JPS6327155Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an automatic pad gap adjustment device for a disc brake.

The disc brake, which can also provide braking action with a handbrake, is equipped with an automatic pad gap adjustment device, which includes a piston that is slidably fitted into the cylinder housing with the friction pad facing the back. A combination of a first strut and a second strut screwed together is interposed in the cylinder housing on the back side of the piston, and the handbrake operating force is applied to the first strut, the second strut, and the first strut.
There is one in which the signal is transmitted to the piston via a second strut. The second strut is normally biased by a spring so as to come into contact with the back side of the piston, and during main braking using hydraulic pressure such as foot braking, in other words, pressure oil is supplied into the cylinder and the piston moves the friction pad against the disk. When the piston is pressed toward the piston, the amount of displacement of the piston (pad gap - gap between the friction pad and the disk) is greater than a predetermined value,
The second strut, which is receiving the biasing force of the spring, rotates relative to the first strut, increasing the overall length of the combined struts, and thus increasing the amount of brake operation (foot) in accordance with the wear of the friction pads. A predetermined braking force can be obtained by braking (both when braking and when using the handbrake).

As mentioned above, as the friction pads wear out, it is necessary to rotate the second strut with respect to the first strut to increase the overall length of the two strut combination. It needs to be stopped so that it does not rotate. For this reason, conventionally, a key plate for preventing rotation, into which the first strut is fitted so as to be slidable and non-rotatable, is seated on the inner bottom of the cylinder, and the key plate is fitted in a concave-convex manner to the cylinder housing in the disk axial direction. This makes it impossible to rotate with respect to the cylinder housing, and a retaining ring is used to prevent the above-mentioned concave-convex fitting from coming off.

However, in the conventional type, the key plate and retaining ring had to be installed by hand in a narrow and deep place at the bottom of the cylinder, making the assembly very troublesome.

The present invention solves the above-mentioned problems and aims to provide an assembly work that can be performed outside the cylinder, that is, under a wide working chamber.

In order to achieve this object, the present invention is characterized in that a key plate for preventing rotation of the first strut is fixed to the piston.

With this configuration, the key plate can be assembled to the piston together with the first strut, second strut, etc. under a wide working chamber before the piston is assembled to the cylinder housing. As a result, the assembly workability can be dramatically improved.

The present invention will be described in detail below with reference to drawings showing embodiments thereof. In FIG. 1, a carrier 2 is fixed to a non-rotating member (not shown) of the vehicle on one side of the disk 1, and the carrier 2 has a pair of friction pads 3 and 4 disposed with the disk 1 in between. It is held slidably in the axial direction (horizontal direction in FIG. 1). Also, carrier 2 has pins 5 and 6.
The caliper 7 is held so as to be slidable in the axial direction of the disk 1. This caliper 7 has a cylinder housing portion 7a, a bridge portion 7b that extends around the outer circumference of the disk, and leg portions (not shown) that extend to the back surface of the friction pad 4.

The cylinder housing portion 7a of the caliper 7 includes
A cylinder 8 that opens toward the back of the friction pad 3
A piston 9 in the shape of a cylinder with a bottom is slidably inserted into the cylinder 8 with its open end facing the inner bottom of the cylinder 8 . Inside the cylinder housing part 7a, on the back side of the piston 9, a combined body of a first strut 10 and a second strut 11 is interposed such that its axis extends in the direction of the axis of the disk 1. The second strut 11
A male threaded portion 11a formed in is screwed together. Both threaded portions 10a and 11a are, for example, multi-thread threads, and when a tensile force is applied to both struts 10 and 11, they rotate relative to each other, increasing their overall length. On the contrary, when a pressing force is applied, both 10 and 11 rotate in the opposite direction relative to each other, and the total length thereof becomes shorter.

The back side of the first strut 10 has a large diameter portion 1 whose outer diameter is slightly larger than the outer diameter of the female threaded portion 10a.
0b, and the large diameter portion 10b extends slidably into a guide hole 12 formed in the cylinder housing 7a. Such a first strut 1
On the back side of 0, the cylinder housing part 7a
A camshaft 14 is rotatably held via a bearing 13, and an intermediate rod is provided between a cam groove 14a formed on the outer peripheral surface of the camshaft 14 and a recess 10c formed on the rear end surface of the first strut 10. 15 is interposed. camshaft 14
is rotatable about an axis perpendicular to the axis of the first strut 10, and one end thereof extends to the outside of the caliper 7, and an arm 16 is integrated therein, and the arm 16 is connected to the arm 16. A hand brake lever (not shown) is connected via a wire (not shown) or the like.

An annular key plate 17 is fixed to the open end of the piston 9 (inner end of the cylinder 8). That is, the key plate 17 is tightly fitted to the inner circumferential large-diameter portion 9a of the piston 9, and is resting on the stepped portion 9c between the inner circumferential large-diameter portion 9b and the small-diameter portion 9b.
c and a caulked portion 9d which is a part of the piston 9, and is fixed to the piston 9 in a non-rotatable manner. And key plate 1
In order to further prevent the rotation of the key plate 17 and the piston 9, the outer periphery of the key plate 17 and the inner periphery of the piston 9 are fitted in a non-circular cross-sectional state, as shown in FIG. The first strut 10 passes through the inner hole 17a of the key plate 17, and while the inner hole 17a is non-circular, the outer shape of the first strut 10 passing through it is also non-circular. , the first strut 10 has a key plate 1
7, but not rotatable.

On the other hand, the second strut 11 has a male threaded portion 11a.
It has a flange portion 11b on the disk 1 side, and a tapered surface 11c formed on the flange portion 11b is in contact with a tapered surface 9e formed on the back surface of the piston 9. The second strut 11 is connected to the disk 1 through a sleeve 19 and a bearing 20 by a spring 18 that uses the key plate 17 as a seat at one end.
The tapered surfaces 11c and 9e are biased toward the side, that is, so that the tapered surfaces 11c and 9e come into contact with each other. Then, the disk 1 side end 11d of the second strut 11 is connected to the piston 8.
A rotary tool engaging portion 11e is formed on the end surface of the end portion 11d, which is a polygonal recess into which a rotary tool such as a wrench is engaged. has been done.

In FIG. 2, 9g is an engagement recess formed on the end surface of the piston 9 on the side of the disk 1 for engaging a rotation prevention tool, 21 to 23 are seal members for ensuring liquid tightness of the cylinder 8, and 24 is a dust boot. It is.

Next, the operation of the above configuration will be explained. now,
When a brake pedal (not shown) is depressed (during main braking), pressure oil is supplied into the cylinder 8 and presses the piston 9 toward the disk 1 side. As a result, the piston 9 presses one of the friction pads 3 toward one side of the disk 1, while the caliper 7 moves to the right in FIG. This performs a braking action.

On the other hand, when a handbrake lever (not shown) is operated, the camshaft 14 is rotated, and this rotational force is applied to the intermediate rod 15, the first strut 10, and the second strut.
The piston 9 is pressed toward the disk 1 via the strut 11, and a braking action is performed in the same manner as in the main braking described above.

Now, as the wear of the friction pads 3 and 4 progresses,
During main braking, the amount of displacement of the piston 9 to the left in FIG. 1 increases, and the tapered surfaces 9e and 11c tend to separate. Then, the second strut 11, which is biased toward the disk 1 side by the spring 18,
While rotating with respect to the first strut 10, it extends toward the disk 1, and the total length of the combined body of both struts 10 and 11 increases by an amount corresponding to the wear described above. As a result, the camshaft 14 and the first strut 10
(When the first strut 10 is largely displaced to the left in FIG. 2, the rotational force of the camshaft is transferred to the first strut via the intermediate rod 15.) communication becomes impossible). Further, a predetermined braking force can be obtained by a predetermined brake operation (both the main brake and the handbrake).

Here, the first and second struts 1 as described above are
0, 11, etc. are assembled by assembling each member 10, 11, 17, 18, 19, 20, etc. to the piston 9 in advance outside the caliper 7, that is, in a wide space. This can be done by fitting the solid body into the cylinder 8.

Furthermore, when replacing the friction pads 3 and 4, it is necessary to shorten the overall length of the combined struts 10 and 11 to match the new friction pads. While preventing the second strut 11 from rotating, a rotary tool may be engaged with the engaging portion 11e of the second strut 11 to rotate the second strut 11 relative to the first strut 10.

In addition, a stopper part 25a protruding from the bleed screw 25 for air bleeding is extended into the cylinder 8, and the stopper part 25a is brought into contact with the end surface of the large diameter part 10b of the first strut 10. Then, when replacing the friction pads, both struts 1
0, 11, etc. can be prevented from accidentally coming off from the cylinder 8. Further, while the first strut 10 is formed with a male threaded portion, the second strut 11 may be formed with a female threaded portion that is screwed into the male threaded portion. Of course, the present invention is equally applicable to other types of disc brakes than the embodiment shown in the drawings.

The present invention is an automatic part gap adjustment device for a disc brake, in which the first strut is formed to have a non-circular cross section, and the key plate has a non-circular inner hole into which the first strut is slidably and non-rotatably fitted. is fixed to the opening side of the piston, so as the friction pad wears out, the first strut screws out relative to the first strut, which is securely prevented from rotating by the key plate, and adjusts the gap between the pads. A predetermined braking force can be obtained during foot braking and hand braking.

When assembling this disc brake part gap automatic adjustment device, the key plate that prevents the first strut from sliding relative to the piston is fixed to the opening side of the piston. 1st strut, 2nd strut,
The spring, key plate, etc. that biases the second strut against the back of the piston can be assembled in advance in a large working space, and the assembly can be performed by inserting this assembly into the cylinder. This allows for extremely improved workability.

Therefore, productivity is improved, manufacturing costs can be reduced, and maintainability is also improved.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing an example of a disc brake to which the present invention is applied, FIG. 2 is a sectional view of a main part in the axial direction of the disc in FIG. 1, and FIG. 3 is a sectional view taken along the line of FIG. 2. 3...Friction pad, 7a...Cylinder housing part, 8...Cylinder, 9 piston, 10...First strut, 10a...Threaded part, 11...Second
Strut, 11a...Threaded portion, 17...Key plate.

Claims (1)

[Scope of Claim for Utility Model Registration] A cylindrical piston with a bottom facing the back side of the friction pad is slidably fitted into the cylinder housing, and the first piston is screwed together with a multi-thread screw and is movable relative to the other in the axial direction.
A combination of a strut and a second strut is interposed in the cylinder housing on the back side of the piston, a handbrake lever is connected to the first strut via a wire, and the second strut is connected to the piston by a spring. In the pad gap automatic adjustment device for a disc brake, the second strut screws out with respect to the first strut according to the amount of movement of the piston to adjust the gap between the friction pad and the disc by applying force to the back side. 1 strut is formed into a non-circular cross section,
An automatic pad gap adjustment device for a disc brake, characterized in that a key plate having a non-circular inner hole into which the first strut is slidably and non-rotatably fitted is fixed to the opening side of the piston.