JP2691367B2 - Engine exhaust gas recirculation valve failure determination device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas recirculation valve failure determination device for an engine that determines a failure of an exhaust gas recirculation valve that supplies exhaust gas to an intake system of the engine. .

(Prior Art) Conventionally, the exhaust gas recirculation is electronically controlled for the purpose of strictly controlling the exhaust gas recirculation so that the recirculation amount of the exhaust gas is always the minimum necessary amount in order to adversely affect the drivability and fuel economy of the engine. The device is being adopted.

As an example of this electronically controlled exhaust gas recirculation device
As disclosed in Japanese Patent Laid-Open No. 57-41455, there is a system in which a position feedback control system is adopted. This position feedback control includes a position sensor that detects a lift position of the valve body of the exhaust gas recirculation valve, and a target lift value set in advance according to an operating state of the engine,
A control signal corresponding to the difference from the lift value actually measured by the position sensor is output to the exhaust gas recirculation valve to control them so that they match.

By the way, in the exhaust gas recirculation system of the position feedback control system as described above, since the lift position of the valve body of the exhaust gas recirculation valve is detected, the exhaust gas is exhausted by the adhesion of carbon or the like to the valve body. The gas recirculation valve can determine a fully closed stuck failure condition. That is, it is possible to determine whether the exhaust gas recirculation valve is fully closed or stuck when the measured lift value is zero, even though the control signals are all output to preset target values.

However, there is a problem of erroneous determination only by the above-described failure determination. In other words, the fixation of the exhaust gas recirculation valve is due to the accumulation of impurities such as carbon, but the impurities are affected by the amount of exhaust gas. Is adhered to the valve body, so that the valve body is fixed. However, since this sticking is a temporary and light sticking degree, if a certain amount of impact is given, the sticking is originally canceled.
Conventionally, there has been a problem of erroneous failure determination because the failure determination is performed immediately without considering this point.

(Object of the Invention) The present invention is to solve the above problems, and an exhaust gas recirculation valve failure determination device for an engine capable of preventing an erroneous determination of a failure of the exhaust gas recirculation valve due to temporary fixation of the exhaust gas recirculation valve. The purpose is to provide.

(Structure of the Invention) The present invention has the following structure in order to achieve the above object.

That is, an exhaust gas recirculation valve arranged in an exhaust gas recirculation passage that connects an intake system and an exhaust system of an engine, an operating state detecting means for detecting an operating state of the engine, and an output of the operating state detecting means. Exhaust gas recirculation valve control means for outputting a control signal to the exhaust gas recirculation valve when a preset exhaust gas recirculation region is detected, and an open position of the exhaust gas recirculation valve To the exhaust gas recirculation valve when it is detected that the exhaust gas recirculation valve open position in the exhaust gas recirculation region is substantially zero in response to the output of the valve opening position detection means. Control signal changing means for changing the output control signal to a value larger by a predetermined value than the control signal according to the operating state in which zero is detected, and an exhaust gas recirculation valve after the control is executed by the control signal changing means. Wherein the open position is a determining failure determining means the failure of the exhaust gas recirculation valve when it is detected is substantially zero.

(Effects of the Invention) With the present invention configured as described above, even if the exhaust gas recirculation valve is stuck, first, the control signal for driving the exhaust gas recirculation valve is set to a predetermined value from the originally required control signal. Increase the value to impact the exhaust gas recirculation valve. Then, after that, it is determined again whether or not the open position of the exhaust gas recirculation valve is zero.As a result, if the open position of the exhaust gas recirculation valve is still zero, a failure is determined only for the moment, so that the valve is temporarily stuck. If it does, sticking is eliminated by the above control,
It is possible to prevent erroneous determination of failure.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

 FIG. 1 is an overall configuration diagram showing a specific structural example.

An air cleaner 15, a fuel injection nozzle 16, and a throttle valve 3 are provided from the upstream side in an intake passage 4 that supplies intake air to the engine 1. Further, in the intake passage 4 downstream of the throttle valve 3, a negative pressure sensor 17 for detecting an intake negative pressure is arranged.

On the other hand, one end is connected to the exhaust passage 2 and the other end is connected to the intake passage 4.
In the EGR valve 6 interposed in the middle of the return passage 5 connected to the valve body 7, a valve body 7 is supported by a diaphragm type actuator 18, and a negative pressure as a source of opening operation of the valve body 7 is provided in a negative pressure chamber of the actuator 18. The intake negative pressure is introduced through the introduction passage 19, and the EGR valve 6 is provided in the middle of the negative pressure introduction passage 19.
A three-way solenoid 20 for controlling the introduction of the negative pressure for opening operation to the valve is provided. A control signal from the control device 9 (control unit) is output to the three-way solenoid 20 to control the exhaust gas recirculation amount. A position sensor 8 for detecting the moving position of the valve body 7 is attached to the actuator 18.

A fuel supply passage 22 is connected to the fuel injection nozzle 16 to form a fuel supply device, and an ignition coil 24 is connected to an ignition plug 23 provided in the engine 1 to form an ignition device.

The fuel supply device and the ignition device are also operated and controlled by a control signal from the control device 9. That is, a fuel injection pulse is output to the fuel injection nozzle 16 to inject a predetermined amount of fuel at a predetermined time, and an ignition signal is output to the ignition coil 24 to ignite at a predetermined time.

Each control including the exhaust gas recirculation control is performed on the basis of the detection of the operating state of the engine, and the control device 9 controls the control device 9 in addition to the measured lift value from the position sensor 8 and the negative pressure sensor 17. The crank angle signal from the crank angle sensor 25 is input to detect the signal, the engine speed, and the reference crank angle (cylinder discrimination).

In addition, in addition to the above-mentioned sensors, in addition to the above sensors, a signal from a throttle sensor that detects the throttle opening, a signal from a water temperature sensor that detects the water temperature, and the supply air-fuel ratio from the exhaust gas component concentration are detected in order to perform various controls precisely. O ₂ sensor signal, the signal of the intake air temperature sensor for detecting an intake temperature, the signal of the atmospheric pressure sensor for detecting the atmospheric pressure, the signal of a starter switch for detecting the time of starting, signal etc. of a starter switch for detecting when cooler use It is input as needed.

The specific control of this embodiment will be described below with reference to the flowchart of FIG.

 First, in step 1, various signals are read.

Next, in steps 2 and 3, it is determined whether or not the current engine operating state is in the exhaust gas recirculation region shown in FIG. Then, when the result of the determination is Yes, it is determined in Step 4 whether or not the exhaust gas recirculation flow region has moved to the exhaust gas recirculation flow region for a predetermined period of time, and when it is determined Yes, the lift amount of the EGR valve 6 is determined in Step 5. It is determined whether it is 0 or not. Then, when the result of this judgment is Yes, that is, the EG
When the lift amount of the R valve 8 is 0 and the EGR valve 6 is stuck, it is determined whether the sticking is temporary or not based on the following processing. First, in step 6, it is determined whether or not a fully open flag F, which will be described later, is 0, and when it is determined as Yes, that is, when sticking in the exhaust gas recirculation region is determined for the first time this time, the EGR valve is sequentially processed in steps 7 to 9. Set the full-open flag F indicating whether the full-open control of 6 is being performed to 1, set the control signal of the EGR valve 6 to full open, and set the timer (T) indicating the time to perform the full-open control of the EGR valve 6. . Next, in step 10, it is determined whether or not the timer is 0, and when it is determined as Yes, it is determined again in step 12 whether or not the lift amount of the EGR valve 6 becomes 0.

When it is determined No, the timer is decremented in step 11. If this determination is Yes, that is, the lift amount of the EGR valve 6 is zero even though the EGR valve 6 is impacted by being fully opened for a predetermined period of time, and it is determined that the EGR valve 6 is not temporarily stuck. Time, step
It is set to 1 the failure determination flag F _F ail at 13, to display the fault by the alarm lamp. On the other hand, when it is determined No in step 12, that is, when the EGR valve 6 is fully opened for a predetermined period, the EGR valve 6
When fixation is determined has been eliminated in is already lift in the step 5 is determined to 0, since regarded to have been temporarily stuck, the failure determination flag F _F ail in step 14 0 In step 14, the display of the fault is stopped. As a result, it is possible to prevent erroneous determinations due to temporary fixation.

In addition, when it is determined No in any one of the above steps 4 and 5, based on the processing of steps 15 to 18,
The lift of the EGR valve 6 is controlled to the lift position according to the operating state, and the exhaust gas amount according to the operating state is recirculated.

Further, when it is determined No in the above steps 2 and 3, it is not the operating state in which the exhaust gas should be recirculated,
In step 18, the lift amount of the EGR valve 6 is set to 0 and the exhaust gas recirculation is prohibited.

Therefore, as shown in the time chart of FIG. 4, even if the EGR valve 6 is stuck, a failure determination is not made immediately, but once the EGR valve 6 is fully opened, the EGR valve 6 is not opened.
EG is released by applying a shock to it to eliminate temporary sticking, and by determining whether the EGR valve 6 is stuck again.
It is possible to prevent erroneous determination of the R valve 6.

In this embodiment, the EGR valve 6 is controlled to be fully open to eliminate temporary sticking, but it is not always necessary to fully open the EGR valve 6, and the EGR valve 6 is larger than the control signal set according to the operating state, and , Any value smaller than full open may be used.

[Brief description of the drawings]

FIG. 1 is an overall view of the present invention, FIG. 2 is a flow chart specifically showing control of the present invention, FIG. 3 is a characteristic diagram showing an exhaust gas recirculation region, and FIG. 4 is a time chart. 2 ... Exhaust passage, 4 ... Intake passage, 5 ... Recirculation passage, 6
...... EGR valve, 8 …… Position sensor, 9 …… Control device.

Claims (1)

(57) [Claims] 1. An exhaust gas recirculation valve disposed in an exhaust gas recirculation passage that connects an intake system and an exhaust system of an engine, an operating state detecting means for detecting an operating state of an engine, and an operating state detecting means of the operating state detecting means. An exhaust gas recirculation valve control means for receiving an output and outputting to the exhaust gas recirculation valve a control signal according to the operating state within the preset exhaust gas recirculation valve when the preset exhaust gas recirculation region is detected; When the open position detecting means for detecting the open position and the output of the open position detecting means are detected to be substantially zero in the exhaust gas recirculation region, the exhaust gas is detected. Control signal changing means for changing the control signal output to the recirculation valve to a value larger by a predetermined value than the control signal according to the operating state in which zero is detected, and exhaust gas recirculation after execution of control by the control signal changing means Exhaust gas recirculation valve failure determination device for an engine, wherein a valve-opening position and a determining failure determining means the failure of the exhaust gas recirculation valve when it is detected is substantially zero.