JP2000266089A - Brake device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a brake device which can obtain stable braking force, and at the same time, can obtain large braking force by a small brake input, and is suitable for miniaturization and reduction of weight. SOLUTION: This brake device is equipped with a brake shoe 5 arranged oppositely to a braking surface 3a formed on the peripheral surface of a braked member 3, a brake shoe driving mechanism 7 for generating braking force by push-pressing the brake shoe 5 to the braking surface 3a according to braking operation, and braking auxiliary arms 11, 12 whose base ends are journalled by a non-rotary body 9 and also whose ends are functionally engaged with the brake shoe 5, and which are swung by circumferential force applied to the brake shoe 5 at the time of braking. Brake shoe push-pressing parts 11c, 12c for push-pressing the brake shoe 5 to the braking surface 3a by the swinging of the braking auxiliary arms 11, 12 are equipped at the ends of these braking auxiliary arms 11, 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake device which can stabilize the braking effect and can obtain a large braking force with a small brake input, and is suitable for reducing the size and weight of the device. .

[0002]

2. Description of the Related Art Conventionally, drum brake devices and disc brake devices have been widely used as brake devices mounted on automobiles and the like. The drum brake device presses a friction material (brake lining) of a brake shoe arranged inside a substantially cylindrical drum against the inner peripheral surface of the drum,
In this configuration, a braking force is generated by a frictional force between the inner peripheral surface of the drum and the friction material. On the other hand, the disc brake device has a configuration in which a friction material of a brake pad is pressed against the surface of a disk-shaped rotor, and a braking force is generated by a friction force between the rotor surface and the friction material.

[0003]

Generally, in a drum brake device, the braking effect is high due to a servo effect at the time of braking, so that a large braking force can be obtained, and the device is reduced in size and weight. easy. On the other hand, however, the braking surface is likely to become hot due to friction on the inner peripheral surface of the drum, which is almost in a sealed state, and water entering the drum is likely to be thinned on the braking surface and remain on the braking surface. However, there is a problem that a fading phenomenon, which lowers the braking effect, is likely to occur due to a rise in temperature and remaining water. Further, since the braking effect is high due to the servo effect, there is also a problem that the braking effect is likely to fluctuate due to a change in the friction coefficient between the braking surface and the brake shoe, and it is difficult to stabilize the braking effect.

[0004] On the other hand, in the case of a disk brake device, there is usually no servo effect, and a change in the braking effect due to a change in the friction coefficient between the braking surface and the brake shoe can be reduced. Further, since the rotor surface, which is the braking surface, is exposed to the outside, it has characteristics of excellent heat dissipation, less water remaining on the braking surface, and less occurrence of a fade phenomenon that reduces the effectiveness of the brake. Therefore, a stable braking force can be obtained by stabilizing the braking effect. However, on the other hand, as described above, since there is no servo effect, it is necessary to increase the brake input in order to obtain a large braking force. There is a problem that problems such as an increase in size and an increase in weight are likely to occur.

[0005] The present invention has been made in view of the above circumstances, and at the same time stabilizes the braking effect and can obtain a large braking force with a small brake input, and is suitable for reducing the size and weight of the device. It is intended to provide a device.

[0006]

According to a first aspect of the present invention, there is provided a brake device, comprising: a brake shoe disposed opposite a braking surface formed on an outer periphery of a member to be braked; A brake shoe drive mechanism for generating a braking force by pressing the brake shoe against a braking surface;
A brake assist arm having a base end pivotally supported by the non-rotating body and a tip operatively engaged with the brake shoe to swing by a circumferential force acting on the brake shoe during braking; A brake shoe pressing portion for pressing the brake shoe against a braking surface by the swing of the brake assist arm is provided at a tip of the arm.

According to the above configuration, at the time of braking,
When a circumferential force F of the braked member acts on the brake shoe from the braked member, the brake shoe pressing portion of the brake assist arm presses the brake shoe against the braking surface of the braked member in accordance with the force F, The friction force on the braking surface increases. The servo effect of increasing the braking torque occurs due to the increase in the friction force by the brake shoe pressing portion,
The effectiveness of the brake is improved. Further, although it has a servo effect, it does not become as large as that of a so-called drum brake device, so that the fluctuation of the braking effect due to the fluctuation of the friction coefficient between the braking surface and the brake shoe can be reduced. In addition, since the braking surface is set on the outer periphery of the member to be braked, and the braking surface is exposed to the outside like a rotor of a disc brake device, it is excellent in heat dissipation and water hardly remains on the braking surface, so that the braking effect is improved. Can be prevented from occurring.

Preferably, in the above-mentioned brake device, the brake assist arms are respectively provided at positions spaced apart in the circumferential direction of the member to be braked, and the brake assist arm located on the rotating side of the member to be braked in the rotation direction is provided. A brake assist lever having an intermediate portion pivotally supported at a tip end of the arm, wherein the brake assist lever is operatively engaged with a brake shoe to receive a circumferential force acting on the brake shoe during braking; It is good to have composition which has a part and the 1st end receives the force of the direction of the circumference, and the brake auxiliary lever rocks, and the end side which presses the revolving side of the above-mentioned brake shoe against the braking surface is carried out. With this configuration, the pressing force of the brake shoe against the member to be braked is increased by the brake assist lever even on the outgoing side.
The distribution of the pressing force of the brake shoe on the member to be braked can be made uniform.

Still preferably, in the above-mentioned brake device, the brake shoe driving mechanism has an eccentric cam which frictionally engages with the brake shoe.
With this configuration, the brake shoe can be pressed against the braking surface of the member to be braked with a simple configuration. When the frictional force between the eccentric cam and the brake shoe is set to an appropriate value, when the eccentric cam is rotated to press the brake shoe against the braking surface of the member to be braked, the circumference of the braked member acting on the brake shoe is reduced. The directional force F acts to further rotate the eccentric cam, thereby creating a servo effect that increases the braking torque.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a brake device according to the present invention will be described below in detail with reference to the drawings.
FIGS. 1 to 3 show a first embodiment of a brake device according to the present invention. FIG. 1 is a front view of a main part of the brake device according to the present invention, and FIG. FIG. 3 is a sectional view taken along line BB of FIG.

This brake device 1 is for a vehicle, and has a brake shoe 5 disposed opposite a braking surface 3a formed on the outer periphery of a substantially cylindrical rotor 3 which is a member to be braked. A brake shoe drive mechanism 7 for pressing the brake shoe 5 against the braking surface 3a to generate a braking force, and a base end rotatably supported by a bracket 9 as a non-rotating body via support shafts 8a to 8d. A pair of inverted U-shaped braking assist arms whose distal ends are operatively engaged with the brake shoes 5 and oscillate around the base support shafts 8a to 8d by a circumferential force F acting on the brake shoes 5 during braking. 11 and 12 are provided.

The rotor 3 rotates so as to rotate integrally with the wheels.
It is attached to the wheel axle and rotates in the direction of arrow (a) in FIG. 1 when moving forward. As shown in FIG. 3, the brake shoe 5 includes a pressure plate 14 and a pair of brake linings 15 and 16 fixedly mounted on the surface of the pressure plate 14 in the circumferential direction of the rotor 3. . The pressure plate 14 includes the rotor 3
And a guide portion 14b, 14c rising from both ends of the lining support portion 14a toward the outside in the radial direction of the rotor 3.

The brake shoe 5 includes guide portions 14b, 1
A mounting member 21 screwed to the top of 4c is supported by a guide shaft 22 erected at the tip of a pair of brake assist arms 11 and 12 so as to be able to advance and retreat toward the braking surface 3a, and a return spring ( It is urged by a compression coil spring 23 in a direction away from the braking surface 3a (upward in FIG. 1). That is, the brake shoe 5 is elastically lifted by the pair of brake assist arms 11 and 12 so as to be able to advance and retreat toward the braking surface 3a.

The bracket 9 includes a pair of connecting portions 9a and 9b straddling the outer periphery of the rotor 3, and a support wall 9 extending from an end of the connecting portions 9a and 9b so as to face the front and back surfaces of the rotor 3.
As shown in FIG. 1, it is fixed to a vehicle body-side structure 18 such as a knuckle by a mounting bolt 19. The support shafts 8a and 8b are supported by the support wall 9c, and the support shafts 8c and 8d are supported by the support wall 9d.

The first brake assist arm 11 located on the reciprocating side of the rotor 3 in the rotation direction (the direction of the arrow (a)) when the vehicle moves forward has a leading end of the guide portion 1 of the pressure plate 14.
The springs 25a, 25a,
Engaging in the clockwise direction (arrow (b) direction) in FIG. 1 by 25b and engaging with stopper pins 27a and 27b on the base end side that restrict rotation by the urging of the springs 25a and 25b. Parts 11a and 11b are formed. Rotor 3
Second brake assist arm 12 located on the rotation direction outgoing side of
The springs 29a and 29b are arranged so that the state in which the tip abuts on the guide portion 14c of the pressure plate 14 is maintained.
As a result, the spring is biased in the counterclockwise direction (the direction of the arrow (c)) in FIG. Parts 12a and 12b are formed.

At the distal end of the first brake assist arm 11, when the vehicle is braked forward, when the brake shoe 5 is rotated counterclockwise in FIG.
The brake shoe pressing portion 11c that presses against a is integrally formed. At the distal end side of the second brake assist arm 12, the brake shoe 5 is moved to the braking surface 3a when rotating clockwise in FIG.
The brake shoe pressing portion 12c that presses the brake shoe is integrally formed.

The brake shoe drive mechanism 7 has an eccentric cam 7a which is rotated by a braking operation. The eccentric cam 7a is mounted on the bracket 9 so that the eccentric cam 7a frictionally engages (contacts) with the lining support portion 14a of the pressure plate 14.
In accordance with the amount of rotation, the lining support portion 14a is pushed toward the braking surface 3a, and the brake linings 15, 16 are pressed against the braking surface 3a in accordance with the amount of rotation, as shown by an arrow (d) in FIG. I do.

In the brake device 1 described above, for example, during forward braking, when a circumferential force F of the rotor 3 acts on the brake shoe 5 from the rotor 3 to be braked, the pressure plate 14 Guide part 14b
The first brake assist arm 11 that is in contact with the
3 and is rotated counterclockwise in FIG. 3, whereby the brake shoe pressing portion 11c presses the brake shoe 5 against the braking surface 3a of the rotor 3 to increase the frictional force on the braking surface 3a. . This brake shoe pressing portion 1
The increase in the frictional force by 1c produces a servo effect of increasing the braking torque, so that the effectiveness of the brake is improved. Therefore, a large braking force can be obtained with a small brake input. The friction force between the eccentric cam 7a and the pressure plate 14 causes the pressure plate 1
4 serves to rotate the eccentric cam 7a clockwise with the movement to the left in FIG. Therefore, the braking torque is further increased. At the time of reverse braking, similarly, the second brake assist arm 12 which is in contact with the guide portion 14c of the pressure plate 14 is pushed by the guide portion 14c and rotated clockwise in FIG. The shoe pressing portion 12c moves the brake shoe 5 to the braking surface 3 of the rotor 3.
a to increase the frictional force on the braking surface 3a,
Causes a servo effect.

Since the braking surface 3a is set on the outer periphery of the rotor 3, and the braking surface 3a is exposed to the outside like a rotor in a general disk brake device, the heat radiation is excellent and the braking surface 3a is provided with water. Is less likely to remain, and the occurrence of a fade phenomenon that reduces the effectiveness of the brake can also be prevented. Therefore, a large braking force can be obtained with a small brake input while stabilizing the braking effect, and the device can be easily reduced in size and weight.

Further, when the brake shoe driving mechanism 7 has the eccentric cam 7a that frictionally engages with the brake shoe 5 as in the above embodiment, the structure is simple.
The brake shoe 5 can be pressed against the braking surface 3a of the rotor 3, and the configuration of the brake shoe drive mechanism 7 can be simplified.

4 to 6 show a second embodiment of the brake device according to the present invention. FIG. 4 is a front view of a main part of the brake device according to the present invention, and FIG. Arrow view,
FIG. 6 is a sectional view taken along the line DD of FIG.

The brake device 35 is the same as the brake device 1 of the first embodiment except that the brake assist lever 37 is added to the brake device 1 of the first embodiment. It is. Therefore, the same components as those of the first embodiment are denoted by the same reference numerals, and description thereof is omitted. The brake assist lever 37 includes an intermediate portion 40 pivotally supported by a pin 39 on a brake shoe pressing portion 12c of the second brake assist arm 12 disposed on the rotation direction (direction of the arrow (a)) of the rotor 3. When the brake shoe 5 is moved in the rotor rotation direction by a rotor circumferential direction force F acting on the brake shoe 5 from the rotor 3 during forward braking, the brake shoe 5 contacts the projection 14d formed on the pressure plate 14 and acts on the brake shoe 5. A first end portion 41 that receives a circumferential force, and the first end portion 41 receives a circumferential force to swing the brake assist lever 37 to thereby move the brake lining 16 on the outgoing side of the brake shoe 5 to the braking surface. The second end portion 42 pressed against 3a is integrally formed.

The brake device 3 according to the second embodiment described above.
In No. 5, the pressing force of the brake shoe 5 on the rotor 3 is increased by the brake assist lever 37 even on the circulation side during forward braking, so that the pressing force of the brake shoe 5 on the rotor 3 can be made more uniform. .

In the above-described embodiment, the brake assist lever is provided only on the second brake assist arm 12 on the rotation direction outgoing side of the rotor 3. However, the first braking assist on the rotation direction inflow side of the rotor 3 is provided. The arm 11 may also be provided with a brake assist lever.

In each of the above-described embodiments, the eccentric cam 7a is used as the brake shoe driving mechanism 7 for pressing the brake shoe 5 against the braking surface 3a in response to the braking operation. The configuration is not limited to the above embodiment. Various known mechanisms are available.

The brake device of the present invention can be used not only for vehicles but also for various industrial machines.
Needless to say.

[0027]

According to the brake device of the present invention, when a force F in the circumferential direction of the braked member acts on the brake shoe from the braked member during braking, the brake shoe of the brake assist arm is actuated in accordance with the force F. The pressing portion presses the brake shoe against the braking surface of the member to be braked, and the friction force on the braking surface increases. The increase in the frictional force by the brake shoe pressing portion produces a servo effect of increasing the braking torque, so that the effectiveness of the brake is improved. Therefore, a large braking force can be obtained with a small brake input. Further, although it has a servo effect, it does not become as large as that of a so-called duo-servo type drum brake device, so that the fluctuation of the braking effect due to the fluctuation of the friction coefficient between the braking surface and the brake shoe can be reduced. In addition, since the braking surface is set on the outer periphery of the member to be braked, and the braking surface is exposed to the outside like a rotor of a disc brake device, the heat radiation is excellent and water hardly remains on the braking surface, so that the braking It is also possible to prevent the occurrence of a fade phenomenon that lowers the effect. Therefore, while stabilizing the braking effect,
A large braking force can be obtained with a small brake input, and a brake device suitable for reducing the size and weight of the device can be provided.

Further, if the brake assist lever is provided as the structure according to the second aspect, the pressing force of the brake shoe against the member to be braked is increased on the outgoing side by the brake assist lever. Can be further uniformized.

Further, according to the third aspect of the present invention, the brake shoe can be pressed against the braking surface of the member to be braked with a simple configuration, and at the same time, the movement of the brake shoe during braking is caused by the rotation of the eccentric cam. , Thereby producing a servo effect that further increases the braking torque.

[Brief description of the drawings]

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

FIG. 2 is a view taken in the direction of arrow A in FIG. 1;

FIG. 3 is a sectional view taken along line BB of FIG. 2;

FIG. 4 is a front view of a main part of a brake device according to a second embodiment of the present invention.

FIG. 5 is a view as viewed in the direction of arrow C in FIG. 4;

FIG. 6 is a sectional view taken along line DD of FIG. 5;

[Explanation of symbols]

 Reference Signs List 1 brake device 3 rotor (member to be braked) 3a braking surface 5 brake shoe 7 brake shoe driving mechanism 7a eccentric cam 8 support shaft 9 non-rotating body (bracket) 11, 12 brake assist arm 11a, 11b, 12a, 12b engaging portion 11c, 12c Brake shoe pressing portion 14 Pressure plate 14a Lining support portion 14b, 14c Guide portion 15, 16 Brake lining 18 Structure 21 Mounting member 22 Guide shaft 23 Return spring 25 Spring 27 Stopper pin 29 Spring 31 Stopper pin 35 Brake device 37 brake assist lever 40 middle part 41 first end part 42 second end part

Claims (3)

[Claims] 1. A brake shoe disposed opposite a braking surface formed on an outer periphery of a member to be braked, and a brake shoe drive for generating a braking force by pressing the brake shoe against the braking surface in response to a braking operation. A brake assist arm that has a base end pivotally supported by the non-rotating body and a distal end operatively engaged with the brake shoe and swings by a circumferential force acting on the brake shoe during braking. A brake device, comprising: a brake shoe pressing portion that presses the brake shoe against a braking surface by the swing of the brake auxiliary arm at a tip of the brake auxiliary arm. 2. The brake device according to claim 1, wherein the brake assist arms are respectively provided at positions spaced apart in a circumferential direction of the member to be braked, and a brake is located on a rotation side of the member to be braked in a rotation direction. A brake assist lever having an intermediate portion pivotally supported at a tip of the assist arm, wherein the brake assist lever is operatively engaged with a brake shoe to receive a circumferential force acting on the brake shoe during braking; A brake, comprising: an end portion; and a second end portion that presses a revolving side of the brake shoe against a braking surface when the first end portion receives a circumferential force and the brake assist lever swings. apparatus. 3. The brake device according to claim 1, wherein the brake shoe driving mechanism has an eccentric cam that frictionally engages with a brake shoe.