JP3483973B2 - Abnormality detection method of pressure sensor in engine control system - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting an abnormality of a pressure sensor in an engine control system for performing a failure diagnosis on a pressure sensor for alternately detecting an intake pipe pressure and an atmospheric pressure. About. 2. Description of the Related Art In general, a pressure, which is one of the control parameters of an engine, is a high altitude correction of a fuel injection amount corresponding to an atmospheric pressure, or a basic fuel injection amount based on an intake pipe pressure and an engine speed. When an abnormality occurs in the pressure sensor system for detecting the pressure, engine malfunction, deterioration of exhaust emission, and the like are caused. For this reason, many control systems have a failure diagnosis function for detecting an abnormality in the output signal from the pressure sensor.
Japanese Patent Application Laid-Open Publication No. H11-163873 discloses that when the opening of a throttle valve (throttle valve) is at an idling opening and the value of an intake pipe pressure corresponding to an input signal from a pressure sensor for detecting the intake pipe pressure is larger than a predetermined value, Alternatively, the value of the intake pipe pressure corresponding to the input signal from the pressure sensor is calculated as a predetermined function of the engine rotation speed and the throttle valve opening degree when the throttle valve is equal to or less than the predetermined opening degree which is larger than the idling opening degree. A technique has been disclosed in which a signal from a pressure sensor is determined to be abnormal when the value is larger than the measured value. [0004] When both the intake pipe pressure and the atmospheric pressure are used as control parameters, a pressure sensor for detecting the intake pipe pressure and a pressure sensor for detecting the atmospheric pressure are provided. In addition, in addition to providing two pressure sensors, it is necessary to perform abnormality diagnosis for each pressure sensor, which leads to an increase in system cost. On the other hand, if one pressure sensor is used for both the intake pipe pressure detection and the atmospheric pressure detection, depending on the operating conditions, the pressure detection ranges may overlap each other, and erroneous diagnosis may occur at the time of abnormality determination. is there. The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide an accurate diagnosis corresponding to a pressure detection function of a pressure sensor for detecting an intake pipe pressure and an atmospheric pressure to prevent erroneous diagnosis. It is an object of the present invention to provide a method for detecting an abnormality of a pressure sensor in an engine control system capable of performing the above. According to the present invention, a switching valve connected to a pressure sensor is switched every set time to selectively communicate the pressure sensor with a throttle valve downstream side and an atmosphere side. The intake pipe pressure and the atmospheric pressure are set alternately by setting detection flags, and the output value of the throttle sensor that detects the opening of the throttle valve is set with the intake pipe pressure detection flag set. When the output value of the pressure sensor is equal to or greater than the value corresponding to the set pressure, and the output value of the pressure sensor is equal to or greater than the value corresponding to the set pressure, it is determined that the signal from the pressure sensor is abnormal. If the output value of the pressure sensor deviates from a set range including a value corresponding to the set pressure while the atmospheric pressure detection flag is set, Is determined to be abnormal. According to the present invention, in the abnormality diagnosis at the time of detecting the intake pipe pressure, it is checked whether a detection flag indicating the detection of the intake pipe pressure is set, and the detection flag is set to measure the intake pipe pressure. In this state, the output value of the throttle sensor that detects the opening of the throttle valve is equal to or less than the value corresponding to the set opening, the engine speed is equal to or greater than the set speed, and the output value of the pressure sensor is equal to the set pressure. If the value is equal to or more than the corresponding value, it is determined that the signal from the pressure sensor is abnormal. In the abnormality diagnosis at the time of detecting the atmospheric pressure, it is checked whether or not a detection flag indicating the detection of the atmospheric pressure is set, and when the detection flag is set and the atmospheric pressure is measured, the pressure sensor is detected. When the output value deviates from the set range including the value corresponding to the set pressure, it is determined that the signal from the pressure sensor is abnormal. Embodiments of the present invention will be described below with reference to the drawings. 1 is a flowchart of a failure diagnosis routine, FIG. 2 is a flowchart of an intake pipe pressure / atmospheric pressure detection routine, FIG. 3 is a schematic configuration diagram of an engine system, and FIG. 4 is an electronic control system. 5 is an output characteristic diagram of the throttle sensor, and FIG. 6 is an output characteristic diagram of the pressure 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. Also, 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 throttle sensor 9 has a characteristic that its output voltage increases substantially linearly with an increase in the throttle opening. An idle speed control valve (ISCV) 11 is interposed in a bypass passage 10 that connects the upstream side and the downstream side of the throttle valve 5a, and a three-way passage that communicates with the intake manifold 3 is provided. A pressure sensor 13 is connected via an intake pipe pressure / atmospheric pressure switching solenoid valve 12 composed of a valve. The pressure sensor 13 is a sensor for detecting an absolute pressure, and has a characteristic that its output voltage increases substantially linearly with an increase in pressure, as shown in FIG. The intake pipe pressure / atmospheric pressure switching solenoid valve 12 has one port communicated with the atmosphere, closes the atmosphere port in a non-energized state, communicates the pressure sensor 13 with the inside of the intake manifold 3, and energizes the air. At this time, the atmosphere port is released to allow the pressure sensor 13 to communicate with the atmosphere, and the intake pipe pressure / atmospheric pressure switching solenoid valve 12 is turned on by a signal from an electronic control unit 40 (see FIG. 4) described later. , By turning off, one pressure sensor 1
3, the intake pipe pressure downstream of the throttle valve and the atmospheric pressure are measured alternately. Further, an injector 14 is located immediately upstream of each intake port 2a of each cylinder of the intake manifold 3, and a spark plug 15a having a tip exposed to the combustion chamber is attached to the cylinder head 2 for each cylinder. Have been. The ignition coil 15 connected to the ignition plug 15a
The igniter 16 is connected to b. 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 mounted on the cylinder block 1a of the engine 1, and a cooling water temperature sensor 24 faces a cooling water passage 23 which connects 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 faces. A catalytic converter 27 is provided downstream of the FO2 sensor 26a, and a rear O2 sensor (RO2 sensor) 26b faces the downstream of the catalytic converter 27. 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 axially mounted on a crankshaft 1b supported by the cylinder block 1a, and a projection (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 22, a crank angle sensor 29, a cam angle sensor 31, and a vehicle speed sensor 32 are connected to the input ports, and an intake air amount sensor 8, a throttle sensor 9, a pressure sensor 13, a cooling water temperature sensor 24, a FO2 sensor The A / D converter 26a and the RO2 sensor 26b are connected via the A / D converter 49.
9 is supplied with the voltage VB from the battery 51 and the battery voltage is monitored. On the other hand, the I / O interface 45
The igniter 16 is connected to an output port of the ISCV 11, the intake pipe pressure / atmospheric pressure switching solenoid valve 12, and the injector 1 via the drive circuit 48.
4, and an MIL lamp 53 which is arranged on an instrument panel (not shown) and displays various alarms in a concentrated manner is connected. The ROM 42 stores an engine control program, various failure diagnosis programs, and fixed data such as maps, and the RAM 43 stores output signals of the sensors and switches. The processed data and the data processed by the CPU 41 are stored. Also, the backup RAM 44
Stores various learning maps and trouble data. The ignition switch 52 is turned on and off.
The backup power is always supplied from the constant voltage circuit 47 regardless of F, and the ignition switch 52 is
Data is held even in the case of FF. The trouble data can be read out by connecting the serial monitor 60 to the ECU 40 via the connector 54. The serial monitor 60 is disclosed in Japanese Patent Application Laid-Open No.
No. 3131 discloses this in detail. The CPU 41 performs engine control such as fuel injection control and ignition timing control based on signals from the sensors. At this time, the CPU 41 turns on and off the intake pipe pressure / atmospheric pressure switching solenoid valve 12 to alternately measure the atmospheric pressure and the intake pipe pressure, and determines whether the signal from the pressure sensor 13 is normal. . When it is determined that the MIL is normal, each measurement data is adopted as engine control data.
A warning is issued by turning on or blinking the lamp 53, and the corresponding trouble data is stored in the backup RAM 44. Hereinafter, measurement processing of the intake pipe pressure and the atmospheric pressure,
The failure diagnosis processing at the time of pressure measurement will be described with reference to the flowcharts of FIGS. FIG. 2 shows an intake pipe pressure / atmospheric pressure detection routine executed every set time. In step S101, the routine is set to "1" when switching from the atmospheric pressure measurement mode to the intake pipe pressure measurement mode. Intake pipe pressure detection determination flag F1
(Initial value is “0”), and when F1 = 0,
The mode is determined to be the atmospheric pressure measurement mode, and the process proceeds to step S102 and thereafter. If F1 = 1, the mode is determined to be the intake pipe pressure measurement mode, and the process proceeds to step S111 and subsequent steps. In the atmospheric pressure measurement mode after step S102, the output value G1 of the I / O port to the intake pipe pressure / atmospheric pressure switching solenoid valve 12 is set to "1" in step S102, and the intake pipe pressure / atmospheric pressure switching solenoid valve is set. When the air supply port 12 is energized to release the atmosphere port, in step S103, a count value C1 (initial value is set) for counting the elapsed time after the port switching of the intake pipe pressure / atmospheric pressure switching solenoid valve 12 (atmosphere port release). “0”) is counted up (C1 ← C1 + 1). Next, in step S104, the count value C1 is compared with the set value CT1, and it is determined whether or not the set time has elapsed after opening the atmosphere port by switching the intake pipe pressure / atmospheric pressure switching solenoid valve 12 to open the air port. Find out what. as a result,
If the set time has not elapsed since the release of the atmosphere port at C1 ≦ CT1, it is determined that the pressure reaching the pressure sensor 13 is not yet stable, and the measurement is not performed and step S110 is not performed.
Jump to the intake pipe pressure / atmospheric pressure switching solenoid valve 1
When the air port 2 is closed to switch the port on the intake manifold 3 side to the port on the pressure sensor 13 side, after clearing the count value C2 for counting the elapsed time after the port switching ( C2 ←
0), exit the routine. In step S104, C1> CT1
If the set time has elapsed since the release of the atmospheric port, it is determined that the pressure on the pressure sensor 13 can be measured sufficiently stably, and the process proceeds to step S105. When a value P ′ obtained by A / D converting the voltage P and converting it to a pressure value is stored as an atmospheric pressure PA at a predetermined address in the RAM 43, an atmospheric pressure detection flag indicating that the atmospheric pressure measurement is being executed in step S106. FATL is set (FATL ← 1), and the flow advances to step S107. In step S107, the count value C1 is compared with a set value CT2 (CT2> CT1) to check whether or not a set time has elapsed after the start of the atmospheric pressure measurement.
If .ltoreq.CT2, the routine exits through the above-described step S110 to continue the atmospheric pressure measurement. If C1> CT2, the process proceeds to step S108 to end the atmospheric pressure measurement, and the atmospheric pressure detection flag FATL is cleared. (FATL ← 0), and
After setting the intake pipe pressure detection determination flag F1 in step S109 (F1 ← 1), the routine exits from step S110 described above. On the other hand, if F1 = 1 (intake pipe pressure measurement mode) in step S101 and the process proceeds from step S101 to step S111 and subsequent steps, the flow proceeds to step S111 where the intake pipe pressure / atmospheric pressure switching solenoid valve 12 is controlled. The output value G1 of the I / O port is set to "0", the intake pipe pressure / atmospheric pressure switching solenoid valve 12 is de-energized, the atmospheric port is closed, and the port communicating with the intake manifold 3 is opened. Next, at step S112, the count value C2 (the initial value is "0") of the intake pipe pressure / atmospheric pressure switching solenoid valve 12 after the air port is closed is counted up (C2 ← C2 + 1). In step S113, the count value C2 is compared with the set value CS1, and it is determined whether or not the set time has elapsed after the intake pipe pressure / atmospheric pressure switching solenoid valve 12 is switched to release the port communicating with the intake manifold 3. Find out. As a result, if the set time has not elapsed since the port on the intake manifold 3 side was opened with C2 ≦ CS1, it is determined that the intake pipe pressure reaching the pressure sensor 13 has not been stabilized yet. Step S119 without measurement
The process jumps to and clears the count value C1 in the atmospheric pressure measurement mode (C1 ← 0), and exits the routine. In step S113, C2> CS1
If the set time has elapsed since the port on the intake manifold 3 side was released, the pressure sensor 13
It is determined that the intake pipe pressure introduced into the intake port is sufficiently stable, and the process proceeds to step S114, in which the output voltage P of the pressure sensor 13 is A / D converted and the value P ′ converted into a pressure value is taken into the intake port. When the pipe pressure PS is stored at a predetermined address in the RAM 43, in step S115, an intake pipe pressure detection flag FPS indicating that the intake pipe pressure measurement is being executed is set (FPS ← 1), and the routine proceeds to step S116. In step S116, the count value C2 is compared with a set value CS2 (where CS2> CS1) to check whether or not a set time has elapsed after the start of the intake pipe pressure measurement.
If C2 ≦ CS2, the routine exits through the aforementioned step S119 to continue the intake pipe pressure measurement. If C2> CS2, the procedure proceeds to step S117 to terminate the intake pipe pressure measurement, and the intake pipe pressure detection flag is set. Clear FPS (FPS ←
0) Further, after clearing the intake pipe pressure detection determination flag F1 in step S118 (F1 ← 0), the above-described step S11 is performed.
Exit the routine via 9. In response to the intake pipe pressure / atmospheric pressure detection routine described above, the failure diagnosis routine shown in FIG. 1 diagnoses whether or not the signal from the pressure sensor 13 is normal. It is adopted as control data. In executing this failure diagnosis routine, it is assumed that other sensors such as the throttle sensor 9 and the crank angle sensor 29 have been confirmed to be normal by another failure diagnosis. First, in step S201, it is checked whether or not the atmospheric pressure is being measured by referring to the atmospheric pressure detection flag FATL.
If it is determined that the atmospheric pressure is not being measured, the process proceeds to step S202, and it is determined whether or not the intake pipe pressure is being measured with reference to the intake pipe pressure detection flag FPS. In step S202, if FPS = 0 and neither the atmospheric pressure nor the intake pipe pressure is being measured,
If the routine is exited without performing the diagnosis and the intake pipe pressure is being measured at FPS = 1, the process proceeds from step S202 to step S203, where the output voltage TH of the throttle sensor 9 is set to a set value for determining whether the throttle is fully closed. Compared to VD (see FIG. 5), if TH> VD, the routine exits from step S203, and if TH ≦ VD and the throttle is almost fully closed, the process proceeds from step S203 to step S204, where the crank angle sensor The engine speed NE calculated based on the signal from the engine 29 is compared with a set speed NESET. If NE <NESET, the routine exits from step S204, and if NE ≧ NESET,
That is, when the throttle is fully closed and the engine speed is equivalent to coasting at or above the set speed, in step S205, the output voltage P of the pressure sensor 13 is set to the set value VS.
Compare with The set value VS corresponds to the upper limit of the intake pipe pressure (absolute value) in a normal coasting state (see FIG. 6). If P ≦ VS, the pressure sensor 13 is determined to be normal. In step S206, the intake pipe pressure NG flag FLGPR1 in the backup RAM 44 is cleared (FLGPR1 ← 0), and the process proceeds to step S212. If P> VS, an abnormality due to leakage of the pipe, disconnection of the pressure sensor 13, etc. Therefore, it is determined that the measured value of the intake pipe pressure is abnormally high, and the process branches to step S207, where the backup RAM is used.
The intake pipe pressure NG flag FLGPR1 of 44 is set (FLGPR1 ← 1), and the routine proceeds to step S212. On the other hand, at step S201, FATL = 1 (atmospheric pressure measurement is being performed).
If the process proceeds to 8 or later, the output voltage P of the pressure sensor 13 is compared with the set values VA and VC in steps S208 and S209, respectively. These set values VA and VC correspond to the lower limit and the upper limit that the output voltage of the pressure sensor 13 can take at the time of measuring the atmospheric pressure. Usually, the upper limit of the atmospheric pressure is determined by the intake air in the coasting state described above. Although the upper limit of the pipe pressure is higher than the upper limit of the pipe pressure, the lower limit of the atmospheric pressure at the high altitude may be lower than the upper limit of the intake pipe pressure in the coasting state in the low altitude. Da
<VS <VC (see FIG. 6). Then, in step S208, P ≧ VA, and
If P ≦ VC in step S209, it is determined to be normal, and the atmospheric pressure NG flag FLGPR2 is cleared in step S210 (FLGPR2 ← 0), and the process proceeds to step S212. If P <VA in step S208 or P> VC at S209
In the case of, it is determined that an abnormality has occurred due to disconnection of the pressure sensor 13 or the like, and the process proceeds from the corresponding step to step S211 to set the atmospheric pressure NG flag FLGPR2 in the backup RAM 44, and then proceeds to step S212. In and after step S212, a comprehensive judgment of the pressure sensor 13 is made, and in steps S212 and S213, the intake pipe pressure NG flag FLGPR1 and the atmospheric pressure NG flag FLGPR2, respectively.
When both the flags FLGPR1 and FLGPR2 are cleared, it is determined that the pressure sensor system is normal and the process proceeds to step S214, where the pressure sensor NG flag FLGPRES stored in the backup RAM 44 is cleared and (F
LGPRES ← 0), exits the routine. Further, the intake pipe pressure NG flag FLGPR1,
Alternatively, when the atmospheric pressure NG flag FLGPR2 is set, it is determined that the pressure sensor system has failed, and the process proceeds from the corresponding step to step S215, where the backup RAM 4
In addition to setting the pressure sensor NG flag FLGPRES of No. 4, the MIL lamp 53 is turned on or blinked to warn the driver and exit the routine. Each of the NG flags FLGPR1, FLGPR2, FLGPRES stored in the backup RAM 44
Is read out by the above-described serial monitor 60, the failure history for the pressure sensor system can be known. As a result, the system cost can be reduced by using one pressure sensor 13 for both the detection of the intake pipe pressure and the function of detecting the atmospheric pressure. Even when the pressure detection ranges overlap with each other depending on the operating conditions, accurate diagnosis corresponding to the pressure detection function can be performed, erroneous diagnosis can be prevented, and reliability can be further improved. As described above, according to the present invention, in the abnormality diagnosis at the time of detecting the intake pipe pressure, it is checked whether or not a detection flag indicating the detection of the intake pipe pressure is set. When the intake pipe pressure is measured while being set, the output value of the throttle sensor for detecting the opening of the throttle valve is equal to or less than the value corresponding to the set opening, and the engine speed is equal to or more than the set speed, When the output value of the pressure sensor is equal to or greater than the value corresponding to the set pressure, it is determined that the signal from the pressure sensor is abnormal, and in the abnormality diagnosis at the time of atmospheric pressure detection, a detection flag indicating the atmospheric pressure detection is set. Check if this is set, and if this detection flag is set and atmospheric pressure is being measured, and the output value of the pressure sensor deviates from the set range including the value corresponding to the set pressure, Since it is determined that the signal from the pressure sensor is abnormal, the pressure sensor that detects the intake pipe pressure and the atmospheric pressure can be accurately diagnosed corresponding to the pressure detection function to prevent erroneous diagnosis. Excellent effects such as improved reliability can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flowchart of a failure diagnosis routine. FIG. 2 is a flowchart of an intake pipe pressure / atmospheric pressure detection routine. FIG. 3 is a schematic configuration diagram of an engine system. FIG. 4 is a circuit configuration of an electronic control system. FIG. 5: Output characteristic diagram of a throttle sensor FIG. 6: Output characteristic diagram of a pressure sensor [Description of symbols] 5a Throttle valve 9 Throttle sensor 13 Pressure sensor 12 Intake pipe pressure / atmospheric pressure switching solenoid valve (switching valve) FATL Atmospheric pressure detection flag FPS Intake pipe pressure detection flag

Continuation of the front page (56) References JP-A-57-46046 (JP, A) JP-A-63-55347 (JP, A) JP-A-59-128926 (JP, A) JP-A-3-54341 (JP) JP-A-2-256853 (JP, A) JP-A-58-101244 (JP, A) JP-A-57-62944 (JP, A) JP-A-64-35053 (JP, A) 61-27944 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02D 35/00 F02D 45/00 358 F02D 45/00 368

Claims (1)

(57) [Claim 1] A switching valve connected to a pressure sensor is switched at every set time to selectively communicate the pressure sensor with the downstream side of the throttle valve and the atmosphere side, so that the intake air is reduced. The pipe pressure and the atmospheric pressure are set alternately by setting a detection flag, and the output value of the throttle sensor for detecting the opening of the throttle valve is set to the set opening with the detection flag of the intake pipe pressure set. If the output value of the pressure sensor is equal to or greater than the value corresponding to the set pressure, the signal from the pressure sensor is determined to be abnormal, If the output value of the pressure sensor is out of the set range including the value corresponding to the set pressure while the atmospheric pressure detection flag is set, the signal from the pressure sensor is abnormal. Abnormality detection method of the pressure sensor in the engine control system and determining that that.