JP3483968B2 - Engine control sensor abnormality detection method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention diagnoses a throttle sensor for detecting a throttle opening and an intake air amount sensor for measuring an intake air amount based on mutual output values. The present invention also relates to a method for detecting an abnormality of an engine control sensor for detecting an abnormality. 2. Description of the Related Art As is well known, many engine control systems have a function of self-diagnosing a failure of an engine control sensor such as an intake air amount sensor or a throttle sensor, and an abnormality has occurred. In such a case, a warning is issued to the driver to call attention, and a malfunction of the system due to the abnormal data is avoided. For example, Japanese Patent Laying-Open No. 62-96758 discloses a technique for judging an abnormality of a throttle opening detecting means based on a detection value of another engine load detecting means.
When it is determined that there is an abnormality, a warning is issued to notify the driver. [0004] Incidentally, when diagnosing one control sensor, it is necessary to judge an abnormality under a set condition, as disclosed in the above-mentioned prior art. However, the output values of other sensors must be used. For this reason, when trying to diagnose the intake air amount sensor and the throttle sensor using the output values of both, there is a possibility that both of them may be abnormal, and there is a possibility that erroneous diagnosis may occur. SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and when diagnosing a failure of an intake air amount sensor and a throttle sensor by using output values of each other, erroneous diagnosis is prevented to improve reliability. It is an object of the present invention to provide a method for detecting an abnormality of an engine control sensor that can be performed. SUMMARY OF THE INVENTION The present invention provides an engine for alternately executing a failure diagnosis process for an intake air amount sensor for detecting an intake air amount and a failure diagnosis process for a throttle sensor for detecting a throttle opening. a method for detecting abnormality control sensor, the fault with respect to the intake air quantity sensor
The flag corresponding to the diagnosis result and the throttle
A flag corresponding to the result of the failure diagnosis
Then, the failure diagnosis process for the intake air amount sensor and
Any of the above fault sensor diagnostic processing
Diagnosis is performed from one process, and in the failure diagnosis process for the intake air amount sensor,
Refer to the flag corresponding to the judgment result of the failure diagnosis for
While the diagnosis is stopped when the throttle sensor is determined to be abnormal, the diagnosis is executed when the throttle sensor is determined to be normal, and the engine speed and the output value of the throttle sensor are determined. When the output value of the intake air amount sensor at the time of high rotation and high load is smaller than the first determination value, or at the time of low rotation and low load based on the engine speed and the output value of the throttle sensor. When the output value of the air amount sensor is larger than the second determination value, it is determined that the intake air amount sensor is abnormal, and in the failure diagnosis process for the throttle sensor, the failure diagnosis for the intake air amount sensor is performed. Judgment
By referring to the flag corresponding to the result, the diagnosis is stopped when the intake air amount sensor is determined to be abnormal, and the diagnosis is performed when the intake air amount sensor is determined to be normal. When the output value of the throttle sensor at high rotation and high load based on the engine speed and the output value of the intake air amount sensor is smaller than a third determination value, or the engine speed and the intake air amount When the output value of the throttle sensor at the time of low rotation and low load based on the output value of the sensor is larger than a fourth determination value, it is determined that the throttle sensor is abnormal. According to the present invention, when each of the failure diagnosis processes is performed using the output values of the throttle sensor and the intake air amount sensor, suction is performed based on a flag corresponding to the determination result of the failure diagnosis.
Diagnosis processing and throttle sensor for air flow sensor
Diagnosis from either one of failure diagnosis processing
Is performed, and if one is determined to be abnormal by referring to the flag , the diagnosis is stopped . In the diagnosis of the intake air amount sensor performed when it is determined that the throttle sensor is normal, when the output value of the intake air amount sensor is smaller than the first determination value during high rotation and high load, At low rotation and low load, when the value is larger than the second determination value, it is determined that there is an abnormality, and when the intake air amount sensor is determined to be normal, the throttle sensor output value is determined in the diagnosis of the throttle sensor. If it is smaller than the third determination value at high rotation and high load, or larger than the fourth determination value at low rotation and low load, it is determined to be abnormal. An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of the present invention. FIG. 1 is a flowchart of a routine for diagnosing a failure of an intake air sensor, FIG. 2 is a flowchart of a routine for diagnosing a failure of a throttle sensor, FIG. 3 is a schematic configuration diagram of an engine system, and FIG. FIG. 5 is an output characteristic diagram of the intake air amount sensor, and FIG. 6 is an output characteristic diagram of the throttle sensor. In FIG. 3, reference numeral 1 denotes an engine,
The figure shows a horizontally opposed four-cylinder engine. An intake manifold 3 communicates with each intake port 2 a formed in a cylinder head 2 of the engine 1, a throttle chamber 5 communicates with the intake manifold 3 via an air chamber 4, and an intake pipe is provided upstream of the throttle chamber 5. An air cleaner 7 is attached through the air cleaner 6. The air cleaner 7 of the intake pipe 6
An intake air amount sensor 8 of, for example, a hot wire type is interposed immediately downstream of the throttle valve 5. Further, a throttle sensor 9 for detecting a throttle opening is connected to a throttle valve 5 a provided in the throttle chamber 5. I have. As shown in FIG. 5, the intake air amount sensor 8 has a characteristic whose output voltage is represented by a monotonically increasing curve with respect to an increase in the intake air amount. As shown in FIG. 6, the output voltage has a characteristic that increases substantially linearly with an increase in the throttle opening. An idle speed control valve (ISCV) 11 is interposed in a bypass passage 10 connecting the upstream side and the downstream side of the throttle valve 5a, and each of the cylinders of the intake manifold 3 is provided with an idle speed control valve (ISCV). An injector 14 is located just upstream of the intake port 2a, and an ignition plug 15a having a tip exposed to a combustion chamber is attached to the cylinder head 2 for each cylinder.
An igniter 16 is connected to an ignition coil 15b connected to the ignition plug 15a. The injector 14 has a fuel supply passage 17.
The fuel tank 18 is in communication with the fuel tank 18 through which an in-tank type fuel pump 19 is provided. The fuel from the fuel pump 19 is pressure-fed to the injector 14 and the pressure regulator 21 through the fuel filter 20 interposed in the fuel supply path 17, and is returned from the pressure regulator 21 to the fuel tank 18 to a predetermined pressure. Regulated to pressure. A knock sensor 22 is attached to the cylinder block 1a of the engine 1, and a cooling water temperature sensor 24 faces a cooling water passage 23 which communicates the left and right banks of the cylinder block 1a. Further, the front O2 is connected to a collecting portion of the exhaust manifold 25 communicating with the exhaust port 2b of the cylinder head 2.
A sensor (FO2 sensor) 26a is provided, and a front catalytic converter 27a is interposed downstream of the FO2 sensor 26a. A rear catalytic converter 27b is interposed immediately downstream of the front catalytic converter 27a, and a rear O2 sensor (RO2 sensor) 26b faces the downstream of the rear catalytic converter 27b. The RO2 sensor 26b is, for example,
The FO2 sensor 2 is provided for catalyst deterioration diagnosis and the like.
A catalyst deterioration diagnosis is performed based on a comparison result between the output of the RO2 sensor 26b and the output of the RO2 sensor 26b. A crank rotor 28 is mounted on a crankshaft 1b supported by the cylinder block 1a. A protrusion (or a slit) corresponding to a predetermined crank angle is detected on the outer periphery of the crank rotor 28. A crank angle sensor 29 including a magnetic sensor (e.g., an electromagnetic pickup) or an optical sensor is provided. Further, the camshaft 1c of the cylinder head 2
The cam rotor 30 is connected to the cam rotor 30.
Similarly, a cam angle sensor 31 for identifying a cylinder, which includes a magnetic sensor or an optical sensor, is provided in opposition. On the other hand, in FIG.
41, ROM 42, RAM 43, backup RAM 4
4. an electronic control unit (ECU) mainly composed of microcomputers connected to each other via a bus line 46, and an I / O interface 45;
In addition, a constant voltage circuit 47 that supplies a stabilized voltage to each unit,
A drive circuit 48 for driving actuators based on a signal from the output port of the I / O interface 45, and an A for converting an analog signal from a sensor into a digital signal.
Peripheral circuits such as a / D converter 49 are incorporated. The constant voltage circuit 47 is directly connected to the ECU
The relay 50 is connected to a battery 51 via a relay contact of the relay 50, and the relay coil of the ECU relay 50 is connected to the battery 51 via an ignition switch 52. The I / O interface 45
Sensor port, crank angle sensor 29, cam angle sensor 31, and vehicle speed sensor 32 are connected to the input ports, and the intake air amount sensor 8, throttle sensor 9, cooling water temperature sensor 24, FO2 sensor 26a, The RO2 sensor 26b is connected via the A / D converter 49, and the voltage from the battery 51 is input to the A / D converter 49 to monitor the battery voltage. On the other hand, the I / O interface 45
The igniter 16 is connected to an output port of the ISCV 11, the injector 14, and an instrument panel (not shown) via the drive circuit 48, and an MIL lamp 53 that collectively displays various alarms is provided. Is connected. The ROM 42 stores engine control programs, various failure diagnosis programs, and fixed data such as maps, and the like.
The data obtained by processing the output signals of the sensors and switches and the data processed by the CPU 41 are stored. The backup RAM 44 stores various learning maps, trouble data, and the like. The backup voltage is always supplied from the constant voltage circuit 47 regardless of whether the ignition switch 52 is on or off, and the ignition switch 52 is turned off. Sometimes data is retained. The trouble data can be read out by connecting the serial monitor 60 to the ECU 40 via the connector 54. This serial monitor 60 is disclosed in Japanese Unexamined Patent Publication No. 2-73131 filed earlier by the present applicant.
The details are described in the official gazette. The CPU 41 performs engine control such as fuel injection control and ignition timing control based on signals from the sensors and the like. At this time, the CPU 41 performs intake air control according to a failure diagnosis routine shown in FIGS. Quantity sensor 8
Then, a failure diagnosis of the throttle sensor 9 is performed, and when it is determined that the throttle sensor 9 is normal, each measurement data is adopted as control data. Hereinafter, a failure diagnosis process for the intake air amount sensor 8 and the throttle sensor 9 will be described. This failure diagnosis is performed by alternately executing the intake air amount sensor failure diagnosis routine shown in FIG. 1 and the throttle sensor failure diagnosis routine shown in FIG. If an abnormality is detected in one or both of the throttle RA and the throttle sensor 9, the backup RA
A flag indicating abnormality is set in M44,
The IL lamp 53 is lit or blinked to warn the driver. In these routines, the engine speed N calculated based on the signal from the crank angle sensor 29
An abnormality is reliably detected using high-speed high-load operation and low-speed low-load operation determined as a diagnostic condition based on E and the output voltage value θV of the throttle sensor 9 or the output voltage QV of the intake air amount sensor 8. In order to prevent erroneous diagnosis, the diagnosis by the intake air amount sensor failure diagnosis routine is executed when the throttle sensor 9 is determined to be normal by the throttle sensor failure diagnosis routine, and is executed by the throttle sensor failure diagnosis routine. The diagnosis is performed when the intake air amount sensor 8 is determined to be normal by the intake air amount sensor failure diagnosis routine. The signal from the crank angle sensor 29 is
This is a basic timing of the engine control system, and it is assumed that the normal state is confirmed from the execution state of another diagnostic program or various processes. First, a failure diagnosis routine for the intake air amount sensor 8 shown in FIG. 1 will be described. In this routine, first, in step S101, a throttle sensor N which is set when the throttle sensor 9 is diagnosed as abnormal in a failure diagnosis routine of the throttle sensor 9 described later.
Referring to the G flag FLGTHS, if FLGTHS = 1 and the throttle sensor 9 is abnormal, the routine exits the routine and the diagnosis is stopped, and if FLGTHS = 0, the throttle sensor 9 is set.
Is normal, the process proceeds to step S102 and subsequent steps. In step S102, the engine speed NE is compared with a set value NEH1 on the high speed side, and if NE> NEH1,
In step S103, the output voltage θV of the throttle sensor 9 is compared with a set value VH1 on the high opening degree side. And θV ≦ VH1
In the case of, it is determined that the diagnosis condition of high rotation and high load is not satisfied, and the routine exits from step S103. If θV> VH1,
The process proceeds to step S104 in order to determine that the diagnosis condition of high rotation and high load is satisfied and to execute the diagnosis of the intake air amount sensor 8. In step S104, the output voltage QV of the intake air amount sensor 8 is compared with a first determination value VA (see FIG. 5). The first determination value VA is obtained by an experiment or the like, based on the output value of the intake air amount sensor 8 which can be taken at the time of high rotation and high load set as the above-described diagnostic condition. The above step S104
If QV ≧ VA, it is determined that the intake air amount sensor 8 is normal and the process proceeds to step S108, where the backup R
The intake air amount sensor NG flag FLGAFS of AM44 is cleared (FLGAFS ← 0), and the routine exits. If QV <VA in step S104, the value that should be measured by the intake air amount sensor 8 cannot be obtained when the throttle opening is large at high engine speed. Then, it is determined that the intake air amount sensor 8 is abnormal, and the process proceeds to step S109, where the backup RAM 44
NG flag FLGAFS is set (FLGAFS ← 1), the MIL lamp 53 is turned on or blinks to warn the driver, and the routine exits. On the other hand, if NE ≦ NEH1 in the above-mentioned step S102 and it is not in the high rotation range, the process branches from the above-mentioned step S102 to step S105 in order to check whether or not the diagnosis condition of low rotation and low load is satisfied. The engine speed NE is compared with a set value NEL1 on the low speed side. Then, the above step S105
If NE ≧ NEL1, the process exits the routine. If NE <NEL1, the process proceeds to step S106, where the output voltage θV of the throttle sensor 9 is compared with a set value VL1 (VL1 <VH1) on the low opening side, and θV If ≧ VL1, it is determined that the diagnostic condition is not satisfied, and the routine exits. If θV <VL1, it is determined that the low-rotation low-load diagnostic condition is satisfied, and the process proceeds to step S107 to execute the diagnosis of the intake air amount sensor 8. . In step S107, the output voltage QV of the intake air amount sensor 8 is changed to a second determination value VB (in this embodiment, VB>
VA (see FIG. 5). However, VB = VA or VB <VA may be set depending on the characteristics of the intake air amount sensor and the like. )
Compare with The second determination value VB is obtained by an experiment or the like to obtain an output value that can be taken by the intake air amount sensor 8 under a low-rotation low-load diagnosis condition. Equivalent to the value. If QV.ltoreq.VB, the intake air amount sensor 8 is determined to be normal, and the routine exits through step S108 described above. If QV> VB, the intake air amount sensor 8 is determined to be abnormal. Then, the process proceeds to step S109, where the NG flag FLGAFS of the intake air amount sensor in the backup RAM 44 is set, and
The L lamp 53 is turned on or blinks to warn the driver, and the routine exits. Next, a failure diagnosis routine for the throttle sensor 9 shown in FIG. 2 will be described. In this routine, in step S201, the intake air amount sensor NG flag F
Referring to LGAFS, FLGAFS = 1 (intake air amount sensor 8
If it is abnormal, the routine exits from the routine and the diagnosis of the throttle sensor 9 is stopped. If FLGAFS = 0 (the intake air amount sensor 8 is normal), the routine proceeds to step S202, where the engine speed NE is set to the high rotation side. Compare with the value NEH2. If NE> NEH2, the above steps are performed.
Proceeding from S202 to step S203, the output voltage QV of the intake air amount sensor 8 is compared with the set value VH2 on the high air amount side, and QV ≦
In the case of VH2, it is determined that the diagnosis condition of the high rotation and high load is not satisfied, and the routine is exited. Proceed to S204. In step S204, the output voltage θV of the throttle sensor 9 is set to the minimum value of the throttle opening which should be under the condition of high rotation and high load based on the engine speed NE and the output voltage QV of the intake air amount sensor 8. It is compared with the corresponding third determination value VC (see FIG. 6). As a result, when θV ≧ VC, it is determined that the throttle sensor 9 is normal, and the process proceeds to step S208, where the throttle sensor NG flag FLGTHS in the backup RAM 44 is cleared and (FLGTHS
← 0) Exit the routine. If θV <VC, there is an inconsistent result that the throttle opening is small at the time of high rotation and high load. Therefore, it is determined that the throttle sensor 9 is abnormal, and the process proceeds from step S204 to step S209. , Backup RAM
The throttle sensor NG flag FLGTHS of 44 is set (FLGTHS ← 1), and the MIL lamp 53 is turned on or blinks to warn the driver and exit the routine. On the other hand, if it is determined in step S202 that NE ≦ NEH2 and the engine speed is not in the high rotation range, the process branches from step S202 to step S205 in order to check whether the low rotation and low load diagnostic condition is satisfied. Then, the engine speed NE is compared with the set value NEL2 on the low rotation side. If NE ≧ NEL2, the routine is exited. If NE <NEL2, the routine proceeds to step S206, where the output voltage QV of the intake air amount sensor 8 is output. Is compared with a set value VL2 (VL2 <VH2) on the low air amount side. And QV ≧
In the case of VL2, it is determined that the diagnostic condition is not satisfied, and the process exits the routine. In the case of QV <VL2, it is determined that the low-rotation low-load diagnostic condition is satisfied, and the process proceeds to step S207 to execute the diagnosis of the throttle sensor 9. In step S207, the output voltage θV of the throttle sensor 9 is set to a fourth determination value VD (VD> VC in this embodiment (VD> VC (see FIG. 6)) corresponding to the maximum value of the throttle opening which should be at low rotation and low load. However, VD = VC or VD <VC may be set according to the characteristics of the throttle sensor, etc.), and if θV ≦ VD, it is determined that the operation is normal and the routine proceeds through the above-described step S208. And θV> VD
In the case where the contradictory result that the throttle opening is large despite the low rotation speed and the low load is obtained, the throttle sensor 9 is determined to be abnormal, and the process proceeds to step S209 described above.
The throttle sensor NG flag FLGTHS of the backup RAM 44 is set, and the MIL lamp 53 is turned on or blinks to warn the driver and exit the routine. Thus, even when the outputs of the intake air amount sensor 8 and the throttle sensor 9 are inconsistent, accurate diagnosis can be performed to prevent erroneous diagnosis and reliability can be further improved. As described above, according to the present invention, when each of the failure diagnosis processes is performed by using the output values of the throttle sensor and the intake air amount sensor, the failure diagnosis results are determined.
Failure to intake air flow sensor based on corresponding flag
Between the diagnostic process and the fault diagnostic process for the throttle sensor
Diagnosis is performed from one of the processes, and if one is determined to be abnormal by referring to the flag , the diagnosis is stopped, and the intake air to be executed when the throttle sensor is determined to be normal is performed. In the diagnosis of the amount sensor, when the output value of the intake air amount sensor is smaller than the first determination value at the time of high rotation and high load, or when the output value of the intake air amount sensor is larger than the second determination value at the time of low rotation and low load, it is determined to be abnormal. In the diagnosis of the throttle sensor performed when the intake air amount sensor is determined to be normal, the output value of the throttle sensor is
The output value of the intake air amount sensor and the output value of the throttle sensor are inconsistent with each other when the engine speed is smaller than the third determination value at the time of high rotation and high load or when the rotation speed is larger than the fourth determination value at the time of low rotation and low load. In such a case, an erroneous diagnosis can be prevented, an abnormality can be reliably determined, and excellent effects such as improvement in reliability can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flowchart of an intake air amount sensor failure diagnosis routine. FIG. 2 is a flowchart of a throttle sensor failure diagnosis routine. FIG. 3 is a schematic configuration diagram of an engine system. FIG. 4 is a circuit of an electronic control system. Configuration diagram [Fig. 5] Output characteristic diagram of intake air amount sensor [Fig. 6] Output characteristic diagram of throttle sensor [Explanation of symbols] 8 Intake air amount sensor 9 Throttle sensor NE Engine speed QV Output voltage (intake air amount sensor Output value) θV Output voltage (output value of throttle sensor) VA First judgment value VB Second judgment value VC Third judgment value VD Fourth judgment value

──────────────────────────────────────────────────の Continuation of the front page (51) Int.Cl. ⁷ identification code FI F02D 41/22 310 F02D 41/22 310K (58) Investigation field (Int.Cl. ⁷ , DB name) F02D 45/00 F02D 41 / 00-41/40 F02B 77/08

Claims (1)

Claims: 1. An engine control for alternately executing a failure diagnosis process for an intake air amount sensor for detecting an intake air amount and a failure diagnosis process for a throttle sensor for detecting a throttle opening. A method of detecting abnormality of a sensor, the method comprising :
Diagnosis of the corresponding flag and the throttle sensor
Based on the flag corresponding to the determination result of
Failure diagnosis processing for the air volume sensor and the throttle sensor
Diagnosis from either one of failure diagnosis processing
In the failure diagnosis process for the intake air amount sensor, the determination result of the failure diagnosis for the throttle sensor
While referring to the flag corresponding to , the diagnosis is stopped when the throttle sensor is determined to be abnormal,
When it is determined that the throttle sensor is normal, a diagnosis is executed, and the output value of the intake air amount sensor at the time of high rotation and high load based on the engine speed and the output value of the throttle sensor is set to a first value. If the output value of the intake air amount sensor at low rotation and low load based on the engine speed and the output value of the throttle sensor is larger than a second determination value, It is determined that the air amount sensor is abnormal, and in the failure diagnosis processing for the throttle sensor, the result of the failure diagnosis for the intake air amount sensor is determined.
With reference to the flag corresponding to the above, while the diagnosis is stopped when the intake air amount sensor is determined to be abnormal,
When it is determined that the intake air amount sensor is normal, a diagnosis is performed, and the output value of the throttle sensor at the time of high rotation and high load based on the engine speed and the output value of the intake air amount sensor is set to the third value. 3, or when the output value of the throttle sensor at low rotation and low load based on the engine speed and the output value of the intake air amount sensor is larger than the fourth determination value. An abnormality detection method for an engine control sensor, characterized in that it is determined that the throttle sensor is abnormal.