Electromechanical brake device, electric vehicle and braking control method thereof

Abstract

The application provides an electromechanical brake device, an electric vehicle and a brake control method thereof, and is applied to the technical field of electric vehicles to improve the brake accuracy of the electromechanical brake device when braking the wheels. The controller in the electromechanical brake device receives a first brake signal and controls the brake motor to output a first brake torque at the first time after the electromechanical brake device brakes the corresponding wheel. Then, at the second time after the first time, the second brake signal is received and the brake motor is controlled to output a second brake torque. The difference between the brake torque indicated by the first brake signal and the brake torque indicated by the second brake signal is less than a preset torque value, and the difference between the second brake torque and the first brake torque is greater than the preset torque value. Based on this, the electromechanical brake device can dynamically adjust the brake torque output by the brake motor according to the temperature change of the friction plate, thereby improving the brake accuracy of the electromechanical brake device when braking the wheels.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electric vehicles, and particularly relates to an electronic mechanical brake device, an electric vehicle and a brake control method thereof. BACKGROUND

[0002] With the development of electric vehicles, the brake system of the electric vehicle is iterated from the traditional hydraulic brake system to the electronic mechanical brake (EMB) system, which is the current mainstream trend. In the electronic mechanical brake system, a brake motor outputs a brake torque to drive the friction plate of an actuator to clamp the brake disc. Compared with the traditional hydraulic brake system, the electronic mechanical brake system can provide faster response speed and higher brake accuracy. However, due to the limited arrangement space of the wheel side in the electric vehicle, it is difficult to install a clamping force sensor and a temperature sensor, which leads to the inability to accurately measure and control the brake torque or clamping force output by the electronic mechanical brake system. In addition, as the temperature of the friction plate rises during the braking process, the brake effect generated by the friction plate changes, thereby affecting the brake accuracy of the electronic mechanical brake system. Therefore, there is an urgent need to provide a solution to solve the above problems. SUMMARY

[0003] The electronic mechanical brake device, the electric vehicle and the brake control method thereof provided by the embodiments of the present application can improve the brake accuracy of the electronic mechanical brake device in the braking process of the electric vehicle and improve the brake performance of the electric vehicle.

[0004] To achieve the above object, the embodiments of the present application provide the following technical solutions.

[0005] In a first aspect, the embodiments of the present application provide an electronic mechanical brake device for braking one wheel of an electric vehicle. The electronic mechanical brake device is further configured to receive a first brake signal and output a first brake torque at a first time after the electronic mechanical brake device continuously brakes. At a second time after the first time, the electronic mechanical brake device receives a second brake signal and outputs a second brake torque. The difference between the brake torque indicated by the first brake signal and the brake torque indicated by the second brake signal is less than or equal to a preset torque value, and the difference between the second brake torque and the first brake torque is greater than the preset torque value.

[0006] When the electronic mechanical brake device continuously brakes the one wheel, the friction between the brake disc of the one wheel and the friction plate of the actuator of the electronic mechanical brake device causes the temperature of the friction plate to rise, so that the actual clamping force provided by the friction plate does not match the expected clamping force corresponding to the brake torque indicated by the brake signal, affecting the braking accuracy of the electronic mechanical brake device when braking the wheel. The embodiment of the present application considers the influence of temperature, adjusts the brake torque output by the brake motor when the brake torque indicated by the brake signal is small, dynamically adjusts the clamping force of the friction plate according to the change of the temperature of the friction plate, improves the braking accuracy of the electronic mechanical brake device when braking the wheel, and thus improves the braking performance of the electric vehicle.

[0007] In an embodiment, the temperature of the friction plate is less than or equal to the thermal decay temperature of the friction plate when the duration of braking the one wheel by the electronic mechanical brake device is greater than the first preset duration and less than or equal to the second preset duration, and the temperature of the friction plate is greater than the thermal decay temperature of the friction plate when the duration of braking the one wheel by the electronic mechanical brake device is greater than the second preset duration. Based on this, the electronic mechanical brake device is further configured to output a second brake torque less than the first brake torque when the duration of braking the one wheel by the electronic mechanical brake device at the second time is greater than the first preset duration and less than or equal to the second preset duration. The electronic mechanical brake device outputs a second brake torque greater than the first brake torque when the duration of braking the one wheel by the electronic mechanical brake device at the second time is greater than the second preset duration.

[0008] In this way, the electronic mechanical brake device can appropriately reduce the brake torque output by the brake motor when the temperature of the friction plate is less than the thermal decay temperature of the friction plate. In addition, the electronic mechanical brake device can appropriately increase the brake torque output by the brake motor when the temperature of the friction plate is greater than the thermal decay temperature of the friction plate, so as to improve the braking accuracy of the electronic mechanical brake device when braking the wheel, thereby improving the braking performance of the electric vehicle.

[0009] In an embodiment, the electronic mechanical brake device is further configured to receive a third brake signal and output a third brake torque at a third time after the second time. The difference between the brake torque indicated by the third brake signal and the brake torque indicated by the second brake signal is greater than a preset torque value, the difference between the third brake torque and the second brake torque is greater than the preset torque value, and the difference between the third brake torque and the second brake torque is different from the difference between the brake torque indicated by the third brake signal and the brake torque indicated by the second brake signal.

[0010] When the stroke of the brake pedal changes, the brake torque indicated by the brake signal also changes. Because the clamping force output by the friction plate is affected by temperature, the electromechanical brake device adjusts the brake torque actually output by the brake motor on the basis of the brake torque indicated by the brake signal, thereby improving the braking precision of the electromechanical brake device when braking the wheel, and improving the braking performance of the electric vehicle.

[0011] In an embodiment, when the temperature of the friction plate at the third time is less than or equal to the thermal recession temperature of the friction plate, the electromechanical brake device is further configured to control the third brake torque to be less than the brake torque indicated by the third brake signal.

[0012] When the temperature of the friction plate at the third time is still less than or equal to the thermal recession temperature of the friction plate, if the brake motor drives the friction plate according to the brake torque indicated by the third brake signal, the actual clamping force provided by the friction plate is still greater than the expected clamping force corresponding to the brake torque indicated by the third brake signal. Therefore, the brake torque output by the brake motor needs to be appropriately reduced so that the actual clamping force provided by the friction plate is closer to the expected clamping force corresponding to the brake torque indicated by the third brake signal, thereby improving the braking precision of the electromechanical brake device when braking the wheel.

[0013] In an embodiment, when the temperature of the friction plate at the third time is still less than or equal to the thermal recession temperature of the friction plate, the electromechanical brake device is further configured to control the third brake torque to be greater than the second brake torque in response to the brake torque indicated by the third brake signal being greater than the brake torque indicated by the second brake signal. The increase of the third brake torque relative to the second brake torque is less than the increase of the brake torque indicated by the third brake signal relative to the brake torque indicated by the second brake signal. Alternatively, the electromechanical brake device is further configured to control the third brake torque to be less than the second brake torque in response to the brake torque indicated by the third brake signal being less than the brake torque indicated by the second brake signal. The decrease of the third brake torque relative to the second brake torque is greater than the decrease of the brake torque indicated by the third brake signal relative to the brake torque indicated by the second brake signal.

[0014] In this way, when the temperature of the friction plate is less than or equal to the thermal recession temperature of the friction plate and the stroke of the brake pedal changes, the electromechanical brake device can adjust the brake torque output according to the influence of temperature on the friction coefficient of the friction plate, so that the actual clamping force of the friction plate is closer to the expected clamping force corresponding to the brake torque indicated by the brake signal.

[0015] In an embodiment, when the temperature of the friction plate at the third time is greater than the thermal recession temperature of the friction plate, the electromechanical brake device is further configured to control the third brake torque to be greater than the brake torque indicated by the third brake signal. In an embodiment, when the temperature of the friction plate at the third time is greater than the thermal recession temperature of the friction plate, the electromechanical brake device is further configured to control the third brake torque to be greater than the brake torque indicated by the third brake signal.

[0016] When the temperature of the friction plate at the third moment is greater than the thermal recession temperature of the friction plate, the friction coefficient of the friction plate gradually decreases with the increase of the temperature, resulting in that the actual clamping force provided by the friction plate is less than the expected clamping force corresponding to the brake torque indicated by the third brake signal. Therefore, it is necessary to appropriately increase the brake torque output by the brake motor in the electromechanical brake device so that the actual clamping force provided by the friction plate is closer to the expected clamping force corresponding to the brake torque indicated by the third brake signal, thereby improving the braking accuracy of the electromechanical brake device when braking the wheels.

[0017] In an embodiment, in the case that the temperature of the friction plate at the third moment is greater than the thermal recession temperature of the friction plate, the electromechanical brake device further controls the third brake torque to be greater than the second brake torque in response to the brake torque indicated by the third brake signal being greater than the brake torque indicated by the second brake signal, and the increase value of the third brake torque relative to the second brake torque is greater than the increase value of the brake torque indicated by the third brake signal relative to the brake torque indicated by the second brake signal. Alternatively, the electromechanical brake device controls the third brake torque to decrease by a value less than the decrease value of the brake torque indicated by the third brake signal relative to the brake torque indicated by the second brake signal in response to the brake torque indicated by the third brake signal being less than the brake torque indicated by the second brake signal.

[0018] In this way, when the stroke of the brake pedal changes in the case that the temperature of the friction plate at the third moment is greater than the thermal recession temperature of the friction plate, the electromechanical brake device can also adjust the output brake torque according to the influence of the temperature on the friction coefficient of the friction plate, so that the actual clamping force of the friction plate is closer to the expected clamping force corresponding to the brake torque indicated by the brake signal.

[0019] In an embodiment, the electromechanical brake device comprises a wheel end controller, a brake motor and an actuator. The wheel end controller is configured to control the brake motor to output a brake torque according to a brake torque indicated by a received brake signal, the brake motor is configured to output the brake torque to drive the actuator, and the actuator is configured to drive a brake disc of a brake pad to clamp a brake disc of a wheel according to the brake torque output by the brake motor. The wheel end controller comprises a temperature estimation module, a clamping force compensation module, a clamping force calculation module, a fusion module and a control signal output module. The temperature estimation module is configured to calculate a temperature estimation value of the brake pad according to a clamping force value of the brake pad at a first time, a wheel speed of the wheel at a second time and an ambient temperature of the electric vehicle. The clamping force compensation module is configured to calculate a clamping force compensation value of the brake pad according to the temperature estimation value. The clamping force calculation module is configured to calculate a clamping force reference value of the brake pad according to an angle of rotation of the brake motor at the second time. The fusion module is configured to calculate a clamping force estimation value of the brake pad according to the clamping force compensation value and the clamping force reference value. The control signal output module is configured to output a control signal of the brake motor according to the clamping force estimation value, and the control signal is configured to control the brake motor to output a second brake torque.

[0020] In this way, the wheel end controller can estimate the temperature of the brake pad according to the wheel speed of the wheel, the ambient temperature of the electric vehicle and the first brake signal, so as to compensate the clamping force according to the change relationship between the temperature of the brake pad and the clamping force compensation value, and adjust the control signal output to the brake motor according to the compensated clamping force estimation value,

[0021] In an embodiment, the control signal output module comprises a torque balance calculation submodule, a Kalman filtering submodule and a signal generation submodule. The torque balance calculation submodule is configured to calculate another clamping force estimation value of the brake pad according to a transmission ratio of the actuator, a moment of inertia of the brake motor, a friction force of the brake pad at the second time, the angle of rotation of the brake motor at the second time and the brake torque. The Kalman filtering submodule is configured to perform Kalman filtering on the clamping force estimation value and the another clamping force estimation value to obtain a target clamping force estimation value of the brake pad. The signal generation submodule is configured to generate the control signal according to the target clamping force estimation value, or to perform verification on the target clamping force estimation value and a brake torque estimation value of the brake motor at the second time to obtain another target clamping force estimation value, and generate the control signal according to the another target clamping force estimation value.

[0022] In this way, the wheel end controller calculates a target clamping force estimate value according to the one clamping force estimate value and the other clamping force estimate value through Kalman filtering, and then outputs a control signal to the brake motor according to the target clamping force estimate value, so that the actual clamping force provided by the friction plate can be closer to the expected clamping force corresponding to the brake torque indicated by the brake signal. In addition, the wheel end controller further checks the one target clamping force estimate value and the brake torque estimate value sent by the brake controller, and outputs a control signal to the brake motor according to the other target clamping force estimate value after the check, so that the actual clamping force of the friction plate can be further closer to the expected clamping force corresponding to the brake torque indicated by the brake signal.

[0023] In a second aspect, the embodiments of the present application provide an electric vehicle, which comprises a plurality of wheels and a plurality of electronic mechanical brake devices as described in any of the embodiments of the first aspect. The plurality of electronic mechanical brake devices are used to brake the plurality of wheels respectively during braking of the electric vehicle.

[0024] The technical principles and beneficial effects of the second aspect described above can be referred to the related description of the first aspect, which will not be repeated here.

[0025] In a third aspect, the embodiments of the present application provide a brake control method of an electric vehicle, which is used to adjust brake torques output by a plurality of electronic mechanical brake devices during continuous braking of the electric vehicle. The brake control method comprises:

[0026] At a first time after continuous braking of the electric vehicle, a first brake torque is output by one or more electronic mechanical brake devices according to a first brake signal, and a difference between the first brake torque and a brake torque indicated by the first brake signal is less than or equal to a preset torque value.

[0027] At a second time after the first time, a second brake torque is output by at least one electronic mechanical brake device according to a second brake signal, a difference between a brake torque indicated by the second brake signal and the brake torque indicated by the first brake signal is less than or equal to the preset torque value, and a difference between the second brake torque and the brake torque indicated by the second brake signal is greater than the preset torque value.

[0028] At a third time after the second time, a third brake torque is output by at least one electronic mechanical brake device according to a third brake signal, a difference between a brake torque indicated by the third brake signal and the brake torque indicated by the second brake signal is greater than the preset torque value, a difference between the third brake torque and the brake torque indicated by the third brake signal is greater than the preset torque value, and the difference between the third brake torque and the brake torque indicated by the third brake signal is different from the difference between the brake torque indicated by the third brake signal and the brake torque indicated by the second brake signal.

[0029] The brake force distribution of the electric vehicle braking process usually causes the brake torques output by the multiple electronic mechanical brake devices to be different during the braking process, causing the temperature rise of different electronic mechanical brake devices at the same time to be inconsistent. In the above manner, during the continuous braking process of the electric vehicle, the brake torques output by the multiple electronic mechanical brake devices can be differentially controlled according to the actual braking situation, so that the actual clamping force provided by the actuators of each electronic mechanical brake device is closer to the expected clamping force corresponding to the brake torque indicated by the brake signal, thereby improving the braking accuracy of the electric vehicle and improving the braking performance of the electric vehicle.

[0030] In an embodiment, the above brake control method further comprises: at a second time after the first time, controlling the difference between the brake torque output by the other electronic mechanical brake devices in the multiple electronic mechanical brake devices except for the at least one electronic mechanical brake device and the second brake torque to be greater than the preset torque value according to the second brake signal.

[0031] In the above manner, in the case that the temperature of the at least one electronic mechanical brake device is different from that of the other electronic mechanical brake devices, the brake torque output by the at least one electronic mechanical brake device and the brake torque output by the other electronic mechanical brake devices can be differentially controlled, so that the actual clamping force provided by the actuators of each electronic mechanical brake device is closer to the expected clamping force corresponding to the brake torque indicated by the brake signal, thereby improving the braking accuracy of the electric vehicle and improving the braking performance of the electric vehicle.

[0032] In an embodiment, at the second time, the temperature of the friction plate corresponding to the at least one electronic mechanical brake device rises and the temperature value is less than the thermal decay temperature, and the temperature value of the friction plate corresponding to the at least one electronic mechanical brake device is greater than that of the friction plate corresponding to the other electronic mechanical brake devices, and the brake control method further comprises: at the second time, controlling the second brake torque output by the at least one electronic mechanical brake device to be less than the brake torque indicated by the second brake signal and the first brake torque, and controlling the difference between the brake torque output by the other electronic mechanical brake devices and the brake torque indicated by the second brake signal to be less than the difference between the second brake torque output by the at least one electronic mechanical brake device and the brake torque indicated by the second brake signal.

[0033] In the case that the temperatures of the friction plates corresponding to the respective electronic mechanical brake devices are all lower than the thermal recession temperature of the friction plate, the friction coefficient of the friction plate gradually increases with the increase of the temperature, resulting in that the actual clamping force of the friction plate is greater than the expected clamping force corresponding to the brake torque indicated by the brake signal. Based on this, in the case that the temperature value of the friction plate corresponding to the at least one electronic mechanical brake device is greater than the temperature value of the friction plate corresponding to the other electronic mechanical brake device, the reduction value of the brake torque of the at least one electronic mechanical brake device needs to be greater to make the actual clamping force of the corresponding friction plate closer to the expected clamping force corresponding to the brake torque indicated by the second brake signal, thereby improving the braking accuracy of the electric vehicle and improving the braking performance of the electric vehicle.

[0034] In an embodiment, at the second time, the temperatures of the friction plates corresponding to the respective electronic mechanical brake devices increase and the temperature values are greater than the thermal recession temperature, and the temperature value of the friction plate corresponding to the at least one electronic mechanical brake device is less than the temperature value of the friction plate corresponding to the other electronic mechanical brake device. The brake control method further comprises: at the second time, controlling the second brake torque output by the at least one electronic mechanical brake device to be greater than the brake torque indicated by the second brake signal and the first brake torque, and controlling the difference between the brake torque output by the other electronic mechanical brake device and the brake torque indicated by the second brake signal to be greater than the difference between the second brake torque output by the at least one electronic mechanical brake device and the brake torque indicated by the second brake signal.

[0035] In the case that the temperatures of the friction plates corresponding to the respective electronic mechanical brake devices increase and the temperature values are greater than the thermal recession temperature, the friction coefficient of the friction plate gradually decreases with the increase of the temperature, and the brake torque output by the plurality of electronic mechanical brake devices needs to be greater than the brake torque indicated by the second brake signal to make the actual clamping force of the corresponding friction plate closer to the expected clamping force corresponding to the brake torque indicated by the second brake signal. Based on this, in the case that the temperature value of the friction plate corresponding to the at least one electronic mechanical brake device is less than the temperature value of the friction plate corresponding to the other electronic mechanical brake device, the friction coefficient of the friction plate corresponding to the at least one electronic mechanical brake device is greater than the friction coefficient of the friction plate corresponding to the other electronic mechanical brake device. Therefore, the reduction value of the brake torque indicated by the second brake signal with respect to the other electronic mechanical brake device needs to be greater than the difference between the second brake torque output by the at least one electronic mechanical brake device and the brake torque indicated by the second brake signal, thereby improving the braking accuracy of the electric vehicle and improving the braking performance of the electric vehicle.

[0036] In one embodiment, at the third time, the temperature of the friction plate corresponding to the at least one electronic mechanical brake device is further increased and the temperature value is greater than the thermal recession temperature, the temperature of the friction plate corresponding to the other electronic mechanical brake device is further increased and the temperature value is less than the thermal recession temperature, and the brake control method further comprises:

[0037] In response to the brake torque indicated by the third brake signal being greater than the brake torque indicated by the second brake signal, the increase value of the third brake torque output by the at least one electronic mechanical brake device relative to the second brake torque is controlled to be greater than the difference between the brake torque indicated by the third brake signal and the brake torque indicated by the second brake signal, and the increase value of the brake torque output by the other electronic mechanical brake device is controlled to be less than the difference between the brake torque indicated by the third brake signal and the brake torque indicated by the second brake signal.

[0038] In response to the brake torque indicated by the third brake signal being less than the brake torque indicated by the second brake signal, the decrease value of the third brake torque output by the at least one electronic mechanical brake device relative to the second brake torque is controlled to be less than the difference between the brake torque indicated by the third brake signal and the brake torque indicated by the second brake signal, and the decrease value of the brake torque output by the other electronic mechanical brake device is controlled to be greater than the difference between the brake torque indicated by the third brake signal and the brake torque indicated by the second brake signal.

[0039] In this way, when the temperature of the friction plate corresponding to the at least one electronic mechanical brake device is greater than the thermal recession temperature and the temperature of the friction plate corresponding to the other electronic mechanical brake device is less than the thermal recession temperature at the third time, different control strategies can be adopted for the brake torque output by each electronic mechanical brake device according to the change in the stroke of the brake pedal, so as to improve the brake accuracy during the braking process of the electric vehicle and improve the braking performance of the electric vehicle. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 A schematic diagram of an electric vehicle provided by an embodiment of the present application;

[0041] Figure 2 Another schematic diagram of an electric vehicle provided by an embodiment of the present application;

[0042] Figure 3 A schematic diagram of an electronic mechanical brake system provided by an embodiment of the present application;

[0043] Figure 4 A schematic diagram of an electronic mechanical brake device provided by an embodiment of the present application;

[0044] Figure 5 A schematic diagram of a brake control process of an electric vehicle provided by an embodiment of the present application;

[0045] Figure 6 Another schematic diagram of a braking control process of an electric vehicle provided by an embodiment of the present application;

[0046] Figure 7 Another schematic diagram of a braking control process of an electric vehicle provided by an embodiment of the present application;

[0047] Figure 8 Another schematic diagram of a braking control process of an electric vehicle provided by an embodiment of the present application;

[0048] Figure 9 Another schematic diagram of a braking control process of an electric vehicle provided by an embodiment of the present application;

[0049] Figure 10 Another schematic diagram of a braking control process of an electric vehicle provided by an embodiment of the present application;

[0050] Figure 11 Another schematic diagram of an electromechanical brake device provided by an embodiment of the present application;

[0051] Figure 12 Another schematic diagram of an electromechanical brake device provided by an embodiment of the present application;

[0052] Figure 13 Another schematic diagram of an electromechanical brake device provided by an embodiment of the present application. DETAILED DESCRIPTION

[0053] In the present application, “in an embodiment” is used to indicate by example, illustration or description. The solution described as “in an embodiment” in the present application should not be interpreted as more preferred or more advantageous than the solution of other embodiments. Rather, “in an embodiment” is used to present the inventive concept of the present application in a specific manner.

[0054] In the braking device of the electric vehicle, the friction coefficient of the friction plate changes with the temperature of the friction plate. When the temperature of the friction plate is less than or equal to the thermal recession temperature of the friction plate, the friction coefficient of the friction plate increases, resulting in that the actual clamping force of the friction plate is greater than the clamping force corresponding to the brake torque indicated by the brake signal. When the temperature of the friction plate is greater than the thermal recession temperature of the friction plate, the friction coefficient of the friction plate decreases, resulting in that the actual clamping force of the friction plate is less than the clamping force corresponding to the brake torque indicated by the brake signal.

[0055] In the driving process of the electric vehicle, when the driver steps on the brake pedal for a long time to brake the electric vehicle, the friction between the friction plate of the braking device and the brake disc of the wheel for a long time will cause the temperature of the friction plate to rise, thereby affecting the friction coefficient of the friction plate, resulting in deviation of the braking effect, and thereby affecting the braking performance of the electric vehicle.

[0056] Due to the limited space at the wheel end of electric vehicles, temperature and clamping force sensors cannot be installed on the brake discs, friction pads, or electromechanical braking devices, making it impossible to accurately measure the temperature and clamping force of the friction pads. Therefore, during braking, electric vehicles struggle to adjust the clamping force of the friction pads based on temperature changes, leading to discrepancies between the calibrated clamping force and the actual clamping force provided by the friction pads to the brake disc. This results in deviations in braking performance and negatively impacts the braking capabilities of the electric vehicle.

[0057] To address the aforementioned problems, this application provides an electromechanical braking device and a braking control method for an electric vehicle. During braking, the braking torque output by the electromechanical braking device can be dynamically adjusted according to the temperature change of the friction pads. This allows for dynamic adjustment of the clamping force of the friction pads based on their temperature changes during prolonged driver braking, thereby improving the braking performance of the electric vehicle.

[0058] The technical solutions in the embodiments of this application will now be described with reference to the accompanying drawings.

[0059] Figure 1 This is a schematic diagram of an electric vehicle provided in an embodiment of this application. Figure 1 As shown, the electric vehicle includes a drive system 100, a braking system 200, and a power battery 300. The drive system 100 drives the wheels of the electric vehicle to propel it. The braking system 200 brakes the wheels of the electric vehicle to decelerate it. The power battery 300 supplies power to the drive system 100 and the braking system 200.

[0060] Figure 2 Another schematic diagram of an electric vehicle provided in an embodiment of this application.

[0061] In one embodiment, the drive system 100 includes a motor controller 110, a drive motor 120, and a reducer 130. For example... Figure 2 As shown, the motor controller 110 receives DC power from the power battery 300 and outputs AC power to control the drive motor 120 to output drive torque. The drive motor 120 drives the wheels of the electric vehicle through the reducer 130.

[0062] In one embodiment, the electric vehicle further includes a temperature sensor 140. For example... Figure 2 As shown, temperature sensor 140 is used to detect the ambient temperature T of the electric vehicle. a .like Figure 11 As shown, the braking system 200 is used to measure the ambient temperature T of the electric vehicle detected by the temperature sensor 140. a Adjust the braking torque output of brake motor 222.

[0063] In an embodiment, the electric vehicle further comprises a wheel speed sensor 150. As shown in Figure 2 , the wheel speed sensor 150 is configured to detect a wheel speed V L of the electric vehicle. Figure 11 As shown in Figure 11 , the brake system 200 is configured to adjust the brake torque output by the brake motor 222 according to the wheel speed V L of the electric vehicle detected by the wheel speed sensor 150.

[0064] In an embodiment, the electric vehicle further comprises an inertial measurement unit 160. As shown in Figure 2 , the inertial measurement unit 160 is configured to detect an acceleration a and a yaw rate Y v of the electric vehicle. The brake system 200 is configured to adjust the brake torque output by the brake motor 222 according to the acceleration a and the yaw rate Y v of the electric vehicle detected by the inertial measurement unit 160.

[0065] In an embodiment, the brake system 200 comprises a plurality of electromechanical brake devices 220. The plurality of electromechanical brake devices 220 are configured to brake a plurality of wheels 250 of the electric vehicle respectively during braking of the electric vehicle.

[0066] Figure 3 An embodiment of the electromechanical brake system provided in the present application is shown in Figure 3 . The electric vehicle further comprises four wheels 250. Four electromechanical brake devices 220 are configured to brake the four wheels 250 of the electric vehicle respectively. Each electromechanical brake device 220 is configured to brake one wheel 250 of the electric vehicle.

[0067] In an embodiment, the two wheels 250 corresponding to the front axle 230 of the electric vehicle are the left front wheel LF and the right front wheel RF, and the two wheels 250 corresponding to the rear axle 240 of the electric vehicle are the left rear wheel LR and the right rear wheel RR. Two electromechanical brake devices 220 are configured to brake the left front wheel LF and the right front wheel RF of the electric vehicle respectively, and the other two electromechanical brake devices 220 are configured to brake the left rear wheel LR and the right rear wheel RR of the electric vehicle respectively.

[0068] As shown in Figure 3 , the electromechanical brake system 200 further comprises one or more brake controllers 260. The brake controller 260 sends a brake signal to the electromechanical brake device 220 after the driver steps on the brake pedal. In an embodiment of the present application, each brake controller 260 is configured to output a brake signal to control one or more electromechanical brake devices 220.

[0069] In one embodiment, the electromechanical brake system 200 includes one brake controller 260 and four electromechanical brake devices 220. After the driver steps on the brake pedal, the brake controller 260 controls the four electromechanical brake devices 220 to brake the four wheels 250 of the electric vehicle respectively.

[0070] In one embodiment, the electromechanical brake system 200 includes two brake controllers 260 and four electromechanical brake devices 220. After the driver steps on the brake pedal, one brake controller 260 controls two electromechanical brake devices 220 to brake the two front wheels of the electric vehicle, and the other brake controller 260 controls the other two electromechanical brake devices 220 to brake the two rear wheels of the electric vehicle.

[0071] In one embodiment, the electromechanical brake system 200 includes four brake controllers 260 and four electromechanical brake devices 220. After the driver steps on the brake pedal, the four brake controllers 260 control the four electromechanical brake devices 220 to brake the four wheels 250 of the electric vehicle respectively.

[0072] In one embodiment, the brake controller 260 is a central controller or vehicle control unit (VCU) in the electric vehicle.

[0073] In one embodiment, the motor controller 110 in the drive system 100 and the brake controller 260 in the brake system 200 are fused into a domain control unit (DCU) in the electric vehicle.

[0074] Figure 4 A schematic diagram of an electromechanical brake device is provided for the embodiments of the present application. The electromechanical brake device 220 includes a wheel-end controller 221, a brake motor 222, and an actuator 223. As shown, the wheel-end controller 221 is configured to receive a brake signal output by the brake controller 260 and to output a control signal to control the brake motor 222. The brake motor 222 is configured to output a brake torque to drive the actuator 223. The actuator 223 is configured to drive a brake pad to clamp a brake disc of a corresponding wheel according to the brake torque output by the brake motor 222. Figure 4

[0075] In one embodiment, the wheel-end controller 221 in the electromechanical brake device 220 includes the brake controller 260 in the electromechanical brake system 200. The brake controller 260 in the electromechanical brake system 200 is configured to output a brake signal to control the brake motor 222.

[0076] ​In one embodiment, the electric vehicle uses the same wheel end controller 221 or brake controller 260 to control the brake motor 222 of the four electromechanical brake devices 220.

[0077] In one embodiment, the electromechanical brake device 220 adjusts the clamping force of the friction plate by adjusting the brake torque output by the brake motor 222 during braking of the electric vehicle. In this embodiment, the wheel end controller 221 actively adjusts the brake torque output by the brake motor 222 according to the brake torque indicated by the brake signal output by the brake controller 260 before controlling the actual brake torque output by the brake motor 222 during braking of the electric vehicle.

[0078] In one embodiment, the electromechanical brake device 220 further includes a position sensor 224. The position sensor 224 is configured to detect the rotation angle and rotation speed of the brake motor 222. In this embodiment, the position sensor 224 includes a resolver. As shown in FIG. 2B, the wheel end controller 221 is configured to adjust the brake torque output by the brake motor 222 according to the rotation angle and rotation speed of the brake motor 222 detected by the position sensor 224. Figure 4

[0079] In one embodiment, the electromechanical brake device 220 further includes a torque sensor 225. The torque sensor 225 is configured to detect the brake torque output by the brake motor 222. In this embodiment, the torque sensor 225 includes a current sensor. As shown in FIG. 2C, the wheel end controller 221 can calculate the brake torque output by the brake motor 222 according to the product of the current of the brake motor 222 detected by the torque sensor 225 and the torque coefficient of the brake motor 222. Figure 4

[0080] In one embodiment, the wheel end controller 221 is configured to adjust the brake torque output by the brake motor 222 according to the brake torque output by the brake motor 222 detected by the torque sensor 225.

[0081] After the electric vehicle is continuously braked, i.e., after the driver continuously steps on the brake pedal, the duration for which the electromechanical brake device 220 brakes the corresponding wheel increases as the duration for which the electric vehicle is continuously braked increases or as the driver further steps on the brake pedal, and the temperature of the friction plate gradually increases. In this embodiment, the duration for which the electromechanical brake device 220 brakes the corresponding wheel is greater than the first preset duration and less than or equal to the second preset duration, and the temperature of the friction plate increases to be less than or equal to the thermal decay temperature of the friction plate. When the duration for which the electromechanical brake device 220 brakes the corresponding wheel is greater than the second preset duration, the temperature of the friction plate increases to be greater than the thermal decay temperature of the friction plate.

[0082] ​​To facilitate understanding of the electromechanical braking device and electric vehicle braking control method provided in the embodiments of this application, the electromechanical braking device and electric vehicle braking control method provided in the embodiments of this application are described below in conjunction with the first time t1, the second time t2 and the third time t3 during the braking process of the electric vehicle.

[0083] At a first moment t1 after the electromechanical braking device 220 continuously brakes a wheel 250, the wheel end controller 221 receives a first braking signal; at a second moment t2 after the first moment t1, the wheel end controller 221 receives a second braking signal; and at a third moment t3 after the second moment t2, the wheel end controller 221 receives a third braking signal.

[0084] In one embodiment, at a first moment t1 after the electromechanical braking device 220 continuously brakes a wheel 250, the wheel end controller 221 receives a first braking signal and controls the brake motor 222 to output a first braking torque b1.

[0085] In one embodiment, at a first moment t1, the duration of braking of the wheel by the electromechanical braking device 220 is greater than a first preset duration and less than or equal to a second preset duration. Correspondingly, the temperature of the friction pad rises to a level less than or equal to the thermal decay temperature of the friction pad.

[0086] Figure 5 This is a schematic diagram of the braking control process of an electric vehicle provided in an embodiment of this application. Figure 5 As shown, at the first moment t1 after continuous braking of the electric vehicle, the wheel-end controller 221 receives the first braking signal and controls the brake motor 222 to output the first braking torque b1. This first braking torque b1 is less than the braking torque a1 indicated by the first braking signal.

[0087] Correspondingly, at the first moment after continuous braking, the wheel end controller 221 actively reduces the braking torque output by the brake motor to prevent the clamping force of the friction pads from increasing with the temperature of the friction pads, thereby improving the braking accuracy of the electric vehicle after long-term braking and improving the braking performance of the electric vehicle.

[0088] In one embodiment, at the second time t2, the duration of continuous braking of the wheel corresponding to the electromechanical braking device 220 is still greater than the first preset duration and less than or equal to the second preset duration. The travel of the brake pedal at the second time t2 remains unchanged relative to the travel of the brake pedal at the first time t1, and the braking torque a2 indicated by the second braking signal is equal to the braking torque a1 indicated by the first braking signal.

[0089] like Figure 5As shown, at the second time t2 after the first time t1, the wheel-end controller 221 receives the second braking signal and controls the brake motor 222 to output the second braking torque b2. The difference between the braking torque a1 indicated by the first braking signal and the braking torque a2 indicated by the second braking signal is less than a preset torque value. The difference between the second braking torque b2 and the first braking torque b1 is greater than the preset torque value.

[0090] At the second moment t2 after continuous braking, the temperature of the friction pads increases relative to the first moment t1. The braking torque a2 indicated by the second braking signal received by the wheel end controller 221 at the second moment t2 does not change relative to the braking torque a1 indicated by the first braking signal received at the first moment t1. If the braking torque output by the brake motor 222 remains unchanged, the actual clamping force of the friction pads before adjustment at the second moment t2 will increase relative to the clamping force at the first moment t1, resulting in a decrease in the braking accuracy of the electric vehicle after long-term braking.

[0091] In this embodiment, the wheel-end controller 221 actively adjusts the braking torque output of the brake motor 222 at the second time t2, so that the second braking torque b2 output by the brake motor 222 at the second time t2 is different from the first braking torque b1 output at the first time t1. This makes the actual clamping force of the friction pad at the second time t2 consistent with the actual clamping force at the first time t1, thereby improving the braking accuracy of the electric vehicle after long-term braking and improving the braking performance of the electric vehicle.

[0092] In one embodiment, at the second time t2, the duration of continuous braking of the wheel by the electromechanical braking device 220 is still greater than the first preset duration and less than or equal to the second preset duration. Correspondingly, the temperature of the friction pad is less than or equal to the thermal decay temperature of the friction pad.

[0093] like Figure 5 As shown, at the second time t2, the wheel end controller 221 controls the brake motor 222 to output a second braking torque b2 that is less than the braking torque a2 indicated by the second braking signal and the first braking torque b1 output at the first time t1.

[0094] In this embodiment, the wheel end controller 221 actively reduces the braking torque output by the brake motor 222 at the second time t2, thereby ensuring that the clamping force of the adjusted friction pad at the second time t2 remains consistent with the clamping force at the first time t1, improving the braking accuracy of the electric vehicle after continuous braking and enhancing the braking performance of the electric vehicle.

[0095] In one embodiment, at a third time t3 after the second time t2, the difference between the braking torque a3 indicated by the third braking signal and the braking torque a2 indicated by the second braking signal is greater than a preset torque value. The wheel-end controller 221 controls the brake motor 222 to output a third braking torque b3 at the third time t3. The difference between the third braking torque b3 and the second braking torque b2 is greater than the preset torque value. The difference b32 between the third braking torque b3 and the second braking torque b2 is different from the difference a32 between the braking torque a3 indicated by the third braking signal and the braking torque a2 indicated by the second braking signal.

[0096] In one embodiment, at the third time t3, the duration of continuous braking of the wheel by the electromechanical braking device 220 is still greater than the first preset duration and less than or equal to the second preset duration. Correspondingly, the temperature of the friction pad is less than or equal to the thermal decay temperature of the friction pad.

[0097] In one embodiment, the travel of the brake pedal at the third time t3 is greater than the travel of the brake pedal at the second time t2, and the braking torque a3 indicated by the third brake signal is greater than the braking torque a2 indicated by the second brake signal.

[0098] like Figure 5 As shown, at the third time t3 after the second time t2, the braking torque a3 indicated by the third braking signal is greater than the braking torque a2 indicated by the second braking signal. Correspondingly, the third braking torque b3 output by the wheel-end controller 221 controlling the brake motor 222 at the third time t3 is less than the braking torque a3 indicated by the third braking signal. The third braking torque b3 is greater than the second braking torque b2. The difference b32 between the third braking torque b3 and the second braking torque b2 is less than the difference a32 between the braking torque a3 indicated by the third braking signal and the braking torque a2 indicated by the second braking signal.

[0099] At the third moment t3 after continuous braking, the temperature of the friction pads increases further compared to the second moment t2, and the friction coefficient of the friction pads increases further. At the third moment t3, the travel of the brake pedal increases, and the brake motor 222 increases the output braking torque accordingly according to the difference a32. This will cause the actual clamping force of the friction pads at the third moment t3 before adjustment to be greater than the expected clamping force, resulting in a decrease in the braking accuracy of the electric vehicle after long-term braking.

[0100] In this embodiment, the wheel end controller 221 actively reduces the increase value b32 of the braking torque output by the brake motor 222 at the third time t3, so that the clamping force of the adjusted friction pad at the third time t3 meets the expected clamping force, thereby improving the braking performance of the electric vehicle.

[0101] In one embodiment, the stroke of the brake pedal at the third time t3 is reduced relative to the stroke of the brake pedal at the second time t2, and the brake torque a1 indicated by the first brake signal is less than the brake torque a2 indicated by the second brake signal.

[0102] Figure 6 Another schematic diagram of the brake control process of the electric vehicle is provided in an embodiment of the present application. As shown in Figure 6 the third brake torque b3 output by the wheel end controller 221 at the third time t3 is less than the brake torque a3 indicated by the third brake signal. The third brake torque b3 is less than the second brake torque b2. The difference b32 between the third brake torque b3 and the second brake torque b2 is greater than the difference a32 between the brake torque a3 indicated by the third brake signal and the brake torque a2 indicated by the second brake signal.

[0103] At the third time t3 after the sustained braking, the temperature of the friction plate is further increased relative to the second time t2, the friction coefficient of the friction plate is further increased, the stroke of the brake pedal at the third time t3 is reduced, and the brake torque output by the brake motor 222 is correspondingly reduced by the difference a32, which will result in that the actual clamping force of the adjusted friction plate at the third time t3 is less than the expected clamping force, resulting in a decrease in braking accuracy.

[0104] In an embodiment of the present application, the wheel end controller 221 actively increases the increase value b32 of the brake torque output by the brake motor 222 at the third time t3, so that the actual clamping force of the adjusted friction plate at the third time t3 conforms to the expected clamping force, thereby improving the braking performance of the electric vehicle.

[0105] In one embodiment, the duration of the sustained braking of the corresponding wheel by the electromechanical brake device 220 at the second time t2 is greater than the second preset duration. Correspondingly, the temperature of the friction plate is greater than the thermal recession temperature of the friction plate.

[0106] In one embodiment, the stroke of the brake pedal at the second time t2 remains unchanged relative to the stroke of the brake pedal at the first time t1, and the brake torque a1 indicated by the first brake signal is equal to the brake torque a2 indicated by the second brake signal.

[0107] Figure 7 Another schematic diagram of the brake control process of the electric vehicle is provided in an embodiment of the present application. As shown in Figure 7As shown, at a second time t2 after the first time t1, the wheel end controller 221 receives a second brake signal and controls the brake motor 222 to output a second brake torque b2. Wherein the difference between the brake torque a1 indicated by the first brake signal and the brake torque a2 indicated by the second brake signal is less than a preset torque value, the wheel end controller 221 controls the brake motor 222 to output the second brake torque b2 with a difference from the first brake torque b1 greater than the preset torque value. The wheel end controller 221 controls the brake motor 222 to output the second brake torque b2 greater than the first brake torque b1.

[0108] At the second time t2 after the continuous braking, the temperature of the friction plate further increases to be greater than the thermal recession temperature of the friction plate relative to the first time t1, and the friction coefficient of the friction plate decreases. The brake torque a2 indicated by the second brake signal received by the wheel end controller 221 at the second time t2 does not change relative to the brake torque a1 indicated by the first brake signal received at the first time t1. If the brake torque output by the brake motor 222 remains unchanged, the clamping force of the friction plate at the second time t2 after adjustment will decrease relative to the clamping force at the first time t1, so that the actual clamping force of the friction plate at the second time t2 is less than the expected clamping force, resulting in that the braking effect of the electric vehicle does not meet the expectation of the driver.

[0109] In the embodiment of the present application, the wheel end controller 221 actively adjusts the brake torque output by the brake motor 222 at the second time t2, so that the second brake torque b2 output at the second time t2 is greater than the first brake torque b1 output at the first time t1, thereby keeping the actual clamping force of the friction plate at the second time t2 consistent with the clamping force at the first time t1 after adjustment, ensuring that the braking effect of the electric vehicle meets the expectation of the driver, thereby improving the braking performance of the electric vehicle.

[0110] At a third time t3, the duration of the continuous braking of the corresponding wheel by the electromechanical brake device 220 is greater than a second preset duration. Correspondingly, the temperature of the friction plate is greater than the thermal recession temperature of the friction plate. Correspondingly, the wheel end controller 221 receives a third brake signal and controls the brake motor 222 to output a third brake torque b3, which is greater than the brake torque a3 indicated by the third brake signal.

[0111] In one embodiment, at a third time t3 after the second time t2, the stroke of the brake pedal increases relative to the stroke of the brake pedal at the second time t2, and the brake torque a3 indicated by the third brake signal is greater than the brake torque a2 indicated by the second brake signal.

[0112] As Figure 7As shown, at the third time t3 after the second time t2, the third brake torque a3 indicated by the third brake signal is greater than the second brake torque a2 indicated by the second brake signal. The third brake torque b3 is greater than the second brake torque b2. The difference b32 between the third brake torque b3 and the second brake torque b2 is greater than the difference a32 between the third brake torque a3 indicated by the third brake signal and the second brake torque a2 indicated by the second brake signal.

[0113] At the third time t3 after the sustained braking, the temperature of the friction plate further increases relative to the second time t2 to be greater than the thermal recession temperature of the friction plate, the friction coefficient of the friction plate decreases, the stroke of the brake pedal at the third time t3 increases, and the brake motor 222 correspondingly increases the output brake torque according to the difference a32, which will cause the actual clamping force of the adjusted friction plate at the third time t3 to be less than the expected clamping force, resulting in the braking effect of the electric vehicle not meeting the expectation of the driver.

[0114] In the embodiment of the present application, the wheel end controller 221 actively increases the increase value b32 of the brake torque output by the brake motor 222 at the third time t3, so that the actual clamping force of the adjusted friction plate at the third time t3 meets the expected clamping force, ensuring that the braking effect of the electric vehicle meets the expectation of the driver, thereby improving the braking performance of the electric vehicle.

[0115] In one embodiment, at the third time t3 after the second time t2, the stroke of the brake pedal decreases relative to the stroke of the brake pedal at the second time t2, and the third brake torque a3 indicated by the third brake signal is less than the second brake torque a2 indicated by the second brake signal.

[0116] Figure 8 Another schematic diagram of the braking control process of the electric vehicle provided by the embodiment of the present application is provided. As shown in Figure 8 As shown, at the third time t3 after the second time t2, the third brake torque a3 indicated by the third brake signal is less than the second brake torque a2 indicated by the second brake signal. The difference between the third brake torque b3 and the second brake torque b2 is greater than the preset torque value. The difference b32 between the third brake torque b3 and the second brake torque b2 is less than the difference a32 between the third brake torque a3 indicated by the third brake signal and the second brake torque a2 indicated by the second brake signal.

[0117] At the third time t3 after the sustained braking, the temperature of the friction plate further increases relative to the second time t2 to be greater than the thermal recession temperature of the friction plate, the friction coefficient of the friction plate decreases, the stroke of the brake pedal at the third time t3 decreases, and the brake motor 222 correspondingly reduces the output brake torque according to the difference a32, which will cause the actual clamping force of the adjusted friction plate at the third time t3 to be less than the expected clamping force, resulting in the braking effect of the electric vehicle not meeting the expectation of the driver.

[0118] In this embodiment, the wheel-end controller 221 actively reduces the difference b32 in the braking torque output by the brake motor 222 at the third time t3, so that the actual clamping force of the adjusted friction pad at the third time t3 meets the expected clamping force, ensuring that the braking effect of the electric vehicle meets the driver's expectations, thereby improving the braking performance of the electric vehicle.

[0119] In one embodiment, before the first moment t1 after the driver has prolongedly depresses the brake pedal, the duration for which the electromechanical braking device 220 brakes the corresponding wheel 250 is greater than a second preset duration. Consequently, the temperature of the friction pads exceeds the thermal decay temperature of the friction pads, and the coefficient of friction of the friction pads decreases.

[0120] Figure 9 This is another schematic diagram illustrating the braking control process of an electric vehicle provided in an embodiment of this application. For example... Figure 9 As shown, at the first moment t1 after continuous braking of the electric vehicle, the wheel-end controller 221 receives the first braking signal and controls the brake motor 222 to output the first braking torque b1. This first braking torque b1 is greater than the braking torque a1 indicated by the first braking signal.

[0121] If the temperature of the friction pad is greater than the thermal decay temperature of the friction pad at the first moment t1 after continuous braking, the friction coefficient of the friction pad will decrease. If the wheel end controller 221 controls the braking torque output by the brake motor 222 at the first moment t1 according to the braking torque a1 indicated by the received first braking signal, the actual clamping force of the friction pad before adjustment at the first moment t1 will be less than the expected clamping force, resulting in the braking effect of the electric vehicle not meeting the driver's expectations.

[0122] In this embodiment, the wheel end controller 221 actively increases the first braking torque b1 output by the brake motor 222 at the first moment t1, so that the first braking torque b1 is greater than the braking torque a1 indicated by the first braking signal, thereby ensuring that the actual clamping force of the friction pad after adjustment at the first moment t1 meets the expected clamping force, ensuring that the braking effect of the electric vehicle meets the driver's expectations, thereby improving the braking performance of the electric vehicle.

[0123] At the second time t2 following the first time t1, the brake pedal travel remains unchanged. The difference between the braking torque a2 indicated by the second brake signal and the braking torque a1 indicated by the first brake signal is less than or equal to a preset torque value. The wheel end controller 221 receives the second brake signal and controls the brake motor to output the second braking torque b2. The second braking torque b2 is greater than the braking torque a2 indicated by the second brake signal.

[0124] At a third time t3 after the second time t2, the stroke of the brake pedal is increased, and the brake torque a3 indicated by the third brake signal is greater than the brake torque a2 indicated by the second brake signal. The wheel end controller 221 receives the third brake signal and controls the brake motor to output a third brake torque b3. The third brake torque b3 is greater than the brake torque a3 indicated by the third brake signal. The third brake torque b3 is greater than the second brake torque b2. A difference b32 between the third brake torque b3 and the second brake torque b2 is greater than a difference a32 between the brake torque a3 indicated by the third brake signal and the brake torque a2 indicated by the second brake signal.

[0125] At the third time t3 after the sustained braking, the temperature of the friction plate is further increased to be greater than the thermal recession temperature of the friction plate relative to the second time t2, the friction coefficient of the friction plate is further decreased, the stroke of the brake pedal is increased at the third time t3, and the brake motor 222 correspondingly increases the output brake torque by the difference a32, which will cause the actual clamping force of the friction plate before adjustment at the third time t3 to be less than the expected clamping force, resulting in the braking effect of the electric vehicle not meeting the expectation of the driver.

[0126] In the embodiment of the present application, the wheel end controller 221 actively increases the increase value b32 of the brake torque output by the brake motor 222 at the third time t3, so that the clamping force of the friction plate after adjustment at the third time t3 meets the expected clamping force, ensures that the braking effect of the electric vehicle meets the expectation of the driver, and thus improves the braking performance of the electric vehicle.

[0127] The brake control method provided in the embodiment of the present application is used to adjust the brake torque output by the plurality of electronic mechanical brake devices 220 in the process of sustained braking of the electric vehicle. At the first time t1, the second time t2, and the third time t3 in the process of sustained braking of the electric vehicle, the brake control method provided in the embodiment of the present application adjusts the brake torque output by the plurality of electronic mechanical brake devices according to the length of time of sustained braking and the received brake signal. The brake control method provided in the embodiment of the present application is described below in combination with the first time t1, the second time t2, and the third time t3 in the process of sustained braking of the electric vehicle.

[0128] In one embodiment, at the first time t1 after the sustained braking of the electric vehicle, one or more electronic mechanical brake devices are controlled to output a first brake torque b1 according to a first brake signal, and a difference between the first brake torque b1 and a brake torque a1 indicated by the first brake signal is less than or equal to a preset torque value.

[0129] Figure 10 Another schematic diagram of the brake control process of the electric vehicle provided in the embodiment of the present application is shown in FIG. 3. As shown in FIG. 3, the brake control process of the electric vehicle provided in the embodiment of the present application includes the following steps. Figure 10As shown, at the first moment t1, the temperature of the friction pads of the electric vehicle has not yet increased, and the coefficient of friction of the friction pads has not yet increased. The difference between the first braking torque b1 output by the electromechanical braking device 220 and the braking torque a1 indicated by the received first braking signal is less than or equal to the preset torque value.

[0130] In this embodiment, at the first moment t1, the temperature of the friction pads of the electric vehicle has not yet increased, and the friction coefficient of the friction pads has not yet increased. At the first moment t1, the brake motor 222 outputs a first braking torque b1 according to the braking torque a1 indicated by the received first braking signal. The difference between the first braking torque b1 and the braking torque a1 indicated by the received first braking signal is less than or equal to a preset torque value, so that the actual clamping force of the friction pads after adjustment at the first moment t1 meets the expected clamping force, ensuring that the braking effect of the electric vehicle meets the driver's expectations, thereby improving the braking performance of the electric vehicle.

[0131] In one embodiment, at a second time t2, the temperature of the friction pad corresponding to at least one electromechanical braking device 220 increases, and the coefficient of friction of the friction pad corresponding to the at least one electromechanical braking device 220 increases. At the second time t2 after the first time t1, at least one electromechanical braking device 220 is controlled to output a second braking torque according to a second braking signal. The difference between the braking torque indicated by the second braking signal and the braking torque indicated by the first braking signal is less than a preset torque value, and the difference between the second braking torque and the braking torque indicated by the second braking signal is greater than the preset torque value.

[0132] like Figure 10 As shown, at the second time t2 after the first time t1, the travel of the brake pedal remains unchanged. At least one electromechanical braking device 220, after continuous braking, has a friction pad temperature that is further increased relative to the first time t1. The friction coefficient of the friction pad changes. The braking torque a2 indicated by the second braking signal received at the second time t2 does not change relative to the braking torque a1 indicated by the first braking signal received at the first time t1. The braking torque output by the electromechanical braking device 220 remains unchanged. This will cause the clamping force of the friction pad before adjustment to decrease at the second time t2 relative to the clamping force at the first time t1. As a result, the actual clamping force of the friction pad at the second time t2 is less than the expected clamping force, causing the braking effect of the electric vehicle to not meet the driver's expectations.

[0133] The braking control method provided in this application adjusts the braking torque output by at least one electromechanical braking device 220 at a second time t2, such that the difference between the second braking torque b2 output at the second time t2 and the braking torque a2 indicated by the second braking signal is greater than a preset torque value. This ensures that the actual clamping force of the friction pad after adjustment at the second time t2 remains consistent with the clamping force at the first time t1, guaranteeing that the braking effect of the electric vehicle meets the driver's expectations, thereby improving the braking performance of the electric vehicle.

[0134] In one embodiment, at a third time t3 after the second time t2, the difference between the braking torque indicated by the third braking signal and the braking torque indicated by the second braking signal is greater than a preset torque value. Based on the third braking signal, at least one electromechanical braking device 220 is controlled to output a third braking torque b3. The difference between the third braking torque and the braking torque indicated by the third braking signal is greater than the preset torque value. The difference between the third braking torque b3 and the braking torque a3 indicated by the third braking signal is different from the difference between the braking torque b3 indicated by the third braking signal and the braking torque b2 indicated by the second braking signal.

[0135] like Figure 10 As shown, at the third time t3 after the second time t2, the travel of the brake pedal of the electric vehicle changes. The braking torque a3 indicated by the third braking signal received at the third time t3 changes relative to the braking torque a2 indicated by the second braking signal received at the second time t2. If the braking torque output by the electromechanical braking device 220 increases accordingly based on the difference a3 between the braking torque a3 indicated by the third braking signal and the braking torque a2 indicated by the second braking signal, this will cause the actual clamping force of the friction pads before adjustment at the third time t3 to be less than or greater than the expected clamping force, resulting in the braking effect of the electric vehicle not meeting the driver's expectations.

[0136] The braking control method provided in this application actively adjusts the increase value b32 of the third braking torque b3 output at the third time t3 relative to the second braking torque b2 output at the second time t2, so that the actual clamping force of the friction pad after adjustment at the third time t3 meets the expected clamping force, ensuring that the braking effect of the electric vehicle meets the driver's expectations, thereby improving the braking performance of the electric vehicle.

[0137] In one embodiment, at a second time t2 after a first time t1, the difference between the braking torque output by the other electromechanical braking devices 220 (excluding at least one electromechanical braking device 220) and the second braking torque output by at least one electromechanical braking device 220 is greater than a preset torque value, according to the second braking signal.

[0138] The brake force distribution of the electric vehicle braking process usually causes the brake torque output by the plurality of electronic mechanical brake devices to be different during the braking process. The temperature increase of the friction plate corresponding to the at least one electronic mechanical brake device 220 and the temperature increase of the friction plate corresponding to the other electronic mechanical brake device are inconsistent at the second time t2 after the first time t1. Correspondingly, the friction coefficient change of the friction plate corresponding to the at least one electronic mechanical brake device 220 and the friction coefficient change of the friction plate corresponding to the other electronic mechanical brake device are inconsistent.

[0139] At the second time t2 after the first time t1, the stroke of the brake pedal is unchanged, the friction coefficient of the friction plate corresponding to the at least one electronic mechanical brake device 220 and the friction coefficient of the friction plate corresponding to the other electronic mechanical brake device are inconsistent, and the second brake torque output by the plurality of electronic mechanical brake devices 220 is the same as the difference between the brake torque indicated by the second brake signal. If so, the clamping force of the friction plate corresponding to the plurality of electronic mechanical brake devices 220 at the second time t2 relative to the clamping force at the first time t1 is inconsistent, resulting in an unbalanced braking effect of the plurality of electronic mechanical brake devices 220 of the electric vehicle, and further resulting in an electric vehicle braking effect that does not meet the driver's expectation or an electric vehicle that produces an unexpected deviation or slip.

[0140] The brake control method provided by the embodiment of the present application controls the brake torque output by the other electronic mechanical brake device 220 except the at least one electronic mechanical brake device 220 to be different from the brake torque output by the at least one electronic mechanical brake device 220 at the second time t2, so that the clamping force of the friction plate corresponding to the plurality of electronic mechanical brake devices 220 at the second time t2 relative to the clamping force at the first time t1 remains consistent, the braking effect of the plurality of electronic mechanical brake devices 220 of the electric vehicle is balanced, and thus the braking performance of the electric vehicle is improved.

[0141] In an embodiment, the duration of the continuous braking of the electric vehicle at the second time t2 after the first time t1 is greater than the first preset duration and less than or equal to the second preset duration. That is, at the second time t2 after the first time t1, the temperature of the friction plate corresponding to the at least one electronic mechanical brake device 220 increases and the temperature value is less than the thermal decay temperature.

[0142] In an embodiment, at the second time t2 after the first time t1, the temperature value of the friction plate corresponding to the at least one electronic mechanical brake device 220 is greater than the temperature value of the friction plate corresponding to the other electronic mechanical brake device 220, and correspondingly, the friction coefficient of the friction plate corresponding to the at least one electronic mechanical brake device 220 is greater than the friction coefficient of the friction plate corresponding to the other electronic mechanical brake device 220.

[0143] The brake control method provided in the embodiments of the present application controls the second brake torque b2 output by the at least one electromechanical brake device 220 to be less than the brake torque a2 indicated by the second brake signal and the first brake torque b1 output at the first time t1, and controls the difference between the brake torque output by the other electromechanical brake device 220 and the brake torque a2 indicated by the second brake signal to be less than the difference between the second brake torque b2 output by the at least one electromechanical brake device 220 and the brake torque a2 indicated by the second brake signal.

[0144] Since the friction coefficient of the friction plate corresponding to the at least one electromechanical brake device 220 is greater than the friction coefficient of the friction plate corresponding to the other electromechanical brake device 220 at the second time t2, the brake control method provided in the embodiments of the present application controls the brake torque output by the other electromechanical brake device 220 to be greater than the second brake torque b2 output by the at least one electromechanical brake device 220, so that the clamping force of the friction plates corresponding to the plurality of electromechanical brake devices 220 at the second time t2 is consistent with the clamping force at the first time t1, thereby ensuring the balance of the brake effect generated by the plurality of electromechanical brake devices 220 of the electric vehicle, and improving the brake performance of the electric vehicle.

[0145] In one embodiment, the duration of the continuous braking of the electric vehicle at the second time t2 after the first time t1 is greater than the second preset duration. That is, at the second time t2 after the first time t1, the temperature of the friction plates corresponding to the plurality of electromechanical brake devices 220 increases and the temperature value is greater than the thermal decay temperature.

[0146] In one embodiment, the temperature value of the friction plate corresponding to the at least one electromechanical brake device 220 is less than the temperature value of the friction plate corresponding to the other electromechanical brake device 220 at the second time t2 after the first time t1, and accordingly, the friction coefficient of the friction plate corresponding to the at least one electromechanical brake device 220 is greater than the friction coefficient of the friction plate corresponding to the other electromechanical brake device 220.

[0147] The brake control method provided in the embodiments of the present application controls the second brake torque b2 output by the at least one electromechanical brake device 220 to be greater than the brake torque a2 indicated by the second brake signal and the first brake torque b1 output at the first time t1, and controls the difference between the brake torque output by the other electromechanical brake device 220 and the brake torque a2 indicated by the second brake signal to be greater than the difference between the second brake torque b2 output by the at least one electromechanical brake device 220 and the brake torque a2 indicated by the second brake signal.

[0148] Since the friction coefficient of the friction plate corresponding to the at least one electromechanical brake device 220 is greater than the friction coefficient of the friction plate corresponding to the other electromechanical brake device 220 at the second time t2, the brake control method provided in the embodiment of the application controls the brake torque output by the other electromechanical brake device 220 to be less than the second brake torque b2 output by the at least one electromechanical brake device 220, so that the clamping force of the friction plate corresponding to the plurality of electromechanical brake devices 220 at the second time t2 is consistent with the clamping force at the first time t1, thereby ensuring the balance of the brake effect generated by the plurality of electromechanical brake devices 220 of the electric vehicle, and improving the brake performance of the electric vehicle.

[0149] In an embodiment, at a third time t3 after the second time t2, the temperature of the friction plate corresponding to the at least one electromechanical brake device 220 further increases and is greater than the thermal decay temperature, and the temperature of the friction plate corresponding to the other electromechanical brake device 220 further increases and is less than the thermal decay temperature.

[0150] In an embodiment, the brake torque a3 indicated by the third brake signal is greater than the brake torque a2 indicated by the second brake signal. The brake control method provided in the embodiment of the application, in response to the brake torque a3 indicated by the third brake signal being greater than the brake torque a2 indicated by the second brake signal, controls the increase value of the third brake torque b3 output by the at least one electromechanical brake device 220 relative to the second brake torque b2 to be greater than the difference a23 between the brake torque a3 indicated by the third brake signal and the brake torque a2 indicated by the second brake signal, and controls the increase value of the brake torque output by the other electromechanical brake device 220 to be less than the difference a23 between the brake torque a3 indicated by the third brake signal and the brake torque a2 indicated by the second brake signal.

[0151] In an embodiment, the brake torque a3 indicated by the third brake signal is less than the brake torque a2 indicated by the second brake signal. The brake control method provided in the embodiment of the application, in response to the brake torque a3 indicated by the third brake signal being less than the brake torque a2 indicated by the second brake signal, controls the decrease value b of the third brake torque b3 output by the at least one electromechanical brake device 220 relative to the second brake torque b2 to be less than the decrease value of the brake torque a3 indicated by the third brake signal and the brake torque a2 indicated by the second brake signal, and controls the decrease value of the brake torque output by the other electromechanical brake device 220 to be greater than the decrease value of the brake torque a3 indicated by the third brake signal and the brake torque a2 indicated by the second brake signal.

[0152] The braking control method provided in this application adjusts the torque variation of multiple electromechanical braking devices 220 according to the temperature difference of multiple electromechanical braking devices 220 at the third time t3, so that the clamping force of the friction pads corresponding to the multiple electromechanical braking devices 220 at the third time t3 meets the expected clamping force, ensuring the balance of the braking effect of the electric vehicle, thereby improving the braking performance of the electric vehicle.

[0153] Figure 11 Another schematic diagram of the electromechanical braking device provided in an embodiment of this application. In one embodiment, as shown... Figure 11 As shown, the wheel end controller 221 includes a temperature estimation module A1, a clamping force compensation module A2, a clamping force calculation module A3, a fusion module A4, and a control signal output module A5.

[0154] In one embodiment, when the driver depresses the brake pedal for an extended period, each electromechanical braking device brakes the corresponding wheel. Specifically, at a first moment after each electromechanical braking device brakes its corresponding wheel, the wheel-end controller 221 receives a first braking signal and controls the corresponding brake motor to output a first braking torque. At a second moment after the first moment, after the wheel-end controller 221 receives a second braking signal, the temperature estimation module A1, based on the clamping force of the friction pads at the first moment and the wheel speed V of the aforementioned wheel at the second moment... L and the ambient temperature T of electric vehicles a Calculate the estimated temperature T of the friction plate k The clamping force compensation module A2 adjusts the clamping force based on the aforementioned temperature estimate T. k Calculate the clamping force compensation value N0 of the friction pad. The clamping force calculation module A3 calculates the reference value N of the clamping force of the friction pad based on the rotation angle of the brake motor at the second moment. ref The fusion module A4 adjusts the clamping force based on the clamping force compensation value N0 and the clamping force reference value N. ref Calculate an estimated clamping force N1 for the friction plate. Finally, the control signal output module A5 outputs a control signal Cs for the brake motor based on the estimated clamping force N1. The control signal Cs is used to control the brake motor to output a second braking torque T. m1 The actuator is used to clamp the brake disc of the electric vehicle.

[0155] In one embodiment, once the clamping force estimate N1 is confirmed, the control signal output module A5 can directly output the temperature estimate T. k The relationship between the corresponding clamping force value and the braking torque output by the brake motor 222 is used to output a control signal to the brake motor, so that the brake motor 222 can drive the actuator 223 to output the required clamping force.

[0156] In one embodiment, therefore the above temperature estimate Tk The calculation can be performed in the following manner:

[0157] T k = T k-1 + ΔT h - ΔT c1 - ΔT c2 ;

[0158] ΔT h = V x F c x P;

[0159] ΔT c1 = (h x ΔT + ΔT x R) x A;

[0160]

[0161] In the above formula, T k represents the temperature estimation value of the friction plate of the actuator 223 at the current time, T k-1 represents the temperature estimation value of the friction plate of the actuator 223 at the previous time, ΔT h represents the heat generation amount of the friction plate, ΔT c1 represents the heat dissipation amount of the friction plate, ΔT c2 represents the radiation heat amount of the friction plate, V represents the wheel speed of the vehicle at the current time, F c represents the clamping force value of the friction plate at the previous time, P represents the calibrated heat generation coefficient, ΔT represents the temperature difference between the temperature estimation value T k-1 at the previous time and the ambient temperature T a at the current time, h represents the convective heat transfer coefficient of the friction plate, R represents the material thermal resistance of the friction plate, ε represents the emissivity of the surface of the friction plate, δ represents the Boltzmann constant, T a represents the ambient temperature, and A represents the heat dissipation area of the friction plate.

[0162] In the above implementation process, the time interval between the second time and the first time can be determined according to the calculation period of the wheel-end controller 221, the signal acquisition period of the brake pedal, the transmission time delay of the signal, and the driver's braking pedal manner. For example, when the driver intermittently steps on the brake pedal, the time interval between the second time and the first time needs to be determined according to the calculation period of the wheel-end controller 221, the signal acquisition period of the brake pedal, the transmission time delay of the signal, and the time interval of the driver stepping on the brake pedal. When the driver steps on the brake pedal for a long time, the time interval between the second time and the first time is determined according to the calculation period of the wheel-end controller 221, the transmission time delay of the signal, and the signal acquisition period of the brake pedal.

[0163] In one embodiment, the clamping force compensation module A2 can output a clamping force compensation value of the friction plate according to a change relationship between a temperature of the friction plate and the clamping force compensation value N0. The clamping force calculation module A3 can output a clamping force reference value of the friction plate according to a change relationship between a rotation angle of the brake motor and the clamping force of the friction plate.

[0164] In one embodiment, the change relationship between the clamping force compensation value and the temperature of the friction plate can be calibrated by experimental data and stored in the memory. The change relationship between the rotation angle of the brake motor and the clamping force output by the actuator 223 can also be calibrated by experimental data and stored in the memory. Based on this, the clamping force compensation module A2 can estimate the temperature of the friction plate according to the temperature estimation value T k The corresponding clamping force compensation value is queried from the memory. The clamping force compensation value can be positive or negative. For example, when the temperature of the friction plate is greater than the thermal recession temperature of the friction plate, the clamping force compensation value is positive. When the temperature of the friction plate is less than the thermal recession temperature of the friction plate, the clamping force compensation value is negative. After the clamping force calculation module A3 obtains the rotation angle θ of the brake motor 222 at the current time, the corresponding clamping force reference value can be queried from the memory.

[0165] In one embodiment, when the stroke of the brake pedal changes, the wheel end controller 221 can also receive a third brake signal and control the brake motor to output a third brake torque at a third time after the second time. The difference between the brake torque indicated by the third brake signal and the brake torque indicated by the second brake signal is greater than a preset torque value, and the difference between the third brake torque and the brake torque indicated by the third brake signal is greater than a preset torque value.

[0166] After receiving the third brake signal, the temperature estimation module A1 calculates the temperature estimation value of the friction plate according to the clamping force estimation value of the friction plate calculated at the second time, the wheel speed of the above-mentioned one wheel at the third time, and the environmental temperature of the electric vehicle. The clamping force compensation module A2 calculates the clamping force compensation value of the friction plate according to the above-mentioned temperature estimation value. The clamping force calculation module A3 calculates the clamping force reference value of the friction plate according to the rotation angle of the brake motor at the third time. The fusion module A4 calculates one clamping force estimation value of the friction plate according to the above-mentioned clamping force compensation value and the above-mentioned clamping force reference value. The control signal output module A5 outputs a control signal to the brake motor according to the above-mentioned one clamping force estimation value, and the above-mentioned control signal is used to control the brake motor to output the third brake torque.

[0167] In this way, the wheel-end controller 221 can calculate the estimated temperature of the friction pads by using the wheel speed at the current moment, the ambient temperature of the electric vehicle, and the clamping force value of the friction pads at the previous moment, without installing temperature sensors and clamping force sensors. Based on the estimated temperature, the clamping force of the friction pads is compensated to output the corresponding control signal. This makes the clamping force provided by the friction pads closer to the expected clamping force corresponding to the braking torque indicated by the braking signal after the brake motor adjusts the output braking torque according to the control signal.

[0168] Figure 12 Another schematic diagram of the electromechanical braking device provided in an embodiment of this application. In one embodiment, as shown... Figure 12 As shown, the control signal output module A5 includes a torque balance calculation submodule A51, a Kalman filter submodule A52, and a signal generation submodule A53. The torque balance calculation submodule A51 calculates another estimated clamping force N2 of the friction plate based on the actuator's transmission ratio, the moment of inertia of the brake motor, the friction force of the friction plate at the previous moment, and the rotation angle and braking torque of the brake motor at the previous moment. The Kalman filter submodule A52 performs Kalman filtering on the aforementioned estimated clamping force N1 and the other estimated clamping force N2 to obtain a target estimated clamping force N3 of the friction plate. The signal generation submodule A53 generates a control signal for the brake motor based on the target estimated clamping force N3. This control signal is used to control the brake motor 222 to output a second braking torque. The signal generation submodule A53 can also generate the control signal for the brake motor based on the relationship between the clamping force value of the friction plate at the temperature corresponding to the temperature estimate and the braking torque output by the brake motor 222.

[0169] In the above manner, the wheel end controller 221 can perform Kalman filtering on the other clamping force estimate N2 obtained by torque balance calculation and the clamping force estimate N1 compensated by temperature estimate, so that the target clamping force estimate N3 is closer to the clamping force value corresponding to the braking signal, thereby further improving the braking accuracy of the electromechanical braking device.

[0170] In one embodiment, the clamping force estimate output by the torque balance calculation submodule A51 can be calculated in the following manner:

[0171]

[0172] In the above formula, T m γ represents the braking torque output by the brake motor 222 at the previous moment, γ represents the transmission ratio of the actuator 223, and J represents the braking torque output by the brake motor 222 at the previous moment. tot T represents the moment of inertia of brake motor 222, θ represents the rotation angle of brake motor 222 at the current moment, and T represents the rotation angle of brake motor 222 at the current moment. frepresents the friction force of the friction plate at the previous time, and sgn() represents a sign function.

[0173] During braking of the electric vehicle, the friction plate of the actuator 223 can clamp the brake disc of the wheel to provide braking force for the wheel. The friction between the friction plate and the brake disc of the wheel can change the temperature of the friction plate, thereby changing the friction force of the friction plate. In order to more accurately calculate the clamping force estimate of the friction plate, the friction force of the friction plate of the actuator 223 during braking needs to be calibrated. The operator can calibrate the friction force of the actuator 223 during clamping or releasing through experimental data. Then, the wheel end controller 221 can calculate the corresponding clamping force estimate according to the braking torque output by the brake motor 222 at the current time, the rotation angle of the brake motor 222 at the current time, the moment of inertia of the brake motor 222, the transmission ratio of the actuator 223, and the friction force of the friction plate during clamping through the torque balance equation.

[0174] In the above process, when the control signal output by the wheel end controller 221 to the brake motor 222 or the ambient temperature changes, the clamping force generated by the brake torque output by the brake motor 222 to the actuator 223 also changes, so that the change of the friction force of the friction plate during braking is different. Therefore, the operator needs to calibrate the friction force of the friction plate in all aspects according to various braking scenarios established according to the control signal or the ambient temperature, so that the clamping force of the friction plate is closer to the expected clamping force corresponding to the braking torque indicated by the braking signal.

[0175] Figure 13 Another schematic diagram of the electromechanical brake device provided by the embodiments of the present application is provided. In one embodiment, as shown in Figure 13 The signal generation sub-module A53 is further configured to output a control signal of the brake motor according to the above another target clamping force estimate, and the control signal is used to control the brake motor to output a second braking torque. b

[0176] In this way, the wheel end controller 221 can output a more accurate control signal to the brake motor 222, so that the clamping force output by the corresponding actuator 223 is closer to the expected clamping force corresponding to the braking torque indicated by the braking signal.

[0177] In one embodiment, the vehicle speed V c , acceleration a, yaw rate Y v , load m, and wheel speed V​L The wheel-end braking torque estimate of each electromechanical braking device is calculated and sent to the wheel-end controller 221. The brake controller or vehicle controller can then determine the wheel-end braking torque estimate based on the vehicle's acceleration a and yaw rate γ. v The vertical load on each wheel is calculated based on the load m. Additionally, the brake controller or vehicle controller can calculate the vertical load on each wheel based on the wheel speed V. L And vehicle speed V c The slip ratio of each wheel is calculated. Then, the brake controller 260 can calculate the longitudinal force F of each wheel based on the vertical load and slip ratio of each wheel. x Among them, the longitudinal force F x The calculation method is as follows:

[0178] F x =C×λ×F z ;

[0179] In the above formula, C represents the calibrated value of the relationship between the wheel's adhesion coefficient and slip ratio, λ represents the wheel's slip ratio, and F z This indicates the vertical load on the wheel.

[0180] Then, the brake controller 260 can adjust the braking force based on the longitudinal force F of each wheel. x The calculation involves determining the calibrated value of the relationship between the wheel's adhesion coefficient and slip ratio, the current driving torque of the wheel, the current braking torque of the wheel, and the wheel radius to estimate the wheel-end braking torque. The calculation method for the wheel-end braking torque estimate is as follows:

[0181] T b =T d -F x r;

[0182] In the above formula, T b T represents the estimated braking torque at the wheel end. d This represents the driving torque of the wheel, and r represents the wheel radius.

[0183] Estimated wheel-end braking torque T b The following relationship exists between the clamping force and the clamping force:

[0184]

[0185] Among them, F cl R represents the clamping force value corresponding to the wheel-end braking torque, μ represents the friction coefficient of the friction plate of actuator 223, and R represents the clamping force value corresponding to the wheel-end braking torque. b This indicates the effective radius of the brake disc.

[0186] In one embodiment, the signal generation submodule A53 can take the one target clamping force estimate value as the another target clamping force estimate value when the difference between the clamping force value corresponding to the wheel end brake torque estimate value and the one target clamping force estimate value is less than a reference threshold. In addition, the signal generation submodule A53 can take the clamping force estimate value corresponding to the wheel end brake torque estimate value as the another target clamping force estimate value when the difference between the clamping force value corresponding to the wheel end brake torque estimate value and the one target clamping force estimate value is greater than the reference threshold. The clamping force value of the friction plate is positively correlated with the brake torque output by the brake motor 222. Therefore, after the another target clamping force estimate value is confirmed, the signal generation submodule A53 can directly output a control signal to the brake motor according to the change relationship between the clamping force value corresponding to the current temperature estimate value and the brake torque output by the brake motor 222.

[0187] In this way, the wheel end controller 221 can generate a control signal based on the clamping force estimate value corresponding to the wheel end brake torque estimate value and the one target clamping force estimate value that is more in line with requirements, so that the clamping force of the friction plate can be closer to the expected clamping force corresponding to the brake torque indicated by the brake signal.

[0188] In one embodiment, the signal generation submodule A53 can perform Kalman filtering processing on the clamping force value corresponding to the wheel end brake torque estimate value and the one target clamping force estimate value to obtain the another target clamping force estimate value.

[0189] In one embodiment, when the stroke of the brake pedal changes, the wheel end controller 221 can also receive a third brake signal at a third time after the second time and control the brake motor to output a third brake torque. The difference between the brake torque indicated by the third brake signal and the brake torque indicated by the second brake signal is greater than a preset torque value, and the difference between the third brake torque and the brake torque indicated by the third brake signal is greater than a preset torque value.

[0190] The temperature estimation module A1 estimates the temperature of the friction plate according to the target clamping force estimation value of the friction plate at the second time and the wheel speed of the one wheel and the ambient temperature of the electric vehicle after receiving the third brake signal. The clamping force compensation module A2 calculates the clamping force compensation value of the friction plate according to the temperature estimation value. The clamping force calculation module A3 calculates the clamping force reference value of the friction plate according to the rotation angle of the brake motor at the third time. The fusion module A4 calculates one clamping force estimation value of the friction plate according to the clamping force compensation value and the clamping force reference value. The torque balance calculation sub-module A51 calculates another clamping force estimation value of the friction plate according to the transmission ratio of the actuator, the moment of inertia of the brake motor, the friction of the friction plate at the third time, and the rotation angle and brake torque of the brake motor at the third time. The Kalman filtering sub-module A52 performs Kalman filtering according to the one clamping force estimation value and the another clamping force estimation value to obtain one target clamping force estimation value of the friction plate. The signal generation sub-module A53 generates a control signal of the brake motor according to the one target clamping force estimation value, and the control signal is used to control the brake motor to output the third brake torque.

[0191] In conclusion, the electronic mechanical brake device and the brake control method of the electric vehicle provided by the embodiments of the present application are applied to the electric vehicle technical field to improve the brake effect of the electronic mechanical brake device when braking the wheel. The electronic mechanical brake device comprises a controller, a brake motor and an actuator. The controller is used to receive a first brake signal and control the brake motor to output a first brake torque at a first time after the electronic mechanical brake device brakes the one wheel. At a second time after the first time, the controller receives a second brake signal and controls the brake motor to output a second brake torque. The difference between the brake torque indicated by the first brake signal and the brake torque indicated by the second brake signal is less than or equal to a preset torque value, and the difference between the second brake torque and the first brake torque is greater than the preset torque value. In this way, the controller can adjust the brake signal output to the brake motor to adjust the brake torque output by the brake motor during the braking process, so that the actual clamping force of the friction plate of the actuator is closer to the expected clamping force corresponding to the brake torque indicated by the brake signal, and the brake precision of the electronic mechanical brake device when braking the wheel is improved.

[0192] In the embodiments provided in the present application, each functional module can be integrated in one device, or each module can exist physically alone, or two or more modules can be integrated in one device.

[0193] The above merely provides the specific implementation of the present application, but the protection scope of the present application is not limited to this. Any person skilled in the art can easily think of the changes or replacements within the technical range disclosed by the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. An electromechanical braking device, characterized in that, The electromechanical braking device is used to brake one wheel of the electric vehicle, and the electromechanical braking device is also used for: At the first moment after the electromechanical braking device has been continuously braking, a first braking signal is received and a first braking torque is output. At a second moment after the first moment, a second braking signal is received and a second braking torque is output; Wherein, the difference between the braking torque indicated by the first braking signal and the braking torque indicated by the second braking signal is less than or equal to a preset torque value, and the difference between the second braking torque and the first braking torque is greater than the preset torque value.

2. The electromechanical braking device according to claim 1, characterized in that, When the electromechanical braking device brakes a wheel for a duration greater than a first preset duration and less than or equal to a second preset duration, the temperature of the friction pad is less than or equal to the thermal decay temperature of the friction pad. When the electromechanical braking device brakes a wheel for a duration greater than the second preset duration, the temperature of the friction pad is greater than the thermal decay temperature of the friction pad. The electromechanical braking device is further configured to: At the first moment, the duration for which the electromechanical braking device brakes one wheel is greater than the first preset duration and less than or equal to the second preset duration, and the output is less than the first braking torque indicated by the first braking signal; At the second moment, the duration for which the electromechanical braking device brakes one wheel is greater than the second preset duration, and the output of the second braking torque is greater than the first braking torque.

3. The electromechanical braking device according to claim 1 or 2, characterized in that, The electromechanical braking device is also used for: At the third moment after the second moment, a third braking signal is received and a third braking torque is output; Wherein, the difference between the braking torque indicated by the third braking signal and the braking torque indicated by the second braking signal is greater than the preset torque value, the difference between the third braking torque and the second braking torque is greater than the preset torque value, and the difference between the third braking torque and the second braking torque is different from the difference between the braking torque indicated by the third braking signal and the braking torque indicated by the second braking signal.

4. The electromechanical braking device according to claim 3, characterized in that, At the third moment, if the temperature of the friction plate is less than or equal to the thermal decay temperature of the friction plate, the electromechanical braking device is further configured to: The third braking torque is controlled to be less than the braking torque indicated by the third braking signal.

5. The electromechanical braking device according to claim 4, characterized in that, The electromechanical braking device is further used for: In response to the braking torque indicated by the third braking signal being greater than the braking torque indicated by the second braking signal, the control output of the third braking torque is greater than the second braking torque, and the increase of the third braking torque relative to the second braking torque is less than the increase of the braking torque indicated by the third braking signal relative to the braking torque indicated by the second braking signal. In response to the braking torque indicated by the third braking signal being less than the braking torque indicated by the second braking signal, the control output of the third braking torque is less than the second braking torque, and the decrease in the third braking torque relative to the second braking torque is greater than the decrease in the braking torque indicated by the third braking signal relative to the second braking signal.

6. The electromechanical braking device according to claim 3, characterized in that, At the third moment, if the temperature of the friction plate is greater than its thermal decay temperature, the electromechanical braking device is further configured to: The third braking torque is controlled to be greater than the braking torque indicated by the third braking signal.

7. The electromechanical braking device according to claim 6, characterized in that, The electromechanical braking device is further used for: In response to the braking torque indicated by the third braking signal being greater than the braking torque indicated by the second braking signal, the third braking torque is controlled to be greater than the second braking torque, wherein the increase in the third braking torque relative to the second braking torque is greater than the increase in the braking torque indicated by the third braking signal relative to the braking torque indicated by the second braking signal. In response to the braking torque indicated by the third braking signal being less than the braking torque indicated by the second braking signal, the reduction in the third braking torque relative to the second braking torque is controlled to be less than the reduction in the braking torque indicated by the third braking signal relative to the braking torque indicated by the second braking signal.

8. The electromechanical braking device according to claim 1, characterized in that, The electromechanical braking device includes a wheel-end controller, a brake motor, and an actuator. The wheel-end controller controls the brake motor to output a braking torque based on a received braking signal indicating a braking torque. The brake motor outputs the braking torque to drive the actuator. The actuator drives friction pads to clamp the brake disc of one wheel based on the braking torque output by the brake motor. The wheel-end controller includes: The temperature estimation module is used to calculate the estimated temperature value of the friction pad based on the clamping force value of the friction pad at the first moment, the wheel speed of the wheel at the second moment, and the ambient temperature of the electric vehicle. A clamping force compensation module is used to calculate the clamping force compensation value of the friction plate based on the temperature estimate. The clamping force calculation module is used to calculate the clamping force reference value of the friction plate based on the rotation angle of the brake motor at the second moment; The fusion module is used to calculate an estimated clamping force value for the friction plate based on the clamping force compensation value and the clamping force reference value; A control signal output module is used to output a control signal for the brake motor based on the clamping force estimate, and the control signal is used to control the brake motor to output the second braking torque.

9. The electromechanical braking device according to claim 8, characterized in that, The control signal output module includes: The torque balance calculation submodule is used to calculate another estimated value of the clamping force of the friction plate based on the transmission ratio of the actuator, the moment of inertia of the brake motor, the friction force of the friction plate at the second moment, the rotation angle of the brake motor at the second moment, and the braking torque. The Kalman filter submodule is used to perform Kalman filtering based on the one clamping force estimate and the other clamping force estimate to obtain a target clamping force estimate of the friction plate; The signal generation submodule is used to generate the control signal based on the estimated value of the target clamping force, or to obtain another estimated value of the target clamping force by verifying the estimated value of the target clamping force and the estimated value of the braking torque of the brake motor at the second moment, and to generate the control signal based on the other estimated value of the target clamping force.

10. An electric vehicle, characterized in that, The electric vehicle includes a plurality of wheels and a plurality of electromechanical braking devices as described in any one of claims 1-9, wherein the plurality of electromechanical braking devices are used to brake the plurality of wheels respectively during the braking process of the electric vehicle.

11. A braking control method for an electric vehicle, characterized in that, The braking control method is used to adjust the braking torque output by multiple electromechanical braking devices during continuous braking of the electric vehicle, and the braking control method includes: At the first moment after continuous braking of the electric vehicle, one or more electromechanical braking devices are controlled to output a first braking torque according to a first braking signal, wherein the difference between the first braking torque and the braking torque indicated by the first braking signal is less than or equal to a preset torque value. At a second moment after the first moment, at least one electromechanical braking device is controlled to output a second braking torque according to the second braking signal. The difference between the braking torque indicated by the second braking signal and the braking torque indicated by the first braking signal is less than or equal to a preset torque value, and the difference between the second braking torque and the braking torque indicated by the second braking signal is greater than the preset torque value. At a third time after the second time, the at least one electromechanical braking device is controlled to output a third braking torque according to the third braking signal. The difference between the braking torque indicated by the third braking signal and the braking torque indicated by the second braking signal is greater than a preset torque value. The difference between the third braking torque and the braking torque indicated by the third braking signal is greater than the preset torque value. The difference between the third braking torque and the braking torque indicated by the third braking signal is different from the difference between the braking torque indicated by the third braking signal and the braking torque indicated by the second braking signal.

12. The braking control method according to claim 11, characterized in that, The braking control method further includes: At a second moment following the first moment, the difference between the braking torque output by the other electromechanical braking devices (excluding the at least one electromechanical braking device) among the plurality of electromechanical braking devices controlled according to the second braking signal and the second braking torque is greater than the preset torque value.

13. The braking control method according to claim 12, characterized in that, At the second moment, the temperature of the friction pad corresponding to the at least one electromechanical braking device rises and the temperature value is lower than the thermal fade temperature, and the temperature value of the friction pad corresponding to the at least one electromechanical braking device is greater than the temperature value of the friction pad corresponding to the other electromechanical braking devices. The braking control method further includes: At the second moment, the second braking torque output by the at least one electromechanical braking device is controlled to be less than the braking torque indicated by the second braking signal and the first braking torque, and the difference between the braking torque output by the other electromechanical braking devices and the braking torque indicated by the second braking signal is controlled to be less than the difference between the second braking torque output by the at least one electromechanical braking device and the braking torque indicated by the second braking signal.

14. The braking control method according to claim 12, characterized in that, At the second moment, the temperature of the friction pads corresponding to the plurality of electromechanical braking devices rises and the temperature value is greater than the thermal fade temperature, and the temperature value of the friction pad corresponding to at least one electromechanical braking device is less than the temperature value of the friction pads corresponding to the other electromechanical braking devices. The braking control method further includes: At the second moment, the second braking torque output by the at least one electromechanical braking device is controlled to be greater than the braking torque indicated by the second braking signal and the first braking torque, and the difference between the braking torque output by the other electromechanical braking devices and the braking torque indicated by the second braking signal is controlled to be greater than the difference between the second braking torque output by the at least one electromechanical braking device and the braking torque indicated by the second braking signal.

15. The braking control method according to claim 11, characterized in that, At the third moment, the temperature of the friction pad corresponding to the at least one electromechanical braking device further increases and the temperature value is greater than the thermal fade temperature; the temperature of the friction pad corresponding to the other electromechanical braking devices further increases and the temperature value is less than the thermal fade temperature; the braking control method further includes: In response to the braking torque indicated by the third braking signal being greater than the braking torque indicated by the second braking signal, the increase in the third braking torque output by the at least one electromechanical braking device relative to the second braking torque is controlled to be greater than the difference between the braking torque indicated by the third braking signal and the braking torque indicated by the second braking signal, and the increase in the braking torque output by the other electromechanical braking devices is controlled to be less than the difference between the braking torque indicated by the third braking signal and the braking torque indicated by the second braking signal. In response to the braking torque indicated by the third braking signal being less than the braking torque indicated by the second braking signal, the reduction in the third braking torque output by the at least one electromechanical braking device relative to the second braking torque is controlled to be less than the difference between the braking torque indicated by the third braking signal and the braking torque indicated by the second braking signal, and the reduction in the braking torque output by the other electromechanical braking devices is controlled to be greater than the difference between the braking torque indicated by the third braking signal and the braking torque indicated by the second braking signal.

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