Hydraulic retarder cavity pressure online diagnosis method and system
By constructing a non-similar redundant architecture for parallel diagnosis of the hydraulic retarder cavity pressure sensor and proportional valve drive circuit, the problem of common-mode failure of the hydraulic retarder cavity pressure sensor was solved, achieving highly reliable and safe cavity pressure control.
Patent Information
- Application Number
- CN202610060719.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-16
- Publication Date
- 2026-04-03
AI Technical Summary
The redundant architecture of existing hydraulic retarder chamber pressure sensors cannot effectively avoid common-mode failure, resulting in insufficient control accuracy and safety.
By constructing a non-similar redundant architecture for the pressure sensor and the proportional valve drive current, the working status of the pressure sensor and the proportional valve drive circuit is diagnosed in parallel. The most reliable signal source is selected to determine the cavity pressure, or a safe value is set in the case of dual faults. High reliability diagnosis and fault-tolerant control are achieved by verifying the rationality of the air pressure and dynamically updating the current-pressure mapping relationship.
It significantly improves the availability of pressure signals in the hydraulic retarder chamber and the safety of the braking system, prevents common-mode failure, and ensures the accuracy of the pressure back-calculation model and the level of intelligent decision-making in the system under long-term use.
Smart Images
Figure CN121777877A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of hydraulic retarder technology, and specifically to an online diagnostic method and system for hydraulic retarder chamber pressure. Background Technology
[0002] Hydraulic retarders, as auxiliary braking devices, are typically installed on the driveshafts of heavy-duty vehicles. They mainly consist of a stator, rotor, working chamber, oil filling and discharging mechanism, and cooling system. The working principle of a hydraulic retarder is that the rotor rotates with the driveshaft. During operation, under the action of an external control system, compressed air enters above the oil tank, causing oil to enter the upper end of the stator through the oil inlet pipe, and then into the closed working chamber formed by the rotor and stator. Driven by the rotor blades, the oil circulates and impacts the stator blades, changing the momentum and generating a braking torque that hinders the rotation of the rotor impeller, thereby reducing the speed of the driveshaft and slowing down the vehicle. During deceleration, the proportional solenoid valve on the hydraulic retarder allows for precise control of the compressed air pressure in the working chamber, thus enabling precise control of the braking torque of the hydraulic retarder to adapt to different operating conditions.
[0003] Obtaining the actual air pressure value inside the working chamber can improve the control accuracy of the hydraulic retarder, and the availability of its signal is also of great significance to the improvement of the overall vehicle safety. The traditional method is to install a pressure sensor on the chamber to obtain the actual pressure of the chamber. In order to avoid the failure of a pressure sensor, a backup pressure sensor can be set to improve reliability. However, this method can usually only deal with the problem of pressure sensor failure due to its own quality. That is, it belongs to a similar redundancy architecture and cannot effectively avoid common mode failure. Therefore, it still cannot meet the actual control requirements. Summary of the Invention
[0004] The purpose of this invention is to provide an online diagnostic method and system for hydraulic retarder chamber pressure, thereby solving the technical problem of common mode failure.
[0005] The solution of the present invention to the above-mentioned technical problems is as follows: A method for online diagnosis of pressure in a hydraulic retarder cavity includes the following steps: Determine whether the pressure sensor inside the retarder cavity is faulty by using sensor fault criteria; Determine whether the drive circuit of the retarder proportional valve is faulty by using the drive circuit fault criteria. If both the pressure sensor and the retarder proportional valve drive circuit are normal, the current pressure in the retarder chamber is determined by the pressure sensor inside the retarder chamber. If only the pressure sensor is faulty, the current retarder chamber pressure is determined by mapping the current in the retarder proportional valve drive circuit to the retarder chamber pressure. If only the retarder proportional valve drive circuit is faulty, the current retarder chamber pressure is determined by the pressure sensor inside the retarder chamber. If both the pressure sensor and the retarder proportional valve drive circuit fail, the pressure inside the retarder chamber will be controlled to a safe value.
[0006] Further specifying, if both the pressure sensor and the retarder proportional valve drive circuit are functioning normally, determining the current retarder chamber pressure using the pressure sensor within the retarder chamber includes the following steps: If the pressure sensor and the retarder proportional valve are both normal, then perform a pressure rationality check. If the air pressure rationality verification passes, the current retarder chamber pressure is determined by the pressure sensor inside the retarder chamber. If the air pressure rationality check fails, the pressure value obtained by the pressure sensor in the retarder cavity is compared with the pressure value obtained by mapping the current and retarder cavity pressure through the retarder proportional valve drive circuit, and the maximum pressure value is selected as the current retarder cavity pressure.
[0007] Further specifying, the air pressure rationality verification specifically includes: Set the air pressure tolerance threshold and tolerance period; Determine whether the difference between the pressure value obtained by the pressure sensor inside the retarder cavity and the pressure value obtained by mapping the current and retarder cavity pressure through the retarder proportional valve drive circuit is greater than the air pressure tolerance threshold and the time exceeds the tolerance period. If yes, the air pressure rationality check fails; if no, the air pressure rationality check passes.
[0008] Further defining the sensor failure criteria is as follows: Collect the voltage value of the pressure sensor inside the retarder chamber, and set the minimum and maximum operating voltage of the pressure sensor; Determine if the voltage value of the pressure sensor inside the retarder cavity is less than the minimum operating voltage. If yes, the pressure sensor is open-circuited. If no, determine if the voltage value of the pressure sensor inside the retarder cavity is greater than the maximum operating voltage. If yes, the pressure sensor is short-circuited. If no, the pressure sensor is normal.
[0009] Further defining the fault criteria for the drive circuit is as follows: Set the maximum operating current and maximum error current of the proportional valve drive circuit; Collect the current of the retarder proportional valve drive circuit and the corresponding retarder chamber pressure, and determine whether the current of the retarder proportional valve drive circuit is greater than the maximum operating current. If so, it is determined that there is a fault in the retarder proportional valve drive circuit; if not, the target current is determined according to the mapping relationship between the current in the retarder proportional valve drive circuit and the retarder chamber pressure. Determine whether the absolute value of the difference between the current in the retarder proportional valve drive circuit and the target current is greater than the maximum error current. If it is, then the retarder proportional valve drive circuit is faulty; if not, then the retarder proportional valve drive circuit is normal.
[0010] Further specifying, the establishment of the mapping relationship between the current in the retarder proportional valve drive circuit and the retarder chamber pressure includes the following steps: During the operation of the retarder, the pressure in the retarder cavity and the current value of the retarder proportional valve drive circuit at the corresponding time are collected at set intervals to obtain a current-pressure dataset. Filter the current-pressure dataset; The mapping relationship between the current value of the retarder proportional valve drive circuit and the retarder cavity pressure is determined and saved based on the filtered current-pressure dataset.
[0011] Furthermore, the online diagnostic method for the hydraulic retarder chamber pressure also includes the following steps: When the mapping relationship update condition is met, update the mapping relationship between the current in the retarder proportional valve drive circuit and the retarder chamber pressure.
[0012] Further specifying, the update condition for the mapping relationship is: The pressure sensor and retarder proportional valve drive circuit are both normal and the vehicle speed is less than the set safe speed. Updating the mapping relationship between current and retarder chamber pressure in the retarder proportional valve drive circuit includes the following steps: Based on the retarder chamber pressure range, N different retarder chamber pressures are set as target pressures; Set n=1, and control the pressure inside the retarder chamber to reach the nth target pressure; After the pressure inside the retarder chamber stabilizes, the current In of the current retarder proportional valve drive circuit is collected. Determine if i is equal to N. If not, set n = n + 1 and re-acquire the current In of the retarder proportional valve drive circuit corresponding to the nth target pressure. If yes, update and save the mapping relationship between the current value of the retarder proportional valve drive circuit and the retarder cavity pressure based on the obtained N retarder proportional valve drive circuit currents and the corresponding N target pressures.
[0013] An online diagnostic system for hydraulic retarder chamber pressure includes: The pressure sensor fault diagnosis module is used to determine whether the pressure sensor in the retarder cavity is faulty based on the sensor fault criteria. The drive circuit fault diagnosis module is used to determine whether the drive circuit of the retarder proportional valve is faulty based on the drive circuit fault criteria. The retarder chamber pressure determination module is used to determine the current retarder chamber pressure when both the pressure sensor and the retarder proportional valve drive circuit are functioning normally, by using the pressure sensor inside the retarder chamber; when only the pressure sensor is faulty, it determines the current retarder chamber pressure by mapping the current in the retarder proportional valve drive circuit to the retarder chamber pressure; when only the retarder proportional valve drive circuit is faulty, it determines the current retarder chamber pressure by using the pressure sensor inside the retarder chamber; when both the pressure sensor and the retarder proportional valve drive circuit are faulty, it controls the pressure inside the retarder chamber to a safe value.
[0014] Further restrictions also include: The learning update module is used to update the mapping relationship between the current in the retarder proportional valve drive circuit and the retarder cavity pressure when the mapping relationship update conditions are met.
[0015] The beneficial effects of this invention are as follows: 1. This invention achieves highly reliable diagnosis and fault-tolerant control of retarder chamber pressure by constructing a non-similar redundant architecture for the pressure sensor and proportional valve drive current. First, the working status of the pressure sensor and proportional valve drive circuit is diagnosed in parallel. Then, based on the diagnosis results, the most reliable signal source is selected to determine the final chamber pressure, or the pressure is set to a safe value in the event of a double fault. This effectively avoids system failure caused by the failure of a single sensor, significantly improves the availability of pressure signals and the safety of the entire braking system, and in particular, can prevent common-mode failure problems that are difficult to solve with traditional similar redundant architectures.
[0016] 2. This invention enhances the accuracy and adaptability of the core diagnostic logic by introducing specific methods such as air pressure rationality verification and dynamic updating of the current-pressure mapping relationship. The air pressure rationality verification can make judgments when both signals are normal but significant deviations occur, improving the system's intelligent decision-making level. The system can automatically learn and update the current-pressure mapping relationship under safe conditions, which effectively compensates for system performance drift caused by factors such as component aging and environmental changes, ensuring the accuracy of the pressure back-calculation model under long-term use, thereby maintaining the effectiveness of the diagnostic method throughout its entire life cycle. Attached Figure Description
[0017] Figure 1 This is a schematic diagram of the online diagnostic method for hydraulic retarder chamber pressure in Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the online diagnostic method for hydraulic retarder chamber pressure in Embodiment 2 of the present invention; Figure 3 This is a schematic diagram of the online diagnostic system for the hydraulic retarder chamber pressure of the present invention. Detailed Implementation
[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.
[0019] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.
[0020] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.
[0021] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper," "lower," "horizontal," or "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, terms such as "first" and "second" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.
[0022] Example 1 refer to Figure 1 This invention provides an online diagnostic method for the chamber pressure of a hydraulic retarder, using an electronic control unit on a vehicle, comprising the following steps: Determine whether the pressure sensor inside the retarder cavity is faulty by using sensor fault criteria; Determine whether the drive circuit of the retarder proportional valve is faulty by using the drive circuit fault criteria. If both the pressure sensor and the retarder proportional valve drive circuit are normal, the current pressure in the retarder chamber is determined by the pressure sensor inside the retarder chamber. If only the pressure sensor is faulty, the current retarder chamber pressure is determined by mapping the current in the retarder proportional valve drive circuit to the retarder chamber pressure. If only the retarder proportional valve drive circuit is faulty, the current retarder chamber pressure is determined by the pressure sensor inside the retarder chamber. If both the pressure sensor and the retarder proportional valve drive circuit fail, the pressure inside the retarder chamber will be controlled to a safe value.
[0023] Specifically, before determining the retarder chamber pressure, it is necessary to diagnose the faults of the pressure sensor and the drive circuit of the retarder proportional valve to avoid directly acquiring erroneous data; a non-similar redundant architecture of the pressure sensor signal and the proportional valve drive circuit current signal is adopted to achieve highly reliable diagnosis and fault-tolerant control of the chamber pressure.
[0024] The sensor failure criteria are as follows: Collect the voltage value of the pressure sensor inside the retarder cavity, and set the minimum and maximum operating voltages of the pressure sensor. The minimum operating voltage is 0.25V, and the maximum operating voltage is 4.95V.
[0025] Determine if the voltage value of the pressure sensor inside the retarder cavity is less than the minimum operating voltage. If yes, the pressure sensor is open-circuited. If no, determine if the voltage value of the pressure sensor inside the retarder cavity is greater than the maximum operating voltage. If yes, the pressure sensor is short-circuited. If no, the pressure sensor is normal.
[0026] The fault criteria for the drive circuit are: Set the maximum operating current and maximum error current of the proportional valve drive circuit. The maximum operating current and maximum error current are both taken as 30mA.
[0027] Collect the current of the retarder proportional valve drive circuit and the corresponding retarder chamber pressure, and determine whether the current of the retarder proportional valve drive circuit is greater than the maximum operating current. If so, it is determined that there is a fault in the retarder proportional valve drive circuit; if not, the target current is determined according to the mapping relationship between the current in the retarder proportional valve drive circuit and the retarder chamber pressure. Determine whether the absolute value of the difference between the current in the retarder proportional valve drive circuit and the target current is greater than the maximum error current. If it is, then the retarder proportional valve drive circuit is faulty; if not, then the retarder proportional valve drive circuit is normal.
[0028] To further explain, establishing the mapping relationship between the current in the retarder proportional valve drive circuit and the retarder chamber pressure includes the following steps: During the operation of the retarder, the electronic control unit collects the retarder chamber pressure and the corresponding current value of the retarder proportional valve drive circuit at set intervals (10ms for example), and obtains the current-pressure dataset through digital-to-analog conversion; at this time, the pressure sensor and proportional valve drive circuit are ensured to be fault-free, ensuring the accuracy of data acquisition.
[0029] Filter the current-pressure dataset, for example, by using mean filtering, to suppress high-frequency noise interference.
[0030] The mapping relationship between the current value of the retarder proportional valve drive circuit and the retarder cavity pressure is determined and saved based on the filtered current-pressure dataset. The mapping relationship between the current value of the retarder proportional valve drive circuit and the retarder cavity pressure is saved by constructing a relational formula or a table.
[0031] To further clarify, when both the pressure sensor and the proportional valve drive circuit are diagnosed as normal, it is necessary to further verify the rationality of the two signals in order to detect potential latent faults or drifts that have not triggered the above diagnoses.
[0032] Specifically, if both the pressure sensor and the retarder proportional valve drive circuit are functioning normally, determining the current retarder chamber pressure using the pressure sensor within the retarder chamber involves the following steps: If the pressure sensor and the retarder proportional valve are both normal, then perform a pressure rationality check. If the air pressure rationality verification passes, the current retarder chamber pressure is determined by the pressure sensor inside the retarder chamber. If the air pressure rationality check fails, it indicates that there is a significant discrepancy between the two signals. In this case, the pressure value obtained by the pressure sensor in the retarder cavity is compared with the pressure value obtained by mapping the current and retarder cavity pressure through the retarder proportional valve drive circuit. The maximum pressure value is selected as the current retarder cavity pressure to avoid excessive braking force due to one signal underestimating the pressure.
[0033] Specifically, the air pressure rationality verification is as follows: Set the air pressure tolerance threshold and tolerance period. The air pressure tolerance threshold is 20 kPa, and the tolerance period is 10 set intervals.
[0034] Determine whether the difference between the pressure value obtained by the pressure sensor inside the retarder cavity and the pressure value obtained by mapping the current and retarder cavity pressure through the retarder proportional valve drive circuit is greater than the air pressure tolerance threshold and the time exceeds the tolerance period; if yes, the air pressure rationality check fails; if no, the air pressure rationality check passes.
[0035] Specifically, the driver needs to be alerted when either the pressure sensor or the proportional valve drive circuit malfunctions, or when the air pressure validity check fails. A strong reminder is required when both malfunction simultaneously. Example 2 refer to Figure 2 Based on the online diagnostic method for hydraulic retarder chamber pressure provided in Embodiment 1, to ensure the accuracy of pressure calculation by current after long-term use, the mapping relationship needs to be updated and learned online. Therefore, the online diagnostic method for hydraulic retarder chamber pressure provided in this embodiment further includes the following steps: When the mapping relationship update condition is met, update the mapping relationship between the current in the retarder proportional valve drive circuit and the retarder chamber pressure.
[0036] Self-learning should be performed when safety conditions are met, such as when the vehicle speed is below the set safe speed (e.g., 2 km / h), the pressure sensor and drive circuit are functioning normally, and there are no other emergency braking requests.
[0037] The mapping relationship update condition is as follows: The pressure sensor and the retarder proportional valve drive circuit are both normal and the vehicle speed is less than the set safe speed, with 2 km / h as an example.
[0038] The process of updating the mapping relationship between the current and the retarder chamber pressure in the retarder proportional valve drive circuit includes the following steps: Based on the retarder chamber pressure range, N different retarder chamber pressures are set as target pressures, where N is a positive integer. Typically, the value of N is determined according to the retarder chamber pressure range. For example, if the pressure range is 0~3.5 Bar, N is 6, meaning that 6 target pressures are determined within the pressure range, and the corresponding proportional valve drive circuit current is obtained at the same time.
[0039] With n=1 set, the proportional valve begins to adjust until the pressure value of the pressure sensor in the retarder chamber reaches the nth target pressure. After the pressure inside the retarder chamber stabilizes, the current In of the current retarder proportional valve drive circuit is collected. Determine if i equals N. If not, set n = n + 1, and re-acquire the current In of the retarder proportional valve drive circuit corresponding to the nth target pressure until N corresponding retarder proportional valve drive circuit currents are obtained. If yes, update the mapping relationship between the retarder proportional valve drive circuit current value and the retarder cavity pressure based on the obtained N retarder proportional valve drive circuit currents and the corresponding N target pressures, and save it.
[0040] By default, when the retarder chamber pressure is 0, the corresponding retarder proportional valve drive circuit current is 0. Therefore, it is preferable to combine N target pressures and the corresponding retarder proportional valve drive circuit currents to update and save the mapping relationship between the retarder proportional valve drive circuit current value and the retarder chamber pressure.
[0041] Through the systematic implementation of the above steps, real-time and reliable diagnosis and fault-tolerant control of the hydraulic retarder chamber pressure were achieved, significantly improving the safety and reliability of the auxiliary braking system.
[0042] Example 3 An online diagnostic system for the chamber pressure of a hydraulic retarder, characterized in that it comprises: The pressure sensor fault diagnosis module is used to determine whether the pressure sensor in the retarder cavity is faulty based on the sensor fault criteria. The drive circuit fault diagnosis module is used to determine whether the drive circuit of the retarder proportional valve is faulty based on the drive circuit fault criteria. The retarder chamber pressure determination module is used to determine the current retarder chamber pressure when both the pressure sensor and the retarder proportional valve drive circuit are functioning normally, by using the pressure sensor inside the retarder chamber; when only the pressure sensor is faulty, it determines the current retarder chamber pressure by mapping the current in the retarder proportional valve drive circuit to the retarder chamber pressure; when only the retarder proportional valve drive circuit is faulty, it determines the current retarder chamber pressure by using the pressure sensor inside the retarder chamber; when both the pressure sensor and the retarder proportional valve drive circuit are faulty, it controls the pressure inside the retarder chamber to a safe value.
[0043] Preferably, the online diagnostic system for hydraulic retarder chamber pressure also includes: The learning update module is used to update the mapping relationship between the current in the retarder proportional valve drive circuit and the retarder cavity pressure when the mapping relationship update conditions are met.
[0044] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the scope of the invention. No reference numerals in the claims should be construed as limiting the scope of the claims.
[0045] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that can be understood by those skilled in the art. The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.
[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.
Claims
1. A method for online diagnosis of pressure in a hydraulic retarder cavity, characterized in that, Includes the following steps: Determine whether the pressure sensor inside the retarder cavity is faulty by using sensor fault criteria; Determine whether the drive circuit of the retarder proportional valve is faulty by using the drive circuit fault criteria. If both the pressure sensor and the retarder proportional valve drive circuit are normal, the current pressure in the retarder chamber is determined by the pressure sensor inside the retarder chamber. If only the pressure sensor is faulty, the current retarder chamber pressure is determined by mapping the current in the retarder proportional valve drive circuit to the retarder chamber pressure. If only the retarder proportional valve drive circuit is faulty, the current retarder chamber pressure is determined by the pressure sensor inside the retarder chamber. If both the pressure sensor and the retarder proportional valve drive circuit fail, the pressure inside the retarder chamber will be controlled to a safe value.
2. The online diagnostic method for hydraulic retarder chamber pressure according to claim 1, characterized in that, If both the pressure sensor and the retarder proportional valve drive circuit are functioning normally, determining the current retarder chamber pressure using the pressure sensor within the retarder chamber involves the following steps: If the pressure sensor and the retarder proportional valve are both normal, then perform a pressure rationality check. If the air pressure rationality verification passes, the current retarder chamber pressure is determined by the pressure sensor inside the retarder chamber. If the air pressure rationality check fails, the pressure value obtained by the pressure sensor in the retarder cavity is compared with the pressure value obtained by mapping the current and retarder cavity pressure through the retarder proportional valve drive circuit, and the maximum pressure value is selected as the current retarder cavity pressure.
3. The online diagnostic method for hydraulic retarder chamber pressure according to claim 2, characterized in that, The specific steps of the air pressure rationality verification are as follows: Set the air pressure tolerance threshold and tolerance period; Determine whether the difference between the pressure value obtained by the pressure sensor inside the retarder cavity and the pressure value obtained by mapping the current and retarder cavity pressure through the retarder proportional valve drive circuit is greater than the air pressure tolerance threshold and the time exceeds the tolerance period. If yes, the air pressure rationality check fails; if no, the air pressure rationality check passes.
4. The online diagnostic method for hydraulic retarder chamber pressure according to claim 1, characterized in that, The sensor failure criteria are as follows: Collect the voltage value of the pressure sensor inside the retarder chamber, and set the minimum and maximum operating voltage of the pressure sensor; Determine if the voltage value of the pressure sensor inside the retarder cavity is less than the minimum operating voltage. If yes, the pressure sensor is open-circuited. If no, determine if the voltage value of the pressure sensor inside the retarder cavity is greater than the maximum operating voltage. If yes, the pressure sensor is short-circuited. If no, the pressure sensor is normal.
5. The online diagnostic method for hydraulic retarder chamber pressure according to claim 1, characterized in that, The fault criteria for the drive circuit are as follows: Set the maximum operating current and maximum error current of the proportional valve drive circuit; Collect the current of the retarder proportional valve drive circuit and the corresponding retarder chamber pressure, and determine whether the current of the retarder proportional valve drive circuit is greater than the maximum operating current. If so, it is determined that there is a fault in the retarder proportional valve drive circuit; if not, the target current is determined according to the mapping relationship between the current in the retarder proportional valve drive circuit and the retarder chamber pressure. Determine whether the absolute value of the difference between the current in the retarder proportional valve drive circuit and the target current is greater than the maximum error current. If it is, then the retarder proportional valve drive circuit is faulty; if not, then the retarder proportional valve drive circuit is normal.
6. The online diagnostic method for hydraulic retarder chamber pressure according to claim 1, characterized in that, Establishing the mapping relationship between the current in the retarder proportional valve drive circuit and the retarder chamber pressure includes the following steps: During the operation of the retarder, the pressure in the retarder cavity and the current value of the retarder proportional valve drive circuit at the corresponding time are collected at set intervals to obtain a current-pressure dataset. Filter the current-pressure dataset; The mapping relationship between the current value of the retarder proportional valve drive circuit and the retarder cavity pressure is determined and saved based on the filtered current-pressure dataset.
7. The online diagnostic method for hydraulic retarder chamber pressure according to claim 1, characterized in that, The online diagnostic method for hydraulic retarder chamber pressure also includes the following steps: When the mapping relationship update condition is met, update the mapping relationship between the current in the retarder proportional valve drive circuit and the retarder chamber pressure.
8. The online diagnostic method for hydraulic retarder chamber pressure according to claim 7, characterized in that, The mapping relationship update condition is: The pressure sensor and retarder proportional valve drive circuit are both normal and the vehicle speed is less than the set safe speed. Updating the mapping relationship between current and retarder chamber pressure in the retarder proportional valve drive circuit includes the following steps: Based on the retarder chamber pressure range, N different retarder chamber pressures are set as target pressures; Set n=1, and control the pressure inside the retarder chamber to reach the nth target pressure; After the pressure inside the retarder chamber stabilizes, the current In of the current retarder proportional valve drive circuit is collected. Determine if i is equal to N. If not, set n = n + 1 and re-acquire the current In of the retarder proportional valve drive circuit corresponding to the nth target pressure. If yes, update the mapping relationship between the current value of the retarder proportional valve drive circuit and the retarder cavity pressure based on the obtained N retarder proportional valve drive circuit currents and the corresponding N target pressures, and save it.
9. An online diagnostic system for the chamber pressure of a hydraulic retarder, characterized in that, include: The pressure sensor fault diagnosis module is used to determine whether the pressure sensor in the retarder cavity is faulty based on the sensor fault criteria. The drive circuit fault diagnosis module is used to determine whether the drive circuit of the retarder proportional valve is faulty based on the drive circuit fault criteria. The retarder chamber pressure determination module is used to determine the current retarder chamber pressure when both the pressure sensor and the retarder proportional valve drive circuit are functioning normally, by using the pressure sensor inside the retarder chamber; when only the pressure sensor is faulty, it determines the current retarder chamber pressure by mapping the current in the retarder proportional valve drive circuit to the retarder chamber pressure; when only the retarder proportional valve drive circuit is faulty, it determines the current retarder chamber pressure by using the pressure sensor inside the retarder chamber; when both the pressure sensor and the retarder proportional valve drive circuit are faulty, it controls the pressure inside the retarder chamber to a safe value.
10. The online diagnostic system for hydraulic retarder chamber pressure according to claim 9, characterized in that, Also includes: The learning update module is used to update the mapping relationship between the current in the retarder proportional valve drive circuit and the retarder cavity pressure when the mapping relationship update conditions are met.