JPS62276244A - Control device for engine - Google Patents

Abstract

PURPOSE:To enable improvement of operability of an engine during the occurrence of a failure in operation, by a method wherein, when a failure in operation of the on-off means of a control valve located in a secondary intake air passage occurs, various control means, governing the combustion state of an engine, are regulated. CONSTITUTION:A control valve 3 located in a secondary intake air passage 2b of an engine 1 is controlled for closing by means of a 3-way solenoid valve 33 and an actuator 31 during low load running, and is controlled for opening during high load running. In which case, a control unit 34 detects a failure in operation state by means of signals from detecting switches 38 and 39 when a control valve 3 is brought into an opening state during low load running or a closed state during high load running. Various control means, governing a combustion state, e.g., an ignition timing, an EGR gas flow rate, an air-fuel ratio, responding to a change in combustibility, e.g. the magnitude of swirl due to a change in the opening and closed state of the control valve 3, are regulated in a direction in which operability is improved. This constitution enables prevention of lowering of operability due to malfunction of the control valve 3.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention (Field of Industrial Application) The present invention relates to an engine control device having a primary intake passage and a secondary intake passage equipped with a control valve. be.

(Prior art) Conventionally, the intake passage of an engine has been configured with a primary intake passage for low loads and a secondary intake passage for high loads, and a control valve has been installed to close the secondary intake passages. At low loads, the control valve is closed and intake air is supplied only through the primary intake passage to improve combustion performance by increasing the flow velocity and creating swirl, while at high loads the control valve is opened to supply intake air through the secondary intake passage. An engine is known in which air is supplied from a passage to secure a filling ship (see, for example, Japanese Patent Laid-Open No. 138723/1983).

The control valve generally has a normally closed structure and is opened by a drive device using a diaphragm or electromagnetic actuator that is operated by intake negative pressure at low loads.

(Problems to be Solved by the Invention) In the drive device for the control valve installed in the secondary intake passage as described above, for example, the negative pressure introduction pipe that introduces the intake negative pressure to the diaphragm type actuator is disconnected or the electromagnetic type Due to disconnection of the actuator or the like, a failure may occur in which the control valve does not open or close according to predetermined characteristics in response to changes in operating conditions.

As mentioned above, when the control valve that should be in the closed state is kept in the open state at low load, the intake flow rate decreases, the swirl generation becomes weaker, and the combustion rate slows down. If the ignition timing is not advanced, there will be a significant drop in fuel efficiency, deterioration of the exhaust purification catalyst and air-fuel ratio sensor due to the rise in exhaust temperature, and a decrease in the EGR gas flow due to the drop in combustibility. Unless efforts are made to improve the rich shift of the air-fuel ratio, the stability of idling operation, etc., it will not be possible to maintain a predetermined operating state. Further, in contrast to the above, if a control valve that should be open under high load is closed, problems such as insufficient output may occur.

SUMMARY OF THE INVENTION In view of the above-mentioned circumstances, it is an object of the present invention to provide an engine control device that improves the operability of the engine when a failure occurs in the 1illllll valve opening/closing means.

(Means for Solving Problems) The engine control means of the present invention uses a failure detection means to detect a failure state of the control valve opening/closing means that opens the control valve installed in the secondary intake passage under high load. The present invention is characterized in that it includes a combustion adjustment means that adjusts various control means governing the combustion state of the engine when a failure occurs in the control valve opening/opening means.

FIG. 1 is an overall configuration diagram for clearly showing the configuration of the present invention.

An intake passage 2 that supplies intake air to an engine 1 is configured to branch into a primary intake passage 2a and a secondary intake passage 2b at its downstream portion, and a control valve 3 is interposed in the secondary intake passage 2b. The control valve 3 is opened and closed by the control valve opening/closing means 4, and when the load is low, the secondary intake ventilation passage 2b is closed and the primary intake passage 2b is closed.
A is used to supply intake air with a high flow velocity to the engine 1 to generate a strong swirl, while at the same time, when the load is high, the control valve 3 is opened and the intake air is supplied to the secondary intake passage 2b in addition to the primary intake passage 2a.
It also supplies intake air from the engine to ensure a full charge of 1,711fi.

A failure detection means 5 for detecting a failure state of the control valve opening/closing means 4 is provided. This failure detection means 5 detects a failure of the control valve opening/closing means 4 when the control valve 3 is operating in an open operation range in an operating range where it should be closed, or conversely, in a case where it is operating in a closed operation range in an operating range where it should be open. It is sometimes detected. The failure detection signal from the failure detection means 5 is output to the combustion adjustment means 6, and when a failure occurs in the control valve opening/closing means 4, the combustion adjustment means 6 responds to the open or closed state of the control valve 3, which is not the original operating state. It outputs adjustment signals to various control means 7 that control various control variables such as ignition timing, EGR gas flow rate, and air-fuel ratio that govern the combustion state of the engine.

(Function) In the above control device, the control valve 3 installed in the secondary intake passage 2b is closed at low load and opened at high load by the control valve opening/closing means 4.
When the control valve 3 becomes open under low load or closed under high load due to failure of the control valve 3, this failure state is detected by the failure detection means 5, and the swirl is detected by changing the open/close state of the l1ltl valve 3. Various control means 7 that govern combustion conditions such as ignition timing, EGR gas flow rate, air-fuel ratio, etc. in response to changes in combustibility such as strength of combustion are adjusted by combustion adjustment means 6 in a direction that improves drivability. Thereby, it is possible to suppress a decrease in drivability due to malfunction of the control valve 3.

(Example) The present invention will be described in detail below with reference to the drawings.

FIG. 2 is a schematic configuration diagram of a specific example.

An intake boat 11 and an exhaust boat 12 are opened in the combustion chamber 10 of the engine 1, and the openings of both boats 11 and 12 are opened and closed at predetermined timings by an intake valve 13 and an exhaust valve 14, respectively. The intake passage 2 that communicates with the intake boat 11 and supplies intake air to the combustion chamber 10 includes an air cleaner 15 from the upstream side and an intake air amount sensor 1 that measures the amount of intake air.
6. A throttle valve 17 is installed to control the amount of intake air, and the downstream side of the surge tank 18 is formed independently for each cylinder, and the downstream part near the intake boat 11 has a relatively small passage area due to the partition wall 19. Small primary intake passage 2a
and a secondary intake passage 2b having a relatively large passage area.

Note that the downstream portion of the secondary intake passage 2b may be further branched to open into the combustion chamber 10.

Further, a fuel injection nozzle 21 for injecting fuel toward the intake boat 11 is provided in the secondary intake passage 2b for each cylinder.
A spark plug 22 is provided facing the combustion chamber 10.
is installed. Furthermore, the throttle valve 17
A bypass air passage 23 is provided to bypass the
An IG valve 24 is interposed. On the other hand, the exhaust passage 25
An EGR passage 26 is provided that recirculates a part of the exhaust gas flowing down into the intake passage 2 (surge tank 18).
EGR valve 2 that adjusts the EGR gas flow rate in the R passage 26
7 is interposed.

A control valve 3 is interposed in the secondary intake passage 2b, and the rotation shaft 3a of the control valve 3 is linked to an actuator 31 formed by a diaphragm device via an arm 28 and a connecting rod 29. It is configured to open and close the secondary intake passage 2b. This actuator 31 has an atmospheric chamber 31b and a negative pressure chamber 31c partitioned by a diaphragm 31a.
Inside is a spring 31d that biases the control valve 3 in the direction of opening.
has been reduced.

A negative pressure introduction passage 32 is connected to the negative pressure chamber 31c of the actuator 31, and the intake negative pressure generated in the intake passage 2 downstream of the throttle valve 17 by this negative pressure introduction passage 32 is used as a closing operation source for the control valve 3. It is introduced into the negative pressure chamber 31C. A three-way solenoid valve 33 is interposed in the middle of the negative pressure introduction passage 32 to introduce negative pressure into the negative pressure chamber 31C or to open the negative pressure chamber 31c to the atmosphere. This three-way solenoid valve 33 is operated by a control signal from a control unit 34, which will be described later.

When the load is low, intake negative pressure is introduced into the negative pressure chamber 31c, the actuator 31 closes the control valve 3 against the biasing force of the spring 31d, and supplies intake air only from the primary intake passage 2a. On the other hand, when the load is high, the control valve 3 is opened to the atmosphere and the actuator 31 opens the control valve 3 by the biasing force of the spring 31d, so that intake air is also supplied from the secondary intake passage 2b.

In addition to controlling the opening and closing of the control valve 3, the control unit 34 performs ignition control, air-fuel ratio control, idle control,
Performs various controls such as R control. That is, the control unit 34 outputs a drive signal to the three-way solenoid valve 33 installed in the negative pressure introduction passage 32 to the actuator 31 to control the opening and closing of the control valve 3 (swirl control), and the ignition signal to the spark plug 22 is controlled. Ignition timing control by output, fuel injection ω control (air-fuel ratio control) by outputting a fuel injection pulse to the fuel injection nozzle 21, and bypass air amount by outputting a duty signal to the SIG valve 24 installed in the bypass air passage 23. Idle control by adjusting the EGR valve 2 installed in the EGR passage 26
EGR control is performed by adjusting the amount of EGR gas by outputting a drive signal to 7.

The control unit 34 detects the intake air m signal from the intake air amount sensor 16, the intake air temperature signal from the intake air temperature sensor 35, and the opening degree of the throttle valve 17 in order to detect the operating state of the engine. The throttle opening signal from the throttle sensor 36 and the crank angle signal (engine rotation signal) from the crank angle sensor 40 installed in the distributor 37 (igniter) are respectively input, and the opening/closing of the control valve 3 including the malfunction of the actuator 31 is input. In order to detect an abnormal state, a signal from a first detection switch 38 that closes (turns on) when the three-way solenoid valve 33 is activated (when negative pressure is introduced);
The control valve 3 is connected to the opening/closing mechanism of the control valve 3, and is engaged with the rotation of a cam plate (not shown) that regulates the opening angle of the control valve 3 to open (turn on) the control valve 3 in an open state. It also receives a signal from the second detection switch 39.

The control unit 34 controls the ignition timing, air-fuel ratio, and
In addition to controlling EGRlSIG and the like, it also performs correction control to adjust the combustion state when the control valve 3 is abnormally opened or closed due to a failure of the actuator 31 or the like.

The failure control by the control unit 34 determines whether the operating state of the control valve 3 is determined based on the intake mdp and the engine speed Ne.
If it is in the closed region with low load and low rotation, a drive signal is output to the three-way solenoid valve 33 and the negative pressure introduction passage 32 injects air into the negative pressure seedling 31c of the actuator 31. Introduce negative pressure. As the three-way solenoid valve 33 operates, the first detection switch 38 is turned on. Then, when the intake negative pressure is introduced into the actuator 31 and the control valve 3 is closed, the second detection switch 39 is turned off to determine a normal operating state. On the other hand, for example, if the negative pressure introduction passage 32 is disconnected and negative pressure is not introduced, the second detection switch When control valve 39 is in the on state, control valve 3
This is to detect a failure based on the assumption that the valve is not closed.

Then, the control unit 34 performs combustion control such as retarding the ignition timing, reducing the EGR gas flow m, and increasing the bypass air m based on the failure detection that the control valve 3 is open during this low load. be. In other words, when the control valve 3 that should be used during low load is open, the swirl is weakly generated as the flow velocity decreases1, and the combustion rate is slowed, resulting in a decrease in combustibility, which reduces fuel efficiency. Deterioration of drivability due to a decrease in the allowable flow of EGR gas and a shift from the lean limit of the air-fuel ratio to rich, deterioration of idling stability, deterioration of the catalyst and air-fuel ratio sensor due to a rise in exhaust gas temperature, torque increase at the same throttle opening The decrease causes phenomena such as deterioration of running performance. Therefore, in response to these, the control unit 34 advances the ignition timing to improve fuel efficiency and lower the exhaust gas temperature, reduce the EGR gas flow rate, enrich the air-fuel ratio, and reduce the amount of bypass air. This increase improves driving performance and stabilizes idling, and roughly speaking, the shift mode of the automatic transmission is fixed to power mode to increase engine speed and use the high output range to improve driving performance. It is something.

The operation of control valve failure determination by the control unit 34 will be explained based on the flowchart of FIG. 3. After the start, in step S1, the intake air pressure signal Tp is output from the intake air m sensor 16, and the engine rotation speed N is output from the crank angle sensor 40.
Load +3. Above intake mTp and engine speed Ne
If the control valve 3 is in the open region, it is confirmed in step S2 that the first detection switch 38 is turned on in conjunction with the operation of the three-way solenoid valve 33 that introduces negative pressure into the actuator 31.

Then, in step S3, it is determined whether or not the three second detection switches are in the on state, and when the second detection switch 39 is in the off state (No), the control valve 3 is in the open state and is operating normally, so the step Normal control is performed in S4. on the other hand,
If the second detection switch 39 is in the on state, step S3
When the determination is YES, since the control valve 3 is in the open state, it is determined in step S5 that the control valve opening/closing Jll has failed, and the process proceeds to step S6, where various corrections are made at the time of failure, such as map value correction of the ignition timing. This is used to adjust the combustion conditions.

In the above embodiment, failure detection is performed based on the operation of the detection switches 38 and 39 that detect the open/closed state of the control valve 3, but for example, in the idling state, the control valve 3 is in the closed state. However, if the control valve 3 is open at that time, the intake air amount of the engine will increase. good. Also,
Similarly, if the control valves are in the same state at idle, the squirt will become weaker and the combustibility will drop, so as the base engine speed decreases, the bypass air surroundings should be adjusted by the SIG valve 24 or the ignition Since the timing is adjusted, failure detection may be performed based on the timing adjustment. Roughly, the opening/opening area of the control valve 3 is determined in accordance with the intake negative pressure and the engine speed, and this g@opening/opening area is compared with the detection of the actual opening/closing state of the control valve 3 to determine a failure. You can do it like this.

On the other hand, as the opening/closing mechanism of the control valve 3, in addition to the actuator 31 using a diaphragm device as described above, a mechanism using an electromagnetic actuator or the like can be adopted as appropriate, and the failure detection means can also be adapted to changes in these control valve opening/closing mechanisms. The design will be changed as appropriate.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram for clearly showing the configuration of the present invention, FIG. 2 is an overall configuration diagram of a specific example, and FIG. 3 is a flow chart diagram for explaining the failure determination operation by the control unit. 1...Engine 2...Intake passage 2a...Primary intake passage 2b...
・Secondary intake passage 3...Control valve 4・
... Control valve opening/closing means 5 ... Failure detection means 6 ... Combustion adjustment means 7 ... Various control means 11 ... Intake boat 21.・・・
... Fuel injection nozzle 22 ... Spark plug 2
4...SIG valve 27...EG
R valve 31... Actuator 32...
... Negative pressure introduction passage 34 ... Control unit 38.39 ... Detection switch Fig. 1

Claims (1)

[Claims] (1) An engine control device comprising an intake passage consisting of a primary intake passage and a secondary intake passage with a control valve interposed therein, and comprising a control valve opening/closing means for opening the control valve during high load. a failure detection means for detecting a failure state of the control valve opening/closing means; and a combustion adjustment means for receiving a signal from the failure detection means and adjusting various control means governing the combustion state of the engine when a failure occurs in the control valve opening/closing means. An engine control device comprising: