JPH10159670A - Fuel pressuring pump for fuel injection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the starting performance of an engine by eliminating the generation of a vapor in an intake passage, as well as maintaining the pressure inside the intake passage from a feed pump to a pump main body at a high pressure, when the engine is stopped. SOLUTION: An intake route is composed of an intake passage 5 communicating with the intake check valves 21 of a pump main body 1A, and an intake piping 40 connected to a feed pump 2, and a pressure maintaining check valve 41 is assembled into a connection plug 26 in order to connect the piping 40 to the intake passage 5. The pressure maintaining check valve 41 furnishes a valve element 42 which consists of an elastic body, and when the pressure at the intake piping 40 side is more than a set pressure, the valve element 42 opens its inner passage. When the engine and the feed pump 2 are stopped, and the pressure in the intake piping 40 is made lower than the set pressure, the valve element 42 of the pressure maintaining check valve 41 closes its inner passage 44, so as to block the further pressure reduction in the intake piping 40.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel pressurizing pump of a fuel injection device for pressurizing fuel sent from a motor-driven supply pump to a high pressure by the driving force of an engine. The present invention relates to a fuel pressurizing pump that has been improved so as to enhance the pressure increasing performance.

[0002]

2. Description of the Related Art Fuel injection devices used in automobiles and the like are:
The fuel is pressurized to a high pressure by a fuel pressurizing pump driven by the engine, and the pressurized fuel is injected into the engine by an injector. As the fuel pressurizing pump, a plunger-type pump is often used in which a plurality of plungers are sequentially pressed by a swash plate that is driven and rotated, and the respective plungers are moved forward and backward to suck and discharge fuel.

In such a fuel injection device, the fuel must be quickly pressurized when the engine is started, and if the fuel pressure is delayed, it is difficult to quickly start the engine. One of the causes of the delay in boosting the pressure is that when the engine is stopped (when the supply pump is stopped), the fuel pressure in the suction passage from the supply pump to the suction check valve of the pump body decreases, and the fuel pressure decreases. It is conceivable that the generated vapor delays the pressure rise.However, at present, it relies exclusively on the operation of the suction check valve of the pump body, and no other special measures have been taken for this problem of fuel pressure drop. .

[0004] This related technique is disclosed, for example, in Japanese Patent Laid-Open Publication No. Hei.
No. 339,179.

[0005]

The suction check valve used in the pump body of the fuel pressurizing pump frequently opens and closes during the operation of the pump.
It is inevitably made with an emphasis on its durability, and it is difficult to expect sealing performance that can completely shut off the suction passage and the inside of the pump body when the engine is stopped (when the supply pump is stopped). For this reason, in the conventional fuel pressurizing pump, when the engine is stopped for a long time, the pressure in the suction passage inevitably passes through the suction check valve to the pump body, further passes through the sliding gap of the plunger, etc., to the drain passage. As a result, the suction passage could not be maintained at a high pressure.

[0006] Therefore, the present invention enables the internal pressure of the suction passage from the supply pump to the pump body to be maintained at a high pressure when the engine is stopped, thereby eliminating the generation of vapor in the suction passage and starting the engine. It is an object of the present invention to provide a fuel pressurizing pump for a fuel injection device capable of reliably increasing the fuel pressure.

[0007]

According to a first aspect of the present invention, a fuel supplied from a motor-driven supply pump is driven by an engine while a suction check valve and a discharge valve are provided. In a fuel pressurizing pump of a fuel injection device which pressurizes with a pump body having a check valve and supplies the same to an injector, a pressure on a supply pump side is equal to or higher than a set pressure in a suction passage from the supply pump to a suction check valve of the pump body. A pressure holding check valve that opens at the time of is provided. When the supply pump stops when the engine is stopped and the pressure on the supply pump side of the suction passage falls below the set pressure, the pressure holding check valve closes to prevent the pressure in the suction passage from further dropping. Also, when the supply pump is activated upon starting the engine, the pressure on the supply pump side in the suction passage rises above the set pressure, so that the pressure holding check valve opens at this time, and the fuel sent from the supply pump is sucked. It is sucked into the pump body through the check valve.

According to a second aspect of the present invention, the pressure holding check valve according to the first aspect of the present invention is disposed upstream of a low-pressure regulator for regulating fuel supplied from the supply pump to the pump body to a set pressure. I did it. In this case, when the supply pump is stopped, the inside of the suction passage can be maintained at a high pressure without being affected by the valve opening pressure of the low-pressure regulator.

According to a third aspect of the present invention, the valve body of the pressure holding check valve according to the second or third aspect of the invention is formed of an elastic body having a sealing property. In this case, when the supply pump is stopped, the suction passage can be reliably sealed. Further, since the pressure holding check valve does not open and close frequently during the operation of the pump, but closes only when the supply pump stops, there is no fear of wear or deterioration.

[0010]

Next, an embodiment of the present invention will be described with reference to the drawings.

In this embodiment, an axial plunger pump 1 is employed as a fuel pressurizing pump of a fuel injection device according to the present invention. As shown in FIGS. 1 and 2, a supply pump 2 driven by a motor M is provided. The fuel such as gasoline supplied from the fuel tank 3 is pressurized to a predetermined pressure by the axial plunger pump 1 and supplied to the injector 4, and the fuel is injected into the cylinder (not shown) of the engine by the injector 4. At the same time, the excess fuel is returned to the suction passage 5 of the pump 1 in the high-pressure regulator 70 for adjusting the injection pressure in the injector 4.

The axial plunger pump 1 comprises a housing body 7 in which a pump housing 6 has a concave portion, and a front cover 8 attached to a front end surface thereof.
The valve block 9 and the cylinder block 10 are connected to each other in the recess of the housing body 7 by bolts 11 in a superposed state. A drive shaft 12 is supported on the front cover 8 via radial bearings 13a and 13b formed of a needle bearing and a metal bearing. An end of the drive shaft 12 on the side facing the inside of the pump housing 6 has: A swash plate 14 having an end surface inclined at a predetermined angle with respect to the axis is integrally formed, and an end protruding outside the pump housing 6 is connected to a camshaft (not shown) of the engine. Is provided.

The cylinder block 10 has a plurality of cylinder holes 16 formed in the axial direction at equal intervals in the circumferential direction. Each of the cylinder holes 16 has a plunger 17 spring-biased in the direction of the swash plate 14. Are housed so as to be able to advance and retreat. Each of the plungers 17 has a hemispherical concave portion formed on the top surface thereof, and a shoe 18 is slidably fitted and held in the concave portion.

A plurality of suction ports 19 and discharge ports 20 communicating with the respective cylinder holes 16 of the cylinder block 10 are formed in the valve block 9 at the back of the cylinder block 10. Is provided with a suction check valve 21, and each discharge port 20 is provided with a discharge check valve 22. The suction port 19 is formed from the corresponding cylinder hole 16 along the axial direction of the valve block 9, and communicates with the suction side annular groove 23 formed on the inner surface of the bottom wall of the housing body 7 at the back of the valve block 9. Then, it communicates with the suction passage 5 of the housing body 7 through the annular groove 23. On the other hand, the discharge port 20 is formed radially outward from the corresponding cylinder hole 16 in the radial direction of the valve block 9,
Discharge side annular groove 2 formed on the outer peripheral surface of valve block 9
4 and through this annular groove 24 the housing body 7
Is communicated with the discharge passage 25. Therefore, when each plunger 17 moves forward and backward in the cylinder hole 16,
Fuel is sucked into each cylinder hole 16 through the suction-side annular groove 23, and the fuel is sent out to the discharge passage 25 through the discharge-side annular groove 24. In this embodiment,
The pump body 1A includes a swash plate 14, a cylinder block 10,
It is constituted by a valve block 9 and the like. Here, the suction passage 5 of the housing body 7 communicates the connection plug 26 (see FIG. 1) to which the suction pipe 40 from the supply pump 2 is connected with the suction side annular groove 23 (see FIG. 2). A low-pressure regulator 27 for regulating the pressure of the fuel sent from the supply pump 2 to a predetermined low pressure is provided in the middle of the passage. This low pressure regulator 27
Is mounted on the uppermost part of the housing body 7, and when the pressure in the suction passage 5 becomes equal to or higher than the set pressure, surplus fuel is discharged into the drain passage 28, and the remaining fuel is discharged to the downstream side of the suction passage 5 (annular shape). (Groove 23 side).

On the other hand, a bottomed cylindrical auxiliary plate 29 is attached to the end surface of the swash plate 14 formed on the drive shaft 12 so as to be relatively rotatable. The auxiliary plate 29 has a boss 30 protruding from the center of the end face on the swash plate 14 side.
1 is fitted so as to be relatively rotatable. An annular thrust plate 32 having a high hardness and a small coefficient of friction is coupled to an end surface of the auxiliary plate 29 on the cylinder block 10 side, and the shoe 18 slidably abuts the thrust plate 32. It has become. Since each plunger 17 is spring-biased in the direction of the swash plate 14 as described above, each shoe 18
7 and is constantly pressed against the thrust plate 32. Thrust bearings 33a and 33b are interposed between the front cover 8 and the swash plate 14, and between the swash plate 14 and the auxiliary plate 29, respectively.

Further, between the auxiliary plate 29 and the thrust plate 32, an inner peripheral edge of an annular resin diaphragm 34 is sandwiched in a sealed state. The outer peripheral edge of the diaphragm 34 is hermetically sandwiched between the joint between the housing body 7 and the front cover 8.
The inside of the pump is separated by a diaphragm 34 into a working fluid chamber 35 on the cylinder block 10 side and a lubricating fluid chamber 36 on the drive shaft 12 side. The working fluid chamber 35 is filled with fuel leaked from the cylinder block 10, and the lubricating fluid chamber 36 is filled with lubricating fluid for lubricating the bearings 33 a and 33 b around the drive shaft 12. It is enclosed.

A pressure holding check valve 41 is incorporated in the connection plug 26 for connecting the suction pipe 40. When the supply pump 2 is stopped, the suction pipe 40
The internal pressure can be maintained at a predetermined pressure by the pressure holding check valve 41. That is, the pressure holding check valve 41 has a hemispherical head portion 42a, and a valve body 42 made of an elastic body having a sealing property such as rubber or resin is urged by a spring 43 so that an internal passage 44 of the connection plug 26 is formed. During operation of the supply pump 2, the supply pressure of the supply pump 2 causes the valve body 42 to open the internal passage 44 of the connection plug 26 against the force of the spring 43, 2 stops and suction pipe 4
When the pressure inside the cylinder becomes lower than the set pressure, the valve element closes the internal passage of the connection plug and maintains the inside of the suction pipe at a predetermined pressure. The supply pump 2 is provided with a discharge check valve 22 as shown in FIG. 1, and when the supply pump 2 is stopped, the fuel pressure between the discharge check valve 22 and the pressure holding check valve 41 becomes a predetermined value. Is to be maintained. Further, in this embodiment, the suction passage is constituted by the suction passage 5 of the axial plunger pump 1 and the suction pipe 40.

In FIG. 1, reference numeral 38 denotes a discharge interposed in the discharge passage 25 near the discharge side annular groove 24 to maintain the pressure in the discharge passage 25 at a predetermined value when the supply pump 2 is stopped. Side pressure holding check valve.

In the above configuration, when the swash plate 14 rotates together with the drive shaft 12 by driving the engine, the auxiliary plate 29 swings (swings) integrally with the swash plate 14 while rotating relative to the swash plate 14. When the auxiliary plate 29 swings in this manner, the plunger 17 on the cylinder block 10 sequentially repeats advancing and retreating operations via the thrust plate 32 and the shoes 18 which are in sliding contact with the thrust plate 32, whereby the pumping operation is performed continuously.

At this time, the supply pump 2 connects the suction pipe 40
As shown in FIG. 3, the fuel sent to the
The valve body 42 of the pressure holding check valve 41 is pushed open to be sent to the low-pressure regulator 27, and after the pressure is adjusted to the set low pressure by the low-pressure regulator 27, the suction check valve 2
1 and is sucked into the pump body 1A. And
The pressure P ₁ on the upstream side of the pressure holding check valve 41 at this time.
The difference ΔP _A between the pressure P _{2 on} the downstream side and the pressure P _{2 on} the downstream side (see FIG. 5) is based on the opening pressure of the pressure holding check valve 41 and the valve body 42 of the check valve 41 moving against the force of the spring 43. It is the sum of the force and the pressure drop at that time.

Further, when the engine and the supply pump 2 are stopped from this state, the pressure in the pump body 1A decreases due to a leak from the sliding gap of the plunger 17, and the fuel in the suction passage 5 side is checked accordingly. Leaks gradually pass through the gap of the valve 21 (the gap of the metal contact portion). At this time, as shown in FIG. 5, both the pressures P ₁ and P ₂ on the upstream side and the downstream side of the pressure holding check valve 41 gradually decrease. When P ₂ is closer to the drain pressure, the pressure holding the check valve 4
4 when the difference ΔP _B between the pressure P ₁ on the upstream side and the pressure P _{2 on} the downstream side becomes slightly smaller than the valve opening pressure of the pressure holding check valve 41. As shown in the figure, the valve element 42 of the pressure holding check valve 41 is
6 is completely closed. As a result, the interior of the suction pipe 40 is maintained at a pressure of about ΔP _B thereafter.

Therefore, in the axial plunger pump 1, the inside of the suction pipe 40 can be maintained at a high pressure (approximately ΔP _B ) even after the engine and the supply pump 2 are stopped, so that the ambient temperature is high. However, vapor is not easily generated in the suction pipe 40. As a result, when the engine is restarted, there is no delay in boosting the pressure due to the vapor, and the starting performance of the engine is reliably improved.

In the axial plunger pump 1 of this embodiment, the valve body 4 of the pressure holding check valve 41 is provided.
2 is formed of an elastic body such as rubber or resin having a sealing property, so that when the valve is closed, the valve body 42 comes into close contact with the internal passage 44 of the connection plug 26, and as a result, the suction pipe 40 (Approximately ΔP _B ) can be maintained for a long time. The pressure holding check valve 41 does not repeatedly open and close during the operation of the pump.
(When stopped), there is no fear of wear or deterioration even with use over time.

Further, in the axial plunger pump 1, a portion of the connection plug 26 located on the upstream side of the low pressure regulator 27 in the suction passage from the supply pump 2 to the suction check valve 21 of the pump body 1A. Since the pressure holding check valve 41 is disposed at
Can be set sufficiently high without being affected by the valve opening pressure of the low-pressure regulator 27 when the operation is stopped. Therefore, generation of vapor in the suction pipe 40 can be more effectively eliminated. Further, in the case of the axial plunger pump 1, since the pressure holding check valve 41 is incorporated in the connection plug 26, there is an advantage that assembling and disassembling are easy and maintenance is easy.

[0025]

As described above, according to the first aspect of the present invention, the suction passage from the supply pump to the suction check valve of the pump main body is provided.
A pressure holding check valve that opens when the pressure on the supply pump side is equal to or higher than the set pressure is provided.When the supply pump stops due to the stop of the engine, the pressure hold check valve closes and the pressure inside the suction passage is set. As a result, it is possible to prevent the generation of vapor in the suction passage, to increase the pressure at the time of starting the engine, and to surely enhance the engine starting performance.

According to a second aspect of the present invention, the pressure holding check valve according to the first aspect of the present invention is disposed upstream of a low-pressure regulator for regulating fuel supplied from the supply pump to the pump body to a set pressure. As a result, when the supply pump is stopped, the pressure in the suction passage can be maintained at a high pressure without being affected by the valve opening pressure of the low-pressure regulator, and as a result, the generation of vapor in the suction passage is reduced. It can be reliably prevented.

According to a third aspect of the present invention, since the valve body of the pressure holding check valve according to the second or third aspect of the present invention is formed of an elastic body having a sealing property, the suction passage can be reliably formed when the supply pump is stopped. Even if the engine is shut down for a long time, the pressure in the suction passage can be maintained at a high pressure.

[Brief description of the drawings]

FIG. 1 is a sectional view taken along line AA of FIG. 2 showing one embodiment of the present invention.

FIG. 2 is a sectional view showing the embodiment.

FIG. 3 is a schematic view showing a main part of the embodiment.

FIG. 4 is a sectional view showing the embodiment.

FIG. 5 is a graph showing pressure characteristics of the example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Axial plunger pump (fuel pressurizing pump), 1A ... Pump body, 2 ... Supply pump, 4 ... Injector, 5 ... Suction passage (suction path), 21 ... Suction check valve, 22 ... Discharge check valve, 27 ... Low pressure Regulator: 40: suction pipe (suction path), 41: pressure holding check valve, 42: valve body.

Claims (3)

[Claims] 1. A fuel injection device for pressurizing fuel sent from a motor-driven supply pump, which is pressurized by an engine-driven pump body having an intake check valve and a discharge check valve and is supplied to an injector. In the pump, a pressure holding check valve that opens when the pressure on the supply pump side is equal to or higher than a set pressure is provided in a suction path from the supply pump to a suction check valve of the pump body. Pressure pump. 2. The pressure holding check valve according to claim 1, wherein the pressure holding check valve is disposed upstream of a low pressure regulator for regulating fuel supplied from a supply pump to a pump body to a set pressure. A fuel pressurizing pump for the fuel injection device as described in the above. 3. The fuel pressurizing pump according to claim 1, wherein a valve body of the pressure holding check valve is formed of an elastic body having a sealing property.