JP2002005119A - Installing structure of cushion valve and variable cushion cylinder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent leakage of fluid when a cushion valve falls off from a cylinder tube (a cover). SOLUTION: When making an adjustment (an adjustment in the direction for reducing cushion pressure) for moving this cushion valve 40 outside in the shaft direction by rotating the cushion valve 40 by loosening a looseness preventive nut 44, even if the moving distance is erroneously adjusted, since a seal part (a blocking-up part) 41 of the cushion valve 40 abuts to a step part 45 between a small diameter female screw hole 37 and a large diameter hole 36 of a plug 35, the cushion valve 40 itself is prevented from slipping out to the outside in the cover radial direction, and does not slip off.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable cushion cylinder and a cushion valve in which at a stroke end of a piston, a cushion pressure generated by a fluid sealed in a cylinder chamber ahead of the piston in the traveling direction can be appropriately adjusted by a cushion valve. Mounting structure.

[0002]

2. Description of the Related Art For example, in Japanese Utility Model Laid-Open Publication No. 58-89603, Japanese Utility Model Publication No. Sho 59-21284, and Japanese Patent Application Laid-Open No. 2000-130408, fluid is supplied to and discharged from a cylinder chamber to an end member (cover) for closing an end of a cylinder tube. And a cushion communication passage communicating the port with the cylinder chamber is formed, and a cushion valve (throttle valve) formed at the tip of a tapered needle portion is provided in the middle of the cushion communication passage. It is screwed into the end member from the outside of the end member so that the position can be adjusted in the radial direction of the cylinder tube. By rotating the cushion valve itself, the tube radial position of the cushion valve is changed by screw connection with the end member. The position of the needle portion at the end) with respect to the cushion communication passage is changed to change the flow passage area of the cushion communication passage, so that the position in front of the piston in the traveling direction is changed. That the fluid Fujikoma the cylinder chamber that escape from the supply and discharge port through the communication passage cushion, are to be able to change the cushion pressure appropriately.

[0003]

The work of changing the cushion pressure is often performed by the end user. Conventionally, as described above, since the cushion valve is screwed into the end member from the outside, when the cushion valve is moved outward to reduce the cushion pressure, the cushion valve is formed. The thread itself may come off from the internal thread of the end member, and as a result, the cushion valve itself may fall off from the end member, leak fluid, and pollute the surroundings. According to the present invention, a cushion valve movable in an axial direction is provided.
An object of the present invention is to provide a valve mounting structure for preventing the valve from falling off and a cylinder having the structure.

[0004]

In order to solve the above problem, in the cushion valve mounting structure according to the first aspect of the present invention, a cushion communication passage is provided between a cylinder chamber and a supply / discharge port communicating with the cylinder chamber. A cushion valve is provided in the cushion communication passage so that the position in the axial direction can be adjusted, and the fluid sealed in the cylinder chamber located forward in the traveling direction of the piston is discharged from the supply / discharge port through the cushion communication passage. In a variable cushion cylinder in which the cushion pressure can be adjusted, the cushion valve is attached to the cylinder tube so as not to come off. When the cushion valve is adjusted, the cushion valve does not come off from the cylinder tube (the cover integral therewith) due to the stopper.

More specifically, a plug is attached to a member having a cushion communication passage formed from the outside of the cylinder tube in the radial direction, and the plug has a stepped hole having a large-diameter hole on the radial inside. A through hole is formed, the seal part of the cushion valve is mounted inside the large diameter hole of the stepped through hole so as to be movable in the axial direction, and the thread part of the cushion valve is screwed into the small diameter screw hole of the stepped through hole. The seal portion of the cushion valve is engaged with the step portion between the small-diameter female screw hole and the large-diameter hole so as to prevent the cushion valve from falling outside in the tube radial direction (claim 2). A supply / discharge port and a cushion communication passage are formed in a cover for closing an end of the cylinder tube.

Further, the variable cushion cylinder of the present invention
Cover the end of the cylinder tube with a cover.
A supply / discharge port communicating with the piston chamber between the cover and the piston movably fitted in the tube, and a cushion communication passage communicating the supply / discharge port with the piston chamber; Cushion valve provided in the communication passage in the tube radial direction adjusts the flow area of the cushion communication passage in a variable cushion cylinder with a small diameter male thread and a large diameter connected to the needle. A cushion valve with a closing part,
A plug having a large-diameter hole and a stepped through-hole formed of a smaller-diameter female screw hole is attached to the plug from the large-diameter hole side, and the plug is covered from the outside of the cover so that the needle portion is located in the cushion communication passage. (Claim 4).
According to this, even if the cushion valve is rotated from the outside of the cover in the direction of moving outward in the axial direction, since the closing portion abuts the step portion between the large-diameter hole and the internal thread portion, it cannot be further moved, The cushion valve does not fall off the cover while adjusting the cushion valve. At the end of the cylinder tube, a female screw hole into which the fitting shaft of the cover is screwed is formed, and a cushion seal is disposed between the bottom of the female screw hole and the end face of the cover. . In this configuration, since the cover itself does not have a holding groove or the like for holding the cushion seal, the cushion seal can be easily attached even when the cover provided with the cushion communication path is thin.

[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 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 the sealing of the fitting portion 17 in this manner, the fluid in the cylinder chamber (in this case, the rod-side cylinder chamber 25) forward in the traveling direction of the piston 18 is sealed, and the fluid is transferred from the rod-side cylinder chamber 25 to the cushion seal. 12, a gap between the outer periphery of the screw hole 4a and the inner surface of the screw hole 4a,
0, the recess 21 through the screw hole 31 and the second communication passage 32
And 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 surface of the cushion seal 12 at the stroke end,
Immediately before the pressure contact, the fluid in the rod-side cylinder chamber 25 is
The fluid flows into the cushion communication path via the groove 13 of the cushion seal 12. Supply / discharge port 23 of rod cover 5
Needless to say, if the pressurized fluid is supplied to the rod-side cylinder chamber 25 from above, the piston 18 moves in the direction opposite to the above, and the same cushioning action as described above occurs at the head-side stroke end.

[0014]

As described above, according to the present invention, when the cushion valve is adjusted, the cushion valve does not fall off the cylinder tube (cover) due to the stopper, thereby preventing fluid leakage. In addition, in the present invention, since the holding groove for holding the cushion seal is not formed in the cover itself, the cushion seal can be easily mounted even in a small-diameter cylinder in which the thickness of the cover provided with the cushion communication passage is reduced.

[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 part of female thread hole 12 Cushion seal 17, 19 Fitting shaft part 18 Piston 23, 24 Supply / discharge port 25 Rod side cylinder chamber 26 Head Side cylinder chamber 35 Plug 36 Large diameter hole 37 Female thread hole 38 Stepped through hole 40 Cushion valve 41 Seal part (blocking part) 43 Male thread part 45 Step part

Claims (5)

[Claims] A cushion communication passage is provided between a cylinder chamber and a supply / discharge port communicating with the cylinder chamber, and a cushion valve is provided in the cushion communication passage so that an axial position can be adjusted. In a variable cushion cylinder capable of adjusting a cushion pressure by discharging a fluid sealed in a cylinder chamber located forward in a traveling direction from a supply / discharge port through a communication passage for a cushion, the cushion valve is moved relative to a cylinder tube. The mounting structure of the cushion valve, which is attached to prevent it from falling off. 2. A plug having a stepped through-hole having a large-diameter hole on the inside in the radial direction is attached to the member having the communication passage for the cushion, the plug being attached to the member from the radial outside of the cylinder tube. The seal part of the cushion valve is installed inside the large diameter hole of the stepped through hole so as to be movable in the axial direction, and the screw part of the cushion valve is screwed into the small diameter screw hole of the stepped through hole to reduce the diameter. 2. The cushion valve mounting structure according to claim 1, wherein a seal portion of the cushion valve is engaged with a step portion between the screw hole and the large-diameter hole so as to prevent the cushion valve from falling outside in the tube radial direction. 3. The cushion valve mounting structure according to claim 1, wherein a supply / discharge port and a communication passage for cushion are formed in a cover for closing an end of the cylinder tube. 4. A supply / discharge port communicating with a piston chamber between the cover and a piston movably fitted in the tube, and a supply / discharge port thereof. And a communication passage for the cushion communicating the piston chamber with the piston chamber. The flow passage area of the communication passage for the cushion is made variable by adjusting the radial position of the cushion valve provided in the communication passage for the cushion in the tube radial direction. In a variable cushion cylinder, a cushion valve with a small-diameter male screw part and a large-diameter closing part connected to the needle part is plugged with a large-diameter hole and a stepped through hole consisting of a smaller-diameter female screw hole. A variable cushion series which is attached to the cover from the outside of the cover so that the needle portion is located in the communication passage for the cushion. Nda. 5. A female screw hole into which the fitting shaft of the cover is screwed is formed at an end of the cylinder tube, and a cushion seal is disposed between the bottom of the female screw hole and the end face of the cover. The variable cushion cylinder according to claim 4, characterized in that: