuel still flows from the low-pressure fuel suction port 10a toward the pressure pulsation reducing mechanism 9. On the other hand, in the reed valve 71, since the valve closing force is only the elastic force of the valve, there is a time delay in shifting from the valve opening state to the valve closing state.

Thus, immediately after the start of the return stroke, the fuel flows into the high-pressure fuel pump from the low-pressure fuel inlet 10a. The present inventors have found a problem that if the fuel flows in at such an unintended timing, the low pressure pulsation inside the high pressure fuel pump becomes too large after the reed valve 71 is closed. This tendency is particularly noticeable during high-speed operation of the internal combustion engine, that is, when the reciprocating speed of the plunger 2 is high. This is because when the speed of the reciprocating motion of the plunger 2 is large, the momentum of the fuel immediately after the start of the return stroke is increased.

Therefore, in this embodiment, even when the reed valve 71 closes and comes into contact with the pump housing 1, the low-pressure fuel suction port 10a and the pressure pulsation reducing mechanism 9 are not completely shut off hydraulically and are very slight. The fuel is allowed to leak from the reed valve 71 toward the low-pressure fuel inlet 10a. That is, the reed valve 71 of the present embodiment is made of a thin metal plate having elasticity, and is configured such that the other end 71b is opened and closed by fixing one end 71d, and the other end 71b is always in communication with the hole. (Not shown) is formed. Although not shown in FIG. 6, it is desirable that the hole formed in the other end 71b is located at the center of the other end 71b and has a smaller diameter than the fixing hole 71c. As a result, the fuel that has flowed in due to the momentum of the fuel at the beginning of the return stroke flows out of the high-pressure fuel pump during the remaining return stroke, and this problem is solved.

Specifically, there is a method of enabling leakage by setting the surface roughness of the contact surface between the reed valve 71 and the pump housing 1 to be large. As described above, there is also a method of making a very small hole in the center of the other end 71b of the reed valve 71. In addition, when the mass of the check valve is large, a collision sound generated by the opening / closing valve of the check valve is large, which may cause annoying noise to the vehicle occupant. However, in this embodiment, since the lightweight reed valve 71 is employed as described above, it is possible to prevent the noise from being generated in this way.

As described above, according to the present embodiment, the pressure pulsation generated in the low-pressure pipe is reliably reduced while maintaining the downsizing of the high-pressure fuel pump by effectively installing the check valve in a limited space, and It is possible to keep the quietness of the combustion system.

低圧 Low-pressure piping often uses a metal pipe and a rubber hose or resin hose. Therefore, there has been a problem that the strength of the connecting portion cannot withstand pressure pulsation, or a high cost is required to secure the strength of the connecting portion. On the other hand, this problem can be solved by adopting the above-described configuration of the present embodiment. That is, according to the present embodiment, the low-pressure pipe can be configured so that the strength of the connecting portion can sufficiently withstand pressure pulsation when the metal pipe portion and the rubber hose or the resin hose are used in combination. Alternatively, the cost for securing the strength of the connecting portion can be kept low. Furthermore, the quietness of the vehicle can be maintained without causing the low-pressure piping to vibrate due to pressure pulsation to generate abnormal noise.

Example 2 of the present invention will be described with reference to FIGS. Since the basic configuration is the same as that of the first embodiment, only differences from the first embodiment will be described here.

The difference from the first embodiment is that the suction joint 51 is attached to the upper part of the damper cover 14 (pump housing cover). That is, in this embodiment, the fuel that has flowed into the high-pressure fuel pump from the low-pressure fuel suction port 10a passes through the suction joint 51 and the damper cover 14 to which the suction joint 51 is connected, and enters the low-pressure fuel chambers (

damper chambers

10b and 10c). Directly supplied without going through the pump housing 1. Further, the damper cover 14 is provided with a recess 14 a for fixing the reed valve 71. The reed valve 71 is disposed on the housing cover 14 and is fixed to the reed valve 71 by a pin 72 that fixes the reed valve. The rest is the same as the first embodiment.

Therefore, as shown in FIGS. 7 and 8, the high-pressure fuel pump of this embodiment includes a valve 71 attached to the surface 14b opposite to the suction pipe (suction joint 51) of the pump housing cover 14. is there. In the present embodiment, the reed valve 71 is disposed in the low pressure flow path 73 to which the suction joint 51 is connected, but is not limited to the reed valve.

In the axial sectional view of the high-pressure fuel pump (FIG. 7), the reed valve 71 is disposed so as to be flush with the lower surface 14b (bottom surface) of the damper cover 14 forming the damper chamber (10b, 10c). Is desirable.

As shown in FIGS. 7 and 8, in the valve described above, the first circular portion 71d and the second circular portion 71b are formed as an integral member, and the fixed portion is fixed to the hole portion 71c formed in the central portion of the first circular portion 71d. The reed valve 71 is fixed by inserting the (pin 72) and inserting the protrusion of the fixing portion (pin 72) into the recess 14a formed in the pump housing cover 14. Further, the recessed portion 14 a is formed so as to be recessed upward in the lower surface of the upper portion of the pump housing cover 14.

The recessed portion 14a is formed to be recessed upward on the lower surface of the upper portion of the pump housing cover 14, and the second circular portion 71b overlaps with the flow path center of the suction pipe (suction joint 51) in the suction pipe axial direction. Placed in.

Even in such a configuration, the effect of suppressing the propagation of the pressure pulsation that cannot be absorbed by the low pressure pulsation reducing mechanism 9 to the low pressure piping can be obtained in the same manner as in the first embodiment.

Further, the problem that the low pressure pressure pulsation increases due to excessive intake of fuel into the high pressure fuel pump due to the momentum of the fuel at the moment of transition from the intake stroke to the return stroke is solved by the same method as in the first embodiment. it can.

DESCRIPTION OF SYMBOLS 1 ... Pump housing, 2 ... Plunger, 4 ... Spring, 6 ... Cylinder, 7 ... Seal holder, 8 ... Discharge valve mechanism, 9 ... Pressure pulsation reduction mechanism, 10a ... Low pressure fuel inlet, 10b * 10c ... Low pressure fuel chamber, DESCRIPTION OF SYMBOLS 10d ... Suction passage, 11 ... Pressurizing chamber, 12 ... Fuel discharge port, 13 ... Plunger seal, 14 ... Housing cover, 15 ... Retainer, 28 ... Suction piping, 30 ... Suction valve, 51 ... Suction joint, 71 ... Reed valve 72 ... fixed part 73 ... low pressure flow path 300 ... electromagnetic suction valve mechanism.

Claims

A pressurizing chamber that pressurizes fuel; an electromagnetic suction valve mechanism that is disposed upstream of the pressurizing chamber and controls a flow rate supplied to the pressurizing chamber; and a pump housing provided with a suction pipe. In high pressure fuel pump,
A high-pressure fuel pump provided with a valve that is arranged on the upstream side of the electromagnetic suction valve mechanism, is attached to an outlet surface of a low-pressure flow path through which fuel that flows in from the suction pipe flows, and is configured to flow in the downstream direction.
The high-pressure fuel pump according to claim 1,
The valve is a high-pressure fuel pump attached to a surface of the pump housing cover opposite to the suction pipe.
2. The high-pressure valve according to claim 1, wherein the valve is a reed valve that is configured by a thin plate having elasticity, and that one end is fixed to an outlet face of a low-pressure channel formed inside the pump housing, and the other end opens and closes. Fuel pump.
3. The high-pressure fuel pump according to claim 1 or 2, wherein the valve is a reed valve that is constituted by a thin plate having elasticity, and the other end is opened and closed by fixing one end.
The valve according to any one of claims 1 to 3, wherein the valve is formed of a thin plate having elasticity, the one end is fixed, and the other end is a reed valve that opens and closes. Formed high-pressure fuel pump.
4. The reed valve according to claim 1, wherein the valve includes a first circular portion and a second circular portion, and the second circular portion is opened and closed by fixing the first circular portion. High pressure fuel pump.
4. The valve according to claim 1, wherein the first circular portion and the second circular portion are formed of an integral member, and the second circular portion opens and closes when the first circular portion is fixed. High pressure fuel pump that is a reed valve.
4. The valve according to claim 1, wherein the first circular portion and the second circular portion are formed of an integral member, and a fixed portion is inserted into a hole formed in a central portion of the first circular portion. High pressure fuel pump that is a reed valve that is fixed by being done.
3. The valve according to claim 2, wherein the first circular portion and the second circular portion are formed of an integral member, and a fixing portion is inserted into a hole formed in a central portion of the first circular portion. A high-pressure fuel pump, which is a reed valve fixed by being inserted into a recess formed in the pump housing cover.
10. The high-pressure fuel pump according to claim 9, wherein the recess is formed to be recessed upward on the lower surface of the upper portion of the pump housing cover.
In Claim 9, the said recessed part is formed so that it may dent upward in the lower surface of the upper part of the said pump housing cover, and the said 2nd circular part may overlap with the flow path center of the said suction piping in the suction piping axial direction. High pressure fuel pump arranged in the.
4. The valve according to claim 3, wherein the first circular portion and the second circular portion are formed as an integral member, a fixing portion is inserted into a hole formed in a central portion of the first circular portion, and the fixing is performed. A high pressure fuel pump which is a reed valve which is fixed by being inserted into a recess formed in the pump housing.
13. The high-pressure fuel pump according to claim 12, wherein the recessed portion is formed to be recessed downward on an upper surface of the pump housing.
13. The flow path center and low pressure of the low pressure flow path according to claim 12, wherein the recessed portion is formed to be recessed downward on the upper surface of the pump housing, and the second circular portion is formed inside the pump housing. A high-pressure fuel pump arranged so as to overlap in the flow axis direction.