KR19990025442U - Drum brake with self-adjusting air gap in the brake lining - Google Patents

Abstract

The present invention is a cylinder body 21 forming an outer body, two pistons (23, 25) installed to expand to both sides of the cylinder body 21 by the braking hydraulic pressure flowing into the cylinder body 21, the piston ( Two piston caps 27 and 29 which hold 23 and 25 in the cylinder body 21, two piston seals 31 and 33 which are designed to maintain the airtightness of the cylinder body 21, and two pistons ( In the drum brake 1 including the wheel cylinder 7 which is provided between the 23 and 25, and is composed of a spring 35 for applying a certain amount of elastic force to the pistons 23 and 25 in a state where no hydraulic pressure is provided. The two pistons 23 and 25 are machined in the circumferential direction on the outer circumferential surface thereof, and the flat plate 45 bent in the form of teeth is inserted into the engaging grooves 43 between the peaks 41. The flat plate 45 is bonded to the fixed frame 47 attached to both ends of the outer circumferential surface of the wheel cylinder body 21, A drum brake in which the air gap of a brake lining is automatically adjusted. When the pistons 23 and 25 are advanced above a threshold value during braking, the bending plate 45 is moved beyond the adjacent peak 41 by elasticity to the next peak. This prevents the expansion of the gap between the lining and the brake drum due to the wear of the lining, so that the air gap is always maintained at regular intervals.

Description

Drum brake with lining air gap auto-readjusting device

The present invention relates to a drum brake in which the air gap of the brake lining is automatically adjusted, and more particularly, the brake shoe is pressed against the brake drum by the hydraulic pressure transmitted from the master cylinder. It relates to a drum brake equipped with a mechanism for automatically resetting the gap between the lining and the brake drum.

In general, a brake of a vehicle is used to reduce the speed of a vehicle or to maintain a stable state of a vehicle. In general, a brake of a vehicle is operated by a pedal to control the speed of a vehicle or maintain a temporary stopping state while the driver frequently operates the vehicle while driving. In addition, a parking brake lever is provided for use when parking a car or stopping for a long time.

One type of brake device that is commonly used as a drum type brake is a brake shoe 105 which is hinged to the back plate 103 by a pin as shown in FIG. The wheel cylinder 107 is installed at one end of the 105 to rotate the brake shoe 105 to the rotation axis, and is installed outside the brake shoe 105 and connected to the wheel to expand the brake shoe 105. The brake drum 109 is configured to generate a braking force.

Such a brake device generates hydraulic pressure in the master cylinder when the driver manipulates the brake pedal by the foot, acting on the wheel cylinder 107, and the piston of the wheel cylinder 107 expands from side to side, causing the brake shoe 105 to be brake drum of the wheel. Pressing on 109 generates a braking force on the wheel.

Here, the structure and operation of the wheel cylinder 107 which acts to press the brake shoe 105 to the brake drum 109 of the wheel will be described in more detail as follows.

As shown in FIG. 2, a conventional wheel cylinder 107 has a structure of a cylinder body 121 having an oil inlet for receiving hydraulic pressure from a master cylinder, and a cylinder body 121 at a pressure provided at an oil inlet. Two pistons 123 and 125 installed to expand in both directions, two piston caps 127 and 129 for continuously maintaining the two pistons 123 and 125 coupled to the cylinder body 121, and two pistons 123 and 125 It is composed of a spring 131 or the like installed between the piston and applying a certain amount of elastic force to the piston (123, 125) in the state that the hydraulic pressure is not provided.

The wheel cylinder 107 configured as described above provides a force for compressing the brake shoe 105 shown in FIG. 1 to the brake drum 109 while the two pistons 123 and 125 are expanded by hydraulic pressure provided from the master cylinder.

However, in the conventional brum brake 101, when the brake lining 111 is worn, the gap between the lining 111 and the brake drum 109 is enlarged to maintain the gap at an appropriate interval to prevent the brake clearance from increasing. It is equipped with a gap automatic control mechanism.

Such a pore self-adjusting mechanism generally has an adjusting pinion 141 and a piston 143 at one end and the other end is inserted into the upper portion of the leading shoe 104 as shown in more detail in FIGS. 3 and 4. 145, the sliding sleeve is fitted in the adjustment sleeve 145, one end of the push rod 147, the adjustment pinion 141 is inserted into the upper portion of the trailing shoe 105, the trail to rotate by one click The control lever 149 is rotatably attached to the upper portion of the ring shoe 105 and the tension spring 151 is connected, and one end thereof is mounted on the same axis as the adjustment lever 149 so as to rotate synchronously. It consists of a fastener 155 inserted at the top of the trailing shoe 105 and returned to its original position by another tension spring 153.

Therefore, the hydraulic pressure acts on the wheel cylinder 107, and the brake shoes 104 and 105 are pressed against the brake drum 109 to perform braking. At this time, when the amount of rotation of the trailing shoe 105 is within the setting range, since the amount of the adjustment lever 149 attracted by the tension spring 151 is small, the adjustment lever 149 is the current gear of the adjustment pinion 141. It will remain in between, and will be returned to its original state by the tension spring 153 when braking is released.

On the other hand, when the amount of wear of the brake lining 111 is greater than the set amount, since the expansion amount of the brake shoes 104 and 105 exceeds the set range, the adjustment lever 149 is pulled downward by the tension spring 151, where Since the adjustment pinion 141 rotates by one click by the adjustment lever 149, the push rod 147 in the adjustment sleeve 145 is advanced, so that the positions of the brake shoes 104 and 105 returned when the brake is released are returned to their original positions. It is in a more expanded state.

In this way, the release positions of the brake shoes 104 and 105 are expanded beyond the initial release positions so that the gaps between the brake shoes 104 and 105 and the brake drum 109 are automatically adjusted to appropriate values.

However, in order to automatically adjust the air gap between the brake shoes 104 and 105 and the brake drum 109 as described above, an adjustment mechanism composed of various types of components has to be configured. The increase in the number of parts and the increase in expenses, such as non-productive factors were not a small number, and by using a large number of parts, the possibility of failure is increased and maintenance is difficult.

Therefore, the present invention has been devised to solve the problems of the conventional drum brake as mentioned above, and the air gap between the brake lining and the brake drum due to wear is installed outside the cylinder body of the wheel cylinder. Its purpose is to ensure that the pressing force applied to the brake drum acts uniformly by controlling the air gap automatically and maintaining it at regular intervals.

1 is an exploded perspective view showing a conventional drum brake device of the prior art.

FIG. 2 is a longitudinal sectional view of the wheel cylinder shown in FIG. 1. FIG.

3 is an assembly view of the drum brake shown in FIG.

4 is a side cross-sectional view of FIG.

5 is an assembly view of the drum brake according to the present invention.

FIG. 6 is a partial longitudinal cross-sectional view of the wheel cylinder shown in FIG. 5. FIG.

* Description of the symbols for the main parts of the drawings *

1: drum brake 3, 5: brake shoe

7: wheel cylinder 11: brake lining

21: wheel cylinder body 23, 25: piston

41, 41 ': Mount 43: Hanging groove

45: bending plate 47: fixed frame

In order to achieve this object, the present invention provides a cylinder body forming an outer body, two pistons installed to expand to both sides of the cylinder body by braking hydraulic pressure flowing into the cylinder body, and two pistons for maintaining the piston in the cylinder body. Drum brake including a cap, two piston seals designed to maintain the airtightness of the cylinder body, and wheel cylinders, which are installed between the two pistons and apply a certain amount of elastic force to the piston in the absence of hydraulic pressure. In the two pistons, a plurality of mountain molds are machined in the circumferential direction on the outer circumferential surface, and a plate bent in the form of teeth is inserted into the engaging groove between the mountain molds, and the plate is fixed to both ends of the outer circumferential surface of the wheel cylinder body The air gap of the brake lining connected to the frame is automatically adjusted. To provide rum brakes.

Hereinafter, with reference to the accompanying drawings will be described an embodiment of the present invention in more detail.

The drum brake according to the present invention is designated by reference numeral 1 in FIG. 5 and the conventional complicated mechanism for automatically adjusting the gap between the brake drum and the brake lining 11 is eliminated.

The drum brake 1 of the present invention thus comprises a part 10 for actuating the parking brake, the back plate 2, the wheel cylinder 7, the brake shoes 3, 5, the tension spring 9. consist of. Here, the back plate 2 serves to serve as a base on which various parts are mounted, and the wheel cylinder 7 is pivotally mounted to the back plate 2 like the conventional wheel cylinder 7. It is provided between (3, 5) and expands by the braking hydraulic pressure which flows in, and presses the brake shoe (3, 5) to a brake drum. When the brake spring is released, the tension spring 9 restores the brake shoes 3 and 5 to their original positions since the pistons 23 and 25 are returned to their original positions.

At this time, the wheel cylinder 7 has a basic configuration similar to that of a conventional conventional wheel cylinder, as shown in FIG. 6, and the cylinder body 21, the pistons 23 and 25, and the piston seals 31 and 33. And a compression spring 35. Here, the cylinder body 21 is configured to form the outer body of the entire wheel cylinder 7, and two pistons 23 and 25 are inserted at both ends of the cylinder body 21, which are the pistons 23 and 25. ) Slides on both sides by the hydraulic pressure transmitted from the master cylinder.

In addition, the leakage of the braking oil flowing into the cylinder body 21 is prevented by the piston seals 31 and 33 inserted into the pistons 23 and 25, and the piston seals 31 and 33 are in close contact with the inside of the piston seals 31 and 33. The spring seat 30 is mounted with a compression spring 35 for urging the pistons 23 and 25 outward when no hydraulic action is applied.

At this time, a plurality of peaks 41 are machined in the circumferential direction on the outer circumferential surfaces of the pistons 23 and 25, and a locking groove 43 is formed between the peaks 41 and the adjacent peaks 41 ′. In addition, an annular sealing seal 51 is wound in the circumferential direction to prevent the leakage of hydraulic oil inside the wheel cylinder 7 just below the mount 41 at the lowermost end of the outer circumferential surface of the pistons 23 and 25.

One end of the serrated bent plate 45 is inserted into the engaging grooves 43 between the hills 41 and 41 'to prevent the pistons 23 and 25 from being separated. The other end divided is respectively joined to the fixed frame 47 attached to the both ends of the outer peripheral surface of the wheel cylinder body 21, respectively. At this time, in the plurality of mountain molds 41, the flanks 49 facing both ends of the wheel cylinder 7 are inclined, and the flanks 51 facing the centerline of the wheel cylinder 7 are at right angles. have. In addition, the bent shape of the flat plate 45 has both end sidewalls 53 formed at right angles so as to act like teeth by interaction with the engaging groove 43, and the center side wall 55 has a flank surface. The inclined surface inclined at the same angle as 49 is formed. At this time, the side wall 55 is extended to be relatively more elastic than the side wall 53.

Therefore, the drum brake 1 of the present invention configured as described above has the following function.

The braking pressure generated in the master cylinder by the driver's brake pedal operation is supplied into the wheel cylinder 7 through the oil inlet of the cylinder body 21, and the pistons 23 and 25 are pushed to both ends by the supplied hydraulic pressure. The brake shoes 3, 5 are pressed against the brake drum and braking is thereby performed. At this time, if the expansion amount of the brake shoes 3 and 5 and the pistons 23 and 25 stays within the threshold value, the pistons 23 and 25 return to their original positions when the brake pressure is released, and the braking mechanism is repeatedly performed. do.

At this time, when the brake lining 11 is worn while the braking is repeated, the amount of expansion of the brake shoes 3 and 5 is increased, and thus the amount of expansion of the pistons 23 and 25 is also increased. As such, when the expansion of the pistons 23 and 25 due to the wear of the lining 11 exceeds the threshold, the peaks 41 of the pistons 23 and 25 overcome the elasticity of the side wall 55 of the bending plate 45 and move forward. It is seated in the engaging groove 43 between the 41 and the next mountain 41 '.

In this way, once the end of the bending plate 45 exceeds the peak 41, the relatively large vertical side wall 53, even if the braking is released, can not cross the vertical flank 51 of the peak 41, the piston (23, 25) cannot return to the original position.

Accordingly, when the brake is released, the pistons 23 and 25 are not returned to their original positions, but are set to one space forward and are pushing the brake shoes 3 and 5 toward the drum. In braking operation, by reducing the air gap substantially expanded by the amount of lining wear, it is possible to substantially maintain the air gap between the drum and the brake shoes 3, 5 in the same state as before.

Therefore, according to the drum brake of the present invention, even though the brake lining is worn out due to repeated braking, the gap between the lining and the brake drum is enlarged, the expansion amount of the wheel cylinder piston is larger than the threshold value due to the increase of the expansion of the brake shoe. As the bending plate, which is connected to the fixed frame of the wheel cylinder outer circumference, is inserted into the next locking groove over the mountain formed on the outer circumference of the piston, the piston is not returned to its original position in braking release state and is set at the position where the lining wear is advanced. The next braking compensates for void expansion due to lining wear, which automatically maintains the size of the void within the set range.

Therefore, since there is no need to install a separate mechanism for adjusting the air gap inside the drum brake, it is possible to reduce the cost incurred by the separate mechanism, reduce the production time or labor, and simplify the parts, Since the possibility can be significantly reduced, the productivity of the drum brake can be improved.

Although the present invention has been shown and described in connection with specific embodiments, it is common knowledge in the art that various modifications and changes can be made without departing from the spirit and scope of the invention as indicated by the appended utility model registration claims. Anyone who has a can easily know.

Claims (5)

A cylinder body 21 forming an outer body, two pistons 23 and 25 installed to expand to both sides of the cylinder body 21 by braking hydraulic pressure flowing into the cylinder body 21, and the two pistons. Two piston caps (27, 29) for holding (23, 25) in the cylinder body (21), two piston seals (31, 33) adapted to hold the airtight of the cylinder body (21), and Drum brake including a wheel cylinder (7) consisting of a spring (35) installed between the two pistons (23, 25) to apply a certain amount of elastic force to the pistons (23, 25) in the state that no hydraulic pressure is provided ( In 1), the two pistons (23, 25) has a plurality of dies 41 are machined in the circumferential direction on the outer circumferential surface, the plate groove bent in the form of a sawtooth in the engaging groove 43 between the dies 41 45 is inserted, and the flat plate 45 is provided at both ends of the outer circumferential surface of the wheel cylinder body 21. The drum brake is automatically adjusted to the gap of the brake lining, characterized in that bonded to the fixed frame 47 attached to the. According to claim 1, wherein the plurality of mountain (41) of the outer peripheral surface of the piston (23, 25) both end flank surface 49 is an inclined surface, the center flank surface 51 is a right angle surface Featuring drum brakes. 2. The drum brake according to claim 1, wherein the bending plate (45) has both end sidewalls (53) at right angles and the center side wall (55) is inclined surfaces. The drum brake according to claim 1, wherein the bending plate (45) extends longer than the center side wall (55) than both end side walls (53). The drum brake according to claim 1, wherein an annular sealing seal (51) is wound in the circumferential direction at a lower end of the outer circumferential surface of the piston (23, 25).