JPS59166733A - Disc brake with parking brake mechanism - Google Patents

Abstract

PURPOSE:To improve facility of air extraction while ensuring easy access to a pad for replacement thereof by interposing a plate which constitutes a thrust bearing between a push member and the head part of an adjusting bolt. CONSTITUTION:For replacement of a pad, if a piston 30 is thrusted into a cylinder 28b, an adjusting bolt 38 is turned by the actions of the projection 38b thereon and a thrust bearing constituted by a plate 48, and is then thrusted into an adjusting nut 36, so that the piston 30 and the adjusting nut 36 may make no turn and be returned to the initial states. Since the closed end 36a only of the adjusting nut 36 stays inside the cylinder 28b while the other parts are arranged outside thereof, there will be no formation of complicated air stagnancy inside the cylinder 28b, hence improving facility of air extraction.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a disc brake with a parking brake mechanism, and in particular, a cup-shaped piston is fitted into a cylinder formed in a caliper so as to be slidable in the axial direction via a piston seal. The present invention relates to a disc brake with a parking brake mechanism in which a piston is pushed by a parking brake mechanism or a pressure fluid supplied into the cylinder to press a pad.

Conventionally, as this type of disc brake,
There is one disclosed in Japanese Patent No. 19556 and shown in FIG. In this disc brake, the parking brake mechanism includes an adjustment bolt 2 disposed coaxially within a cup-shaped piston 1 and fixed to the piston 1, and a caliper that is threadedly engaged with the adjustment bolt 2 through a thrust bearing 3. 4
The adjusting nut 5 is engaged with the bottom wall 4b of the cylinder 4a formed in the figure, and the cylindrical retainer 6 is fixed to the circumferential wall of the cylinder 4a. A thrust bearing 8 is inserted between the spring 7 and the adjusting nut 5, and the adjusting nut 5 is fitted into an inner hole 4c formed coaxially with the cylinder 4a so as to be slidable in the axial direction. A piston 9 facing each other with a gap S, and a cam groove 10 rotatably supported by the caliper 4 at the back of the piston 9 and facing the back recess 9a of the piston 9.
a camshaft 1o and a piston 9
It is constituted by a toggle 11 etc. that is interposed between the two and connects the two.

In this disc brake, when the piston 1 is pushed to the left by pressure fluid supplied into the cylinder 4a, the adjustment bolt 5 is moved by a spring against the adjustment bolt 2, which moves integrally with the piston 1. 7 and the thrust bearing 8 cooperate to rotate, and the so-called pad clearance is automatically adjusted.

Furthermore, if the piston 1 is pushed into the cylinder 4a when replacing the pad, the adjusting nut 5 will rotate due to the action of the thrust bearing 3, and the piston 1 and the adjusting pole 1-2 will return to the illustrated state (initial state) without rotating. Therefore, not only is the workability good, but the piston seal 12 is not twisted by the piston 1.

However, in this disc brake, the adjustment bolt 2 of the parking brake mechanism. Thrust bearing 3.
Adjustment nut 5. Since a large number of parts such as the retainer 6, the spring 7, and the thrust bearing 8 are housed within the cylinder 4a, a complicated air pocket is formed within the cylinder 4a, resulting in extremely poor air removal performance.

The present invention was made in view of this problem, and its purpose is to secure the conventional advantages (automatic adjustment of pad clearance, good workability during pad replacement, and prevention of damage to the seal ring) while also The objective is to reduce the number of parts of the parking brake mechanism housed in the vehicle and improve air bleed performance.

In order to achieve the above-mentioned object, the present invention includes a parking brake mechanism that is slidably inserted into a mounting hole provided in the bottom wall of the cylinder coaxially with the histone via a seal ring, and has a closed end. a bottomed cylindrical adjustment nut that protrudes into the cylinder and is connected to the piston; an adjustment bolt that is screwed into the adjustment nut so that it can move forward and backward, and whose head projects out of the cylinder; a spring interposed between the head of the adjustment bolt and the bottom wall of the cylinder to urge the adjustment bolt outward from the cylinder; and a thrust bearing to ensure smooth rotation of the adjustment bolt; The pusher is coaxially disposed and supported by a portion of the caliper, has a groove substantially perpendicular to the axis of the adjustment bolt at one end, and selectively engages with the head of the adjustment bolt to form a clutch. a second spring that is interposed between the pusher and a part of the caliper and biases the pusher outward; and a second spring that has an intermediate portion inserted into a groove of the pusher. A second plate is interposed between the pusher and the head of the adjustment bolt, and is separably engaged with the center top surface of the head of the adjustment bolt.
a plate constituting a thrust bearing; a cam groove rotatably supported by a support arm extending from the bottom wall of the cylinder of the caliper and facing the other end of the pusher; and integrally provided with a parking lever. The camshaft is provided with a toggle interposed between the cam shaft and the other end of the cam groove and the pusher to move the pusher in the axial direction in accordance with rotational displacement of the cam groove. .

According to the above configuration, when the piston is pushed by the pressure fluid supplied into the cylinder, the adjustment nut moves as the piston moves, and at the same time, the adjustment bolt is moved to the adjustment nut by the cooperative action of the spring and the thrust bearing. When the liquid/pressure is released, the piston is returned to a predetermined amount by the restoring action of the known piston seal, and the adjustment bolt is returned to a predetermined amount as a unit, and at the same time, the adjustment bolt is brought back into contact with the plate. The so-called pad clearance is automatically adjusted because the joint rotates and enters the adjustment pad by a predetermined amount. In addition, when replacing the band, if the piston is pushed into the cylinder, the joint bolt will rotate due to the action of the second thrust bearing consisting of the central top surface of its head and a plate, and will enter the adjustment nut. is returned to its initial state (the state in which the pad is not worn) without rotating. Therefore, not only is the workability as good as that of the conventional method, but the piston seal and seal ring are not twisted by the piston or the adjustment nand. In addition, with the above configuration, only the closed end of the adjustment nut, which is a component of the parking brake mechanism, is housed in the cylinder, and the other parts are arranged outside the cylinder, so there is a complicated structure inside the cylinder. No air pockets are formed, and air removal performance is significantly improved.

An embodiment of the present invention will be described below based on the drawings. In the disc brake shown in FIG. 2, bands 24 and 26 disposed on both sides of a disc rotor 22 slide in the left-right direction in the diagram on a torque member 20 that is attached to a part of the vehicle body (for example, a knuckle arm) (not shown). It is movably assembled.

Further, a caliper 2B is attached to the torque member 20 by a known means so as to be slidable in the left-right direction in the drawing. The caliper 28 is formed in a shape that straddles a part of the outer periphery of the disc rotor 22 and surrounds both pads 24 and 26. The caliper 28 is formed in a bifurcated shape at the right end in the figure, and is connected to the pad 2 on the right side in the figure.
A push arm 28a is formed that comes into contact with the back surface of the back plate 242 of No. 4, and a cylinder 28b is formed on the left side in the figure.

The cylinder 28b is formed in the left-right direction in the figure, and a cup-shaped piston 30 is fitted and inserted through a piston seal 32 so as to be slidable in the left-right direction (axial direction) in the figure. is in contact with. This piston 30 is configured to be pushed by pressure fluid supplied into the cylinder 28b or by a parking brake mechanism, and a dust boot 34 is installed between its outer periphery and the outer end of the cylinder 28b. Note that the piston 3° is prevented from rotating by a projection 26b provided on the back metal 26a of the pad 26.

As shown in FIGS. 2, 3, and 4, the parking brake mechanism includes a bottomed cylindrical joint nut 36. Adjustment bolt 38. Spring 40. Thrust bearing 42. Pusher 44. second spring 46, plate 48. camshaft 5
0. It is equipped with a toggle 52 and the like. The adjustment nand 36 is a boss portion 28 formed at the center of the bottom wall 28c of the cylinder 2'8b.
It is slidably inserted into the mounting hole 28e of d via a seal ring 37, and its closed end 36a is connected to the cylinder 28.
The top wall 30 of the piston 30 is inserted into the top wall 30 of the piston 30 via the disc spring 31 which protrudes into the interior of the piston 30 and is caulked to the piston 30 at the flange 36b.
It is non-rotatably connected to a.

It has the function of correcting the misalignment of the Adjustment bolt 38
is screwed into the joint Nand 36 by a screw with a large pitch so that it can move forward and backward, and its head 38a is formed in a tapered shape and protrudes outside the cylinder 28b. Also, adjust bolt 3
A conical protrusion 38b (a spherical protrusion may also be used) is integrally formed on the central top surface of the head 38a.

The spring 40 is interposed together with a thrust bearing 42 between the cylinder bottom wall 28c and the head 38a of the adjustment bolt 38, and biases the adjustment bolt 38 toward the left in the figure (outward of the cylinder 28b).

The thrust bearing 42 is located between the head 38a of the adjusting bolt 38 and the spring 40 to ensure smooth rotation of the adjusting bolt 38. The pusher 44 is disposed coaxially with the adjustment bolt 38, and is attached to the cylindrical portion 28f of the caliper 28 at its right side in the figure so as to be slidable in the left-right direction, and the annular flange 44a and the caliper A spring 46 interposed between the end faces of the cylindrical portion 28f of the cylindrical portion 28 is biased toward the left in the drawing. Further, an adjustment bolt 3 is located at the right end of the pusher 44 in the figure.
A tapered hole 44b that selectively frictionally engages with the head 38a of the adjusting bolt 38 to form a clutch is formed, and a groove 44C that is substantially orthogonal to the axis of the adjusting bolt 38 is formed in the vertical direction in the drawing.

The plate 48, as shown in FIG. The caliper 2 is interposed at the upper and lower flange portions 48b.
2E1g step (4th
(see figure) to restrict movement to the left in the figure. This plate 48 is separably engaged with the protrusion 38b of the adjustment bolt 38 to form a thrust bearing, and the head 38'a of the adjustment bolt 38 is connected to the tapered hole 44b of the pusher 44.
They are kept a little apart from each other. The camshaft 50 is rotatably supported via a bearing 5j by a pair of support arms 28h extending leftward in the drawing from the cylindrical portion 28f of the caliper 28, and is mounted in a recess 44d at the left end of the pusher 44 in the drawing. It has opposing cams i'Ft 50a, and integrally has a parking lever 50b at the end projecting outside of the boot 54. The toggle 52 is egg-shaped and has a cam groove 50a.
and the recess 44d of the pusher 44, and moves the pusher 44 in the left-right direction (as shown in the figure) according to the rotational displacement of the cam groove 50a.
It has the function of moving in the axial direction).

In this embodiment configured as described above, the cylinder 2
When pressurized fluid is supplied into 8b, the piston 30 moves to the right and presses the pad 26 against the left side of the disc rotor 22, and at the same time the caliper 28 moves to the left and uses its pushing arm 28a to press the pad 26 against the left side of the disc rotor 22. Since the pad 24 is pressed against the right side surface of the disc rotor 22, a normal braking action can be obtained. At this time, in the parking brake mechanism, the piston 3
0 moves to the right, the adjusting nut 36 moves to the right, and the adjusting bolt 38 rotates due to the cooperative action of the spring 40 and the thrust bearing 42 and projects from the adjusting nut 36. Furthermore, when the hydraulic pressure in the cylinder 28b is released, the piston 30 is returned to the left by a predetermined amount due to the restoring action of the piston seal 32, and the caliper 28 is returned to the right due to the frictional vibration between the disc claw 22 and the pad 24. It will be done. At this time, in the parking brake mechanism, the piston 30
As the adjusting bolt 36 moves to the left, the adjusting bolt 36 integrally moves to the left by a predetermined amount, and the adjusting bolt 38 rotates in cooperation with the plate 48 and enters the adjusting nut 36 by a predetermined amount. Therefore, in this embodiment, the band clearance between the disc rotor 22 and both pads 24, 26 during non-braking is always maintained substantially constant, regardless of the wear of both hats 24, 26.

Further, in this embodiment configured as described above, when the parking lever 50b is rotated clockwise in the drawing and the camshaft 5o is rotated clockwise in the drawing, the cam? M50
a is rotationally displaced to the right, and the toggle 52. Pusher 44. Piston 30 via adjustment bolt 38 and adjustment nut 36
is pushed to the right, the pad 26 is pressed against the left side of the disc rotor 22, and the reaction force pushes the caliper 28 to the left, causing the pad 24 to press against the left side of the disc rotor 22.
The parking brake is applied by being pressed against the right side of the brake. At this time, the head 38a of the adjustment bolt 38 and the pusher 4
The adjustment bolt 38 does not move relative to the adjustment nut 36 because the four taper holes 44b are frictionally engaged to prevent the adjustment pole 38 from rotating.

Further, when the parking lever 50b is rotated in the counterclockwise direction in the drawing and the camshaft 50 is rotated in the counterclockwise direction in the drawing, the cam groove 50a is rotationally displaced to the left, and the spring 40.
46, the toggle 52° pusher 44. Adjustment bolt 38. The adjustment pad 36 and the brake pad 30 are returned to the left to their original positions in the figure, and the caliper 28 is returned to the right to release the parking brake. At this time, the head 38a of the adjusting bolt 38 and the tapered hole 44 of the pusher 44 are connected until the adjusting bolt 38 comes into contact with the plate 48 and stops moving to the left. b frictionally engages to prevent the adjustment bolt 38 from rotating, and δ circumferential bolt 38
When the adjustment bolt 38 comes into contact with the plate 48, the action of the spring 40 and the thrust bearing 42 disappears, so the adjustment bolt 38
does not move relative to the adjusting NAND 36.

Furthermore, in the present embodiment configured as described above, when the piston 30 is pushed into the cylinder 28b when replacing the band, the adjustment bolt 38 is moved between the protrusion 38b and the plate 48.
The piston 30 and the adjusting nut 3 rotate due to the action of the thrust bearing and enter the adjusting nut 36.
The piston 30 and the adjusting nut 36 can be easily returned to the initial state (the pad is not worn).
In addition, the piston seal 32 and seal ring 37 are not twisted by the piston 30 or the adjusting nut 36.

Further, in this embodiment, among the components of the parking brake mechanism, only the closed end 36a of the adjustment pad 36 is accommodated in the cylinder 28b, and the other components are accommodated in the cylinder 28b.
Since the cylinder 28b is disposed outside the cylinder 28b, no complicated air pocket is formed inside the cylinder 28b, and air removal performance is significantly improved. Furthermore, since the sliding portion of the adjusting nut 36 and the threaded portion of the adjusting nut 36 and adjusting bolt 38 are provided in parallel (concentrically), the sliding portion of the adjusting nut 36 and the screwing portion of the adjusting bolt 38 are provided in parallel (concentrically).
The dimensions can be shortened. Therefore, between the top wall 30a of the piston 30 and the back metal 26a of the pad 26, there is actively insulated space R (notch 3 provided at the right end of the piston 30).
0b, which communicates with the outside, and improves resistance to heat loss.

In the above embodiment, the head of the adjustment bolt is formed into a tapered shape, and a tapered hole is formed at one end of the pusher that engages with the head of the adjustment bolt, so that the head of the adjustment bolt and the pusher are formed in a tapered shape. Although the one end was designed to engage with a conical surface, the present invention was implemented by forming the top surface of the head of the adjustment bolt and one end surface of the pusher to be flat so that the two engaged with each other in a flat surface. Further, in the above embodiment, an egg-shaped toggle is used as the toggle, but it is also possible to implement the present invention by using a plate-shaped toggle.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a conventional disc brake with a parking brake mechanism, FIG. 2 is a sectional view showing an embodiment of the disc brake with a parking brake mechanism according to the present invention, and FIG. 3 is an enlarged sectional view of the same part. Figure 4 is the arrow view of Figure 3 ■
FIG. 5 is a front view of the plate. Explanation of symbols 26...Pad, 28...Caliper, 28b...
・Cylinder, 28c...bottom wall, 28d...boss part,
28e...Mounting hole, 28f...Cylinder part, 28g...
Slit, 28h... Support arm, 30... Piston, 30a... Top wall, 32... Piston seal, 3
6... Adjustment nut, 36a... Closed end, 37...
Seal ring, 38...Adjustment bolt, 38a...Head, 38b...Protrusion, 40...Spring, 42...
... Thrust bearing, 44... Pusher, 44G... Groove, 46... Second spring, 48... Plate,
50...Cam shaft, 5'Oa...Cam groove, 52...
toggle. Applicant Aisin Seiki Co., Ltd. Agent - Patent Attorney Teru Hase - Figure 1 Figure 2 Figure 3 ↓

Claims (1)

[Claims] A cup-shaped piston is fitted into a cylinder formed in the caliper so that it can slide in the axial direction via a piston seal.
In a disc brake with a parking brake mechanism in which the piston is pushed by a parking brake mechanism or a pressure fluid supplied into the cylinder to press a pad, the parking brake mechanism is attached to the bottom wall of the cylinder. a bottomed cylindrical adjustment nut that is slidably inserted into a mounting hole provided coaxially with the piston via a seal ring, has a closed end protruding into the cylinder, and is connected to the piston; an adjustment bolt which is screwed into an adjustment bolt so as to be reciprocatable and whose head protrudes outside the cylinder; A pusher which composes a clutch with a spring biased outward and a circular layer of the adjusting bolt, and a head of the pusher and the adjusting bolt whose intermediate portion is inserted into a groove of the pusher. a plate interposed between the parts and separably engaged with the center top surface of the head of the adjustment bolt to constitute a second thrust bearing; a camshaft of the carino; and the cam of the camshaft. What is claimed is: 1. A disc brake with a kink brake mechanism, characterized in that it has a groove and a structure in which the pusher is fitted.