JPS5891939A - Drum brake - Google Patents

Abstract

PURPOSE:To easily perform initial adjustment of a shoe clearance, by protrusively providing manually adjusting protrusions of larger pitch than a ratchet of an automatic adjusting wheel from one of the adjusting wheel or adjusting rod. CONSTITUTION:A plural number of protrusions 26 radially protruded with a circumferential pitch larger than of a ratchet 18a are provided in surfaces peripherally of an adjusting rod 15. This protrusion 26 is used for manual adjusting when an initial shoe clearance is adjusted under a condition fixed with a brake drum 13 to a wheel, considering work efficiency, the protrusion is set to a pitch larger than that of the ratchet 18a of an automatic adjusting wheel. While manual adjustment of a shoe clearance is performed by turning the rod 15 in both forward and reverse directions, and this protrusion is formed to a shape radially protruded without having directivity.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic adjustment device for drum brakes.

An example of a conventional automatic adjustment device for adjusting the gap between a brake shoe and a brake drum (hereinafter referred to as shoe gap) in a drum brake is shown in FIG. This is a duo-servo type brake, in which one end of the web of a brake shoe 2.3 placed opposite to the back plate 1 is connected by an automatic adjustment device 4, and the other end of the web is placed upright on the back plate 1. A double-acting wheel cylinder 8 provided on the back plate 1 is in contact with both webs. The brake shoes 2 and 3 are each pressed at their intermediate portions against the back plate l by shoe hold down springs 6.7. 9 and 10 are return springs that are hooked at one end to the anchor pin 5 and at the other end to the brake shoe 2.3;
Further, 11 and 12 are lining wear warning means attached to both brake shoes 2 and 3.

When pressure oil is introduced into the wheel cylinder 8 through a brake pipe (not shown), both brake shoes 2 and 3 are expanded, and regardless of the rotational direction of the brake drum 13, both brake shoes 2 and 3 act as leading shoes. Generates braking force.

The automatic dejust device 4 has a threaded rod portion 1 having a male thread.
A shoe engaging screw member 1 having a forked portion formed at one end of 4 m and non-rotatably locking the forked portion to the end of the brake shoe 2.
4, which has a cylindrical shape and is fitted into and supported by an adjustment rod which is threadedly engaged with the threaded rod part 14m of the shoe engaging screw member at the male threaded part on the inner surface, and whose forked part at the other end is non-rotatably engaged with the brake shoe 3. It consists of a shoe engagement pin 16 for stopping and an adjustment lever 17, and the adjustment rod 15 is integrally formed with a collar-shaped adjustment wheel 18 having a ratchet 18& formed on its outer periphery. The adjustment lever 17 has a substantially L-shape, and is pivotally supported by a pin 19 on the web of the brake shoe 3 at the center.One end engages with the ratchet 18m of the adjustment wheel so that it can be moved in only one direction, and the other end is The adjustment cable 20 is hooked to the anchor bin 5 and guided by a cable guide 21, and is hooked to a return spring 2H stretched between the brake shoe 2 and the brake shoe 2. The cable guide 21 is fixed to the brake shoe 3 web. subordinate
When the brake drum 13 fixed to the wheel is rotating in the direction of the arrow and pressure oil is introduced from the outside into the wheel cylinder 8, the brake shoe 3 slides against the brake drum 13 and rotates clockwise. It moves minutely and presses the brake shoe 2 via the automatic adjustment device 4, and the brake shoe 2 comes into contact with the anchor pin 5 to generate a braking force as a duo-servo type brake. At that time, if the brake shoes 2, 3 are worn beyond a predetermined range, the amount of clockwise movement of the brake shoes 3 will increase, so the adjustment lever 17, which is pivotally supported by the brake shoes 3, It is pulled by the adjustment cable 20, rotates clockwise about the pin 19 as a fulcrum, passes over the ratchet 18m of the adjustment wheel by one tooth, and engages with the next tooth.

When the brake is released, both brake shoes 2゜3 return to their original positions by the action of return springs 9 and 10.
The adjustment lever 17 rotates counterclockwise under the action of the return spring 22 until the adjustment cable 20 is tensioned, so the adjustment wheel 18 rotates and the shoe engagement screw member 14 is screwed out, allowing both brake shoes to be tightened. 2 and 3 in the direction of the brake drum 13 to adjust the shoe gap to an appropriate range.

In this type of drum brake, which is equipped with an automatic adjustment device that adjusts the shoe gap by locking a pair of brake shoes, when manufacturing and assembling a car, or when installing a brake drum, the shoes are sometimes installed using the procedure shown in Figure 2. Perform initial gap adjustment and work. That is, one driver 24 or special tool is inserted through the adjustment window 23 of the back plate to disengage the adjustment lever 17 from the adjustment wheel 18, and then the second driver 25 or special tool is inserted. After the adjustment wheel 18 is rotated by a ratchet 18m to bring both brake shoes 2.3 into contact with the brake drum 13, the ratchet 18m is returned by a specified number of teeth to provide a predetermined shoe gap.

In this way, in the conventional automatic adjustment device for drum brakes, the initial adjustment of the shoe gap is done by using two screwdrivers or special tools to make tooth shapes that can be fed in only one direction for automatic adjustment, and also to compare the pitch. Since this is done by rotating a small ratchet in both forward and reverse directions, the adjustment work is extremely complicated and requires a certain degree of skill. In order to solve these conventional problems, the present invention provides a protrusion for manual adjustment with a pitch larger than that of the ratchet of the adjustment wheel for automatic adjustment, by protruding from at least one of the adjustment wheel or the adjustment rod. The purpose is to measure the resolution of problems.

The present invention will be explained below with reference to the drawings. The same symbols as before represent the same parts. FIG. 3 shows a first example in which the present invention is applied to the automatic adjustment device for the above-mentioned duo servo type brake.
An example is shown. One of the two brake shoes 2 and 3 placed opposite to the back plate 1 fixed to the vehicle body! 1
The automatic adjustment device 4 interposed between the fork part 1 and the forked part 1
4b and a threaded rod portion 14 with a male thread, the shoe engaging screw member 14 non-rotatably locks onto the end of one brake shoe 2 at the forked portion 14b, and a cylindrical inner circumferential surface. An adjustment rod 15 that is screwed into the female thread of the adjustment rod, a collar-shaped adjustment wheel 18 that is integrally formed on the outer periphery of the adjustment rod, and a collar-shaped adjustment wheel 18 that is rotatably fitted to one end of the adjustment rod 15 to support the adjustment rod 15. It consists of a shoe engagement pin 16 that non-rotatably locks the forked part 161 to the end of the other brake shoe 3, and a ratchet 181 is attached to the outer periphery of the adjustment wheel 1B.
The saletail is formed. 17 is an almost L-shaped adjustment lever, the center part of which is pivotally supported by the brake shoe 3 web with a pin 19, and one end engaged with the ratchet 18m of the adjustment wheel so that it can be moved in only one direction.
The other end is hooked to the anchor pin 5 and holds the adjusting cable 2o guided by a cable guide 21 fixed to the web of the brake shoe 3, and a return spring 22 is stretched between the brake shoe 2 and the brake shoe 2. It is. A plurality of protrusions 26 are provided on the outer surface of the adjustment rod 15 so as to protrude in the radial direction with a larger pitch in the circumferential direction than the ratchet 181. These multiple protrusions 2
6 is used for manual adjustment when adjusting the initial shoe gap with the brake drum 13 fixed to the wheel, and in consideration of work efficiency, the pitch of the ratchet 18m of the adjustment wheel for automatic adjustment is used. ,
Set it to a value greater than 1. Furthermore, since the manual adjustment of the shoe gap is made by rotating the adjustment rod 15 in both forward and reverse directions as described above, the shape of this protrusion 26 is ratcheted.
Unlike the 8m, it has a shape that does not project in the radial direction and has no directionality. Next, the action will be explained.

The initial adjustment of the shoe gap, which is sometimes performed during the manufacture and assembly of automobiles and other brake drum installations, is performed by inserting a screwdriver or special tool through the adjustment window of the back plate 1 and securing the adjustment lever 17 to the adjustment wheel 1B. With the shoe removed, the second
When engaging the second screwdriver with the manual adjustment protrusion 26, the manual adjustment protrusion 26 has no directionality and has a larger pitch than the ratchet 18m of the adjustment wheel 18, so the second driver is engaged with the manual adjustment protrusion 26. It is easy to lock and rotate, the adjustment rod can be rotated quickly, and the efficiency of the initial adjustment of the shoe gap is significantly improved. In this case, the protrusion 26 for manual adjustment may be provided on the side surface of the adjustment wheel 18 to produce the same effect. Note that the operation after the initial shoe gap adjustment is the same as the conventional one.

FIG. 4 shows a second embodiment. The screwing relationship between the shoe engaging screw member 14 and the adjusting rod 15 is reversed from that in the first embodiment. In other words, the threaded part 15'a of the adjustment rod 1 is screwed into a shoe engaging screw member 14' having a female thread carved on the inner surface of the cylindrical body, and the adjustment wheel has a ratchet 18a formed on the outer periphery of the adjustment rod 1. 18 is integrally formed, and a shoe engages □Bin! at one end.
6 is fitted. Therefore, the adjustment wheel 18 is rotated by the adjustment lever 17, and the adjustment rod 1da is screwed out to automatically adjust the shoe gap. in this case,
The protrusion 26 for manual adjustment is attached to the adjustment rod 15'.
The adjustment wheel 18 is formed adjacent to the adjustment wheel 18 and protrudes in the radial direction with a low height to avoid interference with the adjustment lever 17, or is formed on the side of the adjustment wheel 18. The same effect as in the example can be obtained.

An automatic adjustment device similar to this embodiment can also be applied to a uni-servo brake, which is used in a duo-servo type brake, in which the wheel cylinder is opened on one side and engages with one brake shoe to expand the brake shoe. and
11th! The same effects as in the example can be obtained.

FIG. 5 shows a third embodiment in which the present invention is applied to a leading trailing vehicle brake. This automatic adjustment device is a negative test device similar to the first embodiment in which the strut ``/'' is extended when the parking brake is released.The strut 27 interposed between the brake shoes 2 and 3 has a cylindrical shape. The shoe engaging screw member 28 has a female thread carved on the inner surface and locks the forked portion of the end to one brake shoe 2 in an immovable manner. , an adjustment rod 29 integrally formed with a collar-shaped adjustment wheel 18 with a ratchet (18 m) on the outer periphery, one end of which is rotatably fitted to the adjustment rod 29 to support the adjustment rod 29, and the other end A shoe engagement pin 31 that non-rotatably engages the forked portion of the brake shoe 3 and a parking lever 32 to be described later.
It becomes more. The adjustment lever 33 has one end connected to the brake shoe 3 web with a pin 34 together with the parking lever 32.
The bent edge 331 of the other end is in contact with the side edge of the parking lever 32. 35 is adjustment lever 3
3 in the counterclockwise direction. The center piece 33b of the adjustment lever 33 is engaged with the ratchet 18m of the adjustment wheel so that it can be moved only in one direction, and the slot 33e is engaged with a protrusion 311 provided on the shoe engagement pin 31. A plurality of protrusions 26 for manual adjustment protruding in the radial direction are formed on the outer surface of the adjustment rod 29 or on the side surface of the adjustment wheel 18 in the circumferential direction.

To explain the operation of the third embodiment, when the parking lever 32 is rotated about the pin 34 by operating the parking cable 38 during parking, the brake shoe 2
are expanded by the struts 27, and the brake shoes 3 are expanded by the reaction force. At that time, brake shoes 2 and 3
If the brake lining attached to the brake lining is worn beyond a predetermined range, the adjustment lever 33 is rotated clockwise by the action of the protrusion 31m of the shoe engagement pin that engages with its thrower 33e, and the air adjustment lever 33 is rotated clockwise. It passes over the ratchet 18 of the wheel by one tooth and engages with the next tooth.

When the operation of the parking cable s8 is released, both brake shoes 2 and 3 are returned by the action of the return spring □39, and the adjustment lever 33 is returned by the return spring 35, and the adjustment wheel 30 is rotated by one tooth and the strut is removed. 27 to adjust the shoe gap.

Adjustment of the initial shoe gap when attaching the brake drum can be performed using the manual adjustment protrusion 26 in the same procedure as in the first embodiment, so that the same effects as in the first embodiment can be obtained. .

FIG. 6 shows a fourth embodiment in which the present invention is applied to another type of automatic adjustment device for a leading-trailing pulse brake. This automatic adjustment device is a positive type that makes adjustments when operating the parking brake, and converts the input from the parking cable 40 into rotational motion, and uses a 5-shaped toggle lever 41 that presses the brake shoe 2 and the reaction force. It consists of a strut 42 that transmits information to the brake shoe 3. The five-shaped toggle lever 41 has one end engaged with the brake shoe 2 and the other end extending outside the back plate 1.

Also, the tip of the toggle lever 41 is equipped with an adjuster rod 51.
An adjustment lever 44 is pivotally supported by a locking pin 45 and engages with a ratchet 18 thread so that the adjustment wheel 18 integrated with the adjustment wheel 18 can be fed in only one direction. A strut 42 serving as an automatic adjustment device interposed between the brake shoes 2 and 3 includes a shoe engagement screw member 46, an adjustment rod 51, and a shoe engagement pin 47. The shoe engaging screw member 46 has one end pivoted to the toggle lever 41 by a locking pin 4s and is non-rotatably locked to the brake shoe 2, and the other end has a male threaded screw portion as described below. It is loosely inserted into the cavity of the shoe engaging pin 47 which has a cylindrical shape.

The adjustment wheel 18 has a ratchet 18m formed on its outer periphery, has a female thread formed on its inner surface, and has a ratchet 18 integrally provided on its side.
It is composed of a plurality of manual adjustment protrusions 26 that protrude in the radial direction and have a larger pitch in the circumferential direction than a. The shoe engagement pin 47 is made of a cylindrical body and the shoe engagement screw member 4
The adjusting rod 51 extends over the receiving side end face of the brake shoe 6 and comes into contact with the side surface of the adjusting rod 51, and is non-rotatably locked to the brake shoe 3 web at the forked portion on the other end side. 48 is a rotation stopper.

Brake shoe 2 operates as an automatic adjustment device.
．． When the parking cable 40 is operated in a state where the shoe gap exceeds a predetermined range due to wear of the lining attached to the lining, the adjustment lever 44 also rotates as the toggle lever 41 rotates, sending the ratchet 18m of the adjustment wheel. Automatic adjustment of the shoe gap is performed by extending the struts 42. Both brake shoes 2.
3 comes into contact with a brake drum (not shown) and the axial force of the strut 42 increases, the rotational resistance of the adjustment wheel 18 increases, and the force applied to the toggle lever 41 thereafter is absorbed by the adjustment spring 50.

The initial shoe gap adjustment work when installing the brake drum is
51 for manual adjustment! Since the process can be carried out in the same manner as in the first embodiment using the actuator 26, the same effects as in the first embodiment can be obtained.

In addition, in the above-mentioned IIi embodiment, when braking, both brake shoes are expanded by one wheel cylinder and come into contact with the brake drum to perform braking, but only one brake shoe is expanded by the wheel cylinder and the braking force is applied. It goes without saying that the same effect can be obtained even if applied to a type of brake that produces .

Further, in the above embodiment, the protrusion 26 for manual adjustment is provided protruding from the adjustment rod Is1, but the same effect can be obtained even if the protrusion 26 is provided protruding from the adjustment wheel 18.

As explained above, in a drum brake according to the present invention, a shoe engagement screw member that is non-rotatably engaged with one of a pair of brake shoes and an adjustment wheel having a ratchet formed on the outer periphery are fixedly installed. In addition, a protrusion for manual adjustment that has a larger pitch in the local direction than the adjustment rod and ratchet that is screwed into the shoe engagement screw member and protrudes from at least one of the adjustment rod or the adjustment wheel, and one end of which is connected to the adjustment rod. The automatic adjustment device has a shoe engaging pin that is rotatably supported and whose other end is non-rotatably locked to the other brake shoe, and an adjustment lever that engages with the ratchet of the adjustment wheel so that it can be fed only in one direction. The initial adjustment of the shoe gap, which is sometimes performed during the manufacture and assembly of automobiles and other brake drum installations, is performed by inserting a screwdriver or special tool through the adjustment window on the back plate to disengage the adjustment lever from the adjustment wheel. In this state, when engaging the second driver for initial shoe gap adjustment with the manual adjustment protrusion, the pitch is large, so the second driver must be engaged with the manual adjustment protrusion and rotated. The adjustment rod can be rotated easily and quickly, significantly improving work efficiency. Note that the manual adjustment protrusion can be used not only for initial adjustment of the shoe gap but also for reducing the diameter of both brake shoes when removing the brake drum.

[Brief explanation of the drawing]

Figure 1 is a front view of a conventional duo servo type brake, Figure 2
The figure is an explanatory diagram of the conventional initial adjustment work of the shoe gap, Figure 3 is a front view of a duo servo type brake showing the first embodiment to which the present invention is applied, and Figure 4 is the second embodiment to which the present invention is applied. FIG. 6 is a front view of a leading trailing brake according to a third embodiment of the present invention, and FIG. 6 is a leading trailing history brake to which the present invention is applied. FIG. 4 is a cross-sectional view of a main part of a fourth embodiment of the present invention. 18 back plate, 2.3? Brake shoe, 4: automatic adjustment device, 5: anchor pin, 8: wheel cylinder, 13 brake drum, 14114': shoe engagement screw member, 1 B, I B' near adjust rod, 16: shoe engagement pin , 17: Adjust lever, 18 Near adjust wheel, 18a: Ratchet, 2
0 Nearest cable, 23; Adjustment window, 26: Adjustment protrusion, 27: Strut, 28: Shoe engaging screw member, 29 Nearest rod, 31: Shoot rat, 4
4 Near adjuster lever, 46: Shoe engaging screw member, 4
7: Shoe engagement pin, 51 Near Azia Stroud agent Patent attorney front 1) Toshiyuki Haka 1 person Figure 2 1d 180 Figure 3 Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] 1. A brake drum fixed to a wheel, a pair of brake shoes arranged facing each other on a back plate fixed to the vehicle body side, and a brake shoe provided on the back plate and engaged with at least one of the brake shoes. In the drum brake, the drum brake has a wheel cylinder that expands the brake shoes to make contact with the brake drum, and an automatic adjustment device that is interposed between the pair of brake shoes and adjusts the gap between the shoes, the automatic adjustment device A shoe engaging screw member that is non-rotatably locked to one of the pair of brake shoes and an adjustment wheel having a ratchet formed on the outer periphery are fixedly installed and are screwed to the shoe engaging screw member. An adjustment rod, a protrusion for manual adjustment that has a larger pitch in the circumferential direction than the ratchet, and is protruded from at least one of the adjustment rod or adjustment wheel; one end is rotatably supported on the adjustment rod, and the other end is rotatably supported on the adjustment rod. A drum brake characterized in that the drum brake has a shoe engagement pin that is non-rotatably engaged with the other brake shoe, and an adjustment lever that engages with a ratchet of the adjusting wheel so as to be able to move in only one direction.