CN210554753U

CN210554753U - Electronic parking brake

Info

Publication number: CN210554753U
Application number: CN201921655065.4U
Authority: CN
Inventors: 郭宇翔; 郭中阳; 孙明海
Original assignee: Zhejiang Libang Hexin Automotive Brake System Co ltd
Current assignee: Zhejiang Libang Hexin Automotive Brake System Co ltd
Priority date: 2019-09-30
Filing date: 2019-09-30
Publication date: 2020-05-19
Anticipated expiration: 2029-09-30

Abstract

The utility model discloses an electron parking brake, including calliper and motor, be equipped with friction disc A, friction disc B, piston, lead screw and nut on the calliper, friction disc B locates friction disc A opposite side, friction disc A is removed by piston drive, the piston removes through the cooperation of lead screw with the nut, the lead screw is rotated by motor drive, a serial communication port, the calliper outer wall is equipped with piezoelectric sensor, piezoelectric sensor pastes and locates calliper and take place great bending deformation department under the clamp force effect, need not change calliper inner structure, only can prevent through pasting piezoelectric sensor outward that the brake disc clamp force is not enough and swift current slope and excessively press from both sides tightly and cause the phenomenon that the vehicle dragged.

Description

Electronic parking brake

Technical Field

The utility model relates to a vehicle braking parking technical field, in particular to electron parking brake.

Background

The electronic parking brake system EPB replaces a mechanical hand brake device of a drag-line rear wheel brake shoe, and the layout design of the whole vehicle is simplified. The electronic parking brake system has the same working principle as a mechanical hand brake, and uses mechanical calipers to clamp a brake pad through a motor to generate brake torque so as to realize the parking brake function. And the electronic parking brake system is automatically released when the driving state condition is met. The improvement of the operability and the full utilization of the space in the vehicle are among the functions which are well received by the users. The EPB expansion value-added function eliminates the hidden danger of slope slipping accidents of ramp starting, signal lamp waiting and engine flameout, prevents some unnecessary accidents caused by paralysis, and improves the safety.

The electronic parking brake system can prevent the phenomenon that the parking brake is forgotten to be implemented after the engine is shut down. Because the electric switch replaces the function of a mechanical hand brake ratchet wheel and pawl device, the space arrangement in the vehicle becomes more free, and the electric switch is beneficial to improving the comfortable feeling and the feeling of drivers and passengers.

On the other hand, (1) how to maintain a proper and sufficient clamping force; (2) the dragging phenomenon caused by excessive clamping is prevented; (3) fail safe response means upon occurrence of an electronic failure remains a subject.

SUMMERY OF THE UTILITY MODEL

Not enough to prior art, the utility model provides an electron parking brake need not change calliper inner structure, only can prevent through pasting piezoelectric sensor outward that the brake disc clamp force is not enough and swift current slope and excessively press from both sides tightly and cause the phenomenon that the vehicle drags.

In order to achieve the above purpose, the utility model discloses a following technical scheme realizes: the electronic parking brake is characterized in that a piezoelectric sensor is arranged on the outer wall of the caliper and attached to a position, where the caliper is bent greatly, of the caliper under the action of clamping force.

The motor adopts the brushless DC motor, the motor sets the corner sensor who is used for gathering the electric motor rotor.

And the signals of the piezoelectric sensor and the rotation angle sensor form correlation verification. Redundancy measures for ensuring a failure safety mode are provided, and a signal safety mechanism is realized.

The piezoelectric sensor and the rotation angle sensor transmit signals to the MCU, and the MCU determines that the motor rotates to a target position according to a control strategy algorithm.

The MCU also receives an EPB key input signal and an ignition switch signal.

The electronic parking braking method is characterized in that if the target state is established, the parking braking is locked, and the vehicle slipping monitoring is stopped; if the target state is not established, stopping locking by the parking brake;

the target state satisfying condition is as follows: the speed of the front wheel is less than or equal to x kph at 2, the speed of the rear wheel is less than or equal to xx kph at x kph and less than or equal to 2, the ignition switch is turned on, and the EPB switch button is released;

the target state does not satisfy the condition: 1 front wheel speed > x kph, or 1 rear wheel speed > xx kph, or the ignition switch is turned off.

When an EPB key is requested, the ECU judges an input signal, if the target state is established, parking braking is finished, vehicle sliding detection is stopped, and if the target is not established, or the EPB key is released, the parking braking state is released;

if the vehicle speed is increased during parking braking, but a driver does not step on an accelerator pedal and re-clamping is finished, monitoring and activating a clamping state of a parking lock, feeding back a signal by a piezoelectric sensor, calculating a required clamping force by combining a ramp angle signal, sending a re-clamping request instruction, and rotating a motor to implement target clamping force control;

if the parking locking clamping state is monitored and activated, an accelerator pedal is stepped down or a re-clamping request is sent when the engine works, parking braking is finished, and vehicle sliding detection is stopped;

and if the monitoring of the clamping state of the parking lock is activated, the parking brake state is released when an EPB button is released or a target is not established.

When the outer wall of the caliper is pressed to generate bending deformation, the piezoelectric sensor senses the pressure change, so that the charge distribution of the caliper is changed, the generated electric signal can be calibrated as the wheel cylinder clamping force, and the wheel cylinder clamping force control for keeping the vehicle stably and reliably parked is determined by the feedback of different working conditions such as the vehicle in a ramp way.

When the motor receives the command of the MCU to implement clamping driving, the motor rotates according to a given angle according to a control algorithm to drive the screw rod, and then the screw rod is driven to push the nut to push the piston to eliminate a gap between the friction plates, so that the action of clamping the brake disc is completed. When the friction plate applies clamping force to the brake disc, the outer wall of the caliper is deformed by expansion force, and the charge change of the piezoelectric sensor is converged into a micro-voltage signal to be output and fed back to the MCU.

The rotation angle sensor and the piezoelectric sensor are matched with each other to check each other, the parking braking state of the EPB is monitored to the maximum extent, and from the safety perspective, if the EPB of the automobile running at high speed fails, the piezoelectric sensor monitors that the target state of the EPB is not established and braking pressurization occurs, and the MCU controls the motor to give up unintended braking; and similarly, when the rotation angle sensor monitors that the EPB target state is not established and braking pressurization occurs, the MCU can also control the motor to give up unintended braking, and the safety and reliability of the automobile in the driving process are ensured.

Drawings

FIG. 1 is a schematic view of the structure of the caliper of the present invention;

FIG. 2 is a schematic view of a caliper cantilever force;

FIG. 3 is a schematic diagram of a system control architecture;

FIG. 4 is a parking brake state transition diagram;

FIG. 5 is a schematic diagram of EPB operating condition state transition;

fig. 6 is a motor workload diagram.

Detailed Description

As shown in fig. 1 and 2, the electronic parking brake includes a caliper 1 and a motor 2, a friction plate a11, a friction plate B12, a piston 3, a lead screw 4 and a nut 5 are arranged on the caliper 1, the friction plate B12 is arranged on the opposite side of the friction plate a11, the friction plate a11 is driven by the piston 3 to move, the piston 3 moves by the matching of the lead screw 4 and the nut 5, the lead screw 4 is driven by the motor 2 to rotate, and then the lead screw is driven to push the nut to push the piston to eliminate the gap between the friction plates, so as to complete the action of clamping the brake disc.

The outer wall of caliper 1 is equipped with piezoelectric sensor 6, piezoelectric sensor 6 pastes and locates caliper 1 and takes place great bending deformation department under the clamp force effect, in this embodiment, piezoelectric sensor adopts the piezoceramics sensor, friction disc B12 is located caliper cantilever 111 inboard, and piezoelectric sensor 6 then pastes and locates the outside of caliper cantilever 111, and when friction disc A11 removed to friction disc B12 and presss from both sides tight brake disc 10, caliper cantilever 111 can receive outside pressure and produce bending deformation, and piezoelectric sensor 6 can sense. The design does not need to change the internal structure of the caliper, and the clamping state of the brake disc can be reliably detected in real time only by sticking the piezoelectric sensor to the outer wall of the outer caliper.

If the motor implementing the clamping driving force is a dc brushed motor, no rotation angle sensor signal of the motor rotor is required for its control. Under this condition, the utility model discloses can only adopt piezoelectric sensor to monitor the clamping state of brake disc, the detection of clamping state can utilize motor load current to mark, but motor load current receives the influence of factors such as temperature as marking the ratio easily.

If the motor for implementing the clamping driving force is a direct-current brushless motor, a rotation angle sensor is required to be arranged to collect a motor rotor, therefore, the motor 2 is provided with the rotation angle sensor 7 for collecting the motor rotor, the problem that the clamping composite current of the motor is easily influenced by the ambient temperature is solved, and the reliability of the system and the accuracy of performance realization are effectively improved.

As shown in fig. 3, the signals of the piezoelectric sensor 6 and the rotation angle sensor 7 form a correlation check, the piezoelectric sensor 6 and the rotation angle sensor 7 transmit the signals to the MCU 100, and the MCU 100 determines that the motor 2 rotates to a target position according to a control strategy algorithm. The piezoelectric sensor 6 is connected to the MCU 100 through an amplifying circuit 200.

The MCU also receives an EPB key input signal and an ignition switch signal.

As shown in fig. 4, the electronic parking brake method:

the target state establishment condition is as follows: the speed of the front wheel is not less than 2 and not more than x kph, meanwhile, the speed of the rear wheel is not less than 2 and not more than xx kph, the ignition switch is turned on, and the EPB switch button is released.

201: if the target state is established, parking braking is locked, and vehicle sliding monitoring is stopped;

202: if the target state is not established, the parking brake stops locking.

As shown in fig. 5, when the EPB button requests, the ECU determines the input signal, if the target state is established, the parking brake is completed, the rolling detection is stopped, if the target is not established, or the EPB button is released, the parking brake state is released;

As shown in fig. 6, when the brake disc clamping is performed, the current and speed of the motor change trend is as shown. The speed, current and pressure tend to be flat during the final clamping phase.

The clamping force of the parking brake and the uphill and downhill level land form a certain proportional relation, and can be calibrated according to the actual vehicle. When the system supply voltage changes and is in the condition of extreme environmental temperature, the pre-calibrated clamping parameters have great deviation from the actually generated clamping force. In this case, the control target of the control strategy algorithm is realized by motor position control; but clamping force feedback is required to ensure that sufficient clamping force is provided to prevent roll-off. The piezoelectric sensor directly measures the caliper strain, and the strain faithfully reflects the clamping force, so that the EPB system realizes the feedback control of the clamping force and improves the reliability of the EPB system.

In addition, as shown in fig. 6, the current monitoring feedback for driving the clamping motor can be estimated to some extent based on the rough clamping degree. If the piezoelectric sensor and the corner sensor are both failed, the current value of the clamping motor is sampled and monitored, and the positive support effect is achieved on the improvement of the safety and reliability.

The utility model discloses a position corner sensor signal and the tight state of clamp that adopts piezoceramics sensor signal monitoring parking brake disc, piezoceramics sensor's high temperature resistant stability has moreover guaranteed the required clamp force accurate control of car parking braking on different ramps. Because the control intervention height of the clamping force is controllable, when the EPB acts on a redundant backup when a vehicle stability controller ESC or a brake power-assisted system fails, the left and right motors can be independently adjusted to control the clamping force, so that the locking of brake wheels is prevented from losing the stability of the vehicle, and the safety and reliability under the limit condition of the vehicle are improved.

Claims

1. The electronic parking brake is characterized in that a piezoelectric sensor is arranged on the outer wall of the caliper and attached to a position, where the caliper is bent greatly, of the caliper under the action of clamping force.

2. The electronic parking brake of claim 1, characterized in that the electric motor is a dc brushless motor, which is equipped with a rotation angle sensor for detecting a rotor of the electric motor.

3. The electronic parking brake of claim 2 wherein the piezoelectric sensor and the rotation angle sensor signal comprise a correlation check.

4. The electronic parking brake of claim 3 wherein the piezoelectric sensor and the rotational angle sensor transmit signals to an MCU, the MCU determining the motor rotation to a target position according to a control strategy algorithm.

5. The electronic parking brake of claim 4, wherein the MCU further receives an EPB key input signal and an ignition switch signal.