JPH1018897A - Method and device for discriminating abnormality of intake system sensor of engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an intake air amount sensor and a throttle sensor from being erroneously discriminated that they are abnormal when a bypass air for bypassing a throttle valve is supplied. SOLUTION: A bypass passage 8 for bypassing a throttle valve 5 is provided at an intake passage 2, and a control valve 9 which opens when a temperature of an engine cooling water is equal to or less than a predetermined value is provided at the bypass passage 8. When a throttle opening detected by a throttle sensor 10 is equal to or less than a predetermined opening at the time the intake air amount detected by an intake air amount sensor 4 is more than a predetermined value, it is discriminated that the throttle sensor 10 is abnormal. When the intake air amount detected by the intake air amount sensor 4 is equal to or more than the predetermined value at the time an engine speed is equal to or less than a predetermined value, it is discriminated that the intake air amount sensor 4 is abnormal. At an engine cold state in which the bypass air is supplied, the discrimination of abnormality in the sensors 4, 10 is prohibited.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for determining an abnormality of an intake system sensor of an engine.

[0002]

2. Description of the Related Art In an engine, particularly an automobile engine,
An intake system sensor whose output changes in accordance with a change in the amount of intake air is provided in an intake passage of the engine. Examples of the intake system sensor include an intake air amount sensor for detecting an intake air amount and a throttle sensor for detecting a throttle opening.

The output of the intake system sensor as described above is used as an important parameter used for engine control and the like. If there is an abnormality in the intake system sensor, the engine control and the like will not be performed well. For this reason, it is required to determine the presence or absence of abnormality of the intake system sensor.
No. 33456 is proposed. According to this publication, the actual intake air amount obtained from the output of the intake air amount sensor is compared with the theoretically obtained intake air amount obtained based on the throttle opening and the engine speed. An abnormality of the intake air amount sensor is determined.

On the other hand, a bypass passage that bypasses a throttle valve is provided in an intake passage of the engine. When the engine is cold, the bypass passage is opened to increase the amount of intake air. The control valve that opens the bypass passage may be of a mechanical type, for example, a coolant temperature-sensitive type that operates according to the engine coolant temperature.

As described above, the supply of bypass air from the bypass passage greatly changes the amount of intake air supplied to the engine. The output of some system sensors will not be affected (for example, a throttle sensor).

Therefore, based on the output of a specific intake system sensor whose output does not change in accordance with the amount of bypass air, it is possible to determine whether the specific intake system sensor itself is abnormal or to use the output of this specific intake system sensor. When the abnormality determination of another intake system sensor is performed, the abnormality determination may not be performed accurately.

In particular, when the output of a plurality of sensors including an intake system sensor is compared to determine the presence or absence of an abnormality in the intake system sensor, it is likely that the presence or absence of the abnormality cannot be normally determined due to the influence of the bypass air. Becomes

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to determine that an intake system sensor is erroneously abnormal when bypass air for bypassing a throttle valve is supplied. It is an object of the present invention to provide a method and an apparatus for determining an abnormality of an intake system sensor of an engine, which can prevent or suppress the occurrence of an abnormality.

To achieve the above object, the method of the present invention is as follows. That is, an intake system sensor whose output changes in response to a change in the amount of intake air is provided in the intake passage of the engine, and when the engine is cold, a bypass passage that bypasses the throttle valve is opened to increase the amount of intake air. In the engine described above, the abnormality determination condition for determining the presence or absence of an abnormality in the intake system sensor based on the output of the intake system sensor is changed so that it is difficult to determine that the system is abnormal when the engine is cold. Preferred embodiments based on the above method are as described in claims 2 to 6 in the claims.

In order to achieve the above object, the apparatus of the present invention is configured as follows. That is, an intake system sensor whose output changes in response to a change in the amount of intake air is provided in the intake passage of the engine, and when the engine is cold, a bypass passage that bypasses the throttle valve is opened to increase the amount of intake air. In the engine, the abnormality determination means for determining the presence or absence of abnormality of the intake system sensor based on the output of the intake system sensor, and the abnormality determination condition of the abnormality determination unit is hardly determined to be abnormal when the engine is cold. And a determination condition changing means for changing. A preferable mode based on the above method is as described in claim 8 of the claims.

[0009]

According to the first aspect of the present invention, when bypass air is supplied, the abnormality determination condition is changed so that the intake system sensor is less likely to be determined to be abnormal. A situation in which the sensor is erroneously determined to be abnormal can be prevented or suppressed.

According to the second aspect, when the bypass air is supplied, the abnormality determination is prohibited, so that the erroneous determination that the intake system sensor is abnormal can be reliably prevented.

According to the third aspect, a situation in which the intake air amount sensor is erroneously determined to be abnormal is prevented or suppressed.

According to the fourth aspect, a specific condition for determining the abnormality of the intake air amount sensor is provided.

According to the fifth aspect, a situation in which the throttle sensor is erroneously determined to be abnormal is prevented or suppressed.

According to the sixth aspect, a specific condition for determining the abnormality of the throttle sensor is provided.

According to the seventh aspect of the invention, the same effect as that of the first aspect can be obtained.

According to the eighth aspect, the same effect as the effect according to the second aspect can be obtained.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, reference numeral 1 denotes an engine body, 2 denotes an intake passage, and the intake passage 2 has an air cleaner 3, an intake air amount sensor 4, and a throttle in order from the upstream side to the downstream side. A valve 5 and a surge tank 6 are provided.
Intake passage 2 between tank 6 and engine body 1
Are independent intake passages 2a which are independent for each cylinder. A fuel injection valve (fuel supply means) 7 is disposed in the independent intake passage 2a.

The intake passage 2 is provided with a bypass passage 8 for bypassing the throttle valve 5. One end of the bypass passage 8 is opened to the intake passage 2 downstream of the intake air amount sensor 4 and upstream of the throttle valve 5, and the other end of the bypass passage 8 is located downstream of the throttle valve 5 and close to the suction valve.
It is open to the intake passage 2 upstream of the tank 6.

A control valve 9 is provided in the bypass passage 8. In the embodiment, the control valve 9 is of a cooling water temperature responsive type whose opening degree changes according to the engine cooling water temperature. More specifically, the control valve 9 is provided with thermo wax, and is fully closed when the engine coolant is supplied and the coolant temperature is equal to or higher than a predetermined upper limit temperature (for example, 80 ° C.). The opening degree gradually increases as the cooling water temperature decreases from the upper limit temperature, and becomes fully open at or below a predetermined lower limit temperature.

A throttle sensor 10 for detecting the opening degree of the throttle valve 5 is provided. The throttle sensor 10 serves as an intake system sensor together with the intake air amount sensor 4. The intake air amount detected by the intake air amount sensor 4 is used, for example, as a parameter for determining the fuel injection amount from the fuel injection valve 7. The throttle opening detected by the throttle sensor is used, for example, as a parameter for speed control of an automatic transmission or as a parameter for detecting acceleration of an engine (for increasing the amount of fuel acceleration). Needless to say, the outputs of the sensors 4 and 10 can be used as appropriate conventional control parameters in addition to the above-described cases.

In FIG. 1, reference numeral 21 denotes an exhaust passage. In the exhaust passage 21, an oxygen sensor (0
₂ ) and an exhaust gas purifying catalyst (Sangen catalyst) 23 are provided. As is known, the oxygen sensor 22 has a characteristic that its output greatly changes (output inversion) between the rich side and the lean side with respect to the stoichiometric air-fuel ratio.

In FIG. 3, U is a control unit (controller) constituted by using a microcomputer, which has a CPU as arithmetic means and a ROM and RAM as storage means, as is known. And is mounted on the vehicle. The control unit U includes the sensors 4, 1
Water temperature sensor 1 that detects the cooling water temperature in addition to the signal from 0
1. A signal from a rotation speed sensor 12 for detecting an engine rotation speed is input. Also, from this control unit U,
It is output to an alarm 13 as a display means such as a lamp or a buzzer or an alarm means.

The control unit U uses the output of the oxygen sensor 22 to perform air-fuel ratio feedback control or the like so that the air-fuel ratio becomes the stoichiometric air-fuel ratio. The abnormality determination of the system sensors 4 and 10 is also performed (the input / output relationship in FIG. 2 shows only the one used for this abnormality determination). Hereinafter, the abnormality determination of the intake system sensors 4 and 10 by the control unit U will be described with reference to the flowchart of FIG. 3, where Q indicates a step in the following description.

First, in Q1, each of the sensors 4, 10,.
After the signals from 11 and 12 are input, in Q2,
It is determined whether or not the coolant temperature detected by the coolant temperature sensor 11 is equal to or lower than a predetermined temperature (80 degrees C in the embodiment). If the determination in Q2 is YES, the presence or absence of an abnormality in the throttle sensor 10 is determined in Q3 and Q4 (Q3 and Q4 are abnormality determination means). That is, in Q3, it is determined whether or not the intake air amount detected by the intake air amount sensor 4 is equal to or larger than a predetermined value (in the embodiment, the intake air amount is set near the throttle being fully opened). This Q3
Is YES, it is determined in Q4 whether or not the throttle opening detected by the throttle sensor 10 is equal to or less than a predetermined value (in the embodiment, a low opening is set to 1/8 opening). .

When the determination in Q4 is YES, the throttle opening is too small compared to the intake air amount.
At this time, it is determined that there is an abnormality in the throttle sensor 10, and the processing of Q5 and thereafter is performed. That is, Q5
In step (6), the alarm 13 is activated, and then in Q6, a failure code indicating that the throttle sensor 10 is abnormal is stored.

When the result of the determination of the above Q3 is NO, or when Q4
If the determination is NO, the presence or absence of an abnormality in the intake air amount sensor 4 is determined by the processing of Q7 and Q8, respectively (Q7 and Q8 are abnormality determination means). That is, first, Q7
In, it is determined whether or not the engine speed is equal to or less than a predetermined value (in the embodiment, set to 2000 rpm at which the engine speed becomes low). When the determination in Q7 is YES, in Q8, the intake air amount detected by the intake air amount sensor 4 is a predetermined value (in the embodiment, 4000 rpm higher than the predetermined value in Q7).
m is set to the intake air amount when the throttle is fully opened at m.

If the determination in Q8 is YES, the detected intake air amount is too large compared to the engine speed, and the intake air amount sensor 4 is abnormal. At this time, after the alarm 13 is activated in Q9, a failure code indicating that the intake air amount sensor 4 is abnormal is stored in Q10.

If the determination in Q2 is YES, the control valve 9 is opened and the bypass air is supplied from the bypass passage 8. In this case, the above-described abnormality determination of the intake system sensors 4 and 10 is performed. Is returned to Q1 to prohibit the operation.

FIG. 4 shows an example in which the above-described abnormality determination function is provided to an external device 71 outside the vehicle, for example, an external device 71 installed in a vehicle maintenance shop or the like. The external device 71 has a connection coupler 72 connected to a control unit U mounted on the vehicle, and inputs data necessary for abnormality determination from the control unit U (input signals from each sensor). etc). Of course, the external device 71 is set to perform a control step as shown in FIG.
In this case, in a maintenance shop or the like where the external device 71 is installed, the vehicle (engine) is brought into a predetermined operation state.
Automatic or manual operation. When the abnormality determination of the intake system sensors 4 and 10 is performed only by the external device 71,
It is not necessary to incorporate a control step as shown in FIG. 3 into the control unit U mounted on the vehicle.

Although the embodiment has been described above, the present invention is not limited to this and includes, for example, the following cases.

When the control valve 9 is opened and the bypass air is supplied, the abnormality determination conditions can be changed so that it is difficult to determine that an abnormality has occurred (for example, Q3, Q4, Q7, Q
The predetermined value as the abnormality determination threshold value in step 8 is changed).

The abnormality determination conditions of the intake system sensors 4 and 10 are as follows.
It can be set appropriately as long as it uses at least the output of the intake system sensor to be subjected to abnormality determination. For example, in the case of abnormality determination of the intake air amount sensor 4, when a predetermined operation state is detected by another sensor, the output of the intake air amount sensor which can be originally obtained in the predetermined operation state is determined by the intake air amount sensor. When the actual output values of the air amount sensor 4 are far apart from each other, it can be determined that the intake air amount sensor 4 is abnormal. In this case, the other sensor may be a speed sensor for detecting the engine speed as in the embodiment, but may be a throttle sensor for detecting the throttle opening. Preferably, as the other sensor, an engine speed sensor is used in a high intake air amount region, and a throttle sensor is used in a low intake air amount region. (Because the degree of change in air volume is small)

Similarly, when the abnormality of the throttle sensor 10 is determined, when a predetermined operation state is detected by another sensor, the output of the throttle sensor which can be originally obtained in the predetermined operation state is not detected. Throttle sensor 10
It can be determined that the throttle sensor 10 is abnormal when the actual output values in the above are far from each other. The other sensor may be the intake air amount sensor 4 as in the embodiment, or may be a rotation speed sensor for detecting the engine rotation speed.

[0034] The object of the present invention is not limited to what is explicitly specified, but implicitly provides contents corresponding to contents described in the effects of the invention or contents that are substantially preferred or advantageous. Including.

[Brief description of the drawings]

FIG. 1 is a main part system diagram showing one embodiment of the present invention.

FIG. 2 is a diagram showing an example of a control system used in the present invention.

FIG. 3 is a flowchart showing a control example of the present invention.

FIG. 4 is a simplified side view showing an example in which abnormality determination is performed by an external device outside the vehicle.

[Description of Signs] 1: Engine main body 2: Intake passage 4: Intake air amount sensor 5: Throttle valve 8: Bypass passage 9: Control valve 10: Throttle sensor 11: Water temperature sensor 12: Engine speed sensor 13: Alarm U :Controller unit

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Takuya Murakami 3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Co., Ltd.

Claims (8)

[Claims] An intake system sensor whose output changes in response to a change in intake air amount is provided in an intake passage of the engine. When the engine is cold, a bypass passage that bypasses a throttle valve is opened to reduce the intake air amount. In the engine configured to increase the amount, the abnormality determination condition for determining the presence or absence of abnormality of the intake system sensor based on the output of the intake system sensor is changed so that the abnormality is not easily determined when the engine is cold. For determining the abnormality of the intake system sensor of the engine. 2. The method according to claim 2, wherein the change of the abnormality determination condition is a prohibition of abnormality determination. 3. The method according to claim 1, wherein the intake system sensor is an intake air amount sensor that detects an intake air amount. 4. The intake system according to claim 3, wherein when the engine speed is equal to or less than a predetermined speed, the output of the intake air amount sensor outputs an output corresponding to an intake air amount equal to or higher than a predetermined value. The abnormality determination condition is set so as to determine that the air amount sensor is abnormal,
An abnormality determination method for an intake system sensor of an engine, characterized by comprising: 5. The method according to claim 1, wherein the intake system sensor is a throttle sensor that detects an opening of a throttle valve. 6. The throttle sensor according to claim 5, wherein when the intake air amount is equal to or larger than a predetermined value, the throttle sensor is abnormal when the throttle sensor outputs an output corresponding to a throttle opening smaller than the predetermined value. Wherein the abnormality determination condition is set so as to determine the abnormality of the intake system sensor of the engine. 7. An intake system sensor whose output changes in response to a change in the amount of intake air is disposed in an intake passage of the engine. When the engine is cold, a bypass passage that bypasses a throttle valve is opened to reduce the amount of intake air. In the engine configured to increase the amount, an abnormality determining unit that determines the presence or absence of an abnormality in the intake system sensor based on an output of the intake system sensor, and an abnormality determination condition of the abnormality determining unit is determined to be abnormal when the engine is cold. An abnormality determination device for an intake system sensor of an engine, comprising: a determination condition changing means for changing the condition so as to be difficult. 8. The abnormality determination device for an intake system sensor of an engine according to claim 7, wherein the determination condition changing means is set to prohibit the abnormality determination when the engine is cold.