CN109424669B

CN109424669B - Disc brake and vehicle

Info

Publication number: CN109424669B
Application number: CN201710758842.7A
Authority: CN
Inventors: 郑祖雄
Original assignee: BYD Co Ltd
Current assignee: BYD Co Ltd
Priority date: 2017-08-29
Filing date: 2017-08-29
Publication date: 2020-08-25
Anticipated expiration: 2037-08-29
Also published as: CN109424669A

Abstract

The present disclosure relates to a disc brake and a vehicle. The disc brake comprises a brake caliper body, a first brake block, a service brake unit and a parking brake unit, wherein the parking brake unit comprises a parking motor, a deflection cone difference planetary reduction mechanism and a crank block mechanism, and the parking motor drives the first brake block to move to compress a brake disc sequentially through the deflection cone difference planetary reduction mechanism and the crank block mechanism. In the brake disclosed by the invention, by adopting the crank slider mechanism, when the parking brake unit executes the auxiliary ABS function, the parking motor only needs to rotate forwards or backwards at a high speed, so that the push rod can output a high-pulse braking force, the state switching of the parking motor is not required to be carried out continuously, and the service life of the motor is prolonged. By adopting the deflection cone difference planetary speed reducing mechanism, a larger transmission ratio can be obtained, and the cycloid pin gear planetary speed reducer has smaller volume, so that the brake has more compact structure and smaller occupied space.

Description

Disc brake and vehicle

Technical Field

The present disclosure relates to the field of brakes, and in particular, to a disc brake and a vehicle.

Background

In a traditional hydraulic or pneumatic braking system, the obvious defects of complex gas-liquid pipelines, difficult maintenance, complex arrangement structure, slow braking dynamic response, lower braking comfort performance and the like exist. For example, in a hydraulic brake system, a rebound vibration phenomenon occurs in a brake pedal when an anti-lock brake system is operated, which affects brake comfort. For another example, because the brake pedal mechanism is directly connected with the brake transmission device and the brake actuating device, the impact force generated when the vehicle collides can be directly transmitted into the cab through the brake system, and the safety performance of the automobile is seriously affected. For another example, the conventional hydraulic brake system employs large-sized components of the conventional hydraulic brake system, such as a vacuum brake booster, a brake master cylinder, and an oil reservoir, which not only have the problems of complicated structure and assembly, large size, and difficulty in maintenance, but also have the problems of the need to periodically replace hydraulic oil and periodically check whether there is hydraulic oil leakage due to the arrangement of a hydraulic brake pipeline and brake fluid for connecting corresponding components in the system. In view of the above problems, in recent years, various electromechanical brake systems having a simple structure, a fast braking dynamic response, and excellent braking comfort and safety performance as compared to hydraulic or pneumatic brake systems have been developed.

Disclosure of Invention

The purpose of this disclosure is to provide a disc brake that can simultaneously achieve both service braking and parking braking functions.

In order to achieve the purpose, the present disclosure provides a disc brake, including a caliper body, a first brake pad, a service brake unit and a parking brake unit, where the parking brake unit includes a parking motor, a deflection cone difference planetary reduction mechanism and a crank-slider mechanism, and the parking motor drives the first brake pad to move sequentially through the deflection cone difference planetary reduction mechanism and the crank-slider mechanism so as to compress a brake disc.

Optionally, the disc brake is a floating caliper disc brake, the disc brake further comprising a second brake pad, the first and second brake pads being located on both sides of the brake disc, respectively, the second brake pad being mounted on the caliper body.

Optionally, the service brake unit includes a service motor, a service reduction mechanism and a screw rod mechanism, the service motor is an external rotor motor, a stator of the service motor has a cavity extending along an axial direction, the screw rod mechanism includes a screw rod and a nut sleeved on the screw rod, the screw rod penetrates through the cavity, and a rotor of the service motor drives the screw rod to rotate through the service reduction mechanism, so that the nut moves along the screw rod axial direction, thereby pushing the first brake block to move so as to compress the brake disc.

Optionally, the screw mechanism is a ball screw mechanism.

Optionally, the slider-crank mechanism includes a crank, a connecting rod and a push rod, two ends of the connecting rod are respectively hinged to the crank and the push rod, the parking motor drives the crank to rotate so as to enable the push rod to move axially, so as to push the first brake block to press the brake disc, the lead screw is formed as a hollow rod, and the push rod is arranged in the lead screw in a penetrating manner.

Optionally, the disc brake further comprises a piston, the piston is in sliding fit with one end of the cavity, and the nut and the push rod push the first brake block to move through the piston.

Optionally, a sealing ring is arranged between the piston and the inner wall of the cavity.

Optionally, the parking brake unit further comprises an electromagnetic clutch mounted on a motor shaft of the parking motor, the electromagnetic clutch being engaged to lock the motor shaft when the electromagnetic clutch is de-energized; when the electromagnetic clutch is energized, the electromagnetic clutch is disengaged to release the motor shaft.

Optionally, the electromagnetic clutch includes electro-magnet, translation friction disc and rotatory friction disc, the electro-magnet includes the fixed core, moves the iron core and acts on move the actuating spring of iron core, rotatory friction disc with the motor shaft is connected, the translation friction disc can by move the iron core drive.

Optionally, the electromagnetic clutch further comprises a clutch housing, an outer race, and an inner race splined to the motor shaft, the rotating friction plate being disposed on the inner race, the outer race being splined to an inner wall of the clutch housing, the translating friction plate being disposed on the outer race.

Optionally, the electromagnetic clutch is located between the parking motor and the deflection cone difference planetary reduction mechanism.

In the brake disclosed by the invention, the service brake unit and the parking brake unit are arranged, so that the brake can simultaneously realize two functions of service brake and parking brake, the function integration level is high, and the occupied space is small. Moreover, by adopting the crank slider mechanism, when the parking brake unit executes an auxiliary ABS (antilock brake system) function, the parking motor only needs to rotate forwards or backwards at high speed, so that the push rod can output a high-pulse braking force, and the parking motor does not need to be switched between forward rotation and reverse rotation or power failure continuously, thereby prolonging the service life of the parking motor. In addition, by adopting the deflection cone difference planetary speed reducing mechanism, a larger transmission ratio can be obtained, and the brake is ensured to have larger braking force.

The present disclosure also provides a vehicle comprising a disc brake as described above.

Additional features and advantages of the disclosure will be set forth in the detailed description which follows.

Drawings

The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and together with the description serve to explain the disclosure without limiting the disclosure. In the drawings:

fig. 1 is a sectional view of a disc brake according to an embodiment of the present disclosure;

FIG. 2 is an enlarged view of a portion of FIG. 1;

FIG. 3 is a cross-sectional view taken along line AA in FIG. 1 of a disc brake according to one embodiment of the present disclosure with the housing omitted;

fig. 4 is a sectional view taken along line AA of fig. 1 of a disc brake according to another embodiment of the present disclosure, in which a housing is omitted;

FIG. 5 is a schematic structural diagram of a deflection cone difference planetary reducer;

fig. 6 is a schematic structural view of the electromagnetic clutch.

Detailed Description

The following detailed description of specific embodiments of the present disclosure is provided in connection with the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present disclosure, are given by way of illustration and explanation only, not limitation.

In the present disclosure, unless otherwise specified, the use of directional terms such as "left" and "right" generally refers to the left and right in the drawing plane direction of the corresponding drawings, and these directional terms are used for convenience of description only and should not be construed as limiting the present disclosure.

According to an aspect of the present disclosure, as shown in fig. 1 to 4, there is provided a disc brake including a caliper body 10, a first pad 31, a service brake unit, and a parking brake unit, the first pad 31 and the second pad 32 being located at both sides of a disc 20, respectively. The service braking unit comprises a service motor 40, a service retarding mechanism 50 and a screw rod mechanism 60, wherein the service motor 40 drives the first brake block 31 to move through the service retarding mechanism 50 and the screw rod mechanism 60 in sequence so as to press the brake disc 20. The parking brake unit includes a parking motor 110, a parking deceleration mechanism 120, and a crank slider mechanism 130, and the parking motor 110 drives the first pad 31 to move to press the brake disc 20 through the parking deceleration mechanism 120 and the crank slider mechanism 130 in sequence.

The disc brake of the present disclosure may be a fixed caliper disc brake or a floating caliper disc brake.

In case the disc brake of the present disclosure is a floating caliper disc brake, the brake further comprises a second brake pad 32, which second brake pad 32 is mounted on the caliper body 10, the caliper body 10 being axially movable with respect to the brake disc 20. Specifically, taking the service brake as an example, as shown in fig. 1 and 2, when the service brake is performed, the service motor 40 drives the screw 61 to rotate, so that the nut 62 sleeved on the screw 61 moves rightwards, thereby pushing the first brake pad 31 to move rightwards and press against the brake disc 20, and then the brake disc 20 gives a leftward reaction force to the nut 62, so that the nut 62 and the caliper body 10 move leftwards integrally until the second brake pad 32 is pressed against the brake disc 20. At this time, the brake pads on both sides are pressed on the brake disc 20, thereby clamping the brake disc 20 and generating a friction torque for preventing the wheel from rotating, so as to realize service braking.

Alternatively, the screw mechanism 60 may be a ball screw mechanism. In the case of the ball screw mechanism, rolling bodies such as balls or rollers are provided between the nut 62 and the screw 61. Further, the screw mechanism 60 may be a planetary roller screw mechanism. Compared with other screw rod mechanisms, the planetary roller screw rod mechanism has the advantages of large bearing load, strong shock resistance, high transmission precision and long service life.

Additionally, and alternatively, the screw mechanism 60 may be a ball screw mechanism. The advantageous effects of using the ball screw mechanism are similar to those of using the planetary roller screw described above, and a description thereof will be omitted here in order to avoid redundancy. However, the present disclosure is not limited thereto, and a slide screw mechanism or the like may be used as the screw mechanism 60. When a sliding screw rod mechanism is adopted, the lead screw lead angle can be larger than the self-locking angle, so that the screw pair can not be self-locked, and the return of the nut can be realized by the acting force of the brake disc on the brake block when the brake is released.

In one embodiment, as shown in fig. 2, the traveling motor 40 may be an external rotor motor, the stator 41 of the traveling motor 40 has a cavity 411 extending in the axial direction, the screw mechanism 60 includes a screw 61 and a nut 62 sleeved on the screw 61, the screw 61 penetrates the cavity 411, and the rotor 42 of the traveling motor 40 drives the screw 61 to rotate through the traveling reduction mechanism 50. In this embodiment, the screw rod mechanism 60 is integrated inside the traveling motor 40, so that the brake is more compact in structure, occupies less space, and is convenient to install and arrange on the whole vehicle.

The traveling reduction mechanism 50 may be any suitable type of reduction mechanism as long as it can reduce the speed and increase the torque of the output torque of the traveling motor 40 and transmit the torque to the lead screw 61. In one embodiment, as shown in fig. 2, the reduction gear mechanism 50 may be a first planetary gear reduction mechanism including a first sun gear 51, a first planet gear 52, a first carrier 53 and a first ring gear 54, wherein the first sun gear 51 is connected with the rotor 42 of the traveling motor 40, the first carrier 53 is connected with the screw 61, and the first ring gear 54 is fixed in the caliper body 10.

Alternatively, the screw 61 may have a thrust bearing 70 mounted thereon. In one embodiment, the lead screw 61 is formed with a stepped surface and the thrust bearing 70 is disposed between the stepped surface and the first carrier 52. When the brake block clamps the brake disc 20, the first planet carrier 52 applies an axial force to the screw rod 61 through the thrust bearing 70 to balance the reaction force of the brake disc 20 to the screw rod 61, so as to ensure that the screw rod 61 is stressed in a balanced manner.

In one embodiment, the disc brake further includes a piston 90, the piston 90 is slidably fitted in one end of the cavity 411, the reduction gear mechanism 50 is disposed at the other end of the cavity 411 and connected to the lead screw 61, and the nut 62 pushes the first brake pad 31 to move through the piston 90. In this embodiment, the piston 90 separates the interior of the cavity 411 from the outside, so that the screw mechanism 60 is in a relatively closed environment, thereby preventing the screw mechanism from being corroded by outside water and impurities, and prolonging the service life of the brake.

To avoid creating resistance to the movement of the piston 90, the piston 90 may be clearance fit with the cavity 411, that is, the diameter of the cavity 411 may be slightly larger than the diameter of the piston 90. In this case, in order to ensure sealability, a seal ring 100 may be provided between the piston 90 and the inner wall of the cavity 411.

Here, the nut 62 may be fastened to the piston 90 by screwing, welding, gluing, etc. However, to avoid stress concentrations at the joints, in one embodiment, the nut 62 is not coupled to the piston 90, and when service braking is performed, the nut 62 pushes the piston 90 to move, and the piston 90 pushes the first brake pad 31 against the brake disc 20. The piston 90 may have a cylindrical structure with one end closed and the other end open, the nut 62 may be disposed in the piston 90 and in clearance fit with an inner wall of the piston 90, and when the driving brake is performed, a thrust force of the nut 62 acts on the closed end of the piston 90 to push the piston 90 to move toward the brake disc 20.

The crank-slider mechanism 130 comprises a crank 131, a connecting rod 132 and a push rod 133, wherein one end of the connecting rod 132 is hinged to the crank 131, the other end of the connecting rod 132 is hinged to one end of the push rod 133, and the other end of the push rod 133 is used for pushing the first brake block 31 to press the brake disc 20. The crank slider mechanism 130 converts the rotational motion of the parking motor 110 into the linear motion output of the push rod 133.

In the disclosure, by adopting the slider-crank mechanism, when the parking brake unit executes the auxiliary ABS function, the parking motor only needs to rotate forward or backward at a high speed, and the push rod can output a high-pulse braking force without the parking motor continuously switching forward and backward or switching power on and off, thereby prolonging the service life of the parking motor.

In one embodiment, the screw 61 may be a hollow rod, that is, an axial hole extending in the axial direction is formed in the screw 61, the screw 61 penetrates through the center of the reduction gear mechanism 50, the push rod 133 penetrates through the axial hole of the screw 61, and the push rod 133 pushes the first brake block 31 through the piston 90. By integrating the push rod 133 inside the screw rod 61, the movement of the push rod 133 can be guided by the screw rod 61, and the compactness of the brake can be further improved.

The parking deceleration mechanism 120 may be any appropriate type of deceleration mechanism as long as the output torque of the parking motor 110 is decelerated and increased and then transmitted to the parking screw 131. In one embodiment, as shown in fig. 4, the parking deceleration mechanism 120 may be a yaw cone differential planetary deceleration mechanism.

Fig. 5 is a schematic structural diagram of a deflection cone difference planetary reducer, which mainly comprises a rotating bevel gear 1, a deflection bevel gear 2, a deflection generator H on an input shaft 5, a circumferential limiting pair and the like. The yaw generator H is composed of a spindle head 6 with a yaw angle Σ at the end of the input shaft 5 and a tapered roller bearing 7. The bevel gear 2 is equivalent to an inner bevel gear and forms inner gearing with the bevel gear 1 arranged on the output shaft 9, one end of the deflection bevel gear 2 is arranged on a tapered roller bearing 7 at a deflection angle shaft head 6, and the other end forms spherical hinge connection with the shaft end of the output shaft 9 by a spherical bearing 8. The cone tops of the two bevel gears coincide with the center O point of the spherical bearing, and the outer edge of the deflection bevel gear 2 is provided with a drum-shaped outer gear ring 3 which forms a circumferential limiting pair with an inner gear ring 4.

The transmission principle of the deflection cone difference planetary reducer is as follows: when the input shaft 5 drives the deflection shaft head 6 to rotate around the fixed axis nn of the input shaft, the axis OO of the deflection shaft head_HA cone beam space with a 2 sigma cone angle is formed. Because the deflection bevel gear 2 arranged on the deflection shaft head 6 is restrained by the circumferential limiting pair and can not do revolving motion, the cone beam motion of the deflection shaft head forces the deflection bevel gear 2 to do circular deflection motion around the O point, and the circular deflection bevel gear 2 and the rotating bevel gear 1 arranged on the output shaft 9 form a circular opening and closing meshing state. In the position shown in the figure, the upper parts of the two bevel gears are in a full meshing state, and the lower parts of the two bevel gears are in a full disengagement state. However, when the deflection angle is rotated by 180 ° to the position a', the lower portions of the two bevel gears are in a fully engaged state, and the upper portions are in a fully disengaged state. When the deflection shaft head rotates 180 degrees again and returns to the original position, just one deflection meshing cycle is completed. In the process that the deflection angle shaft head rotates around a fixed axis nn, the deflection bevel gearThe gear teeth circularly enter and exit from the meshing along the circumferential direction, so that the meshing area is transferred along the pitch cone surface of the output bevel gear.

In case of the yaw cone planetary reducer, the motor shaft 111 of the parking motor 110 may be connected to the input shaft 5 of the yaw cone planetary reducer, and the output shaft 9 of the yaw cone planetary reducer may be connected to the cam 131.

In another embodiment, as shown in fig. 3, the parking deceleration mechanism 120 may be a second planetary gear deceleration mechanism including a second sun gear 121, a second planet gear 122, a second planet carrier 123 and a second ring gear 124, wherein the second sun gear 121 is connected with the motor shaft 111 of the parking motor 110, the second planet carrier 123 is connected with the parking screw 131, and the second ring gear 124 is fixed in the caliper body 10.

In order to ensure that the push rod 132 is still maintained at the position for implementing the parking brake after the parking motor 110 is de-energized, in one embodiment, as shown in fig. 3, 4 and 6, the parking brake unit may further include an electromagnetic clutch 80, the electromagnetic clutch 80 is mounted on the motor shaft 111 of the parking motor 110, and the parking brake state is maintained by locking the motor shaft 111 by the electromagnetic clutch 80.

Specifically, when the electromagnetic clutch 80 is de-energized, the electromagnetic clutch 80 is engaged to lock the motor shaft 111 of the parking motor 110, so that the cam 131 cannot rotate, and the push rod 132 is held at a position where parking braking is achieved and cannot move, and further the push rod 132 keeps thrust to the first brake pad 31, and the parking braking state is maintained. When the electromagnetic clutch 80 is energized, the electromagnetic clutch 80 is disengaged to release the motor shaft 111.

Alternatively, the electromagnetic clutch 80 may include a clutch housing 81, an electromagnet, a translating friction plate 85, a rotating friction plate 86, an outer race 87, and an inner race 88. The clutch housing 81 is fixed to the caliper body 10, and the electromagnet may include a fixed iron core 82, a movable iron core 83, and a drive spring 84 acting on the movable iron core 83. The inner race 88 is slidably connected to the motor shaft 111 through a spline, and the rotary friction plate 86 is provided on the inner race 88 so as to be rotatable by the motor shaft 41. The outer race 87 is slidably connected to the inner wall of the clutch housing 81 by a spline, and the translation friction plate 85 is provided on the outer race 87 so as to be able to translate in the axial direction of the motor shaft 111. The fixed iron core 82 and the movable iron core 83 can be formed into an annular structure, the movable iron core 83 is sleeved outside the motor shaft 111, and the fixed iron core 82 is sleeved outside the movable iron core 83, so that the brake is more compact in structure and smaller in axial size. When the electromagnet is de-energized, the magnetic attraction between the fixed iron core 82 and the movable iron core 83 disappears, the movable iron core 83 moves rightwards under the action of the driving spring 84 and pushes the translation friction plate 85 and the rotation friction plate 86 to be jointed, and the friction force between the translation friction plate and the rotation friction plate causes the motor shaft 111 to be locked; when the electromagnet is energized, magnetic attraction is generated between the fixed iron core 82 and the movable iron core 83, so that the movable iron core 83 is reset and simultaneously compresses the driving spring 84, the translational friction plate 85 and the rotary friction plate 86 are separated, and the friction force between the translational friction plate 85 and the rotary friction plate 86 disappears, so that the locking of the motor shaft 111 is released.

When the parking brake function needs to be executed in a driving process, the parking motor 110 is powered on and drives the push rod 132 to move sequentially through the parking deceleration mechanism 120 and the cam 131, the push rod 132 pushes the brake pad to clamp the brake disc 20, and when the parking requirement is met (for example, the parking brake force reaches the target brake force, and the time taken for the parking brake force to increase from zero to the target brake force is less than the preset time), the parking motor 110 is powered off, the electromagnetic clutch 80 works to lock the motor shaft 111 of the parking motor 110, the parking brake force is maintained, and the parking brake function is executed. When the parking brake is released, the electromagnetic clutch 80 loses the holding force and releases the motor shaft 111.

In order to make the brake structure more compact, the electromagnetic clutch 80 may be integrated inside the parking motor 110.

In one embodiment, the parking motor 110, the electromagnetic clutch 80, the parking deceleration mechanism 120, and the crank link mechanism 130 may be disposed in the same housing 140, and the housing 140 may be fixed with the caliper body 10 by a fastener, for example. The clutch housing 81 may be fixed within the housing 140.

The operation of the disc brake according to an embodiment of the present disclosure will be described in detail below with reference to the accompanying drawings.

During service braking, the parking motor 110 does not work, the rotor 42 of the service motor 40 drives the screw rod 61 to rotate through the service retarding mechanism 50, so that the nut 62 sleeved on the service screw rod 61 moves rightwards, the brake block is pushed to clamp the brake disc 20, friction torque for preventing the wheel from rotating is generated, and service braking is realized.

During parking braking, the driving motor 40 does not work, the parking motor 110 drives the push rod 133 to move sequentially through the parking speed reducing mechanism 120, the slider-crank mechanism 130 and the force increasing mechanism, the push rod 133 pushes the brake block to clamp the brake disc 20, when the parking requirement is met, the parking motor 110 is de-energized, the electromagnetic clutch 80 is de-energized to lock the motor shaft 111 of the parking motor 110, parking braking force is kept, and parking braking is achieved. When the parking brake needs to be released, the electromagnetic clutch 80 is energized to release the motor shaft 111 of the parking motor 110, and the parking brake force disappears.

According to another aspect of the present disclosure, a vehicle is provided, which comprises a disc brake as described above.

The preferred embodiments of the present disclosure are described in detail with reference to the accompanying drawings, however, the present disclosure is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present disclosure within the technical idea of the present disclosure, and these simple modifications all belong to the protection scope of the present disclosure.

It should be noted that the various features described in the above embodiments may be combined in any suitable manner without departing from the scope of the invention. In order to avoid unnecessary repetition, various possible combinations will not be separately described in this disclosure.

In addition, any combination of various embodiments of the present disclosure may be made, and the same should be considered as the disclosure of the present disclosure, as long as it does not depart from the spirit of the present disclosure.

Claims

1. A disc brake is characterized by comprising a brake caliper body (10), a first brake block (31), a service brake unit and a parking brake unit, wherein the parking brake unit comprises a parking motor (110), a deflection cone difference planetary reduction mechanism and a crank block mechanism (130), the parking motor (110) drives the first brake block (31) to move to press a brake disc (20) sequentially through the deflection cone difference planetary reduction mechanism and the crank block mechanism (130), the service brake unit comprises a service motor (40), a service reduction mechanism (50) and a screw rod mechanism (60), the service motor (40) is an outer rotor motor, a stator (41) of the service motor (40) is provided with a cavity (411) extending along the axial direction, the screw rod mechanism (60) comprises a screw rod (61) and a nut (62) sleeved on the screw rod (61), the screw rod (61) penetrates through the cavity (411), the rotor (42) of the travelling crane motor (40) drives the screw rod (61) to rotate through the travelling crane speed reducing mechanism (50) so as to enable the nut (62) to move axially along the screw rod (61), thereby pushing the first brake block (31) to move to press the brake disc (20), the crank slider mechanism (130) comprises a crank (131), a connecting rod (132) and a push rod (133), the two ends of the connecting rod (132) are respectively hinged with the crank (131) and the push rod (133), the parking motor (110) drives the crank (131) to rotate so as to enable the push rod (133) to move along the axial direction, thereby pushing the first brake block (31) to press the brake disc (20), the screw rod (61) is formed into a hollow rod, and the push rod (133) penetrates through the screw rod (61).

2. The disc brake of claim 1, characterized in that it is a floating caliper disc brake, further comprising a second brake pad (32), the first (31) and second (32) brake pads being located on either side of the brake disc (20), respectively, the second brake pad (32) being fixed to the caliper body (10).

3. The disc brake of claim 1, characterized in that the screw mechanism (60) is a ball screw mechanism.

4. The disc brake of claim 1, further comprising a piston (90), the piston (90) being slidably fitted at one end of the cavity (411), the nut (62) and the push rod (133) each pushing the first brake pad (31) to move by means of the piston (90).

5. The disc brake of claim 4, characterized in that a sealing ring (100) is arranged between the piston (90) and the inner wall of the cavity (411).

6. The disc brake of claim 1, characterized in that the parking brake unit further comprises an electromagnetic clutch (80), the electromagnetic clutch (80) being engaged to lock a motor shaft (111) of the parking motor (110) when the electromagnetic clutch (80) is de-energized; when the electromagnetic clutch (80) is energized, the electromagnetic clutch (80) is disengaged to release the motor shaft (111).

7. The disc brake of claim 6, characterized in that the electromagnetic clutch (80) comprises an electromagnet comprising a stationary core (82), a movable core (83) and a drive spring (84) acting on the movable core (83), a translatory friction disc (85) and a rotary friction disc (86), the rotary friction disc (86) being connected to the motor shaft (111), the translatory friction disc (85) being drivable by the movable core (83).

8. The disc brake of claim 7, characterized in that the electromagnetic clutch (80) further comprises a clutch housing (81), an outer race (87), and an inner race (88), the inner race (88) being splined to the motor shaft (111), the rotating friction plate (86) being disposed on the inner race (88), the outer race (87) being splined to an inner wall of the clutch housing (81), the translating friction plate (85) being disposed on the outer race (87).

9. The disc brake of claim 6, characterized in that the electromagnetic clutch (80) is located between the parking motor (110) and the yawing cone difference planetary reduction mechanism.

10. A vehicle, characterized in that it comprises a disc brake according to any one of claims 1-9.