JPH0319373B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an engine control method, and more particularly to an engine control method including a knock sensor for detecting engine knocking.

BACKGROUND ART Various engine control systems have been proposed in the past as systems for constantly operating the engine of a vehicle such as an automobile in an optimal state. This type of conventional system includes, for example, a group of sensors that detect various data related to the operating state of the engine, and an engine control system that sets engine operating conditions based on the output of each sensor and outputs various control signals according to the settings. By supplying the output of the engine control section to the igniter, fuel injection valve, etc., the engine can always be operated in an optimal state. In particular, a system equipped with a knock sensor that detects engine knocking can suppress knocking while operating the engine at optimal ignition timing. Further, in this system, when controlling the engine speed at idle to maintain it at the target rotation speed, a device is provided for supplying a predetermined amount of intake air to the engine even during idle.

For example, as shown in FIG.
Its components include a bypass valve V that bypasses the throttle valve, an excitation coil L, and the like. This exciting coil L is excited by a transistor Q, as shown in FIG. 2, and can control the lift amount of the bypass valve V. The base of the transistor Q is supplied with a control signal from the engine control section, the duty ratio of which changes depending on the operating conditions of the engine. Therefore, the lift amount of the bypass valve V is controlled according to the average value of the excitation current supplied to the excitation coil L.

In an engine control system having such a device, intake air according to the engine operating conditions can be supplied to the engine even when the engine is idling, bypassing the throttle valve, and the engine speed can be adjusted to the target engine speed when idling. It is possible to perform control to maintain the rotational speed.

However, in the case of the above system, a signal whose duty ratio changes is supplied from the engine control section to the excitation coil L even when the engine is not idling.
Control is performed to maintain the bypass valve V at a predetermined position. Moreover, the control signal whose duty ratio changes includes harmonic components. Therefore, in the system, harmonic components of the control signal are superimposed as noise on the sensor output at times other than when the engine is idling. In particular, in the case of a knock sensor, since the output signal is an alternating current signal, if noise is superimposed on the signal, it becomes impossible to distinguish between a knocking signal and a noise signal, resulting in system malfunction.

The present invention has been made in view of the above problems,
The purpose is to provide an engine control method that can prevent noise from being superimposed on the output signal of a knock sensor.

In order to achieve the above object, the present invention includes a knock sensor that detects engine knocking, an engine control section that takes in the output signal of the knock sensor, and a bypass valve that is provided in the middle of a bypass pipe that bypasses the throttle valve. In the engine control method, the amount of air flowing through the bypass valve pipe is controlled by controlling the amount of air flowing through the bypass valve conduit by controlling the valve lift amount by the output signal of the engine control section whose duty ratio changes depending on the operating conditions of the engine, wherein the throttle valve is fully closed. The output signal supplied to the bypass valve is stopped or set to a DC signal at a predetermined level when the vehicle speed is not below a predetermined value or when the vehicle speed is not below a predetermined value.

Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

FIG. 3 shows a configuration diagram of an engine control system having a supercharger, which is a preferred embodiment of the present invention.

In FIG. 3, as sensors for detecting various data related to the operating state of the engine 2, an air flow meter 4 detects the amount of intake air supplied to the intake system of the engine, and a throttle sensor 6 detects the opening degree of the throttle valve. , a rotation angle sensor 8 for detecting engine speed, a cylinder discrimination sensor 10 for discriminating the cylinder of the engine, a knock sensor 12 for detecting knocking of the engine 2, a vehicle speed sensor 14 for detecting vehicle speed, etc. are provided. A rotation angle sensor 8 and a cylinder discrimination sensor 10 are built into the distributor 16, and a knock sensor 12 is attached to the cylinder block of the engine 2.

The respective sensor outputs are supplied to the engine control section 18. The engine control section 18 can set operating conditions for the engine 2 based on the outputs of the sensors and output various control signals according to the settings. This control signal is then supplied to the bypass valve control section 20, igniter 22, fuel injection valve 24, etc.

The bypass valve control section 20 is the bypass valve 3
0, has an excitation coil 32, a bypass pipe 34 is connected to the upstream side of the throttle valve, and a bypass pipe 34 is connected to the upstream side of the throttle valve.
6 is the surge tank 38 downstream of the throttle valve
It is connected to the. When the excitation coil 32 is excited by a control signal from the engine control unit 18, the lift amount of the bypass valve 30 is controlled, and intake air on the upstream side of the throttle valve is bypass-supplied to the downstream side of the throttle valve in accordance with the control signal. can do.

Also, a compressor 40 is installed in the engine intake system.
A supercharger 44 having a turbine 42 is provided in the exhaust system of the engine. The supercharger 44 drives the turbine 42 with exhaust gas, pressurizes the intake air of the intake system with the compressor 40, and can supply the pressurized intake air to the engine 2.

FIG. 4 shows a configuration diagram in which the engine control section 18 is configured with a microcomputer.

As shown in FIG.
D converter 64, multiplexer 66, buffer circuits 68, 70, 72, 74, waveform shaping circuit 80,
It has drive circuits 82, 84, 86, MPU50,
ROM54, RAM52, input/output ports 56,5
8. The output ports 60 and 62 are connected to the bus line 88, respectively.
connected with. The detection outputs of the vehicle speed sensor 14, air flow meter 4, throttle sensor 6, and knock sensor 12 are transferred to buffer circuits 68 to 7, respectively.
4. The detection outputs of the cylinder discrimination sensor 10 and the rotation angle sensor 8 are supplied to the input/output port 58 via the waveform shaping circuit 80. The operations of the bypass valve control section 20, igniter 22, and fuel injection valve 24 are controlled by control signals output from drive circuits 82 to 86, respectively.

The present embodiment has the above-mentioned configuration.Next, the operation of the present invention will be explained based on the flowchart shown in FIG.

The flowchart shown in FIG. 5 is a routine for controlling the bypass valve controller. First, in step 100, the throttle sensor 6,
Based on the detection signal of the vehicle speed sensor 14, the engine 2
It is determined whether or not the time is idle. That is, it is determined whether the throttle valve is fully closed and the vehicle speed is low, for example, 5 km/h or less. If the determination in this step is YES, the process moves to step 102, where control is performed to maintain the engine speed during idling at the target speed. In this case, the bypass valve control section 2
A control signal whose duty ratio changes depending on engine operating conditions set based on the various sensor outputs is supplied to the excitation coil 32 of 0.
Note that the duty ratio of this control signal is determined by the time for exciting the excitation coil 32 according to the operating conditions, and
The time during which excitation of the excitation coil 32 is stopped is determined by the operating conditions of the engine.

If the determination at step 100 is NO, that is, when the engine 2 is not idle, the process moves to step 104. In step 104, processing is performed to stop supplying the control signal to the bypass valve control section 20 or to supply a DC signal at a predetermined level to the bypass valve control section 20. That is, if the bypass valve 30 is of a type that closes the bypass line by de-energizing the excitation coil 32, it stops supplying the control signal to the excitation coil 32, and closes the bypass line by energizing the excitation coil 32. If the valve 30 is of the type that closes the bypass line, a DC signal at a predetermined level is supplied to the excitation coil 32.

As described above, in this embodiment, a control signal whose duty ratio changes and includes a harmonic component is not supplied to the bypass valve control section 20 except when the engine 2 is idling. It is possible to prevent this from happening.

In this embodiment, an engine with a supercharger has been described, but in the case of an engine without a supercharger, there is no need to control the bypass pipes 34 and 36 to close the bypass valve. Even if the type 30 is one of the above types, it is possible to prevent noise from being superimposed on the knock sensor 12 by stopping the supply of the control signal or by supplying a DC signal of a predetermined level to the bypass valve control section 20. It can be prevented.

As explained above, according to the present invention, a control signal that changes the duty ratio is not supplied to the bypass valve control section except when the engine is idling, so it is possible to prevent noise from being superimposed on the output signal of the knock sensor. This has an excellent effect.

[Brief explanation of the drawing]

Figure 1 is a diagram for explaining the configuration of a valve used in an idle speed control device, and Figure 2 is a diagram for explaining the configuration of a valve used in an idle speed control device.
FIG. 1 is a drive circuit diagram of an excitation coil, FIG. 3 is a configuration diagram showing an embodiment of the present invention, and FIG.
FIG. 5 is a diagram for explaining the configuration of the engine control section shown in the figure, and FIG. 5 is a flowchart for explaining the operation according to the present invention. 2...Engine, 4...Air flow meter, 6...
... Throttle sensor, 12 ... Knock sensor, 1
4...Vehicle speed sensor, 18...Engine control unit, 2
0... Bypass valve control unit, 24... Fuel injection valve, 30... Bypass valve, 32... Excitation coil, 44... Supercharger.

Claims (1)

[Claims] 1 Equipped with a knock sensor that detects engine knocking and an engine control unit that takes in the output signal of the knock sensor, the valve lift amount of the bypass valve provided in the middle of the bypass pipe that bypasses the throttle valve is determined based on engine operating conditions. In the engine control method of controlling the amount of air flowing through the bypass valve line by controlling the amount of air flowing through the bypass valve line by controlling the duty ratio by the output signal of the engine control section, the throttle valve is not fully closed or the vehicle speed is not below a predetermined value. An engine control method characterized in that the output signal supplied to the bypass valve during the state is stopped or set to a DC signal at a predetermined level.