JP2541634Y2 - Piston assembly - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a piston assembly incorporated in a hydraulic cylinder.

[0002]

2. Description of the Related Art Conventionally, as one type of fluid pressure cylinder, as shown in FIG.
Assemble the piston assembly 3 and the pulley 4 to the cylinder 1
The rod 2 is reciprocated in the axial direction by supplying fluid pressure to the inside, and torque from a rotary drive source such as a motor (not shown) is transmitted to the rod 2 via the pulley 4 to rotate the rod 2. Things are known. The piston assembly 3
As shown in FIG. 3, the piston body 5 is directly fitted on the outer periphery of the rod 2, and the outer peripheral side seal 6 fitted on the outer periphery of the piston body 5 is axially and circumferentially attached to the inner peripheral wall of the cylinder 1. In sliding contact with both sides. A rubber-like elastic body such as a packing is used for the outer peripheral side seal 6.

[0003]

In the above prior art, since the outer peripheral seal 6 completely follows the movement of the rod 2 via the piston body 5, the rod 2 performs the combined movement of the reciprocating movement and the rotating movement. In this case, there is a problem that a large sliding resistance is generated on the outer peripheral side seal 6, so that the outer peripheral side seal 6 is severely worn and the loss of the transmission torque is large.
Further, when the piston assembly 3 comes into contact with the axial end wall of the cylinder 1 at the reciprocating stroke end, a large impact force is directly applied to the piston body 5.

[0004]

SUMMARY OF THE INVENTION In view of the above, the present invention has been devised in order to solve the above-mentioned problems in the prior art. A stopper axially engaged with the formed engaging groove, a guide and a cover fitted to the outer periphery of the rod, sandwiching the stopper from both sides in the axial direction, and connected to each other; A piston body rotatably fitted to the outer periphery via a radial bearing, a seal interposed between the rod and the guide, and an inner peripheral side seal interposed between the guide and the piston body And an outer peripheral side seal fitted to the outer periphery of the piston main body, wherein the guide and the cover have axial ends respectively projecting in the axial direction from the axial end of the piston main body. Characteristic fixie To provide the assembly.

[0005]

A guide is fitted on the outer periphery of the rod, the piston body is rotatably fitted on the outer periphery of the guide via a radial bearing, and an outer peripheral seal is fitted on the outer periphery of the piston main body. The piston body does not follow the rod even if the rod rotates by utilizing the frictional resistance against the inner peripheral wall of the cylinder. The stopper is axially engaged with the engaging groove formed on the outer peripheral surface of the rod, the stopper is sandwiched between the guide and the cover, and the axial ends of the guide and the cover are respectively pivoted from the axial ends of the piston body. The guide, the cover, and the stopper receive an impact force when the piston assembly abuts on the axial end wall of the cylinder at the reciprocating stroke end.

[0006]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.

As shown in FIG. 1, an annular engaging groove 7a is formed on the outer peripheral surface of the rod 7, and an annular stopper 8 which is divided into two is engaged with the engaging groove 7a. An annular guide 9 is fitted on the outer periphery of the rod 7 from the left side in the figure, and an annular cover 10 is fitted from the right side in the figure.
Are screwed to each other at a screwing portion 11 with a stopper 8 interposed therebetween. The guide 9 and the cover 10 are fixed to the rod 7 in the axial direction and the circumferential direction, respectively. An annular piston body 13 is rotatably fitted on the outer periphery of the guide 9 via a radial bearing 12, and an annular mounting groove 13 a formed on the outer peripheral surface of the piston body 13.
An annular outer-side seal 14 for sealing between the piston body 13 and an inner wall of a cylinder (not shown) is fitted to the piston body 13. An annular mounting groove 13 is formed on the inner peripheral surface of the piston body 13.
An annular inner circumferential seal 15 for sealing between the guide 9 and the piston body 13 is fitted in the mounting groove 13b. An annular mounting groove 7b is formed on the outer peripheral surface of the rod 7.
An annular seal 16 for sealing between the rod 7 and the guide 9 is fitted in the mounting groove 7b. Reference numeral 17 denotes an annular magnet acting as a part of a magnetic proximity switch for detecting a stroke, and is attached to the outer periphery of the guide 9 by a spacer 18. The spacer 18 is screwed to the guide 9 at a screwing portion 19. Screw part 1
The guide 9 and the cover 10 screwed in 1 are formed so that their axial length is longer than the axial length of the piston body 13.
a, 10a to the axial end 13c, 1 of the piston body 13.
It protrudes in the axial direction from 3d.

When torque from a rotary drive source such as a motor (not shown) is transmitted to the rod 7 and the rod 7 rotates, the stopper 8, the guide 9, the cover 10, the seal 16,
The magnet 17 and the spacer 18 rotate completely following, but the piston body 13 is rotatably fitted to the guide 9 via the radial bearing 12 and the piston By setting the frictional resistance against the inner peripheral wall (not shown) larger than the frictional resistance against the guide 9 of the inner peripheral side seal 15, the rod 7 does not completely follow and rotate, and accordingly the outer peripheral part is not rotated. The sliding resistance of the side seal 14 can be reduced, and wear of the outer peripheral side seal 14 and loss of transmission torque can be suppressed. A stopper 8 is axially engaged with an engaging groove 7a formed on the outer peripheral surface of the rod 7, and the stopper 8 is sandwiched between a guide 9 and a cover 10, and axial ends 9a, 10a of the guide 9 and the cover 10 are provided. Are projected in the axial direction from the axial ends 13c and 13d of the piston body 13, respectively, and the axial ends 9a and 10a of the guide 9 and the cover 10 are respectively moved at the stroke ends of the reciprocating motion in the axial end walls of the cylinder (FIG. (Not shown), the guide 9, the cover 10, and the stopper 8 receive an impact force, so that a large impact force can be prevented from being directly applied to the piston body 13.

The illustrated outer seal 14, the inner seal 15 and the seal 16 are each constituted by a single two-way seal and perform their respective sealing functions. It is optional as long as the sealing action can be achieved, for example, as a non-conductive seal. Although the illustrated rod 7 is a hollow body, it may be a solid body. Further, shock absorbers 20 as shown in the drawings may be attached to the axial ends 9a, 10a of the guide 9 and the cover 10, respectively.

[0010]

[Effects of the Invention] The present invention has the following effects. That is,
A guide is fitted on the outer periphery of the rod, the piston body is rotatably fitted on the outer periphery of the guide via a radial bearing, and an outer peripheral seal is fitted on the outer periphery of the piston main body. Even if the rod rotates by utilizing the frictional resistance against the peripheral wall, the piston body is prevented from rotating following the rod, so that the sliding resistance of the outer peripheral side seal is reduced and the wear and transmission of the outer peripheral side seal are reduced. Torque loss can be suppressed. The stopper is axially engaged with the engaging groove formed on the outer peripheral surface of the rod, the stopper is sandwiched between the guide and the cover, and the axial ends of the guide and the cover are respectively pivoted from the axial ends of the piston body. The guide, the cover, and the stopper receive the impact force by the guide, the cover, and the stopper. It is possible to prevent a large impact force from being directly applied to the main body.

[Brief description of the drawings]

FIG. 1 is a sectional view of a piston assembly according to an embodiment of the present invention.

FIG. 2 is a sectional view of a hydraulic cylinder.

FIG. 3 is a sectional view of a conventional piston assembly.

[Explanation of symbols]

 7 Rod 7a Engagement groove 7b, 13a, 13b Mounting groove 8 Stopper 9 Guide 9a, 10a, 13c, 13d Axial end 10 Cover 11, 19 Threaded part 12 Radial bearing 13 Piston main body 14 Outer peripheral seal 15 Inner peripheral side Seal 16 Seal 17 Magnet 18 Spacer 20 Buffer

Continuation of the front page (56) References JP-A 3-305 (JP, U) JP-A 63-137104 (JP, U) JP-A 3-38403 (JP, U) JP-A 47-19697 (JP) , U) Japanese Utility Model Showa 63-170603 (JP, U) Japanese Utility Model Showa 64-17008 (JP, U) Japanese Utility Model Showa 40-25944 (JP, Y1)

Claims (1)

(57) [Scope of request for utility model registration] An engaging groove formed on an outer peripheral surface of a rod.
A stopper 8 axially engaged with the rod 7 and the rod 7
A guide 9 and a cover 10 which are fitted on the outer periphery of the
A piston body 13 rotatably fitted on the outer periphery of the guide 9 via a radial bearing 12;
A seal 16 interposed between the piston 9 and the guide 9, an inner peripheral seal 15 interposed between the guide 9 and the piston body 13, and an outer peripheral side fitted to the outer periphery of the piston body 13 A piston having a seal and projecting axial ends 9a and 10a of the guide 9 and the cover 10 from axial ends 13c and 13d of the piston body 13, respectively. Assembly.