JP2518622Y2 - Fuel injection pump for vehicle diesel engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a fuel injection pump for a vehicle diesel engine.

(Prior Art) As a fuel injection pump for a vehicle diesel engine,
There is a distributed pump that electronically controls fuel injection timing, fuel injection amount, etc. (Reference: Society of Automot)
ive Engineer 860145).

This will be explained with reference to FIG. 8. 1 is a pump housing, 2 and 3 are a low pressure side feed pump and a high pressure side plunger pump driven by a drive shaft 4, and the fuel sucked by the feed pump 2 from a fuel inlet (not shown) is The pressurizing chamber of the plunger pump 3 is supplied to the low pressure chamber 5 in the housing 1 and through the suction passage 6 opening to the low pressure chamber 5.
Sent to 12.

The plunger 7 of the plunger pump 3 has the same number of suction grooves 8 as the cylinders of the engine at the tip and is integrally formed with a cam disc 9 having the same number of face cams. The cam disc 9 rotates together with the drive shaft 4. While passing over the roller 11 arranged on the roller ring 10, it reciprocates by a predetermined cam lift.

Therefore, the plunger 7 reciprocates rotationally, and the fuel sucked from the suction groove 8 into the pressurizing chamber 12 with the reciprocating rotational motion passes through a delivery valve from a distribution port (not shown) communicating with the pressurizing chamber 12 through the delivery valve. It is pumped to the injection nozzle.

Then, in order to control the injection timing and injection amount of fuel,
A return passage 13 that connects the low-pressure chamber 5 and the pressurizing chamber 12 is formed, and a high-speed solenoid valve 14 is interposed in the return passage 13.

The solenoid valve 14 opens the pressurizing chamber 12 when the valve is opened, and is closed by a signal from a drive circuit (not shown) at a predetermined time and for a predetermined period according to the operating conditions of the engine.

The injection of fuel is started by closing the solenoid valve 14 during the pressure stroke of the plunger 7, and the injection is ended by further opening the solenoid valve 14. Therefore, the fuel injection timing is controlled by the closing timing of the solenoid valve 14. The injection amount is controlled by the closing period of the solenoid valve 14.

A fuel cut valve 15 shuts off the suction passage 6 when the engine is stopped.

(Problems to be solved by the invention) However, in the injection pump that controls fuel injection by closing and opening the solenoid valve 14 in this way, the solenoid valve 14 remains closed for some reason. In this case, for example, if the drive circuit of the solenoid valve 14 malfunctions and continues to send a close signal to the solenoid valve 14, fuel will be injected over the entire pressure delivery stroke of the plunger 7 regardless of the operating conditions of the engine, Therefore, there is a problem that the fuel injection amount becomes excessively large and an undesirable situation such as engine overrun occurs.

Further, when used in a vehicle engine, such an injection pump not only controls the opening / closing timing of the solenoid valve 14 so as to obtain the injection amount and the injection timing that match the operating conditions during normal operation of the engine, For example, when the air conditioner for cooling the vehicle compartment is in operation, control of the load must also be performed via the solenoid valve 14, which causes a problem that control becomes extremely complicated.

There is a safety device that limits the fuel injection amount to a predetermined value or less when the solenoid valve or the drive circuit is abnormal (see Japanese Patent Laid-Open No. Sho 60-98130, etc.). Since it operates, there is a fear of malfunctioning like the drive circuit of the solenoid valve, and reliability is low.

This invention aims at providing the fuel injection pump which solved such a problem.

(Means for Solving the Problem) The present invention relates to a diesel engine for a vehicle, in which fuel introduced from a low pressure chamber into a plunger pressurizing chamber is pressure-distributed to each cylinder by a plunger that reciprocates in synchronization with engine rotation. In the fuel injection pump, a fuel return passage that connects the plunger pressurization chamber and the low pressure chamber is formed, and an electromagnetic valve that closes the return passage at a predetermined injection start timing is provided, and the plunger pressurization chamber is connected to the plunger pressurization chamber. A spill passage that connects the low-pressure chamber is formed, and a control sleeve that opens the spill passage as soon as the accelerator pedal operates to reduce the amount of depression is provided, while operating the air conditioner for cooling the passenger compartment. Means for detecting the state and delaying the injection end timing of the control sleeve when the accelerator pedal is closed according to the detected value And a fuel amount increasing device for advancing the closing timing of the solenoid valve.

(Operation) Therefore, while the fuel injection is started by closing the solenoid valve, the fuel injection is ended by opening the spill passage by the control sleeve that works in conjunction with the accelerator pedal. Even if the solenoid valve is not injected and the solenoid valve drive circuit malfunctions and the solenoid valve remains closed, the fuel injection amount can be controlled by the accelerator pedal, and the fuel injection amount according to the accelerator opening can be obtained. To be

Further, the earlier the electromagnetic valve is closed, or the later the control sleeve opens the spill passage, the longer the injection period and the fuel injection amount increases. Therefore, when the air conditioner is in operation, the fuel increaser displaces the control sleeve in the retard direction of the injection end timing or corrects the closing timing of the solenoid valve in the advance direction according to the operating state (load state). As a result, the fuel amount is increased according to the load on the air conditioner.

(Embodiment) FIG. 1 is a cross-sectional view of the essential parts of a distribution type fuel injection pump according to an embodiment of the present invention, in which 21 is a plunger of a plunger pump 20 that reciprocates rotationally via a cam disk 22, and 23 is an illustration. A low pressure chamber to which fuel is supplied from the feed pump, and 24 is a suction passage for guiding the fuel from the low pressure chamber 23 to the pressurizing chamber 25 of the plunger pump 20.

Return passage that connects the pressurizing chamber 25 and the upstream side of the suction passage 24
26 is formed, and a solenoid valve 27 is interposed in the return passage 26.

The solenoid valve 27 is a poppet type valve body that opens and closes the return passage 26.
28, a spring 29 for urging the valve body 28 in the valve opening direction, and a coil 31 for pulling the valve body 28 through the armature 30 to close the valve body 28. Is arranged so as to act in the valve closing direction.

The electromagnetic valve 27 receives signals from a rotation sensor 32 that detects the rotation speed of an engine (not shown) and an accelerator opening sensor 33 (described later) that detects the opening of an accelerator pedal (not shown). The drive circuit 34 is driven and controlled so as to close the valve at a predetermined timing during the pressure-feeding stroke of the plunger 21 according to the operating conditions.

On the other hand, a spill passage 35 that penetrates the plunger 21 and connects the pressurization chamber 25 and the low pressure chamber 23 is formed, and the spill hole 36 that is an opening portion of the spill passage 35 on the low pressure chamber 23 side has a plunger 21.
A ring-shaped control sleeve 37 for opening and closing the spill hole 36 is slidably fitted therein.

The control sleeve 37 includes a shaft 40 which penetrates the housing 38 and engages with the control sleeve 37 via a ball joint 39, and a control lever 42 which engages with a rotating lever 41 fixed to the shaft 40 outside the housing 38. And it is connected to the accelerator pedal via a cable or the like not shown. The ball joint 39 is eccentrically attached to the tip of the shaft 40, and the control lever 42
Is rotatably attached to the shaft 40, and is engaged with the rotation lever 41 via a pin 43 protrudingly provided.

When the accelerator pedal is stepped on, the shaft 40 rotates via the pin 43 and the rotating lever 41 together with the control lever 42 according to the stepping, and this rotation causes the control sleeve via the ball joint 39 at the tip of the shaft 40.
37 is displaced to the right in the figure (the direction that retards the injection end timing). Further, when the accelerator pedal is returned, the control lever 42, the rotating lever 41, and the shaft 40 are rotated in the original direction by the return spring 44 provided on the rotating lever 41, and the control sleeve 37 is moved in the leftward direction in the drawing ( It is displaced in the direction of advancing the injection end timing).

As the plunger 21 moves, the spill hole 36 is opened when coming out of the control sleeve 37, and the opening timing is controlled according to the depression of the accelerator pedal, that is, according to the accelerator opening.

A position sensor 33 for detecting the position of the shaft 40 is provided to accurately detect the accelerator opening, and the position sensor 33 is used as the accelerator opening sensor 33.

On the other hand, as with the control lever 42, the shaft 40 is rotatably attached to the shaft 40 as shown in FIG. 2, and the increasing lever is engaged with the rotating lever 41 via the pin 43.
45 are provided. Pin the increase lever 45 to the increase lever 45.
A return spring 46, which urges in a direction away from 43, is attached, and a fuel amount increasing device 47 is engaged with one end of the amount increasing lever 45.

The fuel increasing device 47 includes a rod 48 that contacts the increasing lever 45.
And a rod 49 and a diaphragm 49 that connects the rod 48 and a diaphragm actuator. A compressor 52 (an electromagnetic clutch) of an air conditioner provided for cooling the vehicle interior through a pipe 51 into a pressure chamber 50 defined by the diaphragm 49. Is connected to the engine via the like).

When the air conditioner is not used (air conditioner switch 53 is OFF), the compressor 52 is not driven,
The discharge pressure is 0. In this state, as shown in FIG. 3, the rod 48 moves backward due to the urging force of the return spring 46 of the increasing lever 45, and the increasing lever 45 separates from the pin 43 of the rotating lever 41. If the accelerator pedal is closed, the rotation lever 41, shaft 40, control sleeve 37
Is kept at the initial position (predetermined idling position). In addition, an air conditioner is used (air conditioner switch
When the compressor 52 is driven, the rod 48 extends according to the discharge pressure of the compressor 52 as shown in FIG.
By pressing, if the accelerator pedal is closed,
The control sleeve 37 is displaced from the initial position by a predetermined amount in the right direction in the figure via the rotary lever 41 and the shaft 40. 54 is an adjusting screw for adjusting the amount of displacement of the control sleeve 37 at this time.

Although not shown, a timer device for controlling the lift timing of the cam disk 22 by rotating a roller ring 55 for lifting the cam disk 22 according to operating conditions is provided at the bottom of the housing 38.

With such a configuration, when the plunger 21 enters the pumping stroke and the solenoid valve 27 of the return passage 26 is closed by the drive circuit 34, the fuel introduced from the low pressure chamber 23 into the pressurizing chamber 25 via the suction passage 24 is released. , From the distribution port 56 communicating with the pressurizing chamber 25 to the injection nozzle of each cylinder via the terrivari valve 57, that is, fuel injection is started, and further the movement of the plunger 21 causes the spill hole 36 of the spill passage 35 to act as an accelerator pedal. Upon exiting from the control sleeve 37 which is displaced accordingly, the fuel in the pressurizing chamber 25 is released into the low pressure chamber 23, that is, the fuel injection is terminated.

Therefore, the injection start timing is controlled by the electromagnetic valve 27, the injection end timing is controlled by the accelerator pedal, and the injection amount is controlled according to the accelerator pedal.

By the way, when the drive circuit 34 malfunctions for some reason and the solenoid valve 27 of the return passage 26 remains closed, fuel injection is started from the beginning of the pressure feeding stroke of the plunger 21, but the injection is ended by the control sleeve 37. Is controlled by the accelerator pedal that displaces, so that the fuel injection amount does not increase significantly beyond the opening degree of the accelerator pedal. Moreover, in this case, the fuel injection amount can be controlled by relatively reducing the depression of the accelerator pedal, and the fuel injection amount according to the opening degree of the accelerator pedal can be secured.

Therefore, it is possible to reliably avoid engine overrun and the like due to malfunction of the electric system such as the drive circuit 34 and the solenoid valve 27,
In addition to high safety, normal operation can be continued even when the drive circuit 34 or the electromagnetic valve 27 fails, and safety and reliability are further improved.

Further, the solenoid valve 27 is closed during the pressure stroke of the plunger 21, but in this case, the high fuel pressure in the pressurizing chamber 25 acts in the valve closing direction of the solenoid valve 27, so that the solenoid valve 27 has a small electromagnetic force. The power consumption of the solenoid valve 27 is significantly reduced.

On the other hand, when the air conditioner is used, the engine load increases by driving the compressor 52, but in this case, the rod 48 of the fuel increasing device 47 pushes the increasing lever 45 according to the discharge pressure of the compressor 52, If the accelerator pedal is closed at this time, the control sleeve 37 is displaced from the initial position in the fuel increasing direction by a predetermined amount.

Therefore, when the air conditioner is used, the amount of fuel is increased in the idling region according to the discharge pressure of the compressor 52, that is, the load state of the compressor 52, so that stable idling operation is secured and the fuel consumption for the operation of the air conditioner is increased. Control becomes easy. The closing timing of the solenoid valve 27 in this case may be constant regardless of the operation of the air conditioner.

FIG. 5 shows another embodiment of the present invention, in which the pressure chamber 50 of the fuel increasing device 58 and the low pressure chamber 23 (first
(Refer to the drawing) is connected via an on-off valve (solenoid valve) 59, and the fuel amount increasing device 58 is operated by the fuel pressure in the low pressure chamber 23 when the air conditioner is used.

According to this, the amount of fuel increase is constant when the air conditioner is used, but this may be applied to, for example, an air conditioner using a fixed displacement compressor.

FIG. 6 also shows another embodiment of the present invention. Instead of providing a mechanism for displacing the control sleeve 37 when the air conditioner is used as in the above embodiment,
As the fuel amount increasing device 60, the closing timing of the solenoid valve 27 in the return passage 26 is advanced when the air conditioner is used. In this case, a second spill hole 61 is formed in the spill passage 35 of the plunger 21, and a relief passage 62 is formed which opens the second spill hole 61 to the low pressure chamber 23 at the beginning of the pressure feeding stroke of the plunger 21. 62 Spill cut solenoid valve that closes when using the air conditioner 63
Is intervening. In the figure, 64 is an electromagnetic clutch that connects the engine and the compressor of the air conditioner,
When the air conditioner switch 53 is turned on, it is operated together with the spill cut solenoid valve 63 via the relay 65.

Therefore, when using the air conditioner,
As shown in the figure, the closing timing of the solenoid valve 27 is advanced and the spill cut solenoid valve 63 of the relief passage 62 is closed, so that the fuel amount is increased, while the air conditioner is not used,
The amount of fuel is reduced by returning the closing timing of the solenoid valve 27 to its original state.At this time, however, the spill cut solenoid valve 63 opens, so the solenoid valve
Even if 27 malfunctions and the valve closing time is advanced,
There is no excessive fuel increase, and the safety of fuel control for the air conditioner is increased.

(Effect of the Invention) As described above, according to the present invention, a diesel engine for a vehicle that distributes the fuel introduced from the low pressure chamber into the plunger pressurizing chamber to each cylinder by the plunger that reciprocates in synchronization with the engine rotation. In a fuel injection pump of an engine, a fuel return passage that connects the plunger pressurization chamber and the low pressure chamber is formed, and an electromagnetic valve that closes the return passage at a predetermined injection start timing is provided, and the plunger pressurization is performed on the plunger. The spill passage that connects the low pressure chamber with the low pressure chamber is formed, and the spill passage is provided with a control sleeve that opens early as the depression amount decreases in conjunction with the accelerator pedal. And a means for detecting the operating state of the control sleeve and delaying the injection end timing of the control sleeve when the accelerator pedal is closed according to the detected value. Since the fuel amount increase device for correcting the displacement of the solenoid valve or the closing timing of the solenoid valve is provided, the fuel injection amount does not increase abnormally when the solenoid valve or its drive circuit malfunctions or fails. The fuel injection amount can always be accurately controlled by the accelerator pedal, and high safety and reliability can be obtained, and the injection amount can be increased according to the operating condition of the air conditioner when using the air conditioner. It can be simplified.

[Brief description of drawings]

1 and 2 are cross-sectional views showing the construction of essential parts of an embodiment of the present invention and a partial arrow view taken along the line AA, and FIGS. 3 and 4 are explanatory views of the operation of a fuel amount increasing device. 6 and 6 are partial structural views showing another embodiment of the present invention, FIG. 7 is an operation explanatory view of FIG. 6, and FIG. 8 is a sectional view of a conventional example. 21 ... Plunger, 23 ... Low-pressure chamber, 25 ... Pressurization chamber, 26 ...
… Return path, 27 …… Solenoid valve, 32 …… Rotation sensor, 33 ……
Accelerator position sensor, 34 …… Drive circuit, 35 …… Spill passage, 37 …… Control sleeve, 47,58,60 …… Fuel increasing device, 52 …… Compressor.

Claims (1)

(57) [Scope of utility model registration request] 1. A fuel injection pump of a diesel engine for a vehicle, wherein a plunger reciprocating in synchronization with engine rotation distributes pressure of fuel introduced from a low pressure chamber to a plunger pressurizing chamber to each cylinder. A fuel return passage that connects the pressure chamber and the low pressure chamber is formed, and a solenoid valve that closes the return passage at a predetermined injection start timing is provided, and the plunger has a spill passage that connects the plunger pressurization chamber and the low pressure chamber. The spill passage is provided with a control sleeve that opens as early as the depression amount decreases in conjunction with the accelerator pedal, while detecting the operating state of the air conditioner for vehicle compartment cooling,
A vehicle provided with a fuel increasing device for displacing the control sleeve in a direction to retard the injection end timing or advancing the closing timing of the solenoid valve when the accelerator pedal is closed according to the detected value. Fuel injection pump for diesel engine.