JPH04209971A - Idle speed control device for engine - Google Patents

Abstract

PURPOSE:To prevent combustibility from worsening at the time of cold fine low speed running by transferring ignition timing to a delay timing side in the case of an engine temperature lower than a predetermined value during action of a feedback control continuing means which acts to continue a rotational speed feedback when a vehicle is in fine low speed running. CONSTITUTION:A CPU in a control unit 20 for inputting detection signals from an air flow meter 8, idle switch 9, crank angle sensor 10, water temperature sensor 12, etc., calculates ignition timing based on each detection signal to command the ignition timing to an ignition coil 15. The CPU performs rotational speed feedback control for converging an engine speed to a target speed by adjusting the ignition timing at the time of idle operation. Here, a function, in which the CPU acts to continue a rotational speed feedback and also inhibiting the rotational speed feedback control in the case of temperature of an engine 1 lower than a predetermined value even during action of continuing this feedback control, is further given to the CPU.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an engine idle speed control device.

(Prior Art) In recent years, as an engine idle speed control device that has come to be widely used for the purpose of stabilizing the rotation speed during idling operation of an automobile engine, for example, Japanese Patent Application Laid-Open No. 2-8]939 As disclosed in the publication, a bypass passage for intake air is provided to bypass the Ennon throttle valve, and the minimum opening state of the throttle valve is controlled by opening of a solenoid valve provided in the bypass passage. Equipped with feedback control means for converging the actual engine speed detected by the engine speed detection means to a predetermined target idle speed by adjusting the amount of intake air in the idle state (i.e., in the idle state) is well known.

By the way, when converging the engine speed to the target speed by controlling the amount of intake air as in the above-mentioned known example, there is a time difference between the detection of the amount of intake air and the timing when the ennon actually burns. However, there is a risk that a delay may occur when the change in intake air amount or engine speed is reflected.

Therefore, by adjusting the engine's ignition timing (that is, advancing or retarding it), we adopted a foot-to-tail control system that provides engine speed feedback to converge the engine speed to the target speed. In addition to ensuring good response to hack control, attempts have also been made to ensure the rotational stability of the engine during idling.In this case, when the target rotational speed is higher than the actual rotational speed, , the ignition timing is retarded, and vice versa, the ignition timing is advanced (see FIG. 7).

In addition, when the throttle valve is in the minimum opening state (that is, the idle state) and the vehicle is running at a very low speed with the gear of the transmission connected, the drive wheel of the vehicle is Since the engine torque is transmitted, the engine torque transmission acts as an external load on the engine, and the engine speed at that time becomes lower than the idling speed when the vehicle is not running. Therefore, even when driving at very low speeds, the feet...
By continuing to perform the torque control, the decrease in the rotational speed is compensated for and surging of the engine is prevented.

(Problem to be Solved by the Invention) As described above, if the feedback control described above is continued even when the vehicle is running at a very low speed, the combustibility of the engine is inherently poor when the engine temperature has not risen sufficiently. When the ignition timing needs to be advanced, the feedback control causes the ignition timing to be retarded, further worsening combustibility, and as a result, the engine speed further decreases. In the end, there is a possibility that the engine speed cannot be converged to the target speed.

In addition, when the engine is cold, as shown in FIG.
Normally, the target idle speed is set to be lowered as the engine coolant temperature rises, but in this case, if the feedback control is continued while driving at very low speeds, the high target speed In order to try to converge to a certain number, the vehicle speed when driving at very low speeds will gradually increase, causing problems in vehicle speed controllability.

The present invention has been made in view of the above-mentioned points, and aims to prevent sagging when a vehicle is running at very low speeds in warm conditions and to prevent deterioration of combustibility when running at very low speeds in cold conditions. be.

(Means for solving the problem) In the invention of claim 1, as a means for solving the above problem, the engine speed is adjusted to the target speed by adjusting the ignition timing of the engine during idling operation. An engine idle speed control device including a feedback control means for performing rotation speed feedback, comprising: a feedback control continuation means that operates to continue the rotation speed feedback by the feedback control means when the vehicle is running at a very low speed; Even when the control continuation means is in operation, if the engine temperature is lower than a predetermined value, the engine speed is reduced and the ignition timing is shifted to the retarded side. ing.

In the invention of claim 2, as a means for solving the above problem, in the engine idle rotation speed control device according to claim 1, the target rotation speed is higher when the engine cooling water temperature is lower. In addition, the feedback control limiting means operates to prohibit rotation speed feedback when the engine temperature is below a predetermined value even when the feedback control continuation means is in operation. That's what I'm saying.

In the invention of claim 3, as a means for solving the above problem, in the engine idle speed control device according to claim 1 or 2, when the vehicle is running at a very low speed, the throttle valve of the engine is in a fully open state. and the engine and drive system are connected.

(Function) In the invention of claim 1 or 3, the following effects can be obtained by the above means.

That is, when the vehicle is running at a very low speed with the throttle valve in the minimum opening state (i.e., idle state) and the transmission gear is connected (for example, when the engine throttle valve is in the fully closed state and the engine is in the idle state), When the drive system is connected 2
-3), when the engine coolant temperature is higher than a predetermined value, the engine speed feed control is continued by adjusting the ignition timing. This will compensate for the decrease in rotational speed. On the other hand, when the engine coolant temperature is below a predetermined value, the engine speed feedback control is limited, so that the ignition timing is not retarded too much.

In the invention according to claim 2 or 3, the following effects can be obtained by the above means.

In other words, when the vehicle is running at very low speeds in cold conditions (for example, when the engine throttle valve is fully closed and the engine and drive system are connected), the rotation speed is adjusted by adjusting the ignition timing. Since feedback control is prohibited, the ignition timing will not be retarded too much, and if the target rotation speed is set high in cold conditions, the vehicle speed will increase. That will no longer be the case.

(Effects of the Invention) According to the invention of claim 1 or 3, the engine includes a feedback control means that performs rotation speed feedback to converge the engine rotation speed to a target rotation speed by adjusting the ignition timing of the engine during idling operation. In the idle speed control device for an engine, when the vehicle is running at a very low speed (for example, when the throttle valve of the engine is in a fully closed state and the engine and the drive system are in a connected state), the feedback control means Feedback control continuation means that operates to continue and continue the rotation speed feedback, and at least shift the ignition timing to the retarded side if the engine temperature is lower than a predetermined value even when the feedback control continuation means is in operation. A feedback control limiting means that acts to limit rotation speed feedback is attached, and when the vehicle is running at a very low speed and the engine coolant temperature is warmer than a predetermined value, the rotation speed feedback control by adjusting the ignition timing continues. The engine speed feedback control is limited during cold periods when the engine coolant temperature is below a predetermined value, so that the decrease in engine speed during warm and very low speed driving is compensated for, and The ignition timing is no longer too retarded during cold and very low speed driving, and by simply changing the existing idle speed control logic, surging can be prevented during warm and very low speed driving, while cold and very low speed driving can be achieved. This has the excellent effect of preventing deterioration of combustibility at times.

According to the invention of claim 2 or 3, in the engine idle speed control device according to claim I, the target engine speed is set to be higher as the engine cooling water temperature is lower, and the feedback control limiting means is set. Even when the feedback control continuation means is in operation, if the engine temperature is below a predetermined value, the rotation speed feedback is prohibited, and when the vehicle is running at a very low speed in cold conditions ( For example, when the engine throttle valve is fully open when the engine is cold and the engine and drive system are connected, the rotation speed feedback control by adjusting the ignition timing is prohibited1. , the ignition timing will no longer be retarded too much when driving at very low speeds in cold conditions, and even if the target rotation speed is set high during cold conditions, the vehicle speed will no longer become high. This has the excellent effect of ensuring combustion stability during low-speed driving and improving vehicle speed controllability.

(Embodiments) Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

In FIG. 1, an engine 1 is a known four-stroke spark ignition engine mounted on an automobile, and intakes combustion air through an air cleaner (not shown), an intake pipe 2, and a throttle valve 3.

Further, fuel is supplied from a fuel system (not shown) through electromagnetic fuel injection valves 4 provided corresponding to each cylinder. The exhaust gas after combustion is passed through an exhaust manifold 5,
It is supposed to be released into the atmosphere through an exhaust pipe 6 and a catalytic converter.

A hot wire air flow meter 8 for detecting the amount of intake air Qa is attached to the intake pipe 2 upstream of the throttle valve 3, and an idle switch 9 is attached to the intake pipe 2. The air flow meter 8 outputs an analog voltage signal.

A distributor 14 that supplies current to the spark plug 13 of the engine 10 at predetermined intervals is attached with a crank angle sensor 10 that detects the rotational speed of the crankshaft of the engine l. What frequency? (Outputs a bus signal.

Reference numeral 15 denotes an ignition coil that controls voltage application to the ignition plug 13 in response to commands from a control unit 20, which will be described later.

Reference numeral I6 denotes an automobile transmission (in the case of this embodiment, a torque converter type automatic transmission), and a knot lever part 17 of the transmission 16 is provided with shift position detection means for detecting a shift position of shift leno<-18. 11 is attached. The shift position detection means II comprises, for example, an inhibit switch, and outputs a signal when the soft lever 18 is moved to a position other than the neutral or I-king position.

Further, a water temperature sensor 12 for detecting the cooling water temperature Tw is attached to the water shaker/soto 19 of the engine I. The water temperature sensor 12 outputs an analog voltage signal.

Detection signals from the sensors 8 to 11 are input to a control unit 20, and the control unit 20 is a circuit that calculates the ignition timing of the engine based on the detection signals, and controls the ignition timing for the ignition coil 15. It acts like a command.

Next, the control unit 20 will be explained with reference to FIG.

The control unit 20 includes a microprocessor (hereinafter referred to as CPU) 21 that calculates the ignition timing of the engine;
A rotation counter 22 that counts the engine rotation speed Ne based on a signal from the crank angle sensor 11, a digital input port 23, an analog input port 24, and a 1 o'clock storage unit (hereinafter referred to as R) used during program operation.
(hereinafter referred to as AM) 25 and a read-only memory (hereinafter referred to as ROM) 2 that stores programs and various constants, etc.
6, an output port 27, and a common bus 28 for sending and receiving signals to and from the CPU 21.

The digital input port 18 transmits ON/OFF signals from the idle switch 9 and output signals from the software position detection means 11 to the CPU 21.

The analog input port 19 is composed of an analog multiplexer and an AD converter, and has the function of converting the signal from the air flow meter 8 and the signal from the water temperature sensor 12 from analog to digital and reading the converted signal into the CPU 21 .

Power is supplied to the RAM 25 via a power supply circuit 29, and the power supply circuit 29 is directly connected to a battery 30 so that power is always applied thereto. On the other hand, a power supply circuit indicated by reference numeral 3I supplies power to parts other than the RAM 25,
It is connected to a battery 30 via a key switch 32.

The CPU 21 has a feedback control means that performs rotational speed feedback to converge the engine rotational speed to a target rotational speed by adjusting the ignition timing of the engine 1 during idling, and a feedback control means that performs rotational speed feedback to converge the engine rotational speed to a target rotational speed when the vehicle is running at very low speed (e.g. , a feedback control continuation means that acts to continue the rotation speed feedback by the feedback control means when the throttle valve 3 of the engine 1 is in a fully closed state and the engine 1 and the drive system are in a connected state); Even when the feedback control continuation means is in operation, if the temperature of the engine 1 is lower than a predetermined value, the feedback control continuation means also serves as a feedback control restriction means that acts to prohibit rotation speed feedback control.

Hereinafter, with reference to the flowchart shown in FIG.
The functions of PU2] will be explained in detail.

Key switch 32 and starter switch (not shown)
When the engine 1 is started with ONL, in step S1, various signals such as the intake air amount Qa from the air flow meter 8, the engine speed Ne from the crank angle sensor 11, and the cooling water temperature [h from the water temperature sensor 12] are detected. Read or execute 7-1.

Next, in step S2, by CPL;2 +,
The filling efficiency CefT of intake air is calculated. Next, in step S3, a basic ignition advance value A is read from the map shown in FIG. After that, C.
The control by the PU 21 proceeds to step S4, where it is determined whether there is a signal from the idle switch 9 (that is, whether or not it is in an idle state).If the idle switch 9 is not in the ON state, the control proceeds to step S, and then the process proceeds to step S4. An ignition command is output to the ignition coil 15 based on the basic advance angle value A calculated in S3.

On the other hand, in step S, the idle switch 9 is turned on.
If it is determined that the engine is in the state, the control by the CPU 21 proceeds to step S, where an idle advance angle value B is calculated. Since the idle advance value B indicates the maximum value of the torque τ corresponding to the basic advance value A, as seen in the characteristic diagram shown in FIG. 5, the ignition timing adjustment described later cannot be performed. It is given as a lead angle value obtained by subtracting a predetermined value from the basic lead angle value A. When the calculation is completed, the control by CPtJ2+ proceeds to step S8, and the shift position detection means 1
The presence or absence of a signal from 1 is determined. In other words, it is determined whether the shift lever 18 is shifted to a position other than neutral or parking (that is, whether or not it is in a gear-in state).

Here, if it is determined to be in gear (in other words,
(if it is determined that the vehicle is traveling at very low speed), C
Control by the PU21 proceeds to step S, where the engine l
A determination is made as to whether it is in a cold state or a warm state. In the case of this embodiment, the target rotational speed No. in the rotational speed feedback control to be described later is the region where the cooling water temperature Tw is below a predetermined value (for example, 60° C.) (i.e., the cold temperature), as shown in FIG. ), the lower the cooling water temperature TV is, the higher the cooling water temperature is. In addition,
Region where the cooling water temperature Tw exceeds a predetermined value (i.e., warm time)
In this case, the target rotational speed No. is constant. Therefore, in step S7, it is determined whether the cooling water temperature Tw is equal to or lower than a set value (60° C. in this embodiment). In this determination, if it is determined that Tw>60°C (in other words, if it is determined that it is warm time), the rotation speed feedback control (IG-F
/B control) is executed. The rotation speed feedback control is calculated in step S5 so that the deviation value ΔNe between the target rotation speed No and the actual rotation speed Ne of the engine 1 obtained from the crank angle sensor 10 becomes zero, as shown in FIG. This is done by advancing or retarding the idle advance value B. Ignition is then executed in step S9 based on the ignition timing finally determined by the rotation speed feedback control. Therefore, even when the vehicle is running at very low speeds, engine speed feedback control continues during warm operation in the same way as during idling in neutral or parked conditions, and the engine speed does not decrease during warm and very low speeds. This means that surging can be prevented by compensation.

On the other hand, in step S7, if it is determined to be T1560°C (in other words, if it is determined that it is cold time),
The control based on CPt, '2+ proceeds to step S without performing the rotation speed feedback control described above, and ignition is executed based on the basic advance value A calculated in step S3. Therefore, when the vehicle is running at very low speeds, rotation speed feedback control is prohibited during cold operation, and the ignition timing is not retarded too much during cold and very low speed driving. This makes it possible to prevent deterioration of combustibility at times. In addition, when engine speed feedback control is performed during cold operation, the vehicle speed may increase due to the engine speed Ne converging to the high target speed No (see Figure 6). It will disappear. Note that during cold operation, the charging efficiency is high and the combustion time is long, so surging is less likely to occur when running at very low speeds, so there is no problem.

If it is determined in step S6 that the gear is not in gear, the vehicle is in idle operation in a stopped state, so control by the CPU 2+ proceeds to step S8, where rotational speed feedback control is executed.

In the above embodiment, the rotation speed feedback control is prohibited during cold and very low speed driving, but during cold operation, the rotation speed feedback control in the direction of advancing the ignition timing is prohibited. In some cases, only the rotational speed feedback control in the direction of retarding the ignition timing is prohibited because it does not become a factor that deteriorates the combustibility of the engine.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram of a device for explaining the present invention in detail, FIG. 2 is a block diagram of a control circuit in the device shown in FIG. 1, and FIG. 3 is a block diagram of a microprocessor shown in FIG. 2. Fig. 4 is a flowchart for explaining the functions of Fig. 3, a basic advance angle value map used in the control shown in Fig.
The figure is a characteristic diagram showing the relationship between ignition timing and torque, Figure 6 is a characteristic diagram showing the relationship between cooling water temperature and target rotation speed, and Figure 7 is a characteristic diagram showing the relationship between cooling water temperature and target rotation speed. Figure 7 is a characteristic diagram showing the relationship between rotation speed feedback control and ignition timing adjustment amount. FIG. l... Engine 3... Throttle valve 8... Air flow meter 9... Idle switch 10... Crank angle sensor 11... Shift position detection means 12. ...Water temperature sensor 13...Ignition plug 15...Ignition coil 20...Control unit Applicant Mazda Corporation

Claims (1)

[Scope of Claims] 1. Engine idle speed control device equipped with feedback control means that performs speed feedback to converge the engine speed to a target speed by adjusting the ignition timing of the engine during idling operation. a feedback control continuation means that acts to continue the rotation speed feedback by the feedback control means when the vehicle is running at a very low speed, and an engine temperature that is lower than a predetermined value even when the feedback control continuation means is in operation. 1. An idle speed control device for an engine, comprising feedback control limiting means that acts to limit rotation speed feedback that shifts ignition timing to a retarded side in some cases. 2. The target rotation speed is set to be higher when the engine cooling water temperature is lower, and the feedback control limiting means is configured to maintain the engine temperature at a predetermined value even when the feedback control continuation means is in operation. 2. The engine idle speed control device according to claim 1, wherein the engine idle speed control device operates to inhibit the rotation speed feedback when the engine speed is below. 3. Idle rotation of the engine according to claim 1 or 2, wherein the throttle valve of the engine is in a fully closed state and the engine and the drive system are in a connected state when the vehicle is running at a very low speed. Number control device.