JPS634013B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a diesel engine control device;
In particular, it relates to a safety function when the glow plug remains energized due to a failure in the glow plug energizing circuit or the like.

BACKGROUND ART A diesel engine is provided with a glow plug that heats the inside of a combustion chamber, and the startability is improved by applying electricity to the glow plug and heating it.

In addition, in cold weather, there is a risk that the engine will stall even after self-sustaining operation has started, so some models are configured so that the glow plug is energized for a while after starting (so-called afterglow).

The energizing circuit that controls the energization of the glow plugs as described above generally uses a relay, etc., but in the unlikely event that the relay or the like fails and the glow plug is still energized, the engine will run under high load. If high-speed operation continues, the glow plug may melt due to overheating, and as a result, there is a risk that the cylinder and piston may also be damaged.

The present invention was made to solve the above problem, and when the glow plug is energized even though the energization command signal is turned off, it is determined that the glow plug is malfunctioning, and the engine rotation is stopped. It is an object of the present invention to provide a control device for a diesel engine that prevents melting of a glow plug by controlling the amount of fuel injection so that the speed does not exceed a predetermined value.

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.

Reference numeral 27 denotes an arithmetic unit, for example, a microcomputer including a central processing unit CPU 28, a read-only memory ROM 29, a readable/writable memory RAM 30, 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 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 pumping.

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 amount of fuel injection 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.
This will indicate the 0 position. 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 safety measures in the event of failure of the glow relay 17 shown in FIG. 1, etc., and will be described in detail below.

FIG. 3 is a diagram showing one embodiment of the present invention.

In Fig. 3, 101 is a glow relay (first
102 is a glow plug (corresponding to the glow plug 5 in FIG. 1) provided for each cylinder.

Glow relay 101 receives a high-level activation signal (for example, the glow control signal in FIG. 1) at input terminal 103.
When the ON signal (OS ₆ or glow switch ON signal) is applied, the contact is turned on and the battery voltage V _B is applied to the glow plug 102. Therefore, if the contact of glow relay 101 is on, input terminal 1
04 is given the terminal voltage of the glow plug (referred to as glow voltage), and if it is off, 0V is given.

When the input terminal 104 is at a high level, the transistor 107 is turned on and a high level emitter terminal voltage is sent to the AND circuit 109.

On the other hand, input terminal 105 is given the same operating signal as input terminal 103, inverted by inverter 108, and sent to AND circuit 109.

If the glow relay 101 is normal, when the activation signals applied to the input terminals 103 and 105 are high level, the output of the transistor 107 is high level, the output of the inverter 108 is low level, and the activation signal is Since the opposite is true when the signal is at a low level, the output of the AND circuit 109 is at a low level in either case.

On the other hand, if an abnormality occurs in the glow relay 101 and the contact remains on even when the activation signal becomes low level, a high level glow voltage is applied to the input terminal 104 and the output of the inverter 108 also decreases. Since the level is high, AND circuit 109
output becomes high level.

When the output of the AND circuit 109 becomes high level, the glow lamp blinking circuit 110 outputs a blinking signal,
The glow lamp 19 is made to blink to indicate the occurrence of an abnormality.

On the other hand, the input terminal 106 is supplied with a signal having a frequency corresponding to the rotational speed of the engine (for example, the unit pulse IS ₃ in FIG. 1). The signal is then converted into an analog voltage by a frequency/voltage converter 111.

Next, in the comparator 112, a reference voltage corresponding to the upper limit of the rotational speed necessary to protect the glow plug is applied.
Compares V _S with the above analog voltage, and outputs a high level if the analog voltage is larger.

When the glow relay 101 is abnormal, the output of the AND circuit 109 is at a high level as described above, so when the output of the comparator 112 is at a high level, the output of the AND circuit 113 is at a high level.

When the output of the AND circuit 113 becomes high level,
The output of the fuel injection amount setting circuit 114 is limited to a constant value. This constant value is, for example, the amount of fuel to be injected when the glow plug is rotated at a safe rotational speed for protection under no-load conditions.

The fuel injection amount control signal OS ₄ output from the fuel injection amount setting circuit 114 is applied to the servo circuit 18 to control the servo motor 62 that adjusts the fuel injection amount of the injection pump.

The servo circuit 18 generates a servo signal S 1 corresponding to the difference between the sleeve position signal IS ₉ outputted by the potentiometer 68 indicating the rotational position (sleeve position) of the servo motor 62 and the above fuel injection amount control signal OOS _{4 .} is applied to the servo motor 62 and controlled so that the difference between the two disappears.

As described above, according to the circuit shown in Figure 3, if the glow plug becomes abnormally energized due to a failure of the glow relay, the glow lamp will blink to indicate the occurrence of the abnormality, and the glow plug will melt. Since the amount of fuel injection is limited so as to operate at a rotation speed below a safe rotation speed, there is no risk of melting the glow plug and resulting damage to the cylinder or piston.

Note that the energizing circuit for the glow plug may be composed of parts other than relays, but in any case, the signal that activates the glow plug (glow control signal OS ₆ in Figure 1) is not output. If there is no glow voltage at the terminal of the glow plug, it can be determined that an abnormality has occurred.

Furthermore, in the circuit shown in FIG. 3, the portion surrounded by broken lines can be constructed by a microcomputer (27 in FIG. 1).

FIG. 4 is an embodiment of a flowchart of calculations when a microcomputer performs the control indicated by the broken lines in FIG.

In Fig. 4, first, the glow control signal OS ₆ is activated at P ₁ .
If it is YES, it is normal and the calculation ends immediately, and if NO, it goes to _P2 . Note that the determination of _P1 is specifically made with reference to the contents of the address corresponding to the glow control signal in the PAM 30 shown in FIG.

Next, in _P2 , it is determined whether or not a glow voltage exists by detecting the terminal voltage of the glow plug, and if NO, it is normal and the calculation ends immediately.

If _P2 is YES, it means that an abnormality has occurred, so in _P3 , the glow lamp is made to blink (specifically, the glow lamp control signal OS ₇ is made to be a blinking signal) to indicate the occurrence of an abnormality.

Next, the rotation speed is read in _P4 , and in _P5 it is determined whether the rotation speed is below a safe predetermined rotation speed that will not cause the glow plug to melt.If YES, the calculation is immediately finished.

If P ₅ is NO, go to P ₆ and output the fuel injection amount control signal OS ₄ corresponding to the fuel injection amount when the glow plug is rotated at a predetermined rotation speed that is safe for protecting the glow plug in a no-load state. .

As explained above, according to the present invention, if a glow voltage is generated even though a signal for activating the glow plug is not output, it is determined that there is an abnormality, the glow lamp is blinked to indicate the abnormality, and the fuel injection Since the amount is limited and the rotational speed is limited to below a predetermined value, it is possible to prevent melting of the glow plug and associated damage to the cylinder and piston.
In addition, even in abnormal situations, minimal operation can be maintained, so
It is possible to avoid hindrance to driving to a repair shop or the like.

[Brief explanation of the drawing]

FIG. 1 is a diagram of an example of a control device for a diesel engine to which the present invention is applied, FIG. 2 is a sectional view of an example of an injection pump, and FIG. 3 is a circuit diagram of an embodiment of the present invention.
FIG. 4 is an embodiment of a flowchart of the present invention. 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
...Coupling, 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, 5
0a... Passage, 51, 52... Oil chamber, 53... Fuel passage, 54... Solenoid valve, 55... End face high pressure chamber,
56... 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, 71... Fuel cutoff valve, 72... Pivot pin, 101... Glow relay, 102... Glow plug, 103-106... Input terminal, 107...
...Transistor, 108...Inverter, 109
...AND circuit, 110...Glow lamp blinking circuit, 111...Frequency/voltage converter, 112...
Comparator, 113...AND circuit, 114...Fuel injection amount setting circuit, IS ₁ ...Accelerator position signal, IS ₂
...Reference pulse, IS ₃ ...Unit pulse, IS ₄ ...Neutral signal, IS ₅ ...Vehicle speed signal, IS ₆ ...Temperature signal, IS ₇ ...Injection start signal, IS ₈ ...Atmospheric pressure 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, S ₁ ... Servo signal.

Claims (1)

[Claims] 1. In a diesel engine control device equipped with a means for controlling energization to a glow plug and a means for controlling the amount of fuel injection, if a signal instructing energization to a glow plug is not output, but a signal is applied to a glow plug terminal. A control device for a diesel engine, comprising means for determining that there is an abnormality when a voltage is applied, and means for limiting the amount of fuel injection so that the engine rotational speed is below a predetermined value when the abnormality occurs.