KR20220003274A - Drum break apparatus - Google Patents

Abstract

The present invention relates to a drum brake apparatus comprising: a housing; a service braking unit which is installed on one side of the housing and presses a shoe by being driven by hydraulic pressure when service braking; and a parking braking unit which is installed on the other side of the housing and presses the shoe by being driven by electromotive force of an actuator when parking braking. The housing comprises: a main body unit in which a piston accommodation unit where the service braking unit is installed and a rod accommodation unit where the parking braking unit is installed are formed; and a foreign material inflow prevention unit which is coupled with a lateral side of the main body unit, on which opening parts of the piston accommodation unit and the rod accommodation unit are located, and seals a space between the piston accommodation unit and the service braking unit and a space between the rod accommodation unit and the parking braking unit. The present invention provides the integrated drum brake which can perform service braking and parking braking together.

Description

Drum brake device {DRUM BREAK APPARATUS}

The present invention relates to a drum brake apparatus, and more particularly, to a drum brake apparatus generating braking force by friction with a drum rotating together with a wheel.

In general, a drum brake is a device that generates braking force by friction with a drum rotating together with a wheel. It uses hydraulic pressure (main braking) or uses a cable connected to the parking brake lever to rub a shoe with a friction material with the drum ( Parking brake) It is a device to obtain braking force.

A conventional drum brake includes a drum, a pair of shoes disposed on a back plate to face the inner peripheral surface of the drum and having a friction material attached to the outer periphery, and a wheel cylinder for main steering that receives braking hydraulic pressure to move the shoe outward. In addition, the parking brake operating lever provided in the drum brake has one end shaft-coupled with the shoe and the other end connected to the parking brake lever provided next to the driver's seat through a cable.

Background art of the present invention is disclosed in Korean Patent Application Laid-Open No. 2018-0047519 (published on May 10, 2018, title of the invention: vehicle drum brake).

Conventionally, a main braking device for performing main braking and a parking braking device for performing parking braking are separately manufactured and installed. Accordingly, the main brake system and the parking brake system are separately manufactured and managed, and the productivity is reduced due to the hassle of setting, adjusting, designing, and assembling the assembly position that can secure the clearance in consideration of the mutual interference according to the specifications. There is a problem that the unit price decreases and the unit price increases.

Therefore, there is a need to improve it.

An object of the present invention is to provide an integrated drum brake device capable of performing both main braking and parking braking.

A drum brake device according to the present invention comprises: a housing; a main moving unit installed on one side of the housing, driven by hydraulic pressure during main actuation, and pressing the shoe; and a parking brake unit installed on the other side of the housing, driven by the electric force of an actuator during parking braking, and pressing the shoe, wherein the housing includes a piston receiving unit in which the main driving unit is installed, and the parking brake unit a body portion in which a rod receiving portion to be installed is formed; and a foreign substance inflow prevention part coupled to a side of the main body in which the open part of the piston accommodating part and the rod accommodating part is located, and sealing between the piston accommodating part and the main moving part, and between the rod accommodating part and the parking brake part It is characterized in that it contains;

The foreign matter inflow prevention part, a first sealing member installed in a first sealing groove formed on the inner surface of the piston receiving part, and sealing between the main moving part and the housing; and a second sealing member installed in a second sealing groove formed on the inner surface of the rod receiving portion and sealing a space between the parking brake and the housing.

The first sealing member may include: a first housing coupling part having a ring shape and fitted to the first sealing groove part; and a piston adhesion portion formed on the inner diameter portion of the first housing coupling portion and in contact with the main moving portion.

The second sealing member may include a second housing coupling part having a ring shape and being fitted and coupled to the second sealing groove part; and a rod adhesion portion formed on the inner diameter portion of the second housing coupling portion and in contact with the parking brake portion.

The foreign matter inflow prevention part, a sealing cover part disposed to cover the side of the body part; a piston sealing part which is formed to penetrate one side of the sealing cover part, and the edge part is connected to the main moving part; a rod sealing part formed to pass through the other side of the sealing cover part and having an edge part connected to the parking brake part; and a body fixing part continuously formed along the edge of the sealing cover part and fixed to the body part.

The main moving part is disposed in the open part of the piston accommodating part, the first coupling groove part is formed around which the piston sealing part is coupled, the piston is moved to the outside of the piston accommodating part by hydraulic pressure to press the shoe; and an elastic member disposed inside the housing and reducing an impact force acting on the piston returning to the inside of the housing.

The parking brake unit may include a gear unit rotating in association with the actuator; and a rod portion disposed in the open portion of the rod receiving portion, a second coupling groove portion to which the rod sealing portion is coupled is formed around the rod receiving portion, and moved to the outside of the housing in conjunction with the gear portion to press the shoe. characterized in that

The body part is formed in a slit shape connecting the piston accommodating part and the edge part of the rod accommodating part in communication with each other, and a slit groove part into which the body fixing part is fitted; and a third sealing groove formed to be recessed inside the piston accommodating part, the rod accommodating part, and the slit groove part, and to which the main body fixing part is coupled.

The third sealing groove portion may include: a first housing groove portion formed to extend along a portion of the inner surface of the piston accommodation portion that does not face the rod accommodation portion, and to which a portion of the body fixing portion is coupled; a second housing groove formed to extend along a portion of the inner surface of the rod receiving portion that does not face the piston receiving portion, and to which the other portion of the body fixing portion is coupled; and a third housing groove continuously formed between the first housing groove and the second housing groove and to which another part of the main body fixing portion is coupled.

The housing may further include a fixing part formed on the body part and fixed to the back plate.

The fixing portion may include: a fixing and fastening portion formed on both sides of the main body and fixed to the back plate together with the actuator by a fastening member; and a flow prevention part which is formed to protrude at a position corresponding to the main body part of the body part and is fitted into a through hole part formed in the back plate.

The piston accommodating part is formed to be hollow in a circumferential shape on the housing, and a cylinder part in which the main moving part is accommodated; and a hydraulic flow passage portion extending from the outer surface of the housing to the cylinder portion and forming a passage for supplying a fluid into the cylinder portion.

The rod accommodating part is formed to be hollow in a circumferential shape on the housing, and a rod cylinder part in which the parking brake part is accommodated; and a drive shaft accommodating part disposed at a set interval from the piston accommodating part, formed in communication with the rod cylinder part, and connected to the parking brake part through which the output shaft of the actuator is introduced.

The piston receiving part and the rod receiving part are positioned on the same radial extension line with respect to the rotational center of the back plate, and the rod receiving part is disposed at a position spaced apart from the rotational center of the shoe than the piston receiving part, and the actuator is located on the same radial extension line as the chassis supporting the central portion of the back plate, and is characterized in that it is arranged in parallel with the rotation center of the back plate.

The drum brake device according to the present invention discloses an integrated main braking and parking braking structure in which a main driving unit and a parking braking unit are mutually coupled to a single housing, so that the main braking unit and parking braking system through a simple process of installing the housing on a back plate Devices can be installed at the same time.

Accordingly, the present invention separately manufactures and manages the main brake system and the parking brake system, and sets, adjusts, designs, and assembles the assembly position that can secure clearance in consideration of mutual interference according to specifications. , the manufacturing process can be simplified, and the distance between the main engine and parking brake can be further reduced, so that it is possible to realize miniaturization and weight reduction, and it is possible to improve space utilization.

In addition, according to the present invention, the fluid inside the piston receiving part and the rod receiving part is prevented from being lost to the outside through the open part by the foreign substance inflow prevention part, and at the same time, foreign substances are prevented from penetrating into the piston receiving part and the rod receiving part. A sealing function can be implemented.

In addition, according to the present invention, when the foreign matter inflow prevention part is coupled to the side of the body part, at least a part can be inserted into the piston receiving part and the rod receiving part, so that the volume exposed to the outside of the housing can be significantly reduced or eliminated. . Accordingly, in arranging a plurality of parts on a limited installation space determined according to the specifications of the drum brake, there is no need to consider interference with other parts disposed outside the housing, so space utilization can be further improved, and the layout The degree of freedom can be further improved.

1 is a front perspective view showing an installation state of a drum brake device according to a first embodiment of the present invention.
2 is a rear perspective view showing an installation state of the drum brake device according to the first embodiment of the present invention.
3 is a sectional view showing a main part of the drum brake device according to the first embodiment of the present invention.
4 is a front perspective view showing the housing of the drum brake device according to the first embodiment of the present invention.
5 is a rear perspective view showing the housing of the drum brake device according to the first embodiment of the present invention.
6 is an enlarged view of the main part of FIG. 3 .
7 is a perspective view illustrating a foreign material inflow prevention unit of the drum brake device according to the first embodiment of the present invention.
8 is a sectional view showing a main part of a drum brake device according to a second embodiment of the present invention.
9 is a front perspective view showing a housing of a drum brake device according to a second embodiment of the present invention.
10 is a rear perspective view showing a housing of a drum brake device according to a second embodiment of the present invention.
11 is an enlarged view of the main part of FIG. 8 .
12 is a perspective view illustrating a foreign material inflow prevention unit of the drum brake apparatus according to the second embodiment of the present invention.
13 is a conceptual diagram illustrating the tolerance according to the arrangement of the main moving part and the parking braking part of the drum brake device according to the present invention.
14 is a cross-sectional view taken along line A-A' of FIG. 1 .

Hereinafter, embodiments of the drum brake apparatus according to the present invention will be described with reference to the accompanying drawings. In this process, the thickness of the lines or the size of the components shown in the drawings may be exaggerated for clarity and convenience of explanation. In addition, the terms to be described later are terms defined in consideration of functions in the present invention, which may vary according to intentions or customs of users and operators. Therefore, definitions of these terms should be made based on the content throughout this specification.

1 is a front perspective view showing an installation state of a drum brake apparatus according to a first embodiment of the present invention, and FIG. 2 is a rear perspective view showing an installation state of the drum brake apparatus according to the first embodiment of the present invention. 3 is a cross-sectional view showing a main part of the drum brake device according to the first embodiment of the present invention.

1 to 3 , the drum brake device 1 according to the first embodiment of the present invention includes a housing 100 , a main driving unit 200 , and a parking braking unit 300 .

The housing 100 is disposed between a pair of left and right shoes 2 . The main movement unit 200 is installed on one side of the housing 100 , and is driven by hydraulic pressure during main operation and presses the shoe 2 . The parking brake unit 300 is installed on the other side of the housing 100 , is driven by electric force during parking braking, and presses the shoe 2 . Both ends of the main driving unit 200 are installed to face one side of each of the pair of shoes 2 , and the parking braking unit 300 is aligned with the other side of the shoe 2 at a set interval from the main driving unit 200 . are usually installed

The fastening member 400 fixes the housing 100 and the actuator 310 of the parking brake unit 300 to a set position on the back plate 5 . The fastening member 400 passes through the actuator 310 and the back plate 5 and is fastened to the housing 100 , thereby coupling the actuator 310 , the back plate 5 , and the housing 100 to each other.

Referring to FIG. 3 , the housing 100 according to the first embodiment of the present invention includes a housing part 110 , a piston accommodating part 120 , and a rod accommodating part 130 .

The housing part 110 is a part constituting the basic frame of the housing 100 and has a single block shape. The piston accommodating part 120 is a part where the main moving part 200 is installed, and is formed to be hollow in one side of the housing part 110 . The rod accommodating part 130 is a part where the parking braking part 300 is installed, and is formed to be hollow with the piston accommodating part 120 and a set interval on the other side of the housing part 110 .

Figure 4 is a front perspective view showing the housing of the drum brake device according to the first embodiment of the present invention, Figure 5 is a rear perspective view showing the housing of the drum brake device according to the first embodiment of the present invention, 6 is an enlarged view of the main part of FIG. 3 .

3 to 5 , the housing part 110 according to the first embodiment of the present invention includes a body part 111 , a fixing part 112 , and a foreign substance inflow prevention part 115 .

The body part 111 is a device part constituting the main body of the housing part 110 , and the piston accommodating part 120 and the rod accommodating part 130 are hollowly formed therein. The piston accommodating part 120 and the rod accommodating part 130 are formed to extend laterally on the body part 111, and both ends are formed to be open.

The main body 111 and the actuator 310 are respectively disposed on one side and the other side of the back plate 5 with the back plate 5 interposed therebetween. Hereinafter, for convenience of explanation, one side on which the main body 111 is disposed is set to the front, and the other side on which the actuator 310 is disposed is set to the rear, based on the back plate 5, the arrangement relationship between the components. directions, etc. will be explained.

The fixing part 112 is a device part fixed to the back plate 5 , and is formed on a rear part of the body part 111 in contact with the back plate 5 . Referring to FIG. 5 , the fixing part 112 according to the first embodiment of the present invention includes a fixing fastening part 114 and a flow preventing part 113 .

The fixed fastening part 114 is a device part fixed to the back plate 5 by the fastening member 400 , and is formed to extend in the front-rear direction on both sides of the body part 111 . The fixing and fastening part 114 has a structure of a hole or a groove part, and a female screw part to which the fastening member 400 such as a bolt can be screwed is formed in the inner diameter part.

Referring to FIG. 2 , the fastening member 400 is fastened to the fixed fastening part 114 by sequentially penetrating the fastening parts 311 formed on both sides of the actuator 310 and the back plate 5 , so that the main body part 111 and the actuator 310 are fixed to one side and the other side of the back plate 5, respectively. By the fastening of the fastening member 400 , the main body 111 and the actuator 310 are installed in close contact with each other on the front and rear surfaces of the back plate 5 in a state of being coupled to each other.

The flow prevention part 113 is formed to protrude at a position corresponding to the main moving part 200 of the main body part 111 . A through-hole 6 for engagement with the flow preventing unit 113 is formed on the back plate 5 (see FIG. 14 ). For example, the through-hole part 6 may have a horizontally extending rectangular shape, and the flow prevention part 113 may have a rectangular cross-sectional shape corresponding thereto. The flow prevention part 113 has a shape corresponding to the through-hole part 6, and by being inserted into the through-hole part 6, the flow in the up-down direction, left-right direction, etc. is stably constrained while being fixed to the back plate 5. do.

The main body 111 passes through the back plate 5 from the rear of the actuator 310 and flows forward and backward by the fastening member 400 fastened to the front fixed fastening part 114, that is, the actuator 310. The flow in the output axial direction is stably restrained, and the flow in the radial direction of the actuator 310 is stably restrained by the flow preventing part 113 fitted in the through hole 6 formed in the back plate 5 .

The foreign material inflow prevention part 115 is a device part for sealing the opening part of the piston accommodating part 120 and the opening part of the rod accommodating part 130, and is made of a material having ductility or flexibility. The foreign matter inflow prevention part 115 is coupled to the side where the open part of the piston receiving part 120 and the rod receiving part 130 of the main body part 111 is located, and the inner surface of the piston receiving part 120 and the main moving part ( 200) seals the gap formed between the piston 210 and the gap formed between the inner surface of the rod accommodating part 130 and the push rod 332 of the parking brake part 300.

7 is a perspective view illustrating a foreign material inflow prevention unit of the drum brake device according to the first embodiment of the present invention. More specifically, FIG. 7A is a perspective view showing the first sealing member 115A of the foreign material inflow prevention part 115 of the drum brake device 1 according to the first embodiment of the present invention, and FIG. (b) is a perspective view showing the second sealing member 115B of the foreign material inflow prevention part 115 of the drum brake device 1 according to the first embodiment of the present invention.

6 and 7, the foreign matter inflow prevention part 115 according to the first embodiment of the present invention is a first sealing member 115A for sealing the gap between the piston receiving part 120 and the piston 210. And, it includes a second sealing member (115B) for sealing the gap between the rod receiving portion 130 and the push rod (332).

The first sealing member 115A is installed in the first sealing groove 111a formed on the inner surface of the piston accommodating part 120, and the piston 210 of the main moving part 200 and the piston accommodating part of the housing 100 ( 120) to seal the gap. The first sealing member 115A according to the first embodiment of the present invention includes a first housing coupling part 1151 and a piston adhesion part 1152 .

The first housing coupling portion 1151 has a circular ring shape and is fitted and coupled to the first sealing groove portion 111a. The piston accommodating part 120 has a circular longitudinal cross-sectional shape, and the first sealing groove part 111a is radially recessed on the inner surface of the piston accommodating part 120, and the circumference of the piston accommodating part 120 is formed. It is formed to extend continuously in the circumferential direction along the

The first housing coupling portion 1151 has a diameter and a transverse width corresponding to the first sealing groove portion 111a, is fitted into the first sealing groove portion 111a, and is in pressure contact with the inner surface of the first sealing groove portion 111a, whereby the piston It is assembled and fixed on the inner surface of the accommodating part 120 .

The piston adhesion part 1152 is formed on the inner diameter part of the first housing coupling part 1151, and protrudes to the outside of the first sealing groove part 111a of the piston 210 accommodated in the piston accommodating part 120. contact the perimeter. A gap between the piston accommodating part 120 and the piston 210 by the first housing coupling part 1151 press-contacted to the piston accommodating part 120 and the piston accommodating part 1152 in close contact with the circumference of the piston 210 . can be sealed.

The second sealing member 115B is installed in the second sealing groove 111b formed on the inner surface of the rod accommodating part 130 , and the push rod 332 of the parking braking part 300 and the rod accommodating part of the housing 100 . Seal between 130. The second sealing member 115B according to the first embodiment of the present invention includes a second housing coupling part 1153 and a rod adhesion part 1154 .

The second housing coupling part 1153 has a circular ring shape and is fitted and coupled to the second sealing groove part 111b. The rod accommodating part 130 has a circular longitudinal cross-sectional shape, and the second sealing groove part 111b is radially recessed on the inner surface of the rod accommodating part 130, and the circumference of the rod accommodating part 130 is formed. It is formed to extend continuously in the circumferential direction along the

The second housing coupling portion 1153 has a diameter and a transverse width corresponding to the second sealing groove portion 111b, is fitted into the second sealing groove portion 111b, and is in pressure contact with the inner surface of the second sealing groove portion 111b, whereby the rod It is assembled and fixed on the inner surface of the accommodating part 130 .

The rod adhesion part 1154 is formed on the inner diameter part of the second housing coupling part 1153, and protrudes to the outside of the second sealing groove part 111b, and the push rod 332 accommodated in the rod accommodating part 130 inside. tangent to the perimeter of Between the rod accommodating part 130 and the push rod 332 by the second housing coupling part 1153 press-contacted to the rod accommodating part 130 and the rod adhesive part 1154 in close contact with the periphery of the push rod 332 . gap can be sealed.

A fluid for creating a hydraulic atmosphere may be introduced into the piston accommodating part 120 , and a lubricant for smooth operation of the gear part 320 and the rod part 330 may be introduced into the rod accommodating part 130 . have. According to the first sealing member 115A and the second sealing member 115B, the piston accommodating part 120 and the rod accommodating part 130 prevent the fluid inside the opening part from being lost to the outside, and at the same time, the piston accommodating part ( It is possible to prevent foreign substances from penetrating into the 120) and the rod receiving part 130. Accordingly, it is possible to secure the operational stability of the main driving unit 200 and the parking braking unit 300 .

In addition, by disposing the first sealing member 115A and the second sealing member 115B in the piston receiving part 120 and the rod receiving part 130, the first sealing member 115A and the second sealing member ( Since the 115B is not exposed to the outside of the housing 100 and does not occupy a separate volume, it does not interfere with other components disposed outside the housing 100 . Accordingly, space utilization and layout freedom can be further improved by arranging a plurality of parts on a limited installation space determined according to the specifications of the drum brake.

4 and 5 , the piston accommodating part 120 according to the first embodiment of the present invention includes a cylinder part 121 and a hydraulic oil passage part 122 .

The cylinder part 121 is a space part in which the main moving part 200 is accommodated, and is formed to be hollow in a cylindrical shape on the housing part 110 . The cylinder part 121 is formed to cross the housing part 110 in the left and right direction, and both ends are formed to be open on the side surface of the housing part 110 .

The cylinder part 121 has a circular cross-sectional shape, and the first sealing groove part 111a to which the first sealing member 115A is fitted is formed to be recessed in the radial direction on the inner surface of the cylinder part 121 . The first sealing groove portion 111a is formed to be radially depressed on the inner surface of the cylinder portion 121 , and is formed to extend continuously along the circumference of the cylinder portion 121 , that is, in the circumferential direction. The first sealing member 115A has a ring shape and is assembled by being press-contacted to the first sealing groove portion 111a.

The hydraulic flow path part 122 is a part constituting a supply path for a fluid for creating a hydraulic atmosphere in the cylinder part 121 , and is formed to extend from the outer surface of the housing part 110 to the cylinder part 121 . The outer end of the hydraulic flow passage part 122 is formed to be opened on the flow prevention part 113 provided on the rear surface of the main body part 111 .

Since the flow prevention part 113 is exposed to the rear of the back plate 5 through the through-hole part 6 , a plurality of parts including a pair of shoes 2 installed in front of the back plate 5 and the like The fluid can be stably supplied from the rear of the back plate 5 to the inside of the cylinder part 121 through the hydraulic flow passage part 122 without the interference of the.

The inner end of the hydraulic flow passage part 122 communicating with the cylinder part 121 is formed to face the elastic member 220 of the main moving part 200 installed inside the cylinder part 121 . The left and right pair of hydraulic flow passages 122 gradually narrow in a V-shape from the outer end toward the inner end. Accordingly, the fluid introduced into the hydraulic flow passage 122 is directed toward the elastic member 220 disposed in the middle portion of the cylinder portion 121 .

According to the structure of the hydraulic flow passage part 122 , the fluid introduced into the cylinder part 121 interferes with the elastic member 220 and can be evenly distributed and diffused into the interior of the cylinder part 121 , and the cylinder part It is possible to solve the problem of repeatedly applying an impact to the inner wall of the cylinder part 121 or one side of the piston 210 while the fluid is introduced into the interior of the 121 .

4 and 5 , the rod accommodating part 130 according to the first embodiment of the present invention includes a rod cylinder part 131 and a driving shaft accommodating part 132 .

The rod cylinder part 131 is a space part in which the rod part 330 of the parking brake part 300 and the driven gear 322 of the gear part 320 are accommodated, and is formed to be cylindrically hollow on the housing part 110 . do. The rod cylinder part 131 crosses the housing part 110 in the left and right directions and is disposed in parallel with the cylinder part 121 , and both ends are formed to be open on the side surface of the housing part 110 .

The rod cylinder part 131 has a circular cross-sectional shape, and the second sealing groove part 111b to which the second sealing member 115B is fitted and coupled is formed to be recessed in the radial direction on the inner surface of the rod cylinder part 131 . . The second sealing groove portion 111b is formed to be radially recessed on the inner surface of the rod cylinder portion 131 , and is formed to extend continuously along the circumference of the rod cylinder portion 131 , that is, in the circumferential direction. The second sealing member 115B has a ring shape and is assembled by being press-contacted to the second sealing groove portion 111b.

The drive shaft accommodating part 132 is a space in which the drive gear 321 of the gear part 320 of the parking brake part 300 and the output shaft of the actuator 310 are accommodated, and is formed in communication with the load cylinder part 131 . The output shaft of the actuator 310 is introduced into the housing 110 through the drive shaft accommodating part 132 , and is connected to the gear part 320 of the parking brake part 300 .

The rod cylinder part 131 is disposed at a set interval from the piston receiving part 120 . The distance between the rod cylinder part 131 and the piston accommodating part 120 can be freely stretched and variable in a range in which mutual interference and communication are not possible. As the distance between the rod cylinder part 131 and the piston accommodating part 120 is reduced, the volume and weight of the housing part 110 may be reduced. In addition, according to this structure, it is realized by reflecting all of the casing thickness of the main brake device, the casing thickness of the parking brake device, and the clearance between the main brake device and the parking brake device in the prior art, in which the main brake device and the parking brake device were separately provided. It is possible to realize miniaturization to a degree that was impossible to do.

1 and 3 , the main moving part 200 according to the first embodiment of the present invention includes a piston 210 and an elastic member 220 .

The piston 210 presses the shoe 2 toward the drum (not shown) or releases the pressurizing while moving in and out of the cylinder part 121 along the cylinder part 121 by hydraulic pressure. In the first embodiment of the present invention, a pair of left and right pistons 210 are disposed at both ends of the cylinder unit 121 . A shoe pressing portion 212 in contact with the shoe 2 is formed at the end of the piston 210 . The shoe pressing unit 212 transmits the pressing force to the shoe 2 or releases the pressing force for rotating the shoe 2 according to the movement position of the piston 210 .

As the pressure inside the cylinder unit 121 increases when the fluid flows in through the hydraulic flow path unit 122, the left and right pair of pistons 210 move by extension in which the mutual separation distance is further extended, and the left and right pair of shoes (2) is pushed out. Through this process, the subject movement is performed. As the pressure inside the cylinder part 121 is reduced when the fluid is discharged through the hydraulic flow passage part 122, the left and right pair of pistons 210 make a reduced movement to bring the distance between them closer to each other, and the left and right pair of shoes (2) is released from the push. Through this process, the subject movement is released.

The elastic member 220 is disposed inside the cylinder part 121 , and is disposed between the pair of pistons 210 . The elastic member 220 is disposed between the pair of pistons 210 , thereby preventing the pair of pistons 210 from directly colliding with each other while returning to the inside of the cylinder part 121 , and on the piston 210 . Reduces the impact force acting on it. In addition, the elastic member 220 may interfere with the fluid flowing between the pair of pistons 210 through the hydraulic flow passage 122 to evenly distribute and spread the hydraulic pressure. As the elastic member 220, an elastic spring or the like may be applied.

1 and 3 , the parking brake unit 300 according to the first embodiment of the present invention includes an actuator 310 , a gear unit 320 , and a rod unit 330 .

The gear unit 320 is a device unit that receives rotational driving force from the actuator 310 and transmits it to the rod unit 330 , and has a structure of a worm wheel gear and is disposed inside the rod receiving unit 130 . The drive gear 321 of the gear unit 320 has a worm gear structure, is installed in the drive shaft accommodating part 132, and is coaxially connected with the output shaft of the actuator 310 introduced into the drive shaft accommodating part 132. . The driven gear 322 of the gear unit 320 has a wheel gear meshing with the worm gear, and is disposed in the middle of the rod cylinder unit 131 .

The rod part 330 is a device part that converts the rotational displacement of the gear part 320 into a linear displacement and transmits it to the shoe 2 , and includes a rotational rod 331 and a push rod 332 , and a rod cylinder part 131 . is installed on The rotating rod 331 is made of a single rod member, and is connected coaxially with the driven gear 322 . The push rod 332 is provided with a screw coupling portion with the rotation rod 331 and is coupled around both ends of the rotation rod 331 , and is interlocked with the rotation and movement of the rotation rod 331 to the inside and outside of the rod cylinder unit 131 . It moves and presses the shoe (2) toward the drum or releases the pressurization.

In the first embodiment of the present invention, a pair of left and right push rods 332 are disposed at both ends of the rod cylinder unit 131 . The end of the push rod 332 has a slit shape into which the end of the shoe 2 can be inserted. can be installed.

When the actuator 310 is driven in the forward direction, the rotational force of the actuator 310 is transmitted to the rotating rod 331 through the gear unit 320 , and the rotating rod 331 is rotated in the forward direction in conjunction with the gear unit 320 . . At this time, the pair of push rods 332 move along the rotation rod 331 to extend the separation distance from each other, and push the left and right pair of shoes 2 .

While the shoe is being pressed with the piston 210, parking braking is performed through the same process as above. When the actuator 310 is driven in the reverse direction, the pair of push rods 332 perform a reduced movement to make the distance between each other closer, and release the pushing of the pair of left and right shoes 2 . Through this process, the runner brake is released.

8 is a sectional view showing a main part of a drum brake device according to a second embodiment of the present invention.

Referring to FIG. 8 , the foreign material inflow prevention unit 115 according to the second embodiment of the present invention is a material having ductility or flexibility, similarly to the foreign material inflow prevention unit 115 according to the first embodiment of the present invention. To seal the opening of the piston accommodating part 120 and the opening of the rod accommodating part 130, including, respectively, are coupled to both sides of the body part 111.

However, the foreign matter inflow prevention unit 115 according to the second embodiment of the present invention is compared with the foreign matter inflow prevention unit 115 according to the first embodiment of the present invention, the piston receiving part 120 and the rod receiving part 130 ), rather than being installed in the interior, has a structure of an integrated stopper covering the side of the main body 111 including the opening of the piston accommodating part 120 and the opening of the rod accommodating part 130 .

That is, the foreign matter inflow prevention unit 115 according to the second embodiment of the present invention is compared with the foreign material inflow prevention unit 115 according to the first embodiment of the present invention, the piston receiving part 120 and the piston 210 It has an integrated structure that can cover the gap between the rod accommodating part 130 and the gap between the push rod 332 at once. Hereinafter, in the description of the present invention, the foreign material inflow prevention part 115 according to the second embodiment of the present invention having an integrated structure as described above is referred to as a third sealing member 115C.

9 is a front perspective view showing a housing of a drum brake device according to a second embodiment of the present invention, and FIG. 10 is a rear perspective view showing a housing of the drum brake device according to the second embodiment of the present invention.

8 to 10 , the housing 100 according to the second embodiment of the present invention has a housing part 110 and a piston receiving part 120 like the housing 100 according to the first embodiment of the present invention. , has a structure including the rod receiving portion 130, but compared to the housing 100 according to the first embodiment of the present invention, the first sealing groove portion (111a) and the second sealing groove portion on the body portion 111 ( 111b) is not formed, but has a structure in which a slit groove portion 111c and a third coupling groove portion 111d are formed.

The slit groove portion 111c is formed in a slit shape connecting the edge portions of the piston receiving portion 120 and the rod receiving portion 130 in communication with each other. The slit groove part (111a) has one side extending in the longitudinal direction (up and down direction) from one transverse end of the piston receiving part 120 to the transverse one end (front end) of the rod receiving part 130, and the piston receiving part ( A pair including the other side extending in the longitudinal direction from the other transverse end (rear end) of 120 to the other transverse end of the rod receiving part 130 is provided.

When the rod accommodating part 130 is disposed above the piston accommodating part 120, the upper edge of the open part of the rod accommodating part 130, the lower edge of the open part of the piston accommodating part 120, and the front and rear sides The pair of slit groove portions 111c form a space portion having a continuous oval shape.

The edge of the third sealing member 115C has the shape of an elliptical ring corresponding thereto, the upper edge of the rod accommodating part 130, the lower edge of the piston accommodating part 120, and a pair of front and rear slits The groove portion 111c is inserted into the continuously formed oval space portion. At this time, the upper part of the edge of the third sealing member 115C is located inside the rod receiving part 130 , the middle part is located inside the slit groove part 111c , and the lower part is located inside the piston receiving part 120 .

The third coupling groove part 111d is a device part to which the body fixing part 119 formed on the edge of the third sealing member 115C is coupled, and the piston receiving part 120 and the rod receiving part 130 forming an elliptical space part. , is formed to be recessed in the interior of the slit groove portion (111c). The third coupling groove portion 111d according to the second embodiment of the present invention includes a first housing groove portion 1111 , a second housing groove portion 1112 , and a third housing groove portion 1113 .

The first housing groove 1111 is formed to extend along a portion of the inner surface of the piston receiving part 120 that does not face the rod receiving part 130 . The second housing groove 1112 is formed to extend along a portion of the inner surface of the rod receiving portion 130 that does not face the piston receiving portion 120 .

When the rod accommodating part 130 is disposed on the upper side of the piston accommodating part 120 , the lower part of the rod accommodating part 130 and the upper part of the piston accommodating part 120 face each other. At this time, a portion of the inner surface of the piston accommodating part 120 that does not face the rod accommodating part 130 becomes the lower part of the piston accommodating part 120 , and the piston accommodating part 120 among the inner surfaces of the rod accommodating part 130 . A portion that does not face the rod accommodating portion 130 is the upper portion.

The first housing groove portion 1111 is formed to be radially recessed on the inner surface of the piston accommodating part 120 , and is formed to extend in a semicircular shape along the lower portion of the piston accommodating part 120 . The second housing groove portion 1112 is formed to be radially recessed on the inner surface of the rod receiving portion 130 , and is formed to extend in a semicircular shape along the upper portion of the inner portion of the rod receiving portion 130 .

The third housing groove portion 1113 is formed to be recessed inside the slit groove portion 111c, and has a linear shape continuously connected to the first housing groove portion 1111 and the second housing groove portion 1112 . The third housing groove portion 1113 is formed as a pair including one side connecting the front portions of the first housing groove portion 1111 and the second housing groove portion 1112 to each other, and the other side connecting the rear portions to each other.

The first housing groove portion 1111 , the second housing groove portion 1112 , and the third housing groove portion 1113 together form an elliptical shape, and the body fixing portion 119 of the third sealing member 115C having an elliptical ring shape. The lower, upper, and middle portions of the are fitted into the first housing groove portion 1111, the second housing groove portion 1112, and the third housing groove portion 1113, respectively, and are coupled and fixed.

11 is an enlarged view of the main part of FIG. 8, and FIG. 12 is a perspective view illustrating a foreign material inflow prevention unit of the drum brake apparatus according to the second embodiment of the present invention.

11 and 12, the foreign matter inflow prevention part 115 according to the second embodiment of the present invention, that is, the third sealing member 115C, is a sealing cover part 116, a piston sealing part 117, It includes a rod sealing part 118 and a body fixing part 119 .

The sealing cover part 116 is disposed to cover the opening of the piston accommodating part 120 and the rod accommodating part 130 formed on the side surface of the body part 111 . The sealing cover part 116 has an elliptical shape as a whole so as to cover the openings of the piston accommodating part 120 and the rod accommodating part 130 . The edge portion of the sealing cover portion 116 has an elliptical ring shape that protrudes toward a middle portion in the extending direction of the piston receiving portion 120 and the rod receiving portion 130 .

The piston sealing part 117 is a device part for sealing the piston accommodating part 120, and is formed to pass through the lower part of the sealing cover part 116 in a ring shape. The rod sealing part 118 is a device part for sealing the rod receiving part 130 , and is formed to penetrate through the upper portion of the sealing cover part 116 in a ring shape.

The inner end 117a of the piston sealing part is fitted into the first coupling groove 211 formed in the piston 210 of the main moving part 200 to be airtightly assembled and connected to the piston 210 . The inner end 118a of the rod sealing unit is fitted into the second coupling groove 333 formed around the push rod 332 of the parking brake unit 300 to be airtightly assembled and connected to the push rod 332 .

The first coupling groove portion 211 is formed to extend in a circular shape along the circumference of the outer surface of the piston 210, and is formed to be depressed in the reverse radial direction (center direction). The second coupling groove portion 333 is formed to extend in a circular shape along the periphery of the outer surface of the push rod 332, and is formed to be depressed in the reverse direction.

The body fixing part 119 is a device coupled to the body part 111 and is formed at the end of the edge of the sealing cover part 116 having an oval shape. The body fixing part 119 has an elliptical ring shape continuously extending along the sealing cover part 116, and is fitted and fixed in the elliptical third coupling groove part 111a formed on the body part 111.

The main body fixing part 119 is fitted and fixed in the third coupling groove part 111a, and the inner peripheral part 117a of the piston sealing part is fitted and connected to the first coupling groove part 211, and the inner peripheral part 117a of the piston sealing part is removed. By fitting and connecting the two coupling grooves 333 , sealing of the open portion side of the cylinder portion 121 and the rod cylinder portion 131 is achieved.

According to the third sealing member 115C, with only one component corresponding to the third sealing member 115C, the fluid inside the piston accommodating part 120 and the rod accommodating part 130 is lost to the outside through the opening. At the same time, it is possible to implement a sealing function to prevent foreign substances from penetrating into the piston receiving part 120 and the rod receiving part 130 at the same time. Accordingly, according to the second embodiment of the present invention, compared to the first embodiment of the present invention including the first sealing member 115A and the second sealing member 115B, the number of parts can be further reduced, Assembly property can be further improved.

In addition, the edge portion and the body fixing portion 119 of the third sealing member 115C are not around the outer surface of the body portion 111, but the piston receiving portion 120, the rod receiving portion 130, the slit groove portion ( 111c), it is not exposed to the outside of the housing 100 , and does not occupy a separate volume, so that it does not interfere with other components disposed outside the housing 100 . Accordingly, space utilization and layout freedom can be further improved by arranging a plurality of parts on a limited installation space determined according to the specifications of the drum brake.

13 is a conceptual diagram illustrating a tolerance according to the arrangement of the main driving unit and the parking braking unit of the drum brake device according to the present invention, and FIG. 14 is a cross-sectional view taken along line A-A' of FIG. 1 .

When the drum brake is used, the friction pad 3 attached to the shoe 2 is worn, and the clearance between the shoe 2 and the drum (not shown) varies due to the wear of the friction pad 3 . The gap between the shoe 2 and the drum may be corrected to be kept constant by the parking brake unit 300 even if the friction pad 3 is worn.

The length of the parking brake unit 300 is elastically variable depending on the driving state of the actuator 310, and the pair of shoes 2 are pressed in a mutually proximate direction by the elastic member 7 while the parking brake unit 300 is ) according to the length of the substantially mutually spaced distance can be determined.

When the actuator 310 is driven in the forward direction, the length of the parking braking unit 300 is extended and the pair of left and right shoes 2 are pushed in a direction to be spaced apart from each other to perform parking braking. When the actuator 310 is driven in the reverse direction, the parking brake is released as the pressing force pushing the shoe 2 is released. can

Referring to FIGS. 1 and 14 , the rod accommodating part 13 is disposed at a position spaced apart from the pivot accommodating part 120 from the rotational center C1 of the shoe 2 . This means that the parking braking unit 300 installed in the rod accommodating part 13 is spaced apart from the rotational center C1 of the shoe 2 rather than the main driving part 200 installed in the piston accommodating part 120 . it means.

13( a ) shows the tolerance d1 of the parking brake unit 300 in the embodiment in which the main driving unit 200 is disposed at a position spaced apart from the rotation center C1 of the shoe 2 rather than the parking braking unit 300 . ) shows the relative size of the tolerance d2 of the main body 200 with respect to the . And, in the embodiment in which the parking braking unit 300 is disposed at a position spaced apart from the rotation center C1 of the shoe 2 rather than the main driving unit 200, Fig. 13 (b) shows the tolerance of the parking braking unit 300 It shows the relative size of the tolerance d2 of the main body 200 with respect to (d1).

When the main driving unit 200 is disposed at a position more spaced apart from the rotation center C1 of the shoe 2 than the parking braking unit 300, the return position of the shoe 2 by the parking braking unit 300 as described above; Alternatively, when the tolerance d1 is generated in adjusting and correcting the gap between the shoe and the drum, the tolerance d2 of the main driving unit 200 is the tolerance of the parking brake unit 300 as shown in FIG. 13(a). It is formed larger than (d1) (d2>d1).

When the rod accommodating part 130 is disposed at a position spaced apart from the piston accommodating part 120 from the rotational center part C1 of the shoe 2, the tolerance d2 of the main moving part 200 is shown in FIG. As shown, it is formed to be smaller than the tolerance d1 of the parking brake unit 300 (d2<d1). Accordingly, even if the parking brake unit 300 has the same degree of tolerance d1 with respect to the shoe 2 , the main moving unit 200 is farther than the parking brake unit 300 from the rotation center C1 of the shoe 2 . It has a smaller tolerance d2 compared to the embodiment arranged in .

By arranging the rod accommodating part 130 at a position spaced apart from the piston accommodating part 120 from the rotation center part C1 of the shoe 2, the tolerance d1 of the parking braking part 300 generated to the same degree as above. For this, the tolerance d2 of the main body 200 can be clearly reduced. Accordingly, even if the tolerance d2 is generated in the process of correcting the gap between the shoe 2 and the drum by the parking brake unit 300 , the operational reliability of the main driving unit 200 can be stably maintained.

Referring to FIG. 14 , the piston receiving part 120 and the rod receiving part 130 of the housing 100 are disposed on one side (front side) of the back plate 5 as a reference, and the actuator is on the other side (rear side). 310 is disposed. The back plate 5 has a de-central portion supported by the chassis 8 of the vehicle body, and the chassis 8 is disposed on the other side of the actuator 310 .

By arranging the parking brake unit 300 at a position more spaced apart from the rotation center portion C1 of the shoe 2 than the main movement portion 200 , the actuator 310 of the parking brake unit 300 is moved to the rotation center of the back plate 5 . It can be arranged more spaced apart from (C2). Accordingly, there is no need to tilt the actuator 310 in consideration of interference with the chassis 8 , or to apply a complicated structure of forming a step in a portion of the housing 110 facing the chassis 8 .

That is, in arranging the actuator 310 on the same radial extension line L2 as the chassis 8 supporting the central portion of the backplate 5 , the actuator 310 is positioned to minimize interference with the chassis 8 . Without tilting downward toward the front, it can be arranged in parallel with the rotation center portion C2 of the back plate 5 .

Accordingly, the piston accommodating part 120 without difficulty in designing and manufacturing for arranging to be arranged in a direction perpendicular to the output shaft of the actuator 310 in consideration of the inclination of the actuator 310 or the piston accommodating part 120 in a complex manner. ) and the rod receiving portion 130 can be easily arranged on the same radial extension line (L1) with respect to the rotation center portion (C2) of the back plate (5). Accordingly, the manufacturability and processability of the housing 100 may be further improved, and cost reduction may be realized.

In addition, by arranging the parking braking unit 300 at a position more spaced apart from the rotation center C1 of the shoe 2 than the main driving unit 200, the interference with the chassis 8 in disposing the actuator 310 is stably prevented. Since it can be avoided, the thickness of the housing part 110, more specifically, the thickness of the lower part of the rear part of the housing part 110 positioned between the actuator 310 and the chassis 8 (eg, flow prevention) The thickness of the part 113 in the vertical direction) can be applied thicker, so that the rigidity of the housing part 110 can be stably secured.

The fastening member 400 includes a pair of fixed fastening parts 114 formed on the left and right sides of the main body 11 and a pair of fastening parts 311 formed on the left and right parts of the actuator 310 to each other. For binding, left and right pairs are provided. In a state in which the housing 100 and the actuator 310 are disposed at the front and rear of the back plate 5, respectively, by fastening the left and right pair of fastening members 400 as described above, the actuator 310, the back plate ( 5), it is possible to fix the housing 100 and the actuator 310 to a set position on the back plate 5 while firmly bonding the housing 100 to each other.

According to the drum brake device 1 according to the present invention having the above configuration, the main braking and parking braking integrated structure in which the main driving unit 200 and the parking braking unit 300 are mutually bound to one housing 100 is disclosed. Accordingly, 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 .

Accordingly, according to the present invention, the main brake system and the parking brake system are separately manufactured and managed, and according to the specifications, an assembly position that can secure play is set, adjusted, designed, and assembled in consideration of mutual interference. In comparison, the manufacturing process can be simplified, the distance between the main driving unit 200 and the parking braking unit 300 can be further reduced, so that miniaturization and weight reduction can be realized, and space utilization can be improved.

In addition, according to the present invention, the piston accommodating part 120 and the rod accommodating part 130 prevent the fluid inside the piston accommodating part 120 and the rod accommodating part 130 from being lost to the outside through the opening part by the foreign substance inflow prevention part 115, and at the same time, the piston accommodating part 120 ) and a sealing function to prevent foreign substances from penetrating into the rod receiving part 130 can be implemented.

In addition, according to the present invention, when the foreign matter inflow prevention part 115 is coupled to the side of the body part 111 , at least a part can be inserted into the piston receiving part 120 and the rod receiving part 130 , and the housing The volume exposed to the outside of (100) can be significantly reduced or eliminated. Accordingly, in arranging a plurality of parts on a limited installation space determined according to the specifications of the drum brake, there is no need to consider interference with other parts disposed on the outside of the housing 100, so space utilization can be further improved. and the degree of freedom in layout can be further improved.

1: drum brake device 2: shoe
5: back plate 6: through hole part
100: housing 110: housing unit
111: body portion 111a: first sealing groove portion
111b: second sealing groove 111c: slit groove
111d: third sealing groove portion 112: fixed portion
113: flow prevention part 114: fixed fastening part
115: foreign matter inflow prevention part 115A: first sealing member
115B: second sealing member 115C: third sealing member
116: sealing cover part 117: piston sealing part
117a: inner end of the sealing portion of the piston 118: sealing portion of the rod
118a: inner end of rod sealing part 119: body fixing part
120: piston receiving part 121: cylinder part
122: hydraulic flow passage 130: rod receiving portion
131: rod cylinder part 132: drive shaft receiving part
200: main east 210: piston
211: first coupling groove 220: elastic member
300: parking brake 310: actuator
311: fastening part 330: rod part
331: rotating rod 332: push rod
333: second coupling groove 400: fastening member
1111: first housing groove 1112: second housing groove
1113: third housing groove portion 1151: first housing coupling portion
1152: piston adhesion part 1153: second housing coupling part
1154: rod adhesion part

Claims (14)

housing;
a main moving unit installed on one side of the housing, driven by hydraulic pressure during main actuation, and pressing the shoe; and
and a parking brake unit installed on the other side of the housing, driven by the electric power of an actuator during parking braking, and pressing the shoe;
The housing is
a main body in which a piston accommodating part in which the main moving part is installed, and a rod accommodating part in which the parking braking part is installed are formed; and
a foreign substance inflow prevention part coupled to a side of the main body in which the open part of the piston accommodating part and the rod accommodating part is located, and sealing between the piston accommodating part and the main moving part, and between the rod accommodating part and the parking brake; A drum brake device comprising a.
According to claim 1,
The foreign matter inflow prevention unit,
a first sealing member installed in a first sealing groove formed on the inner surface of the piston receiving part and sealing a space between the main moving part and the housing; and
and a second sealing member installed in a second sealing groove formed on the inner surface of the rod receiving part and sealing a space between the parking brake part and the housing.
3. The method of claim 2,
The first sealing member,
a first housing coupling part having a ring shape and fitted to the first sealing groove part; and
The drum brake device comprising a; a piston contact portion formed on the inner diameter portion of the first housing coupling portion and in contact with the main moving portion.
3. The method of claim 2,
The second sealing member,
a second housing coupling part having a ring shape and being fitted and coupled to the second sealing groove part; and
and a rod adhesion part formed on the inner diameter part of the second housing coupling part and contacting the parking brake part.
According to claim 1,
The foreign matter inflow prevention unit,
a sealing cover part disposed to cover the side part of the body part;
a piston sealing part which is formed to penetrate one side of the sealing cover part, and the edge part is connected to the main moving part;
a rod sealing part formed to pass through the other side of the sealing cover part and having an edge part connected to the parking brake part; and
and a main body fixing part continuously formed along an edge of the sealing cover part and fixed to the main body part.
6. The method of claim 5,
The subject dong is,
a piston disposed in the open part of the piston accommodating part, a first coupling groove part to which the piston sealing part is coupled is formed around the piston accommodating part, the piston being moved to the outside of the piston accommodating part by hydraulic pressure and pressing the shoe; and
and an elastic member disposed inside the housing and reducing an impact force acting on the piston returning to the inside of the housing.
6. The method of claim 5,
The parking brake unit,
a gear unit rotating in association with the actuator; and
It is disposed in the open portion of the rod accommodating portion, a second coupling groove portion is formed around which the rod sealing portion is coupled, the rod portion is moved to the outside of the housing in conjunction with the gear portion to press the shoe; Drum brake device featuring.
6. The method of claim 5,
The body part,
a slit groove formed in a slit shape connecting the piston receiving part and an edge of the rod receiving part in communication with the body fixing part; and
and a third sealing groove formed to be recessed inside the piston accommodating part, the rod accommodating part, and the slit groove part, and to which the main body fixing part is coupled.
9. The method of claim 8,
The third sealing groove portion,
a first housing groove formed to extend along a portion of the inner surface of the piston receiving portion that does not face the rod receiving portion, and to which a portion of the body fixing portion is coupled;
a second housing groove formed to extend along a portion of the inner surface of the rod receiving portion that does not face the piston receiving portion, and to which the other portion of the body fixing portion is coupled; and
and a third housing groove formed continuously between the first housing groove and the second housing groove and to which another part of the main body fixing portion is coupled.
According to claim 1,
The housing is
The drum brake apparatus further comprising a; a fixing part formed on the main body part and fixed to the back plate.
11. The method of claim 10,
The fixing part,
a fixed fastening part formed on both sides of the main body part and fixed to the back plate together with the actuator by a fastening member; and
and a flow preventing part which is formed to protrude at a position corresponding to the main moving part of the main body and is fitted into a through hole formed in the back plate.
According to claim 1,
The piston receiving part,
a cylinder part formed to be hollow in a cylindrical shape on the housing, and in which the main moving part is accommodated; and
and a hydraulic oil passage portion extending from the outer surface of the housing to the cylinder portion and forming a passage for supplying a fluid into the cylinder portion.
13. The method of claim 1 or 12,
The load receiving unit,
a rod cylinder part formed to be hollow in a circumferential shape on the housing and receiving the parking brake part; and
and a drive shaft accommodating part disposed at a set interval from the piston accommodating part, formed in communication with the rod cylinder part, and connected to the parking brake part through which the output shaft of the actuator is introduced.
According to claim 1,
The piston receiving part and the rod receiving part are positioned on the same radial extension line with respect to the rotation center of the back plate,
The rod accommodating part is disposed at a position spaced apart from the pivot accommodating part of the shoe from the piston accommodating part,
The actuator is positioned on the same radial extension line as the chassis supporting the central portion of the back plate, and is arranged in parallel with the rotation center of the back plate.

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