JPS59126127A - Automatic regulator for shoe gap of drum brake - Google Patents

Abstract

PURPOSE:To prevent an opening amount from attaining the value of overregulation which results in elastic deformation of a drum and a shoe, by a method wherein, when the liquid pressure in a wheel cylinder exceeds the energizing force caused by a compression spring and a regulating spring through frictional engagement of a lining with a drum, automatic regulation is rendered ineffective. CONSTITUTION:When the opening amount of shoes 2 and 3 exceeds a given amount, a drive teeth 16b turns a regulating nut 14 counterclockwise to draw a screw rod 13 out of a tube member 15, and a gap between a drum and linings 2c and 3c is decreased by increasing the effective length of a strut 12. Thereafter, when the linings 2c and 3c are brought into frictional engagement with a drum and the liquid pressure in a cylinder 6 is so increased to a value exceeding the energizing force caused by springs 18 and 11a, a lever 9 turns a lever 16 clockwise through the strut 12 to bring control operation into a stop. This causes stabilizing of a gap between the drum and the lining and improves control feeling of a brake.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a drum brake incorporating an automatic shoe gap adjustment device, which prevents excessive adjustment of the gap between the drum and the shoe.

A shoe expansion device is installed between one opposite end of a pair of shoes movably mounted on a back plate, and an extendable stock adjacent to the expansion device restricts the return of the shoe. 2 when applying the brake with the expansion device.
If the amount of expansion of the shoe is excessive due to the wear of the inning, an automatic adjustment device that senses the amount of expansion of the
Various automatic shoe gap adjustment devices have been provided which extend the substantial effective length of the struts and thereby maintain a substantially constant gap between the drum and the shoes.

However, this type of conventional adjustment device has the drawback of inducing over-adjustment because it continues to adjust by sensing the amount of expansion of the shoe, including single elastic deformation of the drum, shoe, etc. However, if the gap between the drum and the cylinder is set large in order to prevent the above-mentioned over-adjustment, the stroke of the brake pedal and drain drain becomes large, resulting in a negative feeling of operation.

The present invention has been made to solve the above-mentioned drawbacks, and embodiments thereof will be described in detail below with reference to the drawings.

FIG. 1 shows a first embodiment of the present invention, which shows a drum shaft equipped with an incremental automatic adjustment device.

This is applied to a rake. In the figure, 1 is a back plate fixed to the stationary part of the main body, and 2.8 is a pair of opposing shoes, each of which is formed into a T-shaped cross section by rims 21L, 32L and webs 2b, Bb. 22L, 3a
Linings 2c and 3C are adhered to the outer periphery of. The shoe 2.8 has one side of the rim 9a, 8a attached to the holding device 4.
5 is slidably mounted on the top plate 1. webzb.

A wheel cylinder 6, which is a shoe expansion device, is installed between the upper opposing ends of the wheels 8b and is fixed to the back plate 1. The expansion device 6 has opposing actuators t5a and Q.
b is slidably fitted, and by the action of a compression spring 6c etc. interposed between the actuators 6a and 6b, one actuator 6a is attached to a lever 9, which will be described later, and the other actuator 6b is attached to a web 8b. It is lightly pressed. Therefore, a desired gap X' is provided between the web 2b of one shear 2 and the actuator 6a. The lower opposite end of the shoe 2.8 abuts an anchor block 7 fixed to the back plate 1 with rivets 8a, 8b. Reference numeral 9 denotes a lever whose middle part is rotatably supported by the shoe 2 with a pin IO, and whose upper end is in contact with the actuator 6a described above, and whose lower end is connected to a remote transmission device such as a wire 11. has been done. This wire 11 is a so-called parking brake device for a vehicle, and a compression spring lla wound around the wire 11 is usually interposed between the lever 9 and the fixed member, and the lever 9 is attached counterclockwise in the figure. It is strong.

A strut 1.2 having a function of adjusting the gap between the drum (not shown) and the linings 2c and '8c is passed between the lower part of the shaft support of the lever 9 and the shoe 8, and the lever is suspended from the strut 1.2. A protrusion 9a formed on the back edge of the shoe 9 comes into contact with the inner surface of the rim Za, thereby determining the outer diameter of the shoe 2°3 at all times. The strut 12 is composed of a threaded rod 18, an adjustment nut 14, and a tube member 1'5, and the right side of the threaded rod 1B is crushed into a fork shape.
8a is engaged with the lever 9 in a crosswise manner, and
The end portion fits into the notch 2d of the web 2b to restrict movement in the vertical direction in the figure. Further, a male thread is carved on the left side, and an adjustment nut 14 having fine teeth on the outer periphery is screwed into the middle part of the vaginal screw shaft part 18b, and the screw shaft part 18 protrudes.
b is loosely fitted into the hollow part on the right side of the paulownia tube part 15. The left side of the tube member 15 is crushed into a fork shape, and this fork-shaped portion 15a engages with the notch 8d of the shoe 8 so as to intersect with it, and the right open end surface is the left end of the adjustment nut 14. It is in contact with the surface. 16 is a pin 1 near the upper end of the shoe 8.
An adjustment lever rotatably supported by pin 17.
It is loosely fitted with a desired clearance in the axial and radial directions. One arm 16a of the adjustment lever 16 extends toward the 8-shaped nut 14, and drive teeth 16b at the tip bent at a substantially right angle engage fine teeth on the outer periphery of the adjustment nut 14. The other arm 16a of the adjustment lever 16 extends outward from the fork-shaped portion 15a of the tube member 15, and its inner edge 16 (1) is in contact with the outer end surface of the fork-shaped portion 151L. , a bent portion 16θ facing toward the back plate 1 is formed on the outer edge of the other arm 16c;
The adjustment spring 18 stretched between the bent portion 16e and the web 3b constantly contacts the strut 12 with the lever 9, and the pivot tooth 16b of the adjustment lever 16 is connected to the adjustment nut 1.
Is it eccentric force that should be engaged with fine teeth? giving.

Reference numerals 19a and 19b are shoe return springs that urge both shoes 2 and 8 toward each other, and when the brake is released, they are separated from the rolling gc and 9oi drums.

Next, the operation of the automatic shoe gap adjustment device having the above-described configuration will be explained.

When the brake pedal is depressed, pressure fluid is supplied to the wheel cylinder 6. Until the linings 2C and 3c come into contact with the drum (not shown), the shoe return spring 19z,
While the first child 6N pushes the upper end of the lever 9 to the right against the force 19b, the actuator 6b pushes the upper end of the shoe 8 to the left 1. At this time, the lower part of the lever 9 has a compression spring 1. ]2
Since the biasing force of L and the adjustment spring 8 acts on the shoe 1 in the counterclockwise direction, the shoe 2 opens together with the lever 9. Furthermore, the strut 12 follows the movement of the shoe 2 and the lever 9 due to the action of the adjustment spring 18, and the adjustment lever 16 rotates counterclockwise with the pin 17 as a fulcrum.
Now, linings 2c and 3c are worn out and shoe 2.8
If the amount of expansion is larger than the predetermined amount, adjust lever 1
The drive tooth 16t) of No. 6 rotates the adjusting wheel 1-14' to pull out the threaded rod 18 from the tube member 154, and the strut 1
Drum and lining zc by increasing the effective effective length of z
, close the gap with 3c. Next, linings 2c, 8
When the hydraulic pressure of the wheel cylinder 6 reaches such a level that it frictionally engages with the drum and overcomes the biasing force of the adjustment spring 18, the adjustment lever 16 rotates in the opposite direction and the automatic adjustment becomes inactive. That is, since the lever 9 is rotated clockwise about the bin 10, the adjustment lever 16 is also rotated clockwise via the strut 1z2. Therefore, the elastic deformation of the drum, shoe 2.8, etc. due to the subsequent rise in hydraulic pressure is not absorbed, and the drum and lining 2c due to the hydraulic pressure.

Fluctuations in the gap with 8c can be reduced.

If the gap X between the web 2b and the actuator 6a CD is eliminated almost at the same time as the linings 2c and 8c are brought into contact with the drum, then the conventional drum drive can be used.
The actuator tla is operated in the same way as the ya.

6b pushes the straight shoe 2.8 to brake the rotating drum. Also, the web 2b and the actuator 6! When the gap x with L is set large, the shoe 8 receives an input from the actuator 6b, the actuator 6a, the lever 9 and the strut 1zt-
The input transmitted through the shoe 2 is applied to the actuator 6m.
The input is transmitted via the bottle 10 using the point of contact between one end of the strut 12 and the lever 9 as a fulcrum.

As is clear from the above explanation, the actuator 6a is the lever 9.
If the clearance xl is set so that the wheel cylinder 6 is always pushed, the force acting on the shoe 2.8 will increase.
The effective diameter of the can be reduced.

The above is the operation of the foot brake, but next we will explain the entire operation of the hand brake. That is, when you pull the wire 11,
The lever 9 rotates clockwise in the figure as a fulcrum for the bin 10i, presses the lining 80 of the shoe 8 against the drum via the strut 12i, and the lever 9
Since it rotates as a contact point with -12, it comes into pressure contact with the lining 2ct-drum of the shoe 2 via the bottle 10, thereby maintaining the original image etc. in a stationary state. At this time, adjustment lever 1
Since the relative engagement position between the drive teeth 16b of No. 6 and the fine teeth of the adjustment nut 14 is almost unchanged, the strut 1z
No adjustment is made by elongation.

FIG. 2 shows a second embodiment of the present invention, in which the shoe return spring 1
This is a modification of FIG. 1 in which rotational force is applied to the adjustment lever 16 using 9a'i. Therefore, the structure of only this part will be explained. One arm 1 of an adjustment lever 16 rotatably supported by a pin 17 on the web 8b of the shoe 8
62L is the adjustment nut 1 that straddles the shoe return spring 19af.
4, the old bent drive tooth 1
6b engages with the fine teeth on the outer periphery of the adjusting nut (14). The other arm 16c of the adjustment lever 16 extends toward the fork-shaped portion 15a of the tube member 15, and a portion substantially parallel to the upper surface of the web 3b is fitted into the groove of the fork-shaped portion 15m, and a portion on the outer edge thereof is fitted into the groove of the fork-shaped portion 15m. The inner surface of the formed substantially right-angled bent portion 16e is in contact with the outer end of the fork-shaped portion 15a. Also, the shoe return spring 19a has one hook connected to the shaft support of the adjustment lever 16 and the seven-octet shaped portion 152 of the other arm 16o.
The other hook is hooked to one shoe 2 and urges the shoes 2 and 8t toward each other, and the adjustment lever 16 is rotated counterclockwise at -. It is biased in the direction. The brake operation and the automatic shoe gap adjustment operation with this configuration are substantially the same as those in the first embodiment described above, and therefore, the explanation thereof will be omitted.

8 and 4 show a third embodiment of the present invention, which is applied to a one-shot automatic adjustment device. 10 in the diagram
1 is the back plate, IOJ 103 is the rim 1.02
2L, 108a and the web 102b, 1 (a pair of sheets consisting of Hlb and lining 102c', 108a, 104.105 is the holding device of the shoe 102.108)] 06 Between the lower ends of the web 102, 1Of3 The wheel cylinder installed in 1062L
, 106 b Hashi (0 actuator. 107 is Shi'
--The anchor block 1o9 installed between the lower ends of 102 and 108 is a lever whose middle part is rotatably supported by one shoe 102 with a bin 110, and whose upper end is rotatably supported by the actuator 106a. wire 111 at the lower end.
is connected. In addition, a plate-shaped strut 112 with an automatic shoe clearance adjustment function is installed between the lower portion of the shaft support of the lever 109 in FIG. Actuator 1
06a, a gap xl is provided between the two.

One end of the strut 112 is formed into a fork shape, and its notch 112a engages with the notch 109b of the lever 109 so as to intersect with it, and the end of the fork-shaped portion is configured to sandwich the web 102b and the lever 109. installed. In addition, the other end of the strut 11z is bent to a height approximately equivalent to the plate thickness, and the middle part of the bell crank lever 116 is rotatable in the elongated hole fitted in this part, and the lengthwise direction of the strut 112 is bent. It is pivotally supported by a bin 117 so as to be movable. Fine teeth 112b are carved into the arc-shaped end surface of the intermediate portion, which is on the same plane as one end of the strut 112. One arm 116a of the bell crank lever 116 is loosely fitted into the web 108b 17) opening 108e with a gap Y, and fine teeth 116b carved on the arcuate outer end surface of the other arm 116c are inserted into the strut 11?
It meshes with the fine teeth 11Zb of No.2.

120 is a spring stretched between the strut 112 and the shoe 102, 121 is a spring stretched between the strut 112 and the bottle 117, and the mounting load of the springs 120 and 121 is set to be larger for the spring 120. be.

Reference numerals 119a and 119b are shoe return springs, and when the play motion is activated, the bottom of the notch 112a of the strut 112 and the bottom of the notch 109b of the lever 09 come into contact with each other.
The opening 108e of '108b is the bell crank lever 116
is in contact with the outer end surface of one arm 116a of the lever 10.
A protrusion 109c formed by cutting and shearing 9 acts so as to come into contact with the inner edge of the web 1o2b, thereby limiting the return position of both shoes 102.10i8.

Next, the operation of the automatic shoe gap adjustment device having the above-described configuration will be explained. That is, pressure fluid is supplied to the wheel cylinder 106, and the lining 102c,
When the actuator 106a contacts the lever 108c, the actuator 106a
When you press 09, the biasing force of the compression spring 111 & attached to the spring 120 and the wire 111 is applied. expands to the right together with the lever 109. Also sea = i-1
oa expands to the left by actuator 1.06b. At this time, if the gap between the drum and the linings 102c, 103c is larger than a predetermined amount, the strut 112 will be forced into the spring 120.
The movement of the x9 lever lO9 and the shoe 102 is followed by the action of
As the twelve teeth 112b disengage, the bellcrank lever 116 rotates clockwise in FIG. 4 to increase the effective effective length of the strut 112 and thus the drum and lining 102a.

Close the gap of 108C.

Next, the linings 10Zc and 108a frictionally engage the drum, and the hydraulic pressure in the wheel cylinder 106 is reduced by the spring 120.
When it reaches the point where it can overcome the urging force of 1lla, lever 10
9 pushes in the direction of strut 112>shoe 8, so the adjustment stops. Since the subsequent operations are the same as those in the first embodiment described above, the explanation will be omitted.

5 to 7 show a fourth embodiment of the present invention, which is applied to a one-shot automatic gap adjustment device of a different type from the eighth embodiment.

In the figure, 201 is the back plate, 202.208 is the rim 2
02a, a pair of shoes consisting of ZO8a, webs 202b, 208b and linings ZO2c, ZO8c;
204 and 205 are holding devices for the shoes 202 and 208, 206 is a wheel cylinder, and 206 & ZO6b are actuators thereof, each of which has a groove formed at its outer end, into which the web 202b and ZO13b are fitted. There is. 2
07 is an anchor block, 209 is a lever whose middle part is rotatably supported by one shoe 202 with a pin 210, and whose upper end is an actuator 206a as shown in FIG.
A wire (not shown) is connected to the lower end, and a protrusion 209a provided near the lower end is normally in contact with the inner surface of the rim 202a. Reference numeral 212 denotes a plate-shaped strut, as shown in FIG.
02b and lever 209 are mounted in between. A fork-shaped portion is also formed on the left side of the strut 212, and a notch z120 of the fork-shaped portion is secured to intersect with a notch 216f of an adjustment lever 216, which will be described later, and the web 208b and adjustment lever 216'i.
It is attached in a pinching style.

A plate-shaped adjustment lever 216 is rotatably supported by a pin 217 near the upper end of the web 20Bb, and is attached to an arc-shaped end surface of the end portion 216B extending downward in FIG. is carved with fine teeth 216b.

In addition, there is a substantially square hole 216C in the middle part of the adjustment lever 216.
As shown in FIG. 6, a protruding hook portion 212 (i) formed in the notch 212c of the strut 212 is loosely fitted into this hole 216c, and the hook portion 2
A predetermined gap Y is set between the right end surface of the hole 216c and the right end surface of the hole 216c.
It is a pawl member rotatably supported by a pin 228, and fine teeth Z22b carved on the outer surface of the other end mesh with the fine teeth 216b of the adjustment lever 216, and the adjustment lever 21
The clockwise rotation in FIG. 6 of FIG. 6 is inhibited.

The claw member 222 is a torsion spring 22 wound around a pin 228.
4, c6. In FIG. 5, it is always biased counterclockwise. The torsion spring 224 has its coil portion' connected to the pin 228.
One arm 21a contacts the inner surface of the T-rim 208a, and the other arm 224b is bent and hooked to the outer edge of the claw member 222, thereby applying rotational force to the claw member 22g. ing. 220 is a spring stretched between the shoe 2θ2 and the strut 212, 219a, Z], 9
b is a shoe return spring, and when the prekine is activated, the bottom of one notch Z12a of the strut 212 and the bottom of the notch 209b of the lever 209 come into contact, and the bottom of the other notch 212c of the strut 212 and the bottom of the notch 212c of the key IL'/<-216. The bottom of the notch 216r contacts and the protrusion 209 of the lever 209
a acts so as to come into contact with the inner surface of the rim ZOZ&, thereby limiting the return position of both shoes 202, 203. Also, in this case, a gap X is provided between one shoe 202 (1) web 202b and the actuator 206a, as in the embodiment described above.

Next, the operation of the automatic shoe gap adjustment device having the above-described configuration will be explained. That is, pressure fluid is supplied to the wheel cylinder 206 and the lining 202c,
Until the lever 208c comes into contact with the actuator 206a, the shoe 20
2 and the strut 212 are integrated with the lever 209 and expand to the right. Further, the shoe 208 is expanded to the left by the actuator 206b, integrally with the adjustment lever 216, the pawl member 222, and the like. At that time, the drum and lining 202c
, If the gap with the ZO8c is larger than a predetermined value, the right end surface of the hook portion 212d of the stock 121s will touch the adjustment lever 216.
It comes into contact with the right end surface of the hole 216c and absorbs the gap Yi,
Furthermore, since the adjustment lever 216 is rotated counterclockwise in FIG. 5 against the torsion spring 224, the claw member Zf
The tooth 222b of l is the next new tooth 2 of the adjustment lever 216.
16b, thereby extending the substantial effective length of the strut 2]1 and connecting the drum and lining 2020, 20QO.
close the gap between

The linings 202c, 208c then frictionally engage the drum to reduce the hydraulic pressure in the wheel cylinder 206 to the spring gzo.
When the biasing force is overcome, the lever 209 pushes the strut 212 back toward the shoe 208, and the adjustment is stopped. Since the subsequent operations are the same as those in the first embodiment described above, the explanation will be omitted.

Lever 9 shown in the first to fourth embodiments of the present invention as described above. 109.209 are all hand lever operation force when parking 11 brake 't shoe 2.8.102°108.
This is used in conjunction with the l/bar inside the brake that transmits information to 202.208 via wires 11 and 111, but the 8th
A fifth embodiment according to the invention shown in the figure is an independent lever 80.
9. That is, this embodiment is a modification of the first embodiment shown in No. 11, and its brake structure is almost the same. Therefore, the 7-hook portion 18a of the threaded rod 18
is engaged with the notch 2d of the shoe 2 so as to intersect therewith, and the groove bottoms of both are in contact with each other. Also, the upper end of the lever 809, which is pivotally supported on the web 2b with a pin 10, comes into contact with the actuator 6a,
The upper end is pushed by the residual pressure of the compression spring 6C and the master cylinder (not shown), and the lower end of the lever 809 lightly contacts the right side surface of the fork portion 18a of the threaded rod 18. In this state, a gap X is provided between the actuator 6a and the web 2b.

The structure, brake operation, etc. other than those described above are the same as those of the first embodiment described above, so explanations thereof will be omitted. It is clear that the fifth embodiment can also be applied to the second to fourth embodiments.

As is clear from the above description, according to the present invention, elastic deformation of the drum, shoes, etc. is not absorbed when automatically adjusting the shoe gap, so there is no risk of over-adjustment, and the adjustment is instantaneous when the output of the actuator reaches a predetermined value. The detection is extremely sensitive. Therefore, the gap between the drum and the lining becomes stable, and the setting of the gap can be made smaller, which improves the feeling of operating the stroke of the pedal or hand lever, and also improves safety because the brake starts to work sooner. . In addition, levers 9,109, and 209t with built-in brakes for parking brakes have excellent effects such as simple structure and low cost.

[Brief explanation of drawings]

Fig. 1 is a front view of a drum brake showing the first embodiment of the present invention, Fig. 2 is a front view of the main parts of the drum brake showing the @2 embodiment, and Fig. 8 is a drum brake showing the third embodiment. 4th south is an I-I sectional view of the 3rd exit, 5th is a front view of the drum brake showing the 4th embodiment, 6th is a nn sectional view of FIG. 5, 7th The figure is a cross-sectional view of I[[-I[1] of the 5th south.
It is a front view of the principal part of the drum brake which shows an Example. 101.201... Back plate 2, 8.102.108. %,%% 202. ZO
13-... Shoe 6, 106. z06...Wheel cylinder 6a, 6b, 106a, IQ6b, 2
Q6a, 206b ・++ work! b child 7, 107.20
7... Anchor block 9, 109.209.809
...Lever 12, 112.212...Strut 1
3...Threaded rod 14...Adjusting nut 15.
... Pipe member 16,216 ... Adjustment lever 1
16...Bell crank lever 222...Claw member. Patent applicant Nisshinbo Co., Ltd.

Claims (1)

[Scope of Claims] L A shoe expanding device t having an actuator is installed between one opposing end of the opposing shoes, and an extendable strut for returning and restricting the shoe is arranged adjacent to the expanding device. and an automatic shoe gap adjustment device that automatically extends the substantial effective length of the strut in response to excessive expansion of the pair of shoes, thereby adjusting the gap between the drum and the shoe, wherein one of the shoes lever on the shoe (9,109,204,
809), and one end of the lever is engaged with the actuator, and the other part of the lever is engaged with one end of the strut, and when braking. An automatic shoe clearance adjustment device for a drum brake, characterized in that the automatic shoe clearance adjustment device stops operating when a strut is pushed toward the other shoe by a biasing force of an actuator against the lever. & The automatic shoe clearance adjustment device for a drum brake according to claim 1, wherein the other of the levers (9, 109, 209) is extended, and a remote transmission device such as a wire is connected to the extended portion.