JP2009041749A - Brake drum - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve heat release performance of a brake drum while suppressing entry of water and foreign matters from outside to inside of the brake drum. <P>SOLUTION: In the cylindrical brake drum 412 having opened one end and the other end with a bottom face formed thereon, opening/closing means 432 formed on an outer peripheral face 18a of a cylindrical part 18 are provided on the outer peripheral face 18a of the cylindrical part 18 and is constituted to close through holes 18b when the brake drum 412 is not rotated. When the brake drum 412 is rotated, the opening/closing means 432 are deformed toward the radial outer side of the brake drum 412 by the centrifugal force to increase outside air introduced from the rotating axis direction of the brake drum 412 to the through holes 18b while blocking outside air flowing from the downstream side in the brake drum rotating direction with respect to the through holes 18b, and form opening parts 48 intersecting with the rotating axis direction of the brake drum 412. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a brake drum.

  2. Description of the Related Art Conventionally, a drum brake is known in which a belt-like brake shoe that is spread by oil pressure in accordance with the operation of a pedal is installed inside a cylindrical brake drum that rotates together with a tire. The drum brake can brake the vehicle by friction between a brake shoe and a brake drum (hereinafter referred to as a drum as appropriate).

In such a drum brake, dust and heat are generated by the friction described above. Therefore, it is necessary to cool the drum so that the temperature of the drum does not rise excessively. For this reason, it is conceivable that a hole for introducing outside air is provided in a part of the drum on the inner peripheral portion of the drum. However, if water enters through the hole, a noise may be generated between the brake shoe and the drum. . Patent Document 1 discloses a drum brake in which an opening / closing valve that is opened and closed by heat, centrifugal force, or the like is provided in a discharge hole for discharging dust.
JP 2003-336671 A

  The present invention has been further developed in view of the prior art, and its object is to improve the heat dissipation of the brake drum while suppressing the entry of water and foreign matter into the brake drum from the outside. It is to provide a brake drum that can be used.

  In order to solve the above-described problem, a brake drum according to an aspect of the present invention is a cylindrical brake drum having one end opened and a bottom surface formed at the other end, and is formed on the circumferential surface of the cylindrical portion. And an opening / closing means provided on the outer peripheral surface of the cylindrical portion and configured to close the through hole when the brake drum is not rotating. When the brake drum is rotating, the opening / closing means is introduced into the through hole from the rotating shaft direction of the brake drum while shielding the outside air flowing from the downstream side in the brake drum rotating direction with respect to the through hole. It is deformed toward the outside in the radial direction of the brake drum by centrifugal force so that the outside air increases, and an opening that intersects with the rotation axis direction of the brake drum is formed.

  According to this aspect, since the through hole is closed when the brake drum is not rotating, it is possible to prevent water and foreign matter from entering the inner peripheral portion of the brake drum from the through hole. On the other hand, when the brake drum is rotating, the open / close means is deformed by the centrifugal force and the outside air introduced into the through hole is increased, so that the heat dissipation is improved. In addition, when the brake drum is rotating, the opening / closing means generates centrifugal force due to the rotation of the brake drum. Therefore, even if the opening / closing means is deformed and the through hole is opened, water and foreign matter may be It becomes difficult to enter the inside of the brake drum. Moreover, since the opening / closing means shields the outside air flowing from the downstream side in the rotation direction of the brake drum with respect to the through hole, it is possible to suppress water and foreign matter from reaching the through hole directly.

  The opening / closing means includes a plate-shaped shielding member provided on the outer peripheral surface of the cylindrical portion so as to close the through-hole when the brake drum is not rotating, and a downstream side and an upstream side of the through-hole in the brake drum rotation direction, And a holding member that holds both ends of the shielding member so that the shielding member does not fall off from the outer peripheral surface of the cylindrical portion. The shielding member is deformed in the radial direction of the brake drum by a centrifugal force when the brake drum rotates, and opens the through hole. Thereby, a through-hole can be opened and closed repeatedly with a simple structure using the centrifugal force by rotation of a brake drum.

  The holding member is formed so as to guide both end portions of the shielding member in the circumferential direction of the brake drum when the central portion of the shielding member is deformed in the radial direction of the brake drum by centrifugal force when the brake drum rotates. You may have the guide part made. Thereby, when a centrifugal force acts on the central part of the shielding member, both ends of the shielding member approach each other along the guide part, so that the central part of the shielding member can be easily deformed in the radial direction of the brake drum. .

  The shielding member may have a weight attached to a region not held by the holding member. Thereby, a through-hole can be opened by low-speed rotation compared with the shielding member without weight.

  The shielding member may be formed of a metal material that is elastically deformed. Thereby, heat dissipation can be improved.

  ADVANTAGE OF THE INVENTION According to this invention, the heat dissipation of a brake drum can be improved, suppressing the penetration | invasion of the water and a foreign material into the brake drum from the outside.

    Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.

(First embodiment)
[Drum brake configuration]
FIG. 1 is a schematic configuration diagram of a drum brake. FIG. 2 is an overall perspective view of a brake drum used in the drum brake shown in FIG.

  The drum brake 10 shown in FIG. 1 is suitably used as a rear brake unit of a vehicle, for example. The drum brake 10 includes a brake drum 12 attached to an axle (not shown) of the vehicle and a brake shoe 14.

  The brake drum 12 is a cylindrical member that is open at one end (left side shown in FIG. 2) and has a bottom surface 16 formed at the other end (right side shown in FIG. 2). The brake drum 12 is provided in a plurality of through holes 18b formed in the outer peripheral surface 18a of the cylindrical portion 18 and the outer peripheral surface 18a of the cylindrical portion 18, and is configured to close the through holes 18b when the brake drum 12 is not rotating. Open / close means described later.

  The brake shoe 14 includes a pair of brake shoes 14 a and 14 b disposed on the inner peripheral portion of the brake drum 12. The drum brake 10 generates braking torque by pressing a pair of brake shoes 14 a and 14 b against the inner peripheral surface of the brake drum 12.

  The brake shoe 14a has a web 20a, a rim 22a, and a brake lining 24a. Similarly, the brake shoe 14b has a single web 20b, a rim 22b, and a brake lining 24b.

  As shown in FIG. 1, the drum brake 10 includes a wheel cylinder 26 arranged inside the brake drum 12. As shown in FIG. 1, the upper ends of the brake shoes 14 a and 14 b are connected to each other via one or two shoe return springs 28.

  Due to the urging force of the shoe return spring 28, one end of the web 20 a of the brake shoe 14 a is engaged with the end of the piston of the wheel cylinder 26. Further, the urging force of the shoe return spring 28 causes one end of the web 20 b of the brake shoe 14 b to engage with the end of the corresponding piston of the wheel cylinder 26. Furthermore, as shown in FIG. 1, the lower ends of the pair of brake shoes 14 a and 14 b are connected to each other via an anchor block 30.

  In the drum brake 10 configured as described above, when the brake pedal is operated by the driver, the brake fluid is supplied to the wheel cylinder 26 from a master cylinder (not shown). Accordingly, the pair of pistons of the wheel cylinder 26 are protruded outward.

  The pair of brake shoes 14a and 14b is applied with a pressing force from the wheel cylinder 26, and one end portions of the brake shoes 14a and 14b are respectively extended outward (to the left and right in the drawing) with the anchor block 30 as a fulcrum. .

  As a result, the brake linings 24a and 24b provided on the outer peripheral surfaces of the brake shoes 14a and 14b are pressed against the inner peripheral surface 12a of the brake drum 12 that rotates integrally with the wheels. Thereby, a braking torque can be obtained.

[Brake drum structure]
Next, the structure of the brake drum 12 will be described in detail. FIG. 3 is a front view of the brake drum 12 according to the first embodiment. 4 is a cross-sectional view taken along line AA in FIG. FIG. 5 is an enlarged view of a region B in the vicinity of the through hole shown in FIG.

  As shown in FIGS. 3 and 4, the opening / closing means 32 in the brake drum 12 according to the present embodiment is configured to close the through hole 18 b when the brake drum 12 is not rotating. Specifically, as shown in FIG. 5, the opening / closing means 32 has an attachment member 34 fixed to the outer peripheral surface 18 a of the brake drum 12, and a pin 36 serving as a rotation shaft is attached to the tip portion thereof. The spring 38 rotatably supported by the pin 36 urges the fin 40 covering the through hole 18b in a direction to press the outer peripheral surface 18a, so that the through hole 18b is closed by the fin 40. The spring 38 is preferably a torsion spring, for example.

  Thereby, since the through-hole 18b is closed when the brake drum 12 which concerns on this Embodiment does not rotate, water and a foreign material enter into the inner peripheral part of the brake drum 12 from the through-hole 18b.

  FIG. 6 is a diagram for explaining the operation of the opening / closing means when the brake drum 12 according to the first embodiment is rotating.

  As shown in FIG. 6, when the brake drum 12 rotates in the arrow C direction while the vehicle is traveling, the centrifugal force indicated by the arrow R acts on the fin 40 of the opening / closing means 32 in the radial direction. The centrifugal force causes the fin 40 to rotate about the pin 36 as a rotation axis, so that one end of the fin 40 is lifted outward and the through hole 18b is opened. As a result, while the vehicle is traveling, outside air is introduced into the inner peripheral portion of the brake drum 12 from the through hole 18b, so that the heat dissipation of the brake drum 12 is improved. Further, since the fin 40 is opened, more outside air flows toward the through hole 18b along the fin 40 as indicated by the arrow D, so that the heat dissipation at the inner peripheral portion of the brake drum 12 can be further improved. it can. In addition, the fin 40 which concerns on this Embodiment is comprised with the metal, and can radiate | emit the heat | fever of the brake drum 12 itself to external air via the fin 40. FIG.

(Second Embodiment)
FIG. 7 is a front view of the brake drum 112 according to the second embodiment. FIG. 8 is a diagram for explaining the operation of the opening / closing means when the brake drum 112 according to the second embodiment is rotating. The fins 140 of the opening / closing means 132 shown in FIG. 7 reach the vicinity of the adjacent opening / closing means 132 when the opening / closing means 132 is closed, as compared with the fins 40 of the opening / closing means 32 according to the first embodiment. The feature is that it is set to the length of.

  Then, as shown in FIG. 8, when the brake drum 112 rotates in the direction of arrow C while the vehicle is traveling, the centrifugal force indicated by the arrow R acts on the fin 140 of the opening / closing means 132 in the radial direction. Then, the centrifugal force lifts one end of the fin 140 outward, and the through hole 18b is opened. As a result, while the vehicle is traveling, outside air is introduced into the inner peripheral portion of the brake drum 112 from the through hole 18b, so that the heat dissipation of the brake drum 112 is improved. Further, since the fin 140 that is longer than the fin 40 according to the first embodiment is opened, more outside air flows along the fin 140 toward the through hole 18b as shown by the arrow D, so that the brake The heat dissipation in the inner periphery of the drum 112 can be further improved. In addition, since the fin 140 according to the present embodiment is also made of metal and is longer than the fin 40, the heat of the brake drum 12 itself can be efficiently radiated by the outside air through the fin 140.

(Third embodiment)
FIG. 9 is a front view of the brake drum 212 according to the third embodiment. FIG. 10 is a partial side view of the brake drum 212 shown in FIG.

  In the brake drum 212 according to the present embodiment, shielding members 232 that cover the upper portions of the respective through holes 18b are arranged on the outer peripheral surface 18a of the cylindrical portion 18 at regular intervals. Thereby, since the upper part of the through-hole 18b is covered when the brake drum 212 does not rotate, it can suppress that water and a foreign material penetrate | invade into the inner peripheral part of the brake drum 212 from the through-hole 18b.

  The shielding member 232 has an opening 232a formed on the downstream side in the rotation direction of the brake drum 212. When the brake drum 212 rotates in the direction of arrow C, the outside air is shown in the arrow D from the opening 232a as shown by the arrow D. It flows toward the through-hole 18b along the side walls 232b and 232c. Therefore, when the vehicle is traveling, outside air is introduced into the inner peripheral portion of the brake drum 212 from the through hole 18b, so that the heat dissipation of the brake drum 212 is improved.

  Further, as shown in FIG. 10, the side wall 232c of the shielding member 232 is provided so as to be inclined with respect to the rotation axis of the brake drum, and when the brake drum 212 rotates in the rotation direction indicated by the arrow C, the arrow As shown in D, the flow of outside air is directed to the through hole 18b. Thereby, outside air can be efficiently introduced into the through hole 18b, and the heat dissipation of the brake drum 212 can be improved.

(Fourth embodiment)
In the opening / closing means according to the first embodiment and the second embodiment described above, the use of fins allows efficient introduction of outside air into the through-holes, but foreign matter such as dust and dust is also positive. There is a possibility of being caught by fins. FIG. 11 is a schematic diagram for explaining how foreign matters are captured by fins while the brake drum is rotating.

  When the brake drum 312 is rotating, the fins 340 open outward by centrifugal force, so that the dust 42 is captured by the fins 340, and the brake drum 312 remains stationary while remaining between the fins 340 and the through holes 18b. Then, the fin 340 may not be closed normally. In such a case, when the brake drum 312 does not rotate, water and foreign matter easily enter the inner peripheral portion of the brake drum 312.

  Therefore, the brake drum according to the present embodiment employs a structure in which foreign matter is less likely to clog the opening / closing means. FIG. 12 is a schematic cross-sectional view of the vicinity of the opening / closing means provided in the brake drum 412 according to the fourth embodiment. FIG. 13 is a diagram for explaining the operation of the opening / closing means when the brake drum 412 according to the fourth embodiment is rotating. The main structure of the brake drum 412 is the same as the brake drum of each of the above-described embodiments, and the description thereof will be omitted as appropriate.

  The brake drum 412 is provided in a through hole 18b formed in the peripheral surface of the cylindrical portion 18 and an outer peripheral surface 18a of the cylindrical portion 18, and is configured to close the through hole 18b when the brake drum 412 is not rotating. Means 432.

  The opening / closing means 432 includes a leaf spring 44 that functions as a shielding member provided on the outer peripheral surface 18a of the cylindrical portion 18 so as to close the through hole 18b when the brake drum 412 is not rotating, and a brake drum rotation direction (arrow) of the through hole 18b. C) A holding member 46 that holds both end portions of the leaf spring 44 is provided on the downstream side and the upstream side so that the leaf spring 44 does not fall off from the outer peripheral surface 18a of the cylindrical portion 18.

  As shown in FIG. 13, in the leaf spring 44, the central portion 44a is elastically deformed in the radial direction of the brake drum by a centrifugal force when the brake drum 412 rotates, and the through hole 18b is opened. On the other hand, when the rotation of the brake drum 412 stops, the leaf spring 44 returns to the state shown in FIG. Thereby, the through-hole 18b can be repeatedly opened and closed with a simple configuration using the centrifugal force generated by the rotation of the brake drum 412.

  In addition, when the brake drum 412 is rotating, the opening / closing means 432 is configured to shield the outside air flowing from the downstream side of the brake drum rotation direction (arrow C) with respect to the through hole 18b while rotating in the direction of the rotation axis of the brake drum 412. So that the outside air introduced into the through hole 18b is increased by the centrifugal force toward the outside in the radial direction of the brake drum 412 to form an opening 48 that intersects the rotational axis direction of the brake drum 412.

  According to the brake drum 412 shown in FIGS. 12 and 13, since the through hole 18b is closed when the brake drum 412 is not rotated, water and foreign matter may enter the inner peripheral portion of the brake drum 412 from the through hole 18b. It is suppressed. On the other hand, when the brake drum 412 is rotating, the leaf spring 44 is deformed by the centrifugal force and the outside air introduced into the through hole 18b is increased, so that the heat dissipation is improved.

  When the brake drum 412 is rotating, the opening / closing means 432 generates a centrifugal force due to the rotation of the brake drum 412, so that the opening / closing means 432 is deformed and the through hole 18 b is opened. Since centrifugal force also acts on foreign matter 50 such as foreign matter, it is difficult to enter the brake drum 412 from the through hole 18b. Moreover, since the opening / closing means 432 shields the outside air flowing from the downstream side in the rotation direction of the brake drum with respect to the through hole 18b (see FIG. 13), the dust 50 is prevented from reaching the through hole 18b directly. .

  The holding member 46 guides both ends of the leaf spring 44 in the circumferential direction of the brake drum 412 when the central portion 44a of the leaf spring 44 is deformed in the radial direction of the brake drum 412 by centrifugal force when the brake drum 412 rotates. It has the guide part 46a formed so that it may do. Thereby, when a centrifugal force acts on the central portion 44 a of the leaf spring 44, both ends of the leaf spring 44 approach each other along the guide portion 46 a, so that the central portion 44 a of the leaf spring 44 is easily attached to the diameter of the brake drum 412. Can be deformed in the direction.

  The leaf spring 44 is provided with a weight 52 in a region 44 b that is not held by the holding member 46. Thereby, compared with the leaf | plate spring which does not have the weight 52, the through-hole 18b can be opened by low-speed rotation. Moreover, since the leaf | plate spring 44 is formed with the metal material which elastically deforms, heat dissipation can be improved.

  As described above, the present invention has been described with reference to the above-described embodiments. However, the present invention is not limited to the above-described embodiments, and the configurations of the embodiments are appropriately combined or replaced. Those are also included in the present invention. Various modifications such as design changes can be added to each embodiment based on the knowledge of those skilled in the art, and the embodiments to which such modifications are added are also included in the scope of the present invention. sell.

It is a schematic block diagram of a drum brake. It is a whole perspective view of the brake drum used for the drum brake shown by FIG. It is a front view of a brake drum concerning a 1st embodiment. It is AA sectional drawing of FIG. It is an enlarged view of B area | region of the through-hole vicinity shown in FIG. It is a figure for demonstrating operation | movement of the opening / closing means when the brake drum which concerns on 1st Embodiment is rotating. It is a front view of the brake drum which concerns on 2nd Embodiment. It is a figure for demonstrating operation | movement of the opening-closing means when the brake drum which concerns on 2nd Embodiment is rotating. It is a front view of the brake drum which concerns on 3rd Embodiment. FIG. 10 is a partial side view of the brake drum shown in FIG. 9 as viewed from the direction of arrow E. It is a schematic diagram for demonstrating a mode that a foreign material is caught with a fin during rotation of a brake drum. It is a schematic sectional drawing of the opening-closing means vicinity with which the brake drum which concerns on 4th Embodiment is provided. It is a figure for demonstrating operation | movement of the opening-and-closing means when the brake drum which concerns on 4th Embodiment is rotating.

Explanation of symbols

  10 drum brake, 12 brake drum, 14 brake shoe, 16 bottom surface, 18 cylindrical portion, 18a outer peripheral surface, 18b through hole, 26 wheel cylinder, 32 opening / closing means, 34 mounting member, 36 pin, 38 spring, 40 fin, 44 plate Spring, 46 holding member, 46a guide part, 48 opening part, 412 brake drum, 432 opening and closing means.

Claims (5)

A cylindrical brake drum having one end open and a bottom surface formed at the other end;
A through hole formed in the peripheral surface of the cylindrical portion;
Opening and closing means provided on the outer peripheral surface of the cylindrical portion and configured to close the through hole when the brake drum is not rotating,
When the brake drum is rotating, the opening / closing means is introduced into the through hole from the rotating shaft direction of the brake drum while shielding the outside air flowing from the downstream side in the brake drum rotating direction with respect to the through hole. A brake drum, wherein the brake drum is deformed toward a radially outer side of the brake drum by a centrifugal force so as to increase outside air, and an opening that intersects with a rotation axis direction of the brake drum is formed. The opening / closing means includes
A plate-shaped shielding member provided on the outer peripheral surface of the cylindrical portion so as to close the through hole when the brake drum is not rotated;
A holding member that holds both ends of the shielding member so that the shielding member does not fall off from the outer peripheral surface of the cylindrical portion on the downstream side and the upstream side of the through-hole in the rotation direction of the brake drum;
2. The brake drum according to claim 1, wherein a central portion of the shielding member is deformed in a radial direction of the brake drum by a centrifugal force when the brake drum rotates, and the through hole is opened.   The holding member is formed so as to guide both end portions of the shielding member in the circumferential direction of the brake drum when the central portion of the shielding member is deformed in the radial direction of the brake drum by centrifugal force when the brake drum rotates. The brake drum according to claim 2, further comprising a guided portion.   The brake drum according to claim 2, wherein the shielding member is weighted in a region not held by the holding member.   The brake drum according to claim 2, wherein the shielding member is made of a metal material that is elastically deformed.

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