JP3418783B2 - Automatic adjustment of shoe gap for drum brake - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic shoe clearance adjusting device for a drum brake.

[0002]

2. Description of the Related Art An automatic shoe clearance adjusting device of this type is disclosed in Japanese Utility Model Publication No. 63-40667.

In this device, a strut extending horizontally between a brake shoe and a brake lever, an adjust lever rotatably provided on one brake shoe, and a feed claw portion of the adjust lever are engaged with adjusting teeth of the strut. And an adjusting spring for urging the adjusting lever to urge the adjusting lever to extend in the vicinity of the feed claw portion of the adjusting lever and bend the extending piece in the direction opposite to the back plate to form the riding guide portion.

By manually rotating the adjusting teeth in the reverse direction with a tool such as a screwdriver, the riding guide portion of the adjusting lever rides on the straight portion of the shoe return spring. The structure is such that the engagement is released.

[0005]

The above-mentioned automatic shoe clearance adjusting device has the following problems.

<A> When the lining of the brake shoe is worn, the relative position of the shoe return spring with respect to the adjust lever is displaced. As a result of the displacement of the shoe return spring, the riding position of the riding guide portion is displaced, and the manual adjustment operation is not stable over time.

<B> Except for the coil portion of the shoe return spring, the mounting load is regarded as important, so that its dimensional accuracy is not good. Further, when the spring is heat-treated, it is easily deformed by its internal stress, and it is technically difficult to keep the dimensional tolerance small. Furthermore, since both ends of the shoe return spring are hooked only on the shoe webs of the pair of brake shoes, the shoe guide spring of the adjust lever rides on the linear portion of the shoe return spring to exert the shoe force. The straight part of the return spring is easily displaced. As described above, due to the manufacturing variation of the shoe return spring and the displacement during the manual adjustment operation, the certainty that the engagement between the adjusting lever and the adjusting tooth can be released is low.

<C> When attaching or detaching the shoe return spring, unless the adjust lever is detached first when detaching and the shoe return spring is not assembled first when assembling, incorrect assembly or deformation of the adjust lever occurs.

The present invention has been made in view of the above points, and an object of the present invention is to provide an automatic shoe clearance adjusting device for a drum brake, which can ensure a stable manual adjusting operation for a long period of time. It is in.

[0010]

The invention according to claim 1 is
Equipped with an extendable screw coupling mechanism that regulates the outer diameter of the brake shoe, an adjust lever that responds to excessive expansion of the brake shoe automatically rotates the adjusting tooth of the screw coupling mechanism to automatically set the gap between the drum and the brake shoe. to the automatic shoe clearance adjustment apparatus of a drum brake to correct, Gerhard
-Reverse to the rotating direction of the adjusting tooth during automatic clearance adjustment
When you want to rotate. The adjustment teeth manually in a direction, riding on the site rigid member of the adjusting lever, characterized in that the engagement between the adjustment teeth of said adjustment lever is released,
It is a device for automatically adjusting the shoe clearance of a drum brake. The invention according to claim 2 is arranged between a pair of brake shoes,
Struts with an expandable and retractable screw coupling mechanism that adjust the gap between the brake shoes and the drum, an adjust lever that automatically rotates the adjustment teeth of the struts in response to an excessive expansion of both brake shoes, and the adjust lever. In a shoe brake automatic adjusting device for a drum brake equipped with an adjusting spring that applies an urging force in a direction for rotating the adjusting tooth, the adjusting tooth is manually operated in a direction opposite to the rotating direction of the adjusting tooth during automatic shoe clearance adjustment. in is rotated
The drum brake is characterized in that a riding portion for riding on the peripheral surface of the strut to release the engagement with the adjusting tooth of the adjust lever is formed in a part of the adjusting lever facing the peripheral surface of the strut. It is an automatic shoe clearance adjusting device. The invention according to claim 3 is arranged between a pair of brake shoes and responds to an excessive expansion of both brake shoes, and a strut with an expandable and contractible screw coupling mechanism for adjusting a gap between the brake shoes and the drum. and the adjustment lever to automatically rotate the adjustment teeth strut Te, the automatic shoe clearance adjustment apparatus of a drum brake equipped with the adjustment spring that gives biasing force in a direction to rotate the adjustment teeth on the adjustment lever, automatic shoe clearance adjustment Sometimes
The adjustment tooth in the direction opposite to the rotating direction of the adjustment tooth in
When manually Ru rotated, and characterized in that the formation of the raised portions riding rides on the site of the brake shoe to release the engagement with the adjustment teeth of the adjustment lever, to a portion of the adjustment lever which faces the site of the brake shoe It is an automatic shoe clearance adjusting device for a drum brake. The invention according to claim 4 is built in each shoe expanding mechanism arranged between both adjacent ends of the opposing brake shoes, and an expandable and retractable screw coupling mechanism for adjusting a gap between the brake shoe and the drum, and In response to an excessive expansion of the brake shoe, an adjusting lever that rotates the adjusting teeth of each screw coupling mechanism, and an adjusting spring that applies an urging force to the adjusting lever in the direction that rotates the adjusting teeth of a drum brake in the automatic shoe clearance adjustment device, the automatic shoe clearance adjustment
In the direction opposite to the rotating direction of the adjusting tooth in
When manually Ru rotates, the raised portions multiplication to release the engagement between the adjustment teeth of the shoe expanding adjustment lever rides on site mechanism, a portion of the adjustment lever which faces the site of the shoe expanding mechanism The shoe clearance automatic adjusting device for a drum brake is characterized by being formed.

[0011]

Embodiment 1 of the present invention will be described below with reference to the drawings.

<A> Presumed drum brake FIG. 1 shows a leading trailing type (LT type) equipped with an automatic shoe clearance adjusting device and a parking brake device.
An example of a drum brake is shown. The back plate 1 fixed to the immovable part with a bolt has a pair of brake shoes 2,
3 is slidably arranged by shoe hold devices 4 and 5.

The brake shoes 2 and 3 are webs 2a and 3a.
The rims 2b and 3b are joined to each other, and the linings 2c and 3c are fixed to the outer peripheral surfaces of the rims 2b and 3b. The brake shoes 2 and 3 have pistons 6 of a wheel cylinder 6 whose one end (upper end in the figure) is fixed to a back plate 1.
a and 6a are engaged with each other, and the other ends thereof (lower ends in the figure) are supported by anchors 7 fixed to the back plate 1.

Webs 2a, 3 of both brake shoes 2, 3
An upper shoe return spring 18 and a lower shoe return spring 19 are stretched between a and a, respectively.

The base end of the brake lever 8 arranged parallel to the web 3a of the other brake shoe 3 (on the left side of the drawing) is rotatably supported by a pin 10 and is locked at the free end of the brake lever 8. The rotation of the brake lever 8 is remotely controlled by the pulling operation of the brake cable 9 guided inside the plate 1.

The drum brake is further provided with a strut 11 with a screw coupling mechanism, an adjusting lever 15, and an adjusting spring 17, and these members constitute an automatic shoe clearance adjusting device.

<B> Strut In FIG. 1, the strut 11 which is laterally mounted between the brake shoe 2 and the brake lever 8 on one side (right side in the drawing) is composed of a bolt member 12, a nut member 13 and a socket member 14.

Each part will be described with reference to FIGS.
The bolt member 12 is provided with adjusting teeth 12a having a large number of fine teeth formed on its peripheral surface. The right shaft portion is rotatably fitted into the socket member 14, and the left male screw portion is the nut member 13 It is screwed to. A notch formed on the left side of the nut member 13 having a female thread formed on the inner circumference is engaged with the brake lever 8. A notch 14a formed on the right side of the socket member 14 fitted with the bolt member 12 is engaged with the web 2a of one brake shoe 2.

<C> Adjusting lever The adjusting lever 15 has a dented hole 15a, and is rotatably supported by a pin 16 planted in the web 2a of one brake shoe 2 through the hole 15a. ing.

The adjust lever 15 has a first arm 15b to a third arm 15d. The middle portion of the first arm 15b is bent toward the back plate 1 in a crank shape, and the feed claw portion 15e at the tip thereof is engaged with the adjusting tooth 12a of the strut 11. The second arm 15c is the first arm 15b
Is formed in a substantially right-angled direction, and abuts on the stepped surface 14b of the notch 14a of the socket member 14 that constitutes the strut 11. The third arm 15d is formed to extend in the direction opposite to the first arm 15b. An adjusting spring 17 is stretched between the third arm 15d and one of the brake shoes 2, and the spring force of the adjusting spring 17 constantly causes the feeding claw portion 15e to strut 11.
Of the adjusting tooth 12a. The above is the same structure as the conventional one.

[0021] The present embodiment, the tip vicinity of the first arm 15b of the adjustment lever 15 to form a bent-up rides portion 15f in the counter back plate 1 direction, rigidity of the occupant up portion 15f during manual adjustment The strut 11, which is a member, rides on the strut 11 to disengage the feed claw portion 15e from the adjusting tooth 12a.

The formation position and the length of the riding portion 15f are not limited to those shown in the drawings, as long as they do not interfere with the operation during automatic shoe clearance adjustment and function as described above during manual adjustment. Good.

[0023]

<A> Operation of automatic adjustment of shoe clearance In FIG. 1, when the wheel cylinder 6 is pressurized by the service brake, the brake shoes 2 and 3 expand until they come into contact with a brake drum (not shown). At this time, the adjusting lever 15 rotates counterclockwise by the spring force of the adjusting spring 17, causing the strut 11 to follow the brake shoe 3 and the brake lever 8.

When the linings 2c and 3c of the brake shoes 2 and 3 are worn and the expansion amounts of both brake shoes 2 and 3 are increased, the rotation amount of the first arm 15b of the adjusting lever 15 is the tooth of the adjusting tooth 12a. The bolt member 12 is rotated beyond the intermediate pitch. As a result, the bolt member 12 is screwed out from the nut member 13, the entire length of the strut 11 is extended by one tooth, and the gap between the linings 2c and 3c and the brake drum is automatically adjusted.

<B> Operation for manual adjustment of shoe clearance Due to the necessity of replacement and inspection / repair of the brake shoes 2 and 3,
When it is desired to reduce the outer diameter of the brake shoes 2 and 3 to remove the brake drum, the plug member 21 of the back plate 1 shown in FIG. 4 is removed and the tool 20 such as a screwdriver inserted through the window hole 1a shown in FIG. Is pressed against the tooth of the adjusting tooth 12a, and the adjusting tooth 12a is reversely rotated in the arrow direction.

Then, the feed claw portion 15e of the adjusting lever 15 which engages with the adjusting tooth 12a retracts toward the wheel cylinder 6, and the riding portion 1 integrated with the first arm 15b.
5f rides on the peripheral surface of the socket member 14 of the strut 11. At this time, the riding portion 15f is attached to the socket member 14
Since the feed claw portion 15e of the first arm 15b tilts toward the back plate 1 as a result of the movement along the peripheral surface while being supported by, the feed claw portion 15e is disengaged from the adjustment tooth 12a and both Since the engagement is released, the work can be performed reliably and easily.

By repeating this operation, the entire length of the strut 11 is contracted and a predetermined work is performed. As a result, disassembly work can be performed quickly and accurately when the gap between the brake drum and the brake shoes 2 and 3 is too close, or when the brake drum is worn stepwise.

[0028]

Embodiment 2 of the Invention FIGS. 6 and 7 show an adjusting lever 1
Rigid member is a subject riding the 5 showing another embodiment, which is one of the web 2a of the brake shoe 2. The adjust lever 15 is formed by integrally bending a part of a first arm 15b thereof toward the back plate 1 and obliquely bending the first arm 15b.

In this embodiment, when the adjusting tooth 12a is forcibly rotated in the reverse direction from the outside for manual adjustment, the riding portion 15g abuts on the inner edge of the web 2a so that the entire first arm 15b is indicated by a chain line. Since it is pushed toward the back plate 1, the feed claw portion 15e at the tip of the first arm 15b can be removed from the adjusting tooth 12a.

[0030]

[Third Embodiment of the Invention Figures 8-10 show another embodiment of a wheel cylinder 6 is rigid member constituting the shoe extension mechanism.

In this embodiment, a wheel-cylinder 6 is equipped with various known shoe clearance automatic adjusting mechanisms such as a touring type (2L type) or a dual touring type (D2L type).
The present invention can be applied to a drum brake of No. 1, but here, the case of application to a touring type drum brake is shown, in which the slopes provided on the cylinder body 6b and the adjusting lever 15 are arranged so as to face each other, and when adjusting manually, The slope of the lever 15 rides on the slope of the cylinder body 6b.

The illustrated single-ended open wheel cylinder 6
Includes a piston 6c having a bottomed hole structure for expanding one end of one brake shoe 2, and rotatably accommodates the adjusting nut 22 integrated with the adjusting tooth 22a in the piston 6c. The adjusting nut 22 is one of the brake shoes 2
The adjusting bolt 23, which is in non-rotatable abutting engagement with the adjusting bolt 23, is screwed, and the adjusting bolt 23 is screwed out by the rotation of the adjusting nut 22.

The adjusting lever 15 is rotatably supported by the wheel cylinder 6 by a pin 24, and has a first arm 15b that abuts against the adjusting teeth 22a and a third arm 15 to which the pin 25 is fixed.
and d. One end of the connecting plate 26 having a substantially L shape is integrally fixed to the piston 6c, and the other end abuts the pin 25 of the adjusting lever 15. The adjusting spring 17 includes an adjusting lever 15 and a connecting plate 26.
The connection plate 26 and the pin 25 are kept in contact with each other.

In this example, as shown in FIGS. 8 and 10, the slope 6 is formed on a part of the cylinder body 6b facing the adjusting lever 15.
The first arm 1 of the adjusting lever 15 is formed while forming d.
5b is formed with a riding portion 15f facing the sloped surface 6d, and when manual adjustment is performed by rotating the adjusting teeth 22a in the reverse direction,
As the adjusting lever 15 in FIG. 8 rotates clockwise around the pin 24 as a fulcrum, the adjusting lever 15
The riding portion 15f rides on the slope 6d of the cylinder body 6b, and the feed claw portion 15e is disengaged from the adjusting tooth 22a.

Further, depending on the disposition position of the adjusting lever 15 and the outer shape of the cylinder body 6b, one of the riding portion 15f of the adjusting lever 15 or the sloped surface 6d of the cylinder body 6b may be replaced with a protrusion. In short, the adjustment tooth 22
It suffices that the feed claw portion 15e of the adjusting lever 15 is lifted up from the adjustment tooth 22a and the engagement between the two can be released when a is reversely rotated.

Since the automatic shoe clearance adjusting operation of this type is well known (eg, Japanese Utility Model Publication No. 50-7424), its explanation is omitted.

[0037]

Fourth Embodiment In addition to being applicable to the drum brakes of the first to third embodiments described above, the present invention can be applied to, for example, a drum brake dedicated to a service brake or a parking brake instead of the first embodiment. Applicable or various duo servo type (DS type) drum brakes with automatic shoe clearance adjustment device (for example, Japanese Utility Model 2-172)
It is obvious that the invention can also be applied to Japanese Patent No. 25, etc.).

[0038]

The present invention has the following unique effects. <B> is rigid member a riding target of the adjustment lever, a cylinder body of the strut or the brake shoe or wheel cylinder (shoe expanding mechanism). These stiffness member Ajasutore by wear of the lining
Not located relationship fluctuations in the bar, yet in which can be precisely manufactured. It kept small the gap variation between the riding portion and the rigid member of the adjustment lever is an important element for the particular present mechanism. Therefore, outside the brake shoes
The reliability of releasing the engagement between the adjusting lever and the adjusting tooth at the time of manual adjustment for reducing the diameter increases, and the releasing performance can be guaranteed for a long period of time. <B> During manual adjustment performed by rotating the adjusting teeth in the reverse direction to reduce the outer diameter of the brake shoe, the adjusting spring force acts on the engaging portion between the adjusting lever and the adjusting teeth. Thus although not to release the engagement of the adjustment lever to overcome the frictional forces that occur, since the riding portion is rigid member, reliability capable of engagement adjustment lever and the adjustment teeth is much Become higher. <C> Since the adjust lever does not interfere with the components such as the shoe return spring, there is no fear of causing wrong assembly or deformation of the adjust lever when attaching or detaching the adjust lever.

[Brief description of drawings]

FIG. 1 is a front view of a drum brake according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is an exploded view of the automatic shoe clearance adjusting device.

4 is a sectional view taken along line IV-IV in FIG.

FIG. 5 is an explanatory diagram of manual adjustment

FIG. 6 is a front view of a main part of an automatic shoe clearance adjusting device according to a second embodiment.

7 is a sectional view taken along line VII-VII of FIG.

FIG. 8 is a front view of a main part of an automatic shoe clearance adjusting device according to a third embodiment.

9 is a sectional view taken along line IX-IX in FIG.

10 is a sectional view taken along line XX of FIG.

[Explanation of symbols]

1 back plate 2 One brake shoe 3 The other brake shoe 4,5 Shoe hold device 6 wheel cylinder (shoe expansion mechanism) 6a, 6a, 6c piston 6b cylinder body 6d slope 7 anchor 8 brake lever 9 Brake cable 10 pin 11 struts (screw coupling mechanism) 12 bolt members 12a Adjusting tooth 13 Nut member 14 Socket member 14a notch 14b Stepped surface 15 Adjust lever 15a hole 15b to 15d First arm to third arm 15e Feeding claw part 15f, 15g riding section 16 pin 17 Adjust spring 18 Upper shoe return spring 19 Lower shoe return spring 20 tools 21 plug material 22 Adjustment nut 22a Adjusting tooth 23 Adjustment bolt 24, 25 pin 26 Connecting plate

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-3-239827 (JP, A) JP-A-3-92627 (JP, A) Actual development 60-59836 (JP, U) Actual development 59- 136044 (JP, U) Actual development Sho 59-136045 (JP, U) Actual public Sho 63-40667 (JP, Y1) (58) Fields investigated (Int.Cl. ⁷ , DB name) F16D 65/56

Claims (4)

(57) [Claims] 1. An adjust lever having an expandable and contractible screw coupling mechanism for restricting an outer diameter of the brake shoe, wherein an adjust lever responding to an excessive expansion of the brake shoe rotates an adjusting tooth of the screw coupling mechanism to rotate the drum and the brake. In the shoe gap automatic adjustment device for the drum brake that automatically corrects the shoe gap, the direction of rotation of the adjustment teeth during the automatic shoe gap adjustment
When you want to rotate. The adjustment teeth manually in the reverse direction, riding on site rigid member of the adjusting lever, characterized in that the engagement between the adjustment teeth of said adjustment lever is released, the drum brake shoes Automatic gap adjustment device. 2. A strut with an expandable / contractible screw coupling mechanism arranged between a pair of brake shoes to adjust the gap between the brake shoe and the drum, and the strut of the strut in response to an excessive expansion of the brake shoes. In a shoe brake automatic adjusting device for a drum brake equipped with an adjusting lever for automatically rotating the adjusting teeth and an adjusting spring for applying an urging force to the adjusting lever in a direction for rotating the adjusting teeth, the above-described automatic adjustment of the shoe clearance is performed. Adjusting tooth rotation direction
Time you want to rotate. The adjustment teeth manually in the reverse direction, the raised portion ride rides on the peripheral surface of the strut to release the engagement between the adjustment teeth of the adjustment lever, the adjusting lever facing the circumferential surface of the strut one An automatic shoe clearance adjustment device for drum brakes, which is characterized in that it is formed in the section. 3. A strut with an expandable and retractable screw coupling mechanism arranged between a pair of brake shoes to adjust the gap between the brake shoe and the drum, and the strut of the strut in response to excessive expansion of both brake shoes. In a shoe brake automatic adjusting device for a drum brake equipped with an adjusting lever for automatically rotating the adjusting teeth and an adjusting spring for applying an urging force to the adjusting lever in a direction for rotating the adjusting teeth, the above-described automatic adjustment of the shoe clearance is performed. Adjusting tooth rotation direction
Time you want to rotate. The adjustment teeth manually in the reverse direction, one of the adjustment lever a raising portion ride rides on the site of the brake shoe to release the engagement with the adjustment teeth of the adjustment lever, to face the site of the brake shoe An automatic shoe clearance adjustment device for drum brakes, which is characterized in that it is formed in the section. 4. An expandable and retractable screw coupling mechanism for adjusting the clearance between the brake shoe and the drum, which is built in each shoe expanding mechanism arranged between both adjacent ends of the opposing brake shoes, and each brake shoe. Automatic shoe clearance of a drum brake equipped with an adjust lever that responds to excessive expansion and that rotates the adjusting teeth of each screw coupling mechanism, and an adjusting spring that applies an urging force to the adjusting lever in the direction that rotates the adjusting teeth. In the adjusting device, the direction of rotation of the adjusting teeth during automatic shoe clearance adjustment
When you want to rotate. The adjustment teeth manually in the reverse direction, the raised portion multiplication to release the engagement between the adjustment teeth of the shoe expanding adjustment lever rides on site mechanism, site and facing the shoe expanding mechanism The automatic shoe clearance adjustment device for drum brakes is characterized by being formed on a part of the adjusting lever.