JPH051637A - Accumulator fuel injection device - Google Patents

Abstract

PURPOSE:To furnish an accumulator fuel injection device capable of preventing outflow of fuel due to damage to a fuel pipe between a high pressure pump and a common rail. CONSTITUTION:A common rail 19 to pressure-accumulate high pressure fuel is connected to a high pressure pump 1 through fuel, supply pipes 17, 18. Additionally, injection valves 25 provided on each of cylinders of an engine are connected to the common rail 19 through branch pipes 24. Check valves 21, 23 are provided on an edge part of the side of the common rail 19 of the fuel supply pipes 17, 18, and supply of fuel from the high pressure pump 1 to the common rail 19 is allowed by the check valves 21, 23 and simultaneously, passing of fuel from the common rail 19 to the high pressure pump 1 is regulated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure accumulating fuel injection device used in a diesel engine or the like.

[0002]

2. Description of the Related Art Conventionally, for example, JP-A-59-16585.
As shown in Japanese Patent No. 8, there is a pressure accumulation type fuel injection device as one of the fuel injection devices for diesel engines. This is a type of surge tank called a common rail that stores high-pressure fuel from a high-pressure pump and injects it to an engine by opening an injection valve. or,
In this type of device, Japanese Patent Laid-Open No. 60-159366 discloses a device in which a safety device is provided in an injection valve to block the fuel supply passage when a predetermined amount of fuel or more is supplied to the injection valve due to damage to the injection valve or the like. Has been done.

[0003]

However, in this safety device, although it is possible to prevent the injection valve from being damaged and the fuel from flowing out from the injection valve, the pipe between the high pressure pump and the common rail is damaged. If the fuel leaks and the fuel leaks out, this cannot be prevented, resulting in a serious malfunction.

An object of the present invention is to provide a pressure-accumulation type fuel injection device capable of preventing fuel from flowing out due to breakage of a fuel pipe between a high pressure pump and a common rail.

[0005]

According to the present invention, a high pressure fuel is supplied from a high pressure pump through a fuel supply pipe, and a common rail for accumulating the fuel and a branch provided from each common rail provided for each cylinder of the internal combustion engine. An injection valve connected through a pipe is provided, and the injection valve is controlled to be opened and closed to inject a fuel amount according to the operating state of the internal combustion engine so that the fuel in the common rail is injected into each cylinder of the internal combustion engine. In the pressure-accumulation fuel injection device, a check valve that allows the supply of fuel from the high-pressure pump to the common rail at the end of the fuel supply pipe on the common rail side and that restricts the passage of fuel from the common rail to the high-pressure pump. The gist of the present invention is a pressure-accumulation type fuel injection device.

[0006]

The high pressure fuel is supplied to the common rail through the fuel supply pipe by driving the high pressure pump, and the fuel is accumulated in the common rail. Then, the injection valve is controlled to be opened and closed, and the fuel in the common rail is injected into each cylinder of the internal combustion engine. On the other hand, if the fuel supply pipe is damaged, the check valve restricts the passage of fuel from the common rail to the fuel supply pipe, and prevents the high-pressure fuel on the common rail side from flowing out.

[0007]

【Example】

(First Embodiment) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows the overall structure of a diesel engine fuel injection device. The fuel injection device is equipped with a two-cylinder high-pressure pump 1. The high-pressure pump 1 is provided with a drive shaft 2, and the drive shaft 2 is drivingly connected to a crankshaft 4 of a diesel engine 3. Triangular cams 5 and 6 are fixed to the drive shaft 2. Further, the high-pressure pump 1 is provided with cylinders 7 and 8, and pistons 9 and 10 that slide on the cam surfaces of the cams 5 and 6 are arranged in the cylinders 7 and 8. The downward movement of the pistons 9 and 10 accompanying the rotation of the cams 5 and 6 causes the pressurizing chamber 1 in the cylinders 7 and 8 to move.
The fuel in the tank 14 is supplied to the fuel tanks 1 and 12 via the low-pressure pump 13.

Discharge amount control solenoid valves 15 and 16 are arranged above the cylinders 7 and 8, and the solenoid valves 15 and 16 open and close a fuel supply passage from the low pressure pump 13. When the pistons 9 and 10 move upward with the discharge amount control solenoid valves 15 and 16 closed, the fuel is pressurized in the pressurizing chambers 11 and 12. By adjusting the valve closing timing (TF in FIG. 2) of the solenoid valves 15 and 16 during the pressurizing operation, the fuel discharge amount (hatched portion in FIG. 2) can be adjusted. The discharge control solenoid valves 15 and 16 are opened at the top dead center of the cam lift (θ0 in FIG. 2) to complete the fuel pressurization in the pressurizing chambers 11 and 12.

Further, the pressurizing chambers 11 and 12 of the high-pressure pump 1 are provided with high-pressure accumulating pipes common to each cylinder by fuel supply pipes 17 and 18,
A so-called common rail 19 is connected. A check valve 20 is provided at the pump-side end of the fuel supply pipe 17, and a check valve 21 is provided at the common-rail-side end. Similarly, a check valve 22 is provided at the pump side end of the fuel supply pipe 18, and a check valve 23 is provided at the common rail side end. These check valves 20, 2
Reference numerals 1, 22 and 23 allow the fuel to be supplied from the high pressure pump side to the common rail side, and regulate the passage of fuel from the common rail side to the high pressure pump side.

An injection valve 25 for each cylinder of the diesel engine 3 is connected to the common rail 19 by a branch pipe 24. Further, a flow limiter 26 is provided at each end of the branch pipe 24 on the common rail side. The flow limiter 26 allows fuel to be supplied to the injection valve 25 in a predetermined amount or less, and to the injection valve 25 in a predetermined amount or more. It regulates the fuel supply of. That is, if the injection valve 25 is damaged for some reason, the flow limiter 26 will
The fuel supply to No. 5 is restricted.

Further, the injection valve 25 is provided with a three-way control valve 31, and by controlling the three-way control valve 31, high-pressure fuel from the common rail 19 can be injected from the injection valve 25 into each cylinder.

Electronic control unit (hereinafter referred to as ECU)
Reference numeral 27 is an optimum injection timing which is determined by the crank angle sensor 28, the cylinder discrimination sensor 29, and the throttle opening sensor 30 to input information on the engine speed and the throttle opening, and which is determined according to the engine state judged from these signals. The ECU 27 outputs a control signal to the three-way control valve 31 so that the injection amount is obtained. As shown in FIG. 2, the crank angle sensor 28 outputs a signal of one pulse for each predetermined crank angle, and the cylinder discrimination sensor 29 outputs a signal of one pulse for each rotation of the drive shaft 2. Is.

Further, the common rail 19 is provided with a common rail pressure sensor 32 for detecting the common rail pressure.
The ECU 27 controls the discharge amount of the high-pressure pump 1 so that the common rail pressure by the sensor 32 becomes an optimum value set according to the throttle opening and the rotation speed.

Next, the operation of the pressure-accumulation type fuel injection device configured as described above will be described with reference to the flowchart of FIG. When the diesel engine 3 is started, the cams 5 and 6 of the high-pressure pump 1 rotate, and along with this rotation, the pistons 9 and 10
Reciprocates and the fuel from the low pressure pump 13 receives the fuel from the high pressure pump 1
And the high pressure fuel is supplied to the fuel supply pipes 17, 18
Is supplied to the common rail 19 through the common rail 1
Fuel is accumulated in the fuel cell 9. Here, the ECU 27 controls the discharge amount of the high-pressure pump 1 so that the common rail pressure detected by the common rail pressure sensor 32 becomes an optimum value set according to the throttle opening and the rotation speed.

That is, the ECU 27 uses the crank angle sensor 2
When the pulse signal from 8 is input, the processing of FIG. 3 is started. First, in step 100, the ECU 27 takes in the common rail pressure by the common rail pressure sensor 32, the throttle opening by the throttle opening sensor 30, and the engine speed by the crank angle sensor 28. And
In step 101, the ECU 27 calculates the fuel discharge timing TF (see FIG. 2) of the high pressure pump 1 from the predetermined crank angle θa so that the common rail pressure becomes the optimum value set according to the throttle opening and the rotation speed. Furthermore, EC
In step 102, the U 27 determines whether or not the fuel discharge timing TF (fuel discharge amount) is equal to or greater than the predetermined value To, and if it is greater than or equal to, the normal processing for controlling the common rail pressure to the predetermined pressure is performed in step 103. That is, the discharge amount control solenoid valves 15 and 16 are set to the fuel discharge timing TF in FIG.
And the predetermined amount of high-pressure fuel is supplied from the high-pressure pump 1 to the common rail 19.

Further, the ECU 27 controls the opening and closing of the three-way control valve 31 of the injection valve 25 to inject the fuel amount corresponding to the operating state of the diesel engine 3 and injects the fuel in the common rail 19 into each cylinder of the diesel engine 3. ..

On the other hand, when the fuel supply pipes 17 and 18 are damaged, the high pressure fuel accumulated in the common rail 19 is
The check valves 21 and 23 restrict passage to the fuel supply pipes 17 and 18 side, and do not return to the high pressure pump side. Therefore, when the fuel supply pipes 17 and 18 are damaged, the fuel can be prevented from flowing out from the common rail side.

When the fuel supply pipes 17 and 18 are damaged, the amount of fuel supplied from the high-pressure pump 1 to the common rail 19 is reduced, and in step 101, the common rail pressure is controlled to a predetermined pressure so that the fuel discharge timing T is reached.
F (fuel discharge amount) is set to a small value, and the ECU 27 determines in step 102 that TF is below a predetermined value T0, and the fuel supply pipe 1
Step 104, assuming that 7 and 18 are damaged
Drive of the high-pressure pump 1 and fuel injection are stopped at.

As described above, in this embodiment, the fuel supply pipe 1
At the end of the common rail 19 side at 7, 18, the check valve 21,
23 is provided to allow the fuel supply from the high-pressure pump 1 to the common rail 19 and to restrict the passage of the fuel from the common rail 19 to the high-pressure pump 1. As a result, even if the fuel supply pipes 17 and 18 are damaged, the check valves 21 and 2 are
By 3, the passage of fuel from the common rail 19 to the fuel supply pipe 18 is regulated, and the outflow of high-pressure fuel can be prevented. (Second Embodiment) Next, only the difference between the second embodiment and the first embodiment will be described.

In this embodiment, even if one of the two fuel supply systems from the high-pressure pump 1 to the common rail 19 is damaged, only the remaining one is supplied with fuel.

As shown by the alternate long and short dash line in FIG. 1, the fuel supply pipes 17 and 18 are provided with pressure sensors 33 and 34, respectively.
The fuel pressure in the fuel supply pipes 17 and 18 by the pressure sensors 33 and 34 is taken into the ECU 27. Then, the ECU 27 determines that the fuel supply pipe 17 or 18 is damaged when the fuel pressure in the fuel supply pipe 17 or 18 by the pressure sensor 33 or 34 becomes equal to or lower than a predetermined pressure value, and determines that the discharge amount control solenoid valves 15 and 16 are damaged. Is controlled to stop the fuel supply to the damaged fuel supply pipe 17 or 18, and to supply the fuel through the remaining fuel supply pipe 18 or 17.

As described above, in this embodiment, the ECU 27 uses the signals from the pressure sensors 33 and 34 to send the fuel supply pipe 17,
It is judged whether or not 18 is damaged, and the fuel supply pipe 17 or 18
If one of them breaks, the remaining fuel supply pipe 18
Since the fuel supply to the common rail 19 is continued by using the or 17, the vehicle can be moved to a safe place even when the fuel supply pipe 17 or 18 is damaged when the diesel engine is mounted on the vehicle. It will be possible to do.

[0024]

As described in detail above, according to the present invention,
It has an excellent effect of preventing the fuel from flowing out due to the damage of the fuel pipe between the high-pressure pump and the common rail.

[Brief description of drawings]

FIG. 1 is a diagram showing an overall configuration of a diesel engine fuel injection device of an embodiment.

FIG. 2 is a time chart for explaining various processes.

FIG. 3 is a flowchart.

[Explanation of symbols]

 1 High-pressure pump 17 Fuel supply pipe 18 Fuel supply pipe 19 Common rail 21 Check valve 23 Check valve 24 Branch pipe 25 Injection valve

Claims (1)

Claim: What is claimed is: 1. A high pressure fuel is supplied from a high pressure pump through a fuel supply pipe, and a common rail for accumulating the fuel and a branch pipe provided for each cylinder of the internal combustion engine and branched from the common rail are provided. A pressure-accumulation system that includes a connected injection valve, controls the opening and closing of the injection valve to inject a fuel amount according to the operating state of the internal combustion engine, and injects the fuel in the common rail into each cylinder of the internal combustion engine. In the fuel injection device, a check valve is provided at an end of the fuel supply pipe on the common rail side, which allows fuel to be supplied from the high-pressure pump to the common rail and which restricts passage of fuel from the common rail to the high-pressure pump. An accumulator fuel injection device characterized by the above.