JP2012177424A - Sealing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sealing device, effectively preventing pressure release causing leakage, by smoothly moving a seal ring 1 in an installation groove 41 according to a relationship between pressures of both sides in an axial direction.SOLUTION: The sealing device is installed in an installation groove 41 circumferentially and continuously formed to one circumferential face 4a of opposed circumferential faces of an outer circumferential member 3 and an inner circumferential member 4 disposed to be concentrically and relatively movable. The sealing device includes: a seal ring 1 disposed slidably with the other circumferential face 3a; and a back ring 2 interposed between the seal ring 1 and a bottom face 41c of the installation groove 41. End faces 1a, 1b of the seal ring 1 are provided with: pressure introduction grooves 11, 12 extending between the inside and the outside of the opposed area between side faces 41a, 41b of the installation groove 41; and pressure reception grooves 13, 14 circumferentially extended in the opposed area, and communicating to the pressure introduction grooves 11, 12.

Description

  The present invention relates to a sealing device used in, for example, hydraulic equipment, and more particularly to a structure in which a seal ring made of a low friction resin material is supported by an elastic buckling.

  For example, as a sealing device for sealing a peripheral gap of a piston or piston rod of a hydraulic device, there is a conventional one as shown in FIG. In FIG. 6, reference numeral 200 is a cylinder such as a hydraulic device, and reference numeral 300 is a piston inserted through the inner periphery of the cylinder 200 so as to be capable of reciprocating in the axial direction.

  The sealing device 100 is mounted in a mounting groove 301 formed on the outer peripheral surface 300a of the piston 300, and is made of a low material such as PTFE (polytetrafluoroethylene) that is slidably brought into close contact with the inner peripheral surface of the cylinder 200. A seal ring 101 made of a friction synthetic resin and a back ring 102 made of a rubber-like elastic material (rubber material or a synthetic resin material having rubber-like elasticity) located on the inner peripheral side thereof are provided. In addition, as a sealing device provided with the structure approximated to FIG. 6, there exist some which were disclosed by the following patent document.

  A plurality of pressure introducing grooves 101c and 101d are formed on both end faces 101a and 101b of the seal ring 101, respectively. The pressure introducing grooves 101c and 101d extend from the outer diameter ends of the end surfaces 101a and 101b to the inner diameter side of the outer peripheral surface 300a of the piston 300, and are formed on different phases.

As shown in FIG. 7, the sealing device 100 having the above configuration is configured such that, for example, the hydraulic pressure from one side in the axial direction (right side in the drawing) is P ₁ , and the hydraulic pressure from the other side in the axial direction (left side in the drawing) is P _2. , P ₁ > P ₂ , the seal ring 101 and the back ring 102 are pressed against the side surface 301 a of the mounting groove 301 and the outer peripheral surface of the seal ring 101 is The outer peripheral surface and the inner peripheral surface of the back ring 102 are brought into close contact with the inner peripheral surface of the seal ring 101 and the bottom surface 301c of the mounting groove 301, thereby sealing performance. Secured.

Further, when the pressure relationship on both sides in the axial direction is reversed from the state shown in FIG. 7 to satisfy P ₁ <P ₂ , the hydraulic pressure P ₂ is introduced into the pressure introduction groove 101 c of the seal ring 101, thereby FIG. As shown in FIG. 4, not only the region (pressure receiving surface S ₁ ) of the end surface 101a of the seal ring 101 on the outer diameter side of the outer peripheral surface 300a of the piston 300 but also the inner diameter side of the outer peripheral surface 300a of the piston 300 of the pressure introducing groove 101c. Since the oil pressure P ₂ also acts as an axial thrust in this region (pressure receiving surface S ₂ ), this oil pressure P ₂ is introduced into the end faces of the seal ring 101 and the back ring 102, and the seal ring 101 and the back ring 102 are As shown in FIG. 9, the mounting groove 301 moves to the low pressure side (right side in the figure) and is pressed against the side surface 301b.

JP-A-6-174105 WO2008 / 126866

However, according to the conventional sealing device 100, for example, even if P ₁ <P ₂ from the state shown in FIG. 7, the pressure receiving surface (seal of back pressure by the hydraulic pressure P ₁ acting on the end surface 101b of the seal ring 101 is used. If the projected area in the axial direction) _{S 3} of the ring 101, for significantly larger than the pressure receiving surface _S 1 + _{S 2} of the hydraulic _{P 2} acting on the end face 101a of the seal ring 101, the pressure difference of the hydraulic _{P 1} and _{P 2} is small, The thrust P ₂ (S ₁ + S ₂ ) that moves the seal ring 101 toward the right side in the figure is likely to be smaller than the drag force P ₁ S ₃ caused by the back pressure, and therefore the seal ring 101 cannot move. Therefore, the hydraulic pressure P ₂ is less likely to be introduced into the mounting groove 301, as a result, not radial expansion force of the buckling 102 is obtained by the hydraulic, insufficient closely force of the seal ring 101 against the inner circumferential surface 200a of the cylinder 200 There is a risk of blowout leakage. This blow-through leak is a troublesome phenomenon, since once it occurs, a large amount of leak may continue for a long time.

Further, the blow-leakage, or when a part of the seal ring 101 protruding into the gap between the outer peripheral surface 300a of the inner peripheral surface 200a and the piston 300 of the cylinder 200 by the rising of the hydraulic _{P 1} or hydraulic _{P 2,} the seal ring This also tends to occur when the tightening allowance of 101 and buckling 102 is reduced.

  The present invention has been made in view of the above points, and its technical problem is that the seal ring can smoothly move in the mounting groove due to the pressure relationship on both sides in the axial direction. An object of the present invention is to provide a sealing device that can effectively prevent blowout leakage.

  As a means for effectively solving the technical problem described above, a sealing device according to the present invention includes one outer peripheral surface of an outer peripheral member and an inner peripheral member arranged concentrically and capable of relative movement. In a mounting groove formed continuously in the circumferential direction, a seal ring slidably disposed on the other peripheral surface, and a back ring interposed between the seal ring and the bottom surface of the mounting groove A pressure introducing groove extending between a region facing the mounting groove side surface and outside the facing region on the end surface of the seal ring, and extending in a circumferential direction within the facing region and communicating with the pressure introducing groove. The pressure receiving groove to be formed is formed.

  In the above configuration, when one end surface in the axial direction of the seal ring is in close contact with one side surface in the axial direction of the mounting groove, the fluid pressure from one axial direction of the seal ring acts as a back pressure on the seal ring. When the fluid pressure is higher than the other fluid pressure in the axial direction, the fluid pressure on the high-pressure side is outside the region facing the side surface of the mounting groove on the end surface, in other words, on the surface exposed in the gap between the inner peripheral member and the outer peripheral member. In addition, the pressure ring is introduced into the pressure receiving groove extending in the circumferential direction in the facing region through the pressure introducing groove extending from the surface into the facing region with the side surface of the mounting groove. The pressure receiving area of the fluid pressure on the high pressure side that acts as a thrust to move toward the other side surface in the axial direction is large, and the seal ring moves smoothly. For this reason, the fluid pressure on the high pressure side is quickly introduced into the mounting groove, and due to the fluid pressure, the radial expansion force generated in the buckling also increases the closeness of the seal ring, resulting in excellent sealing performance. Is secured.

  According to the sealing device of the present invention, the seal ring moves smoothly according to the reversible change in the pressure relation on both sides in the axial direction, and the radial expansion force of the buckling due to the fluid pressure is reliably obtained. Leakage can be effectively prevented.

1 is a half sectional view showing a schematic configuration of a preferred embodiment of a sealing device according to the present invention by cutting along a plane passing through an axis O. FIG. It is the front view of the seal ring in preferable embodiment of the sealing device based on this invention, a rear view, and AOB sectional drawing. FIG. 5 is a half cross-sectional view showing a state in which the seal ring and the back ring are in close contact with one side surface in the mounting groove in a preferred embodiment of the sealing device according to the present invention, cut along a plane passing through the axis O; It is explanatory drawing which shows the pressure receiving surface of the seal ring in preferable embodiment of the sealing device which concerns on this invention. FIG. 4 is a half cross-sectional view showing a state in which the seal ring and the buckling are in close contact with the side surface on the opposite side to FIG. 3 in a preferred embodiment of the sealing device according to the present invention, cut along a plane passing through the axis O; FIG. 10 is a half cross-sectional view showing a schematic configuration of a sealing device according to a conventional example by cutting along a plane passing through an axis O. FIG. 10 is a half cross-sectional view showing a state in which a seal ring and a back ring are in close contact with one side surface in a mounting groove in a sealing device according to a conventional example, cut along a plane passing through an axis O; It is explanatory drawing which shows the pressure receiving surface of the seal ring in the sealing device which concerns on a prior art example. FIG. 10 is a half cross-sectional view showing a state in which a seal ring and a back ring are in close contact with the other side surface in the mounting groove in a sealing device according to a conventional example, cut by a plane passing through an axis O.

  Hereinafter, preferred embodiments of a sealing device according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a half sectional view showing a schematic configuration of a preferred embodiment of a sealing device according to the present invention by cutting along a plane passing through an axis.

  In FIG. 1, reference numeral 3 is a cylinder, and reference numeral 4 is a piston arranged concentrically and axially movable on the inner periphery of the cylinder 3, and is continuously connected to the outer peripheral surface 4 a of the piston 4 in the circumferential direction. A mounting groove 41 is formed, and the sealing device according to the present invention is mounted in the mounting groove 41. The cylinder 3 corresponds to the outer peripheral member described in claim 1, and the piston 4 corresponds to the inner peripheral member described in claim 1.

  The sealing device according to the present invention is interposed between a seal ring 1 made of a synthetic resin having a low friction coefficient, typically PTFE (polytetrafluoroethylene), and the bottom surface 41 c of the seal ring 1 and the mounting groove 41. A buckling 2 made of a rubber-like elastic material (rubber material or synthetic resin material having rubber-like elasticity) is provided.

  The seal ring 1 has an outer peripheral surface and an inner peripheral surface that form a cylindrical surface. The inner diameter of the seal ring 1 is smaller than the outer peripheral surface 4 a of the piston 4 and larger than the bottom surface 41 c of the mounting groove 41. It is slightly larger in diameter than the outer peripheral surface 4 a and is held in the mounting groove 41 so as to be axially movable, and the outer peripheral surface is slidably in close contact with the inner peripheral surface 3 a of the cylinder 3. Pressure introducing grooves 11 and 12 and pressure receiving grooves 13 and 14 are formed on both axial end faces 1a and 1b of the seal ring 1, respectively. The pressure receiving grooves 13 and 14 extend in the circumferential direction. The pressure introducing grooves 11 and 12 extend from the pressure receiving grooves 13 and 14 in the radial direction, and the outer diameter ends reach the outer diameter of the seal ring 1. The inner peripheral surface 3a of the cylinder 3 and the outer peripheral surface 4a of the piston 4 correspond to the opposed peripheral surface described in claim 1.

  The pressure introducing grooves 11 and 12 extend between the end face 1a and 1b of the seal ring 1 between the area facing the side faces 41a and 41b of the mounting groove 41 and the area outside the facing area, and the pressure receiving grooves 13 and 14 are It is located in the opposed region, in other words, on the inner diameter side of the outer peripheral surface 4 a of the piston 4. In addition, as shown in FIG. 2, the pressure introducing grooves 11 and 12 are formed at a 180 degree symmetrical position on each pair and on phases different from each other by 90 degrees.

  The reason why the pressure introducing grooves 11 and 12 are formed on phases different from each other by 90 degrees is that when the pressure introducing grooves 11 and 12 are formed on the same phase, the pressure introducing grooves 11 and 12 are constricted to receive an expansion force. This is because stress tends to concentrate on the surface. In the example shown in the figure, the pressure introducing grooves 11 and 12 are each formed in a phase that is 90 degrees different from each other so that the pressure introducing grooves 11 and 12 are formed at positions 180 degrees symmetrical to each other.

  The back ring 2 is a so-called square ring whose cross-sectional shape is substantially rectangular or substantially square, and is held in an axially movable state in the mounting groove 41, and its outer peripheral surface is the inner peripheral surface of the seal ring 1. The inner peripheral surface is in close contact with the bottom surface 41c of the mounting groove 41 so as to be slidable.

Figure 3 shows a state where the seal ring 1 and the buckling 2 is in close contact with the side surface 41a of the left in the drawing in the mounting groove 41 by the hydraulic P ₁ from the right in the drawing. In this state, the hydraulic pressure P ₂ acting through the gap between the inner peripheral surface 3a of the cylinder 3 and the outer peripheral surface 4a of the piston 4 from the left side in the drawing is applied to the seal ring 1 and the back ring 2 from the right side in the drawing from the right side in the drawing. becomes higher than a predetermined value than the pressure P ₁ acting as a hydraulic P ₂ is a positive pressure in this case is outside from the outer peripheral surface 4a of the piston 4 out of the end surface 1a of the seal ring 1 facing to the left in FIG. It acts on the region on the radial side (outside the region facing the side surface 41 a of the mounting groove 41), and from there through the pressure introducing groove 11, the region on the inner diameter side from the outer peripheral surface 4 a of the piston 4 (the side surface 41 a of the mounting groove 41 and Are introduced into the pressure receiving grooves 13 extending in the circumferential direction.

That is, the pressure receiving surface S of the hydraulic P ₂ acting on the end surface 1a of the seal ring 1 as a thrust that moves toward the sealing ring 1 to the right side in the drawing of the side surface 41b of the mounting groove 41, denoted by the number of dots in FIG. 4 as shown Te, added the piston outer peripheral surface 4a in region S ₁ on the outer diameter side, since spanning the entire pressure-receiving groove 13 from the piston outer peripheral surface 4a in the region of the inner diameter side through the pressure introduction groove 11, the back pressure P although ₁ (the projected area in the axial direction of the seal ring 1) pressure-receiving surface is smaller than the S _3, as compared to the pressure receiving surface S _{1 +} S ₂ in the conventional structure shown in FIG. 8 increases significantly. Therefore, even if the pressure difference of the hydraulic P ₂ is a hydraulic P ₁ and the back pressure is a positive pressure reduced, the thrust P _{2 S} to move the sealing ring 1 to a low pressure side in the drawing right, drag P by back pressure ₁ S ₃ hardly becomes smaller state, thus moving the seal ring 1 can be smoothly performed.

As the seal ring 1 moves, a gap is created between the side surface 41a of the mounting groove 41 and the end surface 1a of the seal ring 1, and a positive pressure is applied between the side surface 41a of the mounting groove 41 and the back ring 2. hydraulic P ₂ is introduced rapidly, as shown in FIG. 5, buckling 2 also moves toward the inside attachment groove 41 to the right in the drawing together with the seal ring 1.

  As a result, the seal ring 1 and the back ring 2 are pressed against the side surface 41b on the right side of the mounting groove 41 in the figure, and the outer peripheral surface of the seal ring 1 by the radial expansion force generated on the back ring 2 by being pressed against the side surface 41b. Is slidably pressed against the inner peripheral surface 3 a of the cylinder 3, and the outer peripheral surface and inner peripheral surface of the back ring 2 are pressed against the inner peripheral surface of the seal ring 1 and the bottom surface 41 c of the mounting groove 41. Sex is secured.

Further, at this time, the end surface 1b of the seal ring 1 facing the right side in the drawing is only the sealing surface continuous in the circumferential direction on the inner diameter side of the pressure receiving groove 14 with respect to the side surface 41b on the right side of the mounting groove 41 in the drawing. without, since the partial area of the outer diameter side of the pressure-receiving groove 14 is closely be hydraulic P ₂ becomes high, without load is concentrated only on the sealing surface, thus deformation of the seal ring 1 It is suppressed.

Then reversed again pressure relationship from this state, the hydraulic pressure P ₁ from the right side in the figure is the same even when relatively high than hydraulic P ₂ from the left side in the figure, that is, the seal ring 1 pressure receiving area of the hydraulic P ₁ acting on the end face 1b of the seal ring 1 as a thrust that moves toward the left in the drawing in side 41a of the mounting groove 41, as shown are designated by the number of dots in FIG. 4, the piston outer periphery in addition from the surface 4a in region S ₁ on the outer diameter side, since spanning the entire pressure-receiving groove 14 from the piston outer peripheral surface 4a in the region of the inner diameter side through the pressure introduction groove 12, the hydraulic P ₁ is a positive pressure in this case Even if the pressure difference between the hydraulic pressure P ₂ and the back pressure is small, the thrust P ₁ S that moves the seal ring 1 to the left side in the drawing, which is the low pressure side, is less likely to be smaller than the drag P ₂ S ₃ caused by the back pressure. Therefore, transfer of the seal ring 1 It is carried out smoothly.

And with the movement of the seal ring 1, the hydraulic P ₁ promptly to between the side 41b and the buckling 2 of the mounting groove 41 a gap between the side surface 41b and the end face 1b of the seal ring 1 of the mounting groove 41 As shown in FIG. 3, the back ring 2 also moves in the mounting groove 41 together with the seal ring 1 toward the left side in the drawing.

  As a result, the seal ring 1 and the back ring 2 are pressed against the left side surface 41a of the mounting groove 41 in the drawing, and the outer peripheral surface of the seal ring 1 due to the radial expansion force generated in the back ring 2 by being pressed against the side surface 41a. Is slidably pressed against the inner peripheral surface 3 a of the cylinder 3, and the outer peripheral surface and inner peripheral surface of the back ring 2 are pressed against the inner peripheral surface of the seal ring 1 and the bottom surface 41 c of the mounting groove 41.

Further, at this time, the end surface 1a of the seal ring 1 facing the left side in the drawing is only the sealing surface continuous in the circumferential direction on the inner diameter side of the pressure receiving groove 13 with respect to the left side surface 41a of the mounting groove 41 in the drawing. without, since the partial area of the outer diameter side of the pressure receiving groove 13 is closely, even if the oil pressure P ₁ is pressure from the right side in the figure, without the load is concentrated only on the sealing surface, thus sealing The deformation of the ring 1 is suppressed.

Therefore, according to the sealing device of the present invention, the seal ring 1 and the buckling 2 are smoothly moved in accordance with changes in the hydraulic pressures P ₁ and P ₂ on both sides in the axial direction, and the seal ring 1 and the buckling are also smoothly moved. There is no risk that the close contact force of 2 will be insufficient and leakage will occur, and further, the seal ring 1 will be deformed by hydraulic pressure, or the seal ring to the gap between the inner peripheral surface 3a of the cylinder 3 and the outer peripheral surface 4a of the piston 4 The protrusion of No. 1 is suppressed, and an excellent sealing property is secured.

  In the illustrated embodiment, the seal ring 1 slidable with the inner peripheral surface 3a of the cylinder 3 as the outer peripheral member and the seal ring 1 in the mounting groove 41 formed in the outer peripheral surface 4a of the piston 4 as the inner peripheral member, and this seal Although the description has been given of the one provided with the back ring 2 interposed between the ring 1 and the bottom surface 41c of the mounting groove 41, on the contrary, the mounting groove formed on the inner peripheral surface of the outer peripheral member The present invention is also applicable to a device provided with a back ring interposed between the outer peripheral surface of the member and a slidable seal ring and the bottom surface of the mounting groove.

DESCRIPTION OF SYMBOLS 1 Seal ring 1a, 1b End surface 11, 12 Pressure introducing groove 13, 14 Pressure receiving groove 2 Back ring 3 Cylinder (outer peripheral member)
4 Piston (inner peripheral member)
41 Mounting groove

Claims (1)

  Sliding with the other peripheral surface in the mounting groove formed continuously in the circumferential direction on one peripheral surface of the outer peripheral member and the inner peripheral member arranged concentrically and relatively movable A seal ring that can be arranged, and a back ring that is interposed between the seal ring and the bottom surface of the mounting groove. A sealing device comprising: a pressure introducing groove extending between the outside; and a pressure receiving groove extending in a circumferential direction in the facing region and communicating with the pressure introducing groove.

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