JP7129091B2 - Responsive Diagnosis Method of Pressure Sensor Used for Engine Control - Google Patents

Description

The present invention relates to a method of diagnosing the responsiveness of a pressure sensor used for engine control in the intake system and exhaust system of a spark ignition engine.

Conventionally, as a means of improving fuel efficiency and driving performance in a spark ignition type engine mounted on a vehicle, for example, an electronic control system is used instead of opening and closing the throttle mechanically by operating the accelerator by the driver. Electronically controlled throttle controllers that electronically open and close a throttle are widely used, and are described in, for example, Japanese Patent Application Laid-Open No. 5-240073 and Japanese Patent Application Laid-Open No. 2008-38872.

In the electronically controlled throttle control device, the fuel and air taken into the engine are controlled for the purpose of controlling the air-fuel ratio of the engine by an electronic control unit device (hereinafter referred to as "ECU") in order to perform engine control with high accuracy. A pressure sensor is used in the intake system and the exhaust system to measure the pressure of the mixed gas and the pressure of the exhaust gas. There is a problem that the pressure measuring part is clogged with substances such as fuel, engine oil, etc., so that the pressure cannot be measured accurately, and in case of failure, the engine cannot be controlled.

Therefore, as a means of diagnosing the responsiveness of the pressure sensor used for engine control without changing the structure of the pressure sensor or attaching mechanical parts, the engine is diagnosed by the ECU JP-A-2018-71374. Presented in publications, etc.

The means for diagnosing the responsiveness of the pressure sensor used for engine control presented in these publications is, for example, an intake manifold arranged in the intake manifold 2 of the engine as shown in FIG. A manifold pressure sensor [Pmap] is connected to the ECU 3 and input to the microcomputer 4 to control the engine based on information from the intake manifold pressure sensor [Pmap]. The pressure sensor response diagnostic circuit 8 determines whether the responsiveness of the sensor [Pmap] ensures appropriate performance. is performed a plurality of times for each predetermined period, and the difference in pressure detected by the intake manifold intake pressure sensor [Pmap] during one opening and closing operation is calculated as a pressure change amount, and a plurality of the above The responsiveness of the intake manifold pressure sensor [Pmap] is diagnosed by comparing the amount of pressure change for each opening/closing operation.

As another means for diagnosing the responsiveness of the intake manifold pressure sensor [Pmap] in the diagnostic means shown in FIG. The opening sensor information signal (TH) of the throttle valve 6 is detected, and the rise time of the intake manifold pressure sensor [Pmap] is measured from the time when the throttle valve 6 starts to open. , intake manifold pressure sensor [Pmap] When the responsiveness of the sensor is degraded, the time difference becomes .DELTA.T2. Therefore, if the time difference increases, it is determined that the responsiveness is degraded and a failure is determined.

However, the conventional method for diagnosing the responsiveness of a pressure sensor using the ECU 3 triggers the start of diagnosis as a transitional condition of acceleration or deceleration. Therefore, the transient conditions may not be uniform, and the diagnostic results vary widely, making it difficult to determine the correct responsiveness of the pressure sensor.

JP-A-5-240073 JP 2008-38872 A JP 2018-71374 A

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and provides various pressure sensors for preventing the inability to accurately measure pressure sensors used for engine control in the intake system or exhaust system of an engine. An object of the present invention is to provide a responsive diagnostic method.

The present invention, which has been made to solve the above problems, is a method for diagnosing the responsiveness of a pressure sensor provided in an intake system or an exhaust system of an engine used for spark ignition type engine control, comprising: The pressure sensor signal information, which is the pressure pulsation amplitude generated in the intake system or the exhaust system of the engine by the intake or exhaust accompanying the reciprocating motion of the engine, is measured, and the measured pressure sensor signal information is sent to an analog The pressure pulsation amplitude in the high frequency band detected by the pressure sensor is converted into an index value by a filter circuit and a digital filter circuit through band-pass filter processing and absolute value processing, and the pressure measured in the normal state is obtained. The sensor signal information is subjected to band-pass filter processing and absolute value processing by the analog filter circuit and the digital filter circuit, and a normal index value obtained by converting the pressure pulsation amplitude in the high frequency band detected by the pressure sensor into an index value. , and if the measurement index value is lower than or equal to a predetermined responsive failure diagnosis threshold value that is the normal index value, it is determined that the responsiveness of the pressure sensor has deteriorated leading to a failure, and the When the measurement index value is higher than the predetermined responsive failure diagnosis threshold value, which is the normal index value, it is determined that the responsiveness of the pressure sensor is normal . It is characterized by judging the presence or absence of deterioration of responsiveness, and by comparing the measurement index value with the normal index value converted from the pressure sensor signal information in the normal state, the deterioration of responsiveness can be reliably detected. The presence or absence can be determined.

Further, in the present invention, when the pressure sensor signal information is processed by the analog filter circuit and the digital filter circuit , after the absolute value processing, it is smoothed by weighted average processing, and furthermore, in a specific driving cycle, By updating the maximum value with the maximum value update process and converting it into an index value, not only a specific operating condition but also various operating conditions can be determined with one index to reduce the measurement. can do.

Furthermore, in the present invention, based on the engine rotation information and the accelerator opening information, which operating conditions are experienced for how long are counted, and from the total value of the counts, whether or not the assumed operating conditions have been experienced. If the determination is true, a determination process is performed to set the operating condition experience flag to "true", and the measurement index value is lower than a predetermined responsive failure diagnosis threshold that is the normal index value, or If it is equal and the operating condition experience flag is "true", it is determined that the responsiveness of the pressure sensor has deteriorated leading to a failure, and a predetermined response in which the measurement index value is the normal index value If the operating condition experience flag is "true", the responsiveness of the pressure sensor is determined to be normal. Determining whether or not there is deterioration in responsiveness.

According to the present invention, an abnormal state of response of the pressure sensor can be diagnosed in advance without complicating the structure of the pressure sensor, and in particular, specific acceleration/deceleration conditions are not necessarily required as diagnostic conditions. In addition, since there is a possibility that the responsiveness of the pressure sensor can be diagnosed even in the steady state of operation, it is possible to diagnose deterioration of the responsiveness of the pressure sensor with high accuracy and a high diagnostic execution rate under vehicle usage conditions.

1 is a layout diagram showing an example of a pressure sensor mounted on an engine applied to the present invention; FIG. 1 is a schematic diagram of a preferred embodiment of the present invention for an intake manifold pressure sensor [Pmap]; FIG. The intake pressure, which is the pressure pulsation amplitude generated by the intake air accompanying the reciprocating motion of the piston of the intake manifold pressure sensor [Pmap] when the engine in the embodiment shown in FIG. Explanatory drawing which shows the time-series data of [kPa]. FIG. 3 is an explanatory diagram showing indexing of pressure pulsation in the embodiment shown in FIG. 2; FIG. 4 is a measurement diagram showing an example of design of a band-pass filter for extracting amplitude from a pressure sensor signal used in the present invention; FIG. 4 is an explanatory diagram of a failure diagnosis method regarding the responsiveness of the pressure sensor in the present invention; FIG. 4 is a pressure amplitude and time-series measurement diagram of responsiveness diagnosis of the fuel injection pressure sensor [Pinj] in the normal state according to the present embodiment; FIG. 4 is a pressure amplitude and time-series measurement diagram of responsiveness diagnosis in the present embodiment of the fuel injection pressure sensor [Pinj] in a state where responsiveness deterioration corresponding to a time constant (Tc) of 0.1 s is given. FIG. 10 is a pressure amplitude and time-series measurement diagram of responsiveness diagnosis in the present embodiment of the fuel injection pressure sensor [Pinj] in a state where responsiveness deterioration corresponding to a time constant (Tc) of 1.0 s is given; FIG. 8 is a measurement diagram showing the execution result of responsiveness diagnosis at normal time in the embodiment of the present invention in the fuel injection pressure sensor [Pinj] showing the characteristics shown in FIG. 7; Execution result of responsiveness diagnosis when responsiveness deterioration equivalent to time constant (Tc)=0.1 s in the embodiment of the present invention is applied to the fuel injection pressure sensor [Pinj] exhibiting the characteristics shown in FIG. Measurement diagram showing Execution result of responsiveness diagnosis when responsiveness deterioration equivalent to time constant (Tc)=1.0 s in the embodiment of the present invention is applied to the fuel injection pressure sensor [Pinj] exhibiting the characteristics shown in FIG. Measurement diagram showing FIG. 4 is a pressure amplitude and time-series measurement diagram of responsiveness diagnosis in the present embodiment of the intake manifold pressure sensor [Pmap] in a normal state. FIG. 14 is a measurement diagram showing the execution result of a responsiveness diagnosis in a normal state in the embodiment of the present invention for the intake manifold pressure sensor [Pmap] exhibiting the characteristics shown in FIG. 13; Execution result of responsiveness diagnosis when responsiveness deterioration equivalent to time constant (Tc)=0.1 s in the embodiment of the present invention is applied to the intake manifold pressure sensor [Pmap] exhibiting the characteristics shown in FIG. Measurement diagram showing Execution result of responsiveness diagnosis when responsiveness deterioration corresponding to time constant (Tc)=1.0 s in the embodiment of the present invention is applied to the intake manifold pressure sensor [Pmap] exhibiting the characteristics shown in FIG. Measurement diagram showing FIG. 4 is a pressure amplitude and time-series measurement diagram of response diagnosis in the present embodiment of the EGR valve upstream gas pressure sensor [Pegr] in a normal state. FIG. 18 is a measurement diagram showing the execution result of responsiveness diagnosis in the normal state in the embodiment of the present invention in the EGR valve upstream gas pressure sensor [Pegr] showing the characteristics shown in FIG. 17; The responsiveness diagnosis when the responsiveness deterioration corresponding to the time constant (Tc) = 0.1 s in the embodiment of the present invention in the EGR valve upstream gas pressure sensor [Pegr] exhibiting the characteristics shown in Fig. 17 is applied. Measurement diagram showing the execution result. Response diagnosis in the case where the EGR valve upstream gas pressure sensor [Pegr] exhibiting the characteristics shown in FIG. Measurement diagram showing the execution result. FIG. 2 is a schematic diagram of a conventional responsive deterioration diagnostic device for an intake manifold pressure sensor [Pmap]; FIG. 22 is an explanatory diagram showing an example of a diagnostic method by the pressure sensor response deterioration diagnostic device shown in FIG. 21;

EMBODIMENT OF THE INVENTION Below, the form for implementing this invention is demonstrated, referring drawings.

In addition, the present invention is applied to an engine equipped with an Exhaust Gas Recirculation (hereinafter referred to as "EGR") device that uses exhaust gas as a gas to be mixed with fuel for the purpose of improving fuel consumption, for example, as shown in FIG. In addition to the exhaust system pressure sensor, such as the turbo outlet exhaust pressure sensor [Ptcout], the EGR valve upstream pressure sensor [Pegr], etc., the intake manifold pressure sensor [Pmap], which is the intake system pressure sensor, and the turbo upstream air The pressure sensor [Pair], the throttle upstream pressure sensor [Pth], the fuel injection pressure sensor [Pinj], and other pressure sensors used in engine control can also be implemented in the same manner.

FIG. 2 shows a preferred embodiment when the present invention is carried out with respect to the intake manifold pressure sensor [Pmap] installed in the intake manifold 2 of the engine 1 among the above pressure sensors. Information from the sensor [Pmap] is input to the ECU 3 via a wire harness.

In general, the ECU 3 is provided with an analog filter circuit 9 made up of electronic parts and a digital filter processing circuit 11 made up of software for removing noise components that are unnecessary for engine control. , The filter unit used in this technology is equipped with a filter device consisting of an analog filter circuit 10 and a digital filter circuit 13 that can observe high frequency bands in order to detect engine pulsation components, compared with the conventional specification. Based on this information, a failure diagnosis of responsiveness deterioration is performed. Even if the sensor input circuit is changed, the same engine control as before can be achieved.

Next, the principle of responsiveness diagnosis of the pressure sensor according to the present embodiment will be described using the intake manifold pressure sensor [Pmap] as an example.

Fig. 3 shows the time series of the intake pressure [kPa], which is the pressure sensor signal information consisting of the pressure pulsation amplitude caused by the intake air accompanying the reciprocating motion of the piston of the intake manifold pressure sensor [Pmap] when the engine is in steady operation (during idling). data.

Here, since the engine is a reciprocating engine, not a little pulsation occurs due to intermittent intake/exhaust action. Therefore, as shown in FIG. Since this pressure pulsation has a high frequency, it is observed that this amplitude apparently decreases when the responsiveness of the pressure sensor deteriorates. The present invention focuses on this point, and observes the pressure pulsation, converts it into an index value, and compares it with the normal time, thereby making it possible to determine deterioration of the responsiveness of the pressure sensor.

Next, indexing of pressure pulsation in the present embodiment will be described with reference to FIG.

As shown in FIG. 4, each pressure sensor signal to be diagnosed in this embodiment passes through a band-pass filter, absolute value processing, and becomes a pressure sensor amplitude value (RES_AMP). The value (RES_AMP) is superimposed as a high frequency component that includes transient changes during acceleration and deceleration in addition to pressure pulsations that occur in a steady state. It is relatively simple to extract the response as a numerical value and update the maximum value in a specific driving cycle (for example, the entire section during driving from engine start to next engine start) by a maximum value update process. A pressure sensor responsiveness deterioration index (RES_IDX) can be obtained by quantifying the maximum response of the pressure sensor as an index value in a similar manner.

Here, it is important to design a band-pass filter that extracts the amplitude from each pressure sensor signal, an example of which is shown in FIG. By cutting 1Hz or less in the low frequency range and cutting 10Hz or more in the high frequency range, the DC component and electrical noise component unnecessary for responsiveness diagnosis are removed, thereby improving the detection accuracy. there is These band-pass filters can be implemented in a microcomputer with relatively few resources by using general finite impulse response (FIR) filter or infinite impulse response filter (IIR) filter technology. needless to say.

The higher the responsiveness of the pressure sensor, the higher the index value obtained here. will be affected.

Therefore, for example, as shown in FIG. 6, from the engine rotation information [Ne] and the accelerator opening information [APS], the operating conditions experienced for how long are counted, and from the total value of the counts, It can be determined that the previously assumed operating conditions have been experienced.

More specifically, determination processing is performed to calculate flag information indicating the experience, and when this flag information is "true" (True), the aforementioned pressure sensor responsive deterioration index (RES_IDX) is obtained. , and correct responsiveness can be determined by making a determination based on the responsiveness deterioration index (RES_IDX) of the pressure sensor.

If the responsiveness of the pressure sensor is normal, the pressure sensor responsiveness deterioration index (RES_IDX) indicates a high value, and if the responsiveness has deteriorated, the pressure sensor responsiveness deterioration index (RES_IDX) indicates a low value. show.

Therefore, when the value of the pressure sensor responsive deterioration index (RES_IDX) is lower than the responsive failure diagnosis threshold and the operating condition experience flag is "true" (True), the pressure sensor responsiveness is determined by the AND. , the value of the pressure sensor responsive deterioration index (RES_IDX) is higher than the responsive failure diagnosis threshold, and the operating condition experience flag is "true" (True). When the product is determined, the sensor responsiveness is determined to be normal, and a failure diagnosis regarding the responsiveness of the pressure sensor is performed .

Next, the operation of this embodiment will be described for the case of the fuel injection pressure sensor [Pinj], for example.

FIG. 7 shows data obtained when the fuel injection pressure sensor [Pinj] has a normal responsiveness and the engine is operated in the World-wide Harmonized Transient Cycle test mode (hereinafter referred to as "WHTC test mode") on the engine bench. , The upper graph shows data on the time series [s (seconds)] of the pressure pulsation [kPa] from the fuel injection pressure sensor [Pinj]. Both steady-state and transient operations are carried out.

In the upper graph of FIG. 7, it should be noted that relatively large pressure pulsation occurs due to the operation of the fuel injection valve in the idling state with an elapsed time of about 300 (s), and the fuel injection pressure sensor value responds to this. This is the point at which the state of large vibration can be observed.

The graph shown in the lower part of FIG. 7 is obtained by performing a short-time fast Fourier transform on the fuel injection pressure sensor signal, which is an oscillating component observed by the operation of the fuel injection valve in the idling state noted in the upper part of the graph. , the horizontal axis is the time axis, and the vertical axis is the frequency band.

The middle graph in FIG. 7 represents the amplitude of the frequency band in the lower graph by shading, and the lighter the color, the larger the vibration.

According to the analysis result from the lower graph of FIG. 7, it is found that the pressure amplitude of the fuel injection pressure sensor [Pinj] appears around 10 Hz in the idle operation. A large vibration component is also observed in the pressure amplitude of the fuel injection pressure sensor [Pinj] during the latter half of the operation, and it can be seen that this is mainly composed of harmonics of about 30 Hz.

8 and 9 show the result of intentionally deteriorating the responsiveness of the fuel injection pressure sensor [Pinj] in the fuel injection pressure sensor signal of the fuel injection pressure sensor [Pinj] showing the characteristics shown in FIG. FIG. 8 shows the case where response deterioration corresponding to a time constant (Tc) of 0.1 s is given, and FIG. 9 shows the case where the response deterioration of the fuel injection pressure sensor [Pinj] is further given. It shows the case where response degradation corresponding to a constant (Tc) of 1.0 s is given.

According to the frequency distribution diagram shown in FIG. 8, it is observed that the fuel injection pressure sensor signal under the normal idling condition shown in FIG. 7 decreases. This is the result of the deterioration of the responsiveness of the fuel injection pressure sensor [Pinj], which made it impossible to capture high frequency components, further deteriorating the responsiveness of the fuel injection pressure sensor [Pinj] shown in FIG. In the case of the frequency map, a further decrease in the fuel injection pressure sensor signal at idle conditions is observed.

From these facts, it can be seen that even under operating conditions other than the idling condition, the high frequency components decrease as the responsiveness of the fuel injection pressure sensor deteriorates overall.

FIGS. 10 to 12 show the execution results of responsiveness diagnosis in the embodiment of the present invention for the fuel injection pressure sensor [Pinj] exhibiting the characteristics shown in FIG. 7. FIG. FIG. 11 shows the execution result of the diagnosis when the response deterioration corresponding to the time constant (Tc)=0.1 s is given, and FIG. 12 shows the response deterioration corresponding to the time constant (Tc)=1.0 s. are shown respectively.

Then, according to FIG. 10 showing the diagnostic execution result in the normal state, the pressure sensor amplitude value ( RES_AMP) shows a steady value of 0 or more, and from this, it can be seen that the pressure oscillation is steadily detected during idling.

Further, as shown in FIG. 11, when the responsiveness deterioration corresponding to the time constant (Tc)=0.1 s is given, in response to the pressure pulsation [kPa] from the fuel injection pressure sensor [Pinj], It can be seen that the amplitude value (RES_AMP) of the pressure sensor calculated by the diagnostic program decreases and becomes almost zero. In this way, the time constant (Tc )=0.1 s.

Furthermore, as shown in FIG. 12, when the responsiveness deterioration corresponding to the time constant (Tc)=1.0 s is given, in response to the pressure pulsation [kPa] from the fuel injection pressure sensor [Pinj], Since the amplitude value (RES_AMP) of the pressure sensor calculated by the diagnostic program is also near 0, this alone cannot be distinguished from the case corresponding to the time constant (Tc)=0.1 s shown in FIG.

However, not only the steady operation at idle but also the rise of the fuel injection pressure during acceleration is delayed, so the peak of the amplitude value (RES_AMP) of the pressure sensor tends to be low. RES_IDX) shows a downward trend.

Therefore, by using the information of the pressure sensor responsiveness deterioration index (RES_IDX), it becomes possible to detect responsiveness deterioration with a time constant (Tc) of 0.1 s or more. ) quantifies the maximum response of the pressure sensor, so it shows a small value immediately after the engine starts when the diagnosis is activated, but it gradually changes to a large value when various pressure oscillations and transient conditions are experienced.

Thus, in the current WHTC test mode operation, there is a tendency to saturate at a substantially constant value at an elapsed time of about 600 seconds. Regarding this, by utilizing the flag information of the operating range experience determination process in the diagnostic program described above, it is possible to determine that the vehicle has experienced various operating conditions.

13 to 16 illustrate the operation of the embodiment of the present invention when the intake manifold pressure sensor [Pmap] is employed as the pressure sensor.

FIG. 13 shows data of an embodiment of the present invention when the intake manifold pressure sensor [Pmap] is normal and the engine bench WHTC test mode is operated. Data are shown for the time series [s (seconds)] of the pressure pulsation [kPa] from the sensor [Pmap], starting from an engine off condition, each steady and transient as defined in the WHTC test mode. are doing the driving.

Focusing on the idling state after an elapsed time of 300 seconds in FIG. 13, harmonics of about 300 Hz can be observed due to pressure pulsation, but the amplitude is small and deterioration cannot be determined. Also, in the latter half of the mode, in which the high-speed, high-load steady-state operation region can be observed, the harmonic component due to the pressure amplitude can be observed, but the amplitude is small, and the deterioration cannot be determined based on this information alone.

Next, FIGS. 14 to 16 show observation results of the embodiment of the present invention when the intake manifold pressure sensor [Pint] is used as the pressure sensor in the present invention. FIG. 14 shows the results of diagnostic execution in a normal state, FIG. 15 shows the results of diagnostic execution when response deterioration corresponding to time constant (Tc)=0.1 s is given, and FIG. 16 shows time constant (Tc)=1. These figures show the results of diagnostic execution when a responsiveness deterioration equivalent to 0 s is given.

According to FIG. 14, which shows the results of the response performance diagnosis for a normal intake manifold pressure sensor [Pmap], the amplitude value (RES_AMP) of the pressure sensor is near 0 in the idle state, and the pressure sensor amplitude value (RES_AMP) is in the vicinity of 0 in the idle state. is also small in the steady operation region, it can be seen that it is not possible to determine responsiveness deterioration using information on the amplitude value (RES_AMP) of the pressure sensor . Focusing on the information of the pressure sensor response deterioration index (RES_IDX) calculated by the diagnostic program, the pressure sensor response deterioration index (RES_IDX) of the intake manifold pressure sensor [Pmap] reaches around 80 at the end of the test mode. I understand that it is rising.

Furthermore, in FIG. 15, which shows the diagnosis execution result when the responsiveness deterioration corresponding to the time constant (Tc)=0.1 s is given, the amplitude value (RES_AMP) of the pressure sensor and the pressure of the intake manifold pressure sensor [Pmap] Both the sensor responsiveness deterioration index (RES_IDX) and the normal pressure sensor shown in FIG. 12 are the same, and the responsiveness deterioration cannot be determined, but the deterioration of the time constant (Tc) of about 0.1 s does not affect emissions. Therefore, there is no problem even if it cannot be determined.

Furthermore, according to FIG. 16 showing the diagnosis execution result when a further deteriorated responsiveness corresponding to the time constant (Tc)=1.0 s is given, the deterioration corresponding to the time constant (Tc)=1.0 s There is no difference between the normal intake manifold pressure sensor and the pressure sensor amplitude value (RES_AMP) in the idling state and the latter half of the high speed/high load steady operation region, and the pressure sensor amplitude value (RES_AMP) does not respond. Sexual deterioration cannot be determined.

However, when focusing on the pressure sensor responsiveness deterioration index (RES_IDX), the peak value of the amplitude value (RES_AMP) of the pressure sensor decreased due to the deterioration of the pressure sensor, and remained at around 50 at the end of the test mode. is observed, and by comparing the difference between the pressure sensor responsiveness deterioration index (RES_IDX) and a normal sensor, it is possible to detect responsiveness deterioration with a time constant (Tc) of 1.0 s or more. . The judging means is the same as that of the embodiment of the fuel injection pressure sensor [Pinj] shown in FIGS. 10 to 13, and the explanation thereof is omitted.

Further, with reference to FIGS. 17 to 20, the operation of the embodiment of the invention when the EGR valve upstream gas pressure sensor [Pegr] is employed as the pressure sensor will be described.

FIG. 17 shows data when the engine bench WHTC test mode is operated with the EGR valve upstream gas pressure sensor [Pegr] normal. The lower part of the graph shows the frequency and amplitude components of the EGR valve upstream gas pressure sensor [Pegr] on the same time axis as the upper part.

According to FIG. 17, the EGR valve upstream gas pressure sensor [Pegr] can observe harmonics of about 40 Hz during idle operation, but the amplitude is small and relatively large in the steady operation region of high rotation and high load in the latter half of the mode. Pressure amplitude can be observed.

Next, FIG. 18 to FIG. 20 show execution results of responsiveness diagnosis when the present invention is implemented for the EGR valve upstream gas pressure sensor [Pegr] having pressure oscillation shown in FIG. FIG. 18 shows the result of diagnosis in a normal state, FIG. 19 shows the result of diagnosis when response deterioration corresponding to time constant (Tc)=0.1 s is given, and FIG. The results of diagnostic execution when a responsiveness deterioration equivalent to 1.0 s is given are shown.

According to the diagnostic execution result of FIG. 18 showing the diagnostic result of the normal state, the amplitude value (RES_AMP) of the pressure sensor is 0 during idling, which corresponds to the time constant (Tc)=0.1 s shown in FIG. 20 shows the diagnostic execution result when the response deterioration corresponding to the time constant (Tc)=1.0 s is given, and the amplitude value (RES_AMP) of the pressure sensor is 0. Therefore, it is not possible to judge deterioration only by idling.

On the other hand, in the steady operation range of high rotation and high load in the second half of the mode, it can be observed that the amplitude value (RES_AMP) of the pressure sensor is 0 or more in the diagnosis execution result of FIG. In the diagnosis execution result when the responsiveness deterioration corresponding to the time constant (Tc) = 0.1 s shown in FIG. It can be seen that it becomes possible to determine response deterioration corresponding to (Tc)=0.1 s.

Further, in the diagnostic execution result when the response deterioration corresponding to the time constant (Tc) of 1.0 s shown in FIG. 20 is given, the pressure sensor amplitude value (RES_AMP) hardly changes, and It is difficult to make a decision based on the value (RES_AMP). The judging means is the same as that of the embodiment of the fuel injection pressure sensor [Pinj] shown in FIGS. 10 to 12, and the explanation thereof is omitted.

As described above, in each of the present embodiments, the pulsation component superimposed on the pressure sensor is measured, the pressure amplitude is converted into an index value by simple filter signal processing, and combined with the experience flag of the operating conditions to make a determination. , Specific acceleration/deceleration conditions are not necessarily required for the diagnostic conditions, and in addition, there is a possibility that the responsiveness of the pressure sensor can be diagnosed even in the steady state of operation. It is possible to provide deterioration diagnosis of the response performance of pressure sensors with a high diagnosis execution rate.

1 engine, 2 intake manifold, 3 ECU, 4 microcomputer, 5 engine control processing circuit, 6 throttle valve, 7 throttle valve opening sensor, 8 pressure sensor response diagnostic circuit, 9, 10 analog filter circuit, 11, 12, 13 Digital Filter Circuit, Pinj Fuel Injection Pressure Sensor, Ptcout Turbo Outlet Exhaust Pressure Sensor, Pmap Intake Manifold Pressure Sensor, Pair Turbo Upstream Air Pressure Sensor, Pth Throttle Upstream Pressure Sensor

Claims (3)

A method for diagnosing the responsiveness of a pressure sensor provided in an intake system or an exhaust system of an engine used for spark ignition engine control,
Measure pressure sensor signal information, which is pressure pulsation amplitude generated in the intake system or exhaust system of the engine by intake or exhaust accompanying the reciprocating motion of the piston during operation of the engine ,
The measured pressure sensor signal information is subjected to bandpass filter processing and absolute value processing by an analog filter circuit and a digital filter circuit arranged inside the engine control device, and the pressure pulsation in the high frequency band detected by the pressure sensor. a measurement index value obtained by indexing the amplitude;
The pressure sensor signal information measured under normal conditions is subjected to bandpass filtering and absolute value processing by the analog filter circuit and the digital filter circuit, and the pressure pulsation amplitude in the high frequency band detected by the pressure sensor is used as an index. Compare the quantified normal index value and
determining that the responsiveness of the pressure sensor has deteriorated leading to a failure when the measurement index value is lower than or equal to a predetermined responsive failure diagnosis threshold value, which is the normal index value;
By determining that the responsiveness of the pressure sensor is normal when the measurement index value is higher than a predetermined responsive failure diagnosis threshold value, which is the normal index value,
A method for diagnosing responsiveness of a pressure sensor used for engine control, comprising determining whether or not deterioration in responsiveness has occurred in the pressure sensor used for engine control. When the pressure sensor signal information is processed by the analog filter circuit and the digital filter circuit , the pressure sensor signal information is smoothed by weighted average processing after the absolute value processing, and furthermore, in a specific driving cycle, the maximum value is updated by maximum value update processing. 2. The method of diagnosing responsiveness of a pressure sensor used for engine control according to claim 1, wherein the index value is obtained by updating the value . Based on the engine rotation information and the accelerator opening information, count which driving conditions have been experienced for how long, and judge whether or not the presumed driving conditions have been experienced from the total value of the counts, If the determination is true, perform determination processing to set the operating condition experience flag to "true",
When the measurement index value is lower than or equal to the predetermined responsive failure diagnosis threshold value, which is the normal index value, and the operating condition experience flag is "true", the responsiveness of the pressure sensor is determined to be faulty. Determining that there is deterioration that leads,
When the measurement index value is higher than a predetermined responsive failure diagnosis threshold value, which is the normal index value, and when the operating condition experience flag is "true", it is determined that the responsiveness of the pressure sensor is normal. By
3. The method of diagnosing responsiveness of a pressure sensor used for engine control according to claim 1 , wherein the presence or absence of deterioration in responsiveness of the pressure sensor used for engine control is determined.

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