JP5903021B2 - Braking device using seal ring - Google Patents

Description

  The present invention relates to a braking device, and more particularly to a braking device using a seal ring such as an O-ring used when braking is applied to the movement of a door when a sliding door is completely closed or opened.

  For example, when closing a sliding door, various devices have been developed for applying a braking force to the sliding door when it is closed in order to prevent the sliding door from strikingly hitting the door frame. One type of such device consists of a combination of a piston and a cylinder, where one of the piston and cylinder is fixed horizontally to the door frame, and a sliding door that moves toward the closing completion position just before the closing of the door, The sliding door is braked by engaging with the other of the piston and the cylinder to cause a relative movement between the piston and the cylinder and generating a resistance to the movement of the fluid in the cylinder by the relative movement.

  More specifically, in the braking device including the piston and the cylinder as described above, when relative movement occurs between the piston and the cylinder, the flow resistance against the fluid flowing from one side of the piston to the other side is reduced. There is a member using a seal ring such as an O-ring as an increasing channel restricting member (for example, Patent Documents 1 and 2).

Special table 2009-529641 2-4036

  The O-ring is widely used as a seal member and can be obtained at a low price. In this regard, there is an advantage when used as a channel restricting member. However, an O-ring as a seal member is between two members that cause relative movement, such as a seal between the rotating shaft and its shaft hole, and a seal between the end surface of the rotating shaft and the flange surface facing it. It is a common usage that it is set and sealed between both members. For such a normal usage mode of the O-ring, in the braking device composed of the piston and the cylinder described above, the O-ring used as the flow passage restricting member is also disclosed in Patent Documents 1 and 2. As can be seen, an O-ring is set on the peripheral surface of the piston, and when the relative movement between the piston and the cylinder occurs, the O-ring is pressed by the fluid pressure, and the peripheral surface of the piston and the inner periphery of the cylinder The flow path is restricted with respect to the gap (flow path) between the surface and the required braking function.

  For this reason, since the O-ring slides with the inner peripheral surface of the cylinder that moves relative to the piston, the O-ring receives sliding friction and therefore easily wears.

  It is an object of the present invention to provide a braking device that uses a low-cost O-ring as a flow path restricting member and that does not basically cause the above-described problem of O-ring wear. However, an object of the present invention is to provide a braking device that can avoid the above-described wear problem not only in the O-ring but also in various seal rings.

That is, the present invention
A cylinder adapted to seal the fluid;
A rod extending in the longitudinal axis direction of the cylinder in the cylinder and extending outside from at least one end of the cylinder, and the longitudinal axis direction along the inner peripheral surface of the cylinder connected to the rod And a piston rod comprising a piston that divides the inside of the cylinder into a first chamber and a second chamber, and the relative movement of the cylinder when the cylinder moves relative to the piston rod. In a braking device that generates a braking force against the relative movement by adding resistance to the fluid in the cylinder flowing from one of the first chamber and the second chamber to the other with movement.
The piston
A first end face facing the first chamber; a second end face facing the second chamber;
An annular seal ring chamber provided concentrically with the rod and accommodating a seal ring, the seal ring chamber annular end surface being engageable with the accommodated seal ring on the second end surface side; and An annular seal ring chamber having a cylindrical outer peripheral surface extending from the annular end surface of the seal ring chamber toward the first end surface in the radial direction of the seal ring, and communicating with the first chamber;
A communication path extending between a first opening provided on the annular end surface of the seal ring chamber and a second opening provided on the second end surface;
Have
When the cylinder moves in the longitudinal direction relative to the piston rod, the seal ring is pressed against the annular end surface of the seal ring chamber and elastically deforms, and passes from the first chamber to the annular seal ring chamber. Provided is a braking device using a seal ring which limits the area of a flow path toward the first opening of the communication path.

  When this braking device is used, for example, as a braking device when a sliding door is tightened, one of the piston rod and cylinder, for example, the rod is set horizontally on the upper part of the door frame, and the first end surface of the piston faces the door opening direction. When the sliding door is closed from the door opening position toward the door closing position and approaches the door closing completion position, the sliding door engages with the cylinder so that the second end surface faces the door closing direction. -It can also be set so that the piston rod moves relatively into the cylinder by moving along the rod in the closing direction. When the sliding door is closed at a high speed, the cylinder is suddenly moved to take the annular seal ring chamber and the communication path from the first end face side of the piston to the second end face side. This is pressed against the end face, whereby the seal ring is elastically deformed to limit the flow area of the flow path from the annular seal ring chamber to the first opening of the communication path. As a result, the fluid trying to pass through the flow path is subjected to resistance according to the restriction, whereby the sliding door is braked. At this time, the seal ring in the annular seal ring chamber of the piston / rod does not slide with other parts, and therefore is not subjected to wear like the seal ring in the above-described conventional braking device. In setting the sliding door frame of this braking device, the rod is set horizontally on the upper part of the door frame, the first end surface of the piston faces the door opening direction, the second end surface faces the door closing direction, When the door is closed from the opening position toward the closing position and approaches the closing position, the sliding door engages with the cylinder, moves the cylinder along the piston rod in the closing direction, and the piston rod Alternatively, it can be set so as to be pulled out of the cylinder. Also, the cylinder can be fixed to the sliding door frame so that the piston rod is moved by the sliding door.

In particular,
The piston has a shaft hole penetrating in the longitudinal direction, and the rod is fixed through the shaft hole;
The annular seal ring chamber can be opened over the entire circumference of the shaft hole.

  In this case, the seal ring is set immediately around the rod. However, even if the cylinder moves relative to the piston / rod, the rod and the piston are connected. It doesn't move.

When the cylinder moves relative to the piston rod in the longitudinal direction, the first portion of the communication hole is located at a position radially outward from a portion where the seal ring is pressed against the annular end surface of the seal ring chamber. The opening is open,
The seal ring pressed against the annular end surface of the seal ring chamber is elastically deformed to reduce a gap between the seal ring and the cylindrical outer peripheral surface of the seal ring chamber, thereby limiting the flow path area. be able to.

  In another example, the communication passage extends from the first opening extending in the radial direction to the annular ring end surface of the seal ring chamber to the second opening opening in the radial direction to the second end surface of the piston. It can also be made up of at least one slit.

  The seal ring chamber cylindrical outer peripheral surface of the annular seal ring chamber extends from the seal ring chamber annular end surface toward the first end surface, and the first region at a position away from the seal ring chamber annular end surface. A second region following the region, and when the cylinder moves relative to the piston rod in the longitudinal direction and the seal ring is pressed against the annular end surface of the seal ring chamber, The seal ring is displaced into the second region by the fluid passing through the annular seal ring chamber when the cylinder moves relative to the piston rod in the longitudinal direction. The second region may have a larger diameter than the first region.

  When this braking device is used as, for example, a braking device when a sliding door is tightened, the cylinder is moved from the second end to the first end when the closed sliding door is opened. However, when the cylinder is moved in the direction from the second end to the first end with respect to the piston rod, the flow of fluid in the cylinder is the reverse of that in the case of closing the door. In addition, the flow from the second chamber to the first chamber is changed, and the seal ring is displaced to the second region having a large diameter of the annular seal ring chamber, so that the resistance to the flow of the fluid is greatly reduced and the opening operation is performed with a small force. It is possible to do.

  The rod may extend from the piston in the longitudinal direction and extend outward from both ends of the cylinder.

  If it does in this way, the said braking device can be set by fixing the both ends of a rod to the upper part of a door frame. Further, if the same diameter is provided over the entire length of the rod portion that may be inside the cylinder due to movement in the longitudinal direction, even if the piston rod is displaced in the longitudinal direction, the total of the first chamber and the second chamber The volume is constant, and an incompressible fluid such as oil can be used as the fluid stored in the cylinder.

  The annular seal ring chamber is concave from the first end surface to the second end surface of the piston, and the first end surface has an annular shape that prevents the seal ring from coming off the seal ring chamber. A stop member may be provided.

  Moreover, it has the permanent magnet provided in this rod extended from the edge part of this cylinder, and this permanent magnet can be couple | bonded by a magnetic force with a sliding door. Thus, when the closed sliding door is moved in the opening direction, the piston rod moved by the closing sliding door is moved together with the opening sliding door and returned to the initial standby position. I can do it.

  On the contrary, it has a permanent magnet provided in the cylinder, and the permanent magnet can be coupled to the sliding door by magnetic force. Thus, when the closed sliding door is moved in the opening direction, the piston rod moved by the closing sliding door is moved together with the opening sliding door and returned to the initial standby position. I can do it.

  The seal ring is preferably an O-ring. The O-ring is widely used, can be obtained at low cost, and is ready for setting.

  DESCRIPTION OF EMBODIMENTS Hereinafter, an embodiment in which a braking device according to the present invention is used for a sliding door braking device upon completion of closing will be described with reference to the accompanying drawings.

It is embodiment when the braking device using the seal ring which concerns on this invention is used for the braking of the sliding door just before closing, and shows the said braking device when using an O-ring as a seal ring in the longitudinal section. It is a figure which shows the relationship between the cylinder of a braking device using the seal ring of FIG. 1, and a piston rod, and the relationship structure of a piston and a rod. It is a figure which shows the motion of the fluid in a cylinder when a cylinder is suddenly moved to the door closing direction in the braking device using the seal ring of FIG. It is a figure which shows the motion of the fluid in a cylinder when a cylinder is moved to a door closing direction comparatively gently in the braking device using the seal ring of FIG. It is a figure which shows the motion of the fluid in the braking device using the seal ring of FIG. 1 when a sliding door is opened. It is a front view of the braking device using the seal ring which concerns on other embodiment. It is a longitudinal cross-sectional view of the braking device using the seal ring of FIG. FIG. 8 is a longitudinal side view of a piston in a braking device using the seal ring of FIG. 7. The end view of the piston in the braking device using the seal ring of FIG. 7 is shown. It is a longitudinal cross-sectional view of the braking device using the seal ring which concerns on other embodiment. It is a fragmentary sectional view which shows the relationship between a piston and a seal ring at the time of using a Y-shaped seal ring.

  The basic configuration of the braking device 10 using the seal ring according to the present invention shown in FIG. 1 will be described as follows. The braking device 10 according to this embodiment uses an O-ring as a seal ring. Therefore, the above-described “annular seal ring chamber”, “seal ring chamber annular end surface”, and “seal ring chamber cylindrical outer peripheral surface” are respectively , “Annular O-ring chamber”, “O-ring chamber annular end surface”, and “O-ring chamber cylindrical outer peripheral surface”.

  The brake device 10 has a first end portion 12 and a second end portion 14. The cylinder 16 is configured to seal a fluid. The brake device 10 extends in the longitudinal axis direction of the cylinder 16 in the cylinder 16 and extends in the longitudinal direction of the cylinder 16. A rod 18 extending to the outside from the first end 12 and the second end 14 (at least the second end 14), and connected to the rod 18 and slid along the inner peripheral surface 16A of the cylinder 16 in the longitudinal axis direction. A piston rod 22 including a piston 20 that is movable and partitions the inside of the cylinder 16 into a first chamber 16B on the first end side and a second chamber 16C on the second end side. In the illustrated example, both ends 18 of the rod are fixed to the upper portion of a door frame (not shown) by fixing members 18A and 18B, the cylinder 16 is movable along the rod 18, and the sliding door D is closed when the door is closed. When approaching the completion position in the direction indicated by the arrow A, the sliding door D engages with the cylinder 16 and moves the cylinder 16 in the direction from the first end 12 of the cylinder 16 toward the second end 14 with respect to the piston rod 22. As the cylinder 16 moves relative to the piston rod 22 at this time, a resistance is applied to the fluid a flowing from the first chamber 16B to the second chamber 16C as described in detail below. A braking force against the relative movement is generated. The basic configuration of the braking device 10 according to the present invention is as described above. This is conceptually the same as that disclosed in Patent Document 1 described above, but the present invention further includes the following configuration. Have.

  As shown in FIG. 2, the piston 20 is provided concentrically with the first end surface 24 facing the first chamber 16B, the second end surface 26 facing the second chamber 16C, and the rod 18, so that the O-ring 30 is provided. An annular O-ring chamber 32 to be accommodated, and an O-ring chamber annular end surface 34 which can be engaged with the accommodated O-ring 30 on the second end surface 26 side, and the O-ring chamber annular end surface 34 The O-ring chamber has a cylindrical outer peripheral surface 36 extending outside the O-ring toward the first end surface 24, and is provided on the annular O-ring chamber 32 communicating with the first chamber 16B and the O-ring chamber annular end surface 34. And a communication passage 42 extending between the first opening 38 and the second opening 40 provided in the second end face. A plurality of communication passages 42 are provided at appropriate intervals in the circumferential direction. When the cylinder 16 is engaged by the sliding door D and moves in the direction from the first end 12 to the second end 14 of the cylinder 16 relative to the piston rod 22 as described above, the O-ring 30 is It is pressed against the ring chamber annular end face 34 to be elastically deformed, and restricts the flow area from the first chamber 16B through the annular O-ring chamber 32 to the first opening 38 of the communication passage 42.

  In the illustrated embodiment, the piston 20 has a shaft hole 44 through which the piston rod 22 passes in the longitudinal direction, and the rods 18 are passed through the shaft hole 44 and stop rings 46 and 48 set on both sides of the piston 20. The annular O-ring chamber 32 is opened over the entire circumference of the shaft hole 44. Specifically, the annular O-ring chamber 32 has a concave shape from the first end surface 24 of the piston 20 toward the second end surface 26, and an O-ring 30 extends from the annular O-ring chamber 32 to the first end surface 24. An annular stop ring 50 is provided to prevent the outer side from coming off. The stop ring 50 is provided with a plurality of holes 51 through which a fluid passes in the circumferential direction with a space therebetween. An annular sliding member 20B formed of Teflon (registered trademark) or the like is attached to the outer peripheral surface 20A of the piston 20 with the central portion in the longitudinal axis direction being an annular recess.

  The portion where the O-ring 30 is pressed against the O-ring chamber annular end surface 34 when the cylinder 16 moves relative to the piston rod 22 in the direction from the first end 12 to the second end 14 of the cylinder 16. The first opening 38 of the communication hole 42 is opened at a position on the outer side in the radial direction, and the O-ring 30 pressed against the O-ring chamber annular end surface 34 is elastically deformed to form an O-ring 30 and an O-ring chamber cylindrical shape. The gap g1 between the outer peripheral surface 36 is reduced to limit the flow path area. In the example shown in the drawing, the O-ring 30 has an outer space in which a gap g1 is formed between the O-ring chamber and the cylindrical outer peripheral surface 36 as shown in FIG. In addition to the diameter, the inner diameter is such that a gap g <b> 2 is formed between the outer peripheral surface of the rod 18. Therefore, the O-ring is configured to restrict the flow path to the gap g2 as well as to restrict the flow path to the gap g1.

  As shown in FIG. 2, in the braking device 10 shown in FIG. 1, the O-ring chamber cylindrical outer peripheral surface 36 of the annular O-ring chamber 32 is directed from the O-ring chamber annular end surface 34 toward the first end surface 24 of the piston 20. The first region 36A extending in the direction and the second region 36B tapered from the annular end surface 34 of the O-ring chamber. When the cylinder 16 moves relative to the piston rod 22 in the direction from the first end face 24 to the second end face 26 of the piston 20, the O-ring 30 is in the first region 36 </ b> A, and the cylinder 16 is in the piston rod 22. When the O-ring 30 moves relatively in the direction from the second end portion 14 of the cylinder 16 toward the first end portion 12, the O-ring 30 is displaced into the second region 36B by the fluid passing through the annular O-ring chamber 32. Has been. The second region 36B has a diameter that increases with distance from the first region 36A.

  3 and 4 show a state in which the O-ring 30 restricts the flow area of the gaps g1 and g2 by the cylinder 16 that is engaged and moved by the door D approaching the door closing completion position. FIG. 3 shows a state where the closing speed of the sliding door D is fast and the movement of the cylinder 16 engaged with the sliding door D is fast. At this time, since the volume of the first chamber 16B suddenly decreases due to the movement of the cylinder 16, the fluid in the first chamber 16B is directed toward the second chamber having a larger volume as opposed to the first chamber 16B. Thus, it tries to flow rapidly through the communication passage 42. Therefore, the O-ring 30 is strongly pressed against the O-ring chamber annular end surface 34 by the flow and greatly elastically deforms to engage with the O-ring chamber cylindrical outer peripheral surface 36, and the fluid passing through the gaps g1 and g2 Flow is substantially blocked, whereby the cylinder 16 is prevented from moving and the movement of the sliding door D is braked.

  FIG. 4 shows the braking action when such sliding door D is braked or when the sliding door is moved to the closing completion position at a relatively slow speed. In this case, the flow of fluid from the first chamber 16B toward the second chamber 16C is slow, and therefore the O-ring 30 is pressed against the O-ring chamber annular end surface 34 with a weaker force than in the case of FIG. Therefore, the elastic deformation is small, and therefore, the engagement with the O-ring chamber cylindrical outer peripheral surface 36 is weak. In the example shown in the figure, the gap g2 is completely closed, but the gap g1 is left with a certain amount of flow path and is limited. Thus, the cylinder 16 and the door D to which it is engaged approach the closing position at a slow speed. In this case, both the gaps g1 and g2 may be slightly opened so that the door D moves at a slow speed.

  FIG. 5 shows the flow in the cylinder when the sliding door is moved from the closed position toward the open position. In other words, at this time, the cylinder 16 is moved relative to the piston rod 22 in the door opening direction by means not shown in the drawing with the sliding door toward the door opening position, and the door closing door standby position as shown in FIG. It is returned to (initial position). When such a movement occurs in the cylinder 16, the volume of the second chamber 16C decreases, and the fluid therein flows through the communication path 42 and the annular O-ring chamber 32 to the first chamber 16B as indicated by the arrow b. And The O-ring 30 is moved in the door opening direction by this flow of fluid and is displaced from the first region 36A to the second region 36B in the O-ring chamber cylindrical outer peripheral surface 36. For this reason, the fluid flow b flows without receiving a large resistance by the O-ring 30, and thus the sliding door D moved in the door opening direction is moved with a small force without being influenced by the braking device 10.

  FIG. 6 shows another embodiment of the braking device 10 according to the present invention, and the same reference numerals are assigned to the same elements as those in the embodiment shown in FIG. In this embodiment, instead of the piston rod 22, the cylinder 16 is fixed to the upper portion of the door frame F by the fixing member 52, and the piston rod 22 is attached to the sliding door D with respect to the cylinder 16. (Specifically, it is displaced by a door pulley support member D3 that supports a door pulley D2 fixed to the upper edge D1 of the sliding door D). The structure of the cylinder 16 and the piston rod 22 is basically the same as that of the embodiment shown in FIG. 1, but the piston rod 22 is moved in the closing direction by the sliding door D. In addition, as shown in FIG. 7, the first chamber 16B of the cylinder 16 is set closer to the door closing direction (right side in the drawing) than the piston 20, and the second chamber 16C is set closer to the door opening direction side (left side). When the rod 22 is moved in the closing direction by the sliding door D, the fluid in the cylinder 16 flows from the first chamber 16B through the communication path 42 to the second chamber 16C as in the embodiment of FIG. Has been.

The braking device 10 in FIG. 6 is different from the braking device in FIG. 1 in the following points.
That is, the communication passage 42 of the piston 20 extends from the first opening 38 that extends radially to the O-ring chamber annular end surface 34 to the second opening 40 that extends radially to the second end surface 26 of the piston 20. It is composed of four slits 42.
Further, a permanent magnet 60 is fixed to an end surface of the rod 18 in the door opening direction, and the permanent magnet 60 is engaged by a door wheel support member D3 of the sliding door D toward the door closing completion position, and the piston- When the rod 22 is moved in the door closing direction and the sliding door D is moved in the door opening direction from the door closing completion position, the piston rod 22 is moved in the door opening direction while the permanent magnet 60 is coupled to the door wheel support member D3 by its magnetic force. When the sliding door D reaches a predetermined position (closed door sliding door standby position or initial position), the door support member D3 is uncoupled by the magnetic force of the permanent magnet 60, and only the sliding door is moved in the opening direction. ing.

  The braking device 10 according to yet another embodiment shown in FIG. 9 differs from that of the embodiment of FIG. 7 in that it has a rod 18 that extends from only one end of the cylinder 16. The setting and operation of the braking device 10 according to this embodiment need not be described, but are apparent from the description of the above-described embodiment, and thus the description thereof is omitted. In this braking device 10, air is used as a fluid in the cylinder. The cylinder 16 is communicated with the atmosphere via an adjustable restriction channel 54 and a check valve 56, and the cylinder 16 of the piston rod 22 is connected. When the piston rod 22 is pushed in, the air flows to the atmosphere via the adjustable restriction channel 54. Conversely, when the piston rod 22 is pulled out from the cylinder 16, the air is supplied into the cylinder 16 via the check valve 56. To be made.

  FIG. 10 shows the relationship between the seal ring 30A and the piston 20 when a seal ring 30A having a Y-shaped cross section is used instead of the O-ring. In this case, the Y-shaped bottom portion 30 </ b> B is set toward the seal ring chamber annular end surface 34. In the illustrated example, the pair of Y-shaped branch portion tips 30C and 30D are set so as to be close to the seal ring chamber cylindrical outer peripheral surface 36 and the outer peripheral surface of the rod 18, but only one of the gaps is provided. You can also

  As mentioned above, although embodiment of the braking device concerning this invention was described, this invention is not limited to this, A various change is possible. For example, the braking device according to the present invention can be used not only for sliding doors but also for braking for opening and closing furniture drawers. The means for returning the cylinder or piston rod to the initial position for braking is not limited to that of the embodiment of FIG. 6, and various means such as those using a spring can be used.

Brake device 10; first end 12; second end 14; cylinder 16; rod 18; inner peripheral surface 16A; first chamber 16B; second chamber 16C; Rod 22; first end surface 24; second end surface 26; seal ring (O-ring) 30; seal ring 30A; bottom portion 30B; branch portion tip 30C, 30D; annular seal ring chamber (annular O-ring chamber) 32; Ring chamber annular end surface (O-ring chamber annular end surface) 34; seal ring chamber cylindrical outer peripheral surface (O-ring chamber cylindrical outer peripheral surface) 36; first region 36A; second region 36B; first opening 38; Communication passage 42; shaft hole 44; stop ring 46, 48; stop ring 50; hole 51; fixing member 52; restricting flow path 54; check valve 56; permanent magnet 60; gap g1; ; Door roller D2; door roller supporting member D3

Claims (10)

A cylinder adapted to seal the fluid;
A rod extending in the longitudinal axis direction of the cylinder in the cylinder and extending outside from at least one end of the cylinder, and the longitudinal axis direction along the inner peripheral surface of the cylinder connected to the rod And a piston rod comprising a piston that divides the inside of the cylinder into a first chamber and a second chamber, and the relative movement of the cylinder when the cylinder moves relative to the piston rod. In a braking device that generates a braking force against the relative movement by adding resistance to the fluid in the cylinder flowing from one of the first chamber and the second chamber to the other with movement.
The piston
A first end face facing the first chamber; a second end face facing the second chamber;
An annular seal ring chamber provided concentrically with the rod and accommodating a seal ring, the seal ring chamber annular end surface being engageable with the accommodated seal ring on the second end surface side; and An annular seal ring chamber having a cylindrical outer peripheral surface extending from the annular end surface of the seal ring chamber toward the first end surface in the radial direction of the seal ring, and communicating with the first chamber;
A communication path extending between a first opening provided on the annular end surface of the seal ring chamber and a second opening provided on the second end surface;
Have
When the cylinder moves in the longitudinal direction relative to the piston rod, the seal ring is pressed against the annular end surface of the seal ring chamber and elastically deforms, and passes from the first chamber to the annular seal ring chamber. A braking device using a seal ring that limits an area of a flow path toward the first opening of the communication path. The piston has a shaft hole through which the piston rod passes in the longitudinal direction, the rod being fixed through the shaft hole;
The braking device using a seal ring according to claim 1, wherein the annular seal ring chamber is opened over the entire circumference of the shaft hole. When the cylinder moves relative to the piston rod in the longitudinal direction, the first portion of the communication passage is positioned at a position radially outward from a portion where the seal ring is pressed against the annular end surface of the seal ring chamber. The opening is open,
The seal ring pressed against the annular end surface of the seal ring chamber is elastically deformed to reduce a gap between the seal ring and the cylindrical outer peripheral surface of the seal ring chamber, thereby limiting the flow path area. A braking device using the seal ring according to claim 1.   At least one slit extending from the first opening that extends in the radial direction to the annular ring end surface of the seal ring chamber and the second opening that extends in the radial direction to the second end surface of the piston. A braking device using the seal ring according to claim 1 or 2.   The seal ring chamber cylindrical outer peripheral surface of the annular seal ring chamber extends from the seal ring chamber annular end surface toward the first end surface, and the first region at a position away from the seal ring chamber annular end surface. A second region following the region, and when the cylinder moves relative to the piston rod in the longitudinal direction and the seal ring is pressed against the annular end surface of the seal ring chamber, The seal ring is displaced into the second region by the fluid passing through the annular seal ring chamber when the cylinder moves relative to the piston rod in the longitudinal direction. The braking device using a seal ring according to any one of claims 1 to 4, wherein the second region has a larger diameter than the first region.   The braking device using a seal ring according to any one of claims 1 to 5, wherein the rod extends in the longitudinal direction from the piston and extends outward from both ends of the cylinder.   The annular seal ring chamber is recessed from the first end surface of the piston toward the second end surface, and the first end surface prevents the seal ring from coming out of the annular seal ring chamber. A braking device using a seal ring according to any one of claims 1 to 6, wherein an annular stop member is provided.   The seal ring according to any one of claims 1 to 7, further comprising a permanent magnet provided on the rod extending from an end of the cylinder, wherein the permanent magnet can be magnetically coupled to the sliding door. The braking device used.   The braking device using the seal ring according to any one of claims 1 to 7, further comprising a permanent magnet provided in the cylinder, wherein the permanent magnet can be coupled to the sliding door by a magnetic force.   The braking device using the seal ring according to any one of claims 1 to 9, wherein the seal ring is an O-ring.

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