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

Abstract

The invention relates to the technical field of vehicles, in particular to an auxiliary braking method and system for a pure electric off-highway wide-body dumper. Obtaining whole vehicle information; whether the rotating speed of the driving motor is larger than a first threshold value or not is judged according to the whole vehicle information, if yes, an emergency braking mode is started, and if not, whether an auxiliary braking gear is started or not is judged; if the auxiliary braking gear is not opened, control is ended, and if the auxiliary braking gear is opened, whether the auxiliary braking gear is a braking gear or a constant-speed gear is judged; the regenerative braking torque of the driving motor and the braking torque of the hydraulic retarder can be automatically adjusted, the requirements for the braking torque and the vehicle speed of the pure electric off-highway wide-body dumper under the conventional working conditions (flat road / gentle slope) and the long downhill working conditions (especially the 15%-50% large slope) are met, and the electric quantity limiting condition of a power battery and the temperature limiting condition of the driving motor are met; and energy recovery maximization is realized.

Description

Technical Field

[0001] The present invention relates to the field of vehicle technology, and in particular to an auxiliary braking method and system for a pure electric off-road wide-body dump truck. Background Art

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

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

[0004] To overcome this problem, pure electric off-road wide-body dump trucks use regenerative braking technology that uses the drive motor as a generator to recover energy. This technology uses the back electromotive force of the drive motor when the vehicle decelerates or goes downhill, converts it into electrical energy and stores it in the power battery, realizing energy recovery and reuse. However, this technology still has some problems.

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

[0006] Secondly, the braking torque provided by the drive motor during regenerative braking is limited, but its braking torque often cannot meet the needs of pure electric off-highway wide-body dump trucks under extreme road conditions, especially on roads with slopes of 15% to 50%, where it is difficult to provide sufficient braking torque.

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

[0008] In response to the problems mentioned in the prior art, the present invention proposes an auxiliary braking method and system for a pure electric off-road wide-body dump truck. By rationally allocating the regenerative braking of the drive motor and the braking of the hydraulic retarder, the method solves the problem of decreased or lost efficiency of the regenerative braking of the drive motor when the power battery is high or continuous high-power regenerative braking is carried out. The method meets the braking torque and vehicle speed requirements of the pure electric off-road wide-body dump truck on slopes of 15% to 50%, and automatically provides additional auxiliary braking torque to provide the driver with emergency avoidance reaction time when the regenerative braking fails due to a power battery or drive motor failure.

[0009] In order to achieve the above object, the present invention adopts the following technical solutions: The present invention provides a method for controlling an auxiliary braking system of a pure electric off-road wide-body dump truck, comprising the following steps: Get vehicle information; Determine whether the speed of the drive motor is greater than a first threshold value based on the vehicle information. If so, enter the emergency braking mode. If not, determine whether the auxiliary braking gear is on. If the auxiliary braking gear is not on, the control ends; if the auxiliary braking gear is on, it is determined whether the auxiliary braking gear is a braking gear or a constant speed gear; If the auxiliary braking gear is a braking gear, determining whether the remaining power of the power battery is less than a second threshold and whether the temperature of the drive motor is less than a third threshold, if so, allocating 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 not, allocating the regenerative braking torque of the drive motor and the braking torque of the hydraulic retarder according to the second braking torque allocation rule; If the auxiliary brake gear is a constant speed gear, calculate the braking torque required for the current vehicle to go downhill at a constant speed; Determine whether the remaining power 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 distribution rule allocates the regenerative braking torque of the drive motor and the hydraulic retarder braking torque according to the braking torque value; if not, the third braking torque distribution rule allocates the regenerative braking torque of the drive motor and the hydraulic retarder braking torque.

[0010] As a further improvement of the present invention, the emergency braking mode includes: In the emergency braking mode, the hydraulic retarder outputs the braking torque of the hydraulic retarder and determines whether the output braking torque is less than 100%. If so, the preset braking torque is recalculated and the speed of the drive motor is re-determined to be greater than the first threshold. The process is repeated until the speed of the drive motor is less than the first threshold and the next step is entered; otherwise, the traditional friction braking system intervenes and the control ends.

[0011] As a further improvement of the present invention, the braking torque calculation formula of the hydraulic retarder in emergency braking mode is as follows:

[0012] Where: Indicates braking torque; represents the system moment of inertia; is the proportional gain; is the difference between the driving motor speed and the first threshold value of the driving motor speed; is the differential gain.

[0013] As a further improvement of the present invention, the first threshold value is the upper limit of the speed of the drive motor, which can be preset according to the drive motor parameters and the operating conditions of the vehicle.

[0014] As a further improvement of the present invention, the second threshold is an upper limit of the charging capacity of the power battery in the braking gear state, and the value range is 85% to 95%; The third threshold is an upper temperature limit of the drive motor in a braking state.

[0015] As a further improvement of the present invention, the fourth threshold is an upper limit of the charging capacity of the power battery in the constant speed gear state, ranging from 75% to 85%, and the fourth threshold is less than the second threshold; The fifth threshold is an upper temperature limit of the drive motor in a constant speed gear state, and the fifth threshold is smaller than the third threshold.

[0016] As a further improvement of the present invention, the first 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, which is in the range of 90% to 100% of the maximum regenerative braking torque, the drive motor will provide braking torque according to the upper limit, and the remaining part will be compensated by the hydraulic retarder braking torque 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, 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, which is in the range of 0% to 20% of the maximum regenerative braking torque, the drive motor provides braking torque according to the upper limit, and the remaining part is compensated by the hydraulic retarder braking torque 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, the braking torque required by the vehicle is provided by the regenerative braking torque of the drive motor.

[0017] As a further improvement of the present invention, the third braking torque distribution rule includes: If the braking torque required by the vehicle is entirely provided by the hydraulic retarder braking torque, the drive motor regenerative braking torque is not provided.

[0018] As a further improvement of the present invention, the calculation formula of the braking torque value required for the current vehicle to go downhill at a constant speed is as follows:

[0019] Where: is the total vehicle mass; is the acceleration due to gravity; is the rolling resistance coefficient; is the slope; is the air density; is the drag coefficient; is the windward area; is the current vehicle speed; is the tire radius; Main reducer speed ratio.

[0020] A pure electric off-road wide-body dump truck auxiliary braking system control system, used to implement the above method, includes a drive motor, a transmission, a drive shaft, a rear axle wheel end, a final reducer, a hydraulic retarder, a power battery pack and an 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, the other end of the transmission is connected to the drive shaft, and the drive shaft is connected to the rear axle wheel end through the main reducer, and the transmission is also connected to the hydraulic retarder.

[0021] Compared with the prior art, the present invention has achieved the following technical effects: The present 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 vehicle speed requirements of pure electric off-highway wide-body dump trucks under conventional working conditions (flat roads / gentle slopes) and long downhill conditions (especially steep slopes of 15% to 50%), while also meeting the power battery capacity limit and drive motor temperature limit conditions to maximize energy recovery.

[0022] The hydraulic retarder braking system in this invention's auxiliary braking method and system for pure electric off-highway wide-body dump trucks is independent of the vehicle's power battery and drive motor. This system can serve as a redundant backup brake in the event of a power battery or drive motor failure, ensuring braking system reliability. The hydraulic retarder braking system can also automatically activate to reduce the drive motor's speed in the event of a drive motor overspeed, ensuring vehicle and personnel safety.

[0023] The hydraulic retarder in the present invention serves as a non-contact auxiliary brake, which can significantly reduce the risk of overheating failure of traditional friction brakes, reduce friction brake pad wear, extend replacement cycles, and reduce long-term operating costs.

[0024] The hydraulic retarder in the present invention can share the braking energy, reduce the loss of the power battery caused by frequent charging and discharging, and increase the service life of the power battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the overall process of the present invention; Figure 2 It is a logical schematic diagram of the method of the present invention; Figure 3 Schematic diagram of the structure of the system of the present invention.

[0026] Figure numerals: 21, drive motor; 22, transmission; 23, drive shaft; 24, rear axle wheel end; 25, main reducer; 26, hydraulic retarder; 27, power battery pack; 28, inverter. DETAILED DESCRIPTION

[0027] Hereinafter, only certain exemplary embodiments are briefly described. As will be appreciated by those skilled in the art, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and description are to be considered as illustrative in nature and not restrictive.

[0028] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0029] 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 the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0030] In the present invention, unless otherwise expressly specified or limited, terms such as "mounted," "connected," "connect," and "fixed" should be understood broadly. For example, they may refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or communication; direct connection or indirect connection through an intermediate medium; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0031] In the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Furthermore, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0032] It will be understood that when used in this specification and the appended claims, the terms “comprises” and “comprising” indicate the presence of described features, integers, steps, operations, elements and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0033] It should also be understood that the terms used in the present specification are only for the purpose of describing particular embodiments and are not intended to limit the present invention. As used in the present 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.

[0034] It should be further understood that the term "and / or" used in the present description and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.

[0035] The accompanying drawings illustrate various schematic diagrams of structures according to embodiments disclosed herein. These figures are not drawn to scale; for clarity, some details are exaggerated and some details may be omitted. The shapes of the various regions and layers shown in the figures, as well as their relative sizes and positional relationships, are merely exemplary and may deviate in practice due to manufacturing tolerances or technical limitations. Those skilled in the art may design regions / layers with different shapes, sizes, and relative positions as needed.

[0036] Example 1 See also Figure 1 The present invention proposes a method for controlling an auxiliary braking system of a pure electric off-road wide-body dump truck, comprising the following steps: Get vehicle information; Determine whether the speed of the drive motor is greater than a first threshold value based on the vehicle information. If so, enter the emergency braking mode. If not, determine whether the auxiliary braking gear is on. If the auxiliary braking gear is not on, the control ends; if the auxiliary braking gear is on, it is determined whether the auxiliary braking gear is a braking gear or a constant speed gear; If the auxiliary braking gear is a braking gear, determining whether the remaining power of the power battery is less than a second threshold and whether the temperature of the drive motor is less than a third threshold, if so, allocating 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 not, allocating the regenerative braking torque of the drive motor and the braking torque of the hydraulic retarder according to the second braking torque allocation rule; If the auxiliary brake gear is a constant speed gear, calculate the braking torque required for the current vehicle to go downhill at a constant speed; Determine whether the remaining power 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 distribution rule allocates the regenerative braking torque of the drive motor and the hydraulic retarder braking torque according to the braking torque value; if not, the third braking torque distribution rule allocates the regenerative braking torque of the drive motor and the hydraulic retarder braking torque.

[0037] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0038] See also Figure 2 ,Step 1, collect vehicle information in real time.

[0039] Step 2: Based on the collected vehicle information, determine whether the drive motor speed n exceeds the first threshold value, which is the upper limit preset value n of the drive motor speed. H If yes, go to step three; if no, go to step six.

[0040] Step 3: The vehicle controller VCU enters the emergency braking mode, i.e., the hydraulic retarder is called to output according to the preset braking torque Ti; The braking torque Ti of the hydraulic retarder calculated by the vehicle control unit (VCU) in emergency braking mode is expressed as a percentage of the hydraulic retarder's currently available maximum torque. The greater the drive motor speed difference, the greater Ti, with an upper limit of 100%.

[0041] The vehicle controller VCU can be set according to the drive motor speed n and the upper limit of the drive motor speed preset value n H Calculate Ti by the difference:

[0042] Where: Indicates braking torque; represents the system moment of inertia; is the proportional gain; is the difference between the driving motor speed and the first threshold value of the driving motor speed; is the differential gain.

[0043] Step 4: Determine whether the current braking torque Ti of the hydraulic retarder is less than 100%. If so, execute step 5. If not, the traditional friction braking system intervenes and this control ends.

[0044] Step 5. The vehicle controller VCU recalculates and adjusts the braking torque Ti of the hydraulic retarder according to the difference between the current drive motor speed n and the first threshold, and then returns to step 2 to determine again whether the drive motor speed n exceeds the first threshold. If so, the process of steps 3, 4 and 5 is repeated until the drive motor speed in step 2 is less than the first threshold, then exits the loop and executes step 6.

[0045] Step six, determine whether the auxiliary braking gear is on. If not, the control ends. If so, execute step seven. In the embodiment, the auxiliary braking gear is divided into three states: off, constant speed gear, and braking gear. The braking gear is used for normal working conditions (flat road / gentle slope). When the driver adjusts the auxiliary braking gear to the braking gear, 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, it can be divided into several braking gears with different braking torques according to the needs of the user and the vehicle. The constant speed gear is used for long downhill conditions. When the driver adjusts the auxiliary braking gear to the constant speed gear, the vehicle controller VCU will record the vehicle speed at this time and keep the vehicle speed stable by adjusting the regenerative braking torque of the drive motor and the braking torque of the hydraulic retarder during the entire long downhill process, thereby realizing the function of constant speed downhill long slope.

[0046] Step 7: Determine whether the auxiliary brake gear is the brake gear. If so, execute step 8; if not, execute step 12.

[0047] Step 8: Determine whether the remaining power SOC of the power battery is less than SOC H1 If yes, then execute step nine, if no, then execute step eleven; In the embodiment, SOC is the ratio of the remaining power of the power battery to the rated capacity of the power battery, expressed as a percentage. H1 The second threshold is specifically the upper limit of the charging capacity of the power battery in the braking state, expressed as a percentage, SOC H1Generally, it can be preset between 85% and 95%, and the specific upper limit can be preset based on the rated capacity of the power battery, vehicle weight, regenerative braking power of the drive motor, and vehicle operating conditions.

[0048] Step 9: Determine whether the drive motor temperature t is less than t H1 If yes, go to step 10, if no, go to step 11; t is the temperature of the drive motor, t H1 is the third threshold, specifically the upper limit preset value of the drive motor temperature in the braking state, t H1 It can be preset according to vehicle weight, drive motor performance parameters and vehicle operating conditions.

[0049] Step 10. The vehicle controller VCU distributes the regenerative braking torque of the drive motor and the braking torque of the hydraulic retarder according to the first braking torque distribution rule. If the fixed braking torque value preset for the current braking gear is greater than the upper limit value of the regenerative braking torque of the drive motor, where the upper limit value 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 value can be preset according to the vehicle weight, the performance parameters of the drive motor and the vehicle operating conditions, 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 fixed braking torque value preset for the current braking gear; if the fixed braking torque value preset for the current braking gear is not greater than the upper limit value of the regenerative braking torque of the drive motor, the fixed braking torque value preset for the current braking gear is entirely provided by the regenerative braking torque of the drive motor.

[0050] Step 11. The vehicle controller VCU distributes 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 fixed braking torque value preset for the current braking gear is greater than the upper limit value of the regenerative braking torque of the drive motor, where the upper limit value of the regenerative braking torque of the drive motor is preset as 0% to 20% of the maximum regenerative braking torque, and the specific upper limit value can be preset according to the vehicle weight, the performance parameters of the drive motor and the vehicle operating conditions, 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 fixed braking torque value preset for the current braking gear; if the fixed braking torque value preset for the current braking gear is not greater than the upper limit value of the regenerative braking torque of the drive motor, the fixed braking torque value preset for the current braking gear is entirely provided by the regenerative braking torque of the drive motor.

[0051] Step 12: Determine whether the auxiliary brake gear is a constant speed gear. If so, execute step 13; if not, the control ends.

[0052] Step 13: Determine whether the remaining power SOC of the power battery is less than SOC H2 If yes, go to step 14, if no, go to step 16; SOCH2 The fourth threshold is specifically the upper limit of the charging capacity of the power battery in the constant speed state, expressed as a percentage, SOC H2 Generally lower than SOC H1 , which can be preset between 75% and 85%. 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.

[0053] Step 14: Determine whether the drive motor temperature t is less than t H2 If yes, go to step 15, if no, go to step 16; H2 is the fifth threshold, specifically the upper temperature limit preset value of the drive motor in the constant speed gear state, t H2 Generally lower than t H1 , t H2 It can be preset according to vehicle weight, drive motor performance parameters and vehicle operating conditions.

[0054] Step 15. The vehicle controller VCU calculates the braking torque value required to maintain the current vehicle speed constant downhill (converted to the drive shaft) based on the current vehicle speed, vehicle weight and other vehicle information, and distributes the calculated braking torque value to the drive motor regenerative braking torque and the hydraulic retarder braking torque according to the first braking torque distribution rule, wherein the upper limit value of the drive motor regenerative braking torque is preset as 90% to 100% of the maximum regenerative braking torque. The specific upper limit value can be preset according to the vehicle weight, drive motor performance parameters and vehicle operating conditions. If the regenerative braking torque is less than the braking torque value calculated by the vehicle controller VCU, the hydraulic retarder will supplement the braking torque to provide the shortfall.

[0055] Based on the vehicle information in step 1, calculate the braking torque required for the current vehicle to travel downhill at a constant speed. The calculation formula is as follows:

[0056] Where: is the total vehicle mass; is the acceleration due to gravity; is the rolling resistance coefficient; is the slope; is the air density; is the drag coefficient; is the windward area; is the current vehicle speed; is the tire radius; Main reducer speed ratio.

[0057] Step 16: The vehicle controller VCU calculates the braking torque value required to maintain the current constant speed downhill (converted to the drive shaft) based on the current vehicle speed, vehicle weight and other vehicle information, and the hydraulic retarder provides braking torque according to the calculated braking torque value.

[0058] Example 2 This embodiment is basically the same as embodiment 1, except that Figure 3 This embodiment provides an auxiliary braking system for a pure electric off-road wide-body dump truck, including a drive motor 21, a transmission 22, a drive shaft 23, a rear axle wheel end 24, a final reducer 25, a hydraulic retarder 26, a power battery pack 27, and an inverter 28; The rotor of the driving motor 21 is connected to the transmission 22 .

[0059] The stator of the drive motor 21 is connected to the power battery pack 27 via the inverter 28 , wherein the drive motor 21 consumes the mechanical energy of the transmission shaft 23 through the inverter 28 to store electrical energy in the power battery pack 27 and outputs braking torque to the transmission shaft 23 .

[0060] The transmission 22 is connected to a transmission shaft 23 .

[0061] The hydraulic retarder 26 is connected to the transmission 22 , wherein the hydraulic retarder 26 controls the transmission state of the transmission 22 and outputs braking torque to the transmission shaft 23 .

[0062] The transmission shaft 23 is connected to the rear axle wheel end 24 via the final reducer 25 to output the total auxiliary braking torque.

[0063] When the vehicle brakes, the braking torque at the rear axle wheel end 24 can be provided jointly or independently 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 transmitted by the drive shaft 23 connected to the rear end of the transmission 22 to the final reducer 25 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 by the drive shaft 23 connected to the rear end of the transmission 22 to the final reducer 25 for further amplification before finally 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 are braking together, the braking torque of the drive motor 21 and the hydraulic retarder 26 are transmitted jointly 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.

[0064] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, from all points of view, the embodiments should be regarded as illustrative and non-restrictive. The scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes that fall within the meaning and range of equivalents of the claims are included in the present invention. Any reference signs in the claims should not be construed as limiting the claim to which they relate.

[0065] In addition, it should be understood that although this specification describes the embodiments, not every embodiment contains only one independent technical solution. This description is for clarity only. Those skilled in the art should consider the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art. The above content is only for the purpose of illustrating the technical concept of the present invention and cannot be used to limit the scope of protection of the present invention. Any changes made based on the technical solution in accordance with the technical concept proposed by the present invention fall within the scope of protection of the claims of the present invention.

Claims

1. A method for controlling an auxiliary braking system of a pure electric off-road wide-body dump truck, characterized in that: The following steps are involved: Get vehicle information; Determine whether the speed of the drive motor is greater than a first threshold value based on the vehicle information. If so, enter the emergency braking mode. If not, determine whether the auxiliary braking gear is on. If the auxiliary braking gear is not on, the control ends; if the auxiliary braking gear is on, it is determined whether the auxiliary braking gear is a braking gear or a constant speed gear; If the auxiliary braking gear is a braking gear, determining whether the remaining power of the power battery is less than a second threshold and whether the temperature of the drive motor is less than a third threshold, if so, allocating 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 not, allocating the regenerative braking torque of the drive motor and the braking torque of the hydraulic retarder according to the second braking torque allocation rule; If the auxiliary brake gear is a constant speed gear, calculate the braking torque required for the current vehicle to go downhill at a constant speed; Determine whether the remaining power 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 distribution rule allocates the regenerative braking torque of the drive motor and the hydraulic retarder braking torque according to the braking torque value; if not, the third braking torque distribution rule allocates the regenerative braking torque of the drive motor and the hydraulic retarder braking torque.

2. A method for controlling an auxiliary braking system of a pure electric off-road wide-body dump truck according to claim 1, characterized in that: The emergency braking mode includes: In the emergency braking mode, the hydraulic retarder outputs the braking torque of the hydraulic retarder and determines whether the output braking torque is less than 100%. If so, the preset braking torque is recalculated and the speed of the drive motor is re-determined to be greater than the first threshold. The process is repeated until the speed of the drive motor is less than the first threshold and the next step is entered; otherwise, the traditional friction braking system intervenes and the control ends.

3. A method for controlling an auxiliary braking system of a pure electric off-road wide-body dump truck according to claim 2, characterized in that: The braking torque calculation formula of the hydraulic retarder in emergency braking mode is as follows: Where: Indicates braking torque; represents the system moment of inertia; is the proportional gain; is the difference between the driving motor speed and the first threshold value of the driving motor speed; is the differential gain.

4. A method for controlling an auxiliary braking system of a pure electric off-road 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 drive motor parameters and the operating conditions of the vehicle.

5. A method for controlling an auxiliary braking system of a pure electric off-road 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 range is 85% to 95%; The third threshold is an upper temperature limit of the drive motor in a braking state.

6. A method for controlling an auxiliary braking system of a pure electric off-road 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 the constant speed gear state, ranging from 75% to 85%, and the fourth threshold is less than the second threshold; The fifth threshold is an upper temperature limit of the drive motor in a constant speed gear state, and the fifth threshold is smaller than the third threshold.

7. A method for controlling an auxiliary braking system of a pure electric off-road wide-body dump truck according to claim 1, characterized in that: The first 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, which is in the range of 90% to 100% of the maximum regenerative braking torque, the drive motor will provide braking torque according to the upper limit, and the remaining part will be compensated by the hydraulic retarder braking torque 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, 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, which is in the range of 0% to 20% of the maximum regenerative braking torque, the drive motor provides braking torque according to the upper limit, and the remaining part is compensated by the hydraulic retarder braking torque 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, the braking torque required by the vehicle is provided by the regenerative braking torque of the drive motor.

8. A method for controlling an auxiliary braking system of a pure electric off-road wide-body dump truck according to claim 1, characterized in that: The third braking torque distribution rule includes: If the braking torque required by the vehicle is entirely provided by the hydraulic retarder braking torque, the drive motor regenerative braking torque is not provided.

9. A method for controlling an auxiliary braking system of a pure electric off-road wide-body dump truck according to claim 1, characterized in that: The calculation formula for the braking torque value required for the current vehicle to go downhill at a constant speed is as follows: Where: is the total vehicle mass; is the acceleration due to gravity; is the rolling resistance coefficient; is the slope; is the air density; is the drag coefficient; is the windward area; is the current vehicle speed; is the tire radius; Main reducer speed ratio.

10. A pure electric off-road wide-body dump truck auxiliary braking system control system, used to implement the method according to any one of claims 1 to 9, characterized in that: Including drive motor, transmission, drive shaft, rear axle wheel end, final 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, the other end of the transmission is connected to the drive shaft, and the drive shaft is connected to the rear axle wheel end through the main reducer, and the transmission is also connected to the hydraulic retarder.

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