EGR fault diagnosis method, system and vehicle

Abstract

The present invention provides a method, system and vehicle for EGR fault diagnosis, the method comprising: periodically detecting the pressure value of the gas at the rear end of the EGR valve; determining the relationship between the pressure value of the gas at the rear end of the EGR valve and the preset pressure value in the current cycle, and accordingly monitoring the temperature of the EGR valve end for a preset time in the current cycle to determine the relationship between the temperature increment of the temperature at the EGR valve end in the preset time and the preset increment; when it is detected that the pressure value of the gas at the rear end of the EGR valve in the current cycle is continuously greater than or equal to the preset pressure value, and the temperature increment of the temperature at the EGR valve end in the preset time exceeds the preset increment, outputting an alarm message. The method described in the present invention aims to solve the problem that the existing high flow fault diagnosis scheme based on the temperature before the EGR valve has poor anti-interference ability and is prone to missed reports or false reports. At the same time, additional auxiliary diagnosis configuration is added in the application, increasing the diagnosis cost.

Description

Technical Field

[0001] The present invention relates to the field of vehicle engineering technology, and in particular to an EGR fault diagnosis method, system and vehicle. Background Art

[0002] Exhaust Gas Recirculation, Exhaust Gas Recirculation System (EGR) is to send a small part of the exhaust gas generated by a diesel engine or gasoline engine back to the cylinder for combustion. Increasing the exhaust gas recirculation rate will reduce the total exhaust gas flow, so that the total pollutant output in the exhaust emission will be relatively reduced.

[0003] Emission regulations require that engines equipped with exhaust gas recirculation systems must have an EGR flow rate high fault diagnosis function. In the prior art solution for high-flow fault diagnosis of EGR based on the temperature before the EGR valve, since a condenser is provided next to the EGR valve structure, the measurement point of the temperature sensor before the valve is easily affected by the heat radiation of the condenser, and the temperature rise will occur in the case of non-high-flow faults, and the temperature rise may be higher than the temperature rise in certain fault conditions, which can easily cause false alarms. In other words, in the existing solution for high-flow fault diagnosis of EGR based on the temperature before the EGR valve, due to the influence of the structural design, the solution has poor anti-interference ability and is prone to missed reports or false alarms. At the same time, the application is forced to increase the use of additional auxiliary diagnostic configurations, resulting in increased diagnostic costs. Summary of the invention

[0004] In view of this, the present invention aims to propose a method, system and vehicle for EGR fault diagnosis, so as to solve the problem that the existing solution for diagnosing high flow fault based on the temperature before the EGR valve is poor in anti-interference ability due to the influence of structural design, and is prone to missed alarms or false alarms. At the same time, the application is forced to add additional configurations for auxiliary diagnosis, which increases the diagnostic cost.

[0005] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0006] A method for EGR fault diagnosis, the method comprising:

[0007] Periodically test the pressure value of the gas at the rear end of the EGR valve;

[0008] Determine the relationship between the pressure value of the gas at the rear end of the EGR valve and the preset pressure value in the current cycle;

[0009] According to the relationship between the pressure value of the gas at the rear end of the EGR valve in the current cycle and the preset pressure value, the temperature of the EGR valve end is monitored for a preset time in the current cycle, and the relationship between the temperature increment of the temperature of the EGR valve end in the preset time in the current cycle and the preset increment is determined;

[0010] When it is detected that the pressure value of the gas at the rear end of the EGR valve is continuously greater than or equal to the preset pressure value in the current cycle, and the temperature increment of the EGR valve end within the preset time period exceeds the preset increment, an alarm message of excessive exhaust gas flow is output.

[0011] Furthermore, the method further comprises:

[0012] Determine a preset pressure value corresponding to the working condition of the vehicle in the current cycle, wherein different working conditions correspond to different preset pressure values;

[0013] When it is detected that the pressure value of the gas at the rear end of the EGR valve is continuously greater than or equal to the preset pressure value in the current cycle, and the temperature increment of the temperature at the EGR valve end within the preset time period exceeds the preset increment, an alarm message of the exhaust gas flow exceeding the standard is output, including:

[0014] When the pressure value of the gas at the rear end of the EGR valve is greater than or equal to the preset pressure value and lasts for a first preset time during the current cycle, and the temperature increment of the EGR valve end exceeds the preset increment during the preset time, an alarm message of excessive exhaust gas flow is output.

[0015] Further, the monitoring of the temperature of the EGR valve end for a preset time in the current cycle according to the relationship between the pressure value of the gas at the rear end of the EGR valve in the current cycle and the preset pressure value includes:

[0016] When it is determined that the pressure value of the gas at the rear end of the EGR valve in the current cycle is greater than or equal to the preset pressure value, the temperature of the EGR valve end is monitored for a preset time period in the current cycle.

[0017] Furthermore, the temperature increment is an increment between a first temperature and a second temperature, the first temperature being the temperature of the EGR valve end at a starting moment within a preset time length, and the second temperature being the temperature of the EGR valve end at an ending moment within the preset time length.

[0018] Furthermore, the pressure value of the gas at the rear end of the EGR valve includes at least one of the pressure value of the exhaust gas near the EGR valve and the pressure value of the manifold gas at the intake manifold, wherein the manifold gas at the intake manifold is air or a mixture of air and the exhaust gas.

[0019] Further, when it is detected that the pressure value of the gas at the rear end of the EGR valve is continuously greater than or equal to the preset pressure value in the current cycle, and the temperature increment of the temperature at the EGR valve end within the preset time period exceeds the preset increment, outputting the alarm information of the exhaust gas flow exceeding the standard includes:

[0020] When at least one of the following is true: when it is detected that the pressure value of the exhaust gas near the EGR valve in the current cycle is greater than or equal to the preset pressure value of the exhaust gas and lasts for a second preset time, and when it is detected that the pressure value of the manifold gas at the intake manifold in the current cycle is greater than or equal to the preset pressure value of the manifold gas and lasts for a third preset time, and when the temperature increment at the EGR valve end exceeds the preset increment within the preset time, an alarm message of excessive exhaust gas flow is output.

[0021] Furthermore, the periodic detection of the pressure value of the gas at the rear end of the EGR valve includes:

[0022] Obtain detection parameters of the periodic detection, including: detection window time, detection interval time, and continuous detection frequency;

[0023] Based on the detection parameters, the pressure value of the gas at the rear end of the EGR valve is periodically detected.

[0024] Furthermore, the method further comprises:

[0025] When the temperature of the EGR valve end exceeds the preset temperature, an alarm message indicating that the exhaust gas flow exceeds the standard is output. Compared with the prior art, the EGR fault diagnosis method of the present invention has the following advantages:

[0026] (1) The EGR fault diagnosis method described in the present invention proposes an EGR fault diagnosis method based on the laws of physical characteristics without adding additional sensor configuration, thereby saving hardware development and supporting costs.

[0027] (2) The EGR fault diagnosis method described in the present invention is a composite judgment method based on the pressure value of the gas at the rear end of the EGR valve and the temperature at the EGR valve end, which effectively increases the accuracy of EGR fault diagnosis, eliminates the possibility of false alarms and missed alarms as much as possible, and meets more stringent regulatory requirements.

[0028] Another object of the present invention is to propose a system for EGR fault diagnosis to solve the problem that the existing solution for diagnosing high flow faults based on the temperature before the EGR valve is poor in anti-interference ability due to the influence of structural design, and is prone to missed reports or false reports. At the same time, the application is forced to add additional configurations for auxiliary diagnosis, which increases the diagnostic cost.

[0029] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0030] A system for EGR fault diagnosis, the system comprising:

[0031] A detection module, used for periodically detecting the pressure value of the gas at the rear end of the EGR valve;

[0032] A first determination module, used to determine the relationship between the pressure value of the gas at the rear end of the EGR valve and a preset pressure value in a current cycle;

[0033] a second determination module, configured to monitor the temperature of the EGR valve end for a preset time period in the current cycle according to the relationship between the pressure value of the gas at the rear end of the EGR valve and the preset pressure value in the current cycle, and determine the relationship between the temperature increment of the temperature of the EGR valve end within the preset time period and the preset increment in the current cycle;

[0034] The alarm module is used to output an alarm message of excessive exhaust gas flow when it detects that the pressure value of the gas at the rear end of the EGR valve is continuously greater than or equal to a preset pressure value in the current cycle, and the temperature increment of the EGR valve end within the preset time period exceeds a preset increment.

[0035] The advantages of the EGR fault diagnosis system and the above-mentioned EGR fault diagnosis method over the prior art are the same, which will not be repeated here.

[0036] Another object of the present invention is to propose a vehicle to solve the problem that the existing solution for diagnosing high flow faults based on the temperature before the EGR valve is poor in anti-interference ability due to the structural design, and is prone to missed reports or false reports. At the same time, the application is forced to add additional configurations for auxiliary diagnosis, which increases the diagnostic cost.

[0037] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0038] A vehicle comprises: the above-mentioned EGR fault diagnosis system.

[0039] The advantages of the vehicle and the above-mentioned EGR fault diagnosis system over the prior art are the same, which will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0041] Figure 1 is a schematic diagram of a method for EGR fault diagnosis shown in an embodiment of the present application;

[0042] Figure 2 It is a schematic diagram of periodically detecting the pressure value of the gas at the rear end of the EGR valve in a method for diagnosing an EGR fault according to an embodiment of the present application;

[0043] Figure 3 It is a cycle diagram of a method for EGR fault diagnosis shown in an embodiment of the present application;

[0044] Figure 4 It is a logic relationship diagram of pressure difference detection of a method for EGR fault diagnosis shown in an embodiment of the present application;

[0045] Figure 5 It is a logical relationship diagram of temperature increment of a method for diagnosing EGR faults shown in an embodiment of the present application;

[0046] Figure 6 It is a schematic diagram of an EGR fault diagnosis system shown in an embodiment of the present application. DETAILED DESCRIPTION

[0047] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0048] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0049] Before explaining the EGR fault diagnosis method provided by the present application, the following is a brief explanation of the method of diagnosing high flow faults by using the temperature before the EGR valve in the relevant technical field. The current traditional method of diagnosing high flow faults by using the temperature before the EGR valve is to set a temperature sensor before the EGR valve and determine whether the EGR flow is too high based on the measured temperature. However, in the tightly coupled design structure of the EGR valve and the condenser, due to the limitation of the narrow layout space, the measuring point of the temperature sensor before the valve is easily affected by the thermal radiation of the condenser, resulting in a temperature rise in non-high flow fault conditions, and the temperature rise may be higher than the temperature rise in certain fault conditions. This method has poor anti-interference ability and is prone to missed reports or false alarms, and may also cause the EGR processing to fail to meet the relevant regulations. At the same time, during the application process, it is forced to consider adding additional configurations specifically for auxiliary diagnosis, which increases costs.

[0050] Therefore, based on the above problems, the present invention provides a method for EGR fault diagnosis, which effectively increases the accuracy of EGR fault diagnosis through a composite judgment method based on the pressure value of the gas at the rear end of the EGR valve and the temperature at the EGR valve end, eliminates the possibility of false alarms and missed alarms as much as possible, and meets more stringent regulatory requirements. At the same time, the method of the present invention does not require the addition of additional sensors, and is only based on the laws of physical characteristics, effectively saving hardware development and supporting costs.

[0051] Figure 1 Schematic diagram of a method for EGR fault diagnosis shown in one embodiment of the present application. Figure 1 The EGR fault diagnosis method provided by the present application comprises the following steps:

[0052] Step S11: Periodically detect the pressure value of the gas at the rear end of the EGR valve.

[0053] In this embodiment, before periodically detecting the pressure value of the gas at the rear end of the EGR valve to diagnose the fault of the EGR, it is necessary to determine the vehicle state. When it is determined that the vehicle is in a preset state, the periodic detection of the pressure value of the gas at the rear end of the EGR valve is started. The preset state of the vehicle is during non-dynamic transition conditions such as parking idling or parking charging after the engine is started, there is no control system fault, and the EGR is in a non-working state.

[0054] In the present application, the periodic detection of the pressure value of the gas at the rear end of the EGR valve includes: obtaining the detection parameters of the periodic detection, including: the detection window time t w , detection interval time t wd , continuous detection frequency n; based on the detection parameters, periodically detecting the pressure value of the gas at the rear end of the EGR valve.

[0055] In this embodiment, the pressure value of the gas at the rear end of the EGR valve needs to be periodically detected based on the detection parameters of the periodic detection. Therefore, before the pressure value of the gas at the rear end of the EGR valve is periodically detected, the detection parameters of the periodic detection need to be obtained first, including: detection window time, detection interval time, and continuous detection frequency.

[0056] Figure 2 1 is a schematic diagram of a method for diagnosing EGR faults in accordance with an embodiment of the present application, which periodically detects the pressure value of the gas at the rear end of the EGR valve. Figure 2 Each time the pressure value of the gas at the rear end of the EGR valve is detected, it is within the detection window time t w The time interval between two consecutive detections of the pressure value of the gas at the rear end of the EGR valve is the detection interval time t wd The number of periodic detections of the pressure value of the gas at the rear end of the EGR valve is the continuous detection frequency n.

[0057] Figure 3 1 is a cycle diagram of a method for EGR fault diagnosis shown in an embodiment of the present application. Figure 3 , before testing the pressure value of the gas at the rear end of the EGR valve in each detection window time during a complete periodic detection process, it is necessary to determine whether the vehicle is in the preset state. When it is determined that the vehicle is not in the preset state, the fault detection is stopped; when it is determined that the vehicle is in the preset state, the i-th detection window is activated. If the i-th detection window time t w There is no fault code within the interval detection time t wd Afterwards, when it is determined that i of the i-th detection window is less than n-1, an addition operation is performed on i.

[0058] After adding 1 to i, when it is determined that the vehicle is in the preset state, the i+1th detection window is activated. If the i-th detection window time t w There is no fault code within the interval detection time t wd After that, when it is determined that i+1 of the i+1th detection window is less than n-1, an addition operation is performed on i+1. Until a certain detection window time t within the continuous detection frequency n w If a fault code appears within t, an alarm message of exhaust gas flow exceeding the standard is output, and the diagnosis is terminated, or within the continuous detection frequency n, all detection window times t w If no fault code appears, the diagnosis ends. The initial value of i is 1.

[0059] Step S12: Determine the relationship between the pressure value of the gas at the rear end of the EGR valve in the current cycle and the preset pressure value.

[0060] In this embodiment, during the periodic detection of the pressure value of the gas at the rear end of the EGR valve in step S11, step S12 determines the relationship between the pressure value of the gas at the rear end of the EGR valve in the current period and the preset pressure value.

[0061] The relationship between the pressure value of the gas at the rear end of the EGR valve in the current cycle and the preset pressure value includes: the pressure value of the gas at the rear end of the EGR valve in the current cycle is greater than or equal to the preset pressure value; the pressure value of the gas at the rear end of the EGR valve in the current cycle is less than the preset pressure value. The current cycle is the current number of times the pressure value of the gas at the rear end of the EGR valve is detected.

[0062] Preferably, in the present invention, the preset pressure value is set according to actual needs and is not specifically limited here.

[0063] For example, when the pressure value of the gas at the rear end of the EGR valve is detected during the first detection window time, the current cycle is the first detection window time, and the relationship between the pressure value of the gas at the rear end of the EGR valve and the preset pressure value during the detection process during the first detection window time is determined. When the pressure value of the gas at the rear end of the EGR valve is detected during the nth detection window time, the current cycle is the nth detection window time, and the relationship between the pressure value of the gas at the rear end of the EGR valve and the preset pressure value during the detection process during the nth detection window time is determined.

[0064] Step S13: Based on the relationship between the pressure value of the gas at the rear end of the EGR valve in the current cycle and the preset pressure value, the temperature of the EGR valve end is monitored for a preset time in the current cycle, and the relationship between the temperature increment of the temperature of the EGR valve end in the preset time and the preset increment in the current cycle is determined.

[0065] In this embodiment, when it is detected that the pressure value of the gas at the rear end of the EGR valve in the current cycle is greater than or equal to the preset pressure value, the monitoring of the temperature of the EGR valve end is started, and while the pressure value of the gas at the rear end of the EGR valve is detected in the current cycle, the temperature of the EGR valve end is monitored for a preset time in the current cycle. During the process of monitoring the temperature of the EGR valve end for a preset time in the current cycle, the relationship between the temperature increment of the temperature of the EGR valve end in the preset time and the preset increment in the current cycle is determined.

[0066] When the pressure value of the gas at the rear end of the EGR valve is less than the preset pressure value in the current cycle, the detection interval time t wd After that, the pressure value of the gas at the rear end of the EGR valve is detected in the next cycle of the current cycle.

[0067] For example, when the pressure value of the gas at the rear end of the EGR valve is detected within the first detection window time in the current cycle, when it is detected that the pressure value of the gas at the rear end of the EGR valve in the current cycle is greater than or equal to a preset pressure value, while the pressure value of the gas at the rear end of the EGR valve is detected in the current cycle, the temperature of the EGR valve end is monitored for a preset time in the current cycle.

[0068] When the pressure value of the gas at the rear end of the EGR valve is detected within the first detection window time in the current cycle, if it is detected that the pressure value of the gas at the rear end of the EGR valve in the current cycle is less than the preset pressure value, the pressure value of the gas at the rear end of the EGR valve is detected within the interval detection interval time t wd After that, when it is determined that the vehicle is in the preset state, the pressure value of the gas at the rear end of the EGR valve is detected within the second detection window time. When all the detection results before the nth detection window time are that the pressure value of the gas at the rear end of the EGR valve is less than the preset pressure value, the pressure value of the gas at the rear end of the EGR valve is detected within the nth detection window time. When the detection result within the nth detection window time is that the pressure value of the gas at the rear end of the EGR valve is less than the preset pressure value, the periodic detection of the pressure value of the gas at the rear end of the EGR valve of this wheel is terminated.

[0069] The relationship between the temperature increment of the EGR valve end temperature within the preset time length and the preset increment in the current cycle includes: the temperature increment of the EGR valve end within the preset time length exceeds the preset increment; the temperature increment of the EGR valve end within the preset time length does not exceed the preset increment.

[0070] Step S14: When it is detected that the pressure value of the gas at the rear end of the EGR valve is continuously greater than or equal to the preset pressure value in the current cycle, and the temperature increment of the EGR valve end within the preset time period exceeds the preset increment, an alarm message of excessive exhaust gas flow is output.

[0071] In this embodiment, when it is detected that the pressure value of the gas at the rear end of the EGR valve in the current cycle is greater than or equal to the preset pressure value and lasts for more than the set time, and when the temperature increase at the EGR valve end within the preset time in the current cycle exceeds the preset increase, an alarm message that the exhaust gas flow rate of the EGR valve exceeds the standard is output, and this round of periodic detection is ended.

[0072] In this embodiment, when it is detected that the pressure value of the gas at the rear end of the EGR valve in the current cycle is less than the preset pressure value, or the pressure value of the gas at the rear end of the EGR valve in the current cycle is greater than or equal to the preset pressure value, but the duration does not exceed the set duration, and the vehicle is in a preset state, the pressure value of the gas at the rear end of the EGR valve is detected in the next cycle of the current cycle.

[0073] In this embodiment, when it is detected that the pressure value of the gas at the rear end of the EGR valve in the current cycle is greater than or equal to the preset pressure value and lasts for more than the set time, but the temperature increase at the EGR valve end within the preset time in the current cycle does not exceed the preset increase, and the vehicle is in a preset state, the pressure value of the gas at the rear end of the EGR valve is detected in the next cycle of the current cycle.

[0074] The method described in the present invention diagnoses EGR faults through a composite judgment method based on the pressure value of the gas at the rear end of the EGR valve and the temperature at the EGR valve end. Compared with the existing solution of diagnosing EGR high-flow faults based only on the temperature before the EGR valve, the method described in the present invention has higher accuracy and meets more stringent regulatory requirements.

[0075] The method described in the present invention continuously detects for a period of time when measuring the pressure value of the gas at the rear end of the EGR valve and the temperature at the EGR valve end. It is determined that the exhaust gas flow of the EGR valve exceeds the standard only when the judgment conditions are continuously met during the continuous detection process, which effectively reduces the possibility of false alarms and missed alarms.

[0076] The method described in the present invention does not require additional sensor configuration and is only based on the laws of physical properties, effectively saving hardware development and supporting costs.

[0077] In the present application, the method also includes: determining a preset pressure value corresponding to the operating condition of the vehicle in the current cycle, wherein different operating conditions correspond to different preset pressure values; when it is detected that the pressure value of the gas at the rear end of the EGR valve in the current cycle is continuously greater than or equal to the preset pressure value, and the temperature increment of the EGR valve end within the preset time period exceeds the preset increment, outputting an alarm message of excessive exhaust gas flow, including: when the pressure value of the gas at the rear end of the EGR valve in the current cycle is greater than or equal to the preset pressure value and continues for a first preset time, and the temperature increment of the EGR valve end within the preset time period exceeds the preset increment, outputting an alarm message of excessive exhaust gas flow.

[0078] In this embodiment, the vehicle needs to travel in different environments, and different environments will affect the detection of the gas pressure at the rear end of the EGR valve. In a high-altitude environment, the ambient air pressure is lower than a standard atmospheric pressure; in a low-altitude environment, the ambient air pressure is higher than a standard atmospheric pressure. Due to the different ambient pressures in different environments, the pressure of the gas at the rear end of the EGR valve detected in different environments will be different. The pressure of the gas at the rear end of the EGR valve detected in a high-altitude environment is lower than the pressure of the gas at the rear end of the EGR valve detected in a conventional environment, and the pressure of the gas at the rear end of the EGR valve detected in a low-altitude environment is higher than the pressure of the gas at the rear end of the EGR valve detected in a conventional environment. Therefore, setting a fixed preset pressure value in different environments to judge whether the flow of the exhaust gas at the rear end of the EGR valve exceeds the standard will reduce the accuracy, and taking different values ​​for the preset pressure value according to different environments, thereby avoiding the influence of environmental errors on the pressure value of the gas at the rear end of the EGR valve, and effectively improving the accuracy of using the preset pressure value in different environments as a judgment condition for judging whether the flow of the exhaust gas at the rear end of the EGR valve exceeds the standard. Based on this, different preset pressure values ​​are set according to different working conditions of the vehicle in the current cycle. When the ambient pressure is high, the preset pressure value is increased, and when the ambient pressure is low, the preset pressure value is decreased. The working condition at least includes the ambient pressure.

[0079] In this embodiment, another optional implementation of detecting that the pressure value of the gas at the rear end of the EGR valve in the current cycle is greater than or equal to the preset pressure value and lasts for the first preset time is to detect that the difference between the pressure value of the gas at the rear end of the EGR valve in the current cycle and the expected pressure value is greater than or equal to the pressure difference threshold and lasts for the first preset time. The expected pressure value takes different values ​​according to different environments, and the sum of the expected pressure value and the pressure difference threshold is the preset pressure value.

[0080] In this embodiment, the specific value of the preset pressure value determined based on the working condition of the vehicle in the current cycle is set according to the actual application scenario and is not specifically limited here.

[0081] In this embodiment, after determining the preset pressure value corresponding to the working condition of the vehicle in the current cycle, the relationship between the pressure value of the gas at the rear end of the EGR valve in the current cycle and the preset pressure value is detected. When it is detected that the pressure value of the gas at the rear end of the EGR valve in the current cycle is greater than or equal to the preset pressure value, the monitoring of the temperature of the EGR valve end is started, and while the pressure value of the gas at the rear end of the EGR valve is detected in the current cycle, the temperature of the EGR valve end is monitored for a preset period of time in the current cycle.

[0082] When it is detected that the pressure value of the gas at the rear end of the EGR valve in the current cycle is greater than or equal to the preset pressure value corresponding to the operating conditions in the current cycle and lasts for a first preset time, and when it is detected that the temperature increment at the EGR valve end exceeds the preset increment within the preset time, an alarm message of excessive exhaust gas flow is output.

[0083] Preferably, in the present invention, the first preset time is set according to actual needs and is not specifically limited here.

[0084] In this embodiment, the first preset time is the duration for which the pressure value of the gas at the rear end of the EGR valve continues to exceed the preset pressure value, and the preset time is the duration for which the temperature of the EGR valve end is monitored. Since the temperature monitoring of the EGR valve end is started immediately when the pressure value of the gas at the rear end of the EGR valve exceeds the preset pressure value. Therefore, the starting time of the first preset time and the starting time of the preset time length within the same detection window time are the same, and the lengths of the first preset time and the preset time length are less than or equal to one detection window time. The end time of the first preset time and the end time of the preset time length are set according to the actual application scenario, and can be the same or different, and are not specifically limited here.

[0085] In the present application, based on the relationship between the pressure value of the gas at the rear end of the EGR valve in the current cycle and the preset pressure value, the temperature of the EGR valve end is monitored for a preset time in the current cycle, including: when it is determined that the pressure value of the gas at the rear end of the EGR valve in the current cycle is greater than or equal to the preset pressure value, the temperature of the EGR valve end is monitored for a preset time in the current cycle.

[0086] In this embodiment, when it is determined that the pressure value of the gas at the rear end of the EGR valve in the current cycle is greater than or equal to the preset pressure value, the pressure value of the gas at the rear end of the EGR valve in the current cycle is detected, and the temperature of the EGR valve end is monitored for a preset time in the current cycle.

[0087] When it is determined that the pressure value of the gas at the rear end of the EGR valve in the current cycle is less than the preset pressure value and the vehicle is in a preset state, the pressure value of the gas at the rear end of the EGR valve is detected in the next cycle of the current cycle.

[0088] In the present application, the temperature increment is an increment between a first temperature and a second temperature, the first temperature being the temperature of the EGR valve end at the start time within a preset time length, and the second temperature being the temperature of the EGR valve end at the end time within the preset time length.

[0089] In this embodiment, the relationship between the temperature increment of the EGR valve end temperature within the preset time and the preset increment in the current cycle is determined, specifically: in the process of monitoring the temperature of the EGR valve end for the preset time in the current cycle, the first temperature of the EGR valve end measured at the start time of the preset time is determined, and the second temperature of the EGR valve end measured at the end time of the preset time is determined. The second temperature is subtracted from the first temperature to obtain the temperature increment of the EGR valve end within the preset time, and it is determined whether the temperature increment exceeds the preset increment.

[0090] Preferably, in the present invention, the second temperature must be greater than the first temperature, the first temperature is set to a temperature less than the second temperature according to actual needs, the second temperature and the preset increment are set according to actual needs, and are not specifically limited here.

[0091] In the present application, the pressure value of the gas at the rear end of the EGR valve includes at least one of the pressure value of the exhaust gas near the EGR valve and the pressure value of the manifold gas at the intake manifold, wherein the manifold gas at the intake manifold is air or a mixture of air and the exhaust gas.

[0092] In this embodiment, when the exhaust gas generated by the diesel engine or gasoline engine enters the cylinder through the EGR valve for combustion, the exhaust gas needs to pass through the intake manifold, where the exhaust gas and the combustible mixture enter the cylinder for combustion. After the exhaust gas passes through the EGR valve, it needs to pass through a section of pipeline before entering the intake manifold. In order to further avoid the influence of the condenser set near the EGR valve on the entire detection process, resulting in false alarms of fault detection. The periodic detection of the pressure value of the gas at the rear end of the EGR valve is to periodically detect the pressure value of the exhaust gas near the EGR valve and the pressure value of the manifold gas at the intake manifold at the same time. As long as the pressure value of one of them meets the set judgment condition, it is determined that the set judgment condition is met.

[0093] Among them, the set judgment conditions are various judgment conditions corresponding to the pressure value of the gas at the rear end of the EGR valve, which will not be repeated here. For example, whether the pressure value of the gas at the rear end of the EGR valve is greater than or equal to the preset pressure value and whether it lasts for a first preset time, the corresponding judgment conditions are whether the pressure value of the exhaust gas near the EGR valve is greater than or equal to the preset pressure value and whether it lasts for the first preset time, and / or whether the pressure value of the manifold gas at the intake manifold is greater than or equal to the preset pressure value and whether it lasts for the first preset time.

[0094] In the present application, when it is detected that the pressure value of the gas at the rear end of the EGR valve in the current cycle is continuously greater than or equal to the preset pressure value, and the temperature increment of the temperature at the EGR valve end within the preset time period exceeds the preset increment, an alarm message of excessive exhaust gas flow is output, including: when it is detected that the pressure value of the exhaust gas near the EGR valve in the current cycle is greater than or equal to the preset pressure value of the exhaust gas and continues for a second preset time, and when it is detected that the pressure value of the manifold gas at the intake manifold in the current cycle is greater than or equal to the preset pressure value of the manifold gas and continues for a third preset time, at least one of the above is true, and the temperature increment of the temperature at the EGR valve end within the preset time period exceeds the preset increment, an alarm message of excessive exhaust gas flow is output.

[0095] In this embodiment, the preset pressure value of the exhaust gas and the preset pressure value of the manifold gas can be determined according to the working condition of the vehicle in the current cycle. After determining the preset pressure value of the exhaust gas and the preset pressure value of the manifold gas corresponding to the working condition of the vehicle in the current cycle, the fault diagnosis is performed.

[0096] In this embodiment, at least one of the following is true when it is detected that the pressure value of the exhaust gas near the EGR valve in the current cycle is greater than or equal to the preset pressure value of the exhaust gas and lasts for a second preset time, and when it is detected that the pressure value of the manifold gas at the intake manifold in the current cycle is greater than or equal to the preset pressure value of the manifold gas and lasts for a third preset time; at the same time, in the process of monitoring the temperature of the EGR valve end for a preset time in the current cycle, when it is detected that the temperature increment between the first temperature of the EGR valve end measured at the starting time of the preset time and the second temperature of the EGR valve end measured at the ending time of the preset time exceeds the preset increment, an alarm message of exhaust gas flow exceeding the standard is output, and this round of periodic detection is ended.

[0097] Preferably, in the present invention, the preset pressure value, the preset pressure value of the exhaust gas and the preset pressure value of the manifold gas can be set according to actual needs, and the three can be the same or different from each other, and no specific limitation is made here; the first preset time, the second preset time and the third preset time can be set according to actual needs, and the three can be the same or different from each other, and no specific limitation is made here.

[0098] Figure 4 FIG. 1 is a logic diagram of a pressure difference detection method of an EGR fault diagnosis method shown in an embodiment of the present application. Figure 4 Before each test in a complete periodic test process, it is necessary to determine whether the vehicle is in a preset state. When it is determined that the vehicle is in the preset state, the test of the current cycle is performed. During the test of the current cycle, the pressure value DP of the exhaust gas near the EGR valve is determined. EGRA The preset pressure value DP of the exhaust gas uplimEGRand determine the manifold gas pressure DP at the intake manifold S The preset pressure value DP of the manifold gas uplimS In determining the relationship between DP EGRA ≥DP uplimEGR and DP S ≥DP uplimS When at least one of the following conditions is met, a timer for judging whether the pressure difference exceeds the limit is activated.

[0099] In D PEGRA ≥DP uplimEGR When the value is established, the counter t is activated to judge the pressure difference after the EGR valve exceeds the limit. DPR0 ; In DP S ≥DP uplimS When the value is established, the counter t for judging the pressure difference at the intake manifold to exceed the limit is activated. DPS0 ; After determining D PEGRA ≥DP uplimEGR and DP S ≥DP uplimS When both are true, timer t is activated at the same time DPR0 and timer t DPS0 .

[0100] The duration of the pressure difference is determined by the activated counters near the EGR valve and the intake manifold. PEGRA ≥DP uplimEGR When the counter t is activated DPR0 , through the counter t DPR0 Determine D PEGRA ≥DP uplimEGR Duration t DPR0 and the second preset time t DPRlim0 In determining DP S ≥DP uplimS When the counter t is activated DPS0 , through the counter t DPS0 Determine DP S ≥DP uplimS Duration t DPS0 and the second preset time t DPSlim0 relationship.

[0101] In t DPR0 ≥t DPRlim0 and t DPS0 ≥t DPSlim0 When at least one of the following is true, it is determined that the pressure difference of the gas at the rear end of the EGR valve exceeds the limit. DPR0 ≥t DPRlim0 and t DPS0 ≥t DPSlim0When none of the above conditions hold, a time reversal is performed, and when it is determined that the vehicle is in a preset state, the pressure value of the gas at the rear end of the EGR valve is detected in the next cycle of the current cycle.

[0102] In the present application, the method further includes: when the temperature at the EGR valve end exceeds a preset temperature, outputting an alarm message indicating that the exhaust gas flow exceeds a standard.

[0103] In this embodiment, an upper limit protection temperature, ie, a preset temperature, is set for the temperature of the EGR valve end. When the temperature of the EGR valve end exceeds the preset temperature, an alarm message indicating that the exhaust gas flow exceeds the limit is directly output.

[0104] Figure 5 FIG. 1 is a logic diagram of temperature increment of a method for diagnosing EGR faults according to an embodiment of the present application. Figure 5 When it is determined that the vehicle is in a preset state, the pressure value of the gas at the rear end of the EGR valve is detected in the current cycle. When it is determined that the pressure value of the gas at the rear end of the EGR valve in the current cycle is greater than or equal to the preset pressure value, the timer for judging the pressure difference exceeding the limit is activated, and the pressure value of the gas at the rear end of the EGR valve in the current cycle is detected. At the same time, the temperature of the EGR valve end is monitored for a preset time in the current cycle.

[0105] During the monitoring process of the temperature of the EGR valve end for a preset time period in the current cycle, the measured EGR valve end temperature is recorded and the measured EGR valve end temperature is timed and stored. The first temperature T of the EGR valve end measured at the starting time t0 within the preset time period is detected. egr0 , and the second temperature T of the EGR valve end measured at the end time t1 within the preset time egr1 The temperature increment DT egr ≥Preset increment DT egrlim When the temperature increment of the EGR valve end temperature exceeds the limit, it is determined that the temperature T of the EGR valve end is exceeded. egr ≥Preset temperature T Protectlim , directly output the alarm information of exhaust gas flow exceeding the standard.

[0106] In DT egr <DT egrlim When the temperature increment of the EGR valve end temperature is determined to be within the limit, a time rebound is performed, and when it is determined that the vehicle is in a preset state, the pressure value of the gas at the rear end of the EGR valve is detected in the next cycle of the current cycle. When it is determined that the pressure value of the gas at the rear end of the EGR valve in the next cycle of the current cycle is greater than or equal to the preset pressure value, the timer for judging the pressure difference exceeding the limit is activated, and the pressure value of the gas at the rear end of the EGR valve in the next cycle of the current cycle is detected, and at the same time, the temperature of the EGR valve end is monitored for a preset time in the next cycle of the current cycle.

[0107] In summary, the EGR fault diagnosis method described in the embodiment of the present invention has at least the following advantages:

[0108] The EGR fault diagnosis method described in the present invention is a composite judgment method based on two pressure values ​​of the gas at the rear end of the EGR valve and the EGR valve end temperature, which effectively improves the accuracy of EGR fault diagnosis, eliminates the possibility of false alarms and missed alarms as much as possible, and meets more stringent regulatory requirements.

[0109] At the same time, the EGR fault diagnosis method described in the present invention does not require the addition of additional sensors, but only diagnoses the EGR fault based on the laws of physical characteristics, saving hardware development and supporting costs.

[0110] An embodiment of the present invention also provides a system for EGR fault diagnosis. Figure 6 Schematic diagram of an EGR fault diagnosis system shown in an embodiment of the present application. Figure 6 The EGR fault diagnosis system 600 provided in the present application includes:

[0111] The detection module 601 is used to periodically detect the pressure value of the gas at the rear end of the EGR valve.

[0112] The first determination module 602 is used to determine the relationship between the pressure value of the gas at the rear end of the EGR valve and a preset pressure value in the current cycle.

[0113] The second determination module 603 is used to monitor the temperature of the EGR valve end for a preset time period in the current cycle based on the relationship between the pressure value of the gas at the rear end of the EGR valve in the current cycle and the preset pressure value, and determine the relationship between the temperature increment of the temperature of the EGR valve end in the current cycle within the preset time period and the preset increment.

[0114] The alarm module 604 is used to output an alarm message of excessive exhaust gas flow when it detects that the pressure value of the gas at the rear end of the EGR valve is continuously greater than or equal to the preset pressure value in the current cycle, and the temperature increment of the EGR valve end within the preset time period exceeds the preset increment.

[0115] An embodiment of the present invention further provides a vehicle, which may specifically include: the above-mentioned EGR fault diagnosis system.

[0116] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for EGR fault diagnosis, characterized in that: The method comprises: Periodically test the pressure value of the gas at the rear end of the EGR valve; Determine the relationship between the pressure value of the gas at the rear end of the EGR valve and the preset pressure value in the current cycle; When it is determined that the pressure value of the gas at the rear end of the EGR valve in the current cycle is greater than or equal to the preset pressure value, the temperature of the EGR valve end is monitored for a preset time in the current cycle, and the relationship between the temperature increment of the temperature of the EGR valve end in the preset time and the preset increment in the current cycle is determined; When it is detected that the pressure value of the gas at the rear end of the EGR valve is continuously greater than or equal to the preset pressure value in the current cycle, and the temperature increment of the temperature at the EGR valve end within the preset time period exceeds the preset increment, an alarm message of the exhaust gas flow exceeding the standard is output; Wherein, the pressure value of the gas at the rear end of the EGR valve includes at least one of the pressure value of the exhaust gas near the rear end of the EGR valve and the pressure value of the manifold gas at the intake manifold, and the manifold gas at the intake manifold is air or a mixed gas of air and the exhaust gas; the temperature increment is an increment between a first temperature and a second temperature, the first temperature is the temperature of the EGR valve end at the start time within a preset time length, and the second temperature is the temperature of the EGR valve end at the end time within the preset time length; Wherein, the method further comprises: Determine a preset pressure value corresponding to the working condition of the vehicle in the current cycle, wherein different working conditions correspond to different preset pressure values; When it is detected that the pressure value of the gas at the rear end of the EGR valve in the current cycle is continuously greater than or equal to the preset pressure value, and the temperature increment of the EGR valve end in the preset time exceeds the preset increment, an alarm message of excessive exhaust gas flow is output, including: when the pressure value of the gas at the rear end of the EGR valve in the current cycle is greater than or equal to the preset pressure value and continues for a first preset time, and the temperature increment of the EGR valve end in the preset time exceeds the preset increment, an alarm message of excessive exhaust gas flow is output.

2. The method according to claim 1, characterized in that When it is detected that the pressure value of the gas at the rear end of the EGR valve is continuously greater than or equal to the preset pressure value in the current cycle, and the temperature increment of the temperature at the EGR valve end within the preset time period exceeds the preset increment, outputting the alarm information of the exhaust gas flow exceeding the standard includes: When at least one of the following is true: when it is detected that the pressure value of the exhaust gas near the EGR valve in the current cycle is greater than or equal to the preset pressure value of the exhaust gas and lasts for a second preset time, and when it is detected that the pressure value of the manifold gas at the intake manifold in the current cycle is greater than or equal to the preset pressure value of the manifold gas and lasts for a third preset time, and when the temperature increment at the EGR valve end exceeds the preset increment within the preset time, an alarm message of excessive exhaust gas flow is output.

3. The method according to claim 1, characterized in that The periodic detection of the pressure value of the gas at the rear end of the EGR valve includes: Obtain detection parameters of the periodic detection, including: detection window time, detection interval time, and continuous detection frequency; Based on the detection parameters, the pressure value of the gas at the rear end of the EGR valve is periodically detected.

4. The method according to claim 1, characterized in that: The method further comprises: When the temperature at the EGR valve end exceeds a preset temperature, an alarm message indicating that the exhaust gas flow exceeds a standard is output.

5. A system for EGR fault diagnosis, characterized in that: The system comprises: A detection module, used for periodically detecting the pressure value of the gas at the rear end of the EGR valve; A first determination module, used to determine the relationship between the pressure value of the gas at the rear end of the EGR valve and a preset pressure value in a current cycle; A second determination module is used to monitor the temperature of the EGR valve end for a preset time in the current cycle when it is determined that the pressure value of the gas at the rear end of the EGR valve in the current cycle is greater than or equal to the preset pressure value, and determine the relationship between the temperature increment of the temperature of the EGR valve end in the preset time and the preset increment in the current cycle; An alarm module is used to output an alarm message of an exhaust gas flow exceeding a standard when it is detected that the pressure value of the gas at the rear end of the EGR valve is continuously greater than or equal to a preset pressure value in the current cycle, and the temperature increment of the temperature at the EGR valve end within the preset time period exceeds a preset increment; Wherein, the pressure value of the gas at the rear end of the EGR valve includes at least one of the pressure value of the exhaust gas near the rear end of the EGR valve and the pressure value of the manifold gas at the intake manifold, and the manifold gas at the intake manifold is air or a mixed gas of air and the exhaust gas; the temperature increment is an increment between a first temperature and a second temperature, the first temperature is the temperature of the EGR valve end at the start time within a preset time length, and the second temperature is the temperature of the EGR valve end at the end time within the preset time length; Wherein, the system further comprises: A module for determining a preset pressure value corresponding to an operating condition of the vehicle in a current cycle, wherein different operating conditions correspond to different preset pressure values; The alarm module is also used to output an alarm message of excessive exhaust gas flow when the pressure value of the gas at the rear end of the EGR valve is greater than or equal to the preset pressure value and lasts for a first preset time during the current cycle, and the temperature increment of the EGR valve end within the preset time exceeds a preset increment.

6. A vehicle, characterized in that: The vehicle comprises a system for EGR fault diagnosis as claimed in claim 5, which is used to execute the steps in the method for EGR fault diagnosis as claimed in any one of claims 1-4.

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