JPH0144816Y2 - - Google Patents

Description

[Detailed Description of the Invention] Technical Field The present invention relates to an improvement of a disc brake equipped with a parking brake function.

Prior Art A type of disc brake with a parking brake function includes a caliper that has a cylinder portion in which a piston is slidably fitted and that straddles the disc rotor, and a pair of pads that sandwich the disc rotor inside the caliper. and a parking brake pressing device that is provided on the caliper and presses the pad based on the parking brake operating force transmitted via the mechanical operating force transmission means, the parking brake pushing device being provided on the caliper and pressing the pad based on the parking brake operating force transmitted via the mechanical operating force transmitting means. While the pad is pressed by the piston based on the force, there is also a type in which the parking brake pressing device also presses the pad via the piston. For example, the one described in Japanese Unexamined Patent Publication No. 151636/1983 is one such example.

Problems to be solved by this invention However, when operating the parking brake of a disc brake equipped with such a parking brake function, the caliper is usually placed a certain distance away from the part of the caliper that straddles the disc rotor on the inner circumferential side of the disc rotor. Due to the center position of the pressing force of the parking brake pressing device on the pad and the rigidity of the caliper, the cylinder part of the caliper moves away from the disc rotor using the part that straddles the disc rotor as a fulcrum. It is inevitable that it will be expanded slightly. At this time, since the stroke of the pressing device is usually relatively small, if part of the stroke is consumed by the expansion of the caliper, the pressing force of the pressing device against the pad, that is, the effectiveness of the parking brake, will be insufficient. There were times when I couldn't get it.

Means for Solving the Problems The present invention has been made against the background of the above-mentioned circumstances, and its gist is to provide a disc brake with a parking brake function of the type described above. The center position of the pressing force on the pad by the brake pressing device is
The piston is located closer to the outer periphery of the disc rotor than the axis of the piston.

Function and Effect of the Invention With this arrangement, the center position of the pressing force applied to the pad by the parking brake pressing device is located closer to the outer circumference of the disc rotor than the axis of the piston, so when the caliper is expanded. The parking brake force is applied centered at a position closer to the part that straddles the disc rotor, which is the fulcrum of the brake, and the expansion of the caliper when operating the parking brake is suppressed compared to the past. As a result, it is relatively avoided that a part of the stroke of the pressing device is consumed with the expansion of the caliper, and the effectiveness of the parking brake is further improved compared to the prior art.

Furthermore, since the center position of the pressing force by the pressing device is located closer to the outer periphery of the disc rotor than the axis of the piston, the center of rotation of the disc rotor, which is one of the determining factors of braking torque, and the center position of the pressing force As a result, the parking brake becomes more effective than before.

Embodiment Hereinafter, an embodiment of the present invention will be described in detail based on the drawings.

FIG. 1 is a diagram showing the main parts of a disc brake equipped with a parking brake function to which the present invention is applied, in which a caliper 12 is attached to the outer periphery of a disc rotor 10 that is rotatably provided together with wheels, etc. 10 in the thickness direction and is arranged in a floating state by means of a slide pin (not shown) or the like. The caliper 12 includes a cylinder portion 18 in which a piston 16 is slidably fitted into a cylinder bore 14, and an arm portion that extends from an upper portion of the cylinder portion 18 in a direction substantially parallel to its axis at one end of the cylinder portion 18. 20 and its arm portion 20
A claw portion 22 is provided at the tip end of the disk rotor 10 in a direction substantially perpendicular to the axis of the cylinder portion 18 and extends toward the inner circumferential side of the disk rotor 10. Also,
A pair of pads 24 and 26 are disposed inside the caliper 12, that is, between the piston 16 and the claw portion 22, with the disc rotor 10 sandwiched therebetween, and these pads 24 and 26 are not shown. The pistons 16 are supported movably in the axial direction of the piston 16 on a torque plate 28 fixed to a non-rotating member.

When brake fluid pressure is supplied to the cylinder part 18 in the disc brake configured in this way, the piston 16 is pushed out and the pad 24 is pressed against the left side surface of the disc rotor 10 in the figure, and the reaction force pushes the caliper 12. is piston 1
6, the claw portion 22
As a result, the pad 26 is pressed against the right side surface of the disk rotor 10 in the figure. As a result, the disc rotor 10 is compressed by a predetermined pressing force, and its rotation is suppressed.

The caliper 12 of such a disc brake has
Further, a parking brake pressing device is provided on the other end of the cylinder portion 18 and within the cylinder bore 14 to push the piston 16 toward the pad 24 based on the parking brake operating force. That is, a through hole 32 is formed in the bottom wall 30 of the cylinder part 18 so that its center is located at a predetermined distance (L in the figure) above the axis A of the cylinder part 18 (piston 16). A portion of the periphery of the through hole 32 extends a predetermined distance toward the interior of the cylinder portion 18 in a direction parallel to the axis, forming a boss portion 34 having an arcuate cross section. A bottomed cylindrical nut member 3 is provided in the through hole 32.
6 is slidably fitted while being supported by the boss portion 34. A flange 38 formed on the bottom side of the nut member 36 is attached to the top wall 42 of the piston 16 by a retaining ring 40, and the nut member 36 is operated integrally with the piston 16 in a state where it cannot rotate around the axis. . The nut member 36 has an adjusting bolt 46 having a tapered head 44, and the head 44 side is connected to the cylinder portion 18.
are screwed together so as to be relatively movable by a predetermined distance in the axial direction while protruding outward by a predetermined distance from the bottom wall 30 of the holder. A cylindrical member 52 having a pair of slits 48 and 50 extending in the axial direction at positions facing each other in the radial direction is provided on the outer peripheral side of the head 44 of the adjusting bolt 46 and protrudes from the bottom wall 30 of the cylinder portion 18. ing. A generally cylindrical pusher 54 is disposed concentrically on the left side of the head 44 of the adjusting bolt 46 in the figure, and a pair of protrusions formed on the outer periphery of the head 44 in the axial direction is provided. 56 and 58 are fitted into the slits 48 and 50 of the cylindrical member 52, respectively, and a spring 62 is provided between the plate 60 fixed to the outer periphery on the left side in the figure and the distal end surface of the cylindrical member 52. It has been intervened. As a result, the pusher 54 is guided in the axial direction by the slits 48 and 50 in a state where it cannot rotate around the axis, and the pusher 54 is guided by the spring 62.
The cylinder portion 18 is constantly urged in a direction away from the bottom wall 30.

On the other hand, a tapered hole 64 that is removably frictionally engaged with the head 44 of the adjusting bolt 46 is formed in the right side end surface of the pusher 54 in the figure. 44 and the bottom wall 30 of the cylinder portion 18, a thrust bearing 66 and an adjustment bolt 46 are installed between the head 4
A leaf spring 68 is interposed therebetween, which constantly biases the holes 4 and 4 in the direction of engagement with the tapered hole 64. Further, a cylindrical member 52 is attached to the bottom wall 30 of the cylinder portion 18.
A pair of support arms 70 (the other not shown) protrudes across the
A camshaft 74 is rotatably supported through the camshaft 74, and a parking lever 76 is fixed to one end of the camshaft 74. A cam groove 78 is formed approximately at the center in the longitudinal direction of the cam shaft 74, and there is approximately a recess 80 formed on the left side end surface of the pusher 54 in the figure. Eyebrow-shaped toggle 8
2 is interposed. Note that 84 is a slit formed in the pusher 54, and 86 is an adjuster bolt 4.
Although this is a protrusion provided on the head 44 of No. 6, its explanation will be omitted because it has no direct relation to the present invention. Also, 8
8 is a protective cover, 90 is a dust boot, 92 is an O-ring, and 94 is a sealing member for returning the piston 16.

When operating the disc brake equipped with such a parking brake function using hydraulic pressure, the nut member 36 and the adjuster bolt 46
Alternatively, by allowing the relative movement of the piston 16 and the nut member 36 in the axial direction, the adjustment bolt 46 is prevented from moving rightward in the figure, and the head 44 of the adjustment bolt 46 and the pusher 54 are prevented from moving to the right in the figure.
However, when the amount of wear on the pads 24 and 26 exceeds a predetermined limit, the adjustment bolt 46 is moved to the right in the figure together with the piston 16. The frictional engagement is released. As a result, the adjustment bolt 46 is rotated according to the biasing force of the spring 68 and moved toward the left in the figure until it engages with the pusher 54, and the stroke of the parking brake pressing device is always constant. will be maintained.

When the parking brake is operated, when the parking lever 76 is rotated clockwise in the figure by a mechanical operating force transmission means such as a cable (not shown), the cam groove 7 is rotated as the camshaft 74 rotates.
8, the toggle 82 is pushed out to the right in the figure, and the piston 16 is pushed through the pusher 54, the adjustment bolt 46 whose rotation is prevented by frictional engagement therewith, the nut member 36, etc. It is pushed to the right in the figure. As a result, the pad 24 is pressed against the left side surface of the disk rotor 10 in the figure, and the caliper 12 is relatively moved to the left in the figure due to the reaction force, and the pad 26 is pressed against the right side surface of the disk rotor 10 in the figure. As a result, a predetermined parking brake force can be obtained. At this time,
Parking brake pressing device pads 24, 2
6, that is, the toggle 82,
Since the axis B of the pusher 54, adjustment bolt 46, nut member 36, etc. is located on the outer circumferential side of the disc rotor 10 by a predetermined distance L from the axis A of the piston 16, the caliper 12 is not expanded during braking. The parking brake force is applied centering on a position closer to the arm portion 20 where the fulcrum is located when the parking brake is operated, and the expansion of the caliper 12 when the parking brake is operated is suppressed. As a result, it is relatively avoided that a part of the stroke of the parking brake pressing device is consumed with the expansion of the caliper 12, and the effectiveness of the parking brake is further improved compared to the prior art.

Further, according to this embodiment, the center position of the pressing force by the parking brake pressing device is at the piston 16.
Since it is located on the outer circumferential side of the disc rotor 10 with respect to the axis A of
For this reason as well, the effectiveness of the parking brake is further improved compared to the conventional one.

Furthermore, in the past, when the caliper 12 is further expanded due to excessive braking force being applied by hydraulic pressure, the pusher 54 and the like are moved to the cylinder portion 18.
At the same time, the pusher 54 and the adjuster bolt 4 are rotated significantly in the direction away from the adjuster bolt 46 using the arm portion 20 as a fulcrum.
There was a problem in that the frictional engagement with 6 was released and the stroke of the parking brake pressing device was adjusted unnecessarily. In contrast, according to this embodiment, the pusher 5 is located closer to the arm portion 20.
4, etc., the radius of rotation of the pusher 54 becomes smaller than that of the prior art when the caliper 12 is expanded. As a result, even if excessive braking force is applied by hydraulic pressure, the pusher 5
It is effectively prevented that the amount of relative movement of the adjustment bolts 4 to the adjustment bolts 46 becomes small and their frictional engagement is released, and over-adjustment is suppressed.

In the above-mentioned embodiment, a disc brake was described in which a parking brake pressing device was provided on a caliper 12 in which a pair of pads 24 and 26 were pressed against a disc rotor 10 by a single piston 16. However, for example, a caliper may be provided in which a pair of pads are pressed against the disc rotor by separate pistons, or one pad may be pressed against the disc rotor by multiple pistons and the other pad may be pressed against the disc rotor by a plurality of pistons. The present invention can also be applied to a device equipped with a caliper that is pressed by the reaction force, as long as the caliper is disposed straddling the disc rotor.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the main parts of a disc brake with a parking brake function to which the present invention is applied. 10: Disc rotor, 12: Caliper, 1
6: Piston, 18: Cylinder part, 24, 26:
pad, [36: nut member, 46: adjuster bolt, 54: pusher, 74: camshaft, 76: parking lever, 82: toggle] (pressing device for parking brake), A: axis of piston, B:
Axis line (center of pressing force).

Claims (1)

[Claims for Utility Model Registration] A caliper having a cylinder portion into which a piston is slidably fitted and straddling the disc rotor, a pair of pads sandwiching the disc rotor inside the caliper, and a pair of pads provided on the caliper. and a parking brake pressing device that presses the pad based on the parking brake operating force transmitted via the mechanical operating force transmission means, and the parking brake pressing device presses the pad based on the brake operating force transmitted via the hydraulic pressure. is pressed by the piston, and the pad is also pressed by the parking brake pressing device via the piston, in which the pad is pressed by the parking brake pressing device. A disc brake equipped with a parking brake function, characterized in that a center position of the pressing force is located closer to the outer periphery of the disc rotor than the axis of the piston.