WO2003008830A1

WO2003008830A1 - Waterproof construction for brake drums

Info

Publication number: WO2003008830A1
Application number: PCT/JP2001/005706
Authority: WO
Inventors: Tomoyuki Yonezawa; Keigo Dewa
Original assignee: Honda Giken Kogyo Kabushiki Kaisha
Priority date: 2001-07-02
Filing date: 2001-07-02
Publication date: 2003-01-30
Also published as: KR100489775B1; BR0117073B1; JPWO2003008830A1; JP3640659B2; GR20020100274A; CN1289833C; AR033188A1; BR0117073A; TW496841B; KR20030003664A; CN1524167A

Abstract

A brake drum (20A) comprises a wheel hub (21), a brake panel (30) and a drum brake mechanism (40). A clearance (52) between the wheel hub and the brake panel is sealed by a labyrinth mechanism (50). In the portion of the drum brake located above an axle (12), the labyrinth mechanism is fitted at the outer peripheral surface (51) of the brake panel in a recess (23). The brake panel has in its outer peripheral surface an outer labyrinth groove (53) and an inner labyrinth groove (54) in the order mentioned as seen from the front of the panel width toward the recess. The cross-sectional area (A1) of the outer labyrinth groove is smaller than the cross-sectional area (A2) of the inner labyrinth groove.

Description

Description Waterproof structure of drum brake Technical field

The present invention relates to a drum brake mounted on a wheel of a vehicle such as a motorcycle, and in particular, to further improve the waterproof performance of a gap between a wheel hub as a rotating member and a brake panel as a non-rotating member. I 关] ^ "ににドラムドラムドラムドラムドラムドラム技術ドラム背景

In vehicles such as motorcycles, many types of vehicles are equipped with a drum brake on wheels, and the drum brake is operated by a brake lever or a brake pedal.

In a vehicle equipped with such a drum brake, a drum brake mechanism is housed in a concave portion of a wheel hub that is a rotating member, and a concave portion is closed while supporting a main part of the drum brake mechanism with a brake panel that is a non-rotating member. A motorcycle in which the gap between the wheel hap and the brake panel is sealed with a labyrinth structure is known, for example, in Japanese Utility Model Publication No. 62-12913.

As a waterproof structure for such a drum brake, a conventional technique shown in FIG. 19 is known. The waterproof structure of the drum brake shown in FIG. 19 is described in Japanese Utility Model Publication No. 62-12913 for ease of comparison with the present invention. Is changed and shown.

FIG. 19 is a cross-sectional view showing a waterproof structure of a drum brake mounted on a conventional wheel. The wheel 100 has a wheel hub 103 for accommodating the drum brake mechanism 102 in the recess 101, and a brake panel 1004 for closing the recess 101 and supporting the main part of the drum brake mechanism 102. Consists of The brake panel 104 has a panel portion 105 that covers the concave portion 101, and an outer peripheral fitting portion 106 that extends from the panel portion 105 into the concave portion 101 and fits into the concave portion 101. The outer labyrinth formed on the outer peripheral surface of the outer peripheral fitting portion 106 Groove 107 and inner labyrinth groove 108, cover part 109 extending from outer peripheral fitting part 106 to cover the outside of wheel hub 103, and formed at the lower end of cover part 109 Drainage outlet 1 1 1

Even with such a waterproof structure of the drum brake, water such as rainwater is blown off by centrifugal force because the wheel hub 103 rotates at high speed while the vehicle is running. There is no worry that water will enter the recess 101. However, centrifugal force does not work during car washing, which is disadvantageous in terms of waterproofness. Disclosure of the invention

An object of the present invention is to provide a waterproof structure of a drum brake having a high waterproof effect even during a car washing operation by further enhancing waterproof performance of a gap between a wheel hub as a rotating member and a brake panel as a non-rotating member. It is in.

According to the first feature of the present invention, a wheel hub having a concave portion for accommodating a drum brake mechanism, and a brake panel closing a concave portion while supporting a main portion of the drum brake mechanism are provided. In a drum brake that seals the gap with the non-rotating member brake panel with a labyrinth structure,

In a portion above the axle of the drum brake, the labyrinth structure is configured such that an outer peripheral surface of the brake panel is fitted into the concave portion, and an outer labyrinth is formed on the outer peripheral surface of the brake panel from outside the panel width direction into the concave portion. A waterproof structure for a drum brake is provided in which a groove and an inner labyrinth groove are provided in this order, and a cross-sectional area of the outer labyrinth groove is smaller than a cross-sectional area of the inner labyrinth groove.

The drainage capacity of the outer labyrinth groove with a smaller cross section is smaller than that of the inner labyrinth groove with a larger cross section. When a small amount of water, such as water droplets, enters the outside labyrinth groove from the outside, the water that has entered can flow downward using the outside labyrinth groove as a drainage channel, and can be further discharged outside. Therefore, the water that has entered the outer labyrinth groove can be quickly discharged to the outside.

On the other hand, if a large amount of water enters the outside labyrinth groove from the outside, the inside of the outside labyrinth groove with a small cross-sectional area is quickly filled with water. Water overflowing from the outer labyrinth groove flows downward through the adjacent inner labyrinth groove and is further discharged to the outside. Sa Furthermore, the surface tension of the water filled in the outer labyrinth groove closes the gap between the wheel hub and the brake panel, thereby further preventing water from entering. As a result, it is possible to prevent water such as rainwater and washing water from entering.

In this manner, the waterproof performance of the labyrinth structure that seals the gap between the wheel hub and the brake panel can be further enhanced, and the waterproof effect during the car washing operation can be enhanced.

According to the second feature of the present invention, the wheel hub has a concave portion for accommodating the drum brake mechanism, and a brake panel for closing the concave portion while supporting a main part of the drum brake mechanism. In a drum brake that seals the gap with the non-rotating member brake panel with a labyrinth structure,

In a portion below the axle of the drum brake, the labyrinth structure includes an outer labyrinth groove and an inner labyrinth groove in this order from the outside to the concave portion, and three types in the circumferential direction from the bottom to the vicinity of the axle height position. And a waterproof wall extending radially outward from the brake panel in these three types of drainage structures. The lowermost first drainage structure sandwiches the outer labyrinth groove. The height of the outer ribs and the intermediate ribs is minimized, and the distance between the wheel hub and the waterproof wall is maximized to improve drainage,

In the second drainage structure thereon, the height of the outer rib and the intermediate rib sandwiching the outer labyrinth groove is the same as that of the first drainage structure, and the space between the wheel hub and the waterproof wall is the first drainage structure. The drainage structure is narrower than the drainage structure of

In the third drainage structure thereon, the outer rib and the intermediate rib sandwiching the outer labyrinth groove are extended to be higher than the first and second drainage structures, and the distance between the wheel hub and the waterproof wall is increased. By providing a narrower than the first drainage structure, a waterproof structure of a drum spray with improved sealing properties is provided.

In the first drainage structure at the lowest level, the water entering the outer and inner labyrinth grooves can be quickly drained by lowering the outer ribs and intermediate ribs and increasing the distance between the wheel hub and the waterproof wall. So it has good drainage. In addition, there is a large gap between the outer labyrinth groove and the inner labyrinth groove. The capacity to store can be increased. Therefore, the sealing property of the labyrinth structure can be ensured.

In the second drainage structure, the outer ribs and the middle ribs are lowered, so that the gap between the outer labyrinth groove and the inner labyrinth groove is greatly increased. Can increase. Furthermore, in the second drainage structure, the distance between the wheel hub and the waterproof wall is made narrower than in the first drainage structure, so that the surface tension of the water accumulated in the lower part of the outer and inner labyrinth grooves causes the labyrinth structure to seal. And drainage can be ensured in a well-balanced manner. Therefore, it is possible to balance the drainage of water entering the outer and inner labyrinth grooves with the sealing property of the labyrinth structure.

In the third drainage structure, the outer ribs and intermediate ribs must be higher than in the first drainage structure, and the distance between the wheel hub and the waterproof wall must be narrower than in the first drainage structure. Thereby, the sealing property of the labyrinth structure can be improved. Furthermore, in the third drainage structure, by reducing the distance between the wheel hub and the waterproof wall, drainage can be ensured by the surface tension of water accumulated in the lower part of the outer labyrinth groove. In this manner, the waterproof performance of the labyrinth structure that seals the gap between the wheel hub and the brake panel can be further enhanced, and the waterproof effect during the car washing operation can be enhanced.

According to the third feature of the present invention, a wheel hub having a recess for accommodating the drum brake mechanism, and a brake panel for closing the recess while supporting a main part of the drum brake mechanism, A drum brake that seals a gap with a brake panel, which is a non-rotating member, with a labyrinth structure, wherein the drum panel detents and supports the brake panel on a lyafork of a motorcycle.

When a part of the brake panel is extended along the lya fork and the rotation of the brake panel is stopped between the extended portion and the lya fork, the outer surface of the extended portion reflects on the extended portion. Thus, there is provided a waterproof structure of a rear drum brake of a motorcycle provided with a waterproof wall for stopping water directed to the labyrinth structure.

Water reflected on the outer surface of the extension toward the labyrinth structure can be stopped by the waterproof wall. Therefore, water reflected on the outer surface of the extension does not hit the labyrinth structure. Absent. In this manner, the waterproof performance of the labyrinth structure that seals the gap between the wheel hap and the brake panel can be further enhanced, and the waterproof effect during the car washing operation can be enhanced.

It is preferable that the waterproof wall provided on the extending portion extends toward the outer peripheral portion of the spoke flange erected from the wheel hub. Since the range in which water is reflected on the outer surface of the extending portion toward the labyrinth structure can be further suppressed, the waterproof performance can be further enhanced. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a side view around a wheel hub of a wheel according to a first embodiment of the present invention;

FIG. 2 is a cross-sectional view taken along line 2 — 2 of FIG.

FIG. 3 is a side view of the configuration in which the brake panel is mounted on the wheel hub shown in FIG. 1; FIG. 4 is a longitudinal sectional view of the configuration in which the brake panel is mounted on the wheel hub shown in FIG. 3; , Fig. 3 5-5 cross section

Fig. 6 is a sectional view taken along line 6-6 in Fig. 3.

Fig. 7 is a sectional view taken along the line 7-7 in Fig. 3.

Fig. 8 is a sectional view taken along line 8-8 in Fig. 3.

Fig. 9 is a cross-sectional view taken along line 9-9 in Fig. 3.

Figure 10 is a rear view of the brake panel shown in Figure 3;

Fig. 11 is a cross-sectional view taken along line 1 1 1 1 1 in Fig. 10.

Fig. 12 is a cross-sectional view of Fig. 10 taken along the line 12--12.

Fig. 13 is a sectional view taken along the line 13-13 in Fig. 10.

Fig. 14 is a sectional view taken along the line 14-14 in Fig. 10.

Fig. 15 is a sectional view taken along the line 15--15 in Fig. 3;

FIG. 16 is a side view of a configuration in which a brake panel is assembled to a wheel hub according to a second embodiment of the present invention;

Fig. 17 is a sectional view taken along the line 17-17 in Fig. 16;

Fig. 18 is a rear view of the brake panel shown in Fig. 16;

Figure 19 is a cross-sectional view showing the waterproof structure of a drum brake mounted on a conventional wheel. is there. BEST MODE FOR CARRYING OUT THE INVENTION

FIGS. 1 and 2 show a motorcycle 10 around a rear wheel 20 according to a first embodiment of the present invention.

As shown in FIGS. 1 and 2, the motorcycle 10 includes a rear swingable lyafork 11 extending rearward (to the left in the drawing) from a body frame (not shown), and a rear leek fork 11. And an axle 12 provided at the end. The axle 12 includes a wheel hub 21 rotatably provided via bearings 13 and 14 and a rear brake panel 30 adjacent to the wheel hub 21.

Note that the rear brake panel 30 of the first embodiment shown in FIGS. 1 and 2 is the brake panel according to the present invention.

The wheel hub 21 is a hub of the wheel 20 as a rear wheel. The wheel hub 21 has a pair of left and right disk-shaped spoke flanges 22, 22, which are set up radially outward from the outer peripheral portion, and is opened outward in the axial direction of the axle 12 and on the side of the rear brake panel 30. And a concave portion 23 having a circular shape in a side view. The left and right spoke flanges 2 2, 2 2 are members for attaching one end of a large number of spokes 24. In the figure, reference numeral 25 denotes a driven sprocket for a wheel hub.

The lya brake panel 30 includes a panel portion 31 for closing the opening of the concave portion 23, and an extension portion 32 in which a part of the panel portion 31 extends along the lya fork 11. By fitting the detent protrusion 1 1a formed on the lyafork 1 1 with the detent groove 3 2a formed on the extension 32, the lyafork 1 1 and the extension 3 are fitted. The rotation of the rear brake panel 30 can be prevented between the first and second panels. Thus, the rear brake panel 30 is prevented from rotating by the rear Oak 11 and supported.

According to such a wheel 20, the drum brake mechanism 0 is housed in the concave portion 23 of the wheel hub 21, and the main part of the drum brake mechanism 40 is formed by the panel portion 31 of the rear brake panel 30. Can be supported. The drum brake 20 A of the wheel 20 is composed of a wheel hub 21 as a rotating member, a rear brake panel 30 as a non-rotating member, and a drum interposed between the wheel hub 21 and the rear brake panel 30. Brake machine Structure 40.

The drum brake mechanism 40 is, for example, an expanding drum brake, which comes into contact with and separates from the anchor pin 41 and the brake operating shaft 42 supported by the panel 31 and the brake disk 43 in the recess 23. A pair of brake shoes 4 4 (only one is shown) attached to the anchor pin 41 so that the return springs 4 5 resiliently reduce the diameter of the pair of brake shoes 44, and brake operation A brake operation arm 46 provided on the shaft 42 is provided.

The drum brake mechanism 40 is configured so that the brake operating shaft 42 is rotated by the brake operating arm 46 to expand the diameter of the brake shoe 44 so that the lining of the brake shoe 44 and the brake disc 43 are connected. The frictional force acts as a brake. The drum brake mechanism 40 is omitted from FIG.

By the way, the wheel 20 has a waterproof structure in which a gap between the wheel hap 21 that is a rotating member and the rear brake panel 30 that is a non-rotating member is sealed by a lapirins mechanism 50. Hereinafter, the labyrinth mechanism 50 will be described in detail.

As shown in FIGS. 3, 4, and 5, when the outer peripheral surface of the rear brake panel 30, that is, the outer peripheral surface 51 of the panel portion 31 is fitted into the concave portion 23 of the wheel hub 21, the concave portion 2 is formed. There is a gap 52 between 3 and panel portion 31.

The labyrinth mechanism 50 includes an outer labyrinth groove 5 3 and an inner labyrinth groove on the outer peripheral surface 51 of the panel portion 31 from the outer side in the panel width direction (axially outer side of the axle 12 shown in FIG. 2) into the concave portion 23. The labyrinth structure in which the gaps 52 are sealed by providing 54 in this order. The outer and outer labyrinth grooves 53, 54 are annular grooves formed on the outer peripheral surface 51 of the panel portion 31.

As shown in FIGS. 4 and 5, the concave portion 23 is a circular hole having an opening 23 a having an inner diameter D1. The panel portion 31 is a disk having an outer diameter D2 and is smaller than the inner diameter D1 of the opening portion 23a. The dimension of the gap 52 between the inner peripheral surface of the opening 23 a and the outer peripheral surface 51 of the panel portion 31 is S. This dimension <5 is extremely small.

Since the entire outer peripheral surface 51 of the panel portion 31 is fitted into the concave portion 23, the dimension <5 of the gap 52 can be easily set small, and the outer diameter of the rear brake panel 30 can be reduced. It can be made smaller and lighter. Furthermore, axle 1 2 (see Figure 2) By slightly bending, the fluctuation of the dimension 6 of the gap 52 can be suppressed even when the rear brake panel 30 is slightly inclined.

Further, the conventional technique shown in FIG. 19 has a structure in which a cover part 109 is extended so as to cover the outside of the wheel hub 103 from the outer peripheral fitting part 106. On the other hand, in the first embodiment, the entire outer peripheral surface 51 of the panel portion 31 is fitted into the concave portion 23 without having the cover portion 109. Since there is no cover portion 109, water from above does not enter through the gap between the cover portion 109 and the wheel hub 21. Therefore, waterproofness at the time of car washing is improved.

The diameter of the bottom of the outer labyrinth groove 53 is D3. The bottom diameter of the inner labyrinth groove 54 is D4 and smaller than the bottom diameter D3 of the outer labyrinth groove 53. In the portion R 1 above the axle bearing hole 3 3 (that is, the axle 12 shown in FIG. 1 above), the groove depth H 1 of the outer labyrinth groove 53 is larger than the groove depth H 2 of the inner labyrinth groove 54. Is also small. The groove width of the outer labyrinth groove 53 is almost the same as the groove width of the inner labyrinth groove 54. Therefore, the cross-sectional area A 1 of the outer labyrinth groove 53 is smaller than the cross-sectional area A 2 of the inner labyrinth groove 54.

Note that the groove depth H1 is also the height of the outer rib 55 and the intermediate rib 56 sandwiching the outer labyrinth groove 53. The inner labyrinth groove 54 is a groove sandwiched between the intermediate rib 56 and the inner rib 57.

As shown in FIG. 3 and FIG. 6 to FIG. 9, in the portion below the axle bearing hole 33 (that is, the axle 12 shown in FIG. Three types of drainage mechanisms (that is, drainage structures) 61, 62, 63 are continuously provided in the circumferential direction in the range R2 up to the vicinity of the height position of 33 (axle 12). The rear brake panel 30 includes a waterproof wall 65 extending radially outward from the panel portion 31.

FIG. 6 shows a cross section of the lowermost first drainage mechanism 61, FIG. 7 shows a cross section of the second drainage mechanism 62, FIG. 8 shows a cross section of the third drainage mechanism 63, and FIG. The cross section of the labyrinth structure above the third drainage mechanism 63 is shown in FIG.

As shown in FIGS. 3, 6, 10, and 11, the lowermost first drainage mechanism 61 has the lowest height H 11 of the outer rib 55 and the intermediate rib 56, The distance W1 between the wheel hub 21 and the waterproof wall 65 is the widest, drainage structure. Outer 'inner labyrinth groove 5 3, 54 groove depth is small. In this way, by providing the large drainage channel 66 leading from the outer and inner labyrinth grooves 53, 54 to the outside, the drainage of the lowermost first drainage mechanism 61 can be enhanced. The range of the first drainage mechanism 61 is L1 (see Figs. 3 and 10).

As shown in FIG. 3, FIG. 7, FIG. 10 and FIG. 12, the second drainage mechanism 62 above the first drainage mechanism 61 is the same as the height of the outer rib 55 and the intermediate rib 56. H11 is the same lowest drainage structure as the first drainage mechanism 61. The distance W2 between the wheel hub 21 and the waterproof wall 65 in the second drainage mechanism 62 is smaller than the distance W1 between the wheel hub 21 and the waterproof wall 65 in the first drainage mechanism 61. The outer and inner labyrinth grooves 53, 54 have a small depth. In this way, by providing the slightly larger drainage channel 66 extending from the outer and inner labyrinth grooves 53, 54 to the outside, the drainage performance and sealing performance of the second drainage mechanism 62 are balanced. be able to. The area of the second drainage mechanism 62 is L2 (see Figs. 3 and 10).

As shown in FIG. 3, FIG. 8, FIG. 10 and FIG. 13, the third drainage mechanism 63 above the second drainage mechanism 62 is provided with the height of the outer rib 55 and the intermediate rib 56. H 12 is a drainage structure higher than the height H 11 of the first and second drainage mechanisms 6 1, 62. The reason why the height H12 is large is that the tips of the outer rib 55 and the intermediate rib 56 are extended toward the inner peripheral surface of the concave portion 23. The distance W2 between the wheel hap 21 and the waterproof wall 65 in the third drainage mechanism 63 is the same as that of the second drainage mechanism 62, and the wheel hub 2 in the first drainage mechanism 61 The distance between 1 and the waterproof wall 6 5 is smaller than W 1. Therefore, the outer-inner labyrinth grooves 53, 54 have a relatively large groove depth. Thus, the sealing performance of the second drainage mechanism 62 can be improved. The range of the third drainage mechanism 63 is L3 (see Figs. 3 and 10).

As shown in FIGS. 3, 9, 10, and 14, the labyrinth structure of the upper portion of the third drainage mechanism 63 has a height H1 of the outer rib 55 and the intermediate rib 56. It is the highest and is the same as the part shown in FIG. The outer and inner labyrinth grooves 53, 54 have a large groove depth. Moreover, it has almost no waterproof wall 65.

The heights H 11 and H 12 of the outer rib 55 and the intermediate rib 56 refer to the height from the bottom of the outer labyrinth groove 53. As shown in FIGS. 3, 10, and 15, the extension 32 of the rear brake panel 30 is formed with a waterproof wall 68 extending toward the outer periphery 22a of the spoke flange 22. ing. The waterproof wall 68 stops water flowing toward the labyrinth mechanism 50 by being reflected on the outer surface of the extension 32. The waterproof wall 68 is an arc-shaped wall member along the outer peripheral portion 22 a of the spoke flange 22. The tip of the waterproof wall 68 extends to near the end on the opening side of the wheel hub 21. For example, as shown by arrows in FIG. 15, even if water such as rainwater or washing water is reflected on the outer surface of the extension 32, there is no need to worry about going to the lapillin mechanism 50.

FIG. 16, FIG. 17 and FIG. 18 show the area around the front wheel 70 of the motorcycle 10 according to the second embodiment of the present invention. The same members as those in the first embodiment shown in FIGS. 1 to 15 are denoted by the same reference numerals, and description thereof will be omitted. Also, in FIGS. 16 and 17, the drum brake mechanism 40 is omitted.

Further, in FIG. 16, the configuration of the section taken along line 6-6 is the same as the configuration shown in FIG. 6, and the section of the section taken along line 7-7 is the same as the configuration shown in FIG. The configuration of the section taken along line 8-8 is the same as the configuration shown in FIG. 8 above, and the configuration of the section taken along line 9-9 is the same as the configuration shown in FIG. 9 above, and description thereof will be omitted.

Also, in FIG. 18, the configuration of the cross section taken along line 11-11 is the same as the configuration shown in FIG. 11 above, and the configuration of the cross section taken along line 12-12 is shown in FIG. 12 above. The structure is the same as that shown in FIG. 13 with respect to the cross section taken along the line 13-13, and the structure shown in FIG. 14 above is the cross section taken along the line 14-14. The description is omitted.

As shown in FIGS. 16, 17 and 18, a wheel 70 as a front wheel is rotatably provided on an axle 12 (see FIG. 2) via bearings 13 and 14. It comprises a haptic 71 and a front brake panel 80 adjacent to the wheel hub 71.

The front brake panel 80 of the second embodiment shown in FIGS. 16, 17, and 18 is a brake panel according to the present invention.

The wheel hub 71 has substantially the same configuration as the wheel hub 21 described above. The front brake panel 80 has almost the same configuration as the rear brake panel 30 described above, It has a panel part 81 that closes the opening of. However, the front brake panel 80 does not have the extension 32 and the waterproof wall 68 shown above.

The drum brake 7OA of the wheel 70 is interposed between the wheel hub 71, which is a rotating member, the front brake panel 80, which is a non-rotating member, and the wheel hap 71, and the front brake panel 80. Drum brake mechanism 40 (see Fig. 2). Industrial applicability

In the portion above the axle of the drum brake, the outer labyrinth groove and the inner labyrinth groove are provided on the outer peripheral surface of the brake panel from the outside in the width direction of the panel into the recess in this order, and the cross-sectional area of the outer labyrinth groove is cut in the inner labyrinth groove. By making the area smaller, the waterproof performance of the labyrinth structure that seals the gap between the wheel hub and the brake panel can be further improved.

In the portion below the axle of the drum brake, the clearance between the wheel hub and the brake panel can be reduced by appropriately setting the height of the outer rib and the intermediate rib sandwiching the outer labyrinth groove and the distance between the wheel hap and the waterproof wall. The waterproof performance of the labyrinth structure that seals can be further enhanced.

The gap between the wheel hub and the brake panel is sealed by providing a waterproof wall on the extension to stop the rotation of the brake panel and to stop the water reflected on the outer surface of the extension and going to the lapiling structure. The labyrinth structure improves the waterproof performance.

In particular, it is useful in a waterproof structure of a drum brake mounted on a wheel of a vehicle such as a motorcycle.

Claims

The scope of the claims

1. A wheel hub (2 1) having a concave portion (23) for accommodating the drum brake mechanism (40) and a brake panel (3) for supporting the main part of the drum brake mechanism and closing the concave portion

0), and a labyrinth structure (50) is used to seal the gap (52) between the wheel hub that is a rotating member and the brake panel that is a non-rotating member.

In a portion above the axle (12) of the drum brake, the labyrinth structure is configured such that an outer peripheral surface (51) of the brake panel is fitted in the concave portion, and an outer peripheral surface of the brake panel is fitted in a panel width direction. The outer labyrinth groove (53) and the inner labyrinth groove (54) are provided in this order from the outside into the recess, and the cross-sectional area (A

Waterproof structure for drum brakes, characterized in that 1) is smaller than the cross-sectional area (A2) of the inner labyrinth groove.

2. A wheel hub (21) having a concave portion (23) for accommodating the drum brake mechanism (40), and a brake panel (30) for closing the concave portion while supporting the main part of the drum brake mechanism. In a drum brake (20A), a labyrinth structure (50) is used to seal the gap (52) between a certain wheel hub and a brake panel that is a non-rotating member.

In a portion below the axle (12) of the drum brake, the lapilin structure includes an outer labyrinth groove (53) and an inner labyrinth groove (54) in this order from the outside into the recess, but the axle height from the bottom. The three types of drainage structures are continuously arranged in the circumferential direction up to the vicinity of the squat position, and a waterproof wall (65) is extended radially outward from the brake panel in the three types of drainage structures.

In the lowermost first drainage structure (61), the height (H11) of the outer rib (55) and the intermediate rib (56) sandwiching the outer labyrinth groove is made the lowest, and the wheel hub and the waterproof wall are formed. The drainage is increased by making the distance (W1) between

In the second drainage structure (62), the height (H11) of the outer rib and the intermediate rib sandwiching the outer labyrinth groove is the same as that of the first drainage structure, and the wheel hub is formed. The distance (W2) between the drainage structure and the waterproof wall is narrower than that of the first drainage structure to balance the drainage performance and the sealing performance,

In the third drainage structure (63), the outer rib and the intermediate rib sandwiching the outer labyrinth groove are extended to be higher than the first drainage structure and the second drainage structure. A waterproof structure for a drum brake, characterized in that a gap (W2) is made narrower than that of the first drainage structure to enhance sealing performance.

3. A wheel hub (21) having a recess (23) for accommodating the drum brake mechanism (40) and a brake panel (30) for closing the recess while supporting the main part of the drum brake mechanism. A drum brake (2OA) in which a gap (52) between a certain wheel hub and a brake panel as a non-rotating member is sealed with a labyrinth structure (50), wherein the brake panel is a motorcycle (10). In the Lyafork (11) of the

A part of the brake panel is extended along the lyafork, and when the rotation of the brake panel is to be stopped between the extension (32) and the lyafork, the extension is provided with the extension A waterproof structure for a rear drum brake of a motorcycle, comprising a waterproof wall (68) for stopping water reflected on an outer surface toward the labyrinth structure.

4. The waterproof structure for a rear drum brake of a motorcycle according to claim 3, wherein the waterproof wall extends toward an outer peripheral portion (22a) of a spoke flange (22) raised from the wheel hub.