JP2002005118A - Cushion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cushion device applicable to a small diameter cylinder. SOLUTION: A cushion seal 12 can move a little in the shaft direction and the radial direction in a state of being sandwiched between a rod cover end surface 9 and a bottom part 11 of a screw prepared hole 4a. The cushion seal 12 can be easily arranged even when forming a cushion communicating hole composed of a first communicating hole 30 in the small diameter cylinder thinning in the thickness of a fitting shaft part 7 of a cover 5 by this structure for forming no installing recessed part for fitting the cushion seal 12 in an opening edge part of a recessed part 21 in the cover 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cushion valve in which, at a stroke end of a piston, a fitting portion provided on the piston fits into a cushion seal and is sealed in a cylinder chamber located forward in the traveling direction of the piston. The present invention relates to a cylinder cushion device configured to discharge from a supply / discharge port via a cushion communication passage having the same.

[0002]

2. Description of the Related Art For example, Japanese Patent Application Laid-Open No. 2000-130408 discloses that a shaft portion of a cover is screwed into an end of a cylinder tube to close the cover. And a supply / discharge port, and a cushion seal is fitted into an edge of the piston-side opening of the recess, and the cover has an opening at a cover end face, and the cover end face and the piston are connected to each other. There is disclosed a cushion communication passage communicating between the cylinder chamber and the recess, and a cushion valve is disposed in the middle of the communication passage, and a fitting portion of the piston is fitted into the cushion seal. When the fluid is trapped, the fluid sealed in the cylinder chamber ahead of the piston in the traveling direction is supplied to the supply / discharge port via the cushion communication passage whose flow rate is controlled by the cushion valve. By escape, so as to twist cushion piston stroke end of the piston.

[0003]

In the above-mentioned structure, the communication passage for the cushion is provided in the fitting shaft portion of the cover, and the fitting step for fitting the cushion seal is formed at the entrance of the recess at the center of the piston. ing. For this reason, in a cylinder having a large cylinder tube diameter that can increase the thickness between the outer periphery of the fitting shaft portion and the concave portion in the fitting shaft portion of the cover, the fitting step portion for attaching a cushion seal may be provided. Although it is easy, in a cylinder having a small cylinder tube diameter, there is a problem that such a fitting step cannot be formed since the thickness of the fitting shaft portion of the cover becomes thin. An object of the present invention is to provide a cushion device including a cushion communication passage and a cushion seal, which is suitable for being applied to a small-diameter cylinder. Also,
Another object of the present invention is to provide a structure in which when a fitting portion of a piston fits into a cushion seal, it fits without misalignment and enhances sealing performance at a fitting portion.

[0004]

According to a first aspect of the present invention, a fitting shaft portion of a cover is screwed into an end of a cylinder tube, and a fitting provided on a piston moving in the tube. In the cylinder, the joint portion is fitted into the cushion seal at the stroke end, and the fluid sealed in the cylinder chamber ahead of the piston in the traveling direction is discharged from the supply / discharge port through the cushion communication passage formed in the cover. The cushion seal is disposed between the bottom of the female screw hole formed at the end of the cylinder tube and the end face of the cover. Since a step portion for mounting a cushion seal is not formed on the end face of the cover, it can be used even in a small-diameter cylinder having a thin cover. The cushion seal is mounted movably in the diameter direction with respect to the female screw hole (claim 2). According to this, when the fitting portion fits into the cushion seal, the cushion seal can move in the radial direction following the fitting portion, so that the center hole of the cushion seal and the fitting portion are fitted without misalignment. In particular, when the cushion seal is a metal seal, the fluid leakage at the fitting portion (between the center seal hole of the cushion seal and the fitting portion) becomes constant, and the dynamic resistance change due to the leakage fluid is reduced. Small, stable cushion effect can be expected.

[0005] One end of the cushion communication passage is open at the end face of the cover, which is the back face of the cushion seal, and a communication cutout is formed in the end face of the cover from the outer periphery in the radial direction to the opening. ). In addition, a radial groove is provided on the piston-side end surface of the cushion seal (claim 4). According to this, the fluid sealed in the cylinder chamber forward in the traveling direction of the piston is a space between the outer periphery of the cushion seal and the inner surface of the female screw hole, a communication cutout,
It is discharged to the supply / discharge port via the cushion communication passage.

The cushion valve provided in the cushion communication passage is capable of adjusting the position in the axial direction and adjusting the cushion pressure. An appropriate cushion pressure can be selected according to the piston moving speed or the like.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a cylinder 1 shown in FIG.
The hollow cylinder tube 2 has a center hole formed as a cylinder hole 3, and both end portions thereof are formed in a female screw hole 4 having a predetermined length in the axial direction and a larger diameter than the cylinder hole 3. The female screw hole 4 includes a screw lower hole 4a and a female screw portion 4b. The fitting shaft portions 7 and 8 of the rod cover 5 and the head cover 6 are respectively screwed into these female screw holes 4 to close both ends of the cylinder tube 2. The fitting shaft portions 7 and 8 are screwed into the cylinder tube 2 and the inner end surfaces 9 and 10 thereof.
The length of the cushion seal 12 in the axial direction is set so as to form a space S for accommodating the cushion seal 12 between the screw hole 4a and the bottom portion (end surface) 11 of the screw hole 4a.

The diameter of the cushion seal 12 is slightly smaller than the diameter of the screw hole 4a, and the thickness in the axial direction is smaller than the dimension of the accommodation space S in the axial direction. When the cushion seal 12 is sandwiched between the rod (head) cover end surface 9 (10) and the bottom 11 of the screw hole 4a, the cushion seal 12 is slightly movable in the axial direction and the radial direction. The cushion seal 12 has a radial groove 13 formed in an end face facing the piston 13. Unlike the related art, the mounting recess for fitting the cushion seal 12 is not formed at the opening edge of the recess 21 (22) in the cover 5 (6), and thus the fitting shaft 7 ( Even when the cushion communication hole including the first communication passage 30 is formed in the small-diameter cylinder in which the thickness is reduced, the cushion seal 12 can be easily arranged. The cushion seal 12 is a metal seal made of a bronze casting here.

The rear thin shaft portion 16 of the piston rod 15 is
These members are integrally connected by a nut 20 which penetrates the fitting portion 17 on the rod side, the piston 18 sliding in the cylinder hole, and the fitting portion 19 on the head side, and screwed to the rear end. ing. As shown in FIG. 2, the piston rod 15 penetrates the rod cover 5 and protrudes to the outside. At the center of the rod (head) cover 5 (6), there is provided a concave portion 21 (22) into which the corresponding fitting portion 17 (19) enters. The rod (head) cover 5 (6) is provided with a supply / discharge port 23 (24) for pressure fluid, and the supply / discharge port 23 (24) communicates with the concave portion 21 (22), and the fitting portion 17 ( 19) is communicated with the rod-side (head-side) cylinder chamber 25 (26) through the seal hole 12a of the cushion seal 12 for sealing.

Since the rod cover 5 and the head cover 6 have the same structure, the rod cover 5 will be described below. As shown in FIG. 2, in the rod cover 5, the fitting shaft portion 7 is formed with a first communication hole 30 in the axial direction whose one end is open to the cover end surface 9. Screw-in hole 31 of the cushion mounting plug orthogonal to the first communication hole 30
The other end of the first communication hole 30 is screwed into a screw hole 31.
It is open to. The screw hole 31 and the concave portion 21
It communicates via a small diameter second communication hole 32 concentric with the screw hole 31. A screw hole 31 from the first communication hole 30;
The path leading to the recess 21 via the second communication hole 32 is a communication path for the cushion. On the end face 9 of the rod cover 5 facing the back surface of the cushion seal 12, a communication notch 33 is formed to reach the opening of the first communication hole 30 at a predetermined depth in the axial direction.

A plug 35 for mounting a cushion valve is screwed into the screw hole 31 from outside the rod cover 5 (cylinder 1) at right angles to the cylinder axis. An anaerobic adhesive or the like is applied to the screw portion for sealing and preventing loosening. In the plug 35, a stepped through hole 38 is formed in which, in the mounted state, a large-diameter hole 36 is formed on the inside in the radial direction and a small-diameter female screw hole 37 is formed on the outside.

The cushion valve 40 has a tapered needle portion 42 projecting from a large-diameter seal portion (blocking portion) 41, and has a small-diameter external thread portion 43 on the side opposite to the needle portion 42. The cushion valve 40 is attached to the plug 35 from the large-diameter hole 36 side of the stepped through hole 38, and the male thread portion 43 of the cushion valve 40 is screwed into the small-diameter female screw hole 37 to form the large-diameter hole 36. After the seal portion 41 of the cushion valve 40 is mounted so as to be movable in the axial direction, the plug 3
The plug 35 is screwed into the rod cover 5 from outside so that the needle portion 42 of the cushion valve 40 is located in the second communication passage 32 of the cushion communication passage. And attach it. If the cushion valve 40 is moved inward in the axial direction by loosening the locking nut 44 and rotating the male screw portion 43, the needle portion 42 moves in a direction to close the second communication hole 32. When the cushion valve 40 is moved outward in the axial direction, the closed needle part 42 moves away from the second communication hole 32 to increase the flow path area. The cushion pressure of the fluid discharged through the cushion communication passage is variable. Then, the cushion valve 40 is
When adjustment is performed to move the cushion valve 40 outward in the axial direction (adjustment in a direction to reduce the cushion pressure) by mounting the cushion valve 40 as described above via the plug 35, the adjustment movement amount is erroneously increased. Even if it is attempted, since the sealing portion 41 of the cushion valve 40 abuts on the step portion 45 between the small diameter female screw hole 37 and the large diameter hole 36, the cushion valve 40 itself is prevented from falling outside in the tube radial direction and falls off. There is no.

When a pressure fluid (pressure oil) is supplied from the head cover 6 side in FIG. 1, the fluid in the rod side cylinder chamber 25 is
The piston 18 is discharged from the supply / discharge port 23 of the rod cover 5 through the seal hole 12 a of the cushion seal 12 and the concave portion 21, and the piston 18 moves to the rod cover 5 side. When reaching the vicinity of the stroke end, the fitting portion 17 on the rod side enters the seal hole 12a of the cushion seal 12 on the rod cover 5 side (FIG. 2). At this time, since the cushion seal 12 can freely move in the radial direction of the piston 18, the seal hole 12a is fitted so as to follow the fitting portion 17, and the fitting portion 17 and the seal hole 12 are fitted without misalignment. . By fitting without misalignment in this way, the amount of fluid leakage at the fitting portion is more stable than when fitting with misalignment, and the dynamic resistance change of the fluid is reduced, A stable cushion effect can be expected.

By sealing the fitting portion 17 in this manner, the fluid in the cylinder chamber (in this case, the rod-side cylinder chamber 25) forward of the piston 18 in the traveling direction is contained, and the fluid is confined to the rod-side cylinder chamber 25. From the outer periphery of the cushion seal 12 and the inner surface of the screw hole 4a, the notch 33 of the rod cover end surface 9, the first communication passage 30, the screw hole 31, and the second communication passage 32 to reach the concave portion 21, It is discharged from the supply / discharge port 23. Since the flow passage area of the second communication passage 32 is appropriately adjusted and narrowed by the needle portion 42 of the cushion valve 40, an appropriate cushion pressure is generated in the fluid in the rod-side cylinder chamber 25 due to the resistance, and the piston pressure is reduced. Reference numeral 18 gradually stops at the stroke end on the rod side. The piston 18 comes into pressure contact with the piston-side end face of the cushion seal 12 at the stroke end. Immediately before the pressure contact, the fluid in the rod-side cylinder chamber 25 flows into the cushion communication passage via the groove 13 of the cushion seal 12. When the pressurized fluid is supplied from the supply / discharge port 23 of the rod cover 5 to the rod-side cylinder chamber 25, the piston 18 moves in the opposite direction, and the same cushioning action as described above occurs at the head-side stroke end. No.

[0015]

As described above, the cushion device of the present invention does not form a step for mounting a cushion seal on the end face of the cover screwed into the end of the tube, so that it can be used even in a small-diameter cylinder having a thin cover. . Further, in the present invention, since the cushion seal is movably fitted in the female screw hole in the diameter direction, when the fitting portion fits into the cushion seal, the cushion seal follows the fitting portion. The cushion can be moved in the radial direction, the center hole of the cushion seal and the fitting portion can be fitted without misalignment, and a stable cushioning effect can be expected.

[Brief description of the drawings]

FIG. 1 is a sectional view of a hydraulic cylinder embodying the present invention.

FIG. 2 is an enlarged sectional view of a rod cover portion.

FIG. 3 is an enlarged cross-sectional view taken along the line III-III of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder 2 Cylinder tube 4 Female thread hole 5 Rod cover 6 Head cover 9, 10 Cover end face 11 Bottom of female thread hole 12 Cushion seal 13 Groove 17, 19 Fitting shaft part 18 Piston 23, 24 Supply / discharge port 25 Rod side cylinder chamber 26 Head side cylinder chamber 33 Communication cutout 35 Plug 36 Large diameter hole 37 Female screw hole 38 Stepped through hole 40 Cushion valve 41 Seal part (blocking part) 43 Male thread part 45 Step part

Claims (5)

[Claims] 1. A fitting shaft portion of a cover is screwed into an end of a cylinder tube, and a fitting portion provided on a piston moving in the tube is fitted into a cushion seal at a stroke end, so that a piston In a cylinder configured to discharge a fluid contained in a cylinder chamber located forward in a traveling direction from a supply / discharge port through a cushion communication passage formed in a cover, a bottom portion of a female screw hole formed at an end of a cylinder tube. A cushion device comprising a cushion seal interposed between the cover and an end face of the cover. 2. The cushion device according to claim 1, wherein the cushion seal is mounted so as to be diametrically movable with respect to the female screw hole. 3. An end of a cushion communication passage is opened at an end face of a cover serving as a back surface of a cushion seal, and a communication cutout is formed in the end face of the cover so as to reach the opening from the outer periphery in the radial direction. 2. The cushion device according to 2. 4. The cushion device according to claim 1, wherein a radial groove is provided on a piston-side end surface of the cushion seal. 5. The cushion device according to claim 1, wherein the cushion valve provided in the cushion communication passage is capable of adjusting an axial position and adjusting a cushion pressure.