JP2573326Y2 - Duo servo type 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 a duo-servo type drum brake.

[0002]

2. Description of the Related Art A pair of brake shoes, which are provided on a backing plate so as to be able to expand and are connected to each other at one end, are fixed on the backing plate between the other ends of the pair of brake shoes. The other end of the brake shoe is brought into contact with the shoe return spring according to the biasing force of the shoe return spring, and the pair of brake shoes are biased by the shoe return spring by the parking brake operation force transmitted via the parking cable. The braking force generated by the pair of brake shoes is applied to the other brake shoe while the other end of the brake shoe is separated from the anchor member. From the other end of the brake shoe to its anchor member, When Gubureki operation force is released,
There is known a duo-servo type drum brake in which the other end of one brake shoe is abutted against the anchor member according to the urging force of the shoe return spring to reduce the diameter of the pair of brake shoes.

In such a duo-servo type drum brake, a foot-operated type is often used in recent years as a parking brake operating force input device. This foot-operated parking brake operating force input device is normally provided rotatably around one axis at a middle portion in the longitudinal direction, has a plurality of engaging teeth on one end side, and is connected to the parking cable. A longitudinal parking brake pedal that is applied with a pedaling force on the other end side, and is provided so as to be rotatable around one axis in the vicinity of the engagement teeth of the parking brake pedal. A powl engaged with the engagement teeth so as to allow rotation and prevent rotation in the return direction; and rotating the powl in a non-engagement direction to engage the powl with the engagement teeth. And a release mechanism for releasing. As a result, by depressing the parking brake pedal and pulling in the parking cable, the pair of brake shoes are expanded and braking is performed, and the stepped position of the parking brake pedal is maintained based on the engagement between the pawl and the engagement teeth. On the other hand, by releasing the engagement between the pawl and the engagement teeth by the release mechanism, the pair of brake shoes are reduced in diameter while the parking brake pedal is returned, and the brake shoe is brought into a non-braking state. .

[0004]

However, when the engagement between the pawl and the engaging teeth is released, the parking brake pedal is usually rapidly returned according to the tension of the parking cable, and the parking brake operating force is rapidly reduced. In the braking state, the other end of the one brake shoe separated from the anchor member in the braking state is hit against the anchor member at a relatively high speed according to the urging force of the shoe return spring, and a relatively large hitting sound is generated. Sometimes occurred.

The present invention has been made in view of the above circumstances, and a purpose thereof is to make a sound when the end of the brake shoe hits the anchor member when the parking brake operating force is released. Is to provide a duo-servo type drum brake which can suitably suppress the occurrence of a drag.

[0006]

The gist of the present invention to achieve the above object is as follows: (a) Backing play
On the top of each other so as to be able to open each other.
A pair of first brake shoe and second brake shoe connected to
And the other end of a pair of brake shoes (b)
The part is fixed on the backing plate between
The other end of the pair of brake shoes is a shoe return spring
(C) an anchor member abutted according to the urging force of the
The first brake shoe is rotatably disposed on the first brake shoe.
Parking brake operation transmitted via the
Parking brake lever turned by operation
(D) at the other end side of the pair of brake shoes
The parking brake lever and the second brake shoe
And the parking brake operating force
The parking brake lever is rotated by
The other end of the pair of brake shoes
Expands against the urging force of the shoe return spring
(E) a pair of expanded braces with struts.
When the other end of the shoe is pressed against the rotating drum
The braking torque generated by the pair of brake shoes is
One of the pair of brake shoes
With the other end separated from the anchor member.
The other end of the rake shoe abuts its anchor member
To the anchor member, while the parking
When the brake operation force is released, one of the brake shoes
Of the shoe return spring
The pair of breakers
Duo servo type drum shaker with reduced diameter
(F) the one brake shoe and the arm
Provided between the anchor member and the backing plate,
Prior to the other end of one brake shoe being abutted against the anchor member when the parking brake operating force is released, the other brake shoe is elastically deformed as the other end of the brake shoe approaches the anchor member. In other words, the elastic member is included.

[0007]

According to the duo-servo type drum brake having such a configuration, when the parking brake operating force is released, the other end of one of the brake shoes separated from the anchor member is provided with a shoe return spring. Prior to being hit against the anchor member according to the force, the elastic member is elastically deformed as the other end of the brake shoe approaches the anchor member, so that the parking brake operating force is suddenly released. Also, the moving speed of the other end of the brake shoe to the anchor member side can be suitably reduced based on the elastic deformation of the elastic member, whereby the other end of the brake shoe is connected to the anchor member. The impact at the time of hitting, and thus the hitting sound can be suitably suppressed.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 2 is a diagram showing a main part of an example of a duo-servo type drum brake to which the present invention is applied, and is used as, for example, a parking brake mechanism of a drum-in-disk brake. In the figure, a pair of brake shoes 12 and 14 having an arc shape as a whole are supported on a backing plate 10 by a shoe hold-down device 16 and 18 so as to be expandable with each other.
The brake shoes 12 and 14 include a band-shaped shoe rim 20 curved in an arc shape, and a plate-shaped shoe web 22 protruding from an inner peripheral surface of the shoe rim 20 and arranged substantially parallel to the backing plate 10. And a lining 24 fixed to the outer peripheral surface of the shoe rim 20.
The lower end of the shoe web 22 of the brake shoes 12 and 14 in FIG.
6, and are engaged with both ends of a connecting member 28 whose length in the axial direction is variable according to the urging force of a spring (not shown).

On the other hand, the other ends of the shoe webs 22 of the brake shoes 12 and 14 (hereinafter simply referred to as brake shoes 1).
2 and 14), as shown in FIGS. 2 and 3, can be brought into contact with anchor pins 30 fixed on the backing plate 10, respectively. Male screw member 32 screwed
Shoe return springs 34, 36 stretched between the brake shoes 12 and 14, respectively, are constantly biased toward the anchor pin 30 side. The above anchor pin 30
Is a component of the anchor member of the present embodiment, and has a large-diameter portion 38 and a small-diameter portion 40 integrally provided, and is integrally provided at an end of the large-diameter portion 38 on the opposite side to the small-diameter portion 40. The plate-shaped fixing portion 42 is fixed to the backing plate 10 with a plurality of bolts 44 and the like, and the other end portions of the brake shoes 12 and 14 are brought into contact with the outer peripheral surface of the small diameter portion 40. ing.

On the shoe web 22 of the brake shoe 12, a parking brake lever 4 having a long plate shape is provided.
6 is rotatably provided at one end, and a strut 48 is bridged between a middle portion of the parking brake lever 46 in the longitudinal direction and the other brake shoe 14. One end of a parking cable 50 is connected to the other end of the parking brake lever 46,
The other end of the parking cable 50 is connected to a parking brake pedal (not shown) of a foot-operated parking brake operation force input device. Brake shoe 1
2 corresponds to the first brake shoe, and the brake shoe 14
Corresponds to the second brake shoe. 2 and 3, reference numeral 52 denotes a shoe lifting prevention plate, and reference numeral 54 denotes a cable guide.

In the duo-servo type drum brake constructed as described above, when the parking brake pedal is depressed, the parking cable 50 is pulled in and the parking brake lever 46 is rotated counterclockwise in FIG. As a result, the brake shoes 14 are pushed out to the outer peripheral side by the struts 48 and pressed against the inner peripheral surface of the rotating drum (not shown), and the brake shoes 12 are pushed out to the outer peripheral side by the reaction force, and the inner peripheral surface of the rotating drum , And braking is performed. At this time, the brake shoes 12, 14 are caused to rotate in the circumferential direction of the rotary drum according to the direction of the rotational force acting on the rotary drum, and the braking torque generated on the brake shoes 12, 14 is reduced. 14 is transmitted to the anchor pin 30 and received by the anchor pin 30. That is, when, for example, a rotational force in the direction A in FIG. 2 is acting on the rotating drum, the other end of the brake shoe 12 is rotated by the above-mentioned rotation so that the outer peripheral surface of the small diameter portion 40 of the anchor pin 30 as shown in FIG. With a predetermined distance L from the brake shoes 12, 1
4 is transmitted from the other end of the brake shoe 14 to the anchor pin 30, while the A
When a rotational force in the opposite direction is acting, the other end of the brake shoe 14 is separated from the outer peripheral surface of the small diameter portion 40 of the anchor pin 30 by a predetermined distance L due to the above-mentioned rotation, and the brake shoe 12 is rotated. , 14 are transmitted to the anchor pin 30 from the other end of the brake shoe 12. The stepping position of the parking brake pedal is held by a powl (not shown) that meshes with the engagement teeth provided on the parking brake pedal. Can be released by a release mechanism (not shown) provided with. Further, the distance L increases with the wear of the lining 24 of the brake shoes 12 and 14.

When the engagement between the pawl and the engagement teeth is released by operating the release knob or the like in the braking state, the parking brake pedal is rapidly returned according to the tension of the parking cable 50, and the parking brake is released. The operating force is suddenly released. As a result, the parking brake lever 46 is rotated clockwise in FIG. 2 according to the biasing force of the shoe return spring 34 or 36, while the anchor pin 3 is in the braking state.
The other end of the brake shoe 12 or 14 separated from the outer peripheral surface of the small diameter portion 40 by the predetermined distance L abuts against the outer peripheral surface of the small diameter portion 40 of the anchor pin 30 according to the urging force of the shoe return spring 34 or 36. As a result, the diameter of the brake shoes 12, 14 is reduced.

In this embodiment, the surface of the shoe web 22 of each of the brake shoes 12 and 14 on the anchor pin 30 side (the other end) and the surface facing the backing plate 10 is further illustrated in FIG. As shown in FIGS. 1 and 3, leaf springs 56 and 57 are fixed, respectively. As shown in FIG. 4, the leaf springs 56, 57
And an inclined portion 60 extending from one end of the fixed portion 58 and inclining at a predetermined angle θ with respect to the fixed portion 58 to form a “<” shape in a natural state. 60 are fixed to the shoe webs 22 of the brake shoes 12 and 14 by the rivets 62 at the fixing portion 58 in a state where the inclined portions 6 are located on the anchor pin 30 side.
The surface facing the anchor pin 30 of JIS
Rubber sheet 64 having a thickness of and, for example, about 1~2mm has a hardness of about H _R 40 to 50 in A-type spring hardness tester is integrally fixed, respectively.

The brake shoes 1 of the leaf springs 56 and 57
2, 14 fixed position to the shoe web 22, inclined portion 60
Of the brake shoes 12, 14 according to the biasing force of the shoe return springs 34, 36 when the parking brake operation force is released. Prior to being abutted against the outer peripheral surface of the small diameter portion 40 of the anchor pin 30, the inclined portions 60 of the leaf springs 56, 57
And the other end of the brake shoes 12, 14 is in contact with the outer peripheral surface of the large diameter portion 38 of the anchor pin 30 via the anchor pin 3.
The leaf springs 56, 57 come close to the small-diameter portion 40.
Are preferably elastically deformed, and the brake shoes 12, 1
The shoe return springs 34, 36 are provided so that the moving speed of the other end of the fourth member 4 toward the anchor pin 30 can be suitably reduced.
And the distance L when the brake shoes 12 and 14 are new (when the lining 24 is not worn) and the distance L when the lining 24 is at the maximum allowable wear. Accordingly, in the present embodiment, together with the leaf spring 56,5 7 constitutes a resilient member, the inclined portion of the plate spring 56, 57 with the access to the anchor pin 30 of the other end of the brake shoes 12, 14 60
Since the rubber sheet 64 fixed to the rubber sheet 64 is also slightly elastically deformed, it can be said that the rubber sheet 64 also constitutes an elastic member. In this embodiment,
When the brake shoes 12, 14 are new, the inclined portions 60 of the leaf springs 56, 57 and the rubber sheet 64 of the brake shoes 12, 14, which are separated from the anchor pin 30, as shown in FIG. 3
It is configured to be slightly separated from the outer peripheral surface of the large diameter portion 38 (only the separated state of the leaf spring 56 is shown in FIG. 1).

As described above, according to the present embodiment, when the parking brake operation force is released, the other end of the brake shoe 12 or 14 separated from the anchor pin 30 by a predetermined distance L is connected to the shoe return spring 34 or 36. The small diameter portion 40 of the anchor pin 30 according to the urging force of
Prior to being hit by the
Small diameter portion 40 of anchor pin 30 at the other end of 2 or 14
Spring 56 and its rubber sheet 6
4 or the leaf spring 57 and its rubber sheet 64 are elastically deformed, whereby the moving speed of the other end of the brake shoe 12 or 14 toward the anchor pin 30 can be suitably reduced. Even if the parking brake pedal is suddenly returned in accordance with the tension of the parking cable 50 due to the disengagement of the engagement teeth from the pawl and the pawl, and the parking brake operating force is suddenly released, the brake shoes 12 or 14 Is the small diameter portion 4 of the anchor pin 30
It does not suddenly hit the zero, and the hitting sound when the other end of the brake shoe 12 or 14 hits the anchor pin 30 can be suitably suppressed.

According to this embodiment, the leaf springs 56, 5
7 is brought into contact with the anchor pin 30 via the rubber sheet 64 fixed thereto, so that the leaf spring 5
There is an advantage that the sound of hitting when the 6, 57 inclined portions 60 hit the anchor pin 30 can be suitably prevented.

While the embodiment of the present invention has been described with reference to the drawings, the present invention can be applied to other embodiments.

For example, in the above embodiment, the leaf springs 56,
A rubber sheet 64 is fixed to one surface of the inclined portion 60 of the brake 57, and the inclined portions 60 of the leaf springs 56, 57 and the rubber sheet 6 in the brake shoes 12, 14 separated from the anchor pin 30 in the braking state.
The rubber sheet 64 is configured to be separated from the outer peripheral surface of the large diameter portion 38 of the anchor pin 30.
The effect of the present invention can be obtained even when the brake shoe is not provided, and in the braking state, the brake shoes 12 and 14 separated from the anchor pin 30 can be used.
The rubber sheet 64 fixed to the leaf springs 56, 57 or the inclined portions 60 of the leaf springs 56, 57 not provided with the rubber sheet 64 are configured to contact the outer peripheral surface of the large diameter portion 38 of the anchor pin 30. Is also good.

In the above-described embodiment, the leaf springs 56, 57 as elastic members are fixed to the shoe webs 22 of the brake shoes 12, 14, but this is not always necessary. It is also possible to fix to the shoe rim 20 and the backing plate 10. In the latter case, the plate spring fixed to the backing plate 10 is configured to be elastically deformed based on the contact of the brake shoes 12 and 14 with the inner peripheral surface of the shoe rim 20 or the like.

In the above embodiment, the elastic member is constituted by the leaf springs 56 and 57 and the rubber sheet 64, but it is not always necessary. For example, the elastic member may be constituted by a rubber block or a compression coil spring. It is possible.

Further, in the above-described embodiment, the case where a foot-operated type is used as the parking brake operating force input device for the duo servo type drum brake is described. However, the parking brake operating force input device having the hand lever is used. Even if it is used, the effect of the present invention can be obtained when the parking brake operation force is suddenly released.

In the above embodiment, the case where the present invention is applied to a duo servo type drum brake having only a parking brake mechanism has been described. However, a duo servo having a service brake mechanism using a parking brake mechanism and a wheel cylinder has been described. Needless to say, the present invention can be applied to a type drum brake.

In addition, the present invention can be variously modified without departing from the gist thereof.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a braking state of a duo-servo type drum brake of FIG. 2, and is a diagram corresponding to FIG.

FIG. 2 is a diagram illustrating an example of a duo-servo type drum brake to which the present invention is applied, and is a diagram illustrating a main part.

FIG. 3 is an enlarged view of a main part in a section taken along line III-III in FIG. 2;

FIG. 4 is an enlarged perspective view of the leaf spring of FIG. 3 in a natural state.

[Explanation of symbols]

10: backing plate 12: brake shoe (first brake shoe) 14: brake shoe (second brake shoe) 30: anchor pin (anchor member) 34, 36: shoe return spring 46: parking brake lever 48: strut 50: parking cable 56, 57: leaf spring (elastic member) 64: rubber sheet (elastic member)

Claims (1)

(57) [Scope of request for utility model registration] 1. A pair of first and second pair of members which are provided on a backing plate so as to be able to expand and are connected to each other at one end .
The first and second brake shoes are fixed on the backing plate between the other ends of the pair of brake shoes, and the other ends of the pair of brake shoes are brought into contact with each other according to the biasing force of the shoe return spring. Can be pivoted on the anchor member and the first brake shoe
And transmitted via the parking cable.
Parkin rotated by the working brake operating force
Brake lever and the other end of the pair of brake shoes
The parking brake lever and the second
Between the brake shoe and the parking brake
The parking brake lever is turned by the rake operation force.
By being moved, the pair of brake shoes
End against the urging force of the shoe return spring
An expanding strut, and the pair of expanded
-The other end of the shoe is pressed against the rotating drum.
The braking torque generated by the pair of brake shoes is changed by the other end of the other brake shoe while the other end of the other brake shoe is separated from the anchor member. while being brought into contact with the transmission to the anchor member, wherein the parking brake operating force is released, abuts on the anchor member by the biasing force of the other end portion of one of the brake shoe the said shoe return spring A duo-servo-type drum brake in which the pair of brake shoes are reduced in diameter, wherein the one brake shoe and the anchor member
Is provided between the King plate, the other end of the parking said one brake shoe during release of the brake operating force prior to being pressed against the said anchor member, said anchor member at the other end of the brake shoe A duo-servo-type drum brake comprising an elastic member that is elastically deformed when approaching the drum.