JPH0134764Y2 - - Google Patents

Description

[Detailed description of the invention] (a) Industrial application field This invention relates to an improvement of the force transmission part of a disc brake incorporating a parking brake mechanism.

(B) Prior Art Disc brakes incorporating a parking brake mechanism, so-called built-in type disc brakes with a parking brake mechanism, have been known for a long time. In such disc brakes, an actuation lever is provided that is connected to the parking brake lever via an actuation transmission cable, and this actuation lever transmits force to the push rod via an interlocking mechanism such as an internal camshaft. The piston for pressing the brake pads is actuated by this.

A return spring is attached to the above-mentioned operating lever, and by engaging one end of the spring with the operating lever and the other end of the spring with a locking member provided on the caliper, the return spring can be set in the return direction relative to the operating lever. It is designed to provide spring force. The retraction limit stopper of the operating lever is constructed by bringing one end of the operating lever into contact with the locking member or with a separately provided stopper.

A camshaft is fixedly connected to the operating lever,
The camshaft has a structure in which a conical concave surface is provided in a direction eccentric from the axis, and by bringing one end of the strut into contact with the concave surface, the rotational motion of the camshaft is converted into linear motion, moving the strut and pushing the push rod. It is said that The camshaft is supported by a needle bearing press-fitted into the caliper, allowing smooth rotation.

(c) Problems to be solved by the invention (1) The above-mentioned intersection angle between the strut and the camshaft (α in Figure 1) is difficult to set to exactly 90° due to variations in processing accuracy, and in reality it is centered around 90°. It has a width of . If α is smaller than 90°, when a force is applied to the strut due to parking lever operation, the reaction force of the strut will be applied to the camshaft, and the direction of the reaction force will be tilted to the opposite side from the operating lever installation side. The camshaft has
There is no force to pull the camshaft out in the direction toward the operating lever installation side. On the other hand, if α is larger than 90° as shown in Figure 2, when the parking lever is operated, a reaction force tilted toward the side where the actuating lever is attached is applied to the camshaft, so the actuating lever is not attached to the camshaft. A force is applied in the side direction to try to get out of the caliper. For this reason, a slip-off prevention mechanism is required to prevent slip-off, which results in friction loss when the lever is operated.

(2) As shown in Figure 1, the slip-out prevention mechanism described in item 1 has a conventional structure in which a lever spring is locked to the flange of the bolt, and the lever is pressed down by the lever spring, so the mechanism described in item (1) When a pull-out force is applied to the camshaft when the lever is operated, friction occurs between the lever and the lever spring, resulting in significant friction.

(d) Means for solving the problem In order to solve the above problem, the conical concave position of the camshaft is made eccentric to the side opposite to the operating lever from the center of the axis of the cylinder (see Figure 3). In addition, a collar is provided on the cable guide mounting bolt, so that when the camshaft tries to come out, the actuating lever hits the collar to prevent it from coming off, and when the camshaft is pushed in the opposite direction to the actuating lever, it will not engage with the actuating lever. Gap b between stop bolt collar (Fig. 3)
By making a smaller than a (Figure 3),
The intersection angle α between the strut and the camshaft when the operating lever is activated is always an acute angle, so that no force is applied to the camshaft to pull it out. Furthermore, friction between the lever spring and the lever is avoided by locking one end of the lever spring on the opposite side of the locking bolt collar from the side where the operating lever locks.

(e) Embodiment Since the internal structure of a disc brake with parking brake is conventionally known, it will be briefly explained with reference to FIG. A main piston 3 is installed inside a cylinder 2 provided in a caliper 1, and an auxiliary piston 4 and a push rod 5 are installed inside the main piston 3. The push rod 5 is non-rotatably slidably held relative to the caliper by a key plate 6. Auxiliary piston 4 and main piston 3
A spring 7 and a thrust bearing 8 are installed between them. The auxiliary piston 4 and the push rod 5 are screwed together with a large lead. During normal hydraulic brake operation, force is applied to the main piston by hydraulic pressure, and braking force is obtained by pressing the pad 9 against the disc 10. When the pad is worn and the gap between the disk and the pad exceeds a certain value, the auxiliary piston rotates relative to the push rod during hydraulic pressure operation, reducing the gap between the disk and the pad as the pad wears. This prevents the gap between disks from increasing. This is a floating type disc brake with a built-in pad wear compensation device.

The push rod 5 is adapted to be moved by a camshaft 11, and an operating lever 12 is connected to one end of the camshaft 11. The actuating lever 12 has a notch 13 at one end thereof, into which a transmission cable 14 is engaged which is actuated by the parking brake lever.

Further, in the vicinity of the mounting portion of the operating lever 12, one end of a cable support bracket (cable guide 15) is fixed to the caliper 1 with a mounting bolt 16.

The end 17 of the operating lever 12 on the side opposite to the notch 13 is formed into a thin claw shape, and in the state shown in FIG. 3 when no tensile force is applied to the cable 14, the claw-shaped end 17 comes into contact with a mounting bolt 16 of the cable guide, and this bolt 16 serves as a stopper when the operating lever is at rest. Further, the return spring (lever spring) 18 of the actuation lever 12 is in the form of a coil, and its coil portion is fitted into a nut 19 that is screwed into the camshaft 11 to prevent the actuation lever 12 from falling off, and one end is attached to the actuation lever 12.
The other end is engaged with the mounting bolt 16. Therefore, when no tensile force is applied to the cable 14, the actuating lever 15 is moved by the spring 18.
The spring force causes the end 17 of the mounting bolt 16 to
It is in the state shown in the figure, in contact with the

The camshaft 11 and the push rod 5 are provided with conical recesses in which both ends of the strut 20 abut, and the strut 20 is fitted between them.
The camshaft 11 rotates in conjunction with the operation of the lever 12, causing the strut 20 to move linearly and pushing the push rod 5. The camshaft is
Needle bearing 2 press-fitted into the caliper
2, it is rotatably supported.

Next, I will describe the features of this proposal.

Strut 20 provided on the camshaft 11
As shown in FIG. 3, the conical concave position which is the abutting part is located closer to the counteractuation lever than the axial center of the cylinder. Let the amount of eccentricity of this cylinder with respect to the axial center be a.

The operating lever part is located inside the flange 21 provided on the mounting bolt 16 (on the caliper side) over the entire operating range, and the operating lever 1
Assuming that the gap between the claw portion 17 and the collar 21 of No. 2 is b (FIG. 3), the design is such that the relationship between a and b is always a>b. Therefore, even if b is 0 when the parking lever is at rest (that is, the operating lever 17 and the flange 21 of the mounting bolt are in contact), a is larger than 0 (that is, the angle α is acute), so when the parking lever is operated, the camshaft 11 has no power to escape.

Furthermore, the flange portion 21 of the mounting bolt 16 also serves to prevent the camshaft 11 from coming off from the caliper due to vibration.

Furthermore, the lever spring 18 mounting bolt 1
The locking end on the 6 side is locked to the outside (on the opposite side of the caliper) of the flange 21 of the mounting bolt, so the actuating lever 12 and lever spring 18 may not be in contact with each other, or even if they are in contact, it may be only a light contact. There is almost no friction between the operating lever 12 and the lever spring 18 during operation, and there is no wear.

(f) Effects As mentioned above, with this device, when the actuating lever is actuated, a force is always applied to the camshaft in the direction of the counter-actuating lever, so the camshaft does not come off, and the lever and mounting bolt rub against each other when actuated. Will not wear out. Furthermore, since the locking end on the mounting bolt side of the lever spring is devised as described above, there is no wear due to friction between the lever and lever spring, and high durability and reliability around the operating lever can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of the conventional shape, Fig. 2 is a partial sectional view of the camshaft and strut portion, and Fig. 3 is a sectional view of the conventional shape.
A sectional view of the embodiment of this invention, FIG. 4 is A of FIG.
This is a perspective view. 1... Caliper, 2... Cylinder, 3... Main piston, 4... Auxiliary piston, 5... Push rod, 6... Key plate, 7... Spring,
8... Thrust bearing, 9... Padded, 10
...Disc, 11...Camshaft, 12...
Lever, 13...Lever notch, 14...Cable, 15...Cable guide, 16...Cable guide mounting bolt, 17...Lever stopper claw, 18...Lever spring, 19...Nut, 20...Strut , 21...The flange of the mounting bolt.

Claims (1)

[Scope of utility model registration request] In a disc brake with a parking brake mechanism, an actuation lever is connected to a push rod engaged with a brake pad actuation piston via an interlocking mechanism, and a parking brake lever is connected to the actuation lever via a cable. Lever 1
When the contact point between the camshaft 11 and the strut 20, which constitute the cam mechanism that converts the force applied to the push rod 2 into the push rod pressing force, is projected onto a plane parallel to both axes, the distance between the point of intersection between the contact point and the push rod 5 A disc brake with a parking brake mechanism, characterized in that a is constructed such that the relationship between the distance b between the mounting bolt 21 and the lever stopper claw portion 17 is always a>b.