JPS61142339A - Control device for diesel-engine - Google Patents

Abstract

PURPOSE:To eliminate a physical disorder feeling and a discomfortable feel in due to abrupt deceleration, by setting a predetermined limit value for the rate of decrease in the amount of fuel injection upon deceleration so that the degree of deceleration is controlled and by changing over the limit value in accordance with the gear shift position. CONSTITUTION:Upon engine operation, after a fuel injection amount computing means 105 computes a fuel injection amount S6 in accordance with a rotational speed signal S2 and an accelerator positions signal S2, a subtracting means 106 calculates a difference S8 between the calculated fuel injection amount S6 and the previous fuel injection amount S7 stored in a hold means 112. Further, in this stage, a limit value setting means 109 sets a limit value S9 in accordance with the output of a gear position sensor 103, and a comparing means 107 compares the value with the above-mentioned difference S8. Therefore, if S8>=S9, the comparing means 107 delivers a high level signal S10. This signal S10 is delivered to an AND means 108 together with a brake actuating signal S5, and this AND means 108 delivers an output to change over a change-over means 110 so that the amount of fuel injection is controlled in accordance with an output signal S12 delivered from a subtracting means 111 for subtracting the signal S9 from the above-mentioned fuel injection amount signal S6 or the signal S7.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for a diesel engine for a vehicle, and particularly to fuel control during deceleration.

In a diesel engine, the pressure inside the cylinder is high due to high compression, and mechanical loss due to friction etc. is large.

Therefore, when decelerating with the accelerator pedal in the fully open position (idle position), engine braking (negative torque) is applied more strongly than with a gasoline engine, especially when the accelerator pedal is in the fully open position at a specified rotation speed or higher. In an engine equipped with a fuel cutoff function, the negative torque generated by the engine brake is large, so the traveling speed of the vehicle is rapidly reduced.

As a result, the sense of deceleration is too large, which may make the occupants feel uncomfortable.Also, when operating the transmission (so-called gear shift), the deceleration may occur suddenly every time the accelerator pedal is fully opened (particularly when the rotation speed exceeds a predetermined speed, the fuel Since the engine is shut off, the degree of deceleration is large), so when the clutch is engaged after the gear shift is completed, a sudden engine brake is applied.

There is a risk of causing discomfort to the passengers.

The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to provide a control device for a diesel engine that controls the engine so as not to cause discomfort or discomfort due to sudden deceleration.

In order to achieve the above object, the present invention controls the degree of deceleration by setting a predetermined limit value on the rate of decrease in the amount of fuel injected during deceleration, and sets the above limit value according to the gear position. The configuration is such that more precise control can be performed by switching.

FIG. 6 is a block diagram showing the configuration of the present invention.

First, in FIG. 6, 200 is an actuator 204
This is a control signal for controlling the engine speed, and is calculated according to, for example, the depression angle of the accelerator pedal or the rotational speed of the engine.

201 is a first unit that detects that the engine is decelerating;
It is a means of

When the detection result of the first means 201 is that the engine is decelerating, the second means 202 sets and outputs the control signal so as to limit the rate of decrease in the fuel injection amount to a predetermined limit value or less.

The third means 203 changes the value of the limit value of the second means 202 according to the shift position of the transmission.

Actuator 204 is controlled by a control signal limited by second means 202 . This actuator 204 drives the fuel injection amount adjustment mechanism, and fuel is injected accordingly.

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

FIG. 1 is a diagram showing an example 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 10 is a diaphragm valve that controls the opening of the throttle valve; 11 is an EGR valve that controls the amount of EGR (exhaust gas recirculation amount) recirculated from the exhaust pipe 8 to the intake pipe 2; 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 a brake servo pump, for example. Also, 15 is a vacuum pump 14
constant pressure valve that creates a constant negative pressure from the negative pressure applied, 16
17 is a battery, 17 is a glow relay that controls the energization of the glow plug 5, 18 is a servo circuit that controls the fuel injection amount of the injection pump 7, and 19 is a glow lamp that indicates the energization state of the glow plug 5. Further, 20 is an accelerator position sensor that outputs an accelerator position signal IS corresponding to the accelerator pedal position II (depression angle), and 21 is an accelerator position sensor that outputs a reference pulse IS for each reference angle (for example, 120°) of the crank angle. 1°), a crank angle sensor 22 outputs a unit pulse IS, and 22 detects that the transmission is in the neutral position and outputs a neutral signal S.
A neutral switch 23 outputs a vehicle speed signal IS corresponding to the vehicle speed, a vehicle speed sensor outputs a vehicle speed signal IS (detected from the rotation speed of the output shaft of the transmission), and 24 outputs a temperature signal IS corresponding to the engine cooling water temperature. The temperature sensor 25 is a lift sensor that outputs an injection start signal IS every time the injection nozzle 6 starts fuel injection, and is a switch or piezoelectric element operated by fuel pressure, for example. Also 2
6 is an atmospheric density signal IS corresponding to atmospheric temperature and pressure;
This is an atmospheric density sensor that outputs . In addition, signals such as a sleeve position signal rss (details will be described later) corresponding to the position of the sleeve that controls the fuel injection amount of the injection pump 7 and a dispersion voltage signal IS1° are used.

Further, 27 is an arithmetic unit, for example, a central processing unit (CP
The microcomputer includes a read-only memory (ROM) 29, a read/write memory (RAM) 30, an input/output interface 31, and the like.

The calculation bag @27 is each signal IS, ~ISt given from the above-mentioned various sensors. and a starter switch (not shown)
starter signal IS, □, which is applied from the starter motor (on when the starter motor is activated), and glow signal IS1, which is applied from the glow switch. Input a signal such as

It outputs various control signals O8□ to O87 for optimally controlling the diesel engine.

First, throttle valve opening control signal O81 and EGR control signal O82
are pulse signals, and by controlling the duty of the solenoid valves 12 and 13 by changing the duty of these pulse signals, the opening degree of the throttle valve 9 and the opening degree of the EGR valve 11 are controlled.

Further, the fuel cutoff control signal O83 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 O84 and the sleeve position signal IS are given to the servo circuit 18.

The servo circuit 18 outputs a servo signal S so that both signals match, and the sleeve position is controlled by this servo signal S1, thereby controlling the fuel injection amount.

Further, the fuel injection timing is controlled by controlling the injection timing control mechanism in the injection pump 7 using the injection timing control signal O8. The injection timing is feedback-controlled using the injection start signal S7 from the lift sensor 25.

Furthermore, by controlling the glow relay 17 using the glow control signal oS6, the energization of the glow plug 5 is controlled.

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 is turned off when it is 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 the engine output shaft.

The fuel discharged from the feed pump 34 is transferred to a pressure regulating valve 35.
The supply pressure is controlled by the pump housing and supplied to the pump chamber 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 boat 37.

The plunger 39 of this pump 38 is fixed to an eccentric disk 40 connected to the drive shaft 33, and is connected to the drive shaft 3 through a joint 41.
3, it is driven in synchronization with engine rotation.

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

Therefore, the plunger 39 reciprocates while rotating,
Due to this reciprocating movement, the fuel sucked from the suction boat 37 is forced from the distribution boat 45 to the injection nozzle 6 shown in FIG. 1 through the delivery valve 46.

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

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

In FIG. 2, plunger 4 is shown for convenience of explanation.
8 is rotated by 90 degrees, and the feed pump 34 is
At the same time, the axis is also shown rotated by 90 degrees.

The cylinder 49 containing the plunger 48 is connected to the casing 5
The oil chamber 51 is slidably housed inside the cylinder 49, and an oil chamber 51 is defined at the right end of the cylinder 49, and an oil chamber 52 is formed 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. - Also, 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 via one passage 56, and the low pressure chamber 57 on the opposite side is connected to the suction side of the feed pump 34. It communicates and becomes close to negative pressure, but
The plunger 48 is pushed back by the elastic force of the spring 58.

Since the fuel pressure in the pump chamber 36 increases in proportion to the rotational speed of the feed pump 34, when the passage 49a is closed as shown in the figure, the plunger 48 moves to the left in the drawing as the engine rotational speed increases. This causes the roller ring 43 to rotate in the opposite direction to the rotational direction of the eccentric disk 40, so that the injection timing becomes earlier in accordance with the rotational speed.

Furthermore, 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 5
4 is opened), the oil chamber 5 is opened via the passages 49a and 50a.
1 and the end high pressure chamber 55 communicate with each other, the pressure in the end high pressure chamber 55 can be controlled by opening and closing the solenoid valve 54. Therefore, injection timing control signal O8
, if the opening/closing of the solenoid valve 54 is duty-controlled by ,
Injection timing can be controlled electrically.

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 is transferred to the spill port 59.
9 and is released into the pump chamber 36, thus ending the pressure feeding.

That is, when the sleeve 60 is displaced rightward relative to the plunger 39, the fuel injection end time is delayed and the fuel injection amount is increased, and when the sleeve 60 is displaced leftward, the fuel injection end time is advanced. This results in a decrease in the amount of fuel injected.

The position of the sleeve 60 is controlled by a servo motor 62. A 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 bin 66 as a fulcrum.

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

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 the fuel injection amount control signal O84.
This is performed by a servo signal S output by the servo circuit 18 in response to the servo signal S.

Therefore, there is no direct correspondence between the accelerator pedal and the fuel injection amount. In other words, the accelerator pedal is
It becomes a means to simply convey the driver's intention such as "I want to accelerate" or "I want to decelerate" to the computing device 27, and the computing device! 2
7 calculates the optimal fuel injection amount according to the operating state at that time, and performs optimal control using the fuel injection amount control signal O84.

Further, the shaft of a 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 indicates the position of the sleeve 60.

This signal becomes the sleeve position signal IS.

On the other hand, the electromagnetic fuel cutoff valve 71 is controlled to open and close by the aforementioned fuel cutoff control signal O83, and when cut off, the intake port 37 is closed to cut off the fuel, thereby stopping the engine.

The present invention relates to control of the fuel injection amount control signal O84 shown in FIG. 1 during deceleration.

This will be explained in detail below.

FIG. 3 is a functional block diagram of an embodiment of the present invention.

In FIG. 3, 1 rotational speed sensor 101 (21 in FIG.
) outputs a rotational speed signal S corresponding to the rotational speed of the engine.

Also, the accelerator position sensor 102 (corresponding to 20 in Fig. 1)
outputs an accelerator position signal S (corresponding to S in FIG. 1) corresponding to the accelerator pedal position (depression angle).

Further, the gear position sensor 103 is, for example, a switch provided for each shift position of the transmission, and outputs a gear position signal S4 corresponding to the shift position.

Furthermore, the brake sensor 104 outputs a brake activation signal S that is at a low level while the brake is being applied (when the brake pedal is being depressed).

The injection amount calculation means 105 calculates the injection amount according to the rotational speed signal S2 and the accelerator position signal S, and outputs the injection amount signal S.
For example, the characteristic is that 86 increases as S2 and S3 increase, which outputs 6. Note that when the rotational speed is above a predetermined value (for example, 700 rpm) and the accelerator pedal is in the fully open position, fuel cutoff (injection amount=O) is performed.

On the other hand, the hold means 112 stores and outputs the value S7 of the fuel injection amount control signal O84 a certain period of time ago.

Note that if the calculation is performed at regular intervals or intermittently in synchronization with engine rotation, the previous fuel injection amount control signal O8
, and outputs it.

For example, when the calculation is performed once every revolution of the engine, the holding means 112 holds the value of the fuel injection amount control signal O84 (this is set to 87) in the − times previous calculation.
is stored and output until the current calculation, and when a new value of O8° is obtained by the current calculation, it is stored and output until the next calculation, and this process is repeated sequentially.

Next, the subtracting means 106 calculates O8. in the previous calculation given from the holding means 112. What is the difference between the value S, and the value S of the injection amount signal in this calculation, that is, S, -S, =
Outputs S.

Further, the limit value setting means 109 inputs the gear position signal S4, calculates a limit value according to the gear position at that time, and outputs a limit value signal S. Note that the limit value is set to be a larger value as the gear position becomes lower (position II where the gear ratio is larger). That is, when the gear position is low, the driver often requires engine braking, so the degree of restriction is loosened to improve the effectiveness of engine braking.

Comparison means 107 compares S and S, and S8≧S.

When this happens, a signal 51fi which becomes high level is output.

Further, the subtracting means 111 outputs a signal S1□ (S□,=S, -8.) obtained by subtracting the limit value signal S from the value S7 of O84 in the previous calculation output from the holding means 1126. On the other hand, One input terminal of the AND means 108 is connected to the signal S of the comparison means 107 . is applied to the other input terminal, and a brake activation signal Ss is applied to the other input terminal.

Since the brake operation signal SS is at a high level when the prekinesis is activated, the signal S1□ of the AND means 108 is
When the prekinesis is activated, if the signal Sla is at a high level, the level becomes high, and if the signal Sla is at a low level, it becomes a low level.

However, while the brake is being applied, the brake activation signal is S.

Since is at a low level, the signal S□ is the signal S□.

Regardless, it will always be at a low level.

Next, the A terminal of the switching means 110 receives the injection amount signal S6.

A signal sti is applied to the B terminal. and switching means 1
10 switches to the A side to pass the injection amount signal S when the signal SXZ is at a low level, and switches to the B side to pass the signal S18 when the signal S is at a high level. This signal S or S1□ is applied as the fuel injection amount control signal O8 to the servo circuit 113 (corresponding to 18 in FIG. 1), and the servo motor 114 (corresponding to 62 in FIG. 2) is driven to adjust the injection amount. The amount of fuel injected is controlled by displacing the sleeve (60 in FIG. 2).

Therefore, in the circuit of FIG. 3, the injection amount is controlled as follows.

First, when S<S, that is, when not decelerating or even during deceleration, the difference S8 between the injection amount a certain time ago and the calculated value of the current injection amount is a predetermined limit value S that is determined according to the gear position.
, J, the injection amount signal S6 calculated according to the one-rotation speed and the accelerator pedal position is output as is as the fuel injection amount control signal O84.

On the other hand, if S0≧89, that is, if the difference S1 between the injection amount a certain time ago and the calculated value of the current injection amount is greater than or equal to the limit value S9, the limit value S is calculated from the injection amount S7 a certain time ago. The subtracted signal S1. is output as the fuel injection amount control signal O84.

Therefore, the speed at which the injection amount decreases is
Since the deceleration is limited to a predetermined limit value for each calculation, the degree of deceleration is also slower than in the past, and there is no discomfort or discomfort to the occupants.

FIG. 4 is a comparison diagram of deceleration states, where the dash-dotted line shows the characteristics of the gasoline engine, the solid line M shows the characteristics of the present invention, and the broken line N shows the characteristics of the conventional diesel engine, and also shows the case where deceleration starts at time t0.

As can be seen from FIG. 4, in the case of the present invention, the degree of deceleration is gentler than in the past, approaching the characteristics of a gasoline engine. Further, the degree of deceleration (the slope of M) can be arbitrarily set by changing the value of the limit value signal SS.

Furthermore, while the brake is in operation, the calculated value of the current injection amount is output as is, regardless of other conditions, so the effect of the engine brake can be utilized to the fullest. Especially when the accelerator pedal is fully opened at a speed higher than the specified rotation speed,
Since the fuel is cut off, engine braking becomes very strong and braking distances can be shortened.

Next, the portion indicated by the broken line in FIG. 3 can be constructed by a microcomputer (27 in FIG. 1).

FIG. 5 is an embodiment of a flowchart showing calculations when the broken line portion in FIG. 3 is constructed by a microcomputer. Note that the calculation shown in FIG. 5 is repeatedly performed, for example, at regular intervals or in synchronization with engine rotation.

In FIG. 5, first, the accelerator pedal position is read at Pl, and the rotational speed is read at P2.

Next, at P, an injection amount S (corresponding to 86 in FIG. 3) is calculated according to the read accelerator pedal position and rotational speed by table lookup or the like.

Next, in P4, calculate the difference Δ5=S0-8 between the previous injection amount S (corresponding to S in Figure 3) and the calculated value S of the current injection amount (ΔS corresponds to 88 in Figure 3). ).

Next, it is determined whether ΔS>0 at P. If No in P, the vehicle is not decelerating, so normal control continues.

If YES at P, the vehicle is decelerating, so it is determined whether the brake is in operation or not by going to Ps.

If P6 is No, set a limit value corresponding to the gear position in P7 (corresponding to S in Fig. 3), and then P.

It is determined whether ΔS≧L.

If YES at P8, then P, and S'=S, -L(S
' corresponds to StZ in FIG. 3) and calculate the first-order Pl.

After storing S as 8 in the next calculation, P
At 11, S' is output as the fuel injection amount control signal O84.

On the other hand, in the case of YES in P6 and in the case of NO in P8, S is stored as the next S in P1□, and then S is outputted as the fuel injection amount control signal O84 in P13.

As explained above, the present invention is configured to limit the rate at which the injection amount decreases during deceleration to a predetermined limit value or less, so that the degree of deceleration can be made comparable to that of a gasoline engine, and the occupant It does not cause any discomfort or discomfort. Further, since the deceleration is configured to be changed according to the above-mentioned limit value and gear position, the deceleration can be adjusted to suit the actual driving condition of the vehicle. Further, since the above-mentioned restriction is canceled when the brake is applied, the braking distance can be shortened by making full use of the effect of engine braking.

[Brief explanation of drawings]

Fig. 1 is an example of a diesel engine control device to which the present invention is applied, Fig. 2 is an example of an injection pump, Fig. 3 is a block diagram of an embodiment of the present invention, and Fig. 4 is a comparison of deceleration characteristics. 5 is an embodiment of a flowchart showing the calculations of the present invention, and FIG. 6 is a block diagram showing the configuration of the present invention. Explanation of symbols 1... Air cleaner 2... Intake pipe 3... Main combustion chamber 4... Vortex chamber 5... Glow plug 6... Injection nozzle 7... Injection pump
8... Exhaust pipe 9... Throttle valve 10...
Diaphragm valve 11...EGR valve 12.1
3...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 2
5... Lift sensor 26... Atmospheric density sensor 27... Arithmetic unit 28... CPU29.
...ROM 30...PAM3
1... Input/output interface 32... Inlet 33... Drive shaft 34... Feed pump 35... Pressure regulating valve 36... Pump chamber 37... Suction boat 38... High pressure plunger pump 39...Plunger 40...Eccentric disk 41...Joint 42...Face cam 43...Roller ring 44...Roller 45...
...Distribution boat 46...Delivery valve 47
...Driving pin 48...Plunger 49.
... Cylinder 49a... Passage 50... Casing 50a... Passage 51, 52... Oil chamber 53... Fuel passage 54... Solenoid valve
55... End 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
...Fully point 68...Potentiometer 69.70.
... Gear 71 ... Fuel cutoff valve 72 ... Pivot pin 101 ... Rotation speed sensor 102 ... Accelerator position sensor 103 ... Gear position sensor 104 ... Brake sensor 105 ... Injection amount calculation Circuit 106... Subtraction means 107... Comparison means 108... AND means 109... Limit value setting means 110... Switching means 111... Subtraction means 112... Holding means 113... Servo Circuit 114...Servo motor Is□...Accelerator position signal IS3...Reference pulse IS,...Unit pulse IS,...Neutral signal IS,...Vehicle speed signal IS,...Temperature signal I
S, . . . injection start signal IS, . . . atmospheric density signal IS, . . . sleeve position signal ISl. ... Battery voltage signal l5L1 ... Starter signal S12 ... Glow signal O8□ ... Throttle valve opening control signal OS, ... EGR control signal O8, ... Fuel cutoff control signal O8, ... ... Fuel injection amount control signal OS5 ... Injection timing control signal OS, ... Glow control signal OS7 ... Glow lamp control signal S1 ... Servo signal

Claims (1)

[Claims] In a diesel engine control device that controls a fuel injection amount by controlling an actuator that drives a fuel injection amount adjustment mechanism using a control signal, a first means for detecting deceleration is being performed, and a fuel injection during deceleration. a second means for setting the value of the control signal so as to limit the rate of decrease in the amount to a predetermined limit value or less; and changing the value of the limit value of the second means in accordance with the shift position of the transmission. A diesel engine control device comprising a third means.