JP2001193711A - Cushion device for hydraulic cylinder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain variation in cushion property and the generation of an abnormal high pressure, and prevent damage to a hydraulic cylinder, by adding simple means of processing with simple structure. SOLUTION: This cushion device for hydraulic cylinder comprises a cushion ring 6 having a tapered surface 5 arranged on an outer peripheral surface of a base end of a piston rod 2, and a cushion seal 24 arranged to be capable of relative displacement in an axial direction with respect to the cushion ring 6, herein, a cushion effect is generated such that the cushion ring 6 is fitted into the cushion seal 24 accompanied with an extending operation in the vicinity of the most extended state of the hydraulic cylinder 1, to gradually reduce an area of a slit 31 formed by both an inner diameter surface of the cushion seal 24 and the tapered surface 5 of the cushion ring 6. In this device, the length of the tapered surface 5 of the cushion ring 6 is previously set so that the slit 31 is closed before the hydraulic cylinder 1 reaches the most extended state, and a hydraulic fluid chamber 16 at a rod side and a supply/discharge port 27 communicate with each other via an orifice 33 which serves as a restricted oil passage for ensuring a minimum passage area.

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 a hydraulic cylinder 1a provided with this kind of terminal cushion device, as shown in FIG. 7, a cushion having a tapered surface 5 at the base outer peripheral surface of a piston rod 2 in contact with a piston 4 is shown. The ring 6 is arranged, and the cushion seal 24 is displaced in the axial direction by the collar 18 and the holder 19 in contact with the cylinder head 10 so as to face the cushion ring 6.

With the extension operation near the most extended end of the hydraulic cylinder 1a, the cushion ring 6 on the piston rod 2 side is fitted into the cushion seal 24 on the cylinder head 10 side.
By gradually reducing the area of the slit 31 formed by the inner diameter surface of the cylinder 4 and the tapered surface 5 of the cushion ring 6, a cushion effect is provided to the extension operation near the most extended end of the hydraulic cylinder 1a.

[0004]

As described above, in the conventional hydraulic cylinder 1a provided with the terminal cushion device described above, the hydraulic cylinder 1a is discharged from the hydraulic oil chamber 16 on the rod side with the extension operation near the most extended end. The restricting oil passage that exerts a cushion effect by adding flow resistance to the working oil is only the area of the slit 31 formed by the tapered surface 5 of the cushion ring 6 and the inner diameter surface of the cushion seal 24.

In addition, the area of the slit 31 formed by the tapered surface 5 of the cushion ring 6 and the inner diameter surface of the cushion seal 24 is gradually reduced during the extension operation near the most extended end of the hydraulic cylinder 1a. It is necessary to set the length of the tapered surface 5 so that the hydraulic oil chamber 16 on the rod side is not locked until the rod 4 reaches the most extended state in which it is stopped by hitting the holder 19.

Nevertheless, if a machining error occurs in the length or width dimension of the tapered surface 5, this not only immediately leads to variations in cushion operating time and deceleration performance, but also in some cases, When the area of the slit 31 cannot be sufficiently secured, the hydraulic oil chamber 16 on the rod side is in a locked state or a state close thereto.

For this reason, an abnormally high pressure is generated in the hydraulic oil chamber 16 on the rod side, and the occurrence of the abnormally high pressure may damage the cylinder head 10, the cylinder tube 11, and the like.

Therefore, an object of the present invention is to add not only a simple structure but also an easy-to-work means, not only to vary the cushion performance, but also to suppress the occurrence of abnormally high pressure and to prevent the hydraulic cylinder itself from being damaged. To provide a hydraulic cylinder with a new cushion device.

[0009]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a cushion ring having a tapered surface disposed on an outer peripheral surface of a base end of a piston rod and an axially displaceable cushion ring relative to the cushion ring. The cushion ring is fitted into the cushion seal with the extension operation in the vicinity of the maximum extension of the hydraulic cylinder, and 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 of a hydraulic cylinder that provides a cushioning effect by gradually decreasing the length of the tapered surface of the cushion ring, the length of the cushion ring is set in advance so that the slit is closed before the hydraulic cylinder reaches the maximum extension state, The hydraulic fluid chamber on the rod side and the supply / discharge port have an orifice or It is achieved by'll communicating through restricting passage consisting of the groove and the like.

That is, in the elongating operation until the hydraulic cylinder reaches a predetermined position before reaching the most extended state, in other words, the inner end of the tapered surface of the cushion ring enters the inner diameter surface of the cushion seal and is closed. The cushion effect is achieved by the slit that gradually reduces the passage area formed by the inner diameter surface of the cushion seal and the tapered surface of the cushion ring, and the flow resistance of the hydraulic oil in the orifice or notch groove parallel to the slit. I will raise it.

[0011] Therefore, the cushion effect during this time,
Not only the area of the slit due to the tapered surface of the cushion ring and the inner diameter surface of the cushion seal, but also the flow resistance due to the orifice or the notch groove is involved. It is possible to mitigate and suppress the processing error from directly leading to variations in the operation time and deceleration performance of the cushion.

Moreover, at least until the hydraulic cylinder reaches the maximum extension state, at least the hydraulic oil chamber on the rod side communicates with the supply / discharge port through the orifice or the notch groove.
It is also possible to eliminate the possibility that the hydraulic oil chamber on the rod side becomes a hydraulic lock state or a state close thereto and an abnormally high pressure is generated in the hydraulic oil chamber on the rod side, thereby damaging the cylinder tube and the cylinder head. It becomes.

[0013]

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 same as the hydraulic cylinder 1 with a cushion device of the prior art shown in FIG.
Similarly to a, 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.

A cylinder head 10 is inserted into the piston rod 2 through a bearing 7 provided on the inner peripheral surface, a main seal 8 and a dust seal 9, and the cylinder head 10 is inserted into a cylinder tube 11 with a seal 12. By screwing in, the piston rod 2 is cooperated with the piston 4 to guide the piston rod 2 with respect to the cylinder tube 11 while closing one open end of the cylinder tube 11.

On the outer peripheral surface of the piston 4, there is provided a piston seal 14 provided with a seal ring 13 superposed on the inner surface, and a single-piece piston ring 15, 15 disposed on both sides with the piston seal 14 interposed therebetween. The piston 4 slides on the inner wall surface of the cylinder tube 11 via the piston seal 14 and the piston ring 15, so that the interior of the cylinder tube 11 is moved by the piston 4 to the hydraulic oil chamber 16 on the rod side and the bottom. And the working oil chamber 17 on the side.

Inside the hydraulic oil chamber 16 on the rod side, a holder 19 into which the 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 fixed by being pressed by a cylinder head 10 and being pressed against a tapered surface 21 provided on a cylinder tube 11.

As shown in the enlarged view of FIG. 2 (showing the most extended state), the holder 19 has a flange 22 formed at the tip.
And a collar 18 fitted and fixed to the inner surface of the holder 19
An annular groove 23 having a predetermined width is formed between them, and a cushion seal 24 is movably fitted inside the groove 23 in the axial direction.

The cushion seal 24 secures an annular axial oil passage 25 at a distance between the outer peripheral surface and the bottom of the groove 23 on the holder 19 side. By providing a vertical groove toward the
A radial oil passage 26 leading to the oil passage is secured.

The cylinder tube 11 has a supply / discharge port 27 communicating with the hydraulic oil chamber 16 on the rod side in correspondence with a supply / discharge port (not shown) communicating with the hydraulic oil chamber 17 on the head side. The discharge port 27 is connected to the cylinder head 10.
An oil passage 29 formed between the annular oil passage 28 between the piston rod 2 and the oil hole 29 formed in the cylinder head 10 communicates with the hydraulic oil chamber 16 on the rod side.

The above-described cushion seal 2 is provided at a portion of the oil passage 30 which opens to the hydraulic oil chamber 16 on the rod side.
4 is arranged by limiting the movement in the axial direction by the side surface of the collar 18 and the flange portion 22 of the holder 19.

The configuration described above is equivalent to the conventional hydraulic cylinder 1a with a cushion device described above with reference to FIG. 7, and therefore, with this configuration alone, the hydraulic oil chamber 16 on the rod side is still provided in the same manner as the previous case. It is not possible to eliminate the possibility that an abnormally high pressure is generated and the cylinder head 10 and the cylinder tube 11 are damaged by the generation of the abnormally high pressure.

Therefore, in the hydraulic cylinder cushion device according to the present invention, the tapered surface 5 of the cushion ring 6 passes through the inner peripheral surface of the cushion seal 24 before the hydraulic cylinder 1 reaches the most extended state. The dimensions from the piston 4 to the tapered surface 5 of the cushion ring 6 and the dimensions from the piston 4 to the cushion seal 24 are determined and set in advance so that the slit 31 formed therebetween is closed.

In addition, as can be seen from the perspective view of FIG. 3, a guide for guide provided on the outer peripheral surface on the mounting end side of the collar 18 in order to facilitate the mounting of the collar 18 on the holder 19. The orifice 33 is formed by using the tapered portion 32 of the above.

The orifice 33 forms the tapered surface 5.
And slit 31 made by cushion seal 24
Therefore, the minimum communication between the hydraulic oil chamber 16 on the rod side and the supply / discharge port 27 after the disappearance of the rod is ensured.

The orifice 33 is provided in the holder 19
The hole 18 is pierced in the radial direction using the tapered portion 32 for guide provided on the outer peripheral surface on the mounting end side of the collar 18 with respect to
As shown in the perspective view of FIG. 4, a counterbore portion 34 that opens to the oil passage 25 in the axial direction is provided for a corresponding portion of the collar 18, and the rod-side operation that faces radially through the counterbore portion 34. An orifice 33 may be formed as a restricted oil passage that keeps the oil chamber 16 and the supply / discharge port 27 in communication.

In particular, this makes it possible to drill the orifice 33 while keeping the drill at right angles to the bottom surface of the counterbore portion 34, so that the machining of the orifice 33 becomes extremely easy.

Thus, according to the hydraulic cylinder cushion device having the above configuration, the hydraulic oil chamber 17 on the bottom side is provided.
When the hydraulic fluid is supplied to the piston and the piston 4 is pushed toward the extension side, the piston 4 moves the hydraulic fluid in the hydraulic fluid chamber 16 on the rod side together with the piston rod 2 and the outer surface of the piston rod 2 and the cushion seal 24. The hydraulic cylinder 1 extends while passing through the oil passage 30 from the opening between the inner surface and the outside through the oil hole 29, the annular oil passage 28, and the supply / discharge port 27.

Subsequently, when the cushion ring 6 of the piston rod 2 reaches the cushion seal 24 and begins to be fitted therein, the sliding portion between the cushion ring 6 and the cushion seal 24 closes the opening therebetween. The flow of the hydraulic oil from the opening toward the oil passage 30 is cut off.

As a result, the hydraulic oil pressure applied to the hydraulic oil chamber 16 on the rod side rises and pushes the cushion seal 24, and the cushion seal 24 is pressed against the side surface of the collar 18 to move from the radial oil passage 26 to the axial oil passage. The flow of the hydraulic oil toward the oil passage 30 through 25 is also prevented.

As a result, the flow of the hydraulic oil from the hydraulic oil chamber 16 on the rod side toward the oil passage 30 is caused by the slit 31 formed by the tapered surface 5 of the cushion ring 6 and the inner diameter surface of the cushion seal 24, and the cylinder tube 11 side color 1
Only the oil passage passing through the orifice 33 drilled in 8 is provided.

Therefore, after the cushion ring 6 reaches the cushion seal 24 and starts to be fitted, the inner end of the tapered surface 5 of the cushion ring 6 is
In the elongation operation until it enters into the inner diameter surface and is closed, the cushion effect is enhanced by the slit 31 whose area gradually decreases and the flow resistance of the hydraulic oil passing through the orifice 33 parallel to the slit 31. Will go.

In addition, as described above, since the cushion effect during this time involves not only the area of the slit 31 but also the flow resistance due to the orifice 33, the length of the tapered surface 5 constituting the slit 31 is reduced. It is possible to reduce and suppress the processing error of the dimension in the width direction immediately leading to the variation in the operation time and deceleration performance of the cushion.

In addition, until the hydraulic cylinder 1 reaches the maximum extension state, at least the rod-side hydraulic oil chamber 16 communicates with the supply / discharge port 27 through the orifice 33 until the rod-side hydraulic oil chamber 16 Is in or close to the state of the hydraulic lock, and the hydraulic oil chamber 1 on the rod side
It is also possible to eliminate the fear that an abnormally high pressure is generated in the cylinder 6 and the cylinder tube 11 and the cylinder head 10 are damaged.

Contrary to the above, the hydraulic cylinder 1 is compressed by supplying pressure hydraulic oil from the supply / discharge port 27 to the hydraulic oil chamber 16 on the rod side through the annular oil passage 28, the oil hole 29 and the oil passage 30. When operating, the cushion seal 24
Is pressed by the supplied pressure hydraulic oil and pressed against the flange portion 22 of the holder 19.

Thus, the cushion seal 24 is
The side surface having the radial oil passage 26 is pressed against the flange 22 of the holder 19, and the pressure hydraulic oil supplied from the supply / discharge port 27 is supplied to the rod-side hydraulic oil chamber 16 through the radial oil passage 26 of the holder 19. Then, the piston 4 is compressed with the piston rod 2 while the hydraulic oil in the hydraulic oil chamber 17 on the head side is pushed out through a supply / discharge port (not shown).

However, in the above-described embodiment, the orifice 33 is provided in the collar 18 so as to limit the minimum flow of the discharged oil near the extension end of the hydraulic cylinder 1.

As a result, dust or the like is caught by the orifice 33 due to dirt or the like of the working oil used, causing clogging, and the pressure of the working oil becomes abnormally high, so that not only the desired cushioning property cannot be obtained, but also the sealing property. If the oil leaks from the portion or is severe, the cylinder tube 11 may be damaged.

Moreover, once the orifice 3
If clogging occurs, the hydraulic cylinder 1 must be disassembled to remove dust or the like clogged in the orifice 33, which requires a lot of trouble and cost.

Therefore, the other embodiments shown in FIGS. 5 and 6 are configured in consideration of these points, and are different from the above-described embodiments shown in FIGS. Notch groove 35 as a restricting oil passage that keeps the hydraulic oil chamber 16 on the rod side and the supply / discharge port 27 in communication with the tip end surface of the collar 18 facing the cushion seal 24 in place of the orifice 33 of FIG.
It was constructed by drilling.

According to this, when the hydraulic cylinder 1 is extended, the slit 31 formed by the tapered surface 5 of the cushion ring 6 and the cushion seal 24 near the extended end.
Is closed, and when the cushion seal 24 is pressed against the collar 18, the opening side surface of the cutout groove 35 of the collar 18 is closed by the cushion seal 24, and the same operation as the orifice 33 in the previous embodiment. To fulfill.

When the hydraulic cylinder 1 is compressed, the cushion seal 24 separates from the collar 18, so that the side surface of the cutout groove 35 of the collar 18 forming the orifice with the cushion seal 24 opens and returns to the original groove shape. .

Therefore, even if dirt or the like is clogged in the notch groove 35 of the collar 18, it is easily washed away and removed by the flow of hydraulic oil during the compression operation of the hydraulic cylinder 1, and
The desired cushioning characteristics cannot be obtained due to clogging.
This also eliminates the possibility that the device 1 may be damaged.

In each of the embodiments described above, the case where the orifice 33 or the notch groove 35 as the restriction oil passage is provided on the collar 18 side has been described. Can be provided on the cushion seal 24 side, or the collar 18
Obviously, the same effect can be obtained by providing both the and the cushion seal 24.

Therefore, the change in the configuration as described above is
Needless to say, at least belongs to the category of the present invention,

[0046]

As described above, according to the first aspect of the present invention, before the hydraulic cylinder reaches the maximum extension state, the slit formed by the tapered surface of the cushion ring and the inner diameter surface of the cushion seal is closed. So that the length of the tapered surface of the cushion ring is set in advance, and at the same time, the hydraulic oil chamber on the rod side and the supply / discharge port communicate only with the restricted oil passage having the minimum necessary passage area. By doing so, during the elongation operation until the inner end of the tapered surface of the cushion ring enters the inner diameter surface of the cushion seal and is closed, a portion formed by the inner diameter surface of the cushion seal and the tapered surface of the cushion ring. The cushion effect by the slit that gradually reduces the area of the oil and the flow resistance of the hydraulic oil in the restricted oil passage parallel to the slit It can be.

In addition, in the above-described cushion effect, not only the area of the slit formed by the tapered surface of the cushion ring and the inner diameter surface of the cushion seal but also the flow resistance due to the restricted oil passage is involved. It is also possible to mitigate that the machining error in the length or width dimension of the tapered surface directly leads to variations in the cushion operating time or deceleration performance.

Further, until the hydraulic cylinder reaches the maximum extension state, at least the hydraulic oil chamber on the rod side is in communication with the supply / discharge port through the restricted oil passage, so that the hydraulic oil chamber on the rod side is This state or a state close to the above state can eliminate the fear that an abnormally high pressure is generated in the hydraulic oil chamber on the rod side and damage the cylinder tube, the cylinder head, and the like.

According to the second aspect of the invention, in addition to the effects of the first aspect, the cushion seal is limited by the collar provided on the inner surface of the end of the holder and the collar fitted to the holder. To keep the hydraulic oil chamber on the rod side and the supply / discharge port radially facing the tapered part provided on the outer peripheral surface on the mounting end side of the collar with respect to the holder. By drilling an orifice as an oil passage,
An orifice for keeping the hydraulic oil chamber on the rod side and the supply / discharge port in communication with each other can be easily installed by utilizing the taper portion of the collar originally provided for facilitating the attachment of the collar to the holder.

According to the third aspect of the present invention, in addition to the effect of the first aspect of the present invention, a collar provided on the inner surface of the end of the holder and a collar fitted to the holder are limited. Restrictive oil that disposes a cushion seal in the axial direction and that has a counterbore on the outer peripheral surface of the collar on the mounting end side of the holder to keep the hydraulic oil chamber on the rod side and the supply / discharge port in communication. By drilling the orifice as a passage, it is possible to drill the orifice, which is a restricted oil passage, by keeping the drill at a right angle to the bottom surface of the counterbore portion, which makes it extremely easy to process the restricted oil passage. is there.

Further, according to the invention of claim 4, in addition to the effect of the invention of claim 1, the cushion is limited by the collar provided on the inner surface of the end of the holder and the collar fitted to the holder. The seal is displaceable in the axial direction, and a cut-out groove is formed between the cushion seal and the facing surface of the collar as a restricted oil passage that keeps the hydraulic oil chamber on the rod side and the supply / discharge port in communication. When the cushion is pressed against the collar during the extension operation of the hydraulic cylinder, the side opening surface of the cutout groove is closed and becomes an orifice. Even if dirt or the like is clogged in the cutout groove that constitutes the orifice because the side of the groove opens to return to the original groove shape, it is easily washed away and removed by the flow of hydraulic oil during compression operation, and clogging Riniyotte Toka desired cushioning characteristics can not be obtained, it is the cylinder tube or cause leakage oil from the sealing portion so that can be removed the risk of such damage.

[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 partial front view showing a state at the time when a cushion device for a hydraulic cylinder, which is a main part of the present invention, reaches a most extended state.

FIG. 3 is a perspective view showing a collar used in the cushion device for a hydraulic cylinder according to the present invention.

FIG. 4 is a perspective view showing another embodiment of a collar used in a cushion device for a hydraulic cylinder according to the present invention.

FIG. 5 is an enlarged partial front view showing another embodiment of the cushion device for a hydraulic cylinder, which is a main part of the present invention, in a state at the time when the cushion device has reached a maximum extension state.

FIG. 6 is a perspective view showing a collar used in the cushion device of the hydraulic cylinder according to the first embodiment.

FIG. 7 is a front view of a conventionally used hydraulic cylinder cushion device in a longitudinal section.

[Description of Signs] 1 Hydraulic cylinder 2 Piston rod 4 Piston 5 Tapered surface 6 Cushion ring 10 Cylinder head 11 Cylinder tube 16 Hydraulic oil chamber on rod side 17 Bottom hydraulic oil chamber 18 Collar 19 Holder 22 Flange 23 Ring groove 24 Cushion seal 25 Axial oil passage 26 Radial oil passage 27 Supply / discharge port 31 Slit 32 Tapered part 33 Orifice 34 Counterbore part 35 Notch groove

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3H081 AA03 BB02 CC15 DD39 EE30 FF19 3J069 AA50 CC05

Claims (4)

[Claims] 1. A hydraulic cylinder, comprising: a cushion ring having a tapered surface disposed on an outer peripheral surface of a base end of a piston rod; and a cushion seal disposed so as to be axially displaceable relative to the cushion ring. The hydraulic cylinder provides a cushioning effect by fitting the cushion ring into the cushion seal with the extension operation near the maximum extension, and gradually reducing the area of the slit formed by the inner surface of the cushion seal and the tapered surface of the cushion ring. In the cushion device, the length of the tapered surface of the cushion ring is set in advance so that the slit is closed before the hydraulic cylinder reaches the maximum extension state,
A cushion device for a hydraulic cylinder, wherein a hydraulic oil chamber on a rod side and a supply / discharge port communicate with each other through a restricted oil passage that secures a minimum required passage area. 2. A cushion seal, which is limited by a collar provided on a holder and a collar fitted to the holder, is disposed so as to be axially displaceable along the outer peripheral surface of the cushion ring, and the cushion seal is provided. 2. The hydraulic cylinder according to claim 1, wherein a tapered portion is formed on an outer peripheral surface of the collar facing the oil passage, and an orifice is formed as a restriction oil passage through which the hydraulic oil chamber on the rod side communicates with the supply / discharge port through the tapered portion. Cushion device. 3. A cushion seal, which is limited by a collar provided on the holder and a collar fitted to the holder, is disposed so as to be axially displaceable along the outer peripheral surface of the cushion ring, and the cushion seal is provided. A counterbore that opens to the axial oil passage between the holder and the cushion seal is provided on the outer peripheral surface of the collar facing the counterpart, and the hydraulic oil chamber on the rod side and the supply / discharge port are kept in communication through this counterbore. 2. The hydraulic cylinder cushion device according to claim 1, wherein an orifice is formed as a restriction oil passage. 4. A cushion seal, which is limited by a collar provided on the holder and a collar fitted to the holder, is disposed along the outer peripheral surface of the cushion ring so as to be displaceable in the axial direction. 2. The cushion device for a hydraulic cylinder according to claim 1, wherein a cutout groove is provided between the opposed surfaces of the collar as a restriction oil passage for keeping the hydraulic oil chamber on the rod side and the supply / discharge port in communication with each other.