JPS5865338A - Automatic adjuster of brake gap in drum brake - Google Patents

Abstract

PURPOSE:To reduce wearing of a ratchet wheel, by dividing an adjusting lever into a main unit and ratchet plate, arranging the ratchet plate, in a state of not rotating but moving axially of the ratchet wheel when an excessive adjustment preventing spring is extended, and removing relatively sliding movement between the ratchet plate and the ratchet wheel. CONSTITUTION:An adjusting lever 17 and ratchet plate 10 are separately constituted, and the ratchet plate 10 is turnably connected by a pin 15, while one end of an overadjustment preventing spring 16, wound to the pin 15, is stopped to an edge part of the adjusting lever 17, and the other end is stopped to an edge part of the ratchet plate 10. Further the adjusting lever 17 and a protrusive element 7a of a receiver plate 7 are connected by a link 13. Here at application of an excessive brake, even if the adjusting lever 17 is rotated through the receiver plate 7 and the link 13 in accordance with leftward movement of a piston 3, the ratchet plate 10 is not rotated but moved in an equal direction to the piston 3 further by almost the same distance in accordance with movement of the pin 15, and relatively sliding action is not caused in a meshing part of the ratchet wheel 8 and the ratchet plate 10.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a braking III @ automatic adjustment device for drum brakes.

Conventionally, as a brake bolt-automatic inspection device, a nut is rotatably fitted to a piston of a wheel cylinder device, and the outer end of a bolt threaded into the nut is engaged with a brake shoe, and the outer end of the nut is engaged with a brake shoe. It has been proposed that the braking gap is adjusted by rotating a train fixed to the brake pedal in conjunction with the brake operation. In this type of IAIN, for example, as shown in Jikken@52-25093, a C-shaped adjustment bar is rotatably supported with its base end on the outer wall of the cylinder with a support shaft, and the tip of the adjustment lever is A frame member and an over-adjustment prevention spring are engaged with the pawl width, and extend between the intermediate portion of the adjustment lever and the outer end of the piston.

If the brake drum is operated harshly enough to cause expansion, that is, if the hydraulic pressure applied to the inside of the cylinder becomes excessive, the rotational resistance of the threaded part between the nut and adjustment bolt and the seat surface will increase, causing the wind turbine to is not rotated, the over-adjustment prevention spring is stretched, and the adjustment action of the brake bolt wAll is interrupted.

In such a case, the meshing force of the meshing part between the adjustment lever and the pawl width becomes excessive, and in this state, relative sliding occurs between the adjustment lever and the pawl width in the axial direction of the pawl width, so this sliding This causes significant wear on the contact surfaces, especially the pawl widths, and this results in a problem that normal meshing conditions are inhibited.

The present invention eliminates the relative sliding between the adjustment lever and the pawl width while receiving excessive engagement force, and improves the braking efficiency of drum brakes! The objective is to obtain a 111m VRH.

- To solve this problem, the present invention, in the braking arm automatic adjustment device according to i. The pawl plate is biased and engaged by the over-adjustment prevention spring, and when the over-adjustment prevention spring is extended, the pawl plate does not rotate, but moves in the axial direction of the pawl width, thereby causing the pawl plate to slide relative to the pawl width. is removed.

That is, the configuration of the present invention is such that a nut having a pawl width at the outer end is rotatably placed in the inner space of the piston of the wheel cylinder device.
the outer end of an adjustment bolt threaded into the cough nut engages the end of the brake shoe so that the pawl width is rotated adjacent to the movement of the piston; Automatic braking gap adjustment of the brake @ stomach, the hook is passed between the adjustment lever rotatably supported on the outer wall of the cylinder, the receiving plate fixed to the outer end of the piston, and the middle part of the adjustment lever. a link, a pawl plate that is rotatably supported by the IU lever with an overlapping bin and whose tip engages with the pawl width, and an edge of the pawl plate that is biased to the protrusion of the adjustment lever. and an over-adjustment prevention spring that allows relative rotation between the pawl plate and the adjustment lever when the load torque of the pawl width exceeds a predetermined value.

The present invention will be explained based on an example.

As shown in FIG. 2, a hollow piston 3 is fitted inside the cylinder 2, and a nut 4 is rotatably fitted into this hollow part. An adjustment bolt 5 is screwed into this nut 4, and a pawl width 8 is fixed to the outer end of the nut 4. piston 3
is movable in the axial direction, and has an annular receiving plate 7 fixed to its outer end. This configuration is almost the same as the conventional $11111111 automatic mu device.

An adjustment lever 17 made of a substantially triangular plate is rotatably supported at its end with a support shaft 22 on the outer wall of the cylinder 2, and is connected to the intermediate portion of the lever 17 and the protrusion 7a protruding from the receiving plate 7 described above. A connecting member, specifically a link 13 made of a wire rod, is connected.

An unfortunate configuration of the present invention is that the adjustment lever 17 and the pawl plate 10 that engage with the pawl width 8 are constructed separately, and normally both operate as one unit, and when the brake is applied excessively, the adjustment lever 17 rotates. Also, the claw plate 10 does not rotate, but is configured to move in the direction of movement of the piston.

The claw plate 10 has its base end superimposed on the adjustment lever 17 and is rotatably connected with the bin 15. Then, one end of the over-adjustment prevention spring 16 wound around the bottle 15 is locked to the edge of the adjustment lever 17, and the other end is locked to the edge of the claw plate 10, and the claw plate 10 is held by the force of the over-adjustment prevention spring 160. In FIG. 2, the adjustment lever 17 is biased to rotate clockwise.
The number is pressed onto an upwardly extending protrusion 1117a formed at the end of the plate.

Note that a receiver 14 is fixed to the outer wall of the cylinder 2, and an end of the adjustment lever 17 is supported on the receiver 14. Also, a protruding piece 21 is cut downward from the plate surface of the claw plate 10, and this protruding piece 21 and the outside of the cylinder 2! A return spring 20 is passed between the bottle 19 fixed to the hook, which causes the claw plate 10 to
The tip of the nail 118 is pressed lightly, and the nail 1
10 and adjustment lever 17 are returned. Therefore, the weight of the return spring 20 is the same as that of the over-adjustment prevention spring 1.
It is set smaller than the vine weight of 6. A dustproof boot 6 is locked between the outer end of the piston 3 and the outer end of the cylinder 2.

Next, to explain the operation of the device of the present invention, the cylinder 2 is fixed to the back plate of the drum brake, and the end of one platen is connected to the end side 19 of the adjustment bolt 5. The end of the other brake shoe is in the groove 18,
They are partially engaged by a spring stretched between them. When the brake deflection pressure fluid is supplied to the inside of the cylinder 2, the piston 3 is pushed to the left in FIG. At this time, the adjustment lever 17 is rotated clockwise about the support shaft 22 in FIG. 2 via the receiving plate 7 and the link 13, and the pawl plate 10 is also
7 and rotates the electric train 8.

In this way, when the braking gap is larger than a specified value, the nut 4 is rotated together with the model wheel 8, and the adjusting bolt 5 is screwed out, acting to reduce the moving gap. However, if the brake drum expands due to severe braking action, the rotational resistance of the threaded joint between the nut 4 and the adjustment bolt 5 and the seat surface will increase, and the pawl width 8 will be rotated by the pawl plate 10. be unable to do so. At this time, even if the alignment bar 17 is rotated via the receiving plate 7 and the link 13 as the piston 3 moves to the left, the over-alignment prevention spring 16 is bent and the claw plate 10 is held in that position. However, as the pin 1-5 connected to the adjustment lever 17 moves, the pawl plate 10 moves in the same direction as the piston 3-. No relative sliding or movement occurs. In this way - stabbing,
Sectile glands--actions are interrupted.

When the hydraulic pressure inside the cylinder 2 is released and the brake is released, the adjusting bolt 5, nut 4, and seven stones b are integrally moved by the force of the return spring applied to the pair of brake shoes. Along with this, the adjustment lever 17 is rotated counterclockwise via the link 13, and the claw plate 10 is simultaneously returned by the force of the return spring 20 by the protruding edge 17a, and the claw 8 is moved back. Climb over the claws and fall into the new claws and the temple of claws.

Since the present invention is configured as described above, when the brake is applied excessively, that is, when the hydraulic pressure applied to the cylinder 2 exceeds a predetermined value, the rotational resistance between the nut 4 and the adjustment bolt 5 increases, and at this time the piston Even though the adjustment lever 17 rotates as the adjustment lever 3 moves, the claw plate 10 does not rotate, but the adjustment lever 1
7 in the direction of movement of the piston 3. This nail 1
Since the moving layer of i10 and the movement of the piston 3 supporting the electric rate 8 are approximately equal to &t, no sliding occurs between them, and therefore, the meshing portion between the claw plate 10 and the electric rate 8 is worn out. can be prevented.

In contrast, with conventional devices, when excessive braking is applied,
Since the adjustment lever does not rotate and the mold wheel moves together with the piston, there is relative sliding between the pawl mold and the adjustment lever that engages with it, and the engagement force in this poem is caused by the tension of the over-adjustment prevention spring. Since it is in such an excessively stretched state, the wear caused by this vibration is significant, but this invention can eliminate this problem.

Moreover, according to the present invention, 1! Since the lever is simply divided into two parts, these parts are connected so that they can rotate relative to each other, and the adjustment lever is connected with a link so as to work with the piston, the structure is not so complicated compared to the conventional example. ,
It is also excellent in that it does not significantly affect cost.

[Brief explanation of the drawing]

Figure 11 shows the braking gap of 5g for the drum brake according to the present invention.
FIG. 2 is a partially cutaway side view of the 11m device, and FIG. 2 is a plan view thereof. 2 Niji Linda 3: Piston 4: Nut 5: II!
Bolt 6: Bolt 7: Receiving plate 8: Claw skewer 10: Claw plate
13: Link 16: Over-adjustment prevention spring 17: Adjustment lever 17a: Projection 22: Support shaft - Patent applicant: Kake Brake Industry Co., Ltd. Agent, Patent attorney: Toshio Yamamoto

Claims (3)

[Claims] (1) In the inner space of the piston of the wheel cylinder device,
A nut having a train at its outer end is rotatably supported, the outer end of an adjustment bolt screwed into the nut is engaged with an end of a brake shoe, and the train rotates in relation to the movement of the piston. An automatic adjustment device for drum brakes, which is designed to be used in a drum brake system, includes an adjustment lever that is rotatably supported by a shaft on a part of the outer wall of the cylinder, and an intermediate portion between the receiving plate fixed to the outer end of the piston and the adjustment lever. The link between the two and the one with the dowel pin on the ms lever.
a pawl plate that is rotatably supported and whose tip engages with the electric train; The braking gap of the drum brake is further provided with an over-adjustment prevention spring that allows relative rotation between the pawl plate and the adjusting lever when the value exceeds the value of tlJ'al!. 1@-0 (2) The leak is made of 11iI material, and its both ends are bent and inserted into the hole of the receiving plate and the hole of the adjustment lever (
Each locked special 11'Fl range v! Automatic braking adjustment device for drum brakes as described in A(1). (3) The drum brake braking system according to claim (1), wherein the over-adjustment prevention spring is wound around the bottle, and one end of the over-adjustment prevention spring is wound around the adjustment lever, and the other end is temporarily locked with a claw.