Electronic mechanical braking system, control method and vehicle

Abstract

The invention provides an electronic mechanical brake system, a control method and a vehicle, after the opening degree of a brake pedal is increased from zero and before the opening degree of the brake pedal is decreased, the forward torque output by a brake motor is controlled to be increased along with the increase of the opening degree of the brake pedal. And after the opening degree of the brake pedal begins to be reduced, the forward torque output by the brake motor is controlled to be reduced at the first speed and then reduced to zero at the second speed smaller than the first speed. By means of the control mode, the stored elastic potential energy can be quickly released at a high first speed in the large clamping force stage of the wheel end braking device, and after most of the elastic potential energy is released in the large clamping force stage of the wheel end braking device, when a gear in the transmission part is about to move, the gear in the transmission part is driven to move. The speed is reduced to zero at the second small speed, the gear kinetic energy of the transmission part is reduced, then the situation that two adjacent gears collide due to the too high rotating speed is avoided, and the technical effect of eliminating meshing noise is achieved.

Description

Technical Field

[0001] This application relates to the field of automotive technology, and in particular to an electromechanical braking system, control method, and vehicle. Background Technology

[0002] In vehicles, the electronic mechanical brake (EMB) is a brake-by-wire system that transmits braking commands via electronic signals and uses a brake motor to generate braking force. Specifically, the brake motor outputs braking torque, which is then transmitted to the actuator via a transmission component. This actuator drives the actuator to clamp the brake disc, thereby generating braking force. While EMB systems offer high control precision and fast response, the moving parts within the system generate significant noise during braking, impacting the driver's experience.

[0003] Therefore, how to reduce the noise of electromechanical braking systems is an urgent problem to be solved. Summary of the Invention

[0004] This application provides an electromechanical braking system, control method, and vehicle, which avoids excessive noise caused by the impact of moving parts inside the electromechanical braking system due to excessive speed, thereby reducing the noise of the electromechanical braking system.

[0005] To achieve the above objectives, this application adopts the following technical solution:

[0006] In a first aspect, an electromechanical braking system is provided, comprising a brake controller and at least one wheel-end braking device. The wheel-end braking device includes a brake motor and an actuator. The brake motor is used to output positive torque to the actuator to drive the actuator to output clamping force to the brake disc. The brake controller is used for:

[0007] After the brake pedal opening increases from zero and before it begins to decrease, the positive torque output by the brake motor increases as the brake pedal opening increases. Furthermore, after the brake pedal opening begins to decrease, the positive torque output by the brake motor first decreases at a first rate, and then decreases to zero at a second rate less than the first rate.

[0008] When a driver needs to brake the vehicle, they press the brake pedal. As the brake pedal opening increases from zero, it is assumed that braking is required. The larger the brake pedal opening, the greater the braking force is expected to be applied. When the driver no longer needs to brake, they release the brake pedal. As the brake pedal opening begins to decrease, it is assumed that braking force is being released (corresponding to the release of the clamping force output by the actuator to the brake disc). The smaller the brake pedal opening, the less braking force is expected to be applied.

[0009] In this embodiment, as the brake pedal opening increases from zero, the positive torque output by the brake motor increases accordingly, causing the clamping force output by the actuator to the brake disc to increase as the brake pedal opening increases. This ensures that the vehicle brakes when the driver presses the brake pedal, and the deeper the brake pedal is pressed, the greater the braking force. Subsequently, as the brake pedal opening decreases, the positive torque output by the brake motor gradually decreases, causing the clamping force output by the actuator to the brake disc to gradually decrease. This ensures that the braking force decreases when the driver releases the brake pedal. In the initial stage of the decrease in positive torque, the wheel-end braking device is in a high clamping force phase. At this time, the transmission unit, actuator, and brake disc all store a large amount of elastic potential energy, which keeps the transmission chain of the wheel-end braking device in a highly taut state. In the initial stage of the decrease in positive torque, the brake controller controls the positive torque to decrease at a relatively high initial rate, allowing the stored elastic potential energy to be rapidly released as the positive torque decreases rapidly. At the end of the reduction of positive torque, the value of positive torque is small or close to zero, and most of the elastic potential energy of the transmission, actuator, and brake disc is released. The components in the transmission inside the wheel-end braking device are about to move. At the end of the reduction of positive torque, the brake controller controls the positive torque to decrease to zero at a small second rate, reducing the kinetic energy of the transmission components. This avoids collisions between two adjacent moving components (such as gears) due to excessive speed, ultimately achieving the technical effect of reducing the noise of the electromechanical braking system.

[0010] In conjunction with the first aspect, in some implementations of the first aspect, after the driver releases the pedal and during the process of the brake pedal opening decreasing, the brake controller can control the positive torque to decrease to zero before the brake pedal opening decreases to zero.

[0011] When the brake pedal opening decreases to zero, it is assumed that the vehicle's braking force needs to decrease to zero. When the positive torque of the brake motor decreases to zero, the brake caliper in the actuator is still in contact with the brake disc and there is a certain residual clamping force; in other words, there is still a certain residual braking force.

[0012] In this embodiment, the brake controller controls the positive torque to decrease to zero before the brake pedal opening decreases to zero. This essentially controls the timing of the positive torque decreasing to zero, ensuring that the moment the positive torque decreases to zero occurs before the brake pedal opening decreases to zero. This ensures that after the positive torque of the brake motor decreases to zero, a certain period is required before the brake pedal opening decreases to zero, allowing time for the components in the transmission section of the wheel-end braking device to continue moving. This causes the brake caliper in the actuator to move away from the brake disc, releasing residual clamping force (in other words, releasing the braking force). This ensures that the vehicle's braking force decreases to zero when the brake pedal opening decreases to zero. Furthermore, this embodiment ensures that the entire process of reducing the positive torque is controlled, preventing uncontrolled changes in the positive torque and thus preventing the sudden release of potential energy stored in the transmission section. This reduces the probability of collisions between adjacent gears and decreases the operating noise of the wheel-end braking device.

[0013] In conjunction with the first aspect, in some implementations of the first aspect, after the driver releases the pedal and during the process of the brake pedal opening decreasing, the brake controller can also control the positive torque to decrease to zero before the brake pedal opening decreases to a preset opening greater than zero.

[0014] The preset opening can be a positive value or a small value, such as 10%. To further ensure sufficient time to release residual clamping force and effective control of positive torque, the moment when the positive torque decreases to zero can be advanced by controlling the positive torque to decrease to zero before the brake pedal opening decreases to the preset opening. This allows sufficient time to release residual clamping force and further reduces the probability of collision between adjacent gears, thereby reducing the operating noise of the wheel-end braking device.

[0015] In conjunction with the first aspect, in some implementations of the first aspect, the brake controller can control the brake motor to output a first reverse torque after the positive torque output by the brake motor has decreased to zero and before the opening of the brake pedal has decreased to zero.

[0016] To release the residual clamping force of the actuator on the brake disc, after the positive torque output by the brake motor decreases to zero, the brake controller further controls the brake motor to output a first reverse torque in the opposite direction to the positive torque. This causes the brake motor to actively and controllably pull the actuator back, thereby actively counteracting the static friction inside the transmission unit and actively driving the actuator in the reverse direction, thus quickly eliminating this residual clamping force. This allows the actual clamping force to quickly drop to zero, achieving precise and rapid response at the end of brake release, and avoiding slight drag or brake response delay caused by residual clamping force.

[0017] In conjunction with the first aspect, in some implementations of the first aspect, when the brake controller controls the brake motor to output the first reverse torque, it can specifically control the first reverse torque to first increase and then decrease, and control the first reverse torque to decrease to zero when the brake pedal opening decreases to zero or after the brake pedal opening decreases to zero.

[0018] In the initial stage of releasing the residual clamping force, the friction and viscous forces in the transmission unit are relatively large. At this time, controlling the increase of the first reverse torque can actively generate a larger force to actively and quickly overcome the friction and viscous resistance, thereby ensuring that the residual clamping force can be quickly eliminated.

[0019] After the residual clamping force is eliminated or partially eliminated, the transmission unit stores new kinetic potential energy due to being pulled in the opposite direction. If the first reverse torque is suddenly reduced to zero at this time, this kinetic potential energy may cause the transmission system to rebound and oscillate in the opposite direction, thereby generating noise. Based on this, this embodiment controls the first reverse torque to increase and then controls it to decrease instead of suddenly dropping to zero, so that the kinetic potential energy of the transmission unit can be released in a controlled and gradual manner, thereby ensuring the smoothness of the wheel-end braking operation.

[0020] In conjunction with the first aspect, in some implementations of the first aspect, the brake controller can also control the brake motor to output a second reverse torque after the first reverse torque has decreased to zero.

[0021] In this embodiment, after the first reverse torque is reduced to zero, the brake motor is controlled to output a second reverse torque that is opposite to the direction of the forward torque. This actively drives the actuator to generate a backward displacement relative to the brake disc, so that a certain physical gap is maintained between the actuator and the brake disc to ensure that the two are completely separated and to eliminate the braking drag between the actuator and the brake disc.

[0022] In conjunction with the first aspect, in some implementations of the first aspect, after the first reverse torque is reduced to zero, the brake controller may first control the first reverse torque to remain at zero for a preset time, and then control the brake motor to output the second reverse torque.

[0023] This application, after the first reverse torque decreases to zero, first controls the first reverse torque to maintain at zero for a preset time, so that the elastic oscillation or inertial residue existing in the transmission part dissipates within the preset time. After the elastic oscillation or inertial residue dissipates, the brake motor is then controlled to output the second reverse torque, which ensures the accuracy and consistency of the execution of the second reverse torque and avoids the uncertainty of the return position caused by continuous operation.

[0024] In conjunction with the first aspect, in some implementations of the first aspect, when the brake controller controls the output of the second reverse torque of the brake motor, it can control the second reverse torque to first increase and then decrease to zero.

[0025] After the first reverse torque decreases to zero, the actuator will be stationary. Therefore, in order to push the actuator to continue moving, the second reverse torque needs to overcome obstacles such as static friction in the transmission. Controlling the second reverse torque to increase first can generate a sufficiently large and controllable force in the transmission chain of the transmission, reliably breaking through the threshold of static friction, and ensuring that the actuator and transmission mechanism can begin their return motion.

[0026] After the actuator and brake disc are separated, the actuator and transmission mechanism have dynamic potential energy due to the increased second reverse torque. At this time, by gradually reducing the second reverse torque, the actuator and transmission mechanism can be brought to a smooth stop under the control of the brake motor, thereby avoiding vibration of the wheel end braking device.

[0027] In conjunction with the first aspect, in some implementations of the first aspect, the brake controller can control the peak value of the second reverse torque to be less than the peak value of the first reverse torque.

[0028] The peak value of the first reverse torque refers to the maximum torque value reached by the brake motor when outputting the first reverse torque. The peak value of the second reverse torque refers to the maximum torque value reached by the brake motor when outputting the second reverse torque.

[0029] The purpose of the brake controller controlling the brake motor to output the first reverse torque is to actively and quickly overcome static friction and eliminate the residual clamping force of the wheel-end braking device. This requires a relatively large force to change the state of the device. Therefore, the first reverse torque needs a relatively large peak torque to ensure that the task can be reliably completed. The purpose of the brake controller controlling the brake motor to output the second reverse torque is to perform precise displacement control, pulling the actuator backward by an extremely small and controllable distance to establish a stable gap between the actuator and the brake disc. In this process, only friction and inertia during movement need to be overcome. Based on this, controlling the peak value of the second reverse torque to be smaller than the peak value of the first reverse torque in this application can avoid unnecessary energy consumption of the brake motor due to an excessively high peak value of the second reverse torque, thereby improving the overall energy management efficiency of the electromechanical braking system.

[0030] In conjunction with the first aspect, in some implementations of the first aspect, the brake controller can control the rate of decrease of the positive torque to increase as the rate of decrease of the brake pedal opening increases.

[0031] When a driver wants to stop braking quickly, they rapidly release the brake pedal, increasing the rate at which the brake pedal opening decreases. This shortens the time it takes for the brake pedal opening to reach zero. By controlling the rate of decrease of positive torque to increase with the rate of decrease of the brake pedal opening, the time it takes for the positive torque to decrease to zero can be shortened, ensuring that the vehicle's braking force is reduced to zero when the brake pedal opening reaches zero. Furthermore, this increased rate of decrease in positive torque, in turn, increases the rate of decrease in the clamping force output by the actuator to the brake disc, causing the vehicle to stop and decelerate rapidly. This ensures that the vehicle's state matches the driver's desired state, improving the driver's control over the vehicle.

[0032] In conjunction with the first aspect, in some implementations of the first aspect, the brake controller is used to receive the torque signal from the vehicle controller, and during the process of the brake pedal opening decreasing to zero, the torque value controlling the positive torque is different from the torque value indicated by the torque signal.

[0033] The torque signal of the vehicle controller is a torque signal determined by the vehicle controller based on the overall operating conditions of the vehicle. This torque signal is determined from a global perspective. In the embodiments of this application, the noise generated by the electromechanical braking system during braking is taken into account. The torque value of the positive torque output by the brake motor controlled by the brake controller is different from the torque value indicated by the torque signal of the vehicle controller, thereby effectively reducing the noise of the electromechanical braking system.

[0034] Secondly, this application provides a control method for an electromechanical braking system. The electromechanical braking system includes a brake controller and at least one wheel-end braking device. The wheel-end braking device includes a brake motor and an actuator. The brake motor outputs a positive torque to the actuator to drive the actuator to output a clamping force to the brake disc. The method includes:

[0035] After the brake pedal opening increases from zero and before the brake pedal opening decreases, the positive torque output by the brake motor increases as the brake pedal opening increases.

[0036] After the brake pedal opening begins to decrease, the positive torque output by the brake motor is reduced at a first rate, and then at a second rate less than the first rate until it reaches zero.

[0037] In conjunction with the second aspect, in some implementations of the second aspect, the control method further includes: after the brake pedal opening begins to decrease, controlling the positive torque to decrease to zero before the brake pedal opening decreases to zero.

[0038] In conjunction with the second aspect, in some implementations of the second aspect, the control method further includes: after the brake pedal opening begins to decrease, controlling the positive torque to decrease to zero before the brake pedal opening decreases to a preset opening greater than zero.

[0039] In conjunction with the second aspect, in some implementations of the second aspect, the control method further includes: controlling the brake motor to output a first reverse torque after the positive torque output by the brake motor decreases to zero and before the opening of the brake pedal decreases to zero.

[0040] In conjunction with the second aspect, in some implementations of the second aspect, the control method further includes: controlling the first reverse torque to increase first and then decrease, and controlling the first reverse torque to decrease to zero at the moment when the brake pedal opening decreases to zero or after the brake pedal opening decreases to zero.

[0041] In conjunction with the second aspect, in some implementations of the second aspect, the control method further includes: after the first reverse torque decreases to zero, controlling the brake motor to output a second reverse torque.

[0042] In conjunction with the second aspect, in some implementations of the second aspect, the control method further includes: after the first reverse torque decreases to zero, first controlling the first reverse torque to remain at zero for a preset time, and then controlling the brake motor to output the second reverse torque. In conjunction with the second aspect, in some implementations of the second aspect, the control method further includes: controlling the second reverse torque to first increase and then decrease to zero.

[0043] In conjunction with the second aspect, in some implementations of the second aspect, the control method further includes: controlling the peak value of the second reverse torque to be less than the peak value of the first reverse torque.

[0044] In conjunction with the second aspect, in some implementations of the second aspect, the control method further includes: controlling the rate of decrease of the positive torque to increase as the rate of decrease of the brake pedal opening increases.

[0045] In conjunction with the second aspect, in some implementations of the second aspect, the control method further includes: during the process of reducing the brake pedal opening to zero, the torque value of the control positive torque is different from the torque value indicated by the torque signal sent by the vehicle controller.

[0046] Thirdly, this application provides a vehicle that includes an electromechanical braking system as described in the first aspect and various embodiments of the first aspect, or includes a vehicle controller for executing a control method for the electromechanical braking system as described in the second aspect and various embodiments of the second aspect.

[0047] Specifically, other beneficial effects can be referred to the beneficial effects described in the first aspect, and will not be repeated here. Attached Figure Description

[0048] Figure 1 A schematic diagram of a vehicle architecture provided for an embodiment of this application;

[0049] Figure 2 A schematic diagram of the architecture of an electromechanical braking system provided in this application embodiment;

[0050] Figure 3 This is a schematic diagram of the structure of a wheel-end braking device provided in an embodiment of this application;

[0051] Figure 4 This is a schematic diagram of the structure of a brake controller provided in an embodiment of this application;

[0052] Figure 5 A control timing diagram of an electromechanical braking system provided in an embodiment of this application;

[0053] Figure 6 A flowchart illustrating the control method of an electromechanical braking system provided in this application embodiment. Detailed Implementation

[0054] The technical solutions in this application will now be described in conjunction with the accompanying drawings. The detailed descriptions and drawings of the following embodiments are used to exemplarily illustrate the principles of this application, but should not be used to limit the scope of this application; that is, this application is not limited to the described embodiments.

[0055] It should be noted that, in this application, the terms "exemplary" or "for example" are used to indicate that something is being described as an example, illustration, or illustration. Any embodiment or design described as "exemplary" or "for example" in this application should not be construed as being more preferred or advantageous than other embodiments or design solutions. Specifically, the use of terms such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0056] An electromechanical braking system is a brake-by-wire system that transmits braking commands via electronic signals and uses a brake motor to generate braking force. When the driver presses the brake pedal, the electromechanical braking system converts the brake pedal opening into a corresponding braking command, which is then transmitted to the brake motor via a signal transmission path to control the output torque of the brake motor, thereby increasing or decreasing the braking force at the wheel ends according to the driver's control intention.

[0057] Taking the brake release process as an example, when the driver intends to release the brake, they will release the brake pedal, at which point the brake pedal opening gradually decreases. During the process of the brake pedal opening gradually decreasing, the electromechanical braking system can control the torque output by the brake motor to change with the brake pedal opening through braking commands, thereby gradually reducing the braking force at the wheel ends, and ultimately releasing the vehicle from the brakes.

[0058] During the release of the brakes, the torque output by the brake motor is converted into braking force at the wheel ends, which requires the participation of transmission components such as gears. However, because there is backlash between the gears in the transmission components, adjacent gears will collide when the transmission components convert the torque of the brake motor into braking force, generating meshing noise.

[0059] One possible approach is to reduce backlash between gears by improving manufacturing precision, thereby eliminating meshing noise. However, gears wear during use, causing backlash to gradually develop and generate meshing noise. Therefore, improving manufacturing precision can only slow down the onset of meshing noise, but cannot completely eliminate it.

[0060] To address the aforementioned problems, this application provides an electromechanical braking system, control method, and vehicle that divides the torque control of the brake motor during the brake release process into at least two stages. In the first stage (when the positive torque is relatively high) before it drops to zero, the positive torque output by the brake motor is reduced at a relatively high first rate. In the second stage (when the positive torque is relatively low or close to zero) after the first stage, the positive torque output by the brake motor is reduced at a relatively low second rate. This reduces the kinetic energy of the transmission components, prevents adjacent transmission components from colliding due to excessive rotational speed, and achieves the technical effect of reducing the noise (e.g., meshing noise) of the electromechanical braking system.

[0061] Electromechanical braking systems can be applied to vehicles; see [link / reference]. Figure 1 , Figure 1 A schematic diagram of a vehicle 100 provided in an embodiment of this application is shown. The vehicle 100 may be an electric vehicle. Figure 1 As shown, vehicle 100 includes a drive system 110, a braking system 120, a power battery 130 connected to the drive system 110 and the braking system 120, and a vehicle controller 140. The drive system 110 is used to drive vehicle 100. The braking system 120 is used to brake vehicle 100. The power battery 130 is used to provide electrical energy to the drive system 110 and the braking system 120. The vehicle controller 140 is used to control the drive system 110 to drive vehicle 100 and to control the braking system 120 to brake vehicle 100.

[0062] The four wheels of vehicle 100 can be divided into left front wheel, right front wheel, left rear wheel, and right rear wheel according to their position in vehicle 100. In terms of axle arrangement, the left and right front wheels are coaxial and connected via the front axle. The left and right rear wheels are coaxial and connected via the rear axle. In terms of position, the left and left rear wheels are on the same side (left side), and the right front and right rear wheels are on the same side (right side). That is, in vehicle 100, the left and right front wheels are coaxial, the left and right rear wheels are coaxial, the left and left rear wheels are on the same side, and the right front and right rear wheels are on the same side.

[0063] In this application embodiment, the vehicle 100 can be any type of automobile, such as a sedan, truck, or passenger bus, or it can be a tricycle, two-wheeled vehicle, train, or other transportation device for carrying passengers or goods, or other types of vehicles powered by a power battery. This application embodiment does not limit this. The vehicle includes, but is not limited to, pure electric vehicles (pure EV / battery EV), hybrid electric vehicles (HEV), range-extended electric vehicles (REEV), plug-in hybrid electric vehicles (PHEV), and new energy vehicles (NEV).

[0064] The drive system 110 can be referred to as a powertrain. This application embodiment does not limit the specific type of powertrain; it is merely an example and not a limitation. The aforementioned powertrain can be a centralized powertrain, a hub motor powertrain, or a wheel-side motor powertrain. Specifically, the hub motor powertrain directly mounts the motor and reducer in the wheel rim, eliminating transmission components such as half-shafts, universal joints, differentials, and gearboxes; the wheel-side motor powertrain mounts the motor on the subframe.

[0065] The braking system 120 may be an electro-mechanical braking system (EMB).

[0066] The power battery 130 in this application embodiment can be a lithium-ion battery, lithium metal battery, lead-acid battery, nickel-cadmium battery, nickel-metal hydride battery, lithium-sulfur battery, lithium-air battery, or sodium-ion battery, etc., and this application does not limit it. In terms of scale, the power battery 130 in this application embodiment can be a single cell, a battery module, or a battery pack, and this application does not limit it. The power battery 130 can also supply power to other electrical devices in the vehicle, such as the vehicle's air conditioning and in-vehicle media player.

[0067] Please see Figure 2 , Figure 2 This is a schematic diagram of the architecture of an electromechanical braking system provided in an embodiment of this application.

[0068] like Figure 2 As shown, an electromechanical braking system is installed in vehicle 100, including a brake controller 30 and multiple wheel-end braking devices 40. The brake controller 30 is connected to the multiple wheel-end braking devices 40 via a communication bus. The communication bus may include a controller area network (CAN) bus, a local interconnect network (LIN) bus, a high-speed fault-tolerant network protocol (FlexRay), or other types of buses, and is not limited thereto. Vehicle 100 in this application can be a two-wheeled vehicle, a three-wheeled vehicle, a four-wheeled vehicle, or a vehicle with more than four wheels. One wheel-end braking device 40 is used to brake one wheel 50. The number of wheel-end braking devices 40 can be equal to or less than the number of wheels 50. Figure 2 The image shows a four-wheeled vehicle equipped with four wheel-end brake devices 40.

[0069] refer to Figure 3 , Figure 3 This is a schematic diagram of the structure of a wheel-end braking device provided in an embodiment of this application. Figure 3 As shown, the wheel-end braking device 40 includes a brake motor 401, a transmission unit 402, and an actuator 403. A brake disc 60 is mounted on the wheel 50 and is fixedly connected to the wheel 50. The brake motor 401 is connected to the input end of the transmission unit 402, and the actuator 403 is connected to the output end of the transmission unit 402.

[0070] When the vehicle 100 is traveling without braking, the actuator 403 in the wheel-end braking device 40 remains relatively stationary with respect to the vehicle body, and the brake disc 60 rotates together with the wheel 50 without any motion interference between them. When the vehicle 100 is traveling with braking, the actuator 403 outputs a clamping force to the brake disc 60 to compress it. The friction generated by this compression prevents the rotation of the brake disc 60, thereby braking the wheel 50. The actuator 403 may include a brake caliper.

[0071] The clamping force output of actuator 403, which clamps the brake disc 60, is driven by brake motor 401 via transmission unit 402. Taking a braking process as an example, the process of brake motor 401 driving actuator 403 to output clamping force to brake disc 60 is described as follows: When the driver depresses brake pedal 20, a displacement sensor connected to brake pedal 20 measures the opening degree of brake pedal 20 and transmits the measurement result to brake controller 30 via analog or digital signals. Brake controller 30 calculates the measured brake pedal opening degree into the corresponding required clamping force using a pre-stored brake pedal mapping curve. Based on the required clamping force, it controls brake motor 401 to output positive torque, which is then transmitted to actuator 403 via transmission unit 402. This drives actuator 403 to output clamping force to brake disc 60, ultimately causing wheel 50 to brake under the action of the clamping force. Here, positive torque refers to the torque output by brake motor 401 to generate braking force.

[0072] In one alternative implementation, the brake controller 30 may include a central controller 301 and a plurality of wheel-end controllers 302 corresponding to each wheel-end brake device 40.

[0073] refer to Figure 4 , Figure 4 This is a schematic diagram of the structure of a brake controller provided in an embodiment of this application. Figure 4 As shown, the central controller 301 can be connected to the position sensor of the brake pedal 20 to receive the opening signal collected by the position sensor, indicating the opening degree of the brake pedal 20. Then, based on the opening degree of the brake pedal 20 indicated by the opening signal, the central controller 301 determines the required clamping force corresponding to the opening degree of the brake pedal 20 through its internally stored pedal mapping curve, and converts the required clamping force into a clamping force signal, which is then transmitted to each wheel-end controller 302. Each wheel-end controller 302 controls the brake motor in its corresponding wheel-end braking device 40 based on its received clamping force signal.

[0074] The wheel-end braking device 40 may also include a clamping force sensor, which continuously monitors the actual clamping force acting on the brake disc 60 and feeds it back to the brake controller 30 as a feedback signal, so that the brake controller 30 can achieve precise control of the output torque of the brake motor 401 based on closed-loop feedback.

[0075] In one possible implementation, the transmission unit 402 may include a reducer and a worm gear assembly, or the reduction gear set and the worm gear assembly may be integrated into a single housing. The following description uses the transmission unit 402, which includes a reducer and a worm gear assembly, as an example. The reducer contains multiple sets of reduction gears. The input end of the reducer is connected to the brake motor 401, and the output end is connected to the worm wheel in the worm gear assembly. The worm in the worm gear assembly is connected to the actuator 403. When the brake motor 401 outputs positive torque, the brake motor 401 first reduces its speed and increases its torque through the reducer. Then, the increased positive torque from the reducer drives the worm wheel to rotate. The rotating worm wheel, through the meshing worm, converts the rotational motion into linear motion, which in turn outputs thrust to the actuator 403, thereby pushing the actuator 403 to output a clamping force to the brake disc 60.

[0076] The following combination Figure 1 The vehicle architecture shown Figure 2 The architecture of the electromechanical braking system shown Figure 3 The structure of the wheel-end braking device shown and Figure 4 The structure of the brake controller is shown, while referring to... Figure 5 The diagram illustrates a control timing diagram of an electromechanical braking system, and provides a detailed description of the electromechanical braking system, control method, and vehicle provided in this application.

[0077] See Figure 5 , Figure 5 In the diagram, time t0 is the moment when the opening of the brake pedal 20 starts to increase from zero, time t1 is the moment when the opening of the brake pedal 20 starts to decrease, time t2 is the moment when the positive torque value decreases to zero and is also the moment when the reverse torque output by the brake motor 401 starts to increase from zero, and time t3 is the moment when the opening of the brake pedal 20 decreases to zero.

[0078] During the operation of vehicle 100, if the driver detects an obstacle or other situation requiring deceleration / stopping in the direction of travel, they will apply the brakes by pressing the brake pedal 20. After the driver presses the brake pedal 20, the displacement sensor on the brake pedal 20 detects the opening of the brake pedal 20 and sends the detection result to the brake controller 30. When the vehicle speed of 100 decreases to zero or the risk of collision with the obstacle is eliminated, and braking is no longer necessary, the driver will release the brake pedal 20 to release the brakes.

[0079] Based on this, when the brake pedal opening increases from zero, it is assumed that the vehicle needs to brake. The larger the brake pedal opening, the greater the braking force is considered to be required. Subsequently, when the brake pedal opening begins to decrease, it is assumed that the vehicle needs to release the braking force (corresponding to the release of the clamping force output by the actuator to the brake disc). The smaller the brake pedal opening, the less braking force is considered to be required.

[0080] In some situations, to prevent drivers from accidentally pressing the brake pedal when braking is not required, braking can be determined only when the brake pedal opening increases from zero to a preset brake pedal opening. The preset brake pedal opening is set according to needs, such as 5% or 10%.

[0081] In the electromechanical braking system provided in this application embodiment, the brake controller 30 is used to control the positive torque output by the brake motor 401 to increase as the opening of the brake pedal 20 increases after time t0 when the opening of the brake pedal 20 starts to increase from zero and before time t1 when the opening of the brake pedal 20 starts to decrease.

[0082] See Figure 5 The positive torque value increases with the increase of the brake pedal opening between time t0 and time t1. In an optional embodiment, the positive torque can increase linearly with the increase of the brake pedal opening 20, or it can increase non-linearly with the increase of the brake pedal opening 20.

[0083] The positive torque output by the brake motor 401 determines the magnitude of the clamping force output by the actuator 403 to the brake disc 60. The positive torque output by the brake motor 401 increases as the opening of the brake pedal 20 increases, causing the clamping force output by the actuator 403 to the brake disc 60 to also increase as the opening of the brake pedal 20 increases, thereby decelerating the vehicle 100 and preventing a collision with an obstacle.

[0084] The brake controller 30 is also used to control the positive torque output by the brake motor 401 to decrease at a first rate and then at a second rate less than the first rate to zero after the opening of the brake pedal 20 begins to decrease at time t1.

[0085] After the driver releases the brake pedal 20, the opening of the brake pedal 20 gradually decreases from time t1. After time t1, when the opening of the brake pedal 20 begins to decrease, the brake controller 30 controls the positive torque output by the brake motor 401 to decrease first at a first rate, and then at a second rate less than the first rate. In effect, the process of decreasing the positive torque is divided into at least two stages. One stage is when the torque value decreases at a relatively large first rate (e.g., corresponding to...). Figure 5 The time period between time t1 and time t4 is one phase, and the other is a second phase in which the torque value decreases at a smaller second rate (e.g., corresponding to...). Figure 5 (The time period between time t4 and time t2).

[0086] In the first stage, the positive torque value is relatively large, which can be located in the initial period of the positive torque reduction process. In the second stage, the positive torque value is relatively small, which can be located in the later period of the positive torque reduction process. The second stage may include the moment when the positive torque decreases to zero. Through this control method, the brake controller 30 makes the rate of decrease when the positive torque decreases to zero smaller than the rate in the initial stage of positive torque reduction.

[0087] In the initial stage of positive torque reduction, the wheel-end braking device 40 is under high clamping force. At this time, the transmission unit 402, actuator 403, and brake disc 60 all store a large amount of elastic potential energy, which keeps the transmission chain of the wheel-end braking device 40 in a highly taut state. In the initial stage of positive torque reduction, the brake controller 30 controls the positive torque to decrease at a relatively large first rate, so that the stored elastic potential energy is quickly released as the positive torque decreases rapidly. In the final stage of positive torque reduction, the value of the positive torque is small or close to zero, and most of the elastic potential energy of the transmission unit, actuator, and brake disc has been released. The components (e.g., gears) in the transmission unit 402 inside the wheel-end braking device are about to move. In the final stage of positive torque reduction, the brake controller 30 controls the positive torque to decrease to zero at a relatively small second rate, reducing the kinetic energy of the components (e.g., gears) in the transmission unit 402, thereby avoiding collision between two adjacent moving components (e.g., gears) due to excessive speed, and ultimately reducing the noise (e.g., meshing noise) of the electromechanical braking system.

[0088] In one possible implementation, the rate of decrease in positive torque can be altered by changing the gain of the brake pedal 20. The gain of the brake pedal 20 refers to the ratio between the rate of decrease in the brake pedal 20 opening and the rate of decrease in positive torque. For example, during the phase where the positive torque decreases at a first rate, the gain of the brake pedal 20 is set to 20; during the phase where the positive torque decreases at a second rate, the gain is set to 80. This achieves a situation where, while the rate of decrease in the brake pedal 20 opening remains constant, the first rate of decrease in positive torque is greater than the second rate, resulting in the positive torque decreasing at a larger first rate and then decreasing to zero at a smaller second rate.

[0089] In one possible implementation, after time t1 when the brake pedal 20 opening begins to decrease, the brake controller 30 can control the positive torque to decrease to zero before the brake pedal 20 opening decreases to zero. See also Figure 5 The moment t2 when the brake controller 30 controls the positive torque to decrease to zero is before the moment t3 when the opening of the brake pedal 20 decreases to zero.

[0090] When the brake pedal opening decreases to zero, it is assumed that the vehicle's braking force needs to decrease to zero. When the positive torque of the brake motor decreases to zero, the components in the transmission part inside the wheel-end braking device are about to move. At this time, the actuator is still in contact with the brake disc and there is a certain residual clamping force, in other words, there is still a certain residual braking force.

[0091] In this embodiment, the brake controller controls the positive torque to decrease to zero before the brake pedal opening decreases to zero. In effect, it controls the timing of the positive torque decreasing to zero, ensuring that the positive torque decreases to zero precisely at the specified moment (e.g., ...). Figure 5 The moment t2 is when the brake pedal opening decreases to zero (e.g., time t2). Figure 5 Before time t3. In this way, it is ensured that after the positive torque of the brake motor is reduced to zero, there is still a certain period of time before the brake pedal opening is reduced to zero. This allows for a period of time to continue driving the components in the transmission part inside the wheel-end braking device to move, thereby causing the actuator to move away from the brake disc and release the residual clamping force (in other words, release the braking force). This ensures that the vehicle's braking force can be reduced to zero when the brake pedal opening is reduced to zero.

[0092] The brake pedal opening 20 acts as a control signal for the positive torque, continuously controlling it until it decreases to zero. This ensures the positive torque remains under control until time t3, when the brake pedal opening 20 decreases to zero. Simultaneously, the positive torque is the source of potential energy stored in the transmission unit 402. This potential energy increases with increasing positive torque and decreases with decreasing positive torque; the change in positive torque determines the change in potential energy.

[0093] By controlling the moment t2 when the positive torque decreases to zero to be before the moment t3 when the brake pedal 20 opening decreases to zero, the entire process of reducing the positive torque can be kept under control, avoiding uncontrolled changes in the positive torque. This prevents the potential energy stored in the transmission unit 402 from being suddenly released, thereby reducing the probability of collision between adjacent gears and reducing the operating noise of the wheel end braking device 40.

[0094] In another possible implementation, after time t1 when the brake pedal 20 opening begins to decrease, the brake controller 30 can also control the positive torque to decrease to zero before the brake pedal 20 opening decreases to a preset opening greater than zero.

[0095] The preset opening can be a positive value or a small value, such as 10%. To further ensure sufficient time to release residual clamping force and effective control of the positive torque, the moment the positive torque decreases to zero can be advanced by controlling the positive torque to decrease to zero before the brake pedal 20 opening decreases to the preset opening. This ensures sufficient time to release residual clamping force and further reduces the probability of collision between adjacent gears, thereby reducing the operating noise of the wheel-end braking device 40.

[0096] In one possible implementation, the brake controller 30 can control the brake motor 401 to output a first reverse torque after time t2 when the positive torque output by the brake motor 401 decreases to zero and before time t3 when the opening of the brake pedal 20 decreases to zero.

[0097] When the positive torque output by the brake motor 401 decreases to zero, due to friction between the reduction gears, worm gears, and worms in the transmission unit 402, and the viscosity of the lubricating oil and other materials between these components, the clamping force of the actuator 403 on the brake disc 60 cannot decrease to zero synchronously with the positive torque, resulting in a certain residual clamping force. This residual clamping force is difficult to release on its own or releases slowly.

[0098] To release the residual clamping force, after the positive torque output by the brake motor 401 decreases to zero at time t2, the brake controller 30 further controls the brake motor 401 to output a first reverse torque opposite to the positive torque. This causes the brake motor 401 to actively and controllably pull the actuator 403 back, thereby actively counteracting the static friction inside the transmission unit 402 and actively driving the actuator 403 in the reverse direction, thus quickly eliminating this residual clamping force. This allows the actual clamping force to quickly drop to zero, achieving precise and rapid response at the end of the brake release, and avoiding slight drag or brake response delay caused by residual clamping force.

[0099] In one possible implementation, when the brake controller 30 controls the brake motor 401 to output the first reverse torque, it can specifically control the first reverse torque to increase first and then decrease, and control the first reverse torque to decrease to zero at time t3 when the opening of the brake pedal 20 decreases to zero or after the opening of the brake pedal 20 decreases to zero.

[0100] See Figure 5 The time t5 when the first reverse torque decreases to zero coincides with the time t3 when the brake pedal 20 opening decreases to zero, or the time t5 when the first reverse torque decreases to zero is located after the time t3 when the brake pedal 20 opening decreases to zero. Figure 5 The diagram shows the situation where the moment t5, when the first reverse torque decreases to zero, coincides with the moment t3, when the opening of the brake pedal 20 decreases to zero.

[0101] In the initial stage of releasing the residual clamping force, the friction and viscous forces in the transmission unit 402 are relatively large. At this time, controlling the increase of the first reverse torque can actively generate a larger and controlled force to actively and quickly overcome the friction and viscous resistance, thereby ensuring that the residual clamping force can be quickly eliminated.

[0102] After the residual clamping force is eliminated or partially eliminated, the transmission unit 402 stores new kinetic potential energy due to being pulled in the opposite direction. If the first reverse torque is suddenly reduced to zero at this time, this kinetic potential energy may cause the transmission system to rebound and oscillate in the opposite direction, thereby generating noise. Based on this, by controlling the increase of the first reverse torque and then controlling the decrease of the first reverse torque instead of suddenly dropping to zero, the kinetic potential energy of the transmission unit 402 can be released gradually and in a controlled manner through the first reverse torque, thereby ensuring the smoothness of the wheel-end braking operation.

[0103] In one alternative implementation, the first reverse torque can be controlled to increase and then decrease in a sinusoidal manner.

[0104] In one possible implementation, after the first reverse torque decreases to zero at time t5, the brake controller 30 can also control the brake motor 401 to output a second reverse torque.

[0105] When the first reverse torque decreases to zero, the clamping force between the actuator 403 and the brake disc 60 also decreases to zero. However, due to effects such as thermal expansion, mechanical deformation, or oil film adsorption, the actuator 403 and the brake disc 60 may still be in a state of zero contact or micro-contact. This state will cause continuous friction between the actuator 403 and the brake disc 60 during the movement of the vehicle 100, i.e., brake drag. The presence of brake drag not only increases the energy consumption of the vehicle 100, but also accelerates component wear and causes uneven heating of the brake disc 60.

[0106] Therefore, after the first reverse torque decreases to zero at time t5, this application controls the brake motor 401 to output a second reverse torque opposite to the direction of the forward torque, actively driving the actuator 403 to generate a backward displacement relative to the brake disc 60, thereby maintaining a certain physical gap between the two to ensure that the two are completely separated and to eliminate the braking drag between the actuator 403 and the brake disc 60.

[0107] In one possible implementation, when the brake controller 30 controls the brake motor 401 to output the second reverse torque, it can control the second reverse torque to first increase and then decrease to zero.

[0108] After the first reverse torque decreases to zero at time t5, the actuator 403 will be stationary. Therefore, in order to push the actuator 403 to continue moving, the second reverse torque needs to overcome obstacles such as the static friction of the transmission unit 402. Controlling the increase of the second reverse torque first can generate a sufficiently large and controllable force in the transmission chain of the transmission unit 402, reliably breaking through the static friction threshold, and ensuring that the actuator 403 and the transmission mechanism can start the return movement.

[0109] Subsequently, after the actuator 403 and the brake disc 60 are separated, the actuator 403 and the transmission mechanism have dynamic potential energy due to the increased second reverse torque. At this time, by gradually reducing the second reverse torque, the actuator 403 and the transmission mechanism can be smoothly stopped under the control of the brake motor 401, thereby avoiding the wheel end brake device 40 from vibrating.

[0110] In one optional implementation, during the process of controlling the second reverse torque to first increase and then decrease to zero, the brake controller 30 can obtain the position of the actuator 403 in real time through the position sensor of the actuator 403, thereby determining the moment when the second reverse torque begins to decrease based on the real-time position of the actuator 403. The brake controller 30 can control the second reverse torque to increase and then decrease in a sinusoidal manner.

[0111] In one possible implementation, the brake controller 30 can control the peak value of the second reverse torque to be less than the peak value of the first reverse torque.

[0112] The peak value of the first reverse torque refers to the maximum torque value reached by the brake motor 401 when outputting the first reverse torque. The peak value of the second reverse torque refers to the maximum torque value reached by the brake motor 401 when outputting the second reverse torque.

[0113] For example, when the brake controller 30 controls the first reverse torque to increase from zero to a first torque value and then decrease from the first torque value back to zero, and the second reverse torque to increase from zero to a second torque value and then decrease from the second torque value back to zero, then the peak value of the first reverse torque is the first torque value, and the peak value of the second reverse torque is the second torque value. The brake controller 30 controls the peak value of the second reverse torque to be less than the peak value of the first reverse torque, which means controlling the second torque value to be less than the first torque value.

[0114] The purpose of the brake controller 30 controlling the brake motor 401 to output the first reverse torque is to actively and quickly overcome static friction and eliminate the residual clamping force of the wheel-end brake device 40, which requires a large force to change the state of the device. Therefore, the first reverse torque needs to have a relatively large peak torque to ensure that the task can be reliably completed.

[0115] The purpose of the brake controller 30 controlling the brake motor 401 to output a second reverse torque is to achieve precise displacement control, pulling the actuator 403 backward by an extremely small and controllable distance to establish a stable gap between the actuator 403 and the brake disc 60. In this process, the only things that need to be overcome are friction and inertia during motion.

[0116] Based on this, the embodiment of this application controls the peak value of the second reverse torque to be less than the peak value of the first reverse torque, which can avoid unnecessary energy consumption of the brake motor 401 due to the excessively high peak value of the second reverse torque, thereby improving the overall energy management efficiency of the electromechanical braking system.

[0117] In one possible implementation, after the first reverse torque decreases to zero at time t5, the brake controller 30 can first maintain the first reverse torque at zero for a preset duration before controlling the brake motor 401 to output the second reverse torque. The preset duration can be set according to requirements and can be a relatively short duration, such as 1ms or 2ms. When the first reverse torque smoothly decreases to zero, even if the control is intended to allow the transmission unit 402 to smoothly transition to a stationary state, the mechanical transmission system may still have slight elastic oscillations or residual inertia due to its structural limitations. In this case, controlling the brake motor 401 to output the second reverse torque would be equivalent to applying a new excitation to an unstable system, leading to inaccurate control.

[0118] After the first reverse torque decreases to zero, this application controls the first reverse torque to remain at zero for a preset time, allowing the elastic oscillations or residual inertia present in the transmission unit 402 to dissipate within the preset time. After the elastic oscillations or residual inertia dissipate, the brake motor 401 is then controlled to output the second reverse torque, ensuring the accuracy and consistency of the second reverse torque execution and avoiding uncertainty in the return position caused by continuous control operations.

[0119] In one possible implementation, the brake controller 30 can control the rate of decrease of the positive torque to increase as the rate of decrease of the brake pedal opening 20 increases.

[0120] When the driver wishes to stop braking quickly, they will rapidly release the brake pedal 20, increasing the rate at which the brake pedal 20 decreases in opening. This shortens the time it takes for the brake pedal opening to decrease to zero. By controlling the brake controller 30 to increase the rate of decrease in brake pedal opening as the rate of decrease in brake pedal opening increases, the time it takes for the positive torque to decrease to zero is shortened, ensuring that the vehicle's braking force is reduced to zero when the brake pedal opening reaches zero. Furthermore, the increased rate of decrease in positive torque, in turn, causes the clamping force output by the actuator 403 to the brake disc 60 to decrease rapidly, resulting in a rapid stop and deceleration of the vehicle 100. This ensures that the state of the vehicle 100 matches the driver's desired state, improving the driver's control over the vehicle 100.

[0121] In one possible implementation, the brake controller 30 is used to receive the torque signal from the vehicle controller, and during the process of the brake pedal 20 opening decreasing to zero, the torque value controlling the positive torque is different from the torque value indicated by the torque signal.

[0122] The torque signal of the vehicle controller is determined by the vehicle controller based on the overall operating conditions of the vehicle 100. This torque signal is determined from a global perspective. In this embodiment, the noise generated by the electromechanical braking system during braking is considered. The torque value of the positive torque output by the brake motor controlled by the brake controller differs from the torque value indicated by the torque signal of the vehicle controller, thereby effectively reducing the noise of the electromechanical braking system. This embodiment improves the reliability of the electromechanical braking system by giving the brake controller 30 the ability to make local autonomous decisions.

[0123] In this embodiment, the braking system 120 of the vehicle 100 may include multiple wheel-end braking devices 40, each wheel-end braking device 40 used to brake one wheel 50. For any wheel-end braking device 40, the torque output by the brake motor in the wheel-end braking device 40 can be controlled using the method provided in this embodiment.

[0124] Next, refer to Figure 5 as well as Figure 6 The diagram illustrates a control method for an electromechanical braking system. During the entire process from the moment the driver begins braking the vehicle 100 until the driver releases the brakes, the electromechanical braking system can be controlled through the following steps:

[0125] In step S101, after t0 when the opening of the brake pedal 20 increases from zero and before t1 when the opening of the brake pedal 20 begins to decrease, the positive torque output by the brake motor 401 is controlled to increase as the opening of the brake pedal 20 increases.

[0126] In step S102, after the opening of the brake pedal 20 begins to decrease at t1, the positive torque output by the brake motor 401 is controlled to decrease at a first rate, and then decrease to zero at a second rate less than the first rate.

[0127] In step S103, after the positive torque decreases to zero at time t2 and before the opening of the brake pedal 20 decreases to zero at time t3, the first reverse torque is controlled to increase first and then decrease, and the first reverse torque is controlled to decrease to zero at the moment when the opening of the brake pedal 20 decreases to zero or after the opening of the brake pedal 20 decreases to zero.

[0128] In step S104, after the first reverse torque decreases to zero at time t5, the first reverse torque is first controlled to maintain at zero for a preset time, and then the brake motor 401 is controlled to output the second reverse torque, and the second reverse torque is controlled to increase first and then decrease to zero.

[0129] The first and second reverse torques can change according to a sine wave pattern, first increasing and then decreasing, and the peak value of the second reverse torque is smaller than the peak value of the first reverse torque.

[0130] During the change of the opening of the brake pedal 20, the rate of change of the positive torque output by the brake motor 401 can increase as the rate of change of the opening of the brake pedal 20 increases.

[0131] In an optional implementation, step S101 may further include the following steps:

[0132] Step S101-1: After t0 when the opening of the brake pedal 20 increases from zero and before t1 when the opening of the brake pedal 20 begins to decrease, determine whether the vehicle 100 is in an emergency braking state based on the rate of decrease of the opening of the brake pedal 20.

[0133] If the rate at which the opening of the brake pedal 20 decreases is greater than a preset rate, then the vehicle 100 is determined to be in an emergency braking state, and the process proceeds to step S101-2; if the rate at which the opening of the brake pedal 20 decreases is less than or equal to a preset rate, then the vehicle 100 is determined to be in a non-emergency braking state, and the process proceeds to step S101-3.

[0134] In step S101-2, the positive torque output by the brake motor 401 is controlled to increase at a third rate as the opening of the brake pedal 20 increases.

[0135] In step S101-3, the positive torque output by the control brake motor 401 increases at a fourth rate as the opening of the brake pedal 20 increases.

[0136] The third rate is greater than the fourth rate.

[0137] In the embodiments of this application, the words "exemplary," "for example," etc., are used to indicate that they are examples, illustrations, or descriptions. Any embodiment or design that is described as "exemplary" in this application should not be construed as being more preferred or advantageous than other embodiments or design options. Specifically, the use of the term "exemplary" is intended to present the concept in a concrete manner.

[0138] It should be understood that the term "embodiment" used throughout this specification means that a specific feature, structure, or characteristic related to an embodiment is included in at least one embodiment of this application. Therefore, various embodiments throughout this specification do not necessarily refer to the same embodiment. Furthermore, these specific features, structures, or characteristics can be combined in any suitable manner in one or more embodiments.

[0139] It should also be understood that in this application, "when," "if," "in the circumstances of," and "if" all refer to a situation where a corresponding action will be taken under certain objective circumstances, and are not time-limited. They do not require the device to perform a judgment action, nor do they imply any other limitations. Furthermore, in this application, the descriptions of conditions such as "when," "if," "in the circumstances of," and "if" can be understood as necessary conditions, without limiting whether the condition is a sufficient condition or a necessary and sufficient condition. For example, "in the case of A, execute B" can be understood as "if at least A is satisfied, execute B."

[0140] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. An electromechanical brake system characterized by, The electromechanical brake system comprises a brake controller and at least one wheel-end brake device, the wheel-end brake device comprises a brake motor and an actuator, the brake motor is used to output a positive torque to the actuator to drive the actuator to output a clamping force to a brake disc, and the brake controller is used to: After the opening of the brake pedal starts to increase from zero and before the opening of the brake pedal starts to decrease, control the positive torque output by the brake motor to increase with the increase of the opening of the brake pedal; After the opening of the brake pedal starts to decrease, control the positive torque output by the brake motor to first decrease at a first rate and then decrease to zero at a second rate smaller than the first rate.

2. The electromechanical brake system of claim 1, wherein, The brake controller is specifically used to: After the opening of the brake pedal starts to decrease, control the positive torque to first decrease to zero before the opening of the brake pedal decreases to zero.

3. The electromechanical brake system of claim 1, wherein, The brake controller is specifically used to: After the opening of the brake pedal starts to decrease, control the positive torque to first decrease to zero before the opening of the brake pedal decreases to a preset opening greater than zero.

4. The electromechanical brake system of claim 1, wherein, The brake controller is specifically used to: After the positive torque output by the brake motor decreases to zero, control the brake motor to output a first reverse torque before the opening of the brake pedal decreases to zero.

5. The electromechanical brake system of claim 4, wherein, The brake controller is specifically used to: Control the first reverse torque to first increase and then decrease, and control the first reverse torque to decrease to zero at the moment when the opening of the brake pedal decreases to zero or after the opening of the brake pedal decreases to zero.

6. The electromechanical brake system of claim 5, wherein, The brake controller is specifically used to: After the first reverse torque decreases to zero, control the brake motor to output a second reverse torque.

7. The electromechanical brake system of claim 5, wherein, The brake controller is specifically used to: After the first reverse torque decreases to zero, control the brake motor to output a second reverse torque after the first reverse torque is maintained at zero for a preset time length.

8. The electromechanical brake system according to claim 6 or 7, characterized in that The brake controller is specifically used to: Control the second reverse torque to first increase and then decrease to zero.

9. The electromechanical brake system according to claim 6 or 7, characterized in that The brake controller is specifically used to: Control the peak value of the second reverse torque to be smaller than the peak value of the first reverse torque.

10. The electromechanical brake system of claim 1, wherein, The brake controller is specifically used to: Control the decreasing rate of the positive torque to increase with the increasing rate of the opening of the brake pedal.

11. The electromechanical brake system of claim 1, wherein, The brake controller is used to receive a torque signal of a vehicle controller, and the brake controller is specifically used to: During the process that the opening of the brake pedal decreases to zero, control the torque value of the positive torque to be different from the torque value indicated by the torque signal.

12. A control method of an electromechanical brake system, characterized by, The electromechanical brake system comprises a brake controller and at least one wheel-end brake device, the wheel-end brake device comprises a brake motor and an actuator, the brake motor is used to output a positive torque to the actuator to drive the actuator to output a clamping force to a brake disc, and the brake controller is used to: After the opening of the brake pedal starts to increase from zero and before the opening of the brake pedal starts to decrease, control the positive torque output by the brake motor to increase with the increase of the opening of the brake pedal; After the opening of the brake pedal starts to decrease, the positive torque output by the brake motor is first decreased at a first rate, and then decreased at a second rate smaller than the first rate to zero.

13. The control method according to claim 12, characterized by, The control method further comprises: After the opening of the brake pedal starts to decrease, the positive torque is first decreased to zero before the opening of the brake pedal decreases to zero.

14. The control method according to claim 12, characterized by, The control method further comprises: After the opening of the brake pedal starts to decrease, the positive torque is first decreased to zero before the opening of the brake pedal decreases to a preset opening greater than zero.

15. A vehicle characterized by comprising: The vehicle comprises an electromechanical brake system as claimed in any one of claims 1 to 11, or comprises a vehicle controller configured to perform a control method of an electromechanical brake system as claimed in any one of claims 12 to 14.

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