JPS6318015B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an engine rotational speed control method for controlling the rotational speed of an engine during idling based on the outputs of various sensors that detect engine conditions and the like.

``Prior Art'' In order to make the idle rotation speed of the engine maintenance-free, a device has been proposed that performs closed-loop control of the idle rotation speed to a set rotation speed according to the warm-up state of the engine. Alternatively, when moving to load running or vice versa, the air valve that bypasses the throttle valve and controls the amount of auxiliary intake air supplied can be switched between the set opening degree and the fully closed state. ing. That is, control is performed with the same responsiveness even when the actual idle rotational speed is increased or decreased to reach the set rotational speed.

``Problems to be Solved by the Invention'' The above control may cause problems such as when the engine is revved up (racing) or when the engine shifts from a load operating state to an engine braking state with the throttle valve fully closed. A phenomenon occurs in which the engine rotational speed once significantly decreases and then returns to the set rotational speed.

This phenomenon is particularly unfavorable for idle speed control and causes engine stall (so-called engine stall).
There is a great danger that this will occur, and it will also have a negative impact on the driving feeling of the car.

The present invention has been made in view of the above points, and
The purpose is to eliminate the above problems.

"Means and actions for solving the problem" By detecting at least a warm-up state of the engine and comparing the idling speed preset corresponding to this detected state with the current idling speed of the engine. , the amount of auxiliary intake air of the engine is controlled according to the comparison result so that the current idling rotation speed becomes equal to the set rotation speed; The amount of auxiliary intake air is increased depending on the engine rotational speed from time to time, and when the engine decelerates from the above state to the idling operation state, the increased amount of auxiliary intake air is made to depend on the engine rotational speed at that time. The present invention provides a method for controlling engine rotational speed, which includes: gradually decreasing the rotational speed according to a predetermined time function without increasing the rotational speed of the engine.

Embodiment In FIG. 1, an engine 10 is a known four-cycle spark ignition engine, and an air cleaner 11,
Air is inhaled through the air flow meter 12, intake pipe 13, surge tank 14, and each intake branch pipe 15,
Fuel, for example gasoline, is injected and supplied from electromagnetic fuel injection valves 16 provided in each intake branch pipe 15.

The main intake air amount of the engine 10 is regulated by a throttle valve 17 which is arbitrarily operated, while the fuel injection amount is regulated by an electronic fuel control unit 20. The electronic fuel control unit 20 detects the rotational speed measured by the rotational speed sensor 18;
This is a known method that determines the fuel injection amount using the intake air amount measured by the air flow meter 12 as a basic parameter, and also inputs signals from the warm-up sensor 19, etc., and thereby determines the fuel injection amount. Increase or decrease the injection amount.

The air conduits 21, 22 are provided so as to bypass the throttle valve 17, and an air control valve 30 is provided between the two conduits 21, 22. Further, one end of the conduit 21 is connected to an air inlet 23 provided between the throttle valve 17 and the air flow meter 12, and one end of the conduit 22 is connected to an air outlet 24 provided downstream of the throttle valve 17. It is connected.

The air control valve 30 is basically an electromagnetic (linear solenoid) type control valve, and changes the air passage area between the air conduits 21 and 22 by displacement of a plunger 32 that is slidable in a housing 31. .
Normally, the plunger 32 is set by a compression coil spring 33 so that the air passage area is zero.

By energizing the electromagnetic mechanism 34, an electromagnetic attractive force acts between the plunger 32 and the core 35, and the plunger 32 approaches the core 35 depending on the current flow.

In this way, the air control valve 30 is operated by the electromagnetic mechanism 3.
Plunger 32 and core 3 depending on the current flowing through 4.
5 and the air passage area between the air conduits 21 and 22 can be changed continuously, so the air flow rate can be controlled by the current value.

The electromagnetic mechanism 34 is connected to the electronic control unit 6
Driven by 0. This electronic control unit 60 includes a distributor 18 (constituting a rotational speed sensor), a warm-up sensor 19, an electromagnetic clutch 27 that connects a compressor 26 for an air conditioner such as an automobile cooler, and a drive shaft of the engine 10.
An air conditioning switch 28 for turning on and off the air conditioner is connected to the air conditioning switch 28, and receives inputs such as an engine rotational speed signal, a cooling water temperature signal, and an air conditioner on/off signal.

Next, according to Fig. 2, the electronic control unit 6
0 will be explained in detail.

100 is a DA conversion circuit which converts a digital pulse signal synchronized with the engine rotation from the ignition distributor 18 into an analog signal voltage proportional to the engine rotation speed.

200 is a function voltage generation circuit, and warm-up sensor 19
Engine status signals such as the output signal of the engine and the on/off signal of the air conditioning switch 28 are input, and a preprogrammed function voltage is generated depending on the engine warm-up status, the air conditioner status, etc.

300 is an integration circuit, and a function voltage generation circuit 200
The D-A converter circuit 100
Integrate the difference between the output voltage and the output voltage.

Reference numeral 400 is an engine rotational speed signal generating circuit which generates a high voltage as the rotational speed increases, and when the rotational speed decreases, the voltage gradually decreases with a certain time constant.

500 is a voltage-current conversion circuit and an integration circuit 300
This circuit converts the voltage calculated by the engine rotational speed signal generation circuit 400 into a current for driving the electromagnetic mechanism 34.

Next, the operation of the above configuration will be explained.

When the throttle valve 17 is closed and the engine 10 is in idle operation, when the idle rotation speed is lower than the set rotation speed corresponding to the voltage level determined by the function voltage generation circuit 200 of the electronic control unit 60, the capacitor 302, operational amplifier (hereinafter referred to as OP amplifier) 301
A resistor 303 is connected to the inverting input terminal of the integrator consisting of
The potential of the DA converter 100 connected with
It is lower than the output of the function voltage generation circuit 200.

Therefore, the output of the OP amplifier 301 is connected to the resistor 30.
The potential at point a divided by 4,305 is integrated and increases.

This potential is the OP amplifier 501, the resistor 502,
503, 504 and a power transistor 505, the voltage-to-current conversion circuit 500 is connected to the non-inverting input + of the OP amplifier 501.

The resistor 504 is a resistor for detecting the current flowing through the electromagnetic mechanism 34, and the voltage at the terminal C of this resistor 504 is applied to the inverting input of the OP amplifier 501 via the resistor 502. - The current conversion circuit 500 controls the current supplied to the electromagnetic mechanism 34 so that the potential (voltage) at point a and the voltage at terminal C of the resistor 504 are equal.

That is, the current flowing through the electromagnetic mechanism 34 is increased so that the potential at point c increases as the potential at point a increases. As the current flowing through the electromagnetic mechanism 34 increases, the opening degree of the air control valve 30 increases and the amount of air passing through the throttle valve 17 increases, which also activates the air flow meter 12 to increase the amount of fuel injection. , the engine idle speed increases.

[Throttle valve 17 opening degree, engine rotation speed, auxiliary intake air amount (by opening and closing of control valve 30) with respect to the time axis in the conventional control method shown in FIG. 3 below,
Characteristics of engine rotational speed signal and auxiliary intake air amount (at point b in Figure 2) under the control of the present invention ~
The low level in Fig. 3 indicates the throttle fully closed state during idling operation, and the high level after a temporary increase in the opening indicates the opening state during racing or when the car is running. A○ is the conventional characteristic,
B○ indicates improved characteristics according to the present invention, and A○ in FIG.
The part indicates the auxiliary air valve fully closed state, and B○ in Fig. 3
3 shows a state in which a certain amount of auxiliary air is flowed according to the present invention.] When the idle rotation speed increases to the set rotation speed (the set speed state at the beginning of FIG. 3), the output of the DA converter 100 and , the outputs of the functional voltage generation circuit 200 become equal, there is no potential fluctuation in the output of the integrating circuit (point a), the amount of auxiliary air becomes constant, and the engine rotates at the set rotational speed. Conversely, when the engine speed is high, the integral circuit output decreases, and as a result, the voltage-current conversion circuit 500
4, the amount of air is reduced, and the engine rotational speed is lowered.

According to only the above configuration, when the engine is revving (racing) with the throttle valve 17 open, or when the car is running (Fig. 3), the engine rotational speed is higher than the set rotational speed, so the air control valve 30 is As shown by A○ in Figure 3, it is fully closed and the amount of auxiliary air is zero. When the throttle valve is fully closed from this state, the engine rotation speed decreases, and after it falls below the set rotation speed, the auxiliary air amount is controlled to increase, so the engine rotation speed is as shown by A○ in Fig. 3. Once, the rotation speed drops significantly and then returns to the set rotation speed.

This phenomenon adversely affects the risk of engine stall and the driving feeling.

In order to eliminate this problem, an engine rotation speed signal generation circuit 400 is provided. This circuit is composed of diodes 401, 402, resistors 403, 404, and a capacitor 405. As the engine speed increases, the output voltage of the DA converter circuit 100 is input to the capacitor 405, and the voltage at point b ( Third
) in the figure, and the voltage increases the potential at point a through a diode 402 and a resistor 404. Therefore, the auxiliary air amount will be as shown in B○ in Figure 3,
A certain amount of air flows even during racing or under load operation.

Here, when the throttle valve 17 is fully closed, the engine speed will decrease, but the decrease in the amount of auxiliary air will
It is controlled by the potential at point b, which gradually decreases with a time constant determined by a capacitor 405 and a resistor 403. As a result of the above, the engine speed drops smoothly and gradually, and as shown in B○ in Figure 3, the engine speed does not fall below the set speed, and as a result, there is no risk of engine stalling, and the driving feeling is good. becomes.

In the above embodiment, the air control valve is a moving plunger type linear solenoid type solenoid valve whose flow rate changes in proportion to the input current, but it is also possible to use a moving coil type solenoid valve or a current ON/OFF energized valve. A valve may be used to control the air flow rate by time ratio (duty ratio). In this case, the control circuit should of course be changed to control the ON-OFF duty ratio rather than the current value.

Further, in the above embodiment, analog quantity control is performed, but it is also possible to divide the current value into certain bits and perform digital control using a microcomputer.

Effects As described above, in addition to the rotation speed control that controls the amount of auxiliary intake air so that the rotation speed is set according to the operating condition when idling, the present invention further controls the rotation speed when the engine is accelerating and the rotation speed is high. ,
The amount of auxiliary air is increased depending on the rotational speed from time to time.

This has the effect that an optimal amount of auxiliary intake air can be obtained when the vehicle is running and accelerating.

During deceleration when the engine shifts to idling, the amount of auxiliary intake air is gradually reduced as a predetermined time function, regardless of the engine speed.

As a result, even if the rotation speed suddenly drops during deceleration such as during engine racing, the amount of auxiliary intake air is reduced more slowly than the rotation speed reduction rate (a predetermined time function), so the engine does not stall. Also, the driving feeling etc. will not be affected.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an engine speed control system using the present invention, Fig. 2 is an electric circuit diagram showing one embodiment of the present invention, and Fig. 3 is an operating waveform diagram of Fig. 2. 21, 22: Air conduit , 30: Air control valve, 6
0: Electronic control unit, 100: D-A
Conversion circuit, 200: Function voltage generation circuit, 300:
Integration circuit, 400: Engine rotational speed signal generation circuit, 500: Voltage-current conversion circuit.

Claims (1)

[Claims] 1. Detecting at least a warm-up state of the engine,
The idling rotational speed preset corresponding to this detection state is compared with the current idling rotational speed of the engine, and the engine is adjusted so that the current idling rotational speed becomes equal to the set rotational speed according to the comparison result. controlling the amount of auxiliary intake air when the engine is in an accelerating state where the engine speed is higher than idling; increasing the amount of auxiliary intake air depending on the engine speed at the time; An engine rotational speed control method comprising the step of gradually decreasing the increased auxiliary intake air amount according to a predetermined time function without depending on the engine rotational speed at the time when the engine is decelerated to return to an operating state.