1. An electric brake actuator for service and parking brakes, comprising: comprises that

The caliper main cylinder is provided with a first cambered surface on the front surface;

a planetary gear mechanism;

parking brake assembly comprising

The screw rod penetrates through the caliper main cylinder and is connected with the planetary gear mechanism, and the planetary gear mechanism drives the screw rod to be rotatably arranged in a cavity of the caliper main cylinder;

the nut is sleeved on the screw rod and moves along the axial direction of the screw rod, and the nut and the caliper main cylinder are locked through the guide mechanism;

service brake assembly comprising

The front side of the rotating piece is connected with the planetary gear mechanism, the rear side of the rotating piece is connected with the screw rod through a bearing piece, and a second cambered surface is arranged on the side, opposite to the front surface of the caliper main cylinder, of the rotating piece;

the ball, the ball is connected with calliper master cylinder and rotating member respectively and through the spacing direction of first cambered surface and second cambered surface, and at least one of first cambered surface and second cambered surface is the ramp, and planetary gear mechanism drive rotating member rotates along the circumference of screw shaft, and the rotation of rotating member drives the ball and slides along the ramp, thereby the ball promotes the screw nut and brakes along the direction of braking.

2. An electric brake actuator for service and parking brakes according to claim 1, wherein: the locking device comprises a service braking lock and a parking braking lock, the service braking lock locks the rotating piece when parking braking is implemented, and the parking braking lock locks the screw rod when service braking is implemented.

3. An electric brake actuator for service and parking brakes according to claim 1, wherein: the locking device can be switched between a locking state and a non-locking state, the driving brake lock and the parking brake lock are controlled to be in the locking state or the non-locking state through the electromagnetic driving brake actuator and the electromagnetic parking brake actuator respectively, and when the driving brake lock and the parking brake lock are in the locking state, continuous locking or non-continuous locking can be achieved.

4. An electric brake actuator for service and parking brakes according to claim 1, wherein: the driving brake lock and the parking brake lock are respectively a monostable driving brake lock and a monostable parking brake lock or the driving brake lock and the parking brake lock are the same monostable lock, a first torque conversion mechanism is arranged between the driving brake lock and the rotating piece, and a second torque conversion mechanism is arranged between the parking brake lock and the lead screw.

5. An electric brake actuator for service and parking brakes according to claim 1, wherein: the planetary gear mechanism comprises a gear carrier, a sun gear, a gear ring and a planetary gear, wherein the planetary gear is arranged on the gear carrier, the planetary gear is connected with the sun gear and the gear ring, the sun gear is connected with a power source and rotates under the driving of the power source, the gear carrier is connected with a screw rod, and the gear ring is connected with a rotating piece.

6. An electric brake actuator for service and parking brakes according to claim 1, wherein: a guide mechanism is arranged in the caliper main cylinder and connected with the nut to lock the rotation of the nut.

7. An electric brake actuator for service and parking brakes according to claim 6, wherein: the caliper main cylinder is internally provided with a piston, the piston covers the outer side of the nut, a shell of the caliper main cylinder is provided with an oil inlet, the guide mechanism is arranged in the piston, brake fluid enters the oil inlet, and when the sun wheel cannot rotate, the piston moves axially along the screw rod through the brake fluid to generate braking force.

8. An electric brake actuator for service and parking brakes according to claim 1, wherein: the ball is provided with a plurality of, corresponds respectively on calliper master cylinder, the rotating member and is provided with the first cambered surface of a plurality of, second cambered surface, and the ball moves on the ramp that corresponds respectively, is provided with on the rotating member to follow the synchronous pivoted spacing arch of rotating member, is provided with the dog on the calliper master cylinder front surface, and the relative cooperation of spacing arch and dog is used for restricting the turned angle of rotating member.

9. An electric brake actuator for service and parking brakes according to claim 1, wherein: if one of the first cambered surface and the second cambered surface is a ramp, the other cambered surface is a spherical cambered surface for containing the balls, the rotating angle of the rotating piece is not more than 360 degrees divided by the number of the balls, and if the first cambered surface and the second cambered surface are both ramps, the rotating angle of the rotating piece is not more than 720 degrees divided by the number of the balls.

10. An electric brake actuator for service and parking brakes according to claim 1, wherein: the screw rod and the nut are pre-tightened through a spring, and the spring applies pressure to enable initial locking friction force to be generated between the nut and the screw rod.

Background

With the increasing degree of electrification of road vehicles, it has become common practice today to use Electronic Parking Brakes (EPBs) in vehicles to hold the vehicle stationary while the vehicle is not in motion. At the same time, the demands on service braking systems are changing due to the introduction of new ways of decelerating the vehicle by regenerative braking.

While parking brakes using an electronic control system provide more functionality, existing brake calipers still use hydraulic transmission medium to control the service braking function. Compared with the friction type brake of the new energy automobile, the friction type brake has the advantages that the requirements on the friction type brake are increasingly reduced, particularly the friction type brake on the rear wheel is complex in structure, and the manufacturing cost, the installation cost and the maintenance cost of the product are high.

Chinese invention patent CN104074895 discloses a parking brake actuator using a planetary gear transmission as a final reduction stage, wherein the solution is to realize the reduction and torque conversion transmission of a caliper integrated electronic parking brake through the combination of a belt transmission and a planetary gear, and the solution is suitable for realizing the parking brake function, but cannot meet the requirement of service brake. The friction of the adjusting mechanism is large, so that the adjusting mechanism is self-locked, which is beneficial to a parking brake, but the adjusting mechanism runs counter to the self-releasing requirement of a service brake. Further, the inefficiency caused by friction reduces the braking force, resulting in a braking force that does not respond as quickly as required for service braking operations.

PCT patent application No. WO2010094555 discloses a parking brake actuator that converts rotary motion into linear motion through a ball screw and locks a transmission mechanism through an electromagnetic buckle to avoid it rotating due to clamping force, which overcomes the above problems by using a more efficient ball screw device that can ensure self-release behavior and quick response of a service brake, while a locking mechanism required for a parking brake function is realized through an electromagnetic buckle. The disadvantage of this solution is that the cost of such a ball screw is high and that the screw cannot guarantee a stable zero position due to its self-releasing behavior.

The invention thus describes a solution to the above-mentioned disadvantages, in the proposed construction the disc clearance adjustment and locking features of the self-locking screw are combined with the high efficiency and self-releasing features of the ball ramp, in which arrangement the two transmission elements can be operated separately in a controlled manner according to the actual brake operation to achieve easy switching between service and parking brakes.

Disclosure of Invention

The present invention addresses the shortcomings of the prior art by providing an electric brake actuator for service braking and parking braking.

In order to solve the technical problem, the invention is solved by the following technical scheme:

the electronic brake actuator for service braking and parking braking comprises a caliper main cylinder, a planetary gear mechanism, a parking braking assembly and a service braking assembly, wherein a first cambered surface is arranged on the front surface of the caliper main cylinder; the parking brake assembly comprises a screw rod and a nut, the screw rod penetrates through the caliper main cylinder and is connected with the planetary gear mechanism, and the planetary gear mechanism drives the screw rod to be rotatably arranged in a cavity of the caliper main cylinder; the nut is sleeved on the screw rod and moves along the axial direction of the screw rod, and the nut and the caliper main cylinder are locked through the guide mechanism;

the service brake assembly comprises a rotating piece and a ball, the front side of the rotating piece is connected with the planetary gear mechanism, the rear side of the rotating piece is connected with the screw rod through a bearing piece, and a second cambered surface is arranged on the side, opposite to the front surface of the caliper main cylinder, of the rotating piece; the ball is connected with the caliper main cylinder and the rotating piece respectively and is guided in a limiting mode through the first cambered surface and the second cambered surface, at least one of the first cambered surface and the second cambered surface is a ramp, the planetary gear mechanism drives the rotating piece to rotate along the circumferential direction of the screw rod shaft, the rotating piece drives the ball to slide along the ramp in a rotating mode, and the ball pushes the screw rod to push the nut to brake along the braking direction. Both the lead screw and the rotary member can generate linear movement of the nut in a direction of generating a braking force by rotating in a specific direction. The directions in which the lead screw and the rotary member rotate may be the same or opposite, depending on the specific parameters of the lead screw, the rotary member, the planetary gear mechanism, and other additional components.

Preferably, the locking device comprises a service brake lock and a parking brake lock, the service brake lock locks the rotating member when the parking brake is applied, and the parking brake lock locks the screw rod when the service brake is applied.

Preferably, the locking device can be switched between a locking state and a non-locking state, the service brake lock and the parking brake lock are controlled to be in the locking state or the non-locking state by the electromagnetic service brake actuator and the electromagnetic parking brake actuator respectively, and when the service brake lock and the parking brake lock are in the locking state, continuous locking or non-continuous locking can be achieved.

Preferably, the service brake lock and the parking brake lock are respectively a monostable service brake lock and a monostable parking brake lock or the service brake lock and the parking brake lock are the same monostable lock, a first torque conversion mechanism is arranged between the service brake lock and the rotating piece, and a second torque conversion mechanism is arranged between the parking brake lock and the screw rod. When power failure occurs, the screw rod can be subjected to self-locking, the monostable lock can be kept locked in a default state without being electrified, and the monostable lock can be unlocked in an electrified state, so that the vehicle brake requirement specification is met.

Preferably, the planetary gear mechanism includes a carrier, a sun gear, a ring gear, and a planetary gear, the planetary gear is mounted on the carrier, the planetary gear is connected to the sun gear and the ring gear, the sun gear is connected to the power source and rotates under the driving of the power source, the carrier is connected to the screw, and the ring gear is connected to the rotary member.

Preferably, a guide mechanism is arranged in the caliper main cylinder, and the guide mechanism is connected with the nut and used for locking the rotation of the nut.

Preferably, a piston is arranged in the caliper main cylinder, the piston covers the outer side of the nut, an oil inlet is formed in a shell of the caliper main cylinder, the guide mechanism is arranged in the piston, brake fluid enters the oil inlet, and when the sun gear cannot rotate, the piston moves axially along the screw rod through the brake fluid to generate braking force.

Preferably, the ball is provided with a plurality of, corresponds respectively on calliper master cylinder, the rotating member and is provided with the first cambered surface of a plurality of, second cambered surface, and the ball moves on the ramp that corresponds respectively, is provided with the spacing arch of following the synchronous rotation of rotating member on the rotating member, is provided with the dog on the calliper master cylinder front surface, and the relative cooperation of spacing arch and dog is used for restricting the turned angle of rotating member.

Preferably, if one of the first arc surface and the second arc surface is a ramp, the other arc surface is a spherical arc surface for accommodating the balls, the rotation angle of the rotating member is not more than 360 degrees divided by the number of the balls, and if the first arc surface and the second arc surface are both ramps, the rotation angle of the rotating member is not more than 720 degrees divided by the number of the balls. The spherical arc surface can be guided by arranging a sliding bearing.

Preferably, the screw rod and the nut are pre-tightened by a spring, and the spring applies pressure to generate initial locking friction force between the nut and the screw rod. The screw rod is provided with proper pretightening force, the thread clearance between the screw rod and the nut can be eliminated, and the pretightened screw rod does not have idle running stroke when rotating reversely, so that the positioning precision of the screw rod can be improved, and the full locking effect is realized.

Preferably, sealing rings can be arranged between the piston and the caliper main cylinder, between the caliper main cylinder and the rotating piece, and between the screw rod and the rotating piece.

Due to the adoption of the technical scheme, the invention has the remarkable technical effects that:

the parking brake uses a screw rod driven by a planetary gear mechanism to adjust the disc clearance and play a braking role, the screw rod can realize self-locking, a nut can be locked by a guide mechanism to prevent rotation, locking is realized by the matching of the screw rod and the nut during parking brake, and the screw rod is locked to avoid the action during driving brake;

the service brake is carried out by the balls and the ramp which are matched with each other, the balls are partially contacted with the caliper shell, the other side of the caliper shell converts the rotation of the rotating piece into the movement of the rotating piece in the brake direction through the ramp, and then the screw rod is pushed through the bearing, so that the nut pushes the friction plate to act; thereby, the brake has both service brake and parking brake through a simple structure.

Drawings

Fig. 1 is a schematic structural view of the present invention.

Figure 2 is a transverse cross-sectional view of the rotating member with ramps on both sides of the balls.

FIG. 3 is a longitudinal cross-sectional view of the rotary member, ball, caliper master cylinder contact with ramps on both sides of the ball.

FIG. 4 is a transverse cross-sectional view of the front face of the caliper master cylinder with ramps on both sides of the ball.

FIG. 5 is a transverse cross-sectional view of the rotary member with only the front face of the caliper master cylinder being ramped.

FIG. 6 is a longitudinal cross-sectional view of the rotary member, the ball, and the caliper master cylinder contact when only the front face of the caliper master cylinder is ramped.

FIG. 7 is a transverse cross-sectional view of the caliper master cylinder with only the front face of the caliper master cylinder being ramped.

Figure 8 is a transverse cross-sectional view of the rotating member with only the rotating member being ramped.

FIG. 9 is a longitudinal cross-sectional view of the rotary member, ball, caliper master cylinder contact with only the rotary member being ramped.

FIG. 10 is a transverse cross-sectional view of the caliper master cylinder with only the rotary member disposed on the ramp.

Fig. 11 is a schematic diagram of the structure of the present invention with a spring for pre-tightening.

Fig. 12 is a schematic structural diagram of the monostable running brake lock of the invention.

FIG. 13 is a schematic structural diagram of the present invention incorporating a monostable service brake lock and a first torque converter.

Fig. 14 is a schematic structural diagram of the present invention for providing a monostable parking brake lock.

FIG. 15 is a schematic structural diagram of the present invention incorporating a monostable service brake lock and a second torque converter mechanism.

Fig. 16 is a schematic diagram of the arrangement of the monostable lock of the invention.

FIG. 17 is a schematic structural view of the piston and the oil inlet of the present invention.

Fig. 18 is a schematic view of the present invention with a motor controlling the rotation of the sun gear.

FIG. 19 is a schematic view of the present invention showing the structure of the transmission member.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples.

The electronic brake actuator for service braking and parking braking comprises a caliper main cylinder 3, a planetary gear mechanism, a parking braking assembly and a service braking assembly, wherein a first cambered surface is arranged on the front surface of the caliper main cylinder 3; the parking brake assembly comprises a screw rod 1 and a nut 2, the screw rod 1 penetrates through the caliper main cylinder 3 and is connected with a planetary gear mechanism 5, and the planetary gear mechanism 5 drives the screw rod 1 to be rotatably arranged in a cavity of the caliper main cylinder 3; the nut 2 is sleeved on the screw rod 1 and moves along the axial direction of the screw rod 1, and the nut 2 and the caliper main cylinder 3 are locked through a guide mechanism; the lead screw 1 and the nut 2 are disposed in a caliper master cylinder 3 in a brake caliper, and a braking force is generated by rotation of the lead screw 1 while the nut 2 is locked so as not to rotate. The nut 2 is used to push the friction plate to the brake disc to generate a braking friction force.

The service brake assembly comprises a rotating piece 6 and a ball, the front side of the rotating piece 6 is connected with the planetary gear mechanism 5, the rear side of the rotating piece 6 is connected with the screw rod 1 through a bearing piece, and a second cambered surface is arranged on the side, opposite to the front surface of the caliper main cylinder 3, of the rotating piece 6; the ball is connected with the caliper main cylinder 3 and the rotating part respectively and is limited and guided through the first cambered surface and the second cambered surface, at least one of the first cambered surface and the second cambered surface is a ramp, the planetary gear mechanism 5 drives the rotating part to rotate along the circumferential direction of the screw shaft, the rotation of the rotating part drives the ball to slide along the ramp, and the ball pushes the screw 1 to push the nut 2 to brake along the braking direction.

The ball is provided with a plurality of, corresponds respectively on calliper master cylinder 3, the rotating member and is provided with the first cambered surface of a plurality of, second cambered surface, and the ball moves on the ramp that corresponds respectively, is provided with on the rotating member to follow the synchronous pivoted spacing arch of rotating member, is provided with the dog on the 3 front surfaces of calliper master cylinder, and the relative cooperation of spacing arch and dog is used for restricting the turned angle of rotating member. The ball ramp is generally provided with at least three balls, each ball is arranged on the corresponding ramp, so that the ramps are also at least three, the ramps can be arranged on the inner side or the outer side of the ball, the other side of the ramp is provided with a spherical surface, the ball is accommodated in the spherical surface, the ball cannot produce circumferential relative movement with the spherical surface, the ramps can also be arranged on the inner side and the outer side of the ball, and the relative movement of the ball and the ramps can double the rotation stroke of the rotating element compared with the stroke when the ramps are arranged on one side. If one of the first cambered surface and the second cambered surface is a ramp, the other cambered surface is a spherical cambered surface for containing the balls, the rotating angle of the rotating piece is not more than 360 degrees divided by the number of the balls, and if the first cambered surface and the second cambered surface are both ramps, the rotating angle of the rotating piece is not more than 720 degrees divided by the number of the balls.

As shown in fig. 1, the screw 1 is arranged on a carrier 51 of the planetary gear mechanism 5, and the planetary gear mechanism 5 has a ring gear 53 and a sun gear 52, which are connected to at least 3 planetary gears 54 supported by the carrier 51. The sun gear 52 is driven by a power source to rotate the lead screw 1 via the planetary gear mechanism 5, while the ring gear 53 is locked so as not to rotate. The rotary member 6 is disposed between the screw shaft 1 and the front surface 31 of the caliper master cylinder 3, a bearing member 7 is disposed between the screw shaft 1 and the rotary member 6, the bearing member 7 is disposed between the screw shaft 1 and the back surface 67 of the rotary member 6 so that they can relatively rotate without interfering with each other, and at least 3 ramps 61a, 62a, 63a are formed on the back surface of the rotary member 6 to accommodate at least 3 balls 64, 65, 66 which are further guided by the front surface 31 of the caliper master cylinder 3. In the following figures, three balls 64, 65, 66 are provided and correspond to the ramps one by one, so that more balls can be provided, the rotation angle of the rotating member 6 can be smaller, and the number of balls can be changed as required when the precision is improved. The rotary element 6 is connected to the ring gear 53 of the planetary gear mechanism 5, and the rotary element 6 is rotated by rotating the sun gear 52, while the planetary gear mechanism 5 is locked so as not to rotate.

As shown in fig. 2 to 4, ramps 61a, 62a, 63a are provided on the rotary member 6, and ramps 34a, 35a, 36a are provided on the front surface 31 of the caliper master cylinder 3. When the balls 64, 65, 66 roll along the ramps 61a, 62a, 63a, 34a, 35a, 36a, they travel twice the maximum length of a single ramp profile, generating a linear movement of the rotary member 6. When the balls pass through the fore-aft length of a single ramp, the rotating member 6 rotates 360 divided by the number of balls, which means that the maximum rotation angle of the rotating member 6 can be 720 divided by the number of balls. In order to avoid the rotation of the rotary member 6 beyond the range, a limit protrusion 68 is disposed on the rotary member 6, a stopper 32, 33a is disposed on the front surface 31 of the caliper master cylinder 3, and the limit protrusion 68 contacts the stopper 32, 33a when rotating, so that the rotary member 6 is locked by the cooperation of the limit protrusion and the stopper to prevent the rotation of the rotary member 6 beyond the range, and the rotation angle is controlled, for example, 3 balls are disposed in the figure, the rotation angle of the rotary member 6 is within 240 ° each time, and the left and right states in fig. 2 are states that the limit protrusion 68 contacts the stoppers 32, 33a at both ends respectively during the rotation.

As shown in fig. 5-7, the ramps 34a, 35a, 36a are arranged only on the front face 31 of the caliper master cylinder 3, and the slide bearings 61b, 62b, 63b arranged in the rotary member 6 guide the balls 64, 65, 66, which can roll in the slide bearings but cannot produce radial relative sliding. The balls 64, 65, 66 roll along the ramps 34a, 35a, 36a, respectively, over a length which is the maximum length of a single profile, i.e. 360 divided by the number of balls, while generating a linear movement of the rotary member 6. This means that the maximum rotation angle of the rotating member 6 may be 360 divided by the number of balls. In order to prevent the rotary member 6 from rotating beyond this range, a stopper protrusion 68 is disposed on the rotary member 6, and stoppers 32, 33b are provided on the front surface 31 of the caliper master cylinder 3, and the stopper protrusion 68 contacts the stoppers 32, 33b, respectively, to lock the rotary member 6 against rotation beyond the range.

As shown in fig. 8-10, the ramps 61a, 62a, 63a are arranged only in the rotary member 6, and the balls 64, 65, 66 are guided by the slide bearings 34b, 35b, 36 b. The balls 64, 65, 66 roll along the ramps 61a, 62a, 63a over a length which is the maximum length of a single profile, i.e. 360 divided by the number of balls, while generating a linear movement of the rotary member 6. This means that the maximum rotation angle of the rotating member 6 may be 360 divided by the number of balls. In order to avoid the rotation of the rotary member 6 beyond this range, limit projections 68 are arranged on the rotary member 6, the limit projections 68 locking the rotary member 6 by contacting corresponding stops 32, 33b arranged on the front surface 31 of the caliper master cylinder 3, respectively, to prevent the rotation beyond the range.

As shown in fig. 11, in order to avoid the rotation of the spindle 1 when the rotary member 6 is ready to rotate, the load of the friction plate can be transferred to the nut 2 by the friction force generated between the nut 2 and the spindle 1 by the spring 8, and the preload is generated on the nut 2 by the spring 8 to perform the pretensioning function.

Fig. 12-16 disclose a locking device comprising a service brake lock and a parking brake lock which lock the rotary member and the screw rod by locking the ring gear and the carrier of the planetary gear mechanism, respectively. The service brake lock locks the rotating piece when parking brake is implemented, and the parking brake lock locks the screw rod when service brake is implemented. The locking device can be switched between a locking state and a non-locking state, the driving brake lock and the parking brake lock are controlled to be in the locking state or the non-locking state through the electromagnetic driving brake actuator and the electromagnetic parking brake actuator respectively, and when the driving brake lock and the parking brake lock are in the locking state, continuous locking or non-continuous locking can be achieved. As shown in fig. 12, in order to better control the rotation of the spindle 1 corresponding to the parking brake and the rotation of the rotary member 6 corresponding to the service brake separately, a monostable service brake lock 92 is arranged to prevent the rotation of the rotary member 6 or the ring gear 53 of the planetary gear mechanism 5, the monostable service brake lock 92 being controlled by an electromagnetic service brake actuator 91.

As shown in fig. 13, in order to reduce the torque load on the monostable service brake lock 92, a further first torque conversion mechanism 93 is arranged between the monostable service brake lock 92 and the rotary part 6 or the ring gear 53 of the planetary gear mechanism 5 to prevent rotation.

As shown in fig. 14, in order to better control the rotation of the spindle 1 corresponding to the parking brake and the rotation of the rotary member 6 corresponding to the service brake separately, a monostable parking brake lock 95 is arranged to prevent the spindle 1 or the gear carrier 51 of the planetary gear mechanism 5 from rotating. The monostable parking brake lock 95 is operated by an electromagnetic parking brake actuator 94.

As shown in fig. 15, in order to reduce the torque load on the monostable parking brake lock 92, an additional second torque conversion mechanism 96 is arranged between the monostable parking brake lock 95 and the screw 1 or the carrier 51 of the planetary gear mechanism 5 to prevent rotation thereof.

As shown in fig. 16, in order to better control the rotation of the spindle 1 corresponding to the parking brake and the rotation of the rotary member 6 corresponding to the service brake separately, a monostable lock 98 is arranged, which in one state prevents the rotation of the spindle 1 or the gear carrier 51 of the planetary gear mechanism 5 and in the other state prevents the rotation of the rotary member 6 or the ring gear 53 of the planetary gear mechanism 5. The monostable lock 98 is operated by an electromagnetic actuator 97. The steady state of the monostable lock 98 is a state in which the lead screw 1 is locked against rotation.

As shown in fig. 17, the guide mechanism 4 of the nut 2 is disposed in 1 piston 41 which is guided by the caliper master cylinder 3 and sealed by the elastic seal 37. The caliper master cylinder has an oil inlet 38 to receive brake fluid from the brake system. A rotatable sealing ring is also arranged between the caliper master cylinder 3 and the rotary member 6, and a screw seal 11 is arranged between the screw 1 and the rotary member 6. Through the oil inlet, the piston can be moved in the braking direction to generate a braking force if the sun gear 52 of the planetary gear mechanism 5 cannot rotate. The piston covers the outer side of the nut 2, the shell of the caliper main cylinder 3 is provided with an oil inlet, the guide mechanism is arranged in the piston, brake fluid enters the oil inlet, and when the sun gear 52 cannot rotate, the piston moves axially along the screw rod 1 through the brake fluid to generate braking force.

As shown in fig. 18, the sun gear 52 of the planetary gear mechanism 5 is driven and rotated by the motor 100.

As shown in fig. 19, a transmission 101, 102 for converting the torque of the electric motor 100 is additionally provided between the sun gear 52 of the planetary gear mechanism 5 and the electric motor 100.

The rotating member 6 is locked or unlocked by a monostable service brake lock 92 controlled by an electromagnetic service brake actuator 91 so as to control whether the rotating member can rotate, the monostable service brake lock 92 can lock the rotating member 6 at a discontinuous position, the monostable service brake lock 92 can lock the rotating member 6 at a continuous position, and further, the monostable service brake lock 92 can lock the rotating member 6 through a first torque conversion mechanism 93.

The screw rod 1 is locked or unlocked through a monostable parking brake lock 95 controlled by an electromagnetic parking brake actuator 94 so as to control whether the screw rod can rotate, the monostable parking brake lock 95 locks the screw rod 1 at a discontinuous position, and the monostable parking brake lock 95 can also lock the screw rod 1 at a continuous position. Further, the monostable parking brake lock 95 can lock the lead screw 1 by the second torque conversion mechanism 96.

The driving brake lock and the parking brake lock are respectively a monostable driving brake lock and a monostable parking brake lock or the driving brake lock and the parking brake lock are the same monostable lock, a first torque conversion mechanism is arranged between the driving brake lock and the rotating piece, and a second torque conversion mechanism is arranged between the parking brake lock and the lead screw.

The planetary gear mechanism 5 includes a carrier 51, a sun gear 52, a ring gear 53, and planet gears 54, the planet gears 54 are mounted on the carrier 51, the planet gears 54 are connected to the sun gear 52 and the ring gear 53, the sun gear 52 is connected to a power source and is driven by the power source to rotate, the carrier 51 is connected to the lead screw 1, and the ring gear 53 is connected to a rotary member.

In summary, the above-mentioned embodiments are only preferred embodiments of the present invention, and all equivalent changes and modifications made in the claims of the present invention should be covered by the claims of the present invention.