JP2001146908A - Cushioning device of hydraulic cylinder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the interference of a cushion ring to a cushion seal and to minimize the power loss in the compressing operation in a cushioning stroke. SOLUTION: This cushioning device of a hydraulic cylinder comprises a cushion ring 6 having a tapered surface 5 formed on a base end of a piston rod 2, and a cushion seal 24 having the checking function and mounted on an inner surface of a cylinder tube 11 corresponding to the cushion ring 6 axially displaceably through a holder 19. The device provides the cushioning effect by fitting the cushion ring 6 in the cushion seal 24 following the elongating motion near the maximum elongation of a hydraulic cylinder 1, and gradually reducing the area of a slit 31 formed by an inner diameter surface of the cushion seal 24 and a tapered surface 5 of the cushion ring 6. An oil path between the holder 19 and the cushion seal 24 is formed by a series of grooves 32 formed on an inner peripheral surface of the holder 19 over a predetermined range from a flange part 22 at a point to a position reaching a point of a collar 18 toward the axial direction along an inner peripheral surface of the holder 19.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cushion device at the time of terminal operation of a hydraulic cylinder, and more particularly, to communication between a hydraulic oil chamber on the rod side and a supply / discharge port in accordance with an extension operation near the maximum extension of the hydraulic cylinder. The present invention relates to an improvement in a cushion device for a hydraulic cylinder that provides a cushioning effect by gradually reducing a slit area of a restricting oil passage.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 8, a hydraulic cylinder 1c provided with this kind of terminal cushion device has a cushion having a tapered surface 5 on the outer peripheral surface at the base end of a piston rod 2 in contact with a piston 4. The ring 6 is arranged, and the holder 19 is brought into contact with the cylinder head 7 so as to face the cushion ring 6. Is held so as to be displaceable while restricting the movement.

In this case, the cushion seal 24
c is configured so that the diameter of the outer peripheral surface is smaller than the diameter of the inner peripheral surface of the holder 19 to form an axial oil passage 25 between the two.
By pressing the cushion seal 24c against the collar 18, the axial oil passage 25 is closed.

On the other hand, the axial oil passage 25 is formed by a radial oil passage 26 formed on the outer surface of the cushion seal 24c, regardless of whether the holder 19 is pressed against the flange 22 side.
2 is always connected to the hydraulic oil chamber 16 on the rod side.

Thus, during the extension operation before the cushion ring 6 is fitted into the cushion seal 24c, the hydraulic cylinder 1c pushes out the hydraulic oil in the hydraulic oil chamber 16 on the rod side from the supply / discharge port 27 with almost no resistance and extends. The cushion ring 6 is the cushion seal 2
4c, the return oil path resistance increases instantaneously, the hydraulic oil pressure in the hydraulic oil chamber 16 on the rod side increases, and the cushion seal 24c is pressed against the collar 18 so that the axial oil is pressed. Road 25 is closed.

As a result, the hydraulic cylinder 1c causes the tapered surface 5 of the cushion ring 6 to move with the extension operation thereafter.
By gradually reducing the area of the slit 31 formed by the inner surface of the cushion seal 24c and the inner surface of the cushion seal 24c, a cushion effect is provided for the extension operation near the most extended end.

The hydraulic cylinder 1c is inverted to the compression operation side from the most extended state or the vicinity of the most extended end, and the cushion ring 6 on the piston rod 2 side comes out of the cushion seal 24c on the cylinder head 7 side. The cushion seal 24 c is pressed against the inner surface of the flange 22 formed on the distal end side of the holder 19 by the pressure of the hydraulic oil supplied from the supply / discharge port 27.

As a result, the pressure hydraulic oil supplied from the supply / discharge port 27 of the cylinder tube 11 through the annular oil passage 28, the oil hole 29 of the cylinder head 7, and the oil passage 30 between the cylinder head 7 and the piston rod 2. Of the hydraulic oil chamber 16 on the rod side through the slit 31
Most of the hydraulic fluid, except for a small amount, sent to the axial oil passage 2 between the collar 18 and the cushion seal 24c and between the holder 19 and the cushion sill 24c
The hydraulic cylinder 1c is sent to the hydraulic oil chamber 16 on the rod side through a radial oil passage 26 provided in the cushion seal 24c and the hydraulic cylinder 1c.

[0009]

Therefore, in the conventional hydraulic cylinder 1c provided with the terminal cushion device as described above, the supply / discharge port 27 during the compression operation from the most extended state or from the vicinity of the most extended end. Must be supplied to the hydraulic oil chamber 16 on the rod side without resistance.

To this end, the area of the radial oil passage 26 formed in the outer surface of the cushion seal 24c is increased, as well as the inner and outer diameters of the inner peripheral surface of the holder 19 and the outer surface of the cushion seal 24c. It is necessary to make the difference as large as possible to make the passage area of the axial oil passage 25 formed between the holder 19 and the cushion seal 24c as large as possible.

However, the passage area of the radial oil passage 26 does not particularly affect the expansion and contraction operation of the hydraulic cylinder 1c even if the passage area is arbitrarily set. As shown in FIG. 9, when the axial oil passage 25 between the cushion seal 24 c and the passage area is enlarged by increasing the difference between the inner and outer diameters of the two, the maximum eccentricity δ of the cushion seal 24 c with respect to the holder 19 becomes as shown in FIG. growing.

As a result, at the beginning of the cushion stroke during the extension operation, the tip of the cushion ring 6 on the piston rod 2 side easily interferes with the outer surface of the cushion seal 24c, and the smooth extension operation of the hydraulic cylinder 1c is hindered. Have the fear of

However, if the maximum eccentricity δ is made as small as possible in order to prevent the interference between the cushion ring 6 and the cushion seal 24c,
This time, the passage area of the axial oil passage 25 cannot be sufficiently secured, and the hydraulic oil pressure supplied from the supply / discharge port 27 during the compression operation of the hydraulic cylinder 1c in the most extended state or near the most extended end is not sufficient. It will rise as necessary and cause power loss.

Accordingly, an object of the present invention is to keep the maximum eccentricity of the cushion seal as small as possible to prevent interference with the cushion ring, and to minimize power loss during the compression operation in the cushion stroke. It is an object of the present invention to provide a hydraulic cylinder equipped with a novel cushion device that can be maintained at a low pressure.

[0015]

SUMMARY OF THE INVENTION An object of the present invention is to provide a cushion ring having a tapered surface disposed on the outer peripheral surface of a base end of a piston rod, and a holder corresponding to the cushion ring on the inner diameter side of a cylinder tube. A cushion seal with a check function, which is disposed so as to be displaceable in the axial direction via a collar, and the cushion seal is formed by the hydraulic oil pressure generated in the oil chamber on the rod side when the cushion ring is fitted to these cushion seals. A hydraulic cylinder that presses against the collar and closes the oil passage between the holder and the cushion seal to gradually reduce the area of the slit formed by the inner diameter surface of the cushion seal and the tapered surface of the cushion ring. In a cushion device, an oil passage between a holder and a cushion seal is formed on an inner peripheral surface of the holder. It is accomplished by forming a series of grooves bored biting into the inner peripheral surface of the holder over a predetermined range from the flange portion of the tip to a position reaching the distal end of the collar towards to the along-axis direction.

That is, instead of determining the area of the oil passage formed between the holder and the cushion seal by the gap between them, the flange of the holder tip, which is the stopper of the cushion seal, is placed on the inner peripheral surface side of the holder. And formed as a series of grooves extending over a predetermined range up to a position where the collar reaches the leading end of the collar.

Accordingly, the area of the oil passage formed between the holder and the cushion seal is determined by the cross-sectional area of the groove formed on the inner peripheral surface of the holder. While keeping the dimensions very small, the oil passage area between the holder and the cushion seal is made sufficiently large to prevent interference with the cushion ring, and at the same time, minimize power loss during the cushion stroke during compression operation. It can be kept to a minimum.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A hydraulic cylinder with a cushion device according to an embodiment of the present invention will be described below with reference to FIG.

In FIG. 1, a hydraulic cylinder 1 with a cushion device according to an embodiment of the present invention is the hydraulic cylinder 1 with a cushion device of the prior art shown in FIG.
Similarly to c, the piston 4 is fastened to the base end of the piston rod 2 with the piston nut 3, and a cushion ring 6 having a tapered surface 5 on the surface in contact with the piston 4 is provided on the outer peripheral surface of the piston rod 2. I have.

The piston rod 2 has a cylinder head 7
Is inserted through a bearing 8 provided on the inner peripheral surface through a main seal 9 and a dust seal 10, and the cylinder head 7 is screwed into a cylinder tube 11 with a seal 12 interposed therebetween, thereby cooperating with the piston 4. The open end of the cylinder tube 11 is closed while guiding the piston rod 2 with respect to the cylinder tube 11.

On the outer peripheral surface of the piston 4, there are provided a piston ring 14 having a seal ring 13 provided on the inner surface thereof and piston rings 15, 15 having a unitary structure disposed on both sides of the piston ring 14. By sliding the piston 4 against the inner wall surface of the cylinder tube 11 via the piston rings 14 and 15, the piston 4 causes the inside of the cylinder tube 11 to move between the rod-side hydraulic oil chamber 16 and the bottom-side hydraulic oil chamber. 17 and is divided.

Inside the hydraulic oil chamber 16 on the rod side, a holder 19 into which a collar 18 is inserted and fixed is disposed with a seal 20 interposed between the holder 19 and the inner peripheral surface of the cylinder tube 11. Is pressed against the tapered surface 21 provided on the cylinder tube 11 by the cylinder head 7 and fixed.

The holder 19 has an annular groove 23 having a predetermined width formed between the collar portion 22 formed at the tip and the collar 18 fitted and fixed on the inner surface of the holder 19, and
A cushion seal 24 is movably fitted in the groove 23 in the axial direction.

The outer peripheral surface of the cushion seal 24 and the holder 1
9 is provided with an axial oil passage 25 having a desired passage area.
8, one communication end of the axial oil passage 25 is closed, and when the holder 19 is locked by the flange portion 22, both ends of the axial oil passage 25 are communicated by the configuration described later. They are kept open without closing.

The cylinder tube 11 is provided with a supply / discharge port 27 for the hydraulic oil chamber 16 on the rod side opposite to a supply / discharge port (not shown) communicating with the hydraulic oil chamber 17 on the head side. 27 is an oil hole 2 drilled in the cylinder head 7 from the annular oil passage 28 between the cylinder head 7
An oil passage 30 between the piston 9 and the piston rod 2 leads to the rod-side hydraulic oil chamber 16.

The portion of the oil passage 30 which opens into the hydraulic oil chamber 16 on the rod side is provided with the cushion seal 2 as described above.
4 is arranged so that the movement in the axial direction is restricted by the side surface of the collar 18 and the flange portion 22 of the holder 19.

The above-described points are equivalent in structure and operation to the conventional hydraulic cylinder 1c with a cushion device described above with reference to FIG. 8, and therefore, only the above-described structure is still similar to the conventional case. Eliminating the possibility that the cushion ring 6 and the cushion seal 24 interfere with each other at the beginning of the cushion stroke to hinder a smooth extension operation, or that the hydraulic oil supply resistance at the time of the compression operation becomes large, resulting in power loss. Can not.

Therefore, in the hydraulic cylinder cushion device according to the present invention, as can be seen from FIGS. 1 and 2, the inner peripheral surface of the cushion seal 24 is
And the axial oil passage 25 between the outer peripheral surface and the inner peripheral surface of the holder 19 has a slight size to absorb the misalignment due to the processing error. Consists of a gap of dimensions.

Then, the passage area, which is insufficient with the axial oil passage 25 alone, is cut into the inner peripheral surface of the holder 19 from the flange 22 at the tip of the holder 19 which is a stopper of the cushion seal 24, and This is compensated for by forming a series of grooves 32 extending to a position reaching the tip of the collar 18.

The reason that the groove 32 extends to the flange 22 at the tip of the holder 19 is that the cushion seal 24 is locked by the flange 22 of the holder 19 as described above. This is to keep the communication at either end of the open state without closing it.

As a result, as shown in FIG. 3, the cross-sectional dimension of the axial oil passage 25 is reduced so that the maximum eccentricity δ of the cushion seal 24 is kept very small for absorbing misalignment. Due to the groove 32 provided in the holder 19, the substantial sectional size of the axial oil passage 25 can be made sufficiently large.

Thus, the cushion ring 6 is prevented from interfering with the cushion seal 24 at the beginning of the cushion stroke during the extension operation of the hydraulic cylinder 1, and
The power loss during the cushion stroke during the compression operation in the opposite direction can be kept to a minimum.

Further, in addition to the above, the cushion seal 24, which is liable to generate residual stress due to distortion due to processing, does not need to be processed with grooves or the like. Since the cushion seal 24 can be formed as a simple ring, it is possible to reliably prevent the occurrence of defective products due to reverse assembly during the assembly operation.

In the embodiment of FIG. 1 described above, the flange portion 22 at the tip of the holder 19 is cut off to form the axial oil passage 25. 4 and the hydraulic cylinder 1a shown in the embodiment of FIG.
A plurality of through-holes 33 formed in the axial direction from the flange 22 at the tip along the inner peripheral surface of the holder 19a, and Part 2
It is also possible to cut into these through holes 33 over a predetermined range up to the position where the collar 18 reaches the tip end of the collar 18 and supplement with the annular groove 32 a formed in the inner peripheral surface of the holder 19.

In any case, the annular groove 3
2a, the maximum eccentricity δ of the cushion seal 24 is kept to a very small value for absorbing misalignment, and the oil passage area between the holder 19a and the cushion seal 24 is reduced by the hole of the flange 22. 33 and an annular groove 32 formed in the inner peripheral surface
It can be made sufficiently large by the cross-sectional area of a.

Thus, the cushion ring 6 is prevented from interfering with the cushion seal 24 at the beginning of the cushion stroke during the extension operation of the hydraulic cylinder 1, and
Power loss during the cushion stroke during the compression operation in the opposite direction can be kept to a minimum.

In addition, the cushion seal 24, in which residual stress is liable to be generated due to distortion due to processing, does not need to be processed with grooves or the like. This is because, since the ring 24 can be formed as a simple ring, occurrence of defective products due to reverse assembly during the assembling operation can be reliably prevented.

Further, as in the hydraulic cylinder 1b of the embodiment shown in FIGS. 6 and 7, the holder 19 is kept the same as the conventional one without any processing, and instead, the holder 19 and the cushion seal are replaced. The oil passage between 24b
A series of grooves 32b which are shallower than the thickness of the collar 18 extending in the axial direction from the radial oil passage 26 provided on the outer surface of the cushion seal 24b to the outer peripheral surface are additionally provided.

In this manner, the cushion seal 24b
While keeping the maximum eccentric amount of the eccentricity to a very small size for absorbing misalignment, the oil passage area between the holder 19 and the cushion seal 24b is made sufficiently large to prevent interference with the cushion ring 6 and Further, it is possible to minimize the power loss during the cushion stroke during the compression operation.

However, in this case, as in the conventional case, it is not possible to eliminate the possibility of defective products due to the processing distortion of the cushion seal 24b and the wrong assembly. The object can be achieved with an extremely simple configuration as compared with the embodiment.

[0041]

As described above, according to the first aspect of the present invention, the oil passage between the holder and the cushion seal is extended axially along the inner peripheral surface of the holder from the collar portion at the distal end to the collar. The holder and the cushion are formed by a series of grooves formed by cutting into the inner peripheral surface of the holder over a predetermined range up to a position where the inner peripheral surface of the holder is reached. The area of the oil passage between the seal and the seal is determined, whereby the maximum eccentricity of the cushion seal is kept to a very small value for absorbing misalignment, and the oil passage between the holder and the cushion seal is kept. It is possible to make the area, that is, the oil passage in the axial direction sufficiently large, while preventing the cushion ring from interfering with the cushion seal at the beginning of the cushion stroke during the extension operation of the hydraulic cylinder, It is possible to maintain to a minimum the power loss in the cushion stroke during compression operation to the contralateral direction.

In addition to this, a cushion seal in which residual stress is liable to be generated due to distortion or the like due to processing does not need to be subjected to processing such as grooves, so that not only the rate of occurrence of defective products is significantly reduced, but also Since the seal can be formed as a simple ring, it is possible to reliably prevent the occurrence of defective products due to reverse assembly.

According to the second aspect of the present invention, a plurality of through holes are formed in the oil passage between the holder and the cushion seal along the inner peripheral surface of the holder and from the flange at the tip end in the axial direction. And an annular groove formed in the inner peripheral surface of the holder by cutting into these through holes over a predetermined range up to the position where the collar reaches the tip of the collar. In addition to the effects of the first aspect of the present invention, the axial oil passage for the holder can be easily formed, and the machining can be performed by the notch groove. The rate of occurrence of defective products in the holder due to residual stress or deformation due to the influence of the processing can be significantly reduced.

Further, according to the third aspect of the present invention, the collar extending in the axial direction from the radial oil passage provided on the outer surface of the cushion seal to the outer peripheral surface of the oil passage between the holder and the cushion seal. By forming a series of grooves shallower than the thickness dimension of the cushion seal, there is a possibility that deformation or mis-assembly may occur due to processing distortion of the cushion seal as in the conventional case, but on the other hand, the object of the present invention is to provide a very simple configuration. Can be achieved.

[Brief description of the drawings]

FIG. 1 is a front view of a portion of a cushion device, which is a main part of a hydraulic cylinder according to the present invention, which is cut longitudinally.

FIG. 2 is an enlarged side view showing a holder used in the cushion device according to the first embodiment.

FIG. 3 is an explanatory view showing a maximum eccentricity of a cushion seal in the cushion device of the above.

FIG. 4 is a front view showing a longitudinal section of another embodiment of the cushion device as a main part of the hydraulic cylinder according to the present invention.

FIG. 5 is an enlarged side view showing a holder used in the cushion device according to the first embodiment.

FIG. 6 is a front view of a cushion device, which is a main part of a hydraulic cylinder according to another embodiment of the present invention.

FIG. 7 is an enlarged perspective view showing a holder used in the cushion device according to the first embodiment.

FIG. 8 is a front view of a conventionally used hydraulic cylinder cushion device in a longitudinal section.

FIG. 9 is an explanatory view showing a maximum eccentric amount of a cushion seal in the cushion device of the above.

[Description of Signs] 1, 1a, 1b, 1c Hydraulic cylinder 2 Piston rod 5 Tapered surface 6 Cushion ring 7 Cylinder head 11 Cylinder tube 16 Rod-side hydraulic oil chamber 17 Bottom-side hydraulic oil chamber 18 Collar 19, 19a Holder 22 Flange 23 Annular groove 24, 24b, 24c Cushion seal 25 Axial oil passage 26 Radial oil passage 27 Supply / discharge port 31 Slit 32, 32b Groove 32a Annular groove 33 Through hole

Claims (3)

[Claims] 1. A cushion ring having a tapered surface disposed on the outer peripheral surface of a base end of a piston rod, and displaceable in the axial direction via a holder and a collar on an inner diameter side of a cylinder tube corresponding to the cushion ring. A cushion seal with a check function is provided.The cushion seal is pressed against the collar by hydraulic oil pressure generated in the oil chamber on the rod side when the cushion ring is fitted to these cushion seals. In a cushion device of a hydraulic cylinder that generates a cushioning effect by gradually reducing the area of a slit formed by the inner diameter surface of the cushion seal and the tapered surface of the cushion ring by closing the oil passage of Turn the path along the inner peripheral surface of the holder in the axial direction A hydraulic cylinder cushion device formed by a series of grooves cut into the inner peripheral surface of the holder over a predetermined range up to a position reaching the tip of the hydraulic cylinder. 2. A cushion ring having a tapered surface disposed on an outer peripheral surface of a base end of a piston rod, and displaceable in an axial direction on a radially inner side of a cylinder tube via a holder and a collar corresponding to the cushion ring. A cushion seal with a check function is provided.The cushion seal is pressed against the collar by hydraulic oil pressure generated in the oil chamber on the rod side when the cushion ring is fitted to these cushion seals. In a cushion device of a hydraulic cylinder that generates a cushioning effect by gradually reducing the area of a slit formed by the inner diameter surface of the cushion seal and the tapered surface of the cushion ring by closing the oil passage of Multiple holes drilled along the inner circumferential surface of the holder from the collar at the tip in the axial direction A plurality of through-holes, and an annular groove formed in the inner peripheral surface of the holder by cutting into these through-holes over a predetermined range up to a position reaching the tip of the collar while leaving the flange portion. Hydraulic cylinder cushioning device. 3. A cushion ring having a tapered surface disposed on an outer peripheral surface of a base end of a piston rod, and displaceable in an axial direction corresponding to the cushion ring on an inner diameter side of a cylinder tube via a holder and a collar. A cushion seal with a check function is provided.The cushion seal is pressed against the collar by hydraulic oil pressure generated in the oil chamber on the rod side when the cushion ring is fitted to these cushion seals. In a cushion device of a hydraulic cylinder that generates a cushioning effect by gradually reducing the area of a slit formed by the inner diameter surface of the cushion seal and the tapered surface of the cushion ring by closing the oil passage of From the radial oil passage provided on the outer surface of the cushion seal to the outer peripheral surface. A cushion device for a hydraulic cylinder, wherein the cushion device is formed by a series of grooves shallower than a thickness dimension of a collar continuing in an axial direction.