JP2005180675A - Brake drum - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the occurrence of cavities at the root portion of a rib in manufacturing a brake drum by carrying out the die forming of molten material or semi-molten material. <P>SOLUTION: The brake drum 17 rotates together with a wheel, and is braked by being brought into frictional contact with a brake shoe, and is manufactured by carrying out the die forming of molten material or semi-molten material, and has a plurality of radially extending ribs 17c, 17d on its outside and inside surfaces. The phase of the ribs 17c on the outside surface is different from the phase of the ribs 17d on the inside surface. By this configuration, the increase of the thickness at the root portion of the ribs 17c, 17d can be suppressed compared with the case that the phase of the ribs 17c on the outside surface coincides with the phase of the ribs 17d on the inside surface, and the occurrence of cavities due to the drop of cooling speed during cooling after the die forming can be prevented. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention is a brake drum formed by molding a molten material or a semi-molten material that rotates with a wheel and is braked by frictional contact with a brake shoe, and includes a plurality of ribs extending radially on the outer surface and the inner surface of the brake drum. About things.

Such a brake drum is known, for example, from Patent Document 1 below.
US Pat. No. 5,383,537

  When cooling the brake drum after casting it with an aluminum alloy, for example, the thick part is harder to cool than the other parts. There's a problem. In addition, when the brake drum is processed by forging or pressing from an ingot having a semi-molten liquid phase, there is a problem that a cavity is also generated in the thick portion during cooling.

  Generally, a brake drum is a cup-shaped member with a small wall thickness. However, if radial ribs are formed on its outer and inner surfaces to increase rigidity and improve heat dissipation, the thickness of the rib base increases. In particular, when the outer surface rib and the inner surface rib are arranged in the same phase, there is a problem that the thickness of the base portion of the rib is remarkably increased and a cavity is easily generated.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to prevent a cavity from being generated at the base of a rib when manufacturing a brake drum that molds a molten material or a semi-molten material.

  In order to achieve the above object, according to the first aspect of the present invention, there is provided a brake drum formed by molding a molten material or a semi-molten material that rotates together with a wheel and is braked by frictional contact with a brake shoe. Thus, a brake drum is proposed in which a plurality of ribs extending radially are provided on the outer surface and the inner surface, and the phase of the rib on the outer surface is different from the phase of the rib on the inner surface.

  The first and second ribs 17c and 17d of the embodiment correspond to the ribs of the present invention.

  According to the configuration of the first aspect, the phase of the outer rib and the inner rib of the brake drum formed by molding the molten material or the semi-molten material are different from each other. Compared to the case where the phase is matched, the increase in the thickness of the base of the rib is suppressed, and the cooling rate is lowered at the time of cooling after mold processing of the molten material or semi-molten material, so that a cavity is generated. Can be prevented.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on examples of the present invention shown in the accompanying drawings.

  1 to 4 show an embodiment of the present invention. FIG. 1 is a longitudinal sectional view of a drum brake device of an automobile, and FIG. 2 is a longitudinal sectional view of a brake drum (a sectional view taken along line 2-2 in FIG. 3). 3 is a view in the direction of the arrow 3 in FIG. 2, and FIG. 4 is a view in the direction of the arrow 4 in FIG.

  FIG. 1 shows a drum brake device for a driven wheel of an automobile. A knuckle 11 fixed to a vehicle body includes an axle 11b extending outward from the vehicle body from a flange portion 11a. The inner race 13 of the ball bearing 12 is fitted to the outer periphery of the axle 11b and fastened with a nut 14, and the outer race supported by the inner race 13 via a plurality of balls 15 ... also serves as the shaft portion 16a of the axle hub 16. ing. The iron axle hub 16 includes a flange portion 16b extending radially outward from the outer end of the shaft portion 16a, and a short cylindrical hub portion 16c extending axially outward from the outer end of the shaft portion 16a, so that it cannot rotate. The ball can be freely rotated through the ball bearing 12 with respect to the fixed axle 11b.

  A hub hole 17a formed at the center of an aluminum brake drum 17 is fitted to the outer periphery of the hub portion 16c of the axle hub 16, and further, the hub hole 18a of the wheel 18 of the wheel W is fitted. A plurality of bolts 19 pass through the bolt holes 16d of the flange portion 16b, the bolt holes 17b of the brake drum 17, and the bolt holes 18b of the wheel 18, and the nuts 20 are screwed into these bolts 19. It is concluded with….

  The back plate 22 is fixed to the flange portion 11a of the knuckle 11 with a plurality of bolts 21. The labyrinth 23 is configured by the outer peripheral portion of the back plate 22 and the outer peripheral portion of the brake drum 17, thereby Prevents water and dust from entering the interior. The lower end of a pair of brake shoes 25, 25 (only one shown) is pivotally supported by an anchor 24 fixed to the lower end of the back plate 22 with a bolt 30 so that it is positioned between the upper ends thereof. A brake cylinder 26 is provided on the inner surface of the back plate 22. The pair of brake shoes 25, 25 are connected by a return spring 27 and a holding spring 28.

  Accordingly, when the brake cylinder 26 is driven in the extending direction by hydraulic pressure, the pair of brake shoes 25, 25 expands with the anchor 24 as a fulcrum, and the friction materials 29, 29 fixed to the outer peripheral surface thereof are the friction surfaces of the brake drum 17. The rotation of the wheel W can be braked by being in pressure contact with 17e.

  As is apparent from FIGS. 2 to 4, a large number of first ribs 17 c... Extending in the radial direction are provided at equal intervals on the outer peripheral side of the outer surface of the brake drum 17. A large number of second ribs 17d extending in the radial direction are projected at equal intervals on the outer peripheral side. The phase of the first ribs 17c and the phase of the second ribs 17d are shifted by a half pitch. Therefore, the second ribs 17d are disposed between the adjacent first ribs 17c and 17c, and the adjacent second ribs 17d and 17d are disposed. A first rib 17c is disposed between the first ribs 17c. Since the first and second ribs 17c, 17d, etc. are provided in the vicinity of the friction surface 17e of the brake drum 17 with which the brake shoes 25, 25 abut, the brake drum 17 is subjected to a load applied from the brake shoes 25, 25. The brake drum 17 having a function of increasing rigidity so as not to be deformed and a function of cooling the brake drum 17 whose temperature has risen due to heat generated by friction with the brake shoes 25, 25 by contact with air.

  The hub hole 17a formed at the center of the brake drum 17 is basically circular, and the brake drum 17 is positioned in the radial direction by closely fitting to the outer periphery of the hub portion 11c having a circular cross section of the knuckle 11. A part of the hub hole 17a is expanded in diameter by a plurality of (four in the embodiment) semicircular cutouts 17f. Therefore, a gap (see FIG. 1) is formed between the notches 17f and the outer periphery of the hub portion 11c.

  On the other hand, the wheel 18 of the wheel W is positioned in the radial direction by the bolt holes 18b being in contact with the spherical portions 20a of the nuts 20 ... Are not in close contact with each other, and a slight gap (see FIG. 1) is formed there.

  Accordingly, when moisture enters between the hub portion 11c of the iron knuckle 11 and the hub hole 17a of the aluminum brake drum 17, a potential difference is generated between the hub portion 11c and the hub hole 17a due to a difference in ionization tendency. As a stray current flows, there is a possibility that electrolytic corrosion occurs in the brake drum 17 made of aluminum. However, according to the present embodiment, even if moisture enters between the hub portion 11c of the knuckle 11 and the hub hole 17a of the brake drum 17, the moisture is notched 17f of the hub hole 17a by the centrifugal force that the wheel W rotates. Are passed through a gap between the hub portion 11c of the knuckle 11 and the hub hole 18a of the wheel 18 and then discharged to the outside. As a result, it is possible to reliably avoid situations where the knuckle 11 and the brake drum 17 are corroded and durability is lowered, and it is difficult to separate the brake drum 17 from the knuckle 11 due to corrosion.

  Further, when the aluminum brake drum 17 is cooled after being cast with a mold, if there is a part with a large thickness, the cooling of that part is delayed with respect to the other part (so-called “su”). There is a problem that occurs. For this reason, if the first ribs 17c on the outer surface of the brake drum 17 and the second ribs 17d on the inner surface are arranged in the same phase, the root portions of the first and second ribs 17c, 17d. Thickness increases and the possibility of cavities increases. However, according to the present embodiment, the phase of the first ribs 17c and the phase of the second ribs 17d are shifted by a half pitch, so that the thickness of the bases of the first ribs 17c. Can be prevented, and the quality of the brake drum 17 can be ensured.

  The embodiments of the present invention have been described above, but various design changes can be made without departing from the scope of the present invention.

  For example, in the embodiment, the brake drum 17 made of casting is exemplified. However, when the brake drum 17 is forged or semi-molten pressed from an ingot having a semi-molten liquid phase, a cavity is generated in the thick portion during cooling. In some cases, the present invention can be applied to the brake drum 17 made of forging or semi-melting press. Here, the semi-molten press is a method in which an ingot having a semi-molten liquid phase is molded by a mold, and is compression-molded at a lower speed than forging.

Longitudinal sectional view of automobile drum brake device 2 is a longitudinal sectional view of the brake drum (cross sectional view taken along line 2-2 in FIG. 3). 3 direction arrow view of FIG. 4 direction view of FIG.

Explanation of symbols

17c 1st rib (rib)
17d Second rib (rib)
25 Brake shoe W Wheel

Claims (1)

A brake drum formed by molding a molten material or a semi-molten material that rotates with a wheel (W) and is braked by frictional contact with a brake shoe (25), and a plurality of ribs extending radially on the outer surface and the inner surface of the brake drum (17c, 17d)
A brake drum characterized in that the phase of the outer rib (17c) is different from the phase of the inner rib (17d).

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