Auxiliary braking method and system for pure electric off-highway wide-body dump truck

Abstract

This invention relates to the field of vehicle technology, specifically to an auxiliary braking method and system for a pure electric off-highway wide-body dump truck. The method involves acquiring vehicle information; determining whether the drive motor speed exceeds a first threshold based on the vehicle information; if so, entering emergency braking mode; otherwise, determining whether auxiliary braking is engaged; if auxiliary braking is not engaged, control ends; if auxiliary braking is engaged, determining whether the auxiliary braking is in braking or constant speed mode. This invention can automatically adjust the regenerative braking torque of the drive motor and the braking torque of the hydraulic retarder to meet the braking torque and speed requirements of the pure electric off-highway wide-body dump truck under normal operating conditions (flat roads / gentle slopes) and long downhill conditions (especially steep slopes of 15% to 50%), while also meeting the limitations of the power battery charge and drive motor temperature, thus maximizing energy recovery.

Description

Technical Field

[0001] This invention relates to the field of vehicle technology, specifically to an auxiliary braking method and system for a pure electric off-highway wide-body dump truck. Background Technology

[0002] As an important transportation equipment in modern mining and large-scale engineering fields, pure electric off-highway wide-body dump trucks operate in extremely special and complex environments. They often need to operate for long periods of time and under high intensity in extreme conditions such as mines, steep slopes, and heavy loads. In these operating scenarios, frequent braking operations have become a problem that urgently needs to be solved.

[0003] Traditional friction braking systems are prone to overheating during frequent braking in pure electric off-highway wide-body dump trucks. This is because when a dump truck goes downhill or needs to slow down and stop, the braking system needs to withstand huge frictional forces and energy conversion, generating a lot of heat. Once the braking system overheats, its braking efficiency will decrease significantly, or it may even fail completely, thus affecting driving safety. In addition, overheating will also accelerate the wear of the service brakes and tires, shorten their service life, and thus increase the operating costs of pure electric off-highway wide-body dump trucks.

[0004] To overcome this challenge, pure electric off-highway wide-body dump trucks have adopted regenerative braking technology that uses the drive motor as the generator to recover energy. This technology utilizes the back electromotive force of the drive motor when the vehicle decelerates or goes downhill, converting it into electrical energy and storing it in the power battery, thus realizing energy recovery and reuse. However, this technology still has some problems.

[0005] First, the charging acceptance capacity of the power battery will decrease significantly when the power battery is in a high charge state. When the power battery is at a high charge level, the electrical energy generated by the regenerative braking of the drive motor cannot be effectively stored, resulting in a decrease in recycling efficiency. When continuous high-power braking occurs, the drive motor and power battery will exceed their load capacity, leading to problems such as overheating of the drive motor and overcharging or over-discharging of the power battery.

[0006] Secondly, the braking torque provided by the drive motor during regenerative braking is limited, and its braking torque often fails to meet the needs of pure electric off-highway wide-body dump trucks under extreme road conditions, especially on roads with a gradient of 15% to 50%, where it is difficult to provide sufficient braking torque.

[0007] Furthermore, when a failure of the power battery or drive motor causes regenerative braking to fail, pure electric off-highway wide-body dump trucks lack other effective auxiliary braking measures. Summary of the Invention

[0008] To address the problems mentioned in the prior art, this invention proposes an auxiliary braking method and system for pure electric off-highway wide-body dump trucks. It solves the problem of reduced or lost efficiency of regenerative braking of the drive motor when the power battery is at high charge or under continuous high-power regenerative braking by rationally distributing the regenerative braking of the drive motor. This meets the braking torque and speed requirements of pure electric off-highway wide-body dump trucks on slopes of 15% to 50%. In the event of regenerative braking failure due to a power battery or drive motor malfunction, it automatically provides additional auxiliary braking torque to give the driver reaction time for emergency avoidance.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] This invention proposes a control method for the auxiliary braking system of a pure electric off-highway wide-body dump truck, comprising the following steps:

[0011] Obtain vehicle information;

[0012] Based on the vehicle information, determine whether the speed of the drive motor is greater than the first threshold. If so, enter the emergency braking mode; otherwise, determine whether the auxiliary braking gear is activated.

[0013] If the auxiliary braking mode is not engaged, the control ends; if the auxiliary braking mode is engaged, it is determined whether the auxiliary braking mode is a braking mode or a constant speed mode.

[0014] If the auxiliary braking gear is the braking gear, determine whether the remaining power battery charge is less than the second threshold and whether the drive motor temperature is less than the third threshold. If so, the regenerative braking torque of the drive motor and the braking torque of the hydraulic retarder are allocated according to the first braking torque allocation rule; otherwise, the regenerative braking torque of the drive motor and the braking torque of the hydraulic retarder are allocated according to the second braking torque allocation rule.

[0015] If the auxiliary braking gear is constant speed, calculate the braking torque required for a constant downhill speed at the current vehicle speed;

[0016] Determine whether the remaining power battery charge is less than the fourth threshold and whether the drive motor temperature is less than the fifth threshold. If so, the first braking torque allocation rule allocates the regenerative braking torque of the drive motor and the braking torque of the hydraulic retarder according to the braking torque value. Otherwise, the third braking torque allocation rule allocates the regenerative braking torque of the drive motor and the braking torque of the hydraulic retarder.

[0017] As a further improvement of the present invention, the emergency braking mode includes:

[0018] In emergency braking mode, the hydraulic retarder outputs braking torque and determines whether the output braking torque is less than 100%. If so, it recalculates the preset braking torque and re-determines whether the speed of the drive motor is greater than the first threshold. This process is repeated until the speed of the drive motor is less than the first threshold, at which point it proceeds to the next step. Otherwise, the traditional friction braking system intervenes, and the control ends.

[0019] As a further improvement to the present invention, the braking torque calculation formula for the hydraulic retarder in emergency braking mode is as follows:

[0020]

[0021] In the formula: Indicates braking torque; Indicates the system's moment of inertia; For proportional gain; This is the difference between the drive motor speed and the first threshold speed of the drive motor. This is the differential gain.

[0022] As a further improvement of the present invention, the first threshold is the upper limit of the speed of the drive motor, which can be preset according to the parameters of the drive motor and the operating conditions of the vehicle.

[0023] As a further improvement of the present invention, the second threshold is the upper limit of the charging capacity of the power battery in the braking state, and the value range is 85% to 95%;

[0024] The third threshold is the upper limit of the temperature of the drive motor under braking conditions.

[0025] As a further improvement of the present invention, the fourth threshold is the upper limit of the charging capacity of the power battery in constant speed mode, and the value range is 75% to 85%, and the fourth threshold is less than the second threshold.

[0026] The fifth threshold is the upper limit of the temperature of the drive motor in constant speed mode, and the fifth threshold is less than the third threshold.

[0027] As a further improvement of the present invention, the first braking torque distribution rule includes:

[0028] If the braking torque required by the vehicle is greater than the upper limit of the regenerative braking torque of the drive motor, and the upper limit ranges from 90% to 100% of the maximum regenerative braking torque, then the drive motor provides the braking torque according to the upper limit, and the remaining part is provided by the hydraulic retarder braking torque compensation to provide the braking torque required by the vehicle.

[0029] If the braking torque required by the vehicle is not greater than the upper limit of the regenerative braking torque of the drive motor, then the braking torque required by the vehicle is provided by the regenerative braking torque of the drive motor.

[0030] The second braking torque distribution rule includes:

[0031] If the braking torque required by the vehicle is greater than the upper limit of the regenerative braking torque of the drive motor, and the upper limit ranges from 0% to 20% of the maximum regenerative braking torque, then the drive motor provides the braking torque according to the upper limit, and the remaining part is provided by the hydraulic retarder braking torque compensation to provide the braking torque required by the vehicle.

[0032] If the braking torque required by the vehicle is not greater than the upper limit of the regenerative braking torque of the drive motor, then the braking torque required by the vehicle is provided by the regenerative braking torque of the drive motor.

[0033] As a further improvement of the present invention, the third braking torque distribution rule includes:

[0034] If the braking torque required by the entire vehicle is provided by the hydraulic retarder, the regenerative braking torque of the drive motor is not provided.

[0035] As a further improvement to the present invention, the formula for calculating the braking torque value required for a constant downhill speed is as follows:

[0036]

[0037] In the formula: The total mass of the vehicle; It is the acceleration due to gravity; This is the rolling resistance coefficient; Slope; air density; This refers to the drag coefficient; For windward area; Current vehicle speed; The radius of the tire; The speed ratio of the main reducer.

[0038] A control system for an auxiliary braking system of a pure electric off-highway wide-body dump truck, used to implement the above method, includes a drive motor, a transmission, a drive shaft, a rear axle wheel end, a main reducer, a hydraulic retarder, a power battery pack, and an inverter;

[0039] One end of the inverter is connected to the drive motor, and the other end is connected to the power battery pack;

[0040] The drive motor is also connected to the transmission, and the other end of the transmission is connected to the drive shaft. The drive shaft is connected to the rear axle wheel end through the main reducer. The transmission is also connected to the hydraulic retarder.

[0041] Compared with the prior art, the present invention achieves the following technical effects:

[0042] This invention can automatically adjust the regenerative braking torque of the drive motor and the braking torque of the hydraulic retarder to meet the braking torque and speed requirements of pure electric off-highway wide-body dump trucks under normal working conditions (flat roads / gentle slopes) and long downhill working conditions (especially large slopes of 15% to 50%), and meet the power battery charge limit and drive motor temperature limit conditions, thereby maximizing energy recovery.

[0043] The hydraulic retarder braking system in this invention for a pure electric off-highway wide-body dump truck is independent of the vehicle's power battery and drive motor. It serves as a redundant backup auxiliary brake in case of power battery or drive motor failure, ensuring the reliability of the braking system. It can also automatically activate the hydraulic retarder braking system to reduce the drive motor speed when it overspeeds, ensuring the safety of the vehicle and its occupants.

[0044] The hydraulic retarder in this invention serves as a non-contact auxiliary brake, which can significantly reduce the risk of overheating failure of traditional friction brakes, reduce wear on friction brake pads, extend replacement cycles, and lower long-term operating costs.

[0045] The hydraulic retarder in this invention can share braking energy, reduce the loss from frequent charging and discharging of the power battery, and improve the service life of the power battery. Attached Figure Description

[0046] Figure 1 This is a schematic diagram of the overall process of the present invention;

[0047] Figure 2 This is a schematic diagram of the method logic of the present invention;

[0048] Figure 3 This is a schematic diagram of the system of the present invention.

[0049] Reference numerals: 21. Drive motor; 22. Gearbox; 23. Drive shaft; 24. Rear axle wheel end; 25. Main reducer; 26. Hydraulic retarder; 27. Power battery pack; 28. Inverter. Detailed Implementation

[0050] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of the invention. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0051] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0052] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0053] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0054] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0055] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0056] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0057] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0058] The accompanying drawings illustrate various structural schematic diagrams according to embodiments disclosed in this invention. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0059] Example 1

[0060] See Figure 1 This invention proposes a control method for the auxiliary braking system of a pure electric off-highway wide-body dump truck, comprising the following steps:

[0061] Obtain vehicle information;

[0062] Based on the vehicle information, determine whether the speed of the drive motor is greater than the first threshold. If so, enter the emergency braking mode; otherwise, determine whether the auxiliary braking gear is activated.

[0063] If the auxiliary braking mode is not engaged, the control ends; if the auxiliary braking mode is engaged, it is determined whether the auxiliary braking mode is a braking mode or a constant speed mode.

[0064] If the auxiliary braking gear is the braking gear, determine whether the remaining power battery charge is less than the second threshold and whether the drive motor temperature is less than the third threshold. If so, the regenerative braking torque of the drive motor and the braking torque of the hydraulic retarder are allocated according to the first braking torque allocation rule; otherwise, the regenerative braking torque of the drive motor and the braking torque of the hydraulic retarder are allocated according to the second braking torque allocation rule.

[0065] If the auxiliary braking gear is constant speed, calculate the braking torque required for a constant downhill speed at the current vehicle speed;

[0066] Determine whether the remaining power battery charge is less than the fourth threshold and whether the drive motor temperature is less than the fifth threshold. If so, the first braking torque allocation rule allocates the regenerative braking torque of the drive motor and the braking torque of the hydraulic retarder according to the braking torque value. Otherwise, the third braking torque allocation rule allocates the regenerative braking torque of the drive motor and the braking torque of the hydraulic retarder.

[0067] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0068] See Figure 2 Step 1: Collect vehicle information in real time.

[0069] Step 2: Based on the collected vehicle information, determine whether the drive motor speed n exceeds the first threshold, which is the preset upper limit value n of the drive motor speed. H If yes, proceed to step three; otherwise, proceed to step six.

[0070] Step 3: The vehicle control unit (VCU) enters emergency braking mode, which means it calls the hydraulic retarder to output according to the preset braking torque Ti.

[0071] In emergency braking mode, the braking torque Ti of the hydraulic retarder calculated by the vehicle control unit (VCU) is expressed as a percentage of the current maximum available torque value of the hydraulic retarder. The greater the difference in drive motor speeds, the larger Ti becomes, with an upper limit of 100%.

[0072] The vehicle control unit (VCU) can adjust the speed of the drive motor (n) based on the speed of the drive motor and the preset upper limit of the drive motor speed (n). H Calculate the difference Ti:

[0073]

[0074] In the formula: Indicates braking torque; Indicates the system's moment of inertia; For proportional gain; This is the difference between the drive motor speed and the first threshold speed of the drive motor. This is the differential gain.

[0075] Step 4: Determine if the current braking torque Ti of the hydraulic retarder is less than 100%. If yes, proceed to step 5. If no, the traditional friction braking system will intervene, and this control operation will end.

[0076] Step 5: The vehicle control unit (VCU) recalculates and adjusts the braking torque Ti of the hydraulic retarder based on the difference between the current drive motor speed n and the first threshold. Then, it returns to step 2 to determine whether the drive motor speed n exceeds the first threshold. If so, it repeats steps 3, 4, and 5 until the drive motor speed in step 2 is less than the first threshold. Then, it exits the loop and executes step 6.

[0077] Step Six: Determine if the auxiliary braking position is engaged. If not, the control operation ends; if so, proceed to Step Seven. In this embodiment, the auxiliary braking position has three states: off, constant speed, and braking. The braking position is used for normal operating conditions (flat roads / gentle slopes). When the driver adjusts the auxiliary braking position to braking, the vehicle controller (VCU) will output a preset fixed braking torque by adjusting the regenerative braking torque of the drive motor and the braking torque of the hydraulic retarder. Generally, this can be divided into several braking positions with different braking torques depending on the user and vehicle requirements. The constant speed position is used for long downhill conditions. When the driver adjusts the auxiliary braking position to constant speed, the vehicle controller (VCU) will record the vehicle speed at this time and maintain a stable vehicle speed throughout the long downhill process by adjusting the regenerative braking torque of the drive motor and the braking torque of the hydraulic retarder, achieving the constant speed downhill function.

[0078] Step 7: Determine if the auxiliary braking gear is the braking gear. If yes, proceed to step 8; otherwise, proceed to step 12.

[0079] Step 8: Determine if the remaining SOC of the power battery is less than the SOC. H1 If yes, proceed to step nine; otherwise, proceed to step eleven. In this embodiment, SOC is the ratio of the remaining charge of the power battery to its rated capacity, expressed as a percentage. H1 The second threshold is the preset upper limit of the charging capacity of the power battery in braking mode, expressed as a percentage, SOC. H1 Generally, the preset value can be set between 85% and 95%, and the specific upper limit can be preset according to the rated capacity of the power battery, vehicle weight, regenerative braking power of the drive motor, and vehicle operating conditions.

[0080] Step 9: Determine if the drive motor temperature t is less than t0. H1 If yes, proceed to step ten; otherwise, proceed to step eleven. t represents the temperature of the drive motor. H1 The third threshold is specifically the preset upper limit of the drive motor temperature in braking mode, t. H1 Specifically, presets can be made based on vehicle weight, drive motor performance parameters, and vehicle operating conditions.

[0081] Step 10: The vehicle control unit (VCU) allocates the regenerative braking torque of the drive motor and the braking torque of the hydraulic retarder according to the first braking torque allocation rule. If the preset fixed braking torque value of the current braking gear is greater than the upper limit of the regenerative braking torque of the drive motor (the upper limit of the regenerative braking torque of the drive motor is preset according to 90% to 100% of the maximum regenerative braking torque, and the specific upper limit can be preset according to the vehicle weight, drive motor performance parameters, and vehicle operating conditions), then the drive motor provides braking torque according to the upper limit value, and the insufficient part is compensated by the braking torque of the hydraulic retarder to provide the preset fixed braking torque value of the current braking gear. If the preset fixed braking torque value of the current braking gear is not greater than the upper limit of the regenerative braking torque of the drive motor, then the entire preset fixed braking torque value of the current braking gear is provided by the regenerative braking torque of the drive motor.

[0082] Step 11: The vehicle control unit (VCU) allocates the regenerative braking torque of the drive motor and the braking torque of the hydraulic retarder according to the second braking torque distribution rule. If the preset fixed braking torque value of the current braking gear is greater than the upper limit of the regenerative braking torque of the drive motor (the upper limit of the regenerative braking torque of the drive motor is preset according to 0% to 20% of the maximum regenerative braking torque, and the specific upper limit can be preset according to the vehicle weight, drive motor performance parameters and vehicle operating conditions), then the drive motor provides braking torque according to the upper limit value, and the insufficient part is compensated by the braking torque of the hydraulic retarder to provide the preset fixed braking torque value of the current braking gear. If the preset fixed braking torque value of the current braking gear is not greater than the upper limit of the regenerative braking torque of the drive motor, then the entire preset fixed braking torque value of the current braking gear is provided by the regenerative braking torque of the drive motor.

[0083] Step 12: Determine if the auxiliary braking gear is in constant speed mode. If yes, proceed to step 13. If no, the control operation ends.

[0084] Step 13: Determine if the remaining SOC of the power battery is less than the SOC. H2 If yes, proceed to step fourteen; otherwise, proceed to step sixteen. (SOC) H2 The fourth threshold is the preset upper limit of the charging capacity of the power battery under constant speed conditions, expressed as a percentage, SOC. H2 Generally lower than SOC H1 The setting can be preset between 75% and 85%, and the specific upper limit can be preset according to the rated capacity of the power battery, vehicle weight, regenerative braking power of the drive motor and vehicle operating conditions.

[0085] Step 14: Determine if the drive motor temperature t is less than t H2 If yes, proceed to step fifteen; otherwise, proceed to step sixteen. H2The fifth threshold is specifically the preset upper limit of the drive motor temperature in constant speed mode, t. H2 Generally, it should be lower than t. H1 , t H2 Specifically, presets can be made based on vehicle weight, drive motor performance parameters, and vehicle operating conditions.

[0086] Step 15: The vehicle controller (VCU) calculates the braking torque required to maintain a constant downhill speed (converted to the drive shaft) based on the current vehicle speed, vehicle weight, and other vehicle information. It then distributes the calculated braking torque to the regenerative braking torque of the drive motor and the braking torque of the hydraulic retarder according to the first braking torque distribution rule. The upper limit of the regenerative braking torque of the drive motor is preset to 90%–100% of the maximum regenerative braking torque. The specific upper limit can be preset based on vehicle weight, drive motor performance parameters, and vehicle operating conditions. If the regenerative braking torque is less than the braking torque calculated by the vehicle controller (VCU), the insufficient portion is supplemented by the hydraulic retarder.

[0087] Based on the vehicle information from step one, calculate the braking torque required for a constant downhill speed at the current vehicle speed. The calculation formula is as follows:

[0088]

[0089] In the formula: The total mass of the vehicle; It is the acceleration due to gravity; This is the rolling resistance coefficient; Slope; air density; This refers to the drag coefficient; For windward area; Current vehicle speed; The radius of the tire; The speed ratio of the main reducer.

[0090] Step 16: The vehicle control unit (VCU) calculates the braking torque required to maintain a constant downhill speed (converted to the drive shaft) based on the current vehicle speed, vehicle weight, and other vehicle information, and the hydraulic retarder provides the braking torque according to the calculated braking torque value.

[0091] Example 2

[0092] This embodiment is basically the same as Embodiment 1, except that, see [link / reference] Figure 3 This embodiment proposes an auxiliary braking system for a pure electric off-highway wide-body dump truck, including a drive motor 21, a transmission 22, a drive shaft 23, a rear axle wheel end 24, a main reducer 25, a hydraulic retarder 26, a power battery pack 27, and an inverter 28.

[0093] The rotor of the drive motor 21 is connected to the gearbox 22.

[0094] The stator of the drive motor 21 is connected to the power battery pack 27 via the inverter 28. The drive motor 21 consumes the mechanical energy of the transmission shaft 23 to store electrical energy in the power battery pack 27 via the inverter 28, and outputs braking torque to the transmission shaft 23.

[0095] The gearbox 22 is connected to the drive shaft 23.

[0096] The hydraulic retarder 26 is connected to the transmission 22, and the hydraulic retarder 26 controls the transmission state of the transmission 22 and outputs braking torque to the drive shaft 23.

[0097] The drive shaft 23 is connected to the rear axle wheel end 24 via the main reducer 25, and outputs the total auxiliary braking torque.

[0098] When the vehicle brakes, the braking torque at the rear axle wheel end 24 can be provided jointly or separately by the drive motor 21 and the hydraulic retarder 26. The braking torque output by the drive motor 21 is amplified by the transmission 22 and then transmitted to the final reducer 25 via the drive shaft 23 connected to the rear end of the transmission 22 for further amplification before finally being transmitted to the rear axle wheel end 24, thus achieving auxiliary braking torque transmission for the vehicle. The hydraulic retarder 26 is connected in parallel with the transmission 22. The braking torque output by the hydraulic retarder 26 is transmitted to the final reducer 25 via the drive shaft 23 connected to the rear end of the transmission 22 for amplification before being transmitted to the rear axle wheel end 24, thus achieving auxiliary braking torque transmission for the vehicle. When the drive motor 21 and the hydraulic retarder 26 brake together, the braking torque of the drive motor 21 and the hydraulic retarder 26 is transmitted together to the drive shaft 23, then amplified by the final reducer 25 before being transmitted to the rear axle wheel end 24, thus achieving auxiliary braking torque transmission for the vehicle.

[0099] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the scope of the invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0100] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that can be understood by those skilled in the art. The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A control method for an auxiliary braking system of a pure electric off-highway wide-body dump truck, characterized in that, Includes the following steps: Obtain vehicle information; Based on the vehicle information, determine whether the drive motor speed is greater than a first threshold. If so, enter emergency braking mode; otherwise, determine whether auxiliary braking is activated. The emergency braking mode includes: In emergency braking mode, the hydraulic retarder outputs braking torque and checks if the output braking torque is less than 100%. If so, it recalculates the preset braking torque and checks if the drive motor speed is greater than a first threshold. This process is repeated until the drive motor speed is less than the first threshold, at which point it proceeds to the next step. Otherwise, the conventional friction braking system intervenes, and control ends. The braking torque calculation formula for the hydraulic retarder in emergency braking mode is as follows: In the formula: Indicates braking torque; Indicates the system's moment of inertia; For proportional gain; This is the difference between the drive motor speed and the first threshold speed of the drive motor. This is the differential gain; If the auxiliary braking mode is not engaged, the control ends; if the auxiliary braking mode is engaged, it is determined whether the auxiliary braking mode is a braking mode or a constant speed mode. If the auxiliary braking gear is the braking gear, determine whether the remaining power battery charge is less than the second threshold and whether the drive motor temperature is less than the third threshold. If so, the regenerative braking torque of the drive motor and the braking torque of the hydraulic retarder are allocated according to the first braking torque allocation rule; otherwise, the regenerative braking torque of the drive motor and the braking torque of the hydraulic retarder are allocated according to the second braking torque allocation rule. If the auxiliary braking gear is constant speed, calculate the braking torque required for a constant downhill speed at the current vehicle speed; The system determines whether the remaining charge of the power battery is less than a fourth threshold and whether the temperature of the drive motor is less than a fifth threshold. If so, the first braking torque allocation rule allocates the regenerative braking torque of the drive motor and the braking torque of the hydraulic retarder according to the braking torque values. Otherwise, the third braking torque allocation rule allocates the regenerative braking torque of the drive motor and the braking torque of the hydraulic retarder. The first braking torque allocation rule includes: If the braking torque required by the vehicle is greater than the upper limit of the regenerative braking torque of the drive motor, and the upper limit ranges from 90% to 100% of the maximum regenerative braking torque, then the drive motor provides the braking torque according to the upper limit, and the remaining part is provided by the hydraulic retarder braking torque compensation to provide the braking torque required by the vehicle. If the braking torque required by the vehicle is not greater than the upper limit of the regenerative braking torque of the drive motor, then the braking torque required by the vehicle is provided by the regenerative braking torque of the drive motor. The second braking torque distribution rule includes: If the braking torque required by the vehicle is greater than the upper limit of the regenerative braking torque of the drive motor, and the upper limit ranges from 0% to 20% of the maximum regenerative braking torque, then the drive motor provides the braking torque according to the upper limit, and the remaining part is provided by the hydraulic retarder braking torque compensation to provide the braking torque required by the vehicle. If the braking torque required by the vehicle is not greater than the upper limit of the regenerative braking torque of the drive motor, then the braking torque required by the vehicle is provided by the regenerative braking torque of the drive motor. The third braking torque distribution rule includes: If the braking torque required by the entire vehicle is provided by the hydraulic retarder, the regenerative braking torque of the drive motor is not provided.

2. The control method for the auxiliary braking system of a pure electric off-highway wide-body dump truck according to claim 1, characterized in that, The first threshold is the upper limit of the speed of the drive motor, which can be preset according to the parameters of the drive motor and the operating conditions of the vehicle.

3. The control method for the auxiliary braking system of a pure electric off-highway wide-body dump truck according to claim 1, characterized in that, The second threshold is the upper limit of the charging capacity of the power battery in the braking state, and the value ranges from 85% to 95%. The third threshold is the upper limit of the temperature of the drive motor under braking conditions.

4. The control method for the auxiliary braking system of a pure electric off-highway wide-body dump truck according to claim 1, characterized in that, The fourth threshold is the upper limit of the charging capacity of the power battery in constant speed mode, and the value ranges from 75% to 85%, and the fourth threshold is less than the second threshold. The fifth threshold is the upper limit of the temperature of the drive motor in constant speed mode, and the fifth threshold is less than the third threshold.

5. The control method for the auxiliary braking system of a pure electric off-highway wide-body dump truck according to claim 1, characterized in that, The formula for calculating the braking torque required for a constant downhill speed is as follows: In the formula: The total mass of the vehicle; It is the acceleration due to gravity; This is the rolling resistance coefficient; Slope; air density; This refers to the drag coefficient; For windward area; Current vehicle speed; The radius of the tire; The speed ratio of the main reducer.

6. A control system for an auxiliary braking system of a pure electric off-highway wide-body dump truck, used to implement the method described in any one of claims 1 to 5, characterized in that, It includes a drive motor, transmission, drive shaft, rear axle wheel end, main reducer, hydraulic retarder, power battery pack, and inverter; One end of the inverter is connected to the drive motor, and the other end is connected to the power battery pack; The drive motor is also connected to the transmission, and the other end of the transmission is connected to the drive shaft. The drive shaft is connected to the rear axle wheel end through the main reducer. The transmission is also connected to the hydraulic retarder.

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