JPS642994Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a wheel cylinder, an anchor, a brake shoe that is extendedly operated by the wheel cylinder using the anchor as a fulcrum, and a brake shoe that is connected to the lining of the brake shoe. The present invention relates to a drum brake device with an automatic adjustment device that automatically expands and adjusts to compensate for wear.

[Prior art]

In this type of brake system, a step is formed on the inner circumferential surface of the brake drum over a long period of time due to the friction between the brake shoe and the brake shoe. It is expanded and adjusted by. Therefore, when the brake drum is removed in the axial direction to replace the brake shoe, for example, the stepped portion formed on the inner circumferential surface of the brake shoe and the brake shoe may interfere with each other and obstruct removal of the brake drum. There was a problem that made the separation work difficult.

[Purpose of invention]

The present invention has been made in view of the above points, and an object of the present invention is to provide a drum brake for a vehicle in which the interference between the drum braking surface and the brake shoe can be easily canceled.

[Structure of the idea]

In order to achieve the above object, the present invention has a pair of brake shoes provided on the inner surface of a back plate, one end of which is brought into contact with an anchor fixed to the back plate, and the other end of each brake shoe is used as a fulcrum. In a vehicle drum brake device that performs a braking action by expanding the anchor, a mounting bolt for fixing the anchor has a shew web contact surface on the head thereof, a protrusion extending in the direction of the shew web, and an anchor that abuts the anchor. the anchor is formed with a tightening seat surface having an insertion hole for the mounting bolt penetrating through the back plate side, and a pressure receiving surface connected to the tightening seat surface; The anchor is fastened and fixed to the back plate by passing the shaft portion through a mounting hole of the back plate.

〔Example〕

Next, an embodiment in which the present invention is applied to a two-leaving type drum brake device will be described based on the drawings.

The drum brake device 1 includes a pair of wheel cylinders 3, 3 (one not shown) at the top and bottom positions when installed on the vehicle body, and a pair of brake shoes 4, 4 at the left and right positions on the inner surface of the back plate 2. ing.

Further, a cylinder hole 5 with one side open is formed in the wheel cylinder 3, and a piston 6 is fitted into the cylinder hole 5 in a fluid-tight and movable manner.
A hydraulic pressure chamber 7 is defined between the piston 6 and the rear wall, and a braking gap automatic adjustment device 8 is provided within the hydraulic pressure chamber 7.
A tapered clutch surface 3 in which a tapered clutch portion 8a at the end thereof is formed in a recess 3a in the inner rear wall of the cylinder.
b, and is arranged in frictional engagement with the recess 3a.
An atmospheric communication hole 10 is opened in the bottom part 3c of the wheel cylinder 3 and penetrates to the anchor 9 side formed integrally with the wheel cylinder 3 on the side opposite to the side where the cylinder hole 5 of the wheel cylinder 3 opens. The aim is to facilitate the assembly of the adjustment device and smoothen the adjustment operation.

The anchor 9, which is formed integrally with the wheel cylinder 3, has a tightening seat surface 11 formed substantially parallel to the back plate 2 on the side opposite to the back plate, and a tightening seat surface 11 formed on the side opposite to the back plate 2 from the cylinder hole 5 side of the tightening seat surface 11. A pressure receiving surface 12 is formed that stands up substantially at right angles in the direction opposite to the back plate, and one end of the atmospheric communication hole 10 is opened in the pressure receiving surface 12.

Further, in the tightening seat surface 11, there is provided a bolt insertion hole 11 that passes through the back plate side through which the shaft portion 14 of the mounting bolt 13 that fixes the anchor 9 side formed integrally with the wheel cylinder 3 to the back plate is inserted.
a is bored, and a ventilation groove 11b is recessed between the opening of the bolt insertion hole 11a and the opening side of the atmospheric communication hole 10.

On the other hand, the mounting bolts 13 are attached to flanges 1 at the upper portions of a pair of parallel side surfaces 15 and 16 of the rectangular parallelepiped.
The shaft portion 14 has a head portion 19 with protruding portions 7 and 18, and a small hole 22 through which a split pin 21 is inserted is bored near the tip of the shaft portion 14 on the side where the male thread 20 is provided.

The wheel cylinder 3 integrally formed with the anchor 9 is placed at a predetermined position on the back plate 2.
The open end side of the cylinder hole 5 is fixed with a mounting bolt 23 planted on the lower surface of the wheel cylinder 3 side, and the anchor 9 side is fixed with the mounting bolt 13, and the shaft portion 14 of the mounting bolt 13 is fixed with the bolt. Insert into the insertion hole 11a and back plate 2
The head 19 penetrates the mounting hole of the anchor 9 and extends to the lower surface side of the back plate 2.
Then, the lower surface of the head is brought into contact with the tightening seat surface 11, and the nut 25 is tightened via the spring washer 24 on the lower surface side of the back plate 2, and the anchor 9 side is fixed to the back plate 2. There is.

Further, one end of the shoe web 4a of the brake shoe 4 is brought into contact with the other side surface 15 of the parallel side surface of the mounting bolt 13 arranged as described above, and the collar portion 17 protruding from the upper part of the side surface 15 makes contact. This prevents the brake shoe 4 from floating up.

The atmosphere communication hole 10 is covered by one side 16 of the mounting bolt 13 that contacts the pressure receiving surface 12 of the anchor 9 to prevent dust from entering. They communicate through the gap in the insertion hole 11a, forming a communication path with the atmosphere.

The position of the hole 22 through which the split pin 21 inserted is formed near the end of the shaft portion 14 of the mounting bolt 13 that fixed the anchor 9 side to the back plate 2 is located at the head 19 of the mounting bolt 13. A hole is drilled at a position away from the nut 25 toward the distal end by a distance l _{2 that is greater than the distance l 1 between} the upper surface of the shew web 4a in contact with one side 15 and the tightening seat surface 11 of the anchor 9, and the nut 25 is screwed into the hole. After fitting, the nut 25 is prevented from separating from the mounting bolt 13.

Note that 26 is a hydraulic chamber 7 defined within the cylinder 3.
This is the mounting boss for a brake hose (not shown) that introduces pressurized fluid into the brake hose.

Next, the operation of this embodiment configured as described above will be explained.

The drum brake device 1 introduces pressure fluid supplied from a pressure fluid generation source (not shown) into a hydraulic pressure chamber 7, pushes a piston 6 by the action of the pressure fluid, and provides one end of each piston 6 to an anchor 9. A braking action is performed by expanding the other ends of the pair of brake shoes 4, 4 which are in contact with one side 15 of the mounting bolt 13, respectively.

During this braking operation, even if a force that lifts the brake shoes 4, 4 is generated, the flange 17 formed on the head 19 of the mounting bolt 13 will cause the brake shoes 4, 4 to float.
Effectively prevents floating.

The brake shoe clearance is kept constant by an automatic braking gap adjustment device 8 disposed inside the cylinder 3, and when the brake shoes 4, 4 are replaced, the brake shoe 4 is inserted into the shoe groove of the brake drum (not shown). If there is any interference with the brake shoe web 4a, loosen the nut 25 of the mounting bolt 13 that has the head 19 interposed between the pressure receiving surface 12 of the anchor 9 that one end of the shoe web 4a of each brake shoe 4 is in contact with. 25
After screwing the bolt until it touches the split pin 21 and separating the lower surface of the back plate 2 and the spring washer 24 by the same distance as _l2 , insert the shaft of the mounting bolt 13 from the lower surface of the back plate 2. When the end face of the part 14 is pressed with a tool and the mounting bolt 13 is moved by a distance l ₂ towards the inner surface of the back plate 2, the lower face of the head 19 touches the tightening seat face 11 of the anchor 9.
One side 15 of the head ₁₉ is spaced l ₁ less than l ₂ from the tightening seat surface 11.
The shoe web 4a that was in contact with the brake shoe 4 moves back to the position where it comes into contact with the shaft portion 14 of the mounting bolt 13 by the action of the return spring, and the interference between the brake shoe 4 and the shoe groove of the brake drum is released.

When performing this release, it is possible to prevent the mounting bolt 13 from falling into the brake drum, and
Thread the nut 25 onto the mounting bolt 13, and attach the split pin 2.
Since the work can be carried out while the brake shoe is not removed in step 1, there is no risk of losing bolts or nuts, and furthermore, reassembly work can be easily performed after replacing the brake shoe and adjusting and returning to the appropriate braking gap.

[Effect of idea]

As described above, the present invention has a shoe web contact surface on the head of the mounting bolt that fixes the anchor that is the fulcrum during expansion by contacting one end of the brake shoe, and a shoe web contact surface on the head end side of the shoe web contact surface. a tightening seat surface having a protrusion extending in the show web direction and an anchor abutting surface that abuts the anchor, the anchor having an insertion hole for the mounting bolt penetrating toward the back plate; and a pressure-receiving surface connected to the seat surface, and the shaft portion is passed through the mounting hole of the back plate and the anchor is fastened and fixed to the back plate.This prevents the brake shoe from floating and prevents the drum from rising. It is easy to remove the interference between the shoe groove and the brake shoe, and since the mounting bolt for release is always attached to the back plate and anchor, no parts are lost, and reassembly is easy. It can be done.

[Brief explanation of the drawing]

Figures 1 and 2 show an embodiment of a vehicle drum brake device according to the present invention, with Figure 1 being a cross-sectional front view of the main parts, and Figure 2 showing the assembled state of the anchor and mounting bolt. It is an exploded perspective view. 2 is the back plate, 3 is the wheel cylinder,
4 is a brake shoe, 4a is a shoe web, 8 is an automatic braking gap adjustment device, 9 is an anchor, 11 is a tightening seat surface, 11a is a bolt insertion hole, 12 is a pressure receiving surface, 1
3 is a mounting bolt, 14 is a shaft portion, 15 is a side surface in contact with the shew web 4a, 16 is a side surface in contact with the pressure receiving surface 12 of the anchor 9, 17 is a flange portion for preventing floating;
19 is a head, 21 is a cotter pin, 22 is a hole through which the cotter pin 21 is inserted, 23 is a mounting bolt implanted in the wheel cylinder 3, 24 is a spring washer, 2
5 is Natsuto.

Claims (1)

[Scope of utility model registration request] For vehicles in which a pair of brake shoes provided on the inner surface of the back plate are used as fulcrums by abutting one end of each on an anchor fixed to the back plate, and each other end is expanded for braking action. In the drum brake device, a shoe web contact surface is provided on the head of a mounting bolt that fixes the anchor;
A protrusion extending in the direction of the shew web and an anchor abutment surface that abuts the anchor are formed on the top end side of the head of the shew web abutting surface, and the anchor is provided with a mounting bolt that penetrates toward the back plate. The anchor is fastened and fixed to the back plate by forming a tightening seat surface with an insertion hole and a pressure receiving surface connected to the tightening seat surface, and passing the shaft portion through the mounting hole of the back plate. Characteristic drum brake device for vehicles.