JPH11270358A - Control device for diesel engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device for a diesel engine capable of speedily stopping driving. SOLUTION: A diesel engine furnished with a distributor type fuel injection pump is provided with a demand fuel injection quantity computing part 31 to retrieve demand fuel injection quantity Q in correspondence with engine speed N and an accelerator opening TVO in accordance with a driving map, a fuel injection quantity computing part 32 for engine stopping to retrieve the demand fuel injection quantity Q in correspondence with the engine speed N in accordance with a drive stopping map and a map changeover means 33 to changeover the maps in correspondence with ON and OFF of an ignition switch. Additionally, a control sleeve is gradually moved at specified speed toward the direction to accelerate driving stop of an engine at the time when a driving stop condition is established.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for stopping fuel injection when stopping operation of a diesel engine.

[0002]

2. Description of the Related Art A conventional diesel engine equipped with an electronically controlled distribution type fuel injection pump is disclosed in, for example, Japanese Patent Application Laid-Open No. 6-272635.
As disclosed in JP-A-8-319855 and the like, a control sleeve for releasing fuel discharged from a plunger high-pressure chamber at the end of pressure feeding for adjusting a fuel injection amount, and an actuator for driving the control sleeve are provided. A fuel cut valve for shutting off fuel supplied to the plunger high pressure chamber for stopping operation is provided.

Usually, the operation of the engine is stopped by shutting off fuel supplied to the plunger high-pressure chamber by a fuel cut valve. If any abnormality occurs in the operation of the fuel cut valve, the abnormality is diagnosed, the control sleeve is moved to the non-injection position, and the operation of the engine is stopped, so that fail-safe is achieved.

However, in such a conventional diesel engine control device, when the operation of the engine is stopped, the fuel cut valve normally operates to shut off the fuel supplied to the plunger high pressure chamber. Even
There was a possibility that the operation of the engine did not stop immediately.

As will be described later, this phenomenon is likely to occur when the volume of a suction port or the like connecting the fuel cut valve and the plunger high pressure chamber is large, and the pressure gradient generated in the plunger high pressure chamber during the compression stroke of the plunger affects the pressure. It is considered that a large amount of fuel flows back during the suction stroke from the cut-off port opened by the control sleeve to the plunger high-pressure chamber as the plunger reciprocates.

Accordingly, the present applicant has filed a Japanese Patent Application No. 9-269.
No. 850 has already been proposed in an engine equipped with a distribution type fuel injection pump, when the fuel cut valve is closed and the fuel supplied to the plunger high pressure chamber is shut off when the operation stop condition is satisfied. By immediately moving the control sleeve to the maximum injection position that closes the cutoff port over the entire stroke of the plunger, the flow of fuel flowing backward from the cutoff port to the plunger high-pressure chamber is shut off.

However, if the moving speed of the control sleeve is as high as the speed at which the plunger strokes, as described later, the control sleeve moves to the maximum injection position after the fuel cut valve closes, and the control sleeve moves to the plunger high pressure chamber. When the fuel is confined and the confined fuel is injected, a rotation fluctuation occurs, and there is a possibility that the stop of the operation is delayed to some extent. In this case, of course, the operation is stopped, but the shorter the delay time, the better.

The present invention has been made in view of the above problems, and has as its object to provide a diesel engine control device capable of stopping operation promptly.

[0009]

According to a first aspect of the present invention, there is provided a diesel engine control device comprising: a means for detecting an accelerator opening; a means for detecting an engine speed; and a request from an accelerator opening and an engine speed. Means for determining the fuel injection amount, a fuel injection pump having a plunger for pumping the injected fuel to the engine, means for adjusting the injection amount of the fuel injection pump according to the required fuel injection amount, and The present invention is applied to a control device for a diesel engine including a determination unit and a unit that shuts off the introduction of fuel to a plunger when an operation stop condition is satisfied.

[0010] Further, there is provided means for gradually moving the adjusting means toward a position promoting the operation stop when the operation stop condition is satisfied.

According to a second aspect of the present invention, there is provided a diesel engine control device, wherein a plunger reciprocates in synchronization with engine rotation, and fuel sucked from an intake port is pressure-fed from a distribution port to each cylinder by the reciprocating motion of the plunger. A plunger high-pressure chamber, a fuel cut valve that shuts off fuel supplied from the suction port to the plunger high-pressure chamber, and a fuel discharged from the plunger high-pressure chamber by opening a cut-off port opened on the outer peripheral surface of the plunger at the end of pressure feeding. A control sleeve for releasing the control sleeve, an actuator for driving the control sleeve, a means for determining when the operation stop condition is satisfied, and a fuel cut valve closed when the operation stop condition is satisfied to supply the fuel from the suction port to the plunger high pressure chamber. Diesel engine with means for shutting off the fuel To apply to the emissions of the control device.

[0012] Further, there is provided means for gradually moving the control sleeve toward a position promoting the operation stop when the operation stop condition is satisfied.

According to a third aspect of the present invention, in the diesel engine control device according to the second aspect of the present invention, the control sleeve extends over the entire stroke of the plunger as the control sleeve position for promoting the stoppage when the stoppage condition is satisfied. To the maximum injection position without opening the cut-off port.

According to a fourth aspect of the present invention, there is provided a diesel engine control device according to the second or third aspect, wherein the plunger controls the speed at which the control sleeve is moved to a position promoting the operation stop when the operation stop condition is satisfied. Was set lower than the reciprocating speed.

According to a fifth aspect of the present invention, in the diesel engine control device according to the fourth aspect, the speed at which the control sleeve is moved toward the position for promoting the stop of the engine when the stop condition is satisfied is set to 0. It was set to move the full stroke amount within a time period from 0.02 seconds to 0.2 seconds.

According to a sixth aspect of the present invention, there is provided a control apparatus for a diesel engine according to any one of the second to fifth aspects, wherein the control sleeve is moved toward a position promoting the stop of operation. The control sleeve is moved closer to the minimum injection position as the engine speed rises above a predetermined value.

According to a seventh aspect of the present invention, there is provided a control apparatus for a diesel engine according to any one of the second to sixth aspects, wherein the control sleeve is moved toward a position promoting operation stop. The configuration is such that it is determined whether or not the operation of the fuel cut valve is abnormal based on the behavior of the engine speed.

[0018] In the diesel engine control device according to the present invention, in the invention according to the seventh aspect, the determination of the abnormality may be performed during a period from when the fuel cut valve is closed until a predetermined time elapses. When the rotation does not stop, it is determined to be abnormal.

According to a ninth aspect of the present invention, in the diesel engine control device according to the eighth aspect, when it is determined that the operation of the fuel cut valve is abnormal, the control sleeve is moved to the full stroke of the plunger. In this configuration, the cut-off port is moved to the non-injection position to be opened.

[0020] The control apparatus for a diesel engine according to a tenth aspect of the present invention is the operation apparatus according to any one of the first to ninth aspects, wherein the required fuel injection amount is set according to the engine speed and the accelerator opening. And an operation stop map in which the required fuel injection amount is set to be maximum as the engine speed falls below a predetermined value. When the operation stop condition is satisfied, the operation map is switched to the operation stop map. To calculate the required fuel injection amount.

According to an eleventh aspect of the present invention, in the diesel engine control device according to any one of the first to ninth aspects, the drive voltage of the actuator for driving the control sleeve is controlled by the engine speed and the required fuel injection. An operation map set in accordance with the amount and an operation stop map in which the drive voltage of the actuator is set to a predetermined maximum value when the engine speed is equal to or lower than a predetermined value, and the operation map is stopped when the operation stop condition is satisfied. The configuration is such that the driving voltage of the actuator is controlled by switching to the map.

[0022]

In the control apparatus for a diesel engine according to the first aspect, the introduction of fuel to the plunger is shut off when the operation stop condition is satisfied. And, by gradually moving the adjusting means toward the position promoting the operation stop, the fuel is prevented from flowing back to the plunger and the fuel is prevented from being trapped in the plunger high pressure chamber, and the operation of the engine is stopped immediately. it can.

As a result, for example, even in the case of a six-cylinder engine or the like having a large capacity of the suction port in the distribution type fuel injection pump, the operation of the engine can be stopped immediately and the driver can be prevented from feeling uncomfortable.

The present invention can be applied not only to an engine having a distribution type fuel injection pump but also to an engine having a row type fuel injection pump and an engine having another fuel injection system.

According to a second aspect of the present invention, there is provided a control system for a diesel engine having a distribution type fuel injection pump, wherein a fuel cut valve is closed when an operation stop condition is satisfied, so that the intake port is connected to the plunger high pressure chamber. The supplied fuel is shut off.

After closing the fuel cut valve,
In the conventional device in which the position of the control sleeve is fixed, fuel flows backward from the cut-off port to the plunger high-pressure chamber during the suction stroke, and the back-flowed fuel escapes from the cut-off port during the compression stroke. There was a possibility that the operation was not immediately stopped because the cylinder was pressure-fed from the distribution port to each cylinder.

According to the present invention, in order to cope with this, the control sleeve is gradually moved after the fuel cut valve is closed, so that the fuel is prevented from being trapped in the plunger high pressure chamber, the operation can be stopped immediately, and the driver can be stopped. You do not have to feel uncomfortable.

In the diesel engine control device according to the third aspect, when the operation stop condition is satisfied, the control sleeve gradually moves toward the maximum injection position closing the cutoff port over the entire stroke of the plunger, While gradually reducing the amount of fuel flowing back from the cut-off port to the plunger high pressure chamber during the suction stroke,
Since the fuel is prevented from being confined in the plunger high-pressure chamber and the amount of fuel fed from the distribution port to each cylinder during the compression stroke is gradually reduced, the operation can be stopped immediately.

In the control apparatus for a diesel engine according to the fourth aspect, the speed at which the control sleeve is moved toward the position promoting the operation stop when the operation stop condition is satisfied is set lower than the speed at which the plunger reciprocates. The amount of fuel flowing backward from the cut-off port to the plunger high-pressure chamber can be reduced while suppressing the fuel from being trapped in the high-pressure chamber, and the operation can be stopped immediately.

In the diesel engine control apparatus according to the fifth aspect, the speed at which the control sleeve is moved when the operation stop condition is satisfied is set such that the full stroke amount is moved within a time period from 0.02 seconds to 0.2 seconds. Therefore, the amount of fuel flowing backward from the cutoff port to the plunger high-pressure chamber is reduced while suppressing the fuel from being trapped in the plunger high-pressure chamber, and the operation of the engine is quickly stopped.

In the control apparatus for a diesel engine according to the present invention, if the fuel cut valve normally closes and the suction port is shut off when the operation stop condition is satisfied, the control sleeve lowers the engine speed. Then, it moves to the maximum injection position side. As a result, the operation of the engine can be stopped immediately.

When the fuel cut valve does not normally close and the suction port is not shut off, the control sleeve moves away from the maximum injection position and moves to the minimum injection position as the engine speed increases. As a result, the engine speed can be maintained at a certain value or less, and the driver does not feel uncomfortable.

[0033] In the control apparatus for a diesel engine according to the seventh aspect, after the fuel cut valve is closed in an operation state in which the control sleeve is moved to a position promoting the operation stop, the engine speed is quickly reduced to zero. When the engine speed decreases, it can be determined that the fuel cut valve is operating normally, and when the engine speed does not rapidly decrease, it can be determined that the operation of the fuel cut valve has failed.

The diagnosis of the fuel cut valve is performed by moving the control sleeve toward the position promoting the stop of the operation, so that the diagnosis accuracy can be prevented from being deteriorated due to the backflow of the fuel from the cutoff port.

In the diesel engine control device according to the present invention, when the engine rotation does not stop within a predetermined time after the fuel cut valve is closed, the operation of the fuel cut valve is abnormal. judge.

In the diesel engine control device according to the ninth aspect, when it is determined that the operation of the fuel cut valve is abnormal, the control sleeve opens the cutoff port over the entire stroke of the plunger. By moving the engine toward the non-injection position, the operation of the engine is stopped. As a result, fail-safe operation corresponding to a failure of the fuel cut valve or the like is achieved.

In the diesel engine control device according to the tenth aspect, the required fuel injection amount is calculated according to the engine speed and the accelerator opening based on an operation map set in advance during operation of the engine, and the required fuel injection amount is calculated according to the operating state. Thus, the fuel injection amount is controlled.

When the fuel cut valve operates normally and the suction port is shut off when the operation stop condition is satisfied,
The required fuel injection amount is increased as the engine speed decreases based on the map set in advance, and the control sleeve is moved toward the maximum injection position that promotes operation stoppage. As a result, the operation of the engine can be stopped immediately.

If the fuel cut valve does not normally close and the intake port is not shut off, the required fuel injection amount is reduced as the engine speed increases based on the operation stop map characteristic. Move toward the non-injection position. As a result, the engine speed can be maintained at a certain value or less, and the driver does not feel uncomfortable.

In the diesel engine control device according to the eleventh aspect, the driving voltage of the actuator is calculated according to the engine speed and the required fuel injection amount based on an operation map set in advance during the operation of the engine, and the operation state is set. The fuel injection amount is controlled accordingly.

When the fuel cut valve operates normally and the suction port is shut off, the driving voltage of the actuator is increased as the engine speed decreases based on a map set in advance when the operation stop condition is satisfied. In addition, the control sleeve can be moved toward the maximum injection position that promotes the stop of operation, and the operation can be stopped immediately.

When the fuel cut valve does not normally close and the suction port is not shut off, the drive voltage of the actuator is reduced as the engine speed increases based on the operation stop map characteristic, and the control sleeve is not used. Move toward the injection position. As a result, the engine speed can be maintained at a certain value or less, and the driver does not feel uncomfortable.

[0043]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows a fuel injection system for a diesel engine.

In FIG. 1, an input shaft 6a of a fuel injection pump 1 which is driven to rotate in synchronization with the rotation of a diesel engine.
Is equipped with a feed pump 6 for pre-pressurizing the fuel,
Further, a plunger 2 connected so as to rotate in the same direction as the input shaft 6a and reciprocate in the axial direction is disposed coaxially.

The feed pump 6 sends out the pressurized fuel to the pump chamber 7, and excess fuel is returned to a fuel tank (not shown) to maintain the pressure in the pump chamber 7 constant.

The plunger 2 is coaxially provided with a face cam 2a having cam lobes corresponding to the number of cylinders. Each time the face cam 2a rides on the roller 8a, the plunger 2 reciprocates in the axial direction. For example, in the case of a six-cylinder diesel engine, when the input shaft 6a makes one rotation, the face cam 2a rides on the roller 8a six times during this time, and the plunger 2 reciprocates six times. Each time the plunger 2 reciprocates, fuel is sucked into the plunger high-pressure chamber 2b,
Apply pressure. A return spring 2k pushes back the plunger 2 against the face cam 2a.

In the extension stroke of the plunger 2, fuel from the pump chamber 7 is sucked into the plunger high-pressure chamber 2b through the suction port 2n and the slit 2j provided in the plunger 2.

On the other hand, the pressurized fuel in the plunger high-pressure chamber 2b is fed to the fuel injection nozzle 11 of each cylinder in the compression stroke of the plunger 2, so that it communicates with the plunger high-pressure chamber 2b along the axis of the plunger 2. A communication passage 2c is formed, and a high-pressure passage 2d branches in the radial direction from the middle of the communication passage 2c. Further, a cutoff port 2e penetrating through the plunger 2 in the radial direction branches off from the distal end of the communication passage 2c.

Ports 2g of a number corresponding to the number of cylinders of the diesel engine are equally provided on the inner periphery of the cylinder 2f around the plunger 2 so as to be selectively connected to the high pressure passage 2d according to the rotational position of the plunger 2. , And a delivery valve 2h (only one is shown) is connected to each port 2g, and fuel is pressure-fed from the delivery valve 2h to the fuel injection nozzle 11.

The plunger 2 reciprocates six times each time it rotates, and pressurizes the inhaled fuel each time. The pressurized fuel is pushed from the communication passage 2c into the high-pressure passage 2d. The pressurized fuel is sent to the port 2g, and the fuel is fed to the fuel injection nozzle 11 via the corresponding delivery valve 2h.

On the other hand, a control sleeve 3 is slidably fitted on the outer periphery of the plunger 2 and normally covers the cut-off port 2e so as to be closed. Cut-off port 2e
To release. Thereby, the pressure of the plunger high pressure chamber 2b is released, and the fuel injection nozzle 1
The pumping of the fuel to 1 ends.

The fuel injection nozzle 11 has a delivery valve 2h
The fuel (not shown) lifts a needle (not shown) to open the injection port, and directly injects fuel from the injection port to each cylinder.

Therefore, the amount of fuel fed into the fuel injection nozzle 11 varies depending on the position of the control sleeve 3. If the cutoff port 2e is opened early when the plunger 2 moves in the compression direction, the fuel injection amount will be reduced. If the opening timing of the cutoff port 2e is delayed, the fuel injection amount increases.

In order to control the fuel injection amount, a rotary solenoid 4 for freely changing the position of the control sleeve 3 is provided. The rotary solenoid 4 is supplied with a fuel injection signal from a control unit 18 mainly composed of a microcomputer or the like, and changes the position of the control sleeve 3 according to the signal. The position of the control sleeve 3 is detected by the position sensor 5 and is fed back to the control unit 18.

FIG. 2 is a characteristic diagram showing the voltage output to the rotary solenoid 4 and the state of injection from the fuel injection nozzle 11. The voltage output to the rotary solenoid 4 is V ₁
In the range of V ₂ is the fuel injection quantity control during normal operation is carried out from. The voltage output to the rotary solenoid 4 is V ₁ is smaller than the non-injection region, to open the cutoff port 2e is control sleeve 3 over the entire stroke of the plunger 2, the fuel injection amount is zero. Rotary solenoid 4
Voltage output is the V ₂ greater than the maximum injection zone, by closing the cutoff port 2e is control sleeve 3 over the entire stroke of the plunger 2, the fuel injection amount becomes the maximum.

As will be described later, the control unit 18 searches the required injection amount Q in accordance with the engine speed and the accelerator opening based on the operation map shown in FIG. The driving voltage sent to the solenoid 4 is controlled.

Next, the position of the face cam 2a in the circumferential direction of the roller 8a on which the face cam 2a rides is controlled by the timer piston 8. In addition,
The illustrated timer piston 8 is rotated by 90 degrees from the actual position for convenience of explanation. A low-pressure chamber 8b and a high-pressure chamber 8c are provided on both sides of the timer piston 8, and the pressure in the high-pressure chamber 8c is adjusted by controlling the amount of a part of the high-pressure fuel released to the low-pressure chamber 8b by the control valve 9. Thus, the position of the timer piston 8 changes.

When the position of the timer piston 8 changes and the position of the roller 8a is advanced in the rotation direction of the face cam 2a,
The position at which the face cam 2a rides on the roller 8a is relatively delayed, and the timing of starting pressurization of the fuel by the plunger 2, that is, the fuel injection timing is delayed.
If the position of the roller 8a is delayed in the direction opposite to the rotation of the roller, the pressure start timing by the plunger 2 is advanced, and the fuel injection timing is advanced.

The signal from the control unit 18 controls the operation of the control valve 9 in accordance with the operating state, adjusts the position of the timer piston 8,
The fuel injection timing is advanced and retarded.

The control unit 18 has a nozzle lift sensor 1 for detecting the valve opening timing of the fuel injection nozzle 11.
2, a fuel temperature sensor 15 for detecting the temperature of the fuel supplied to the fuel injection pump 1, a cooling water temperature sensor 13 for detecting the cooling water temperature of the diesel engine, an accelerator opening sensor 16 for detecting the accelerator opening, and pump rotation. A signal from the engine speed sensor 14 or the like for detecting the number is input,
Based on these, control signals for the above-described fuel injection amount and injection timing are calculated and output.

A fuel cut valve 10 is interposed in the middle of the suction port 2n. Fuel cut valve 1
0 shuts off fuel supplied from the suction port 2n to the plunger high-pressure chamber 2b when the valve is closed.

The control unit 18 is composed mainly of two microcomputers. During normal operation, the main microcomputer controls the fuel injection amount and fuel injection timing, and the sub-microcomputer controls the fuel cut valve 10. Is controlled. The sub-microcomputer is mainly responsible for the self-diagnosis function, and mutual monitoring is performed so that if one microcomputer goes down, the other microcomputer can detect an abnormality.

The control unit 18 receives a signal from the ignition switch 19, opens the fuel cut valve 10 when the engine is running when the ignition switch 19 is turned on, and sets the ignition switch 1
The fuel cut valve 10 is closed when the operation of the engine 9 is turned off. By closing the fuel cut valve 10 when the operation of the engine is stopped, the supply of fuel from the suction port 2n to the plunger high-pressure chamber 2b is stopped. Pumping of fuel to the engine is stopped, and the operation of the engine is stopped.

However, as will be described later, for example, when the fuel cut valve 10 is closed in a four-cylinder engine, the operation of the engine is immediately stopped, whereas in the six cylinder engine, even if the fuel cut valve 10 is closed,
Engine operation may not stop for a while.

In order to cope with this, the control unit 18 closes the fuel cut valve 10 when the engine operation stop condition for turning off the ignition switch 19 is satisfied, and at the same time, controls the control sleeve 3.
The map for controlling the position of the control sleeve 3 in accordance with the engine operating conditions is switched, and control is performed to gradually move the control sleeve 3 at a predetermined speed toward a predetermined operation stop promotion position while keeping the engine speed low.

In the present embodiment, the operation stop promotion position of the control sleeve 3 is a maximum injection position at which the control sleeve 3 does not communicate the cutoff port 2 e with the pump chamber 7 over the entire stroke of the plunger 2.

With the fuel cut valve 10 blocking the suction port 2n, the control sleeve 3 is gradually moved at a predetermined speed toward the maximum injection position.

Thus, the fuel can be prevented from being confined in the plunger high pressure chamber 2b while the fuel is prevented from flowing backward from the cutoff port 2e to the plunger high pressure chamber 2b, and the operation can be stopped immediately.

FIG. 4 is a block diagram for controlling the operation of the rotary solenoid 4 in the control unit 18.

To explain this, the required fuel injection amount calculating section 31 searches the required fuel injection amount Q according to the engine speed N and the accelerator opening TVO based on the operation map. This driving map characteristic is represented by a solid line in FIG.
At the same accelerator opening TVO, the required fuel injection amount Q decreases as the engine speed N increases, and the accelerator opening T
When the VO becomes relatively large, the required fuel injection amount Q is relatively increased.

The engine stop fuel injection amount calculation unit 32 calculates
The required fuel injection amount Q is searched according to the engine speed N based on the operation stop map. As shown by the broken line in FIG. 3, the operation stop map characteristics, the engine speed N irrespective of the accelerator opening TVO increases beyond N ₁ the required fuel injection quantity Q to 0, the engine speed N is N _{In the} engine speed range lower than _{1, the} required fuel injection amount Q is rapidly increased to the maximum injection amount as the engine speed N decreases.

The map switching means 33 switches the map according to ON / OFF of the ignition switch 19.
That is, when the engine stop condition is satisfied, the operation map characteristic indicated by the solid line in FIG. 3 is switched to the operation stop map characteristic indicated by the broken line.

The drive voltage calculation unit 34 searches the target drive voltage Va of the rotary solenoid 4 according to the engine speed N and the required fuel injection amount Q based on a preset map in order to control the fuel injection amount. A drive voltage V calculated based on the target drive voltage Va is output to the rotary solenoid 4. When the engine is operating, the drive voltage V is changed to the target drive voltage Va.
The control sleeve 3 is stopped by moving the control sleeve 3 as the drive voltage V as it is, while increasing the drive voltage V stepwise at a predetermined change rate toward the target drive voltage Va when the operation stop condition is satisfied. Is gradually moved at a predetermined speed toward the maximum injection position that promotes the above.

When the above-mentioned operation stop condition is satisfied, the speed at which the control sleeve 3 is moved toward the maximum injection position is set lower than the speed at which the plunger 2 reciprocates.
Specifically, the control sleeve 3 is set to 0.02 sec.
The moving speed of the control sleeve 3 is set so as to move the full stroke amount from the minimum injection position to the maximum injection position in the range from to 0.2 sec.

The rate of increase of the drive voltage V per unit time may be changed so as to increase as the control sleeve 3 moves from the minimum injection position toward the maximum injection position.

Next, these control operations executed by the control unit 18 will be described in more detail with reference to the flowcharts of FIGS.

FIG. 5 is a flowchart showing a routine for controlling the opening and closing of the fuel cut valve 10, which is executed by the sub microcomputer of the control unit 18 in synchronization with the engine rotation.

This will be described. First, step 2
At 1, it is determined whether or not the ignition switch 19 is switched from ON to OFF.

When the ignition switch 19 is ON
If it switched to FF, the process proceeds to step 22 counts up the delay timer R _1. Then step 2
Proceed to 3, it determines whether the delay timer R ₁ exceeds a predetermined value T _1. If the delay timer R ₁ is equal to or less than the predetermined value T _1, by repeating the routine of step 21, the delay timer R ₁ counts up the delay timer R ₁ to greater than predetermined value T _1. Thus, it is possible to accurately determine that the ignition switch 19 has been turned from ON to OFF without being affected by an erroneous signal such as an instantaneous ignition switch off signal due to electric noise or the like.

[0081] On the other hand, when the ignition switch 19 is judged to ON in step 21, clearing the delay timer R ₁ proceeds to step 25. Subsequently, the routine proceeds to step 26, where the fuel cut valve 10 is opened, and this routine is terminated. Thereby, fuel is supplied from the intake port 2n to the plunger high-pressure chamber 2b, and the engine is operated.

When the delay timer R ₁ exceeds the predetermined value T ₁ , the routine proceeds to step 24, where the fuel cut valve 1
0 is operated to close the valve, and this routine ends. As a result, the fuel supplied from the suction port 2n to the plunger high-pressure chamber 2b is shut off, and the operation of the engine is stopped.

The flowchart of FIG. 6 shows a routine for switching the map when the engine stop condition is satisfied, and is executed by the main microcomputer of the control unit 18 in synchronization with the engine rotation.

This will be described. First, step 1
It is determined whether the ignition switch 19 changes from ON to OFF.

In step 1, the ignition switch 19
Is determined to be ON, the process proceeds to step 8 to clear the delay timer _R0, and then proceeds to step 9 to switch the map for searching for the required fuel injection amount Q to the operation map.

On the other hand, the ignition switch 19 is turned on.
When the state is switched from OFF to OFF, the process proceeds to step 2, and the delay timer _R0 is counted up. Then, the process proceeds to a step 3, wherein it is determined whether or not the delay timer R ₀ has exceeded a predetermined value T ₀ . If the delay timer R ₀ is equal to or less than the predetermined value T _0, repeating the routine of step 1, 2 and 3, the delay timer R ₀ counts up the delay timer R ₁ to greater than a predetermined value T _0. Thus, it is possible to accurately determine that the ignition switch 19 has been turned from ON to OFF without being affected by an erroneous signal such as an instantaneous ignition switch off signal due to electric noise or the like.

If the delay timer R ₀ has exceeded the predetermined value T ₀ , the routine proceeds to step 4, where it is determined whether or not the engine is running so that the engine speed N does not become zero.

[0088] When the engine speed N is determined that the engine operation which is not 0, the process proceeds to Step 5, it is determined whether the engine rotational speed N is lower than a predetermined value N _2.

[0089] When the engine speed N is lower than a predetermined value N _2, the flow advances to step 6 to determine whether the normal engine speed sensor 14 being monitored by another routine.

If it is determined that the engine speed sensor 14 is normal and all the operation stop conditions in Steps 3 to 6 are satisfied, the process proceeds to Step 7 where the map for retrieving the required fuel injection amount Q is stopped. Switch to map.

Finally, the routine proceeds to step 10, where the required fuel injection amount Q is searched based on the selected operation map, and this routine is terminated.

The flowchart of FIG. 7 shows the routine for calculating the drive voltage V of the rotary solenoid 4 from the required fuel injection amount Q, which is executed every 10 msec in the main microcomputer of the control unit 18. Is done.

First, at step 31, the required fuel injection amount Q
Is read, and the routine proceeds to step 32, where the rotary solenoid 4
Is searched according to the engine speed N and the required fuel injection amount Q based on a preset map.

Then, the process proceeds to a step 33, wherein it is determined whether or not the operation is stopped when the fuel cut valve 10 is closed.

If it is determined that the engine is operating, the routine proceeds to step 39, where the target drive voltage Va is output as it is to the rotary solenoid 4 as the drive voltage V, the control sleeve 3 is moved, and this routine ends. I do.

On the other hand, if it is determined that the operation has been stopped, the routine proceeds to step 34, where it is determined whether the target drive voltage Va is higher than the previous value Vol of the drive voltage V.

Here, if it is determined that the target drive voltage Va is equal to or lower than the previous value Vol of the drive voltage V, the routine proceeds to step 39, where the target drive voltage Va is output as it is to the rotary solenoid 4 as the drive voltage V, and the control is performed. The sleeve 3 is moved, and this routine ends.

On the other hand, if it is determined that the target drive voltage Va is higher than the previous value Vol of the drive voltage V, step 35
Go to, to count up the delay timer R _2.
Then the routine proceeds to step 36 to determine whether the delay timer R ₂ exceeds a predetermined value T _2. If the delay timer R ₂ is equal to or less than the predetermined value T _2, repeat the routine of steps 31 to 36 counts up the delay timer R ₂ until the delay timer R ₂ exceeds a predetermined value T _2. If it is determined that the delay timer R ₂ has exceeded the predetermined value T ₂ , the process proceeds to step 37, where the drive voltage V is set to the previous value Vo.
ld to a value obtained by adding a predetermined value ΔV,
Proceed to 8 to clear put the 0 to the delay timer R _2.

That is, the delay timer R ₂ is an interval at which the control sleeve 3 moves, and the drive voltage V is increased by ΔV every time the delay timer R ₂ elapses after the fuel cut valve 10 is closed. Then, the drive voltage V is increased stepwise at a predetermined change rate toward the target drive voltage Va, and the control sleeve 3 is gradually moved toward the maximum injection position for promoting the stop of operation regardless of the engine speed.

When the operation of the engine is stopped in this way, the voltage guided to the rotary solenoid 4 becomes 0, and the control sleeve 3 is returned from the maximum injection position to the non-injection amount position by the urging force of a spring (not shown). .

[0102] fuel cut valve 10 is not closed operate normally, if the suction port 2n is not blocked, the required fuel engine speed N based on the outage map characteristic shown by the broken line in FIG. 3 rises above N ₁ Set the injection amount to 0,
Since N is increased the amount of required fuel injection with to lower than N _1, eventually the engine speed N remains at a rotational speed range in the vicinity of N _1, the engine rotational speed N does not soar.

The operation is described below.

FIG. 8 shows the output Uαist of the position sensor 5 corresponding to the elapsed time and the stroke position of the control sleeve 3 when the conventional control of holding the control sleeve 3 at the injection position after closing the fuel cut valve 10 is performed. And the manner in which fuel is pumped and sucked in accordance with the stroke of the plunger. This corresponds to the stroke position at which the cut-off port 2e opens during the plunger 2 pumping stroke and the plunger 2
Is the same as the stroke position at which the cut-off port 2e is closed in the suction stroke. In this case, even if the fuel cut valve 10 closes the intake port 2n when the operation of the engine is stopped, a small amount of fuel flows from the pump chamber 7 to the plunger high-pressure chamber 2b through the cutoff port 2e as the plunger 2 reciprocates. A part of the fuel that has flowed back, and thus flowed back, is pressure-fed from the plunger high-pressure chamber 2b to the fuel injection nozzle 11 via the delivery valve 2h, and is injected from the injection hole of the fuel injection nozzle 11 into each cylinder. May not stop there. This phenomenon is likely to occur when the volume of the suction port 2n connecting the fuel cut valve 10 and the plunger high pressure chamber 2b is large, and is caused by a large pressure gradient generated in the plunger high pressure chamber 2b during the compression stroke of the plunger 2. it is conceivable that. In the case of a four-cylinder engine, as shown in FIG.
Are formed so as to communicate with one slit 2j. On the other hand, in the case of a six-cylinder engine, as shown in FIG. As a result, the volume of the suction port 2n and the like serving as a dead volume is large. For this reason, for example, a four-cylinder engine has a fuel cut valve 1
When 0 is closed, the operation of the engine is stopped immediately, whereas in the case of the 6-cylinder engine, even if the fuel cut valve 10 is closed, the operation of the engine may not be stopped for a while.

FIG. 9 shows that the present applicant has filed Japanese Patent Application No. 9-326.
FIG. 9 is a characteristic diagram that has already been proposed as No. 9850 and shows control for moving the control sleeve 3 to the maximum injection position after the fuel cut valve 10 is closed. FIG.
Is the elapsed time on the horizontal axis and the output Uαi of the position sensor 5 on the vertical axis.
st shows that the fuel is pumped and sucked in accordance with the stroke of the plunger. This is because the control sleeve 3 immediately moves to the maximum injection position at the same speed as the plunger 2 after the fuel cut valve 10 closes the suction port 2n when the operation of the engine is stopped. As shown in FIG. 10, the fuel is injected into the cylinder several times until the pressure in the plunger high-pressure chamber 2b falls below the valve opening pressure. Therefore, as shown by a broken line in FIG. 11, a slight rotation fluctuation occurs in the engine, and the time required from the key-off to the stop of the operation becomes longer than in the present invention shown by the solid line.

FIG. 12 is a characteristic diagram showing a control for gradually moving the control sleeve 3 toward the maximum injection position after closing the fuel cut valve 10 of the present invention. FIG. 12 shows the elapsed time on the horizontal axis and the output U of the position sensor 5 on the vertical axis.
αist, which shows how fuel is fed and sucked in accordance with the stroke of the plunger. This is because the control sleeve 3 gradually moves to the maximum injection position at a predetermined speed lower than that of the plunger 2 after the fuel cut valve 10 closes the suction port 2n when the operation of the engine is stopped, so that the fuel is trapped in the plunger high pressure chamber 2b. The amount of fuel flowing backward from the cutoff port 2e to the plunger high-pressure chamber 2b is gradually reduced, and the operation can be stopped immediately.

When the operation stop condition is satisfied, the moving speed of the control sleeve 3 is set such that the control sleeve 3 moves the full stroke amount from the minimum injection position to the maximum injection position within a range from 0.02 sec to 0.2 sec. It has been confirmed by an experiment that the amount of fuel flowing backward from the cutoff port 2e to the plunger high-pressure chamber 2b is reduced without confining the fuel in the plunger high-pressure chamber 2b, thereby promptly stopping the operation.

FIG. 15 is a flowchart showing a routine for diagnosing an abnormality of the fuel cut valve 10.
This is executed in synchronization with the engine rotation in the sub microcomputer of the control unit 18.

To explain this, first, step 1
At 1, it is determined whether or not a valve closing signal for the fuel cut valve 10 has been output.

Here, if it is determined that the valve opening signal of the fuel cut valve 10 has not been output, the routine proceeds to step 19, where a timer value R ₃ described later and an abnormality flag FC
Clear VNG.

[0110] On the other hand, when the closing signal of the fuel cut valve 10 is outputted, the routine proceeds to step 12, the timer value R ₃ is given t the closing signal of the fuel cut valve 10 is counted from the output Determine if ₃ has elapsed.

Until the timer value R ₃ exceeds t ₃ , the routine proceeds to step 13, where the timer value R ₃ is counted up.
Then, the process proceeds to a step 14, wherein it is determined whether or not the engine speed N becomes zero.

When the engine speed N becomes zero before the timer value R ₃ exceeds t ₃ , it is diagnosed that the fuel cut valve 10 is normally closed, and the fuel cut valve 10 is diagnosed. The abnormality flag FCVNG of 10 is cleared, and this routine ends.

On the other hand, if the timer value R ₃ has exceeded t ₃ without the engine speed N becoming 0, the routine proceeds to step 16, where it is assumed that the valve closing operation of the fuel cut valve 10 is abnormal. Diagnose the fuel cut valve 1
An abnormal flag FCVNG of 0 is set.

When the abnormality flag FCVNG is set in this way, the routine proceeds to step 17, where the control sleeve 3 is moved via the rotary solenoid 4 toward the non-injection position. As a result, the cutoff port 2e is opened over the entire stroke of the plunger 2, the fuel injection amount becomes zero, and the operation of the engine is stopped. The operation stop control used here is different from the characteristics of the operation stop map shown by the broken line in FIG. 3 in that the required fuel injection amount Q is forcibly set to 0 irrespective of the accelerator opening TVO and the engine speed N. It is fixed.

Therefore, the fuel cut valve 10
Not only at the time of abnormality, but also at the time of abnormality of the accelerator opening sensor 16 for detecting the accelerator opening TVO and the rotational speed sensor 14 for detecting the engine rotational speed N, if the valve closing signal of the fuel cut valve 10 is output, a predetermined value is obtained. operation of the engine after a lapse of time t ₃ is stopped immediately.

Then, the process proceeds to a step 18, wherein the warning lamp 22 is turned on, and the routine is terminated. Thereby, the driver can be notified of the abnormality of the fuel cut valve 10.

As another embodiment, instead of switching the required fuel injection amount map, as shown in FIG. 16, the map of the output voltage V to the rotary solenoid 4 may be switched when the engine stop condition is satisfied.

More specifically, the required fuel injection amount calculation unit 41 searches the required fuel injection amount Q according to the engine speed N and the accelerator opening TVO based on the operation map.

The drive voltage calculator 42 searches the drive voltage V output to the rotary solenoid 4 according to the engine speed N and the required fuel injection amount Q based on the operation map. The driving map characteristic is that the driving voltage V is relatively increased as the required fuel injection amount Q is increased to increase the fuel injection amount, and the driving voltage V is decreased as the engine speed N is increased. The fuel injection amount is reduced to prevent the engine speed from rising excessively.

The engine stop drive voltage calculator 43 searches the drive voltage V output to the rotary solenoid 4 according to the engine speed N based on the drive stop map. The outage map characteristics, the engine speed N is to minimize the output voltage V exceeds N _1, engine speed N is N ₁
When it is lower, the drive voltage V is increased to the maximum value regardless of the engine speed N.

The map switching means 44 switches the map of the output voltage V in accordance with ON / OFF of the ignition switch 19, and outputs the drive voltage V calculated based on the target drive voltage Va to the rotary solenoid 4. When the engine is operated, the control sleeve 3 is moved with the drive voltage V as the target drive voltage Va as it is as the drive voltage V. On the other hand, when the operation stop condition is satisfied, the drive voltage V is brought close to the target drive voltage Va at a predetermined speed. Is gradually moved toward the maximum injection position that promotes stoppage of operation, so that operation can be stopped immediately.

In this case, too, it can be easily implemented by changing only the logic of the main microcomputer in the control unit 18.

[Brief description of the drawings]

FIG. 1 is a system diagram of a fuel injection device showing an embodiment of the present invention.

FIG. 2 is a characteristic diagram showing a voltage output to a rotary solenoid and an injection state from a fuel injection nozzle.

FIG. 3 is a map in which a fuel injection amount is set.

FIG. 4 is a control block diagram.

FIG. 5 is a flowchart showing control contents.

FIG. 6 is a flowchart showing control contents.

FIG. 7 is a flowchart showing the same control contents.

FIG. 8 is a control characteristic diagram of a comparative example.

FIG. 9 is a control characteristic diagram of a comparative example.

FIG. 10 is a characteristic diagram showing a pressure change of a plunger high-pressure chamber in a comparative example.

FIG. 11 is a characteristic diagram showing a change in engine speed in a comparative example.

FIG. 12 is a control characteristic diagram of the embodiment.

FIG. 13 is a sectional view of a suction port in a comparative example.

FIG. 14 is a sectional view of a suction port according to the embodiment;

FIG. 15 is a flowchart showing control contents.

FIG. 16 is a block diagram illustrating another embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fuel injection pump 2 Plunger 2b Plunger high pressure chamber 2e Cut-off port 2n Suction port 3 Control sleeve 4 Rotary solenoid 5 Position sensor 11 Fuel injection nozzle 14 Revolution speed sensor 16 Accelerator opening sensor 18 Control unit 19 Ignition switch

Claims (11)

[Claims] 1. A means for detecting an accelerator opening, a means for detecting an engine speed, a means for determining a required fuel injection amount from an accelerator opening and an engine speed, and a plunger for forcing injection fuel to the engine. A fuel injection pump comprising: a means for adjusting an injection amount of the fuel injection pump in accordance with the required fuel injection amount; a means for determining when an operation stop condition is satisfied; and A diesel engine control device comprising: means for interrupting the introduction of fuel; and a control device for a diesel engine, comprising: means for gradually moving the adjusting means toward a position promoting the operation stop when an operation stop condition is satisfied. Engine control device. 2. A plunger which reciprocates in rotation in synchronization with engine rotation, a plunger high pressure chamber for pumping fuel sucked from an intake port by a reciprocating motion of the plunger from a distribution port to each cylinder, and a plunger high pressure chamber from the suction port. A fuel cut valve that shuts off the fuel supplied to the plunger, a control sleeve that opens the cut-off port that opens to the outer peripheral surface of the plunger at the end of pumping, and releases the fuel discharged from the plunger high-pressure chamber, and drives the control sleeve. A diesel engine comprising: an actuator; means for determining when an operation stop condition is satisfied; and means for closing a fuel cut valve when the operation stop condition is satisfied to shut off fuel supplied from the suction port to the plunger high-pressure chamber. In the engine control system, Control device for a diesel engine characterized by comprising means for moving progressively toward a position to facilitate the operation stop control sleeve when. 3. A control sleeve position for facilitating operation stoppage when the operation stop condition is satisfied is a maximum injection position at which the control sleeve does not open a cutoff port over the entire stroke of the plunger. 3. The control device for a diesel engine according to item 2. 4. The apparatus according to claim 2, wherein the speed at which the control sleeve is moved toward the position promoting the operation stop when the operation stop condition is satisfied is set lower than the speed at which the plunger reciprocates. Diesel engine control device. 5. The full-stroke amount is moved within a time period from 0.02 seconds to 0.2 seconds when the control sleeve is moved toward a position promoting the operation stop of the engine when the operation stop condition is satisfied. The control device for a diesel engine according to claim 4, wherein the control unit is set as follows. 6. An operation state in which the control sleeve is moved to a position promoting the stop of operation, wherein the control sleeve is moved closer to the minimum injection position as the engine speed rises above a predetermined value. The control device for a diesel engine according to any one of claims 2 to 5, wherein 7. An operation state in which the control sleeve is moved to a position promoting the stop of operation, and it is determined whether or not an abnormality has occurred in the operation of the fuel cut valve by observing the behavior of the engine speed. The control device for a diesel engine according to any one of claims 2 to 6. 8. The diesel engine control device according to claim 7, wherein the abnormality is determined when the engine rotation does not stop within a predetermined time after closing the fuel cut valve. . 9. A control sleeve is moved to a non-injection position where a cut-off port is opened over the entire stroke of the plunger when it is determined that the operation of the fuel cut valve is abnormal. The control device for a diesel engine according to claim 8. 10. An operation map in which a required fuel injection amount is set in accordance with an engine speed and an accelerator opening, and a required fuel injection amount is set to be maximum as the engine speed falls below a predetermined value. The diesel engine according to any one of claims 1 to 9, wherein the required fuel injection amount is calculated by switching from the driving map to the driving stop map when the driving stop condition is satisfied. Engine control device. 11. An operation map in which a drive voltage of an actuator for driving the control sleeve is set according to an engine speed and a required fuel injection amount, and a drive voltage of the actuator is set to a predetermined maximum value when the engine speed is less than a predetermined value. And a driving stop map set to take the following formula: wherein when the driving stop condition is satisfied, the driving map is switched from the driving map to the stop map to control the driving voltage of the actuator. 2. The control device for a diesel engine according to claim 1.