JP2864298B2 - Sealing device for piston peripheral surface of high-speed rotating cylinder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylinder device which is mounted on a machine element which rotates at a high speed around an axis, such as a spindle of a machining center, and more particularly, seals a peripheral surface of a piston inserted into a cylinder. Related to the device.

[0002]

2. Description of the Related Art Generally, in a sealing device for a piston peripheral surface,
A rectangular O-ring groove is formed in a cross-sectional view on the outer peripheral surface of the piston, and a sliding gap between the inner peripheral surface of the cylinder and the outer peripheral surface of the piston is sealed by a rubber O-ring attached to the O-ring groove. is there. The width of the groove is set to a value larger than the thickness of the O-ring. The total dimension of the depth of the groove and the sliding gap is set to a value smaller than the thickness of the O-ring.

[0003]

The sealing device having the above-mentioned conventional structure cannot be used for a device which rotates at a high speed such as a spindle of a machining center. That is, when the cylinder and the piston rotate at a high speed, a strong centrifugal force acts on the O-ring, so that the O-ring is separated from the groove bottom wall.
As a result, the fluid in the high pressure chamber on one end side of the piston easily leaks to the low pressure chamber on the other end side between the O-ring and the groove side wall. An object of the present invention is to reliably seal a piston peripheral surface of a high-speed rotation cylinder.

[0004]

In order to achieve the above object, the present invention provides, for example, FIGS. 1 and 8 or FIGS.
1, the sealing device was configured as follows.

(Invention of claim 1) A piston 11 is inserted into a cylinder 10 which rotates at high speed around an axis, a low pressure chamber 13 is provided at a first end side of the piston 11, and a high pressure chamber 13 is provided at a second end side. And an outer peripheral surface 11a of the piston 11
A first groove 41 is formed in the first groove 41, and the first groove 41
The cylinder 10 and the piston 1 are
In the sealing device for the peripheral surface of the piston of the high-speed rotating cylinder configured so as to seal the sliding gap C between the first seal member 46 and the first seal member 46, The seal width Ww is set to substantially the same value, and the total dimension of the depth dimension F of the first groove 41 and the sliding gap C is larger than the seal height Wh of the first seal member 46 of the above. And a bottom space 41c communicating with the high-pressure chamber 12 is formed in the first groove 41, and the first space 41c of the first groove 41
A pressing surface 41d that comes into contact with the peripheral surface of the first seal member 46 on the first end side is provided in the end fillet portion 41a.

(Invention of claim 2) In the structure of claim 1, a second groove 42 is formed on the outer peripheral surface 11a of the piston 11 at a first end side from the first groove 41, and 2
The sliding gap C is configured to be able to be sealed by the second seal member 45 mounted in the groove 42, and the width dimension G of the second groove 42 is set to a value larger than the seal width Vw of the second seal member 45. And the total dimension of the depth dimension H of the second groove 42 and the sliding gap C is set to a value smaller than the seal height Vh of the second seal member 45 of the above. In each of the above configurations, the seal members 46 and 45 may be an O-ring or an X-ring made of an elastic member such as rubber.

[0007]

The present invention operates as follows, for example, as shown in FIGS. FIG. 1 shows a cylinder 10 and a piston 1
8 shows a state where the motor 1 is rotating at a low speed or stopped.
Shows a state in which the cylinder 10 and the piston 11 are rotating at high speed. In FIG. 1, when no pressure is generated in the high-pressure chamber 12, the first seal member 46
It is pressed downward and outward by the pressing surface 41d, and lightly contacts the inner peripheral surface 10b of the cylinder 10.

When the pressure in the high-pressure chamber 12 increases, the pressure also acts on the bottom space 41c of the first groove 41. As a result, the first seal member 46 is pressed outward by the differential pressure corresponding to the difference between the inner pressure receiving width P and the outer pressure receiving width Q, and lightly contacts the upper wall of the first groove 41, and slides. The moving gap C is sealed.

As shown in FIG. 8, when the cylinder 10 and the piston 11 rotate at a high speed, a strong centrifugal force acts on the first seal member 46. Then, the first seal member 46 becomes
The centrifugal force causes the cylinder inner peripheral surface 10 b to be strongly pressed and swelled up and down, thereby strongly sealingly contacting the upper and lower walls of the first groove 41. Thereby, the high pressure chamber 1
2 is reliably prevented from leaking into the upper low-pressure chamber 13. Therefore, even in the high-speed rotation state, the high-pressure chamber 1
2 can be maintained at a high pressure.

(Invention of claim 2) The second seal member 45 operates as follows. In the low-speed rotation state or the rotation stop state shown in FIG. 1, when the fluid L leaks to the upper side of the first seal member 46 for some reason, the second seal is caused by the pressure of the leaked fluid L. The member 45 sealingly contacts the cylinder inner peripheral surface 10 b and the upper wall of the second groove 42.
Thus, leakage from the high-pressure chamber 12 to the low-pressure chamber 13 can be reliably prevented. In this case, both seal members 46 and 45
When the high-pressure chamber 12 is depressurized, the first seal member 46 is pressed rightward and downward by the depressurized operation, and the first seal member 46 is pressed. The sealing surface between the cylinder 11 and the cylinder inner peripheral surface 10b is automatically opened, so that the sliding movement of the piston 11 is not hindered.

[0011]

【Example】

(First Embodiment) FIGS. 1 to 8 show a first embodiment, in which the sealing device of the present invention is applied to a tool lock device of a machining center. As shown in FIGS. 2 and 3, in a casing 23 fixed to a spindle head 22 of a vertical machining center 21, a spindle 24 is rotatably supported by a plurality of bearings 25 and a motor 2.
6 is driven to rotate at a high speed. A draw bar 28 is fitted inside the main shaft 24 so as to be freely slidable up and down, and a collet 29 is connected to a lower portion of the draw bar 28.

When the tool holder 30 is clamped to the main shaft 24, the draw bar 28 is elastically pressed upward against the main shaft 24 by a plurality of disc springs 31 and the collet 29 is pressed.
Is reduced and the tool holder 30 is clamped to the holder receiving surface 24 a of the main shaft 24 via the pull bolt 32.
Reference numeral 33 denotes a tool. On the other hand, when the tool holder 30 is unclamped, the pneumatic hydraulic booster 34
The draw bar 28 is driven downward against the disc spring 31 by the pressing force of the output part 35, and the collet 29 is expanded and lowered to allow the tool holder 30 to be extracted.

In the above configuration, the clamp holding device 8 for holding the tool holder 30 in the clamped state.
A switching device 9 for switching between them is provided above the main shaft 24. The cylinder 1 of the clamp holding device 8
Numeral 0 is fixed to the upper part of the main shaft 24 with screws. The switching device 9 is provided in the internal space of the cylinder 10. In the air hydraulic booster 34, reference numeral 36 denotes a compressed air supply nozzle. An air blow channel 39 is formed in the draw bar 28 so that the upper end of the channel 39 can communicate with the air supply hole 40 in the output unit 35 of the booster 34.

Referring to the schematic view of FIG. 4 and FIGS. 5 to 7, the clamp holding device 8 and the switching device 9 will be specifically described. The clamp holding device 8 is configured such that the cylindrical piston 11 and the cylindrical piston rod 43 are slidably inserted into the cylinder 10 in a liquid-tight manner by upper and lower seal members 45 and 46 and 47 and 48, respectively. The piston 11 and the piston rod 43 are fixed to the draw bar 28 via a cylindrical pressing tool 49, a washer 50, and a nut 51 in this order. A liquid sealing chamber 12 which is a high pressure chamber is formed below the piston 11 (second end side), and a liquid supply / discharge chamber 13 which is a low pressure chamber is formed above the piston 11 (first end side). Both chambers 12 and 13 are provided with oil L through an oil supply hole 53 provided in the upper wall 10a of the cylinder 10.
Is supplied.

The oil supply hole 53 and its plug 54 are
A plurality of pistons 11 are provided symmetrically with respect to the axial center, so that rotational balance can be obtained. Among the seal members of the piston 11 and the piston rod 43, the first seal members 46 and 47 on the side closer to the liquid seal chamber 12 function as seal members for medium / high-speed rotation, and are farther from the liquid seal chamber 12. Second
The seal members 45 and 48 are configured to function as seal members for low-speed rotation or during rotation stop.

The switching device 9 includes a communication passage 14 formed in the piston 11 and communicating the upper and lower chambers 12 and 13.
And a check valve 56 interposed in the communication passage 14. That is, an annular check valve chamber 57 and a check valve seat 58 are formed in the annular communication passage 14 formed around the axis of the piston 11 in order from the bottom. The check valve seat 58 is disposed downward at a halfway height of the pressing tool 49. A check valve body 59 inserted into the check valve chamber 57 in a liquid-tight sliding manner in a vertical direction is provided with a check spring 60.
This causes the check valve seat 58 to be elastically closed.

A cylindrical unclamping input member 63 is fitted over the pressing tool 49 so as to penetrate the upper wall 10a of the cylinder 10 so as to be slidable in a liquid-tight manner in the vertical direction. The input member 63 is pressed against the washer 50 by a return spring 67 and faces the booster output unit 35. Further, a check valve valve opening device 66 is fixed to a lower portion of the input member 63. The valve opening member 66 is driven downward by the pressing force of the booster output portion 35 against the return spring 67 to separate the check valve body 59 from the check valve seat 58. An unclamping start stroke M, which is a contact gap between the unclamping input portion 69 provided at a halfway height of the pressing tool 49 and the input member 63, is opposite to the valve opening tool 66. The value is set to a value larger than the valve opening start stroke N which is a contact gap with the stop valve body 59.

The cross-sectional area for oil storage of the liquid supply / discharge chamber 13 is such that the pressing tool 4
9 and the input member 63, the cross-sectional area is smaller than the cross-sectional area of the liquid seal chamber 12.
The shortage of the cross-sectional area is compensated for by forming the liquid spill chamber 71. The liquid release chamber 71 is also provided at a plurality of locations symmetrically about the axis of the piston 11. Further, a disk-shaped partition wall 73 for preventing gas-liquid mixing is protruded from the valve opening member 66 toward the cylinder inner peripheral surface 10b.

The above-described spring clamp 1 operates as follows. In the clamped state shown in FIG. 5, the booster output unit 35 rises and returns, and the draw bar 28 is upwardly elastically pressed to the clamp position X by the disc spring 31 (see FIG. 3 or 4), and the unclamping input member 63 and the valve opening device 66 is a return spring 67
Is suppressed by the raised position. As a result, the check valve body 59 is brought into close contact with the check valve seat 58 by the check spring 60, the oil L is sealed in the liquid seal chamber 12, and the clamp holding device 8 is in the locked state R. .

In the clamped state, the spindle 24 is driven to rotate at a high speed, and the work is machined. Here, the cutting performance of the tool 33 depends on the processing conditions such as the feed speed, the number of revolutions, the cutting depth, etc. of the tool 33 (see FIG. 3) and the material of the work, or the swarf of the chip during pocket machining. Is worsened, a lowering force than the elastic force of the disc spring 31 acts on the tool 33, and the draw bar 28
And the piston 11 is to be lowered. Then, the internal pressure of the liquid sealing chamber 12 rises to prevent the piston 11 from being lowered, and the draw bar 28 is held at the clamp position X. As a result, the tool holder 30 is attached to the holder receiving surface 2 of the spindle 24.
4A is strongly prevented from falling off.

During rotation of the main shaft 24, the oil in the liquid supply / discharge chamber 13 is pressed against the peripheral wall of the cylinder 10 by centrifugal force, as shown by a two-dot chain line K in FIG. However, since the partition wall 73 prevents the upper space of the check valve body 59 from communicating with the gas phase (air portion), the air in the liquid supply / discharge chamber 13 becomes oily in the liquid seal chamber 12. L is prevented from being mixed. Thereby, the incompressibility of the oil L in the liquid sealing chamber 12 can be prevented from being impaired, and the function of holding the clamp can be kept good.

When the tool is replaced, the rotation of the main shaft 24 is stopped in the clamped state shown in FIG. 5, and then the state is switched to the unclamped state shown in FIG. 7 through the switching transition state shown in FIG. That is, in the clamped state shown in FIG.
Is driven to lower the booster output section 35, and the output section 35 starts to lower the input member 63. Then, the input member 63 first descends by the contact gap N to contact the check valve body 59, and then the check valve body 5
9 to separate it from the check valve seat 58,
Is released, the clamp holding device 8 is switched to the unlocked state U, and further lowered by the distance (MN) to come into contact with the input portion 69, thereby switching to the switching transient state of FIG.

Subsequently, the input member 63 is driven downward by the booster output section 35, so that the oil L in the liquid sealing chamber 12 is supplied through the communication passage 14 to supply the liquid L as shown in the unclamped state in FIG. The piston 11 is allowed to descend to the discharge chamber 13, and the draw bar 28 descends by the unclamping stroke S and switches to the unclamping position Z. The switching from the unclamped state in FIG. 7 to the clamped state in FIG. 5 is performed in the reverse procedure.

Next, the outer peripheral surface 11a of the piston 11
1 and FIG. 8 will be described. FIG.
Shows a state in which the main shaft 24 of the machining center 21 is rotated at a low speed, and the cylinder 10 and the piston 11 are rotating around the axis at a low speed. FIG. 8 shows a state in which the cylinder 10 and the piston 11 are rotating at a high speed.

In FIG. 1, the outer peripheral surface 11 of the piston 11
A first seal member 46 made of an O-ring having an original thickness W is mounted in the first groove 41 formed in the first groove 41a, and the seal member 46 seals a sliding gap C between the cylinder 10 and the piston 11. It is. The width E of the first groove 41 is set to substantially the same value as the seal width Ww of the seal member 46, and the total dimension of the depth F of the groove 41 and the sliding gap C is determined by the seal member. 46 seal height W
Set to a value greater than h. Since the first seal member 46 is substantially circular in cross section, the seal width Ww and the seal height Wh are equal to the original thickness W.

The bottom space 41c of the first groove 41 communicates with the liquid sealing chamber 12 through the communication passage 14. Furthermore, the upper side of the upper and lower fillet portions 41a and 41b of the above-mentioned groove 41
The pressing surface 41 d is projected from the fillet portion 41 a (first end side) toward the center of the groove 41. The pressing surface 41d is
The sealing member 46 comes into sealing contact with the upper peripheral surface of the peripheral surface of the sealing member 46 and presses the sealing member 46 against the inner peripheral surface 10 b of the cylinder 10.

A second seal member 45 made of an O-ring having an original thickness V is mounted in a second groove 42 formed above the first groove 41. The second groove 42
Is a generally used shape, the width dimension G of which is set to a value larger than the seal width Vw of the second seal member 45, and the depth dimension H and the sliding gap C described above. The total size is set to a value smaller than the seal height Vh of the second seal member 45. The second sealing member 45
Also, since the cross section is substantially circular in cross section, the seal width Vw and the seal height Vh are equal to the original thickness V.

When the cylinder 10 is rotating at a low speed or stopped, the above-mentioned seal members 46 and 45 operate as follows. During normal operation in which no pressure is generated in the liquid seal chamber 12 which is a high-pressure chamber, the first seal member 46 elastically contacts the upper and lower walls of the first groove 41 and the inner peripheral surface 10b of the cylinder 10, and The sealing member 45 also elastically contacts the top and bottom walls of the second groove 42 and the inner peripheral surface 10b of the cylinder 10, and the sliding gap C is sealed.

When the pressure of the oil L in the liquid sealing chamber 12 rises due to the above-described lowering force acting on the piston 11, the pressure acts on the bottom space 41 c of the first groove 41 from the communication passage 14. As a result, the first seal member 46 has the inner pressure receiving width P
Is pressed against the inner peripheral surface 10b of the cylinder 10 by a differential pressure corresponding to the difference between the outer pressure receiving width Q and the outer pressure receiving width Q, thereby sealing the sliding gap C. When the pressure oil leaks to the upper side of the first seal member 46 for some reason, the leaked pressure oil is sealed by the second seal member 45. In this case, both seal members 46
Even if the pressurized oil is trapped during 45, when the liquid sealing chamber 12 is depressurized, the first seal member 46 is pressed to the lower right by the trapped pressure oil, and the Since the sealing surface between the one seal member 46 and the inner peripheral surface 10b of the cylinder 10 is automatically opened, the sliding movement of the piston 11 is not hindered.

As shown in FIG. 8, when the cylinder 10 and the piston 11 rotate at a high speed, each of the sealing members 45.
Since a strong centrifugal force acts on 46, the upper second seal member 45 is separated from the bottom wall of the second groove 42. Therefore, with only the second seal member 45, the pressure oil L in the liquid sealing chamber 12 may leak upward from between the upper wall of the second groove 42 and the second seal member 45. On the other hand, the lower first seal member 46 is swelled up and down by being strongly pressed against the inner peripheral surface 10b of the cylinder 10 by the centrifugal force described above, so that the upper wall and the lower wall of the first groove 41 are formed. Strong sealing contact with the wall. Therefore, the pressure oil L in the liquid sealing chamber 12 does not leak upward. Therefore, even in the high-speed rotation state, the inside of the liquid sealing chamber 12 can be held at a high pressure, and the clamp holding performance can be kept good.

When the first seal member 46 swells due to a change over time, the swollen portion is accommodated in the bottom space 41c of the first groove 41, so that the seal member 46 moves to the sliding gap C. It can be prevented from protruding.
Therefore, the sealing life is long.

The width dimension E of the first groove 41 may be the same as the seal width Ww of the first seal member 46 in order to ensure the sealing performance during high-speed rotation. It may be slightly larger than the seal width Ww. However, in order to ensure the sealing performance at the time of low-speed rotation or rotation stop, as shown in FIG.
Is preferably smaller than the seal width Ww.
Thus, the second groove 42 and the second seal member 45 can be omitted.

As shown in FIG. 5, the sealing portion between the piston rod 43 and the cylinder 10 and the piston 11
The sealing portion between the first groove 41 and the check valve body 59 is also provided.
And the first seal member 46.

The present invention can of course be applied to not only machining centers but also other machine tools and industrial machines. Further, the fluid to be sealed may be another fluid liquid such as glycerin instead of the oil L,
It may be a gas body.

FIGS. 9 to 11 show first to third modifications, respectively, and are partial views corresponding to FIG. In each modification, members having the same functions as those in FIG. 1 are denoted by the same reference numerals. In the first modification of FIG. 9, the pressing surface 41d of the fillet portion 41a on the upper end side is formed in a substantially right angle.
In the second modification of FIG. 10, the above-mentioned pressing surface 41d is formed in a U-shape. In a third modification of FIG. 11, the pressing surface 41d is formed in a horizontal U-shape.

(Second Embodiment) FIG. 12 shows a second embodiment and shows a clamp holding device 8 used for a relatively large machining center. In the second embodiment, members having the same functions as those in the first embodiment are given the same reference numerals in principle. The lower part of the cylinder 10 is fixed to the upper flange 74 of the main shaft 24 by a plurality of bolts 75. Further, a cylindrical bolt 96 is inserted between the piston 11 and the piston rod 43. By screwing the lower part of the bolt 96 to the upper part of the draw bar 28,
The piston 11 and the piston rod 43 are connected to the cylindrical pressing member 4.
9 and the drawbar 28 are fixedly held therebetween.

A rotor 97a of a rotary joint 97 for supplying a cutting fluid is fixed above the cylindrical bolt 96. During the machining operation of the machining center, the rotary joint 97
The cutting fluid that has been pressure-fed to the tool 33 (FIG. 3) flows sequentially through a distribution fitting 81 provided inside the bolt 96 and an annular fluid passage 83 outside the center pipe 82, as indicated by the solid arrow. Ref.). Thereby, the tool 33 can be cooled strongly when performing deep hole processing or heavy cutting.

During the unclamping drive, after the booster output section 35 comes into contact with the unclamping input member 63, the compressed air which has been pressure-fed to the air supply port 35a of the output section 35 is indicated by a broken arrow. The input member 63
The distribution fitting 81 and the pipe 82
Flows downward in the order of the air blow channel 39 to clean the holder receiving surface 24a (see FIG. 3).

Further, a sliding gap between the check valve body 59 of the check valve 56 and the piston 11 is sealed by an X-ring 98. The dimensional relationship between the X ring 98 and the ring mounting groove is substantially the same as the dimensional relationship between the first seal member 46 and the first groove 41 in FIG.

[0040]

The present invention has the following effects because it is constructed and operates as described above. (Invention of Claim 1) At the time of high-speed rotation, the first seal member swells up and down by being strongly pressed against the inner peripheral surface of the cylinder by strong centrifugal force, and the upper wall and the lower wall of the first groove. Strong sealing contact. Thereby, it is possible to strongly prevent the fluid in the high pressure chamber from leaking to the low pressure chamber.

Further, even if the first seal member swells due to aging or the like, it is possible to prevent the first seal member from protruding into the sliding gap by storing the swollen portion in the bottom space of the first groove. So long life.

(Invention of Claim 2) In the low-speed rotation state or the rotation stop state, if the sealing function of the first seal member is impaired, the leaked fluid is sealed by the second seal member. Therefore, leakage from the high-pressure chamber to the low-pressure chamber can be reliably prevented.

[Brief description of the drawings]

FIG. 1 is a view showing a first embodiment and showing a low-speed rotation state of a cylinder, and is a partially enlarged view of a spring clamp shown in FIG. 5;

FIG. 2 is a front view of a machining center provided with the spring clamp.

FIG. 3 is a sectional view taken along line III-III of FIG. 2;

FIG. 4 is a schematic diagram corresponding to FIG.

FIG. 5 is a longitudinal sectional view showing a clamped state of the spring clamp.

FIG. 6 is a vertical cross-sectional view showing a transition state of the same spring clamp in a switching state.

FIG. 7 is a longitudinal sectional view showing an unclamped state of the spring clamp.

FIG. 8 is a view showing a high-speed rotation state of the cylinder and corresponding to FIG. 1;

FIG. 9 shows a first modified example and is a partial view corresponding to FIG. 1;

FIG. 10 shows a second modification, and is a partial view corresponding to FIG. 1;

FIG. 11 shows a third modification, and is a partial view corresponding to FIG. 1;

FIG. 12 is a view showing a second embodiment and corresponding to FIG. 5;

[Explanation of symbols]

10: cylinder, 11: piston, 11a: outer peripheral surface, 1
2: High pressure chamber (liquid sealing chamber), 13: Low pressure chamber (liquid supply / discharge chamber), 41:
1st groove, 41a ... fillet, 41c ... bottom space, 41d ...
Pressing surface, 42 second groove, 45 second seal member, 46
First seal member, C: sliding gap, E: width of first groove 41, F: depth of first groove 41, G: width of second groove 42, H: depth of second groove 42 Dimensions, Vw: seal width of the second seal member 45, Vh: seal height of the second seal member 45, Ww: seal width of the first seal member 46, Wh: seal height of the first seal member 46.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁶ , DB name) B23B 31/30 F16J 15/16 B23B 31/117

Claims (4)

(57) [Claims] A cylinder (1) rotated at high speed around an axis.
0), insert the piston (11) into the piston (11).
A low-pressure chamber (13) is provided on the first end side and a high-pressure chamber (12) is provided on the second end side, and an outer peripheral surface (1) of the piston (11) is provided.
1a), a first groove (41) is formed, and the first seal member (46) inserted into the first groove (41) is used to form the cylinder (1).
0) and the piston (11), in which the sliding gap (C) can be sealed, the sealing device for the peripheral surface of the piston of the high-speed rotation cylinder, wherein the width of the first groove (41) is (E) is set to substantially the same value as the seal width (Ww) of the first seal member (46), and the depth dimension (F) of the first groove (41) and the sliding gap are set.
(C) is set to a value larger than the seal height (Wh) of the first seal member (46) in the same manner as above, and the high pressure chamber (12) is inserted in the first groove (41). A bottom space (41c) communicating with the first groove (41) is formed in the fillet (41a) on the first end side of the first groove (41). A sealing device for a peripheral surface of a piston of a high-speed rotating cylinder, wherein a pressing surface (41d) contacting the surface is provided. 2. The sealing device for sealing a peripheral surface of a piston of a high-speed rotary cylinder according to claim 1, wherein the piston (1) is located on a first end side of the first groove (41).
A second groove (42) is formed on the outer peripheral surface (11a) of 1), and the sliding gap (C) can be sealed by a second seal member (45) mounted in the second groove (42). The width dimension (G) of the second groove (42) is set to the second sealing member.
(45) is set to a value larger than the seal width (Vw), and the depth dimension (H) of the second groove (42) and the sliding gap described above are set.
The sum of (C) and the dimension is set to a value smaller than the seal height (Vh) of the second seal member (45). 3. The sealing device for sealing a peripheral surface of a piston of a high-speed rotating cylinder according to claim 1 or 2, wherein the first seal member (46) is formed by an O-ring having a substantially circular cross section. 4. The sealing device for a peripheral surface of a piston of a high-speed rotating cylinder according to claim 1, wherein the first seal member is formed by an X-shaped X-ring in a cross-sectional view.