JP2897464B2 - Accumulator type fuel injection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an accumulator type fuel injection device used for a diesel engine or the like.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Unexamined Patent Publication No.
As disclosed in Japanese Patent Publication No. 8 (JP-A) No. 8, there is an accumulator type fuel injection device as one of the fuel injection devices for a diesel engine. In this method, high-pressure fuel from a high-pressure pump is accumulated in a kind of surge tank called a common rail, and this is injected and supplied to an engine by opening an injection valve. or,
In this type of apparatus, Japanese Patent Application Laid-Open No. 60-159366 discloses a device in which a safety device is provided for an injection valve and blocks a fuel supply passage when a predetermined amount or more of fuel is supplied to the injection valve due to damage to the injection valve. Have been.

[0003]

However, with this safety device, it is possible to prevent the fuel from leaking out of the injector due to the damage of the injector, but the safety pipe is damaged in the pipe between the high pressure pump and the common rail. If this occurs and the fuel spills out, this cannot be prevented and serious problems will result.

[0004] It is an object of the present invention to provide a pressure accumulating 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 for each cylinder of the internal combustion engine and branched from the common rail are provided. An injection valve connected through a pipe, wherein the injection valve is opened and closed so as to inject a fuel amount according to an operation state of the internal combustion engine, and fuel in the common rail is injected to each cylinder of the internal combustion engine. In the pressure-accumulation type fuel injection device, a check valve that allows supply of fuel from the high-pressure pump to the common rail and restricts passage of fuel from the common rail to the high-pressure pump at an end of the fuel supply pipe on the common rail side. The gist of the present invention is a pressure-accumulation type fuel injection device provided with.

[0006]

By driving the high-pressure pump, high-pressure fuel is supplied to the common rail through the fuel supply pipe, and the fuel is accumulated in the common rail. Then, the opening and closing of the injection valve is controlled, 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 passage of fuel from the common rail to the fuel supply pipe is restricted by the check valve, and high-pressure fuel on the common rail side is prevented 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 configuration of a fuel injection device for a diesel engine. The fuel injection device includes a two-cylinder high-pressure pump 1. The high-pressure pump 1 is provided with a drive shaft 2. The drive shaft 2 is drivingly connected to a crankshaft 4 of a diesel engine 3. Further, 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 lowering 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 downward.
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 disposed above the cylinders 7 and 8, and open and close the 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 pressurizing operation is performed 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 this pressurizing operation, the fuel discharge amount (shaded area in FIG. 2) can be adjusted. The discharge amount controlling solenoid valves 15 and 16 are opened at the top dead center (θ0 in FIG. 2) of the cam lift, and the fuel pressurization in the pressurizing chambers 11 and 12 is completed.

The pressurizing chambers 11 and 12 of the high-pressure pump 1 are connected by fuel supply pipes 17 and 18 to a common high-pressure accumulator pipe for each cylinder.
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 permit the supply of fuel from the high-pressure pump to the common rail, and restrict the passage of fuel from the common rail to the high-pressure pump.

An injection valve 25 for each cylinder of the diesel engine 3 is connected to the common rail 19 through a branch pipe 24. A flow limiter 26 is provided at an end of the branch pipe 24 on the common rail side, and the flow limiter 26 allows fuel supply to the injection valve 25 of a certain amount or less, and supplies the fuel to the injection valve 25 of a certain amount or more. Regulate the fuel supply. That is, when the injection valve 25 is damaged for any reason, the flow limiter 26 sets the injection valve 2
5 is limited.

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

Electronic control unit (hereinafter referred to as ECU)
Reference numeral 27 denotes an optimum injection timing which is inputted from the crank angle sensor 28, the cylinder discriminating sensor 29 and the throttle opening sensor 30 and receives information on the engine speed and the throttle opening, and is determined according to the engine state determined 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 discriminating sensor 29 outputs a signal of one pulse for each rotation of the drive shaft 2. It is.

Further, a common rail pressure sensor 32 for detecting a common rail pressure is provided on the common rail 19,
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 number of revolutions.

Next, the operation of the pressure-accumulation type fuel injection device thus configured will be described with reference to the flowchart of FIG. When the diesel engine 3 starts, the cams 5 and 6 of the high-pressure pump 1 rotate.
Reciprocates and the fuel from the low pressure pump 13 becomes high pressure pump 1
And the high-pressure fuel is supplied to the fuel supply pipes 17 and 18.
To the common rail 19 through the common rail 1
The fuel is accumulated in 9. Here, the ECU 27 controls the discharge amount of the high-pressure pump 1 so that the common rail pressure by the common rail pressure sensor 32 becomes an optimum value set according to the throttle opening and the number of revolutions.

That is, the ECU 27 controls the crank angle sensor 2
When the pulse signal from 8 is input, the processing of FIG. 3 is started. First, at step 100, the ECU 27 captures 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. And
The ECU 27 calculates the fuel discharge timing TF (see FIG. 2) of the high-pressure pump 1 from a predetermined crank angle θa so that the common rail pressure becomes an optimum value set according to the throttle opening and the number of revolutions in step 101. Furthermore, EC
U27 determines in step 102 whether or not the fuel discharge timing TF (fuel discharge amount) is equal to or greater than a predetermined value To, and if it is, in step 103, performs a normal process for controlling the common rail pressure to a predetermined pressure. That is, the discharge amount control solenoid valves 15 and 16 are set at the fuel discharge timing TF in FIG.
And a predetermined amount of high-pressure fuel is supplied from the high-pressure pump 1 to the common rail 19.

The ECU 27 controls the opening and closing of the three-way control valve 31 of the injection valve 25 to inject a fuel amount corresponding to the operation state of the diesel engine 3 and injects the fuel in the common rail 19 to 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 stored in the common rail 19 becomes
The check valves 21 and 23 restrict passage to the fuel supply pipes 17 and 18 and do not return to the high-pressure pump. Therefore, when the fuel supply pipes 17 and 18 are damaged, it is possible to prevent the fuel 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 decreases. In step 101, the common rail pressure is controlled to a predetermined pressure.
F (fuel discharge amount) is set small, and the ECU 27 determines in step 102 that TF is less than the predetermined value T0 and
Steps 104 and 107 are regarded as having been damaged.
To stop the driving of the high-pressure pump 1 and the fuel injection.

As described above, in this embodiment, the fuel supply pipe 1
A check valve 21 is provided at the end of the common rail 19 side at 7 and 18.
23 is provided to allow the supply of fuel from the high-pressure pump 1 to the common rail 19 and restrict the passage of 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
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 differences 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, the remaining one system supplies fuel.

In FIG. 1, pressure sensors 33 and 34 are provided in the fuel supply pipes 17 and 18 as indicated by a chain line.
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 pipes 17 and 18 by the pressure sensors 33 and 34 falls below a predetermined pressure value, and determines that the discharge amount control solenoid valves 15 and 16 To stop the fuel supply to the damaged fuel supply pipe 17 or 18, and supply the fuel through the remaining fuel supply pipe 18 or 17.

As described above, in the present embodiment, the ECU 27 uses the signals from the pressure sensors 33 and 34 to
It is determined whether or not the fuel supply pipe 18 has been damaged.
If one of them fails, the remaining fuel supply line 18
Or 17, the fuel supply to the common rail 19 is continued, so when the diesel engine is mounted on the vehicle, even if the fuel supply pipe 17 or 18 is damaged, the vehicle is moved to a safe place. It can be done.

[0024]

As described in detail above, according to the present invention,
An excellent effect of preventing fuel from flowing out due to breakage of the fuel pipe between the high-pressure pump and the common rail is exhibited.

[Brief description of the drawings]

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

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

FIG. 3 is a flowchart.

[Explanation of symbols]

 DESCRIPTION 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

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-124957 (JP, A) JP-A-61-138873 (JP, A) JP-A-62-258160 (JP, A) JP-A-2- 291472 (JP, A) JP-A-4-347358 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) F02M 55/02 350 F02M 55/02 330 F02M 55/02 310 F02M 55 / 00 F02M 47/00 F02M 63/00

Claims (1)

(57) [Claims] 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 an injection valve provided for each cylinder of the internal combustion engine and connected through a branch pipe branched from the common rail. A pressure-accumulation-type fuel injection device, comprising: opening and closing the injection valve to inject a fuel amount according to an operation state of the internal combustion engine to inject fuel in the common rail to each cylinder of the internal combustion engine. A check valve is provided at an end on the common rail side of the fuel supply pipe, which allows supply of fuel from the high pressure pump to the common rail and restricts passage of fuel from the common rail to the high pressure pump. Accumulator type fuel injection device.