ELECTRONIC PARKING BRAKE

Abstract

Electronic parking brake, comprehensive: a drum (10) which rotates with a wheel of a vehicle; Brake shoes (20) which are attached to two sides in the drum (10) to brake the drum (10); a wheel cylinder (30) designed to press the brake shoes (20) in order to bring the brake shoes (20) into contact with an inner circumferential surface of the drum (10); and an actuator that generates the drive power for the drive of the wheel cylinder (30), wherein the actuator comprises a drive motor (40) which generates the drive power for braking the drum (10) and a transmission shaft (50) which transmits the drive power of the drive motor (40) to the wheel cylinder (30) and The electronic parking brake further comprises a first helical gear element (100) that transmits the drive power of the drive motor (40) to the transmission shaft (50), and a second helical gear element (200) that transmits the drive power transmitted via the transmission shaft (50) to the wheel cylinder (30). wherein a drive shaft (41) of the drive motor (40) and a rotary shaft of the wheel cylinder (30) are inclined to each other, wherein a housing (300) is provided on the outside of the actuator; and the housing (300) comprises a first housing (310) that surrounds the drive motor (40) and one side of the transmission shaft (50), and a second housing (320) that surrounds the wheel cylinder (30) and the other side of the transmission shaft (50), wherein the transmission shaft (50) comprises a first shaft (51) which is housed in the first casing (310) and connected to the drive motor (40), and a second shaft (52) which is housed in the second housing (320) and connected to the wheel cylinder (30), wherein the second shaft (52) is connected to the first shaft (51) when the first housing (310) and the second housing (320) are installed on a support plate (60).

Description

field of technology

[0001] The present invention relates to an electronic parking brake, and more particularly to an electronic parking brake in which an electronic actuator is applied to a drum brake to reduce noise when the drive power of a drive motor is transmitted, and a rotating shaft of the drive motor and a rotating shaft of a wheel cylinder are arranged to be inclined to each other. General state of the art

[0002] Generally, a parking brake is a device for stopping a vehicle so that the vehicle does not move when parked. It is used to hold a wheel of the vehicle in place so that the wheel does not rotate. A drum brake type device can be used as a parking brake, and braking force is generally generated by pulling a parking cable when a handbrake or footbrake is applied.

[0003] EP 3 089 897 B1 discloses an electronic parking brake comprising a first and second housing and a multi-part transmission shaft. The transmission shaft consists of a first hollow shaft (gear) and a second shaft, which, however, must be axially displaced in the second housing for the assembly of the complete drive. Furthermore, JP 2017-110 775 A discloses an electronic parking brake comprising an inclined arrangement of a drive shaft of the drive motor and a rotating shaft of a wheel cylinder.

[0004] Although a study on an electronic parking brake with an actuator attached has been conducted for a drum brake parking brake, there is a problem of loud noise because a plurality of planetary gears are used between a drive motor and an output shaft.

[0005] In addition, since a drive shaft and the output shaft of the drive motor are arranged in parallel, there is the problem that the degree of design freedom and installability is reduced.

[0006] There is therefore room for improvement in this area. RevelationTechnical task

[0007] The present invention relates to an electronic parking brake in which an electronic actuator is applied to a drum brake and which is capable of reducing noise when the drive power of a drive motor is transmitted.

[0008] Furthermore, the present invention is directed to providing an electronic parking brake in which a rotating shaft of a drive motor and a rotating shaft of a wheel cylinder are arranged to be inclined to each other. Technical solution

[0009] The subject matter of the invention is defined in claim 1. Advantageous further developments are set out in the dependent claims and the following description.

[0010] One aspect of the present invention provides an electronic parking brake comprising a drum that rotates with a wheel of a vehicle, brake shoes installed on two sides of the drum to brake the drum, a wheel cylinder configured to press the brake shoes to bring the brake shoes into contact with an inner peripheral surface of the drum, and an actuator that generates drive power for driving the wheel cylinder. The actuator comprises a drive motor that generates drive power for braking the drum and a transmission shaft that transmits the drive power of the drive motor to the wheel cylinder. The electronic parking brake further comprises a first helical gear member that transmits the drive power of the drive motor to the transmission shaft, and a second helical gear member.which transfers the drive power transmitted via the transmission shaft to the wheel cylinder.

[0011] The first helical gear member may include a drive gear provided on a drive shaft of the drive motor, and a first transmission gear provided on one side of the transmission shaft and meshing with the drive gear.

[0012] A first angle can be formed between a rotational axis of the drive wheel and a rotational axis of the first transmission gear.

[0013] The second helical gear member may include a second transmission gear on the other side of the transmission shaft and a driven gear on the wheel cylinder meshing with the second transmission gear.

[0014] A second angle can be formed between a rotational axis of the second transmission gear and a rotational axis of the driven gear.

[0015] Alternatively, the driven gear may be rotated by the driving force transmitted through the transmission shaft, and the facing brake shoes may be controlled to come into contact with or separate from the inner peripheral surface of the drum depending on the direction of rotation of the driven gear.

[0016] A housing is provided outside the actuator, which includes a first housing surrounding the drive motor and one side of the transmission shaft, and a second housing surrounding the wheel cylinder and the other side of the transmission shaft.

[0017] A through-piece leading through a support plate can be built into the second housing.

[0018] A coupling part coupled to the passage part may be formed in the first housing. Beneficial effects

[0019] In an electronic parking brake of the present invention having the above-described structure, since a helical gear member is used when the drive power of a drive motor is transmitted to a wheel cylinder, the noise can be reduced and thus the product satisfaction of a user can be improved.

[0020] Furthermore, the inclination between the drive motor, a transmission shaft, and the wheel cylinder can be changed by means of first and second helical gear elements according to a design specification, thereby improving a certain degree of design freedom and installability. Description of drawings Fig. 1 and Fig. 2 are perspective views showing an electronic parking brake according to the present invention, wherein Fig. 1 is the view showing the electronic parking brake when viewed from one side of a carrier plate, and Fig. 2 is the view showing the electronic parking brake when viewed from the other side of the carrier plate. Fig. 3 is an exploded perspective view of an actuator included in the electronic parking brake according to the present invention. Fig. 4 is a plan view showing the actuator in the electronic parking brake according to the present invention. Fig. 5 is a perspective view showing the actuator of the electronic parking brake according to the present invention, that is, a view showing the actuator in a state where the support plate is removed. Embodiments of the invention

[0021] In the following, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that a person skilled in the art can readily utilize the present invention. The present invention can be implemented in a variety of different forms and is not limited to the embodiments described herein. Parts unimportant for description have been omitted from the drawings to clarify the nature of the present invention, and the same or similar parts are designated by the same reference numerals throughout the application.

[0022] It is further understood that the terms "comprises," "comprising," "has," and / or "having," when used herein, indicate the presence of the recited features, numbers, steps, acts, elements, and / or components, but do not preclude the presence or addition of one or more other features, numbers, steps, acts, elements, components, and / or groups thereof. When an element, such as a layer, film, region, plate, or the like, is referred to as being disposed "on" another part, this includes not only the element directly disposed on another element, but also any other element disposed therebetween.Conversely, when an element such as a layer, film, region, plate, or the like is referred to as being disposed "under" another part, this includes not only the element disposed directly under another element, but also another element disposed therebetween.

[0023] Fig. 1 and Fig. 2 are perspective views showing an electronic parking brake according to the present invention, wherein Fig. 1 is the view showing the electronic parking brake when viewed from one side of a carrier plate, Fig. 2 is the view showing the electronic parking brake when viewed from the other side of the carrier plate, Fig. 3 is an exploded perspective view showing an actuator included in the electronic parking brake according to the present invention, Fig. 4 is a plan view showing the actuator included in the electronic parking brake according to the present invention, and Fig. 5 is a perspective view showing the actuator of the electronic parking brake according to the present invention, that is, a view showing the actuator in a state where the support plate is removed.

[0024] As in the Fig. 1 to 3, the electronic parking brake includes a drum 10 that rotates with a wheel of a vehicle, brake shoes 20 disposed on two sides in the drum 10 to brake the drum 10, a wheel cylinder 30 that presses the opposed brake shoes 20 to bring the brake shoes 20 into contact with an inner peripheral surface of the drum 10, and an actuator that generates driving force for driving the wheel cylinder 30.

[0025] The actuator comprises a drive motor 40 which is electronically operated and generates a drive force or power for braking the drum 10, as well as a transmission shaft 50 via which the drive power of the drive motor 40 is transmitted to the wheel cylinder 30.

[0026] The drive motor 40 generates rotational force in the forward or reverse direction to generate drive power for driving the wheel cylinder 30. The drive motor 40 is connected to a control unit (not shown) that controls the drive motor 40, so that an operation of the drive motor 40 is controlled. For example, the control unit controls the drive motor 40 to perform various operations such as driving, stopping, forward rotation, and reverse rotation through input signals transmitted according to the operation commands of an operation switch operated by a driver. When the driver issues a command to apply or release the brake, the control unit rotates the drive motor 40 in the forward or reverse direction.Furthermore, the control unit may be connected to a load sensor (not shown) to detect a magnitude of the driving force transmitted to the wheel cylinder 30, and may receive a signal output from the load sensor to stop the drive motor 40 when the driving force transmitted to the wheel cylinder 30 is greater than or equal to a predetermined magnitude.

[0027] The transmission shaft 50 transmits the drive power of the drive motor 40, and the transmission shaft 50 may include a first shaft 51 connected to the drive motor 40 and a second shaft 52 connected to the wheel cylinder 30. When the transmission shaft 50 is configured as described and the drive motor 40 and the wheel cylinder 30 are installed on a support plate 60, the transmission shaft 50 does not need to be additionally installed because the first shaft 51 and the second shaft 52 are coupled to each other to form the transmission shaft 50, thus simplifying the installation process of an actuator. The first shaft 51 and the second shaft 52 may be coupled such that one of the two shafts is inserted into the other shaft. As shown in Fig. 3, for example, a cover is formed on the first shaft 51, into which one end of the second shaft 52 is inserted and which surrounds one end, wherein radially inwardly projecting teeth are formed on an inner peripheral surface of the cover, and tooth grooves into which the teeth are inserted are formed in the second shaft 52. Alternatively, radially outwardly projecting teeth may also be formed on the second shaft 52, and tooth grooves into which the teeth are inserted may also be formed in the first shaft 51.

[0028] The electronic parking brake may further include a first helical gear member 100 that transmits the drive power of the drive motor 40 to the transmission shaft 50, and a second helical gear member 200 that transmits the drive power transmitted via the transmission shaft 50 to the wheel cylinder 30. Since the first helical gear member 100 is provided for the drive motor 40, whose rotational speed is high, to transmit the drive power to the transmission shaft 50, noise can be reduced, and since the second helical gear member 200 is provided to transmit the drive power transmitted via the transmission shaft 50 to the wheel cylinder 30, noise can be further reduced.

[0029] As in the Fig. 3 and Fig. 4, the first helical gear member 100 may include a drive gear 110 provided on a drive shaft 41 of the drive motor 40, and a first transmission gear 120 provided on one side of the transmission shaft 50 and meshing with the drive gear 110.

[0030] In this case, the drive gear 110 can be formed integrally with the drive shaft 41 of the drive motor 40. That is, a drive motor with an integrated drive gear can be used. When the drive shaft 41 of the drive motor 40 rotates, the first transmission gear 120, which meshes with the drive gear 110 formed on the drive shaft 41, rotates with the transmission shaft 50. In this case, the transmission shaft 50 is rotatably supported in a housing 300, which will be described below.

[0031] In particular, a first angle α can be formed between a rotational axis 40a of the drive gear 110 and a rotational axis 50a of the first transmission gear 120. That is, the drive power supplied via the drive gear 110 is varied by the first angle α and transmitted via the transmission shaft 50. Furthermore, if the first angle α is set to meet a design specification, the installability of the drive motor 40 can be improved.

[0032] The first transmission gear 120 can be formed by envelope machining. Here, the envelope machining is performed in such a way that, when a tooth shape of one of two gears rotating according to a predetermined rule is determined, a tooth shape of the other gear rotating after the one gear is machined. That is, when a tooth shape of the drive gear 110 provided on the drive shaft 41 is determined, a tooth shape of the first transmission gear 120 can be machined by envelope machining. In this case, the tooth shape of the first transmission gear 120 can be machined by considering both a vehicle design specification and installability.

[0033] In this case, the teeth of a rotating contact surface of the first transmission gear 120 may be formed to be inclined with respect to a transmission shaft at predetermined intervals so that the first transmission gear 120 engages with the drive gear 110.

[0034] In addition, the diameter of the pitch circle of the first transmission gear 120 may be formed to decrease from the edges of both sides toward the center of the thickness, so that the first transmission gear 120 closely surrounds a part of the circumferential contact surface of the drive gear 110, and as the contact area between the drive gear 110 and the first transmission gear 120 increases, the contact ratio increases.

[0035] The second helical gear member 200 may include a second transmission gear 210 on the other side of the transmission shaft 50 and a driven gear 220 on the wheel cylinder 30 that meshes with the second transmission gear 210.

[0036] When the transmission shaft 50 rotates, the driven gear 220, which is connected to the second transmission gear 210 on the other side of the transmission shaft 50, rotates together. The driven gear 220 may be formed integrally with the wheel cylinder 30.

[0037] That is, in a method in which the rotational drive power of the drive motor 40 is transmitted to the wheel cylinder 30 via the transmission shaft 50, since the rotational movement is kept unchanged, the transmission efficiency of the drive power can be improved and also the noise can be reduced.

[0038] In this case, since the second transmission gear 210 rotates with the first transmission gear 120 in a state where the second transmission gear 210 is fixed to the transmission shaft 50, the first transmission gear 120 and the second transmission gear 210 share the rotation axis 50a.

[0039] A second angle b may be formed between the rotational axis 50a of the second transmission gear 210 and a rotational axis 30a of the wheel cylinder 30. That is, the drive power transmitted via the transmission shaft 50 is changed by the second angle b and transmitted to the wheel cylinder 30. Furthermore, if the second angle b is set to meet a design specification, the installability of the drive motor 40 and the wheel cylinder 30 can be improved.

[0040] As described above, the driven gear 220 can also be manufactured by enveloping machining. That is, when a tooth shape of the second transmission gear 210 provided on the transmission shaft 50 is determined, a tooth shape of the driven gear 220 can be machined by enveloping machining. In this case, the tooth shape of the driven gear 220 can be machined taking into account both a vehicle design specification and installability.

[0041] Moreover, as described above, teeth of a circumferential contact surface of the driven gear 220 may also be formed to be inclined with respect to a transmission shaft at predetermined intervals so that the driven gear 220 meshes with the second transmission gear 210, and in addition, a diameter of a pitch circle of the driven gear 220 is also formed to decrease in a direction from the edges of both sides to a center of a thickness so that the second transmission gear 210 closely surrounds a part of the circumferential contact surface of the driven gear 220, a contact area between the second transmission gear 210 and the driven gear 220 increases, and thus a contact ratio can increase.

[0042] Accordingly, in the electronic parking brake, when the driving force of the drive motor 40 is transmitted to the wheel cylinder 30, the use of a gear with a helical gear structure can reduce noise and improve user satisfaction. Since the inclination between the drive motor 40, the transmission shaft 50, and the wheel cylinder 30 can be varied in various ways to meet a design specification with the first and second helical gear elements 100 and 200, a certain degree of design freedom and installation capability can be improved.

[0043] The first angle a and the second angle b can be determined in consideration of a design specification in a vehicle assembly process, and the first angle a and the second angle b can also be adjusted according to a parking state (flat / sloped ground surface) of the vehicle.

[0044] Alternatively, the driven gear 220 may be rotated by the driving force transmitted via the transmission shaft 50, and the facing brake shoes 20 may be controlled to come into contact with the inner peripheral surface of the drum 10 or to be separated from the inner peripheral surface of the drum 10 depending on the rotation direction of the driven gear 220.

[0045] That is, when the driven gear 220 rotates in one direction, the distance between the two ends of the wheel cylinder 30 increases and the brake shoes 20 facing each other are pushed so that the brake shoes 20 come into contact with the inner peripheral surface of the drum 10 and braking can be performed, and when the driven gear 220 rotates in the other direction, the distance between the two ends of the wheel cylinder 30 decreases and the brake shoes 20 facing each other are pulled so that the brake shoes 20 are separated from the inner peripheral surface of the drum 10 and braking force is released.

[0046] In addition, the housing is 300, as in Fig. 5, provided outside the actuator, and the housing 300 may include a first housing 310 surrounding the drive motor 40 and one side of the transmission shaft 50, and a second housing 320 surrounding the wheel cylinder 30 of the other side of the transmission shaft 50.

[0047] That is, as described above, the transmission shaft 50 may include the first shaft 51 connected to the drive motor 40 and the second shaft 52 connected to the wheel cylinder 30, wherein the drive motor 40 and the first shaft 51 are housed in the first housing 310, and the wheel cylinder 30 and the second shaft 52 are housed in the second housing 320. Therefore, when the drive motor 40 and the wheel cylinder 30 are installed on the support plate 60, and the first housing 310 and the second housing 320 are easily installed, since the first shaft 51 and the second shaft 52 are coupled to each other to form the transmission shaft 50, the transmission shaft 50 does not need to be additionally installed, and thus an actuator assembly process can be simplified.

[0048] As in the Fig. 2 and Fig. 5, a through-hole 321 may be formed in the second housing 320, which is installed to pass through the support plate 60. A through-hole through which the through-hole 321 can pass may be formed in the support plate 60, and since the through-hole 321 of the second housing 320 is configured to be fixed in a state where the through-hole 321 passes through the support plate 60, the wheel cylinder 30 can be installed in a regular position, and thus, the ease of assembly can also be improved.

[0049] In addition, as described in the Fig. 2 and Fig.5, a coupling part 311 coupled to the passage part 321 of the second housing 320 may be formed in the first housing 310. As described above, the first shaft 51 and the second shaft 52 constituting the transmission shaft 50 are coupled to each other in a process in which the first housing 310 and the second housing 320 are installed on the support plate 60, and therefore, it is important to couple the first shaft 51 and the second shaft 52 so that the first shaft 51 and the second shaft 52 share the rotation axis 50a in order to maintain durability and prevent noise.

[0050] When the coupling part 311 on the first housing 310 is shaped to match the through part 321 of the second housing 320, not only can the assembling ease be improved, but also the first shaft 51 and the second shaft 52 can be positioned at regular positions to share the rotation axis 50a.

[0051] Although the embodiments of the present invention have been described above, the spirit of the present invention is not limited to the embodiments proposed in this description, and by adding, changing and omitting components, other embodiments can be easily proposed by a person skilled in the art which are within the spirit of the present invention.

Claims

[1] Electronic parking brake, comprising: a drum (10) rotating with a wheel of a vehicle; brake shoes (20) mounted on two sides in the drum (10) to brake the drum (10); a wheel cylinder (30) configured to press the brake shoes (20) to bring the brake shoes (20) into contact with an inner peripheral surface of the drum (10); and an actuator which generates the drive power for driving the wheel cylinder (30), wherein the actuator comprises a drive motor (40) which generates the drive power for braking the drum (10), and a transmission shaft (50) which transmits the drive power of the drive motor (40) to the wheel cylinder (30), and the electronic parking brake further comprises a first helical gear element (100) which transmits the drive power of the drive motor (40) to the transmission shaft (50), and a second helical gear element (200) which transmits the drive power transmitted via the transmission shaft (50) to the wheel cylinder (30). wherein a drive shaft (41) of the drive motor (40) and a rotary shaft of the wheel cylinder (30) are inclined to each other, wherein a housing (300) is provided on the outside of the actuator; and the housing (300) comprises a first housing (310) surrounding the drive motor (40) and one side of the transmission shaft (50), and a second housing (320) surrounding the wheel cylinder (30) and the other side of the transmission shaft (50), wherein the transmission shaft (50) comprises a first shaft (51) housed in the first housing (310) and connected to the drive motor (40), and a second shaft (52) housed in the second housing (320) and connected to the wheel cylinder (30), wherein the second shaft (52) is connected to the first shaft (51) when the first housing (310) and the second housing (320) are installed on a support plate (60). [2] Electronic parking brake according to claim 1, wherein the first helical gear element (100) comprises: a drive gear (110) provided on the drive shaft (41) of the drive motor (40); and a first transmission gear (120) provided on one side of the transmission shaft (50) and meshing with the drive gear (110). [3] Electronic parking brake according to claim 2, wherein a first angle (a) is formed between a rotational axis (40a) of the drive gear (110) and a rotational axis (50a) of the first transmission gear (120). [4] Electronic parking brake according to claim 1, wherein the second helical gear element (200) comprises: a second transmission gear (210) provided on the other side of the transmission shaft (50); and a driven gear (220) provided on the wheel cylinder (30) and meshing with the second transmission gear (210). [5] Electronic parking brake according to claim 4, wherein a second angle (b) is formed between a rotational axis (50a) of the second transmission gear (210) and a rotational axis (30a) of the driven gear (220). [6] Electronic parking brake according to claim 4, wherein: the driven gear (220) is rotated by the drive power transmitted via the transmission shaft (50); and the mutually facing brake shoes (20) are controlled so that they come into contact with the inner peripheral surface of the drum (10) or are separated from the inner peripheral surface of the drum (10) according to the direction of rotation of the driven gear (220). [7] Electronic parking brake according to claim 1, wherein a through-part (321) mounted through a support plate (60) is formed in the second housing (320). [8] Electronic parking brake according to claim 7, wherein a coupling part (311) is formed in the first housing (310) which is correspondingly coupled to the passage part (321).

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