JPS6328224B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rotation speed control device for an automobile engine or the like having an idle rotation speed control function.

Conventionally, in gasoline engines for automobiles, various engine-related controls have been performed, such as A/F (air-fuel ratio) control according to throttle valve opening and load torque, starting correction and warm-up correction, and idle speed control. Most of the controls were performed independently by the vaporizer alone.

However, in recent years, electronic control systems have been developed that use microcomputers (hereinafter referred to as microcomputers) to capture various data representing engine operating conditions and comprehensively control engine operating conditions via various actuators. Engine control systems have become widely adopted.

As an idle speed control device for such an engine control system, for example, an actuator means for controlling the opening degree of a throttle valve in an idle state is provided, and a sensor for detecting engine temperature T _W and engine speed N is used. The actuator means feedback-controls the opening degree of the throttle valve at its return position in accordance with the data of A device is known that performs this, and an example thereof will be explained with reference to FIGS. 1 to 5.

Figure 1 shows the entire system. In the figure, 1 is the engine, 2 is the carburetor, 3 is the slow solenoid, 4 is the main solenoid, 5 is the fuel solenoid, 6 is the limit switch, and 7 is the throttle actuator. 8 is an intake negative pressure sensor, 9 is a cooling water temperature sensor, 10 is a pulse type engine speed sensor, 11 is an idle detection switch, and 12 is a control unit.

FIG. 2 shows the configuration of the throttle actuator 7.

In the figure, 14 is a throttle valve (hereinafter referred to as
13 is a shaft (referred to as a throttle valve), 15 is an opening/closing lever attached to the shaft 14, 16 is a return lever,
17 is a return spring, 18 is a stroke shaft, 19 is a reduction gear, 20 is a DC motor, 2
1 is a spring. In addition, 2 is a vaporizer, 11
1 is an idle detection switch, 12 is a control unit, and 13 is a throttle valve.

When the accelerator pedal is not operated, the throttle valve 13 returns to the return position due to the tension of the return spring 17. At this time, the return position is such that the opening/closing lever 15 is in the position of the stroke shaft 18.
It is determined by the position where it touches. Since the stroke shaft 18 is held on the gear 19 by a screw, it sends a signal to the motor 20 to move the gear 1.
By rotating the throttle valve 9, the return position of the throttle valve 13 can be arbitrarily controlled.

The stroke shaft 18 and the gear 19 as a whole are configured to be able to move slightly in the longitudinal direction of the shaft 18, and when the throttle valve 13 is opened from the return position by operating the accelerator pedal, the stroke shaft 18 and the gear 19 are moved as shown in the figure by the spring 21. As shown by the broken line, the switch 11 is opened by being displaced to the left, and when the throttle valve 13 returns to its return position under the tension of the return spring 17, the opening/closing lever 15 is pressed against the stroke shaft 18, and the spring 21 is pushed in. The switch 11 is configured to close. Therefore,
By turning the switch 11 on and off, it is possible to detect whether the throttle valve 13 is being operated via the accelerator pedal or whether it has returned to the return position.

Furthermore, when the throttle valve 13 returns to the vicinity of the fully closed position, the limit switch 6 operates, so the limit switch 6 closes the throttle valve 13.
It is possible to detect that the throttle valve 13 has returned to near the fully closed position, and the limit switch 6 also functions as a stopper for regulating the maximum return position of the throttle valve 13.

FIG. 3 shows an example of the control unit 12, which includes a control logic 22, a microprocessor 23, a ROM 24, and a multiplexer 2.
5. Consists of an analog-to-digital converter 26, etc., and detects the intake negative pressure V _c from the negative pressure sensor 8 (Fig. 1).
The analog data such as the engine temperature T _w from the water temperature sensor 9 is sent via the multiplexer 25 and the analog-to-digital converter 26 to the data TH _sw from the idle detection switch 11 and the engine rotation speed N from the rotation speed sensor 10. Control logic 2 with digital data intact
2, microprocessor 23, ROM 2
4, etc., and controls various actuators, such as the slow solenoid 3, main solenoid 4, fuel solenoid 5, and throttle actuator 7, to perform optimal control according to the operating state of the engine.

Therefore, in a system configured in this way,
According to various data representing the operating state of the engine, the A/F is controlled to the optimum level through the control of the slow and main solenoids 3 and 4 in the steady operating state, and the fuel solenoid 5 is controlled in the warm-up operating state. By controlling the A/F to the optimum state, and further controlling the throttle actuator 7, it is possible to control the engine rotational speed to the optimum state in the idle state and the left warm-up state.

The control mode for the throttle actuator 7 at this time is to drive the DC motor 20 with pulses in order to enable digital control by the control unit 12, thereby moving the stroke shaft 18 in and out to adjust the throttle. Valve 1
The pulses supplied at this time have a waveform as shown in FIG. 4, and have a predetermined pulse width t during a predetermined repetition period T. Therefore, when this pulse is supplied to the DC motor 20, the number of revolutions obtained each time one pulse is supplied becomes a constant value, and the amount of movement of the stroke shaft 18 is determined by the number of supplied pulses. That will happen.

Then, the return position of the throttle valve 13, that is, the opening degree of the throttle valve 13 in the idle state is determined depending on the position to which the stroke shaft 18 has moved, and the engine rotation speed is thereby determined. As shown in FIG. 5, the engine speed can be controlled by the number of pulses supplied to the DC motor 20 of FIG. In FIG. 5, the straight line UA is the characteristic when a pulse of positive polarity is applied, and the line DB is the characteristic when a pulse of negative polarity is applied.

Therefore, in such an electronic control system, when it is detected that the throttle valve 13 enters the idle state by turning on the idle detection switch 11, the control unit 12 inputs the data T from the water temperature sensor 9 into the program by the microcomputer. Add FISC or ISC program according to _w ,
FISC which takes data N from rotation speed sensor 10 and determines it by data T _w from water temperature sensor 9
The throttle actuator 7 is controlled so that the target rotational speed N _set or the ISC target rotational speed N _set is achieved, and the function as FISC or ISC is performed.

Note that at this time, the throttle actuator 7
There is a kind of hysteresis in the opening control operation of the throttle valve 13 due to the influence of the return spring 17, etc., and as is clear from FIG.
Generally, the change in rotational speed due to

Furthermore, the period T and pulse width t of the pulse A or B at this time are factors that determine the rotation angle of the motor 20 per pulse, and the ratio t/T of these is called the control gain. As this gain becomes larger, the response speed of the throttle actuator 7 becomes faster, that is, the response speed of the control system becomes faster. However, the value of the gain in such a feedback control system has an optimum value that is unique to the control system in terms of both response speed and stability. Therefore, in the conventional idle speed control system described above, For example, as shown in FIG. 6, control is performed to obtain a predetermined gain according to the deviation ΔN between the target rotational speed N _set and the actual engine rotational speed N. In FIG. 6, the pulse period T is plotted on the vertical axis, and therefore, the gain of the control system increases toward the bottom.

In addition, Fig. 7 shows an example of the setting state of the target rotation speed N _set . For example, when the temperature T _w is 50°C or higher, the target rotation speed N _set is set to a constant value N _I , and the temperature T _w
When is below 20℃, the target rotation speed N _set is a constant value
N _F , and in the meantime, the target rotation speed N _set is the temperature T _w
It is made to change in inverse proportion to .

Therefore, according to the above-mentioned idle speed control system, it is possible to accurately control the idle speed from during warm-up to after transition to steady operation, and to obtain an automobile engine that is fully compliant with exhaust gas regulations. In recent years, such control systems have become widely used.

However, in such conventional systems, after the engine is started, the engine starts running before it has finished warming up, and then when it returns to idling, the engine speed increases rapidly, and it takes a long time to reach the specified speed. This has the drawback of causing a phenomenon in which the rotation speed does not return to the idle speed, which causes a great sense of anxiety to the driver.

This will be explained with reference to FIG. Now, after the engine has been started, the engine temperature T _w has hardly risen, and therefore the car is operated to a running state at time t ₀ when control is being performed in the FISC region, and then the engine temperature T _w rises considerably. Assume that it returns to the idle state at time _t1 .

Then, as already explained, since the control of the throttle actuator 7 is stopped from time t ₀ to time t ₁ , the return opening degree of the throttle valve 13 is determined by the target rotation speed in the FISC state. N _F
It remains at the opening corresponding to .
Therefore, when the throttle valve 13 is returned to the idle state at time _t1 , the opening degree of the throttle valve 13 simply returns to a fairly wide opening degree corresponding to the rotational speed N _F in the FISC state.

On the other hand, the engine temperature T _w from time t ₀ to t ₁
has increased considerably, so the rotational resistance of the engine in the idling state has decreased considerably. Therefore, the throttle valve opening only returns to the opening corresponding to the target rotation speed N _F , which causes the engine to The actual rotational speed N increases rapidly after time _t1 as shown in the figure.

At this time, if the control gain of the idle speed control system is sufficiently high, the throttle actuator 7 responds at high speed, and as shown by the solid line of characteristic N in _FIG . The engine speed is immediately set to the target speed N _I in ISC state.
There is no particular problem because it converges to
In the conventional system described above, if the ISC control gain is set high when the accelerator pedal is suddenly operated during idling, which is a so-called idle operation, there is a risk of engine stalling. Therefore, as shown in FIG. 6, it is becoming necessary to set a relatively low gain as represented by gain (2) on the reverse pulse side.

As a result, in the above-mentioned conventional system, as shown by the broken line in the characteristic N in Fig. 8, after time _t1 , control is performed slowly toward the ISC target rotation speed N _I , and the idle rotation speed increases. The situation continues for quite some time.

An object of the present invention is to eliminate the drawbacks of the prior art described above, to quickly converge the increase in idle rotation speed to a predetermined idle rotation speed even after the vehicle is running during warm-up, and to reduce the number of idle rotations. To provide a rotation speed control device that does not cause engine stalling even during operation.

To achieve this objective, the present invention sets the gain of the idle speed control system to the engine operating state when the throttle valve returns to the idle state and immediately before that when the throttle valve enters the state operated by the accelerator pedal. The feature is that it can be switched depending on the situation.

Embodiments of the rotation speed control device according to the present invention will be described below with reference to the drawings.

FIGS. 9 and 10 are flowcharts for explaining the operation of an embodiment of the present invention, and the following will be explained accordingly.

In one embodiment of the present invention, the hardware configuration is the same as that of the conventional example shown in FIGS.
Since it is simply added to the microcontroller inside, a detailed explanation will be omitted.

This program is started periodically, for example, every 40 mS, and when it starts executing, it starts the first step (hereinafter referred to as the first step S1 and the second step S2).
(abbreviated as), the starter switch is
Check whether it is ON or not, and if the result is YES, proceed to S2 and check whether the engine speed N is 300 rpm or more.
When YES, the engine intake negative pressure V _c is set in the next S3.
Check to see if it is 250mmHg or more, and when it becomes YES, set the engine start flag to 1 through S4.
Set to . In other words, all of the results in S1 to S3 become YES only when the engine is starting and complete explosion occurs, so this sets the engine start flag to 1 to indicate that the engine has completed starting. be.

On the other hand, if even one of the results in S1 to S3 is NO, either the engine has started and is in operation, or it is starting but has not yet fully exploded. Because it is
Proceed to the next step S5 and check whether the engine start flag is 1 or not. When the result is NO, it means that the engine has stopped before starting.
In the following S6, in preparation for the engine starting operation, control is entered to set the throttle valve opening suitable for engine starting, and this flow is exited.

Also, if the result in S5 is YES, it means that the engine has started and is running, so first proceed to S7 and turn off the idle detection switch.
Check whether the flag is set to 1 or not, and the result is
If YES, immediately jump to S11. On the other hand, if the result in S7 is NO, it is checked in the next S8 whether the idle detection switch 11 (see FIGS. 1 and 2) is ON, and if the result is YES, the process also proceeds to S11.

However, if the result in S8 is NO, start from S9.
Proceeding to S11 via S10, first, in S9, a table search is performed based on the engine temperature T _w at this time to determine the target rotation speed N _set according to the characteristics shown in Fig. 7, and it is stored in a predetermined memory. I'll keep it. Then S10
Now set the idle detection switch OFF flag to 1. As a result, S9 and S10 are executed only once when the accelerator pedal is operated for the first time after the engine has started, and the idle target rotation speed N _set at that time is stored and the idle detection switch OFF flag is set. It will be set to 1.

The following steps S11 to S14 are steps for determining whether or not to perform idle rotation speed control, that is, control of the throttle actuator 7.NO in S11 and NO in S14.
When it becomes YES, for example when the car is stopped and the accelerator pedal is not operated,
Either when S11, S12, and S14 are all YES, for example, the car is coasting, or when only S12 and S13 of S11 to S14 are NO, for example, when there is a risk of engine stalling due to engine braking. Only when this occurs, the system enters the idle speed control operation and proceeds to the steps after S16. Otherwise, the throttle actuator is stopped through S15, and then this flow is exited. Idle speed control is not performed.

Now, when it is determined that the idle speed control should be performed based on the determination results in S11 to S14, the process first proceeds to _S16 , and the seventh
Read the target rotational speed N _set according to the characteristics shown in the table from the table, and then in S17 (continued in Fig. 10) compare the data N _set stored in S9 with the set value N _L (N _set > N _L ). Setting value at this time
For example, N _L is 1000 rpm as shown in Figure 7.
is selected.

When the result in S17 is NO, when the accelerator pedal is first depressed at time t ₀ in Fig. 8, warm-up has already progressed considerably, and the engine temperature T _w has reached, for example, 45°C or higher. This means that the data N _set given by the characteristics shown in FIG. 7 is below 1000 rpm. In this case, the return opening of the throttle valve immediately before the accelerator pedal was depressed at time t ₀ in Figure 8, that is, the opening of the throttle valve controlled by the throttle actuator, becomes considerably narrower. This means that there is no longer any risk that the engine speed will suddenly increase when the accelerator pedal is released at time _t1 and the throttle valve returns to the idle position. When the result in S17 is NO, the process immediately moves to S21, where the pulse period T is set according to the characteristics of gain (2) in Fig. 6, and then, in S31, gain (2) is applied to the throttle actuator. The throttle valve is controlled slowly by outputting pulses with low gain characteristics.

On the other hand, if the result in S17 is YES, the process first proceeds to S18 to check whether the idle detection switch OFF flag is 1 or not. If the result in S18 is NO, the operating state of the engine is in the state before time t ₀ in Figure 8, and the accelerator pedal has not been depressed even once since the engine started. In this case, it means that
Proceeding to S22, the FISC or ISC control operation with a relatively large gain consisting of steps S22 to S28 is performed.

First, in S22, data ΔN of the difference between the actual engine rotation speed N and the target rotation speed _{N set} obtained according to FIG. The period T according to the characteristics shown in the figure is determined from a table, etc., and in S24 it is determined whether the rotation speed N is higher or lower than the target rotation speed N _set . If it is low, the throttle actuator is rotated normally through S25 and S26. When the pulse is high, a reverse pulse is supplied to the throttle actuator through S277 and S28. Therefore, the throttle valve opening degree is controlled according to the engine rotation speed N in an idling state, and control is performed to converge the engine rotation speed N to the target rotation speed N _set , that is, FISC.
or ISC functions will be performed. and,
At this time, control is performed with a high gain given by the characteristic of gain (1) in Fig. 6, so
This means that control with excellent responsiveness is obtained.

Next, when the result in S18 is YES, it means that the operating state of the engine has reached the state at time _t1 in Figure 8, and there is a risk that the engine's idle speed will suddenly increase. Therefore, when the result in the next S19 is NO, the process immediately moves to S22, and the operation is performed with a high control gain of gain (1). As a result, the engine speed N changes over time as shown by the solid line of characteristic N in Figure 8.
After t ₁ , although the rotational speed increases rapidly, it immediately converges to the target rotational speed N _I , and there is no longer a possibility that the high-speed rotational state will continue for a long time as in the conventional example shown by the broken line.

On the other hand, the steps after S22 have already been executed,
If the determination result in S29 is YES, that is, the engine rotation speed N is controlled to be equal to the target rotation speed N _set , the slow pulse period set flag is set to 1 in S30. Therefore, in this case, the process proceeds to S20, and it is determined whether the engine rotation speed N is higher than the target rotation speed N _set by a predetermined rotation speed of, for example, 200 rpm (N-N _set > 200 rpm),
When the result is YES, control proceeds to S21 and control is performed using a small gain (2), and when the result is NO, control is performed using a large gain (1) toward S22.

As a result, according to the above embodiment, the slow pulse cycle set flag is set to 1 by S30 when the accelerator pedal is depressed for the first time after starting the engine and the car is driven, or after the engine is run dry. , after the second or subsequent driving, or after the engine runs dry, the gain will always be switched based on the result of S20, and the engine speed N will be the target speed.
It is in a state where the rpm is not higher than N _set ,
Therefore, if there is no risk of hunting occurring even if idle speed control is performed with a large gain, control with a large gain from S22 onward is performed to obtain quick response characteristics, and the engine speed N is set to the target. If the rotation speed is 200 rpm or more higher than N _set and there is a risk of hunting occurring if sudden control is performed, stable control can be obtained by performing control with a small gain from S21 onwards. .

Next, the effects obtained by the embodiment of the present invention will be explained with reference to FIG.

In the conventional system, when control is performed using the gain (1) shown in Fig. 6 to prevent the control from becoming as shown by the broken line in Fig. 8, the result is as shown in Fig. 11a. If the engine is run dry, the state of the pulses given to the throttle actuator at that time will be as shown in Figure c, and therefore the engine speed N will drop significantly as shown by the broken line in Figure A. In some cases, this may even cause the engine to stall.

On the other hand, according to the embodiment of the present invention, the state of the pulse given to the throttle actuator when the engine is run dry is as shown in FIG. 11b, and is therefore indicated by the solid line in FIG. In this way, the engine speed N does not drop even after the engine is idled, and moreover, control as shown by the solid line in FIG. 8 can be obtained at the same time.

By the way, in the above embodiment, a step S17 is provided, and when the target rotation speed N _set is lower than the predetermined rotation speed N _L when the accelerator pedal is first depressed after the engine has started, , that alone enters control using gain (2).

Therefore, even after the engine is stopped, the engine temperature remains
There is no risk of hunting occurring when the engine is restarted and the engine is put into operation when T _w is sufficiently high. That is, if S17 were not present, even if the engine temperature T _w is sufficiently high after restarting the engine, when the accelerator pedal is first operated and then returned to the idle state, S19,
Since the judgment result of S20 is NO, control using the gain (1) will be performed, and after the empty stroke shown in a of Fig. 11, a pulse as shown in c of the figure is given. Hunting occurs as shown by the broken line in a, but according to the above embodiment, after restarting the engine, all the determination results in S17 are NO, so the 11th
Even after emptying as shown in Figure a, the pulses given to the throttle actuator are as shown in Figure b.
Therefore, hunting is effectively prevented from occurring.

Note _that the target rotational speed N _set is given from the engine _temperature T _w by the characteristics shown in FIG _. Set temperature T _WL
Alternatively, it may be determined whether or not it is higher than that.

As explained above, according to the present invention, the gain of the feedback control system for idle rotation speed control is switched depending on the operating state of the engine from the time the engine starts until the predetermined state is reached. Therefore, it is possible to quickly reduce the sudden increase in the idle speed after driving during warm-up, and effectively prevent hunting when the engine is running at high speed, eliminating the shortcomings of the conventional technology and improving responsiveness. It is possible to provide an excellent idle speed control device that operates stably and does not cause engine stalling.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an example of an electronic control system for an engine to which the present invention is applied, Fig. 2 is a schematic diagram of a throttle actuator, Fig. 3 is a block diagram of a control unit, Figs. 5, 6A and 6B, 7 and 8 are characteristic diagrams for explaining the operation, and FIGS. 9 and 10 are flowcharts for explaining the operation of an embodiment of the present invention. , 11th
The figure is a characteristic diagram showing the effects of one embodiment of the present invention. 1... Engine, 7... Throttle actuator, 9... Cooling water temperature sensor, 10... Rotation speed sensor, 11... Idle detection switch, 12...
Control unit, 13... Throttle valve.

Claims (1)

[Scope of Claims] 1. Sensor means for detecting engine speed and engine temperature, actuator means for controlling the return position of the throttle valve, and detecting that the throttle valve is in a state where the opening degree can be controlled by the actuator means. and a switch means for generating an ON signal, and controlling the opening degree of a throttle valve of an internal combustion engine in an idling state according to engine temperature and rotation speed, wherein the signal from the switch means is A storage means for setting at least one of the engine speed and temperature when the engine is first turned off after completion of engine starting as reference data, and a control gain of the idle speed feedback control system by the actuator means as a high gain. comprising: a control means for switching to a two-stage low gain; and a determination means for determining whether a difference between at least one of the engine speed and temperature detected by the sensor means and the reference data is equal to or greater than a predetermined value; The feedback control is performed by switching the control gain to a low gain when the judgment result by the judgment means is positive, and switching the control gain to a high gain when the judgment result is negative. Rotation speed control device. 2. The rotational speed control device according to claim 1, characterized in that the high gain of the feedback control system is configured to be equal to the control gain in steady state. 3. The rotational speed control device according to claim 1, wherein the engine rotational speed set as the reference data is a control target idle rotational speed of the engine.