JP4016706B2 - Drum brake device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a drum brake device in which a rotational force transmitting member is disposed between opposite ends of a pair of brake shoes built in a drum that rotates integrally with a wheel.
[0002]
[Prior art]
6 and 7 are diagrams showing a drum-in disc brake device mounted on, for example, a rear wheel of a vehicle. This device includes a back plate 2 fixed to a knuckle on the vehicle body side with mounting bolts, a disc brake device 8 having a caliper 6 straddling the disc rotor 4, and a hat of the disc rotor 4 incorporated in the back plate 2. And a drum brake device 12 built in the internal space of the unit 10. In addition, the member of the code | symbol 14 currently fixed to the backplate 2 coaxially is a dust-proof cover.
[0003]
The drum brake device 12 is elastically supported by the back plate 2 by a shoe hold-down device 16 and has a pair of substantially arc-shaped brake shoes 20a and 20b disposed facing the inner peripheral surface 10a of the hat portion 10, and these brake shoes. An adjuster 22 that is interposed between one longitudinal ends of 20a and 20b and adjusts the distance between the friction surfaces of the brake shoes 20a and 20b, and the other longitudinal end of the brake shoes 20a and 20b. A toggle mechanism 24 for expanding the diameter of the pair of brake shoes 20a and 20b during parking operation, and a side surface 20a _{1 on} the other end of the pair of brake shoes 20a and 20b from the back plate 2. 20b _1, a rotational force transmission member with a gap between the side surfaces 20a ₁ and 20b ₁ Each anchor block 26 and return springs 27a and 27b spanned between the pair of brake shoes 20a and 20b.
[0004]
The pair of brake shoes 20a and 20b includes a substantially crescent-shaped web 21a made of a metal material, and a rim made of a metal material having an arc plate shape and the outer peripheral end face of the web 21a being fixed in the circumferential direction of the central portion of the plate width. 21b and a brake lining 21c fixed to the outer peripheral curved surface of the rim 21b and having a lining surface facing the inner peripheral surface 10a.
[0005]
The aforementioned anchor block 26 as a rotational force transmitting member is formed in a substantially rectangular parallelepiped shape and rises from the back plate 2, and as described above, the other side surfaces 20a ₁ and 20b ₁ of the pair of brake shoes 20a and 20b and There is a gap between them. The function of the anchor block 26 is that a shoe hold-down device is used when the brake lining 21c of the pair of brake shoes 20a and 20b abuts against the inner peripheral surface 10a of the hat portion 10 to perform a braking action by the operation of the toggle mechanism 24. The pair of brake shoes 20 a and 20 b elastically supported by the back plate 2 by 16 is prevented from excessively dragging with the rotation of the hat portion 10.
[0006]
However, since the brake shoes 20a and 20b are arranged with a slight gap between the side surfaces 20a ₁ and 20b ₁ and the end face of the anchor block 26, when the vehicle travels on a rough road. The brake shoes 20a and 20b elastically supported by the shoe hold-down device 16 rotate toward the anchor block 26, and the side surfaces 20a ₁ and 20b ₁ frequently collide with the end surface of the anchor block 26 so that the metal hits each other. Sound will be generated. If this abnormal noise (battering sound between metals) is continuously transmitted to the inside of the vehicle while traveling on a rough road, there is a risk of discomfort to the people in the vehicle.
[0007]
Therefore, in Japanese Patent Application Laid-Open No. 2001-74078 filed earlier by the present applicant, a buffer member comprising a fixed portion and an elastically deformable buffer portion bent at a right angle from the fixed portion is provided with a pair of brakes. It connects with each web 21a of shoes 20a and 20b. That is, the fixing portion of the buffer member is fixed to each web 21a of the pair of brake shoes 20a and 20b, and the buffer portion is provided between the block end surface of the anchor block 26 and the side surfaces 20a ₁ and 20b ₁ of the brake shoes 20a and 20b. It is located and arranged. Then, the buffer section, a gap of predetermined dimension between the block end face is provided with a predetermined gap in between the side surface 20a _1, 20b _1.
[0008]
According to the drum-in disc brake device provided with a cushioning member having the above configuration, for example, the vehicle is elastically supported brake shoes 20a rotate the shoe hold-down device 16 by traveling on a rough road, the side surface 20a ₁ anchor block When moving to the block end face side of 26, first, the buffer portion of the buffer member collides with the block end face and absorbs the collision force by elastic deformation. Next, the buffer portion that continues to be elastically deformed abuts against the side surface 20a ₁ and elastically deforms, thereby further absorbing the collision force. In this manner, the shock-absorbing sound between the metals is prevented by elastically deforming the buffer portion and absorbing the collision force.
[0009]
[Problems to be solved by the invention]
Incidentally, since the clearance between the side surfaces 20a ₁ and 20b _{1 of} the pair of brake shoes 20a and 20b and the block end surface of the anchor block 26 is usually as small as about 2 mm, Japanese Patent Laid-Open No. 2001-74078 having a buffer member is disclosed. In this technique, if it is attempted to arrange a buffer member capable of absorbing a collision force that leads to a hitting sound, it is difficult to lay out components. Further, if a buffer member having a size capable of sufficiently absorbing the collision force is disposed, there is a risk of interference with other parts such as the hat portion 10.
[0010]
The present invention has been made in view of the above circumstances, and is a drum brake device that can reliably suppress the generation of noise due to contact between a brake shoe and a rotational force transmission member when the vehicle travels on a rough road. The purpose is to provide.
[0011]
[Means for Solving the Problems]
According to the first aspect of the present invention, a drum that rotates integrally with a wheel, a pair of substantially arc-shaped brake shoes disposed opposite to an inner peripheral surface of the drum, and the pair of brake shoes are fixed to a knuckle on the vehicle body side. A pair of shoe hold-down devices that are respectively supported by the back plates and one end in the longitudinal direction of the pair of brake shoes. A rotational force transmitting member that receives a shoe rotational force generated when the shoe rotates in a direction toward itself and contacts one end thereof, and each of the pair of shoe holddown devices includes the back plate A pin that is fixed to the pin and an elastic body that elastically supports the brake shoe by engaging between the pin and the brake shoe. In the brake device, on the surface of the rotational force transmitting member facing the ends of the pair of brake shoes, the end portion rides and slides as the brake shoe rotates in a direction toward the rotational force transmitting member, An inclined surface spaced from the back plate side is provided, and the inclined surface transmits a part of the shoe rotational force to the elastic body and absorbs a part of the shoe rotational force by elastically deforming the elastic body. The rotational reaction force generating means for generating the rotational reaction force is used.
[0012]
According to a second aspect of the present invention, in the drum brake device according to the first aspect, the inclined surface of the rotational force transmitting member serving as the rotational reaction force generating means has the pair of brake shoes connected to the rotational force transmitting member. A concave curved surface having a gradually increased inclination angle is formed in a direction in which the end portion rides up and slides as it rotates in the direction of heading.
According to a third aspect of the present invention, in the drum brake device according to the second aspect, the ends of the pair of brake shoes that slide on the upper end surface of the rotational force transmitting member on the inclined surface are inclined. A stopper member was provided to prevent it from coming off the surface.
[0013]
According to a fourth aspect of the present invention, in the drum brake device according to any one of the first to third aspects, the tip ends of the pair of brake shoes that contact the inclined surfaces are in surface contact with the inclined surfaces. It was formed as a sloped surface.
[0014]
【The invention's effect】
According to the first aspect of the present invention, the pair of brake shoes supported by the shoe hold-down device rotate in the direction toward the rotational force transmitting member as when the vehicle travels on a rough road, When the rotational force transmitting member receives the shoe rotational force, the rotational reaction force generating means generates a rotational reaction force that absorbs the shoe rotational force by elastically deforming the elastic body constituting the shoe holddown device. The sound with which a pair of brake shoes are hit | damaged to a rotational force transmission member can be suppressed. Therefore, it is possible to suppress the generation of abnormal noise of the drum brake device when the vehicle travels on a rough road.
[0015]
According to the first aspect of the present invention, the rotational reaction force determined by the inclination angle of the inclined surface of the rotational force transmitting member provided as the rotational reaction force generating means and the elastic force of the elastic body exceeds the shoe rotational force. By doing so, it is possible to reliably prevent the sound of the pair of brake shoes being struck against the rotational force transmission member. Further, since no parts are interposed between the pair of brake shoes and the rotational force transmitting member, the parts layout is easy and there is no possibility of interference with other parts constituting the apparatus.
[0016]
According to the second aspect of the present invention, for example, an unnecessarily large shoe rotational force acts in a direction toward the rotation transmission member, and the end of the brake shoe is inclined at a high speed, and the curved shape of the torque transmission member is inclined. Even if it rides on the end of the surface and slides, the speed of the end of the brake shoe gradually decreases by sliding the position where the upward inclination angle of the curved inclined surface is increased. The sound that the brake shoe is struck against the rotational force transmitting member can be suppressed.
[0017]
According to the invention of claim 3 , since the stopper member is provided on the upper end surface of the rotational force transmission member, a shoe rotational force larger than expected acts in the direction toward the rotational transmission member, and the end portion of the brake shoe Even if it moves to above the inclined surface, the stopper member can reliably prevent the end of the brake shoe from coming off the rotational force transmitting member.
[0018]
Furthermore, according to the invention described in claim 4 , since the tips of the ends of the pair of brake shoes that contact the inclined surface of the rotational force transmitting member are formed as the inclined surfaces that are in surface contact with the inclined surface, Even if the shoe rotational force that is larger than expected acts in the direction of the direction and the ends of the pair of brake shoes slide on the inclined surface of the rotational force transmitting member, the inclined surface is prevented from being damaged . In addition to preventing malfunction due to damage, it is possible to prevent the generation of noise when the tip portions of the pair of brake shoes slide on the inclined surface.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments according to the present invention will be described with reference to the drawings. The same components as those of the drum-in-disc brake device shown in FIGS. 6 and 7 are denoted by the same reference numerals, and description thereof is omitted.
1 and 2 show the main part of a drum-in-disc brake device according to a first embodiment of the present invention.
[0020]
FIG. 1 shows only one brake shoe 20b of the pair of brake shoes 20a and 20b, and shows a state where one web end 20b _{2 in} the longitudinal direction of the brake shoe 20b is in contact with the anchor block 30. ing. FIG. 2 shows a state where one web end 20a ₂ , 20b _{2 in} the longitudinal direction of the pair of brake shoes 20a, 20b is in contact with the anchor block 30. An adjuster 22 for adjusting the distance between the brake shoes 20a and 20b and the friction surface is interposed between the other ends in the longitudinal direction of the pair of brake shoes 20a and 20b.
[0021]
The pair of brake shoes 20a, 20b is elastically supported on the back plate by a shoe hold-down device 16. As shown in FIG. 1, the shoe hold down device 16 includes a shoe hold pin 16a and a shoe hold spring 16b made of a coil spring, and is provided at a substantially central portion in the longitudinal direction of the web 21a of the brake shoe 20b. The shoe hold spring 16b is fitted into the through hole, and the shoe hold pin 16a that has passed through the shaft center of the shoe hold spring 16b is fixed to the back plate 2, so that one brake shoe 20b is elastically supported by the back plate 2. ing. The other brake shoe 20a has the same structure and is elastically supported by the back plate by the shoe hold-down device 16.
[0022]
The anchor block 30 of this embodiment, a pair of brake shoes 20a, the surface facing the web end portion 20a _2, 20b ₂ and 20b is, in accordance separated from the web end 20a _2, 20b _2, at a predetermined taper angle θ The taper surfaces 30a and 30b are formed so as to be inclined upward and are fixed on the back plate 2.
When the vehicle travels on a rough road, a rotational force that rotates the pair of brake shoes 20a and 20b elastically supported by the shoe hold-down device 16 in the direction from the disk rotor 4 toward the anchor block 30; Alternatively, a rotational force that rotates in a direction away from the anchor block 30 acts, but when a rotational force in the direction toward the anchor block 30 acts on the brake shoes 20a and 20b, the web ends 20a ₂ of the brake shoes 20a and 20b. , 20b ₂ rides on the tapered surfaces 30a, 30b described above and slides.
[0023]
When the brake shoe 20b in the direction toward the anchor block 30 rotates, as shown in FIG. 1, one of the web end portion 20b ₂ of the longitudinal rides on the tapered surface 30a, of the other longitudinal end portion side rim 21b contacts the convex part 2a provided in the back plate 2, and the brake shoe 20b is inclined.
As described above, when the brake shoe 20b is inclined, the shoe hold spring (coil spring) 16b constituting the shoe hold down device 16 is shortened and elastically deformed. Using the elastic deformation of the shoe hold spring 16b, the rotational force F _N that rotates the brake shoe 20b in the direction toward the anchor block 30 is absorbed. Note that the rotational force F _N may be obtained in advance by an experiment or the like assuming a rough road.
[0024]
That is, when the brake shoe 20b is inclined, the brake shoe 20b is subjected to a set force F _S of the shoe-hold spring 16b in the contacts on the opposite side of the rim 21b side and one web end portion 20b ₂ of the longitudinal direction. In this case, the shoe-hold spring 16b, so positioned in substantially the center of the web end portion 20b ₂ and the other side of the rim 21b, the substantially reaction force F _S / 2 of the same force in the contacts acts.
[0025]
At this time, when the web end portion 20b ₂ of the brake shoe 20b rides on the tapered surface 30a, the rotational reaction force F _R of the brake shoe 20b is generated in the direction against the rotating force F _N is the following (1) This is determined by the relationship between the set force F _S of the shoe hold spring 16b and the taper angle θ of the taper surface 30a.
F _R = F _S / 2 × tanθ (1)
Therefore, with respect to the rotational force F _N to rotate in a direction toward the brake shoe 20b to the anchor block 30, so that the rotational reaction force F _R of the brake shoe 20b is above, i.e. such that the following relationship (2), The setting force F _S of the shoe hold spring 16b and the taper angle θ of the tapered surface 30a are set.
[0026]
F _N <F _R (2)
Also, the other brake shoe 20a, relative to the rotational force F _N to rotate in a direction toward the anchor block 30, so that the rotational reaction force F _R of the brake shoe 20a is above, i.e., the (2) equation relationship with Thus, the set force F _S of the shoe hold spring 16b and the taper angle θ of the taper surface 30b are set. For example, assuming that F _S = 10 kgf and F _N = 2 kgf, the taper angle θ = 30 °.
According to the drum-in disc brake device having the above-described configuration, when the vehicle travels on a rough road, the anchor block 30 from the disc rotor 4 side to the pair of brake shoes 20a and 20b elastically supported by the shoe hold-down device 16 is provided. Even when a rotational force F _N that rotates in the direction toward the direction of the force acts, the set force F _S of the shoe hold spring 16b and the taper angle θ of the taper surface 30b of the anchor block 30 are set to specific values, so that the rotational force as above the F _N, it is possible to generate a pair brake shoes 20a, a rotational reaction force F _R of 20b, whereby the striking noise of the conventional such pair of brake shoes and the anchor block does not occur. Therefore, it is possible to suppress the generation of abnormal noise in the drum-in disc brake device when the vehicle travels on a rough road.
[0027]
In addition, since no parts are interposed between the pair of brake shoes 20a, 20b and the anchor block 30, the parts layout is easy and there is a risk of interference with other parts constituting the drum-in disc brake device. Nor.
Here, the shoe hold spring 16b which comprises the shoe hold down apparatus 16 of this embodiment is equivalent to the elastic body of this invention. Further, the anchor block 30 of the present embodiment corresponds to the rotational force transmission member of the present invention.
[0028]
Next, what is shown in FIG. 3 shows the anchor block of 2nd Embodiment which concerns on this invention.
In the anchor block 32 of the present embodiment, the surface facing the web end portion 20b ₂ of one brake shoe 20b is formed into a concave curved surface 32a with an gradually increasing inclination angle as the distance from the web end portion 20b ₂ increases. Is formed.
[0029]
Thus, by providing the anchor block 32 having a concave curved surface 32a facing the web end portion 20b ₂ of the brake shoe 20b, for example, in a direction towards the anchor block 32, a large rotational force than expected F _NL Even if the web end 20b ₂ of the brake shoe 20b rides and slides on the end of the curved surface 32a at a high speed, the web end 20b ₂ has a position where the upward inclination angle of the curved surface 32a is increased (FIG. 3). since the speed gradually numerals 32a ₁ side) by sliding movement is getting late, hitting sound is hardly generated between the brake shoe 20b and the anchor block 32. Therefore, similar to the first embodiment, it is possible to suppress the generation of abnormal noise of the drum-in disc brake device when the vehicle travels on a rough road.
[0030]
Although not shown, also the other surface facing the web end portion 20a ₂ of the brake shoes 20a, in accordance with away from the web end portion 20a _2, are formed in the up-ramp angle larger the concave curved surface progressively Therefore, the same effect can be produced.
Next, what is shown in FIG. 4 shows an anchor block according to a third embodiment of the present invention.
[0031]
In the present embodiment, a plate-like shoe stopper 34 is integrally fixed to the upper end surface of the anchor block 30 shown in the first embodiment.
Since the shoe stopper 34 is integrally fixed to the upper end surface of the anchor block 30 in this way, a larger rotational force F _NL acts on the brake shoe 20b in the direction toward the anchor block 30 than expected, and the web of the brake shoe 20b Even if the end 20b ₂ slides on the taper surface 30a and moves upward, the shoe stopper 34 reliably prevents the web end 20b ₂ from coming off the anchor block 30. Accordingly, by providing the shoe stopper 34, it can the web end portion 20b ₂ of the brake shoe 20b is always kept a state of being opposed to the tapered surface 30a of the anchor block 30, the vehicle travels on a rough road Occurrence of abnormal noise in the drum-in disc brake device can be reliably suppressed.
[0032]
In the present embodiment, the shoe stopper 34 is separately fixed to the upper end surface of the anchor block 30, but the same effect can be obtained even if an anchor block integrated with the shoe stopper is formed.
Next, what is shown in FIG. 5 shows a fourth embodiment according to the present invention.
In the present embodiment, a sloped surface 36 is formed at the tip 20b ₃ of the web 21a constituting the brake shoe 20b so as to be in surface contact with the tapered surface 30a of the anchor block 30.
[0033]
As described above, when the inclined surface 36 is formed at the tip 20b ₃ of the web 21a, even if the torque _FNL larger than expected acts on the brake shoe 20b and collides with the tapered surface 30a, the tapered surface 30a is damaged. is prevented, it is possible to prevent failure and operation due to damage of the tapered surface 30a, the occurrence of abnormal noise when the distal end portion 20b ₃ of the brake shoe 20b is slid on the tapered surface 30a.
[0034]
In the first to fourth embodiments, the coil spring is exemplified as the shoe hold spring 16b. However, the gist of the present invention is not limited to this, and for example, the same applies to a disc spring or a leaf spring. The effect of can be produced.
In each embodiment, the brake shoes 20a and 20b are elastically supported by the back plate 2 by disposing the shoe hold spring 16b at a substantially central portion in the longitudinal direction of the brake shoes 20a and 20b. The gist of the invention is not limited to this structure. For example, a plurality of shoe hold springs are arranged at equal distances from the substantially central part in the longitudinal direction of the brake shoes 20a, 20b, and the brake shoes 20a, 20b are arranged. Even if the back plate 2 is elastically supported, the same effects can be obtained.
Furthermore, although each embodiment has been described as applied to a drum-in-disc brake device, the same effects can be achieved even when applied to a normal drum brake device.
[Brief description of the drawings]
FIG. 1 is a diagram showing a state in which a brake shoe according to a first embodiment of the present invention rides on a rotational force transmission member.
FIG. 2 is a diagram showing a state in which a pair of brake shoes rides on a rotational force transmission member in the first embodiment.
FIG. 3 is a view showing a rotational force transmission member of a second embodiment in which an inclined surface having a concave curved surface according to the present invention is formed.
FIG. 4 is a view showing a rotational force transmission member of a third embodiment provided with a stopper member according to the present invention.
FIG. 5 is a view showing a fourth embodiment in which a slope surface in surface contact with the inclined surface of the rotational force transmitting member is provided at the tip of the end portion of the brake shoe according to the present invention.
FIG. 6 is a diagram showing a drum brake device built in a conventional hat portion.
FIG. 7 is a cross-sectional view showing a conventional drum brake device.
[Explanation of symbols]
2 Back plate 2a Convex part of back plate 4 Disc rotor (drum)
DESCRIPTION OF SYMBOLS 10 Hat part 10a Inner peripheral surface 12 Drum brake device 16 Shoe hold down device 16a Shoe hold pin 16b Shoe hold spring (elastic body)
20a, 20b brake shoe 20a _2, 20b ₂ web end portion (one end portion in the longitudinal direction of the brake shoe)
20b ₃ Brake shoe tip 21a Web 21b Rim 21c Brake lining 30, 32 Anchor block (rotational force transmission member)
30a, 30b Tapered surface (inclined surface)
32a Concave curved surface (inclined surface with concave curved surface)
34 Shoe stopper (stopper member)
36 Gradient surface _FN rotational force (shoe rotational force)
F _R Rotation reaction force F _S Shoe hold spring setting force θ Taper angle (angle of inclined surface)

Claims (4)

A drum that rotates integrally with the wheel, a pair of substantially arc-shaped brake shoes disposed opposite to the inner peripheral surface of the drum, and a back plate that fixes the pair of brake shoes to a knuckle on the vehicle body side. Between the pair of shoe holddown devices and one end of the pair of brake shoes in the longitudinal direction and fixed to the back plate, and the pair of brake shoes rotate in a direction toward itself. Each of the pair of shoe hold-down devices includes a pin fixed to the back plate, A drum brake device having an elastic body engaged between the brake shoes and elastically supporting the brake shoes;
As the brake shoe rotates in a direction toward the rotational force transmitting member on the surface of the rotational force transmitting member facing the end portions of the pair of brake shoes, the end portion rides up and slides, A rotational reaction force that absorbs a part of the shoe rotational force by providing an inclined surface that is separated from the elastic surface, transmitting a part of the shoe rotational force to the elastic body, and elastically deforming the elastic body. A drum brake device characterized in that it is a rotational reaction force generating means for generating The inclined surface of the rotational force transmitting member serving as the rotational reaction force generating means gradually increases in a direction in which the end portion rides up and slides as the pair of brake shoes rotate in the direction toward the rotational force transmitting member. 2. The drum brake device according to claim 1, wherein the drum brake device is formed in a concave curved surface with a large inclination angle . 3. A stopper member for preventing the end portions of the pair of brake shoes that slide on the inclined surface from slipping off the inclined surface is provided on an upper end surface of the rotational force transmitting member. The drum brake device described . The drum brake according to any one of claims 1 to 3, wherein tips of end portions of the pair of brake shoes that are in contact with the inclined surfaces are formed as inclined surfaces so as to be in surface contact with the inclined surfaces. apparatus.

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