CN117818544A

CN117818544A - Wheel end brake device with parking re-clamping function, brake system and method

Info

Publication number: CN117818544A
Application number: CN202311867644.6A
Authority: CN
Inventors: 张云光; 黄崇玺; 倪辉
Original assignee: Huawei Digital Power Technologies Co Ltd
Current assignee: Huawei Digital Power Technologies Co Ltd
Priority date: 2023-12-29
Filing date: 2023-12-29
Publication date: 2024-04-05

Abstract

The application provides a wheel end braking device with a parking and re-clamping function, a braking system and a braking method, relates to the field of new energy automobiles, and can be applied to pure electric vehicles and hybrid vehicles. The wheel end braking device comprises a braking unit, a parking unit and a wheel end controller. The braking unit comprises a braking motor and a braking caliper, the braking motor is used for outputting braking torque to drive the braking caliper to output clamping force to a brake disc of the vehicle, and the parking unit is used for locking the braking motor. The wheel end controller responds to the fact that the difference value between the clamping force output by the braking unit and the target clamping force is smaller than the preset difference value for a preset duration, and the wheel end controller is used for controlling the parking unit to lock the braking motor. According to the scheme, the risk of sliding due to insufficient clamping force output by the brake calipers in the parking process of the vehicle can be reduced, and the safety and reliability of parking are improved.

Description

Wheel end brake device with parking re-clamping function, brake system and method

Technical Field

The present application relates to the field of vehicle control, and more particularly, to a wheel end brake apparatus, brake system and method with park reclamping.

Background

A brake system for an automobile is a system that applies a certain braking force to wheels of the automobile to forcibly brake the wheels to a certain extent. The braking system is used for forcedly decelerating or even stopping the running automobile according to the requirements of a driver or a controller, or stabilizing the stopped automobile under various road conditions (such as on a slope), or stabilizing the speed of the automobile running downhill. Compared with the traditional mechanical hand brake, the electronic parking brake (Electronic Parking Brake, EPB) system can control the motor of the parking brake device mounted on the wheel through the built-in electronic control unit (electronic control unit, ECU) to clamp and release the wheels, and can provide proper braking force for the vehicle according to different road conditions to realize electronic parking of the vehicle. On a vehicle with the EPB system, a driver can realize the braking of the vehicle through simple switch operation (an electronic hand brake button), and can also generate braking to the running vehicle through the EPB system in the driving process, so that a certain braking force is provided under an emergency condition, and the occurrence of accidents is avoided.

When the vehicle runs on a road section which runs at high speed and descends and needs continuous braking, the temperature of the brake disc can be increased, if the vehicle is parked after being braked strongly at the moment, after the brake disc is clamped by the driving calipers, the vehicle can shrink due to temperature reduction caused by heat dissipation of the brake disc and air convection, the actual clamping force is reduced, the braking efficiency is affected, the parking braking force can be possibly insufficient, and the parking safety is directly threatened. The conventional scheme is to judge whether the clamping force needs to be increased or not through temperature or heat calculation, so that the error is large, the influence factors are many, and the risk of sliding the vehicle after the vehicle is parked due to inaccurate temperature estimation and not performing the re-clamping function is still caused.

How to achieve safe parking is a problem that needs to be solved.

Disclosure of Invention

The application provides a wheel end braking device with parking and clamping functions, braking system and method, whether judge because the clamping force changes because the clamping force through real time monitoring, when monitoring the clamping force is not enough, control parking unit and press from both sides again to reduce the swift current car risk that the clamping force is not enough and arouse after the vehicle parking, realize safe parking.

In a first aspect, the present application provides a wheel end brake device for a vehicle having a parking re-clamping function, the wheel end brake device including a brake unit, a parking unit, and a wheel end controller. The braking unit comprises a braking motor and a braking caliper, the braking motor is used for outputting braking torque to drive the braking caliper to output clamping force to a brake disc of the vehicle, and the parking unit is used for locking the braking motor. The wheel end controller responds to the fact that the difference value between the clamping force output by the braking unit and the target clamping force is smaller than the preset difference value for a preset duration, and the wheel end controller is used for controlling the parking unit to lock the braking motor.

And in the preset time period, the wheel end controller can always monitor the output clamping force of the brake caliper, and if the difference between the output clamping force of the brake unit and the target clamping force is always smaller than the preset difference in the preset time period, the wheel end controller controls the parking unit to lock the brake motor. Because the clamping force changes, for example, the temperature of a brake disc is reduced, the brake motor is locked again for a period of time after the clamping force is output, and whether the clamping force changes can be monitored in the period of time, so that the risk of sliding of the vehicle caused by insufficient clamping force after the clamping force is high Wen Zhuche is reduced, and the safe parking is realized.

With reference to the first aspect, in some implementations of the first aspect, the wheel end controller is configured to control the brake unit to increase the clamping force output before controlling the parking unit to lock the brake motor in response to a difference between the clamping force output by the brake unit and the target clamping force within a preset time period after the clamping force output by the brake unit being greater than or equal to a preset difference.

If the difference between the clamping force output by the braking unit and the target clamping force within the preset duration is greater than or equal to the preset difference, the fact that the clamping force output by the brake caliper is insufficient is indicated, and the wheel end controller is used for controlling the braking unit to increase the clamping force output and controlling the parking unit to lock the braking motor, so that the brake disc can be fully clamped before the braking motor is locked, and the safety and reliability of parking are improved.

With reference to the first aspect, in certain implementations of the first aspect, the wheel end controller is responsive to a parking signal, the wheel end controller is configured to output a first control signal, the first control signal is configured to control the motor to output a brake torque, and the brake torque is configured to drive the brake caliper to output a target clamping force indicated by the parking signal. The wheel end controller responds to the fact that after the first control signal is output for a preset time period, the difference value between the clamping force output by the brake caliper and the target clamping force is smaller than the preset difference value, the wheel end controller is used for outputting a second control signal, and the second control signal is used for controlling the parking unit to lock the brake motor.

When the vehicle needs to be parked, the wheel end controller receives a parking signal, and responds to the parking signal, a first control signal is output to the brake motor, so that the brake motor outputs a brake torque to drive the brake caliper to output a target clamping force, and the brake disc is clamped, namely clamped for the first time. And the wheel end controller responds to the fact that after the first control signal is output for a preset time, the difference value between the clamping force output by the brake caliper and the target clamping force is smaller than a preset difference value, so that the parking unit is controlled to lock the brake motor, and parking is completed. When the brake caliper outputs the target clamping force, the output actual clamping force may be reduced due to the temperature reduction, and parking is completed only when the difference between the output actual clamping force and the target clamping force is smaller than the preset difference value for more than a preset time period, that is, the value of the actual clamping force is unchanged or is changed for more than the preset difference value and the duration time is longer than the preset time period.

According to the scheme of this application, whether judging because brake disc temperature reduces and lead to the clamp force to change through the control clamp force, carry out the action of clamping again by the change control brake unit of clamp force, whether need increase the clamp force through temperature or heat calculation judgement, avoided because the inaccurate great problem of error that leads to of temperature estimation to reduce the vehicle and because of high Wen Zhuche after, the clamp force is not enough and the swift current car risk that arouses realizes safe parking.

With reference to the first aspect, in certain implementations of the first aspect, the wheel end controller is configured to output a re-clamping signal for controlling the brake motor to increase the brake torque output to increase the clamping force output by the brake caliper in response to a difference between the clamping force output by the brake caliper and the target clamping force being greater than or equal to a preset difference within a preset period of time of outputting the first control signal.

Because the brake disc and air are subjected to convection heat dissipation, the temperature is reduced and the brake disc is contracted, the actual clamping force is reduced, the braking efficiency is affected, and the parking braking force may be insufficient. The wheel end controller can determine whether a re-clamping signal needs to be output by monitoring the actual clamping force output by the brake caliper. After the first clamping, the actual clamping force output by the brake caliper is reduced from the value of the target clamping force, and when the difference value between the actual clamping force and the target clamping force is larger than or equal to a preset difference value, the wheel end controller outputs a re-clamping signal to control the brake motor to increase the braking torque so as to increase the actually output clamping force, namely, the re-clamping function is executed. Through clamping again, the risk of insufficient parking braking force caused by the temperature reduction of the brake disc can be reduced, and safe parking is realized.

With reference to the first aspect, in certain implementations of the first aspect, the re-clamping signal is used to control the brake motor to increase the brake torque output to thereby increase the clamping force of the brake caliper output to the target clamping force.

The re-clamping signal may control the difference between the clamping force increase output by the brake caliper and the target clamping force indicated by the park signal to be less than a predetermined difference.

With reference to the first aspect, in certain implementations of the first aspect, the parking unit includes a parking motor and a lock lever, a rotor of the brake motor is sleeved with a ratchet, the ratchet is used for being connected with the lock lever to lock the brake motor, and the parking motor is used for driving the lock lever to lock to execute parking; in response to the second control signal, the parking motor is configured to output a torque to drive the lock lever to lock the brake motor.

The wheel end braking device comprises two motors, a braking motor and a parking motor, wherein the wheel end controller is used for controlling the two motors, the braking motor is used for driving a brake caliper to output clamping force, the clamping force controls vehicle braking through a brake disc, the parking motor is used for driving a lock rod to lock the braking motor, and the lock rod can be connected and locked with a ratchet wheel on a rotor of the braking motor, so that parking is completed.

With reference to the first aspect, in certain implementation manners of the first aspect, in response to a difference between the clamping force output by the brake caliper and the target clamping force within the preset time period after the re-clamping signal is output, the wheel end controller is configured to re-output the re-clamping signal. The wheel end controller responds to the fact that the difference value between the clamping force output by the brake caliper after the preset time period and the target clamping force is smaller than the preset difference value, and the wheel end controller is used for outputting a second control signal to control the parking unit to lock the brake motor and electrify the brake motor after the brake motor is locked.

If the wheel end controller controls the brake unit to clamp the brake disc again, and then the clamping force output by the brake calipers is still insufficient, the wheel end controller outputs a re-clamping signal again, and the cycle is performed until the clamping force output by the brake calipers meets the requirement, so that the brake disc can be clamped when the vehicle can be parked. If the clamping force output by the brake calipers is enough after the wheel end controller controls the brake unit to clamp the brake disc again, the parking unit directly locks the brake motor, the wheel end controller is powered down after the brake motor is locked, and the parking process is finished.

With reference to the first aspect, in some implementations of the first aspect, a difference between the clamping force output by the brake caliper and the target clamping force after the wheel end controller responds to the output of the re-clamping signal for a preset number of times is still greater than or equal to a preset difference, the wheel end controller is used for outputting a second control signal to control the parking unit to lock the brake motor and power down after the brake motor is locked, the preset number of times is greater than or equal to 3, or a difference between the clamping force output by the brake caliper and the target clamping force after the wheel end controller responds to the first output of the re-clamping signal for a preset time threshold is still greater than or equal to a preset difference, and the wheel end controller is used for outputting a second control signal to control the parking unit to lock the brake motor and power down after the brake motor is locked, and the preset time threshold is greater than 1 minute.

If the clamping force output by the brake caliper is still insufficient after the clamping is repeated for a plurality of times, or the clamping force is still insufficient after the parking process lasts for too long, the parking unit can lock the brake motor and output an alarm signal for reminding a driver that the current clamping force is insufficient.

With reference to the first aspect, in certain implementations of the first aspect, the wheel end controller is configured to end the powered-up state in response to the parking unit locking the brake motor.

When the wheel end controller outputs a first control signal, the wheel end controller keeps a power-on state after the brake caliper finishes clamping for the first time, and detects the change of the clamping force. When the wheel end controller outputs a re-clamping signal, the brake caliper increases the output clamping force, and the postRun time is prolonged, so that the power-on state is kept continuously. When the wheel end controller outputs a second control signal, the parking unit locks the brake motor to finish parking, and the wheel end controller can finish maintaining the power-on state at the moment, and can execute power-down after finishing subsequent control.

With reference to the first aspect, in certain implementations of the first aspect, the wheel end brake device further includes a clamp force sensor, and the wheel end controller is configured to receive a clamp force signal from the clamp force sensor, the clamp force signal being configured to indicate a clamp force output by the brake caliper.

The clamping force sensor can detect the clamping force actually output by the brake caliper, the detected clamping force is fed back to the wheel end controller, and the wheel end controller receives a detection signal from the clamping force sensor and judges whether the clamping needs to be carried out again according to the actual clamping force indicated by the detection signal.

With reference to the first aspect, in certain implementations of the first aspect, the clamping force signal is a periodic signal, the clamping force sensor is configured to periodically output the clamping force signal at preset time intervals, and the clamping force signal is configured to indicate a clamping force output by the brake caliper.

The clamping force sensor may periodically detect the actual clamping force, e.g. the value of the current clamping force may be read every 100ms cycle.

With reference to the first aspect, in certain implementations of the first aspect, the preset time period is greater than or equal to 2s and the preset time interval is greater than or equal to 100ms.

According to the scheme of the application, the time and the frequency of the value of the monitoring clamping force are set, so that the time of the safe parking process can be flexibly controlled, and the parking efficiency and the safety of the vehicle are improved.

With reference to the first aspect, in certain implementations of the first aspect, the wheel end controller includes a control circuit, a brake motor power circuit, and a parking motor power circuit, where the control circuit is configured to receive a parking signal, control the brake motor power circuit to output a first control signal, and control the parking motor power circuit to output a second control signal; the braking motor power circuit comprises a three-phase bridge arm, and the midpoint of the bridge arm of the three-phase bridge arm of the braking motor power circuit is used for being connected with a three-phase winding of the braking motor; the parking motor power circuit comprises a three-phase bridge arm, and the midpoint of the bridge arm of the three-phase bridge arm of the parking motor power circuit is used for being connected with a three-phase winding of the parking motor.

In a second aspect, the present application provides a brake system comprising a central controller and the wheel end brake device of the first aspect. The central controller responds to the parking signal, the central controller is used for controlling the wheel end controller to output a second control signal, or the wheel end controller is used for responding to the parking signal to output the second control signal, and the parking signal is used for indicating that the vehicle is in a parking state.

That is, the central controller may control the wheel end brake device to park, and the wheel end control device may also park directly according to the park signal. When the central controller fails, the wheel end braking device can automatically respond to the parking signal, so that the control reliability is improved. And the wheel end braking device directly responds to the parking signal, so that a signal transmission link can be shortened, and the control speed and control precision are improved.

With reference to the second aspect, in certain implementations of the second aspect, the brake system includes a central controller and a plurality of wheel end brake devices, the wheel end brake devices are used for receiving parking signals from the central controller, the wheel end brake devices include a wheel end controller, a brake unit and a parking unit, the brake unit includes a brake motor and a brake caliper, the brake motor is used for outputting brake torque to drive the brake caliper to output clamping force to a brake disc of the vehicle, the parking unit includes a parking motor and a lock rod, and the parking motor is used for driving the lock rod to lock the brake motor to execute parking; the central controller is used for responding to the parking requirement and outputting a first control signal to control the braking unit to output a target clamping force; and outputting a second control signal to control the parking unit to lock the brake motor in response to the fact that the duration of the difference between the output clamping force and the target clamping force is smaller than the preset difference is longer than the preset duration.

The central controller can receive a parking instruction sent by a driver and calculate a target clamping force required by the vehicle, so that a parking signal is sent to the wheel end controller.

The central controller may also perform the function of the wheel end controller, such as monitoring changes in actual clamping force, and in response to a parking demand, outputting a first control signal to the wheel end brake device such that the brake motor outputs a brake torque to drive the brake caliper to output a target clamping force to clamp the brake disc, i.e., first clamp. And the central controller responds to the fact that after the first control signal is output for a preset time, the difference value between the clamping force output by the brake caliper and the target clamping force is smaller than a preset difference value, so that the parking unit is controlled to lock the brake motor, and parking is completed. When the brake caliper outputs the target clamping force, the output actual clamping force may be reduced due to the temperature reduction, and parking is completed only when the difference between the output actual clamping force and the target clamping force is smaller than the preset difference value for more than a preset time period, that is, the value of the actual clamping force is unchanged or is changed for more than the preset difference value and the duration time is longer than the preset time period.

With reference to the second aspect, in certain implementations of the second aspect, the central controller is configured to control the brake unit to increase the clamping force output by the brake caliper to the target clamping force in response to a difference between the clamping force output by the brake caliper before the parking unit locks the brake motor being greater than or equal to a preset difference.

In a third aspect, there is provided a control method for a brake system including a plurality of wheel end brake devices including a wheel end controller, a brake unit including a brake motor for outputting a brake torque to drive the brake caliper to output a clamping force to a brake disc of a vehicle, and a parking unit including a parking motor and a lock lever for locking the brake motor, the control method including controlling the brake unit to output the clamping force in response to a parking signal; the parking unit locks the brake motor in response to the difference between the clamping force output by the brake caliper after the brake unit outputs the clamping force for a preset period of time and the target clamping force being smaller than the preset difference; and outputting a re-clamping signal in response to the difference between the clamping force output by the brake caliper and the target clamping force within a preset time period after the clamping force is output by the brake unit being greater than or equal to a preset difference, wherein the re-clamping signal is used for controlling the brake unit to increase the clamping force output.

With reference to the third aspect, in some implementations of the third aspect, the control method includes, in response to a difference between the clamping force output by the brake caliper and the target clamping force within a preset time period after the output of the re-clamping signal being still greater than or equal to a preset difference, re-outputting the re-clamping signal; and responding to the fact that the difference value between the clamping force output by the brake caliper and the target clamping force after the preset time period is smaller than the preset difference value, and locking the brake motor by the parking unit.

With reference to the third aspect, in some implementations of the third aspect, the control method includes, in response to a difference between a clamping force output by the brake caliper and a target clamping force being still greater than or equal to a preset difference after outputting the re-clamping signal a preset number of times, locking the brake motor by the parking unit, the preset number of times being greater than or equal to 3; or the difference value between the clamping force output by the brake caliper and the target clamping force is still larger than or equal to the preset difference value after the first time of outputting the re-clamping signal for a preset time threshold value, and the parking unit locks the brake motor, wherein the preset time threshold value is larger than 1 minute.

With reference to the third aspect, in certain implementations of the third aspect, the wheel end brake device further includes a clamp force sensor for periodically outputting a clamp force signal at preset time intervals, the clamp force signal being for indicating a clamp force output by the brake caliper, the method further including receiving the clamp force signal from the clamp force sensor.

In a fourth aspect, there is provided a vehicle comprising a power battery and a braking system as in the second aspect and in various implementations of the second aspect, wherein the power battery is adapted to supply current to the wheel end brake device.

In particular, the advantages of the other aspects may refer to the advantages described in the first aspect, and will not be described here again.

Drawings

FIG. 1 is a schematic illustration of a vehicle provided in an embodiment of the present application;

FIG. 2 is a schematic illustration of a braking system provided in an embodiment of the present application;

FIG. 3 is a schematic diagram of a brake disc versus temperature provided in an embodiment of the present application;

FIG. 4 is a schematic view of a wheel end brake apparatus provided in an embodiment of the present application;

FIG. 5 is a further schematic illustration of a wheel end brake apparatus provided in an embodiment of the present application;

fig. 6 is a schematic view of a parking unit according to an embodiment of the present application;

FIG. 7 is a schematic diagram of locking a lock lever according to an embodiment of the present disclosure;

FIG. 8 is a schematic diagram of a wheel end controller signal according to an embodiment of the present application

FIG. 9 is another schematic illustration of a braking system provided in an embodiment of the present application;

FIG. 10 is another schematic illustration of a braking system provided in an embodiment of the present application;

FIG. 11 is a schematic diagram of a control method according to an embodiment of the present disclosure;

FIG. 12 is a schematic diagram of a control architecture provided in an embodiment of the present application;

FIG. 13 is a schematic diagram of a control flow provided in an embodiment of the present application;

fig. 14 is a schematic diagram of clamping force and time provided by an embodiment of the present application.

Detailed Description

The technical solutions in the present application will be described below with reference to the accompanying drawings. The following detailed description of the embodiments and the accompanying drawings are provided to illustrate the principles of the present application and are not intended to limit the scope of the application, i.e., the application is not limited to the embodiments described.

With the wide popularization and application of automobiles, the safety problem of automobiles is getting more and more attention.

Fig. 1 is a schematic diagram of a vehicle according to an embodiment of the present application. As shown in fig. 1, the vehicle 10 includes wheels, a braking system 100. The brake system 100 includes a brake pedal, a central controller 120, and a wheel end brake device 110. During a driving operation of the driver, when the vehicle 10 is required to brake, the driver depresses a brake pedal, the central controller 120 receives a brake signal from the brake pedal and outputs a brake torque signal to the four wheel end brake devices 110, and the wheel end brake devices 110 are configured to receive the brake torque signal and output a friction braking force to the brake disc 104 according to an indication of the brake torque signal.

Fig. 2 is a schematic diagram of a braking system provided in an embodiment of the present application. As shown in fig. 2, the brake system 100 includes four wheel end brakes 110 and a central controller 120. The vehicle 10 may also include a power battery (not shown) coupled to the input of the wheel end brake device 110, the power battery providing electrical current to the wheel end brake device 110. The vehicle 10 also includes a brake pedal and a park button by which the driver can control the vehicle's travel state. The central controller 120 is used to control the wheel end brake device 110 to perform braking and/or parking according to the stroke of the brake pedal and the state of the parking button.

The present application is mainly applied to a parking process of a vehicle, and the vehicle 10 may be any one of different types of automobiles such as a sedan, a van, a passenger train, etc., or may be a passenger or cargo carrying transportation device such as a tricycle, a two-wheeled vehicle, a train, etc., or may be any other type of transportation means driven by a conventional power source or other power battery. The vehicle 10 includes, but is not limited to, a pure electric vehicle (pure electric vehicle/battery electric vehicle, pure EV/battery EV), a hybrid electric vehicle (hybrid electric vehicle, HEV), an extended range electric vehicle (range extended electric vehicle, REEV), a plug-in hybrid electric vehicle (PHEV), a new energy vehicle (new energy vehicle, NEV), and the like.

In a vehicle chassis system, an Electro-Mechanical Brake (EMB) is adopted to replace an Electro-hydraulic Brake (Electro-Hydraulic Brake System, EHB) and has the advantages of high response speed, high precision, no liquid leakage and the like, and the safety performance is greatly improved while the arrangement is flexible and the maintenance cost is reduced. The wheel assembly of the EMB system consists of a wheel control board, a brake motor, a speed reducer, an execution machine, a friction plate, an EPB motor and the like. The electronic parking system EPB is used as a part of a chassis braking domain, can be integrated in a wheel side assembly of the EMB system, and can complete parking locking through a single EPB motor to realize automatic control.

The vehicle is parked after continuous braking, and the temperature profile of the brake disc over time is shown in fig. 3 (a). After parking, the temperature of the brake disc may be attenuated by heat dissipation, and the temperature of the brake disc may be gradually reduced as time increases. The temperature drop with respect to the initial position of clamping will result in a reduced brake disc volume and a consequent reduction in clamping force. In addition, as shown in fig. 3 (b), the friction factor of the brake disc is also lowered by the decrease in temperature. Thus, with increasing time, the temperature gradually decreases, the friction factor of the brake disc decreases, and the clamping force decreases. As shown in fig. 3 (c), the final effect caused by the combination of the above two factors is that the braking force of the parking brake is attenuated with the decrease of the temperature, and as the temperature decreases, the clamping force that the brake disc can output is reduced compared with the initial clamping position, so that the braking force may be insufficient, and the risk of sliding a vehicle is increased.

In one possible implementation, the model may be used to calculate the amount of change in brake disc temperature when the vehicle is high Wen Zhuche, and the high temperature re-clamping action is performed when a preset value is reached.

In another possible implementation, when the vehicle is high Wen Zhuche, the heat production of the single rear wheel brake disc is calculated, the temperature of the brake disc at the time of stopping braking is obtained, and if the temperature is greater than a threshold value, the driving current of the parking motor is increased, so that the electronic caliper is further clamped.

In another possible implementation, based on the EHB system, the wheel speed, the ambient temperature, and the wheel cylinder pressure during parking are obtained through calculation to obtain the brake disc temperature, and whether the temperature threshold is exceeded or not is determined and re-clamping is performed.

It should be understood that in the above implementation manner, the execution strategy of clamping after high-temperature braking is mostly closed-loop controlled by temperature, the temperature change caused by the convective heat exchange between the brake disc and air is calculated through a model, and whether the clamping function is started or not is judged through a temperature threshold. However, the error of the environmental temperature estimation on the change of the clamping force is larger, the longer influence factors of the control loop are more, and the re-clamping function or the ECU is powered down in advance possibly because of inaccurate temperature estimation, so that the risk of sliding the vehicle still exists after the vehicle is parked.

Based on the above problems, the application provides a wheel end braking device with parking and clamping functions, a braking system and a method, which are used for judging whether the clamping force changes due to the fact that the temperature of a brake disc is reduced or not by monitoring the value of a clamping force sensor in real time, and controlling the system to clamp again when the change of the clamping force is monitored, so that the risk of sliding of a vehicle caused by insufficient clamping force after the vehicle is Wen Zhuche is reduced, and safe parking is realized.

In the description of the present application, it should be noted that, unless explicitly specified and limited otherwise, the terms "disposed," "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be directly connected or indirectly connected through an intermediate medium. The specific meaning of the terms in the present application can be understood as appropriate by one of ordinary skill in the art. The term "comprising" as used in this application should not be construed as limited to what is listed thereafter; it does not exclude other elements or steps. Thus, it should be interpreted as specifying the presence of the stated features, integers, steps or components as referred to, but does not preclude the presence or addition of one or more other features, integers, steps or components, or groups thereof. Thus, the expression "a device comprising means a and B" should not be limited to a device consisting of only components a and B.

The present application provides a wheel end brake device 110.

As shown in fig. 4, the wheel end brake device 110 includes a wheel end controller 111, a brake unit 112, and a parking unit 115.

The brake unit 112 includes a brake motor 114 and a brake caliper, the brake motor 114 for outputting a brake torque to drive the brake caliper to output a clamping force to a brake disc of the vehicle 10, the clamping force being used to generate a friction force between the brake unit 112 and the brake disc.

The brake unit 112 may include a thrust bearing, a ball screw assembly, a piston, etc., and the brake unit 112 is used to convert the rotational torque of the brake motor 114 into a linear clamping force, and to pressurize the brake disc through the friction plate, thereby achieving a braking effect.

Fig. 5 is a schematic view of a wheel end brake device 110 according to an embodiment of the present application. As shown in fig. 5, the actuator includes a brake caliper, and during vehicle braking, the wheel end controller 111 drives the brake motor 114, which in turn drives the brake caliper to clamp the brake disc 104, to generate a brake torque.

The parking unit 115 is used to lock the brake motor 114.

The parking unit 115 is configured to lock the brake motor 114 in response to the difference between the clamping force output from the brake unit 112 and the target clamping force being less than the preset difference for a preset period of time.

The parking unit 115 is configured to lock the brake motor 114 in response to the difference between the clamping force output by the brake unit 112 and the target clamping force after the brake unit 112 outputs the clamping force for a preset period of time being smaller than a preset difference. The parking unit 115 is configured to lock the brake motor 114 after the brake unit 112 increases the clamping force output in response to the difference between the clamping force output by the brake unit 112 and the target clamping force being greater than a preset difference after the brake unit 112 outputs the clamping force for a preset period of time.

Each wheel end brake device 110 includes a parking unit 115. The parking unit 115 includes a parking motor and a lock lever. During operation of the vehicle, the central controller 120 receives a parking signal, the central controller 120 transmits the parking signal to the wheel end controller 111, the wheel end controller 111 controls the brake motor 114 to drive the brake caliper to clamp the brake disc, and after the brake disc is clamped, the wheel end controller 111 controls the parking motor to drive the locking mechanism, such as the lock rod, to lock the brake motor, so that the actuator is kept in a state of clamping the brake disc and is not released, and the vehicle is kept in a parking state.

The park signal may be from an electronic park brake system (Electronic Parking Brake, EPB) system that generates and communicates the park signal to the central controller 120 when the driver presses the EPB button, the central controller 120 further transmitting the park signal to the wheel end controller 111. In one embodiment, the electronic parking brake system may also be directly connected to the wheel end controller 111, that is, the parking signal generated by the electronic parking system may be directly transmitted to the wheel end controller without passing through the central controller 120, which may make the transmission path of the parking signal shorter, thereby improving the accuracy and control speed of the parking controller.

In the embodiment of the application, the parking signal may also be from other parking systems, for example, when the driver adjusts the gear of the vehicle to P gear, the parking signal may be generated, or the parking signal may also be from an automatic parking system (Auto Hold). The wheel end controller 111 may directly receive the parking signal or the central controller 120 may receive the parking signal before transmitting the parking signal to the wheel end controller 111.

Fig. 6 is a schematic view of the parking unit 115 according to the embodiment of the present application. As shown in fig. 6, the parking unit includes a parking motor and a locking lever including pawls and ratchet wheels that cooperate with each other. The pawl is arranged on the rotor of the parking motor, and when the parking motor rotates, the pawl can be driven to rotate along with the rotation of the rotor of the parking motor. The ratchet wheel is sleeved on the rotor of the brake motor 114, and when the brake motor 114 rotates, the ratchet wheel can be driven to rotate along with the rotation of the rotor of the brake motor. When the vehicle is parked, the parking motor rotates to drive the pawl to rotate, and the pawl can be clamped into the gear groove of the ratchet wheel, so that the braking motor 114 is locked.

Fig. 7 is a schematic view of a process of locking a brake motor by a lock lever according to an embodiment of the present application. Fig. 7 (a) is a schematic view of the case where parking is not performed, and when parking is not performed, the pawl is out of the inter-tooth grooves of the ratchet wheel, and the rotor of the brake motor 114 can be rotated freely, i.e., the brake motor 114 is not locked. In fig. 7 (b), when parking, the ratchet is locked in the inter-tooth groove of the ratchet, the rotor of the brake motor 114 is locked and cannot rotate freely, and the brake motor 114 cannot rotate, so that the actuator always maintains the clamped state of the brake disc, and the vehicle 10 is in the parking state.

When parking, parking motor and brake motor in this application embodiment can rotate simultaneously, that is to say, at the in-process that parking motor rotates and drives pawl and be close to the ratchet, brake motor rotates with opposite direction and drives the ratchet rotation, can make the ratchet card in the inter-tooth groove of ratchet more easily like this to the success rate of parking and the fail safe nature of vehicle operation have been improved.

As shown in fig. 8, during parking of the vehicle, the wheel end controller 111 is responsive to a parking signal, the wheel end controller 111 is configured to output a first control signal for controlling the brake motor 114 to output a brake torque for driving the brake caliper to output a target clamping force indicated by the parking signal.

The wheel end controller 111 is configured to output a second control signal for controlling the parking unit to lock the brake motor 114 in response to the difference between the clamping force output by the brake unit and the target clamping force being less than the preset difference for a preset period of time.

The target clamping force indicated by the parking signal is sent to the wheel end controller 111 by the central controller 120, and the target clamping force may be obtained through calculation or may be preset, which is not limited in this application.

In one possible embodiment, the wheel end controller 111 is further configured to output a re-clamping signal for controlling the brake motor 114 to increase the brake torque output and thereby the brake caliper output clamping force in response to the brake unit outputting the clamping force having a difference from the target clamping force greater than or equal to the preset difference within a preset time period.

Because the brake disc and air are subjected to convection heat dissipation, the temperature is reduced and the brake disc is contracted, the actual clamping force is reduced, the braking efficiency is affected, and the parking braking force may be insufficient. The wheel end controller can determine whether a re-clamping signal needs to be output by monitoring the actual clamping force output by the brake caliper. After the first clamping, the actual clamping force output by the brake caliper is reduced from the value of the target clamping force, and when the difference value between the actual clamping force and the target clamping force is larger than or equal to a preset difference value, the wheel end controller outputs a re-clamping signal to control the brake motor to increase the braking torque so as to increase the actually output clamping force, namely, the re-clamping function is executed.

In one possible embodiment, the re-clamping signal is used to control the brake motor 114 to increase the brake torque output so that the clamping force of the brake caliper output increases to the target clamping force.

The preset difference and the preset time period may be preset, or may be calculated by the central controller 120 and then indicated to the wheel end controller 111.

The parking unit 115 includes a parking motor and a locking bar, a rotor of the braking motor 114 is sleeved with a ratchet, the ratchet is used for being connected with the locking bar to lock the braking motor 114, and the parking motor is used for driving the locking bar to lock to perform parking.

The wheel end controller 111 transmits a second control signal to the parking unit 115 in response to the difference between the actual clamping force and the target clamping force being less than the preset difference for a period of time greater than the preset period of time, and the parking motor outputs torque to drive the lock lever to lock in response to the second control signal to perform parking.

The wheel end controller 111 maintains the power-on state in response to the brake unit 112 increasing the output clamping force. The wheel end controller 111 ends maintaining the powered-on state in response to the parking unit 115 completing the parking.

During parking of the vehicle, the wheel end controller 111 maintains a power-on state, and in response to the parking unit 115 completing parking, the wheel end controller 111 is configured to perform power-down.

The wheel end brake device 110 further includes a clamping force sensor 113, the clamping force sensor 113 being configured to detect a clamping force output by the brake caliper and output a detection signal, the detection signal being configured to indicate the clamping force output by the brake caliper.

The clamping force sensor 113 may be another detection device, and may be mounted on the brake caliper portion or other portions of the brake unit, which is not limited in this application.

The wheel end controller 111 is configured to acquire a detection signal output from the detection clamp force sensor 113, and the detection signal is configured to instruct the brake unit 112 to output an actual clamp force.

In one possible embodiment, the detection signal is a periodic signal, and the clamping force sensor 113 is configured to periodically detect the clamping force at preset time intervals and output the detection signal.

The clamp force sensor 113 may detect the output clamp force at preset time intervals and periodically transmit a detection signal to the wheel end controller 111.

Illustratively, the clamp force sensor 113 reads the value of the current clamp force every 100ms cycle.

In one possible embodiment, the clamping force sensor 113 is configured to detect the clamping force at a preset point in time and output a detection signal.

The clamp force sensor 113 may also detect at preset time points and send detection signals to the wheel end controller 111 according to time nodes.

Illustratively, the clamp force sensor 113 may read the value of the clamp force at a time node of 100ms,200ms,400ms,700ms, etc., after the first clamp.

In one possible embodiment, the preset time period is greater than or equal to 2s and the preset time interval is greater than or equal to 100ms.

The wheel end controller 111 includes a control circuit, a brake motor power circuit, and a parking motor power circuit, wherein the control circuit is configured to receive a parking signal, control the brake motor power circuit to output a first control signal, and control the parking motor power circuit to output a second control signal; the braking motor power circuit comprises a three-phase bridge arm, and the midpoint of the bridge arm of the three-phase bridge arm of the braking motor power circuit is used for being connected with a three-phase winding of the braking motor; the parking motor power circuit comprises a three-phase bridge arm, and the midpoint of the bridge arm of the three-phase bridge arm of the parking motor power circuit is used for being connected with a three-phase winding of the parking motor.

In the parking process of the vehicle, the central controller 120 responds to the parking instruction of the parking sensor, namely, receives the parking instruction of the driver, sends a parking signal to the wheel end controller 111, the wheel end controller 111 drives the reducer clamp caliper to clamp through the brake motor 114, and meanwhile, the clamping force sensor 113 feeds back the actual value of the current output clamping force of the wheel end controller 111. The wheel end controller 111 performs control by an algorithm to determine whether to perform the re-clamping operation. Finally, the parking motor is controlled to drive the locking rod locking motor, the wheel end controller 111 is powered down, and parking operation is completed.

According to the scheme of this application, through the change of clamp force sensor control clamp force, reduced control loop length, eliminate the error that the temperature estimation brought, reduce the vehicle because of high Wen Zhuche after, the clamp force is not enough and the swift current car risk that arouses has improved parking security.

It should be understood that the control algorithm may also be executed in the central controller, and during parking of the vehicle, the central controller 120 sends a first control signal to the wheel end brake device 110 in response to a parking command of the parking sensor, i.e. receiving a parking command of the driver, and drives the decelerator clamp caliper to clamp through the brake motor 114, while the clamp force sensor 113 feeds back to the central controller 120 an actual value of the current output clamp force. The central controller 120 performs control by an algorithm to determine whether to perform the re-clamping operation. Finally controlling the parking motor to drive the locking rod locking motor.

The present application provides a brake system 100 with park reclassifying function, comprising a central controller 120 and a plurality of wheel end brakes 110.

The wheel end brake device 110 is configured to receive a parking signal from the central controller 120.

In one possible implementation, the central controller 120 is configured to output a first control signal to control the brake unit to output a target clamping force in response to a parking demand; in response to the difference between the clamping force output by the brake unit and the target clamping force being less than the preset difference for a duration greater than the preset duration, that is, for a preset duration, a second control signal is output to control the parking unit to lock the brake motor 114.

In one possible implementation, the wheel end brake device 110 is configured to control the brake unit 112 to output a target clamping force indicated by the parking signal in response to the parking signal; the parking unit 115 is controlled to lock the brake motor 114 in response to the difference between the output clamping force and the target clamping force being less than the preset difference for a period of time greater than the preset period of time.

The central controller 120 is configured to send a parking signal to the wheel end controller in response to a parking command of the parking sensor.

The central controller 120 may receive a parking command from the driver and calculate a target clamping force required for the vehicle, thereby transmitting a parking signal to the wheel end controller.

The description of the wheel end brake device 110 may be referred to in the foregoing description, and will not be repeated here.

Referring to fig. 9 and 10, fig. 8 and 9 are schematic control architecture diagrams of two brake systems 100 according to an embodiment of the present application. As shown in fig. 9, in the brake system 100 of fig. 9, the wheel end controller 111 may directly receive the parking signal and the clamping force signal output from the clamping force sensor 113. As shown in fig. 10, in the brake system 100 of fig. 10, a central controller 120 is used to receive a parking signal and a clamping force signal output from a clamping force sensor 113.

The present application provides a control method 200 for a brake system.

As shown in fig. 11, the method includes the steps of:

s210, responding to the parking signal, controlling the brake motor to output the braking torque to drive the brake caliper to output the target clamping force indicated by the parking signal.

And S220, controlling the brake motor to increase the brake torque output so as to increase the clamping force output by the brake caliper to the target clamping force in response to the difference between the clamping force output by the brake caliper and the target clamping force being greater than or equal to a preset difference.

It should be appreciated that if the brake disc temperature does not change or changes little during parking, then the clamping force may not change or changes little, and the difference between the clamping force output by the brake caliper and the target clamping force does not necessarily exceed the preset difference, then the wheel end brake device does not necessarily perform re-clamping, i.e. step S220 may not be performed.

And S230, responding to the fact that the duration that the difference value between the clamping force output by the brake caliper and the target clamping force is smaller than the preset difference value is longer than the preset duration, and the parking motor is used for outputting torque to drive the lock rod to lock the brake motor.

The above method can be applied in the architecture of a wheel end brake device as in fig. 10.

As shown in fig. 12, the wheel end brake device includes a brake motor, a parking motor, an EPB lock lever, a wheel end controller, a decelerator, a clamp force sensor, a caliper, a brake disc, and a central controller.

The parking motor is connected with the lock rod, the clamping force sensor, the calipers and the brake disc form a caliper sub-assembly, the caliper sub-assembly is connected to the speed reducer through the gear set, the speed reducer is controlled by the brake motor, and the lock rod can lock the brake motor.

During vehicle parking, the wheel end controller performs the method 200 described above.

The wheel end controller 111 carries the control method described above, which may be a software algorithm, integrated into the wheel end brake device 110. The received signals include a parking command of the driver, a detection signal of the clamping force sensor (i.e., an actual clamping force signal), and a target clamping force calculated by the central controller, the controller processes postRun time internally, and the output signals include driving signals for controlling two motors (a brake motor and a parking motor), the driving signals including the first control signal, the second control signal, and the re-clamping signal described above. The wheel end controller 111 determines whether to perform the re-clamping control by the difference between the target clamping force and the actual clamping force.

It should be understood that the control method 200 may also be performed in the central controller 120, which is not described herein.

The present application provides a vehicle 10.

The vehicle comprises a power battery and the braking system, wherein the power battery is used for supplying current to the wheel end braking device.

The vehicle further includes a brake pedal and a parking button, and the central controller 120 is configured to control the wheel end brake device to perform braking and/or parking according to a stroke of the brake pedal and a state of the parking button.

As shown in fig. 11, the parking process of the vehicle may have the following flow.

First, the central controller 120 receives a driver's parking request, such as the driver depressing a brake pedal and/or pressing an EPB parking button. The parking signal is sent to the wheel end controller 111 of the wheel end brake device 110, and the wheel end controller 111 sends a first control signal to the brake unit 112, so that the brake motor 114 in the brake unit 112 outputs torque to enable the brake caliper to output a clamping force to clamp the brake disc.

Then, the clamping force sensor 113 detects the clamping force actually output by the brake unit 112, and transmits a detection signal to the wheel end controller 111. The clamp force sensor, illustratively, periodically reads the actual clamp force value at a preset, e.g., 100ms, and sends it to the wheel end controller 111 while maintaining the wheel end controller powered on state.

If it is detected that the value of the actual clamping force decays beyond the set threshold, i.e. the difference between the actual clamping force and the target clamping force is greater than or equal to the preset difference, the wheel end controller 111 sends a re-clamping signal, which instructs the control brake unit 112 to perform a re-clamping action, and issues a command to the brake motor 114 to increase the clamping force. And extends the postRun time of the wheel end controller 111.

In one possible implementation, the wheel end controller 111 re-outputs the re-clamping signal in response to the difference between the clamping force output by the brake caliper and the target clamping force remaining greater than or equal to the preset difference for a preset period of time after the re-clamping signal is output. In response to the difference between the clamping force output by the brake caliper and the target clamping force being less than the preset difference after the preset period of time, a second control signal is output to control the parking unit 115 to lock the brake motor 114 and to power down after the brake motor 114 is locked.

It will be appreciated that this re-clamping process may be repeated as in fig. 13, and if the clamping force output by the brake caliper is still insufficient after the wheel end controller 111 controls the brake unit 112 to re-clamp the brake disc, the wheel end controller 111 will again output a re-clamping signal and so cycle until the clamping force output by the brake caliper meets the requirements, so that the brake disc can be clamped while in park. If the clamping force output from the brake caliper is sufficient after the wheel end controller 111 controls the brake unit to re-clamp the brake disc, the parking unit 115 directly locks the brake motor, the wheel end controller 111 is powered down after the brake motor is locked, and the parking process is ended.

In one possible implementation, the difference between the clamping force output by the brake caliper and the target clamping force after the wheel end controller 111 outputs the re-clamping signal for a preset number of times is still greater than or equal to a preset difference, the wheel end controller 111 is used for outputting a second control signal to control the parking unit to lock the brake motor and power down after the brake motor is locked, the preset number of times is greater than or equal to 3, or the difference between the clamping force output by the brake caliper and the target clamping force after the wheel end controller 111 outputs the re-clamping signal for the first time for a preset time threshold is still greater than or equal to a preset difference, and the wheel end controller 111 is used for outputting the second control signal to control the parking unit to lock the brake motor and power down after the brake motor is locked, and the preset time threshold is greater than 1 minute.

In one possible implementation, if no change in the value of the clamping force or no change exceeding a threshold is detected, i.e. the duration of time that the difference between the actual clamping force and the target clamping force is less than the preset difference is greater than a preset duration, the clamping force increasing action is not performed for a duration exceeding a set time threshold.

At this time, the wheel end controller transmits a second control signal to the parking unit 115 in response to the difference between the actual clamping force and the target clamping force being less than or equal to the preset difference for a period of time greater than the preset period of time, the second control signal being for instructing the parking unit 115 to perform parking. The parking motor locks the position of the braking motor through the lock rod, and the power-down of the wheel end controller 111 is synchronously completed, so that the parking action is completed.

Illustratively, as shown in fig. 14, the wheel end controller 111 controls the brake unit 112 to output the target clamping force, the brake unit 112 at t ₁ The target clamping force is reached at a time, and then the clamping force actually output by the brake unit 112 is lowered due to the influence of the temperature decrease. At t ₂ At this time, the controller 111 detects that the actual clamping force drops to a difference from the target clamping force greater than or equal to a preset difference through the clamping force sensor 113, at which time a re-clamping signal is transmitted to the brake unit 112, and the brake unit 112 increases the output clamping force according to the re-clamping signal. At t ₃ At this time, the clamping force actually output by the brake unit 112 is still reduced due to the influence of the temperature drop, the wheel end controller 111 detects that the difference between the actual clamping force and the target clamping force is greater than or equal to a preset difference through the clamping force sensor 113, and sends a re-clamping signal to the brake unit 112 again, and the brake unit 112 increases the output clamping force according to the re-clamping signal. At t ₄ After the moment, the clamping force output by the braking unit is not changed greatly, the attenuation value does not exceed the threshold value or is not changed, at the moment, the controller 111 detects that the difference value between the actual clamping force and the target clamping force is smaller than the preset difference value by the clamping force sensor 113 for a period longer than the preset period, a second control signal is output to the parking unit 115, the parking motor locks the position of the braking motor by the lock rod, and the wheel end controller 111 is powered down synchronously to complete the parking action.

It should be understood that the magnitude of the preset difference and the preset time period may be preset values or may be regulated.

It should be understood that the graph in fig. 14 is merely a schematic representation of possible variation trends, and actual variation situations may be different, and the application is not limited to the actual possible values.

According to the scheme, the control method is integrated on the wheel end controller, the advantages of EMB are brought into play, the safety braking system which is faster, higher in precision and flexible in arrangement is provided, the control method can adjust adaptive parameters according to different vehicles, flexibility is achieved, and parking safety of various vehicles can be improved.

Those of ordinary skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.

In the several embodiments provided in this application, it should be understood that the disclosed systems, devices, and methods may be implemented in other manners. For example, the apparatus embodiments described above are merely illustrative, e.g., the division of the units is merely a logical function division, and there may be additional divisions when actually implemented, e.g., multiple units or components may be combined or integrated into another system, or some features may be omitted or not performed. Alternatively, the coupling or direct coupling or communication connection shown or discussed with each other may be an indirect coupling or communication connection via some interfaces, devices or units, which may be in electrical, mechanical or other form.

Claims

1. A wheel end brake device with a parking and re-clamping function for a vehicle is characterized in that the wheel end brake device comprises a brake unit, a parking unit and a wheel end controller, wherein the brake unit comprises a brake motor and a brake caliper,

the parking unit is used for locking the brake motor;

The wheel end controller is used for:

and controlling the parking unit to lock the brake motor in response to the difference between the clamping force output by the brake unit and the target clamping force being smaller than a preset difference for a preset duration.

2. The wheel end brake apparatus of claim 1, wherein the wheel end controller is configured to:

and in response to the difference value between the clamping force output by the braking unit and the target clamping force within the preset time after the braking unit outputs the clamping force being greater than or equal to a preset difference value, controlling the braking unit to increase the clamping force output, and controlling the parking unit to lock the braking motor.

3. The wheel end brake apparatus of claim 1, wherein the wheel end controller is configured to sequentially output a first control signal and a second control signal in response to a parking signal, wherein:

the first control signal is used for controlling the brake motor to output a brake torque, and the brake torque is used for driving the brake caliper to output a target clamping force indicated by the parking signal;

and outputting a second control signal in response to the difference between the clamping force output by the brake caliper after outputting the first control signal for the preset time period and the target clamping force being smaller than a preset difference, wherein the second control signal is used for controlling the parking unit to lock the brake motor.

4. A wheel end brake apparatus according to claim 3, wherein the wheel end controller is further configured to:

and responding to the fact that the difference value between the clamping force output by the brake caliper and the target clamping force within the preset time period when the first control signal is output is greater than or equal to the preset difference value, and outputting a re-clamping signal, wherein the re-clamping signal is used for controlling the brake motor to increase the braking torque output so as to increase the clamping force output by the brake caliper.

5. The wheel end brake apparatus of claim 4, wherein the re-clamping signal is used to control the brake motor to increase the brake torque output to increase the clamping force of the brake caliper output to less than a preset difference from the target clamping force.

6. The wheel end brake apparatus of claim 4, wherein after outputting the re-clamping signal, the wheel end controller is further configured to:

responding to the fact that the difference value between the clamping force output by the brake caliper and the target clamping force within the preset time after the re-clamping signal is output is still greater than or equal to the preset difference value, and re-outputting the re-clamping signal;

and outputting a second control signal to control the parking unit to lock the brake motor and to power down after the brake motor is locked in response to the difference between the clamping force output by the brake caliper after the preset time period and the target clamping force is smaller than the preset difference.

7. The wheel end brake device of claim 6, wherein the wheel end controller is configured to:

responding to the fact that after the re-clamping signal is output for a preset number of times, the difference value between the clamping force output by the brake caliper and the target clamping force is still larger than or equal to the preset difference value, outputting the second control signal to control the parking unit to lock the brake motor and electrifying the parking unit after the brake motor is locked, wherein the preset number of times is larger than or equal to 3; or,

and responding to the preset time threshold value of the first output re-clamping signal, wherein the difference value between the clamping force output by the brake caliper and the target clamping force is still larger than or equal to the preset difference value, outputting the second control signal to control the parking unit to lock the brake motor and electrifying the brake motor after the brake motor is locked, and the preset time threshold value is larger than 1 minute.

8. A wheel end brake apparatus as claimed in claim 3, further comprising a clamp force sensor, the wheel end controller being adapted to receive a clamp force signal from the clamp force sensor, the clamp force signal being indicative of the clamp force output by the brake caliper.

9. The wheel end brake apparatus of claim 8, wherein the clamp force signal is a periodic signal, the clamp force sensor being configured to periodically output the clamp force signal at preset time intervals, the clamp force signal being configured to indicate a clamp force output by the brake caliper.

10. The wheel end brake apparatus of claim 9, wherein the predetermined time period is greater than or equal to 2s and the predetermined time interval is less than or equal to 100ms.

11. The wheel end brake apparatus of any of claims 1-10, wherein the wheel end controller includes a control circuit, a brake motor power circuit, and a park motor power circuit, wherein:

the control circuit is used for receiving a parking signal, controlling the brake motor power circuit to output a first control signal and controlling the parking motor power circuit to output a second control signal;

the braking motor power circuit comprises a three-phase bridge arm, and the midpoint of the bridge arm of the three-phase bridge arm of the braking motor power circuit is used for connecting a three-phase winding of the braking motor;

the parking motor power circuit comprises a three-phase bridge arm, and the midpoint of the bridge arm of the three-phase bridge arm of the parking motor power circuit is used for being connected with a three-phase winding of the parking motor.

12. A brake system for a vehicle having a parking reclamping function, characterized in that the brake system comprises a central controller and a wheel end brake device as claimed in any one of claims 1-10, the central controller being arranged to control the wheel end controller to output the second control signal in response to a parking signal, or the wheel end controller being arranged to output the second control signal in response to the parking signal, the parking signal being arranged to indicate that the vehicle is in a parked state.

13. A control method for a brake system, characterized in that the brake system comprises a plurality of wheel end brake devices, the wheel end brake devices comprising: a wheel end controller, a brake unit and a parking unit, the brake unit including a brake motor and a brake caliper, the brake motor for outputting a brake torque to drive the brake caliper to output a clamping force to a brake disc of a vehicle, the parking unit for locking the brake motor, the method comprising:

controlling the brake unit to output a clamping force in response to a parking signal;

the parking unit locks the brake motor in response to the difference between the clamping force output by the brake caliper after the clamping force is output by the brake unit for a preset time period and the target clamping force being smaller than a preset difference;

And outputting a re-clamping signal in response to the difference between the clamping force output by the brake caliper and the target clamping force within the preset time period after the clamping force is output by the brake unit being greater than or equal to a preset difference, wherein the re-clamping signal is used for controlling the brake unit to increase the clamping force output.

14. The method according to claim 13, characterized in that the method comprises:

and the parking unit locks the brake motor in response to the difference between the clamping force output by the brake caliper after the preset time period and the target clamping force being smaller than the preset difference.

15. The method according to claim 14, characterized in that the method comprises:

responding to the fact that after the re-clamping signal is output for a preset number of times, the difference value between the clamping force output by the brake caliper and the target clamping force is still larger than or equal to the preset difference value, and the parking unit locks the brake motor, wherein the preset number of times is larger than or equal to 3; or,

And responding to the difference value between the clamping force output by the brake caliper and the target clamping force after the first time of outputting the re-clamping signal for a preset time threshold value is still greater than or equal to the preset difference value, and locking the brake motor by the parking unit, wherein the preset time threshold value is greater than 1 minute.