Electromechanical brake device, electric vehicle and brake control method thereof

Abstract

The invention provides an electronic mechanical braking device, an electric vehicle and a braking control method of the electronic mechanical braking device, and is applied to the technical field of electric vehicles so as to improve the braking precision when the electronic mechanical braking device brakes wheels. A controller in the electronic mechanical braking device receives a first braking signal and controls a braking motor to output a first braking torque at the first moment after the electronic mechanical braking device brakes the corresponding wheels. And then, at a second moment after the first moment, a second brake signal is received, and the brake motor is controlled to output a second brake torque. The difference value between the braking torque indicated by the first braking signal and the braking torque indicated by the second braking signal is smaller than a preset torque value, and the difference value between the second braking torque and the first braking torque is larger than the preset torque value. On the basis, the electronic mechanical braking device can dynamically adjust the braking torque output by the braking motor according to the temperature change of the friction plate, and therefore the braking precision of the electronic mechanical braking device when the wheels are braked is improved.

Description

Technical Field

[0001] The present application relates to the technical field of electric vehicles, and in particular to an electronic mechanical braking device, an electric vehicle and a braking control method thereof. Background Art

[0002] With the development of electric vehicles, the braking system of electric vehicles has evolved from a traditional hydraulic braking system to an electronic mechanical brake (EMB) system, which is the current mainstream trend. In the electronic mechanical braking system, a brake motor is used to output the braking torque to drive the friction plate of the actuator to clamp the brake disc, which can provide faster response speed and higher braking accuracy than the traditional hydraulic braking system. However, due to the limited layout space of the wheel side in electric vehicles, it is difficult to install clamping force sensors and temperature sensors, resulting in the inability to accurately measure and control the braking torque or clamping force output by the electronic mechanical braking system. In addition, as the temperature of the friction plate increases during the braking process, the braking effect generated by the friction plate will change, thereby affecting the braking accuracy of the electronic mechanical braking system. Therefore, it is urgent to provide a solution to solve the above problems. Summary of the invention

[0003] The embodiments of the present application provide an electronic mechanical braking device, an electric vehicle and a braking control method thereof, so as to improve the braking accuracy of the electronic mechanical braking device during the braking process of the electric vehicle and improve the braking performance of the electric vehicle.

[0004] In order to achieve the above objectives, the embodiments of the present application provide the following technical solutions.

[0005] In a first aspect, an embodiment of the present application provides an electronic mechanical braking device, which is used to brake a wheel of an electric vehicle. The electronic mechanical braking device is also used to receive a first braking signal and output a first braking torque at a first moment after the electronic mechanical braking device continuously brakes. At a second moment after the first moment, a second braking signal is received and a second braking torque is output. 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.

[0006] When the electronic mechanical brake device continuously brakes the above-mentioned one wheel, the friction between the brake disc of the above-mentioned one wheel and the friction plate of the actuator in the electronic mechanical brake device will cause the temperature of the friction plate to rise, thereby causing the actual clamping force provided by the friction plate to be inconsistent with the expected clamping force corresponding to the braking 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 takes into account the influence of temperature, adjusts the braking torque output by the brake motor when the difference in the braking torque indicated by the brake signal is small, and dynamically adjusts the clamping force of the friction plate according to the change in the temperature of the friction plate, thereby improving the braking accuracy of the electronic mechanical brake device when braking the wheel, thereby improving the braking performance of the electric vehicle.

[0007] In one embodiment, when the electronic mechanical brake device brakes the one wheel for a time longer than the first preset time and less than or equal to the second preset time, the temperature of the friction plate is less than or equal to the thermal decay temperature of the friction plate; when the electronic mechanical brake device brakes the one wheel for a time longer than the second preset time, the temperature of the friction plate is greater than the thermal decay temperature of the friction plate. Based on this, the electronic mechanical brake device is further used to: at the second moment, when the electronic mechanical brake device brakes one wheel for a time longer than the first preset time and less than or equal to the second preset time, output a second braking torque less than the first braking torque. At the second moment, when the electronic mechanical brake device brakes one wheel for a time longer than the second preset time, output a second braking torque greater than the first braking torque.

[0008] In the above manner, the electronic mechanical brake device can appropriately reduce the braking torque output by the brake motor when the temperature of the friction plate is lower than the thermal decay temperature of the friction plate. In addition, the electronic mechanical brake device can appropriately increase the braking torque output by the brake motor when the temperature of the friction plate is higher 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 one embodiment, the electronic mechanical brake device is further configured to: at a third moment after the second moment, receive a third brake signal and output a third brake torque, wherein 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 travel of the brake pedal changes, the braking torque indicated by the brake signal will also change. Because the clamping force output by the friction plate is affected by temperature, the electronic mechanical brake device can improve the braking accuracy of the electronic mechanical brake device when braking the wheel by dynamically adjusting the braking torque actually output by the brake motor based on the braking torque indicated by the brake signal, thereby improving the braking performance of the electric vehicle.

[0011] In one embodiment, when the temperature of the friction plate is less than or equal to the thermal decay temperature of the friction plate at the third moment, the electronic mechanical braking device is further used to control the third braking torque to be less than the braking torque indicated by the third braking signal.

[0012] At the third moment, if the temperature of the friction plate is still less than or equal to the thermal decay temperature of the friction plate, when 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 will still be greater than the expected clamping force corresponding to the brake torque indicated by the third brake signal. Therefore, it is necessary to appropriately reduce the brake torque output by the brake motor 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 electronic mechanical brake device when braking the wheel.

[0013] In one embodiment, when the temperature of the friction plate at the third moment is still less than or equal to the thermal decay temperature of the friction plate, the electronic mechanical brake device further controls the output third braking torque to be greater than the second braking torque in response to the braking torque indicated by the third brake signal being greater than the braking torque indicated by the second brake signal. The increase value of the third braking torque relative to the second braking torque is less than the increase value of the braking torque indicated by the third brake signal relative to the braking torque indicated by the second brake signal. Alternatively, the electronic mechanical brake device further controls the output third braking torque to be less than the second braking torque in response to the braking torque indicated by the third brake signal being less than the braking torque indicated by the second brake signal, and the decrease value of the third braking torque relative to the second braking torque is greater than the decrease value of the braking torque indicated by the third brake signal relative to the braking torque indicated by the second brake signal.

[0014] In the above manner, when the temperature of the friction plate is less than or equal to the thermal decay temperature of the friction plate and the travel of the brake pedal changes, the electronic mechanical braking device can adjust the output braking torque 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 braking torque indicated by the braking signal.

[0015] In one implementation, at the third moment, the temperature of the friction plate is greater than the thermal decay temperature of the friction plate, and the electronic mechanical brake device further controls the third braking torque to be greater than the braking torque indicated by the third brake signal.

[0016] When the temperature of the friction plate at the third moment is greater than the thermal decay temperature of the friction plate, the friction coefficient of the friction plate will gradually decrease as the temperature rises, resulting in the actual clamping force provided by the friction plate being less than the expected clamping force corresponding to the braking torque indicated by the third brake signal. Therefore, it is necessary to appropriately increase the braking torque output by the brake motor in the electronic mechanical brake device so that the actual clamping force provided by the friction plate is closer to the expected clamping force corresponding to the braking torque indicated by the third brake signal, thereby improving the braking accuracy of the electronic mechanical brake device when braking the wheel.

[0017] In one embodiment, when the temperature of the friction plate at the third moment is greater than the thermal decay temperature of the friction plate, the electronic mechanical brake device further controls the third braking torque to be greater than the second braking torque in response to the braking torque indicated by the third brake signal being greater than the braking torque indicated by the second brake signal, and the increase value of the third braking torque relative to the second braking torque is greater than the increase value of the braking torque indicated by the third brake signal relative to the braking torque indicated by the second brake signal. Alternatively, the electronic mechanical brake device controls the decrease value of the third braking torque relative to the second braking torque to be less than the decrease value of the braking torque indicated by the third brake signal relative to the braking torque indicated by the second brake signal in response to the braking torque indicated by the third brake signal being less than the braking torque indicated by the second brake signal.

[0018] In the above manner, when the travel of the brake pedal changes when the temperature of the friction plate is greater than the thermal decay temperature of the friction plate at the third moment, the electronic mechanical braking device can also adjust the output braking torque 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 braking torque indicated by the braking signal.

[0019] In one embodiment, the electronic mechanical brake device includes a wheel-end controller, a brake motor and an actuator. The wheel-end controller is used to control the brake motor to output a brake torque according to the brake torque indicated by the received brake signal, the brake motor is used to output a brake torque to drive the actuator, and the actuator is used to drive the friction plate to clamp the brake disc of a wheel according to the brake torque output by the brake motor. Wherein, the wheel-end controller includes: a temperature estimation module, a clamping force compensation module, a clamping force calculation module, a fusion module and a control signal output module. Wherein, the temperature estimation module is used to calculate the temperature estimation value of the friction plate according to the clamping force value of the friction plate at the first moment and the wheel speed of a wheel at the second moment and the ambient temperature of the electric vehicle. The clamping force compensation module is used to calculate the clamping force compensation value of the friction plate according to the temperature estimation value. The clamping force calculation module is used to calculate the clamping force reference value of the friction plate according to the rotation angle of the brake motor at the second moment. The fusion module is used to calculate a clamping force estimation value of the friction plate according to the clamping force compensation value and the clamping force reference value. The control signal output module is used to output a control signal of the brake motor according to the above-mentioned clamping force estimation value, and the control signal is used to control the brake motor to output a second braking torque.

[0020] In the above manner, the wheel-end controller can estimate the temperature of the friction plate through the wheel speed, the ambient temperature of the electric vehicle and the first brake signal, so as to compensate the clamping force according to the changing relationship between the temperature of the friction plate and the clamping force compensation value, and adjust the output control signal to the brake motor according to the compensated clamping force estimation value.

[0021] In one embodiment, the control signal output module includes a torque balance calculation submodule, a Kalman filter submodule and a signal generation submodule. The torque balance calculation submodule is used to calculate 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 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 one clamping force estimation value and another clamping force estimation value to obtain a target clamping force estimation value of the friction plate. The signal generation submodule is used to generate the control signal according to the above-mentioned target clamping force estimation value, or to obtain another target clamping force estimation value by verifying a target clamping force estimation value and the braking torque estimation value of the brake motor at the second moment, and to generate a control signal according to the other target clamping force estimation value.

[0022] In the above manner, the wheel-end controller calculates the target clamping force estimate value according to the above one clamping force estimate value and the above another clamping force estimate value by means of 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 braking torque indicated by the brake signal. In addition, the wheel-end controller further verifies the above one target clamping force estimate value and the braking torque estimate value sent by the brake controller, and outputs a control signal to the brake motor according to the verified another target clamping force estimate value, so that the actual clamping force of the friction plate can be closer to the expected clamping force corresponding to the braking torque indicated by the brake signal.

[0023] In a second aspect, an embodiment of the present application provides an electric vehicle, comprising a plurality of wheels and a plurality of electronic mechanical braking devices as in any one of the embodiments of the first aspect described above, wherein the plurality of electronic mechanical braking devices are used to brake the plurality of wheels separately during the braking process of the electric vehicle.

[0024] Regarding the technical principles and beneficial effects of the above-mentioned second aspect, reference may be made to the relevant description of the above-mentioned first aspect, which will not be repeated here.

[0025] In a third aspect, an embodiment of the present application provides a braking control method for an electric vehicle, the braking control method being used to adjust the braking torque output by multiple electromechanical braking devices during continuous braking of the electric vehicle. The braking control method comprises:

[0026] At a first moment after the electric vehicle is continuously braked, one or more electronic mechanical braking devices are controlled to output a first braking torque according to a first braking signal, and a 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.

[0027] At a second moment after the first moment, at least one electronic mechanical braking device 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 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.

[0028] At a third moment after the second moment, at least one electronic mechanical braking device is controlled to output a third braking torque according to a 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, and 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.

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

[0030] In one embodiment, the above-mentioned braking control method also includes: at a second moment after the first moment, controlling the difference between the braking torque output by other electronic mechanical braking devices among the multiple electronic mechanical braking devices except at least one electronic mechanical braking device and the second braking torque to be greater than a preset torque value according to the second braking signal.

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

[0032] In one embodiment, at the second moment, the temperature of the friction plate corresponding to the at least one electronic mechanical braking device increases 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 braking device is greater than the temperature values ​​of the friction plates corresponding to other electronic mechanical braking devices. The braking control method further includes: at the second moment, controlling the second braking torque output by the at least one electronic mechanical braking device to be less than the braking torque indicated by the second braking signal and the first braking torque, and controlling the difference between the braking torque output by other electronic mechanical braking devices and the braking torque indicated by the second braking signal to be less than the difference between the second braking torque output by the at least one electronic mechanical braking device and the braking torque indicated by the second braking signal.

[0033] When the temperature of the friction plate corresponding to each electronic mechanical brake device is lower than the thermal decay temperature of the friction plate, the friction coefficient of the friction plate will gradually increase with the increase of temperature, resulting in the actual clamping force of the friction plate being greater than the expected clamping force corresponding to the braking torque indicated by the brake signal. Based on this, when the temperature value of the friction plate corresponding to at least one electronic mechanical brake device is greater than the temperature value of the friction plate corresponding to other electronic mechanical brake devices, the reduction value of the braking torque of at least one electronic mechanical brake device needs to be greater in order to make the actual clamping force of the corresponding friction plate closer to the expected clamping force corresponding to the braking 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 one embodiment, at the second moment, the temperatures of the friction plates corresponding to the above-mentioned multiple electronic mechanical braking devices increase and the temperature value is greater than the thermal decay temperature, and the temperature value of the friction plates corresponding to the above-mentioned at least one electronic mechanical braking device is less than the temperature values ​​of the friction plates corresponding to other electronic mechanical braking devices. The above-mentioned braking control method further includes: at the second moment, controlling the second braking torque output by the above-mentioned at least one electronic mechanical braking device to be greater than the braking torque indicated by the second braking signal and the first braking torque, and controlling the difference between the braking torque output by other electronic mechanical braking devices and the braking torque indicated by the second braking signal to be greater than the difference between the second braking torque output by the above-mentioned at least one electronic mechanical braking device and the braking torque indicated by the second braking signal.

[0035] When the temperature of the friction plates corresponding to the multiple electronic mechanical brake devices increases and the temperature value is greater than the thermal decay temperature, the friction coefficient of the friction plates gradually decreases with the increase of temperature, and the braking torque output by the multiple electronic mechanical brake devices needs to be greater than the braking torque indicated by the second brake signal in order to make the actual clamping force of the corresponding friction plates closer to the expected clamping force corresponding to the braking torque indicated by the second brake signal. Based on this, when the temperature value of the friction plates corresponding to the above-mentioned at least one electronic mechanical brake device is less than the temperature value of the friction plates corresponding to other electronic mechanical brake devices, the friction coefficient of the friction plates corresponding to the above-mentioned at least one electronic mechanical brake device is greater than the friction coefficient of the friction plates corresponding to other electronic mechanical brake devices. Therefore, the reduction value of the braking torque of other electronic mechanical brake devices relative to the second brake signal indication needs to be greater than the difference between the second braking torque output by the above-mentioned at least one electronic mechanical brake device and the braking 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 moment, the temperature of the friction plate corresponding to the at least one electronic mechanical brake device further increases and the temperature value is greater than the thermal decay temperature, and the temperature of the friction plate corresponding to the other electronic mechanical brake devices further increases and the temperature value is less than the thermal decay temperature, and the braking control method further includes:

[0037] In response to the braking torque indicated by the third braking signal being greater than the braking torque indicated by the second braking signal, controlling the increase value of the third braking torque output by the at least one electronic mechanical braking device relative to the second braking torque 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 controlling the increase value of the braking torque output by the other electronic mechanical braking devices 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;

[0038] 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 third braking torque output by at least one of the above-mentioned electronic mechanical braking devices is controlled to have a reduction value relative to the second braking torque that is 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 braking torque output by other electronic mechanical braking devices is controlled to have a reduction value that is greater than the difference between the braking torque indicated by the third braking signal and the second braking signal.

[0039] Through the above method, when the temperature of the friction plate corresponding to at least one of the above-mentioned electronic mechanical braking devices is greater than the thermal decay temperature at the third moment, and the temperature of the friction plate corresponding to other electronic mechanical braking devices is less than the thermal decay temperature, different control strategies can be adopted for the braking torque output by each electronic mechanical braking device according to the change of the brake pedal stroke to improve the braking accuracy of the electric vehicle during braking and improve the braking performance of the electric vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0042] Figure 3 A schematic diagram of an electromechanical braking system provided in an embodiment of the present application;

[0043] Figure 4 A schematic diagram of an electromechanical braking device provided in an embodiment of the present application;

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

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

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

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

[0048] Fig. 9 Another schematic diagram of the braking control process of an electric vehicle provided in an embodiment of the present application;

[0049] Fig.10 Another schematic diagram of the braking control process of an electric vehicle provided in an embodiment of the present application;

[0050] Fig.11 Another schematic diagram of an electromechanical brake device provided in an embodiment of the present application;

[0051] Fig.12 Another schematic diagram of an electromechanical brake device provided in an embodiment of the present application;

[0052] Fig.13 Another schematic diagram of an electromechanical braking device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0053] In this application, "in one embodiment" is used to indicate an example, illustration or description. The solution described in this application as "in one embodiment" should not be interpreted as being more preferred or more advantageous than the solutions of other embodiments. Specifically, the use of "in one embodiment" is intended to present the inventive concept of this application in a specific way.

[0054] In the braking device of an 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 decay temperature of the friction plate, the friction coefficient of the friction plate will increase, resulting in the actual clamping force of the friction plate being greater than the clamping force corresponding to the braking torque indicated by the brake signal. When the temperature of the friction plate is greater than the thermal decay temperature of the friction plate, the friction coefficient of the friction plate decreases, resulting in the actual clamping force of the friction plate being less than the clamping force corresponding to the braking torque indicated by the brake signal.

[0055] During the driving process of an electric vehicle, if the driver steps on the brake pedal for a long time to brake the electric vehicle, the long-term friction between the friction plate of the braking device and the brake disc of the wheel will cause the temperature of the friction plate to rise, thereby affecting the friction coefficient of the friction plate, causing deviations in the braking effect, thereby affecting the braking performance of the electric vehicle.

[0056] Due to the limited wheel side layout space of electric vehicles, it is impossible to install temperature sensors and clamping force sensors on the brake discs, friction pads or electronic mechanical brake devices of electric vehicles, and it is impossible to accurately measure the temperature and clamping force of the friction pads. Therefore, it is difficult for electric vehicles to adjust the clamping force of the friction pads according to the temperature changes of the friction pads during braking, resulting in errors between the calibrated clamping force and the actual clamping force provided by the friction pads to the brake discs, resulting in deviations in the braking effect, thereby affecting the braking performance of electric vehicles.

[0057] In order to solve the above problems, the embodiments of the present application provide an electromechanical brake device and a brake control method for an electric vehicle. During the braking process, the brake torque output by the electromechanical brake device can be dynamically adjusted according to the temperature change of the friction plate, so that the clamping force of the friction plate can be dynamically adjusted according to the temperature change of the friction plate when the driver steps on the brake pedal for a long time, thereby improving the braking performance of the electric vehicle.

[0058] The technical solutions in the embodiments of the present application will be described below in conjunction with the accompanying drawings.

[0059] Figure 1 A schematic diagram of an electric vehicle provided in an embodiment of the present application. Figure 1 As shown, the electric vehicle includes a drive system 100, a brake system 200 and a power battery 300. The drive system 100 is used to drive the wheels of the electric vehicle to drive the electric vehicle. The brake system 200 is used to brake the wheels of the electric vehicle to slow down the electric vehicle. The power battery 300 is used to power the drive system 100 and the brake system 200.

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

[0061] In one embodiment, the drive system 100 includes a motor controller 110, a drive motor 120, and a reducer 130. Figure 2 As shown, the motor controller 110 is used to receive the direct current outputted by the power battery 300 and output the alternating current to control the drive motor 120 to output the driving 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. Figure 2 As shown, the temperature sensor 140 is used to detect the ambient temperature T of the electric vehicle. a .like Fig.11 As shown, the braking system 200 is used to detect the ambient temperature T of the electric vehicle according to the temperature sensor 140. a The braking torque output by the brake motor 222 is adjusted.

[0063] In one embodiment, the electric vehicle further includes a wheel speed sensor 150. Figure 2 As shown, the wheel speed sensor 150 is used to detect the wheel speed V of the electric vehicle. L .like Fig.11 As shown, the braking system 200 is used to detect the wheel speed V of the electric vehicle according to the wheel speed sensor 150. L The braking torque output by the brake motor 222 is adjusted.

[0064] In one embodiment, the electric vehicle further includes an inertial measurement unit 160. Figure 2 As shown, the inertial measurement unit 160 is used to detect the acceleration a and the yaw angular velocity Y of the electric vehicle. v The braking system 200 is used to detect the acceleration a and yaw rate Y of the electric vehicle according to the inertial measurement unit 160. v The braking torque output by the brake motor 222 is adjusted.

[0065] In the embodiment of the present application, the braking system 200 includes a plurality of electromechanical braking devices 220. The plurality of electromechanical braking devices 220 are used to brake a plurality of wheels 250 respectively during the braking process of the electric vehicle.

[0066] Figure 3 A schematic diagram of an electronic mechanical braking system provided in an embodiment of the present application. Figure 3 As shown, the electric vehicle further comprises four wheels 250. Four electromechanical brake devices 220 are respectively used to brake the four wheels 250 of the electric vehicle. Each electromechanical brake device 220 is used to brake one wheel 250 of the electric vehicle.

[0067] In one 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 electronic mechanical brake devices 220 are respectively used to brake the left front wheel LF and the right front wheel RF of the electric vehicle, and the other two electronic mechanical brake devices 220 are respectively used to brake the left rear wheel LR and the right rear wheel RR of the electric vehicle.

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

[0069] In one embodiment, the electromechanical brake system 200 includes a 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 the two electromechanical brake devices 220 to brake the two front wheels of the electric vehicle, and another 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 respectively control the four electromechanical brake devices 220 to brake the four wheels 250 of the electric vehicle.

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

[0074] Figure 4 A schematic diagram of an electronic mechanical brake device provided in an embodiment of the present application. The electronic mechanical brake device 220 includes a wheel end controller 221, a brake motor 222 and an actuator 223. Figure 4 As shown, the wheel end controller 221 is used to receive the braking signal output by the brake controller 260 and to output a control signal to control the brake motor 222. The brake motor 222 is used to output a braking torque to drive the actuator 223. The actuator 223 is used to drive the friction plate to clamp the brake disc of a corresponding wheel according to the braking torque output by the brake motor 222.

[0075] In one embodiment, the wheel end controller 221 in the electromechanical brake device 220 includes a brake controller 260 in the electromechanical brake system 200 . The brake controller 260 in the electromechanical brake system 200 is used 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 motors 222 in 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 braking torque output by the brake motor 222 during the braking process of the electric vehicle. After receiving the braking signal output by the brake controller 260 during the braking process of the electric vehicle, the wheel end controller 221 actively adjusts the braking torque indicated by the braking signal output by the brake controller 260 and then controls the brake motor 222 to output the actual braking torque.

[0078] In one embodiment, the electronic mechanical brake device 220 further includes a position sensor 224. The position sensor 224 is used to detect the rotation angle and rotation speed of the brake motor 222. In the embodiment of the present application, the position sensor 224 includes a rotary transformer. Figure 4 As shown, the wheel end controller 221 is used to adjust the braking 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.

[0079] In one embodiment, the electronic mechanical brake device 220 further includes a torque sensor 225. The torque sensor 225 is used to detect the braking torque output by the brake motor 222. In the embodiment of the present application, the torque sensor 225 includes a current sensor. Figure 4 As shown, the wheel end controller 221 can calculate the braking 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 .

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

[0081] After the electric vehicle has been continuously braked, that is, after the driver has stepped on the brake pedal for a long time, as the electric vehicle has been continuously braked for an increased period of time or the driver has further stepped on the brake pedal, the time for the electronic mechanical brake device 220 to brake the corresponding wheel increases, and the temperature of the friction plate gradually increases. Among them, when the time for the electronic mechanical brake device 220 to brake the corresponding wheel is greater than the first preset time and less than or equal to the second preset time, the temperature of the friction plate increases to less than or equal to the thermal decay temperature of the friction plate. When the time for the electronic mechanical brake device 220 to brake the corresponding wheel is greater than the second preset time, the temperature of the friction plate increases to greater than the thermal decay temperature of the friction plate.

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

[0083] At the first moment t1 after the electronic mechanical brake device 220 continuously brakes one wheel 250, the wheel end controller 221 receives the first brake signal, at the second moment t2 after the first moment t1, the wheel end controller 221 receives the second brake signal, and at the third moment t3 after the second moment t2, the wheel end controller 221 receives the third brake signal.

[0084] In one embodiment, at a first time t1 after the electronic mechanical brake device 220 continuously brakes one 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 the first moment t1, the electronic mechanical brake device 220 brakes the corresponding wheel for a time period greater than the first preset time period and less than or equal to the second preset time period. Accordingly, the temperature of the friction plate increases to a temperature less than or equal to the thermal decay temperature of the friction plate.

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

[0087] Accordingly, at the first moment t1 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 plate from increasing with the increase in the temperature of the friction plate, 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 moment t2, the duration of the electronic mechanical brake device 220 continuously braking the corresponding wheel 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 moment t2 remains unchanged relative to the travel of the brake pedal at the first moment 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 moment t2 after the first moment 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 the 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 plate increases relative to that at 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 plate at the second moment t2 before adjustment 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 the embodiment of the present application, the wheel-end controller 221 actively adjusts the braking torque output by the brake motor 222 at the second moment t2, so that the second braking torque b2 output by the adjusted brake motor 222 at the second moment t2 is different from the first braking torque b1 output at the first moment t1, so that the actual clamping force of the friction plate at the second moment t2 after adjustment remains consistent with the actual clamping force at the first moment 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 the electronic mechanical brake device 220 continuously braking the corresponding wheel is still greater than the first preset duration and less than or equal to the second preset duration. Accordingly, the temperature of the friction plate is less than or equal to the thermal decay temperature of the friction plate.

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

[0094] In an embodiment of the present application, the wheel-end controller 221 actively reduces the braking torque output by the brake motor 222 at the second moment t2, so that the clamping force of the friction plate at the second moment t2 after adjustment remains consistent with the clamping force at the first moment t1, thereby improving the braking accuracy of the electric vehicle after continuous braking and improving the braking performance of the electric vehicle.

[0095] In one embodiment, at a third moment t3 after the second moment 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 the preset torque value. The wheel end controller 221 controls the brake motor 222 to output the third braking torque b3 at the third moment t3, the difference between the third braking torque b3 and the second braking torque b2 is greater than the preset torque value, and 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 the electronic mechanical brake device 220 continuously braking the corresponding wheel is still greater than the first preset duration and less than or equal to the second preset duration. Accordingly, the temperature of the friction plate is less than or equal to the thermal decay temperature of the friction plate.

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

[0098] like Figure 5 As shown, at the third moment t3 after the second moment t2, the braking torque a3 indicated by the third braking signal is greater than the braking torque a2 indicated by the second braking signal. Accordingly, the wheel-end controller 221 controls the brake motor 222 to output a third braking torque b3 that is less than the braking torque a3 indicated by the third braking signal at the third moment t3. 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 plate further increases relative to the second moment t2, the friction coefficient of the friction plate further increases, the stroke of the brake pedal increases at the third moment t3, and the brake motor 222 correspondingly increases the output braking torque according to the difference a32, which will cause the actual clamping force of the friction plate 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 the embodiment of the present application, the wheel-end controller 221 actively reduces the increase value b32 of the braking torque output by the brake motor 222 at the third moment t3, so that the clamping force of the friction plate at the third moment t3 after adjustment meets the expected clamping force, thereby improving the braking performance of the electric vehicle.

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

[0102] Figure 6 Another schematic diagram of the braking control process of an electric vehicle provided in an embodiment of the present application. Figure 6 As shown, at the third moment t3 after the second moment t2, the braking torque a3 indicated by the third braking signal is less than the braking torque a2 indicated by the second braking signal. Accordingly, the wheel-end controller 221 controls the braking motor 222 to output a third braking torque b3 that is less than the braking torque a3 indicated by the third braking signal at the third moment t3. The third braking torque b3 is less than the second braking torque b2. The difference b32 between the third braking torque b3 and the second braking torque b2 is greater 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.

[0103] At the third moment t3 after continuous braking, the temperature of the friction plate further increases compared with the second moment t2, and the friction coefficient of the friction plate further increases. The stroke of the brake pedal at the third moment t3 is reduced, and the brake motor 222 correspondingly reduces the output braking torque according to the difference a32, which will cause the actual clamping force of the friction plate at the third moment t3 before adjustment to be 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 braking torque output by the brake motor 222 at the third moment t3, so that the actual clamping force of the friction plate at the third moment t3 after adjustment meets the expected clamping force, thereby improving the braking performance of the electric vehicle.

[0105] In one embodiment, at the second moment t2, the time duration for which the electronic mechanical brake device 220 continuously brakes the corresponding wheel is greater than the second preset time duration. Accordingly, the temperature of the friction plate is greater than the thermal decay temperature of the friction plate.

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

[0107] Figure 7 Another schematic diagram of the braking control process of an electric vehicle provided in an embodiment of the present application. Figure 7As shown, at the second moment t2 after the first moment 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 the preset torque value, and the wheel-end controller 221 controls the difference between the second braking torque b2 output by the brake motor 222 and the first braking torque b1 to be greater than the preset torque value. The wheel-end controller 221 controls the brake motor 222 to output the second braking torque b2 greater than the first braking torque b1.

[0108] At the second moment t2 after continuous braking, the temperature of the friction plate further increases to a temperature greater than the thermal decay temperature of the friction plate relative to the first moment t1, and the friction coefficient of the friction plate decreases. 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 clamping force of the friction plate at the second moment t2 before adjustment will decrease relative to the clamping force at the first moment t1, so that the actual clamping force of the friction plate at the second moment t2 is less than the expected clamping force, resulting in the braking effect of the electric vehicle not meeting the driver's expectations.

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

[0110] At the third moment t3, the duration of the electronic mechanical brake device 220 continuously braking the corresponding wheel is greater than the second preset duration. Accordingly, the temperature of the friction plate is greater than the thermal decay temperature of the friction plate. Accordingly, the wheel end controller 221 receives the third brake signal and controls the brake motor 222 to output a third brake torque b3, and the third brake torque b3 is greater than the brake torque a3 indicated by the third brake signal.

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

[0112] like Figure 7As shown, at a third moment t3 after the second moment t2, the braking torque a3 indicated by the third braking signal is greater than the braking torque a2 indicated by the second 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 greater 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.

[0113] At the third moment t3 after continuous braking, the temperature of the friction plate further increases to a temperature greater than the thermal decay temperature of the friction plate relative to the second moment t2, the friction coefficient of the friction plate decreases, the stroke of the brake pedal increases at the third moment t3, and the brake motor 222 increases the output braking torque accordingly according to the difference a32, which will cause the actual clamping force of the friction plate at the third moment t3 before adjustment to be less than the expected clamping force, resulting in the braking effect of the electric vehicle not meeting the driver's expectations.

[0114] In the embodiment of the present application, the wheel-end controller 221 actively increases the increase value b32 of the braking torque output by the brake motor 222 at the third moment t3, so that the actual clamping force of the friction plate at the third moment t3 after adjustment 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.

[0115] In one embodiment, at a third moment t3 after the second moment t2, the travel of the brake pedal is reduced relative to the travel of the brake pedal at the second moment t2, and the braking torque a3 indicated by the third braking signal is less than the braking torque a2 indicated by the second braking signal.

[0116] Figure 8 Another schematic diagram of the braking control process of an electric vehicle provided in an embodiment of the present application. Figure 8 As shown, at a third moment t3 after the second moment t2, the braking torque a3 indicated by the third braking signal is less than the braking torque a2 indicated by the second braking signal. 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 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.

[0117] At the third moment t3 after continuous braking, the temperature of the friction plate further increases to a temperature greater than the thermal decay temperature of the friction plate relative to the second moment t2, the friction coefficient of the friction plate decreases, the stroke of the brake pedal decreases at the third moment t3, and the brake motor 222 correspondingly reduces the output braking torque according to the difference a32, which will cause the actual clamping force of the friction plate at the third moment t3 before adjustment to be less than the expected clamping force, causing the braking effect of the electric vehicle to not meet the driver's expectations.

[0118] In the embodiment of the present application, the wheel-end controller 221 actively reduces the difference b32 of the braking torque output by the brake motor 222 at the third moment t3, so that the actual clamping force of the friction plate at the third moment t3 after adjustment 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 steps on the brake pedal for a long time, the time length of the electronic mechanical brake device 220 braking the corresponding wheel 250 is greater than the second preset time length. Accordingly, the temperature of the friction plate is greater than the thermal decay temperature of the friction plate, and the friction coefficient of the friction plate decreases.

[0120] Fig. 9 Another schematic diagram of the braking control process of an electric vehicle provided in an embodiment of the present application. Fig. 9 As shown, at the first moment t1 after the electric vehicle is continuously braked, the wheel end controller 221 receives the first braking signal and controls the brake motor 222 to output the first braking torque b1, wherein the first braking torque b1 is greater than the braking torque a1 indicated by the first braking signal.

[0121] At the first moment t1 after continuous braking, the temperature of the friction plate is greater than the thermal decay temperature of the friction plate, and the friction coefficient of the friction plate decreases. 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 plate at the first moment t1 before adjustment 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 the embodiment of the present application, 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, so that the actual clamping force of the friction plate 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 a second moment t2 after the first moment t1, the travel of the brake pedal remains unchanged, the difference between the braking torque a2 indicated by the second braking signal and the braking torque a1 indicated by the first braking signal is less than or equal to the preset torque value, and the wheel-end controller 221 receives the second braking 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 braking signal.

[0124] At a third moment t3 after the second moment t2, the travel of the brake pedal increases, and the braking torque a3 indicated by the third braking signal is greater than the braking torque a2 indicated by the second braking signal. The wheel-end controller 221 receives the third braking signal and controls the brake motor to output the third braking torque b3. The third braking torque b3 is greater than the braking torque a3 indicated by the second 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 greater 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.

[0125] At the third moment t3 after continuous braking, the temperature of the friction plate further increases to a temperature greater than the thermal decay temperature of the friction plate relative to the second moment t2, and the friction coefficient of the friction plate further decreases. The stroke of the brake pedal increases at the third moment t3, and the brake motor 222 correspondingly increases the output braking torque according to the difference a32, which will cause the actual clamping force of the friction plate before adjustment at the third moment t3 to be less than the expected clamping force, resulting in the braking effect of the electric vehicle not meeting the driver's expectations.

[0126] In the embodiment of the present application, the wheel-end controller 221 actively increases the increase value b32 of the braking torque output by the brake motor 222 at the third moment t3, so that the clamping force of the friction plate after adjustment at the third moment 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.

[0127] The braking control method provided in the embodiment of the present application is used to adjust the braking torque output by multiple electronic mechanical braking devices 220 during the continuous braking of the electric vehicle. At the first moment t1, the second moment t2, and the third moment t3 during the continuous braking of the electric vehicle, the braking control method provided in the embodiment of the present application adjusts the braking torque output by multiple electronic mechanical braking devices according to the duration of continuous braking and the received braking signal. The braking control method provided in the embodiment of the present application is described below in conjunction with the first moment t1, the second moment t2, and the third moment t3 during the continuous braking of the electric vehicle.

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

[0129] Fig.10 Another schematic diagram of the braking control process of an electric vehicle provided in an embodiment of the present application. Fig.10As shown, at the first moment t1, the friction plate temperature of the electric vehicle has not increased, and the friction coefficient of the friction plate has not increased. The difference between the first braking torque b1 output by the electronic mechanical brake 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 the embodiment of the present application, at the first moment t1, the temperature of the friction plate of the electric vehicle has not yet increased, and the friction coefficient of the friction plate has not yet increased. At the first moment t1, the first braking torque b1 output by the brake motor 222 is controlled according to the braking torque a1 indicated by the received first braking signal, and 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 the preset torque value, so that the actual clamping force of the friction plate 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 the second moment t2, the temperature of the friction plate corresponding to at least one electronic mechanical brake device 220 increases, and the friction coefficient of the friction plate corresponding to at least one electronic mechanical brake device 220 increases. At the second moment t2 after the first moment t1, at least one electronic mechanical brake device 220 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 the 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 Fig.10 As shown, at the second moment t2 after the first moment t1, the travel of the brake pedal remains unchanged, and the temperature of the friction plate of at least one electronic mechanical brake device 220 at the second moment t2 after continuous braking further increases relative to the first moment t1, and the friction coefficient of the friction plate changes, and the braking torque a2 indicated by the second brake signal received at the second moment t2 does not change relative to the braking torque a1 indicated by the first brake signal received at the first moment t1, and the braking torque output by the electronic mechanical brake device 220 remains unchanged, which will cause the clamping force of the friction plate at the second moment t2 before adjustment to decrease relative to the clamping force at the first moment t1, so that the actual clamping force of the friction plate at the second moment t2 is less than the expected clamping force, resulting in the braking effect of the electric vehicle not meeting the driver's expectations.

[0133] The braking control method provided in the embodiment of the present application adjusts the braking torque output by at least one electronic mechanical braking device 220 at the second moment t2, so that the difference between the second braking torque b2 output at the second moment t2 and the braking torque a2 indicated by the second braking signal is greater than the preset torque value, so that the actual clamping force of the friction plate after adjustment at the second moment t2 remains consistent with the clamping force at the first moment t1, thereby ensuring 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 moment t3 after the second moment 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, and at least one electronic mechanical braking device 220 is controlled to output a third braking torque b3 according to the third braking signal, and the difference between the third braking torque and the braking torque indicated by the third braking signal is greater than the preset torque value, and 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 Fig.10 As shown, at the third moment t3 after the second moment 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 moment t3 changes relative to the braking torque a2 indicated by the second braking signal received at the second moment t2. If the braking torque output by the electronic mechanical brake device 220 increases the output braking torque according to 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, the actual clamping force of the friction plate before adjustment at the third moment t3 will 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 the embodiment of the present application actively adjusts the increase value b32 of the third braking torque b3 output at the third moment t3 relative to the second braking torque b2 output at the second moment t2, so that the actual clamping force of the friction plate after adjustment at the third moment 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 moment t2 after the first moment t1, the difference between the braking torque output by other electronic mechanical braking devices 220 except at least one electronic mechanical braking device 220 among the multiple electronic mechanical braking devices 220 and the second braking torque output by at least one electronic mechanical braking device 220 is greater than a preset torque value according to the second braking signal.

[0138] The braking force distribution during the braking process of an electric vehicle usually results in different braking torques output by multiple electronic mechanical brake devices during the braking process. At a second moment t2 after the first moment t1, the temperature increase of the friction plate corresponding to at least one electronic mechanical brake device 220 is inconsistent with the temperature increase of the friction plates corresponding to other electronic mechanical brake devices. Accordingly, the change in the friction coefficient of the friction plate corresponding to at least one electronic mechanical brake device 220 is inconsistent with the change in the friction coefficient of the friction plates corresponding to other electronic mechanical brake devices.

[0139] At the second moment t2 after the first moment t1, the travel of the brake pedal remains unchanged, the friction coefficient of the friction plate corresponding to at least one of the multiple electronic mechanical brake devices 220 is inconsistent with the friction coefficient of the friction plate corresponding to other electronic mechanical brake devices, and if the second braking torque output by the multiple electronic mechanical brake devices 220 is the same as the difference between the braking torque indicated by the second brake signal, it will cause the clamping force of the friction plates corresponding to the multiple electronic mechanical brake devices 220 at the second moment t2 to be inconsistent with the clamping force at the first moment t1, resulting in an unbalanced braking effect produced by the multiple electronic mechanical brake devices 220 of the electric vehicle, which in turn causes the braking effect of the electric vehicle to fail to meet the driver's expectations or causes the electric vehicle to produce unexpected deviation or slippage.

[0140] The braking control method provided in the embodiment of the present application controls the braking torque output by other electronic mechanical braking devices 220 except at least one electronic mechanical braking device 220 at the second moment t2 to be different from the braking torque output by at least one electronic mechanical braking device 220, so that the clamping force of the friction plates corresponding to the multiple electronic mechanical braking devices 220 at the second moment t2 remains consistent with the clamping force at the first moment t1, and the braking effects generated by the multiple electronic mechanical braking devices 220 of the electric vehicle are balanced, thereby improving the braking performance of the electric vehicle.

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

[0142] In one embodiment, at a second moment t2 after the first moment t1, the temperature value of the friction plate corresponding to at least one electronic mechanical braking device 220 is greater than the temperature value of the friction plate corresponding to other electronic mechanical braking devices 220, and accordingly, the friction coefficient of the friction plate corresponding to at least one electronic mechanical braking device 220 is greater than the friction coefficient of the friction plate corresponding to other electronic mechanical braking devices 220.

[0143] The braking control method provided in the embodiment of the present application controls the second braking torque b2 output by at least one electronic mechanical braking device 220 at the second moment t2 to be smaller than the braking torque a2 indicated by the second braking signal and the first braking torque b1 output at the first moment t1, and controls the difference between the braking torque output by other electronic mechanical braking devices 220 and the braking torque a2 indicated by the second braking signal to be smaller than the difference between the second braking torque b2 output by at least one electronic mechanical braking device 220 and the braking torque a2 indicated by the second braking signal.

[0144] Since the friction coefficient of the friction plate corresponding to at least one electronic mechanical braking device 220 at the second moment t2 is greater than the friction coefficient of the friction plate corresponding to other electronic mechanical braking devices 220, the braking control method provided in the embodiment of the present application controls the braking torque output by other electronic mechanical braking devices 220 to be greater than the second braking torque b2 output by at least one electronic mechanical braking device 220, so that the clamping force of the friction plates corresponding to multiple electronic mechanical braking devices 220 at the second moment t2 remains consistent with the clamping force at the first moment t1, thereby ensuring the balance of the braking effects generated by multiple electronic mechanical braking devices 220 of the electric vehicle, thereby improving the braking performance of the electric vehicle.

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

[0146] In one embodiment, at a second moment t2 after the first moment t1, the temperature value of the friction plate corresponding to at least one electronic mechanical braking device 220 is lower than the temperature value of the friction plate corresponding to other electronic mechanical braking devices 220, and accordingly, the friction coefficient of the friction plate corresponding to at least one electronic mechanical braking device 220 is higher than the friction coefficient of the friction plate corresponding to other electronic mechanical braking devices 220.

[0147] The braking control method provided in the embodiment of the present application controls the second braking torque b2 output by at least one electronic mechanical braking device 220 at the second moment t2 to be greater than the braking torque a2 indicated by the second braking signal and the first braking torque b1 output at the first moment t1, and controls the difference between the braking torque output by other electronic mechanical braking devices 220 and the braking torque a2 indicated by the second braking signal to be greater than the difference between the second braking torque b2 output by at least one electronic mechanical braking device 220 and the braking torque a2 indicated by the second braking signal.

[0148] Since the friction coefficient of the friction plate corresponding to at least one electronic mechanical braking device 220 at the second moment t2 is greater than the friction coefficient of the friction plate corresponding to other electronic mechanical braking devices 220, the braking control method provided in the embodiment of the present application controls the braking torque output by other electronic mechanical braking devices 220 to be smaller than the second braking torque b2 output by at least one electronic mechanical braking device 220, so that the clamping force of the friction plates corresponding to multiple electronic mechanical braking devices 220 at the second moment t2 remains consistent with the clamping force at the first moment t1, thereby ensuring the balance of the braking effects generated by multiple electronic mechanical braking devices 220 of the electric vehicle, thereby improving the braking performance of the electric vehicle.

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

[0150] In one embodiment, the braking torque a3 indicated by the third braking signal is greater than the braking torque a2 indicated by the second braking signal. In the braking control method provided in the embodiment of the present application, in response to the braking torque a3 indicated by the third braking signal being greater than the braking torque a2 indicated by the second braking signal, the third braking torque b3 output by at least one electronic mechanical braking device 220 is controlled to have an increase value greater than the difference a23 between the braking torque a3 indicated by the third braking signal and the braking torque a2 indicated by the second braking signal, and the braking torque output by other electronic mechanical braking devices 220 is controlled to have an increase value less than the difference a23 between the braking torque a3 indicated by the third braking signal and the braking torque indicated by the second braking signal.

[0151] In one embodiment, the braking torque a3 indicated by the third braking signal is less than the braking torque a2 indicated by the second braking signal. In the braking control method provided in the embodiment of the present application, in response to the braking torque a3 indicated by the third braking signal being less than the braking torque a2 indicated by the second braking signal, the third braking torque b3 output by at least one electronic mechanical braking device 220 is controlled to have a reduction value b relative to the second braking torque b2 that is less than the reduction value of the braking torque a3 indicated by the third braking signal and the braking torque a2 indicated by the second braking signal, and the reduction value of the braking torque output by other electronic mechanical braking devices 220 is controlled to be greater than the reduction value of the braking torque a3 indicated by the third braking signal and the braking torque a2 indicated by the second braking signal.

[0152] The braking control method provided in the embodiment of the present application adjusts the torque change amplitudes of the multiple electronic mechanical braking devices 220 according to the temperature difference of the multiple electronic mechanical braking devices 220 at the third moment t3, so that the clamping force of the friction plates corresponding to the multiple electronic mechanical braking devices 220 at the third moment t3 meets the expected clamping force, thereby ensuring the balance of the braking effect of the electric vehicle, thereby improving the braking performance of the electric vehicle.

[0153] Fig.11 Another schematic diagram of an electronic mechanical brake device provided in an embodiment of the present application. In one embodiment, as Fig.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 steps on the brake pedal for a long time, each electronic mechanical brake device will brake the corresponding wheel. In the first moment after each electronic mechanical brake device brakes the corresponding wheel, the wheel end controller 221 receives the first brake signal and controls the corresponding brake motor to output the first brake torque. At a second moment after the first moment, after the wheel end controller 221 receives the second brake signal, the temperature estimation module A1 estimates the clamping force value of the friction plate at the first moment and the wheel speed V of the above-mentioned wheel at the second moment. L and the ambient temperature T of the electric vehicle a Calculate the estimated friction plate temperature T k The clamping force compensation module A2 calculates the estimated temperature T k The clamping force calculation module A3 calculates the clamping force reference value N0 of the friction plate according to the rotation angle of the brake motor at the second moment. ref The fusion module A4 calculates the clamping force compensation value N0 and the clamping force reference value N1 according to the above clamping force compensation value N0 and the above clamping force reference value N1. ref Finally, the control signal output module A5 outputs a control signal Cs of the brake motor according to the above-mentioned clamping force estimation value N1, and the above-mentioned control signal Cs is used to control the brake motor to output the second braking torque T m1 To drive the actuator to clamp the brake disc of the electric vehicle.

[0155] In one embodiment, after the clamping force estimation value N1 is confirmed, the control signal output module A5 can directly generate the temperature estimation value T k The change relationship between the corresponding clamping force value and the braking torque output by the brake motor 222 outputs 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, the temperature estimation value Tk It can be calculated as follows:

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

[0158] ΔT h =V×F c ×P;

[0159] ΔT c1 =(h×ΔT+ΔT×R)×A;

[0160]

[0161] In the above formula, T k represents the estimated temperature value of the friction plate of the actuator 223 at the current moment, T k-1 represents the estimated temperature value of the friction plate of the actuator 223 at the last moment, △T h Indicates the heat generation of the friction plate, △T c1 Indicates the heat dissipation of the friction plate, △T c2 represents the radiant heat of the friction plate, V represents the wheel speed at the current moment, and F c represents the clamping force value of the friction plate at the last moment, P represents the calibrated heat generation coefficient, and △T represents the estimated temperature value T of the friction plate at the last moment k-1 The current ambient temperature T a temperature difference, h represents the convection heat transfer coefficient of the friction plate, R represents the material thermal resistance of the friction plate, ε represents the emissivity of the friction plate surface, 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 moment and the first moment can be determined according to the calculation cycle of the wheel-end controller 221, the signal acquisition cycle of the brake pedal, the transmission delay of the signal, and the driver's brake pedal stepping method. For example, when the driver steps on the brake pedal intermittently, the time interval between the second moment and the above-mentioned first moment needs to be determined according to the calculation cycle of the wheel-end controller 221, the signal acquisition cycle of the brake pedal, the transmission 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 moment and the first moment is determined according to the calculation cycle of the wheel-end controller 221, the transmission delay of the signal, and the signal acquisition cycle of the brake pedal.

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

[0164] In one embodiment, the relationship between the clamping force compensation value and the temperature of the friction plate can be calibrated by experimental data and stored in a memory. The 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 a memory. Based on this, the clamping force compensation module A2 can calculate the temperature estimated value T k The corresponding clamping force compensation value is queried from the memory. The clamping force compensation value may be positive or negative. For example, when the temperature of the friction plate is greater than the thermal decay temperature of the friction plate, the clamping force compensation value is positive. When the temperature of the friction plate is less than the thermal decay 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 moment, the corresponding clamping force reference value can be queried from the memory.

[0165] In one embodiment, when the travel of the brake pedal changes, the wheel-end controller 221 may also receive a third brake signal and control the brake motor to output a third brake torque at a third moment after the second moment, wherein 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 the preset torque value.

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

[0167] In the above manner, the wheel-end controller 221 can calculate the temperature estimate of the friction plate through the wheel speed at the current moment, the ambient temperature of the electric vehicle and the clamping force value of the friction plate at the previous moment without installing a temperature sensor and a clamping force sensor, and compensate the clamping force of the friction plate according to the temperature estimate to output a corresponding control signal, so that after the brake motor adjusts the output braking torque according to the control signal, the clamping force provided by the friction plate is closer to the expected clamping force corresponding to the braking torque indicated by the braking signal.

[0168] Fig.12 Another schematic diagram of an electronic mechanical brake device provided in an embodiment of the present application. In one embodiment, as Fig.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 is used to calculate another clamping force estimation value N2 of the friction plate according to the transmission ratio of the actuator, the moment of inertia of the brake motor, the friction force of the friction plate at the previous moment, the rotation angle of the brake motor at the previous moment, and the braking torque. The Kalman filter submodule A52 is used to perform Kalman filtering on the above-mentioned clamping force estimation value N1 and the above-mentioned other clamping force estimation value N2 to obtain a target clamping force estimation value N3 of the friction plate. The signal generation submodule A53 generates a control signal of the brake motor according to the above-mentioned target clamping force estimation value N3, and the control signal is used to control the brake motor 222 to output the second braking torque. The signal generation submodule A53 can generate a control signal of the brake motor according to the change relationship between the clamping force value of the friction plate at the temperature corresponding to the temperature estimation value 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 estimation value N2 obtained by torque balance calculation and the clamping force estimation value N1 compensated according to the temperature estimation value to make the target clamping force estimation value N3 closer to the clamping force value corresponding to the braking signal, thereby further improving the braking accuracy of the electronic mechanical braking device.

[0170] In one embodiment, the clamping force estimation value output by the torque balance calculation submodule A51 can be calculated according to the following method:

[0171]

[0172] In the above formula, T m 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 tot represents the moment of inertia of the brake motor 222, θ represents the rotation angle of the brake motor 222 at the current moment, T fIt represents the friction force of the friction plate at the previous moment, and sgn() represents the sign function.

[0173] During the braking process of the electric vehicle, the friction plate of the actuator 223 will 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 will cause the temperature of the friction plate to change, thereby causing the friction force of the friction plate to change. In order to more accurately calculate the estimated value of the clamping force of the friction plate, it is necessary to calibrate the friction force of the friction plate of the actuator 223 during the braking process. Among them, the operator can calibrate the friction force of the actuator 223 during the clamping process or the release process through experimental data. Then, the wheel-end controller 221 can calculate the corresponding clamping force estimate value according to the braking torque output by the brake motor 222 at the current moment, the rotation angle of the brake motor 222 at the current moment, 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 the clamping process 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 brake torque output by the brake motor 222 to the actuator 223 drives the clamping force generated by the actuator 223 to change, so that the change of the friction force of the friction plate during the braking process is different. Therefore, the operator needs to calibrate the friction force of the friction plate in all aspects according to various braking scenarios established by 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 brake signal.

[0175] Fig.13 Another schematic diagram of an electronic mechanical brake device provided in an embodiment of the present application. In one embodiment, as Fig.13 As shown, the signal generating submodule A53 is further used to generate a signal according to the target clamping force estimation value N3 and the braking torque estimation value T of the brake motor at the second moment. b The verification is performed to obtain another target clamping force estimation value. On this basis, the signal generation submodule A53 outputs a control signal of the brake motor according to the another target clamping force estimation value, and the control signal is used to control the brake motor to output a second braking torque.

[0176] In the above manner, 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 brake controller 260 or the vehicle controller can be used according to the vehicle speed V c , acceleration a, yaw rate Y v , load m and wheel speed V of each wheelL The wheel end braking torque estimation value of each electronic mechanical braking device is calculated and sent to the wheel end braking torque estimation value. The braking controller or the vehicle controller can calculate the wheel end braking torque estimation value according to the vehicle acceleration a, yaw angular velocity Y v and load m to calculate the vertical load of each wheel. In addition, the brake controller or vehicle controller can calculate the vertical load of each wheel according to 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 according to 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 calibration quantity of the relationship between the wheel adhesion coefficient and the slip rate, λ represents the wheel slip rate, and F z Indicates the vertical load on the wheel.

[0180] Then, the brake controller 260 can adjust the longitudinal force F of each wheel according to the longitudinal force F of each wheel. x , the calibration quantity of the relationship between the wheel adhesion coefficient and the slip rate, the current wheel driving torque, the current wheel braking torque, and the wheel radius to calculate the wheel end braking torque estimate. The wheel end braking torque estimate is calculated as follows:

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

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

[0183] Wheel end braking torque estimation value T b The following relationship exists between the clamping force value and the clamping force value:

[0184]

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

[0186] In one embodiment, the signal generation submodule A53 can use the above-mentioned target clamping force estimate as the above-mentioned other target clamping force estimate when the difference between the clamping force value corresponding to the above-mentioned wheel-end braking torque estimate and the above-mentioned target clamping force estimate is less than a reference threshold. In addition, the signal generation submodule A53 can use the clamping force estimate corresponding to the wheel-end braking torque estimate as the above-mentioned other target clamping force estimate when the difference between the clamping force value corresponding to the above-mentioned wheel-end braking torque estimate and the above-mentioned target clamping force estimate is greater than a reference threshold. The clamping force value of the friction plate is positively correlated with the braking torque output by the brake motor 222. Therefore, after the above-mentioned other target clamping force estimate 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 and the braking torque output by the brake motor 222.

[0187] In the above manner, the wheel-end controller 221 can generate a control signal based on the clamping force estimate value corresponding to the wheel-end braking torque estimate value and the clamping force value that better meets the requirements among the above-mentioned target clamping force estimate values, so that the clamping force of the friction plate can be closer to the expected clamping force corresponding to the braking torque indicated by the braking signal.

[0188] In one embodiment, the signal generating submodule A53 may perform Kalman filtering on the clamping force value corresponding to the wheel-end braking torque estimation value and the one target clamping force estimation value to obtain the other target clamping force estimation value.

[0189] In one embodiment, when the travel of the brake pedal changes, the wheel-end controller 221 may also receive a third brake signal and control the brake motor to output a third brake torque at a third moment after the second moment, wherein 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 the preset torque value.

[0190] Among them, after receiving the third brake signal, the temperature estimation module A1 calculates the temperature estimation value of the friction plate according to the target clamping force estimation value of the friction plate at the second moment, the wheel speed of the above-mentioned one wheel at the third moment, and the ambient 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 moment. The fusion module A4 calculates a 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 torque balance calculation submodule A51 calculates another clamping force estimation value of the friction plate according to the transmission ratio of the actuator, the rotational inertia of the brake motor, the friction force of the friction plate at the third moment, the rotation angle of the brake motor at the third moment, and the braking torque. The Kalman filter submodule A52 performs Kalman filtering on the above-mentioned one clamping force estimation value and the above-mentioned another clamping force estimation value to obtain a target clamping force estimation value of the friction plate. The signal generating submodule A53 generates a control signal of the brake motor according to the above-mentioned target clamping force estimation value, and the control signal is used to control the brake motor to output a third braking torque.

[0191] In summary, the embodiment of the present application provides an electronic mechanical brake device and a brake control method for an electric vehicle, which are applied to the field of electric vehicle technology to improve the braking effect of the electronic mechanical brake device when braking the wheel. Among them, the electronic mechanical brake device includes 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 moment after the electronic mechanical brake device brakes the above-mentioned one wheel. At a second moment after the first moment, the controller receives a second brake signal and controls the brake motor to output a second brake torque. Among them, 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 the preset torque value, and the difference between the second brake torque and the first brake torque is greater than the preset torque value. In the above manner, the controller can adjust the brake signal output to the brake motor during the braking process to adjust the brake torque output by the brake motor, 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, thereby improving the braking accuracy of the electronic mechanical brake device when braking the wheel.

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

[0193] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. An electromechanical brake device, characterized in that: The electromechanical brake device is used to brake a wheel of an electric vehicle, and the electromechanical brake device is also used to: At a first moment after the electronic mechanical brake device continues braking, receiving a first braking signal and outputting a first braking torque; At a second moment after the first moment, receiving a second braking signal and outputting a second braking torque; 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 brake device according to claim 1, characterized in that: When the duration of braking the one wheel by the electronic mechanical brake device is longer than the first preset duration and shorter than or equal to the second preset duration, the temperature of the friction plate is shorter 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 longer than the second preset duration, the temperature of the friction plate is higher than the thermal decay temperature of the friction plate; the electronic mechanical brake device is further used for: At the first moment, the electronic mechanical brake device brakes the one wheel for a time period greater than the first preset time period and less than or equal to the second preset time period, and outputs the first braking torque that is less than the braking torque indicated by the first braking signal; At the second moment, the electronic mechanical braking device brakes the one wheel for a period longer than the second preset period, and outputs the second braking torque that is greater than the first braking torque.

3. The electromechanical brake device according to claim 1 or 2, characterized in that: The electromechanical brake device is also used for: At a third moment after the second moment, receiving a third braking signal and outputting a third braking torque; In which, 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 brake device according to claim 3, characterized in that: At the third moment, the temperature of the friction plate is less than or equal to the thermal decay temperature of the friction plate, and the electronic mechanical brake device is further used for: The third braking torque is controlled to be smaller than the braking torque indicated by the third braking signal.

5. The electromechanical brake device according to claim 4, characterized in that: The electromechanical brake 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 output is controlled to be greater than the second braking torque, and an increase value of the third braking torque relative to the second braking torque is less than an increase value 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 third braking torque output is controlled to be less than the second braking torque, and a reduction value of the third braking torque relative to the second braking torque is greater than a reduction value of the braking torque indicated by the third braking signal relative to the braking torque indicated by the second braking signal.

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

7. The electromechanical brake device according to claim 6, characterized in that: The electromechanical brake 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, controlling the third braking torque to be greater than the second braking torque, an increase value of the third braking torque relative to the second braking torque being greater than an increase value 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, a reduction value of the third braking torque relative to the second braking torque is controlled to be less than a reduction value of the braking torque indicated by the third braking signal relative to the braking torque indicated by the second braking signal.

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

9. The electromechanical brake device according to claim 8, characterized in that: The control signal output module comprises: a torque balance calculation submodule, used for calculating 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 force of the friction plate at the second moment, the rotation angle of the brake motor at the second moment, and the brake torque; A Kalman filter submodule, configured to perform Kalman filtering on the one clamping force estimation value and the other clamping force estimation value to obtain a target clamping force estimation value of the friction plate; A signal generating submodule is used to generate the control signal according to the one target clamping force estimation value, or to obtain another target clamping force estimation value by verifying the one target clamping force estimation value and the braking torque estimation value of the brake motor at the second moment, and to generate the control signal according to the other target clamping force estimation value.

10. An electric vehicle, characterized in that: The electric vehicle comprises a plurality of wheels and a plurality of electromechanical braking devices as described in any one of claims 1 to 9, wherein the plurality of electromechanical braking devices are used to brake the plurality of wheels respectively during a 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 electronic mechanical braking devices during the continuous braking process of the electric vehicle, and the braking control method includes: At a first moment after the electric vehicle is continuously braked, controlling one or more electronic mechanical brake devices to output a first braking torque according to a first braking signal, wherein a 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, controlling at least one electronic mechanical brake device 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 being 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 being greater than the preset torque value; At a third moment after the second moment, the at least one electronic mechanical braking device is controlled to output a third braking torque according to a 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, and 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 brake control method according to claim 11, characterized in that: The braking control method further comprises: At a second moment after the first moment, the difference between the braking torque output by other electronic mechanical braking devices except the at least one electronic mechanical braking device among the plurality of electronic mechanical braking devices and the second braking torque is controlled to be greater than the preset torque value according to the second braking signal.

13. The brake control method according to claim 12, characterized in that: At the second moment, the temperature of the friction plate corresponding to the at least one electronic mechanical brake device increases and the temperature value is less than the thermal decay temperature, 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 devices, and the braking control method further includes: At the second moment, the second braking torque output by the at least one electronic mechanical braking device is controlled to be smaller 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 electronic mechanical braking devices and the braking torque indicated by the second braking signal is controlled to be smaller than the difference between the second braking torque output by the at least one electronic mechanical braking device and the braking torque indicated by the second braking signal.

14. The brake control method according to claim 12, characterized in that: At the second moment, the temperature of the friction plates corresponding to the multiple electronic mechanical brake devices increases and the temperature value is greater than the thermal decay temperature, and the temperature value of the friction plates corresponding to at least one electronic mechanical brake device is less than the temperature value of the friction plates corresponding to the other electronic mechanical brake devices, and the braking control method further includes: At the second moment, the second braking torque output by the at least one electronic mechanical 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 electronic mechanical 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 electronic mechanical braking device and the braking torque indicated by the second braking signal.

15. The brake control method according to claim 11, characterized in that: At the third moment, the temperature of the friction plate corresponding to the at least one electronic mechanical brake device further increases and the temperature value is greater than the thermal decay temperature, and the temperature of the friction plate corresponding to the other electronic mechanical brake device further increases and the temperature value is less than the thermal decay temperature, and 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, controlling the increase value of the third braking torque output by the at least one electronic mechanical braking device relative to the second braking torque 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 controlling the increase value of the braking torque output by the other electronic mechanical braking devices 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 third braking torque output by the at least one electronic mechanical braking device is controlled to have a reduction value relative to the second braking torque that is 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 braking torque output by the other electronic mechanical braking devices is controlled to have a reduction value that is 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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