CN106402205A - Automobile electronic mechanical brake system wheel rim self-powered type brake executing mechanism - Google Patents

Abstract

The invention relates to the technical field of vehicle braking, in particular to a wheel-side self-powered braking actuator of an automotive electromechanical braking system, which includes a braking actuator part and a regenerative motor part. The brake execution part includes stepper motor, planetary gear mechanism, screw nut mechanism and brake caliper body, etc. The regenerative motor part includes electromagnetic clutch and regenerative motor. The electromagnetic clutch and regenerative motor are arranged axially along the brake disc. When the car is braking, the electromagnetic clutch is preferentially controlled to engage, and the brake disc drives the regenerative motor to rotate, converting the braking energy of the car into electrical energy and providing braking torque. When the braking torque provided by the regenerative motor is not enough, the stepper motor is controlled to rotate, and the friction block is pushed to the brake disc through the planetary gear mechanism and the screw nut mechanism to implement friction braking. The invention has the advantages of compact structure, convenient layout, good dynamic characteristics and easy integrated control, etc., and can directly use the recovered braking energy to drive the braking actuator to act.

Description

Wheel-side self-powered brake actuators for automotive electromechanical brake systems

technical field

The invention relates to the technical field of vehicle braking, in particular to a wheel-edge self-powered braking actuator of an automotive electromechanical braking system.

Background technique

The braking system is one of the important components of the automobile chassis, which is directly related to the comprehensive performance of the automobile and the safety of life and property. Although the traditional hydraulic and pneumatic braking systems can meet the requirements of the existing braking regulations, there are complex pipeline arrangements, relying on vacuum booster devices, slow braking response speed, non-active adjustment of braking torque, and difficulty in matching Inadequacies such as other system integration control are not suitable for the development requirements of automobile, especially electric vehicle chassis integration control.

The electronically controlled braking system realizes the decoupling of the braking system, mainly including the electronic hydraulic braking system (EHB) and the electromechanical braking system (EMB), which cancels the direct connection between the brake pedal and the brake wheel cylinder. Connection, using wires as the information transmission medium, the electronic control unit recognizes the braking intention according to the relevant sensor signals, controls the action of the brake actuator, and realizes the control of the wheel braking force. It overcomes the shortcomings of the traditional braking system structure and principle.

However, the EHB system is generally arranged in a centralized manner, and the hydraulic pipelines of the whole vehicle still need to be arranged, so that the dynamic response performance can be further improved. The EMB system generally adopts a distributed layout, without the need to arrange the brake pipeline of the whole vehicle, and has the advantages of good dynamic performance and easy layout. However, most of the current EMB systems are single-motor actuators, which cannot make full use of the braking energy of the vehicle to drive the friction brake, and cannot share the braking load of the vehicle to reduce the wear of the friction brake pair. So far, the wheel-side self-powered brake actuators of automotive electromechanical brake systems have rarely been mentioned.

Contents of the invention

The purpose of the present invention is to propose a wheel-side self-powered brake actuator of the automotive electromechanical braking system, which adopts the wheel-side self-powered arrangement, does not need to arrange the brake pipeline of the whole vehicle, has good dynamic response performance, compact structure, and convenient layout , easy to integrate control with other systems, can convert braking energy into electric energy to directly drive the action of the brake actuator, and can share the braking load to reduce the friction wear of the dual-motor brake actuator.

In order to achieve the purpose of the present invention, the adopted technical solution is: the wheel side self-powered brake actuator of the automotive electromechanical braking system, the wheel side self-powered brake actuator of the automotive electromechanical brake system is arranged on each The wheel brake disc is characterized in that it includes a regenerative motor part and a brake execution part, the regenerative motor part includes an electromagnetic clutch and a regenerative motor, the electromagnetic clutch and the regenerative motor are arranged axially along the wheel brake disc, and the brake execution part includes The electronic control unit, stepping motor, planetary gear mechanism, screw nut mechanism, brake caliper body and friction block, the electronic control unit controls the combination of the electromagnetic clutch, the wheel brake disc drives the regenerative motor to rotate, and converts the braking energy of the car into The electric energy provides braking torque for the brake execution part. The electronic control unit controls the rotation of the stepping motor, and the stepping motor drives the sun gear of the planetary gear mechanism to rotate. The planet carrier of the planetary gear mechanism is connected with the screw nut mechanism, and the screw nut mechanism It includes a left nut and a right nut, the brake caliper body is connected with the right nut, and the friction block includes a left friction block and a right friction block, and the left friction block and the right friction block are respectively arranged on the wheel brake disc. On both sides, the right friction block is arranged on the inner side of the brake caliper body, and the screw nut mechanism respectively pushes the left friction block and the right friction block to press against the wheel brake disc for friction braking.

As an optimized solution of the present invention, the wheel-side self-powered brake actuator of the automotive electromechanical braking system also includes a lithium battery, which is used to provide electric energy for the wheel-side self-powered brake actuator of the automotive electromechanical brake system. A diode is arranged between the lithium battery and the vehicle power connection line, and the lithium battery stores the energy recovered when the regenerative motor brakes.

As an optimized solution of the present invention, the planetary gear mechanism includes a left planetary gear mechanism and a right planetary gear mechanism, the screw nut mechanism includes a left screw screw and a right screw screw, and the stepper motor is connected to the sun of the left planetary gear mechanism respectively. The gear wheel is connected with the sun gear of the right planetary gear mechanism, the planet carrier of the left planetary gear mechanism is connected with the left screw rod, the planet carrier of the right planetary gear mechanism is connected with the right screw rod, and the left nut and the left screw The screw mandrels are connected, and the right nut is connected with the right screw mandrel.

As an optimized solution of the present invention, the brake executive part further includes a friction block gasket, the left nut is connected with the friction block gasket, and the left friction block is installed on the friction block gasket.

As an optimized solution of the present invention, the brake execution part also includes a left displacement sensor and a right displacement sensor, the left displacement sensor and the right displacement sensor are potentiometer type displacement sensors, and the slide plate of the left displacement sensor is connected on the left side On the nut, the sliding piece of the right displacement sensor is connected on the right nut, and the left displacement sensor and the right displacement sensor transmit the measured moving positions of the left nut and the right nut to the electronic control unit.

As an optimized solution of the present invention, the brake execution part also includes a left displacement sensor and a right displacement sensor, the left displacement sensor and the right displacement sensor are potentiometer type displacement sensors, and the slide plate of the left displacement sensor is connected on the left side On the nut, the sliding piece of the right displacement sensor is connected on the right nut, and the left displacement sensor and the right displacement sensor transmit the measured moving positions of the left nut and the right nut to the electronic control unit.

As an optimized solution of the present invention, the brake execution part also includes a left limit switch and a right limit switch, the left limit switch is set between the left nut and the friction block gasket, and the right limit switch is set at Between the right side nut and the inside of the caliper body.

As an optimization scheme of the present invention, both the left limit switch and the right limit switch are normally open contact switches, and the front end of the left screw rod is in contact with the left limit switch, so that the contact of the left limit switch Closed, the left limit switch transmits the contact closure information to the electronic control unit, the front end of the right screw rod contacts the right limit switch, so that the contact of the right limit switch is closed, and the right limit switch will The contact closure information is transmitted to the electronic control unit, and the electronic control unit receives the information that the left limit switch closes the contact or the right limit switch closes the contact, and the electronic control unit controls the stepper motor to power off.

As an optimized solution of the present invention, the wheel-side self-powered brake actuator of the automotive electro-mechanical braking system also includes a cooling fan and a temperature sensor, the cooling fan is arranged on one side of the lithium battery, and the wheel-side self-powered of the automotive electro-mechanical braking system There is also a heat dissipation channel inside the brake actuator, and a metal heat dissipation fine mesh is set in the heat dissipation channel. The temperature sensor transmits the measured temperature to the electronic control unit. When the electronic control unit judges that the temperature reaches a certain value, it controls the cooling fan to rotate. .

As an optimized solution of the present invention, the brake caliper body is a floating caliper type brake caliper body.

The present invention has positive effects: 1) The present invention is a decoupling distributed brake actuator, which does not need to arrange brake pipelines of the whole vehicle, is easy to be integrated and controlled with other systems, has compact structure, convenient layout and rapid dynamic response;

2) The present invention can convert braking energy into electric energy, and can be directly used to drive the action of the braking actuator, improving the utilization efficiency of braking energy and reducing energy consumption;

3) When the regenerative motor of the present invention is working, it can generate braking torque to share the braking load, reduce the wear of the friction pair of the brake disc, and improve the service life and thermal decay resistance of the friction pair;

4) The present invention has better anti-failure capability, and each brake actuator is relatively independent, if one of them breaks down, the other several can still make the automobile reliably decelerate and stop; the present invention is easy to realize the emergency braking function, and can Self-braking energy drives the brake actuator to act to realize emergency braking of the vehicle;

5) The present invention has the function of detecting the wear condition of the friction block;

6) The present invention has a self-cooling function, which can prevent the brake performance from being affected by excessive temperature of the brake actuator.

Description of drawings

The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

Fig. 1 is the overall structural representation of the present invention;

Fig. 2 is a schematic diagram of the housing structure of the braking actuator of the present invention;

Figure 3 is a diagram of an embodiment of the present invention.

Among them: 1. Wheel brake disc, 21. Electromagnetic clutch, 22. Regenerative motor, 31. Electronic control unit, 32. Stepper motor, 35. Brake caliper body, 341. Left nut, 342. Right nut, 361, left friction block, 362, right friction block, 4, lithium battery, 331, left planetary gear mechanism, 332, right planetary gear mechanism, 343, left screw mandrel, 344, right screw mandrel, 37 , friction block gasket, 38, left displacement sensor, 39, right displacement sensor, 310, left limit switch, 311, right limit switch, 5, cooling fan, 6, temperature sensor.

detailed description

In describing the present invention, it is to be understood that the terms "radial", "axial", "upper", "lower", "top", "bottom", "inner", "outer" etc. indicate orientation Or the positional relationship is based on the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation , and therefore cannot be construed as a limitation of the present invention. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

In the description of the present invention, it should be noted that unless otherwise specified and limited, the terms "installation", "setting", and "connection" should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection. Connected, or integrally connected; either directly or indirectly through an intermediary. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present invention according to specific situations.

As shown in the figure, the present invention discloses a wheel-side self-powered brake actuator of an automotive electromechanical braking system. , including a regenerative motor part and a brake execution part, the regenerative motor part includes an electromagnetic clutch 21 and a regenerative motor 22, the electromagnetic clutch 21 and the regenerative motor 22 are arranged axially along the wheel brake disc 1, and the brake execution part includes an electronic control unit 31. Stepper motor 32, planetary gear mechanism, screw nut mechanism, brake caliper body 35 and friction block, electronic control unit 31 controls the combination of electromagnetic clutch 21, wheel brake disc 1 drives regenerative motor 22 to rotate, and brakes the car. Kinetic energy is converted into electric energy and provides braking torque for the braking executive part. The electronic control unit 31 controls the rotation of the stepping motor 32, and the stepping motor 32 drives the rotation of the sun gear of the planetary gear mechanism. The planet carrier of the planetary gear mechanism and the screw nut Mechanisms are connected, the screw nut mechanism includes a left nut 341 and a right nut 342, the brake caliper body 35 is connected with the right nut 342, the friction block includes a left friction block 361 and a right friction block 362, and the left friction block 361 and the right side friction block 362 are arranged on both sides of the wheel brake disc 1 respectively, the right side friction block 362 is arranged on the inner side of the brake caliper body 35, and the screw nut mechanism pushes the left side friction block 361 and the right side friction block respectively 362 Press against wheel brake disc 1 for friction braking. Among them, each wheel brake disc 1 is provided with an independent wheel-side self-powered brake actuator of the automotive electro-mechanical braking system, and the wheel-side self-powered brake actuators of each automotive electro-mechanical braking system are interconnected. Without interference, the regenerative motor part and the brake execution part are connected by wires, the brake execution part is arranged in the casing, and the casing of the brake execution part is fixedly connected to the axle. The brake caliper body 35 is flexibly connected with the housing of the brake executing part, the stepping motor 32 is installed in the housing of the braking executing part, and the stepping motor 32 is connected in the housing of the braking executing part through a chute, that is, step The feeder motor 32 can move linearly within the housing of the brake actuator.

The wheel-side self-powered brake actuator of the automotive electromechanical braking system also includes a lithium battery 4, which is used to provide electric energy for the wheel-side self-powered brake actuator of the automotive electromechanical braking system, and the lithium battery 4 is connected to the vehicle Diodes are arranged between the power connection lines, and the lithium battery 4 stores the energy recovered when the regenerative motor 22 brakes.

Planetary gear mechanism comprises left side planetary gear mechanism 331 and right side planetary gear mechanism 332, and screw nut mechanism comprises left side screw mandrel 343 and right side screw mandrel 344, and stepper motor 32 is connected with the sun gear of left side planetary gear mechanism 331 respectively. It is connected with the sun gear of the right planetary gear mechanism 332, the planet carrier of the left planetary gear mechanism 331 is connected with the left screw rod 343, the planet carrier of the right planetary gear mechanism 332 is connected with the right screw rod 344, and the left side The nut 341 is connected with the left screw rod 343 , and the right nut 342 is connected with the right screw rod 344 . Wherein, the sun gear of the left side planetary gear mechanism 331 and the sun gear of the right side planetary gear mechanism 332 are respectively fixedly connected with the output shafts on both sides of the stepper motor 32, and the planet carrier of the left side planetary gear mechanism 331 is connected with the left side screw rod 343 Connected, the planet carrier of the right side planetary gear mechanism 332 is connected with the right side screw mandrel 344, when the stepper motor 32 rotates, the screw nut mechanism is driven by the planetary gear mechanism to rotate, which plays the role of deceleration and torque increase. This can reduce the size of the stepping motor 32 .

The brake execution part also includes a friction block washer 37 , the left nut 341 is connected with the friction block washer 37 , and the left friction block 361 is installed on the friction block washer 37 . The screw nut mechanism can convert the rotary motion of the screw into the linear motion of the nut. The left side nut 341 is rigidly connected with the friction block gasket 37, and the friction block gasket 37 is rigidly connected with the left side friction block 361, that is, the left side nut 341 moves, driving the friction block gasket 37 and the left side friction block 361 to move together. The right nut 342 is rigidly connected to the brake caliper body 35, and the right friction block 362 is rigidly connected to the brake caliper body 35, that is, the movement of the right nut 342 drives the brake caliper body 35 and the right friction block 362 to move together. Therefore, when the stepper motor 32 rotates and works, the left side friction block 361 and the right side friction block 362 are driven to be pressed against the wheel brake through the planetary gear mechanism, the screw nut mechanism, the friction block gasket 37 and the brake caliper body 35. disc 1 to increase or decrease the braking torque. If the time when the left side friction block 361 and the right side friction block 362 contact the wheel brake disc 1 is inconsistent, then when the friction block on one side first contacts the wheel brake disc 1, the stepper motor 32 can be in the braking execution part shell. The body slides linearly, so the displacement of the left nut 341 or the right nut 342 generated by the rotation of the stepping motor 32 will be applied to the friction block on the other side at the same time, so that the friction block on the other side will quickly contact the wheel brake disc 1, and the left The side friction block 361 and the right side friction block 362 apply braking torque simultaneously. In this way, the forces on both sides of the wheel brake disc 1 are balanced, which is beneficial to the control of the braking torque and the service life of the brake friction pair.

The brake execution part also includes a left side displacement sensor 38 and a right side displacement sensor 39, the left side displacement sensor 38 and the right side displacement sensor 39 are potentiometer type displacement sensors, and the sliding plate of the left side displacement sensor 38 is connected to the left side nut 341 Above, the sliding piece of the right side displacement sensor 39 is connected on the right side nut 342, and the left side displacement sensor 38 and the right side displacement sensor 39 transmit the measured moving positions of the left side nut 341 and the right side nut 342 to the electronic control unit 31. When the side nut 341 or the right side nut 342 moves, the slide plates of the left side displacement sensor 38 and the right side displacement sensor 39 move accordingly, thereby changing their output voltage value, and the electronic control unit 31 thus identifies the left side nut 341 and the right side nut 341. The movement position of nut 342. They can provide feedback signals for the action control of the brake actuator and information on the wear of the friction pads. If the electronic control unit 31 detects that the wear of the friction block reaches the allowable upper limit, a warning is issued to remind the driver to pay attention.

The brake execution part also includes a left limit switch 310 and a right limit switch 311. The left limit switch 310 is arranged between the left nut 341 and the friction block gasket 37, and the right limit switch 311 is arranged on the right side. between the side nut 342 and the inner side of the caliper body 35 . The left limit switch 310 and the right limit switch 311 are normally open contact switches, and the front end of the left screw rod 343 is in contact with the left limit switch 310, so that the contact of the left limit switch 310 is closed. The left limit switch 310 transmits the contact closure information to the electronic control unit 31, and the front end of the right screw rod 344 is in contact with the right limit switch 311, so that the contact of the right limit switch 311 is closed, and the right limit switch 311 is closed. The position switch 311 transmits the contact closure information to the electronic control unit 31, and the electronic control unit 31 receives the information that the left limit switch 310 closes the contact or the information that the right limit switch 311 closes the contact, and the electronic control unit 31 controls the stepper motor 32 to power off. When the left limit switch 310 and the right limit switch 311 are pressed, the contact switch is closed, and the left limit switch 310 and the right limit switch 311 are facing the center position of the left screw rod 343 and the right screw rod 344 . When the left screw mandrel 343 and the right screw mandrel 344 return to the limit position, the front ends of the left screw mandrel 343 and the right screw mandrel 344 will contact the left limit switch 310 and the right limit switch 311, so that The contacts of the left limit switch 310 and the right limit switch 311 are closed, and information is transmitted to the electronic control unit 31 at the same time. The electronic control unit 31 receives the contact closure information of the limit switch, and then immediately controls the stepper motor 32 to power off or reversely rotate a certain angle to prevent the screw nut mechanism from damaging the stepper motor 32 and the planetary gear mechanism.

The wheel-side self-powered braking actuator of the automotive electromechanical braking system also includes a cooling fan 5 and a temperature sensor 6. The cooling fan 5 is arranged on one side of the lithium battery 4. There is also a heat dissipation channel inside the actuator, and a metal heat dissipation fine mesh is arranged in the heat dissipation channel. The temperature sensor 6 transmits the measured temperature to the electronic control unit 31. When the electronic control unit 31 judges that the temperature reaches a certain value, it controls the rotation of the cooling fan 5 Work. The brake caliper body 35 is a floating caliper type brake caliper body.

The wheel brake disc 1 is fixedly connected with the active part of the electromagnetic clutch 21, and the active part of the electromagnetic clutch 21 is connected with the semi-axis of the wheel brake disc 1 through a needle bearing, that is, the wheel brake disc 1 rotates, and the active part of the electromagnetic clutch 21 Partially turned. The casing of the electromagnetic clutch 21 is fixedly connected with the casing of the regenerative motor 22 . The driven part of the electromagnetic clutch 21 is fixedly connected with the rotor of the regenerative motor 22, and the rotor of the regenerative motor 22 is connected with the half shaft of the wheel brake disc 1 through a needle bearing. When the electromagnetic coil in the electromagnetic clutch 21 is energized, the electromagnetic clutch 21 is engaged by the magnetic field, and the wheel brake disc 1 can drive the rotor of the regenerative motor 22 to rotate through the electromagnetic clutch 21 . When the electromagnetic coil is powered off, the electromagnetic clutch 21 is disengaged, the power between the wheel brake disc 1 and the rotor of the regenerative motor 22 is interrupted, and the regenerative motor 22 does not work.

The regenerative motor 22 is an electric and generator integrated machine. When the rotor of the regenerative motor 22 is rotated by the wheel brake disc 1, it enters the generator mode. While providing part of the braking torque to reduce the burden on the friction pair, the braking energy of the vehicle is converted into electrical energy and sent to the stepper The motor 32, the cooling fan 5 and the lithium battery 4 etc. play the role of efficiently recovering braking energy. When the car is in the working conditions of rapid acceleration, climbing, etc., the electronic control unit 31 can control the power supply to the regenerative motor 22. At this time, it enters the motor mode, and the regenerative motor 22 provides auxiliary driving rotation for the wheels through the electromagnetic clutch 21 and the wheel brake disc 1. moment. The regenerative motor 22 has its own fan for heat dissipation of the electromagnetic clutch 21 and the regenerative motor 22 .

Lithium battery 4 provides electric energy for the wheel self-powered brake actuator of the electronic mechanical braking system of the automobile, and stores the energy recovered when the regenerative motor 22 brakes, its voltage value is slightly higher than the power supply voltage of the automobile, and is connected to the automobile power supply A second tube is added between the lines. Usually, the lithium battery voltage is higher than the vehicle power supply voltage, the diode is cut off, and the power supply system of the wheel-side self-powered brake actuator of the automotive electromechanical braking system is relatively independent; when the voltage of the lithium battery 4 is lower than the vehicle power supply voltage, the secondary The tube is turned on, the automobile power supply system supplies power to the lithium battery 4, and the wheel-side self-powered brake actuator of the automobile electromechanical braking system maintains normal performance. In this way, if a sudden failure occurs in the automobile power supply system, the wheel-side self-powered brake actuator of the automobile electromechanical braking system can still work normally, thereby improving the working reliability.

The wheel-side self-powered brake actuator of the entire automotive electromechanical brake system adopts a layered control structure, and is provided with a general control unit of the brake system and each electronic control unit 31 . The main control unit of the braking system is responsible for identifying the driver's braking intention, judging the braking state, allocating the target braking force of each wheel, and interacting with other systems of the vehicle. Each electronic control unit 31 is used to collect information such as the displacement of the left nut 341 and the right nut 342, the housing temperature of the brake actuator, and the limit switch, and control the action of the brake actuator according to the instructions of the brake system master control unit. , realize the recovery of braking energy, deceleration and braking of wheels, and feed back relevant information to the master control unit of the braking system.

When the vehicle brakes, the electronic control unit 31 preferentially controls the engagement of the electromagnetic clutch 21 according to the braking conditions, and the wheel brake disc 1 drives the regenerative motor 22 to rotate through the electromagnetic clutch 21, transforming the braking energy of the vehicle into electric energy and providing part of braking energy. The dynamic torque is used to recover the braking energy, divert the braking load, and reduce the wear of the friction pair. When the braking torque provided by the regenerative motor 22 is not enough, the electronic control unit 31 controls the rotation of the stepping motor, and pushes the friction block to the wheel brake disc through the planetary gear mechanism and the screw nut mechanism to implement friction braking.

As shown in Fig. 3, the regeneration part of the motor is the same as the first embodiment. The brake execution part includes a brake caliper body 35, a friction block, a friction block gasket 37, a left limit switch 310, a left screw mandrel 343, a stepper motor 32, a left planetary gear mechanism 331, a left nut 341, Left side displacement sensor 38 etc. Compared with the first embodiment, the brake execution part of the second embodiment omits the right planetary gear mechanism 332, the right screw rod 344, the right limit switch 311, the right nut 342, the right displacement sensor 39, etc., and the whole The size of the wheel-side self-powered brake actuator of the automotive electromechanical brake system is reduced. The basic function of each key component and the basic working principle of the wheel-side self-powered brake actuator of the entire automotive electromechanical brake system are similar to the first implementation, except that the simultaneous drive on both sides is changed to one-side drive.

It should be understood that the specific embodiments described above are only used to explain the present invention, not to limit the present invention. Obvious changes or variations derived from the spirit of the present invention are still within the protection scope of the present invention.

Claims (9)

1. The wheel-side self-powered brake actuator of the automotive electro-mechanical braking system. The wheel-side self-powered brake actuator of the automotive electro-mechanical brake system is arranged at each wheel brake disc (1). It is characterized in that it includes a regenerative motor part and a braking execution part, the regenerative motor part includes an electromagnetic clutch (21) and a regenerative motor (22), and the electromagnetic clutch (21) and regenerative motor (22) are both along the wheel system. The moving disc (1) is axially arranged, and the brake execution part includes an electronic control unit (31), a stepping motor (32), a planetary gear mechanism, a screw nut mechanism, a brake caliper body (35) and friction blocks , the electronic control unit (31) controls the combination of the electromagnetic clutch (21), the wheel brake disc (1) drives the regenerative motor (22) to rotate, converts the braking energy of the vehicle into electric energy and provides braking torque for the braking executive part, The electronic control unit (31) controls the stepping motor (32) to rotate, and the stepping motor (32) drives the sun gear of the planetary gear mechanism to rotate, and the planet carrier of the planetary gear mechanism is connected with the screw nut mechanism, and the described wire The rod nut mechanism includes a left side nut (341) and a right side nut (342), the brake caliper body (35) is connected with the right side nut (342), and the friction block includes a left side friction block (361 ) and the right side friction block (362), the left side friction block (361) and the right side friction block (362) are respectively arranged on both sides of the wheel brake disc (1), and the right side friction block ( 362) is arranged on the inner side of the brake caliper body (35), and the screw nut mechanism respectively pushes the left friction block (361) and the right friction block (362) to press against the wheel brake disc (1) for friction braking. move. 2. The wheel-side self-powered braking actuator of the automotive electromechanical braking system according to claim 1, characterized in that: the automotive electromechanical braking system wheel-side self-powered braking actuator also includes a lithium battery (4), the lithium battery (4) is used to provide electric energy for the wheel-side self-powered brake actuator of the automotive electromechanical braking system, and the lithium battery (4) and the vehicle power connection line are provided with Diode, the lithium battery (4) stores the energy recovered when the regenerative motor (22) brakes. 3. The wheel-side self-powered brake actuator of the automotive electromechanical braking system according to claim 2, characterized in that: the planetary gear mechanism includes a left planetary gear mechanism (331) and a right planetary gear mechanism (332), described screw mandrel nut mechanism comprises left side screw mandrel (343) and right side screw mandrel (344), and stepping motor (32) is respectively connected with the sun gear of left side planetary gear mechanism (331) and the right side The sun gear of the planetary gear mechanism (332) is connected, the planet carrier of the left planetary gear mechanism (331) is connected with the left screw mandrel (343), and the planet carrier of the right planetary gear mechanism (332) is connected with the right screw mandrel ( 344) are connected, the left side nut (341) is connected with the left side screw mandrel (343), and the right side nut (342) is connected with the right side screw mandrel (344). 4. The wheel-side self-powered brake actuator of the automotive electromechanical brake system according to claim 3, characterized in that: the brake actuator part also includes a friction block gasket (37), and the left The side nut (341) is connected with the friction block gasket (37), and the left side friction block (361) is installed on the friction block gasket (37). 5. The wheel-side self-powered brake actuator of the automotive electromechanical brake system according to claim 4, characterized in that: the brake actuator part also includes a left displacement sensor (38) and a right displacement sensor (39), the left side displacement sensor (38) and the right side displacement sensor (39) are potentiometer type displacement sensors, and the sliding plate of the left side displacement sensor (38) is connected on the left side nut (341), and the right side displacement sensor The slide plate of (39) is connected on the right side nut (342), and described left side displacement sensor (38) and right side displacement sensor (39) will measure left side nut (341) and right side nut (342) ) is transmitted to the electronic control unit (31). 6. The wheel-side self-powered brake actuator of the automotive electromechanical brake system according to claim 5, characterized in that: the brake actuator part also includes a left limit switch (310) and a right limit switch. position switch (311), the left limit switch (310) is set between the left nut (341) and the friction block gasket (37), and the right limit switch (311) is set on the right Between the side nut (342) and the inner side of the brake caliper body (35). 7. The wheel-side self-powered brake actuator of the automotive electromechanical braking system according to claim 6, characterized in that: the left limit switch (310) and the right limit switch (311) are both It is a normally open contact switch, the front end of the left screw rod (343) is in contact with the left limit switch (310), so that the contact of the left limit switch (310) is closed, and the left limit switch (310) The contact closure information is transmitted to the electronic control unit (31), and the front end of the right screw rod (344) is in contact with the right limit switch (311), so that the contact of the right limit switch (311) is closed, and the right The side limit switch (311) transmits the contact closure information to the electronic control unit (31), and the electronic control unit (31) receives the information that the left limit switch (310) closes the contact or the right limit switch ( 311) The electronic control unit (31) controls the stepper motor (32) to cut off the power according to the contact closure information. 8. The wheel-side self-powered brake actuator of the automotive electro-mechanical braking system according to claim 7, characterized in that: the wheel-side self-powered brake actuator of the automotive electro-mechanical brake system also includes cooling A fan (5) and a temperature sensor (6), the cooling fan (5) is arranged on one side of the lithium battery (4), and the wheel-side self-powered brake actuator of the automotive electromechanical braking system also has a A heat dissipation channel is provided, and a metal heat dissipation fine mesh is arranged in the heat dissipation channel. The temperature sensor (6) transmits the measured temperature to the electronic control unit (31), and the electronic control unit (31) judges that when the temperature reaches a certain value, Control the cooling fan (5) to rotate and work. 9. The wheel-side self-powered brake actuator of the automotive electromechanical braking system according to claim 7, characterized in that: the brake caliper body (35) is a floating caliper type brake caliper body.