JP2002039237A - Drum brake device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a brake device to prevent the occurrence of stick slip phenomenon between a brake shoe and a brake drum even when a wheel cylinder pressure is increased during a stop. SOLUTION: A movement regulating means 15 is provided to limit an amount of movement of the brake shoe 5 to the anchor part 9 side when, during a stop, the brake shoe 5 is brought into a state to be pressed in surplus against the brake drum 4 along with the increase of a pressure fed to a wheel cylinder 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a drum brake device for a vehicle.

[0002]

2. Description of the Related Art For example, Japanese Utility Model Laid-Open No. 4-66431 discloses this type of prior art. In the drum brake device described in this publication, one end of each of a pair of brake shoes abuts on an anchor provided on a back plate, and the other end faces the anchor on the back plate. The brake shoe is connected to a piston of a wheel cylinder disposed on the side, and at the time of operation, the pair of brake shoes are pushed apart by the piston in a direction away from each other with a contact portion with the anchor portion as a fulcrum, It is pressed against the rotating brake drum to obtain braking force.

[0003]

In this conventional drum brake device, when the wheel cylinder pressure is increased when the vehicle stops, an abnormal noise (so-called brake squeal) may be generated. When the wheel cylinder pressure is increased when the vehicle stops, when the driver depresses the brake pedal excessively, the supply pressure from the master cylinder increases. In addition, an electronically controlled brake distribution device is provided which includes a drum brake device having a wheel cylinder at least on the rear wheel side, and a hydraulic pressure supplied to the wheel cylinder is reduced in proportion to a hydraulic pressure supplied from a master cylinder. When the vehicle is stopped, the pressure reduction control ends when the vehicle stops, the hydraulic pressure supplied to the wheel cylinder becomes the same as the hydraulic pressure of the master cylinder, and the driver depresses the brake pedal with the same force as before stopping. In the case of continuing, the hydraulic pressure of the rear wheel cylinder is increased immediately after the end of the pressure reduction control when the vehicle is stopped. In this way, when the wheel cylinder pressure is increased in a stopped state, the wheel cylinder side portion of the brake shoe is excessively pressed against the stationary brake drum, causing local deformation of the brake shoe, In addition, the lining characteristics of the brake shoes have changed due to the temperature rise associated with the operation of the brakes until the vehicle stopped, so that a stick-slip (intermittent slippage between contact and non-contact) between the brake drum and the brake shoes occurred. Exercise), and the inventors have found that this stick-slip causes brake squeal. It is necessary to prevent the brake squeal at the time of stoppage from occurring in terms of quietness and comfort, similarly to the squeal (abnormal noise) generated when the brake is applied during running of the vehicle.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above-described problems, and provides a drum brake device that prevents a stick-slip phenomenon from occurring between a brake shoe and a brake drum even when a wheel cylinder pressure is increased when the vehicle is stopped. As an issue.

[0005]

In order to solve the above-mentioned problems, in the drum brake device of the present invention, when the vehicle is stopped, the brake shoes are excessively pressed against the brake drum as the supply pressure to the wheel cylinder increases. A movement restricting means is provided for restricting the amount of movement of the brake shoe toward the anchor when the state is reached.

That is, when the vehicle is stopped, the wheel cylinder pressure is increased, and even if the brake shoe is excessively pressed against the brake drum so as to cause stick-slip, the brake shoe moves toward the anchor portion. The amount of movement is restricted by movement restriction means (movement that causes stick-slip is not allowed).

[0007]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a drum brake device 1 according to a first embodiment of the present invention, which is an LT type (leading trailing type) drum brake device.

An anchor portion 9 is fixed to an outer peripheral portion of a disc-shaped back plate 6 fixed to a non-rotating portion of the vehicle, with respect to a lower portion in a vertical diameter direction. The anchor portion 9 is fixed to the back plate 6 with two pins 14, 14 via a plate member 10.

The wheel cylinder 2 is fixed to the outer peripheral side of the back plate 6 at a position facing the anchor portion 9 with respect to the center of the back plate 6 in the vertical diametric direction. The wheel cylinder 2 includes two pistons that operate in the leftward and rightward directions in FIG. 1 by external pressure supply.

A pair of arcuate brake shoes 5, 12 are bridged between the anchor portion 6 and the wheel cylinder 2 along the outer periphery of the back plate 6. FIG. 2 shows FIG.
The anchor part 9 with the plate member 10 removed
Although an enlarged view of the vicinity is shown, assuming that a line connecting the center of the back plate 6 and the center of the anchor portion 9 is a virtual line C, one end 5a, 12a of each of the brake shoes 5, 12 is positioned with respect to the virtual line C. At a position shifted in the circumferential direction of the back plate 6, the back plate 6 is in contact with the end face of the anchor portion 9 with the anchor portion 9 interposed therebetween. The other ends 5b and 12b are engaged with both pistons of the wheel cylinder 2, respectively.

In FIG. 1, the brake drum 4 at the time of forward movement is shown.
Is the arrow A, the brake shoe 5 is the trailing brake shoe, and the brake shoe 12 is the leading brake shoe.

The brake shoes 5 and 12 are respectively provided with webs 5c and 12c, rims 5d and 12d, and rims 5d and 1d.
It consists of linings 5e and 12e attached to 2d. A return spring 13 is provided at the other end of the webs 5c and 12c.
Are engaged with each other, and both ends of the return spring 11 are engaged with one end thereof.
13, the brake shoes 5, 12 are urged in the direction of approaching each other. A strut 3 with a known automatic adjustment mechanism is disposed between the brake shoes 5 and 12.

As shown in FIGS. 1 and 2, near the anchor portion 9 of the brake shoe 5 on the trailing side,
A through hole 7 penetrating in the axial direction of the back plate 6 is formed, and a pin member 8 fixed to the back plate 6 has a gap in the through hole 7 with respect to an inner peripheral wall of the through hole 7. Mated. The through hole 7 and the pin member 8 constitute the movement restricting means 15 in the present embodiment.

Drum brake device 1 according to the present embodiment
Is configured as described above, and its operation will be described below.

When the driver depresses the brake pedal while the vehicle is running, a hydraulic pressure is generated in a master cylinder (not shown), and this hydraulic pressure is supplied to the wheel cylinder 2 so that both internal pistons move leftward in FIG. , Move to the right. As a result, the brake shoes 5, 12 are each pushed and spread in directions opposite to each other with the contact surface with the anchor portion 9 as a fulcrum, and the linings 5e, 12e are provided on the inner peripheral surface of the brake drum 4 rotating together with the wheels. Press to brake the wheels.

When the vehicle is stopped, an increase in wheel cylinder pressure due to excessive braking operation by the driver or a drum brake device having a wheel cylinder at least on the rear wheel side is provided. When a portion of the brake shoe 5 on the wheel cylinder 2 side is excessively pressed against the stationary brake drum 4 due to an increase in rear wheel cylinder pressure in a vehicle equipped with a force distribution device. The movement of the brake shoe 5 toward the anchor portion 9 (downward in the figure) is restricted by the inner peripheral wall of the through hole 7 formed in the brake shoe 5 hitting the pin member 8 fixed to the back plate 6. Therefore, the occurrence of stick-slip between the brake drum 4 and the brake shoe 5 can be prevented. It is possible to prevent the occurrence of brake noise to cause. The reason why the gap is formed between the pin member 8 and the inner peripheral wall of the through-hole 7 is to prevent the rotation of the brake shoe 5 about the anchor portion 9 as a fulcrum. However, the brake shoe 5 moves downward, but does not move as much as to cause stick-slip.

FIG. 3 shows a movement restricting means 16 according to a second embodiment of the present invention. The tangent line B of the contact surface between the brake shoe 5 on the trailing side and the anchor portion 9 and the above-mentioned imaginary line C intersect in the central region of the back plate 6 so that the angle on the acute angle side is 20 degrees. The movement restricting means 16 is formed by inclining the contact surface between the brake shoe 5 on the trailing side and the anchor portion 9. The configuration other than the portion shown in FIG. 3 is the same as that of the first embodiment shown in FIG. 1, and the operation is the same.

Also in this embodiment, the downward movement of the brake shoe 5 is performed by the brake shoe 5 and the anchor portion 9.
The contact surface is limited by tilting the contact surface, thereby preventing the occurrence of stick-slip and the occurrence of brake squeal due to the stick-slip. Strictly speaking, the brake shoe 5 moves down slightly, but not so much as to cause stick-slip. Although a good result was obtained in the test in which the inclination angle was 20 degrees,
A similar effect can be obtained within a range of 30 degrees. If the angle is smaller than 10 degrees, the downward movement of the brake shoe 5 cannot be regulated, and if the angle of inclination is larger than 30 degrees, the rotation of the brake shoe 5 about the anchor portion 9 as a fulcrum will be hindered.

FIG. 4 shows a movement restricting means 17 according to a third embodiment of the present invention. The movement restricting means 17 is provided with a concave portion 17a on an end surface of the anchor portion 9 extending parallel to the imaginary line C, and a convex portion 17b on one end surface of the brake shoe 5 on the trailing side which is opposed to the end surface of the anchor portion 9. ,
It is constituted by fitting these concave portions 17a and convex portions 17b with each other. The configuration other than the portion shown in FIG. 4 is the same as that of the first embodiment shown in FIG. 1, and the operation is the same.

In the present embodiment, the brake shoe 5
The downward movement is restricted by the convex portion 17b formed on the contact surface with the anchor portion 9 being fitted into the concave portion 17a of the anchor portion 9, and the occurrence of stick-slip and the brake caused by this are caused. The occurrence of squeal can be prevented. In addition, the concave portion 17a formed so as not to hinder the rotation of the brake shoe 5 about the anchor portion 9 as a fulcrum.
The brake shoe 5 is lowered downward by an amount corresponding to the gap between the brake shoe 5 and the convex portion 17b, but the movement amount is not large enough to cause stick-slip.

FIG. 5 shows a movement restricting means 18 according to a fourth embodiment of the present invention. Contrary to the above-mentioned third embodiment, the movement restricting means 18 is convex on the end face of the anchor portion 9 extending parallel to the imaginary line C. A portion 18a is provided, and a concave portion 18 is formed in one end surface of the brake shoe 5 on the trailing side, which is in contact with the end surface of the anchor portion 9.
b, the concave portion 18b and the convex portion 18a are fitted to each other to form the movement restricting means 18. The configuration other than that shown in FIG. 5 is the same as that of the first embodiment shown in FIG. 1, and the operation is the same.

In the present embodiment, the brake shoe 5
Since the concave portion 18b formed on the contact surface with the anchor portion 9 is fitted to the convex portion 18a of the anchor portion 9, the downward movement is restricted, and the occurrence of stick-slip and the brake caused by this are caused. The occurrence of squeal can be prevented. A concave portion 18b formed so as not to hinder the rotation of the brake shoe 5 about the anchor portion 9 as a fulcrum.
The brake shoe 5 is lowered downward by an amount corresponding to the gap between the protrusions 18a and the protrusions 18a, but the amount of movement is not large enough to cause stick-slip.

FIG. 6 shows a movement restricting means 19 according to a fifth embodiment of the present invention. The movement restricting means 19 includes a pair of recesses 1 formed in the end face of the anchor portion 9 extending in parallel with the imaginary line C and one end face of the brake shoe 5 on the trailing side in contact with the end face with openings facing each other.
9a, 19b and a fitting member (pin member) 1 fitted in a space defined by the pair of recesses 19a, 19b.
9c. The fitting member 19c is fixed to the back plate 6, and is fitted into the inner peripheral walls of the pair of recesses 19a and 19b with a gap. FIG.
Are the same as those of the first embodiment shown in FIG. 1, and the operation is the same.

In this embodiment, the brake shoe 5 is
When the concave portion 19a formed on the contact surface with the anchor portion 9 hits the fitting member 19c, the downward movement is restricted, and the occurrence of stick-slip and the occurrence of brake squeal due to this can be prevented. . A concave portion 19a and a fitting member 19c formed so as not to hinder the rotation of the brake shoe 5 about the anchor portion 9 as a fulcrum.
The brake shoe 5 is lowered downward by an amount corresponding to the gap therebetween, but the amount of movement is not large enough to cause stick-slip.

In each of the above embodiments, the movement restricting means is disposed near the anchor side. Since the anchor portion is a fulcrum at the time of operation of the drum brake device, the movement effective means of the brake shoe can be reduced by arranging and operating the movement restricting means in the vicinity thereof.

In each of the above embodiments, only the brake shoes 5 on the trailing side are provided with the movement restricting means. This is because the leading side brake shoe 12 tends to bite into the rotating drum 4, and the work ratio at the time of braking is larger than that of the trailing side due to the self-servo action, and the contribution to the braking force is large. This is because it is desired that the self-servo operation is not restricted by the movement restricting means.

[0028]

According to the drum brake device of the present invention,
When the vehicle is stopped, noise (brake squeal) caused by stick-slip can be prevented, and quietness and comfort can be improved.

[Brief description of the drawings]

FIG. 1 is an overall view of a drum brake device according to a first embodiment of the present invention.

FIG. 2 is an enlarged view of the main part.

FIG. 3 is an enlarged view of a main part of a drum brake device according to a second embodiment of the present invention.

FIG. 4 is an enlarged view of a main part of a drum brake device according to a third embodiment of the present invention.

FIG. 5 is an enlarged view of a main part of a drum brake device according to a fourth embodiment of the present invention.

FIG. 6 is an enlarged view of a main part of a drum brake device according to a fifth embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Drum brake device 2 Wheel cylinder 4 Brake drum 5 Brake shoe 6 Back plate 7 Through hole 8 Pin member 9 Anchor part 12 Brake shoe 15 Movement restriction unit 16 Movement restriction unit 17 Movement restriction unit 18 Movement restriction unit 19 Movement restriction unit C virtual line

Claims (7)

[Claims] 1. A disc-shaped back plate fixed to a non-rotating portion of a vehicle, an anchor fixed to an outer peripheral side of the back plate, and opposed to the anchor with a center of the back plate as a boundary. A wheel cylinder fixed to the outer peripheral side of the position and operated by external pressure supply, and is bridged between the anchor portion and the wheel cylinder along the outer periphery of the back plate, according to the operation of the wheel cylinder. A brake shoe pressed against the inner peripheral surface of a brake drum that rotates with the wheel, and the one end of the brake shoe is attached to the back plate with respect to an imaginary line connecting the center of the back plate and the center of the anchor portion. In the drum brake device abutted on the anchor portion at a position shifted in the circumferential direction of the Along with the supply pressure increased to Linda,
A drum brake provided with a movement restricting means for restricting an amount of movement of the brake shoe toward the anchor portion when the brake shoe is excessively pressed against the brake drum. apparatus. 2. The movement restricting means includes a through hole provided near the anchor portion of the brake shoe and penetrating in the axial direction of the back plate, and a pin inserted into the through hole and fixed to the back plate. The drum brake device according to claim 1, comprising a member. 3. The drum brake device according to claim 2, wherein the pin member is fitted in the through hole while leaving a gap with respect to the inner peripheral wall of the through hole. 4. As the movement restricting means, a contact surface between the anchor portion and the brake shoe is provided so that a tangent line thereof intersects the virtual line in the center of the back plate and in the back plate. 10-30 on the acute angle side
The drum brake device according to claim 1, wherein the drum brake device is formed with a degree of inclination angle. 5. The movement restricting means includes a convex portion on one end and a concave portion on the other end surface of the anchor portion extending parallel to the imaginary line and one end surface of the brake shoe facing and in contact with the end surface. The drum brake device according to claim 1, wherein the drum brake device is provided by fitting the concave and convex portions to each other. 6. The movement restricting means includes a pair of concave portions formed with openings facing each other on an end surface of the anchor portion extending parallel to the imaginary line and on one end surface of the brake shoe opposed to the end surface. 2. The drum brake device according to claim 1, further comprising: a fitting member which is fitted into the space defined by the pair of recesses with a gap between the inner peripheral walls of the pair of recesses. 7. The drum brake device according to claim 1, wherein the drum brake device is an LT type drum brake device, and wherein the movement restricting means is provided only on a trailing side. .