JPS60215174A - Control device for idle rotational speed control valve - Google Patents

Abstract

PURPOSE:To hold the valve opening degree of an idle rotational speed control valve (ISC) at a safe and effective value by means of an emergency system even if the control of a normal system is in effective due to a short-circuiting accident, by providing a dual control system for the idle rotational speed control valve. CONSTITUTION:A current detecting section 38 monitors the averaged value of current running through an ISC valve 2 and a wire 4 and grounding on the ECU3 side, as a voltage value which is generated through a very low resistance. When the wire 4 is grounded intermediately thereof, the detection current value of the current detecting section 36 will not vary even though the duty ratio of an output A is changed. A CPU31 determines whether the control of the output A is effective or not in accordance with the detection current value. When it is determined that the control is ineffective, an output B is made to issue a predetermined duty output, and the ISC valve 2 is maintained at a predetermined valve opening degree in order to hold an idle condition.

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 controlling an idle speed control valve that controls the amount of bypass air to an engine, and in particular, to prevent the valve from becoming uncontrollable due to a short-circuit accident in the drive line. It is an attempt to avoid this.

Prior Art and Problems The idle speed control bypasses the throttle valve and controls the amount of air taken into the engine. An electromagnetic type that changes the opening degree is common. In addition, from the standpoint of safety, a normally closed type (normally closed type), which is fully opened by a spring force or the like when the power is cut off, is convenient.

The specific structure of this type of IC3 valve varies, but in the linear solenoid type, the current flowing through the coil for generating magnetic flux is interrupted at regular intervals, so that the current is proportional to the average value of the current. The valve opening degree can be controlled by

For example, if one end of the above coil is connected to the 10B (power supply) line, the other end is connected to the ISO valve drive circuit, and the excitation current is intermittently applied by intermittently grounding the other end of the coil in the drive circuit. It can flow. By keeping this intermittent 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 driving method called duty control, and the driving pulses necessary for control are generated on the rsc valve driving circuit side.

Since the ISC valve and its drive circuit are usually separated, they are connected by a drive cable. Therefore, if a portion of the cable comes into contact with the vehicle body and is grounded, current will continue to flow through the ISO valve coil regardless of the control of the drive circuit. Figure 3 is an explanatory diagram of this, where 10B is the power supply,
L is the ISO valve coil, and BDY is the vehicle body. The path shown by the broken line indicates a short circuit to the vehicle body BDY, and at this time, the current I continuously flows through the coil. In normal duty control, this current I has a value corresponding to 100% duty, so the opening degree of the ISO valve becomes maximum (fully open).
The engine speed increases abnormally, creating the risk of a rear-end collision.

Purpose of the Invention The present invention has been developed to meet ISO
The valve control system has been doubled to improve safety by preventing the ISC valve from fully opening due to uncontrollable conditions, and to maintain a constant opening to prevent the ISC valve from fully closing. This is what we are trying to do.

Composition of the Invention The present invention provides 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 duty-controls the average value of the current flowing through the coil with a pulse width on the power supply side or the ground side of the energization path for the coil, and a current detection unit 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 opposite side of the energization path when the average value of the current flowing through the coil is determined to be an abnormal value by the detection unit. The present invention is characterized in that only duty control is performed by the normal control system at all times, and this will be explained in detail below with reference to the illustrated embodiment.

Embodiment of the Invention FIG. 1 is a configuration diagram showing an embodiment of the present invention, in which 1 is a throttle valve that changes the amount of air AR taken in from the air cleaner to the intake manifold of the engine in conjunction with the accelerator pedal; 2; 3 is the aforementioned SC 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 (C) that has various engine control programs.
PU) 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 that converts some analog inputs into digital values. Converter 33, memory 3 such as R'AM
4. It is equipped with a data output section 35 etc. that outputs various control signals, and has a current detection section 36 especially for use with ISOS2O2.

In the present invention, two control outputs A and B are provided for ISOS2O2.
Use. The first output A is for normal duty control,
The duty of the pulse train of a constant period varies, for example, in the range of 0% to 100% under the control of the CPU 31. Although it depends on the ISOS2O2 characteristics, if it is a linear solenoid type, 0% of the duty corresponds to fully closed and 100% of the duty corresponds to fully open, and the valve opening degree between them can be linearly controlled by an arbitrary duty. This output A is transmitted through the drive line 4 to the ground side of the ISOS2O2 file (shown in the box in FIG. 3). On the other hand, the power source side of the coil is connected to the power supply element B through the power line 5, but in this example, a power supply limiting circuit 6 is interposed on the way. This control circuit 6 is composed of, for example, a transistor, and its ON/OFF state is controlled by the second output B. When this output B can be controlled by the first output A outside the ISCSC, the transistor of the limiting circuit 6 is always turned on. However, ISOS2O2
When the output A becomes uncontrollable, the transistor is turned on and off at a constant duty, and the opening degree of ISOS2O2 is maintained at a constant value in place of the output A.

It is determined using the current detection unit 36 whether control is possible using the output A of the ISOS2O21. This current detection section 36 is
The average value of the current that flows through the SC valve 2 and further through the line 4 to the ground on the EC0g side is monitored as the voltage value generated in the minute resistance. This function is originally intended for feedbanking the result of duty control, but in this example, this function is utilized to determine whether control by output A is impossible. In other words, as shown in FIG. 3, if the line 4 contacts the vehicle body BD'Y or the like midway and is grounded, even if the duty of the output A is changed, the current detection unit 36
The detection current at (referred to as iSC current) does not change. In other words, it remains at 0.

However, this will not happen unless the duty is 0%, so the CPU 31 determines whether control by output A is impossible, that is, whether a short-circuit accident has occurred or not from the value of this iSC current (several tens of mA or more during control). judge. If it is determined that a short-circuit accident has occurred (2), a constant duty output is generated at output B, and the valve opening is maintained at a constant ISOS2O2. 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 short circuit accident may also occur on the power line 5 side. Immediately after the system starts, output B is set to L (low) to turn off the transistor of circuit 6, and at that time, ISOS
This can be discovered by detecting whether or not the 2O2 flow is flowing.

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 regular system becomes uncontrollable due to a short-circuit accident, the valve opening can be controlled by the emergency system. It has the advantage of being able to maintain a safe and useful value and detecting short circuits in the valve.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a flowchart thereof, and FIG. 3 is an explanatory diagram of a short-circuit accident. In the figure, 1 is the throttle valve, 2 is the idle speed control valve, L is its coil, 3 is the engine i1i+1 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. Applicant: Minoru Aoyagi, Patent Attorney, Fujitsu Ten Co., Ltd. Figure 1, 10B, Figure 2

Claims (1)

[Claims] In a control device for a normally closed idle speed control valve 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, an energizing path for the coil is controlled. A normal control system that duty-controls the average value of the current flowing through the coil on the power supply side or the earth side, 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 a current detection section that detects the average value of the current flowing through the coil. An emergency control system is provided which controls the average value of the current flowing through the coil to a predetermined value on the opposite side of the energizing path when the average value of the flowing current is determined to be an abnormal value and is cut off. A control device for an idle speed control valve, characterized in that it performs only duty control using a normal control system.