Thermal management system fault diagnosis method based on UDS protocol

Abstract

The invention relates to a thermal management system fault diagnosis method based on a UDS protocol, and belongs to the technical field of automobile electronic control. The method comprises the following steps: establishing communication connection with an ECU of a thermal management system through an OBD interface of a vehicle, initializing a UDS protocol data transmission channel, requesting fault information from the ECU of the thermal management system through a UDS protocol, obtaining fault codes, abnormal information and real-time data in the system, and monitoring key parameters of the thermal management system in real time. The method comprises the steps of reading fault information and monitoring data of a thermal management system, judging whether the working state of the system is normal or not according to the monitoring data, performing fault mode recognition on the running state of the thermal management system by adopting a data analysis method according to the read fault information and the monitoring data, repairing a diagnosed fault, sending a fault clearing instruction to the thermal management system through a UDS protocol, and resetting the state of the system. The method has the advantages of improving the diagnosis accuracy, improving the diagnosis efficiency and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of automobile electronic control and relates to a thermal management system fault diagnosis method based on a Unified Diagnostic Services (UDS) protocol. Background Art

[0002] With the continuous development of automotive electronic technology, modern cars are integrated with a variety of complex thermal management systems to regulate the temperature of vehicle engines, gearboxes, power batteries and other components to ensure that they work within the optimal temperature range, extend service life and improve work efficiency. Traditional thermal management systems work together through various sensors, actuators and control units to maintain the temperature balance of the system.

[0003] However, as automotive thermal management systems become more complex, fault diagnosis becomes increasingly difficult. Traditional diagnostic methods usually rely on manual inspection or regular maintenance, which makes it difficult to detect faults in a timely manner, resulting in low diagnostic efficiency and the risk of missed diagnosis. In recent years, diagnostic methods based on the UDS protocol have been widely used in automotive fault diagnosis. They can communicate with the Electronic Control Unit (ECU) through the vehicle's On-Board Diagnostics (OBD) interface to provide fast and accurate fault detection and diagnostic results.

[0004] However, the existing fault diagnosis methods based on the UDS protocol mostly focus on components such as engines and gearboxes, and there is still a lack of special solutions for the diagnosis and maintenance of thermal management systems. Therefore, it is of great practical significance to develop a diagnostic method based on the UDS protocol that can efficiently and accurately diagnose thermal management system faults. Summary of the invention

[0005] In view of this, the purpose of the present invention is to provide a thermal management system fault diagnosis method based on the UDS protocol. It can communicate with the ECU of the thermal management system through the on-board diagnostic interface to achieve fast and accurate fault diagnosis. The method can monitor various working parameters of the thermal management system in real time, identify abnormal conditions and generate diagnostic reports, thereby improving the accuracy and efficiency of fault diagnosis.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A thermal management system fault diagnosis method based on UDS protocol includes the following steps:

[0008] a. Establish a communication connection with the thermal management system ECU through the vehicle's OBD interface and initialize the UDS protocol data transmission channel;

[0009] b. Request fault information from the ECU of the thermal management system through the UDS protocol to obtain fault codes, abnormal information and real-time data in the system;

[0010] c. Monitor the key parameters of the thermal management system in real time and determine whether the system is working normally based on the monitoring data;

[0011] d. Based on the fault information and monitoring data read, use data analysis methods to identify the fault mode of the operating status of the thermal management system, and identify whether the relevant parameters of components such as the compressor, condenser, expansion valve and evaporator are within the safe range. If not, respond to the fault analysis based on the current data values ​​and take action;

[0012] e. For the diagnosed fault, after repair, send a fault clearing instruction to the thermal management system through the UDS protocol and reset the system status;

[0013] f. After the diagnosis is completed, the system will feedback the diagnosis results and related data to the user or maintenance personnel and provide corresponding maintenance suggestions.

[0014] Furthermore, in b, the fault information includes fault code, abnormal information and real-time data, wherein the fault code is composed of a string of 4-bit characters YJKL, where Y is the fault level, i.e. A, B, and C; J, K, and L are hexadecimal numbers, J is a bit to be used, usually represented as 0; K is the component number; and L is the fault content number.

[0015] Furthermore, in said c, the key parameters include compressor inlet pressure, outlet pressure, inlet temperature, outlet temperature, inlet refrigerant mass flow rate, outlet refrigerant mass flow rate, compressor speed, condenser inlet pressure, outlet pressure, inlet temperature, outlet temperature, inlet air temperature, outlet air temperature, radiator gear position, expansion valve inlet pressure, outlet pressure, inlet temperature, outlet temperature, inlet refrigerant mass flow rate, outlet refrigerant mass flow rate, expansion valve opening, evaporator inlet pressure, inlet temperature, inlet temperature, inlet air temperature, outlet air temperature and blower gear position.

[0016] Furthermore, in said d, the response action includes sending a fault code, performing a fault protection action, sending a fault clearing instruction and resetting the system status.

[0017] Furthermore, in said step d, the fault protection actions include reducing the compressor speed, closing the radiator gear, closing the blower gear and reducing the expansion valve opening.

[0018] Furthermore, in said e, the fault clearing instruction is implemented through the "clear fault code" service in the UDS protocol.

[0019] Furthermore, in said f, the diagnosis results and related data are displayed through the vehicle-mounted display screen or the remote diagnosis platform.

[0020] Furthermore, the thermal management system includes internal combustion engine vehicles, electric vehicles and hybrid vehicles.

[0021] The beneficial effects of the present invention are:

[0022] (1) Improve diagnostic accuracy

[0023] The present invention can collect multiple parameters of the thermal management system in real time, proposes a fault code encoding method, accurately provides fault information to the host computer, performs detailed data analysis through the UDS protocol, effectively identifies system faults and abnormal conditions, and avoids misdiagnosis and missed diagnosis problems in traditional methods.

[0024] (2) Improve diagnostic efficiency

[0025] A fault level classification method for thermal management systems is proposed, which divides the fault conditions into three levels: A, B, and C according to their severity levels; through an automated online fault detection process, fault problems can be detected immediately and corresponding measures can be taken, saving the cost of manual inspection and improving the efficiency of troubleshooting.

[0026] (3) Enhance system reliability

[0027] The method can promptly alarm when a thermal management system fails, and provide detailed fault information and maintenance suggestions, thereby reducing the risk after a failure occurs and enhancing the reliability and safety of the system.

[0028] (4) Wide applicability

[0029] The present invention is applicable to various vehicle thermal management systems based on the UDS protocol, including but not limited to internal combustion engine vehicles, electric vehicles, hybrid vehicles, etc.

[0030] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below in conjunction with the accompanying drawings, wherein:

[0032] Figure 1 Connect the socket pin interface for OBD fault diagnosis;

[0033] Figure 2 This is the flow chart of the fault diagnosis principle;

[0034] Figure 3 This is the fault signal level diagram. DETAILED DESCRIPTION

[0035] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0036] Among them, the drawings are only used for illustrative explanations, and they only represent schematic diagrams rather than actual pictures, and should not be understood as limitations on the present invention. In order to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of actual products. For those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0037] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right", "front", "rear", etc. indicate the orientation or position relationship, they are based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0038] The present invention provides a thermal management system fault diagnosis method based on the UDS protocol, which mainly includes the following steps:

[0039] 1. Data collection and communication establishment

[0040] Establish a communication connection with the thermal management system ECU through the vehicle's OBD interface and initialize the UDS protocol data transmission channel. This step includes sending a diagnostic session request, establishing a communication session, etc., to ensure the security and reliability of data transmission. The OBD-II system uses a standard diagnostic interface, often called DLC (Data Link Connector), which is generally installed below the dashboard on the driver's side. According to ISO15031-3 and SAE1962 protocols, its connection socket has 16 pins such as Figure 1As shown, each pin has different functions and protocols. The pin definition of the OBD-II diagnostic interface is shown in Table 1. When an external device is connected to the OBD-II interface, it is actually connected to a specific pin.

[0041] Table 1

[0042] Pins Allocation Definition Pins Allocation Definition 1 Customized by car manufacturers 9 Customized by car manufacturers 2 SAE J1850 bus positive 10 SAE J1850 bus negative 3 Customized by car manufacturers 11 Customized by car manufacturers 4 Chassis 12 Customized by car manufacturers 5 signal ground 13 Car manufacturer customization 6 CAN_H defined in ISO15765-4 14 CAN_L defined in ISO15765-4 7 K-line defined by ISO9141-2 and ISO14230-4 15 L line defined by ISO9141-2 and ISO14230-4 8 Car manufacturer customization 16 Vehicle battery power supply

[0043] 2. Read fault information

[0044] Request fault information from the thermal management system ECU through the UDS protocol. This step obtains fault codes, abnormal information and real-time data in the system by sending a diagnostic service request.

[0045] Fault level classification:

[0046] Class C fault: initial fault confirmation, fault protection action is initiated;

[0047] Class B fault: After the fault protection action is performed until it is impossible to continue the action, the fault still exists and the system stops running;

[0048] Class A failure: Hardware failure, the system will be shut down for repair;

[0049] Fault code: It is composed of a string of 4 characters YJKL, for example: C001, which means that the C-level fault occurs in the No. 0 component, and the fault content is No. 1 fault;

[0050] The Y position is the fault level, i.e. A\B\C level;

[0051] J, K, and L are hexadecimal numbers;

[0052] The J bit is a bit to be used, usually represented as 0;

[0053] The K position is the part number;

[0054] L is the fault content number.

[0055] 3. Thermal management system parameter monitoring

[0056] The key parameters of the thermal management system are monitored in real time, and the monitoring data are shown in Table 2. These key parameters are read through the diagnostic service to analyze the current working status of the system. The monitoring parameters include but are not limited to the pressure, temperature, flow, speed, gear position, etc. of the compressor, condenser, expansion valve, evaporator and other components.

[0057] Table 2

[0058]

[0059] The unit of pressure P is Pa, the unit of temperature T is ℃, the unit of mass flow rate is g / s, the unit of compressor speed is rpm, the unit of expansion valve opening is %, and the radiator gear and blower gear are divided into 0\1\2\3\...\n gears.

[0060] 4. Failure mode analysis

[0061] According to the fault information and monitoring data read, the data analysis method is used to identify the fault mode of the operation status of the thermal management system. Identify whether the relevant parameters of components such as the compressor, condenser, expansion valve and evaporator are within the safe range. If not, respond according to the fault analysis of the current data value. If the controllable parameters (compressor speed N, radiator gear P1, expansion valve opening X, blower gear P2) do not respond after receiving the command, or the data cannot be read, it is defined as a hardware failure, that is, a Class A failure.

[0062] Assume that the current monitoring data is x, and its specified working range is y=(y min ,y max );

[0063] like There is no fault at present;

[0064] like It is defined as a failure, according to x <y min or x>y max , search the corresponding fault event table and find the corresponding fault number L, where L is a hexadecimal number;

[0065] Send a fault code based on the component to which x belongs and the fault level.

[0066] If the controllable parameters (compressor speed N, radiator gear P1, expansion valve opening X, blower gear P2) do not respond after receiving the command, or cannot read the data, it is defined as a hardware failure, that is, a Class A failure;

[0067] According to the fault protection action corresponding to the fault code, send the corresponding instruction to the target control object;

[0068] Continue to monitor the current data until the data returns to normal and the fault code is cleared;

[0069] 5. Fault Clearance and System Reset

[0070] For the diagnosed fault, after repair, the fault clearing command is sent to the thermal management system through the UDS protocol, and the system status is reset. This step is implemented through the "clear fault code" service in the UDS protocol to ensure that the system returns to normal working status.

[0071] 6. Feedback on diagnosis results and maintenance suggestions

[0072] After the diagnosis is completed, the system will feedback the diagnosis results and related data to the user or maintenance personnel, and provide corresponding maintenance suggestions. This step displays the results through the vehicle display or remote diagnosis platform to facilitate further processing by the staff.

[0073] The specific diagnostic steps flow chart is as follows Figure 2 shown.

[0074] S1: ECU reads data;

[0075] S2: Determine whether the data is abnormal. If it is abnormal, go to S3; if it is not abnormal, go to S8;

[0076] S3: Perform fault analysis and send fault code;

[0077] S4: Determine whether it is a Class A or Class B fault; if so, stop running; if not, enter S5;

[0078] S5: Perform fault protection action;

[0079] S6: Determine whether the data is abnormal. If it is abnormal, return to S3; if it is not abnormal, enter S7;

[0080] S7: Clear fault code;

[0081] S8: End.

[0082] Example: Compressor outlet overpressure diagnosis

[0083] Connect the diagnostic tool to the OBD port of the electric vehicle and start the vehicle diagnostic mode.

[0084] Establish communication with the thermal management system ECU of the electric vehicle through the UDS protocol.

[0085] Send a diagnostic request to the ECU to obtain data from various sensors in the thermal management system.

[0086] The system analyzes the acquired sensor data and detects the abnormal compressor outlet pressure at the 1ms. The current data is P1=53Pa, N=3200rpm. It is found that the compressor outlet pressure P1 is greater than the safety value of 50Pa. The fault trigger is pulled up from low level 0 to high level 1. Figure 3 As shown, after 10 operation cycles, that is, at 201ms, the fault trigger still maintains a high level 1, that is, the fault is confirmed, and the fault confirmation is pulled up from a low level 0 to a high level 1;

[0087] The fault code C011 is sent, which means a Class C fault, which occurs in component No. 1 compressor, and the fault event is event No. 1: the compressor outlet pressure is greater than the safety range.

[0088] After 1ms, the fault protection action is started, and the compressor speed is reduced by 5rpm every 1000ms. After 3000ms, P1=49Pa, N=3185rpm, and the compressor outlet pressure is detected to be back to the safe range, and the fault trigger changes from high level 1 to low level 0; after 10 operation cycles, that is, at 3401ms, the fault trigger is not pulled up again, confirming that the fault is repaired, and the fault confirmation changes from high level 1 to low level 0;

[0089] The fault code is cleared and the fault protection action stops after 1ms;

[0090] The steps for diagnosing compressor overpressure faults are shown in Table 3.

[0091] Table 3 Compressor overpressure fault diagnosis steps

[0092] Diagnostic Process Conditions and Actions Fault diagnosis on ECU on Fault detection cycle 20ms Fault trigger <![CDATA[P1>50Pa]]> Detection duration 10 Fault confirmation Lasts for 10 times Send fault code C011 Fault protection action Reduce compressor speed Failure recovery is enabled <![CDATA[P1<50Pa]]> Detection duration 10 Clear fault codes Clear fault codes Failure recovery actions Exit compressor speed reduction mode

[0093] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. A thermal management system fault diagnosis method based on UDS protocol, characterized in that: The following steps are involved: a. Establish a communication connection with the thermal management system ECU through the vehicle's OBD interface and initialize the UDS protocol data transmission channel; b. Request fault information from the ECU of the thermal management system through the UDS protocol to obtain fault codes, abnormal information and real-time data in the system; c. Monitor the key parameters of the thermal management system in real time and determine whether the system is working normally based on the monitoring data; d. Based on the fault information and monitoring data read, use data analysis methods to identify the fault mode of the operating status of the thermal management system, and identify whether the relevant parameters of components such as the compressor, condenser, expansion valve and evaporator are within the safe range. If not, respond to the fault analysis based on the current data values ​​and take action; e. For the diagnosed fault, after repair, send a fault clearing instruction to the thermal management system through the UDS protocol and reset the system status; f. After the diagnosis is completed, the system will feedback the diagnosis results and related data to the user or maintenance personnel and provide corresponding maintenance suggestions.

2. A thermal management system fault diagnosis method based on UDS protocol according to claim 1, characterized in that: In b, the fault information includes fault code, abnormal information and real-time data, wherein the fault code is composed of a string of 4-bit characters YJKL, where Y is the fault level, i.e. A, B, C; J, K, L are hexadecimal numbers, J is a bit to be used, usually represented as 0; K is the component number; and L is the fault content number.

3. The thermal management system fault diagnosis method based on the UDS protocol according to claim 1 is characterized in that: In the above c, the key parameters include compressor inlet pressure, outlet pressure, inlet temperature, outlet temperature, inlet refrigerant mass flow rate, outlet refrigerant mass flow rate, compressor speed, condenser inlet pressure, outlet pressure, inlet temperature, outlet temperature, inlet air temperature, outlet air temperature, radiator gear, expansion valve inlet pressure, outlet pressure, inlet temperature, outlet temperature, inlet refrigerant mass flow rate, outlet refrigerant mass flow rate, expansion valve opening, evaporator inlet pressure, inlet temperature, inlet temperature, inlet air temperature, outlet air temperature and blower gear.

4. The thermal management system fault diagnosis method based on the UDS protocol according to claim 1 is characterized in that: In the above-mentioned step d, the response actions include sending a fault code, performing a fault protection action, sending a fault clearing instruction, and resetting the system status.

5. The thermal management system fault diagnosis method based on the UDS protocol according to claim 1 is characterized in that: In the above-mentioned step d, the fault protection actions include reducing the compressor speed, closing the radiator gear, closing the blower gear and reducing the expansion valve opening.

6. A thermal management system fault diagnosis method based on UDS protocol according to claim 1, characterized in that: In the above e, the fault clearing instruction is implemented through the "clear fault code" service in the UDS protocol.

7. The thermal management system fault diagnosis method based on the UDS protocol according to claim 1 is characterized in that: In said f, the diagnosis results and related data are displayed through the vehicle display screen or the remote diagnosis platform.

8. The thermal management system fault diagnosis method based on the UDS protocol according to claim 1 is characterized in that: The thermal management system includes internal combustion engine vehicles, electric vehicles and hybrid vehicles.

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