JP2006348778A - Abnormality diagnosis device for pressure sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately determine existence of abnormality of an upstream side intake air pressure sensor, a downstream side intake air pressure sensor, and an atmospheric pressure sensor. <P>SOLUTION: A detection value of the upstream side intake air pressure sensor 15, a detection value of the downstream side intake air pressure 19, and a detection value of the atmospheric air pressure sensor 35 are compares during engine stop to determine existence of abnormality of the three pressure sensors (the upstream side intake air pressure sensor 15, the downstream side intake air pressure sensor 19 and the atmospheric air pressure sensor 35). Since pressure in an intake pipe 12 is roughly atmospheric pressure during engine stop, detection values of three pressure sensors are roughly same when all three pressure sensors are normal, the detection value of an abnormal pressure sensor becomes different from detection values of other two normal pressure sensors. Consequently, if the detection values of three pressure sensors are compared during engine stop, existence of abnormality of the three pressure sensors can be accurately determined. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an abnormality diagnosis device for a pressure sensor that determines the presence or absence of abnormality of an intake pressure sensor or the like of an internal combustion engine.

As a conventional abnormality diagnosis technique for an intake pressure sensor, for example, as described in Patent Document 1 (Japanese Patent Laid-Open No. 60-4838), a low pressure intake pressure sensor and a high pressure sensor are provided in an intake passage of an internal combustion engine. If the detection value VPBTC of the high-pressure intake pressure sensor is lower than the predetermined value VPBTC17 and the detection value VPBNA of the low-pressure intake pressure sensor is higher than the determination value VPBNAH, When the detection value VPBNA of the low pressure intake pressure sensor is higher than the predetermined value VPBNA17, the detection value VPBTC of the high pressure intake pressure sensor is determined from the determination value VPBTCL. If the value is too low, it is determined that there is an abnormality in the high-pressure intake pressure sensor.
JP-A-60-4838 (Page 4 etc.)

  However, in the abnormality diagnosis technique disclosed in Patent Document 1, abnormality diagnosis of the other intake pressure sensor is performed on the basis of the detection value of one intake pressure sensor of the two intake pressure sensors. When an abnormality occurs in the sensor, an abnormality diagnosis of the other intake pressure sensor (normal sensor) is performed based on the abnormal detection value of one intake pressure sensor, and the other intake pressure sensor is normal. Nevertheless, there is a possibility of misdiagnosing that there is an abnormality.

  The present invention has been made in view of such circumstances. Accordingly, an object of the present invention is to provide a pressure sensor abnormality diagnosis device that can accurately determine the presence or absence of abnormality of a plurality of pressure sensors. There is.

  In order to achieve the above object, the invention according to claim 1 detects the atmospheric pressure by the first intake pressure sensor and the second intake pressure sensor which are two pressure sensors for detecting the intake pressure of the internal combustion engine. This is applied to a system including an atmospheric pressure sensor that is a pressure sensor, and the detected values of the three pressure sensors are compared when the internal combustion engine is stopped or started, and the presence or absence of abnormality of the three pressure sensors is determined. Is.

  When the internal combustion engine is stopped or started (for example, immediately after the ignition switch is turned on, the internal combustion engine is not yet rotating or is taking very little rotation), the pressure in the intake passage is almost atmospheric pressure. Therefore, when all of the three pressure sensors (the first intake pressure sensor, the second intake pressure sensor, and the atmospheric pressure sensor) are normal, the detection values of these three pressure sensors are substantially equivalent to the atmospheric pressure. If any one of the pressure sensors becomes abnormal, the detected value of the abnormal pressure sensor becomes different from the detected values of the other two normal pressure sensors. Therefore, when the internal combustion engine is stopped or started, the detection values of the three pressure sensors are compared, and if the detection values of the three pressure sensors are determined to be substantially the same, it can be determined that all three pressure sensors are normal. On the other hand, when it is determined that the detection values of the three pressure sensors do not match, by selecting a pressure sensor having a different detection value from the detection values of the three pressure sensors, an abnormal condition is detected from the three pressure sensors. The pressure sensor can be specified, and it can be prevented that a normal pressure sensor is erroneously diagnosed as having an abnormality.

  Specifically, as in claim 2, the coincidence / disagreement of the detection values of the three pressure sensors is determined by majority calculation, and two or more pressure sensors determined to match the detection values are regarded as normal pressure sensors. The pressure sensor that is determined and the detected value is determined to be inconsistent may be determined as an abnormal pressure sensor. In this way, when any one of the pressure sensors becomes abnormal, the abnormal pressure sensor can be accurately identified by majority calculation.

  By the way, immediately after the internal combustion engine is stopped, the pressure in the intake passage may not be close to the atmospheric pressure. There is a possibility of misdiagnosing the presence or absence of sensor abnormality.

  Therefore, as described in claim 3, it is preferable to perform abnormality diagnosis of the three pressure sensors during stoppage or start-up after a predetermined time has elapsed since the internal combustion engine was stopped. In this way, after the internal combustion engine is stopped, a predetermined time required for the pressure in the intake passage to become almost atmospheric pressure has passed, and the pressure in the intake passage has been reliably made almost atmospheric. Thus, the abnormality diagnosis of the three pressure sensors can be executed, and the reliability of the abnormality diagnosis of the pressure sensor can be improved.

  According to a fourth aspect of the present invention, the turbocharger includes a supercharger that supercharges intake air with a compressor provided upstream of the throttle valve in the intake passage of the internal combustion engine. The present invention may be applied to a system in which the intake pressure between the compressor and the throttle valve is detected, and the second intake pressure sensor detects the intake pressure downstream of the throttle valve. In this way, the upstream intake pressure sensor (first intake pressure sensor) that detects the intake pressure (so-called supercharging pressure) between the compressor and the throttle valve of the internal combustion engine with a supercharger, and the throttle valve downstream It is possible to accurately determine whether there is an abnormality in the downstream side intake pressure sensor (second intake pressure sensor) that detects the side intake pressure.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
First, a schematic configuration of the entire engine control system will be described with reference to FIG. An air cleaner (not shown) is provided at the uppermost stream portion of the intake pipe 12 (intake passage) of the engine 11 that is an internal combustion engine, and an air flow meter 13 for detecting the intake air amount is disposed downstream of the air cleaner. An intake air temperature sensor 14 for detecting the air temperature is provided. On the downstream side of the air flow meter 13 and the intake air temperature sensor 14, a compressor 26 of an exhaust turbine drive supercharger 24 described later and an intercooler 27 for cooling the intake air pressurized by the compressor 26 are provided. An upstream intake pressure sensor 15 (first intake pressure sensor) that detects an intake pressure upstream of the throttle valve 16 (so-called supercharging pressure) is provided downstream of the intercooler 27. An intake air temperature sensor may be provided integrally with the upstream intake pressure sensor 15. On the downstream side of the upstream intake pressure sensor 15, a throttle valve 16 whose opening is adjusted by a motor or the like and a throttle opening sensor 17 for detecting the opening (throttle opening) of the throttle valve 16 are provided. ing.

  Further, a surge tank 18 is provided on the downstream side of the throttle valve 16, and a downstream intake pressure sensor 19 (second intake pressure sensor) that detects the intake pressure downstream of the throttle valve 16 is provided in the surge tank 18. Is provided. The surge tank 18 is provided with an intake manifold 20 for introducing air into each cylinder of the engine 11, and a fuel injection valve 21 for injecting fuel is attached in the vicinity of the intake port of the intake manifold 20 of each cylinder. Yes. A spark plug 22 is attached to each cylinder of the cylinder head of the engine 11, and the air-fuel mixture of each cylinder is ignited by spark discharge of each spark plug 22.

  An exhaust turbine driven supercharger 24 is mounted on the engine 11. In the supercharger 24, an exhaust turbine 25 is disposed in the exhaust pipe 23, and a compressor 26 is disposed between the air flow meter 13 and the throttle valve 16 in the intake pipe 12. In the supercharger 24, an exhaust turbine 25 and a compressor 26 are connected, and the exhaust turbine 25 is rotationally driven by the kinetic energy of exhaust gas, whereby the compressor 26 is rotationally driven to supercharge intake air. .

  Further, the intake pipe 12 is provided with an intake bypass passage 28 that bypasses the upstream side and the downstream side of the compressor 26 on the upstream side of the throttle valve 16. An air bypass valve 29 is provided. On the other hand, the exhaust pipe 23 is provided with an exhaust bypass passage 30 that bypasses the upstream side and the downstream side of the exhaust turbine 25, and a waste gate valve 31 that opens and closes the exhaust bypass passage 30 is provided in the middle of the exhaust bypass passage 30. Is provided.

  A cooling water temperature sensor 32 that detects the cooling water temperature and a crank angle sensor 33 that outputs a pulse signal each time the crankshaft of the engine 11 rotates a predetermined crank angle are attached to the cylinder block of the engine 11. Based on the output signal of the crank angle sensor 33, the crank angle and the engine speed are detected. The accelerator sensor 34 detects the amount of depression of the accelerator pedal (accelerator opening), and the atmospheric pressure sensor 35 detects the atmospheric pressure. The atmospheric pressure sensor 35 is disposed in a case of an ECU 36 described later.

  The outputs of the various sensors described above are input to an engine control circuit (hereinafter referred to as “ECU”) 36. The ECU 36 is mainly composed of a microcomputer, and executes various engine control programs stored in a built-in ROM (storage medium) to thereby determine the fuel injection amount of the fuel injection valve 21 according to the engine operating state. The ignition timing of the spark plug 22 is controlled.

  Further, the ECU 36 executes a pressure sensor abnormality diagnosis routine of FIGS. 2 and 3 to be described later, so that the detection value MAP1 of the upstream intake pressure sensor 15 and the detection of the downstream intake pressure sensor 19 are detected while the engine 11 is stopped. The value MAP2 is compared with the detected value ATP of the atmospheric pressure sensor 35, and the upstream side intake pressure sensor 15, the downstream side intake pressure sensor 19 and the atmospheric pressure sensor 35 are determined by majority decision to determine whether the detected values match or not. Determine if there is an abnormality. In order to execute the pressure sensor abnormality diagnosis while the engine is stopped, the ECU 36 is continuously energized for a while after the IG switch (ignition switch) (not shown) is turned off.

  While the engine 11 is stopped, the pressure in the intake pipe 12 is almost atmospheric pressure, so all three pressure sensors (upstream intake pressure sensor 15, downstream intake pressure sensor 19, and atmospheric pressure sensor 35) are all. In the normal case, the detected values of these three pressure sensors coincide with each other at a pressure corresponding to almost atmospheric pressure. If any one of the pressure sensors becomes abnormal, the detected value of the abnormal pressure sensor is different from the other. The detected values of the two normal pressure sensors are different. Focusing on this point, in the present embodiment, when the engine 11 is stopped, two or more pressures that are determined to be coincident with each other are determined by majority calculation by determining majority or non-matching of the detection values of the three pressure sensors. The sensor is determined to be a normal pressure sensor, and the pressure sensor whose detected value is determined to be inconsistent is determined to be an abnormal pressure sensor.

  Hereinafter, processing contents of the pressure sensor abnormality diagnosis routine of FIGS. 2 and 3 executed by the ECU 36 will be described.

  The pressure sensor abnormality diagnosis routine shown in FIGS. 2 and 3 is executed at a predetermined cycle while the ECU 36 is turned on, and serves as abnormality diagnosis means in the claims. When this routine is started, first, at step 101, it is determined whether or not the engine 11 has been stopped, for example, by whether or not the IG switch has been turned off.

  If it is determined in step 101 that the engine 11 has not been stopped (that is, the engine is operating), the process proceeds to step 102 without executing the processing related to the pressure sensor abnormality diagnosis in and after step 103, and the engine is stopped. The count value of the counter Cnt that measures time (elapsed time since the engine 11 was stopped) is reset to “0”, and this routine is finished.

  Thereafter, when it is determined in step 101 that the engine 11 has been stopped, the processing relating to the pressure sensor abnormality diagnosis after step 103 is executed as follows. First, in step 103, after the count value of the counter Cnt for measuring the engine stop time is counted up, the process proceeds to step 104, and it is determined whether or not the count value (engine stop time) of the counter Cnt exceeds a predetermined value CONST. . The predetermined value CONST is set to a predetermined time required for the pressure in the intake pipe 12 to be almost atmospheric pressure after the engine 11 is stopped.

  If it is determined in step 104 that the count value (engine stop time) of the counter Cnt does not exceed the predetermined value CONST, there is a possibility that the pressure in the intake pipe 12 has not yet become close to the atmospheric pressure. It is determined that there is, and this routine is finished as it is.

Thereafter, when it is determined in step 104 that the count value (engine stop time) of the counter Cnt has exceeded the predetermined value CONST, it is determined that the pressure in the intake pipe 12 has become substantially atmospheric pressure, and the step of FIG. Proceeding to 105, the detected value MAP1 of the upstream intake pressure sensor 15, the detected value MAP2 of the downstream intake pressure sensor 19, and the detected value ATP of the atmospheric pressure sensor 35 are compared to determine whether these three detected values match or not. The majority operation is performed as follows. First, deviations (degrees of deviation) ΔMAP1, ΔMAP2, and ΔATP are calculated for the detected values MAP1, MAP2, and ATP of the respective pressure sensors. Specifically, with respect to the detection values MAP1, MAP2, and ATP of the respective pressure sensors, absolute values of differences from the average values of the detection values of the other two pressure sensors are obtained, and these are obtained as deviations ΔMAP1 of the detection values of the respective pressure sensors. , ΔMAP 2, ΔATP.
ΔMAP 1 = | MAP 1 − (MAP 2 + ATP) / 2 |
ΔMAP2 = | MAP2− (MAP1 + ATP) / 2 |
ΔATP = | ATP− (MAP1 + MAP2) / 2 |

  Thereafter, the routine proceeds to step 106, where it is determined whether or not the deviation ΔMAP1 of the detected value of the upstream side intake pressure sensor 15 is larger than the determination value TMap1 set according to the maximum allowable detection error of the upstream side intake pressure sensor 15. If it is determined that the deviation ΔMAP1 of the detection value of the upstream intake pressure sensor 15 is larger than the determination value TMap1, the detection value MAP1 of the upstream intake pressure sensor 15 is inconsistent with the detection values of the other two pressure sensors. If it is determined that there is, the routine proceeds to step 109, where it is determined that the upstream side intake pressure sensor 15 is abnormal.

  On the other hand, when it is determined in step 106 that the deviation ΔMAP1 of the detection value of the upstream intake pressure sensor 15 is equal to or smaller than the determination value TMap1, the process proceeds to step 107 and the detection of the downstream intake pressure sensor 19 is performed. It is determined whether or not the deviation ΔMAP2 of the value is larger than a determination value TMap2 set according to the maximum allowable detection error of the downstream side intake pressure sensor 19, and the deviation ΔMAP2 of the detection value of the downstream side intake pressure sensor 19 is determined. If it is determined that the value is greater than the value TMap2, it is determined that the detected value MAP2 of the downstream intake pressure sensor 19 is inconsistent with the detected values of the other two pressure sensors, and the routine proceeds to step 110, where the downstream intake pressure is determined. It is determined that the sensor 19 is abnormal.

  If it is determined in step 107 that the deviation ΔMAP2 of the detection value of the downstream intake pressure sensor 19 is equal to or smaller than the determination value TMap2, the process proceeds to step 108 where the deviation ΔATP of the detection value of the atmospheric pressure sensor 35 is It is determined whether or not the determination value TAtp set in accordance with the maximum allowable detection error of the atmospheric pressure sensor 35 is larger, and it is determined that the deviation ΔATP of the detection value of the atmospheric pressure sensor 35 is larger than the determination value TAtp. In this case, it is determined that the detection value ATP of the atmospheric pressure sensor 35 is inconsistent with the detection values of the other two pressure sensors, the process proceeds to step 111, and it is determined that the atmospheric pressure sensor 35 is abnormal.

  On the other hand, in step 106, it is determined that the deviation ΔMAP1 of the detection value of the upstream intake pressure sensor 15 is equal to or smaller than the determination value TMap1, and in step 107, the deviation ΔMAP2 of the detection value of the downstream intake pressure sensor 19 is determined as the determination value. If it is determined that it is equal to or less than TMap2, and it is determined in step 108 that the deviation ΔATP of the detection value of the atmospheric pressure sensor 35 is equal to or less than the determination value TAtp, the detection value MAP1 of the upstream intake pressure sensor 15 and It is determined that the detected value MAP2 of the downstream side intake pressure sensor 19 and the detected value ATP of the atmospheric pressure sensor 35 coincide with each other, the process proceeds to step 112, and the upstream side intake pressure sensor 15, the downstream side intake pressure sensor 19, and the atmospheric pressure sensor 35 are advanced. Are all normal.

  In the present embodiment described above, paying attention to the fact that the pressure in the intake pipe 12 is substantially atmospheric pressure while the engine 11 is stopped, the detection of the upstream intake pressure sensor 15 while the engine 11 is stopped. By comparing the value MAP1, the detection value MAP2 of the downstream intake pressure sensor 19 with the detection value ATP of the atmospheric pressure sensor 35, and determining the coincidence / mismatch of these three detection values, the upstream intake pressure sensor 15 Since the presence / absence of abnormality of the downstream side intake pressure sensor 19 and the atmospheric pressure sensor 35 is determined, the presence / absence of abnormality of the three pressure sensors can be accurately determined. Thereby, when there is an abnormal pressure sensor, the abnormal pressure sensor can be specified, and it can be prevented that a normal pressure sensor is erroneously diagnosed as having an abnormality.

  In addition, in the present embodiment, when the majority operation is performed, whether or not the absolute value of the difference between the detection value of each pressure sensor and the average value of the detection values of the other two pressure sensors is equal to or greater than the determination value, Since the detection value of each pressure sensor is inconsistent with the detection value of the other two pressure sensors, an abnormal pressure sensor is identified, so if any of the pressure sensors is abnormal There is an advantage that the abnormal pressure sensor can be easily and accurately specified by majority calculation.

  Further, in this embodiment, since the abnormality diagnosis of the three pressure sensors is executed during the stop after a predetermined time has elapsed since the engine 11 was stopped, the intake pipe 11 is stopped after the engine 11 is stopped. The abnormality diagnosis of the three pressure sensors can be executed in a state where the predetermined time required for the internal pressure to become almost atmospheric pressure has elapsed and the pressure in the intake pipe 12 has become almost atmospheric pressure. It is possible to improve the reliability of pressure sensor abnormality diagnosis.

  In the above embodiment, the abnormality diagnosis of the three pressure sensors is executed while the engine 11 is stopped. However, when the engine 11 is started (for example, immediately after the IG switch is turned on, the engine 11 is still rotating). Abnormal diagnosis of the three pressure sensors may be executed at the time of extremely low rotation with little or no intake.

  Further, in the above-described embodiment, when the majority calculation for determining the coincidence / mismatch of the detection values of the three pressure sensors is performed, the difference between the detection value of each pressure sensor and the average value of the detection values of the other two pressure sensors. Is calculated, but the ratio between the detection value of each pressure sensor and the average value of the detection values of the other two pressure sensors is calculated. A mismatch may be determined. Or, for each of the three types of combinations for selecting two pressure sensors from among the three pressure sensors, whether the difference between the detected values of the two pressure sensors is less than or equal to a determination value is determined. It is determined whether or not the detected values match (whether or not the two pressure sensors are normal), and the abnormal pressure sensor that does not match the detected values is identified from the determination results of the three types of combinations. For example, the method for identifying an abnormal pressure sensor in which detected values do not match among the three pressure sensors may be appropriately changed.

  The scope of application of the present invention is not limited to the supercharged engine 11 provided with an exhaust turbine drive supercharger (so-called turbocharger), and other machine drive supercharger (so-called supercharger) and the like. The present invention may be applied to a supercharged engine having a supercharger of a system or a naturally aspirated engine not having a supercharger. The present invention includes two intake pressure sensors and an atmospheric pressure sensor. It can be widely applied to various systems.

It is a schematic block diagram of the whole engine control system in one Example of this invention. It is a flowchart (the 1) which shows the flow of a process of a pressure sensor abnormality diagnosis routine. It is a flowchart (the 2) which shows the flow of a process of a pressure sensor abnormality diagnosis routine.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Engine (internal combustion engine), 12 ... Intake pipe (intake passage), 15 ... Upstream intake pressure sensor (first intake pressure sensor), 16 ... Throttle valve, 19 ... Downstream intake pressure sensor (second intake) Pressure sensor), 21 ... fuel injection valve, 22 ... spark plug, 23 ... exhaust pipe, 24 ... supercharger, 25 ... exhaust turbine, 26 ... compressor, 35 ... atmospheric pressure sensor, 36 ... ECU (abnormality diagnosis means)

Claims (4)

Applied to a system including two intake pressure sensors that detect two intake pressures of an internal combustion engine, a first intake pressure sensor and a second intake pressure sensor, and an atmospheric pressure sensor that is a pressure sensor that detects atmospheric pressure;
An abnormality diagnosing device for a pressure sensor, comprising abnormality diagnosing means for comparing the detected values of the three pressure sensors when the internal combustion engine is stopped or started to determine whether or not the three pressure sensors are abnormal. .   The abnormality diagnosing means determines whether the detected values of the three pressure sensors match or not by majority decision, determines two or more pressure sensors determined to match the detected values as normal pressure sensors, and detects the detected values. The pressure sensor abnormality diagnosing device according to claim 1, wherein a pressure sensor determined to be inconsistent is determined as an abnormal pressure sensor.   3. The pressure according to claim 1, wherein the abnormality diagnosis unit performs abnormality diagnosis of the three pressure sensors during stoppage or start-up after a predetermined time has elapsed since the internal combustion engine was stopped. Sensor abnormality diagnosis device. A supercharger that supercharges intake air with a compressor provided upstream of the throttle valve in the intake passage of the internal combustion engine;
The first intake pressure sensor detects an intake pressure between the compressor and the throttle valve;
4. The pressure sensor abnormality diagnosis device according to claim 1, wherein the second intake pressure sensor detects an intake pressure downstream of the throttle valve. 5.

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