DRUM BRAKE DEVICE FOR A VEHICLE

Abstract

A drum brake device for a vehicle may comprise: a first brake shoe and a second brake shoe, which are movably connected to a back plate and spaced apart from each other; a wheel cylinder, which is positioned between one end of the first brake shoe and one end of the second brake shoe and is designed to expand the distance between the one ends of the first and the second brake shoe; and an actuator, which is positioned between the other end of the first brake shoe and the other end of the second brake shoe and is designed to provide a driving force for expanding the distance between the one ends of the first and the second brake shoe and the distance between the other ends of the first and the second brake shoe.

Description

BACKGROUND AREA Exemplary embodiments of the present disclosure relate to a drum brake device for a vehicle and in particular a drum brake device for a vehicle with which a parking brake force can be improved. BACKGROUND DISCUSSION Generally, a brake for a vehicle refers to a device used to decelerate or stop a vehicle in operation or to maintain a parking brake condition. A dual-servo drum brake generates braking force through the following process. When a lever on a driver's seat is pulled, a lever on the drum brake, connected via a parking brake cable, is pulled to generate a brake booster force. This brake booster force expands a pair of brake shoes, pressing them against a drum to generate braking force. The dual-servo drum brake can generate a braking force equivalent to a leading / trailing (L / T) type during main braking and a braking force equivalent to a dual-servo type during parking braking. An EPB (Electrical Parking Brake) for a vehicle is a device that electronically controls a parking brake. When a driver activates a switch, the EPB expands a pair of brake shoes using a force amplified by an actuator and a screw, so that the pair of brake shoes is pressed against the drum to generate a braking force. The EPB can perform an emergency stop and is automatically engaged and disengaged when the vehicle stops, for example, when waiting for a signal. In particular, even if a driver intends to restart the vehicle after it has stopped on an incline, the vehicle will not move backward, thus improving stability and driver comfort. Since the state-of-the-art dual-servo drum brake can be operated during parking braking on a dual-servo type and provides a strong parking braking force, it can be used on a heavy-duty vehicle. However, the dual-servo drum brake lacks the primary functions of an EPB (Electronic Parking Brake), which performs emergency braking or is automatically applied and released. As described above, the state-of-the-art EPB performs an emergency braking control or similar function. However, since the EPB only performs this emergency braking control or similar function on light / truck types, it is difficult to use the EPB on heavy-duty vehicles. Therefore, there is a need for a drum brake device that can be used on heavy-duty vehicles while still possessing the functions of the EPB, such as emergency braking. The prior art relating to the present disclosure is described in Korean patent application no. 2015-0049725, published on May 8, 2015, entitled “Parking Brake Device for Vehicle”. WO 2020 / 174 150 A1 discloses a drum brake according to the preamble of claim 1. US 2016 / 0 025 171 A1, DE 600 27 051 T2 and DE 10 2005 025 296 A1 disclose further drum brakes. OVERVIEW Various embodiments relate to a drum brake device for a vehicle, with which a loss of actuating force can be prevented or minimized and the occurrence of a loss of torque can be prevented. Furthermore, various embodiments relate to a drum brake device for a vehicle in which parts forming an actuator are arranged efficiently to improve space availability. In one embodiment, a drum brake device for a vehicle may comprise: a first brake shoe and a second brake shoe, which are movably connected to a back plate and spaced apart from each other; a wheel cylinder, which is positioned between one end of the first brake shoe and one end of the second brake shoe and is designed such that it expands the distance between one end of the first and the second brake shoe; and an actuator, which is positioned between the other end of the first brake shoe and the other end of the second brake shoe and is designed such that it provides a driving force for expanding the distance between one end of the first and the second brake shoe and the distance between the other ends of the first and the second brake shoe. The actuator comprises: an armature housing part; a motor housing part which is received in the armature housing part and is designed to generate a driving force for braking; a power transmission part which is designed to transmit the driving force generated by the motor part; and a pushrod part with a length which is varied by the driving force transmitted by the power transmission part. The motor part can have the motor shaft, the axial direction of which is parallel to the extension direction of the pushrod part. The armature housing part may comprise: a motor housing part in which the motor is received and which extends in one direction; a rod housing part in which the pushrod part is received and which is provided parallel to the direction of extension of the motor housing part; and a gear housing part in which the power transmission part is received and which extends from the motor housing part in the direction of the pushrod part, wherein the gear housing part is arranged eccentrically to one side in a longitudinal direction of the same on the basis of the center of the rod housing part. According to the invention, the power transmission part comprises: a first worm shaft which is connected to the motor shaft received in the motor part and on which a first gear worm is integrally formed; a first worm wheel which engages with the first gear worm and rotates with it; a second worm shaft which is arranged transversely over the first worm shaft and on which a second gear worm is integrally formed; and a second worm wheel which engages with the second gear worm and rotates with it and is designed in such a way that it varies the length of the pushrod part. The pushrod assembly comprises: a first pushrod, which rests against the first brake shoe, is screwed to one side of the second worm gear and is moved in one direction to press against the first brake shoe in conjunction with the rotation of the second worm gear; and a second pushrod, which rests against the second brake shoe, is connected to the other side of the second worm gear and is pushed by the second worm gear and moved in one direction to press against the second brake shoe when the first pushrod is moved. The second worm gear comprises: a gear that meshes with the second worm shaft; a bolt screw provided on one side of the gear and screwed onto the first pushrod; and a rod connecting part provided on the other side of the gear and connected to the second pushrod. The drum brake device further comprises: an adjusting arrangement positioned between one end of the first brake shoe and one end of the second brake shoe, designed to adjust the distance between the ends of the first and second brake shoes; and a pivoting lever rotatably mounted on the back plate, one end of which is connected to the adjusting arrangement and the other end of which is connected to the actuator, and which is rotated by the driving force of the actuator such that the adjusting arrangement expands the distance between the first and second brake shoes. The adjustment arrangement includes: a moving rod which is moved by the pivot lever to press against the second brake shoe; and a locking rod which is moved in conjunction with the moving rod and is designed to press against the first brake shoe. The pivot lever comprises: a lever plate provided between the first brake shoe and the back plate, the lower end of which is connected to the first pushrod and the upper end of which is connected to the adjusting assembly; and a lever pin projecting from the lever plate and passing through the first brake shoe, the lever plate being pressed by the first pushrod and rotated around the lever pin to move the actuating rod in a direction in which it presses against the second brake shoe. According to the embodiment of the present disclosure, the drum brake device for a vehicle can minimize the loss of actuating force of the actuator during a braking operation by the actuator, while the distance between the one ends of the first and the second brake shoe is expanded by actuating the wheel cylinder. Furthermore, when a driver releases the brake pedal to reduce the hydraulic pressure through the wheel cylinder, the drum brake device can maintain the state in which one end of the first and second brake shoes are pushed apart, thus preventing a loss of torque. Furthermore, since the parts that form the actuator in the drum brake device are arranged in an efficient manner, the actuator itself can be easily installed even in confined or restricted spaces. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a front view illustrating a drum brake device for a vehicle according to an embodiment of the present disclosure. Fig. 2 is an enlarged view of part A of Fig. 1. Fig. 3 is a perspective view illustrating an actuator according to the embodiment of the present disclosure. Fig. 4 is a top view of Fig. 3. Fig. 5 is an enlarged view of Fig. 3. Fig. 6 is a view illustrating that the length of a pushrod part of Fig. 3 is varied. Fig. 7 is a view illustrating that the distance between the first and second brake shoes is expanded by a wheel cylinder of Fig. 1. Figs. 8 and 9 are views illustrating an actuated state of the actuator of Fig. 7. DETAILED DESCRIPTION OF THE EXECUTION FORMS SHOWN A braking device for a vehicle is described below with reference to the accompanying drawings and various exemplary embodiments. It should be noted that the drawings are not to scale and line thicknesses or component sizes may be exaggerated for the sake of clarity and to simplify the description. Furthermore, the terms used herein are defined with consideration for the functions of the invention and may be modified according to the custom or intention of users or operators. Therefore, the definitions of terms should be made in accordance with the entirety of the disclosures set forth herein. Fig. 1 is a front view illustrating a drum brake device for a vehicle according to an embodiment of the present disclosure, Fig. 2 is an enlarged view of part A of Fig. 1, Fig. 3 is a perspective view illustrating an actuator according to the embodiment of the present disclosure, Fig. 4 is a top view of Fig. 3, Fig. 5 is an enlarged view of Fig. 3, Fig. 6 is a view illustrating that the length of a pushrod part of Fig. 3 is varied, Fig. 7 is a view illustrating that the distance between the first and second brake shoes is expanded by a wheel cylinder of Fig. 1, and Figs. 8 and 9 are views illustrating an actuation state of the actuator of Fig. 7. According to Fig. 1, Fig. 2, Fig. 3, Fig. 4, Fig. 5, Fig. 6, Fig. 7, Fig. 8 to Fig. 9, a drum brake device 100 for a vehicle according to an embodiment of the present invention has a first brake shoe 210, a second brake shoe 220, a wheel cylinder 300 and an actuator 500. The first brake shoe 210 and the second brake shoe 220 can be movably connected to a back plate 101 by a pin, a clamp, or the like, and spaced apart from each other. For example, the first and second brake shoes 210 and 220 can be designed in a circular arc shape that is convex towards the inner circumferential surface of a drum 103, and can have liners 211 and 221 that are attached to surfaces which each face the drum 103 and increase the frictional forces generated between the drum 103 and the first and second brake shoes 210 and 220. The wheel cylinder 300 is positioned between one end 210a of the first brake shoe 210 and one end 220a of the second brake shoe 220 and is designed to increase the distance between the ends of the first and second brake shoes 210 and 220. The ends of the first and second brake shoes 210 and 220 can be considered upper ends based on Fig. 1, and the ends of the first and second brake shoes 210 and 220 can be considered lower ends based on Fig. 1. The wheel cylinder 300 can have a cylinder rod (not shown) whose internal hydraulic pressure is varied according to brake pedal actuation by a driver, and which adjusts the distance between the ends of the first and second brake shoes 210 and 220. The cylinder rod can bear against the first and second brake shoes 210 and 220. As the internal hydraulic pressure of the cylinder rod increases, the cylinder rod can expand the distance between the first and second brake shoes 210 and 220, while varying its length. The actuator 500 is positioned between the other end 210b of the first brake shoe 210 and the other end 220b of the second brake shoe 220 and provides a driving force to expand the distance between the one ends of the first and second brake shoes 210 and 220 and the distance between the other ends of the first and second brake shoes 210 and 22. In particular, the actuator 500 can expand the distance between the other end of the first brake shoe 210 and the other end of the second brake shoe 220, and, in conjunction with the expansion of the distance between the other ends, expand the distance between one end of the first brake shoe 210 and one end of the second brake shoe 220. This means that while the distance between the other end of the first brake shoe 210 and the other end of the second brake shoe 220 is being expanded by the driving force of the actuator 500, the other ends can be pressed against the drum 103. Simultaneously, the state in which one end of the first brake shoe 210 and one end of the second brake shoe 220 are expanded can be maintained. Thus, by operating the wheel cylinder 300, a loss of actuating force of the actuator 500 during a braking process can be minimized by the actuator 500, while the distance between the one ends of the first and the second brake shoe 210 and 220 is expanded. Furthermore, when the driver releases a brake pedal to reduce the hydraulic pressure through the wheel cylinder 300, the condition in which the other ends of the first and second brake shoes 210 and 220 are pushed apart can be maintained to prevent a loss of torque. Furthermore, according to the embodiment of the present disclosure, the drum brake device can include both the wheel cylinder 300 and the actuator 500. This means that the drum brake device can be designed in such a way that the prior art dual-servo drum brake device and EPB are combined, thus ensuring sufficient parking brake force. Therefore, it is possible to implement an EPB that can also be used in a heavy-duty vehicle. The actuator 500 comprises an armature housing part 510, a motor part 530, a power transmission part 550 and a pushrod part 570. The armature housing part 510 can be positioned between the other end of the first brake shoe 210 and the other end of the second brake shoe 220 and have a housing space in this. The motor part 530 is housed in the armature housing part 510 and generates a driving force for braking. The motor part 530 can include a motor 531 and a motor shaft 532. The power transmission part 550 can be configured to transmit the driving force generated by the motor part 530. For example, the power transmission part 550 can have a plurality of gears connected to the motor shaft 532, reducing the driving force of the motor 531 and transmitting the reduced driving force. The pushrod section 570 can have a length that varies according to the driving force transmitted by the power transmission section 550. In particular, the pushrod section 570 can have a first pushrod 571 and a second pushrod 572, which are arranged coaxially and connected to the other ends of the first and second brake shoes 210 and 220, respectively. The pushrod section 570 can be configured to receive the driving force from the motor section 530 via the power transmission section 550 and to adjust the distance between the first and second pushrods 571 and 572. The axial direction of the motor shaft 532 contained in the motor part 530 can be set parallel to the extension direction of the pushrod part 570. In particular, according to the embodiment of the present disclosure, the armature housing part 510 can be arranged such that the axial direction B1 of the motor part 530 is parallel to the extension direction of the pushrod part 570, i.e., a longitudinal direction B2 (see Fig. 4). This means that the extension directions of the motor shaft 532 and the pushrod part 570 can be fixed in the same direction. Such an efficient arrangement allows the size of the armature housing part 510 for accommodating the motor part 530 and the pushrod part 570 to be reduced. Thus, the available space for the drum brake components can be increased. The armature housing part 510 includes a motor housing part 511, a gearbox housing part 513 and a rod housing part 515. The motor housing part 511 can extend in one direction, and the motor part 530 is incorporated therein. The rod housing part 515 can be arranged parallel to the direction of extension of the motor housing part 511, and the pushrod part 570 can be accommodated in it. That is to say, as described above, the motor housing part 511 and the rod housing part 515 can be arranged such that the axial direction of the motor shaft 532 and the longitudinal direction of the pushrod part 570 are parallel to each other. The gearbox housing part 513 can extend from the motor housing part 511 towards the pushrod part 570, and the power transmission part 550 can be accommodated within it. This means that the gearbox housing part 513 can be arranged perpendicular in direction B3 to the axial direction of the motor shaft 532 and the longitudinal direction of the pushrod part 570. This means that the motor housing part 511, the pushrod housing part 515, the pushrod part 570, and the power transmission part 550 are accommodated within the armature housing part 510. The gearbox housing part 513 can be arranged eccentrically to any side in the longitudinal direction of the rod housing part 515, based on the center of the rod housing part 515. For example, the gear housing part 513 can be positioned eccentrically to the right side (based on Fig. 4) in the longitudinal direction from the center C of the rod housing part 515. Since the power transmission part 550 of the actuator 500, which has a plurality of gears, is arranged eccentrically to one side in the armature housing part 510, the parts can be arranged efficiently in the narrow armature housing part 510. In particular, the power transmission part 550 has a first worm shaft 551, a first worm wheel 552, a second worm shaft 553 and a second worm wheel 554. The first worm shaft 551 is connected to the motor shaft 532 installed in the motor part 530, and a first gear worm is molded onto it. The first worm gear 552 engages rotatably with the first worm, and the second worm shaft 553 is arranged transversely across the first worm shaft 551, with a second worm integrally formed on it. This means that the second worm shaft can be arranged perpendicular to the first worm shaft and connected to the first worm gear 552. When the first worm gear 552, which engages with the first worm shaft 551, is rotated, the second worm shaft can rotate along with it. The second worm gear 554 engages with the second gear worm and is rotated, thereby varying the length of the pushrod section 570. This means that the second worm gear 554 can receive the driving force from the motor section 530 via the first worm shaft 551, the first worm gear 552, and the second worm shaft 553, and the length of the pushrod section 570 can vary using the received driving force. The pushrod part 570 can have a first pushrod 571 and a second pushrod 572. The first pushrod 571 can be arranged such that it rests against the first brake shoe 210 and is screwed to one side of the second worm gear 554. In conjunction with the rotation of the second worm gear 554, the first pushrod 571 can be rotated in a direction in which it presses against the first brake shoe 210. The second pushrod 572 can be arranged such that it rests against the second brake shoe 220 and is connected to the other side of the second worm gear 554. When the first pushrod 571 is moved, the second pushrod 572 can be pushed by the second worm gear 554 and moved in a direction in which it presses against the second brake shoe 220. The second worm gear 554 can include a gear 555, a bolt 556 and a rod connecting part 557. The gear 555 can mesh with the second worm shaft 553. The bolt 556 can be provided on one side of the gear 555 and screwed onto the first pushrod 571. The connecting rod 557 can be provided on the other side of the gear 555 and connected to the second pushrod 572. The following describes an actuation mechanism of the actuator with reference to the configuration described above. When the motor section 530 is operated, the first worm shaft 551, connected to the motor shaft 532, can be rotated, and the first worm gear 552, which meshes with the first worm shaft 551, can be rotated. When the first worm gear 552 is rotated, the second worm shaft 553, connected to the first worm gear 552, can be rotated. In conjunction with the rotation of the second worm shaft 553, the second worm gear 554, which meshes with the second worm shaft 553, can be rotated. When the gear 555 of the second worm gear 554 engages with the second worm shaft 553 and is rotated, the bolt 556 can move the first pushrod 571 screwed to it. This allows the other end of the first brake shoe 210 to be pressed against the drum 103. While the first pushrod 571 is moving, the second worm gear 554, which is screwed onto the first pushrod 571, can be moved towards the second pushrod 572. This allows the connecting rod 557 to press against the second pushrod 572. In doing so, the second brake shoe 220 can be pressed by the second pushrod 572 against the drum 103. This generates a braking force. The drum brake device according to the embodiment of the present disclosure may further comprise an adjustment arrangement 400 and a pivot lever 600. The adjusting arrangement 400 can be positioned between one end of the first brake shoe 210 and one end of the second brake shoe 220 and adjust the distance between the one ends of the first and second brake shoes 210 and 220. This means that the adjustment arrangement 400 can have a variable length for adjusting the gap between the ends of the first and second brake shoes 210 and 220. The adjustment arrangement 400 can include a movement rod 410 and a locking rod 420. The actuating rod 410 can be moved by the pivot lever 600 and press against the second brake shoe 220. The locking rod 420 can be moved in conjunction with the actuating rod 410 and press against the first brake shoe 210. The pivot lever 600 can be rotatably mounted on the back plate 101, and one end of it can be connected to the adjusting arrangement 400, and the other end of it can be connected to the actuator 500. While the pivot lever 600 is rotated by the driving force of the actuator 500, the adjusting arrangement 400 can expand the distance between the first and second brake shoes 210 and 220. In particular, the pivot lever 600 can have a lever plate 610 and a lever pin 620. The lever plate 610 can be positioned between the first brake shoe 210 and the back plate 101, and its lower end can be connected to the first pushrod 571, and its upper end can be connected to the adjusting assembly 400. The lever pin 620 can protrude from the lever plate 610 through the first brake shoe 210. In particular, the lever plate 610 can be designed in a plate shape and arranged between the first brake shoe 210 and the back plate 101. The lever pin 620 can project from the central region of the lever plate 610 such that it is rotatably arranged by the first brake shoe 210. When the lever plate 610 is pressed by the first pushrod 571, the lever plate 610 can pivot around the lever pin 620. While the lever plate 610 is pressed by the first pushrod 571 and pivoted around the lever pin 620, the lever plate 610 can move the actuating rod 410 in a direction in which it presses against the second brake shoe 220. In conjunction with the movement of the actuating rod 410, the locking rod 420 can be moved in a direction in which it presses against the first brake shoe 210. This allows the distance between one end of the first brake shoe 210 and one end of the second brake shoe 220 to be increased. In particular, even after the hydraulic pressure of the wheel cylinder 300 is removed, the condition in which the distance between the ends of the first and second brake shoes 210 and 220 is increased by actuating the actuator 500 can be maintained. The actuation and effect of the drum brake device for a vehicle according to the embodiment of the present disclosure are described below with reference to Figs. 1 and 7 to 9. Initially, when a driver presses the brake pedal in the initial phase shown in Fig. 1, the hydraulic pressure of the wheel cylinder 300 can be increased to expand the gap between one end of the first brake shoe 210 and one end of the second brake shoe 220 (see Fig. 7). This allows the first and second brake shoes 210 and 220 to be pressed against the drum 103 and held by the armature housing part 510. During this process, a torque can be generated to complete the main braking of the vehicle. Then, when the actuator 500 is actuated, the motor section 530 can be operated to expand the distance between the other ends of the first and second brake shoes 210 and 220. The pivot lever 600 can then lock these ends together, minimizing any loss of actuation force from the actuator 500. In particular, if the pivot lever 600 is not provided, the actuator 500 must be actuated by a force equal to or greater than the torque generated by the wheel cylinder 300 in order to expand the distance between the other ends of the first and second brake shoes 210 and 220, while the distance between their one ends is also being expanded. In this case, the actuating force may be lost. Therefore, with the drum brake device for a vehicle according to the embodiment of the present disclosure, the loss of the actuating force of the actuator 500 from the pivot lever 600 can be minimized by the locking structure. As shown in Figures 8 and 9, the distance between the other ends of the first and second brake shoes 210 and 220 can be expanded by the actuator 500, and the distance between the one ends of the first and second brake shoes 210 and 220 from the locking structure can be expanded by the pivot lever 600. This process minimizes any torque loss that may occur when the hydraulic pressure of the wheel cylinder 300 is released. In particular, if the driver releases the brake pedal when the vehicle is fully braked on an incline by wheel cylinder 300 and actuator 500, and the pivot lever 600 is not present, the distance between the first and second brake shoes 210 and 220 may decrease and return to their original position as the hydraulic pressure of wheel cylinder 300 is released. This means that during the transition from the state where one end of the first and second brake shoes 210 and 220 are in contact with the drum 103 to the state where only the other ends of the first and second brake shoes 210 and 220 are in contact with the drum 103, a loss of torque may occur. In this case, the vehicle may skid on an incline.Therefore, if the swivel lever 600 is not provided, a loss of torque can occur while the hydraulic pressure of the wheel cylinder 300 is released. The drum brake device for a vehicle according to the embodiment of the present disclosure can include the pivot lever 600 for maintaining the state in which the distance between the ends of the first and second brake shoes 210 and 220 is expanded by actuation of the actuator 500. Thus, although the hydraulic pressure of the wheel cylinder 300 is released after the driver has released the brake pedal, a loss of torque can be minimized to prevent a problem such as vehicle skidding. Thus, with the drum brake device for a vehicle according to the embodiment of the present disclosure, a loss of actuating force of the actuator during a braking operation can be minimized by the actuator, while the distance between the one ends of the first and the second brake shoe is expanded by actuating the wheel cylinder. Furthermore, when a driver releases the brake pedal to reduce the hydraulic pressure through the wheel cylinder, the drum brake device can maintain the state in which one end of the first and second brake shoes are pushed apart, thus preventing a loss of torque. Furthermore, since the parts that form the actuator in the drum brake device are arranged in an efficient manner, the actuator itself can be easily installed even in confined or restricted spaces. Although exemplary embodiments of the disclosure have been disclosed for illustrative purposes, those skilled in the art recognize that various modifications, additions, and substitutions are possible without altering the scope and content of the disclosure as defined in the accompanying claims. Thus, the true technical scope of the disclosure is defined by the subsequent claims.

Claims

Drum brake device (100) for a vehicle, comprising: a first brake shoe (210) and a second brake shoe (220) which are movably connected to a back plate (101) and spaced apart from each other; a wheel cylinder (300) which is positioned between one end of the first brake shoe (210) and one end of the second brake shoe (220) and is designed such that it expands the distance between the ends of the first and second brake shoes (210, 220); and an actuator (500) positioned between the other end of the first brake shoe (210) and the other end of the second brake shoe (220) and configured to provide a driving force for expanding the distance between the one ends of the first and second brake shoes (210, 220) and the distance between the other ends of the first and second brake shoes (210, 220), wherein the actuator (500) comprises: an armature housing part (510);a motor part (530) which is received in the armature housing part (510) and is configured to generate a driving force for braking; a power transmission part (550) which is configured to transmit the driving force generated by the motor part (530); and a pushrod part (570) with a length which is varied by the driving force transmitted by the power transmission part (550), characterized in that the power transmission part (550) comprises: a first worm shaft (551) which is connected to a motor shaft (532) received in the motor part (530) and on which a first gear worm is integrally formed; a first worm wheel (552) which engages with the first gear worm and rotates with it; a second worm shaft (553) which is arranged transversely over the first worm shaft (551) and on which a second gear worm is integrally formed;and a second worm gear (554) which engages with and rotates with the second gear worm and is designed in such a way as to vary the length of the pushrod part (570); wherein the pushrod part (570) comprises: a first pushrod (571) which bears against the first brake shoe (210), is screwed onto one side of the second worm gear (554) and is moved in a direction in which, in conjunction with the rotation of the second worm gear (554), it presses against the first brake shoe (210); and a second pushrod (572) which bears against the second brake shoe (220), is connected to the other side of the second worm gear (554) and is pressed by the second worm gear (554) and moved in a direction in which it presses against the second brake shoe (220) when the first pushrod (571) is moved; and wherein the second worm gear (554) has: a gear (555) which meshes with the second worm shaft (553);a bolt (556) provided on one side of the gear (555) and screwed onto the first pushrod (571); and a rod connecting part (557) provided on the other side of the gear (555) and connected to the second pushrod (572); furthermore, an adjusting arrangement (400) positioned between one end of the first brake shoe (210) and one end of the second brake shoe (220) and designed to adjust the distance between the ends of the first and second brake shoes (210, 220); and a pivot lever (600) which is rotatably provided on the back plate (101), one end of which is connected to the adjusting arrangement (400) and the other end of which is connected to the actuator (500) and which is rotated by the driving force of the actuator (500) such that the adjusting arrangement (400) expands the distance between the first and the second brake shoe (210, 220);wherein the adjusting arrangement (400) comprises: a moving rod (410) which is moved by the pivoting lever (600) to press against the second brake shoe (220); and a locking rod (420) which is moved in conjunction with the moving rod (410) and is designed to press against the first brake shoe (210); and wherein the pivoting lever (600) comprises: a lever plate (610) which is provided between the first brake shoe (210) and the back plate (101) and the lower end of which is connected to the first pushrod (571) and the upper end of which is connected to the adjusting arrangement (400); and a lever pin (620) projecting from the lever plate (610) and arranged through the first brake shoe (210), wherein the lever plate (610) is pressed by the first pushrod (571) and rotated around the lever pin (620) to move the actuating rod (410) in a direction in which it presses against the second brake shoe (220). Drum brake device for a vehicle according to claim 1, wherein the motor part (530) has the motor shaft (532), the axial direction of which is parallel to the extension direction of the pushrod part (570). Drum brake device for a vehicle according to claim 1, wherein the armature housing part (510) comprises: a motor housing part (511) in which the motor part (530) is received and which extends in one direction; a rod housing part (515) in which the pushrod part (570) is received and which is provided parallel to the direction of extension of the motor housing part (511); and a transmission housing part (513) in which the power transmission part (550) is received and which extends from the motor housing part (511) in the direction of the pushrod part (570), wherein the transmission housing part (513) is arranged eccentrically to one side in a longitudinal direction of the same on the basis of the center of the rod housing part (570).

Images