Retarding braking method and device, vehicle control unit and vehicle

Abstract

The invention provides a retarding braking method and device, a vehicle control unit and a vehicle, and can be applied to the technical field of vehicle braking. The method comprises the steps that under the condition that it is determined that a vehicle enters a long downhill working condition, driving data of the vehicle are collected; determining a required braking force required by the vehicle based on the driving data; based on the battery SOC of the vehicle, a corresponding retarding braking strategy is determined and executed; wherein the retarding braking strategy is used for distributing respective target braking force of an electric driving system and a hydraulic retarding system in the vehicle, so that the braking force output by the vehicle is consistent with the required braking force. The corresponding retarding braking strategy is executed according to the SOC condition of the battery of the vehicle, the braking force of the electric driving system and the braking force of the hydraulic retarding system in the vehicle are dynamically distributed, and the energy recovery efficiency and the braking safety performance of the vehicle are both considered.

Description

Technical Field

[0001] The present application relates to the technical field of vehicle braking, and particularly to a retarder braking method, device, vehicle controller and vehicle. Background Art

[0002] The current service braking system of automobiles mainly adopts a friction-based mechanical braking system. In areas with many long downhill slopes, under the working conditions of frequent or continuous braking on long downhill slopes, the temperature of the mechanical braking system will rise significantly, and the thermal load is large. This will cause the friction coefficient of the friction pair of the mechanical braking system to decrease to a small value, resulting in braking failure and then easily causing traffic accidents.

[0003] For new energy vehicles, long downhill slopes are beneficial to the energy recovery of the new energy system. Therefore, new energy vehicles can use the braking force generated by the electric drive system during energy recovery to assist vehicle braking. However, during the energy recovery process, the State of Charge (SOC) value of the vehicle's battery cannot be too high, otherwise the battery is prone to overheating and damage, thus affecting the battery life and safety.

[0004] The existing retarder braking methods for vehicles are to switch different braking modes under different working conditions. For example, the mechanical braking system is used for braking at low speeds, the auxiliary braking device is used for auxiliary braking at medium speeds, and the energy recovery braking of the electric drive system is used at high speeds. Although this braking mode is simple, it cannot take into account both the energy recovery efficiency and braking safety performance of the vehicle. Summary of the Invention

[0005] The present application provides a retarder braking method, device, vehicle controller and vehicle, aiming to solve the technical problem that existing new energy vehicles cannot take into account both the energy recovery efficiency and braking safety performance during the retarder braking process.

[0006] According to the first aspect disclosed in the present application, the present application provides a retarder braking method, including:

[0007] When it is determined that the vehicle enters the long downhill working condition, collect the driving data of the vehicle;

[0008] Based on the driving data, determine the required braking force of the vehicle;

[0009] Based on the battery SOC of the vehicle, determine and execute the corresponding retarder braking strategy; wherein, the retarder braking strategy is used to allocate the target braking forces of the electric drive system and the hydraulic retarder system in the vehicle respectively, so that the braking force output by the vehicle is consistent with the required braking force.

[0010] In a feasible implementation, based on the battery SOC of the vehicle, a corresponding retarder braking strategy is determined and executed, including:

[0011] If the battery SOC is less than the first preset SOC threshold, a primary retarder braking strategy is executed; wherein, the primary retarder braking strategy uses only the electric drive system for braking;

[0012] If the battery SOC is greater than the first preset SOC threshold and less than the second preset SOC threshold, a secondary retarder braking strategy is executed; wherein, the secondary retarder braking strategy combines the electric drive system and the hydraulic retarder system for compound braking;

[0013] If the battery SOC is greater than the second preset SOC threshold, a tertiary retarder braking strategy is executed; wherein, the tertiary retarder braking strategy uses only the hydraulic retarder system for braking.

[0014] In a feasible implementation, the secondary retarder braking strategy combines the electric drive system and the hydraulic retarder system for compound braking, including:

[0015] Based on the battery SOC, the required braking force, and the current vehicle speed, a preset fuzzy controller is introduced to obtain an energy recovery priority coefficient;

[0016] Based on the energy recovery priority coefficient, the required braking force, and the maximum braking force of the electric drive system, the target braking force of the electric drive system is obtained;

[0017] Based on the current vehicle speed and the oil temperature and working gear of the hydraulic retarder system, a preset dynamic compensation mechanism is introduced to obtain a dynamic compensation coefficient;

[0018] Based on the dynamic compensation coefficient, the maximum braking force of the hydraulic retarder, and the difference between the required braking force and the target braking force of the electric drive system, the target braking force of the hydraulic retarder is obtained.

[0019] In a feasible implementation, the secondary retarder braking strategy combines the electric drive system and the hydraulic retarder system for compound braking, including:

[0020] Obtain the current gear of the transmission in the electric drive system and the slope data of the long downhill condition;

[0021] Based on the current gear and the slope data, query a pre-configured braking force ratio distribution table to obtain the braking ratios of the electric drive system and the hydraulic retarder system respectively; wherein, the braking force ratio distribution table is used to indicate the corresponding braking ratios of the electric drive system and the hydraulic retarder system under different current gears and different slope data conditions; the braking ratio is the ratio of the target braking force allocated to the electric drive system or the hydraulic retarder system to the required braking force;

[0022] Based on the braking ratios of the electric drive system and the hydraulic retarder system respectively, determine the target braking forces of the electric drive system and the hydraulic retarder system respectively.

[0023] In a feasible implementation manner, the three-stage retarder braking strategy uses the hydraulic retarder system alone for braking, including:

[0024] Obtain the current vehicle speed of the vehicle and the slope data of the long downhill working condition;

[0025] Based on the current vehicle speed and the slope data, query a pre-configured retarder gear allocation table to obtain the working gear of the hydraulic retarder system; wherein, the retarder gear allocation table is used to indicate the working gear corresponding to the hydraulic retarder system under different current vehicle speeds and different slope data conditions.

[0026] In a feasible implementation manner, the method further includes:

[0027] Based on a pre-configured oil temperature prediction model, obtain the oil temperature of the hydraulic retarder system;

[0028] If the oil temperature is greater than a first preset temperature threshold, limit the target braking force allocation of the hydraulic retarder system and start the thermal management resources of the electric drive system for forced heat dissipation.

[0029] In a feasible implementation manner, the method further includes:

[0030] Obtain the cooling water inlet temperature of the electric drive system;

[0031] If the cooling water inlet temperature is greater than a second preset temperature threshold, stop the target braking force allocation of the electric drive system.

[0032] According to the second aspect disclosed in the present application, the present application provides a vehicle retarder braking device, which is applied to the vehicle's vehicle controller. The vehicle includes an electric drive system, a hydraulic retarder system and a mechanical braking system, and includes:

[0033] A data acquisition module, configured to collect the vehicle data of the vehicle when it is determined that the vehicle is in a long downhill working condition;

[0034] A braking force acquisition module, configured to determine a required braking force of the vehicle based on the vehicle data;

[0035] A strategy execution module, configured to determine and execute a corresponding regenerative braking strategy based on the battery SOC of the vehicle; wherein, the regenerative braking strategy is used to allocate respective target braking forces of an electric drive system and a hydrodynamic retarder system in the vehicle, so that the braking force output by the vehicle is consistent with the required braking force.

[0036] According to a third aspect disclosed in the present application, the present application provides a vehicle controller, including a processor and a memory communicatively connected to the processor;

[0037] The memory stores computer-executable instructions;

[0038] The processor executes the computer-executable instructions stored in the memory to implement the method according to any one of the first aspect.

[0039] According to a fourth aspect disclosed in the present application, the present application provides a computer-readable storage medium, in which computer-executable instructions are stored, and when the computer-executable instructions are executed, they are used to implement the method according to any one of the first aspect.

[0040] According to a fifth aspect disclosed in the present application, the present application provides a computer program product, including a computer program, and when the computer program is executed, it is used to implement the method according to any one of the first aspect.

[0041] According to a sixth aspect disclosed in the present application, the present application provides a vehicle, which includes the vehicle controller according to the third aspect, and an electric drive system, a hydrodynamic retarder system and a mechanical braking system.

[0042] Compared with the prior art, the present application has the following beneficial effects:

[0043] A regenerative braking method, device, vehicle controller and vehicle provided by the present application confirm and execute a corresponding regenerative braking strategy according to the battery SOC of the vehicle, and dynamically allocate the braking forces of the electric drive system and the hydrodynamic retarder system in the vehicle respectively, so as to meet the braking force requirement of the vehicle. On the premise of ensuring the safety of the battery, it can not only ensure that the vehicle has sufficient braking force to achieve regenerative braking under long downhill conditions, ensuring the braking safety performance of the vehicle, but also make full use of the energy recovery function of the electric drive system, improving the energy recovery efficiency of the vehicle. Description of the Drawings

[0044] The accompanying drawings here are incorporated into the specification and form a part of this specification, showing the embodiments consistent with this application, and are used together with the specification to explain the principles of this application.

[0045] Figure 1 Schematic diagram of a connection structure between a motor and a hydraulic retarder provided for an embodiment of this application;

[0046] Figure 2 Schematic flow chart of a retarder braking method provided for an embodiment of this application;

[0047] Figure 3 Schematic flow chart of another retarder braking method provided for an embodiment of this application;

[0048] Figure 4 Schematic diagram of a structure of a retarder braking device provided for an embodiment of this application;

[0049] Figure 5 Schematic diagram of a structure of a vehicle controller provided for an embodiment of this application.

[0050] Through the above accompanying drawings, the clear embodiments of this application have been shown, and there will be more detailed descriptions hereinafter. These drawings and textual descriptions are not intended to limit the scope of the concept of this application in any way, but to illustrate the concept of this application to those skilled in the art by referring to specific embodiments. Detailed implementation manners

[0051] Here, the exemplary embodiments will be described in detail, and the examples are shown in the accompanying drawings. When the following description refers to the accompanying drawings, unless otherwise indicated, the same numerals in different drawings represent the same or similar elements. The implementation manners described in the following exemplary embodiments do not represent all implementation manners consistent with this application. On the contrary, they are merely examples of devices and methods consistent with some aspects of this application as detailed in the appended claims.

[0052] The current vehicle service braking system mainly adopts a friction-type mechanical braking system. In areas with many long downhill slopes, under the working conditions of frequent braking or continuous braking on long downhill slopes, the temperature of the mechanical braking system will rise significantly, and the thermal load is relatively large. This will cause the friction coefficient of the friction pair of the mechanical braking system to decrease to a relatively small value, resulting in braking failure and thus prone to traffic accidents.

[0053] For new energy vehicles, a long downhill is beneficial to the energy recovery of the new energy system. Therefore, new energy vehicles can use the braking force generated by the electric drive system during energy recovery to assist vehicle braking. However, during the energy recovery process, the State of Charge (SOC) value of the vehicle's battery (which represents the percentage of the current remaining battery capacity to its rated capacity) cannot be too high, otherwise the battery is prone to overheating and damage, thus affecting the battery life and safety.

[0054] The existing vehicle retarder braking method is to switch different braking modes under different working conditions. For example, mechanical braking system is used for braking at low speed, auxiliary braking device is used for auxiliary braking at medium speed, and energy recovery braking of the electric drive system is used at high speed. Although this braking mode is simple, it cannot balance the energy recovery efficiency and braking safety performance of the vehicle.

[0055] In view of the above technical problems, the present application proposes a retarder braking method, device, vehicle integrated controller and vehicle. By executing corresponding retarder braking strategies according to the SOC of the vehicle's battery, the braking forces of the electric drive system and the hydraulic retarder system in the vehicle are dynamically allocated, taking into account both the energy recovery efficiency and braking safety performance of the vehicle.

[0056] The following uses specific embodiments to elaborate in detail on the technical solutions of the retarder braking method provided by the present application. It should be noted that the following embodiments can exist independently or be combined with each other. For the same or similar content, it may not be repeated in different embodiments.

[0057] It should be noted that the execution subject of the retarder braking method provided by the embodiments of the present application is the vehicle integrated controller of the vehicle. Correspondingly, the vehicle retarder braking device is also provided in the vehicle integrated controller.

[0058] Specifically, the vehicle integrated controller is the core control unit of an electric vehicle, responsible for coordinating and managing the vehicle's power system, energy management system, and each electronic control unit (ECU). By receiving the driver's operation instructions and the vehicle's real-time status information, it precisely controls key components such as the motor, battery, and braking system to achieve functions such as vehicle driving, braking, and energy recovery.

[0059] Specifically, in addition to the vehicle integrated controller, the vehicle also includes an electric drive system, a hydraulic retarder system, and a mechanical braking system.

[0060] Among them, the electric drive system includes a battery, a DC-DC converter DCDC, a high-voltage distribution box, a motor controller MCU, a transmission controller TCU, a motor, a transmission, an electric drive cooling system, a drive shaft, an axle, tires, etc. connected in series in sequence to form a loop to achieve vehicle driving and energy recovery.

[0061] Among them, the hydraulic retarder system includes a hydraulic retarder, a hydraulic retarder cooling system, a retarder controller RCU, etc. Specifically, the circuit of the hydraulic retarder cooling system is independent of the circuit of the electric drive cooling system and does not affect the cooling capacity of the electric drive system.

[0062] Refer to Figure 1 , specifically, the motor 101 is connected to the transmission 102, and the hydraulic retarder 103 is connected in parallel to the output main shaft of the transmission 102 for assisting the vehicle in retarder braking.

[0063] Among them, in the prior art, generally, a scheme of matching an eddy current retarder for the motor for auxiliary braking is adopted. As a common auxiliary braking device, although the eddy current retarder performs excellently in improving vehicle braking safety and reducing the wear of the main brake, it also has significant disadvantages. For example, the braking force at low speeds is insufficient, and it is strongly dependent on the speed; the power demand is high, and there are potential electrical fault hazards; the strong electromagnetic field may affect in-vehicle electronic devices, and there is a potential risk of electromagnetic interference, etc.

[0064] Compared with the eddy current retarder, the hydraulic retarder has a good braking effect at low speeds, has a low power demand, and there is no risk of electromagnetic interference, and can effectively overcome the above problems of the eddy current retarder.

[0065] Specifically, the vehicle controller VCU communicates with each controller module such as the motor controller MCU, the transmission controller TCU, the retarder controller RCU, the battery management system BMS, and the brake system control unit through CAN communication, monitors and controls relevant signals for closed-loop control.

[0066] Among them, through vehicle CAN communication, sensor signals are collected and controlled in real time, including: brake pedal - braking signal, gear sensor - gear signal, battery BMS - SOC signal, central controller - temperature sensor signal, motor controller - braking energy recovery, hydraulic retarder - proportional valve control signal, vehicle speed sensor - vehicle speed signal, slope sensor - slope signal, etc., so as to realize the coordinated control of each system.

[0067] Figure 2 It is a schematic flow chart of a retarder braking method provided by an embodiment of the present application. Refer to Figure 2 , in some embodiments, this retarder braking method is applied to the vehicle controller of a vehicle. The vehicle includes an electric drive system, a hydraulic retarder system, and a mechanical braking system, and its process includes the following steps:

[0068] S201, when it is determined that the vehicle enters a long downhill working condition, collect the driving data of the vehicle.

[0069] Among them, the vehicle detects the slope signal according to the slope sensor. When the slope sensor feedback indicates that the slope remains large for a long time, it is determined that the vehicle enters the long downhill working condition. The whole vehicle receives the long downhill braking force demand. The sensor data collects signals such as vehicle speed, slope, battery SOC, water temperature, gear, throttle, and brake, and obtains relevant vehicle driving data.

[0070] S202. Based on the driving data, determine the required braking force of the vehicle.

[0071] Among them, according to the relevant vehicle driving data, further determine the required braking force of the vehicle.

[0072] Specifically, to keep the vehicle at a constant speed when going downhill, the resultant force on the vehicle needs to be zero, that is, the braking force should balance the component of the gravity along the inclined plane when the vehicle is going downhill. When the vehicle is going downhill, the gravity can be decomposed into a component perpendicular to the inclined plane and a component along the inclined plane downward. The component along the inclined plane downward will cause the vehicle to have an accelerating trend. To keep the vehicle speed constant, the braking system needs to generate a braking force equal in magnitude and opposite in direction to this component. When specifically calculating, first calculate the magnitude of the component of the gravity along the inclined plane according to the vehicle mass and the downhill slope angle using the gravity decomposition formula. This magnitude of the component is the theoretical value of the braking force required to maintain a constant speed. In practice, other factors such as rolling resistance and air resistance that affect the vehicle's motion also need to be considered. Therefore, by combining the vehicle's driving data, accurately calculating this component and adjusting according to the actual situation, the magnitude of the braking force required to keep the vehicle at a constant speed when going downhill can be determined.

[0073] S203. Based on the battery SOC of the vehicle, determine and execute the corresponding retarder braking strategy; among them, the retarder braking strategy is used to allocate the respective target braking forces of the electric drive system and the hydraulic retarder system in the vehicle, so that the braking force output by the vehicle is consistent with the required braking force.

[0074] Among them, according to the battery SOC situation of the vehicle, confirm and execute the corresponding retarder braking strategy, so as to dynamically allocate the respective target braking forces of the electric drive system and the hydraulic retarder system in the vehicle to meet the braking force demand of the vehicle.

[0075] In this embodiment, by confirming and executing the corresponding retarder braking strategy according to the battery SOC situation of the vehicle, the braking forces of the electric drive system and the hydraulic retarder system in the vehicle are dynamically allocated to meet the braking force demand of the vehicle. On the premise of ensuring battery safety, it not only ensures that the vehicle has sufficient braking force to achieve retarder braking in the long downhill working condition, ensuring the braking safety performance of the vehicle, but also can make full use of the energy recovery function of the electric drive system, improving the energy recovery efficiency of the vehicle.

[0076] In addition, through the combined braking of the hydraulic retarder system and the electric drive system, the use of the mechanical braking system can be minimized, the wear of the braking components in the mechanical braking system can be reduced, and the service life of the mechanical braking system can be extended.

[0077] Based on the Figure 2 embodiment shown below, in combination with Figure 3 , the technical solution of the above-mentioned retarder braking method will be further introduced.

[0078] Figure 3 FIG. Figure 3 is a schematic flow chart of another retarder braking method provided by an embodiment of the present application. Referring to

[0079] In some embodiments, the process of the retarder braking method includes the following steps:

[0080] S301, when it is determined that the vehicle enters a long downhill condition, collect the driving data of the vehicle.

[0081] S302, based on the driving data, determine the required braking force of the vehicle.

[0082] S303, if the battery SOC is less than the first preset SOC threshold, execute a primary retarder braking strategy; wherein, the primary retarder braking strategy uses only the electric drive system for braking.

[0083] Specifically, the first preset SOC threshold is 30%.

[0084] Optionally, when executing the primary retarder braking strategy, if the maximum braking force of the electric drive system is less than the required braking force, on the basis of the electric drive system outputting the maximum braking force, use the mechanical braking system in the vehicle to compensate for the difference in braking force between the required braking force and the maximum braking force of the electric drive system.

[0085] Among them, when executing the primary retarder braking strategy, if there is a special situation where the maximum braking force of the electric drive system is less than the required braking force of the vehicle, that is, relying solely on the electric drive system cannot meet the braking requirements of the vehicle. At this time, on the basis of the electric drive system outputting the maximum braking force, use the mechanical braking system of the vehicle to compensate for the difference in braking force of the electric drive system. Among them, the magnitude of the difference in braking force is the difference between the required braking force and the maximum driving force of the electric drive system.

[0086] S304, if the battery SOC is greater than the first preset SOC threshold and less than the second preset SOC threshold, then execute the secondary retardation braking strategy; wherein, the secondary retardation braking strategy combines the electric drive system and the hydraulic retarder system for composite braking.

[0087] Among them, when the battery SOC is between the first preset SOC threshold and the second preset SOC threshold, there may be an overcharge risk for the battery at this time. The electric drive system and the hydraulic retarder system can be combined for braking to meet the braking requirements of the vehicle while taking into account the energy recovery efficiency.

[0088] Specifically, the second preset SOC threshold is 80%.

[0089] Optionally, the secondary retardation braking strategy combines the electric drive system and the hydraulic retarder system for composite braking, which specifically includes:

[0090] Step 1, based on the battery SOC, the required braking force, and the current vehicle speed, introduce a preset fuzzy controller to obtain the energy recovery priority coefficient.

[0091] Specifically, the fuzzy controller is a control algorithm based on fuzzy logic. It can handle uncertainty and ambiguity and is suitable for systems that are difficult to describe with precise mathematical models. In the vehicle's energy recovery system, the fuzzy controller can dynamically adjust the control strategy according to the fuzzy description of the vehicle's real-time state (such as vehicle speed, battery SOC, braking force demand, etc.).

[0092] Specifically, the control rules of the fuzzy controller can be based on expert experience or the experience of operators. By simulating the human reasoning and decision-making process, the expert experience or the experience rules of operators are regularized to achieve effective control of complex, nonlinear, or difficult-to-precisely-model systems.

[0093] Specifically, the energy recovery priority coefficient K (0 ≤ K ≤ 1).

[0094] Step 2, based on the energy recovery priority coefficient, the required braking force, and the maximum braking force of the electric drive system, obtain the target braking force of the electric drive system.

[0095] Specifically, the target braking force F of the electric drive system motor = min(K * F total , F total_max ), where F total represents the required braking force, and F total_max represents the maximum braking force of the electric drive system.

[0096] The target braking force of the electric drive system takes the smaller value of K * F total and the maximum braking force F of the motor motor_maxthe smaller value, the core purpose is to ensure that the allocated braking force does not exceed the physical limit of the electric drive system.

[0097] Step 3: Based on the current vehicle speed, the oil temperature, and the working gear of the hydraulic retarder system, introduce a preset dynamic compensation mechanism to obtain a dynamic compensation coefficient.

[0098] Among them, the dynamic compensation mechanism is a mechanism that automatically adjusts the compensation amount according to the system operating state, external environment changes, or other relevant factors to maintain system stability, optimize performance, or achieve specific goals. Based on the current vehicle speed, the oil temperature, and the working gear of the hydraulic retarder system, introduce a preset dynamic compensation mechanism to obtain a dynamic compensation coefficient. For example, when the temperature is high, reduce α to avoid overheating of the hydraulic retarder; when the vehicle speed is high, increase α to make full use of the high-efficiency braking range of the retarder, so as to achieve a balance between safety and efficiency through the dynamic compensation mechanism.

[0099] Specifically, the dynamic compensation coefficient α (0 ≤ α ≤ 1). When α = 1, the hydraulic retarder system fully compensates the remaining braking force (within the premise of not exceeding its own upper limit); when α = 0, the hydraulic retarder system does not participate in the compensation, and the remaining braking force is borne by the mechanical braking system.

[0100] Specifically, the dynamic compensation mechanism can be pre-constructed based on the mapping relationship between the current vehicle speed, the oil temperature, and the working gear of the hydraulic retarder system and the dynamic compensation coefficient, so as to obtain the corresponding dynamic compensation coefficient based on the current vehicle speed, the oil temperature, and the working gear of the hydraulic retarder system.

[0101] Step 4: Based on the dynamic compensation coefficient and the difference between the required braking force and the target braking force of the electric drive system, obtain the target braking force of the hydraulic retarder system.

[0102] Specifically, the target braking force F of the hydraulic retarder retarder = min(α * (F total - F motor ), F retarder_max ). Among them, F retarder_max represents the maximum braking force of the hydraulic retarder system.

[0103] The target braking force of the hydraulic retarder system takes the smaller value of (α * (F total - F motor ) and the maximum braking force F of the retarder retarder_max to ensure that the output of the hydraulic retarder system does not exceed its rated capacity (heat dissipation limit, upper limit of hydraulic system pressure) and avoid overload.

[0104] Optionally, when implementing the secondary retard braking strategy, it is also possible to dynamically adjust the energy recovery priority coefficient K and the dynamic compensation coefficient α by monitoring whether the actual braking force output by the vehicle is consistent with the required braking force, so as to achieve an optimal solution combination that satisfies both the braking demand and energy recovery.

[0105] Specifically, the actual braking force of the vehicle is the braking force output by the electric drive system, the hydraulic retarder system, and the mechanical braking system converted to the braking force of the vehicle tires.

[0106] Optionally, when implementing the secondary retard braking strategy, if the sum of the target braking forces of the electric drive system and the hydraulic retarder system is less than the required braking force, the mechanical braking system in the vehicle is used to compensate for the difference in braking force between the required braking force and the target braking forces of the electric drive system and the hydraulic retarder system.

[0107] Among them, when implementing the secondary retard braking strategy, if the target braking forces allocated to the electric drive system and the hydraulic retarder system are less than the required braking force of the vehicle, the difference is made up by the mechanical braking system of the vehicle. Through the braking force compensation mechanism of the mechanical braking system, the braking force requirement of the vehicle is met.

[0108] Specifically, the braking force of the mechanical braking system is F brake =F total -F retarder -F motor .

[0109] Optionally, the secondary retard braking strategy combination uses the electric drive system and the hydraulic retarder system for compound braking, which specifically includes:

[0110] Step 1: Obtain the current gear of the transmission in the electric drive system and the slope data of the long downhill condition.

[0111] Step 2: Based on the current gear and slope data, query the pre-configured braking force ratio distribution table to obtain the respective braking force ratios of the electric drive system and the hydraulic retarder system; among them, the braking force ratio distribution table is used to indicate the respective corresponding braking force ratios of the electric drive system and the hydraulic retarder system under different current gear and different slope data conditions; the braking force ratio is the ratio of the target braking force allocated to the electric drive system or the hydraulic retarder system to the required braking force.

[0112] Among them, the influence of different gears of the gearbox on the braking force is considered. When in low gear, the motor may provide greater braking force, while in high gear, the hydraulic retarder is more effective. Therefore, it is necessary to adjust the braking force distribution by combining the gear information. The proportion of the target braking force of the electric drive system in the required braking force and the proportion of the target braking force of the hydraulic retarder system in the required braking force are pre-configured according to different gears and different slopes, so as to obtain a braking force proportion distribution table, which is convenient to query the corresponding braking proportions of the electric drive system and the hydraulic retarder system in the braking force proportion distribution table according to the current gear and slope data of the vehicle.

[0113] Specifically, a partial example of the braking force proportion distribution table is shown in Table 1.

[0114] Table 1 Schematic diagram of braking force proportion distribution

[0115] Gear position Gradient (%) Proportion of electric braking (%) Proportion of hydrodynamic retarder (%) First gear 10 80％ 20％ Second gear 10-20 70％ 30％ Third gear 20-30 50％ 50％ Fourth gear 30 30％ 70％

[0116] Specifically, it is the ratio of the vertical height to the horizontal width of the slope surface, that is, the tangent value of the slope angle.

[0117] Specifically, the braking force proportion distribution table is stored using a MAP database.

[0118] Step 3: Determine the target braking forces of the electric drive system and the hydraulic retarder system respectively based on their respective braking proportions.

[0119] Among them, after obtaining the respective braking proportions of the electric drive system and the hydraulic retarder system, combining the braking proportions with the required braking force can obtain the target braking forces of the electric drive system and the hydraulic retarder system respectively, realizing the distribution of the target braking forces of the electric drive system and the hydraulic retarder system.

[0120] Optionally, in the case of executing the secondary retardation braking strategy, if the target braking force of the electric drive system is greater than the maximum braking force of the electric drive system, obtain the first braking force difference between the target braking force of the electric drive system and the maximum braking force of the electric drive system;

[0121] If the target braking force of the hydraulic retarder is greater than the maximum braking force of the hydraulic retarder, obtain the second braking force difference between the target braking force of the hydraulic retarder and the maximum braking force of the hydraulic retarder;

[0122] On the basis of the electric drive system and the hydraulic retarder system outputting the maximum braking force, use the mechanical braking system in the vehicle to compensate for the first braking force difference and the second braking force difference.

[0123] Among them, when executing the secondary retardation braking strategy, if the target braking force allocated to the electric drive system is greater than the maximum braking force of the electric drive system, the first braking force difference lacking in the electric drive system is obtained. If the target braking force allocated to the hydraulic retarder system is greater than the maximum braking force of the hydraulic retarder, the second braking force lacking in the hydraulic retarder system is obtained. At this time, on the basis of the electric drive system and the hydraulic retarder system outputting the maximum braking force, the mechanical braking system in the vehicle is used to compensate for the first braking force difference and the second braking force difference.

[0124] Through the above braking force compensation mechanism, the braking force requirement of the vehicle can be satisfied, and the electric drive system and the hydraulic retarder system can be prevented from exceeding their own maximum physical limits, avoiding overload failures of the electric drive system and the hydraulic retarder system.

[0125] Specifically, assume that the braking force required by the vehicle is F total , the maximum braking force of the electric drive system is F motor_max , the maximum braking force of the hydraulic retarder system is F retarder_max , and the braking force of the mechanical braking system is F brake . The braking proportion allocated to the electric drive system is a, and the braking proportion allocated to the hydraulic retarder system is b. Among them, the value ranges of a and b are [0, 1].

[0126] Then the target braking force of the electric drive system is F motor = a * F total , and the target braking force F of the hydraulic retarder system retarder = b * F total .

[0127] Then when F motor > F motor_max , the braking force that the electric drive system cannot provide is compensated by the hydraulic retarder system or the mechanical braking system.

[0128] Then when F retarder > F retarder_max , the braking force that the hydraulic retarder system cannot provide is compensated by the mechanical braking system.

[0129] Then there are three cases for the magnitude of the braking force of the mechanical braking system. When the electric drive system brakes alone, F brake = F total - F motor ; when the electric drive system and the hydraulic retarder system brake in combination, F brake = F total - F retarder - F motor ; when the hydraulic retarder system brakes alone, F brake = F total - F retarder .

[0130] S305, if the battery SOC is greater than the second preset SOC threshold, then execute the three - level retarder braking strategy; among them, the three - level retarder braking strategy uses the hydraulic retarder system for braking alone.

[0131] Among them, when the battery SOC is greater than the second preset SOC threshold, it indicates that the battery power is too high. At this time, the battery has a risk of overcharging. To ensure vehicle safety, the braking force is no longer allocated to the electric drive system at this time, that is, the energy recovery of the electric drive system is stopped, avoiding the risk of overcharging the battery, and using the hydraulic retarder system for braking alone.

[0132] Optionally, the three - level retarder braking strategy using the hydraulic retarder system for braking alone specifically includes:

[0133] Step 1, obtain the current vehicle speed and the slope data of the long downhill condition.

[0134] Step 2, based on the current vehicle speed and slope data, query the pre - configured retarder gear allocation table to obtain the working gear of the hydraulic retarder system; among them, the retarder gear allocation table is used to indicate the corresponding working gear of the hydraulic retarder system under different current vehicle speeds and different slope data conditions.

[0135] Among them, the working gears of the hydraulic retarder system are pre - configured according to different vehicle speeds and different slopes, so as to obtain the retarder gear allocation table, which is convenient to query the corresponding working gear of the hydraulic retarder system in the retarder gear allocation table according to the current vehicle speed and slope data of the vehicle.

[0136] After determining the working gear of the hydraulic retarder system, at this working gear, allocate all the required braking force to the hydraulic retarder system to use the hydraulic retarder system for braking alone.

[0137] Specifically, the hydraulic retarder system includes a closed 0 - gear, a constant - speed 1 - gear, and 2 - 5 gears for braking.

[0138] Among them, the 0 - gear is a closed gear, the constant - speed 1 - gear is used to maintain a constant vehicle speed on long downhill sections, and the 2 - 5 gears are used for short - distance deceleration or long - downhill assisted braking, and the braking force increases with the gear. The 2 - 3 gears are suitable for general deceleration requirements, with a mild braking force that can be gradually increased; the 4 - 5 gears have a strong braking force, but long - term use is likely to cause the engine to overheat and is only limited to short - time emergency braking.

[0139] Optionally, in the case of executing the three - level retarder braking strategy, if the maximum braking force of the hydraulic retarder system is less than the required braking force, then on the basis of the maximum braking force output of the hydraulic retarder system, use the mechanical braking system in the vehicle to compensate for the difference in braking force between the required braking force and the maximum braking force of the hydraulic retarder system.

[0140] Among them, when implementing the primary retardation braking strategy, if a special situation occurs where the maximum braking force of the electric drive system is less than the required braking force of the vehicle, that is, the electric drive system alone cannot meet the braking requirements of the vehicle. At this time, on the basis of the electric drive system outputting the maximum braking force, the mechanical braking system of the vehicle is used to compensate for the difference in braking force of the electric drive system. Among them, the magnitude of the differential braking force is the difference between the required braking force and the maximum driving force of the electric drive system.

[0141] S206. Based on the pre-configured oil temperature prediction model, obtain the oil temperature of the hydrodynamic retarder system.

[0142] Among them, during the process of retardation braking, the hydrodynamic retarder may overheat after long-term operation. At the same time, it is necessary to monitor the oil temperature of the hydrodynamic retarder and adjust the braking force distribution to avoid overheating.

[0143] Specifically, the oil temperature prediction model of the hydrodynamic retarder satisfies the following formula:

[0144] T(t) = T0 + ∫(β * P retarder - γ * T) / C dt

[0145] Among them, T0 represents the predicted oil temperature of the hydrodynamic retarder system at time t (unit: °C).

[0146] Among them, T0 represents the initial oil temperature of the hydrodynamic retarder system (unit: °C).

[0147] Among them, P retarder represents the power of the hydrodynamic retarder (unit: W), which is related to the braking force and rotational speed of the hydrodynamic retarder.

[0148] Among them, β represents the heat generation coefficient of the hydrodynamic retarder, which represents the heat generated per unit power (unit: 1 / °C·s -1 ), and its physical meaning is the efficiency of converting mechanical energy into heat energy when the hydrodynamic retarder works, which is related to factors such as frictional loss and oil viscosity.

[0149] Among them, γ represents the heat dissipation coefficient of the hydrodynamic retarder system, which represents the heat dissipation rate driven by the temperature difference between the oil temperature and the ambient temperature (unit: 1 / s). Its physical meaning is the heat dissipation ability of the self-cooling system of the hydrodynamic retarder (such as radiator, fan, coolant circulation).

[0150] Among them, C represents the total heat capacity of the oil and the structure of the hydrodynamic retarder (unit: J / °C), which reflects the heat storage capacity of the hydrodynamic retarder system;

[0151] Among them, the integral term ∫(β * P retarder - γ * T) / C dt, β * P retarder represents the heat generation rate when the hydrodynamic retarder system works, γ* T represents the heat dissipation rate of the system through its own cooling (related to the ambient temperature). (Heat generation rate - Heat dissipation rate) represents the net heat accumulation rate. Dividing by C means converting the heat accumulation into a temperature rise rate, and integration represents the result of the temperature accumulating over time.

[0152] Among them, through the oil temperature prediction model, the oil temperature of the hydraulic retarder is estimated in real time, avoiding reliance on physical sensors, thereby reducing the monitoring cost and improving the monitoring reliability. It is also possible to trigger the heat dissipation action in advance based on the prediction of the oil temperature prediction model (such as actively limiting the braking force of the hydraulic retarder system when T(t) approaches 95°C) to prevent overheating faults of the hydraulic retarder system.

[0153] S207, if the oil temperature is greater than the first preset temperature threshold, limit the target braking force distribution of the hydraulic retarder system, and start the thermal management resources of the electric drive system for forced heat dissipation.

[0154] Among them, the hydraulic retarder has an independent liquid cooling system (radiator, water pump, fan), and dissipates heat through circulating coolant or oil. When the hydraulic retarder works alone, it only relies on its own heat dissipation system to control the temperature (reflected by the γ*T term). The intervention condition for the increased braking ratio of the electric drive system, for example, automatically reduces the hydraulic braking ratio when T(t) > 100°C and increases the forced heat dissipation of the motor.

[0155] When the oil temperature exceeds the threshold (T(t) > 100°C), the system determines that the independent cooling capacity of the hydraulic retarder is insufficient. Reduce the braking ratio of the hydraulic retarder system, reduce or stop the braking force distribution of the hydraulic retarder, and directly reduce its heat generation power P retarder . Then use the thermal management resources of the motor system (such as electric water pump, electric fan, motor coolant circuit) to enhance heat dissipation. The electric water pump increases the coolant flow rate, and the electric fan forces convective heat dissipation to conduct forced heat dissipation on the hydraulic retarder system to prevent the hydraulic retarder system from overheating.

[0156] Optionally, when the oil temperature is greater than the first preset temperature threshold, an alarm can also be issued to remind the driver that the hydraulic retarder system is overheating.

[0157] S208, obtain the cooling water inlet temperature of the electric drive system.

[0158] Specifically, obtain the cooling water inlet temperature of the electric drive system through a temperature sensor.

[0159] S209, if the cooling water inlet temperature is greater than the second preset temperature threshold, stop the target braking force distribution of the electric drive system.

[0160] Among them, when the cooling inlet water temperature of the electric drive system is greater than the second preset temperature threshold, it indicates that the electric drive system is overheated. To ensure the safety of the electric drive system, the electric drive system is stopped at this time to perform a retardation brake.

[0161] Specifically, the second preset temperature threshold is 65 °C.

[0162] Optionally, when the cooling inlet water temperature is greater than the second preset temperature threshold, an alarm can also be issued to remind the driver that the electric drive system is overheated.

[0163] In this embodiment, when the vehicle enters a long downhill condition, the energy recovery function of the electric drive system is preferentially used for braking because it can be directly converted into electric energy with higher efficiency. However, when the motor cannot meet the braking demand, the auxiliary braking hydraulic retarder system is then turned on. Finally, if the braking force is still insufficient, the mechanical braking system is used for braking. At the same time, the SOC of the battery also affects the use of energy recovery. If the battery is almost full, it is necessary to reduce energy recovery and increase the use of other braking methods. By combining the braking of the mechanical braking system, the retardation braking of the hydraulic retarder system, and the energy recovery braking of the electric drive system, the three braking methods can be effectively integrated, improving the energy recovery efficiency and ensuring braking safety and stability at the same time.

[0164] Through multi-physical field coupling control, dynamic weight distribution, and deep system integration, the primary retardation braking strategy and the secondary retardation braking strategy are expected to increase the comprehensive braking efficiency by 22% and the energy recovery rate by 10%, which is especially suitable for the long downhill condition of heavy-duty electric commercial vehicles. The hydraulic retarder system avoids the risk of battery overcharging in the three-level retardation braking strategy and at the same time increases the emergency braking fault tolerance mechanism.

[0165] Figure 4 is a schematic structural diagram of a vehicle retardation braking device provided by an embodiment of the present application. Refer to Figure 4 , the vehicle retardation braking device includes various functional modules for implementing the foregoing retardation braking method, and any functional module can be implemented in software and / or hardware.

[0166] In some embodiments, the vehicle retardation braking device 400 is applied to the vehicle's vehicle controller. The vehicle includes an electric drive system, a hydraulic retarder system, and a mechanical braking system. The vehicle retardation braking device 400 includes a data acquisition module and a strategy execution module. Among them:

[0167] The data acquisition module 401 is used to collect vehicle data of the vehicle when it is determined that the vehicle is in a long downhill condition;

[0168] The braking force acquisition module 402 is used to determine the required braking force of the vehicle based on the vehicle data;

[0169] The policy execution module 403 is used to determine and execute a corresponding retardation braking policy based on the battery SOC of the vehicle; wherein, the retardation braking policy is used to allocate the target braking forces of the electric drive system and the hydraulic retarder system in the vehicle respectively, so that the braking force output by the vehicle is consistent with the required braking force.

[0170] In some embodiments, the policy execution module 403 is specifically configured to:

[0171] If the battery SOC is less than the first preset SOC threshold, execute a primary retardation braking policy; wherein, the primary retardation braking policy uses only the electric drive system for braking;

[0172] If the battery SOC is greater than the first preset SOC threshold and less than the second preset SOC threshold, execute a secondary retardation braking policy; wherein, the secondary retardation braking policy combines the electric drive system and the hydraulic retarder system for compound braking;

[0173] If the battery SOC is greater than the second preset SOC threshold, execute a tertiary retardation braking policy; wherein, the tertiary retardation braking policy uses only the hydraulic retarder system for braking.

[0174] In some embodiments, the policy execution module 403 is specifically configured to:

[0175] Based on the battery SOC, the required braking force, and the current vehicle speed, introduce a preset fuzzy controller to obtain an energy recovery priority coefficient;

[0176] Based on the energy recovery priority coefficient, the required braking force, and the maximum braking force of the electric drive system, obtain the target braking force of the electric drive system;

[0177] Based on the current vehicle speed, the oil temperature of the hydraulic retarder system, and the working gear, introduce a preset dynamic compensation mechanism to obtain a dynamic compensation coefficient;

[0178] Based on the dynamic compensation coefficient, the maximum braking force of the hydraulic retarder, and the difference between the required braking force and the target braking force of the electric drive system, obtain the target braking force of the hydraulic retarder.

[0179] In some embodiments, the policy execution module 403 is specifically configured to:

[0180] Obtain the current gear of the transmission in the electric drive system and the slope data of the long downhill working condition;

[0181] Based on the current gear position and slope data, query the pre-configured braking force ratio distribution table to obtain the braking force ratios of the electric drive system and the hydraulic retarder system respectively; wherein, the braking force ratio distribution table is used to indicate the corresponding braking force ratios of the electric drive system and the hydraulic retarder system under different current gear positions and different slope data conditions; the braking force ratio is the ratio of the target braking force allocated to the electric drive system or the hydraulic retarder system to the required braking force.

[0182] Based on the braking force ratios of the electric drive system and the hydraulic retarder system respectively, determine the target braking forces of the electric drive system and the hydraulic retarder system respectively.

[0183] In some embodiments, the policy execution module 403 is specifically configured to:

[0184] Obtain the current vehicle speed of the vehicle and the slope data of the long downhill working condition;

[0185] Based on the current vehicle speed and slope data, query the pre-configured retarder gear position distribution table to obtain the working gear position of the hydraulic retarder system; wherein, the retarder gear position distribution table is used to indicate the corresponding working gear position of the hydraulic retarder system under different current vehicle speeds and different slope data conditions.

[0186] In some embodiments, the policy execution module 403 is specifically further configured to:

[0187] Based on the pre-configured oil temperature prediction model, obtain the oil temperature of the hydraulic retarder system;

[0188] If the oil temperature is greater than the first preset temperature threshold, limit the allocation of the target braking force of the hydraulic retarder system and start the thermal management resources of the electric drive system for forced heat dissipation.

[0189] In some embodiments, the policy execution module 403 is specifically further configured to:

[0190] Obtain the cooling water inlet temperature of the electric drive system;

[0191] If the cooling water inlet temperature is greater than the second preset temperature threshold, stop the allocation of the target braking force of the electric drive system.

[0192] The vehicle retarder braking device 400 provided by the embodiments of the present application is used to execute the technical solutions provided by the foregoing embodiments of the retarder braking method, and its implementation principle and technical effects are similar to those in the foregoing embodiments of the method, and will not be elaborated here.

[0193] It should be noted that it should be understood that the division of each module of the above device is only a division of logical functions. In actual implementation, all or part of them can be integrated into a physical entity, or physically separated. And these modules can all be implemented in the form of software called by processing elements, or all in the form of hardware, or some modules can be implemented in the form of software called by processing elements and some modules in the form of hardware. For example, the data acquisition module 401 can be a separately established processing element, or can be integrated in a certain chip of the above device. In addition, it can also be stored in the memory of the above device in the form of program code, and the function of the above data acquisition module 401 can be called and executed by a certain processing element of the above device. The implementation of other modules is similar. In addition, all or part of these modules can be integrated together or can be independently implemented. Here, the processing element can be an integrated circuit with signal processing capabilities. In the implementation process, each step of the above method or each of the above modules can be completed by the integrated logic circuit in the processor element or the instruction in the form of software.

[0194] Figure 5 FIG. is a schematic structural diagram of a vehicle controller provided by an embodiment of the present application. Refer to Figure 5 As shown in, the vehicle controller 500 includes a processor 501 and a memory 502 communicatively connected to the processor 501;

[0195] The memory 502 stores computer-executable instructions;

[0196] The processor 501 executes the computer-executable instructions stored in the memory 502 to implement the technical solution of the aforementioned engine braking method.

[0197] In the above-mentioned vehicle controller 500, the memory 502 and the processor 501 are electrically connected directly or indirectly to achieve data transmission or interaction. For example, these components can be electrically connected to each other through one or more communication buses or signal lines, such as through a bus connection. The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, an Extended Industry Standard Architecture (EISA) bus, etc. The bus can be divided into an address bus, a data bus, a control bus, etc., but it does not mean that there is only one bus or one type of bus. The memory 502 stores computer execution instructions for implementing the aforementioned retarder braking method, including at least one software function module that can be stored in the memory 502 in the form of software or firmware. The processor 501 executes various functional applications and data processing by running the software programs and modules stored in the memory 502.

[0198] The memory 502 includes at least one type of readable storage medium, not limited to Random Access Memory (RAM), Read Only Memory (ROM), Programmable Read-Only Memory (PROM), Erasable Programmable Read-Only Memory (EPROM), Electric Erasable Programmable Read-Only Memory (EEPROM), etc. Among them, the memory 502 is used to store programs, and the processor 501 executes the programs after receiving the execution instructions. Further, the software programs and modules in the memory 502 may also include an operating system, which may include various software components and / or drivers for managing system tasks (such as memory management, storage device control, power management, etc.), and can communicate with various hardware or software components to provide a running environment for other software components.

[0199] The processor 501 may be an integrated circuit chip with the ability to process signals. The aforementioned processor 501 may be a general-purpose processor, including a Central Processing Unit (CPU), a Network Processor (NP), a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), etc. It can implement or execute the various methods, steps, and logic block diagrams disclosed in the embodiments of the present application. The general-purpose processor may be a microprocessor, or the processor 501 may also be any conventional processor, etc.

[0200] The vehicle controller 500 is used to execute the technical solution provided by the foregoing embodiment of the retarder braking method. Its implementation principle and technical effects are similar to those in the foregoing method embodiment, and will not be elaborated here.

[0201] The embodiments of the present application also provide a computer-readable storage medium. Computer-executable instructions are stored in the computer-readable storage medium. When the computer-executable instructions are executed, they are used to implement the technical solution of the foregoing retarder braking method.

[0202] The aforementioned computer-readable storage medium may be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as Static Random Access Memory (SRAM), Electrically Erasable Programmable Read-Only Memory (EEPROM), Erasable Programmable Read-Only Memory (EPROM), Programmable Read-Only Memory (PROM), Read-Only Memory (ROM), magnetic memory, flash memory, a magnetic disk, or an optical disk. The computer-readable storage medium may be any available medium accessible by a general-purpose or special-purpose computer.

[0203] An exemplary readable storage medium is coupled to the processor, enabling the processor to read information from the readable storage medium and write information to the readable storage medium. Of course, the readable storage medium may also be a component of the processor. The processor and the readable storage medium may be located in an Application Specific Integrated Circuit (ASIC). Of course, the processor and the readable storage medium may also exist as discrete components in the control device of the vehicle retarder braking device.

[0204] The embodiments of the present application also provide a computer program product, including a computer program. When the computer program is executed, it is used to implement the technical solution of the foregoing retarder braking method.

[0205] An embodiment of the present application further provides a vehicle, which includes the above-mentioned vehicle controller, as well as an electric drive system, a hydraulic retarder system, and a mechanical braking system.

[0206] In this embodiment, the vehicle includes an electric drive system, a hydraulic retarder system, and a mechanical braking system, as well as a vehicle controller that can execute the above-mentioned retarder braking method. Thus, corresponding retarder braking strategies can be executed according to the battery SOC condition of the vehicle, dynamically allocating the braking forces of the electric drive system and the hydraulic retarder system in the vehicle, taking into account both the energy recovery efficiency and the braking safety performance of the vehicle.

[0207] In the above embodiments, those skilled in the art can understand that implementing the above method embodiments can be achieved in whole or in part through software, hardware, firmware, or any combination thereof. When implemented using software, it can be achieved in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the processes or functions according to the embodiments of the present application are generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer instructions can be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from a website, computer, server, or data center to another website, computer, server, or data center in a wired manner (such as coaxial cable, optical fiber, digital subscriber line (DSL)) or wirelessly (such as infrared, wireless network, microwave, etc.). The computer-readable storage medium can be any available medium that the computer can access, or a data storage device such as a server or data center that includes one or more integrated available media. The available medium can be a magnetic medium (such as a floppy disk, hard disk, magnetic tape), an optical medium (such as a DVD), or a semiconductor medium (such as a solid state disk (SSD)).

[0208] In the above embodiments, the descriptions of the respective embodiments have their own focuses. For parts not detailed in a certain embodiment, reference can be made to the relevant descriptions of other embodiments. The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered to be within the scope described in this specification.

[0209] Those skilled in the art will readily conceive of other embodiments of the present application after considering the specification and practicing the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present application, which follow the general principles of the present application and include known common general knowledge or conventional technical means in the technical field not disclosed in the present application. The specification and examples are only regarded as exemplary, and the true scope and spirit of the present application are pointed out by the appended claims.

[0210] It should be understood that the present application is not limited to the exact structures described above and shown in the drawings, and various modifications and changes can be made without departing from its scope. The scope of the present application is only limited by the appended claims.

Claims

1. A slow braking method, characterized in that, A vehicle integrated controller applied to a vehicle, where the vehicle includes an electric drive system, a hydraulic retarder system, and a mechanical braking system, comprising: When it is determined that the vehicle enters a long downhill driving condition, collect the driving data of the vehicle; Based on the driving data, determine the required braking force of the vehicle; Based on the battery SOC of the vehicle, determine and execute a corresponding retarder braking strategy; wherein, the retarder braking strategy is used to allocate the target braking force of the electric drive system and the hydraulic retarder system in the vehicle respectively, so that the braking force output by the vehicle is consistent with the required braking force.

2. The method according to claim 1, wherein Based on the battery SOC of the vehicle, determine and execute a corresponding retarder braking strategy, including: If the battery SOC is less than the first preset SOC threshold, execute a primary retarder braking strategy; wherein, the primary retarder braking strategy uses the electric drive system alone for braking; If the battery SOC is greater than the first preset SOC threshold and less than the second preset SOC threshold, execute a secondary retarder braking strategy; wherein, the secondary retarder braking strategy combines the electric drive system and the hydraulic retarder system for composite braking; If the battery SOC is greater than the second preset SOC threshold, execute a tertiary retarder braking strategy; wherein, the tertiary retarder braking strategy uses the hydraulic retarder system alone for braking.

3. The method according to claim 2, wherein The secondary retarder braking strategy combines the electric drive system and the hydraulic retarder system for composite braking, including: Based on the battery SOC, the required braking force, and the current vehicle speed of the vehicle, introduce a preset fuzzy controller to obtain an energy recovery priority coefficient; Based on the energy recovery priority coefficient, the required braking force, and the maximum braking force of the electric drive system, obtain the target braking force of the electric drive system; Based on the current vehicle speed, the oil temperature, and the working gear of the hydraulic retarder system, introduce a preset dynamic compensation mechanism to obtain a dynamic compensation coefficient; Based on the dynamic compensation coefficient, the maximum braking force of the hydraulic retarder, and the difference between the required braking force and the target braking force of the electric drive system, obtain the target braking force of the hydraulic retarder.

4. The method according to claim 2, wherein The secondary retarder braking strategy combines the electric drive system and the hydraulic retarder system for composite braking, including: Obtain the current gear of the transmission in the electric drive system and the slope data of the long downhill driving condition; Based on the current gear and the slope data, query a pre-configured braking force ratio distribution table to obtain the braking ratio of the electric drive system and the hydraulic retarder system respectively; wherein, the braking force ratio distribution table is used to indicate the corresponding braking ratio of the electric drive system and the hydraulic retarder system under different current gears and different slope data conditions; the braking ratio is the ratio of the target braking force allocated to the electric drive system or the hydraulic retarder system to the required braking force; Based on the braking ratio of the electric drive system and the hydraulic retarder system respectively, determine the target braking force of the electric drive system and the hydraulic retarder system respectively.

5. The method according to claim 2, characterized in that, The three-stage retarder braking strategy uses the hydraulic retarder system for braking alone, including: Obtaining the current vehicle speed of the vehicle and the slope data of the long downhill condition; Based on the current vehicle speed and the slope data, querying a pre-configured retarder gear allocation table to obtain the working gear of the hydraulic retarder system; wherein, the retarder gear allocation table is used to indicate the corresponding working gear of the hydraulic retarder system under different current vehicle speeds and different slope data conditions.

6. The method according to any one of claims 1-5, characterized in that, The method further includes: Based on a pre-configured oil temperature prediction model, obtaining the oil temperature of the hydraulic retarder system; If the oil temperature is greater than a first preset temperature threshold, restricting the target braking force distribution of the hydraulic retarder system and starting the thermal management resources of the electric drive system for forced heat dissipation.

7. The method according to any one of claims 1-5, characterized in that, The method further includes: Obtaining the cooling water inlet temperature of the electric drive system; If the cooling water inlet temperature is greater than a second preset temperature threshold, stopping the target braking force distribution of the electric drive system.

8. A vehicle retarder braking device, characterized in that, Applied to a vehicle's vehicle controller, the vehicle includes an electric drive system, a hydraulic retarder system, and a mechanical braking system, including: A data acquisition module for collecting vehicle data of the vehicle when it is determined that the vehicle is in a long downhill condition; A braking force acquisition module for determining the required braking force of the vehicle based on the vehicle data; A strategy execution module for determining and executing a corresponding retarder braking strategy based on the battery SOC of the vehicle; wherein, the retarder braking strategy is used to allocate the target braking forces of the electric drive system and the hydraulic retarder system in the vehicle respectively, so that the braking force output by the vehicle is consistent with the required braking force.

9. A vehicle controller, characterized in that, Including a processor and a memory communicatively connected to the processor; The memory stores computer execution instructions; The processor executes the computer execution instructions stored in the memory to implement the method according to any one of claims 1 to 7.

10. A vehicle, characterized in that, The vehicle includes the vehicle controller according to claim 9, as well as an electric drive system, a hydraulic retarder system, and a mechanical braking system.

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