JPH09324724A - Fuel injection pump for fuel injection system - Google Patents

Abstract

(57) 【Abstract】 PROBLEM TO BE SOLVED: To supply sufficient fuel to an injector at the time of starting an engine whose rotation speed is extremely low. Improves engine starting performance. A bypass passage 55 is provided which directly connects the suction passage 5 and the discharge passage 28, and an electromagnetic valve 56 is provided in the bypass passage 55. The controller 58 opens and closes the solenoid valve 56.
Control with. An engine rotation sensor 59 and a combustion pressure sensor 60 are connected to the input section of the controller 58. The controller 58 outputs an opening operation signal to the solenoid valve 56 at the time of engine startup where the engine speed is extremely low and when the combustion pressure is abnormal. When the engine is started, the solenoid valve 56 causes the bypass passage 5
5 is opened, and a sufficient amount of fuel from the motor-driven supply pump 3 is directly supplied to the injector 4. When the combustion pressure is abnormal, the intake passage 5 and the discharge passage 28 are communicated with each other to stop the supply of the pressurized fuel to the injector 4.

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 for a fuel injector of an automobile or the like, and more particularly to a fuel pressurizing pump for a fuel injector which has been improved to enhance engine starting performance.

[0002]

2. Description of the Related Art In an automobile fuel injection system, fuel sent from a motor-driven supply pump is pressurized to a high pressure by an engine-driven fuel pressurizing pump.
The pressurized high-pressure fuel is injected into the engine by an injector. This related technique is disclosed in, for example, Japanese Utility Model Laid-Open No. 6-43274.

[0003]

However, in the above-described conventional fuel injection device, the fuel pressurizing pump is driven by the power of the engine, and therefore, when the engine is started at an extremely low engine speed, A sufficient amount of fuel cannot be supplied from the fuel pressurizing pump to the injectors, and especially when the sensation of cooling requires a large amount of fuel to be supplied compared to normal times, it is difficult to smoothly start the engine due to insufficient fuel supply. Become.

In the case of the fuel injection device, when the engine speed decreases, the theoretical discharge flow rate proportional to the speed decreases, of course, but the actual discharge flow rate of the fuel pressurizing pump is As shown in Fig. 6, since the leak amount of fuel from each pump part is subtracted from the theoretical discharge flow rate, in the region where the engine speed is extremely low such as when the engine is started, as shown in the same figure, The discharge flow rate of is almost zero, which may lead to a situation in which fuel can hardly be supplied to the injector.

Therefore, the present invention provides a fuel pressurizing pump for a fuel injection device capable of reliably supplying sufficient fuel to the injector even when the engine is started at an extremely low engine speed, thereby reliably improving the starting performance of the engine. Is to provide.

[0006]

As a means for solving the above-mentioned problems, the invention according to claim 1 pressurizes fuel sent from a motor-driven supply pump by receiving power from an engine. In the fuel pressurizing pump of the fuel injection device that supplies the injector, a bypass passage that directly connects the pump suction passage and the pump discharge passage, a solenoid valve that opens and closes this bypass passage, and an opening operation signal to this solenoid valve when the engine is started. The output controller is provided. When the engine is started at an extremely low rotation speed, the controller outputs an opening operation signal to the solenoid valve, and the solenoid valve receives this signal and opens the bypass passage. As a result, the pump suction passage and the pump discharge passage communicate directly with each other without passing through the pump function section, and a sufficient amount of fuel sent from the supply pump is directly supplied to the injector.

According to a second aspect of the present invention, in the fuel pressurizing pump of the fuel injection device, the fuel sent from the motor-driven supply pump is pressurized by receiving power from the engine and is supplied to the injector. A bypass passage that directly communicates the intake passage and the pump discharge passage, a solenoid valve that opens and closes the bypass passage, and a controller that outputs an opening operation signal to the solenoid valve when the engine is started and when the combustion pressure of the engine is abnormal It was configured. When the engine is started, the solenoid valve receives a signal from the controller to open the bypass passage, and the pump suction passage and the pump discharge passage communicate directly with each other through the bypass passage, so that a sufficient amount of fuel sent from the supply pump is directly Supplied to the injector. Further, even when the combustion pressure of the engine is abnormal, the solenoid valve receives a signal from the controller to open the bypass passage, and the pump suction passage and the pump discharge passage communicate directly with each other through the bypass passage. In this case, the fuel supplied to the injector is not subjected to high-pressure pressurization in the pump function unit, so that the combustion pressure can be quickly lowered.

[0008]

FIG. 1 shows an embodiment of the present invention.
~ It demonstrates based on FIG.

In this embodiment, the axial plunger pump 1 is used as a fuel pressurizing pump of a fuel injection device according to the present invention. As shown in FIGS. The fuel such as gasoline supplied via the axial plunger pump 1 is pressurized to a predetermined pressure and supplied to the injector 4, and the fuel is injected by the injector 4 into a cylinder (not shown) of the engine. Excess fuel is returned from the injector 4 to the suction passage 5 (pump suction passage) of the pump 1.

As shown in FIG. 2, the axial plunger pump 1 comprises a housing main body 8 in which a pump housing 6 has a recess 7 and a front cover 9 attached to the front end portion thereof. The valve block 10 and the cylinder block 11 are connected by a bolt 12 in a superposed state. Further, on the front cover 9, the drive shaft 13 has radial bearings 14 and 15 formed of needle bearings and metal bearings.
A swash plate 16 whose end surface is inclined at a predetermined angle with respect to the axis is integrally formed at the end of the drive shaft 13 that faces the inside of the housing 6. A coupling 17 for coupling with a camshaft (not shown) of the engine is provided at an end portion on the side projecting to
Is provided.

The cylinder block 11 is formed with a plurality of cylinder holes 18 along the axial direction at equal intervals in the circumferential direction. In each of the cylinder holes 18, a plunger 19 is spring-biased toward the swash plate 16. Is housed so that it can move back and forth. A hemispherical recess 20 is formed on the top surface of each plunger 19, and a shoe 21 is rotatably fitted in the recess 20. A plurality of suction ports 22 and a discharge port 23 communicating with each cylinder hole 18 of the cylinder block 11 are formed in the valve block 10 at the back of the cylinder block 11, and each suction port 22 has a suction check. A valve 24 is provided, and each discharge port 23 is provided with a discharge check valve 25.
Of these, the suction port 22 is formed along the axial direction of the valve block 10 from the corresponding cylinder hole 18 and communicates with the suction side annular groove 26 formed on the inner surface of the bottom wall of the housing body 8 on the back surface of the valve block 10. However, it communicates with the suction passage 5 of the housing body 8 through the annular groove 26. On the other hand, the discharge ports 23 are formed radially from the corresponding cylinder holes 18 to the outside in the radial direction of the valve block 10, and communicate with the discharge side annular groove 27 formed on the outer peripheral surface of the valve block 10. Annular groove 27
It is communicated with the discharge passage 28 (pump discharge passage) of the housing body 8 via. Therefore, each plunger 19
When the cylinder moves forward and backward in the cylinder hole 18, the fuel is sucked into each cylinder hole 18 through the suction side annular groove 26, and the fuel passes through the discharge side annular groove 27 and the discharge passage 2
Sent to 8.

The suction passage 5 of the housing body 8 is a passage for connecting a suction pipe connection port (not shown) connected to the supply pump 3 to the suction side annular groove 26, and the passage is in the middle thereof. A low-voltage regulator 29 is interposed in the. This low-pressure regulator 29 is integrally assembled on the uppermost part of the housing body 8, and when the pressure on the upstream side (supply pump 3 side) of the suction passage 5 becomes equal to or higher than the set pressure, excess fuel is fed to the drain passage 30. The residual fuel that is discharged and adjusted to a set low pressure there is allowed to flow to the downstream side (the annular groove 26 side) of the intake passage 5.

In FIG. 3, reference numeral 32 is an accumulator connected to the discharge side annular groove 27 for preventing pulse pressure, and 33
Is a discharge pressure sensor, and 35 is a high pressure regulator.

On the other hand, a disc-shaped auxiliary plate 38 is attached to the end face of the swash plate 16 formed on the drive shaft 13 so as to be relatively rotatable. The auxiliary plate 38 has a boss 39 projecting from the center of the end face on the swash plate 16 side, and the boss 39 is fitted into a support hole 40 formed in the center of the end face of the swash plate 16 so as to be relatively rotatable. . A thrust plate 41 having a high hardness and a small friction coefficient is rotatably attached to an end surface of the auxiliary plate 38 on the cylinder block 11 side by a bolt 42, and the thrust plate 41 is fitted to the plunger 19. Shoe 2
1 is slidably abutted. Since each plunger 19 is biased by the spring in the direction of the swash plate 16 as described above, each shoe 21 is constantly pressed against the thrust plate 41 by the biasing force of the plunger 19.

A load supporting flange 43 is provided on the back surface of the swash plate 16 of the front cover 9 between the load supporting flange 43 and the swash plate 16 and between the swash plate 16 and the load supporting flange 43.
Thrust bearings 44a and 44b, which are needle bearings, are interposed between and the auxiliary plate 38. The thrust bearings 44a and 44b are for supporting the load supporting flange 43 of the front cover 9 to support the axial component of the reaction force received by the auxiliary plate 38 from the plunger 19, and the diameter of the reaction force received from the plunger 19. The directional component is supported by the fitting portion between the boss 39 of the auxiliary plate 38 and the support hole 40 of the swash plate 16.

Further, one end of a metal bellows 45 that covers the periphery of the drive shaft supporting portion of the housing 6 to the periphery of the swash plate 16 is joined to the outer peripheral edge of the auxiliary plate 38 in a hermetically sealed state. ing. And this bellows 4
Similarly, the other end side of 5 is joined in a hermetically sealed state to an annular mounting flange 46, and the outer peripheral edge portion of this mounting flange 46 is interposed between the joint portion of the housing body 8 and the front cover 9 and is fixed by a bolt 47. It is connected to the housing body 8 together with the front cover 9. A lubricating liquid having a predetermined viscosity is filled in the space around the drive shaft surrounded by the bellows 45. That is, the bellows 45 divides the inside of the housing 6 into a working fluid chamber 48 filled with the fuel leaked from the cylinder block 11 and a lubricating fluid chamber 49 filled with the lubricating fluid.

Reference numeral 53 in the drawing denotes a return passage for returning the fuel leaking into the hydraulic fluid chamber 48 to the fuel tank 2. This return passage 53 is provided in the drain passage 30 located above the recess 7 and above it. The air that is formed toward the inside of the recess 7 can be discharged to the drain passage 30 together with the leaked fuel.

By the way, a bypass passage 55 is provided between the discharge passage 28 and a portion of the suction passage 5 on the upstream side of the low pressure regulator 29. The bypass passage 55 directly connects the passages 5 and 28. A solenoid valve 56 that opens and closes the passage 55 is provided midway. This solenoid valve 56
In the normal state, the spring-biased valve portion 57 closes the bypass passage 55 as shown in FIG. 4, and when an ON signal, which is an opening operation signal, is input from the controller 58 from this state, FIG. As shown, the valve portion 57 opens the bypass passage 55 against the spring force. A rotation sensor 59 attached to the engine and a combustion pressure sensor 60 are connected to an input portion of the controller 58, and the rotation sensor 59 indicates that the engine rotation speed is equal to or lower than a set rotation speed lower than the idling rotation speed (engine rotation speed). An ON signal is output to the solenoid valve 56 when the engine speed (starting speed) is detected and when the combustion pressure sensor 60 detects an abnormal pressure equal to or higher than the set pressure.

In the above structure, when the drive shaft 13 rotates with the operation of the engine, the swash plate 1 integral with the drive shaft 13 is formed.
6 rotates, whereby the auxiliary plate 38 is prevented from being rotated by the bellows 45 and relatively swings with the swash plate 16 and swings (swings) integrally with the swash plate 16. At this time, the auxiliary plate 38 is rotatably fitted and held in the center of the swash plate 16 via the boss 39 projectingly provided on the end surface thereof, so that the auxiliary plate 38 is allowed to rotate relative to the swash plate 16. It does not separate from the end face of the swash plate 16 and always swings integrally with it.

When the auxiliary plate 38 swings in this way, the plunger 19 on the cylinder block 11 is moved through the thrust plate 41 and the shoe 21 slidingly contacting the thrust plate 41.
The pump action is continuously performed by repeating the forward / backward movement. At this time, when the engine is in a normal operating state (when the engine is rotating at a speed equal to or higher than the idling speed), the bypass passage 55 is closed by the solenoid valve 56 as shown in FIG. For,
The fuel supplied from the fuel tank 2 to the intake passage 5 via the supply pump 3 is regulated to a set low pressure by the low pressure regulator 29, and then sequentially passed through the intake side annular groove 26, the intake port 22, and the intake check valve 24. Is sucked into the cylinder hole 18 and pressurized there by the plunger 19 and then discharged from the cylinder hole 18 to the discharge check valve 25 and the discharge port 2.
3, the discharge side annular groove 27, and the discharge passage 28 are sequentially passed to be supplied to the injector 4, and the surplus fuel used in the injector 4 is returned to the upstream side of the intake passage 5.

Further, when the engine is started, the engine is rotated by the power of the starter motor. Since the engine speed at this time is equal to or lower than the set speed smaller than the idling speed, this is detected by the rotation sensor 59. Then, an ON signal is output from the controller 58 to the solenoid valve 56, which causes the solenoid valve 56 to open the bypass passage 55 as shown in FIG. Therefore, at the time of starting the engine, the fuel introduced from the supply pump 3 into the intake passage 5 passes through the bypass passage 55 from the upstream side of the low pressure regulator 29 to the discharge passage 28 directly, and the pump function unit (cylinder block 11). Also, it is directly supplied to the injector 4 without passing through the valve block 10). Therefore, at this time, the injector 4 is directly supplied with a large flow rate of fuel from the supply pump 3 which does not depend on the engine rotation, whereby the engine can be reliably started. In particular, at the time of engine starting at the time of a cold sensation that requires a large amount of fuel, a sufficient amount of fuel can be reliably supplied to the injector 4, so the starting performance of the engine is reliably improved. When the engine starts and its rotation speed exceeds the set value, an off signal is output from the controller 58 to the solenoid valve 56, and the solenoid valve 56 closes the bypass passage 55 and switches to the normal operating state described above.

Furthermore, when the combustion pressure of the engine rises above the set pressure due to some abnormality during the operation of the engine, this is detected by the combustion pressure sensor 60 and the controller 58 outputs an ON signal to the solenoid valve 56. The solenoid valve 56 opens the bypass passage 55 to open the intake passage 5
And the discharge passage 28 are directly communicated with each other. As a result, the fuel supplied to the injector 4 is not pressurized to a high pressure in the pump function unit, and the abnormal increase in the combustion pressure of the engine is promptly avoided.

The embodiment of the present invention is not limited to the one described above. For example, in the above embodiment, it is determined based on the signal from the rotation sensor 59 that the engine is starting. Although the ON signal is output to the solenoid valve 56, it may be determined that the engine is being started based on the ON signal of the ignition switch.

In the above description, although the axial plunger type fuel pressurizing pump has been described, the fuel pressurizing pump of the present invention is not limited to this type, and other types of pumps such as a radial plunger type and a vane type may be used. It may be.

[0025]

As described above, according to the first aspect of the invention, the bypass passage that directly connects the pump suction passage and the pump discharge passage, the solenoid valve that opens and closes the bypass passage, and the opening operation of the solenoid valve when the engine is started. Since the controller is configured to output a signal, sufficient fuel sent from the supply pump can be directly supplied to the injector through the bypass passage at the time of engine start when the engine speed becomes extremely low. As a result, the starting performance of the engine can be reliably improved. Therefore, according to the present invention, the engine start failure does not occur when the engine is cold.

According to the second aspect of the present invention, a bypass passage that directly connects the pump intake passage and the pump discharge passage, a solenoid valve that opens and closes the bypass passage, and a solenoid valve when the engine is started and when the combustion pressure of the engine is abnormal. Since the controller for outputting the opening operation signal is provided, it is possible to eliminate the shortage of the supplied fuel at the time of starting the engine and to promptly reduce the supplied fuel pressure when the combustion pressure is abnormal. Therefore, according to the present invention, it is possible to surely improve the starting performance of the engine, and it is possible to avoid a defect due to an abnormal combustion pressure of the engine without adding a special passage structure or a valve device.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing one embodiment of the present invention.

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

FIG. 3 is a sectional view taken along the line BB of FIG. 1 showing the same embodiment.

FIG. 4 is an enlarged cross-sectional view of a C portion of FIG. 1 showing the same embodiment.

FIG. 5 is an enlarged cross-sectional view of a C portion of FIG. 1 showing the same embodiment.

FIG. 6 is a graph showing a discharge flow rate-rotation speed characteristic of a conventional fuel pressurizing pump.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Axial plunger pump (fuel pressurizing pump), 3 ... Supply pump, 4 ... Injector, 5 ... Suction passage (pump suction passage), 28 ... Discharge passage (pump discharge passage), 55 ... Bypass passage, 56 ... Solenoid valve , 58 ... Controller.

Claims (2)

[Claims] 1. A fuel pressurizing pump of a fuel injection device, which pressurizes fuel sent from a motor-driven supply pump by receiving power from an engine and supplies it to an injector, in which a pump suction passage and a pump discharge passage are provided. A fuel pressurizing pump for a fuel injection device, comprising: a bypass passage that directly communicates with the solenoid valve; an electromagnetic valve that opens and closes the bypass passage; and a controller that outputs an opening operation signal to the electromagnetic valve when the engine is started. 2. A fuel pressurizing pump of a fuel injection device, which pressurizes fuel sent from a motor-driven supply pump by receiving power from an engine and supplies it to an injector, wherein a pump suction passage and a pump discharge passage are provided. Fuel injection characterized by comprising a bypass passage directly communicating with the solenoid valve, a solenoid valve for opening and closing the bypass passage, and a controller for outputting an opening operation signal to the solenoid valve at the time of engine start and abnormal combustion pressure of the engine. Pump for fuel pressurization of equipment.