JP3822664B2 - 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

[0001]
[Industrial application fields]
The present invention relates to a mechanically operated parking brake of an automobile, that is, a mechanical disc brake. The above-described parking brake operated by an air actuator uses a servo action to reduce the operating force of the air actuator. Even if it is small, a large braking force can be obtained, and it is particularly effective when used for a parking brake of a large truck.
[0002]
[Prior art]
There are various operating mechanisms for mechanical disk brakes in automobiles, but in order to make the actuators necessary for obtaining a predetermined braking operating force as small as possible, there are those that use a boosting mechanism with a rotating cam disk. is there. As an example, a vehicle disc brake device disclosed in Japanese Patent Publication No. 52-1056 will be described with reference to FIG.
A plurality of circumferential cam grooves 4 and 5 are provided on the opposing surfaces of the pressing portion 2 ′ integrated with the operation shaft 1 and the plate 3 a ′, and wedge balls 6 are interposed in the cam grooves. The pressure portion 2 ′ is rotated, the pressure portion 2 ′ is pushed out by the cam action of the cam grooves 4, 5 and the wedge ball 6, and the brake disc 9 is clamped by the brake pads 7 and 8 to brake it. is there.
[0003]
[Problems to be solved by the invention]
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 determined by the operating force by the air actuator. In order to increase the pressure applied to the brake pad by the booster mechanism constituted by the wedge ball 6 and the wedge ball 6, there is no other way than increasing the air pressure of the air actuator or increasing the output of the air actuator by increasing its size. . Since it is not practical to increase the current operating air pressure to increase the output of the air actuator, there is no choice but to make the air actuator larger. Increasing the size of the air actuator is against the request to promote weight reduction as much as possible for each part of the automobile.
Therefore, the reason for not increasing the size of the air actuator in order to increase the braking force, or not being able to meet the demand for reducing the size of the air actuator as much as possible and reducing the weight is as much as possible. That is, the braking force depends on the operating force of the air actuator. In order to reduce the size of the air actuator without increasing the air pressure of the air actuator, it is most effective to use a servo action. However, in order to use the servo action for the parking disk brake, it is an indispensable requirement that the servo mechanism generates 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 use a servo action for a parking brake, and an object of the invention is to devise a parking brake servo mechanism that performs the servo action equally in the forward and reverse directions of the vehicle.
[0004]
[Means for Solving the Problems]
The means taken to solve the above problem is that a booster mechanism comprising a cam groove and a wedge ball is interposed between the back surface of the cylindrical pressure member fitted to the caliper cylinder and the bottom surface of the caliper cylinder. The following elements (a) to (d) are provided on the premise of a parking mechanical disk brake that brakes the brake disk by rotating the pressure member and moving it forward by the booster mechanism. is there.
(A) Two unidirectional drive mechanisms for rotating the pressure member in one direction between the pressure member and the brake pad pressed by the pressure member are provided in a pair of upper and lower sides;
(B) the brake pad is supported by the caliper so as to be movable in the longitudinal direction of the vehicle with respect to the caliper;
(C) A return spring is interposed between the brake pad and the holding member, and the brake pad is held at the neutral position in the front-rear direction by the return spring;
(D) When the brake pad moves forward and backward against the return spring, one of the one-way drive mechanisms rotates the pressure member by forward movement, and The other of the one-way drive mechanism rotates the pressure member and rotates it in the same direction in both the forward and backward movements to increase the braking force.
[0005]
[Operation]
When the vehicle advances and the brake disc rotates in the forward direction while the brake pad is pressed against the brake disc and is braked, the brake pad is dragged by this rotation and resists the return spring against the caliper. Move to the front of the vehicle. The forward movement of the brake pad causes the upper unidirectional drive mechanism to rotate the pressure member in the same direction as the drive direction of the operating shaft, and this rotation activates the boost mechanism by the wedge ball and cam groove. The pressing member is pushed out more strongly to increase the pressing force by the pressing member. This pressing force increases as the brake disk rotates. When the vehicle moves backward and the brake disc rotates in the reverse direction, the brake pad is dragged by this rotation, and the brake pad moves against the caliper toward the rear of the vehicle. By the rearward movement of the brake pad, the pressing member is rotated in the same direction as the driving direction by the operating shaft by the lower one-way driving mechanism, and the boosting mechanism by the wedge ball and the cam groove is operated by this rotation. The pressing member is pushed out more strongly to increase the pressing force by the pressing member. The increase in braking force due to the servo action increases as the brake disk rotates in the forward direction and the reverse direction, so that the brake disk 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 disk, the drag force by the brake disk with respect to the brake pad is reduced, so that the brake pad is returned to the neutral position by the return spring.
Therefore, it is sufficient that the parking brake is operated by dragging the brake pad by the brake disc. Therefore, the braking operation force can be reduced, and the air actuator therefor can be made as small as possible.
[0006]
【Example】
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 the operation shaft 1 driven to rotate by an air actuator and a bottom surface 3 a of the cylinder are respectively opposed to each other. Circumferential cam grooves 4 and 5 are provided, and wedge balls 6 are interposed in the cam grooves (a boost mechanism). The pressurizing member 2 is rotated, and the cam grooves 4 and 5 and the wedge balls 6 are used. The pressurizing member 2 is pushed out by a cam action (action of a booster mechanism), and the brake disc 9 is clamped by the brake pads 7 and 8 to brake it. 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 this air actuator.
The brake pad 7 that is in contact with the pressure member 2 has long holes 20, 20 that are long in the front-rear direction of the vehicle, and the long holes 20, 20 span the opening of the caliper 3. The passed support pins 21 and 21 are respectively fitted. As a result, the brake pad 7 can be dragged and slid in the same direction by the brake disc 9 during braking, but is normally held in a neutral position by a return spring 22 provided on the support surface of the brake pad holding member. . In addition, a pair of upper and lower pins 23 a and 23 b protrude from the rear surface of the brake pad 7 (the surface in contact with the end surface of the pressure member 2). On the other hand, a pair of upper and lower notches 24a and 24b are provided on the end face of the pressure member 2, and these notches are in front of the rotation direction of the pressure member 2 (the rotation direction rotated by the operation shaft 1). It is an L-shaped notch composed of vertical walls 25a and 25b and horizontal walls 26a and 26b. When the brake pad 7 is assembled to the pressure member 2, the upper and lower pins 23a, 23b of the brake pad 7 are fitted into the upper and lower cutouts 24a, 24b of the pressure member 2, respectively. At this time, the brake pad 7 is held in a neutral position (an intermediate position in the front-rear direction) by return springs (return springs) 22 and 22, and the pin 23a above the back surface of the brake pad 7 is connected to the notch 24a of the pressure member. The lower pin 23b is in contact with the vertical wall 25a, and the lower pin 23b is in contact with the vertical wall 25b of the notch 24b of the pressure member. The pins 23a and 23b and the notches 24a and 24b having vertical walls constitute a pair of upper and lower one-way drive mechanisms.
When the brake disk 7 rotates in the forward direction (the forward direction of the vehicle) with the brake pad 7 pressed against the brake disk 9, the brake pad 7 is dragged forward by the brake disk 9 against 22 when the brake pad 7 returns. The pin 23a above the rear 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 shaft 2 is rotated by the operation shaft 1). In the same direction as the operated direction), and the pressing force 2 is strongly pushed out by the cam action of the cam grooves 4 and 5 and the wedge ball 6 to further increase the braking force of the brake. When the brake disc 9 rotates in the reverse direction (reverse direction of the vehicle), the brake pad 7 is dragged backward by the brake disc 9, and the pin 23 b below the back surface of the brake pad 7 is connected to the notch of the pressure member 2. The pressure member 2 is pushed in the same direction (arrow R direction) by being pushed onto the vertical wall 25b of 24b, and the pressure member 2 is strongly pushed out by the cam action of the cam grooves 4 and 5 and the wedge ball 6, thereby braking the brake. Is further increased.
When one of the upper and lower pins 23a, 23b, for example, the pin 23a pushes the vertical wall 25a of the notch 24a, the other pin 23b also moves in the same direction, but the other pin 23b is located beside the notch 24b. Since it moves backward along the direction wall 26b, it does not become an obstacle to rotating the pressurizing member 2 in the arrow R direction. The same applies to the case where the pin 23b pushes the vertical wall 25b of the notch 24b.
Thus, even if the brake pad 7 is dragged forward or backward by the brake disc 9, the pressure member 2 is driven in the same direction (arrow R direction) by either of the pins 23a and 23b. Therefore, even if the brake disk 9 rotates in either the forward direction or the reverse direction, the servo action is generated and the braking force can be further increased.
The notches 24a and 24b with which the pins 23a and 23b are engaged have a relatively small diameter of the pressure member 2 in a normal vehicle mechanical disc brake. Therefore, the vertical walls 25a and 25b and the lateral walls 26a and 26b are used. Although the L-shaped notches 24a and 24b are formed as follows, they may be laterally elongated holes. When the pressure member 2 is driven and rotated by the pins 23a and 23b, the pin moves slightly in the radial direction with respect to the notch. It is necessary to make the width slightly larger than the diameter of the pin.
The pair of upper and lower one-way drive mechanisms including the pin 23a and the notch 24a, and the pin 23b and the notch 24b described above are used to move the brake pad in the forward direction and the backward direction. Is a transmission mechanism that converts the pressure member into a rotary motion and transmits it to the pressure member, but has a notch in the brake pad and a pin protruding from the end surface of the pressure member. If the pin is pushed by the longitudinal wall of the notch, the same effect is obtained. And when making a notch into a horizontal long hole, a horizontal long hole should just be provided in a separate board, and this should just adhere to the back of brake pad 7.
Further, since the up / down unidirectional drive mechanism is a mechanism that alternatively transmits the forward and backward movements of the brake pad as rotational movements to the pressure member, it can also be configured by a rack and pinion mechanism. In this case, a pair of upper and lower rack gears (see FIGS. 6 to 8) 61 and 62 (upper rack gear is downward and lower rack gear is upward) are provided on the rear surface of the brake pad 7, and two gears meshing with the respective rack gears 61 and 62 are provided. Pinions 63 and 64 are provided concentrically on the pressure member 2, and one-way clutches 65 and 66 having the same direction of operation are 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 and 62 drive the pinions 63 and 64 in opposite directions, but the pressurizing member 2 is unidirectionally driven by the pinion 63 engaged with the upper rack gear 61. Driven forward (in the direction of arrow R) via the clutch 65. At this time, the pinion 64 meshed with the lower rack gear 62 rotates in the opposite direction, so that the one-way clutch 66 enters a free state, and the pinion 64 rotates freely with respect to the pressure 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) via the one-way clutch 66 by the pinion 64 meshing with the lower rack gear 62. At this time, the pinion 63 meshed with the upper rack gear 61 is free to rotate with respect to the pressure member 2 because the one-way clutch 65 is in a free state. As described above, the pressure member 2 is driven by the rack and pinion mechanism in the same direction (arrow R direction) regardless of whether the brake pad is dragged forward or backward by the brake disc.
However, the rack and pinion mechanism is more complicated than the mechanism using pins and notches, so that the mechanism using pins and notches is superior in terms of practicality.
[0007]
[Effect]
The invention that has solved the above problems is not yet known. Therefore, it is a unique effect of the present invention to solve this problem and solve the above-mentioned problems in the prior art.
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 utilizing this dragging force, so that even if braking is applied with a small operating force, the brake disc is powerful. Can be braked. Therefore, the output of the actuator that rotates the operation shaft can be reduced (smaller and lighter). Further, when the output of the actuator is reduced, the force applied to the rotation operation shaft 1 and the lever 10 is also reduced, so that these can be reduced in size and weight, and the manufacturing cost can be reduced. .
Furthermore, since the actuator can be miniaturized, the occupied space is reduced and the arrangement becomes easy. This effect is remarkable in the case where the space occupied by the air actuator is very large, such as a very large truck.
When the present invention is applied to a parking brake by operating a manual lever, the manual operating force can be reduced, so that the operation becomes easier. In addition, an operation mechanism of a parking brake for a relatively small truck, which has conventionally used an air actuator, is provided. It can also be changed to manual operation.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an embodiment.
FIG. 2 is a view taken along the line AA in FIG.
3A is a cross-sectional view of the pressure member, FIG. 3B is a front view of the pressure member, and FIG. 3C is a rear view of the pressure member.
4A is a front view of a caliper cover, and FIG. 4B is a cross-sectional view taken along line BB in FIG.
5A is a front view of a brake pad, and FIG. 5B is a cross-sectional view taken along a line CC in FIG.
FIG. 6 is a cross-sectional view of another embodiment.
FIG.
8 is a cross-sectional view showing the relationship among the rack gear, pinion, and one-way clutch shown in FIG. 6;
FIG. 9 is a cross-sectional view of a conventional disc brake.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Operation shaft 2 ... Pressure member 2 '... Pressure part 3 ... Caliper 3a ... Bottom surface of a 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 ... Horizontal walls 61, 62 ... Rack gears 63, 64 ... Pinions 65, 66 ... One-way clutch

Claims (2)

A booster mechanism with a cam groove and a wedge ball is interposed between the back surface of the cylindrical pressure member fitted to the caliper cylinder and the bottom surface of the caliper cylinder, and the pressure member is rotated. In the parking mechanical disc brake that brakes the brake disc by being advanced by the booster mechanism,
Two unidirectional drive mechanisms for rotating the pressure member in one direction between the pressure member and the brake pad pressed by the pressure member are provided in a pair of upper and lower sides,
The caliper supports the brake pad so that the caliper can move in the longitudinal direction of the vehicle,
A return spring is interposed between the brake pad and the holding member, and the brake pad is held at the neutral position in the front-rear direction by the return spring.
When the brake pad moves forward and backward against the return spring, one of the one-way drive mechanisms rotates the pressure member by moving forward and the one-way drive by moving backward. A parking mechanical disc brake in which the other side of the mechanism rotates the pressure member and rotates it in the same direction in both forward and backward movements to increase the braking force. A pin projecting from the pressure member or a brake pad pressed by the pressure member, and a notch having a vertical wall provided on the brake pad or the pressure member pressed by the pressure member, The parking mechanical disk brake according to claim 1, wherein the one-way drive mechanism is configured.

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