ELECTRONIC PARKING BRAKE DEVICE

Abstract

An electronic parking brake may comprise: a gear unit driven by an actuator; a rotary rod connected to the gear unit; a push rod designed to apply pressure to one or more brake shoes while moving in conjunction with the push rod; a coupling unit arranged to interfere with a line of motion of the gear unit and designed to apply a rotational load to the gear unit while in contact with the gear unit when the gear unit is rotated at a preset angle; and a control device designed to control the operation of the actuator according to the load applied to the actuator.

Description

CROSS-REFERENCES TO RELATED APPLICATIONS BACKGROUND AREA

[0001] The present invention relates to an electronic parking brake device and, more particularly, to an electronic parking brake device for braking a parked vehicle using an actuator. DISCUSSION OF THE BACKGROUND

[0002] Generally, a drum brake refers to a device that generates braking force through friction by means of a drum rotating together with a wheel. Specifically, the drum brake generates braking force through hydraulic pressure (normal braking), or it generates braking force by rubbing a brake shoe provided with friction material against a drum via a line connected to a parking brake lever (parking braking). The conventional drum brake comprises: the drum, a pair of brake shoes arranged on a back plate so as to face the inner peripheral surface of the drum and provided with a friction material on their outer peripheral surface, and a wheel brake cylinder provided for normal braking, which receives braking hydraulic pressure to move the brake shoes outward.Furthermore, a parking brake operating lever installed on the drum brake is axially connected to the brake shoes at one end and connected via a cable at the other end to the parking brake lever installed next to the driver's seat. When the driver pulls the parking brake lever, the parking brake operation is mechanically applied.

[0003] An adjuster for compensating a gap between the drum and the friction material is arranged between the pair of brake shoes. The adjuster has a structure in which a male push rod, a female push rod, and an adjusting nut are assembled. When the adjusting nut is rotated, the length of the adjuster increases to compensate for the widened gap between the friction material and the drum. To implement the operation of the adjuster, the operating lever for a parking brake must be connected to the adjuster, a lever slide, one end of which engages the outer side of the adjusting nut, must be rotatably installed in the brake shoe, and a tension spring must be installed between the lever slide and the bottom of the brake shoe.

[0004] The prior art is described in Korean patent application KR 10 1 272 497 B1, filed on June 3, 2013, entitled "Adjust Assembly of Drum Brake," and discloses an electronic parking brake comprising an actuator configured to drive a gear unit; a torque rod connected to the gear unit; and a push rod configured to apply pressure to one or more brake shoes while being moved in conjunction with the torque rod.

[0005] In the prior art, a plurality of parts, such as the adjuster comprising the male push rod, the female push rod, and the adjusting nut, the lever slide, and the tension spring, must be provided to implement the adjusting function for compensating for wear of the friction material. Furthermore, a cumbersome process for assembling the plurality of parts to set positions must be performed to implement the adjusting function in conjunction with changes in the moving lines of the brake shoes and the operating lever for a parking brake. Furthermore, since the gap compensation is performed based on the thread of the adjusting nut, the accuracy is inevitably low, and an operation for reducing the length of the adjuster cannot be performed, making it difficult to efficiently handle the thermal expansion of the drum.

[0006] There is therefore a need for a structure capable of solving these problems. OVERVIEW OF THE INVENTION

[0007] Embodiments of the present invention relate to an electronic parking brake device that can be manufactured with a simple structure, in which an adjusting function for constantly maintaining a gap between a drum and a friction material can be implemented with greater accuracy, and thermal expansion of a drum can be efficiently handled.

[0008] In one embodiment, an electronic parking brake may include: an actuator configured to drive a gear unit; a rotating rod connected to the gear unit; a push rod unit configured to apply pressure to one or more brake shoes while being moved in conjunction with the rotating rod; a clutch unit arranged to interfere with a line of movement of the gear unit and configured to apply a rotational load to the gear unit while abutting against the gear unit when the gear unit is rotated at a preset angle; and a controller for controlling an operation of the actuator in accordance with the load applied to the actuator.

[0009] The gear unit may include: a drive gear rotated by power obtained from the actuator; and a driven gear meshed with the drive gear and rotated, reducing a rotational speed of the drive gear.

[0010] The driven gear may include: a rod connecting part to which the rotating rod is attached; a guide groove formed on an inner peripheral surface of the rod connecting part and extending in a direction of a rotation axis; and a clutch connecting part abutting against the clutch unit.

[0011] The rotating rod may include: a gear arranging part installed through the rod connecting part; and a screw extending part formed coaxially with the gear arranging part and having a screw connected to the push rod unit.

[0012] The gear assembly part may include: a central shaft having a diameter corresponding to the rod connecting part; and a guide projection formed on an outer surface of the gear assembly part and sliding along the guide groove in an axial direction of the driven gear.

[0013] The screw extension part may include: a first extension portion formed at one end of the central shaft, in which the screw is formed on an outer surface of the first extension portion, the screw being connected to the push rod unit; and a second extension portion formed at the other end of the central shaft, in which a contact stabilizer is formed at one end of the second extension portion.

[0014] The rotating rod may further comprise a thrust extending part connected to the gear arrangement part on an opposite side of the screw extending part and configured to transmit a sliding displacement of the gear arrangement part to the thrust rod unit.

[0015] The push rod unit may include: a moving push rod abutting a brake shoe of a pair of the one or more brake shoes, screwed to the screw extension part, and moved along the screw extension part while cooperating with the rotation of the screw extension part; and a bracing push rod abutting another brake shoe of the pair of the one or more brake shoes, connected to the push extension part, and pushed and moved by the push extension part when the moving push rod is moved.

[0016] The clutch unit may include: a clutch base portion arranged coaxially with the driven gear; a gear locking portion formed in the shape of a protrusion on the clutch base portion and arranged at a preset angle to the clutch connecting portion; and a rotational load member configured to press the clutch base portion to apply a load to the driven gear while the clutch connecting portion is locked to the gear locking portion.

[0017] The rotational load member may include: a first contact part disposed on one side of the clutch base part and abutting against the clutch base part; a second contact part facing the first contact part with the clutch base part interposed therebetween; and an elastic pressurizing member disposed between the clutch base part and the second contact part and elastically pressurizing the clutch base part.

[0018] The controller may drive the actuator in a forward direction when the electronic parking brake device is applied, and stop the operation of the actuator when a preset amount of current is applied to the actuator while a brake shoe of the one or more brake shoes is applying pressure to a drum.

[0019] The controller may drive the actuator in a reverse direction when the electronic parking brake device is released, and stop the operation of the actuator when a current applied to the actuator increases while a load is applied from the clutch unit to the transmission unit.

[0020] In one embodiment of the present invention, when the parking brake is released, a load can be applied to the clutch unit from the gear unit, which is rotated at the preset angle, and the control device can control the operation of the actuator according to the load such that the gap between the brake shoe and the drum is constantly maintained at a distance corresponding to the preset angle. This means that the adjustment function can be implemented.

[0021] Furthermore, the electronic parking brake according to the embodiment of the present invention can be manufactured with a simple structure in which the gear unit, the torsion bar, the push rod, and the clutch unit are coaxially connected and fixed to a housing. Therefore, unlike an existing device, the electronic parking brake does not need to include a plurality of parts such as an adjuster, a lever slide, and a tension spring, the adjuster comprising a male push rod, a female push rod, and an adjusting nut. Furthermore, the electronic parking brake device can eliminate a cumbersome process of assembling the parts in preset positions to implement the adjusting function in conjunction with changes in the moving lines of the brake shoes and the parking brake operating lever.

[0022] Furthermore, since the gap between the brake shoe and the drum is correctly maintained as a distance corresponding to the preset angle, the extension of the gap to the drum can be linearly compensated according to the wear of the friction material, thereby making it possible to prevent deterioration of the adjustment accuracy that occurs in the existing device when performing the gap compensation based on a thread.

[0023] Furthermore, in the electronic parking brake according to the embodiment of the present invention, not only can the extension of the gap to the drum due to the wear of the friction material be compensated, but also the reduction of the gap to the drum can be flexibly compensated, thereby making it possible to solve the problems encountered in the existing device in which the thermal expansion of the drum could not be handled efficiently because an operation for reducing the length of the adjuster could not be implemented in the existing device. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a front view schematically showing that an electronic parking brake device according to an embodiment of the present invention is installed. Fig. 2 is a perspective view showing a section A of Fig. 1. Fig. 3 is a cross-sectional view of main parts of Fig. 2. Fig. 4 is a perspective view schematically showing main parts of the electronic parking brake device according to the embodiment of the present invention. Fig. 5 is an exploded perspective view showing the main parts of the electronic parking brake according to the embodiment of the present invention. Fig. 6 is a perspective view schematically illustrating a driven gear and a clutch unit of the electronic parking brake according to the embodiment of the present invention. Fig. 7 is a schematic diagram for describing the length extension of the electronic parking brake device according to the embodiment of the present invention when the brake is applied. Fig. 8 is a schematic diagram for describing the position adjustment of the electronic parking brake device according to the embodiment of the present invention when the brake is applied. Fig. 9A and Fig. 9B are schematic diagrams for describing a process in which a load of the clutch unit is transmitted to the driven gear of the electronic parking brake device according to the embodiment of the present invention when the brake is released. Fig. 10 is a schematic diagram for describing an adjustment gap in the electronic parking brake device according to the embodiment of the present invention when the brake is released. Fig. 11 is a front view schematically showing that an electronic parking brake device according to another embodiment of the present invention is installed. DESCRIPTION OF SPECIFIC EMBODIMENTS

[0024] An electronic parking brake device according to an embodiment of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that the drawings are not precisely to scale and may be exaggerated in line thickness or component size for the sake of clarity and descriptiveness. Furthermore, the terms used herein are selected with the functions of the invention in mind and may be changed according to the custom or intention of users or operators. Thus, the definitions of the terms should be understood in accordance with the entirety of the disclosures contained herein.

[0025] Fig. 1 is a front view schematically showing that an electronic parking brake device according to an embodiment of the present invention is installed, Fig. 2 is a perspective view showing a section A of Fig. 1, and Fig. 3 is a cross-sectional view of main parts of Fig. 2.

[0026] According to Fig. 1 to 3, the electronic parking brake device 1 according to the embodiment of the present invention may include an actuator 100, a gear unit 200, a rotating rod 300, a push rod unit 400, a clutch unit 500, a controller 600, and a housing 700.

[0027] The gear unit 200, which has a reduction gear structure, may be connected to an output shaft of an actuator 100. The rotating rod 300 may be rod-shaped and coaxially connected to the driven gear 220 of the gear unit 200. The pair of push rod units 400 may be connected to both ends of the rotating rod 300 and apply pressure to brake shoes 2 toward a drum 4 while being moved in conjunction with the rotation of the rotating rod 300 in an extending direction of the rotating rod 300. When the rotating rod 300 is rotated in the forward direction, the pair of push rod units 400 can apply pressure to the brake shoes 2 while being moved away from each other in a direction, and when the rotating rod 300 is rotated in the reverse direction, the pair of push rod units 400 can release the pressure applied to the brake shoes 2 while being moved toward each other in a direction.

[0028] The clutch unit 500 may be arranged such that it interferes with a line of movement of the gear unit 200. When the gear unit 200 is rotated at a preset or larger angle α° (see Fig. 9A and Fig. 9B), the clutch unit 500 may apply a rotational load to the gear unit 200 while contacting the gear unit 200. The rotational load may indicate a factor that prevents the gear unit 200 from rotating smoothly, thus increasing the load applied to the gear unit 200 or a current applied to the actuator 100. The controller 600 may maintain or stop the operation of the actuator 100 according to the load applied to the actuator 100.

[0029] According to Fig. 2 and Fig. 3, the gear unit 200 according to the embodiment of the present invention may include a drive gear 210 and a driven gear 220 having a worm gear structure. The drive gear 210 may be connected to the output shaft of the actuator 100 and may have a worm gear structure. The drive gear 210 may be rotated by power obtained from the actuator 100. Here, a motor may be used as the actuator 100. The driven gear 220, which serves to finally transmit the rotation of the actuator 100 to the rotating rod 300, may be configured to have a worm gear structure to mesh with the drive gear 210. The driven gear 220 may mesh with the drive gear 210 and be rotated in a constant position while reducing its speed.

[0030] Fig. 4 is a perspective view schematically showing the main parts of the electronic parking brake device according to the embodiment of the present invention, Fig. 5 is an exploded perspective view showing the main parts of the electronic parking brake according to the embodiment of the present invention, and Fig. 6 is a perspective view schematically illustrating the driven gear and the clutch unit of the electronic parking brake according to the embodiment of the present invention.

[0031] According to Fig. 4 to 6, the driven gear 220 according to the embodiment of the present invention may include a rod connecting part 221, a guide groove 222, and a clutch connecting part 223.

[0032] The rod connecting part 221, to which the rotating rod 300 is attached, may be formed from a section along the rotation axis corresponding to the rotation axis of the driven gear 220. The rotating rod 300 may be attached through the rod connecting part 221 and thus be joined to the driven gear 220. The guide groove 222 may be recessed on the inner peripheral surface of the rod connecting part 221. If the guide groove 222 is formed in the form of a recess, this may indicate that the rod connecting part 221 does not have a smooth circular inner peripheral surface, i.e., a circular cross-section.

[0033] That is, the guide groove 222 serves to expand the diameter of the rod connecting part 221 based on the minimum diameter of the rod connecting part 221. One or more guide grooves 222 may be formed on the rod connecting part 221, which has a circular cross-section, and the one or more guide grooves 222 and the rod connecting part 221 may have a polygonal cross-section, for example, a star-shaped cross-section. The guide grooves 222 may extend along the rotation axis of the driven gear 220 to guide a rectilinear movement of a guide projection 312 formed on the rotating rod 300.

[0034] The clutch connecting part 223, which abuts the clutch unit 500, may be formed at an end of the driven gear 220 facing the clutch unit 500 and protrude toward the clutch unit 500. When the driven gear 220 is rotated, the clutch connecting part 223 may be rotated, forming a circular movement line around the rotation axis of the driven gear 220. At an end of the clutch unit 500 facing the driven gear 220, a gear locking part 512 may be formed in the shape of a protrusion and have a movement line that overlaps the clutch connecting part 223. When the driven gear 220 is rotated, the clutch connecting part 223 may be moved to come into contact with the gear locking part 512.Then, when the rotation direction is maintained constant, the clutch connecting part 223 and the gear locking part 512 can be moved together by the same displacement amount while maintaining the contact state therebetween (see . Fig. 9A and Fig. 9B).

[0035] According to Fig. 4 and Fig. 5, the rotating rod 300 according to the embodiment of the present invention may have a rod shape in which a screw extending part 320, a gear arrangement part 310, and a thrust extending part 330 are successively connected.

[0036] The gear assembly part 310 may be installed through the rod connecting part 221 of the driven gear 220. The gear assembly part 310 according to the embodiment of the present invention may include a central shaft 311 and a guide projection 312. The central shaft 311, having a diameter corresponding to the rod connecting part 221, may be attached to the rod connecting part 221. The guide projection 312 may be formed on the outer surface of the gear assembly part 310 and inserted into the guide groove 222 so as to slide along the guide groove 222 in the axial direction of the driven gear 220, that is, the extending direction of the rotating rod 300.

[0037] When the guide protrusion 312 is retained in the guide groove 222, the gear assembly part 310 can only move in the axial direction of the driven gear 220, and can be reliably prevented from moving or rotating in any other direction. Due to the guide groove 222 and the guide protrusion 312, the driven gear 220 and the rotating rod 300 can always have the same rotational displacement, and the rotational force of the driven gear 220 can be stably transmitted to the rotating rod 300.

[0038] The screw extension part 320 may be formed continuously at one end of the gear assembly part 310 exposed to the outside of the driven gear 220. The screw extension part 320 may be formed coaxially with the gear assembly part 310. The screw extension part 320 according to the embodiment of the present invention may include a first extension portion 321 and a screw 322.

[0039] The first extension portion 321 may be formed at an end of the central shaft 311 exposed to the outside of the driven gear 220 and may have a constant diameter. The screw 322 may be formed on the outer surface of the first extension portion 321 so as to be screwed to the push rod unit 400. By adjusting the front part of the screw 322, it is possible to adjust a linear displacement with respect to the rotational displacement of the driven gear 220. For example, assume that the front part of the screw 322 is 4 mm. In this case, when the driven gear 220 and the rotation rod 300 are rotated once, the push rod unit 400 meshes with the screw 322, that is, the moving push rod 410 can be moved linearly by 4 mm along the screw extension portion 320.When the driven gear 220 and the rotating rod 300 are rotated by 90°, the moving push rod 410 can be moved by 1 mm.

[0040] The thrust extension part 330 may be formed continuously at the other end of the gear assembly part 310, which is exposed to the outside of the driven gear 220. The thrust extension part 330 may be formed on the opposite side of the screw extension part 320 so as to be coaxial with the gear assembly part 310. Thus, the screw extension part 320, the gear assembly part 310, and the thrust extension part 330 may form a straight rod shape. The thrust extension part 330 according to the embodiment of the present invention may include a second extension portion 331 and a contact stabilizer 332.

[0041] The second extension portion 331 may be formed at the other end of the central shaft 311, which is exposed to the outside of the driven gear 220, and may have a constant diameter. The contact stabilizer 332, which has a smaller diameter than the second extension portion 331, may be formed at one end of the second extension portion 331. The contact stabilizer 332 may have a diameter that gradually decreases toward the end of the second extension portion 331.

[0042] When the gear assembly part 310 slides, the entire rotating rod 300 can be moved together with the gear assembly part 310. At this time, the thrust extension part 330 can transmit the sliding displacement of the gear assembly part 310 to the push rod unit 400, or specifically, a bracing push rod 420. Contact with the bracing push rod 420 without a gap can be reliably achieved by the contact stabilizer 332. Therefore, the sliding displacement of the rotating rod 300 can be stably transmitted to the bracing push rod 420.

[0043] According to Fig. 1 and Fig. 2, the push rod unit 400 according to the embodiment of the present invention may include a moving push rod 410 and the bracing push rod 420.

[0044] In Fig. 1 and Fig. 2, the moving push rod 410 can be positioned between the pair of left and right brake shoes 2 and can be abutted against the left brake shoe 2 and screwed to the screw extension part 320 of the rotating rod 300. Thus, when the screw extension part 320 is rotated, the moving push rod 410 can be moved along the screw extension part 320 in conjunction with the rotation of the screw extension part 320. According to Fig. 4, the moving push rod 410 according to the embodiment of the present invention may include a first extending rod 411, a nut-fitted bolt 412, and a first brake shoe connection 413.

[0045] The first extending rod 411 may be arranged between the left brake shoe 2 and the driven gear 220 and extend along the screw extending part 320. The nut-equipped screw 412 may be formed in a hollow shape at the right end of the first extending rod 411 and have an internal screw thread formed on its inner surface, the internal screw thread corresponding to the screw 322. The first brake shoe connection 413 may be formed at the left end of the first extending rod 411 and have a slotted shape into which the brake shoe 2 can be inserted. The first brake shoe connection 413 can maintain the connection with the brake shoe 2 and restrict movement or rotation in any direction except the extending direction of the rotating rod 300.

[0046] In Fig. 1 and Fig. 2, the bracing push rod 420 can be positioned between the pair of left and right brake shoes 2 and can be connected to the right brake shoe 2 and to the push extension part 330 of the rotating rod 300. Thus, when the moving push rod 410 is moved, the bracing push rod 420 can be pushed and moved by the push extension part 330. Such a process will be described in more detail below. According to Fig. 4, the tension push rod 420 according to the embodiment of the present invention may include a second extending rod 421, a rod cover 422, and a second brake shoe connection 423.

[0047] The second extending rod 421 may be disposed between the right brake shoe 2 and the driven gear 220 and extend along the thrust extending part 330. The rod cover 422 may be formed in a hollow shape at the left end of the second extending rod 421, and the thrust extending part 330 may be fitted to the rod cover 422. The rod cover 422 may be connected to the thrust extending part 330 while covering the thrust extending part 330. Thus, while the thrust extending part 330 is moved, the connection with the thrust extending part 330 may be maintained. The second brake shoe connection 423 may be formed at the right end of the second extending rod 421 and have a slotted shape into which the brake shoe 2 can be inserted.The second brake shoe connection 423 can maintain the connection between the brake shoe 2 and the second extending rod 421 and restrict movement or rotation in any direction except the extending direction of the rotating rod 300.

[0048] Fig. Fig. 7 is a schematic diagram for describing the length extension of the electronic parking brake device according to the embodiment of the present invention when the brake is applied, and Fig. 8 is a schematic diagram for describing the position adjustment of the electronic parking brake device according to the embodiment of the present invention when the brake is applied.

[0049] According to Fig. 7, a distance from the driven gear 220 to the end of the moving push rod 410 and a distance from the driven gear 220 to the end of the bracing push rod 420 can become L1 when the end of the screw extension part 320 is located at P1. When the brake is applied, the actuator 100 can be driven in the forward direction. In this case, the driven gear 220 can be rotated in the direction shown in Fig. 7, cooperating with the operation of the actuator 100, and the rotating rod 300 can also be rotated by the same angular displacement as the driven gear 220.

[0050] When the rotating rod 300 is rotated in the forward direction, the moving push rod 410 can be moved by a distance corresponding to L2 toward the end of the screw extension part 320, ie in Fig. 7 to the left, and the end of the screw extension part 320 can be located at P2. When a load caused by contact with the brake shoe 2 is removed, such a process can lengthen the distance from the driven gear 220 to the end of the moving push rod 410 to L1+L2.

[0051] According to the Fig. In the state illustrated in Figure 7, the moving push rod 410 may have a distance to the driven gear 220 corresponding to L1+L2, and the tensioning push rod 420 may have a distance from the driven gear 220 corresponding to L1. In this case, a braking force only needs to be concentrated on one brake shoe of the pair of brake shoes 2. In reality, as shown in Fig. 1 and Fig. 2, the ends of the moving push rod 410 and the tensioning push rod 420 are continuously restricted by the pair of brake shoes 2, respectively, and return springs 7 can continuously apply a compressive force in such a direction to the pair of brake shoes 2 that the ends of the pair of brake shoes 2 approach each other. Therefore, the moving push rod 410 and the tensioning push rod 420 can be operated as shown in Fig. 8 is shown.

[0052] Fig. Fig. 8 illustrates an actual case in which a load caused by contact with the pair of left and right brake shoes 2 is considered. While the moving push rod 410 is moved to the left by L2 along the screw extension part 320 as shown in Fig. As shown in Figure 7, the leftward movement may be restricted by the brake shoe 2, so that both the rotating rod 300 and the push rod assembly 400 naturally slide to the right by a distance corresponding to L2 / 2. Therefore, the moving push rod 410 and the bracing push rod 420 can be moved outwardly to the left and right by the same displacement corresponding to L2 / 2 based on the driven gear 220, thereby applying the same force to the pair of left and right brake shoes 2.

[0053] The sliding of the rotating rod 300 can be stably performed by the rod connecting part 221 and the guide groove 222 formed in the driven gear 220, and the central shaft 311 and the guide projection 312 of the gear assembly part 310. When the brake is released, the actuator 100 can be driven in the reverse direction. At this time, while the driven gear 220 and the rotating rod 300 are rotated in the reverse direction, the moving push rod 410 and the tension push rod 420 based on the driving gear 220 can be moved by the same displacement through the process described above, thereby releasing the pressure applied to the brake shoes 2.

[0054] In the embodiment of the present invention, the rotating rod 300 may include the screw extending part 320 and the thrust extending part 330, and the thrust rod unit 400 may include the moving thrust rod 410 and the bracing thrust rod 420. However, the rotating rod 300 and the thrust rod unit 400 are not limited to this, as long as an adjustment function can be implemented by the coupling unit 500. For example, as shown in Fig. 11, the present invention may be embodied in another manner in which the rotating rod 300 includes a pair of screw extending portions 320 without the thrust extending portion 330, and the thrust rod unit 400 includes a pair of moving thrust rods 410 without the tensioning thrust rod 420.

[0055] According to Fig. 4 to 6, the clutch unit 500 according to the embodiment of the present invention may include a clutch ring 510 and a rotational load element 520.

[0056] The coupling ring 510 can serve to transmit a load to the driven gear 220, wherein it comes into contact with the driven gear 220, and has a coupling base part 511 and the gear locking part 512. The coupling base part 511 in the form of a flat ring can be placed on the circumference of the rotating rod 300 and thus arranged coaxially with the driven gear 220. The gear locking part 512 can be formed on the coupling base part 511 such that it protrudes toward the driven gear 220 and is arranged at a preset angle α° to the coupling connecting part 223 of the driven gear 220 (see Fig. 9A and Fig. 9B).

[0057] The rotational load element 520 may serve to pressurize the clutch ring 510 to prevent smooth rotation of the clutch ring 510 and may include a first clutch housing 521, a second clutch housing 523, an elastic pressurizing element 525, a first plate 526, and a second plate 527.

[0058] The first and second clutch housings 521 and 523 can serve to hold the clutch ring 510, the elastic pressurizing element 525, the first plate 526, and the second plate 527 in the correct positions. The first and second clutch housings 521 and 523 can be arranged on the periphery of the driven gear 220, the push rod unit 400, and the rotating rod 300, covering the clutch ring 510, the elastic pressurizing element 525, the first plate 526, and the second plate 527.

[0059] The first clutch housing 521 may be connected to the periphery of the driven gear 220, and the clutch ring 510, the elastic pressurizing member 525, the first plate 526, and the second plate 527 may be housed in the first clutch housing 521. The first clutch housing 521 may have a first contact part 522 formed at the contact point with the clutch base part 511. The second clutch housing 523 may be connected to the periphery of the push rod unit 400 and connected to the first clutch housing 521, with one end portion thereof inserted into the first clutch housing 521. The end portion inserted into the first clutch housing 521 may face the first contact part 522 and abut against the elastic pressurizing member 525 or the second plate 527.

[0060] The elastic pressurizing element 525 may serve to elastically pressurize the coupling base part 511 and may be arranged between the coupling base part 511 and a second contact part 524. As the elastic force of the elastic pressurizing element 525 increases, a torsional load applied to the coupling ring 510 may increase. A disc spring may be used as the elastic pressurizing element 525, and the number of elastic pressurizing elements 525 or the material or degree of bending of the elastic pressurizing element 525 may vary depending on the magnitude of the load to be applied.

[0061] The first plate 526 in the form of a flat ring can be arranged between the coupling ring 510 and the elastic pressurizing element 525. The elastic force of the elastic pressurizing element 525 can be evenly distributed by the first plate 526 and transmitted to the coupling ring 510. The second plate 527 in the form of a flat ring can be arranged between the elastic pressurizing element 525 and the second contact part 524. The elastic force of the elastic pressurizing element 525 can be evenly distributed by the second plate 527 and transmitted to the second clutch housing 523. The second plate 525 can prevent uneven contact between the elastic pressurizing element 525 and the second clutch housing 523, thereby smoothly generating a target load size without peaks and valleys.

[0062] When the clutch ring 510 is rotated, the clutch base portion 511 can be rotated with both surfaces coming into contact with the first contact portion 522 and the first plate 526. Therefore, when the clutch ring 510 is rotated, a load corresponding to a frictional force with the first contact portion 522 and the first plate 526 can be applied to the clutch base portion 511. When the driven gear 220 is to rotate continuously with the clutch connecting portion 223 brought into contact with the gear locking portion 512, or when the clutch ring 510 is pulled, such a load can also be transmitted to the driven gear 220.

[0063] Fig. 9A and Fig. 9B are schematic diagrams for describing a process in which a load of the clutch unit is transmitted to the driven gear of the electronic parking brake device according to the embodiment of the present invention when the brake is released, and Fig. 10 is a schematic diagram for describing an adjustment gap in the electronic parking brake device according to the embodiment of the present invention when the brake is released.

[0064] According to Fig. 9A and Fig. 9B, the clutch connecting part 223 and the gear locking part 512 can be arranged with a preset angle α° between them. When the driven gear 220 is rotated by the preset angle α° in a Fig. 9A, the clutch connecting part 223 can abut the gear locking part 512, as shown in Fig. 9B. In this state, when the driven gear 220 is continuously rotated, a load of the clutch ring 510 can be transmitted and applied to the driven gear. Furthermore, the load can also be transmitted to and applied to the actuator 100 that drives the driven gear 220, thus increasing the current applied to the actuator 100.

[0065] The current rise can be achieved in various ways depending on the device specifications or the load intensity. For example, the current can vary from a state where no load is applied to a state where a load is applied, be increased rapidly, be increased gradually when the clutch connection part 223 and the gear locking part 512 are in contact with each other, or be maintained constant after being slightly increased. Therefore, the current rise standard can be properly set depending on a product to which the present invention is applied.

[0066] The controller 600 can drive the actuator 100 in the forward direction when the parking brake is applied, and stop the operation of the actuator 100 when a preset amount of current is applied to the actuator 100 while the brake shoe 2 is pressing the drum 4. The current applied to the actuator 100 can be increased in proportion to the pressurizing force for pressurizing the brake shoe 2. Thus, a parking brake operation can be performed by the operation of the controller 600. Specifically, the actuator 100 can be driven in the forward direction to pressurize the brake shoes 2 toward the drum 4 with the preset force, and the operation of the actuator 100 in the forward direction can be stopped to maintain the pressurizing state.The driven gear 220, the rotating rod 300 and the push rod unit 400 can be actuated as shown in . Fig. 8 is shown.

[0067] When the parking brake is applied, the driven gear 220 can rotate continuously in the forward direction (the counterclockwise direction in Fig. 9A) with the clutch connecting part 223 and the gear locking part 512 abutting against each other, as shown in Fig. 9A, that is, the load from the clutch unit 500 is increased. At this time, the load caused by the clutch unit 500 may be lower than the load caused by applying the preset force to the brake shoes 2 and may not serve as an obstruction factor when applying a braking force to the brake shoes 2.

[0068] According to Fig. 7, when the parking brake is applied, the brake shoe 2 can be brought into contact with the drum 4, and the distance between the moving push rod 410 and the tension push rod 420 is increased by L2. For example, if the driven gear 220 and the rotating rod 300 are rotated once, assuming that the front part of the screw 322 is 4 mm, the moving push rod 410 can be moved rectilinearly by 4 mm along the screw extension part 320. If the driven gear 220 and the rotating rod 300 are rotated once until the brake shoe 2 is brought into contact with the drum 4 by means of a preset pressurizing force, the extension distance L2 between the moving push rod 410 and the tension push rod 420 can become 4 mm.

[0069] The controller 600 can drive the actuator 100 in the reverse direction when the parking brake is released, and stop the operation of the actuator 100 when the current applied to the actuator 100 increases while the load is applied from the clutch unit 500 to the transmission unit 200. Since the controller 600 performs such control when the brake is released, the gap between the brake shoe 2 and the drum 4 can be constantly maintained at a distance corresponding to the relative angle α° between the clutch connecting part 223 and the transmission locking part 512.

[0070] When the parking brake is applied, the driven gear 220 can be rotated in the forward direction and the clutch connecting part 223 and the gear locking part 512, which abut against each other, can be moved as shown in Fig. 9A, continuously in the forward direction (the counterclockwise direction in Fig. 9A) and then stopped. Therefore, before releasing the parking brake, the clutch connecting part 223 can maintain contact with the gear locking part 512 on the clockwise side of the gear locking part 512, as shown in Fig. 9A is shown.

[0071] Therefore, the parking brake can always be released in the Fig. 9A. The clutch connecting part 223 and the gear locking part 512 can be arranged with the preset angle α° between them. Thus, when the parking brake is released, the driven gear 220 can be rotated by the preset angle α° in the reverse direction (the clockwise direction in Fig. 9A), the clutch connecting part 223 of the driven gear 220 abuts the gear locking part 512, as shown in Fig. 9A. At this time, while the load of the clutch unit 500 is transmitted to the actuator 100 via the driven gear 220 and the drive gear 210, the current applied to the actuator 100 may increase, and the controller 600 may detect the increase in current and stop the operation of the actuator 100 in the reverse direction.

[0072] After the driven gear 220 begins to rotate in the reverse direction, no load can be applied to the driven gear 220 until the clutch connecting part 223 collides with the gear locking part 512. This means that the no-load state can be reached. Then, when the clutch connecting part 223 abuts the gear locking part 512, a load can be applied to the driven gear 220. Such a load fluctuation can occur as a current fluctuation of the actuator 100.

[0073] When the driven gear 220 is rotated by the preset angle α° in the reverse direction as described above, the moving push rod 410 can be moved back by L3 along the screw extension part 320 as shown in Fig. 10, the end of the screw extension part 320 on the moving push rod 410 can be moved from P2 to P3. That is, the reverse rotation of the driven gear 220 by the preset angle α° can indicate the backward movement of the moving push rod 410 by L3. For example, when the driven gear 220 and the rotating rod 300 are rotated by 90°, assuming that the front part of the screw 322 is 4 mm and the preset angle α° is 90°, the moving push rod 410 can be moved by 1 mm, and a gap of 1 mm / 2 can be provided between the left brake shoe 2 and the drum 4 and between the right brake shoe 2 and the drum 4.

[0074] Therefore, the brake shoe 2 and the drum 4 can constantly maintain a gap corresponding to 1 mm / 2 whenever the parking brake is released. In particular, a gap between the drum 4 and the friction material 3 coupled to the shoe 2 can be constantly maintained. According to Fig. 10, when the final travel distance of the moving push rod 410 is L2 and the return travel distance of the moving push rod 410 is L3, it can be indicated that the friction material 3 is worn by L4. This means that the wear of the friction material 3 corresponding to L4 can be compensated.

[0075] In the embodiment of the present invention, when the parking brake is applied, the actuator 100 can be controlled to stop when the preset current value is applied to the actuator 100 driven in the forward direction, and when the parking brake is released, the actuator 100 can be controlled to stop when the current applied to the actuator 100 driven in the reverse direction is increased. Therefore, the gap between the brake shoe 2 and the drum 4 can be constantly maintained at a distance corresponding to the relative angle α° between the clutch connecting part 223 and the gear locking part 512.

[0076] The electronic parking brake 1 having the above-described configuration according to the embodiment of the present invention may have a structure in which a main brake unit 10 and a parking brake unit 20 are formed in one and the same housing 700, as shown in Fig. 1 is shown.

[0077] The main brake unit 10 may include a piston housing part 11 formed in the housing 700 and a piston 12 installed in the piston housing part 11, and perform a normal braking operation using hydraulic pressure. Furthermore, the parking brake unit 20 may include a rod housing part 21 formed in the housing 700, and the gear unit 200, the rotating rod 300, the push rod unit 400, and the clutch unit 500 installed in the rod housing part 21, and perform a parking braking operation. With such a configuration, both the normal braking function and the parking braking function can be implemented only by installing an electronic parking brake device 1 between free ends of the pair of brake shoes 2.

[0078] However, the present invention is not limited to this, as long as the adjustment function can be implemented by the clutch unit 500. For example, the electronic parking brake according to the embodiment of the present invention may have a structure including the gear unit 200, the torsion bar 300, the push rod unit 400, the clutch unit 500, and the control device 600, and may be manufactured and installed separately from a wheel brake cylinder 8.

[0079] Fig. 11 is a front view schematically showing that an electronic parking brake device according to another embodiment of the present invention is installed.

[0080] The electronic parking brake device according to the embodiment of the present invention may be manufactured separately from the wheel brake cylinder 8 and arranged parallel to the wheel brake cylinder 8 between the free ends of the pair of brake shoes 2 or installed on an anchor 6 corresponding to the fixed ends of the brake shoes 2, as shown in Fig. 11. Furthermore, the electronic parking brake device can be installed outside the drum 4 or on the opposite side of the back plate 5. This means that the installation position of the electronic parking brake device is not specifically limited (see Fig. 1).

[0081] According to the embodiment of the present invention, when the parking brake is released, a load can be applied from the gear unit 200, which is rotated by the preset angle α°, to the clutch unit 500, and the controller 600 can control the operation of the actuator 100 according to the load such that the gap between the brake shoe 2 and the drum 4 is constantly maintained at a distance corresponding to the preset angle α°. That is, the adjustment function can be implemented.

[0082] Furthermore, the electronic parking brake device 1 according to the embodiment of the present invention can be manufactured with a simple structure in which the gear unit 200, the rotating rod 300, the push rod unit 400, and the clutch unit 500 are coaxially connected and fixed to one and the same housing 700. Therefore, the electronic parking brake device 1 does not need to include a plurality of parts such as an adjuster, a lever slide, and a tension spring, which adjuster includes a male push rod, a female push rod, and an adjusting nut, unlike an existing device. Furthermore, the electronic parking brake device 1 can eliminate a cumbersome process of assembling the parts into predetermined positions to implement the adjustment function in conjunction with movement line changes of the brake shoes and the parking brake operating lever.

[0083] Furthermore, since the gap between the brake shoe 2 and the drum 4 is correctly maintained as a distance corresponding to the preset angle α°, the extension of the gap to the drum 4 can be linearly compensated according to the wear of the friction material 3, thereby making it possible to prevent deterioration of the adjustment accuracy that occurs in the existing device when performing the gap compensation on the basis of a thread.

[0084] Furthermore, in the electronic parking brake device 1 according to the embodiment of the present invention, not only can the extension of the gap to the drum 4 due to the wear of the friction material 3 be compensated, but also the reduction of the gap to the drum 4 can be flexibly compensated, thereby making it possible to solve the problem in the existing device that the thermal expansion of the drum 4 cannot be efficiently handled because the existing device could not implement an operation for reducing the length of the adjuster.

Claims

[1] Electronic parking brake, which has: an actuator (100) configured to drive a gear unit (200); a rotating rod (300) connected to the gear unit (200); a push rod unit (400) configured to apply pressure to one or more brake shoes (2) while being moved in conjunction with the rotary rod (300); a clutch unit (500) arranged to interfere with a line of movement of the transmission unit (200) and configured to apply a rotational load to the transmission unit (200), while it rests against the gear unit (200) when the gear unit (200) is rotated at a preset angle; and a control device (600) configured to control an operation of the actuator (100) in accordance with the load applied to the actuator (100). [2] Electronic parking brake device according to claim 1, wherein the transmission unit (200) comprises: a drive gear (210) rotated by energy received from the actuator (100); and a driven gear (220) which engages with the drive gear (210) and is rotated, whereby a speed of the drive gear (210) is reduced. [3] Electronic parking brake device according to claim 2, wherein the driven gear (220) comprises: a rod connecting part (221) to which the rotating rod (300) is attached; a guide groove (222) formed on an inner peripheral surface of the rod connecting part (221) and extending in a direction of a rotation axis; and a coupling connecting part (223) which bears against the coupling unit (500). [4] Electronic parking brake device according to claim 3, wherein the rotating rod (300) comprises: a gear assembly part (310) installed through the rod connecting part (221); and a screw extension part (320) formed coaxially with the gear arrangement part (310) and having a screw (322) connected to the push rod unit (400). [5] Electronic parking brake device according to claim 4, wherein the gear arrangement part (310) comprises: a central shaft (311) having a diameter corresponding to the rod connecting part (221); and a guide projection (312) formed on an outer surface of the gear assembly part (310) and sliding along the guide groove (222) in an axial direction of the driven gear (220). [6] Electronic parking brake device according to claim 5, wherein the screw extension part (320) comprises: a first extension portion (321) formed at one end of the central shaft (311), wherein the screw (322) is formed on an outer surface of the first extension portion (321), the screw (322) being connected to the push rod unit (400); and a second extension portion (331) formed at the other end of the central shaft (311), and in which a contact stabilizer (332) is formed at one end of the second extension portion (331). [7] The electronic parking brake device according to claim 4, wherein the rotating rod (300) further comprises a thrust extending part (330) connected to the gear arrangement part (310) on an opposite side of the screw extending part (320) and configured to transmit a sliding displacement of the gear arrangement part (310) to the thrust rod unit (400). [8] Electronic parking brake device according to claim 7, wherein the push rod unit (400) comprises: a moving push rod (410) which bears against a brake shoe (2) of a pair of the one or more brake shoes (2), is screwed to the screw extension part (320) and is moved along the screw extension part (320) while cooperating with the rotation of the screw extension part (320); and a bracing push rod (420) abutting another brake shoe (2) of the pair of one or more brake shoes (2), connected to the push extension part (330), and pushed and moved by the push extension part (330) when the moving push rod (410) is moved. [9] Electronic parking brake device according to claim 3, wherein the clutch unit (500) comprises: a clutch base part (511) arranged coaxially with the driven gear (220); a gear locking part (512) formed in the form of a projection on the coupling base part (511) and arranged at a preset angle to the coupling connecting part (223); and a rotary load element (520) configured to pressurize the clutch base portion (511) to apply a load to the driven gear (220), the clutch connecting portion (223) being locked to the gear locking portion (512). [10] Electronic parking brake device according to claim 9, wherein the rotational load element (520) comprises: a first contact part (522) arranged on one side of the coupling base part and abutting the coupling base part; a second contact part (524) facing the first contact part, wherein the coupling base part (511) is provided therebetween; and an elastic pressurizing element (525) arranged between the coupling base part (511) and the second contact part (524) and elastically pressurizing the coupling base part (511). [11] An electronic parking brake device according to claim 1, wherein the control device (600) is configured to drive the actuator (100) in a forward direction when the electronic parking brake device is actuated, and to stop the operation of the actuator (100) when a preset amount of current is applied to the actuator (100) while a brake shoe (2) of the one or more brake shoes (2) is applying pressure to a drum (4). [12] The electronic parking brake device according to claim 11, wherein the control device (600) is configured to drive the actuator (100) in a reverse direction when the electronic parking brake device is released, and to stop the operation of the actuator (100) when a current applied to the actuator (100) increases while a load is applied from the clutch unit (500) to the transmission unit (200).

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