JP2943340B2 - 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 a pressure storage pipe (hereinafter, referred to as a common rail) which is a kind of surge tank for supplying high-pressure fuel.
The present invention relates to a pressure-accumulation type fuel injection device in which the accumulated high-pressure fuel is injected into a diesel engine by an electrically controlled injector.

[0002]

2. Description of the Related Art Conventionally, high-pressure fuel has been pressurized and sent to a common rail by a high-pressure supply pump to accumulate pressure.
2. Description of the Related Art A pressure accumulating fuel injection device in which high-pressure fuel of a common rail is injected into a diesel engine by an electrically controlled injector is known. In this configuration, it is necessary to provide a safety device for stopping the supply of fuel to the injector when an abnormality occurs in the injector.

[0003] Further, since the high-pressure fuel stored in the common rail is as high as 150 ° Pa, the reflected wave generated by the injector of one cylinder is propagated to the other cylinder via the common rail, and the opening and closing timing of the injector of that cylinder is increased. The fuel injection from the common rail to the injector, and provide a check valve in the injector piping that regulates fuel pressure from the injector to the common rail. Has already been proposed by the applicant.

However, the above-described safety device and check valve basically have different functions, and are provided independently of each other, and there is a problem that the assembling work is extremely troublesome. Therefore, in the present invention, a safety device capable of stopping the fuel supply to the injector when the injector is abnormal, and a non-return mechanism for restricting a reflected wave generated by the operation of the injector, and a pressure accumulating type excellent in assembling workability It is an object to provide a fuel injection device.

[0005]

According to the present invention, a common rail for accumulating high-pressure fuel is provided.
A fuel pipe for leading high-pressure fuel from the common rail;
An injector that is provided for each cylinder, receives fuel supplied from the fuel pipe, and is electrically controlled to inject fuel into the diesel engine; and an amount of fuel that is provided in the common rail or in the fuel pipe and flows inside. A safety device that shuts off the flow of fuel when the value exceeds an allowable range, and a safety device provided in the safety device, which allows only the supply of fuel from the common rail to the injector, and
Shut off fuel flow from the
And a check mechanism for restricting the propagation of pressure from the injector to the common rail.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 2 shows the overall configuration of the fuel injection device for a diesel engine of the present embodiment, and FIG. 3 shows injection valves provided for each combustion chamber of each cylinder of the engine.
In FIG. 3, a lower casing member 1 is a body lower 2.
, A connecting portion 3 and a nozzle body 4, and each member 2, 3, 4 is integrated by a retaining nut 5.
A valve body sliding hole 6 and a fuel reservoir 7 are formed in the nozzle body 4, and a nozzle hole 8 communicating with the fuel reservoir 7 is formed at the tip. The large diameter portion 10 of the nozzle needle 9 is slidably fitted in the valve body sliding hole 6. The large diameter portion 10 of the nozzle needle 9 has a connecting portion 11
Are formed, and a small diameter portion 12 and a valve body portion 13 are integrally formed at a lower end portion. Then, the seat portion x is opened and closed by the valve body portion 13, and the injection from the nozzle hole 8 is turned on / off.

[0007] A flange 14, a piston pin 15 and a hinston 16 are integrally connected to the tip of the connecting portion 11 of the nozzle needle 9. The nozzle needle 9 is urged in the closing direction by a spring 17. The piston 16 is slidably fitted in a cylinder 18 formed in the body lower 2, and a pressure control chamber 19 is formed in the cylinder 18 so as to face the end of the front piston 16.

A plate valve 20 having an orifice is provided above the pressure control chamber 19, and a spring 21 for pressing the plate valve 20 is provided. On the body lower 2, an upper casing member 23 having a three-way control valve 22 (electromagnetic valve) is tightly connected. That is, the cylindrical body upper 24 is screwed into the body lower 2, the three-way valve body 25 is disposed in the internal hole of the body upper 24, and the retaining nut 26 is screwed into the internal hole of the body upper 24.

The outer valve 2 is provided in the three-way valve body 25.
7 is slidably fitted, and an inner valve 28 is provided in an inner hole of the outer valve 27. When the coil 29 is demagnetized, the outer valve 27 is at the lower position by the force of the spring 30, and the high-pressure side passage 31 and the pressure control chamber 19 are communicated via the oil passage 32. When the coil 29 is excited, the outer valve 27 moves upward, and the pressure control chamber 19 and the drain passage (low-pressure side passage) 33 communicate with each other via the oil passage 32.

A fuel supply passage 34 is formed in the lower casing member 1, one end of which is exposed to the surface of the casing member (body lower 2) 1, the other end of which is communicated with the fuel reservoir 7, and Is connected to the high-pressure side passage 31 of the casing member 23. Further, an inlet 35 is screwed into a surface portion of the lower casing member (body lower 2) 1, and communicates with the fuel supply passage 34.

The high-pressure fuel of the common rail 38 is supplied to the fuel reservoir 7 through the inlet 35 and the fuel supply passage 34, and is supplied to the three-way control valve 22. The fuel in the drain passage 33 can be drained to a drain tank. Therefore,
When high-pressure fuel is supplied to the pressure control chamber 19, the force applied in the valve closing direction from the piston 16 to the nozzle needle 9 under this pressure exceeds the force applied in the valve opening direction by the pressure in the fuel reservoir 7. The nozzle needle 9 closes the nozzle hole 8. From this state, the three-way control valve 22 is controlled, the pressure control chamber 19 communicates with the low pressure side drain passage 33, and the fuel in the pressure control chamber 19 flows out to the low pressure side, so that the nozzle needle 9 moves in the valve opening direction. Fuel will be injected. At this time, the hydraulic pressure is
It descends slowly due to the action of the zero orifice.

As shown in FIG. 2, such an injection valve 36 for each cylinder is connected through an injection pipe 37 to a high-pressure accumulating pipe common to each cylinder, a so-called common rail 38. A high-pressure supply pump 41 is connected to the common rail 38 via a supply pipe 39 and a check valve 40. The high-pressure supply pump 41 is connected to the low-pressure supply pump 4 from the fuel tank 42.
The pressure of the fuel sucked in through the step 3 is increased to a predetermined high pressure and is controlled to a predetermined high pressure. That is, the cam 45 rotates in synchronization with the rotation of the engine 44, and the hinston 47 in the cylinder 46 moves forward to pressurize the fuel from the low-pressure supply pump 43 and supply the fuel to the common rail 38. Also, in order to always control the high pressure supply pump 41 to keep the common rail pressure at a predetermined pressure, that is, to control the amount of fuel to be pumped to the pressure accumulating pipe 38, the discharge amount control that closes at a predetermined timing during the pressure feeding stroke of the piston 47. The solenoid valve 48 is provided.

Electronic control unit (hereinafter referred to as ECU)
At 49, information on the number of revolutions and the load is input from the cylinder discrimination sensor 50, the crank angle sensor 51, and the load sensor 52, and the optimum injection timing and injection amount (injection amount) determined according to the engine state determined from these signals. The ECU 49 outputs a control signal to the three-way control valve 22 as shown in FIG. Further, a pressure sensor 53 for detecting a common rail pressure is provided on the common rail 38.
The amount of discharge is controlled so that this signal becomes an optimal value set in advance according to the load and the number of revolutions. That is, negative pressure feedback control is performed to perform more precise pressure setting.

A safety device 54 is provided between the common rail 38 and the injection pipe 37 as shown in FIG.
The safety device 54 includes a housing 58 having an inlet 56, a hollow cylindrical hole 60, a press-fit hole 64, and an outlet 65 formed therein, a piston 59 slidably disposed in the hollow cylindrical hole 60, a ball valve 57, And a spring 66 for urging the ball valve 57 toward the inlet 56. An axial orifice 55 and a radial passage 62 are formed in the piston 59, and an annular seat portion 63 that closes the introduction port 56 is formed.

Next, the operation of the safety device 54 will be described. In the safety device 54, during normal (normal) operation, the fuel corresponding to the injection amount flows into the safety device 54 from the common rail 38 with the operation of the injector 36. This fuel flows into the housing 58 from the inlet 56,
The piston 5 is pressed against the urging force of the spring 66 in accordance with the flow rate.
Move 9 In addition, the ball 57 moves integrally with the movement of the piston 59. The amount of movement of the ball 57 is set such that the amount of movement does not exceed an allowable value corresponding to the distance from the center of the ball 57 to the press-fitting hole 64 due to the flow of fuel in a normal operating state. Therefore, the fuel flowing from the inlet 56 passes around the ball 57 through the annular chamber 61 formed in the outer periphery of the annular seat portion 63, the radial passage 62, and the orifice 55, and passes through the outlet 65. I do. Then, fuel is supplied from the outlet 65 to the injector 36 through the injection pipe 37.

When the amount of fuel flowing from the common rail 38 into the injector 36 decreases, the ball 57 and the piston 59 are pushed back by the urging force of the spring 66, and the annular seat 63 introduction port 56 is closed. Therefore, when the fuel injection by the injector 36 is completed and a reflected wave is generated in the injection pipe 37 from the injector 36 side to the pressure accumulation pipe 38 side, the annular seat portion 63 of the piston 59 closes the introduction port 56 and the reflected wave Is prevented from propagating inside the common rail 38. This can prevent interference between cylinders (change in pressure in the common rail 38) which causes variation in injection timing and injection amount.

On the other hand, for example, a bug occurs in the microcomputer program of the ECU 49, or the three-way control valve 22
When the injection period of the injector 36 is prolonged due to the occurrence of an abnormality in the safety device 54 from the common rail 38.
The amount of fuel flowing into the tank increases. Then, the movement amount of the ball 57 and the piston 59 exceeds the allowable range, and the ball 57 is press-fitted into the press-fitting hole 64 and is permanently locked. Therefore, the safety device 54 completely stops supplying fuel to the injector 36.

As described above, according to this embodiment, the supply of fuel from the common rail 38 to the injector 36 can be stopped by the safety device 54 in the event of an abnormality, and the piston 59 can be stopped when fuel injection by the injector 36 ends. When the annular sheet portion 63 closes the inlet 56, the reflected wave can be prevented from propagating into the common rail 38. Moreover, since the two different mechanisms are integrally formed in the safety device 54, the assemblability thereof is greatly improved.

In the present embodiment, the safety device 54 is disposed between the common rail 38 and the injection pipe 37. However, the safety device 54 may be located at any position in the fuel pipe from the common rail 38 to the injector 36. good. Further, as shown in FIG. 4, the end of the piston 59 may be formed into a tapered shape 67 so that the seat surface 68 of the inlet 56 can be opened and closed.

Next, another embodiment of the present invention will be described with reference to FIG. In the embodiment shown in FIG.
An axial passage 73 is formed, a seat portion 74 is formed in the passage, and a check valve 70 for opening and closing the seat portion 74 is provided. The check valve 70 includes a plunger valve 72 and a spring 71, and opens when fuel flows from the common rail 38 to the injector 36, and opens when fuel flows from the injector 36 to the common rail 38. 1 and has the same effect as the embodiment shown in FIG.

[0021]

As described above, according to the present invention,
Provided only in the common rail or in the fuel pipe to the injector, when the amount of fuel flowing inside exceeds the allowable range, only the supply of fuel from the common rail to the injector is allowed inside the safety device that shuts off the fuel flow, and I
Block fuel flow from injector to common rail
Accordingly, by providing the check mechanism for restricting the pressure propagation from the injector to the common rail, the configuration is simplified, and the assemblability is greatly improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a configuration of a safety device according to an embodiment of the present invention.

FIG. 2 is a diagram showing an overall configuration of an embodiment of the present invention.

FIG. 3 is a cross-sectional view illustrating a configuration of an injector according to an embodiment of the present invention.

FIG. 4 is a sectional view showing the configuration of another embodiment of the safety device of the present invention.

FIG. 5 is a sectional view showing another embodiment of the safety device of the present invention.

[Explanation of symbols]

 36 Injector 37 Injection pipe 38 Common rail 54 Safety device 59 Piston 63 Annular seat part (check mechanism) 70 Check valve

──────────────────────────────────────────────────続 き Continuation of front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F02M 55/02 350 F02M 55/02 310 F02M 47/00 F02M 47/02

Claims (1)

(57) [Claims] 1. A common rail that accumulates high-pressure fuel, a fuel pipe that leads high-pressure fuel from the common rail, and is provided for each cylinder, receives fuel supplied from the fuel pipe, and is electrically controlled to produce a diesel engine. An injector for injecting fuel into the fuel cell, a safety device provided in the common rail or in the fuel pipe, and shutting off the fuel flow when the amount of fuel flowing through the fuel cell exceeds an allowable range; and a safety device provided in the safety device. Only allow the supply of fuel from the common rail to the injector, and
Block fuel flow from the injector to the common rail
And a check mechanism for restricting pressure propagation from the injector to the common rail.