JPH0158333B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in an operation control device for a diesel engine.

In the conventional fuel injection pump for a diesel engine, as shown in the schematic diagram of FIG. Fuel is injected and supplied to the engine 54 only while this is open. (Showa 55
(Refer to "Diesel Engine," a technical manual published by Nissan Motor Co., Ltd., August 2013) In the figure, 56 indicates an intake pipe, and 55 indicates an exhaust pipe.

As shown in FIG. 2, the injection pump 53 is configured to variably control the fuel injection amount according to the engine speed and required output.

First, fuel is sucked from an inlet 1 of a pump body by a feed pump 3 driven by a drive shaft 2 connected to an engine output shaft.

The supply pressure of the fuel discharged from the feed pump 3 is controlled by a pressure regulating valve 4, and the fuel is supplied to a pump chamber 5 inside the pump housing.

The fuel in the pump chamber 5 lubricates the operating parts and is simultaneously sent to the suction passage 6.

The suction passage 6 has a key switch 50 at the time of starting.
A fuel cut valve 7 is provided which continuously shuts off the passage 6 by turning ON and OFF. This fuel cut valve 7
When the engine is stopped, the valve body 8 shuts off the passage 6 by the pressing force of the spring 9, cutting off the subsequent supply of fuel, but when the key switch 50 is turned on, the solenoid 10 becomes conductive, and the engine stops. In operation,
The valve body 8 is sucked against the pressing force of the spring 9,
The passage 6 is communicated.

Therefore, the fuel in the suction passage 6 is sent to the high pressure plunger pump 12 through the suction port 11.

A plunger 13 of this pump 12 is fixed to an eccentric disk 14 connected to a drive shaft 2, and is driven by the drive shaft 2 via a joint 15 in synchronization with engine rotation.

The eccentric disk 14 has the same number of face cams 16 as the number of engine cylinders, and each time the face cams 16 pass over a roller 17 disposed on a roller ring 18 while rotating, the eccentric disk 14 reciprocates by a certain amount of cam lift.

Therefore, the plunger 13 reciprocates while rotating, and this reciprocating movement forces the fuel sucked in from the suction port 11 through the distribution port 22 and through the delivery valve 19 to an injection nozzle (not shown).

At that time, the fuel injection timing is determined by the roller ring 18.
can be freely adjusted by changing the relative position between the face cam 16 and the roller 17.

On the other hand, the amount of fuel to be injected is determined by the spill ring 2 covering the spill port 20 formed in the plunger 13.
First, it is determined by position. For example, when the opening of the spill port 20 crosses the right end of the spill ring 21 due to the right movement of the plunger 13,
The fuel that had been pressurized from the inside of the pump chamber 5 to the distribution port 22 is released to the pump chamber 5 through the spill port 20, thus ending the pressurization.

That is, the spill ring 21 is connected to the plunger 13.
If it is displaced relative to the right, the release of fuel pressure, that is, the end of fuel injection will be delayed, and the fuel injection amount will increase. Conversely, if it is displaced to the left, the end of fuel injection will be earlier. This results in a decrease in the amount of fuel injected.

The position of the spill ring 21 is controlled via a link lever section 25 by a control lever 23 that interlocks with an accelerator pedal (not shown) and a governor mechanism 24 that is driven by the rotation of the drive shaft 2. The fuel injection amount is increased or decreased in order to maintain the engine speed corresponding to the engine speed.

The link lever part 25 is an adjuster lever 2 fixed to the housing so as to be rotatable about a fulcrum A.
6 is pressed against the adjuster screw 28 by the pressing force of the spring 27 to fix the fulcrum B at one point, and the tension is rotated at the fulcrum B by the tensile force exerted by the control lever 23 on the control spring 29. The lever 30 and a start lever 32 that engages with the tension lever 30 via a start spring 31 are configured to be rotatably supported. The spill ring 21 is engaged with the tip of the start lever 32 via a ball joint 33.

On the other hand, the governor mechanism 24 includes a governor shaft 34 protruding from the housing, a gear 35 that operates around the governor shaft, a fly weight holder 36, a fly weight 37, and a governor sleeve 38, and as the drive shaft 2 rotates, When the gear 35 rotates via the drive gear 39, the fly weight holder 36 integrated therewith
The flyweight 37, which is supported by the flyweight holder 36 around the fulcrum 40, is expanded by the rotational centrifugal force. Then, the governor sleeve 38, which fits into the governor shaft 34 and engages with the flyweight 37, slides on the flyweight 37.

However, since the start lever 32 is always in contact with the governor sleeve 38 due to the pressing force of the start spring 31, the governor sleeve 38
8, the spill ring 21 rotates around the fulcrum B and moves the spill ring 21. As a result, the amount of fuel injected is feedback-controlled to the characteristics shown in FIG.

That is, when the engine is operated, when the accelerator pedal (not shown) is depressed by an arbitrary amount, the control lever 23 rotates, and the control spring 29 stores a tension corresponding to the amount of the amount of depression. The tension lever 30 is pulled by this tension and rotates around the fulcrum B. At the same time, the start lever 32 engaged with the tension lever 30 rotates to move the spill ring 21 in the direction of increasing fuel. Eventually, the engine speed will reach the speed corresponding to the pedal stroke, but at this time the governor 24
The rotational speed of the start lever 32 also increases sufficiently, and the rotational centrifugal force of the flyweight 37 pushes the start lever 32 back in the direction of fuel reduction against the pressing force of the spring 29.

Therefore, as the engine speed increases, a downward trend toward the right appears as shown in the figure, in which the fuel decreases.

When starting, when the accelerator pedal (not shown) is depressed and the control lever 23 is rotated in the full direction, the control spring 2
Tension is stored in the lever 9, and the tension lever 30 is pulled and rotated about the fulcrum B until it comes into contact with the stopper 41. As a result, the weakly tensioned start spring 31 presses the start lever 32 against the governor sleeve 38, completely closing the stationary flyweight 37, and moves the spill ring 21 to the right to move the spill port. 21 is fully closed over the entire stroke of the plunger 13. This ensures a starting increase.

When the engine starts, the control lever 23
When the (accelerator pedal) is returned to the idle position, the tension of the control spring 29 becomes the initial setting value, and therefore the governor sleeve 38 pushes back the start lever 32, moves the spill ring 21 to the left, and Moving on to fuel injection amount characteristics.

At this time, in order to stabilize the idling operation by the action of the damper spring 42, the downward trend of the idling characteristic to the right is weakened, forming a broken line portion in the characteristic diagram.

In this way, the governor mechanism 24, which controls the fuel injection amount according to the engine speed, uses the control spring when the engine is braked, that is, when the engine suddenly decelerates from high speed with the accelerator being released (idling). Although the tension of 29 is the initial setting value, the governor mechanism 24 rotates at high speed, moves the spill ring 21 to the left, and opens the spill port 20 over the entire stroke of the plunger 13.
The fuel leaks into the pump chamber 5 and the fuel is shut off.

When such a fuel cut is performed, injection is restarted at a rotation below point A in FIG. 3, but at this time, if point A is too low, the inertia of the governor mechanism 24 and spill ring 21 Since the return speed may drop too low and cause the engine to stall, set the A point to 2000 rpm.
It is high enough to be nearby.

However, since the rotation speed of 2000 rpm is, for example, about 60 km/r in top gear, unnecessary fuel is injected with engine braking in the practical range. In addition, the fuel cannot be completely shut off even at point A or higher, which not only wastes fuel, but also causes HC gas to be discharged.

On the other hand, in a diesel engine, the intake air is compressed 20 to 30 times, so if the intake air is throttled while the exhaust passage is open, the actual compression ratio will decrease and the compression work loss of the engine will decrease. If this is applied during engine braking, coasting performance will be improved accordingly.

This invention was made by focusing on such conventional problems and the characteristics of engines, and detects engine braking from the accelerator opening, clutch state, transmission engagement state, engine rotation, etc. To provide a control device for a diesel engine that improves fuel efficiency by cutting off fuel using a fuel cut valve that immediately cuts off communication between a fuel passage and by throttling only an intake passage.

Embodiments of the present invention will be described below based on the drawings.

FIG. 4 is a wiring diagram showing one embodiment of the present invention.

An electromagnetic switch 61 is connected to the engine key switch 50, which conducts the power supply current of the battery 51 at the time of starting, and which operates by switching from a normally closed contact a to a normally open contact b only when a coil 60 is energized. A fuel cut valve 7 that opens the passage only when energized is connected to the a contact, and an intake throttle valve actuator 6 that fully closes the intake passage only when energized is connected to the b contact.
Connect 2.

By the way, the coil 60 is connected to the engine key switch 50 via three electromagnetic switches 63, 64, and 65 connected in series.
It is energized and energized only when 3, 64, and 65 are all closed.

The electromagnetic switch 63 is electrically conductive when the coil 67 is excited, and the coil 67 is connected to an accelerator switch 66 that is turned on when the accelerator pedal is pressed down to zero.

Similarly, the electromagnetic switches 64 and 65 become conductive when the corresponding coils 68 and 70 are excited, the coil 68 is connected to a transmission switch 69 that is turned on when the transmission is not in neutral, and the coil 70 is connected to a transmission switch 69 that is turned on when the transmission is not in neutral. It is connected to a clutch switch 71 that is turned on when the pedal is not depressed.

Next, the action will be explained.

When you turn on the ignition key switch 50,
Since the electromagnetic switch 61 is electrically connected to contact a,
The fuel cut-off valve 7 opens, the engine is enabled to operate, and the fuel injection amount is controlled according to the same characteristics as in the past.

During engine braking, the accelerator pedal has no travel distance, is not in neutral, and the clutch is engaged, so the accelerator switch 60 and transmission switch 6
9. The clutch switches 71 are all conductive, and therefore, the electromagnetic switches 68, 64, 65 are all turned on by excitation of the respective coils 67, 68, 70.
As a result, the coil 60 is excited and the electromagnetic switch 61 is switched from contact a to contact b.

Therefore, the fuel cut valve 7 is demagnetized to cut off the fuel passage, and the intake throttle valve actuator 6 is also demagnetized.
2 to narrow the intake air passage.

That is, during engine braking, fuel is immediately cut off and intake air is throttled.

When the engine braking condition is resolved, for example, when the engine braking ends and acceleration begins, switch 6
6 and returns to the original fuel control system, and sufficient intake air is supplied.

FIG. 5 shows another embodiment.

This embodiment differs from the embodiment shown in FIG. 4 above.
A switch 72 is provided that detects the engine speed and turns on when the engine speed is above a predetermined speed, and an electromagnetic switch 74 is controlled to open and close by a coil 73 that is energized when the switch 72 is turned on.
are connected in series with electromagnetic switches 63, 64, and 65.

As a result, the engine speed will not drop too low in the unlikely event that the engine stalls as soon as the clutch is engaged, which can be avoided.

Furthermore, as shown in FIG.
If an electromagnetic relay 76 is provided between the intake throttle valve actuator 62 and the intake throttle valve actuator 62, an electromagnetic relay 76 in which a coil 75 is energized intermittently by the operation of the brake is provided.
2 can be prevented from being activated.

As explained above, according to the present invention, fuel is instantly and completely cut off during engine braking, and by throttling the intake air, the compression work during coasting is reduced and fuel efficiency is improved.
Exhaust gas can be purified.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of a conventional diesel engine, FIG. 2 is a sectional view of its injection pump, and FIG. 3 is a characteristic diagram of its engine speed and injection amount. FIG. 4 is a wiring diagram of one embodiment of the invention, and FIGS. 5 and 6 are wiring diagrams of other embodiments. 7...Fuel cut valve, 50...Key switch,
61... Solenoid switch, 62... Intake throttle valve actuator, 63, 64, 65... Solenoid switch,
66...Accelerator switch, 69...Transmission switch, 70...Clutch switch.

Claims (1)

[Scope of Claims] 1. Control of an intake throttle valve provided in an intake passage, a fuel cut valve that stops fuel supply from a fuel injection pump, means for detecting an engine brake state, and the intake throttle valve and fuel cut valve. and the control means is configured to drive a fuel cut valve to cut off fuel supply during engine braking, and reduce the opening degree of the intake throttle valve to throttle the intake passage. A diesel engine control device characterized by narrowing only the intake passage while leaving the exhaust passage open. 2. The engine brake detection means is characterized by comprising a series circuit of a switch for detecting the fully returned position of the accelerator pedal, a switch for detecting positions other than the neutral position of the transmission, and a switch for detecting engagement of the clutch. A control device for a diesel engine according to claim 1.