Drum brake system

Abstract

To provide a drum brake device which can perform both main brake and parking brake.SOLUTION: The invention relates to a drum brake device and includes: a housing; a main brake part which is provided at one side part of the housing and driven by oil pressure to compress shoes when main brake is performed; a parking brake part which is provided at the other side part of the housing and is driven by electromotive force of an actuator to compress the shoes when parking brake is performed; a first fastening member which fixes the housing to one surface part of a back plate; and a second fastening member which fixes the actuator to the housing at the other surface side of the back plate.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a drum brake device, and more particularly to a drum brake device that generates a braking force by friction with a drum that rotates with a wheel.

Background Art

[0002] Generally, a drum brake is a device that generates a braking force by friction with a drum that rotates with a wheel, and uses hydraulic pressure (main braking) or a shoe with a friction material attached thereto by using a cable linked to a parking brake lever to obtain a braking force by friction with the drum (parking braking).

[0003] A conventional drum brake includes a drum, a pair of shoes disposed on a back plate so as to face the inner peripheral surface of the drum and having a friction material attached to the outer periphery thereof, and a main braking wheel cylinder to which a braking hydraulic pressure is transmitted to move the shoes outward. Further, an operating lever for a parking brake provided in the drum brake has one end axially coupled to the shoe and the other end linked to a parking brake lever provided adjacent to the driver's seat via a cable, and when the parking brake lever is pulled, parking braking is mechanically performed.

[0004] The background art of the present invention is disclosed in Korean Patent Laid-Open Publication No. 2018-0047519 (published on May 10, 2018, title of the invention: Drum Brake for Vehicles).

Summary of the Invention

Problems to be Solved by the Invention

[0005] Conventionally, a main braking device for main braking and a parking braking device for parking braking are separately manufactured and installed. As a result, each of the main braking device and the parking braking device is separately manufactured and managed, and an assembly position where play can be ensured considering interference between each other according to specifications is set, adjusted, designed, and assembled, resulting in a problem of reduced productivity and increased unit price due to troublesome work.

[0006] Therefore, there is a need to improve this.

[0007] The present invention aims to provide a drum brake system that can perform both primary braking and parking braking. [Means for solving the problem]

[0008] The drum brake device according to the present invention is characterized by including a housing, a main braking unit provided on one side of the housing and driven by hydraulic pressure to pressurize the shoe during main braking, a parking braking unit provided on the other side of the housing and driven by the electric force of an actuator to pressurize the shoe during parking braking, a first fastening member for fixing the housing to one surface of a back plate, and a second fastening member for fixing the actuator to the housing on the other surface of the back plate.

[0009] The housing is characterized by including a housing portion, a piston housing portion formed to be hollow on one side of the housing portion and provided with the main braking portion, and a rod housing portion formed to be hollow on the other side of the housing portion and provided with the parking braking portion, and positioned at a distance from the piston housing portion from the rotation center of the shoe.

[0010] The housing portion is characterized by including a main body portion on which the piston housing portion and the rod housing portion are formed, a first fixing portion formed on the main body portion and fixed to the back plate by the first fastening member, a through extension portion formed at the end of the main body portion and positioned on the other side of the back plate through a through hole portion formed in the back plate, and a second fixing portion formed on the through extension portion and to which the second fastening member is fastened.

[0011] The first fixing portion includes a left fixing portion formed on the left side of the main body and fixed to the back plate by the first fastening member, and a right fixing portion formed on the right side of the main body and fixed to the back plate by the first fastening member, and the through extension portion is arranged between the left fixing portion and the right fixing portion.

[0012] The piston housing includes a cylinder portion in which the main braking portion is housed, and a hydraulic flow path portion that extends from both sides of the through extension portion to the cylinder portion and forms a flow path for supplying fluid to the inside of the cylinder portion, and the second fixing portion is arranged in the lateral intermediate portion of the through extension portion at a distance from the hydraulic flow path portion.

[0013] The present invention further includes a rotation prevention assembly that restrains the rotation of the actuator around the second fastening member by fitting assembly between the housing and the actuator, wherein the rod housing includes a rod cylinder portion in which the parking brake portion is housed, and a drive shaft housing portion formed extending from the through extension portion to the rod cylinder portion, into which the output shaft of the actuator is retracted and connected to the parking brake portion, wherein the second fixing portion is arranged on one side of the drive shaft housing portion at a distance from the first fixing portion, and the rotation prevention assembly portion is formed on the opposite side of the second fixing portion with respect to the central portion of the drive shaft housing portion.

[0014] The anti-rotation assembly is characterized by being formed in communication with the peripheral edge of the drive shaft housing and including an anti-rotation groove formed by recessing in the extension direction of the drive shaft housing, and an anti-rotation projection formed protruding from the actuator and fitted into the anti-rotation groove.

[0015] The housing portion is connected to the side of the main body portion where the piston housing portion and the rod housing portion are located, and further includes a foreign matter inflow prevention portion that covers the peripheral edge of the piston housing portion and the peripheral edge of the rod housing portion.

[0016] The foreign matter inflow prevention section is characterized by including a connecting section disposed between the opening of the piston housing section and the opening of the rod housing section; a piston sealing section having a ring shape corresponding to the peripheral edge of the piston housing section, formed continuously on one side of the connecting section, with its inner end connected to the main braking section; a rod sealing section having a ring shape corresponding to the peripheral edge of the rod housing section, formed continuously on the other side of the connecting section, with its inner end connected to the parking braking section; and a main body fixing section formed on the connecting section and fixed to the main body section.

[0017] The piston housing and the rod housing are located on the same radial extension line with respect to the center of rotation of the back plate, and the actuator is located on the same radial extension line as the chassis supporting the central part of the back plate and is positioned alongside the center of rotation of the back plate.

[0018] The main braking unit is characterized by including a piston located at the end of the housing and moving to the outside of the housing by hydraulic pressure to pressurize the shoe, and an elastic member located inside the housing that reduces the impact force acting on the piston as it returns to the inside of the housing.

[0019] The parking brake unit is characterized by including a gear unit disposed inside the housing and rotating in conjunction with the actuator, and a rod unit connected to the gear unit and moving to the outside of the housing in conjunction with the gear unit to pressurize the shoe.

[0020] The present invention is further characterized by including a rotation prevention assembly portion which is disposed at a distance from the second fastening member and which restrains the rotation of the actuator around the second fastening member by fitting assembly between the housing and the actuator.

[0021] The anti-rotation assembly is characterized by including an anti-rotation groove formed recessed into one side of the housing and the actuator, and an anti-rotation projection formed protruding from the other side of the housing and the actuator, which is fitted into the anti-rotation groove. [Effects of the Invention]

[0022] The drum brake device according to the present invention can realize an integrated main brake and parking brake structure in which the main brake unit and the parking brake unit are interconnected in a single housing. Furthermore, in the drum brake device according to the present invention, the process of installing the main brake unit and the parking brake unit is simple. Specifically, the main brake unit and the parking brake unit can be installed simultaneously through a simple process of installing the housing on the back plate.

[0023] As a result, the present invention simplifies the manufacturing process compared to conventional methods, which involved separately manufacturing and managing the main braking unit and the parking braking unit, and then designing and assembling them while considering mutual interference according to specifications to ensure sufficient play. Furthermore, it is possible to further reduce the distance between the main braking unit and the parking braking unit, enabling miniaturization and weight reduction, and improving space utilization.

[0024] Furthermore, according to the present invention, by fastening the first fastening member and the second fastening member to the housing, multiple components including the actuator, back plate, and housing can be firmly bound together with the housing and actuator positioned on one side and the other side, respectively, with respect to the back plate.

[0025] Furthermore, according to the present invention, since the first and second fastening members are assembled with the housing and actuator positioned on one and the other sides of the back plate, the rigidity and structural stability of the back plate can be further improved compared to embodiments in which a large hole must be formed on the back plate for the actuator to pass through, as in embodiments in which the housing and actuator are assembled first and then the back plate is assembled later.

[0026] Further, according to the present invention, by releasing the fastening of the second fastening member, only the actuator can be easily separated alone. Compared with an embodiment in which the actuator, the back plate, and the housing are continuously penetrated and fastened with one fastening member, replacement and inspection of the actuator can be performed more easily.

Brief Description of the Drawings

[0027] [Figure 1] It is a front-side perspective view showing an installation state of a drum brake device according to an embodiment of the present invention. [Figure 2] It is a back-side perspective view showing an installation state of a drum brake device according to an embodiment of the present invention. [Figure 3] It is a cross-sectional view of a main part showing a drum brake device according to an embodiment of the present invention. [Figure 4] It is a front-side perspective view showing a housing of a drum brake device according to an embodiment of the present invention. [Figure 5] It is a back-side perspective view showing a housing of a drum brake device according to an embodiment of the present invention. [Figure 6] It is an assembly view of a main part showing a drum brake device according to an embodiment of the present invention. [Figure 7] It is a perspective view showing a foreign matter intrusion prevention part of a drum brake device according to an embodiment of the present invention. [Figure 8] It is a cross-sectional view taken along line A-A' of FIG. 7. [Figure 9] It is a conceptual diagram shown to explain a tolerance due to an arrangement of a main braking part and a parking braking part of a drum brake device according to an embodiment of the present invention. [Figure 10] It is a cross-sectional view taken along line B-B' of FIG. 1.

Modes for Carrying Out the Invention

[0028] Hereinafter, embodiments of the drum brake device according to the present invention will be described with reference to the attached drawings. In this process, the thickness of the lines and the size of the components shown in the drawings may be exaggerated for clarity and convenience of explanation. Furthermore, the terms described later are defined in consideration of the function in the present invention, and these may vary depending on the intent or convention of the user or operator. Therefore, the definitions of these terms must be based on the content throughout this specification.

[0029] Figure 1 is a front perspective view showing the installed state of a drum brake device according to one embodiment of the present invention, Figure 2 is a rear perspective view showing the installed state of a drum brake device according to one embodiment of the present invention, and Figure 3 is a cross-sectional view of the main part of a drum brake device according to one embodiment of the present invention.

[0030] Referring to Figures 1 to 3, a drum brake device 1 according to one embodiment of the present invention includes a housing 100, a main braking unit 200, a parking braking unit 300, a first fastening member 410, a second fastening member 420, and an anti-rotation assembly unit 430.

[0031] The housing 100 is positioned between a pair of left and right shoes 2. The main braking unit 200 is located on one side of the housing 100 and is driven by hydraulic pressure during main braking to pressurize the shoes 2. The parking braking unit 300 is located on the other side of the housing 100 and is driven by electric power during parking braking to pressurize the shoes 2. Both ends of the main braking unit 200 are positioned to engage with one side of the shoe 2, and the parking braking unit 300 is positioned to engage with the other side of the shoe 2 at a set distance from the main braking unit 200.

[0032] The first fastening member 410 fixes the housing 100 to a set position on one surface of the back plate 5. The first fastening member 410 fastens to the housing 100 by passing through the back plate 5, thereby binding the back plate 5 and the housing 100 together.

[0033] The second fastening member 420 penetrates the back plate 5 and secures the actuator 310 to the end of the housing 100 located on the other side of the back plate 5. The second fastening member 420 secures the actuator 310 to the housing 100 on the other side of the back plate 5. The second fastening member 420 fastens to the housing 100 by penetrating the actuator 310, thereby binding the actuator 310 and the housing 100 together.

[0034] By sequentially fastening the first fastening member 410 and the second fastening member 420, the actuator 310, back plate 5, and housing 100 can be firmly bound together with the housing 100 and actuator 310 positioned on one side and the other side, respectively, relative to the back plate 5.

[0035] The rotation prevention assembly section 430 is a device for preventing the rotation and movement of the actuator 310. It is positioned at a distance from the second fastening member 420 and restrains the rotation and movement of the actuator 310, centered on the second fastening member 420, during the fitting assembly between the housing 100 and the actuator 310.

[0036] Referring to Figure 3, the housing 100 according to one embodiment of the present invention includes a housing portion 110, a piston housing portion 120, and a rod housing portion 130.

[0037] The housing portion 110 is the basic framework of the housing 100 and has a single block shape. The piston housing portion 120 is the portion where the main braking portion 200 is provided and is formed to be hollow on one side of the housing portion 110. The rod housing portion 130 is the portion where the parking braking portion 300 is provided and is formed to be hollow on the other side of the housing portion 110 at a set distance from the piston housing portion 120.

[0038] Figure 4 is a front perspective view showing the housing of a drum brake device according to one embodiment of the present invention, Figure 5 is a rear perspective view showing the housing of a drum brake device according to one embodiment of the present invention, and Figure 6 is an assembly diagram of the main parts of a drum brake device according to one embodiment of the present invention.

[0039] Referring to Figures 4 to 6, the housing portion 110 according to one embodiment of the present invention includes a main body portion 111, a first fixing portion 112, a through extension portion 113, a second fixing portion 114, and a foreign matter inflow prevention portion 115.

[0040] The main body portion 111 is the device portion that forms the main body of the housing portion 110, and a piston housing portion 120 and a rod housing portion 130 are formed inside so that they are hollow. The piston housing portion 120 and the rod housing portion 130 are formed extending laterally on the main body portion 111 and are formed so that both ends are open.

[0041] The main body 111 and the actuator 310 are positioned on either side of the backplate 5, with the backplate 5 in between. For the sake of explanation, the arrangement and orientation of the components will be described below, with the backplate 5 as the reference point, with the side where the main body 111 is positioned being the front and the other side where the actuator 310 is positioned being the rear.

[0042] The first fixing portion 112 is a device portion that is fixed to the front portion of the back plate 5 by the first fastening member 410, and is formed on the left and right sides of the main body portion 111. In one embodiment of the present invention, the first fixing portion 112 includes a left fixing portion 112a and a right fixing portion 112b, and the first fastening member 410 is provided with two or more members that are fastened to the left fixing portion 112a and the right fixing portion 112b, respectively.

[0043] The left-side fixing portion 112a is formed on the left side of the main body portion 111, and the first fastening member 410 is fastened to the front left-side fixing portion 112a by passing through the left side of the back plate 5 from the rear. The right-side fixing portion 112b is formed on the right side of the main body portion 111, and the other first fastening member 410 is fastened to the front right-side fixing portion 112b by passing through the right side of the back plate 5 from the rear.

[0044] On the left fixing portion 112a and the right fixing portion 112b, there are holes or grooves into which the first fastening member 410 can be fitted and fastened, and there are also female threaded portions into which the first fastening member 410, which has a male threaded portion, can be screw-fastened. By fastening multiple first fastening members 410 to the left fixing portion 112a and the right fixing portion 112b, which are located on the left and right sides of the housing 100, the housing 100 can be firmly fixed to the set position on the back plate 5 without movement or rotation.

[0045] The through extension 113 is formed at the rear end of the main body 111 and penetrates the through hole 6 formed in the back plate 5 from front to rear, and is positioned on the rear side of the back plate 5, i.e., at the rear. The actuator 310 is coupled and fixed to the through extension 113 located at the rear of the back plate 5, thereby firmly positioning itself at the set position at the rear of the back plate 5.

[0046] In the through extension 113, at the position corresponding to the parking brake section 300, the drive shaft housing section 132 of the rod housing section 130 for coupling the actuator 310, the second fixing section 114, and the rotation prevention groove section 431 of the rotation prevention assembly section 430 are formed. In addition, in the through extension 113, at the position corresponding to the main brake section 200, the hydraulic flow path section 122 of the piston housing section 120 is formed.

[0047] More specifically, the through extension 113 is positioned between the pair of left and right first fixing parts 112, namely the left fixing part 112a and the right fixing part 112b. At this time, the drive shaft housing part 132 is positioned on the extension line connecting the left fixing part 112a to the right fixing part 112b, or in other words, the extension line connecting the pair of left and right first fastening members 410.

[0048] The second fixing portion 114 is a device portion that is connected to the actuator 310 by the second fastening member 420, and is formed on the lower rear surface of the through extension portion 113. More specifically, the second fixing portion 114 is formed below the drive shaft housing portion 132 and is positioned between the pair of left and right hydraulic flow passage portions 122. That is, the second fixing portion 114 is positioned in the lateral intermediate portion of the through extension portion 113, spaced apart from the pair of left and right hydraulic flow passage portions 122.

[0049] Since the pair of left and right hydraulic flow passage sections 122 have an extension structure in which the distance between them narrows as they move towards the front side where the cylinder section 121 is located, it is preferable that one second fastening member 420 is fastened to the second fixing section 114 in order to stably secure the distance between the pair of left and right hydraulic flow passage sections 122.

[0050] A fastening portion 311 is formed at the lower part of the actuator 310, through which the second fastening member 420 can pass. The second fastening member 420 is fastened from the rear of the actuator 310 through the fastening portion 311 to the front second fixing portion 114. A hole or groove is formed on the second fixing portion 114 into which the second fastening member 420 can be fitted and fastened, and a female threaded portion is formed into which the second fastening member 420, which has a male threaded portion, can be screw fastened.

[0051] Figure 7 is a perspective view showing a foreign matter inflow prevention section of a drum brake device according to one embodiment of the present invention, and Figure 8 is a cross-sectional view taken along line A-A' in Figure 7.

[0052] The foreign matter inflow prevention section 115 is a device that prevents foreign matter from flowing into the piston housing section 120 and the rod housing section 130, and is connected to both sides of the main body section 111 where the openings of the piston housing section 120 and the rod housing section 130 are located. Here, the opening of the piston housing section 120 refers to the open lateral ends of the piston housing section 120, and the opening of the rod housing section 130 refers to the open lateral ends of the rod housing section 130.

[0053] The foreign matter inflow prevention section 115 is made of a soft or flexible material and is provided on the main body 111 so as to cover the open portion of the piston housing section 120 and the open portion of the rod housing section 130, more specifically so as to cover the gap between the piston housing section 120 and the piston 210 and the gap between the rod housing section 130 and the push rod 332. Referring to Figures 7 and 8, the foreign matter inflow prevention section 115 according to one embodiment of the present invention includes a connecting section 116, a piston sealing section 117, a rod sealing section 118, and a main body fixing section 119.

[0054] The connecting portion 116 is positioned between the opening of the piston housing portion 120 and the opening of the rod housing portion 130, which are formed on the side surface of the main body portion 111. The piston sealing portion 117 has a shape that can cover both sides of the piston housing portion 120 and is formed continuously with the lower part of the connecting portion 116. The rod sealing portion 118 has a shape that can cover both sides of the rod housing portion 130 and is formed continuously with the upper part of the connecting portion 116.

[0055] When the piston housing 120 is positioned below the rod housing 130, the connecting portion 116 is positioned between the piston housing 120 and the rod housing 130, the piston sealing portion 117 is formed integrally with the connecting portion 116 at its lower part, and the rod sealing portion 118 is formed integrally with the connecting portion 116 at its upper part.

[0056] A circular hole is formed on the piston sealing portion 117, corresponding to the peripheral edge of the opening of the piston housing portion 120. Referring to Figure 3, the inner circumference 117a of the piston sealing portion 117 crosses the opening of the piston housing portion 120 and connects to the main braking portion 200. More specifically, the inner circumference 117a of the piston sealing portion 117 is fitted into the first coupling groove 211 formed in the piston 210 of the main braking portion 200 and is airtightly connected to the piston 210.

[0057] The rod sealing portion 118 has a circular hole portion that corresponds to the peripheral edge of the opening portion of the rod housing portion 130. Referring to Figure 3, the inner circumference 118a of the rod sealing portion 118 crosses the opening portion of the rod housing portion 130 and is fitted into the parking brake portion 300, and more specifically into the second coupling groove portion 333 formed around the push rod 332 of the parking brake portion 300, thereby connecting it to the push rod 332.

[0058] A fluid for creating a hydraulic atmosphere can flow into the piston housing 120, and a lubricant for the smooth operation of the gear section 320 and the rod section 330 can flow into the rod housing 130. The piston seal 117 and the rod seal 118 prevent the fluid inside the piston housing 120 and the rod housing 130 from flowing out to the outside through the opening, and also prevent foreign matter from entering the main braking section 200 and the parking braking section 300.

[0059] The main body fixing portion 119 is a device portion that is connected to the main body portion 111, and has a ring shape that extends continuously along the front and rear ends of the connecting portion 116, the lower peripheral edge of the piston sealing portion 117, and the upper peripheral edge of the rod sealing portion 118, and is formed to protrude toward the main body portion 111 to a set thickness. By fitting the main body fixing portion 119 into the third connecting groove portion 111a formed around the main body portion 111 and fixing it, the piston sealing portion 117 and the rod sealing portion 118 can be firmly bound to the main body portion 111.

[0060] With the structure described above, the foreign matter inflow prevention section 115 serves to prevent the main braking section 200 from detaching from the piston housing section 120 and the parking braking section 300 from detaching from the rod housing section 130, without hindering the operation of the main braking section 200 and the parking braking section 300.

[0061] Referring to Figures 4 to 7, the piston housing 120 according to one embodiment of the present invention includes a cylinder portion 121 and a hydraulic flow path portion 122.

[0062] The cylinder portion 121 is the space in which the main braking portion 200 is housed, and is formed to be circumferentially hollow on the housing portion 110. The cylinder portion 121 is formed to cross the housing portion 110 in the left-right direction, and both ends are formed to be open onto the side surfaces of the housing portion 110. The hydraulic flow path portion 122 is the portion that forms a fluid supply path for creating a hydraulic atmosphere inside the cylinder portion 121, and is formed to extend from the outer surface of the housing portion 110 to the cylinder portion 121.

[0063] The outer end of the hydraulic flow path section 122 is formed to open onto a through extension section 113 formed on the rear surface of the main body section 111. Since the through extension section 113 is exposed to the rear of the back plate 5 via the through hole section 6, fluid can be stably supplied from the rear of the back plate 5 through the hydraulic flow path section 122 into the interior of the cylinder section 121 without interference with numerous components, including a pair of shoes 2 provided in front of the back plate 5.

[0064] The inner end of the hydraulic flow path section 122, which communicates with the cylinder section 121, is formed to face the elastic member 220 of the main braking section 200, which is located inside the cylinder section 121. The pair of left and right hydraulic flow path sections 122 gradually narrow in a V-shape as they move from the outer end to the inner end. As a result, the fluid flowing into the hydraulic flow path section 122 is directed towards the elastic member 220 located in the middle of the cylinder section 121.

[0065] With this structure of the hydraulic flow path 122, the fluid that flows into the cylinder 121 can interact with the elastic member 220 and be uniformly dispersed and diffused inside the cylinder 121, thus solving the problem of the fluid repeatedly impacting the inner wall of the cylinder 121 or one side of the piston 210 during the process of the fluid flowing into the cylinder 121.

[0066] Referring to Figures 4 to 7, the rod housing portion 130 according to one embodiment of the present invention includes a rod cylinder portion 131 and a drive shaft housing portion 132.

[0067] The rod cylinder section 131 is a space that houses the rod section 330 of the parking brake section 300 and the driven gear 322 of the gear section 320, and is formed on the housing section 110 to be circumferentially hollow. The rod cylinder section 131 is arranged alongside the cylinder section 121, crossing the housing section 110 in the left-right direction, and is formed so that both ends are open onto the side surfaces of the housing section 110.

[0068] The drive shaft housing 132 is a space that houses the drive gear 321 of the gear section 320 of the parking brake section 300 and the output shaft of the actuator 310, and is formed in communication with the rod cylinder section 131. The output shaft of the actuator 310 is pulled into the housing section 110 via the drive shaft housing 132 and connected to the gear section 320 of the parking brake section 300.

[0069] The rod cylinder section 131 is positioned at a set distance from the piston housing section 120. The distance between the rod cylinder section 131 and the piston housing section 120 can be freely extended or retracted and adjusted within a range where they do not interfere with or communicate with each other. Reducing the distance between the rod cylinder section 131 and the piston housing section 120 reduces the volume and weight of the housing section 110.

[0070] Furthermore, this structure allows for a degree of miniaturization that was previously impossible to achieve by taking into account the casing thickness of the main brake system, the casing thickness of the parking brake system, and the play between the main brake system and the parking brake system, which were all required in conventional systems where the main brake system and parking brake system were provided separately.

[0071] Referring to Figures 1 and 3, the main braking unit 200 according to one embodiment of the present invention includes a piston 210 and an elastic member 220.

[0072] The piston 210 moves along the cylinder portion 121 by hydraulic pressure, both inward and outward, while applying pressure to the shoe 2 toward the drum (not shown) or releasing the pressure it has applied. In one embodiment of the present invention, a pair of pistons 210 are positioned at both ends of the cylinder portion 121. A first coupling groove 211 and a shoe coupling portion 212 are formed at the ends of the piston 210 that are exposed to the outside of the cylinder portion 121.

[0073] The first coupling groove 211 is formed in a circular shape around the outer surface of the piston 210, and the inner circumference 117a of the piston sealing portion 117 is fitted into and coupled to it. The cylinder portion 121 is sealed by the inner circumference 117a of the piston sealing portion 117 being fitted into and fixed in the first coupling groove 211. The shoe coupling portion 212 has a slit shape into which the end of the shoe 2 can be inserted, or in other words, a pincer shape, and is provided to engage with the shoe 2.

[0074] When fluid flows in through the hydraulic passage 122, the internal pressure of the cylinder 121 increases, and the pair of left and right pistons 210 extend, increasing the distance between them and pushing out the pair of left and right shoes 2. This process performs the main braking. When fluid is discharged through the hydraulic passage 122, the internal pressure of the cylinder 121 decreases, and the pair of left and right pistons 210 contract, decreasing the distance between them and releasing the push-out of the pair of left and right shoes 2. This process releases the main braking.

[0075] The elastic member 220 is positioned inside the cylinder section 121 and between the pair of pistons 210. By being positioned between the pair of pistons 210, the elastic member 220 prevents the pair of pistons 210 from directly colliding with each other as they return to the inside of the cylinder section 121, thereby reducing the impact force acting on the pistons 210. In addition, the elastic member 220 interferes with the fluid flowing between the pair of pistons 210 through the hydraulic flow path section 122, allowing the hydraulic pressure to be uniformly distributed and diffused. An elastic spring or the like can be used as the elastic member 220.

[0076] Referring to Figures 1 and 3, the parking brake unit 300 according to one embodiment of the present invention includes an actuator 310, a gear unit 320, and a rod unit 330.

[0077] The gear section 320 is a device that transmits rotational driving force from the actuator 310 to the rod section 330, and has the structure of a worm wheel gear, and is located inside the rod housing section 130. The drive gear 321 of the gear section 320 has a worm gear structure, is provided in the drive shaft housing section 132, and is connected coaxially to the output shaft of the actuator 310 which is pulled inside the drive shaft housing section 132. The driven gear 322 of the gear section 320 has the structure of a wheel gear that meshes with the worm gear, and is located in the middle of the rod cylinder section 131.

[0078] The rod section 330 is a device that converts the rotational displacement of the gear section 320 into linear displacement and transmits it to the shoe 2. It includes a rotating rod 331 and a push rod 332 and is provided on the rod cylinder section 131. The rotating rod 331 consists of a single rod member and is connected coaxially to the driven gear 322. The push rod 332 is connected around both ends of the rotating rod 331 with a screw connection to the rotating rod 331. It moves in conjunction with the rotation and movement of the rotating rod 331, moving inward and outward on the rod cylinder section 131 to pressurize the shoe 2 toward the drum or to release the pressurized shoe 2.

[0079] In one embodiment of the present invention, a pair of push rods 332 are arranged on the left and right sides at both ends of the rod cylinder portion 131. The ends of the push rods 332 that are exposed to the outside of the rod cylinder portion 131 have the same structure as the ends of the piston 210, which have a first coupling groove portion 211 and a shoe coupling portion 212 formed thereon. The rod sealing portion 118 seals the rod cylinder portion 131 by fitting the inner circumference portion 118a of the rod sealing portion 118 into the second coupling groove portion formed around the outer surface portion of the push rod 332 and fixing it in place. The ends of the push rods 332 have a slit shape into which the end of the shoe 2 can be inserted and are provided to engage with the shoe 2.

[0080] When the actuator 310 is driven in the forward direction, the rotational force of the actuator 310 is transmitted to the rotating rod 331 via the gear section 320, and the rotating rod 331 rotates in the forward direction in conjunction with the gear section 320. At this time, the pair of push rods 332 extend along the rotating rod 331, increasing the distance between them, and push out the pair of shoes 2 on the left and right sides.

[0081] With the piston 210 pressurizing the shoe, the parking brake is applied through the process described above. When the actuator 310 is driven in the reverse direction, the pair of push rods 332 move in a reduced position, bringing them closer together and releasing the push of the pair of shoes 2 on the left and right sides. The parking brake is released through this process.

[0082] Figure 9 is a conceptual diagram illustrating the tolerances due to the arrangement of the main braking unit and parking braking unit of a drum brake device according to one embodiment of the present invention, and Figure 10 is a cross-sectional view taken along the line B-B' in Figure 1.

[0083] When using drum brakes, the friction pad 3 attached to the shoe 2 wears down, and this wear of the friction pad 3 causes the gap between the shoe 2 and the drum (not shown) to change. This gap between the shoe 2 and the drum can be corrected so that it remains constant even when the friction pad 3 wears down, by the parking brake unit 300.

[0084] The length of the parking brake section 300 is adjustable depending on the driving state of the actuator 310, but the pair of shoes 2 are subjected to pressure in a direction toward each other by the elastic member 7, and the distance between them can be substantially determined according to the length of the parking brake section 300.

[0085] When the actuator 310 is driven in the forward direction, the length of the parking brake section 300 extends, performing parking braking by pushing the pair of left and right shoes 2 in a direction that separates them from each other. When the actuator 310 is driven in the reverse direction, the pressure that was pushing out the shoes 2 is released, releasing the parking brake. The distance between the shoes 2 and the drum can be adjusted and corrected according to the amount of reverse driving of the actuator 310.

[0086] Referring to Figures 1 and 10, the rod housing 130 is positioned at a distance from the piston housing 120 to the rotational center C1 of the shoe 2. This means that the parking brake unit 300 provided in the rod housing 130 is positioned at a distance from the rotational center C1 of the shoe 2 to the main brake unit 200 provided in the piston housing 120.

[0087] Figure 9(a) shows the relative magnitude of the tolerance d2 of the main braking unit 200 to the tolerance d1 of the parking braking unit 300 in an embodiment in which the main braking unit 200 is positioned further away from the rotation center C1 of the shoe 2 than the parking braking unit 300. And Figure 9(b) shows the relative magnitude of the tolerance d2 of the main braking unit 200 to the tolerance d1 of the parking braking unit 300 in an embodiment in which the parking braking unit 300 is positioned further away from the rotation center C1 of the shoe 2 than the main braking unit 200.

[0088] When the main braking unit 200 is positioned further away from the rotation center C1 of the shoe 2 than the parking braking unit 300, if a tolerance d1 occurs when the parking braking unit 300 adjusts and corrects the return position of the shoe 2 or the gap between the shoe and the drum as described above, the tolerance d2 of the main braking unit 200 will be formed to be larger than the tolerance d1 of the parking braking unit 300 (d2>d1), as shown in Figure 9(a).

[0089] As in one embodiment of the present invention, when the rod housing portion 130 is disposed at a position spaced apart from the piston housing portion 120 from the rotation center portion C1 of the shoe 2, the tolerance d2 of the main braking portion 200 is formed smaller than the tolerance d1 of the parking braking portion 300 as shown in (b) of FIG. 9 (d2 < d1). Accordingly, even if the parking braking portion 300 has the same degree of tolerance d1 with respect to the shoe 2, the main braking portion 200 has a smaller tolerance d2 as compared to an embodiment in which it is disposed at a distance farther from the rotation center portion C1 of the shoe 2 than the parking braking portion 300.

[0090] By disposing the rod housing portion 130 at a position spaced apart from the piston housing portion 120 from the rotation center portion C1 of the shoe 2, the tolerance d2 of the main braking portion 200 can be clearly reduced with respect to the tolerance d1 of the parking braking portion 300 that occurs in the same degree as described above. Accordingly, even if a tolerance d2 occurs in the process of correcting the gap between the shoe 2 and the drum by the parking braking portion 300, the operating reliability of the main braking portion 200 can be stably maintained.

[0091] Referring to FIG. 10, with reference to the back plate 5, the piston housing portion 120 and the rod housing portion 130 of the housing 100 are disposed on one side (front side), and the actuator 310 is disposed on the other side (back side). The back plate 5 is supported at its central portion by the chassis 8 of the vehicle body, and the chassis 8 is disposed on the other side of the actuator 310.

[0092] By disposing the parking braking portion 300 at a position farther from the rotation center portion C1 of the shoe 2 than the main braking portion 200, the actuator 310 of the parking braking portion 300 can be disposed at a distance farther from the rotation center portion C2 of the back plate 5. Accordingly, it is not necessary to apply a complicated structure in which the actuator 310 is disposed obliquely in consideration of interference with the chassis 8 or a stepped portion is formed in a portion of the housing portion 110 facing the chassis 8.

[0093] In other words, when positioning the actuator 310 on the same radial extension line L2 as the chassis 8 that supports the central part of the backplate 5, the actuator 310 does not tilt downward as it moves forward, in order to minimize interference with the chassis 8, and can be positioned alongside the rotation center C2 of the backplate 5.

[0094] This allows the piston housing 120 and rod housing 130 to be easily positioned on the same radial extension line L1 with respect to the rotation center C2 of the back plate 5, without the design and manufacturing difficulties of arranging them perpendicular to the output shaft of the actuator 310, while taking into account the tilt of the actuator 310 and the piston housing 120. Therefore, the manufacturability and machinability of the housing 100 can be further improved, and costs can be reduced.

[0095] Furthermore, by positioning the parking brake unit 300 further away from the rotation center C1 of the shoe 2 than the main brake unit 200, interference with the chassis 8 can be reliably avoided when positioning the actuator 310. This allows for a thicker housing unit 110, more specifically, a thicker lower rear portion of the housing unit 110 located between the actuator 310 and the chassis 8 (for example, the vertical thickness of the second fixing portion 114 located below the through extension portion 113), thereby ensuring stable rigidity of the housing unit 110.

[0096] Referring to Figures 4 to 6, the anti-rotation assembly 430 according to one embodiment of the present invention includes an anti-rotation groove 431 and an anti-rotation projection 432.

[0097] The anti-rotation groove 431 is formed at the rear end of the through extension 113 and is formed on the upper peripheral edge of the drive shaft housing 132, communicating with the drive shaft housing 132, and is formed recessed in the direction of extension of the drive shaft housing 132, i.e., forward. The anti-rotation projection 432 is formed on the upper part of the actuator 310, protruding upward, and is assembled by being fitted forward into the anti-rotation groove 431.

[0098] With the anti-rotation projection 432 fitted into the anti-rotation groove 431, the fastening portion 311 of the actuator 310 is naturally positioned to correspond to the second fixing portion 114. This makes assembly easy, as the second fastening member 420 can pass and enter the fastening portion 311 and the second fixing portion 114 in a continuous manner.

[0099] As described above, by fastening the second fastening member 420 to the second fixing part 114 with the anti-rotation groove 431 and the anti-rotation projection 432 fitted together, the load of rotational torque generated when the actuator 310 is driven can be stably supported, and the rotation and flow of the actuator 310 centered on the second fastening member 420 can be stably restrained. As a result, the actuator 310 can be firmly fastened to the housing 100 with just one second fastening member 420.

[0100] In one embodiment of the present invention, the first fixing portion 112 and the first fastening member 410 are arranged on the left and right sides with respect to the drive shaft housing portion 132, the second fixing portion 114 and the second fastening member 420 are arranged below the drive shaft housing portion 132, and the anti-rotation assembly portion 430 is arranged on the opposite side of the second fixing portion 114 with respect to the central part of the drive shaft housing portion 132, that is, above the drive shaft housing portion 132.

[0101] With the left and right sides of the housing 100 fixed to the back plate 5 by the first fastening member 410, the anti-rotation projection 432 is fastened to the anti-rotation groove 431, and the actuator 310 is fixed to the lower part of the housing 100 by the second fastening member 420, thereby firmly fastening the left and right sides and the upper and lower parts of the housing 100 to the back plate 5 and actuator 310, respectively.

[0102] According to the drum brake device 1 of the present invention having the above configuration, by disclosing an integrated structure of main brake and parking brake in which the main brake unit 200 and the parking brake unit 300 are mutually bound to a single housing 100, the main brake device and the parking brake device can be installed simultaneously through a simple process of installing the housing 100 on the back plate 5.

[0103] As a result, the present invention simplifies the manufacturing process compared to conventional methods in which the main braking device and the parking braking device were manufactured and managed separately, and assembly positions were set, adjusted, and designed to ensure play while considering mutual interference according to the specifications. It also makes it possible to further reduce the distance between the main braking unit 200 and the parking braking unit 300, enabling miniaturization and weight reduction, and improving space utilization.

[0104] Furthermore, according to the present invention, by fastening the first fastening member 410 and the second fastening member 420 to the housing 100, multiple components including the actuator 310, back plate 5, and housing 100 can be firmly bound together with the housing 100 and actuator 310 positioned on one side and the other side, respectively, with respect to the back plate 5.

[0105] Furthermore, according to the present invention, the first fastening member 410 and the second fastening member 420 are assembled with the housing 100 and actuator 310 positioned on one side and the other side of the back plate. Compared to an embodiment in which the housing 100 and actuator 310 are assembled first, and then the back plate 5 is assembled later, which requires forming a large hole on the back plate 5 for the actuator 310 to pass through, the rigidity and structural stability of the back plate 5 can be further improved.

[0106] Furthermore, according to the present invention, the actuator 310 can be easily separated independently by releasing the fastening of the second fastening member 420, making it easier to replace and inspect the actuator 310 compared to an embodiment in which a single fastening member continuously penetrates and fastens the actuator 310, back plate 5, and housing 100. [Explanation of symbols]

[0107] 1: Drum brake system 2: Shoe 5: Backplate 6: Through-hole section 100: Housing 110: Housing Department 111: Main body 111a: Third coupling groove 112: 1st fixed part 112a: Left side fixed part 112b: Right side fixed part 113: Penetration extension 114:Second fixed part 115: Foreign matter inflow prevention part 116:Connection part 117: Piston seal 118: Rod sealing section 119: Main body fixing part 120: Piston housing 121: Cylinder section 122: Hydraulic flow path section 130: Rod storage section 131: Rod cylinder section 132: Drive shaft housing 200: Main brake part 210: Piston 211: First connecting groove 220: Elastic member 300: Parking Brake Unit 310: Actuator 311: Fastening section 330: Rod section 331: Rotating Rod 332: Pushrod 333: Second connecting groove 410: First fastening member 420: Second fastening member 430: Anti-rotation assembly section 431: Anti-rotation groove 432: Anti-rotation protrusion

Claims

1. Housing and A main braking unit is provided on one side of the housing and is driven by hydraulic pressure during main braking to pressurize the shoe, A parking braking unit is provided on the other side of the housing and is driven by the electric force of the actuator to pressurize the shoe during parking braking, A first fastening member for fixing the housing to one surface of the back plate, The back plate includes a second fastening member that secures the actuator to the housing on the other side of the back plate, The housing includes a housing portion, a piston housing portion, and a rod housing portion. The aforementioned housing portion is The main body portion in which the piston housing portion and the rod housing portion are formed, A first fixing portion is formed on the main body portion and fixed to the back plate by the first fastening member, A through extension is formed at the end of the main body portion, passes through a through hole formed in the back plate, and is positioned on the other side of the back plate, to which the actuator is connected, The second fastening member is fastened to the second fixing portion, A drum brake device characterized by including the following:

2. The piston housing is formed to be hollow on one side of the housing, and the main braking section is provided there. The rod housing portion is formed to be hollow on the other side of the housing portion, the parking brake portion is provided therein, and is positioned away from the piston housing portion from the rotation center of the shoe. The drum brake device according to feature 1.

3. The first fixing part is, A left-side fixing portion is formed on the left side of the main body portion and is fixed to the back plate by the first fastening member, The main body portion includes a right-side fixing portion formed on the right side and fixed to the back plate by the first fastening member, The drum brake device according to claim 1, characterized in that the through extension is arranged between the left fixing portion and the right fixing portion.

4. The piston housing portion is The cylinder section in which the main braking unit is housed, It includes a hydraulic flow path that extends from both sides of the through extension to the cylinder and forms a flow path for supplying fluid to the inside of the cylinder, The drum brake device according to claim 1, characterized in that the second fixing portion is arranged in the lateral intermediate portion of the through extension portion at a distance from the hydraulic flow path portion.

5. The present invention further includes a rotation prevention assembly that restrains the rotation of the actuator around the second fastening member by fitting and assembling the housing and the actuator, The aforementioned rod housing section is The rod cylinder section in which the parking brake unit is housed, It includes a drive shaft housing that extends from the through extension to the rod cylinder and into which the output shaft of the actuator is retracted and connected to the parking brake section, The second fixing portion is arranged on one side of the drive shaft housing portion, spaced apart from the first fixing portion. The drum brake device according to claim 4, characterized in that the anti-rotation assembly is formed on the opposite side from the second fixing portion with reference to the central portion of the drive shaft housing portion.

6. The aforementioned anti-rotation assembly part is A rotation prevention groove is formed in communication with the peripheral edge of the drive shaft housing and recessed in the direction extending from the drive shaft housing, The drum brake device according to claim 5, characterized in that it includes a rotation-preventing projection formed protruding from the actuator and fitted into the rotation-preventing groove.

7. The aforementioned housing portion is The drum brake device according to claim 1, further comprising a foreign matter inflow prevention portion which is coupled to the side portion of the main body where the piston housing portion and the rod housing portion are located, and covers the peripheral edge of the piston housing portion and the peripheral edge of the rod housing portion.

8. The aforementioned foreign matter inflow prevention unit is A connecting portion is disposed between the opening of the piston housing and the opening of the rod housing, A piston sealing portion having a ring shape corresponding to the peripheral edge of the piston housing portion, formed continuously on one side of the connecting portion, and whose inner end is connected to the main braking portion, A rod sealing portion having a ring shape corresponding to the peripheral edge of the rod housing portion, formed continuously on the other side of the connecting portion, and whose inner end is connected to the parking brake portion, The drum brake device according to claim 7, characterized in that it includes a main body fixing portion formed on the connecting portion and fixed to the main body portion.

9. The piston housing and the rod housing are located on the same radial extension line with respect to the center of rotation of the back plate. The drum brake device according to claim 2, characterized in that the actuator is located on the same radial extension line as the chassis supporting the central part of the back plate and is positioned alongside the center of rotation of the back plate.

10. The main braking unit is, A piston is positioned at the end of the housing and moves to the outside of the housing by hydraulic pressure to pressurize the shoe, The drum brake device according to claim 1, further comprising an elastic member disposed inside the housing to reduce the impact force acting on the piston as it returns to the inside of the housing.

11. The aforementioned parking brake unit is, A gear section is disposed inside the housing and rotates in conjunction with the actuator, The drum brake device according to claim 1, characterized in that it includes a rod portion connected to the gear portion, which moves to the outside of the housing in conjunction with the gear portion and pressurizes the shoe.

12. The drum brake device according to claim 1, further comprising a rotation prevention assembly portion disposed at a distance from the second fastening member, which restrains the rotation of the actuator around the second fastening member by fitting assembly between the housing and the actuator.

13. The aforementioned anti-rotation assembly part is The housing and the actuator have a recessed anti-rotation groove portion formed on one side, The drum brake device according to claim 12, characterized in that it includes the housing and a rotation-preventing projection formed to protrude from the other side of the actuator and fitted into the rotation-preventing groove.

Images