JPS61192834A - Control device for idling speed of engine - Google Patents

Abstract

PURPOSE:To ensure the safety performance of a vehicle against any unpredictable failure by stopping the operation of a fuel injection valve in such a case that the ratio of the compensation value, which is obtained in compensation for the output of an air flow sensor in response to the output of a temperature sensor, to the output of a throttle valve opening sensor exceeds a predetermined value. CONSTITUTION:In the captioned control device, a control valve 31 operated through an actuator 3 is interposed in a bypass 8 which is arranged in such a manner as making a detour around a throttle valve 4 and the opening of said valve 31 is controlled for setting the idling speed of an engine to a desired value. Further, a fuel injection valve 5 provided in an intake valve 7 is operatively controlled in response to the quantity of fuel which is calculated on the basis of operation parameters supplied frm an air flow sensor 2 and an engine speed sensor 6 and the like. In this case, the output of a compensation circuit 97 for making compensation for the output of the air flow sensor 2 in response to the output of a temperature sensor 15, is compared with the output of a throttle valve opening sensor 10 through a comparison circuit 96, and when the output of the former exceeds the output of the latter, the control of the idling speed of the engine is judged to be in abnormal state, so that the operation of the fuel injection valve 5 is to be stopped.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to an idling speed control device that controls the engine speed during idling to a target value by changing the opening area of a passage that bypasses an intake throttle valve. It is something.

[Conventional technology]

Conventionally, when the engine is idling, it prevents the engine speed from fluctuating due to load changes such as electric load, power steering, air conditioner, etc., and maintains it at a predetermined value.The target speed matches the actual speed. In order to do this, a method is used in which the opening area of the passage is controlled by a valve provided in the passage that bypasses the intake throttle valve. However, in conventional devices, the actual idling speed is compared with the target value, and the control circuit that outputs a drive signal according to the deviation may be malfunctioning, or the actuator or valve that is driven by the control circuit may change the opening area of the bypass passage. If a malfunction such as a failure or a poor connection of the wiring connecting the control circuit and the 7-cut unit occurs when the opening area of the bypass passage is large, the output generated by the engine will be commensurate with the amount of intake air at that time. Therefore, even if the accelerator pedal is fully closed, the vehicle will still be driven by the engine. Particularly when fast idle control is included, the engine output increases as the maximum amount of air passing through the bypass passage increases. As a result, when the accelerator pedal is fully closed, the speed decreases and K<<
However, when operating the brakes, there is a danger that the braking distance will be longer than when it is normal, and the idling speed when stopped will be slightly higher than normal (approximately 800 rpm). 3,000 rpm), which had the disadvantage of giving a sense of anxiety to the driver.

On the other hand, with a conventional device that also uses a fuel injection device, when the accelerator pedal is fully closed (idle switch activated), the engine speed is above a predetermined value (for example, 2000 rpm or above).
The control logic is configured in such a way that the fuel supply is cut off when Because the fuel is not shut off, the engine produces power and remains dangerous.

Figure 4 shows a conventional device. In the figure, 1 is an engine, 2 is an air flow sensor that detects the amount of intake air, and 3
3 is an ISO actuator, such as a stepper motor or a near solenoid, which controls the amount of air that bypasses the throttle valve 4/flows through the exhaust path 8; 31 is a valve driven by this actuator 3; 5 is an intake pipe of the engine L; 7 is a fuel injection valve that injects fuel, 6 is a rotation sensor that detects the engine speed, 15 is a temperature sensor that detects the engine temperature, and 9 is a microcomputer that controls fuel injection and idle speed. 91 is an input circuit that receives a 0N10FF input signal, and 92 converts the next analog value into a digital value corresponding to the intake air amount obtained from, for example, a hot wire type or movable vane type air flow sensor. AD converter to convert,
Reference numeral 93 indicates the fuel injection valve 5 based on the engine operating parameters such as the air 70-sensor 2, rotation sensor 6, and temperature sensor 15.
This is a microcomputer that calculates the drive signal for the ISO actuator 30 and the control amount for the ISO actuator 30, and an output circuit that amplifies the 94.95 wave signal.

Since the fuel injection operation in the above configuration is the same as the conventional one, it will be omitted here, and the idling rotation speed control will be explained. The target value of the idling speed generally varies depending on the load condition such as whether the air conditioner compressor is activated or not, and is set to a higher value when the engine cooling water temperature is low, but in any case, the target speed is determined in advance based on various conditions. The corresponding 几a2>E is stored in the ROM in the microcomputer 93. This target rotation speed and the actual rotation speed obtained from the rotation sensor 6 are compared, and depending on the magnitude relationship, the ISO actuator 3 is driven, the valve 31 is operated, and the amount of air flowing through the bypass path 8 is changed. By doing so, feedback control is performed to a desired rotation speed. Relatively small load fluctuations such as electric power loads are controlled by such rotation speed feedback, and when relatively large loads such as air conditioner loads are applied, feedforward control is used to control the air volume pipe step through bypass path 8. After increasing the speed, it is controlled by rotational speed feedback.

[Problem that the invention seeks to solve]

The above-mentioned better idling speed control is performed by the control device 9,
■There is no problem when the SC actuator 3 is normal, but in the unlikely event that the inside of the control device 9 breaks down or the ISO actuator 3 becomes inoperable, the wiring and connectors that connect the control device 9 and the ISO actuator 3 If there is a defect in the valve 31, the valve 31 may remain nearly fully open and inoperative, resulting in a continued state in which a large amount of air flows through the bypass passage 8. Such inconvenience tlI SO actuator 3
This is particularly likely to occur with DC motors such as step motors, which maintain their current position when not energized.When an inconvenience occurs, a certain amount of engine output is generated, and normal deceleration occurs even when the accelerator pedal is fully closed. Not only is this not done, but even if the brakes are operated, the braking distance is longer than normal, giving the driver a sense of anxiety. As a way to solve this problem, it is possible to detect the abnormality in some way and configure the 7-air sensor 7 by using a dual system of the control device 9, ISO actuator 3, etc., but the device is large and costly. Since this method is impractical for use in automobiles, there is a method that prohibits the driving of the fuel injector 5 when the engine speed increases abnormally (over 2000 rpm) only when the accelerator is fully closed (idle switch activated). There are examples where it is used. If this method is used, inconveniences caused by unexpected engine and output generation can be largely eliminated, but if the idle switch malfunctions or a failure occurs while the accelerator pedal is slightly depressed, it will have no effect and will be completely dangerous. There was a problem that could not be resolved.

This invention was made to solve the above-mentioned problems, and it eliminates unexpected malfunctions caused by idle switch malfunction or when the accelerator pedal is slightly depressed, thereby ensuring vehicle safety and improving driving performance. To obtain an engine idling speed control device that does not give a feeling of anxiety to a person.

[Means for solving problems]

The idling speed control device according to the present invention is configured to open a bypass passage in order to match a target number of revolutions and an actual number of revolutions when the engine is idling, or to match a target value of an opening area of the bypass passage with an actual opening area. An actuator that changes the area, an opening sensor that detects the opening of the intake throttle valve, an air flow sensor that measures the amount of intake air in the engine, a temperature sensor that detects the operating temperature of the engine, an air 70 sensor, and rotation. A fuel injection valve is driven according to the amount of fuel calculated from operating parameters such as a fuel injection valve, a comparison circuit that compares the outputs of the opening sensor and the airflow sensor, and a comparison circuit that compares the output of the airflow sensor with the output of the temperature sensor. It consists of a correction circuit that corrects the

[Effect]

The idling speed control device of the present invention assumes that the idling speed control device is malfunctioning when the correction value of the air flow sensor output by the temperature sensor for the opening sensor output exceeds a predetermined value. This prevents the engine from generating excessive power and ensures safety.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. 1st
In the figure, the same reference numerals as in FIG. 4 indicate the same parts. 10 is an opening sensor that detects the opening of the throttle valve 4; 96 is a comparison circuit that compares the output of the opening sensor lO and the air flow sensor 2; 97 is a correction circuit for correcting the output of the air flow sensor 2 according to the output of the temperature sensor 15. a correction circuit 95a for the fuel injection valve 5;
This is an output circuit that drives the

Next, this invention will be explained in detail. The idling speed control under normal conditions is the same as the conventional one, but ISO
The bypass path may be damaged due to malfunction due to electrical or mechanical failure of the actuator 3, malfunction due to sticking of the valve 31, malfunction of the microcomputer 93, disconnection of the wiring connecting the control device 9 and the ISC actuator 3, poor contact of the connector, etc. If the amount of intake air passing through 8 becomes abnormally large, this can be detected. The characteristics of the opening degree of the throttle valve 4 and the intake air amount obtained from the opening sensor IO are shown in FIG. 2. When the temperature information obtained from the temperature sensor 15 is a high value, that is, in a state after warming up, fast idle is completed. Therefore, the amount of air flowing through the bypass passage 8 is added to QBυ, and the total value with the amount of air flowing through the main intake pipe 7a as the throttle valve opening increases is QT(t).
becomes. A value of QFυ that is larger than the flow rate of QTυ is set as an abnormality determination value. Furthermore, in a state where the temperature information obtained from the temperature sensor 15 is low, the amount of air flowing through the bypass path 8 is a thick value QBI due to the fast idle.
I) and the amount of air that depends on the opening degree of the throttle valve, the total value is QT(8). The value of QF4, which is larger than the flow rate of QT(El), is taken as the abnormality judgment value. When the device is normal, QF does not reach the abnormality judgment value shown by QFυ and Qy(El, but the idling rotation speed When the ISC actuator 3, valve 31, microcomputer 93, etc. related to the control malfunctions or the wiring connecting these fails, the amount of air flowing through the bypass path 8 corresponds to the target value and is significantly larger than the next air amount. As a result, when the amount of air taken into the engine l becomes larger than a predetermined value, the air flow sensor 2 detects the t value and changes the engine temperature as shown in FIG. That is, according to the correction coefficient determined from the fast idle characteristic, the correction circuit 9 of FIG.
The comparison circuit 96 compares and determines the value corrected in step 7 and the opening degree of the throttle valve, and gives a drive stop signal to the output circuit 95 & that drives the fuel injection valve 5 to stop fuel injection. As a result, even if the amount of air flowing through the bypass passage 8 is excessive, the output of the engine 1 is reduced, and the driving force for the vehicle is reduced.

Since it is provided separately from the section that controls the original control of the fail-safe circuit line described above, it operates effectively even in the event of a failure of the microcomputer 93. Furthermore, if the opening sensor IO is already provided as a sensor for correcting the amount of fuel during acceleration or for an automatic transmission, it can be used in combination and there is no need to add a new one, which is economical.

[Effects of the Invention] As described above, according to the present invention, when the correction value by the temperature sensor of the air 70-sensor output with respect to the opening sensor output exceeds a predetermined value, the fuel supply is stopped and the engine output is reduced. Since the structure is simple and inexpensive, the safety of the vehicle is ensured even in the event of an unexpected failure, and the driver does not feel uneasy.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an idling speed control device showing an embodiment of the present invention, Fig. 2 is a characteristic diagram of the throttle valve opening and intake air amount, Fig. 3 is a fast idle characteristic diagram, and Fig. 4 is a diagram of the characteristics of the throttle valve opening and intake air amount. FIG. 2 is a configuration diagram of a conventional rotation speed control device. l...Engine, 2...Air flow sensor, 3...
・ISC actuator, 4... Throttle valve, 5... Fuel injection valve, 8... Bypass path, 9... Control device, l
O...Opening sensor, 15...Temperature sensor, 96...
-Comparison circuit, 97...correction circuit. In addition, in Figure 1, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] In an engine idling speed control device that controls idling speed to a desired value by varying the opening area of a passage that bypasses an intake throttle valve, an engine idling speed control device that controls idling speed to a desired value is provided in order to match target speed and actual speed during idling. ,
or an actuator that changes the opening area of the bypass passage to match the target opening area of the bypass passage with the actual opening area, an opening sensor that detects the opening of the intake throttle valve, and an intake air amount of the engine. a temperature sensor that detects the operating temperature of the engine, a fuel injection valve that is driven in accordance with the amount of fuel calculated from the airflow sensor and operating parameters such as rotation speed, and an opening sensor. A comparison circuit that compares the output of the air flow sensor and a correction circuit that corrects the output of the air flow sensor according to the output of the temperature sensor are provided, and the correction value by the temperature sensor of the air flow sensor output with respect to the output of the opening sensor is a predetermined value. An idling speed control device for an engine, characterized in that when the speed exceeds the idling speed, driving of the fuel injection valve is stopped.