JPH11236864A - Fuel injection device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform discharge of a working fluid during running of an engine while discharge of working fluid during the stop of an engine is prevented from occurring. SOLUTION: A fuel injection device for an internal combustion engine operates an injector 2 by a fluid pressure stored in a pressure accumulator chamber 8 and executes injection of fuel is provided with a pump 9 to pressurize and feed the working fluid is arranged in the pressure accumulator chamber 8. A pressure control valve 11 to control a pressure in the pressure accumulator chamber 8 is arranged between the pump 9 and the pressure accumulator chamber 8. Further, a first check valve 21 to regulate movement of fluid from the pressure accumulator chamber 8 side toward the pressure control valve 11 side is arranged between the pressure control valve 11 and the pressure accumulator chamber 8, and a second check valve 61 in parallel with the first check valve 21 is provided to regulate movement of fluid from the pressure control valve 11 side toward the pressure accumulator chamber 8 side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection device applied to an internal combustion engine such as a diesel engine.

[0002]

2. Description of the Related Art As a fuel injection device applied to a diesel engine, there is known a hydraulically operated electronically controlled fuel injection device as disclosed in Japanese Patent Publication No. Hei 6-511524. In this method, oil is pressurized to a high pressure by a high-pressure oil pump, this high-pressure oil is temporarily stored in an oil rail, and then supplied to the injector. Is pressurized to the injection pressure, the needle valve is lifted by the pressurized fuel, and fuel injection is executed. The oil is shared with engine lubrication oil.

[0003]

The oil rail pressure is one of the factors that determine the fuel injection amount.
Engine operation status (engine speed, engine load, etc.)
It is controlled according to. In order to do this, a pressure control valve is provided between the high pressure oil pump and the oil rail, and the oil pressure is appropriately released from the pressure control valve,
The oil rail pressure is controlled to the target pressure.

[0004] However, when the engine is stopped, there is a problem that the oil rail pressure drops. That is, when the pressure control valve is normally open, when the engine is stopped, oil in the oil rail is discharged from the pressure control valve, and the oil rail pressure is lost. In this case, the starter must be turned for a long time until the oil rail pressure increases at the next start, which is not preferable in terms of practicality.

In order to prevent this, there is a method of providing a check valve. However, in this case, the means for draining the oil from the oil rail and reducing the oil rail pressure is only a leak of the injector due to injection, and the oil rail pressure is reduced. Control becomes difficult.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a fuel injection device for an internal combustion engine that operates an injector by a fluid pressure stored in a pressure accumulation chamber to execute fuel injection. A supply pump is provided, a pressure control valve for controlling the pressure of the pressure accumulation chamber is provided between the pump and the pressure accumulation chamber, and pressure control is performed between the pressure control valve and the pressure accumulation chamber from the pressure accumulation chamber side. A first check valve for regulating the movement of the fluid toward the valve side, and a second check valve arranged in parallel with the first check valve and for regulating the movement of the fluid from the pressure control valve side to the accumulation chamber side. It is a thing.

[0007] According to this, while the first check valve can prevent the discharge of the working fluid when the engine is stopped, when the engine is operating, the working fluid is discharged through the second check valve and the oil rail pressure is reduced. It is possible to reduce the pressure with good response.

[0008]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 shows a fuel injection device for an internal combustion engine according to the present invention, that is, a hydraulically operated electronically controlled fuel injection device for a diesel engine. As shown, such a device 1 comprises:
A plurality of (four in this case) injectors 2 having the same number of cylinders as the engine are provided, and the fuel in the fuel tank 3 is supplied to these injectors 2 by the fuel pump 4. The fuel passage is indicated by 6, and the fuel filter for filtering the fuel is indicated by 5. The injector 2 is attached to a cylinder head (not shown) of the engine, and is supplied with fuel from a fuel port formed inside the cylinder head. The injector 2 is completely housed in the head cover so as not to be exposed to the outside.

Each injector 2 has a common oil rail 8
Connected to. The oil rail 8 forms a pressure accumulator and is high pressure
(About 3 to 20 MPa) oil (working fluid) is stored, and the oil is distributed and supplied to each injector 2. Here, engine lubricating oil is shared, and rationalization and cost reduction are achieved. It is optional to use a special oil. This oil rail 8 is also completely stored in the head cover. High-pressure oil discharged from a high-pressure oil pump 9 (pump) is supplied to the oil rail 8 through a high-pressure oil passage 10. The high-pressure oil pump 9 is driven by the engine. Oil rail pressure is
It is controlled by a pressure control valve 11 provided between the high-pressure oil pump 9 and the oil rail 8. That is, the pressure control valve 11 transfers a part of the oil discharged from the high-pressure oil pump 9 to the oil pan 13
, The internal pressure of the oil rail 8 is controlled.

The high-pressure oil pump 9 has an oil pan 13
The oil inside is sent through the low pressure oil passage 14. That is, an oil pump 15 driven by the engine is provided in the low-pressure oil passage 14. The oil pump 15 pressurizes the oil in the oil pan 13 to an appropriate pressure and supplies the oil to the high-pressure oil pump 9. This is a high pressure oil pump 9
Is a structure that cannot be inhaled by itself. An oil filter 16 is provided on the discharge side of the oil pump 15 in the low-pressure oil passage 14. As usual, another oil pump 5 for supplying oil to each lubricating portion of the engine is provided.
4 are also provided.

Reference numeral 18 in the figure denotes a controller such as a CPU and an ECU. This is based on the electrical signals sent from various sensors, reads the current engine operating conditions such as engine speed, engine load, etc., and determines the target injection quantity by comparing these values with the map values. The ON / OFF signal is sent to the injector 2 to execute fuel injection control. In particular, an oil rail pressure sensor 20 is provided on the oil rail 8, and the controller 18 controls the duty of the pressure control valve 11 based on a comparison between the output value and the map value, and controls the oil rail pressure to the target pressure. I have.

FIG. 2 schematically shows the structure of the injector 2. The injector 2 integrally has a solenoid 24 at the top thereof, and the ON / OFF control of the solenoid 24 causes the poppet valve 26 to move up and down, and the oil inlet 29
The oil is introduced and shut off. Here, the high pressure oil of the oil rail 8 is always supplied to the oil inlet 29.

As shown in FIG. 3, when the solenoid 24 is turned on, the poppet valve 26 rises and high-pressure oil is introduced into the injector. This high-pressure oil lowers the pressure-intensifying piston 31 against the urging force of the piston return spring 33. As a result, the fuel in the fuel chamber 32 is pressurized to a high pressure via the plunger 46. This pressurized fuel acts on the needle valve 35 through the fuel port 34, and the fuel pressure lifts the needle valve 35 against the urging force of the nozzle return spring 37. As a result, high-pressure fuel is injected from the injection hole 38.

On the other hand, when the solenoid 24 is turned off,
The poppet valve 26 descends and stops introducing oil. Then, the internal high-pressure oil is discharged from the oil discharge port 53 shown in FIG. Since the injector 2 is completely accommodated in the head cover, the discharged oil returns from the cylinder head to the oil pan.

Here, the pressure control valve 11 is of a normally open type, that is, one in which the oil discharge port is fully opened when no power is supplied and the oil supply port is completely discharged. In this case, when the engine is stopped, the high-pressure oil in the oil rail 8 is discharged from the pressure control valve 11 to the oil pan 13, and it takes a long time until the oil rail pressure rises sufficiently at the next start. There are inconveniences such as a longer engine start time.

Therefore, in the present apparatus 1, first, the pressure control valve 1
1 and the oil rail 8, specifically the pressure control valve 11
A check valve 21 (first check valve) for regulating the flow of oil from the oil rail 8 toward the pressure control valve 11 is provided in the middle of the high-pressure oil passage 10 that connects the oil rail 8 with the oil rail 8. The check valve 21 includes a valve body 22 and a spring 23 for urging the valve body 22 in a closing direction, and is opened based on a differential pressure on the upstream and downstream sides.

When high-pressure oil is supplied from the high-pressure oil pump 9 to the oil rail 8, the check valve 21 is opened,
Oil can be supplied. When the engine is stopped and the pressure control valve 11 is OFF, the check valve 21 closes with the pressure on the oil rail 8 side, so that the internal pressure of the oil rail 8 can be maintained. As a result, the oil rail oil pressure at the time of restart can be immediately increased, and the engine can be restarted quickly.

In particular, in the present apparatus 1, a pressure control valve 11 is provided at a position below the oil rail 8 for reasons of layout. Therefore, there is a concern about discharge due to natural fall, but the check valve 21 has solved this problem.

On the other hand, according to this configuration, it becomes difficult to control the oil rail pressure to the decreasing side with good responsiveness during engine operation. In particular, since high-pressure oil is discharged from the injector 2 every fuel injection as described above, the oil rail pressure drops by itself only in normal operation. However, if it is desired to reduce the oil rail pressure more quickly, this is necessary. There are inconveniences that cannot be made. Also, for example, when performing no-load operation for downhill after performing acceleration operation for uphill,
Due to the fuel cut during the no-load operation, the high pressure is maintained as it is, and at the moment of the next normal driving, excessive fuel is injected, which causes problems such as diesel knock.

Therefore, in the present apparatus 1, the check valve 21 is used.
Another check valve 61 (second check valve) is provided in parallel with and in the opposite direction. That is, the check valve 61 regulates the flow of oil from the pressure control valve 11 to the oil rail 8. 62 is a valve body, 63 is a spring,
The opening of the check valve 61 is also performed based on the differential pressure on the upstream and downstream sides. As a result, the high-pressure oil in the oil rail 8 flows backward and is discharged from the pressure control valve 11, and the oil rail pressure can be reduced. The responsiveness at this time is also greatly improved.

Here, the arrangement positions of the check valves 21 and 61 will be described in detail. The inlet of the high-pressure oil passage 10 is connected to the discharge port of the high-pressure oil pump 9.
0 is branched on the way and an oil rail 8
However, a pressure control valve 11 is connected to the other outlet. In the middle of the passage from the branch position to the oil rail 8, the check valves 21 and 61 having different directions are provided in parallel.

For these check valves 21 and 61, the spring constant k ₁ of the former spring 23 is relatively small, and the spring constant k ₂ of the latter spring 63 is relatively large. In these relations, k ₁ <k ₂ . The reason is as follows. First, in the former check valve 21, there is a demand that the check valve 21 should be opened surely even when the oil rail pressure is slightly increased during the operation of the engine, that is, even if the differential pressure on the upstream and downstream sides is small. On the other hand, the latter check valve 6
In No. 1, there is a demand that the oil rail pressure is not easily opened when the engine is stopped, and that the oil rail pressure should be kept high enough for the next start. However, if the engine is stopped at or above this set value, the check valve 61 continues to open until the engine value falls below the set value. In this case, the controllability when the oil rail pressure is slightly reduced during the operation of the engine becomes a problem. However, since the differential pressure that causes the check valve 61 to open can be immediately generated by the pressure control valve 11, this point can be solved. . For these reasons, the spring constants of the springs 23 and 61 are determined as described above.

The check valves 21 and 61 are specifically formed in a check valve unit 65 shown in FIG. That is, the check valve unit 65 includes the piston-like valve bodies 22 and 62 and the springs 23 and 63 in one body 66, respectively.
Is built in a compact two-way configuration.
Oil passage holes 67 and 68 are provided in the body 66 in parallel with each other, and the inlet side of the valve body 22 and 62 is located at the outlet side of the other oil passage holes 67 and 68, and the curved passage holes 69 and 70.
Is to be communicated through. Valve body 22, 62
Are urged toward the inlet side by springs 23 and 63, and the movement is restricted by stopper rings 71 and 72 pressed into the inlet side. 73 is a mounting hole,
Reference numeral 74 denotes a female screw for pipe connection.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and can adopt other embodiments. As described above, the present invention is most suitable for a hydraulically operated electronically controlled fuel injection device, but is not limited to this, and can be applied to various devices that operate an injector using fluid pressure. .

[0026]

The present invention exhibits the following excellent effects.

(1) It is possible to discharge the working fluid while the engine is running, while preventing the discharge of the working fluid when the engine is stopped.

(2) It is optimal for a hydraulically operated electronically controlled fuel injection device.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a hydraulically operated electronically controlled fuel injection device according to the present embodiment.

FIG. 2 is a schematic vertical sectional view showing an injector.

FIG. 3 is a schematic longitudinal sectional view showing the injector during operation.

FIG. 4 is a longitudinal sectional view showing a check valve unit.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 hydraulically operated electronically controlled fuel injection device 2 injector 8 oil rail 9 high pressure oil pump 11 pressure control valve 21, 61 check valve

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI F02M 55/02 350 F02M 55/02 350E 350P (72) Inventor Jun Otsuka 8 Tsuzura, Fujisawa City, Kanagawa Prefecture Isuzu Motors Fujisawa Plant, Ltd. (72) Inventor Toshiyuki Usui 8 Tosanabe, Fujisawa-shi, Kanagawa Prefecture Isuzu Motors Fujisawa Plant Co., Ltd.

Claims (1)

[Claims] 1. A fuel injection device for an internal combustion engine, which operates an injector by a fluid pressure stored in a pressure accumulation chamber to execute fuel injection, comprising a pump for pressurizing and supplying a working fluid to the pressure accumulation chamber. A pressure control valve for controlling the pressure of the pressure accumulating chamber is provided between the pressure accumulating chamber and the pressure accumulating chamber, and the movement of the fluid from the pressure accumulating chamber to the pressure control valve is controlled between the pressure control valve and the accumulating chamber. An internal combustion engine, comprising: a first check valve for regulating the pressure; and a second check valve in parallel with the first check valve for regulating the movement of fluid from the pressure control valve to the pressure accumulating chamber. Fuel injector.