JPH04316726A - Integral type backing plate for drum brake - Google Patents

Abstract

PURPOSE:To provide a backing plate for a drum brake which reduces the number of machining processes. CONSTITUTION:A backing plate 1 is formed by using an aluminum alloy or an aluminum group composite material by a molten iron forging method or a die cast method and the thickness of a main part on which a force is exerted is increased and that of other part is decreased. Further, in a different embodiment, an iron piece is embedded in a part on which a force is applied or a part which is apt to wear.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backing plate for a drum brake used for braking automobiles and the like.

0002

[Prior Art] Drum brakes are widely used as brakes for automobiles. In this brake, the lining of a brake shoe is pressed against the inner peripheral surface of a drum that is connected to a wheel and rotates together. This is a device that brakes wheels by braking a drum using a frictional force, and is configured as illustrated in FIG.

In FIG. 7, reference numeral 1 denotes a backing plate made of steel plate, which is formed into a shallow dish shape by folding the edge 1a.
A drum 2 is provided across a. The drum 2 has a groove formed on its opening side end surface, and its folded edge 1a is inserted into the drum 2 as shown in FIG. 9, and its inner peripheral surface is placed inside the backing plate. An axle hole 3 is bored in the center of the backing plate, an axle is inserted therethrough, and a drum is connected thereto. 4 is a plurality of bolt insertion holes for fixing the backing plate to the vehicle body, and 5 is a hole for fitting and fixing the base of the foil cylinder 6. The two brake shoes 7 are movably supported along the backing plate in the lateral direction in FIG. 7 by a hold-down device 8 attached to the backing plate, and one end 7a is attached to an anchor 9 fixed to the backing plate with a stud 9a. the other end 7b is in contact with the foil cylinder 6.
The piston rod 6a is brought into contact with the piston rod 6a.

[0004] When pressure oil is sent to the foil cylinder 6 to push out the piston rod 6a, the brake shoe rotates about the anchor 9 and presses the lining 7c against the inner peripheral surface of the drum 2 to perform braking. When the pressure oil is released from the wheel cylinder 6, the brake shoes 7, 7 are returned to their positions by being pulled by the return springs 10, 11, and the lining 7c is separated from the drum to stop braking.

12 is a parking brake lever whose one end is pivotally connected to one brake shoe by a pivot 13; 14 is a cable guide for guiding a cable passed through a hole 15 to the other end of the lever 12 in order to operate the lever 12; be.

FIG. 8 is a front view of the backing plate with the wheel cylinder, brake shoe, parking brake lever, etc. removed, FIG. 9 is a sectional view taken along line A-A in FIG. 8, and FIG. 10 is a cross-sectional view taken along line B-B in FIG. FIG. Dust entering the drum is
This is suppressed by the fit between the edge 1a of the backing plate and the groove on the end surface of the drum, but in order to further improve this effect, the illustrated backing plate 1 has a ring-shaped dust shield 16 welded to its outer periphery.

As described above, many parts such as a foil cylinder, an anchor, a brake shoe, a parking brake lever, a cable guide, and a dust shield are attached to the backing plate 1, but in the past, steel plates were used and the parts were assembled through multiple steps. A backing plate was molded and each part was attached to it.

[0008] It is described in Japanese Utility Model Application Publication No. 55-97230 that the backing plate is cast from a light metal or light alloy, but this is done by casting the backing plate on the inside of the plate so that the bolts for mounting the parts are not exposed outside the backing plate. This method is different from the present invention because it is screwed together or fixed.

[0009]

[Problems to be Solved by the Invention] In order to improve the performance of automobiles, efforts have been made to make the car body lightweight, but if the backing plate is made of steel plate, it is unavoidable that the weight of the backing plate increases.

[0010] As for the backing plate, it is necessary to increase the strength of the portions bordered by diagonal lines in FIGS. 8 and 9, but the other portions do not require high strength. However, if it is made of steel plate, the wall thickness cannot be changed depending on the part, so it has unnecessary weight. Furthermore, although it has been put into practice to reduce the thickness of the backing plate by using a high-tensile steel plate, there is a limit to the weight reduction achieved by this method.

[0011] Moreover, since a multi-step press operation is added to this and parts are attached by a joining process such as welding and caulking, the number of processing steps increases, which is also disadvantageous in terms of manufacturing efficiency.

0012

[Means for Solving the Problems] In order to reduce the weight, the backing plate of the present invention is reinforced with aluminum alloy, ceramic particles or fibers, or reinforced with silicon carbide (SiC).
) using an aluminum matrix composite material, thickening only the necessary parts and reducing the thickness of unnecessary parts, using the molten metal forging method or die casting method (in this specification, these are referred to as pressure casting methods).
The above-mentioned problem has been solved by manufacturing the same.

[0013]

[Action] By using aluminum alloy or aluminum matrix composite material, only necessary parts are thickened and unnecessary parts are thinned.
In addition to reducing the weight of the backing plate, anchor parts, dust covers, etc., which were conventionally manufactured separately and attached to the backing plate by means such as welding or caulking, are now integrated with the backing plate, making manufacturing more efficient. can.

[0014]

[Embodiment] Fig. 1 is a front view of a backing plate showing a first embodiment of the present invention, Fig. 2 is a sectional view taken along the line CC in Fig. 1, Fig. 3 is a sectional view taken along the line DD in Fig. 1, and Figs. Showing a second example,
Figure 4 is a front view of the backing plate, and Figure 5 is E- in Figure 4.
6 is a sectional view taken along arrow F in FIG. 4. The same reference numerals are used for parts equivalent to those of the conventional example shown in FIGS. A to D, and the description thereof will be omitted, and will be described next.

The backing plate 1 is formed by a molten metal forging method in which a molten aluminum alloy or an aluminum matrix composite is injected into a mold and solidified under pressure, or by a pressure casting method such as die casting.

The molded backing plate is integrally formed with an anchor 9, a cable guide 14, and a dust shield 16, and has a hole 3 for passing the axle, a hole 4 for attaching to the vehicle body, a hole 5 for attaching the wheel cylinder 5, etc. formed,
The areas outlined with diagonal lines in Figures 1 and 2, namely the anchor 9, the peripheral area 17 of the hole 3 through which the axle passes, the peripheral area 18 on which the brake shoe slides, and the peripheral area 19 of the hole 5 for attaching the wheel cylinder are thickened. There is. These parts are subjected to a large amount of force during braking or are subject to a lot of wear due to sliding on the brake shoes.

FIG. 4 shows iron pieces 20 and 21 as shown in FIGS. 5 and 6 on the part 9a of the anchor 9 that comes into contact with the web of the brake shoe and on the peripheral edge 18 on which the brake shoe slides, where a large force is applied and the anchor 9 easily wears out. An example of embedding and reinforcement is shown. With this configuration, the aluminum alloy or aluminum matrix composite material can be reinforced and wear can be reduced.

[0018]

[Effects of the invention] (1) Since aluminum alloy or aluminum matrix composite material is pressure cast, the backing plate can be made thicker in important parts and thinner in other parts, and it can also be made lighter, with rigidity, strength, and durability suitable for drum brakes. Abrasion resistance can be ensured.

(2) The backing plate can be manufactured efficiently by pressure casting.

(3) Since conventional methods such as welding and caulking are not required, the number of man-hours can be significantly reduced.

[Brief explanation of drawings]

FIG. 1 is a front view of a backing plate of a first embodiment.

FIG. 2 is a sectional view taken along line CC in FIG. 1;

FIG. 3 is a sectional view taken along line DD in FIG. 1;

FIG. 4 is a front view of the backing plate of the second embodiment.

FIG. 5 is a sectional view taken along line E-E in FIG. 4;

FIG. 6 is a view taken along arrow F in FIG. 4;

FIG. 7 is a front view of a conventional drum brake with the drum removed.

FIG. 8 is a front view showing a portion of a conventional steel backing plate that requires strength.

FIG. 9 is a sectional view taken along line AA in FIG. 8 showing a portion of the backing plate that requires strength.

FIG. 10 is a sectional view taken along line BB in FIG. 8 showing a portion of the backing plate that requires strength.

[Explanation of symbols]

1 Backing plate 1a Edge 2 Drums 3 Shaft hole 4 Bolt hole 5 holes 6 Foil cylinder 6a Piston rod 7 Brake shoes 7a　One end 7b Other end 7c lining 8 Hold down device 9 Anchor 9a　Tack 10 Return spring 11 Return spring 12 Parking brake lever 13 Axis 14 Cable guide 15 Hole 16 Dust shield 17 Central part 18 Peripheral area 19 Peripheral area 20 Iron piece 21 Iron piece

Claims (2)

[Claims] 1. An integrated backing plate for a drum brake, in which at least an anchor part and a dust cover are integrally formed by pressure casting using an aluminum alloy or an aluminum matrix composite material. 2. The integrated backing plate for a drum brake according to claim 1, wherein iron pieces are embedded in the anchor portion where a large force is applied and the portion where the brake shoe slides and easily wears out.