Actuator for brake device and brake device including the same

Abstract

An actuator for a braking device is disclosed. The actuator according to an embodiment of the present invention includes: a motor; a housing for accommodating a power connection unit and a reduction gear unit; and a cover covering an open upper portion of the housing and including a shaft support unit, wherein the reduction gear unit includes: a worm wheel including a receiving groove concavely formed on an upper surface thereof and a locking rib provided on the receiving groove; a sun gear including a support rib supported by a bottom of the receiving groove so as to be relatively rotatable and thus capable of contacting the locking rib when rotating; and a clutch spring slidably provided on an outer peripheral surface of the shaft support unit in a wound state, and when the worm wheel and the sun gear rotate relative to each other, the clutch spring can selectively tighten or loosen the outer peripheral surface of the shaft support unit according to the rotation direction.

Description

Technical Field

[0001] The present disclosure relates to an actuator and a brake device having the same, and more particularly, to an actuator capable of achieving a parking function through operation of a motor and a brake device having the same. Background Art

[0002] Generally, a braking device is a device for stopping the movement of a vehicle during braking or parking, and is used to prevent the wheels of the vehicle from rotating.

[0003] Recently, an electronic parking brake (EPB) system for electronically controlling the actuation of a parking brake has been widely used, and the EPB is installed on a conventional disc brake to perform the function of a parking brake. Electronic parking brakes include cable-type, motor-on-caliper (MOC)-type, and hydraulic parking brake types.

[0004] For example, Korean Patent Publication No. 10-2011-0072877 (June 29, 2011) discloses a structure of an MOC-type EPB actuator in which a motor for generating power is connected to the EPB actuator. Furthermore, the EPB actuator discloses an actuator for an electronic disc brake that uses multiple gears to decelerate the power generated by the motor while increasing the torque and transmit the power to a caliper, thereby performing a braking operation. Summary of the Invention

[0005] Technical issues

[0006] One aspect of the present disclosure is to provide an actuator for a brake device, which is capable of preventing reverse torque during braking with a simple structure, and a brake device having the same.

[0007] Technical Solution

[0008] According to one aspect of the present disclosure, an actuator for a braking device includes: a housing that accommodates a motor, a power transmission unit connected to the motor, and a reduction gear unit connected to the power transmission unit; and a cover that covers the open top of the housing and has a shaft support portion; wherein the reduction gear unit includes: a worm gear that rotates by receiving power from the power transmission unit, the worm gear including a concave receiving groove on the upper surface of the worm gear and a locking rib arranged in the receiving groove; a sun gear that is rotatably supported on the bottom of the receiving groove and has a support rib that can contact the locking rib during rotation; and a clutch spring that is arranged in a state of being slidably wound around the outer peripheral surface of the shaft support portion and is configured to selectively tighten or loosen the outer peripheral surface of the shaft support portion by contacting at least one of the support rib and the locking rib according to the direction of rotation when the worm gear and the sun gear rotate relative to each other.

[0009] The clutch spring may include: a body, which surrounds the outer peripheral surface of the shaft support portion multiple times; a first end, which protrudes from a lower end of the body to be positioned between the support rib and the locking rib and is capable of contacting the support rib and the locking rib during rotation; and a second end, which protrudes from an upper end of the body and is capable of contacting the locking rib during rotation.

[0010] When the worm wheel rotates counterclockwise, the first end may be configured to rotate counterclockwise while in contact with the support rib and the locking rib so that the body can slide relative to an outer surface of the shaft support portion.

[0011] When the worm wheel rotates clockwise, the second end may be configured to rotate clockwise while in contact with the locking rib, so that the body can slide relative to the outer surface of the shaft supporting portion.

[0012] When the sun gear rotates clockwise, the first end may be configured to rotate clockwise by the support rib so that the body tensions the outer surface of the shaft support portion.

[0013] A plurality of the support ribs and the locking ribs may be alternately positioned in the receiving groove along a circumferential direction to contact each other during rotation.

[0014] The locking rib may include a first portion and a second portion, wherein the first portion extends from a side wall of the receiving groove toward a center of the receiving groove and contacts at least one of the support rib and the first end during rotation, and the second portion extends from the first portion in a longitudinal direction and contacts the second end during rotation.

[0015] The reduction gear unit may include: a plurality of planetary gears meshing with the sun gear; a ring gear serving as an internal gear to accommodate the plurality of planetary gears; and a planet carrier rotatably supporting the plurality of planetary gears and having a rotating shaft supported by the shaft supporting portion to rotate coaxially with the sun gear.

[0016] The worm gear may include a circular body formed with the receiving groove, and an annular body coupled to an outer circumference of the circular body and having a gear portion.

[0017] The circular body may comprise a steel material, and the annular body comprises a plastic material.

[0018] The circular body and the annular body may be manufactured by insert injection.

[0019] The power transmission unit may include a worm member including a shaft portion having helical gear teeth and a driven worm wheel provided at one end of the shaft portion to mesh with a driving worm coupled to a rotation shaft of the motor.

[0020] According to another aspect of the present disclosure, a brake device includes: a piston slidably disposed in a cylinder of a caliper housing to press a pad; an actuator including a housing and a cover, the housing accommodating a motor, a power transmission unit connected to the motor, and a reduction gear unit connected to the power transmission unit, the cover covering the open top of the housing and having a shaft supporting portion; and an output conversion device, the output conversion device receiving rotational motion from the actuator and converting the rotational motion into linear motion to apply thrust to move the piston; wherein the reduction gear unit includes: a worm gear, the worm gear being The power transmission unit receives power and rotates, the worm gear includes a concave receiving groove on the upper surface of the worm gear and a locking rib arranged in the receiving groove; a sun gear, which is rotatably supported on the bottom of the receiving groove and has a support rib that can contact the locking rib during rotation; and a clutch spring, which is arranged in a state of being slidably wound on the outer peripheral surface of the shaft support part, and is configured to selectively tighten or loosen the outer peripheral surface of the shaft support part by contacting at least one of the support rib and the locking rib according to the rotation direction when the worm gear and the sun gear rotate relative to each other.

[0021] The clutch spring may include: a body, which surrounds the outer peripheral surface of the shaft support portion multiple times; a first end, which protrudes from a lower end of the body to be positioned between the support rib and the locking rib and is capable of contacting the support rib and the locking rib during rotation; and a second end, which protrudes from an upper end of the body and is capable of contacting the locking rib during rotation.

[0022] When the sun gear rotates by the reaction force of the output conversion device after braking, the body may tension the outer peripheral surface of the shaft support portion as the support rib presses and rotates the first end.

[0023] Beneficial effects

[0024] The embodiments of the present disclosure may reduce costs by simplifying the configuration of a locking structure for preventing reverse rotation torque generated during braking, thereby improving productivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a schematic diagram illustrating a braking device according to an embodiment of the present disclosure.

[0026] Figure 2 is a perspective view illustrating a ball-entry ramp mechanism according to an embodiment of the present disclosure.

[0027] Figure 3 is a cross-sectional perspective view showing an actuator according to an embodiment of the present disclosure.

[0028] Figure 4 is an exploded perspective view showing an actuator according to an embodiment of the present disclosure.

[0029] Figure 5 is an exploded perspective view showing a reduction gear unit according to an embodiment of the present disclosure.

[0030] Figure 6 is a cross-sectional view of a reduction gear unit according to an embodiment of the present disclosure.

[0031] Figure 7 is a perspective view illustrating a worm gear according to an embodiment of the present disclosure.

[0032] Figure 8 2 is a view illustrating an operating state of a reduction gear unit during braking according to an embodiment of the present disclosure.

[0033] Figure 9 is a view illustrating an operating state of a reduction gear unit according to an embodiment of the present disclosure according to transmission of reverse rotation torque after braking.

[0034] Figure 10is a view illustrating an operating state of the reduction gear unit according to an embodiment of the present disclosure when the brake is released. DETAILED DESCRIPTION

[0035] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. It should be understood that the terms used in the specification and the appended claims should not be interpreted as limited to the general meaning and dictionary meaning, but should be interpreted based on the meaning and concept corresponding to the technical aspects of the present disclosure based on the principle of allowing the inventor to appropriately define the terms for the best interpretation. Therefore, the descriptions provided herein are merely preferred examples for illustrative purposes and are not intended to limit the scope of the present disclosure. Therefore, it should be understood that other equivalents and modifications may be made thereto without departing from the spirit and scope of the present disclosure.

[0036] See also Figure 1 and Figure 2 A brake device 1 according to an embodiment of the present disclosure may include a disc 2 that rotates together with a wheel, a planetary carrier on which a pair of shims 5 and 6 are respectively attached so as to be spaced apart from each other, a caliper housing 10 that is slidably mounted on the planetary carrier and operates the pair of shims 5 and 6, a piston 12 that is mounted to move back and forth in a cylinder 11 of the caliper housing 10, and an output conversion device 20 that receives a rotational force from an actuator 40 including a motor 41 and a reduction gear unit 100 and converts the rotational force into linear motion to apply a thrust to move the piston 12.

[0037] The caliper housing 10 includes a cylinder 11 in which a piston 12 is embedded, and fingers 13 for operating the pair of backing plates 5 and 6 .

[0038] The shim plates 5 and 6 have friction pads 3 and 4 attached to their inner sides, with one shim plate 5 being arranged to contact the piston 12 and the other shim plate 6 being arranged to contact the finger 13 .

[0039] The output conversion device 20 receives power from the actuator 40 , converts the rotational motion into translational motion, and presses the piston 12 toward the backing plate 5 .

[0040] As one example, the output conversion device 20 may be configured as a ball-in-ramp (BIR) mechanism 30 and a pushing member 21 for pressing the piston 12 by operation of the BIR mechanism 30 .

[0041] The BIR mechanism 30 includes a fixed ramp 31 fixedly installed in the cylinder 11 , a rotating ramp 32 positioned in front of the fixed ramp 31 so as to rotate by receiving power from the actuator 40 , and a ball 33 interposed between the fixed ramp 31 and the rotating ramp 32 .

[0042] The rotating ramp 32 includes a disk portion 32 a in the form of a disk and a shaft portion 32 b extending from the center of the disk portion 32 a toward the fixed ramp 31 , and has a T-shaped cross section in the axial direction.

[0043] The shaft portion 32 b of the rotating ramp 32 is a portion that rotates by receiving power from the actuator 40 , and a rear end of the shaft portion 32 b passes through the fixed ramp 31 and the cylinder 11 and is connected to the output shaft 42 of the actuator 40 .

[0044] The fixing slope 31 has a cylindrical shape with a front opening, and is fixedly installed in the cylinder 11. In addition, the flange 21a of the thrust member 21 and the thrust bearing 23 are provided in the fixing slope 31.

[0045] The flange 21a of the thrust member 21 is slidably coupled to the fixed slope 31 while its rotation is restricted by inserting a protrusion 21b protruding from the outer periphery of the flange into a fitting groove 31a formed on the inner periphery of the fixed slope 31. A thrust bearing 23 is interposed between the flange 21a of the thrust member 21 and the disk portion 32a of the rotating slope 32.

[0046] The balls 33 are interposed between the fixed slope 31 and the rotating slope 32. The balls 33 are respectively provided on the opposing surfaces of the fixed slope 31 and the rotating slope 32, thereby forming movable guide grooves 31b and 32c.

[0047] The guide grooves 31b and 32c are formed to extend in an arc shape at a predetermined inclination angle along the circumferential direction thereof. Therefore, when the rotation inclined surface 32 rotates, the balls 33 roll between the inclined guide grooves 31b and 32c, and further when the balls 33 roll, the rotation inclined surface 32 rotates and moves forward in the axial direction toward the piston 12.

[0048] The pushing member 21 is elastically supported in a direction in which the rotating slope 32 is pressed toward the fixing slope 31 by the elastic member 22 provided in the cylinder 11 .

[0049] One end of the elastic member 22 is elastically supported by the holder 14 fixed to the inner wall of the cylinder 11 , and the other end includes a coil spring elastically supported by the flange 21 a of the pushing member 21 .

[0050] The elastic member 22 provides an elastic force in the direction in which the flange 21a of the pushing member 21 presses the thrust bearing 23, so that the fixed inclined surface 31 and the rotating inclined surface 32 are in close contact with each other, and when the rotational torque applied to the rotating inclined surface 32 is removed, the pushing member 21 is returned by rotating the rotating inclined surface 32 to its original position.

[0051] On the other hand, in the embodiment of the present disclosure, as an example of the output conversion device 20, the structure of the BIR mechanism formed by the ball 33 placed between the fixed inclined plane 31 and the rotating inclined plane 32 is described, but if it is a structure that converts the rotational motion of the actuator 40 into linear motion, various known structures can be adopted.

[0052] Figure 3 is a cross-sectional perspective view showing an actuator according to an embodiment of the present disclosure, Figure 4 is an exploded perspective view showing an actuator according to an embodiment of the present disclosure, Figure 5 is an exploded perspective view showing a reduction gear unit according to an embodiment of the present disclosure, Figure 6 is a sectional view showing a reduction gear unit according to an embodiment of the present disclosure, Figure 7 is a perspective view illustrating a worm gear according to an embodiment of the present disclosure.

[0053] See also Figures 3 to 7 , the actuator 40 according to an embodiment of the present disclosure includes a motor 50, a power transmission unit 60 connected to the motor 50, a reduction gear unit 100 connected to the power transmission unit 60, and a housing 70 and a cover 80 coupled to each other to accommodate them.

[0054] The housing 70 has an open top, and the cover 80 is coupled to the housing 70 to cover the open top of the housing 70 .

[0055] The housing 70 has a motor accommodating portion 71 for accommodating the motor 50 on one side and a gear accommodating portion 72 for accommodating the reduction gear unit 100 on the other side.

[0056] The motor accommodating portion 71 has a depth that can accommodate the motor 50 and can be formed as a cylindrical groove with an open top, and the gear accommodating portion 72 is located adjacent to the motor accommodating portion 71 and can be formed as a cylindrical groove capable of accommodating the reduction gear unit 100 .

[0057] The cover 80 is installed to cover the open top of the housing 70 , and is provided with a cylindrical shaft supporting portion 81 extending downward on a surface facing the gear accommodating portion 72 .

[0058] The shaft support portion 81 is a portion on which a rotating shaft 152 of a planetary carrier 150 , which is a component of the reduction gear unit 100 , is rotatably supported.

[0059] The motor 50 may be configured to rotate in two directions, and power transmission from the motor 50 to the reduction gear unit 100 may be performed through the power transmission unit 60 .

[0060] The power transmission unit 60 includes a worm member 61 that receives power from the motor 50 and transmits the power to the reduction gear unit 100 .

[0061] The worm member 61 includes a shaft portion 61 a , helical gear teeth 61 b ​​provided on the shaft portion 61 a , and driven worm wheels 61 c and bearings 61 d mounted at opposite ends of the shaft portion 61 a .

[0062] The driving worm 51 is coupled to a rotation shaft of the motor 50 , and the driving worm 51 meshes with the driven worm wheel 61 c of the worm member 61 to transmit the rotational force of the motor 50 to the worm member 61 .

[0063] Then, the rotation of the worm member 61 is transmitted to the reduction gear unit 100 , and then the output is increased through the output shaft 42 of the reduction gear unit 100 .

[0064] The reduction gear unit 100 includes: a worm wheel 110, which is engaged with the worm member 61; a ring gear 120, which is arranged below the worm wheel 110 and formed as an internal gear; a sun gear 130, which has an upper end supported to rotate relative to the worm wheel 110 and a lower end extending to the inside of the ring gear 120; a plurality of planetary gears 140, which are arranged on the inner side of the ring gear 120 to be engaged with the sun gear 130 and the ring gear 120; a planetary carrier 150, on which a plurality of planetary gears 140 are rotatably supported; and a clutch spring 160, which selectively tightens or loosens the outer peripheral surface of the shaft support part 81 according to the rotation direction when the worm wheel 110 and the sun gear 130 rotate relative to each other, and can be slidably wound on the outer peripheral surface of the shaft support part 81.

[0065] The worm wheel 110 has a cylindrical shape and is provided on an outer circumference thereof with helical gear teeth 111 that mesh with the helical gear teeth 61 b ​​of the worm member 61 .

[0066] The worm gear 110 includes a circular body 112 made of steel and an annular body 113 made of plastic, which is coupled to the outer circumference of the circular body 112 .

[0067] The circular body 112 and the annular body 113 may be manufactured by insert injection, and the helical gear teeth 111 are provided on the outer circumference of the annular body 113 .

[0068] A concave receiving groove 114 is formed on an upper surface of the circular body 112 , and a locking rib 115 extending from a sidewall 114 a of the receiving groove 114 is provided within the receiving groove 114 .

[0069] The plurality of locking ribs 115 may be provided at equal intervals along the circumferential direction of the receiving groove 114. The locking ribs 115 of the embodiment of the present disclosure illustrate an example in which three locking ribs 115 are arranged at equal intervals, but are not limited thereto.

[0070] Each locking rib 115 includes a first portion 115 a extending from a side wall 114 a of the receiving groove 114 toward the center of the receiving groove 114 and a second portion 115 b extending from an end of the first portion 115 a in the longitudinal direction.

[0071] The sun gear 130 includes a body 131 , support ribs 132 , and a gear portion 133 .

[0072] The body 131 of the sun gear 130 is inserted into the hole 116 passing through the center of the bottom 114b of the receiving groove 114, the support rib 132 extends outward from the upper end of the body 131 to be slidably supported on the bottom 114b of the receiving groove 114, and the gear part 133 extends downward from the lower end of the body 131 to be located in the ring gear 120.

[0073] The plurality of support ribs 132 may be provided at equal intervals along the circumferential direction of the body 131. The number of support ribs 132 of the embodiment of the present disclosure shows an example of three, but is not limited thereto.

[0074] The support rib 132 may be located between each of the plurality of locking ribs 115 provided in the receiving groove 114. When the sun gear 130 rotates relative to the worm gear 110, the support rib 132 may contact the locking rib 115 after rotating by a predetermined angle.

[0075] The clutch spring 160 is arranged in a state where it can be slidably wound on the outer peripheral surface of the shaft support portion 81 extending from the cover 80, and when the worm gear 110 and the sun gear 130 rotate relative to each other, the clutch spring contacts at least one of the support rib 132 and the locking rib 115 according to the direction of rotation.

[0076] The clutch spring 160 includes a spiral-shaped body 161 that wraps around the outer surface of the shaft support portion 81 multiple times, and a first end 162 and a second end 163 that protrude outward from upper and lower ends of the body 161 .

[0077] When the clutch spring 160 is mounted on the outer surface of the shaft support portion 81, the first end 162 protruding from the lower end of the body 161 of the clutch spring 160 is positioned between the support rib 132 and the first portion 115a of the locking rib 115, and the second end 163 protruding from the upper end of the body 161 of the clutch spring 160 is positioned between the second portions 115b of the two locking ribs 115 adjacent to each other at the upper end of the support rib 132.

[0078] Therefore, when the sun gear 130 rotates relative to the worm gear 110 , the first end 162 of the clutch spring 160 may contact the support rib 132 and the first portion 115 a of the locking rib 115 , and the second end 163 may contact the second portion 115 b of the locking rib 115 .

[0079] Therefore, when the worm wheel 110 rotates in one direction (e.g., counterclockwise), the first portion 115a of the locking rib 115 contacts the first end 162 to rotate together with the first end 162. At this time, the body 161 of the clutch spring 160 does not tension the outer peripheral surface of the shaft support portion 81, thereby causing the shaft support portion 81 to slide. Thereafter, when the first end 162 contacts the support rib 132, the sun gear 130 rotates together with the worm wheel 110. In this state, when the sun gear 130 rotates in another direction opposite to the one direction (e.g., clockwise), the first end 162 rotates in the direction in which the body 161 of the clutch spring 160 tensions the outer peripheral surface of the shaft support portion 81, so that the rotation of the sun gear 130 is restricted.

[0080] Conversely, when the worm wheel 110 rotates in the other direction (e.g., clockwise), the second end 163 of the clutch spring 160 contacts the second portion 115b of the locking rib 115 to rotate together. At this time, the body 161 of the clutch spring 160 does not tension the outer peripheral surface of the shaft support portion 81, thereby causing the shaft support portion 81 to slide. Thereafter, when the first portion 115a of the locking rib 115 contacts the support rib 132, the sun gear 130 rotates together with the worm wheel 110.

[0081] The plurality of planetary gears 140 are rotatably mounted on shafts 151 formed on the planetary carrier 150. For example, three planetary gears 140 are arranged at equal intervals along the circumferential direction of the sun gear 130.

[0082] The planet carrier 150 is formed in the form of a disk, and the output shaft 42 is provided on the opposite surface to which the planetary gear 140 is mounted. Since the output shaft 42 is connected to the shaft portion 32b of the rotating inclined surface 32 of the BIR mechanism 30, the output shaft 42 transmits the output of the reduction gear unit 100 to the output conversion device 20.

[0083] The ring gear 120 may have a hollow cylindrical shape with an open bottom, and may be coupled to the inside of the gear receiving portion 72 to restrict rotation.

[0084] A plurality of coupling grooves 74 are provided around the side wall 73 of the gear receiving portion 72, which are spaced apart from each other at predetermined intervals. A plurality of coupling ribs 121, which are spaced apart from each other at predetermined intervals along the outer circumference of the ring gear 120, enter and engage with the coupling grooves 74 from the upper portions. Thus, the ring gear 120 is coupled in a state where its rotation is restricted in the gear receiving portion 72.

[0085] Hereinafter, operations of the actuator during braking and releasing of the brake of the braking apparatus according to the embodiment of the present disclosure will be described.

[0086] Figure 8 is a view showing an operating state of a reduction gear unit during braking according to an embodiment of the present disclosure, Figure 9 is a view showing an operating state of the reduction gear unit according to an embodiment of the present disclosure according to transmission of reverse rotation torque after braking, and Figure 10 is a view illustrating an operating state of the reduction gear unit according to an embodiment of the present disclosure when the brake is released.

[0087] Reference Figure 1 and Figure 8 When the motor 50 is driven during braking, the power of the motor 50 is transmitted to the worm wheel 110 through the driving worm 51, the driven worm wheel 61c and the helical gear teeth 61b of the worm member 61, and the worm wheel 110 receiving the power of the worm member 61 rotates counterclockwise.

[0088] When the worm wheel 110 rotates counterclockwise, the locking rib 115 of the worm wheel 110 contacts the first end 162 of the clutch spring 160 to rotate counterclockwise. In this case, because the body 161 of the clutch spring 160 does not tension the outer peripheral surface of the shaft support portion 81, the first end 162 of the clutch spring 160 rotates together with the worm wheel 110 and then contacts the support rib 132 of the sun gear 130, causing the sun gear 130 to rotate counterclockwise.

[0089] Therefore, the rotational force of the worm gear 110 is transmitted to the plurality of planetary gears 140 through the sun gear 130, and the plurality of planetary gears 140 rotate around the sun gear 130 along the gear teeth 122 of the ring gear 120, thereby rotating the planetary carrier 150. The rotation of the planetary carrier 150 rotates the rotating inclined surface 32 of the output conversion device 20 through the output shaft 42.

[0090] When the rotation ramp 32 of the output conversion device 20 rotates, the balls 33 roll between the inclined guide grooves 31b and 32c. As a result, the rotation ramp 32 rotates and moves the push member 21 forward in the axial direction to press the piston 12, thereby performing braking.

[0091] Reference Figure 9When the power of the motor 50 is released after braking, the reverse rotation torque transmitted by the reaction force of the output conversion device 20 through the output shaft 42 causes the sun gear 130 to rotate clockwise.

[0092] When the sun gear 130 rotates clockwise, the support rib 132 of the sun gear 130 contacts the first end 162 of the clutch spring 160, causing the first end 162 to rotate clockwise. In addition, when the body 161 of the clutch spring 160 is tensioned on the outer surface of the shaft support portion 81, the rotation of the sun gear 130 is limited by friction to prevent the reduction gear unit 100 from loosening.

[0093] Reference Figure 10 When the brake is released and the motor 50 is driven, the power of the motor 50 is transmitted to the worm wheel 110 through the driving worm 51, the driven worm wheel 61c and the worm member 61, and the worm wheel 110 receiving the power of the worm member 61 rotates clockwise.

[0094] When worm gear 110 rotates clockwise, locking rib 115 of worm gear 110 contacts second end 163 of clutch spring 160, causing second end 163 to rotate clockwise. In this state, since body 161 of clutch spring 160 does not tension the outer circumferential surface of shaft support portion 81, it rotates along with worm gear 110. Thereafter, locking rib 115 of worm gear 110 contacts support rib 132 of sun gear 130, causing sun gear 130 to rotate clockwise, thereby releasing the rotational torque transmitted to output conversion device 20.

[0095] As described above, although several embodiments of the present disclosure have been shown and described, it will be appreciated by those skilled in the art that changes may be made to these embodiments without departing from the principles and spirit of the present disclosure, the scope of which is defined by the claims and their equivalents.

Claims

1. An actuator for a braking device, the actuator comprising: a housing accommodating a motor, a power transmission unit connected to the motor, and a reduction gear unit connected to the power transmission unit; as well as a cover covering the open top of the housing and having a shaft supporting portion; Wherein, the reduction gear unit comprises: a worm wheel that is rotated by receiving power from the power transmission unit, the worm wheel including a concave receiving groove on an upper surface of the worm wheel and a locking rib provided in the receiving groove; a sun gear rotatably supported on the bottom of the receiving groove and having a support rib that can contact the locking rib during rotation; and a clutch spring provided in a state of being slidably wound around an outer peripheral surface of the shaft support portion and configured to selectively tighten or loosen the outer peripheral surface of the shaft support portion by contacting at least one of the support rib and the locking rib according to a rotational direction when the worm gear and the sun gear rotate relative to each other, wherein when the worm wheel rotates in one direction, the locking rib contacts the clutch spring, and when the worm wheel rotates in the other direction, the locking rib contacts the clutch spring and the support rib.

2. The actuator according to claim 1, wherein The clutch spring includes: a body that surrounds the outer peripheral surface of the shaft supporting portion multiple times; a first end that protrudes from a lower end of the body to be positioned between the support rib and the locking rib and is capable of contacting the support rib and the locking rib during rotation; and a second end that protrudes from an upper end of the body and is capable of contacting the locking rib during rotation.

3. The actuator according to claim 2, wherein: When the worm wheel rotates counterclockwise, the first end is configured to rotate counterclockwise while in contact with the support rib and the locking rib, so that the body can slide relative to the outer surface of the shaft support portion.

4. The actuator according to claim 2, wherein: When the worm wheel rotates clockwise, the second end is configured to rotate clockwise while in contact with the locking rib, so that the body can slide relative to the outer surface of the shaft supporting portion.

5. The actuator according to claim 3, wherein: When the sun gear rotates clockwise, the first end is configured to rotate clockwise via the support rib, causing the body to tension the outer surface of the shaft support portion.

6. The actuator according to claim 1, wherein A plurality of the support ribs and the locking ribs are alternately positioned in the receiving groove along a circumferential direction to contact each other during rotation.

7. The actuator according to claim 2, wherein: The locking rib includes a first portion and a second portion, wherein the first portion extends from a side wall of the receiving groove toward the center of the receiving groove and contacts at least one of the support rib and the first end during rotation, and the second portion extends from the first portion in a longitudinal direction and contacts the second end during rotation.

8. The actuator according to claim 1, wherein The reduction gear unit comprises: a plurality of planetary gears meshing with the sun gear; a ring gear serving as an internal gear to accommodate the plurality of planetary gears; and A planet carrier rotatably supports the plurality of planetary gears and has a rotation shaft supported by the shaft support portion to rotate coaxially with the sun gear.

9. The actuator according to claim 1, wherein: The worm gear includes a circular body formed with the receiving groove and an annular body coupled to an outer circumference of the circular body and having a gear portion.

10. The actuator according to claim 9, wherein The circular body comprises a steel material, and the annular body comprises a plastic material.

11. The actuator according to claim 10, wherein: The circular body and the annular body are manufactured by insert injection.

12. The actuator according to claim 1, wherein The power transmission unit includes a worm member including a shaft portion having helical gear teeth and a driven worm wheel provided at one end of the shaft portion to mesh with a driving worm coupled to a rotation shaft of the motor.

13. A braking device, comprising: a piston slidably disposed in a cylinder of the caliper housing to press the backing plate; an actuator including a housing accommodating a motor, a power transmission unit connected to the motor, and a reduction gear unit connected to the power transmission unit, and a cover covering an open top of the housing and having a shaft supporting portion; as well as an output conversion device that receives rotational motion from the actuator and converts the rotational motion into linear motion to apply thrust to move the piston; Wherein, the reduction gear unit comprises: a worm wheel that is rotated by receiving power from the power transmission unit, the worm wheel including a concave receiving groove on an upper surface of the worm wheel and a locking rib provided in the receiving groove; a sun gear rotatably supported on the bottom of the receiving groove and having a support rib that can contact the locking rib during rotation; and a clutch spring provided in a state of being slidably wound around an outer peripheral surface of the shaft support portion and configured to selectively tighten or loosen the outer peripheral surface of the shaft support portion by contacting at least one of the support rib and the locking rib according to a rotational direction when the worm gear and the sun gear rotate relative to each other, wherein when the worm wheel rotates in one direction, the locking rib contacts the clutch spring, and when the worm wheel rotates in the other direction, the locking rib contacts the clutch spring and the support rib.

14. The braking device according to claim 13, wherein: The clutch spring includes: a body that surrounds the outer peripheral surface of the shaft supporting portion multiple times; a first end that protrudes from a lower end of the body to be positioned between the support rib and the locking rib and is capable of contacting the support rib and the locking rib during rotation; and a second end that protrudes from an upper end of the body and is capable of contacting the locking rib during rotation.

15. The braking device according to claim 14, wherein: When the sun gear rotates by the reaction force of the output conversion device after braking, the body tensions the outer peripheral surface of the shaft support portion as the support rib presses and rotates the first end.

Images