JPH09166162A - Drum brake device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drum brake device to reduce size and weight through reduction of the number of parts and improve working efficiency. SOLUTION: A drum brake device comprises a brake drum; a single brake shoe 2 movably attached on a back board 1 fixed at a car body; a link 6 pivotally supported at the back board 1; a brake cylinder 9 and a strut member 18 disposed between the link 6 and the brake shoe 2; and an extrapolation member 10 located between the piston 9b of the brake cylinder 9 and the link 6. A brake power generated through frictional engagement of the brake shoe 2, expanded by the brake cylinder 9, with a brake drum is received by a first anchor formed on the direction of the opposite expansion side of the brake shoe 2 when the brake drum is rotated in one way and when the brake drum is rotated in other direction, the brake force is received by a second anchor through the strut member 18.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drum brake device having a single brake shoe.

[0002]

2. Description of the Related Art As a conventional drum brake device having a single brake shoe, for example, Japanese Utility Model Publication No. 4-5122.
There is a drum brake device disclosed in Japanese Patent No. 5 and a parking brake device disclosed in Japanese Utility Model Publication No. 5-14016.

[0003]

The device disclosed in Japanese Utility Model Publication No. 4-51225 of the above-mentioned conventional device is an adjusting member 30 and a strut 36 which are connecting members between the brake shoe and the rotating member. And because it's being passed over,
There is a problem that the number of parts is increased and assembly is complicated. Further, in the conventional device of this type, since the rotating member is rotated and an input is applied to the brake shoe via the connecting member, a large axial thrust force acts on the connecting member. Moreover, since this connecting member also serves as a shoe gap adjusting member that is screwed, the adjusting action may be abnormal due to the thrust force. In addition, the thread portion of the shoe gap adjusting member may be deformed or stuck,
Alternatively, when vibration is applied while the thrust force acts, the screw portion is rotated in the reverse direction and the length of the adjusting member is shortened, so that the shoe gap becomes extremely large.

Since the strut member of the above-mentioned conventional device is on the opposite side of the shoe gap adjusting member (connecting member),
If the screw gap of the shoe gap adjusting member is extended to adjust the shoe gap, the gap between the brake shoe and the brake lever around which the strut member is stretched and the rotating member is widened. As a result, the parking brake becomes less effective and the feeling is deteriorated. In addition, the anchor pin 20 of Jpn. Pat. Appln. No. 5-14016 needs to be strong because it receives the braking force of forward and backward movement, and when it is received by the anchor blocks 40 and 42, two anchor blocks are required. There is a problem that the score increases.

[0005]

In order to solve the above problems, in the present invention, a brake drum rotatable in both directions, a back plate fixed to the vehicle body facing the brake drum, and the back plate. A single brake shoe movably attached to the upper side, a link rotatably supporting the intermediate portion to the back plate so as to face the brake shoe, and between one side of each of the link and the brake shoe. A pair of brake cylinders, which are provided inside and have a pair of pistons housed therein to project to expand between the respective one sides, and strut members installed between the brake shoes and links near the brake cylinders. And an interposing member interposed between one side of the link and the piston of the brake cylinder, and the brake shoe expanded by the brake cylinder. A braking force generated by frictionally engaging with the brake drum is received by a first anchor formed on the other side of the brake shoe when the brake drum rotates in one direction, and when the brake drum rotates in the other direction. The drum brake device is configured so that it is received by the second anchor via the strut member.

Further, in the present invention, the interposing member interposed between the one side of the link of the drum brake device of the first invention and the piston of the brake cylinder is a push rod, and the push rod is opposed to the piston. The surface may be formed into a spherical surface, and a groove that engages with the link may be provided in a portion facing the link.

In the present invention, a roller is rotatably provided at one end of the link as an interposing member interposed between one side of the link of the drum brake device of the first aspect of the invention and the piston of the brake cylinder. The outer peripheral surface of the roller may be projected from the end portion of the link, and the protruding portion may be brought into contact with the outer end surface of the opposed piston.

In the present invention, the interposing member interposed between one side of the link of the drum brake device of the first invention and the piston of the brake cylinder may be a liner made of low friction resin.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 7 show a first embodiment of the present invention, in which reference numeral 1 denotes a back plate fixed to a vehicle body, and a brake fixed to an axle (not shown) facing the inside of the back plate 1. A drum (not shown) is positioned so that it can rotate in both directions. Reference numeral 2 denotes a single brake shoe movably provided with respect to the back plate 1 and facing the inner peripheral surface of the brake drum, 2a denotes a web thereof, 2b denotes a rim, 2c denotes a lining, and a web 2a. The rim 2b has a T-shaped cross section.

The brake shoe 2 has a hole (not shown) formed in the intermediate portion of the web 2a, a shoe hold pin 3 penetrating the back plate 1 penetrates the hole, and a leaf spring is formed on the protrusion thereof. The shoe-hold spring 4 is engaged to elastically hold the brake shoe 2 on the back plate 1 so as to be movable.

A semicircular arc-shaped link 6 is rotatably supported by a support shaft 5 on a back plate 1 on the side opposite to the brake shoe 2, and the lower end of the link 6 in FIG. As shown in FIGS. 5 and 6, the back plate 1 is bent by about 90 degrees, and the lower end edge 2d of the web 2a of the brake shoe 2 is brought into contact with the bent piece 6a.
The protrusion 1a that supports the lower end edge 2d of the web 2a of the brake shoe 2 via the bent piece 6a of the link 6 is formed as a first anchor. The arm 6b projecting from the link 6 in FIGS. 1 and 6 is engaged with the web 2a of the brake shoe 2 to prevent the brake shoe 2 from rising. Reference numeral 7 denotes a shoe return spring that extends over the lower portion of the brake shoe 2 and the link 6 in FIG. In addition, 5a in FIG. 4 is a flange portion of the support shaft 5, 5b is a crimped portion to the back plate 1, and 8 (see FIGS. 1 and 4) is a push nut fitted in the support shaft 5.

Between the upper ends of the brake shoe 2 and the link 6 in FIG. 1, a double-sided open type brake cylinder 9 is fixed to the back plate 1 by mounting bolts (not shown) or the like. 9a and 9b are pistons provided on both sides of the brake cylinder 9, and 9c is a spring interposed between the pistons 9a and 9b. In the embodiment of FIG. 1, the outer end of the piston 9a abuts against the upper end of the brake shoe 2, and the outer end of the piston 9b is recessed into a spherical shape. The push rod 10 is interposed as an interposing member. This push rod 10
As shown in detail in FIG. 2, a surface facing the piston is formed into a spherical surface 10a, a groove 10b engaging with the link 6 is provided at a portion facing the link 6, and an annular groove 1 for boot fitting is provided at an intermediate portion.
0c is provided. In the figure, 11 is a boot made of an elastic material such as rubber. Also, the piston 9a and the web 2 of the brake shoe 2
The push rod 10 may be inserted between the upper ends of a.

The upper end of the brake lever 13 is pivotally supported by the lever pin 12 on the upper end of the link 6. Reference numeral 14 is a U retainer fitted in the lever pin 12. FIG.
Further, as shown in FIG. 3, a plate-shaped quadrant 16 is superposed on the brake shoe 2 side of the plate-shaped strut 15, and the quadrant 1 is connected by the quadrant pin 17.
6 is rotatably connected to a strut 15 to form a strut member 18, and the quadrant 16 has a neck portion 1
6a is a window 2e provided in the web 2a of the brake shoe 2
, And a quadrant spring 19 is bridged between the quadrant pin 17 and the strut 15. 16b
(See FIG. 3) is a stopper portion of the quadrant 16.

As shown in FIG. 3, a step portion 15a and a lateral projection 15b are formed on the link 6 side of the strut 15, and the side edge of the brake lever 13 connected to the link 6 is engaged with the step portion 15a. At the same time, the hole 6c provided in the link 6 (see FIG.
(See) and the lateral projection 15b of the strut 15 are stretched over the anti-rattle spring 20. Strut 15
A step portion 15c (see FIG. 3) is formed on the back plate 1 side, and the protrusion 1b engaging with the step portion 15c is formed on the back plate 1 as a second anchor. Further, as shown in FIGS. 3 and 7, a window hole 15d is provided in the middle portion of the strut 15.
A projecting piece 9e that is inserted through the cylinder 9 is provided so as to project from the cylinder 9.
To prevent the floating of The spring load of the quadrant spring 19 is the anti-rattle spring 20.
Smaller than the spring load of. Further, a shoe return spring 21 is bridged between the brake shoe 2 and the upper portion of the link 6 in FIG. Reference numeral 32 in FIG. 1 is a pull-off spring, which is a hook 1d formed by bending the back plate 1.
And a hole 2g formed in the web 2a of the brake shoe 2. This pull-off spring 3
Reference numeral 2 is for forcibly returning the lower end edge 2d of the brake shoe 2 and the bent piece 6a of the link 6 to abut the first anchor 1a. Note that 9f shown in FIG. 7 is an input port of the cylinder 9, and 9g is an air bleed screw for bleeding air from the cylinder 9.

8 to 15 show another embodiment of the present invention, in which the same reference numerals as those used in the drawings denote the same elements. FIG. 8 shows a modified example of the portion shown in FIG. 5, in which the end portion 2f of the shoe web 2a is bent and directly supported by the first anchor 1a, and the link 6 is flat. is there. 9 is the same as FIG.
This is a modified example of the portion shown in FIG. 3, which is an example in which the present invention is applied to a cross-pull type brake lever. Reference numeral 22 is a cable bracket for fixing an outer (not shown) of a control cable for pulling the brake lever 23 and receiving a reaction force, which is fixed to the back plate 1 by welding, rivets, bolting or the like. The brake lever 23 is pivotally supported by a lever pin 24 at the right end of the strut 15 in the drawing. 25
Is a push nut type retainer, 26 is a rubber boot provided so that the brake lever 23 seals around the opening 1c penetrating the back plate 1, 27 is a lever fixed to the back plate 1 by welding, rivets, bolting, etc. Stopper, 28
Is a lever return spring spanned between the protrusion 27a of the lever stopper 27 and the brake lever 23. The second anchor 1b is formed by projecting the back plate 1 in a stepwise manner. Instead of the projection 1b, a convex portion is formed on a vehicle body side member, or a pin or a bolt is attached to mount the strut 15 on the strut 15. You may make it contact | abut directly. FIG.
As shown in Fig. 3, if the gap between the step portion 15c and the second anchor 1b is L ₁ , and the gap between the window hole 15d and the projecting piece 9e on the left side in Fig. 3 is L ₂ , and if L ₁ > L ₂ , then the cylinder is 9
The projecting piece 9e may be used as the second anchor.

10 and 11 show a modification of the lower part of FIG. 1, in which a long hole 6d is provided in the lower part of the link 6 and an anchor pin 29 loosely fitted in the long hole 6d is attached to the back plate 1.
It is fixed to the first anchor. A flange portion 29a is formed on the anchor pin 29 to prevent the link 6 from rising. 6e is an arm extending from the link 6, and the brake shoe 2 is provided between the arm 6e and the back plate 1.
The web 2a of the above is inserted. Also, θ in FIG.
Is an anchor angle. This anchor angle is an angle at which the brake shoe 2 abuts the vertical line L. Normally, when the anchor angle θ becomes large, the braking effect decreases, and the maximum surface pressure position in the lining circumferential direction is the anchor. The brake cylinder 9 is displaced from the side. It also has the purpose of preventing dragging on the anchor side.

12 and 13 show the brake cylinder 9
This shows a modified example of both outer side parts of the boot.
Is provided, and an engaging groove 9i into which the upper end of the web 2a of the brake shoe 2 can be inserted is provided at the outer end of the left piston 9a, and the link 6 is provided at the outer end of the right piston 9b.
Engaging groove 9 into which the roller pin 30 provided at the upper end of the
j is provided.

The roller pin 30 as an interposing member is shown in FIG.
As shown in detail in FIG. 3, the shaft 30b integral with the roller 30a
Through the hole 6f provided at the upper end of the link 6, and the shaft 30b
The ring-shaped roller 30 is attached to the stepped small-diameter portion 30c from which the
The end portion 30e of the small diameter portion 30c is caulked to be integrated by d and is made rotatable with respect to the link 6. The outer peripheral surfaces of the rollers 30a and 30d of the roller pin 30 are projected from the end surface of the link 6, and the projecting portion is housed in the engaging groove 9j formed at the outer end portion of the piston 9b which faces the link. A bearing may be used instead of the roller pin 30.

14 and 15 show another embodiment of the present invention. In this case, the pistons 9a, 9b are provided.
Low friction containing fluorine, molybdenum disulfide, etc. as an insertion member in an engaging groove 9k provided so that the upper end of the web 2a of the brake shoe 2 or the upper end of the link 6 can be inserted into the outer end of the A liner 31 made of resin is provided. The liner 31 may be provided at least on the right side of the piston 9b. Further, at least one of the bottom of the engaging groove formed on the piston and the end face of the link may be coated with a low friction material. Further, the push rod and the insertion member, or the roller and the insertion member may be combined.

As described above, in the present invention, the brake drum rotatable in both directions, the back plate 1 facing the brake drum and fixed to the vehicle body, and the single movably mounted on the back plate 1. One brake shoe 2, a link 6 facing the brake shoe 2 and having an intermediate portion rotatably supported on the back plate 1, and disposed between one side of each of the link 6 and the brake shoe 2. And a pair of pistons 9a and 9b housed therein are projected so as to expand between the respective one sides of the brake cylinder 9 and between the brake shoe 2 and the link 6 in the vicinity of the brake cylinder 9. Since the strut member 18 is installed and the interposition member 10 (30, 31) interposed between one side of the link 6 and the piston 9b of the brake cylinder 9, the breaker is provided. When the brake drum rotates in the direction of arrow I in FIG. 1, the braking force generated by frictional engagement of the brake shoe 2 expanded by the cylinder with the brake drum causes the back plate 1 of the brake shoe 2 in the other direction. It can be received by the second anchor 1b via the strut member 18 when the brake drum rotates in the direction of arrow J in FIG.

FIG. 16 is an explanatory view of the operation of the conventional apparatus, and the same reference numerals as those used in the previous description denote the same elements. When the hydraulic pressure is introduced into the brake cylinder 9 and the piston 9b is projected in the state of the solid line, the link 6 rotates in the clockwise direction as shown by the arrow K with the support shaft 5 as the fulcrum, and the state of the two-dot chain line is obtained. At this time, the contact point between the piston 9b and the link 6 moves in the X dimension in the axial direction of the piston 9b and in the Y dimension in the direction perpendicular to the axis of the piston 9b. This Y dimension causes mechanical loss because the link 6 moves while sliding with respect to the piston 9b. In the present invention, as described above, since the push rod 10, the roller pin 30, and the liner 31 are inserted between the upper end of the link 6 and the outer end of the piston 9b of the brake cylinder 9, these insert members are used. As a result, the sliding resistance in the direction of the arrow Y can be significantly reduced.

That is, according to the push rod 10, the frictional resistance can be reduced by tilting the push rod 10 between the piston 9b and the link 6. Further, when the roller pin 30 is used, the movement in the arrow Y direction is absorbed by the rolling of the roller, and when the liner 31 is used, the sliding resistance can be reduced due to the low friction performance of the liner 31.

[0023]

Since the device of the present invention is constructed as described above, the following effects can be obtained. (1) Since the interposing member (10, 30, 31) that can reduce the sliding friction resistance therebetween is provided between the upper end of the link 6 and the outer end of the piston 9b of the brake cylinder 9, the machine of the drum brake device is thereby provided. Efficiency can be improved. (2) Further, the device of the present invention does not require an adjusting member which is a connecting member between the brake shoe 2 and the link 6 which is a rotating member. (3) Since the strut member 18, which is the gap adjusting mechanism, is on the expansion side of the brake shoe 2, the brake lever 13
The operating stroke of is constant. Also brake shoe 2
The wear is corrected by the gap adjusting mechanism, so the stroke does not increase. (4) The strut member 18, which is a gap adjusting mechanism, is
Since it is used as a braking force transmission member to the anchor 1b, the number of parts can be reduced. Also, the brake can be easily assembled.

[Brief description of the drawings]

FIG. 1 is a front view showing a partial cross-section of a device of the present invention.

2 (a) is a front view of the push rod of FIG.
(B) is a plan view of (a).

FIG. 3 is a sectional view taken along line AA of FIG. 1;

FIG. 4 is a sectional view taken along line BB of FIG. 1;

FIG. 5 is a sectional view taken along the line CC of FIG. 1;

FIG. 6 is a sectional view taken along line DD of FIG. 1;

FIG. 7 is a sectional view taken along the line EE of FIG. 1;

FIG. 8 is a modification diagram of FIG.

FIG. 9 is a modification view of the portion of FIG.

FIG. 10 is a modification view of the lower portion of FIG.

11 is a cross-sectional view taken along the line FF of FIG.

FIG. 12 is a front view showing another embodiment of the device of the present invention in a partial cross section.

13 is a partial cross-sectional view taken along the line GG of FIG.

14 is a diagram of another embodiment of the upper portion of FIG.

15 is a partial cross-sectional view taken along the line HH of FIG.

FIG. 16 is an explanatory view of the operation of the conventional device.

[Explanation of symbols]

 1 Back Plate 1a 1st Anchor (Projection) 1b 2nd Anchor (Projection) 1c Opening 1d Latching piece 2 Brake shoe 2a Web 2b Rim 2c Lining 2d Lower edge 2e Window hole 2f End 2g Hole 3 Shoe hold pin 4 Shoe hold spring 5 Support shaft 5a Collar part 5b Caulking part 6 Link 6a Bending piece 6b Arm 6c hole 6d Long hole 6e Arm 6f hole 7 Shoe return spring 8 Push nut 9 Brake cylinder with both sides opening 9a, 9b Piston 9c Spring recess 9d Part 9e Projection piece 9f Input port 9g Air bleed screw 9h Annular groove 9i Engaging groove 9j Engaging groove 9k Engaging groove 10 Push rod (interposition member) 10a Spherical 10b Groove 10c Annular groove 11 Boot 12 Lever pin 13 Brake lever 14 U Retainer 15 strap 15a Step 15b Side protrusion 15c Step 15d Window hole 16 Quadrant 16a Neck 16b Stopper 17 Quadrant pin 18 Strut member 19 Quadrant spring 20 Anti-rattle spring 21 Shoe return spring 22 Cable bracket 23 Brake lever 24 Lever pin 25 Retainer Rubber boot 27 Reversing top 27a Projection piece 28 Lever return spring 29 Anchor pin (first anchor) 29a Collar part θ Anchor angle L Vertical line 30 Roller pin (interposition member) 30a Roller 30b Shaft 30c Small diameter part 30d Roller 30e End part 31 Liner (Interposer) 32 Pull-off spring

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Junichi Hasegawa 5-14-25 Toyota, Minami-ku, Nagoya-shi, Aichi Nisshin Spinning Co., Ltd. Nagoya factory

Claims (4)

[Claims] 1. A brake drum rotatable in both directions,
A back plate fixed to the vehicle body facing the brake drum, a single brake shoe movably mounted on the back plate, and an intermediate portion rotatable to the back plate facing the brake shoe. A link that is pivotally supported on each side, and a brake cylinder that is disposed between each one side of the link and the brake shoe, and that has a pair of pistons housed inside and that projects between the one side to expand the pair of pistons. A strut member provided between the brake shoe and the link in the vicinity of the brake cylinder, and an interposing member interposed between one side of the link and the piston of the brake cylinder. The braking force generated by frictional engagement of the opened brake shoe with the brake drum is applied to the other brake shoe when the brake drum rotates in one direction. A drum brake device characterized in that it is received by a first anchor formed in a lateral direction and is received by a second anchor via a strut member when the brake drum rotates in the other direction. 2. A push rod is used as an interposing member interposed between one side of the link of the drum brake device according to claim 1 and a piston of a brake cylinder, and a surface of the push rod facing the piston is formed into a spherical surface. A groove for engaging the link is provided at a portion facing the link. 3. A roller is rotatably provided at one end of the link as an interposing member interposed between one side of the link of the drum brake device according to claim 1 and the piston of the brake cylinder, and the end of the link is provided. A drum brake device characterized in that an outer peripheral surface of a roller is protruded from a portion, and the protruding portion is brought into contact with an outer end surface of an opposed piston. 4. The drum brake device according to claim 1, wherein the interposing member interposed between one side of the link of the drum brake device and the piston of the brake cylinder is a liner made of low friction resin. .