JP3564969B2 - Control unit for diesel engine - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a control device that stops fuel injection when stopping operation of a diesel engine.
[0002]
[Prior art]
In a conventional diesel engine equipped with a distribution type fuel injection pump of an electronic control type, as disclosed in, for example, JP-A-6-272635 and JP-A-8-319855, the fuel injection amount is adjusted. Equipped with a control sleeve that releases fuel discharged from the plunger high-pressure chamber at the end of pressure feeding, an actuator that drives the control sleeve, and a fuel cut valve that shuts off fuel supplied to the plunger high-pressure chamber to stop operation. ing.
[0003]
Usually, the operation of the engine is stopped by shutting off the fuel supplied to the plunger high pressure chamber by the 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 operation is achieved.
[0004]
[Problems to be solved by the invention]
However, in such a conventional diesel engine control device, even when the fuel cut valve normally operates to shut off the fuel supplied to the plunger high-pressure chamber when the operation of the engine is stopped, the engine is stopped. Driving may not stop immediately.
[0005]
As will be described later, this phenomenon tends 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 plunger reciprocation. It is considered that the fuel flows back from the cut-off port opened by the control sleeve to the plunger high-pressure chamber with the movement.
[0006]
The present invention has been made in view of the above problems, and an object of the present invention is to provide a control device for a diesel engine in which operation is stopped immediately.
[0007]
[Means for Solving the Problems]
The control device for a diesel engine according to claim 1,A plunger that rotates and reciprocates in synchronization with engine rotation, a plunger high-pressure chamber that pumps 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 that is supplied from the suction port. A fuel cut valve that shuts off fuel, a control sleeve that opens a cut-off port opened on the outer peripheral surface of the plunger at the end of pumping to allow fuel discharged from the plunger high-pressure chamber, an actuator that drives the control sleeve, and operation shutdown A diesel engine control device comprising: means for determining when the condition is satisfied; and means for closing the fuel cut valve to shut off fuel supplied from the suction port to the plunger high pressure chamber when the operation stop condition is satisfied. , Control when the operation stop condition is satisfied Means for moving the leave to a position promoting the stop of the engine, wherein the control sleeve is provided with a cut-off port over the entire stroke of the plunger as a control sleeve position for promoting the stop of the engine when the stop condition is satisfied. The maximum injection position was set so as not to open.
[0008]
The control device for a diesel engine according to claim 2,In the invention according to claim 1, an operation map in which the required fuel injection amount is set according to the engine speed and the accelerator opening, and the required fuel injection amount is set to a maximum value as the engine speed falls below a predetermined value. And an operation stop map set so that the required fuel injection amount is calculated by switching from the operation map to the operation stop map when the operation stop condition is satisfied.
[0009]
The control device for a diesel engine according to claim 3 is the claim1 orIn the invention described in Item 2,An operation map in which the drive voltage of the actuator that drives the control sleeve is set according to the engine speed and the required fuel injection amount, and the drive voltage of the actuator is set so that the engine speed takes a predetermined maximum value when the engine speed is equal to or less than a predetermined value. And an operation stop map, and when the operation stop condition is satisfied, the operation map is switched to the stop map to control the drive voltage of the actuator.
[0010]
The control device for a diesel engine according to claim 4,A plunger that rotates and reciprocates in synchronization with engine rotation, a plunger high-pressure chamber that pumps 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 that is supplied from the suction port. A fuel cut valve that shuts off fuel, a control sleeve that opens a cut-off port opened on the outer peripheral surface of the plunger at the end of pumping to allow fuel discharged from the plunger high-pressure chamber, an actuator that drives the control sleeve, and operation shutdown A diesel engine control device comprising: means for determining when the condition is satisfied; and means for closing the fuel cut valve to shut off fuel supplied from the suction port to the plunger high pressure chamber when the operation stop condition is satisfied. , Control when the operation stop condition is satisfied Means for moving the leave to a position promoting the stop of the engine, wherein the control sleeve is cut off over most of the stroke of the plunger as a control sleeve position for promoting the stop of the engine when the stop condition is satisfied. The large injection position was set to reduce the flow of fuel flowing backward from the cutoff port to the plunger high-pressure chamber without opening the port.
According to a fifth aspect of the present invention, there is provided a diesel engine control device according to any one of the first to fourth aspects, wherein the engine speed is increased in an operating state in which the control sleeve is moved to a position promoting the stop of the operation of the engine. The control sleeve is moved closer to the minimum injection position as the pressure rises above a predetermined value.
[0011]
Claim6Diesel engine control device according to claim1From5In the invention according to any one of the above, in the operating state of moving the control sleeve to a position that promotes the stop of the operation of the engine, the behavior of the engine speed is checked by looking at the behavior of the engine speed to determine whether an abnormality has occurred in the operation of the fuel cut valve. It was configured to be determined.
[0012]
Claim7Diesel engine control device according to claim6In the invention described in (1), the abnormality is determined when the engine rotation is not stopped during a period from when the fuel cut valve is closed to when a predetermined time elapses.
[0013]
Claim8Diesel engine control device according to claim7In the invention described in (1), when it is determined that the operation of the fuel cut valve is abnormal, the control sleeve is moved to the non-injection position where the cutoff port is opened over the entire stroke of the plunger.
[0016]
Function and Effect of the Invention
The control device for a diesel engine according to claim 1,In the engine including the distribution type fuel injection pump, the fuel supplied from the suction port to the plunger high-pressure chamber is shut off by closing the fuel cut valve when the operation stop condition is satisfied. Then, by moving the control sleeve to a position that promotes engine shutdown, fuel moves from the cutoff port to the plunger high-pressure chamber.The backflow is suppressed, and the operation of the engine is stopped promptly.
[0017]
As a result, the suction portEven in the case of a six-cylinder engine or the like having a large volume, the operation of the engine is stopped quickly, so that the driver does not feel uncomfortable.
[0018]
Further, when the operation stop condition is satisfied, the control sleeve moves to the maximum injection position that closes the cutoff port over the entire stroke of the plunger, whereby the flow of fuel flowing backward from the cutoff port to the plunger high-pressure chamber is cut off. The operation of the engine is stopped immediately.
[0019]
The control device for a diesel engine according to claim 2.In, 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 fuel injection amount is controlled according to the operating state.
If 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 a preset map, and the control sleeve is stopped. To the maximum injection position that promotes operation stop. As a result, the operation of the engine is stopped immediately.
If the fuel cut valve does not close normally and the suction port is not shut off, the required fuel injection amount is reduced as the engine speed increases based on the operation stop map characteristics, so the control sleeve is placed in the non-injection position. Move to the side. As a result, the engine speed can be maintained at a certain value or less, so that the driver does not feel uncomfortable.
[0020]
4. The control device for a diesel engine according to claim 3, wherein the drive 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 operation of the engine, and the fuel is determined according to the operation state. The injection amount is controlled.
When the fuel cut valve operates normally and the suction port is shut off, the drive voltage of the actuator is increased as the engine speed is reduced based on a preset map when the operation stop condition is satisfied, and the control sleeve is increased. Is moved to the maximum injection position to promote the stop of the operation, and the engine is stopped immediately.
When the fuel cut valve does not close normally 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 characteristics, and the control sleeve is moved to the non-injection position side. Go to As a result, the engine speed can be maintained at a certain value or less, so that the driver does not feel uncomfortable.
[0021]
Claim4In the diesel engine control device described in the above,
When the operation stop condition is satisfied, the control sleeveMostCutoff port over strokeWithout opening, reduce the flow of fuel flowing backward from the cutoff port to the plunger high pressure chamberBy moving to the large injection position, the flow of fuel flowing backward from the cutoff port to the plunger high pressure chamber is reduced.DecreaseThe operation of the engine is stopped immediately.
[0022]
Claim5If the fuel cut valve normally closes and the suction port is shut off when the operation stop condition is satisfied, the maximum injection of the control sleeve is performed as the engine speed decreases. Move to the position side. As a result, the operation of the engine is stopped immediately.
[0023]
If 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, so that the driver does not feel uncomfortable.
[0024]
Claim6In the diesel engine control device described in the above, after closing the fuel cut valve in the operating state of moving the control sleeve to a position that promotes the stop of the operation of the engine, if the engine speed quickly decreases to 0, While it can be determined that the fuel cut valve is operating normally, if the engine speed does not rapidly decrease, it can be determined that the operation of the fuel cut valve is abnormal.
[0025]
By diagnosing the fuel cut valve by moving the control sleeve to a position that facilitates stopping the operation of the engine, it is possible to prevent the diagnostic accuracy from being deteriorated due to the backflow of fuel from the cutoff port and the like.
[0026]
Claim7In the control device for a diesel engine described in the above, when the engine rotation does not stop within a predetermined time after closing the fuel cut valve, it is determined that the operation of the fuel cut valve is abnormal.
[0027]
Claim8Wherein the control sleeve is moved to the non-injection position to open the cut-off port over the entire stroke of the plunger when it is determined that the operation of the fuel cut valve is abnormal. As a result, 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.
[0034]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
[0035]
First, FIG. 1 shows a fuel injection system for a diesel engine.
[0036]
In FIG. 1, a feed pump 6 for pre-pressurizing fuel is mounted on an input shaft 6a of a fuel injection pump 1 which is driven to rotate in synchronization with the rotation of a diesel engine. Further, the feed pump 6 rotates coaxially with the input shaft 6a. At the same time, a plunger 2 connected to reciprocate in the axial direction is arranged.
[0037]
The feed pump 6 sends out the pressurized fuel to the pump chamber 7, and the excess fuel is returned to a fuel tank (not shown) to keep the pressure in the pump chamber 7 constant.
[0038]
A face cam 2a having cam lobes corresponding to the number of cylinders is coaxially provided on the plunger 2, and the plunger 2 reciprocates in the axial direction each time the face cam 2a rides on the roller 8a. 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, the fuel is sucked into the plunger high-pressure chamber 2b and pressurized. A return spring 2k pushes back the plunger 2 against the face cam 2a.
[0039]
In the extension stroke of the plunger 2, fuel from the pump chamber 7 is sucked into the plunger high-pressure chamber 2b via the suction port 2n and the slit 2j provided in the plunger 2.
[0040]
On the other hand, a communication passage communicating with the plunger high-pressure chamber 2b along the axis of the plunger 2 to pressurize the pressurized fuel in the plunger high-pressure chamber 2b to the fuel injection nozzle 11 of each cylinder during the compression stroke of the plunger 2. 2c is formed, and a high-pressure passage 2d branches radially from the middle of the communication passage 2c. Further, a cut-off port 2e penetrating through the plunger 2 in the radial direction branches off from the distal end of the communication passage 2c.
[0041]
Ports 2g of a number corresponding to the number of cylinders of the diesel engine are uniformly arranged 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. A delivery valve 2h (only one is shown) is connected to each port 2g, and fuel is fed from the delivery valve 2h to the fuel injection nozzle 11.
[0042]
The plunger 2 reciprocates six times each time it rotates, and pressurizes the inhaled fuel each time. The pressurized fuel is pushed into the high-pressure passage 2d from the communication passage 2c, and at this time, the port 2g communicates depending on the rotation position of the plunger 2. Is fed to the fuel injection nozzle 11 through the corresponding delivery valve 2h.
[0043]
On the other hand, a control sleeve 3 is slidably fitted on the outer periphery of the plunger 2 and normally covers and closes the cutoff port 2e. However, due to the movement of the plunger 2 in the compression direction, the cutoff port 2 Release 2e. As a result, the pressure in the plunger high-pressure chamber 2b is released, and the pressure feed of the fuel from the delivery valve 2h to the fuel injection nozzle 11 ends.
[0044]
The fuel injection nozzle 11 lifts the needle (not shown) by the fuel being fed from the delivery valve 2h to open the injection port, and directly injects the fuel from the injection port to each cylinder.
[0045]
Therefore, the amount of fuel sent to the fuel injection nozzle 11 changes 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 is small, and If the opening time of the cutoff port 2e is delayed, the fuel injection amount increases.
[0046]
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.
[0047]
FIG. 2 is a characteristic diagram showing a voltage output to the rotary solenoid 4 and an injection state from the fuel injection nozzle 11. When the voltage output to the rotary solenoid 4 is V₁To V₂The fuel injection amount control during normal operation is performed in the range of. When the voltage output to the rotary solenoid 4 is V₁In the smaller no-injection region, the control sleeve 3 opens the cutoff port 2e over the entire stroke of the plunger 2, and the fuel injection amount becomes zero. When the voltage output to the rotary solenoid 4 is V₂In the larger maximum injection range, the control sleeve 3 closes the cutoff port 2e over the entire stroke of the plunger 2, and the fuel injection amount becomes maximum.
[0048]
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. 6, and instructs the rotary solenoid 4 to obtain the required fuel injection amount Q. Control the driving voltage sent.
[0049]
Next, the position of the roller 8a on which the face cam 2a rides is controlled by the timer piston 8 in the circumferential direction of the face cam 2a. 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.
[0050]
When the position of the timer piston 8 changes and the position of the roller 8a advances in the direction of rotation of the face cam 2a, the position at which the face cam 2a rides on the roller 8a is relatively delayed, and the time when the pressurization of the fuel by the plunger 2 starts, that is, If the fuel injection timing is delayed, and conversely, if the position of the roller 8a is delayed in the direction opposite to the rotation of the face cam 2a, the pressure start timing by the plunger 2 is advanced, and the fuel injection timing is advanced.
[0051]
The signal from the control unit 18 controls the operation of the control valve 9 in accordance with the operation state, adjusts the position of the timer piston 8, and controls the advance and retard of the fuel injection timing.
[0052]
The control unit 18 includes a nozzle lift sensor 12 for detecting a valve opening timing of the fuel injection nozzle 11, a fuel temperature sensor 15 for detecting a temperature of the fuel supplied to the fuel injection pump 1, and a cooling system for detecting a diesel engine cooling water temperature. Signals from a water temperature sensor 13, an accelerator opening sensor 16 for detecting an accelerator opening, an engine speed sensor 14 for detecting a pump speed, and the like are input, and based on these, the above-described fuel injection amount and injection timing are obtained. Is calculated and output.
[0053]
A fuel cut valve 10 is interposed in the middle of the suction port 2n. The fuel cut valve 10 shuts off fuel supplied from the suction port 2n to the plunger high pressure chamber 2b when the fuel cut valve 10 is closed.
[0054]
The control unit 18 is mainly composed of two microcomputers. During normal operation, the main microcomputer controls the fuel injection amount and fuel injection timing, and the sub-microcomputer opens and closes the fuel cut valve 10. Controlled. The sub-microcomputer is mainly responsible for the self-diagnosis function, and mutual monitoring is performed so that even if one microcomputer goes down, the other microcomputer can detect an abnormality.
[0055]
The control unit 18 receives a signal from an ignition switch 19, opens the fuel cut valve 10 when the engine is running when the ignition switch 19 is turned on, and closes the fuel cut valve 10 when the engine is stopped when the ignition switch 19 is turned off. Let it go. By closing the fuel cut valve 10 when the operation of the engine is stopped, the supply of the 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.
[0056]
However, for example, in the case of a four-cylinder engine, when the fuel cut valve 10 is closed, the operation of the engine is immediately stopped, whereas in the case of the six cylinder engine, even if the fuel cut valve 10 is closed, the operation of the engine does not stop for a while. there is a possibility. That is, even if the fuel cut valve 10 closes the suction port 2n when the operation of the engine is stopped, the fuel in the pump chamber 7 flows back from the cutoff port 2e to the plunger high pressure chamber 2b as the plunger 2 reciprocates, and the plunger pressure increases. Fuel may be pressure-fed from the chamber 2b to the fuel injection nozzle 11 via the delivery valve 2h, and injected into each cylinder from the injection port of the fuel injection nozzle 11, so that the operation of the engine may not stop for a while. This phenomenon tends to occur when the volume of the suction port 2n or the like 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. 3, the intake port 2n is formed so as to communicate with one slit 2j. On the other hand, in the case of the 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.
[0057]
In order to cope with this, the control unit 18 closes the fuel cut valve 10 and controls the position of the control sleeve 3 according to the engine operating conditions when the engine operation stop condition in which the ignition switch 19 is turned off is satisfied. The control is performed to switch the map and move the control sleeve 3 to a predetermined operation stop accelerating position while keeping the engine speed low.
[0058]
In the present embodiment, the operation stop accelerating position of the control sleeve 3 is a maximum injection position at which the control sleeve 3 does not allow the cutoff port 2 e to communicate with the pump chamber 7 over the entire stroke of the plunger 2. By moving the control sleeve 3 to the maximum injection position with the fuel cut valve 10 blocking the suction port 2n, the flow of fuel flowing backward from the cutoff port 2e to the plunger high-pressure chamber 2b is blocked, and the operation of the engine is started. Shutdown occurs promptly.
[0059]
In a state where the fuel cut valve 10 shuts off the suction port 2n, even if the control sleeve 3 is moved to the large injection position where the cutoff port 2e is not communicated with the pump chamber 7 in most of the stroke of the plunger 2, the cutoff can be performed. The flow of fuel flowing backward from the port 2e to the plunger high-pressure chamber 2b is reduced, and the operation of the engine is quickly stopped.
[0060]
FIG. 5 shows a block diagram for controlling the operation of the rotary solenoid 4 in the control unit 18.
[0061]
Describing this, the required fuel injection amount calculation unit 31 searches the required fuel injection amount Q according to the engine speed N and the accelerator opening TVO based on the operation map. As shown by the solid line in FIG. 6, this operation map characteristic shows that as the engine speed N increases at the same accelerator opening TVO, the required fuel injection amount Q decreases and the accelerator opening TVO increases relative to the required fuel injection amount. The injection amount Q is relatively increased.
[0062]
The engine stop fuel injection amount calculation unit 32 searches for the required fuel injection amount Q according to the engine speed N based on the operation stop map. As shown by the broken line in FIG. 6, this operation stop map characteristic indicates that the engine speed N is N regardless of the accelerator opening TVO.₁When the engine speed exceeds N, the required fuel injection amount Q is set to 0, and the engine speed N becomes N₁In a lower engine speed range, the required fuel injection amount Q is rapidly increased to the maximum injection amount as the engine speed N decreases.
[0063]
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. 6 is switched to the operation stop map characteristic indicated by the broken line.
[0064]
The drive voltage calculation unit 34 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 a preset operation stop map in order to control the fuel injection amount. .
[0065]
As a result, the required fuel injection amount Q during the operation of the engine is calculated based on the engine speed N and the accelerator opening TVO based on the operation map, and the control sleeve 3 is moved according to the operating state to control the fuel injection amount. You.
[0066]
When the fuel cut valve 10 operates normally and the intake port is shut off when the operation stop condition is satisfied, the required fuel injection amount Q is increased with a decrease in the engine speed N based on a preset map. Then, the control sleeve 3 is moved to the maximum injection position for promoting the stop of operation. As a result, the operation of the engine is stopped immediately.
[0067]
When the fuel cut valve 10 does not normally close and the intake port 2n is not shut off, the engine speed N becomes N based on the operation stop map characteristic.₁The required fuel injection amount Q is reduced to 0 with the rise above the control sleeve, and the control sleeve moves to the non-injection position side. As a result, the engine speed N can be maintained at a certain value or less, and the driver does not feel uncomfortable.
[0068]
Next, these control operations executed by the control unit 18 will be described in more detail with reference to the flowcharts of FIGS.
[0069]
The flowchart of FIG. 7 shows a routine for controlling the opening and closing of the fuel cut valve 10, and is executed by the sub microcomputer of the control unit 18 in synchronization with the engine rotation.
[0070]
To explain this, first, at step 21, it is determined whether or not the ignition switch 19 is switched from ON to OFF.
[0071]
If the ignition switch 19 has been switched from ON to OFF, the routine proceeds to step 22, where the delay timer R₁Count up. Then, the process proceeds to a step 23, wherein the delay timer R₁Is a predetermined value T₁Is determined. Delay timer R₁Is a predetermined value T₁In the following cases, the routine of steps 21, 22, 23 is repeated to₁Is a predetermined value T₁Delay timer R until₁Count up. Thereby, 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.
[0072]
On the other hand, if it is determined in step 1 that the ignition switch 19 is ON, the process proceeds to step 25, where the delay timer R₁Clear Then, the process proceeds to a step 26, wherein the fuel cut valve 10 is opened, and this routine ends. Thereby, fuel is supplied from the intake port 2n to the plunger high-pressure chamber 2b, and the operation of the engine is performed.
[0073]
Delay timer R₁Is a predetermined value T₁If it exceeds, the routine proceeds to step 24, where the fuel cut valve 10 is closed, and this routine ends. Thereby, 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.
[0074]
The flowchart of FIG. 8 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.
[0075]
To explain this, first, at step 1, it is determined whether or not the ignition switch 19 is changed from ON to OFF.
[0076]
If the ignition switch 19 has been switched from ON to OFF, the process proceeds to step 2 where the delay timer R₀Count up. Then, the process proceeds to step 3, where the delay timer R₀Is a predetermined value T₀Is determined. Delay timer R₀Is a predetermined value T₀In the following case, the routine of steps 1, 2, and 3 is repeated to₀Is a predetermined value T₀Delay timer R until₁Count up. Thereby, 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.
[0077]
On the other hand, if it is determined in step 1 that the ignition switch 19 is ON, the process proceeds to step 8 where the delay timer R₀Clear
[0078]
Delay timer R₀Is a predetermined value T₀If the engine speed exceeds N, the routine proceeds to step 4, where it is determined whether or not the engine is running, in which the engine speed N does not become zero.
[0079]
If it is determined that the engine is not operating, the engine speed N does not become 0, the routine proceeds to step 5, where the engine speed N becomes the predetermined value N₂Determine if it is lower.
[0080]
The engine speed N is a predetermined value N₂If it is lower, the routine proceeds to step 6, where it is determined whether the engine speed sensor 14 monitored by another routine is normal.
[0081]
Here, when the engine speed sensor 14 is determined to be normal and all the operation stop conditions of Steps 3 to 6 are satisfied, the process proceeds to Step 7 and the map for searching for the required fuel injection amount is switched to the operation stop map. Then, the process ends.
[0082]
If the fuel cut valve 10 normally closes when the operation stop condition is satisfied, the engine speed N becomes N based on the operation stop map characteristic.₁Since the control sleeve 3 is moved to the predetermined maximum injection position as the engine speed drops below the lower predetermined rotational speed, the flow of fuel flowing backward from the cutoff port 2e to the plunger high-pressure chamber 2b is cut off, and the engine is stopped. Is immediately stopped.
[0083]
When the operation of the engine is stopped, the voltage guided to the rotary solenoid 4 becomes 0, so that 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).
[0084]
When the fuel cut valve 10 does not normally close and the intake port 2n is not shut off, the engine speed N becomes N based on the operation stop map characteristic.₁After that, the fuel injection amount is controlled to be 0 or maximum, so that N₁The engine speed N does not hunt in the vicinity of the engine speed range, and the engine speed N does not rise rapidly.
[0085]
On the other hand, if the operation stop condition is not satisfied, the routine proceeds to step 9, where the map for searching for the required fuel injection amount is switched to the operation map, and this routine ends. Thereby, the operation of the engine is continued.
[0086]
The flowchart of FIG. 9 shows a routine for diagnosing an abnormality of the fuel cut valve 10, and is executed by the sub microcomputer of the control unit 18 in synchronization with the engine rotation.
[0087]
To explain this, first, at step 11, it is determined whether or not the fuel cut valve 10 has been closed.
[0088]
Here, if it is determined that the fuel cut valve 10 is open, the routine proceeds to step 19, where a timer value R to be described later is set.₂, Clears the abnormality flag FCVNG.
[0089]
On the other hand, when the fuel cut valve 10 is closed, the process proceeds to step 12, where the timer value R counted after the fuel cut valve 10 is closed is counted.₂Is a given t₁Is determined.
[0090]
Timer value R₂Is t₁To step 13 until the timer value R₂Count up. Then, the process proceeds to a step 14, wherein it is determined whether or not the engine speed N becomes zero.
[0091]
Timer value R₂Is t₁If the engine speed N becomes 0 before the engine speed exceeds 0, it is diagnosed that the fuel cut valve 10 is normally closed, and the abnormality flag FCVNG of the fuel cut valve 10 is cleared. End the routine.
[0092]
On the other hand, while the engine speed N does not become 0, the timer value R₂Is t₁If the value exceeds the limit, the routine proceeds to step 16, where it is diagnosed that the valve closing operation of the fuel cut valve 10 is abnormal, and the abnormality flag FCVNG of the fuel cut valve 10 is set.
[0093]
When the abnormality flag FCVNG is thus set, the routine proceeds to step 17, where the control sleeve 3 is moved to the non-injection position via the rotary solenoid 4. 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.
[0094]
Then, the process proceeds to a step 18, wherein the warning lamp 22 is turned on, and the present routine ends. Thereby, the driver can be notified of the abnormality of the fuel cut valve 10.
[0095]
Instead of switching the required fuel injection amount map as shown in FIGS. 5 and 6, as another embodiment, as shown in FIG. 10, when the operation stop condition of the engine is satisfied, the map of the output voltage V to the rotary solenoid 4 is switched. You may.
[0096]
Describing this, the required fuel injection amount calculating 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.
[0097]
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 characteristics are as follows. As the required fuel injection amount Q increases, the driving voltage V is relatively increased to increase the fuel injection amount, and as the engine speed N increases, the driving voltage V decreases. The fuel injection amount is reduced to prevent the engine speed from rising excessively.
[0098]
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 operation stop map. This stop map characteristic indicates that the engine speed N is N₁Is exceeded, the output voltage V is minimized, and the engine speed N becomes N₁When it is lower, the drive voltage V is increased to the maximum value regardless of the engine speed N, so that the fuel injection amount is maximized.
[0099]
The map switching means 44 switches the map of the output voltage V according to ON / OFF of the ignition switch 19. That is, when the engine operation stop condition is satisfied, the operation map characteristic is switched from the preset operation map characteristic to the operation stop map characteristic.
[0100]
By switching the map of the output voltage V to the rotary solenoid 4 when the operation stop condition is satisfied in this manner, the engine speed N becomes N₁Since the control sleeve 3 is moved to the predetermined maximum injection position as the engine speed drops below the lower predetermined rotational speed, the flow of fuel flowing backward from the cutoff port 2e to the plunger high-pressure chamber 2b is cut off, and the engine is stopped. Is immediately stopped.
[0101]
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 sectional view of a suction port showing a comparative example.
FIG. 4 is a cross-sectional view of the suction port showing the same embodiment.
FIG. 5 is a control block diagram.
FIG. 6 is a map in which a fuel injection amount is set.
FIG. 7 is a flowchart showing control contents.
FIG. 8 is a flowchart showing control contents.
FIG. 9 is a flowchart showing control contents.
FIG. 10 is a block diagram showing another embodiment.
[Explanation 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
11 Fuel injection nozzle
14 Speed sensor
16 Accelerator opening sensor
18 Control unit
19 Ignition switch

Claims (8)

A plunger that rotates and reciprocates 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;
A fuel cut valve that shuts off fuel supplied from the suction port to the plunger high-pressure chamber;
A control sleeve for opening a cut-off port opened on the outer peripheral surface of the plunger at the end of the pressure feed to release fuel discharged from the plunger high-pressure chamber,
An actuator for driving the control sleeve,
Means for determining when the operation stop condition is satisfied;
Means for closing the fuel cut valve when the operation stop condition is satisfied and shutting off fuel supplied from the suction port to the plunger high pressure chamber;
In a diesel engine control device comprising:
Means for moving the control sleeve to a position that facilitates stopping the operation of the engine when the stop condition is satisfied,
As the control sleeve position for promoting the stop of the engine when the stop condition is satisfied, the maximum injection position where the control sleeve does not open the cut-off port over the entire stroke of the plunger,
A control device for a diesel engine, comprising: An operation map in which the required fuel injection amount is set according to the engine speed and the accelerator opening,
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,
With
Calculating the required fuel injection amount by switching from the operation map to the operation stop map when the operation stop condition is satisfied,
The control device for a diesel engine according to claim 1, wherein: An operation map in which the drive voltage of the actuator that drives the control sleeve is set according to the engine speed and the required fuel injection amount,
An operation stop map in which the drive voltage of the actuator is set such that the engine speed takes a predetermined maximum value when the engine speed is equal to or lower than a predetermined value,
With
When the operation stop condition is satisfied, the operation map is switched to the stop map to control the drive voltage of the actuator.
The control device for a diesel engine according to claim 1 or 2, wherein: A plunger that rotates and reciprocates 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;
A fuel cut valve that shuts off fuel supplied from the suction port to the plunger high-pressure chamber;
A control sleeve for opening a cut-off port opened on the outer peripheral surface of the plunger at the end of the pressure feed to release fuel discharged from the plunger high-pressure chamber,
An actuator for driving the control sleeve,
Means for determining when the operation stop condition is satisfied;
Means for closing the fuel cut valve when the operation stop condition is satisfied and shutting off fuel supplied from the suction port to the plunger high pressure chamber;
In a diesel engine control device comprising:
Means for moving the control sleeve to a position that facilitates stopping the operation of the engine when the stop condition is satisfied,
As the control sleeve position that promotes engine stoppage when the operation stop condition is satisfied, the control sleeve does not open the cutoff port over most of the stroke of the plunger, and flows backward from the cutoff port to the plunger high pressure chamber. Large injection position to reduce the flow of fuel
A control device for a diesel engine, comprising: In an operating state in which the control sleeve is moved to a position promoting the stop of the operation of the engine, the control sleeve is moved closer to the minimum injection position as the engine speed increases beyond a predetermined value,
The control device for a diesel engine according to any one of claims 1 to 4, wherein: In the operating state of moving the control sleeve to a position that promotes the stop of the operation of the engine, the behavior of the engine speed is checked to determine whether or not an abnormality has occurred in the operation of the fuel cut valve,
The control device for a diesel engine according to any one of claims 1 to 5 , characterized in that: The determination of the abnormality is determined to be abnormal when the engine rotation does not stop within a predetermined time after closing the fuel cut valve,
The control device for a diesel engine according to claim 6, wherein: The control sleeve is moved to a non-injection position in which 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. 8. The control device for a diesel engine according to 7 .

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