Parking brake device

Abstract

A parking brake device may include: a driving part; a driving gear rotatably connected to the driving part; a gear shaft meshed with the driving gear to be rotated by the driving gear; two pistons disposed on both sides of the gear shaft and respectively connected to brake shoes; two nuts disposed in each of the pistons and screwed onto the gear shaft; an elastic member installed between the piston and the nut for urging the nut toward the brake shoe; a retainer installed in the piston for supporting the elastic member; and a retainer ring installed in the piston for retaining the retainer.

Description

Cross-reference to related applications

[0001] This application claims priority under 35 USC §119(a) to Korean Application No. 10-2019-0017672, filed in the Korean Intellectual Property Office on February 15, 2019, which is incorporated herein by reference in its entirety. Background1. Technical area

[0002] Embodiments of the present disclosure relate to a parking brake device, and more particularly, to a parking brake device that can improve assembly efficiency and control an elastic member to compensate for stroke loss even when another elastic member is damaged. 2. State of the art

[0003] In general, an EPB (Electronic Parking Brake) is a device that applies a parking brake using the power of a drive motor, without requiring driver input, to prevent a parked vehicle from moving. That is, when the EPB motor is driven to rotate a worm gear, a worm gear meshing with the worm gear rotates to move a piston. The parking brake is then applied or released.

[0004] The piston has a nut built into it, and an elastic element is installed between the nut and the piston. When a brake shoe is rotated, stroke loss may occur, causing the piston and brake shoe to separate. When stroke loss occurs, the elastic element can push the piston toward the brake shoe, thereby compensating for the stroke loss.

[0005] However, in the current art, if the elastic element is damaged, the piston cannot be elastically pushed toward the brake shoe. Thus, the stroke loss cannot be compensated. Furthermore, the assembly efficiency of the parking brake device may be insufficient because the piston, elastic element, a bolt, and the worm gear are installed separately. Therefore, there is a need for a device capable of solving this problem.

[0006] The prior art of the present disclosure is disclosed in Korean Patent Application Publication No. 2006-0134444, published on December 28, 2006, titled "Parking Brake Apparatus of Disk Brake." KR 10 1 910 854 B1 discloses a parking brake apparatus having the features of the preamble of claim 1. overview

[0007] Various different embodiments relate to a parking brake device which can improve assembly efficiency and can control one elastic member to compensate for stroke loss even when the other elastic member is damaged.

[0008] According to the invention, a parking brake device comprises: a driving part; a driving gear rotatably connected to the driving part; a gear shaft engaged with the driving gear to be rotated by the driving gear; two pistons arranged on both sides of the gear shaft and respectively connected to brake shoes; two nuts arranged in the respective pistons and screwed onto the gear shaft; an elastic member installed between the piston and the nut for urging the nut toward the brake shoe; a retainer installed in the piston for supporting the elastic member; and a retainer ring installed in the piston for retaining the retainer.

[0009] According to the invention, the retainer comprises: a first retaining ring installed in the piston to support the elastic member; and a second retaining ring fitted onto the first retaining ring, configured to retain the nut and retained by the retaining ring.

[0010] The second retaining ring may have a second projection portion for retaining the first retaining ring, and the first retaining ring may be locked to the retaining ring and retained by the retaining ring.

[0011] The second retaining ring may have a retaining threaded portion formed on its inner surface, and the nut may have an external threaded portion formed on its outer surface for screwing with the retaining threaded portion.

[0012] The piston may have a retaining groove formed in its inner surface such that the retaining ring is locked to the retaining groove and is retained by the retaining groove.

[0013] The elastic element may comprise a plurality of disc springs stacked in the piston.

[0014] The piston may include: a piston body portion having a receiving space portion in which the nut and the elastic member are received, and a rotation-blocking portion configured to be connected to the receiving space and prevent rotation of the nut; and a piston pressure portion extending from the piston body portion to be connected to the brake shoe.

[0015] The rotation-locking member may be formed with a polygonal shape, and the nut may have a polygonal flange formed on the outer surface thereof to be retained by the rotation-locking member.

[0016] The drive part may include a motor and a reducer, and a driving force of the motor may be transmitted to the gear shaft via the reducer.

[0017] The gear shaft may comprise: a worm gear engaging the drive gear; and two screws extending axially from each side of the worm gear and having a screw thread engaged with the nut.

[0018] The screw threads of both screws can be formed in opposite directions, the worm and the screws can be rotated when the drive gear is rotated, and the nuts and the pistons can be rotated in the axial direction of the gear shaft when the screws are rotated.

[0019] According to the embodiment of the present disclosure, since the pistons, the nuts, and the elastic members are assembled into an assembly, the assembly efficiency of the parking brake device can be improved and the assembly time can be shortened.

[0020] Furthermore, since the retainer ring is inserted into the piston and the holder and the elastic member are fixed so as not to be separable from each other, the assembly efficiency of the parking brake device can be improved.

[0021] Furthermore, since the two elastic elements are mounted on both sides of the transmission shaft and the pistons are elastically supported by the respective elastic elements, the elastic force of one elastic element can be applied to both pistons even if the other elastic element is damaged. Therefore, even if the other elastic element is damaged, the elastic force of one elastic element can be applied to both brake shoes, thereby compensating for piston stroke losses. Brief description of the drawings Fig. 1 is a perspective view illustrating a parking brake device according to an embodiment of the present disclosure. Fig. 2 is a cross-sectional view illustrating the parking brake device according to the embodiment of the present disclosure. Fig. 3 is a cross-sectional view showing the internal structure of a piston in the parking brake device according to the embodiment of the present disclosure. Detailed description

[0022] A parking brake device will be described below with reference to the accompanying drawings using various examples of embodiments. It should be noted that the drawings are not exactly to scale and may be exaggerated in line thickness or component size solely for the purpose of better description and clarity. Furthermore, the terms used herein are defined with functions of the disclosure in mind and may be changed according to the habits or intentions of users or operators. Therefore, the definitions of the terms should be consistent with the present disclosure as a whole.

[0023] Fig. 1 is a perspective view showing a parking brake device according to an embodiment of the present disclosure, Fig. 2 is a cross-sectional view showing the parking brake device according to the embodiment of the present disclosure, and Fig. 3 is a cross-sectional view showing the internal structure of a piston in the parking brake device according to the embodiment of the present disclosure.

[0024] With reference to the Fig. 1 to 3, the parking brake device according to the embodiment of the present disclosure includes a drive part 10, a drive gear 20, a gear shaft 30, two pistons 40, two nuts 50, two elastic members 60, two holders 70, and two retaining rings 80.

[0025] The drive part 10 has a motor 11 and a reducer 13. The drive force of the motor 11 is transmitted by the reducer 13 to the drive gear 20.

[0026] The drive gear 20 is rotatably connected to the drive part 10. The drive gear 20 is axially connected to a driven gear (not shown) of the reducer 13. A worm gear can be used as the drive gear 20.

[0027] The gear shaft 30 meshes with the drive gear 20 so that it is rotated by the drive gear. The gear shaft 30 has a worm 31 that meshes with the drive gear 20 and two screws 33 that extend axially from both sides of the worm 31 and are connected to the respective nuts 50. Both screws 33 have threads formed in opposite directions. When the drive gear 20 rotates, the worm 31 and the screws 33 are rotated. When the screws 33 are rotated, the nuts 50 and the pistons 40 are rotated in the axial direction of the gear shaft 30. At this time, the two pistons 40 are moved simultaneously to both sides of the gear shaft 30 or simultaneously toward the center of the gear shaft 30. Therefore, the two pistons 40 are moved away from each other or towards each other.

[0028] Pistons 40 are arranged on both sides of the transmission shaft 30 and connected to two brake shoes 1. When pistons 40 apply pressure to brake shoes 1, vehicle wheels (not shown) are prevented from rotating. When pistons 40 are moved to opposite sides of brake shoes 1, the vehicle wheels are released.

[0029] Each of the pistons includes a piston body portion 41 and a piston thrust portion 45. The piston body portion 41 includes a receiving space portion 42 in which the nut 50 and the elastic member 60 are received, and a rotation-blocking portion 43 communicating with the receiving space portion 42 and preventing rotation of the nut 50. The rotation-blocking portion 43 has a smaller inner diameter than the receiving space portion 42. Since the piston body portion 41 includes the rotation-blocking portion 43 for preventing rotation of the nut 50, the rotation of the transmission shaft 30 is converted into a linear movement of the nut 50.

[0030] The rotation-blocking part 43 is formed in a polygonal shape, and the nut 50 has a polygonal flange part 54 formed on its outer surface to be retained by the rotation-blocking part 43. Since the polygonal flange part 54 is retained by the rotation-blocking part 43, the nut 50 is not rotated but is moved straight when the gear shaft 30 is rotated.

[0031] The nut 50 is arranged in each of the pistons 40 and is screwed onto the transmission shaft 30. The nut 50 has a nut threaded portion 51 formed on its inner surface. The nut threaded portion 51 is screwed onto the screw 33 of the transmission shaft 30. When the transmission shaft 30 is rotated, the nut 50 and the piston 60 are moved together in the axial direction of the transmission shaft 30.

[0032] The elastic member 60 is installed between the piston 40 and the nut 50 to urge the nut 50 toward the brake shoe 1. The elastic member 60 includes a plurality of disc springs 61 stacked within the piston 40. The elastic member 60 elastically urges the piston 40 toward the brake shoe 1. Since the elastic member 60 elastically urges the brake shoe 1, when a stroke loss occurs that separates the piston 40 from the brake shoe 1, the elastic member 60 urges the piston 40 toward the brake shoe 1. Therefore, the stroke loss of the piston 40 can be compensated.

[0033] Since the elastic elements 60 are installed on both sides of the transmission shaft 30, and the pistons 40 are each elastically supported by the elastic elements 60, an elastic force from one elastic element 60 can be applied to both pistons 40 even though the other elastic element 60 is damaged. Therefore, the one elastic element 60 can compensate for stroke losses occurring at both brake shoes 1.

[0034] The retainer 70 is installed in the piston 40 to support one end of the elastic member 60. Since the retainer 70 is installed in the piston 40 to support the end of the elastic member 60, the retainer 70 can prevent the elastic member 60 from detaching outward from the piston 40.

[0035] The retainer 70 includes a first retaining ring 71 and a second retaining ring 73. The first retaining ring 71 is installed in the piston 40 to support the elastic member 60. The first retaining ring 71 is formed in an annular shape overall. The second retaining ring 73 is fitted onto the first retaining ring 71 and retains the nut 50 while being retained by the retaining ring 80. Since the second retaining ring 73 retains the nut 50 and the retaining ring 80 retains the second retaining ring 73, the elastic member 60 and the nut 50 can be prevented from detaching from the piston 40. Furthermore, since the retaining ring 80 is installed in the piston 40 to retain the second retaining ring 73, the assembly efficiency of the parking brake device can be improved and the assembly time can be shortened.

[0036] The retainer ring 80 is installed in the piston 40 to retain the retainer 70. The retainer ring 80 is partially cut and formed into a C-shape. When the retainer ring 80 is inserted into the piston 40, the retainer ring 80 expands outward due to its restoring force and is fixed to the piston 40. Therefore, when the retainer ring 80 is in the piston 40, the retainer 70 and the elastic member 60 are fixed so that they cannot be separated from each other, thereby making it possible to improve the assembly efficiency of the parking brake device.

[0037] The second retaining ring 73 has a second projection portion 73a for retaining the first retaining ring 71, and the first retaining ring 71 is locked to and retained by the retaining ring 80. Since the first retaining ring 71 is locked to and retained by the second projection portion 73a and the retaining ring 80, the elastic member 60 can be prevented from detaching from the piston 40.

[0038] The second retaining ring 73 has a retaining threaded portion 73b formed on its inner surface, and the nut 50 has an external threaded portion 52 formed on its outer surface for screwing with the retaining threaded portion 73b. Since the second retaining ring 73 is screwed onto the outer surface of the nut 50, the nut 50 is prevented from being detached from the piston 40.

[0039] The piston 40 has a retaining groove 44 formed in its inner surface such that the retaining ring 80 is locked to and retained by the retaining groove 44. The retaining groove 44 is formed annularly along the inner surface of the piston 40. Since the retaining ring 80 is locked to and retained by the retaining groove 44, the first retaining ring 71 and the elastic member 60 can be prevented from detaching from the piston 40.

[0040] According to the present disclosure, since the pistons 40, the nuts 50, and the elastic members 60 can be assembled and formed as an assembly, the assembly efficiency of the parking brake device can be improved and the assembly time can be shortened.

[0041] The operation of the parking brake device according to the embodiment of the present invention having the above-described configuration will be described below.

[0042] When a vehicle is parked, the drive part 10 is driven. This drives the motor 11, and the speed of the motor 11 is reduced by the reducer 13. As the reducer 13 is driven, the drive gear 20 is rotated in one direction. As the drive gear 20 engages with the worm 31 of the gear shaft 30 and is rotated, the two nuts 50 and the two pistons 40 are moved toward the respective brake shoes 1. As the pistons 40 press against the brake shoes 1, the vehicle wheels are locked.

[0043] Since the two elastic elements 60 are installed on both sides of the transmission shaft 30, and the pistons 40 are elastically supported by the respective elastic elements 60, an elastic force of one elastic element 60 can be applied to both pistons 40 even if the other elastic element 60 is damaged. Therefore, even if the other elastic element 60 is damaged, the elastic force of one elastic element 60 can be applied to both brake shoes 1, thereby compensating for stroke losses of the pistons 40.

[0044] While preferred embodiments of the invention have been disclosed for illustrative purposes, it will be apparent to those skilled in the art that numerous modifications, additions, and substitutions are possible without departing from the scope of the invention as defined in the appended claims. The true technical scope of the disclosure is therefore defined by the following claims.

Claims

[1] Parking brake device comprising: a drive part (10); a drive gear (20) rotatably connected to the drive part (10); a gear shaft (30) meshing with the drive gear (20) to be rotated by the drive gear (20); two pistons (40) arranged on both sides of the transmission shaft (30) and each connected to brake shoes (1); two nuts (50) arranged in the respective pistons (40) and screwed onto the gear shaft (30); an elastic element (60) installed between the piston (40) and the nut (50) for pressing the nut (50) towards the brake shoe (1); a holder (70) installed in the piston (40) for supporting the elastic element (60); and a retaining ring (80) installed in the piston (40) to retain the holder (70), the holder (70) comprising: a first retaining ring (71) installed in the piston (40) to support the elastic element (60), and a second retaining ring (73), characterized by , that the second retaining ring (73) is placed on the first retaining ring (71) and is designed to retain the nut (50) and is retained by the retaining ring (80). [2] A parking brake device according to claim 1, wherein the second retaining ring (73) has a second projection part (73a) for retaining the first retaining ring (71), and the first retaining ring (71) is locked to the retaining ring (80) and retained by the retaining ring (80). [3] A parking brake device according to claim 2, wherein the second retaining ring (73) has a retaining threaded part (73b) formed on the inner surface thereof, and the nut (50) has an external threaded part (52) formed on the outer surface thereof for screwing with the retaining threaded part (73b). [4] A parking brake device according to claim 1, wherein the piston (40) has a retaining groove (44) formed in its inner surface such that the retaining ring (80) is locked to the retaining groove (44) and is retained by the retaining groove (44). [5] A parking brake device according to claim 1, wherein the elastic member (60) comprises a plurality of disc springs (61) stacked in the piston (40). [6] Parking brake device according to claim 1, wherein the piston (40) comprises: a piston body part (41) having a receiving space part (42) in which the nut (50) and the elastic element (60) are received, and a rotation-blocking part (43) which is designed such that it is connected to the receiving space (42) and prevents the rotation of the nut (50); and a piston pressure part (45) extending from the piston body part (41) to be connected to the brake shoe (1). [7] A parking brake device according to claim 6, wherein the rotation-blocking member (43) is formed with a polygonal shape, and the nut (50) has a polygonal flange (54) formed on the outer surface thereof to be retained by the rotation-blocking member (43). [8] Parking brake device according to claim 1, wherein the drive part (10) comprises a motor (11) and a reducer (13), and a driving force of the motor (11) is transmitted to the transmission shaft (30) via the reducer (13). [9] Parking brake device according to claim 1, wherein the transmission shaft (30) may comprise: a worm (31) which engages with the drive gear (20); and two screws (33) which extend axially from both sides of the screw (31) and have a screw thread screwed to the nut (50). [10] Parking brake device according to claim 9, wherein the screw threads of both screws (33) are formed in opposite directions, the worm (31) and the screws (33) are rotated when the drive gear (20) is rotated, and the nuts (50) and the pistons (40) are rotated in the axial direction of the gear shaft (30) when turning the screws (33).

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