JPS6221784Y2 - - Google Patents

Description

[Detailed description of the invention] This invention restricts the movement of the shoe assembly beyond what is necessary for its function, and prevents damage to the boot due to excessive movement of the shoe assembly and prevents damage from the piston of the shoe assembly. This relates to a shed-floating type drum brake that prevents separation.

A shoe floating type drum brake generally includes a wheel cylinder and an anchor block fixed to a backing plate, and a shoe assembly disposed between the wheel cylinder and the anchor block. The anchor block has a block shape and is fixed at a position diametrically apart from the wheel cylinder of the bucking plate. and a planar shoe receiving surface facing in the circumferential direction. The shoe assembly has a semi-annular shape, and is brought into contact with the shoe receiving surface at the convex end surface formed at one end on the anchor block side, while the diameter of the piston of the wheel cylinder piston is at the other end. It has a web that is engaged with an engagement groove formed in the direction. This shoe assembly is expanded by the piston of the wheel cylinder, and is pressed against the brake drum to suppress its rotation. The structure prevents it from lifting off the plate.

However, due to its functionality, this shoe assembly cannot be firmly fixed to the bucking plate, so if it receives a large impact from falling during assembly work on the vehicle or during transportation prior to that, the brake There was a risk that the shoe would move significantly and become detached from the piston or get stuck between the piston and the wheel cylinder body, damaging the boot and the wheel cylinder body. Such damage has a serious impact on brake performance, is extremely difficult to repair, and significantly reduces work efficiency, but no appropriate countermeasures have been taken in the past.

The present invention was developed against the background of the above circumstances, and provides a shoe floating type drum brake that is equipped with a means to prevent the shoe assembly from moving excessively even in the event of a fall. The purpose is to
In a drum brake equipped with an anchor block (b) and a shoe assembly (c), from the inner circumference side of the end of the web on the anchor block side to the anchor block side, beyond the extended surface of the shoe receiving surface and at the center It extends with a certain gap between it and the side end face, and engages with the center side end face when the show assembly moves, thereby preventing the show assembly from moving radially outward beyond the above gap. The reason lies in the fact that the protrusions are integrally formed.

In the drum brake configured as described above, even if a shock is applied during assembly to a vehicle, the movement of the shoe assembly is restricted by the engagement of the protrusion with the center side end surface of the anchor block. Therefore, the web does not move significantly and separate from the engagement groove of the piston, and damage to the dust boot, wheel cylinder body, etc. is avoided.

In addition, the above effects can be obtained by making only slight changes to the shape of the web, so it is possible to improve the safety of the brake without increasing manufacturing costs, and it also eliminates troublesome work such as repairs. , the effect of improving work efficiency can be obtained.

Hereinafter, one embodiment of the present invention will be described based on the drawings.

In FIG. 1, a wheel cylinder 4 is fixed on a backing plate 2, and a pair of shoe assemblies 6, 8 are arranged on the left and right sides of this wheel cylinder 4. As shown in FIG. The shoe assemblies 6, 8 have a semi-annular web 10 on the innermost side, a rim 12 is welded to the outside thereof, and a lining 14 is attached to the outer peripheral surface of the rim 12. Further, a pair of pistons 16 are fitted in the wheel cylinder 4 in a liquid-tight and slidable manner as shown in FIG.
8 and the piston insert member 2 press-fitted therein.
It consists of 0. Piston insert member 2
An engagement groove 22 having a rectangular cross section and extending in the diametrical direction of the piston 16 is formed in the head of the piston 0, and a groove 22 is formed in the head of the piston 16 to prevent foreign matter from entering between the piston insert member 20 and the wheel cylinder body 24. A boot 26 is attached for doing so. One end of the web 10 of the shear assembly 6, 8 is
The piston insert members 20 are urged toward each other by the return spring 28, and are prevented from approaching each other beyond a certain level by the strut device 29 stretched between the two shoe assemblies 6, 8. The piston body 18 is engaged with the engagement groove 22, and the force applied to the piston body 18 by hydraulic pressure is transmitted to the web 10 via the piston insert member 20.

The other end of the web 10 is a retainer spring 30.
It is urged in the direction of contacting the anchor block 32 by the anchor block 32. The anchor block 32 has a block shape and has a rivet 3 at a position diametrically apart from the wheel cylinder 4 of the bucking plate 2.
6, and as shown in FIG.
and a planar shoe receiving surface 42 facing in the circumferential direction of the backing plate 2. web 10
is brought into contact with the shoe receiving surface 42 at an end surface 44 that is convex toward the anchor block 32 and is formed at the end opposite to the side that is engaged with the engagement groove 22 . Further, web protrusions 34 are provided on the inner and outer circumferential sides of the end of the web 10 that is brought into contact with the anchor block 32, respectively.
35 are integrally formed. These web protrusions 34 and 35 extend toward the anchor block 32 beyond the extended surface of the shoe receiving surface 42 and with a certain gap between them and the center end surface 38 and the outer peripheral end surface 40, respectively. I'm forced to. These web protrusions 34, 35 have end faces 38, 4, respectively.
0 prevents the web 10 from moving radially outward and radially inward beyond the above-mentioned gap, and this gap prevents the show assemblies 6 and 8 from moving beyond what is necessary for their functionality. The size is determined to be such that it can restrict movement.

In the drum brake configured as described above, if hydraulic pressure is applied to the wheel cylinder 4, the piston 1
6, the shoe assemblies 6 and 8 are pressed against a brake drum (not shown) attached to the rotating part side, and rotation of the brake drum is suppressed by solid friction between the lining 14 and the brake drum. At this time, the shoe assemblies 6, 8 are moved, and the lining 14 is worn out due to repeated braking.
radially outward movement of the web protrusions 34,3
5 and the anchor block 32. However, if the shear assemblies 6, 8 move beyond the amount of movement required for their functions, the web protrusions 34, 3
5 comes into contact with the anchor block 32, thereby being reliably blocked. Therefore, even if the drum brake is subjected to a large shock due to falling during transportation, etc., before it is assembled to a vehicle, the show assemblies 6 and 8 may come off from the piston insert member 20 or the piston insert member may be damaged. There is no fear that the boot 26, wheel cylinder body 24, etc. will be damaged by getting between the wheel cylinder body 20 and the wheel cylinder body 24.

Furthermore, the web protrusions 34 and 35 according to the present invention are integrally formed by slightly changing the shape of the conventional web 10, and do not require any new parts to be attached during the assembly process, and do not involve the conventional work process. There is almost no increase in manufacturing costs.

The shape and size of the web protrusion and the size of the gap between the web protrusion and the anchor block can be varied depending on the type of drum brake and considering the ease of machining.

Although not illustrated in detail, the present invention can be implemented in various modifications and improvements based on the knowledge of those skilled in the art.

[Brief explanation of the drawing]

FIG. 1 is a front view of a drum brake assembly which is an embodiment of the present invention, FIG. 2 is a sectional view showing the engagement state between the wheel cylinder and the shoe assembly in FIG. 1, and FIG. FIG. 2 is an explanatory diagram showing the state of engagement between the anchor block and the shoe assembly in FIG. 1; 2...Bucking plate, 4...Wheel cylinder, 6, 8...Shew assembly, 10...
Web, 16...Piston, 22...Engagement groove, 3
2... Anchor block, 34, 35... Web protrusion, 38... Center side end surface, 42... Shoe receiving surface, 44... End surface.

Claims (1)

[Claims for Utility Model Registration] A wheel cylinder fixed to a bucking plate; an anchor block having a center side end face facing the center side of the plate and a planar shoe receiving surface facing the circumferential direction of the backing plate; are respectively arranged between, and
A web that is brought into contact with the shoe receiving surface at one end that is convex toward the anchor block side, and that is engaged at the other end in an engagement groove formed in the diametrical direction of the piston of the wheel cylinder. In a drum brake equipped with a shoe assembly, the web extends from the inner peripheral side of the one end of the web to the anchor block side, beyond the extended surface of the shoe receiving surface, and between the end surface on the center side. A protrusion is integrally formed on the end face of the center side of the protrusion, which extends out with a certain gap between the protrusions and engages with the protrusion when the shoe assembly moves, thereby preventing the shoe assembly from moving radially outward beyond the gap. Drum brakes are characterized by: