JPS5841236A - Apparatus for controlling idling speed of engine - Google Patents

Abstract

PURPOSE:To stabilize starting performance of an engine, by increasing the opening of a throttle valve until an aimed idling speed is obtained, through detection of the fact that a prescribed time period is passed after a starter switch is turned OFF or that particular conditions of engine operation are safisfied in the above-titled apparatus. CONSTITUTION:With stopping of an engine after driving a vehicle, a second timer 33 in a circuit 29 for detecting the operational conditions is turned ON when a first timer 32 is turned OFF after passing of a time T1 after the engine key is turned OFF, and the second timer 33 is turned OFF after passing of a time T2. Therefore, by the output of the circuit 29, a voltage generator 34 produces a voltage for driving a DC motor 8 to its maximum position, and the voltage is applied to the motor 8 via an adder circuit 28, whereby a throttle 7 is opened. With starting of idling operation, a control circuit 18 applies an output to terminals P1, P2 and drives the DC motor 8 by making a judgement whether the deviation between the voltage corresponding to an aimed idling speed produced by a reference voltage generating circuit 20 and the voltage corresponding to the actual idling speed is negative or positive. On the basis of this judgement, the throttle valve is opened or closed to attain the desired idling speed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an engine idle speed control device, and more particularly to an engine idle speed control device that improves startability.

In general, idle rotation system of automobiles! The l-min directing system uses electronic feedback control to keep the engine speed during idling to a low speed of around 600 to 700 rpm, thereby stabilizing combustibility and improving fuel efficiency. (Japanese Unexamined Patent Publication No. 55-69745).

The target idle speed for this engine idle speed control device is adjusted depending on the water temperature, cooler, electrical load, etc., and when the temperature is low, such as during a cold start, the engine combustion speed increases. This is because stable idling cannot be achieved unless the engine speed exceeds a certain level due to the nature of the engine, and when the load is large, this causes fluctuations in the idling speed.

By the way, in conventional idle speed control devices, when faced with low temperatures, the target idle speed is set to a low value, that is, the throttle opening degree is increased to a considerably large point in order to increase the amount of air-fuel mixture. There is a problem in that the battery voltage is low and therefore the response is poor even if it is desired to bring the throttle opening to the target value quickly.

Therefore, in order to solve this problem, the conventional idle speed control 19 & direct is based on the idea that the throttle valve only needs to be opened a predetermined amount when starting the engine, so when the ignition key is off, the throttle valve is pre-opened. There are known ones that are kept open until the end. However, if the throttle valve is opened immediately after the engine ignition key is turned off, a problem arises in that dieseling or afterburn occurs. Dieseling means that even if the engine is turned off,
In other words, even if the spark plug is turned off, the temperature in the combustion chamber remains high for a while, so if the throttle valve is left open, the intake air-fuel mixture will self-ignite and the engine will continue to rotate. Also, afterburn refers to the fact that the throttle valve is open even when the engine is turned off, so that the fuel layered in the slow boat (slow system fuel supply passage) or diffuser pipe remains in the exhaust system. This invention was made in view of these conventional problems. By opening the throttle valve to F9Tf1mff when the switch is turned off and other engine conditions are satisfied, dieseling or afterburn is avoided and engine startability is improved during cold starts. It is an object of the present invention to provide an engine idle rotation control device that allows smooth idle operation to be performed immediately.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an engine to which this invention is applied.

In the figure, 1 is the engine, 2 is the piston, 3 is the intake passage, 4 is the exhaust passage, 3- is the intake valve, 4a is the exhaust valve, and 5 is the intake passage 3. 6 is a carburetor provided in the intake passage 3 below the air cleaner 5; 6a is provided in this carburetor 6;
! A fuel nozzle 7 that opens into the IfR 13 is provided slightly below the carburetor 6.

A throttle valve 8 controls the intake air level supplied to the engine 1, a DC motor 8 serves as an electric actuator that closes the throttle valve 7, and a water temperature 9 detects the temperature of the cooling water 10 of the engine 1. sensor, 11
A converts the detection signal of this water temperature sensor 9 into A/D.
12 is a digital water temperature signal that is the output of the A/D display device 11, 13 is a distributor used as a rotary distributor in the factory, 14 is a rotation detection signal from this distributor 13, 15 is a cooler switch, 16 is a cooler switch signal from the cooler switch 15, and 17 is an idle switch signal that indicates whether or not the engine continuous operation state is an idling operation state in response to opening of the throttle valve 7.

18 is the water temperature signal 12. Cooler switch polarization code 1
6. Detect the difference between the target idle speed determined by the idle switch signal 17 etc. and the actual idle speed obtained from the rotation detection signal 14, and output the motor drive signal 19 according to this difference. It is a control circuit.

111!2ei again! 12, 14, 16, 17 are the same signals as in FIG. 1, and in the control circuit 18, 20 is the idle switch signal 17. 21 is a waveform shaping circuit that generates a reference voltage corresponding to the target idle speed from the water temperature signal 12 and the cooler switch 16; 21 is a waveform shaping circuit that forms the rotational speed signal 14 into an hourglass shape; is an h-v friendly device that converts an input frequency signal into a voltage signal, 2
3 is a difference 1j4) J amplifier that amplifies the difference between the output of the reference voltage generation circuit 20 and the output of the F-V converter 22; 24 is a reference level setting circuit that sets a reference level that is a dead zone;
5 is a comparator that compares the reference level with the output level of the differential amplifier 23; 26 is a positive/negative discrimination circuit that determines whether the output of the axle amplifier 22 is positive or negative; and 27 is the comparator. Pl, P2, and P3 are the output terminals of the main control circuit 18, as well as the drive circuit 4M of the numeral motor 8. Pl is a drive signal terminal for raising the throttle (opening), P2 is a drive signal terminal for lowering (closing) the throttle, and P3 is a ground terminal. 28 is a terminal P1 of the cooking circuit 27
This is an addition circuit that adds the output polarization of the voltage generator 634 and the output of the voltage generator 634 described below. Furthermore, 29 is an operating condition detection circuit that detects that the operating condition of the throttle valve 11 is satisfied after a predetermined period of time from the time when the ignition switch is turned off, and outputs a detection signal. In 29, 3o is a battery, 31 is an ignition switch, 32 is a first timer that is turned on only for T1 time after the switch 31 is turned off, 33 is turned on 1'1 hour after the switch 31 is turned off, and 12 This is a second timer that turns off when the time elapses. The output of the second timer 33, that is, the operating condition detection circuit 2
This is a voltage generator serving as a drive circuit that receives the output of the DC motor 8 and generates a voltage for moving the DC motor 8 to the maximum position of the idle rotation side electric actuator.

In addition, Fig. 3 shows the characteristics of the target idle speed with respect to the water temperature in this device, and A shows the characteristics of the cooler on state.
B shows the characteristics of the cooler off state. According to the figure, when the water temperature is low, the target idle speed is low to reduce combustibility, and when the cooler is on, the electrical load is large, so the target idle speed is still low.

Further, FIG. 4 is an explanatory diagram of the operation of the device of this embodiment, and C(
a) shows the on/off state of the ignition switch, figure (
bl is the on/off state of the starter switch, Figure (C) is the engine operating state, and Figure (dl is the operating condition detection circuit 29).
The on/off state of the output, Figure (el indicates the throttle valve opening, and the solid line in Figure (el) indicates the characteristics of the device of the present invention,
The broken line indicates the characteristic of Conventional Example No. 1, in which the throttle valve is not opened at all when the engine is stopped, and the dashed line represents the characteristic of Conventional Example No. 2, in which the throttle valve is opened immediately (to a predetermined opening degree) when the engine is stopped.

Next, the operation will be explained.

First of all, if you turn on the ignition switch and then immediately turn on the starter switch while the engine is stopped as shown at the left end of Figure 4, the engine will either crank and idle continuously, or the engine will stop. Since the throttle valve 7 is set to the predetermined opening S1, that is, the maximum position of the DC motor 8, which is the electric actuator for idle speed control, '#14 Figure t
As shown by the solid line el, the opening degree of the throttle valve 7 becomes slightly smaller when entering the idle operating range from cranking, and is then automatically controlled to reach the target idle speed. Therefore, the engine startability in this device is greatly improved by increasing the throttle opening from SO as shown by the broken line in Fig. 4 (tel) (compared to the conventional example 1) (Fig. ).In the idling operating range, when it is detected from the idle switch signal 17i that the idling operating range is present, the reference voltage generating circuit 19 in the control circuit 18 obtains the water temperature signal 12 and the cooler switch number 16. The F-V converter 22 generates a voltage corresponding to the actual idle rotation speed from the waveform shaper 21 that shapes the rotation speed signal 14 by the waveform shaping circuit 21. .

Then, left motion amplification! ! 123 calculates the difference in the above-mentioned direction voltage, and 25 compares the output with a reference level indicating the dead zone set by the reference level setting device 24, and when the absolute value is greater than the reference level, the target rotation speed and the actual rotation speed are compared. Outputs a voltage corresponding to the difference in rotation speed. On the other hand, the positive/negative discrimination circuit 26 has a difference of 11
It determines whether the output of the 1711 width converter 23 is positive or negative, and sends a 1 or 0 signal to the logic circuit 27 according to the result.

- The logic circuit 27 outputs a signal in which the sign determined by the positive/negative discrimination circuit 26 is added to the sign indicating the output of the comparator 25, and this signal is determined when the ignition switch 31 is on, that is, when the ignition switch is in the normal idling state. In the operating state, if the signal is positive, the negative 1c! If the number is ', the terminal P2f is output, which drives the motor 8 to open or close the throttle valve 7, thereby setting the idle speed or the target idle speed depending on the load condition. (B-to-8 in Figure 1!84 (e)).

After continuous idling, when normal driving begins, the throttle opening changes depending on the depression of the accelerator pedal, or by human operation (Figure 84 (e)).
CSW*>. Then, when the continuous running state ends and the engine stops after some idling operation, the operating condition detection circuit 29 first detects the first timer 3.
2 is on only for 11 hours after the ignition switch 31 is turned off, and the second timer 33 is the same as the first timer 32.
The output from the detection circuit 29 becomes as shown in FIG. 4(d) because it turns on when the key turns off after T1 hours have elapsed after the key is turned off, and turns off when another 1 to 2 hours have passed since the key was turned off. Therefore, based on the output of the operating condition detection circuit 29, the voltage generator 34 generates a voltage for driving the DC motor 8 to the maximum position, and this voltage is applied to the DC motor 8 via the addition circuit 28, thereby controlling the throttle. The valve 7 is opened to several positions of the DC motor 8.In this way, in this system, the throttle valve 7 is opened immediately when the engine is stopped, unlike in the case of the second conventional example shown by the dashed line in Fig. 4(e). Since it does not open, it does not cause dieseling or afterburn (4th N (e)
l's Dsi light). Furthermore, since the throttle valve is opened as described above, the startability at the next start can be greatly improved.

In the above embodiment, the operating condition detection circuit 29 detects the elapse of a predetermined period of time after the ignition switch is turned off as a condition for opening the throttle valve. is not limited to this. For example, when the ignition switch is turned off from the on state, and the engine rotational speed falls below a predetermined number of rotations, or when the engine intake negative pressure is set to a predetermined value. The following conditions may be used as operating conditions, or these conditions may be combined. An example of when it would be inappropriate to set the conditions regarding the engine speed is when the vehicle is coasting downhill with the key switch turned off. In other words, when the engine speed falls below the predetermined speed in such driving conditions, there is no longer any risk of dieseling or afterburn, so even if the throttle valve is opened to 81'r, there will be no loss of speed. Without,
This makes it possible to improve startability at the next start. Note that the electric actuator is not limited to a l1il flow motor, but can also be used with a proportional solenoid valve or a stepper motor.Also, when the engine is stopped, the throttle is opened once, and the actuator operates at its maximum position. It is also possible to lay grass at any one time.

As described above, according to the present invention, the throttle valve is opened to a predetermined opening degree when the engine has established a specific operating condition after the ignition switch is turned off, and the engine idle speed control is controlled directly. Therefore, without causing dieseling or afterburn,
This has the effect of significantly improving the startability of the engine.

[Brief explanation of the drawing]

The first problem is idle rotation control according to an embodiment of the present invention.
2 is a cross-sectional view of the engine that is operated by k@L, FIG. 2 is the electric circuit M6 diagram of the above embodiment, FIG. 3 is a characteristic diagram of the target idle speed of the above embodiment device versus water temperature, and FIG. 4 is the above diagram. FIG. 3 is an explanatory diagram of the operation of the embodiment device. 13... Distributor (rotation detection: #) 7...
- Throttle valve 8... DC motor (electric actuator) 18... Control circuit 29... Operating condition detection circuit 34... Voltage generator (drive circuit) 31
...Ignition switch patent applicant Toyo Kogyo Co., Ltd. agent Patent attorney Ken Hayase - Figure 1

Claims (2)

[Claims] (1) A rotation detector that detects engine rotation speed,
A throttle valve that controls the amount of intake air supplied to the engine in order to adjust the engine speed, a 111 actuator that opens and closes the throttle valve, and a target idle speed that is set according to the operating state of the engine. a control circuit that detects a difference between the actual idle rotation speed detected by the rotation detector and outputs a drive signal to the electric actuator so that the actual idle rotation speed or the target idle rotation speed is achieved according to the difference; An operating condition detection circuit detects that the ignition switch is turned off and that specific engine conditions are satisfied and outputs a signal to detection 4, and receives the output of this operating condition detection circuit and operates the electric actuator. An idle rotation system for an engine, characterized by comprising a drive circuit for opening the throttle valve to a predetermined opening degree. (2) A feature characterized in that the specific engine condition is at least one of the following three conditions.
An engine idle rotation control device according to claim 1. ■ The specified time has elapsed after the ignition switch was turned off ■ The engine rotation speed is below the specified kB ■ The negative pressure in the engine intake pipe is below the specified value