JPH0354985Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial application field This invention relates to a brake device equipped with an automatic clearance adjustment mechanism, and attempts to improve automatic clearance adjustment performance and assembly performance by opening the air chamber of the brake device. It is something.

Prior Art In an automatic clearance adjustment device for a disc brake with a parking brake mechanism, a cup-shaped piston that fits into a brake operating cylinder provided in the brake body is connected to a cylindrical portion that slides into the cylinder, and a head that has a smaller diameter than the cylindrical portion. The adjuster is constructed by screwing together an adjustment nut and an adjustment bolt, and the bottom of the cup-shaped piston is in contact with the head of the adjustment nut, and the bottom of the piston and the head of the adjustment nut are in contact with each other. As a prior art of a brake device in which an exhaust passage is provided between a space chamber and the outside air, and the outer end of the exhaust passage is provided in a portion facing a space on the outer periphery of the head portion having a small diameter, for example, Japanese Patent Application Laid-Open No. Showa 52-63560
There is a publication.

Problems to be solved by the invention By the way, the above-mentioned conventional technology is designed to exhaust the space between the bottom of the cup-shaped piston that fits into the brake operation cylinder provided in the brake body and the head of the adjustment nut of the adjuster. This is an automatic disc brake gap adjustment device that is provided with a ventilation hole, but is not provided with a ventilation hole for exhausting the threaded part of the adjustment nut and adjustment bolt that constitute the adjuster. That is, when a cup-shaped piston is assembled into a brake operation cylinder, a vent hole is not provided to gradually remove the increase in internal pressure inside the adjustment nut (threaded part) due to the screwing of the adjustment bolt, and the brake pad A vent hole is provided that communicates with the inside of the adjustment nut (threaded part) in order to eliminate the influence on the adjustment performance of the adjuster due to fluctuations in the internal pressure inside the adjustment nut (threaded part) due to piston movement during wear. Nakatsuta.
The present invention provides an exhaust passage that communicates with the threaded part of the adjustment nut, so that when the cup-shaped piston is assembled to the brake operating cylinder, the pressure inside the adjustment nut (threaded part) due to the threaded adjustment bolt is reduced. The purpose is to eliminate the effect on adjuster adjustment performance due to fluctuations in internal pressure inside the adjustment nut (threaded part) due to piston movement when brake pads wear out. It is something.

Means for Solving the Problems The present invention has been made to solve these problems, and the brake operation cylinder provided in the brake body has a return spring attached to the brake body side behind the cylinder. A pressurized and non-rotatable but movable adjuster nut is mounted on the cup-shaped piston to bring a rotatable adjuster screw into frictional engagement with the piston. A brake operating cylinder with an adjusting nut is installed by being pressed by a set spring, and a cup seal is provided near the open end of the opening of the piston to define the opening of the piston as an air chamber communicating with outside air. In a brake device equipped with an automatic gap adjustment mechanism, which is assembled by fitting and assembling a cup-shaped piston with an adjuster steering screw, the adjuster stays over approximately the entire length of the threaded portion of the adjuster staying screw that is screwed into the adjuster steering nut, or the screw. A brake device is constructed in which a groove deeper than the thread groove is provided even in the shaft portion where the groove is not carved.

Operation The cup-shaped piston 17 is constituted by a cylindrical portion 18 and a small-diameter head portion 19, and the cup-shaped opening 20 of the piston 17 is separated from the cylinder 2 by a cup seal 33 to constitute an air chamber. A vent hole 22 is provided in the cylindrical portion 18 leading from the air chamber to a space on the outer periphery of the small-diameter head portion 19, so that the air chamber can be evacuated;
Since a groove 28 is provided in the shaft portion of the screw 23 which is deeper than the groove extending approximately the entire length of the screw portion 24 of the adjusting screw 23 or the unthreaded cylindrical portion 25 thereof, the screw 2
3, the air in the nut 7 is exhausted through the deep groove 28, and the cup-shaped piston 17 is fitted into the cylinder 2 to form a brake device equipped with an automatic clearance adjustment mechanism. and when,
This makes the assembly easy.

Embodiment The brake body 1 has a brake operation cylinder 2 having an opening on the side facing a disc rotor (not shown) in a part thereof, and a handbrake cylinder 2 is provided on the rear closed end wall 3 of the cylinder 2. (not shown)
A guide hole 6 is formed which communicates with a circular hole 5 into which a cam 4 operated by is inserted. The adjusting nut 7 is composed of a large-diameter cylindrical portion 8 and a truncated conical portion 10 that connects a small-diameter cylindrical portion 9. is formed, and this long hole 11
A multi-thread internal thread 12 is formed on the inner circumferential surface of the holder.
Small diameter cylindrical portion 9 of the adjusting nut 7
is slidably and liquid-tightly fitted into the guide hole 6, and is stopped from rotating by a rotation regulating member 13, and is also pressed against the closed end wall 3 side by a return spring 13 via the rotation regulating member 13. has been done. Therefore, the adjusting nut 7, which is biased to the right in the drawing, is movable in its axial direction, but is provided so that it cannot rotate. The adjusting nut 7 is linked to the cam 4 via a connecting rod 16. The cup-shaped piston 17 is composed of a cylindrical portion 18 that slidably fits into the inner surface of the brake operation cylinder 2 in a fluid-tight manner, and a head portion 19 having a smaller diameter than this portion 18. A cup-shaped opening 20 is formed, and this opening 20 consists of a truncated conical bottom space with a conical surface 21 and a cylindrical space. The adjuster steering screw 23 has a vent hole 22 formed in the cylindrical portion 18 that communicates the left end portion of the cylindrical space with the space on the left side of the edge of the cylindrical portion 18. It is composed of a cylindrical screw portion 24, a cylindrical portion 25 without a male thread, and a head 27 having a conical surface 26 on the outside. It is designed to be screwed together with the female female 12 with a slight back gap. The screw portion 24 is provided with a groove 28 that is deeper than the thread groove of the male thread, and this groove 28 is formed over approximately the entire length of the screw portion 24, and the cylindrical portion 25
It is also formed by extending. This groove 28 may have one or more grooves. Furthermore, although FIGS. 3 and 4 show two straight grooves 28 having a U-shaped cross section, the grooves may have a U-shaped, V-shaped, or other cross-sectional shape. The groove 28 may have a linear shape, a spiral shape, or any other shape, but it is necessary that the groove 28 is in communication over substantially the entire length. Opening 2 of cup-shaped piston 17
0, and the conical surface 26 of the head 27 of the screw 23 is fitted.
is brought into contact with the conical surface 21 at the bottom of the opening 20. In this state, a set spring 30 supported by a circlip 29 inside the cylindrical portion 18 of the piston 17 moves the head 27 of the screw 23 into the opening 23 via a thrust bearing 31.
Press against the conical surface 21 at the bottom of the screw 2.
3 is rotatably mounted within the opening 20 of the cup-shaped piston 17. The right end portion of the cup-shaped opening 20 of the cup-shaped piston 17 has a slightly larger diameter, and a back-up ring 32 and a cup seal 33 are fitted into this portion. The cup seal 33 is prevented from coming off the opening 20 by a circlip 34 provided near the right end of the opening 20. The adjusting screw 23 is pressed against the conical surface 21 at the bottom of the opening 20 of the cup-shaped piston 17 by the set spring 30, and the cup-shaped piston 17 with the adjusting screw 23 is attached, and the adjusting nut 7 is braked by the return spring 14. When assembled to the cylinder 2 with the adjusting nut 7 pressed against the rear closed end wall 3 of the cylinder 2 provided in the main body 1 to constitute a brake device equipped with an automatic clearance adjustment mechanism, the cup seal 3
3 is in liquid-tight sliding contact with the outer circumferential surface of the adjusting nut 7, and the cup seal 33 connects the cup-shaped opening 20 of the cup-shaped piston 17 to the piston 17.
It is defined as a cylinder 2 into which pressure fluid is introduced to operate the cylinder. The cup-shaped opening 18 of the cup-shaped piston 17 defined by the cup seal 33 constitutes an air chamber that communicates with the outside of the piston 17 through the vent hole 22. In addition, 35 is a pressure liquid introduction port. By the way, when assembling the cup-shaped piston 17 with the adjusting screw 23 into the cylinder 2 with the adjusting nut 7 to assemble a brake device equipped with an automatic clearance adjustment mechanism, the piston 1 defined by the cup seal 33 is assembled.
The air in the air chamber of the cup-shaped opening 20 of 7 is released to the atmosphere through the vent hole 22, and the air inside the adjuster steering nut 7 into which the adjuster steering screw 23 is screwed also flows through the groove provided in the screw 23. Released by 28.

Effects of the invention Conventionally, when assembling a brake device equipped with an automatic clearance adjustment mechanism by fitting a cup-shaped piston with an adjusting screw into a cylinder with an adjusting nut, the threaded surfaces of the screw and nut were coated with grease. This obstructs air venting and increases the internal pressure within the nut when the screw is screwed into the nut, which affects the assembly performance of the brake device. In the present invention, a groove 28 deeper than the thread groove of the screw portion is bored in the adjuster steering screw 23, which improves air venting and improves the assembly performance of the brake device. Fluctuations in the internal pressure within the nut 7 were also alleviated, so the adjustment performance of the automatic gap adjustment mechanism was improved. Also, Asia Sting Screw 23
A scratching surface is formed over the inner diameter and outer diameter of the screw by the vertical cut surface of the threaded portion formed by drilling a groove 28 deeper than the thread groove in the screw portion of the screw 23.
The rotation of the screw removes sludge into the groove 28, cleaning the threaded surface, stabilizes the friction coefficient μ of the threaded surface, and improves the automatic clearance adjustment function. Furthermore, the groove 2
By filling groove 8 with grease, that is, groove 2
By setting 8 as a grease reservoir, grease is constantly supplied to the threaded surface, contributing to stabilization of the friction coefficient μ. Furthermore, the cup type piston 1
The head portion 19 of the piston 17 has a diameter smaller than that of the cylindrical portion 18, and a vent hole 22 is provided in the cylindrical portion 18 to communicate a space on the outer periphery of the head portion 19 with the small diameter and an air chamber of the opening 18 of the piston 17. If provided, the header processing of the piston can be done in one go with a press, which has the remarkable effect of reducing costs.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of the main part of the brake device of the present invention when the cup-shaped piston is assembled to the cylinder, FIG. 2 is a longitudinal cross-sectional view of the main part of the brake device of the present invention when the cup-type piston is assembled to the cylinder, FIG. 3 is a rear view of the adjusting screw, and FIG. 4 is a side view of the adjusting screw. In the figure, 1 is the brake body, 2 is a brake operation cylinder, 7 is an adjusting nut, 11 is a long hole, 12 is a multi-thread female thread, 14 is a return spring, 17 is a cup-shaped piston, 18 is a cylindrical part, 19 is a head part, 20 is a cup-shaped opening,
22 is a ventilation hole, 23 is an adjusting screw, 24 is a cylindrical screw portion with multiple male threads, 25 is a cylindrical portion with no male threads,
28 is a deep groove, 30 is a set spring, and 33 is a cup seal.

Claims (1)

[Claims for Utility Model Registration] (1) The brake operating cylinder 2 provided in the brake body 1 is pressed by a return spring 14 on the side of the brake body 1 at the rear of the cylinder 2, and cannot rotate. A movable adjusting nut 7 is attached to the cylinder 2 in the axial direction, and a rotatable adjusting screw 2 is attached to the cup-shaped piston 17.
3 is pressed and attached by a set spring 30 so as to frictionally engage the piston 17, and the opening 20 of the piston 17 is opened to define the opening 20 of the piston 17 as an air chamber communicating with outside air. In the brake device equipped with an automatic clearance adjustment mechanism, a cup seal is provided near the end, and the brake operating cylinder 2 with the adjuster steering nut 7 and the cup-shaped piston 17 with the adjuster steering screw 23 are fitted and assembled. A brake characterized in that a groove 28 deeper than the thread groove is provided over substantially the entire length of the threaded portion of the adjusting screw 23 that is screwed into the staying nut 7, or even over the shaft portion where no thread is carved. Device. (2) The brake device according to claim 1, wherein a plurality of deep grooves 28 are provided in the threaded portion of the adjusting screw 23. (3) The head portion 19 of the cup-shaped piston 17 has a smaller diameter than the cylindrical portion 18 thereof, and a vent hole is provided in the cylindrical portion 18 to connect a space on the outer periphery of the head portion 19 with the smaller diameter and the air chamber. 22. The brake device according to claim 1, which is a utility model.