CN107503854A - Determine supercharged diesel engine exhaust gas temperature sensor whether exception and method for diagnosing faults - Google Patents

Abstract

The invention relates to a method for determining whether the exhaust gas temperature sensor of a supercharged diesel engine is abnormal and a fault diagnosis method, wherein the method for determining whether the exhaust temperature sensor of a supercharged diesel engine is abnormal includes the following steps: Step 1, comparing the collected value with the observed value, according to Whether the collected value exceeds the error band of the observed value during abnormality and whether the rate of change of the collected value exceeds the maximum rate of change of the observed value determines whether the abnormality occurs; step 2, according to the duration and fixed time period when the collected value exceeds the error band of the observed value when abnormal The number of times the rate of change of the internal collected value exceeds the maximum rate of change of the observed value is used to determine whether the sensor is faulty. This method can realize rapid diagnosis and accurate positioning, and realize rapid maintenance.

Description

Determining whether the exhaust gas temperature sensor of supercharged diesel engine is abnormal and its fault diagnosis method

technical field

The invention generally relates to the field of electronic control of diesel engines, in particular to a method for determining whether an exhaust gas temperature sensor of a supercharged diesel engine is abnormal and a fault diagnosis method.

Background technique

The exhaust temperature sensor is an important part of the diesel engine electronic control system. The exhaust temperature affects the efficiency of the engine. The electronic control system calculates the actual gas volume entering the cylinder according to the exhaust temperature, and then corrects and limits the actual fuel injection volume. Therefore, whether the state of the exhaust gas temperature sensor is normal or not has an important impact on the power, economy and emissions of the diesel engine.

At present, in the fault diagnosis technology of the diesel engine electronic control system, the fault is judged by directly measuring the output voltage of the sensor, such as a thermocouple sensor, whose working principle is that two different material conductors (called thermal electrodes) form a closed loop. When the temperature at the junction of the two ends (working end and reference end) is different and there is a temperature gradient, there will be a current flowing in the circuit, and there will be an electromotive force between the two ends - thermal electromotive force, which is the Seebeck effect. There is a functional relationship between the thermal electromotive force generated by the Seebeck effect and the temperature, and a thermocouple index table is made to obtain the temperature parameter. When the output voltage exceeds the maximum range set by the controller, it is judged that the sensor has failed. The disadvantage is that it is inaccurate to use the output voltage to judge the fault. When the sensor signal is at the millivolt level, it is difficult to measure due to the weak signal, and when the sensor characteristics change or zero point drift occurs, this method cannot detect and is prone to missed detection. Secondly, the output voltage is affected by the power system. If the power system is unstable, this method is prone to false detection.

The information disclosed in this Background section is only intended to increase the understanding of the general background of the present invention and should not be taken as an acknowledgment or any form of suggestion that the information constitutes the prior art that is already known to those of ordinary skill in the art.

Contents of the invention

The purpose of the present invention is to provide a method for determining whether the exhaust gas temperature sensor of a supercharged diesel engine is abnormal and a fault diagnosis method. By comparing and detecting the collected value and the predicted value of the exhaust temperature sensor during operation, the rapid diagnosis and accurate diagnosis of the exhaust temperature sensor can be realized. Positioning increases the reliability of the electronic control system and enables rapid maintenance.

In order to achieve the above object, the present invention provides a method for determining whether the exhaust gas temperature sensor of a supercharged diesel engine is abnormal, including the following steps: Step 1, by constructing an online observer for the exhaust temperature behind the turbocharged diesel engine, the sensor observation value is obtained by online calculation . In step 2, the collected value is compared with the observed value, and the duration of the collected value exceeding the error band of the observed value is used as the judgment condition for the deviation fault of the exhaust temperature sensor to detect whether the fault occurs. Step 3: Detect the number of times that the rate of change of the collected value exceeds the maximum rate of change of the observed value within a fixed period of time, and use it as a condition for determining the fault of the exhaust temperature sensor to detect whether the fault occurs.

Preferably, in the step 1, the on-line observer of the exhaust gas temperature behind the turbo of the output supercharged diesel engine includes the calculation of the exhaust gas temperature before the turbo and the exhaust gas temperature after the turbo.

Preferably, according to claim 2, a diesel engine exhaust temperature sensor fault diagnosis algorithm is characterized in that the calculation of the exhaust gas temperature before the vortex includes the following three steps: Step 1 (a), online collection by the controller The intake air temperature and intake air pressure in the intake pipe after the intercooling of the supercharged diesel engine, and according to the ideal gas state equation, calculate the instantaneous intake air mass flow rate of the diesel engine; step 2 (a), obtain the current cycle fuel injection quantity from the controller, according to The obtained air-fuel mass flow rate is calculated online to obtain the real-time air-fuel ratio; step 3(a), the exhaust temperature factor is obtained from the air-fuel ratio and speed look-up table, and the working fluid caused by in-cylinder combustion is obtained by calculating with the current air-fuel ratio. The temperature is increased, and the increased temperature is added to the intake air temperature to obtain the exhaust gas temperature before the vortex.

Preferably, according to a diesel engine exhaust temperature sensor fault diagnosis algorithm according to claim 2, it is characterized in that the calculation of the exhaust gas temperature after the vortex includes the following two steps: step 1 (b), the controller according to the collected The ambient pressure and the mass flow rate of exhaust gas calculated online are used to calculate the turbo expansion ratio and turbo efficiency by looking up the table. Step 2(b), calculate the exhaust temperature conversion coefficient from before the swirl to after the swirl, which is calculated from the expansion ratio and turbine efficiency, and multiply the exhaust gas temperature before the swirl by the coefficient to obtain the exhaust gas temperature after the swirl.

Preferably, the obtained exhaust temperature value after the vortex is corrected to obtain the exhaust temperature correction value, which is characterized in that the calculation of the exhaust temperature correction value includes two parts: the gain Kd and the acquisition of the pole value Z of the compensator .

Preferably, a diesel engine exhaust temperature sensor fault diagnosis algorithm according to claim 1 is characterized in that the determination of the exhaust temperature sensor deviation fault includes the following three steps: Step 1(c), the controller uses the observed value 25°C is used as the upper and lower limit of the normal variation of the exhaust temperature, and the continuous duration of the collection value of the exhaust temperature sensor exceeding the upper or lower limit is monitored online; step 2(c), if the collection value of the exhaust temperature exceeds the upper or lower limit of the normal change, the abnormality continues The time count value increases, otherwise the abnormal duration count value decreases; when the abnormal duration count value exceeds the maximum limit, the controller determines that a deviation fault has occurred, and the fault recovery count value is cleared, otherwise the abnormal duration count value does not exceed the limit , the failure is not identified; step 3(c), if the deviation fault is identified, when the exhaust temperature collection value is between the upper limit and the lower limit, the fault recovery count value increases, otherwise the fault recovery count value decreases; when the fault recovery count When the value exceeds the maximum limit, the controller determines that the deviation fault is eliminated, and the count value of the abnormal duration is cleared, otherwise, when the fault recovery count value does not exceed the limit value, the fault recovery is not recognized.

Preferably, a diesel engine exhaust temperature sensor fault diagnosis algorithm according to claim 1, wherein the determination of a virtual connection of the exhaust temperature sensor includes the following three steps: Step 1(d), the controller uses the rate of change 40°C/s is used as the maximum rate of change of the exhaust temperature sensor when it is normal, and the number of times the collected value of the exhaust temperature sensor exceeds the maximum rate of change is monitored within every 10s. Every time the maximum rate of change is exceeded, the abnormal count value increases by 1; Step 2( d) If the value collected by the exhaust temperature sensor exceeds the maximum change rate for 4 times within 10s, the controller will determine that a virtual connection fault has occurred, and the fault recovery count value will be cleared; otherwise, the abnormal count value will be cleared after every 10s, For the next 10s detection. Step 3(d), if it is determined that a virtual connection fault has occurred, the controller will monitor whether the collected value of the exhaust temperature sensor still exceeds the maximum rate of change within 20 consecutive seconds. Otherwise, the fault state is not eliminated.

Compared with the prior art, the present invention has the following beneficial effects: the exhaust gas temperature sensor fault diagnosis algorithm has real-time performance, and can calculate the exhaust gas temperature value in real time during the high-speed operation of the diesel engine; the parameters used in the algorithm are conventional diesel engine electronic control systems The data collected and calculated has the ability of online observation; the algorithm is simple and practical, and can be realized in the software of the diesel engine electronic control system through programming.

Description of drawings

Figure 1 is a schematic diagram of the deviation fault of the exhaust gas temperature sensor of a supercharged diesel engine;

Figure 2 is a schematic diagram of a virtual connection fault of a supercharged diesel engine exhaust temperature sensor;

Fig. 3 is a composition schematic diagram of a supercharged diesel engine exhaust temperature sensor according to the present invention;

Figure 4 Schematic diagram of temperature factor MAP before vortex;

Figures 5 and 6 are schematic diagrams of a diagnosis method for determining whether the exhaust gas temperature sensor of a supercharged diesel engine is abnormal during operation;

Fig. 7 is a principle schematic diagram of a fault diagnosis method for an air intake pressure sensor of a supercharged diesel engine according to the present invention.

detailed description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. In this regard, embodiments of the invention may have different forms and should not be construed as limited to the descriptions set forth herein. Accordingly, the embodiments are merely described below, by referring to the figures, to illustrate aspects of the present invention.

The specific embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, but it should be understood that the protection scope of the present invention is not limited by the specific embodiments.

Unless expressly stated otherwise, throughout the specification and claims, the term "comprise" or variations thereof such as "includes" or "includes" and the like will be understood to include the stated elements or constituents, and not Other elements or other components are not excluded.

The thermocouple sensor consists of two different conductors, A and B, which are closely connected to each other to form a closed loop. Among them, the two conductors A and B are called thermal electrodes. Among the two connecting nodes, one is placed in the measured temperature field during temperature measurement, which is called the working end; the other is placed at a constant temperature. environment, known as the reference junction. The basic working principle of the thermocouple sensor is based on the thermoelectric effect of the object, that is, when the temperature of the working end and the reference end are not equal (T>T0), due to the different voltages generated by the two conductors A and B due to the temperature difference, a This phenomenon is called thermoelectric effect, and the generated electromotive force is called thermoelectric potential. The size of the thermoelectric potential is related to the properties of the two conductor materials and the junction temperature. The numerical correspondence between the thermoelectric potential and temperature can be obtained through experiments, so as to establish a thermocouple index table. In the practical application of thermocouple sensors, the temperature information can be obtained by looking up the table by measuring the thermoelectric potential.

As shown in Figure 1 and Figure 2, there are mainly two types of sensor faults: deviation faults and virtual connection faults. Virtual connection fault means that the connection between the sensor and the wiring harness is not reliable enough, resulting in unstable operation of the sensor, and it returns to normal after a large shock in a short period of time. The fault performance is shown in Figure 2. The fault is characterized by rapid changes and large changes, and can occur multiple times within a certain period of time. The virtual connection fault causes the exhaust gas temperature value obtained by the ECU to change drastically in a short period of time, which affects the stable operation of the diesel engine and the triggering of the protection strategy. In addition, the virtual junction will often turn into a complete open circuit state with the driving bumps, resulting in the sensor being unable to collect the exhaust gas temperature. Deviation fault means that there is a fixed difference between the collected value of the exhaust gas temperature sensor and the normal value, resulting in inaccurate measurement. The failure performance is shown in Figure 1. When the difference is small, the impact on the diesel engine is small and it is not easy to find out; when the difference is large, it means that the collected value of the exhaust temperature is seriously out of the normal range, and even exceeds the exhaust temperature threshold, causing the ECU to make an error Judgment, there is an alarm for excessive exhaust temperature, which affects the normal operation of the diesel engine.

As shown in Figures 5 and 6, the method for determining whether the supercharged diesel engine exhaust temperature sensor is abnormal and the fault diagnosis method according to the specific embodiment of the present invention is based on the existing sensor, by constructing an online observation of the turbocharged diesel engine exhaust temperature The sensor can be calculated online to obtain the observed value of the sensor, and the collected value is compared with the observed value to quickly and accurately diagnose the fault of the supercharged diesel engine exhaust temperature sensor, whether it is to increase the reliability of the electronic control system or to improve the rapid maintenance. Sex has important practical implications. Specifically, according to the duration of the collected value exceeding the error band of the observed value during abnormality and the number of times the rate of change of the collected value exceeds the maximum rate of change of the observed value within a fixed period of time. Finally, the controller can also determine whether the fault has been eliminated according to the number of times the sensor returns to normal and whether the collected value exceeds the maximum rate of change within a fixed time.

As shown in Figure 3, the online observer of turbocharged diesel engine exhaust temperature includes the calculation of exhaust temperature before the turbo and the exhaust temperature after the turbo, as well as dynamic correction. The controller calculates the turbine expansion ratio and turbine efficiency through a look-up table according to the collected ambient pressure and the online calculated exhaust gas mass flow. The controller collects the intake air temperature and intake pressure in the intercooled intake pipe of the supercharged diesel engine online, and calculates the instantaneous intake air mass flow rate of the diesel engine according to the ideal gas state equation; The obtained air-fuel mass flow rate is calculated online to obtain the real-time air-fuel ratio; the controller obtains the exhaust temperature factor through the table look-up program, and calculates with the current air-fuel ratio to obtain the temperature rise of the working fluid caused by the combustion in the cylinder, and the temperature rise Add the intake air temperature to get the exhaust temperature before the vortex; calculate the conversion coefficient of the exhaust temperature from the front of the vortex to the rear of the vortex. Temperature, the obtained exhaust temperature after the vortex is corrected by the first-order lag compensator to obtain the corrected observation value of the exhaust temperature behind the vortex.

As shown in Figure 4, the air-fuel ratio and rotational speed are used to simulate and fit the pre-vortex temperature factor, and MATLAB is used to perform two-dimensional interpolation on the processed data to obtain the MAP schematic diagram of the pre-vortex temperature factor.

As shown in Figure 5, firstly, the deviation fault identification of the exhaust temperature sensor is carried out. Specifically, the controller takes the observed value °C as the upper and lower limits of the normal change of the exhaust temperature, and monitors the continuous continuous occurrence of the exhaust temperature sensor’s collection value exceeding the upper or lower limit online. time. Detect whether the exhaust gas temperature value measured by the sensor exceeds the upper and lower limit range of the normal change of the exhaust temperature. If it exceeds the upper and lower limit range, the controller judges that the sensor is abnormal, otherwise the sensor is not abnormal. Because after the sensor design is completed, its characteristic curve (the relationship between the measured temperature and time) must meet the requirements of the use range. Therefore, when the exhaust gas temperature measured by the sensor is outside the characteristic curve (see Figure 2), if it exceeds 25°C of the temperature value on the characteristic curve or is lower than 25°C of the temperature value, it means that the measured temperature is no longer within the use range Inside, it does not conform to the sensor design, so the controller detects that the sensor is abnormal. In addition, there are errors in general sensor processing, so the upper and lower limits are not a specific value, there will be a slight deviation but must be within 5%.

Secondly, identify the fault of the exhaust gas temperature sensor as a virtual connection. Specifically, the controller uses a change rate of 40°C/s as the maximum change rate of the exhaust temperature sensor when it is normal. If the maximum change rate exceeds the maximum change rate, the controller judges that the sensor is abnormal. Otherwise, the sensor is normal. Because after the sensor design is completed, its characteristic curve (the relationship between the measured temperature and time) must meet the requirements of the use range. Therefore, when the change rate of the exhaust gas temperature measured by the sensor exceeds the maximum change rate at a certain moment (see Figure 2), it means that the measured temperature is no longer within the range of use and does not conform to the sensor design, so the controller detects that the sensor is abnormal . In addition, there are errors in general sensor processing, so the upper and lower limits are not a specific value, there will be a slight deviation but must be within 5%.

As shown in Figure 5, the above-mentioned deviation identification of the exhaust gas temperature sensor only determines whether the sensor is abnormal, and it is necessary to determine whether the sensor is faulty or not through a fault identification method based on continuous time. That is, when the duration of abnormal occurrence exceeds the first predetermined value, it is determined that a fault has occurred. When the sensor fault has occurred, the controller starts to judge whether the sensor has returned to normal. If the abnormal state disappears and the exhaust temperature collection value is between the upper limit and the lower limit, it is determined that the fault has been eliminated. Among them, the above-mentioned first predetermined value can be specifically set to 10s. If the abnormality continues to occur without interruption, the diesel engine controller will determine that the fault has occurred. eliminate. details as follows:

1) When the exhaust gas temperature sensor has never failed, the fault judgment of the exhaust gas temperature sensor is performed; if the exhaust gas temperature sensor has been determined to be faulty, the fault removal judgment of the exhaust temperature sensor is performed.

2) When the exhaust temperature sensor has never failed and the exhaust temperature sensor has no abnormality, it means that the exhaust temperature sensor is in normal working condition, so the abnormal count value is reset to zero, and the exhaust temperature sensor is not faulty.

3) When the exhaust temperature sensor has never failed, but the exhaust temperature sensor is abnormal, it means that the exhaust temperature sensor has a problem, but it cannot be determined that the fault has occurred, so increase the abnormal count, and pass the abnormal duration time (the abnormal count indicates the fault duration) to determine whether the fault actually occurred. If the accumulation of abnormal counts reaches the first predetermined value during operation, the controller determines that a fault has occurred. At this time, the fault recovery count value should be cleared to be used when the exhaust gas temperature sensor recovers to judge. If the abnormality count does not reach the first predetermined value during operation, the state of the exhaust temperature sensor is not changed, that is, the exhaust temperature sensor is regarded as a normal state.

4) When the exhaust temperature sensor has failed, but there is no abnormality in the detection of the exhaust temperature sensor, it means that the abnormality of the exhaust temperature sensor has disappeared, but it cannot be determined that the fault has been resolved, so increase the fault recovery count and pass the duration of the abnormal disappearance (Fault recovery count shows the duration of fault elimination) to judge whether the fault is really eliminated. If the accumulation of the fault recovery count reaches the second predetermined value during the operation, the controller determines that the fault has been eliminated. At this time, the abnormal count value should be cleared to be used in case of failure judgment of the exhaust gas temperature sensor. If the failure recovery count does not reach the second predetermined value during operation, the state of the exhaust temperature sensor is not changed, that is, the exhaust temperature sensor is regarded as a failure state.

5) When the exhaust temperature sensor has failed and the detection of the exhaust temperature sensor is also abnormal, it means that the exhaust temperature sensor is still in the fault state. Therefore, the fault recovery count value is cleared, and the controller considers that the exhaust gas temperature sensor is always in a fault state

As shown in Figure 6, the above-mentioned virtual connection identification of the exhaust gas temperature sensor only determines whether the sensor is abnormal, and it is necessary to determine whether the sensor is faulty through a fault identification method based on the number of times exceeding the maximum rate of change within a fixed period of time. That is, when the number of times of abnormal rate of change exceeds the first predetermined value, it is determined that a fault has occurred. When the sensor failure has occurred, the controller starts to judge whether the sensor has returned to normal. If the abnormal state disappears and the rate of change of the exhaust temperature collection value is within the maximum rate of change, it is determined that the fault has been eliminated. Among them, the above-mentioned fixed time is set to 10s, and the predetermined value can be set to 4. If the abnormality continues to appear without interruption, the diesel engine controller will determine that a fault has occurred. Similarly, when the abnormal state disappears and the recovery time reaches 20s, the diesel engine will control The device determines that the fault has been eliminated. details as follows:

1) When the exhaust gas temperature sensor has never failed, the fault judgment of the exhaust gas temperature sensor is performed; if the exhaust gas temperature sensor has been determined to be faulty, the fault removal judgment of the exhaust temperature sensor is performed.

2) When the exhaust temperature sensor has never failed and the exhaust temperature sensor has no abnormality, it means that the exhaust temperature sensor is in normal working condition, so the abnormal count value is reset to zero, and the exhaust temperature sensor is not faulty.

3) When the exhaust temperature sensor has never failed, but the exhaust temperature sensor is abnormal, it means that the exhaust temperature sensor has a problem, but it cannot be determined that the fault has occurred, so increase the abnormal count, and pass the number of times exceeding the maximum change rate (abnormal count Indicate the number of times the maximum rate of change has been exceeded) to determine whether the fault actually occurred. If the accumulation of abnormal counts reaches the first predetermined value during operation, the controller determines that a fault has occurred. At this time, the fault recovery count value should be cleared to be used when the exhaust gas temperature sensor recovers to judge. If the abnormality count does not reach the first predetermined value during operation, the state of the exhaust temperature sensor is not changed, that is, the exhaust temperature sensor is regarded as a normal state.

4) When the exhaust temperature sensor has failed, but there is no abnormality in the detection of the exhaust temperature sensor, it means that the abnormality of the exhaust temperature sensor has disappeared, but it cannot be determined that the fault has been resolved, so increase the fault recovery count and pass the duration of the abnormal disappearance (Fault recovery count shows the duration of fault elimination) to judge whether the fault is really eliminated. If the accumulation of the fault recovery count reaches the second predetermined value during the operation, the controller determines that the fault has been eliminated. At this time, the abnormal count value should be cleared to be used in case of failure judgment of the exhaust gas temperature sensor. If the failure recovery count does not reach the second predetermined value during operation, the state of the exhaust temperature sensor is not changed, that is, the exhaust temperature sensor is regarded as a failure state.

5) When the exhaust temperature sensor has failed and the detection of the exhaust temperature sensor is also abnormal, it means that the exhaust temperature sensor is still in the fault state. Therefore, the fault recovery count value is cleared, and the controller considers that the exhaust gas temperature sensor is always in a fault state

The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. These descriptions are not intended to limit the invention to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teaching. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling others skilled in the art to make and use various exemplary embodiments of the invention, as well as various Choose and change. It is intended that the scope of the invention be defined by the claims and their equivalents.

Those of ordinary skill in the art can understand that all or part of the steps in the above method can be completed by instructing related hardware (such as a processor) through a program, and the program can be stored in a computer-readable storage medium, such as a read-only memory, magnetic disk or optical disk Wait. Optionally, all or part of the steps in the foregoing embodiments may also be implemented using one or more integrated circuits. Correspondingly, each module/unit in the above-mentioned embodiments can be implemented in the form of hardware, such as implementing its corresponding functions through an integrated circuit, or can be implemented in the form of software function modules, such as executing a program stored in a memory by a processor. programs/instructions to realize their corresponding functions. The present invention is not limited to any specific combination of hardware and software.

Although the embodiments disclosed in the present application are as above, the content described is only the embodiments adopted to facilitate understanding of the present application, and is not intended to limit the present application, such as the specific implementation method in the embodiments of the present invention. Anyone skilled in the field of this application can make any modifications and changes in the form and details of implementation without departing from the spirit and scope disclosed in this application, but the scope of patent protection of this application must still be The scope defined by the appended claims shall prevail.

The above description is a preferred embodiment of the present invention, it should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, and these improvements and modifications can also be made. It should be regarded as the protection scope of the present invention.

Claims (7)

1. a kind of diesel engine exhaust temperature sensor fault diagnosis algorithm, it is characterised in that comprise the following steps：

Step 1, by building supercharged diesel engine whirlpool heel row temperature online observation device, sensor observation is calculated online；

Step 2, collection value and observation are contrasted, according to collection value during exception beyond observation error band it is lasting when Between, as exhaust temperature sensor deviation fault decision condition, to detect whether the failure occurs；

Step 3, the number that collection value rate of change in fixed time period exceeds observation maximum rate of change is detected, as row's temperature sensing Device fault verification condition, to detect whether the failure occurs.

2. a kind of diesel engine exhaust temperature sensor fault diagnosis algorithm according to claim 1, it is characterised in that in the step In rapid 1, output supercharged diesel engine whirlpool heel row temperature online observation device, whirlpool front exhaust temperature computation and whirlpool final vacuum temperature are included Calculate.

3. a kind of diesel engine exhaust temperature sensor fault diagnosis algorithm according to claim 2, it is characterised in that in the whirlpool Front exhaust temperature computation includes following three step：

Step 1 (a), by cold laggard endotracheal intake air temperature and admission pressure in controller online acquisition supercharged diesel engine, and According to The Ideal-Gas Equation, instantaneous diesel engine intake mass flow is calculated；

Step 2 (a), previous cycle distributive value is obtained from controller, according to acquired air-mass flow, is calculated online Real-time air-fuel ratio；

Step 3 (a), tabled look-up to obtain the delivery temperature factor by air-fuel ratio and rotating speed, drawn with current air fuel ratio computing because of cylinder internal combustion Working medium caused by burning raises temperature, and elevated temperature is added to obtain whirlpool front exhaust temperature with intake air temperature.

4. a kind of diesel engine exhaust temperature sensor fault diagnosis algorithm according to claim 2, it is characterised in that in the whirlpool Final vacuum temperature computation includes following two steps：

Step 1 (b), controller pass through computation of table lookup according to the environmental pressure collected and in the exhaust air mass flow of line computation Expansion ratio of turbine and turbine efficiency.

Step 2 (b), calculate whirlpool before to whirlpool heel row temperature conversion coefficient, the value is obtained by expansion ratio and turbine efficiency computing, before whirlpool Delivery temperature is multiplied by coefficient and obtains whirlpool final vacuum temperature.

5. whirlpool heel row temperature value acquired by obtains delivery temperature correction value by amendment, it is characterised in that in the exhaust Temperature corrected value calculates and includes two parts：The pole value Z of gain Kd and compensator acquisition.

6. a kind of diesel engine exhaust temperature sensor fault diagnosis algorithm according to claim 1, it is characterised in that in the row Temperature sensor deviation fault judges to include following two steps：

Step 1 (d), controller are used as threshold value basis for selecting, ± 25 DEG C of conducts of selection using controller using judging nicety rate as 80% Judgment threshold.The bound of i.e. warm normal variation, and exhaust temperature sensor collection value is monitored on-line beyond the continuous of the upper limit or lower limit Duration；

Step 3 (d), if arranging the upper limit or lower limit that warm collection value exceeds normal variation, the increase of Abnormal lasting count value, instead Abnormal lasting count value reduce；When Abnormal lasting count value exceeds threshold limit value, controller assert deviation event Barrier occurs, and fault recovery count value is reset, otherwise Abnormal lasting count value is without departing from limit value, does not assert failure；

Step 4 (d), if after deviation fault is assert, when the warm collection value of row is between upper and lower bound, fault recovery count value Increase, on the contrary fault recovery count value reduces；When fault recovery count value exceeds threshold limit value, controller assert deviation fault Eliminate, Abnormal lasting count value is reset, otherwise fault recovery count value is without departing from limit value, does not assert fault recovery.

7. a kind of diesel engine exhaust temperature sensor fault diagnosis algorithm according to claim 1, it is characterised in that in the row Temperature sensor virtual connection fault verification includes following two steps：

Step 1 (e), maximum rate of change of the controller using 40 DEG C/s of rate of change as exhaust temperature sensor when normal, and in every 10s The number that exhaust temperature sensor collection value exceeds maximum rate of change is monitored, often more than maximum rate of change 1 time, anomalous counts value increase by 1；

Step 2 (e), if exhaust temperature sensor collection value occurs 4 times beyond the situation of maximum rate of change in 10s, controller Assert that virtual connection failure occurs, fault recovery count value is reset；Otherwise anomalous counts value is reset after per 10s, in case next 10s Detection.

Step 3 (e), if assert, virtual connection failure occurs, and whether controller monitors exhaust temperature sensor collection value in continuous 20s Still there is the situation beyond maximum rate of change, if continuous 20s does not occur exception, assert that sensor recovers normal, on the contrary failure shape State does not eliminate.