Control method and system for hydraulic retarder of heavy truck and vehicle

Abstract

The invention discloses a heavy truck hydraulic retarder control method and system and a vehicle, and belongs to the technical field of retarder control. The method comprises the steps that the target braking torque value of a retarder is read; if the target braking torque value is larger than or equal to the maximum output torque value, the target braking torque value is set to be the maximum output torque value; if yes, the target braking torque value is dynamically compensated; calculating a target working pressure value of the retarder cavity; and the deviation between the target working pressure value of the retarder containing cavity and the current working pressure and the deviation between the proportional valve target and the actual current are calculated, calculation is conducted through a PID controller, and the output serves as the input of the retarder proportional valve so as to control the output torque of the retarder. According to the invention, the output torque delay can be reduced so as to improve the braking performance of the retarder, the braking precision and stability are relatively high, and relatively stable braking can be maintained under the conditions of different vehicle speeds and different oil temperatures.

Description

Technical Field

[0001] The present invention belongs to the technical field of retarder control, and particularly relates to a control method and system for a hydraulic retarder of a heavy truck, and a vehicle. Background Art

[0002] The heavy load of a heavy truck places high requirements on the performance of its braking system. When the vehicle is driving on a long downhill section, if only the wheel side braking system of the vehicle is used, measures such as continuous water spraying are required to cool the braking system to maintain effective braking performance, but this method cannot meet the usage requirements. In order to meet the requirements of large braking torque and long-term effective braking, the most widely used and effective method at present is to install a hydraulic retarder at the output shaft end of the heavy truck transmission. The control of the hydraulic retarder includes constant torque mode control and constant vehicle speed mode control. No matter which mode, ultimately, the actual output torque of the retarder is controlled according to the target braking torque command obtained by the controller. The prior art monitors the pressure in the retarder cavity, and according to the maximum braking torque and the maximum cavity pressure value obtained by prior experiments, converts the target braking torque command into a target braking pressure in proportion, and then calculates the control input of the proportional valve through the deviation value between the target pressure and the actual pressure by a PID controller to achieve the control of the target torque. However, the prior art has the following problems in output torque control: The torque output delay is obvious. When the retarder receives a braking command, the cavity of the retarder starts to be filled with oil, but the oil filling process is relatively slow, resulting in a torque output delay. In the constant speed control mode, it will cause the vehicle speed to deviate from the target vehicle speed by a large amount before the vehicle speed can be effectively controlled. The time taken to reach the target torque value is relatively long in the constant torque control mode. Over-control leads to large fluctuations in the output torque, and at the same time increases the time taken to reach the steady-state torque. The prior art controls the proportional valve through the deviation between the target pressure value in the retarder cavity and the actual pressure value collected by the sensor. Since the process of establishing the oil pressure is relatively slow, this results in the opening of the oil supply port of the proportional valve being out of sync with the corresponding theoretical system oil pressure, leading to excessive control input, thereby increasing the control time to reach the steady state. The control accuracy is not high, and there are significant differences in the control effects at different vehicle speeds and different retarder oil temperatures. The rotational speed of the retarder impeller and the oil temperature have a great influence on the maximum torque that can be output by the retarder. If this factor is not considered and it is assumed that the maximum torque of the retarder is the maximum torque value under all working conditions, and the target pressure is calculated uniformly using the maximum torque value of the retarder under different working conditions, inaccurate target pressure will be obtained, which will have a certain impact on the control accuracy. Therefore, in summary, when controlling the output torque of the retarder at present, there is a relatively obvious torque output delay, over-control leads to large fluctuations in the output torque while increasing the time taken to reach the steady-state torque, and the control accuracy needs to be further improved. Summary of the Invention

[0003] The present invention provides a control method and system for a heavy truck hydraulic retarder, and a vehicle, aiming to solve the problems that in the current control of the output torque of the retarder, the delay of torque output is relatively obvious, over-control leads to large fluctuations in the output torque while increasing the time to reach the steady-state torque, and the control accuracy needs to be further improved.

[0004] To achieve the above object, the present invention adopts the following technical solutions: The present invention provides a control method for a heavy truck hydraulic retarder, including the following steps: S1. Read the target braking torque value of the retarder; If the target braking torque value of the retarder is greater than or equal to the maximum output torque value of the retarder, then set the target braking torque value of the retarder to the maximum output torque value of the retarder to form the processed target braking torque value of the retarder; If the target braking torque value of the retarder is less than the maximum output torque value of the retarder, then perform dynamic compensation on the target braking torque value to form the processed target braking torque value of the retarder; S2. Calculate the target working pressure value of the retarder cavity according to the processed target braking torque value of the retarder and the maximum output torque value of the retarder; S3. Calculate the deviation between the target working pressure value of the retarder cavity and the current working pressure of the retarder, and the deviation between the target current and the actual current of the proportional valve. Through PID controller calculation, take the output of the PID controller as the input of the retarder proportional valve to control the output torque of the retarder.

[0005] In some embodiments, in S1, the following dynamic compensation is performed on the target braking torque value: If , then , where: (1); Wherein, is the target braking torque value of the retarder, is the maximum output torque value of the retarder, is the processed target braking torque value of the retarder, is the current working pressure of the retarder working chamber, is the maximum pressure value of the retarder working chamber, is the oil filling characteristic time constant of the retarder, is time.

[0006] Further, in S1, during the control process, the current working pressure of the retarder working chamber is collected in real time.

[0007] Further, in S1, the maximum pressure value of the retarder working chamber and the retarder oil filling characteristic time constant are pre-measured.

[0008] In some embodiments, in S2, according to the retarder braking torque database, the current oil temperature of the retarder, and the driving wheel speed, the maximum output torque value of the retarder under the current conditions is obtained. Based on the maximum output torque value of the retarder under the current conditions, the target working pressure value of the retarder is calculated through the following formula (2): ) (2); Wherein, is the target working pressure value of the retarder, is the maximum output torque value under the current conditions.

[0009] Further, in S2, the liquid filling rate input value of the retarder is set to 100%.

[0010] In some embodiments, in S3, the following formula (3) is used to calculate the deviation between the target working pressure value of the retarder cavity and the current working pressure of the retarder: (3).

[0011] In some embodiments, in S3, the PID controller calculates the control input of the proportional valve through the following formula (4): (4); (5); Wherein, is the control input of the proportional valve, is the current moment, are all PID controller parameters, is a preset pressure constant value, is the deviation between the proportional valve target current and the actual current, is the pressure deviation change rate.

[0012] In some embodiments, in S3, the deviation between the proportional valve target current and the actual current is obtained through the following formula (6): (6); The target current value is obtained through the following formula (7): ) (7); Wherein, is the current value obtained from the retarder sensor at the current moment, is the target current value, is the maximum input current of the retarder proportional valve, is a constant value obtained by pre-testing according to the pressure deviation range.

[0013] The present invention also provides a control system for a heavy truck hydraulic retarder. The system includes a data acquisition module, a target braking torque value processing module, a pressure calculation module, and a PID controller calculation module, where: Data acquisition module: used to collect in real time the input current of the retarder proportional valve, the pressure in the retarder cavity, the rotational speed of the retarder driving wheel, and the oil temperature of the retarder; Target braking torque value processing module: used to read the target braking torque value of the retarder; If the target braking torque value of the retarder is greater than or equal to the maximum output torque value of the retarder, then the target braking torque value of the retarder is set to the maximum output torque value of the retarder to form the processed target braking torque value of the retarder; If the target braking torque value of the retarder is less than the maximum output torque value of the retarder, then the target braking torque value is dynamically compensated to form the processed target braking torque value of the retarder; Pressure calculation module: used to calculate the target working pressure value of the retarder cavity according to the processed target braking torque value of the retarder and the maximum output torque value of the retarder PID controller calculation module: used to calculate the deviation between the target working pressure value of the retarder cavity and the current working pressure of the retarder. Through PID controller calculation, the output of the PID controller is used as the input of the retarder proportional valve to control the output torque of the retarder.

[0014] The present invention also provides a vehicle, which includes the control system of the heavy truck hydraulic retarder as above.

[0015] Compared with the prior art, the control method, system, and vehicle of the heavy truck hydraulic retarder of the present invention have the following beneficial effects: In the torque control stage when the vehicle starts the retarder, the present invention can control the output torque of the retarder to the target torque value faster by compensating the target torque value in real time, improving the response speed of the retarder. Converting the target torque value into a pressure value improves the control accuracy. Through the calculation of the PID controller, the present invention reduces the over-control caused by the delay of the actual working pressure feedback, thereby reducing the time for the torque to reach the steady state and reducing the torque fluctuation. By querying the maximum torque that the retarder can output currently at different vehicle speeds and different retarder oil temperatures, and using this torque value and the target torque value to calculate the target working pressure, the control accuracy and stability are improved.

[0016] Furthermore, the present invention coordinates the current working pressure and the maximum working pressure of the retarder working chamber, as well as the retarder oil filling characteristic time constant, etc., and further improves the response speed of the retarder by integrating and setting a compensation formula.

[0017] Furthermore, the present invention obtains the maximum output torque value of the retarder under current conditions based on the retarder braking torque database, the current oil temperature of the retarder, and the driving wheel speed, improves the calculation accuracy, and further improves the control stability of the retarder.

[0018] The present invention can reduce the output torque delay, improve the braking performance of heavy trucks, and make the vehicle braking process more in line with the driver's braking intention. When using the retarder for vehicle braking, the braking effect is more stable, the time required to achieve the target braking demand is shorter, enhancing vehicle driving comfort and vehicle controllability. It improves the braking accuracy of the retarder under comprehensive operating conditions and the working applicability of the vehicle, and can maintain relatively stable braking performance under different vehicle speeds and different oil temperature conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings in the specification are used to provide a further understanding of the present invention, and constitute a part of the present invention. The schematic 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.

[0020] Figure 1 It is a schematic diagram of the control flow of a control method for a heavy truck hydraulic retarder of the present invention; Figure 2 It is a schematic diagram of the working principle of a hydraulic retarder torque control system in a control method for a heavy truck hydraulic retarder of the present invention; Figure 3 It is a schematic diagram of a braking torque database in a control method for a heavy truck hydraulic retarder of the present invention.

[0021] Among them, 1. Retarder, 2. Proportional valve, 3. Variable pump, 4. Drain valve, 5. Fuel tank, 6. Working chamber, 7. Transmission shaft. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Usually, the components of the embodiments of the present invention described and illustrated in the accompanying drawings here can be arranged and designed in various different configurations.

[0023] Accordingly, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0024] It should be noted that like reference numerals and letters denote like items in the following drawings. Therefore, once an item is defined in one drawing, it does not require further definition and explanation in subsequent drawings.

[0025] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper", "lower", "horizontal", "inner", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the invention product is habitually placed during use, it 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 operated in a specific orientation, and thus should not be construed as a limitation of the present invention. In addition, terms such as "first", "second", etc. are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance.

[0026] In addition, if the term "horizontal" appears, it does not mean that the component is required to be absolutely horizontal, but it can be slightly inclined. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but it can be slightly inclined.

[0027] In the description of the embodiments of the present invention, it should also be noted that unless otherwise clearly specified and limited, if terms such as "set", "installed", "connected", "connected to" are understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0028] How to make the vehicle braking process more in line with the driver's braking intention, shorten the time required to achieve the target braking demand, enhance the vehicle driving comfort and vehicle controllability, and improve the braking accuracy of the retarder and the vehicle working applicability under comprehensive operating conditions.

[0029] As Figure 1 and Figure 2 shown, a control method for a heavy truck hydraulic retarder of the present invention includes the following steps: S1. Read the target braking torque value of the retarder; If the target braking torque value of the retarder is greater than or equal to the maximum output torque value of the retarder, the target braking torque value of the retarder is set to the maximum output torque value of the retarder to form the target braking torque value of the processed retarder; If the target braking torque value of the retarder is less than the maximum output torque value of the retarder, the target braking torque value is dynamically compensated to form the target braking torque value of the processed retarder; S2. Calculate the target working pressure value of the retarder cavity according to the target braking torque value of the processed retarder and the maximum output torque value of the retarder; S3. Calculate the deviation between the target working pressure value of the retarder cavity and the current working pressure of the retarder, and the deviation between the target current and the actual current of the proportional valve. Through PID controller calculation, the output of the PID controller is used as the input of the retarder proportional valve to control the output torque of the retarder.

[0030] In the torque control stage of starting the retarder of the vehicle, the control method of the present invention can control the output torque of the retarder to the target torque value faster by compensating the target torque value. In the process of solenoid valve control, a control algorithm is constructed by comprehensively considering the control current of the proportional valve and the pressure parameter of the retarder working chamber, taking into account the rapidity of current feedback control and the accuracy of indirectly reflecting the actual torque by pressure. Thus, the over-control caused by the delay of actual working pressure feedback is reduced, the time for the torque to reach the steady state is reduced, the control accuracy is improved, and the fluctuation of the retarder output torque is reduced. By querying the maximum torque that the retarder can output currently at different vehicle speeds and different retarder oil temperatures, and using this torque value and the target torque value to calculate the target working pressure, the compensation for the influence of oil temperature and speed on the braking torque is realized, thereby improving the control accuracy and stability. It brings a better driving experience for the driver.

[0031] The present invention also provides a control system for a heavy truck hydraulic retarder. The control system includes a data acquisition module, a target braking torque value processing module, a pressure calculation module, and a PID controller calculation module, wherein: The data acquisition module: is used to collect in real time the input current of the retarder proportional valve, the pressure in the retarder cavity, the rotation speed of the retarder driving wheel, and the retarder oil temperature; The target braking torque value processing module: is used to read the target braking torque value of the retarder; If the target braking torque value of the retarder is greater than or equal to the maximum output torque value of the retarder, the target braking torque value of the retarder is set to the maximum output torque value of the retarder to form the target braking torque value of the processed retarder; If the target braking torque value of the retarder is less than the maximum output torque value of the retarder, the target braking torque value is dynamically compensated to form the target braking torque value of the processed retarder; Pressure calculation module: used to calculate the target working pressure value of the retarder cavity according to the target braking torque value of the processed retarder and the maximum output torque value of the retarder PID controller calculation module: calculates the deviation between the target working pressure value of the retarder cavity and the current working pressure of the retarder, and the deviation between the target current and the actual current of the proportional valve. Through PID controller calculation, the output of the PID controller is used as the input of the retarder proportional valve to control the output torque of the retarder.

[0032] The system provided by the present invention provides a carrier for the control method of the heavy truck hydraulic retarder, thereby realizing the precise and rapid response of the retarder.

[0033] The present invention also provides a vehicle, which includes the above-mentioned control system of the heavy truck hydraulic retarder. By adopting the system of the present invention, the control accuracy and stability of the vehicle retarder can be improved.

[0034] The following further elaborates on a control method and system for a heavy truck hydraulic retarder of the present invention through specific embodiments.

[0035] Step 1: Pretreatment of the retarder target torque value; When the vehicle starts the retarder braking, the retarder torque control system will receive the target braking torque value , and at this time, the system makes a judgment and of the magnitudes, where is the maximum torque value that the retarder can provide, and this value is pre-measured through experiments and stored in the retarder torque control system.

[0036] If then ; If , then , where: (1); Among them, is the target braking torque value of the retarder, is the maximum output torque value of the retarder, is the processed target braking torque value of the retarder, is the current working pressure of the retarder working chamber, is the maximum pressure value of the retarder working chamber, is the retarder oil filling characteristic time constant, is time.

[0037] Step 2: Calculate the target working pressure value of the retarder; The target working pressure value of the retarder is calculated based on the target torque command signal received by the system, specifically: 1) Establish a retarder braking torque database as shown in Figure 3 . According to the conditions of oil temperature, driving wheel speed, and filling rate, the retarder braking torque database can output the maximum output torque value under the current conditions .

[0038] 2) Convert the target torque value calculated in step 1 into the target working pressure value of the retarder according to the oil temperature information and driving wheel speed information obtained by the current sensor . The filling rate input value is 100%.

[0039] ) (2); Among them, is the target working pressure value of the retarder, is the maximum output torque value under the current conditions.

[0040] Step 3: Calculate the control input of the retarder proportional valve; In view of the problems of large output torque fluctuations and long time to reach the steady-state target torque value caused by over-control in the present invention, a method of using the solenoid valve feedback current value as an additional control input parameter is adopted to solve the problem. First, test and obtain the relationship between the solenoid valve control current and the oil supply pressure. When the retarder is working, according to the magnitude of the target pressure and the actual pressure deviation value, determine the calculation method for calculating the control input value of the proportional solenoid valve by the PID controller. When the pressure deviation value at time is greater than the preset pressure constant value , calculate the control input value of the proportional solenoid valve using calculation method 1. When the pressure deviation value at time is less than the preset pressure constant value , calculate the control input value of the proportional solenoid valve using calculation method 2, where calculation method 2 will include parameters such as the solenoid valve feedback current value and the relationship between the current and the oil supply pressure.

[0041] 1) Calculate the pressure deviation value according to the results obtained in steps 1 and 2: (3).

[0042] Calculate the control input of the proportional valve through the PID controller : (4); (5); Among them, is the current moment, are all PID controller parameters, is a preset pressure constant value, is the current deviation, is the rate of change of the pressure deviation.

[0043] such as Figure 2 shown, the current deviation is obtained through the following formula (6): (6); The target current value is obtained through the following formula (7): ) (7); wherein, is the current value obtained from the retarder sensor at the current moment, is the target current value, is the maximum input current of the retarder proportional valve, is a constant value obtained through pre-testing according to the pressure deviation range.

[0044] In addition, as Figure 2 shown, the transmission shaft 7 of the retarder 1 is connected to the output shaft of the transmission outside the system. The transmission shaft 7 drives the driving wheel of the retarder 1 to rotate. The driving wheel stirs the oil fluid and impacts on the fixed wheel of the retarder 1, and the deceleration requirement is achieved through the generated reaction force. The heat energy generated by stirring the oil fluid is dissipated through the heat dissipation device. The fuel tank 5 conducts the entire control path through the variable pump 3 input by connecting the drain valve 4. The magnitude of the braking torque generated by the retarder 1 is adjusted by adjusting the volume of the oil fluid in the cavity (filling rate). The filling rate is related to the pressure in the working cavity 6. Therefore, the magnitude of the braking torque generated by the retarder is adjusted by adjusting the working pressure in the working cavity 6. A higher working pressure results in a greater braking torque, and the adjustment of the working pressure is achieved by controlling the proportional valve 2 and the drain valve 4. Specifically: the controller closes the drain valve 4 through current control, and at the same time controls the opening degree of the oil supply port of the proportional valve 2 to adjust the oil supply pressure at the outlet of the variable pump 3, thereby achieving the adjustment of the filling rate of the cavity of the retarder 1. The larger the opening of the proportional valve 2, the higher the oil pressure at the outlet of the variable pump 3, the greater the working pressure of the retarder 1, and the greater the filling rate of the retarder 1. When it is necessary to quickly reduce the working pressure of the cavity 6, the oil pressure at the outlet of the variable pump 3 can be quickly reduced, and at the same time the drain valve 4 is opened to accelerate the discharge of the liquid in the cavity 6.

[0045] Control method for heavy truck hydraulic retarder of the present invention. Aiming at the problem of torque output delay, through the tests on the control characteristics of the proportional valve and the charging and discharging characteristics of the retarder, parameters such as the maximum pressure value during the operation of the retarder, the oil charging time of the retarder, and the working dead zone of the proportional valve are obtained. Compensate the control input amount corresponding to the control input dead zone of the proportional valve. When the retarder is working, if the target pressure value is less than the maximum target pressure value, compensate the control input during the valve opening stage of the proportional valve for the oil charging process, and the size of the oil charging process compensation value is adjusted according to the size of the target braking pressure, so as to achieve the effect of reducing the output torque delay.

[0046] Control method for heavy truck hydraulic retarder of the present invention. Aiming at the problem that the control accuracy is not high and the control effect varies greatly at different vehicle speeds and different retarder oil temperatures, a braking torque database of the retarder is obtained through experimental tests. The input of the braking torque database is the oil temperature of the retarder and the rotational speed of the retarder driving wheel, and the output of the database is the maximum output torque value. When the retarder is working, obtain the maximum output torque value by querying the database in real time, and calculate the target working pressure according to the maximum output torque value, so as to more accurately control the output torque of the retarder.

[0047] Finally, it should be noted that: the above description is only a preferred embodiment of the present invention, and does not impose any form of limitation on the present invention; any ordinary technician in the industry can smoothly implement the present invention according to the description in the specification and the above description. Any equivalent changes made by slightly modifying and evolving using the technical content disclosed above are equivalent embodiments of the present invention; at the same time, any equivalent changes, modifications and evolutions made to the above embodiments based on the essential technology of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A control method for a heavy truck hydraulic retarder, characterized in that: The steps include: S1, read the target braking torque value of the retarder; If the target braking torque value of the retarder is greater than or equal to the maximum output torque value of the retarder, the target braking torque value of the retarder is set to the maximum output torque value of the retarder to form a processed target braking torque value of the retarder; If the target braking torque value of the retarder is less than the maximum output torque value of the retarder, the target braking torque value is dynamically compensated to form a processed target braking torque value of the retarder; S2. Calculating a target working pressure value of the retarder chamber according to the processed target braking torque value of the retarder and the maximum output torque value of the retarder; S3. Calculate the deviation between the target working pressure value of the retarder chamber and the current working pressure of the retarder, and the deviation between the target current of the proportional valve and the actual current, calculate through a PID controller, and use the output of the PID controller as the input of the retarder proportional valve to control the output torque of the retarder.

2. The control method of the heavy truck hydraulic retarder according to claim 1, characterized in that: In S1, the target braking torque value is dynamically compensated as follows: if ,but ,in: （1）； in, is the target braking torque value of the retarder, is the maximum output torque value of the retarder, is the target braking torque value of the retarder after processing, is the current working pressure of the retarder working chamber, is the maximum pressure value of the retarder working chamber, is the time constant of the retarder oil filling characteristic, It's time.

3. The control method of the heavy truck hydraulic retarder according to claim 2, characterized in that: In said S1, during the control process, the current working pressure of the retarder working chamber is collected in real time.

4. The control method of the heavy truck hydraulic retarder according to claim 2, characterized in that: In the step S1 , the maximum pressure value of the retarder working chamber and the time constant of the retarder oil filling characteristic are measured in advance.

5. The control method of the heavy truck hydraulic retarder according to claim 1, characterized in that: In S2, the maximum output torque value of the retarder under the current condition is obtained according to the retarder braking torque database, the current oil temperature of the retarder and the driving wheel speed. Based on the maximum output torque value of the retarder under the current condition, the target working pressure value of the retarder is calculated by the following formula (2): )（2）； in, is the target working pressure value of the retarder, It is the maximum output torque value under current conditions.

6. The control method of the heavy truck hydraulic retarder according to claim 1, characterized in that: In S3, the deviation between the target working pressure value of the retarder chamber and the current working pressure of the retarder is calculated using the following formula (3): （3）。 7. The control method of the heavy truck hydraulic retarder according to claim 1, characterized in that: In S3, the PID controller calculates the control input of the proportional valve by the following formula (4): （4）； （5）； in, is the control input of the proportional valve, For the current moment, These are the PID controller parameters. is the preset pressure constant value, is the deviation between the proportional valve target current and the actual current, is the pressure deviation change rate.

8. The control method of the heavy truck hydraulic retarder according to claim 1, characterized in that: In S3, the deviation between the proportional valve target current and the actual current is obtained by the following formula (6): （6）； The target current value is obtained by the following formula (7): )（7）； in, is the current value obtained from the retarder sensor at the current moment, is the target current value, is the maximum input current of the retarder proportional valve, It is a constant value obtained by pre-testing based on the pressure deviation range.

9. A control system for a heavy truck hydraulic retarder, characterized in that: The control system is controlled by the control method of the heavy truck hydraulic retarder according to any one of claims 1 to 8, and the control system includes a data acquisition module, a target braking torque value processing module, a pressure calculation module and a PID controller calculation module, wherein: Data acquisition module: used to collect the input current of the retarder proportional valve, the pressure in the retarder cavity, the speed of the retarder driving wheel and the retarder oil temperature in real time; Target braking torque value processing module: used to read the target braking torque value of the retarder; If the target braking torque value of the retarder is greater than or equal to the maximum output torque value of the retarder, the target braking torque value of the retarder is set to the maximum output torque value of the retarder to form a processed target braking torque value of the retarder; If the target braking torque value of the retarder is less than the maximum output torque value of the retarder, the target braking torque value is dynamically compensated to form a processed target braking torque value of the retarder; Pressure calculation module: used for calculating the target working pressure value of the retarder chamber according to the processed target braking torque value of the retarder and the maximum output torque value of the retarder; PID controller calculation module: calculates the deviation between the target working pressure value of the retarder chamber and the current working pressure of the retarder, and the deviation between the target current of the proportional valve and the actual current. Through the PID controller calculation, the output of the PID controller is used as the input of the retarder proportional valve to control the output torque of the retarder.

10. A vehicle, characterized in that: The vehicle includes the control system of the heavy truck hydraulic retarder according to claim 9.

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