JPH09189337A - Mechanical disc brake for parking - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a servo mechanism for a parking brake to do servo work equally in the forwarding direction and in the backward direction of a vehicle by using the servo work for the parking brake. SOLUTION: This mechanical disc brake is constituted to hold a brake pad 7 at a neutral position in the longitudinal direction by return springs 22, 22 and to increase braking force by turning a pressure member 2 in the same direction by movement at the time when the brake pad 7 moves forward and backward against the return springs 22, 22 by providing a pair of upper and lower unidirectional drive mechanisms 23a, 23b between the pressure member 2 and the brake pad 7 to be pressurized by the pressure member 2, supporting the brake pad 7 by a caliper 3 free to move in the longitudinal direction of a vehicle against the caliper 3 and interposing the return springs 22, 22 between the brake pad 7 and its holding member.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mechanically operated parking brake of an automobile, that is, a mechanical disc brake. By utilizing a servo action for the parking brake operated by an air actuator. A large braking force can be obtained even if the operating force of the air actuator is reduced, and it is particularly effective when used for a parking brake of a large truck.

[0002]

2. Description of the Related Art There are various types of mechanical disc brake operating mechanisms for automobiles, but in order to make the actuator necessary for obtaining a predetermined brake operating force as small as possible, a boosting mechanism using a rotating cam disk is used. There are some that use. As an example thereof, a vehicle disk brake device disclosed in Japanese Patent Publication No. 52-1056 will be described with reference to FIG. Pressure unit 2'integrated with the operating shaft 1
A plurality of circumferential cam grooves 4 and 5 are provided on the surfaces facing each other and the plate 3a ', and wedge balls 6 are interposed in the cam grooves. 4,5
The pressing portion 2'is pushed out by the cam action of the wedge ball 6 and the brake disc 7 is clamped by the brake pads 7 and 8 to brake it.

[0003]

In such a disc brake, when an air actuator is connected to the lever 10 at the outer end of the operating shaft 1 and operated by this air actuator, the braking force of the disc brake is operated by the air actuator. Because it depends on the force, the cam groove 4,
In order to increase the pressure applied to the brake pad by the boosting mechanism constituted by 5 and the wedge ball 6, the air pressure of the air actuator may be increased or the air actuator may be enlarged to increase its output. . Since it is not realistic to increase the current working air pressure in order to increase the output of the air actuator, it is impossible to increase the size of the air actuator. Increasing the size of the air actuator is against the demand to promote the weight reduction of each automobile part as much as possible. Therefore, in order to increase the braking force, there is no choice but to increase the size of the air actuator, or it is not possible to meet the request to reduce the size of the air actuator and reduce the weight as much as possible. That is, the braking force depends on the operating force of the air actuator.
The servo effect is most effective for downsizing the air actuator without increasing the air pressure of the air actuator. However, in order to utilize the servo action for the parking disc brake, it is an essential requirement that the servo mechanism produces a predetermined servo action in the forward direction and the reverse direction of the vehicle. However, such a servo mechanism is not yet known. An object of the present invention is to utilize a servo action for a parking brake, and an object thereof is to devise a parking brake servo mechanism that exerts a servo action equally in a forward direction and a reverse direction of a vehicle.

[0004]

[Means for Solving the Problems] The measures taken for solving the above problems are constituted by the following elements (a) to (c). (A) A pair of upper and lower unidirectional drive mechanisms is provided between the pressure member and the brake pad pressed by the pressure member, and (b) the brake pad is moved in the front-rear direction of the vehicle with respect to the caliper. Having calipers support as much as possible,
(C) A return spring is interposed between the brake pad and its holding member, and the brake pad is held at the neutral position in the front-rear direction by the return spring.

[0005]

[Operation] When the vehicle moves forward with the brake pad pressed against the brake disc and the brake disc rotates in the forward direction, the brake pad is dragged by this rotation and resists the return spring, Move forward of the vehicle with respect to the caliper. This forward movement of the brake pad causes the upper one-way drive mechanism to rotate the pressurizing member in the same direction as the drive direction of the operation shaft, and this rotation activates the booster mechanism of the wedge ball and the cam groove. The pressing member is further strongly pushed to increase the pressing force of the pressing member. This pressing force increases as the brake disc rotates. When the vehicle moves backward and the brake disc rotates in the reverse direction, the brake pad is dragged by this rotation and moves rearward of the vehicle with respect to the caliper against the return spring. By this backward movement of the brake pad, the pressing member is rotated in the same direction as the driving direction by the operation shaft by the downward one-way driving mechanism, and this rotation activates the boosting mechanism by the wedge ball and the cam groove. The pressing member is further strongly pushed to increase the pressing force of the pressing member. The increase in the braking force due to the servo action increases as the brake disc rotates in the forward and reverse directions, so that the brake disc is strongly braked. When the operating shaft is operated in the opposite direction to release the parking brake and the brake pad is separated from the brake disc, the drag force of the brake disc on the brake pad is reduced, and the brake pad is returned to the neutral position by the return spring. Therefore,
The operating force of the parking brake is sufficient to drag the break hex pad by the above-mentioned brake disc, and therefore the braking operating force can be reduced,
The air actuator for that purpose can be made as small as possible.

[0006]

[Examples] Next, examples will be described. The basic structure of the embodiment is as shown in FIG. 1, and a plurality of pressure members 2 spline-fitted to an operating shaft 1 that is rotationally driven by an air actuator and a plurality of facing surfaces of a bottom surface 3a of the cylinder are provided. The cam grooves 4 and 5 are provided in the circumferential direction, and the wedge balls 6 are interposed in the cam grooves (power boosting mechanism). The pressurizing member 2 is rotated to form the cam grooves 4 and 5 and the wedge balls 6. The pressing member 2 is pushed out by the cam action (the action of the boosting mechanism), and the brake discs 9 are clamped by the brake pads 7 and 8 to brake them. The piston rod of the air actuator is directly or indirectly connected to the lever 10 at the outer end of the operation shaft 1 and is operated by the air actuator. In the brake hake pad 7 which is in contact with the pressing member 2 of this thing, the long holes 20, 20 which are long in the front-rear direction of the vehicle
Therefore, the support pins 21 and 21 laid over the openings of the caliper 3 are fitted into the elongated holes 20 and 20, respectively. This allows the brake pad 7 to be dragged by the brake disc 9 and slide in the same direction during braking, but is normally held in the neutral position by the return spring 22 provided on the support surface of the holding member of the brake pad. . Further, a pair of upper and lower pins 23a, 23 are provided on the back surface of the brake pad 7 (the surface contacting the end surface of the pressing member 2).
b is projected. On the other hand, a pair of upper and lower cutouts 24a and 24b are provided on the end surface of the pressure member 2, and these cutouts are located in front of the rotation direction of the pressure member 2 (the rotation direction in which the operation shaft 1 is rotated). Vertical walls 25a, 25b
And an L-shaped notch formed by the lateral walls 26a and 26b. When the brake pad 7 is assembled to the pressure member 2, the upper and lower pins 23a and 23b of the brake pad 7 are fitted into the upper and lower cutouts 24a and 24b of the pressure member 2, respectively. At this time, the brake pad 7 is held at the neutral position (intermediate position in the front-rear direction) by the return springs (return springs) 22, 22, and the pin 23a above the back surface of the brake pad 7 is formed in the notch 24a of the pressing member. Vertical wall 25
The lower pin 23b is in contact with the vertical wall 25b of the notch 24b of the pressing member. Pin 23a,
23b and the notches 24a and 24b having the vertical walls form a pair of upper and lower unidirectional drive mechanisms. When the brake disc 7 rotates in the forward direction (forward direction of the vehicle) while the brake pad 7 is pressed against the brake disc 9, if the brake pad 7 returns, it is dragged forward by the brake disc 9 against 22. The upper pin 23a on the back surface of the brake pad 7 pushes the vertical wall 25a of the notch 24a of the pressure member 2 to move the pressure member 2 in the forward direction (arrow R direction, the pressure member 2 is rotated by the operation shaft 1). Driven in the same direction as the operated direction), the cam action of the cam grooves 4, 5 and the wedge ball 6 strongly pushes out the pressing member 2 to further increase the braking force of the brake. When the brake disc 9 rotates in the reverse direction (the reverse direction of the vehicle), the brake pad 7 is dragged rearward by the brake disc 9, and the pin 23b below the back surface of the brake pad 7 causes the notch of the pressing member 2 to be cut out. 24b longitudinal wall 25
By pushing in b, the pressure member 2 is driven in the same direction (the direction of arrow R), and the cam action of the cam grooves 4, 5 and the wedge ball 6 strongly pushes out the pressure member 2 to further increase the braking force of the brake. One of the upper and lower pins 23a, 23b, for example pin 2
When 3a pushes the vertical wall 25a of the cutout 24a, the other pin 23b also moves in the same direction, but the other pin 23b must move rearward along the lateral wall 26b of the cutout 24b. Therefore, it does not hinder the rotation of the pressing member 2 in the arrow R direction. The same applies when the pin 23b pushes the vertical wall 25b of the cutout 24b. In this way, even if the brake pad 7 is dragged forward or backward by the brake disc 9, the pressing member 2 is driven in the same direction (arrow R direction) by either of the pins 23a and 23b. Therefore, regardless of whether the brake disc 9 rotates in the forward direction or the reverse direction, the servo action is generated and the braking force can be further increased. Pins 23a, 23
The notches 24a, 24b with which b is engaged are different from the vertical walls 25a, 25b and the lateral walls 2 because the pressure member 2 has a relatively small diameter in a mechanical disc brake of a normal vehicle.
Although the L-shaped notches 24a and 24b are formed by 6a and 26b, they may be elongated holes in the lateral direction. Pins 23a, 23b
When the pressurizing member 2 is driven and rotated by the pin, the pin also moves slightly in the radial direction with respect to the notch. Therefore, when the notch is a lateral slot, the width of the lateral slot should be the same as that of the pin. It should be slightly larger than the diameter. Pin 2 above
The pair of upper and lower unidirectional drive mechanisms 3a and the notch 24a, and the pin 23b and the notch 24b select the movement of the brake pad in the forward and backward directions by selecting the vertical wall of the upper and lower notches with the upper and lower pins. It is a transmission mechanism that pushes it into the rotary motion of the pressure member and transmits it to the pressure member.However, a cutout is provided in the brake pad and a pin is projected on the end face of the pressure member. The same effect will be obtained if the pin is pushed by the notch vertical wall. And when making the notch a horizontal slot, a horizontal slot is provided in a separate plate,
This may be fixed to the back surface of the brake pad 7. Further, the up and down one-way drive mechanism is a mechanism that selectively transmits the forward and backward movements of the brake pad as a rotational movement to the pressing member, and thus may be configured by a rack and pinion mechanism. In this case, a pair of upper and lower rack gears (see FIGS. 6 to 8) 6 are provided on the back surface of the brake pad 7.
1, 62 (upper rack gear is downward, lower rack gear is upward), and two pinions 63 and 64 that mesh with the rack gears 61 and 62 are provided concentrically on the pressing member 2 so that the operating directions are the same. One-way clutch 65, 66
Is interposed between the pressure member 2 and the pinions 63 and 64. When the brake pad moves in the forward direction of the vehicle, the upper and lower rack gears 61, 62 cause the pinions 63, 64 to move.
Are driven in opposite directions, but the pressure member 2 is driven forward (in the direction of arrow R) by the pinion 63 meshing with the upper rack gear 61 via the one-way clutch 65. At this time, the pinion 64 meshing with the lower rack gear 62 rotates in the opposite direction, so that the one-way clutch 66 becomes free, and the pinion 64 rotates freely with respect to the pressing member 2. When the brake pad moves in the reverse direction of the vehicle, the pressure member 2 is driven forward (in the direction of arrow R) by the pinion 64 meshing with the lower rack gear 62 via the one-way clutch 66. At this time, the one-way clutch 65 of the pinion 63 meshing with the upper rack gear 61 is free to rotate with respect to the pressing member 2. in this way,
The pressing member 2 is driven by the rack and pinion mechanism in the same direction (direction of arrow R) regardless of whether the brake pad is pulled in the forward direction or the backward direction by the brake disc. However, the rack and pinion mechanism is more complicated than the pin and notch mechanism, and therefore the pin and notch mechanism is preferable in terms of practicality.

[0007]

[Effect] The invention that solves the above problems is not yet known. Therefore, solving this problem and solving the above-mentioned problems in the prior art is the effect peculiar to the present invention. In other words, when the braking force is applied, the brake pad is dragged by the brake disc, and the braking force can be remarkably increased by the servo action using this dragging force. Can be braked. Therefore, the output of the actuator for rotating the operation shaft can be reduced (smaller and lighter). Further, when the output of the actuator is reduced, the force applied to the rotary operation shaft 1 and the lever 10 is also reduced, so that these can also be made smaller and lighter, and the manufacturing cost can be reduced. . Further, since the actuator can be downsized, the space occupied by the actuator can be reduced, and its arrangement can be facilitated. This effect is remarkable in the case where the air actuator occupies a very large space such as an ultra-large truck. When the present invention is applied to a parking brake operated by a manual lever, the manual operation force can be reduced, which facilitates the operation. In addition, a parking brake operation mechanism for a relatively small truck that has conventionally used an air actuator can be provided. It can also be changed to manual operation.

[Brief description of the drawings]

FIG. 1 is a sectional view of an example.

FIG. 2 is a view taken on line AA of FIG. 1;

3A is a cross-sectional view of the pressing member, FIG. 3-3 is a front view of the pressing member, and FIG. 3C is a rear view of the pressing member.

FIG. 4 is a front view of a caliper cover;
-2) is a BB sectional view in (4-1).

FIG. 5A is a front view of a brake pad, and FIG.
2) is a cross-sectional view taken along the line CC in (5-1).

FIG. 6 is a sectional view of another embodiment.

FIG.

8 is a cross-sectional view showing the relationship between the rack gear, the pinion, and the one-way clutch shown in FIG.

FIG. 9 is a sectional view of a conventional disc brake.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Operation shaft 2 ... Pressurizing member 2 '... Pressurizing part 3 ... Caliper 3a ... Bottom surface of cylinder 3a' ... Plate 4, 5 ... Cam groove 6 ...・ Wedge ball 7, 8 ... Brake pad 9 ... Brake disc 10 ... Lever 20 ... Long hole 21 ... Support pin 22 ... Return spring (return spring) 23a, 23b ... Pins 24a, 24b ... Notches 25a, 25b ... Vertical walls 26a, 26b ... Lateral walls 61, 62 ... Rack gears 63, 64 ... Pinion 65, 66 ... One-way clutch

Claims (2)

[Claims] 1. A booster mechanism including a cam groove and a wedge ball is interposed between the back surface of a cylindrical pressure member fitted in a cylinder of a caliper and the bottom surface of the cylinder of the caliper, and the pressure member is In a parking mechanical disc brake that brakes a brake disc by rotating it and advancing by the booster mechanism, a pair of upper and lower one direction is provided between the pressing member and a brake pad pressed by the pressing member. A driving mechanism is provided, the brake pad is supported by the caliper so as to be movable in the front-rear direction of the vehicle, and a return spring is interposed between the brake pad and its holding member, and the brake pad is operated by the return spring. Is held at the neutral position in the front-rear direction, and when the brake pad moves forward and backward against the return spring, A mechanical disc brake for parking in which the pressing member is rotated in the same direction by the movement of the wheel to increase the braking force. 2. A pin projecting from the pressure member or a brake pad pressed by the pressure member, and a vertical wall provided on the brake pad pressed by the pressure member or the pressure member. The mechanical disc brake for parking according to claim 1, wherein the one-way drive mechanism is constituted by a notch.