JP4009411B2 - Cylinder cushion structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cylinder cushion structure for mitigating an impact at a stroke end of a piston.
[0002]
[Prior art]
As a cylinder cushion device, those shown in FIGS. 4 to 6 are conventionally known, and the structure thereof is as follows.
As shown in FIG. 4, a piston 2 is slidably incorporated in the cylinder tube 1, and a piston rod 3 is provided on the piston 2. The piston 2 divides the inside of the cylinder tube 1 into cylinder chambers 4 and 5.
Moreover, a cushion ring 6 is fixed at a position adjacent to the piston 2 in the piston rod 3. The cushion ring 6 is formed with a slit 7 that gradually becomes shallower from the end opposite to the piston 2 toward the piston side.
[0003]
A cylinder head 8 is fitted to the end of the cylinder tube 1, and a bearing 9 is provided on the inner periphery of the cylinder head 8. The piston rod 3 is slidably supported by the bearing 9 and protrudes outward from the cylinder head 8.
In the figure, reference numeral 10 denotes a seal provided inside the bearing 9.
[0004]
A holder 11 is fixed to the inner end of the cylinder head 8 as described above, and a collar 12 and a metal cushion seal 13 are fitted to the inner periphery of the holder 11 in this order from the cylinder head 8 side.
The collar 12 is press-fitted into the holder 11 and one end thereof is in close contact with the inner end of the cylinder head 8. Further, a notch 14 is formed on the other end of the collar 12, that is, the surface facing the cushion seal 13, and an orifice is formed when the cushion seal 13 contacts the other end of the collar 12. When the cushion seal 13 is separated from the collar 12, the notch 14 is released and the function as an orifice is lost.
[0005]
On the other hand, the cushion seal 13 is movable between the collar 12 and a stopper 15 formed at the inner end of the holder 11. As shown in FIG. 5, the cushion seal 13 thus configured maintains a slight gap 16 as shown in FIG. 5, and maintains an inner diameter that allows the cushion ring 6 to enter when the piston 2 reaches the stroke end portion. ing.
In addition, a free flow passage 17 is formed in the holder 11, and this free flow passage 17 is interposed between the collar 12 and the cushion seal 13 when the cushion seal 13 is in contact with the stopper 15. Thus, the cylinder chamber 4 and the cylinder port 18 are communicated in a free flow state.
[0006]
Although each member is assembled as described above, a gap is actually formed in the following portion. First, the cushion ring 6 has a mating clearance required between the cushion ring 6 and the piston rod 3 for assembly. Further, a mating gap is also generated between the bearing 9 and the piston rod 3. Further, a mating gap is generated between the cylinder tube 1 and the piston 2.
Such a mating gap causes a shift in the axis of each member. The above-mentioned mating gaps are integrated and the piston rod 3 is eccentric. In order to absorb the eccentricity, the cushion seal 13 is allowed to move to some extent in the radial direction.
[0007]
If the cushion seal 13 cannot move at all in the radial direction, the cushion ring 6 cannot enter the cushion seal 13 at the stroke end portion of the piston when the above-mentioned mating gap is integrated and the piston rod 3 is eccentric. . However, if the cushion seal 13 moves in the radial direction as described above, the eccentricity of the piston rod 3 can be absorbed.
[0008]
Now, when the piston 2 moves in the direction of the arrow 19 from the state of FIG. 4, the working fluid in the cylinder chamber 4 passes through the cushion seal 13 and the inside of the collar 12 and is discharged from the cylinder port 18. When the cushion ring 6 tries to enter the cushion seal 13, the cushion seal 13 is pressed against the collar 12 by the fluid pressure at that time. In this state, the free flow passage 17 communicates with the notch 14 via a gap 16 formed on the outer periphery of the cushion seal 13.
[0009]
As shown in FIG. 5 from the above state, when the cushion ring 6 enters the cushion seal 13, the cylinder chamber 4 and the cylinder port 18 communicate with each other through the following two passages.
One is a passage that passes between the cushion seal 13 and the slit 7 formed in the cushion ring 6, and the other is a passage that passes through the orifice formed by the gap 16 and the notch 14.
In any case, since the flow passage resistance of the two passages is large, the pressure of the cylinder chamber 4 is increased by the resistance, and the moving speed of the piston 2 is relaxed by the increased pressure to exert a cushion effect. .
[0010]
When the pressure in the cylinder chamber 4 increases as described above when the cushion function is performed, the high pressure acts on the outer periphery 13a of the cushion seal 13 and the piston-side contact surface 13b as shown in FIG. However, this high pressure acts only on the portion of the notch 14 on the anti-piston side contact surface 13c, and does not act on other portions.
Therefore, a thrust in the left direction of the drawing acts on the cushion seal 13 due to the difference in the area where the high pressure acts. Then, this thrust force strongly presses the anti-piston side contact surface 13 c of the cushion seal 13 against the collar 12.
[0011]
Further, as described above, the mating gap on the assembly causes the piston rod 3 to be eccentric when it is integrated, but the cushion seal 13 is allowed to move to some extent in the radial direction in order to absorb the eccentricity. . For this reason, when the cushion ring 6 enters the cushion seal 13, their axial centers often do not completely coincide.
[0012]
However, even if the axial center of the cushion ring 6 and the cushion seal 13 is slightly shifted, the cushion seal 13 is gradually loosened and gradually adjusts to the cushion ring 6, and finally the axial center of both is perfect. To match. This principle, when placed in tightly and the hole a stick, similar to push into the hole with little to rattle the bar.
[0013]
On the other hand, when the piston 2 is moved in the direction opposite to the arrow 19, pressure fluid is supplied from the cylinder port 18. When pressure fluid is supplied from the cylinder port 18 in this way, the cushion seal 13 moves to the stopper 15 side by the pressure action. When the cushion seal 13 moves in this manner, the orifice formed by the notch 14 is released, and the cylinder chamber 4 and the cylinder port 18 are directly connected between the collar 12 and the cushion seal 13 and through the free flow passage 17. You will communicate.
Accordingly, the pressure fluid supplied from the cylinder port 18 is supplied to the cylinder chamber 4 between the notch 14 → the collar 12 and the cushion seal 13 and via the free flow passage 17, and the piston 2 is connected to the arrow 19 and the above. Move in the opposite direction.
[0014]
[Problems to be solved by the invention]
In the conventional cushion structure as described above, when the axis of the cushion ring 6 and the cushion seal 13 is displaced, the cushion ring 6 enters while moving the cushion seal 13 in the radial direction. because 13 is, as shown in FIG. 6, it is strongly pressed et al collar 12. Thus, the cushion seal 13 strongly pressed against the collar 12 is difficult to slip in the radial direction.
For this reason, when the cushion ring 6 enters the cushion seal 13, uneven wear tends to occur in the cushion seal 13. As a result, there is a problem that the sealing function of the cushion seal 13 is impaired in a short period of time.
[0015]
Also, when the cushion seal 13 as described above is less likely to slip, entering direction leading end of the cushion ring 6, shock突音increases when impinging on the open end of the cushion seal 13. This loud collision noise not only makes the operator feel uneasy about whether or not the cylinder is broken, but also causes a failure due to the cushion seal 13 being missing.
[0016]
In addition, if the thickness of the cushion seal 13 in the radial direction is reduced to reduce the pressure receiving area, the cushion seal 13 can be easily slid in the radial direction due to a decrease in the pressing force.
However, when the thickness of the cushion seal 13 is reduced in this way, the cushion seal 13 is insufficient in strength.
For this reason, the thickness of the cushion seal 13 could hardly be reduced.
An object of the present invention is to provide a cushion structure for a cylinder that allows the cushion ring 6 to smoothly enter the cushion seal 13 to prevent the above-described uneven wear and large collision noise.
[0017]
[Means for Solving the Problems]
In this invention, a piston is slidably provided on a cylinder tube, a cylinder head is provided at an end of the cylinder tube, and a piston rod provided on the piston is protruded outward from the cylinder head to form a cylinder tube. The piston is reciprocated by supplying or discharging the pressure fluid from the port, while the cushion ring provided on the piston rod side and the cylinder head side are provided in the axial direction and the radial direction. A cushion cushion made of metal that can move to the cushion seal, and when the cushion ring enters the cushion seal, the cushion function is exhibited. The contact surface is It assumes cushion structure of a cylinder having a configuration which is pressed against the Daheddo.
[0018]
In the present invention, an annular pressure introducing groove is formed on the anti-piston side contact surface of the cushion seal or the cylinder head side contact surface with which the anti-piston side contact surface is in contact with the above structure, and the pressure introducing groove is formed on the pressure introducing groove. It is characterized in that it is configured to guide high pressure generated when the cushion function is performed.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
In the first embodiment shown in FIG. 1, the shape of the cushion seal 20 is changed, and the configuration of the cylinder itself is the same as the conventional example.
Therefore, below, it demonstrates centering on the cushion seal 20, the same code | symbol is attached | subjected about the same component as the past, and the detailed description is abbreviate | omitted.
The cylinder head 8, the holder 11 and the collar 12 constitute a cylinder head according to the present invention.
[0020]
As shown in the drawing, a pressure introduction groove 22 is formed in an annular shape on the contact surface 21 of the cushion seal 20 on the non-piston side. The pressure oil in the cylinder chamber 4 is introduced into the pressure introducing groove 22.
According to the first embodiment thus configured, when the cylinder exhibits a cushion function and the cylinder chamber 4 becomes high pressure, the high pressure also acts on the side surface 22 a of the pressure introducing groove 22. That is, it becomes a state equivalent to the state where the high pressure is applied to the portion obtained by subtracting the area of the side surface 22a from the piston side contact surface 23.
Therefore, the force with which the cushion seal 20 is pressed against the collar 12 is reduced, and the frictional force with the collar 12 is also reduced.
Therefore, the cushion seal 20 is easily slidable in the radial direction with respect to the collar 12.
[0021]
If the cushion seal 20 is made slippery, even if the axis of the cushion seal 20 and the axis of the cushion ring 6 are misaligned, the misalignment can be quickly absorbed.
Therefore, the cushion ring 6 can smoothly enter the cushion seal 20, and uneven wear is reduced accordingly.
Therefore, the sealing function of the cushion seal 20 can be maintained for a long time.
Moreover, since the shift | offset | difference of the shaft center of the cushion seal 20 and the shaft center of the cushion ring 6 can be absorbed quickly, a collision sound can also be made small.
[0022]
In the second embodiment shown in FIG. 2, taper surfaces 25a, 26a are formed on the piston side contact surface 25 and the anti-piston side contact surface 26 of the cushion seal 24, and the shapes thereof are symmetrical with respect to the left and right lines. Other configurations are the same as those in the first embodiment.
According to the second embodiment, the pressure introducing groove is constituted by the tapered surface 26 a formed on the anti-piston side contact surface 26. Therefore, the same effect as the first embodiment, that is, the pressing force acting on the cushion seal 24 can be reduced.
Therefore, uneven wear of the cushion seal 24 and collision noise when the cushion ring 6 enters can be reduced.
Further, if the cushion seal 24 that is symmetrical to the left and right lines is used as described above, since there is no directionality during assembly, the assembly workability is good.
[0023]
In the third embodiment shown in FIG. 3, a pressure introducing groove is formed on the collar 27 side. That is, the pressure introduction groove 28 is formed in an annular shape on the contact surface of the collar 27 without forming the pressure introduction groove in the cushion seal 13. A high pressure is applied from the pressure introducing groove 28 to the non-piston side contact surface 13 c of the cushion seal 13.
[0024]
When the high pressure is applied in this way, the pressing force of the cushion seal 13 can be reduced, and therefore the sliding of the cushion seal 13 with respect to the collar 27 can be improved.
Therefore, also according to the third embodiment, the cushion ring 6 can be smoothly inserted into the cushion seal 13 and conventional disadvantages can be prevented.
In addition, according to this 3rd Example, since the cushion seal 13 of the same cross-sectional shape as the past can be used, the intensity | strength can also be maintained.
[0025]
【The invention's effect】
According to the first invention, an annular pressure introducing groove is formed in the contact surface on the side opposite to the piston of the cushion seal or on the cylinder head side in contact with the cushion seal, and the high pressure generated when the cushion function is exerted in the pressure introducing groove. By guiding, the force with which the cushion seal is pressed against the cylinder head can be reduced.
For this reason, the cushion seal becomes slippery with respect to the cylinder head side, and the cushion ring can smoothly enter the cushion seal.
In this way, the cushion seal is less likely to be unevenly worn, so that the sealing function can be maintained for a long time.
Moreover, the impact sound when the cushion ring enters the cushion seal can be reduced.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a main part of a first embodiment.
FIG. 2 is a cross-sectional view of a main part of a second embodiment.
FIG. 3 is a sectional view of an essential part of a third embodiment.
FIG. 4 is a cross-sectional view of a conventional example.
FIG. 5 is an enlarged cross-sectional view showing a state in which the cushion ring 6 of the conventional example has entered the cushion seal 13;
FIG. 6 is a distribution diagram of pressure acting on the cushion seal 13;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Cylinder tube 2 Piston 3 Piston rod 6 Cushion ring 8 Cylinder head 11 Holder 12, 27 which comprises the cylinder head of this invention Collar 18 which comprises the cylinder head of this invention Cylinder port 20 Cushion seal 21, 26 Anti-piston side contact surface 22, 28 Pressure introducing groove 26a Tapered surface constituting the pressure introducing groove of the present invention

Claims (1)

A piston is slidably provided on the cylinder tube, and a cylinder head is provided at the end of the cylinder tube. A piston rod provided on the piston is projected outward from the cylinder head, and pressure fluid is supplied from a cylinder port formed on the cylinder tube. The piston is reciprocated by supplying or discharging the pressure fluid therefrom, while being provided on the piston rod side and the cylinder head side, and is movable in the axial and radial directions. When the cushion ring enters the cushion seal, the cushion function is exhibited, and at this time, the high pressure generated in the cylinder tube causes the anti-piston side contact surface of the cushion seal to On the cylinder head In the cushion structure of a cylinder which was configured to be disciplined, the contact surface of the cylinder head side opposite piston side contact surface or the opposite piston side contact surface of the cushion seal contact to form a pressure introduction annular grooves, in the pressure introduction groove Cylinder cushion structure characterized by a configuration that guides the high pressure generated when the cushion function is performed.

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