JPS6321022B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for a diesel engine, and particularly to a safety function when a fuel cutoff valve malfunctions.

In a diesel engine, normally, after starting operation, the engine will not stop unless the fuel supply is stopped.

Therefore, as shown in FIG. 3, an electromagnetic fuel cutoff valve 103 is provided in the fuel supply system (for example, in the injection pump), and the driver can cut off the connection to the battery 101 by turning off the key switch 102. However, the engine is configured to be stopped by closing the fuel cutoff valve.

Therefore, if the fuel cutoff valve malfunctions and the engine remains open even when the key switch is turned off, the engine cannot be stopped and the engine will run out of control.

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 that can reliably stop the engine even when a fuel cutoff valve fails.

In order to achieve the above object, in the present invention,
If the engine continues to operate even after the key switch is turned off, it is determined that there is an abnormality, and an engine stop means other than the fuel cutoff valve is activated to stop the engine.

The present invention will be explained in detail below based on the drawings.

FIG. 1 is an example diagram of a diesel engine control device to which the present invention is applied.

In Fig. 1, 1 is an air cleaner, 2 is an intake pipe, 3 is a main combustion chamber, 4 is a swirl chamber, 5 is a glow plug, 6 is an injection nozzle, 7 is an injection pump (details will be described later), 8 is an exhaust pipe, 9 is a throttle valve that adjusts the amount of intake air,
10 is a diaphragm valve that controls the throttle valve opening;
1 is an EGR valve that controls the amount of EGR recirculated from the exhaust pipe 8 to the intake pipe 2 (exhaust gas recirculation amount); 12 and 13;
is a solenoid valve. Further, 14 is a vacuum pump serving as a negative pressure source, and can be used in common with, for example, a brake servo pump. Further, 15 is a constant pressure valve that creates a constant negative pressure from the negative pressure given from the vacuum pump 14, 16 is a battery, 17 is a glow relay that controls energization to the glow plug 5, and 18 is a control unit that controls the fuel injection amount of the injection pump 7. A servo circuit 19 is a glow lamp that indicates the energization state of the glow plug 5. 20 is an accelerator position signal IS ₁ corresponding to the accelerator pedal position (depression angle)
The accelerator position sensor 21 outputs a reference pulse at every reference angle of crank angle (for example, 120°).
IS ₂ , unit pulse per unit angle (e.g. 1°)
A crank angle sensor that outputs IS ₃ , 22 a neutral switch that detects that the transmission is in the neutral position and outputs a neutral signal IS ₄ , and 23 a vehicle speed signal IS ₅ corresponding to the vehicle speed (transmission 24 is a temperature sensor that outputs a temperature signal IS ₆ corresponding to the engine cooling water temperature; 25 is an injection start signal every time the injection nozzle 6 starts fuel injection. A lift sensor outputting IS ₇ , for example a switch or a piezoelectric element actuated by fuel pressure. Further, 26 is an atmospheric density sensor that outputs an atmospheric density signal _IS8 corresponding to the temperature and pressure of the atmosphere. In addition, a sleeve position signal corresponding to the position of the sleeve that controls the fuel injection amount of the injection pump 7
Signals such as IS ₉ (details will be described later) and battery voltage signal IS ₁₀ are used.

Further, 27 is an arithmetic unit, such as a central processing unit (CPU) 28 and a read-only memory (ROM).
29. Readable and writable memory (RAM) 3
0, an input/output interface 31, and the like.

The computing device 27 receives signals IS ₁ to IS ₁₀ provided from the various sensors described above, a starter signal IS ₁₁ provided from a starter switch (not shown) (turned on when the starter motor is activated), a glow signal IS ₁₂ provided from a glow switch, etc. It inputs signals and outputs various control signals OS ₁ to _{OS 7} for optimally controlling the diesel engine.

First, throttle valve opening control signal OS ₁ and EGR control signal
OS ₂ is a pulse signal, and by changing the duty of these pulse signals and controlling the duty of the solenoid valves 12 and 13, the opening degree of the throttle valve 9 and
The opening degree of the EGR valve 11 is controlled.

Further, the fuel cutoff control signal OS ₃ controls opening and closing of a fuel cutoff valve 71 (for stopping the engine) in the injection pump 7.

Further, the fuel injection amount control signal OS ₄ and the sleeve position signal IS ₉ are given to the servo circuit 18, and the servo circuit 18 outputs the servo signal S ₁ so as to match both signals _. Therefore, by controlling the sleeve position, the fuel injection amount is controlled.

Furthermore, by controlling the injection timing control mechanism in the injection pump 7 using the injection timing control signal OS ₅ ,
Controls fuel injection timing. Note that the injection timing is feedback-controlled using the injection start signal _IS7 from the lift sensor 25.

Furthermore, by controlling the glow relay 17 using the glow control signal OS ₆ , the energization of the glow plug 5 is controlled.

Further, the energization state of the glow plug 5 is displayed by controlling the flashing of the glow lamp 19 using the glow lamp control signal _OS7 . For example, the glow lamp 19 is turned on when energized, and turned off when not energized.

Next, FIG. 2 is a sectional view of an example of the injection pump 7. As shown in FIG.

In FIG. 2, fuel is first sucked from an inlet 32 of the pump body by a feed pump 34 driven by a drive shaft 33 connected to an engine output shaft.

The supply pressure of the fuel discharged from the feed pump 34 is controlled by a pressure regulating valve 35, and the fuel is supplied to a pump chamber 36 inside the pump housing.

The fuel in the pump chamber 36 lubricates the working parts and is simultaneously sent to the high pressure plunger pump 38 through the suction port 37.

A plunger 39 of this pump 38 is fixed to an eccentric disk 40 connected to a drive shaft 33, and is driven by the drive shaft 33 via a joint 41 in synchronization with the rotation of the engine.

The eccentric disk 40 has the same number of face cams 42 as the number of engine cylinders, and each time the face cams 42 pass over a roller 44 disposed on a roller ring 43 while rotating, the eccentric disk 40 reciprocates by a predetermined cam lift.

Therefore, the plunger 39 reciprocates while rotating, and due to this reciprocating movement, the fuel sucked from the suction port 37 is forced into the injection nozzle 6 of FIG. 1 through the distribution port 45 and the delivery valve 46. be done.

At that time, the fuel injection timing is determined by the roller ring 43.
can be freely adjusted by changing the relative position between the face cam 42 and the roller 44.

The roller ring 43 is connected to a plunger 48 via a driving pin 47.

In FIG. 2, for convenience of explanation, the axis of the plunger 48 is rotated by 90 degrees, and the axis of the feed pump 34 is also rotated by 90 degrees.

A cylinder 49 containing the plunger 48 is slidably housed inside the casing 50.
An oil chamber 51 is defined at the right end of the cylinder 49, and an oil chamber 52 is defined at the left end. Note that passages 49a and 50a are provided for communicating between the oil chamber 51 and the end face high pressure chamber 55 when the cylinder 49 moves to the right.

The oil chamber 51 communicates with the other oil chamber 52 and the suction side of the feed pump 34 through a fuel passage 53, and a solenoid valve 54 is provided at the connection between the oil chamber 51 and the fuel passage 53. .

Further, the fuel pressure in the pump chamber 36 is introduced to the end face high pressure chamber 55 of the plunger 48 sliding in the cylinder 49 through a passage 56, and the low pressure chamber 57 on the opposite side is communicated with the suction side of the feed pump 34. However, the elastic force of the spring 58 pushes back the plunger 48.

The fuel pressure in the pump chamber 36 is
4, so when the passage 49a is closed as shown in the figure, the plunger 48 is pushed to the left in the figure as the engine rotation speed increases, thereby causing the eccentric Since the roller ring 43 is rotated in the opposite direction to the rotational direction of the disk 40, the injection timing becomes earlier in accordance with the rotational speed.

Furthermore, when the cylinder 49 moves fully to the right in the drawing due to the rotational force of the eccentric disk 40 (at this time, the solenoid valve 54 is open), the passages 49a and 5
Since the oil chamber 51 and the end high pressure chamber 55 communicate with each other through the oil chamber 51 and the end high pressure chamber 55, the pressure in the end high pressure chamber 55 can be controlled by opening and closing the solenoid valve 54. Therefore, by duty-controlling the opening and closing of the solenoid valve 54 using the injection timing control signal _OS5 , the injection timing can be electrically controlled.

On the other hand, the amount of fuel to be injected is determined by the position of the sleeve 60 that covers the spill port 59 formed in the plunger 39. For example, when the opening of the spill port 59 passes over the right end of the sleeve 60 due to the rightward movement of the plunger 39, the fuel that had been pumped from the plunger pump chamber 61 to the distribution port 45 passes through the spill port 59. The pump is then released into the pump chamber 36, thus ending the pressure feeding.

That is, if the sleeve 60 is displaced rightward relative to the plunger 39, the fuel injection end time will be delayed and the fuel injection amount will be increased, and conversely, if the sleeve 60 is displaced leftward, the fuel injection end time will be brought forward. Therefore, the fuel injection amount decreases.

The position control of the sleeve 60 described above is performed by a servo motor 62. That is, the shaft 63 of the servo motor 62 is threaded, and a slider 64 having a threaded hole in the center is screwed into the shaft 63 of the servo motor 62.

A link lever 65 is coupled to this slider 64 so as to be rotatable about a pin 66 as a fulcrum.

The link lever 65 is rotatably attached around a fulcrum 67, and is connected to the sleeve 60 via a pivot pin 72 at the tip of the link lever 65.
is locked.

Therefore, when the servo motor 62 rotates forward and backward, the slider 64 moves left and right, which causes the link lever 65 to rotate about the fulcrum 67 and move the sleeve 60 left and right.

The servo motor 62 is controlled by a servo signal _{S1 output from the servo circuit 18} in response to the fuel injection amount control signal _OS4 .

Therefore, there is no direct correspondence between the accelerator pedal and the fuel injection amount. In other words, the accelerator pedal "want to accelerate" or "want to decelerate"
The calculation device 27 calculates the optimal fuel injection amount according to the driving condition at that time, and performs optimal control using the fuel injection amount control signal OS ₄ . This is what we do.

Further, the shaft of the potentiometer 68 provided near the servo motor 62 is coupled to the shaft 63 of the servo motor 62 by gears 69 and 70, so that the signal from the potentiometer 68 is transmitted to the sleeve 63.
It will indicate the position at 0. This signal becomes the aforementioned sleeve position signal _IS9 .

On the other hand, the electromagnetic type fuel cutoff valve 71 is controlled to open and close by the fuel cutoff control signal OS ₃ , and when the fuel cutoff valve 71 is cut off, the intake port 37 is closed and the fuel is cut off, thereby stopping the engine. There is.

The present invention relates to a safety function in the event that the fuel cutoff valve 71 shown in FIG. 2 fails.

This will be explained in detail below.

FIG. 4 is a block diagram of one embodiment of the present invention, and FIG. 5 is a signal waveform diagram of the circuit of FIG. 4.

In FIG. 4, the time limit circuit 104 consists of a charging/discharging circuit composed of a diode D ₁ , a capacitor C ₁ , and a resistor R ₁ , and a switching circuit composed of a transistor Q ₁ and the like. and while the key switch 102 is on and the key switch 10
The transistor _Q1 is on for a predetermined time _τ1 determined by the time constant of the charging/discharging circuit from the time _T1 when the key switch 102 is turned off, and the key switch 102 is turned off and the voltage _V1 becomes 0. It turns off at time _T4 , which is a predetermined time _τ1 after time _T1 .

The contact of relay 105 is on while transistor _Q1 is on. Therefore, the voltage V ₂ downstream of the relay 105, that is, the power supply voltage of the determination circuit 107 and the control circuit 111, remains at the battery 10 for a predetermined time τ ₁ even after the key switch 102 is turned off.
The voltage is kept at 1.

Next, the time limit circuit 106 includes a charging/discharging circuit composed of a diode D ₂ , a capacitor C ₂ , and a resistor R ₂ .
It is composed of transistors Q ₂ , Q _{3 ,} etc., and outputs a voltage V ₃ that becomes a low level at a time T 3 after a predetermined time τ ₂ (τ ₂ <τ ₁ ) from the time T ₁ when the key switch ₁₀₂ is turned off. do.

On the other hand, the oil pressure switch 110 outputs a voltage _V5 that becomes a low level when the lubricating oil pressure of the engine or the fuel oil pressure in the injection pump falls below a predetermined value.

If the fuel cutoff valve 103 (corresponding to 71 in FIG. 2) is normal, when the key switch 102 is turned off, the fuel supply is cut off and the engine is stopped, and there is some delay time τ ₃ from time T ₁ . At time T ₂ later (τ ₃ <τ ₂ ), the oil pressure drops below the predetermined value, so the voltage V ₅ becomes a low level.

Note that if the fuel cutoff valve 103 fails and the engine continues to operate even after the key switch 102 is turned off, the voltage V ₅ continues to be at a high level as indicated by the broken line V ₅ '.

Next, in the determination circuit 107, the time limit circuit 10
The voltage V ₄ obtained by inverting the voltage V ₃ given from the inverter 109 and the voltage V ₅ of the hydraulic switch 110
The AND circuit 108 calculates the logical product with .

Since the value of the predetermined time τ ₂ of the time limit circuit 106 is set longer than the delay time τ ₃ until the engine stops under normal conditions, the output V ₆ of the AND circuit 108 is always at a low level during normal times. However, if an abnormality occurs and the engine continues to operate even after the key switch 102 is turned off, the predetermined time τ ₂
Later V ₆ becomes high level.

When V ₆ becomes high level, the control circuit 111 provides a stop signal S ₂ to the engine stop means 112 to stop the engine.

The engine stop means 112 is, for example, the throttle valve 9 shown in FIG. ₁ or the sleeve 60 shown in FIG. , shut off the intake air and/or fuel and stop the engine. The fully closed position of the sleeve 60 is a position in FIG. 2 where the sleeve 60 does not cover the spill port 59 at all (moves to the left in the drawing), and in this position the fuel injection amount becomes zero.

Next, when a predetermined time τ ₁ has elapsed after the key switch 102 is turned off, the relay 105 is turned off, so the determination circuit 107 and the control circuit 111 are cut off from the battery 101, and all devices are stopped.

As mentioned above, in the circuit shown in Figure 4, if the oil pressure remains at a predetermined value or more even after a predetermined time τ ₂ has passed after the key switch is turned off, it is determined that the fuel cutoff valve has failed, and the engine is stopped by other means. Therefore, the engine can be reliably stopped even in the event of a failure of the fuel cutoff valve.

Furthermore, in order to keep the judgment circuit and the control circuit operating even after the key switch is turned off, a time limit circuit 104 is configured to keep both of the circuits connected to the power supply for a predetermined time τ ₁ . are doing.

The engine stop means 112 may be provided with two fuel cutoff valves, one of which is opened and closed normally by a key switch, and the other closed only when the stop signal _S2 is given.

Further, instead of the oil pressure switch 110, a lift sensor 25 which outputs the injection start signal _IS7 may be used.

FIG. 6 is a diagram of an embodiment in which a lift sensor is used.

In FIG. 6, the injection start signal ^IS7 output by the lift sensor 25 is a pulse-like signal output every time the engine performs fuel injection. this
After amplifying IS ₇ with operational amplifier 113 (V _M is the midpoint voltage), diode D ³ , capacitor C ₃ , and resistor
Give to the charge/discharge circuit consisting of R ₃ .

The output of this charging/discharging circuit i.e. capacitor C ₃
The terminal voltage V ₇ is at a high level while the injection start signal IS ₇ is continuously input, but becomes a low level when IS ₇ is no longer input.

This voltage V ₇ is compared with a reference voltage V _S by a comparator 114 to create a signal that becomes low level when V _S ≧V ₇ ; this is used as V ₅ .

Further, in FIG. 4, the determination circuit 107 and the control circuit 111 are operated by a microcomputer (2 in FIG.
7).

FIG. 7 is an embodiment of a flowchart showing calculations when both of the above circuits are configured by a microcomputer. The calculation shown in FIG. 7 is repeated at regular intervals or in synchronization with engine rotation.

In FIG. 7, it is first determined at _P1 whether the key switch is on or not. If YES, the engine is running, so the program immediately goes to _P2 to perform another control routine.

If _P1 is NO, go to _P3 and increment the counter by 1 for each operation.

Next, in _P4 , it is determined whether the value of the counter is longer than a predetermined time _τ2 ( _τ2 in FIG. 5), and if NO, the process goes to _P2 .

If YES in P ₄ , go to P ₅ and determine whether the oil pressure switch is on (hydraulic is high, that is, the engine is running).

If YES at _P5 , the fuel cutoff valve has failed, so fully close the sleeve and throttle valve at _P6 and _P7 to stop the engine, then go to _P8 .

If _P5 is NO, the engine has stopped normally, so go to _P8 immediately.

At P ₈ , the value of the counter changes for a predetermined time τ ₁ (τ ₁ in Figure 5).
It is determined whether or not the above is true, and if YES, go to _P9 , turn off the power of the control system, and complete all operations.

If P ₈ is NO, go to P ₂ and the counter value is τ ₁
The operation continues until reaching .

As explained above, according to the present invention, if the engine is still running after the key switch is turned off, it is determined that the fuel cutoff valve is malfunctioning, and the engine is stopped using other stopping means. Therefore, even if the fuel cutoff valve fails, the engine can be reliably stopped. Furthermore, even after the key switch is turned off, the power supply is connected only for the time necessary for failure determination and engine stop control, so battery power is not wasted.

[Brief explanation of drawings]

FIG. 1 is a diagram of an example of a control system for a diesel engine to which the present invention is applied, FIG. 2 is a sectional view of an example of an injection pump, FIG. 3 is a diagram of an example of a conventional fuel cutoff valve control circuit, and FIG. FIG. 5 is a signal waveform diagram of the circuit of FIG. 4, FIG. 6 is a diagram of another embodiment of the present invention, and FIG. 7 is a flowchart showing an operation of the present invention. This is an example diagram. Explanation of symbols, 1...Air cleaner, 2...Intake pipe, 3...Main combustion chamber, 4...Swirl chamber, 5...Glow plug, 6...Injection nozzle, 7...Injection pump, 8...Exhaust Pipe, 9... Throttle valve, 10... Diaphragm valve, 11... EGR valve, 12, 13...
Solenoid valve, 14...Vacuum pump, 15...Constant pressure valve, 16...Battery, 17...Glow relay, 18...Servo circuit, 19...Glow lamp, 20...Accelerator position sensor, 21...Crank Angle sensor, 22...neutral switch,
23...Vehicle speed sensor, 24...Temperature sensor, 25
... Lift sensor, 26 ... Atmospheric density sensor, 2
7... Arithmetic unit, 28... CPU, 29...
ROM, 30... RAM, 31... Input/output interface, 32... Inlet, 33... Drive shaft, 34... Feed pump, 35... Pressure adjustment valve, 36... Pump chamber, 37... Suction port,
38...High pressure plunger pump, 39...Plunger, 40...Eccentric disk, 41
...Joint, 42...Face cam, 43...Roller ring, 44...Roller, 45...Distribution port, 46...Delivery valve, 47...Driving pin, 48...Plunger, 49...Cylinder, 49a... ... passage, 50 ... casing, 50
a... Passage, 51, 52... Oil chamber, 53... Fuel passage, 54... Solenoid valve, 55... End face high pressure chamber, 5
6... Passage, 57... Low pressure chamber, 58... Spring, 59... Spill port, 60... Sleeve,
61... Plunger pump chamber, 62... Servo motor, 63... Shaft, 64... Slider, 65... Link lever, 66... Pin, 67... Fulcrum, 68
...Potentiometer, 69,70...Gear, 7
1...Fuel cutoff valve, 72...Pivot pin, 10
1...Battery, 102...Key switch, 10
3...Fuel cutoff valve, 104...Time limit circuit, 105
... Relay, 106 ... Time limit circuit, 107 ... Judgment circuit, 108 ... Inverter, 109 ... AND circuit, 110 ... Oil pressure switch, 111 ... Control circuit, 112 ... Engine stopping means, 113 ...
…Operation amplifier, 114…Comparator, _IS1 …Accelerator position signal, _IS2 …Reference pulse, IS3…Unit pulse, _IS4 …Neutral signal, _{IS5 …} Vehicle speed signal, _IS6 … Temperature signal, IS ₇ ...Injection start signal,
IS ₈ : Atmospheric density signal, IS ₉ : Sleeve position signal, IS ₁₀ : Battery voltage signal, IS ₁₁ : Starter signal, IS ₁₂ : Glow signal, OS ₁ : Throttle valve opening control signal, OS ₂ ...EGR control signal, OS ₃ ...Fuel cutoff control signal, OS ₄ ...Fuel injection amount control signal,
OS ₅ ...Injection timing control signal, OS ₆ ...Glow control signal, OS ₇ ...Glow lamp control signal, _S1 ...Servo signal.

Claims (1)

[Scope of Claims] 1. A control device for a diesel engine equipped with a fuel cutoff valve that supplies and cuts off fuel in response to on/off of a key switch, comprising means for detecting that the engine is in operation, and a means for detecting that the key switch is in operation. means for detecting that a predetermined period of time has elapsed since the time the device was turned off; and inputting the detection signals of both of the above means;
A control device for a diesel engine, comprising means for determining that a fuel cutoff valve has failed if the engine continues to operate even after a predetermined period of time has elapsed after a key switch is turned off. 2. In a diesel engine control device equipped with a fuel cutoff valve that supplies or cuts off fuel in response to the on/off state of a key switch, a first means for detecting that the engine is in operation and a first means for detecting that the key switch is turned off. a second means for detecting that a first predetermined time has elapsed from the point in time when the key switch is turned off; a third means for determining that the fuel cutoff valve is malfunctioning when the fuel cutoff valve is malfunctioning; and a fourth means for stopping the engine by operating an engine stop means other than the fuel cutoff valve when the third means determines that the fuel cutoff valve is malfunctioning. and fifth means for cutting off the power after a second predetermined time period that is longer than the first predetermined time period has elapsed since the key switch was turned off. 3. The first means outputs a signal indicating that the engine is operating when the lubricating oil pressure of the engine or the fuel oil pressure in the injection pump is equal to or higher than a predetermined value. Diesel engine control device. 4. Claim 2, characterized in that the first means outputs a signal indicating that the engine is operating when there is a signal output every time fuel injection is performed. diesel engine control device. 5. The engine stopping means is a sleeve that adjusts the fuel injection amount of the injection pump, and the fourth means is characterized in that in the event of a failure, the sleeve is displaced to a position where the injection amount is zero to stop the engine. A control device for a diesel engine according to claim 2. 6. A patent claim characterized in that the engine stopping means is a throttle valve provided in the intake system, and the fourth means stops the engine by fully closing the throttle valve in the event of a failure. A control device for a diesel engine according to item 2.