JPH04259642A - Fail-safe device for idling control valve - Google Patents

Abstract

PURPOSE:To prevent engine stall when a mechanical failure is generated in an idling control valve furnished in a bypass to detour a throttle valve, and to prevent hunting of the control system by suppressing rise of the engine revolving speed when the failure is corrected. CONSTITUTION:A failure occurrence signal is emitted by a failure sensing means M1 when the engine operating state meets the failure generating conditions of an idling control valve, and with this signal a safe signal generating means M2 emits No.1 safe signal and No.2 safe signal. The drive of the idling control valve is stopped with the No.1 safe signal, and rise of the engine revolving speed when the failure is corrected to provide prevention of the control system from hunting. The No.2 safe signal puts an aux. valve in open state, wherein the aux. valve is installed in parallel with the idling control valve, and thereby air supply to the engine is ensured to preclude occurrence of engine stall. Further an alarm is issued by an alarming means M3 to inform about occurrence of failure.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fail-safe device for an idle control valve that ensures safety when an abnormality occurs in the idle control valve.

0002

[Prior Art] Generally, in engine idle speed control, the amount of air in a bypass passage that bypasses a throttle valve installed in the intake passage is adjusted by an idle control valve to bring the engine speed to a target speed. The bypass air method uses feedback control to keep the engine speed at the target speed, or the throttle valve direct drive method uses a throttle valve direct actuator to adjust the amount of air in the intake passage and feedback controls the engine speed to reach the target speed. ing.

[0003] The latter direct-acting throttle valve system combines a DC motor or the like with a deceleration mechanism and has excellent positional stability due to its strong operating force, but it tends to increase the size of the device. This bypass air method is often adopted for idle rotation speed control because it has features such as the ability to miniaturize the device and excellent control responsiveness.

[0004] The prior art related to idle rotation speed control using this bypass air system is disclosed in Japanese Patent Laid-Open No. 60-2619.
It is disclosed in Publication No. 51 and the like.

[0005]

[Problems to be Solved by the Invention] However, in the above bypass air method, the opening degree of the idle control valve usually changes depending on the duty ratio of the drive pulse signal from the electronic control unit (ECU). However, since this idle control valve utilizes the electromagnetic attraction force of a solenoid such as a linear solenoid, it is difficult to obtain a strong operating force. Therefore, carbon, oil, etc. in the bypass passage may cause the valve to become stuck to the valve seat, or so-called valve stick.

That is, when this valve stick occurs, no amount of air is supplied from the bypass passage, resulting in difficulty in starting, engine stalling, and the like. Furthermore, even if the engine is successfully started by accelerator work, the engine will rotate at the very edge of engine stall, as shown in A in Figure 4, and on the ECU side, valve stick will occur in the idle control valve. However, this mechanical abnormality of the idle control valve cannot be detected because it is not an electrical abnormality such as a disconnection or short circuit.

Therefore, even though the duty ratio of the drive pulse signal from the ECU is increased, the engine continues to rotate with the rotation speed lower than the target rotation speed, and in this state, vibrations and shocks occur. When the valve stick of the idle control valve is fixed due to such reasons, the engine rotation speed will change to B in Figure 4 due to the drive pulse signal with a large duty ratio.
There is a risk that the control system will increase from C to C, causing overshoot and hunting in the control system.

The present invention has been made in view of the above circumstances, and it prevents the engine from stalling when a mechanical abnormality occurs in the idle control valve, and also suppresses the increase in engine speed even after the abnormality is recovered. It is an object of the present invention to provide a fail-safe device for an idle control valve that can prevent hunting in a control system.

[0009]

[Means for Solving the Problems] As shown in FIG. 1, the present invention provides an abnormality occurrence signal when an engine operating state satisfies an abnormality occurrence condition for an idle control valve provided in a bypass passage that bypasses a throttle valve. Abnormality detection means M to output
1, and an abnormality occurrence signal from the abnormality detecting means M1, outputs a first safe signal that stops driving the idle control valve, and also opens an auxiliary valve provided in parallel with the idle control valve. 2, and a warning means M3 that issues a warning based on the abnormality occurrence signal from the abnormality determining means.

0010

[Operation] In the present invention, when the engine operating state satisfies the abnormality occurrence conditions of the idle control valve, an abnormality occurrence signal is output, and this abnormality occurrence signal causes the drive of the idle control valve to be stopped and the idle control valve to be controlled. An auxiliary valve installed in parallel with the valve is opened to ensure the supply of air to the engine, and a warning is issued to notify that an abnormality has occurred.

[0011]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. The drawings show an embodiment of the present invention, with FIG. 2 being a schematic diagram of an engine control system, and FIG. 3 being a flowchart showing a fail-safe execution procedure.

[Configuration of engine control system] In FIG. 2,
Reference numeral 1 denotes an engine main body (horizontally opposed four-cylinder engine in the figure), and an intake manifold 3 and an exhaust manifold 4 are connected to a cylinder head 2 of the engine main body 1, respectively.

A throttle chamber 6 is communicated with the upstream side of the intake manifold 3 via an air chamber 5, and the upstream side of the throttle chamber 6 is communicated with an air cleaner 8 via an intake pipe 7. Further, an intake air amount sensor 9 is placed directly downstream of the air cleaner 8.

Further, a throttle opening sensor 10 is attached to the throttle valve 6a provided in the throttle chamber 6.
a and an idle switch 10b that detects the fully closed throttle valve are connected, and the throttle valve 6
An idle control valve (ISCV) 11a is installed in the first bypass passage 11 that bypasses the air and connects the upstream side and the downstream side.
In addition, an idle up solenoid (hereinafter referred to as FICD) that is turned on when the air conditioner is activated is installed in the second bypass passage 12 that bypasses the throttle valve 6a and communicates the upstream side and the downstream side. ) 12a is interposed as an auxiliary valve.

The ISCV 11a is composed of a linear solenoid valve and the like, and the valve opening degree increases or decreases in accordance with the duty ratio of the drive pulse signal, and the amount of air in the bypass passage 11 increases or decreases. Further, the FICD 12a is constituted by a normal solenoid valve, and when turned on when the air conditioner is operating, opens the second bypass passage 12 to supply air to the engine, increases the idle speed, and turns off the air conditioner. and the above ISCV11
It is turned on when a mechanical failure occurs in a, and supplies air to the engine from the second bypass passage 12 to prevent engine stall.

Note that the first bypass passage 11 and the second bypass passage 12 do not necessarily have to be independent;
The upstream side of the bypass passage may be shared, and the downstream side may be branched, and the ISCV 11a and the FICD 12a may be installed in each passage.

Further, an injector 13 is disposed immediately upstream of each intake port of each cylinder of the intake manifold 3, and injects a cooling water temperature into a cooling water passage (not shown) forming a riser formed in the intake manifold 3. A sensor 14 is facing. Furthermore, an O2 sensor 16 is provided facing an exhaust pipe 15 communicating with the exhaust manifold 4. Note that the reference numeral 17 is a catalytic converter.

A crank rotor 18 is fixed to the crankshaft 1a of the engine body 1, and the crank rotor 18 has an electromagnetic pickup on its outer periphery that detects a protrusion (or slit) corresponding to a predetermined crank angle. A crank angle sensor 19 is provided oppositely.

[Circuit configuration of control device] On the other hand, reference numeral 20 denotes an electronic control unit (ECU) consisting of a microcomputer.
, and the CPU 21, ROM 22, and R of this ECU 20
The AM 23 and the I/O interface 24 are connected to each other via a bus line 25, and a predetermined stabilized voltage is supplied from a constant voltage circuit 26.

[0020] Then, when the engine operating state satisfies the abnormality occurrence condition of the idle control valve provided in the bypass passage that bypasses the throttle valve, the ECU 20
Abnormality detection means for outputting an abnormality occurrence signal; and an auxiliary valve that outputs a first safe signal to stop driving the idle control valve in response to the abnormality occurrence signal from the abnormality detection means, and is provided in parallel with the idle control valve. Various control functions are realized, including a safe signal generating means for outputting a second safe signal to open the gate.

[0021] The constant voltage circuit 26 includes an ECU relay 27
is connected to the battery 28 through the relay contact of the E
A relay coil of the CU relay 27 is connected to the battery 28 via a key switch 29. In addition, the above I
/O The input port of the interface 24 is connected to the intake air amount sensor 9, throttle opening sensor 10a, cooling water temperature sensor 14, O2 sensor 16, crank angle sensor 19,
A vehicle speed sensor 30, an idle switch 10b, an air conditioner switch 31, a neutral switch 32, a power steering switch 33, etc. are connected, and the engine operating state is determined from the output signals of these sensors and switches, data calculated by the CPU 21, etc. is detected.

Furthermore, the above I/O interface 2
The relay contact of the ECU relay 27 is connected to the input port 4 to monitor the battery voltage VB, while the output port of the I/O interface 24 is connected to the ISCV 11a and FICD 12 via the drive circuit 34.
A, the injector 13, and a check lamp 35 as a warning means for notifying the occurrence of an abnormality are connected.

The ROM 22 stores a control program and various control fixed data, and also stores the RA
M23 stores data after processing the output signals of the sensors and switches, and data processed by the CPU 21.

The CPU 21 calculates the fuel injection amount, ignition timing, etc. according to the control program stored in the ROM 22, and outputs a drive pulse signal to the injector 13, an ignition signal to the spark plug (not shown), etc. The duty ratio of the drive pulse signal is calculated, and the amount of air in the first bypass passage 11 is controlled to keep the idle rotation speed constant.

[Failsafe execution procedure] Next, the IS
A failsafe execution procedure for the CV 11a will be explained. FIG. 3 shows a general flow of an interrupt routine that is executed at predetermined time intervals. Water temperature TW
, vehicle speed S from vehicle speed sensor 30, and ISCV11
Import the engine operating state such as the duty ratio DUTY of the drive pulse signal for a and the calculation data.

Next, the process proceeds to step S102, where it is determined whether these engine operating conditions meet conditions for occurrence of an abnormality in mechanical operation, such as valve sticking in the ISCV 11a. That is, the idle switch 10b and the neutral switch 32 are ON, the air conditioner switch 31 and the power steering switch 33 are OFF, and the vehicle speed S is the set value SSET (for example, 8 km/h).
Below, and the cooling water temperature TW is the set water temperature (for example, 70
°C) or more, if the duty ratio DUTY of the drive pulse signal of ISCV11a is more than the set value DUTYSET (for example, 60%), the duty ratio DUTY has increased to a value that is not possible under normal conditions. , it is determined that valve sticking has occurred in the ISCV 11a, and the process proceeds from step S102 to step S103. On the other hand, if even one of these engine operating conditions deviates from the conditions, the routine exits from step S102.

When it is determined in step S102 that a valve stick has occurred and the process proceeds to step S103, ISCV1
The duty ratio DUTY of the drive signal for 1a is set to “0”.
"(DUTY ← 0) and outputs the first safe signal to maintain the continuous OFF state, and then in step S104
When the second safe signal is output to turn on the FICD 12a and open it, in step S105, the check lamp 35 is turned on to notify the driver of the occurrence of an abnormality, and the routine exits.

As a result, even if the first bypass passage 11 is blocked due to a mechanical failure such as valve sticking in the ISCV 11a, the FICD 12
a is turned on and air is supplied from the second bypass passage 12, so engine stall can be prevented.Furthermore, since the duty ratio DUTY does not increase as a result of feedback to the target rotation speed, the IS
Even when the CV 11a returns to normal, it is possible to suppress the increase in engine speed and prevent control hunting.

It should be noted that the present invention is not limited to the above-described embodiments, and a fail-safe device for the ISCV 11a may be configured using only hardware such as counters, comparators, gates, etc.

[0030]

[Effects of the Invention] As explained above, according to the present invention, it is possible to prevent an engine stall when a mechanical abnormality occurs in the idle control valve, and to suppress the increase in engine speed when the abnormality is recovered. Excellent effects such as being able to prevent hunting in the control system can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a claim correspondence diagram showing the basic configuration of the present invention.

FIG. 2 is a schematic diagram of an engine control system.

FIG. 3 is a flowchart showing a failsafe execution procedure.

FIG. 4 is an explanatory diagram illustrating a conventional example and a change in engine speed when an abnormality occurs.

[Explanation of symbols]

M1 Abnormality detection means M2 Safe signal generation means M3 Warning means

Claims (1)

[Claims] 1. Abnormality detection means for outputting an abnormality occurrence signal when an engine operating state satisfies abnormality occurrence conditions for an idle control valve provided in a bypass passage that bypasses a throttle valve; and an abnormality detection means for outputting an abnormality occurrence signal from the abnormality detection means. Safe signal generating means for outputting a first safe signal for stopping the drive of the idle control valve and a second safe signal for opening an auxiliary valve provided in parallel with the idle control valve in response to the signal; 1. A fail-safe device for an idle control valve, comprising: warning means for issuing a warning in response to an abnormality occurrence signal from the abnormality determining means.