JPH0536623B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a control device for an idle speed control valve that controls the amount of bypass air to an engine, and in particular, to a control device for an idle speed control valve that controls the amount of bypass air to an engine, and in particular, to a control device for controlling an idle speed control valve that controls the amount of air bypassed to an engine. It is an attempt to avoid this.

Conventional technology and problems The idle speed control valve (hereinafter referred to as the ISC valve), which bypasses the throttle valve and controls the amount of air taken into the engine, opens the valve depending on the magnitude of the current flowing through the coil. Electromagnetic types that change the degree are common. In addition, from the standpoint of safety, a normally-closed type (normally closed type), which is closed forward by a spring force or the like when the power is cut off, is convenient.

The specific structure of this type of ICS valve varies, but in the case of a linear solenoid type, the current flowing through the coil for generating magnetic flux is continued at a constant cycle, and the valve changes in proportion to the average value of the current. Opening degree can be controlled. For example, if one end of the above coil is connected to the +B (power supply) line, the other end
By connecting the coil to the ISC valve drive circuit and continuously grounding the other end of the coil in the drive circuit, the excitation current can be caused to flow continuously. By keeping this continuation cycle constant and varying the energization period, the average value of the current flowing through the coil can be controlled according to the energization period. This is a drive method called duty control, and the drive pulses necessary for control are generated on the ISC valve drive circuit side.

Usually, the ISC valve and its drive circuit are separated, so they are connected by a drive cable. Therefore, if a part of the cable comes into contact with the vehicle body and is grounded, the ISC will be activated regardless of drive circuit control.
Current flows continuously through the valve coil. Third
The figure is this explanatory diagram, +B is the power supply, L is the ISC valve coil, and BDY is the vehicle body. The route shown by the broken line shows the short to the vehicle body BDY, and at this time, the coil L
Current I flows continuously through. Since this current I has a value corresponding to 100% duty in normal duty control, the opening degree of the ISC valve becomes maximum (fully open), causing an abnormal increase in engine speed and the risk of a rear-end collision.

Purpose of the Invention The present invention has a dual ISC control system so as to cope with the above-mentioned short circuit accident, and
This is intended to improve safety by preventing the valve from fully opening, and to maintain a constant idling state by ensuring a constant opening to prevent the valve from fully closing.

Composition of the Invention The present invention is a control device for a normally closed idle speed control valve that controls the flow rate of air taken into an engine by bypassing a throttle valve by controlling the valve opening depending on the magnetic flux generated in a coil. , a normal control system that data-controls the average value of the current flowing through the coil with a pulse width on the ground side of the current-carrying path to the coil; a current detection unit that detects the average value of the current flowing through the coil; an emergency control system that controls the average value of the current flowing through the coil to a predetermined value on the power supply side of the current-carrying path when the average value of the current flowing through the coil is determined to be an abnormal value by the section; The present invention is characterized in that it is equipped with two control systems, and only the duty control is performed by the normal control system at all times.This will be explained in detail below with reference to the illustrated embodiment.

Embodiment of the Invention FIG. 1 is a block diagram showing an embodiment of the present invention.
2 is a throttle valve that changes the amount of air taken into the engine intake manifold from the air cleaner in conjunction with the accelerator pedal.
3 is the aforementioned ISC valve that controls the amount of bypass air that bypasses the throttle valve, and 3 is an engine control unit (ECU). ECU3 is a central processing unit (CPU) that has various engine control programs.
31, a data input section 32 that takes in data such as engine (E/G) rotation speed, idle SW (switch), E/G cooling water temperature, etc., and an A/D converter that converts some analog inputs into digital values. 33,
It includes a memory 34 such as a RAM, a data output section 35 that outputs various control signals, and a current detection section 36 particularly for controlling the ISC valve 2.

In the present invention, two control outputs A and B are used for controlling the ISC valve 2. The first output A is for normal duty control, and the duty of a constant period pulse train is
It changes, for example, from 0% to 100% under the control of the CPU 31. Although it depends on the characteristics of the ISC valve 2, if it is a linear solenoid type, 0% of duty corresponds to fully closed and 100% of duty corresponds to fully open, and the valve opening degree in between can be linearly controlled by an arbitrary duty. This output A is passed through drive line 4.
It is transmitted to the ground side of the coil of ISC valve 2 (L in Figure 3). On the other hand, the power source side of the coil is connected to a power source +B through a power line 5, but in this example, a power supply control circuit 6 is interposed in the middle. This control circuit 6 is composed of, for example, a transistor, and its ON/OFF state is controlled by the second output B. This output B keeps the transistor of the limiting circuit 6 on at all times when the ISC valve 2 is in a state where it can be controlled by the first output A. However, when the ISC valve 2 becomes uncontrollable with the first output A, the transistor is turned on and off with a constant duty, and the valve opening of the ISC valve 2 is maintained at a constant value in place of the output A.

Whether or not the ISC valve 2 can be controlled by the first output A is determined using the current detection unit 36. This current detection unit 36 detects the average value of the current that flows through the ISC valve 2 and further flows through the line 4 to the ground on the ECU 3 side.
It is monitored as a voltage value generated across a minute resistance.
This function is originally intended to feed back the result of duty control, but in this example, this function is utilized to determine whether or not control by output A is impossible. In other words, as shown in Fig. 3, if line 4 contacts the vehicle body BDY etc. midway and is grounded, even if the duty of output A is changed, the detected current (iSC current and ) does not change. That is, it remains approximately 0. However, this will not happen unless the duty is 0%, so the CPU 31 determines whether control by output A is impossible based on the current value of this iSC (several tens of mA or more during control), that is, whether a short accident has occurred. Determine. If it is determined that a shortcut accident has occurred, a constant duty output is generated at output B to maintain the ISC valve 2 at a constant valve opening. This valve opening degree is, of course, smaller than full opening. However, it should be made larger than fully closed so that the idle state can be maintained. FIG. 2 is a flowchart including the above operations.

Incidentally, a shoot accident may also occur on the power line 5 side. This can be discovered by turning off the transistor of the circuit 6 by setting the output B to L (low) immediately after resetting the system, and detecting whether or not current flows through the ISC valve 2 at that time.

Effects of the Invention As described above, according to the present invention, the control system for the idle speed control valve is duplicated, so even if the normal system becomes uncontrollable due to a short accident, the emergency system can control the valve opening. This has the advantage of being able to maintain the value at a safe and useful value and detecting the valve shot.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing one embodiment of the present invention, and FIG.
The figure is a flowchart, and Figure 3 is an explanatory diagram of the shot accident. In the figure, 1 is the throttle valve, 2 is the idle speed control valve, L is its coil, 3 is the engine control unit, 31 is the CPU, 35 is the data output section, 36 is the current detection section, 4 is the drive line, 5 6 is a power supply line, and 6 is a power supply limiting circuit.

Claims (1)

[Claims] 1 In a normally closed idle speed control valve control device that controls the flow rate of air taken into the engine by bypassing the throttle valve by the valve opening depending on the magnetic flux generated in the coil, A normal control system that duty-controls the average value of the current flowing through the coil on the ground side of the electric circuit using a pulse width, a current detection section that detects the average value of the current flowing through the coil, and a current detection section that detects the average value of the current flowing through the coil; and an emergency control system that controls the average value of the current flowing through the coil to a predetermined value on the power supply side of the energization path when the average value of the current flowing through the coil is determined to be an abnormal value, A control device for an idle rotation speed control valve, characterized in that only duty control is performed by the normal control system at all times.