CN112000077B - Vehicle environment pressure sensor fault diagnosis method and fault protection method - Google Patents
Vehicle environment pressure sensor fault diagnosis method and fault protection method Download PDFInfo
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- CN112000077B CN112000077B CN202010636906.8A CN202010636906A CN112000077B CN 112000077 B CN112000077 B CN 112000077B CN 202010636906 A CN202010636906 A CN 202010636906A CN 112000077 B CN112000077 B CN 112000077B
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- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B23/00—Testing or monitoring of control systems or parts thereof
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- G05B23/0205—Electric testing or monitoring by means of a monitoring system capable of detecting and responding to faults
- G05B23/0218—Electric testing or monitoring by means of a monitoring system capable of detecting and responding to faults characterised by the fault detection method dealing with either existing or incipient faults
Abstract
The application discloses a fault diagnosis method and a fault protection method for a vehicle environment pressure sensor, and relates to the technical field of fault diagnosis, wherein the method comprises the following steps: after the engine is electrified, acquiring a voltage signal analog quantity of the environmental pressure and a current reference voltage value according to a preset first time interval, and performing proportional correction through a standard reference voltage value to obtain an environmental voltage correction value; carrying out electrical connection fault diagnosis and rationality fault diagnosis on the environmental pressure sensor periodically through the environmental voltage correction value obtained each time; if the electrical connection fault is diagnosed, the current diagnosis period of the electrical connection fault is ended in advance, the next diagnosis period of the electrical connection fault is started, and the rationality fault diagnosis is stopped; and starting the electrical connection fault diagnosis and the rationality fault diagnosis at the same time again until the electrical connection fault is not diagnosed in the diagnosis period of the electrical connection fault. According to the method and the device, the reliability of fault diagnosis and signals is improved, and the dynamic property and the safety of the vehicle are guaranteed.
Description
Technical Field
The application relates to the technical field of fault diagnosis, in particular to a fault diagnosis method and a fault protection method for a vehicle environment pressure sensor.
Background
As one of the engine operation control parameters, the intake air amount affects the normal operation of the engine. The ambient pressure is used as an important factor for calculating the air intake quantity, and if the ambient pressure is not accurately calculated or an ambient pressure sensor fails, the engine cannot normally operate indirectly.
In the related technology, the fault state of the sensor is judged according to the difference value of the collected information of the sensor in 2 periods. Then, in order to meet the normal working requirement of the engine, when the ambient pressure sensor fails, an ECU (Electronic Control Unit) calculates the air intake amount by using a preset fixed ambient pressure value.
However, since the driving condition of the vehicle and the state of the pressure sensor change in real time, the diagnosis method has a large limitation, and the state of the pressure sensor cannot be accurately judged. In addition, the air inflow is calculated through the fixed environment pressure value, the obtained air inflow error is large, the normal operation of the engine is easily influenced, and the operation of the engine is unstable.
Disclosure of Invention
Aiming at one of the defects in the prior art, the invention aims to provide a fault diagnosis method and a fault protection method for a vehicle environment pressure sensor to solve the problem that the state of the pressure sensor cannot be accurately judged in the related technology.
The present application provides, in a first aspect, a method for diagnosing a failure of a vehicle ambient pressure sensor, including the steps of:
after the engine is electrified, acquiring a voltage signal analog quantity of the environmental pressure and a current reference voltage value according to a preset first time interval, and performing proportional correction through a standard reference voltage value to obtain an environmental voltage correction value;
carrying out electrical connection fault diagnosis and rationality fault diagnosis on the environmental pressure sensor periodically through the environmental voltage correction value obtained each time;
if the electrical connection fault is diagnosed, the current diagnosis period of the electrical connection fault is ended in advance, the next diagnosis period of the electrical connection fault is started, and the rationality fault diagnosis is stopped; and starting the electrical connection fault diagnosis and the rationality fault diagnosis at the same time again until the electrical connection fault is not diagnosed in the diagnosis period of the electrical connection fault.
In some embodiments, performing electrical connection fault diagnostics specifically includes:
taking the diagnosis period of the electrical connection fault as a first diagnosis period, if the times that the environmental voltage correction value is greater than the first voltage threshold value in one first diagnosis period are not greater than a first time threshold value and the times that the environmental voltage correction value is less than the second voltage threshold value are not greater than a second time threshold value, determining that the electrical connection fault is not diagnosed in the current first diagnosis period, and entering the next first diagnosis period; the first voltage threshold is greater than the second voltage threshold.
In some embodiments, in the first diagnosis period, performing an electrical connection fault diagnosis on the ambient pressure sensor through the ambient voltage correction value obtained each time, specifically includes:
sequentially judging whether the environmental voltage correction value obtained each time in the first diagnosis period is larger than a first voltage threshold or smaller than a second voltage threshold;
when the environment voltage correction value is larger than a first voltage threshold, adding one to the first counting value, and if the first counting value after adding one is larger than a first time threshold, determining that the environment pressure sensor has a short-circuit fault to the power supply, and ending the current first diagnosis period in advance;
and when the environment voltage correction value is smaller than a second voltage threshold, adding one to the second counting value, and if the second counting value after adding one is larger than a second secondary threshold, determining that the environment pressure sensor has a short circuit fault to the ground, and ending the current first diagnosis period in advance.
In some embodiments, before performing the rationality fault diagnosis, the method further includes: and converting the environmental voltage correction value obtained each time into a pressure signal according to the voltage-pressure gauge.
In some embodiments, the rationality fault diagnosis includes data out-of-range diagnosis, and a diagnosis period of the data out-of-range diagnosis is taken as a second diagnosis period, and the second diagnosis period is greater than a diagnosis period of the electrical connection fault;
in a second diagnosis period, performing data out-of-range diagnosis on the ambient pressure sensor, specifically including:
sequentially judging whether the pressure signal obtained each time in the second diagnosis period exceeds a preset range;
and when the pressure signal exceeds the preset range, adding one to the third counting value, if the added third counting value is larger than the third counting threshold value, determining that the environmental pressure sensor has data out-of-range fault, ending the current second diagnosis period in advance, and entering the next second diagnosis period.
In some embodiments, the rationality fault diagnosis includes a signal drift diagnosis, and a diagnosis period of the signal drift diagnosis is a third diagnosis period, and the third diagnosis period is greater than the second diagnosis period;
in a third diagnostic period, performing signal drift diagnosis on the ambient pressure sensor, specifically including:
taking the difference value of the pressure signals before and after a preset second time interval as the change gradient of the pressure signal; the second predetermined time interval is not less than the second diagnostic period;
in a third diagnosis period, obtaining the change gradient for multiple times, and performing signal drift diagnosis on the environmental pressure sensor through the change gradient obtained each time;
if the data out-of-range fault is diagnosed in the current second diagnosis period, the current second diagnosis period and the third diagnosis period are both ended in advance, and the next second diagnosis period and the next third diagnosis period are started at the same time.
In some embodiments, in the third diagnosis period, performing signal drift diagnosis on the ambient pressure sensor through the change gradient obtained each time, specifically including:
sequentially judging whether the change gradient obtained each time in the third diagnosis period is greater than a gradient threshold value;
and when the change gradient is greater than the gradient threshold, adding one to the fourth counting value, and if the fourth counting value after adding one is greater than the fourth counting threshold, determining that the ambient pressure sensor has a signal drift fault, and ending the current third diagnosis period in advance.
A second aspect of the present application provides a method of fault protection for a vehicle ambient pressure sensor, comprising:
the ambient pressure determination step is performed in accordance with the diagnostic state of the vehicle ambient pressure sensor malfunction diagnostic method according to claim 1.
In some embodiments, if the ambient voltage correction value is abnormal at a certain time and the ambient pressure sensor does not diagnose an electrical connection fault or a rationality fault, the ambient pressure corresponding to the ambient voltage correction value without abnormality at the previous time is used as the current ambient pressure to calculate the intake air amount.
In some embodiments, the diagnostic status is a confirmed fault when the ambient pressure sensor diagnoses an electrical connection fault or a rationality fault;
judging the current engine state, if the engine is in the running state, performing environmental pressure estimation calculation according to a compressed fluid equation, and taking the obtained estimated environmental pressure as the current environmental pressure; otherwise, taking the intake pressure as the current ambient pressure;
the above estimating and calculating the environmental pressure according to the compressed fluid equation specifically includes:
acquiring average air mass flow, air inlet pressure, air inlet temperature and air throttle opening at a throttle valve, and calculating a pressure ratio correction coefficient;
and estimating the current ambient pressure according to the intake pressure and the pressure ratio correction coefficient.
The beneficial effect that technical scheme that this application provided brought includes:
according to the vehicle environment pressure sensor fault diagnosis method and the fault protection method, the environment pressure voltage signal analog quantity is subjected to proportional correction through the standard reference voltage value and the current reference voltage value, then the pressure sensor is subjected to electrical connection fault diagnosis and rationality fault diagnosis according to the environment voltage correction value, all possible faults are covered, and finally, corresponding environment pressure determination steps are carried out according to diagnosis states. The method not only constantly keeps monitoring the signal of the pressure sensor, but also eliminates the influence of the reference voltage fluctuation on the voltage signal and the pressure signal acquired by the pressure sensor, improves the reliability of fault diagnosis and the signal, and meanwhile, under the condition that the pressure sensor breaks down, can also take correction measures to obtain proper environmental pressure, meets the requirement of an ECU on the accuracy of the environmental pressure, and ensures the dynamic property, the driving property and the safety of a vehicle.
Drawings
FIG. 1 is a flow chart of a method for diagnosing a fault of a vehicle ambient pressure sensor in an embodiment of the present application;
FIG. 2 is a flow chart of calculating an ambient voltage correction value according to an embodiment of the present application;
FIG. 3 is a flow chart of electrical connection fault diagnosis in an embodiment of the present application;
FIG. 4 is a flow chart of data out-of-range diagnostics in an embodiment of the present application;
FIG. 5 is a flow chart of signal drift diagnostics in an embodiment of the present application;
FIG. 6 is a flow chart of a fault protection method in an embodiment of the present application;
fig. 7 is a flow chart of a value of a current ambient pressure in an embodiment of the present application;
FIG. 8 is a schematic illustration of an engine air intake system in an embodiment of the subject application;
FIG. 9 is a diagram illustrating a relationship between a pressure ratio and a correction coefficient in an embodiment of the present application;
FIG. 10 is a flow chart of an ambient pressure estimation calculation in an embodiment of the present application;
fig. 11 is a schematic diagram of an in-loop simulation result of the ambient pressure estimation algorithm software in the embodiment of the present application.
Detailed Description
The present application will be described in further detail with reference to the accompanying drawings and examples.
Referring to fig. 1, an embodiment of the present application provides a method for diagnosing a fault of a vehicle ambient pressure sensor, which includes the steps of:
s1, after an engine is electrified, acquiring voltage signal analog quantity of environmental pressure and a current reference voltage value according to a preset first time interval, and performing proportional correction through a standard reference voltage value to obtain an environmental voltage correction value.
Referring to FIG. 2, in the present embodiment, the standard reference voltage value U0Is 5V. After the engine is powered on, the ECU acquires 0-5V voltage signal analog quantity U according to a preset time interval1Simultaneously obtaining the current reference voltage value U2Then, the voltage signal is corrected by a 5V reference voltage to obtain a corrected environment voltage correction value U ═ U0×(U1÷U2). Wherein the voltage correction value U for calculating the ambient pressure will no longer be affected by the 5V reference voltage fluctuation.
And S2, carrying out electrical connection fault diagnosis and rationality fault diagnosis on the environmental pressure sensor periodically through the environmental voltage correction value obtained each time.
The diagnosis period of the electrical connection fault diagnosis and the diagnosis period of the rationality fault diagnosis are different, and the diagnosis period of the rationality fault diagnosis is larger than the diagnosis period of the electrical connection fault diagnosis after the engine is electrified.
S3, if the electrical connection fault is diagnosed, the current diagnosis period of the electrical connection fault is ended in advance, the next diagnosis period of the electrical connection fault is started, and the rationality fault diagnosis is stopped; and starting the electrical connection fault diagnosis and the rationality fault diagnosis at the same time again until the electrical connection fault is not diagnosed in the diagnosis period of the electrical connection fault.
According to the fault diagnosis method, the environment pressure voltage signal analog quantity is subjected to proportional correction through the standard reference voltage value and the current reference voltage value, then the pressure sensor is subjected to electrical connection fault diagnosis and rationality fault diagnosis according to the environment voltage correction value, all possible faults are covered, and finally, corresponding environment pressure determination steps are carried out according to diagnosis states. The method not only keeps monitoring the signal of the pressure sensor at all times, but also eliminates the influence of the reference voltage fluctuation on the voltage signal and the pressure signal acquired by the pressure sensor, and improves the fault diagnosis and the reliability of the signal.
In this embodiment, the step S2 of performing the electrical connection fault diagnosis specifically includes:
and taking the diagnosis period of the electrical connection fault as a first diagnosis period, and if the times that the environmental voltage correction value is greater than the first voltage threshold value in one first diagnosis period are not greater than a first time threshold value and are less than a second voltage threshold value, determining that the electrical connection fault is not diagnosed in the current first diagnosis period, wherein the first voltage threshold value is greater than the second voltage threshold value.
In this embodiment, the electrical connection fault diagnosis includes fault diagnosis of a power supply short circuit scb (short to battery) and fault diagnosis of a ground short circuit scg (short circuit group).
Further, in the first diagnosis period, the electrical connection fault diagnosis of the ambient pressure sensor is performed by the ambient voltage correction value obtained each time, and specifically includes:
firstly, whether the environmental voltage correction value obtained each time in the first diagnosis period is larger than a first voltage threshold value or smaller than a second voltage threshold value is judged in sequence.
And when the environment voltage correction value is larger than the first voltage threshold, adding one to the first counting value, if the first counting value after adding one is larger than the first time threshold, determining that the environment pressure sensor has a short-circuit fault to the power supply, reporting a corresponding fault code, and ending the current first diagnosis period. Wherein the first count value indicates a number of times the ambient voltage correction value is greater than the first voltage threshold.
And when the environment voltage correction value is smaller than a second voltage threshold, adding one to the second counting value, if the second counting value after adding one is larger than a second secondary threshold, determining the ground short circuit fault of the environment pressure sensor, reporting a corresponding fault code, and ending the current first diagnosis period. Wherein the second count value represents a number of times the ambient voltage correction value is less than the second voltage threshold.
Specifically, referring to fig. 3, the specific flow of the electrical connection fault diagnosis is as follows:
A1. and judging whether the engine controller is in a power-on state, namely whether the ignition key position is located on key on, if so, turning to A2, and if not, ending the current first diagnosis period.
A2. Obtaining a current environment voltage correction value, and judging whether the environment voltage correction value is larger than a first voltage threshold value, if so, turning to A3, otherwise, turning to A4;
A3. adding one to the first count value, judging whether the first count value after adding one is larger than a first time threshold value, if so, turning to A7, otherwise, turning to A6;
A4. judging whether the current environment voltage correction value is smaller than a second voltage threshold value, if so, turning to A5, otherwise, turning to A6;
A5. adding one to the second counting value, judging whether the second counting value after adding one is larger than a second secondary threshold value, if so, turning to A7, otherwise, turning to A6;
A6. and adding one to the first diagnosis times, judging whether the added first diagnosis times are smaller than the maximum diagnosis times N1 of the first diagnosis period, if so, turning to A1, otherwise, determining that no electrical connection fault exists currently, and ending the current first diagnosis period.
A7. And reporting a corresponding fault code, and ending the current first diagnosis period.
Further, after obtaining the ambient voltage correction value each time, before performing the rationality fault diagnosis, the method further includes: and converting the environmental voltage correction value obtained each time into a pressure signal according to the voltage-pressure gauge.
In this embodiment, the rationality fault diagnosis includes data out-of-range diagnosis, and the diagnosis period of the data out-of-range diagnosis is used as a second diagnosis period, and the second diagnosis period is greater than the diagnosis period of the electrical connection fault.
In a second diagnosis period, performing data out-of-range diagnosis on the ambient pressure sensor, specifically including:
firstly, whether the pressure signal obtained each time in the second diagnosis period exceeds a preset range is sequentially judged. If the pressure exceeds the preset pressure, the ambient pressure exceeds a reasonable range.
And when the pressure signal exceeds the preset range, adding one to the third counting value, and if the added third counting value is larger than the third counting threshold, determining that the environmental pressure sensor has data out-of-range fault, and ending the current second diagnosis period in advance. Wherein the third count value represents a number of times the pressure signal is outside of the preset range.
And if the data out-of-range fault is not diagnosed in the current second diagnosis period, entering the next second diagnosis period.
And stopping the data out-of-range diagnosis when the electrical connection fault occurs in the data out-of-range diagnosis process.
Referring to fig. 4, in the second diagnosis period, a specific flow of performing data out-of-range diagnosis on the ambient pressure sensor is as follows:
B1. and judging whether the ignition key position is located on key on and no electrical connection fault exists currently, if so, turning to B2, and otherwise, ending the current second diagnosis period.
B2. Acquiring a current pressure signal, and judging whether the pressure signal exceeds a preset range, if so, turning to B3, otherwise, turning to B5;
B3. adding one to the third counting value, judging whether the added third counting value is larger than a third counting threshold value, if so, turning to B4, otherwise, turning to B5;
B4. and reporting a corresponding fault code, and ending the current second diagnosis period.
B5. And adding one to the second diagnosis times, judging whether the added second diagnosis times are smaller than the maximum diagnosis times N2 of the second diagnosis period, if so, turning to B1, otherwise, determining that the current no-data out-of-range fault exists, and ending the current second diagnosis period.
Preferably, the rationality fault diagnosis further includes signal drift diagnosis, a diagnosis period of the signal drift diagnosis is a third diagnosis period, the third diagnosis period is greater than the second diagnosis period, and the third diagnosis period starts at the same time as the second diagnosis period after the engine is powered on.
The above diagnosing the signal drift of the ambient pressure sensor specifically includes:
firstly, taking the difference value of the pressure signals before and after a preset second time interval as the change gradient of the next pressure signal; the second preset time interval is not less than the second diagnosis period.
Then, in a third diagnostic period, a change gradient is obtained a plurality of times, and a signal drift diagnosis is performed on the ambient pressure sensor by the change gradient obtained each time.
If the data out-of-range fault is diagnosed in the current second diagnosis period, the current second diagnosis period and the third diagnosis period are both ended in advance, and the next second diagnosis period and the next third diagnosis period are started at the same time.
Further, in a third diagnostic period, performing signal drift diagnosis on the ambient pressure sensor through the change gradient obtained each time, specifically including:
and sequentially judging whether the change gradient obtained each time in the third diagnosis period is larger than a gradient threshold value. And when the change gradient is greater than the gradient threshold, adding one to the fourth counting value, and if the fourth counting value after adding one is greater than the fourth counting threshold, determining that the ambient pressure sensor has a signal drift fault, and ending the current third diagnosis period in advance. Wherein the fourth count value represents a number of times the gradient of change is greater than the gradient threshold.
Referring to fig. 5, in the third diagnostic period, a specific flow of performing the signal drift diagnosis on the ambient pressure sensor is as follows:
C1. and judging whether the ignition key position is located on key on and no electrical connection fault and data out-of-range fault exist currently, if so, turning to C2, and otherwise, ending the current second diagnosis period.
C2. Acquiring the change gradient of the current pressure signal, and judging whether the change gradient exceeds a preset range, if so, turning to C3, otherwise, turning to C5;
C3. adding one to the fourth count value, judging whether the fourth count value after adding one is larger than a fourth count threshold value, if so, turning to C4, otherwise, turning to C5;
C4. and reporting a corresponding fault code, and ending the current third diagnosis period.
C5. And adding one to the third diagnosis frequency, judging whether the added third diagnosis frequency is smaller than the maximum diagnosis frequency N3 of the third diagnosis period, if so, turning to C1, otherwise, determining the current no-signal drift fault, and ending the current third diagnosis period.
In this embodiment, both the data out-of-range diagnosis and the signal drift diagnosis belong to the rationality fault diagnosis.
In order to meet the requirement of normal work of the engine, when the ambient pressure sensor fails, the ECU needs to obtain an accurate ambient pressure value through reasonable degradation measures.
The embodiment of the application also provides a fault protection method for the vehicle environment pressure sensor, which comprises the following steps: and performing an ambient pressure determination step corresponding to the diagnostic state based on the diagnostic state of the vehicle ambient pressure sensor failure diagnostic method. Wherein the diagnostic state includes no fault, sampling fault and confirming fault.
According to the fault protection method, under the condition that the pressure sensor fails, appropriate environmental pressure can be obtained by taking correction measures, the requirement of the ECU on the accuracy of the environmental pressure is met, and the dynamic property, the driving property and the safety of the vehicle are guaranteed.
In this embodiment, if the ambient voltage correction value is abnormal at a certain time and the ambient pressure sensor is not diagnosed as an electrical connection fault, a data out-of-range fault, or a signal drift fault, the ambient pressure signal corresponding to the ambient voltage correction value without abnormality at the previous time is used as the current ambient pressure to calculate the intake air amount.
The abnormal condition of the environmental voltage correction value comprises the following steps: the environment voltage correction value is larger than the first voltage threshold value, the environment voltage correction value is smaller than the second voltage threshold value, the pressure signal corresponding to the environment voltage correction value exceeds a preset range, the change gradient of the pressure signal corresponding to the environment voltage correction value is larger than a gradient threshold value, and the like.
Further, when the environmental pressure sensor diagnoses an electrical connection failure, a data out-of-range failure, or a signal drift failure, the diagnostic state is a confirmation failure.
When the diagnosis state is the confirmed fault state, judging the current engine state, if the engine is in the running state, performing environmental pressure estimation calculation according to a compressed fluid equation, and taking the obtained estimated environmental pressure as the current environmental pressure; otherwise, the intake pressure acquired by the intake pressure sensor is used as the current ambient pressure, that is, if the engine is in a power-on, start or stop state, the intake pressure is used as the current ambient pressure.
Referring to fig. 6, the specific flow of the fault protection method of the present embodiment is as follows:
D1. judging whether the currently obtained environmental voltage correction value is effective or not, namely, no abnormity occurs, if so, turning to D2, otherwise, turning to D3;
D2. and adopting the environmental pressure signal corresponding to the current environmental voltage correction value as the current environmental pressure.
D3. Judging whether the diagnosis state is a confirmed fault, if so, turning to D4, otherwise, turning to D5;
D4. and performing environmental pressure estimation calculation according to a compressed fluid equation, and taking the obtained estimated environmental pressure as the current environmental pressure.
D5. And judging that the diagnosis state is a sampling fault, and taking an environmental pressure signal corresponding to the environmental voltage correction value without abnormality at the previous time as the current environmental pressure.
In this embodiment, the basic principle of the environmental pressure estimation is to ensure that the engine can suck enough air, and as shown in fig. 7, when the diagnostic state is a confirmed fault, the current environmental pressure value flow is specifically as follows:
E1. judging whether the current engine is in a power-on state, if so, turning to E2, and otherwise, turning to E3;
E2. the intake pressure is taken as the current ambient pressure.
E3. Judging whether the current engine is in a starting state, if so, turning to E2, and otherwise, turning to E4;
E4. judging whether the current engine is in a running state, if so, turning to E5, and otherwise, turning to E6;
E5. and performing environmental pressure estimation calculation according to a compressed fluid equation, and taking the obtained estimated environmental pressure as the current environmental pressure.
E6. Judging whether the current engine is in a flameout state, if so, turning to E2, otherwise, turning to E7;
E7. the current ambient pressure is taken as a default value.
In this embodiment, the performing of the environmental pressure estimation calculation according to the compressed fluid equation specifically includes:
first, the average air mass flow rate at the throttle valve, the intake pressure, the intake temperature, and the throttle opening degree are acquired, and the pressure ratio correction coefficient is calculated.
Then, the current ambient pressure is estimated based on the intake pressure and the pressure ratio correction coefficient.
Referring to FIG. 8, average air mass flow for a typical gasoline engine is characterized by measuring manifold pressure, using the compressible gas equation at the ideal nozzle, average air mass flow at the throttle
Can be described as:
wherein R is a gas constant, TstdIs the standard intake air temperature (20 ℃), pstdIs standard atmospheric pressure (101.3kPa), p0For intake pressure, p is ambient pressure, i.e. atmospheric pressure, AEffIs the effective area of the throttle valve, T0As the temperature of the intake air, there is,
is a pressure ratio
A correction factor for the average air mass flow.
Alternatively, the average air mass flow at the throttle can be monitored in real time by a flow meter.
From the above equation, the pressure ratio can be found when the average mass airflow at the throttle, the intake pressure, the intake temperature, and the throttle opening are known
Correction coefficient of
And estimating the current ambient pressure p according to the pressure ratio of the intake pressure to the corrected intake pressure, and estimating the intake air amount according to the ambient pressure p.
Wherein the content of the first and second substances,
in this example, the pressure ratio
And correction factor
The relationship between them is shown in fig. 9. See fig. 10 for aThe average air mass flow and the effective area of the throttle valve can be obtained through the opening of the throttle valve, the intake air temperature correction coefficient can be obtained through the intake air temperature, and the correction coefficient of the pressure ratio can be obtained according to the intake air pressure so as to obtain the ambient pressure.
Referring to fig. 11, the collected real vehicle operation data is utilized to perform software-in-loop simulation on the proposed ambient pressure indirect estimation algorithm, and from the power-on, starting and running of the engine, along with the change of the engine state, mainly when the state is switched or the opening degree of a throttle valve is large, the estimated ambient pressure will change correspondingly along with the change of the intake pressure, and the error of the intake air amount is controlled within an actual allowable range.
The fault protection method of the embodiment is suitable for all the diagnosis methods, all possible faults are covered by performing electrical connection fault diagnosis, data out-of-range diagnosis and signal drift diagnosis on the pressure sensor, and according to the fault diagnosis and the high reliability of signals, when the pressure sensor is in fault, appropriate environmental pressure can be obtained, so that the requirement of an ECU on the accuracy of the environmental pressure is met.
The present application is not limited to the above embodiments, and it will be apparent to those skilled in the art that various modifications and improvements can be made without departing from the principle of the present application, and such modifications and improvements are also considered to be within the scope of the present application.
Claims (10)
1. A vehicle ambient pressure sensor fault diagnosis method is characterized by comprising the following steps:
after the engine is electrified, acquiring a voltage signal analog quantity of the environmental pressure and a current reference voltage value according to a preset first time interval, and performing proportional correction through a standard reference voltage value to obtain an environmental voltage correction value;
carrying out electrical connection fault diagnosis and rationality fault diagnosis on the environmental pressure sensor periodically through the environmental voltage correction value obtained each time;
if the electrical connection fault is diagnosed, the current diagnosis period of the electrical connection fault is ended in advance, the next diagnosis period of the electrical connection fault is started, and the rationality fault diagnosis is stopped; starting electrical connection fault diagnosis and rationality fault diagnosis at the same time again until an electrical connection fault is not diagnosed in a diagnosis period of the electrical connection fault;
the rationality fault diagnosis comprises data out-of-range diagnosis, and a diagnosis period of the data out-of-range diagnosis is used as a second diagnosis period which is larger than a diagnosis period of the electrical connection fault.
2. The vehicle ambient pressure sensor fault diagnosis method according to claim 1, wherein performing electrical connection fault diagnosis specifically includes:
taking the diagnosis period of the electrical connection fault as a first diagnosis period, if the times that the environmental voltage correction value is greater than the first voltage threshold value in one first diagnosis period are not greater than a first time threshold value and the times that the environmental voltage correction value is less than the second voltage threshold value are not greater than a second time threshold value, determining that the electrical connection fault is not diagnosed in the current first diagnosis period, and entering the next first diagnosis period; the first voltage threshold is greater than a second voltage threshold.
3. The vehicle ambient pressure sensor fault diagnosis method according to claim 2, wherein in the first diagnosis period, the electrical connection fault diagnosis is performed on the ambient pressure sensor by the ambient voltage correction value obtained each time, and specifically includes:
sequentially judging whether the environmental voltage correction value obtained each time in the first diagnosis period is larger than a first voltage threshold or smaller than a second voltage threshold;
when the environmental voltage correction value is larger than a first voltage threshold value, adding one to the first counting value, and if the first counting value after adding one is larger than a first time threshold value, determining that the environmental pressure sensor has short-circuit fault to the power supply, and ending the current first diagnosis period in advance;
and when the environmental voltage correction value is smaller than a second voltage threshold, adding one to the second counting value, and if the second counting value after adding one is larger than a second secondary threshold, determining that the environmental pressure sensor has a short circuit fault to the ground, and ending the current first diagnosis period in advance.
4. The vehicle ambient pressure sensor malfunction diagnosis method according to claim 1, further comprising, before performing the rationality malfunction diagnosis: and converting the environmental voltage correction value obtained each time into a pressure signal according to the voltage-pressure gauge.
5. The method for diagnosing the failure of the vehicle ambient pressure sensor according to claim 4, wherein in the second diagnosis period, the data out-of-range diagnosis is performed on the ambient pressure sensor, and specifically comprises:
sequentially judging whether the pressure signal obtained each time in the second diagnosis period exceeds a preset range;
and when the pressure signal exceeds the preset range, adding one to the third counting value, if the third counting value after adding one is larger than the third counting threshold value, determining that the environmental pressure sensor has data out-of-range fault, ending the current second diagnosis period in advance, and entering the next second diagnosis period.
6. The vehicle ambient pressure sensor malfunction diagnosis method according to claim 5, characterized in that the rationality malfunction diagnosis includes a signal drift diagnosis, a diagnosis period of the signal drift diagnosis is a third diagnosis period, and the third diagnosis period is greater than the second diagnosis period;
in a third diagnostic period, performing signal drift diagnosis on the ambient pressure sensor, specifically including:
taking the difference value of the pressure signals before and after a preset second time interval as the change gradient of the pressure signal; the second preset time interval is not less than the second diagnostic period;
in a third diagnosis period, obtaining the change gradient for multiple times, and performing signal drift diagnosis on the environmental pressure sensor through the change gradient obtained each time;
if the data out-of-range fault is diagnosed in the current second diagnosis period, the current second diagnosis period and the third diagnosis period are both ended in advance, and the next second diagnosis period and the next third diagnosis period are started at the same time.
7. The method for diagnosing a malfunction of a vehicle ambient pressure sensor according to claim 6, wherein in the third diagnostic period, the signal drift diagnosis of the ambient pressure sensor is performed by a change gradient obtained each time, and specifically includes:
sequentially judging whether the change gradient obtained each time in the third diagnosis period is greater than a gradient threshold value;
and when the change gradient is larger than the gradient threshold, adding one to the fourth counting number, and if the fourth counting number after adding one is larger than the fourth counting threshold, determining that the signal drift fault occurs in the environmental pressure sensor, and ending the current third diagnosis period in advance.
8. A fault protection method of a vehicle ambient pressure sensor is characterized by comprising the following steps:
the ambient pressure determination step according to the diagnostic state of the vehicle ambient pressure sensor malfunction diagnosis method according to claim 1 is carried out.
9. The fault protection method of claim 8, wherein:
and if the environmental voltage correction value is abnormal at a certain time and the environmental pressure sensor does not diagnose that the electrical connection fault or the rationality fault occurs, taking the environmental pressure corresponding to the environmental voltage correction value without abnormality at the last time as the current environmental pressure to calculate the air intake quantity.
10. The fault protection method of claim 8,
when the environmental pressure sensor diagnoses an electrical connection fault or a rationality fault, the diagnosis state is a confirmation fault;
judging the current engine state, if the engine is in the running state, performing environmental pressure estimation calculation according to a compressed fluid equation, and taking the obtained estimated environmental pressure as the current environmental pressure; otherwise, taking the intake pressure as the current ambient pressure;
the performing of the environmental pressure estimation calculation according to the compressed fluid equation specifically comprises:
acquiring average air mass flow, air inlet pressure, air inlet temperature and air throttle opening at a throttle valve, and calculating a pressure ratio correction coefficient;
and estimating the current ambient pressure according to the intake pressure and the pressure ratio correction coefficient.
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