JP2005114007A - Sealing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the generation of damage in a back-up ring 4 installed in a sealing device in advance, due to floating thereof from an installation groove 21 when inserting a piston 2 into a housing 1. <P>SOLUTION: The sealing device has an O-ring 3 made of a rubbe-like elastic material and the back-up ring 4 made of a material harder than that of the O-ring 3 and cut at one position in the circumferential direction in the installation groove 21 formed in any one of the inner peripheral surface 1a of the housing 1 and the outer peripheral surface 2a of the piston 2 arranged in the inner periphery of the housing freely to move in the axial direction and continued in the circumferential direction. A groove inside surface 21a, to which the O-ring 3 is pushed when inserting the piston 2 into the housing 1, is formed into a tapered surface by narrowing groove width on a groove shoulder 21c side, and a back surface 4c on the opposite side in relation to the O-ring 3 in the back-up ring 4 as a side, to which the O-ring 3 is pushed when inserting the piston 2 into the housing 1, is formed into a shape corresponding to the groove inside surface 21a. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a sealing device that seals a reciprocating portion of a device that generates a high pressure, such as a hydraulic device for an automobile or industrial equipment.

A typical prior art of a sealing device that seals between a housing on the outer peripheral side and a piston on the inner peripheral side in a hydraulic device or the like is described in Patent Document 1 below.
Japanese Patent Laid-Open No. 9-72310 (FIG. 6)

  FIG. 9 is a cross-sectional view of a mounting state in which a conventional sealing device of the same type as that disclosed in Patent Document 1 is cut along a plane passing through an axis, and reference numeral 101 in the drawing is a housing of a hydraulic device. , 102 are pistons arranged on the inner periphery of the housing 101 so as to be movable in the axial direction. A mounting groove 102a having a rectangular cross section continuous in the circumferential direction is formed on the outer peripheral surface of the piston 102. The mounting groove 102a includes an O-ring 103 and a pair of backup rings 104 positioned on both sides in the axial direction. , 105 are installed.

  The O-ring 103 is made of a rubber-like elastic material and is formed into an annular shape having a circular cross section, and is interposed between the groove bottom surface of the mounting groove 102 a and the inner peripheral surface 101 a of the housing 101 in an appropriately compressed state. As the hydraulic pressure on both sides in the axial direction of the piston 102 is alternately pressurized, the piston 102 slides in close contact with the inner peripheral surface 101a of the housing 101 along with the reciprocating motion in the axial direction of the piston 102. The hydraulic oil is sealed. The backup rings 104 and 105 are made of a synthetic resin material such as PTFE (tetrafluoroethylene) which is harder than the O-ring 103 and has a low friction coefficient. The O-ring 103 protrudes into the gap between the outer peripheral surface 102b of the piston 102 and the inner peripheral surface 101a of the housing 101 due to the pressure of the hydraulic oil facing the inner peripheral surface 101a of the housing 101. It is to prevent.

  Since the O-ring 103 is made of a rubber-like elastic material, when mounting, the O-ring 103 is stretched to a larger diameter than the outer peripheral surface 102b of the piston 102, and then fitted into the mounting groove 102a. On the other hand, the backup rings 104 and 105 are made of a hard synthetic resin material having poor elasticity. Therefore, by cutting one place in the circumferential direction (bias cut or spiral cut), the backup rings 104 and 105 are more than the outer peripheral surface 102b of the piston 102. It can be opened to a large diameter, and the mounting property to the mounting groove 102a is ensured.

  FIG. 10 is a cross-sectional view showing the behavior of the backup ring 104 in the conventional sealing device when the piston 102 is inserted into the inner periphery of the housing 101 by cutting along a plane passing through its axis. As shown in FIG. 10, when the piston 102 is incorporated into the inner periphery of the housing 101, the O-ring 103 and the backup rings 104 and 105 are mounted in the mounting groove 102 a of the piston 102 in advance. Further, the end portion of the inner peripheral surface 101a of the housing 101 is a tapered surface 101b that opens outward in the axial direction. From the viewpoint of insertability, the piston 102 is inserted and assembled from the tapered surface 101b side.

  However, according to the conventional technique, when the O-ring 103 in the mounting groove 102a is compressed while being guided by the tapered surface 101b of the housing 101 in the process of inserting the piston 102, the stress is shown in FIG. As shown, the non-inserted portion 103a of the O-ring 103 into the inner peripheral surface 101a of the housing 101 is pressed against the backup ring 104 on the opposite side (axially outer side) to the insertion direction and deforms so as to swell toward the outer peripheral side. For this reason, there is a possibility that the backup ring 104 pressed against the O-ring 103 floats up from the mounting groove 102a and is pinched between the axially outer groove shoulder 102c and the tapered surface 101b to be damaged. For this reason, it is necessary to pay close attention to the insertion work of the piston 102, and the workability is deteriorated.

  The present invention has been made in view of the above problems, and the technical problem thereof is a backup ring that is mounted in a mounting groove in advance when an inner peripheral member such as a piston is inserted into an outer peripheral member such as a housing. Is to effectively prevent the surface from being lifted and damaged.

  As means for effectively solving the technical problem described above, the sealing device according to the invention of claim 1 includes an inner peripheral surface of the outer peripheral member and an outer periphery of the inner peripheral member arranged axially movable on the inner periphery. A packing groove made of rubber-like elastic material and a backup ring made of a material harder than this packing and cut in one circumferential direction in a mounting groove formed on one of the surfaces and continuously in the circumferential direction. And at least a groove inner surface on a side to which the packing is pressed when the inner circumferential member is inserted into the outer circumferential member is formed in a shape that narrows the groove width on the groove shoulder side. The back surface of the backup ring on the side to which the packing is pressed when the inner peripheral member is inserted into the outer peripheral member has a shape corresponding to the inner surface of the groove. .

  According to the sealing device of the first aspect of the invention, when the inner peripheral member is inserted into the inner periphery of the outer peripheral member, the backup ring mounted in advance in the mounting groove is pushed up by the packing and is about to float up. Also, due to the fitting force between the inner surface of the groove formed so that the groove width of the mounting groove is narrowed on the shoulder side of the groove and the back surface of the backup ring in contact with the groove, the backup ring is lifted from the mounting groove or is caused by this The occurrence of damage can be prevented.

  A preferred embodiment in which a sealing device according to the present invention is applied as a sealing means between a housing of a hydraulic device and a piston will be described below with reference to the drawings. 1 is a cross-sectional view of a mounted state in which the first embodiment is cut by a plane passing through an axis, FIG. 2 is a perspective view of the backup ring 4 or 5 in FIG. 1, and FIG. It is sectional drawing which shows the process inserted in the inner periphery of 1 by cut | disconnecting with the plane which passes along an axial center.

  First, in FIG. 1, reference numeral 1 is a housing of a hydraulic device, and 2 is a piston disposed on the inner periphery of the housing 1 so as to be axially movable. A mounting groove 21 continuous in the circumferential direction is formed on the outer peripheral surface of the piston 2, and the O-ring 3 and a pair of backup rings 4, 5 positioned on both sides in the axial direction are formed in the mounting groove 21. It is installed. The housing 1 corresponds to the outer peripheral member described in claim 1, the piston 2 corresponds to the inner peripheral member described in claim 1, and the O-ring 3 is described in claim 1. This is equivalent to packing.

  A tapered surface 1b that opens outward in the axial direction is formed at one axial end of the inner peripheral surface 1a having a simple cylindrical surface shape in the housing 1. On the other hand, the mounting groove 21 has a tapered surface in which the groove inner side surfaces 21a and 21b on both sides in the axial direction narrow the groove width toward the groove shoulders 21c and 21d, in other words, the groove width increases toward the groove bottom surface 21e side. It is formed in a tapered surface shape. That is, the mounting groove 21 has a dovetail cross-sectional shape.

  The O-ring 3 is made of a rubber-like elastic material and is formed into an annular shape having a circular cross section, and has an appropriate crushing allowance for the inner peripheral surface 1a of the housing 1 and the groove bottom surface 21e of the mounting groove 21, in other words, The cross-sectional diameter of the O-ring 3 in the mounted state is larger than the radial distance between the inner peripheral surface 1a of the housing 1 and the groove bottom surface 21e of the mounting groove 21, and accordingly, the inner peripheral surface 1a of the housing 1 and the mounting groove 21 It mounts | wears with the state compressed appropriately in the radial direction between the groove bottom surfaces 21e.

  On the other hand, the backup rings 4 and 5 are made of a synthetic resin material such as PTFE (tetrafluoroethylene) which is harder than the rubber-like elastic material of the O-ring 3 and has a low friction coefficient. It has a diameter larger than that of the outer peripheral surface 2a and opposes the inner peripheral surface 1a of the housing 1 with a small gap, and a part of the O-ring 3 is hydraulically separated from the outer peripheral surface 2a of the piston 2 and the inner peripheral surface 1a of the housing 1. It prevents it from protruding into the gap between the two.

  Inner side surfaces 4b and 5b facing the O-ring 3 side of the backup rings 4 and 5 are formed in a plane substantially perpendicular to the axial center, and are opposite to the O-ring 3, that is, groove inner side surfaces 21a and 21b. The back surfaces 4c and 5c facing the side have a tapered surface shape corresponding to the groove inner surfaces 21a and 21b. As shown in FIG. 2, the backup rings 4 and 5 are cut at one place in the circumferential direction, and the cut portion 4d (5d) is so-called bias cut, that is, with respect to a plane passing through the axis. By making an appropriate inclination angle, the O-ring 3 is prevented from biting into the cut portion 4d (5d).

  In the hydraulic apparatus having the above-described configuration, the hydraulic pressure is alternately introduced into the space on both sides in the axial direction of the piston 2 so that the piston 2 reciprocates in the axial direction on the inner periphery of the housing 1 or the piston 2 moves to the housing 1. By forcibly reciprocating in the axial direction on the inner circumference, high pressure is alternately generated in the space on both sides in the axial direction. This hydraulic pressure also acts on the O-ring 3 via the backup ring 4 or 5 from the gap between the inner peripheral surface 1a of the housing 1 and the outer peripheral surface 2a of the piston 2, for example, the hydraulic pressure in the right space in FIG. Rises, the O-ring 3 is pressed against and supported by the inner side surface 4 b of the backup ring 4, and when the hydraulic pressure in the left space in FIG. 1 rises, the O-ring 3 moves to the inner side surface 5 b of the backup ring 5. Pressed and supported.

  More specifically, for example, when the hydraulic pressure in the right space in FIG. 1 rises, the O-ring 3 moves to the relatively low pressure side (left side in FIG. 1) in the mounting groove 21 by this hydraulic pressure, and the backup ring 4. Therefore, the pressure on the inner peripheral surface 1a of the housing 1 and the groove bottom surface 21e of the mounting groove 21 is increased. On the other hand, for example, when the oil pressure in the left space in FIG. 1 increases, the O-ring 3 moves to the relatively low pressure side (right side in FIG. 1) in the mounting groove 21 by this oil pressure, and the backup ring 5. Since the inner surface 5b of the housing 1 is deformed, the surface pressure on the inner peripheral surface 1a of the housing 1 and the groove bottom surface 21e of the mounting groove 21 increases. For this reason, the seal surface pressure changes according to the introduction pressure, and an excellent sealing function is achieved.

  Further, since the outer peripheral edges 4a and 5a of the backup rings 4 and 5 are larger in diameter than the outer peripheral surface 2a of the piston 2 and face the inner peripheral surface 1a of the housing 1 with a minute gap, the O A part of the ring 3 is effectively prevented from protruding into the gap between the outer peripheral surface 2 a of the piston 2 and the inner peripheral surface 1 a of the housing 1.

  Here, the method of inserting the piston 2 into the inner periphery of the housing 1 in the state shown in FIG. 1 will be described. When this assembly is performed, the O-ring 3 and the backup ring 4, 4 are first inserted in the mounting groove 21 of the piston 2 in advance. Wear 5 Since the O-ring 3 is made of a rubber-like elastic material, when the O-ring 3 is mounted, the O-ring 3 is stretched to a larger diameter than the outer peripheral surface 2a of the piston 2 and then fitted into the mounting groove 21 by its restoring force (reducing diameter). It ’s fine. On the other hand, the backup rings 4 and 5 are made of a hard synthetic resin material, but have a cut portion 4d (5d) in one circumferential direction, so that they have a larger diameter than the outer peripheral surface 2a of the piston 2. From the above, it can be elastically fitted into the mounting groove 21.

  Further, the piston 2 in which the O-ring 3 and the backup rings 4 and 5 are mounted in the mounting groove 21 is inserted from the left side in the drawing in which the tapered surface 1b is formed on the inner periphery of the housing 1, as shown in FIG. And incorporate.

  In this insertion process, as shown in FIG. 3, the outer periphery of the O-ring 3 in the mounting groove 21 is in contact with the tapered surface 1b of the housing 1, so that the frictional resistance causes the O-ring 3 to move inside the mounting groove 21. It is relatively moved in the direction opposite to the insertion direction and pressed against the inner side surface 4 b of the backup ring 4. Further, since the O-ring 3 is subjected to radial compression as it is inserted toward the small diameter side of the tapered surface 1b, the portion 3a facing the large diameter side of the tapered surface 1b swells to the outer peripheral side due to the stress. This is pressed against the inner surface 4 b of the backup ring 4, and therefore, a displacement force is given to the backup ring 4 to lift from the mounting groove 21 to the outer peripheral side.

  However, the groove inner surface 21a formed in a tapered surface shape that narrows the groove width of the mounting groove 21 on the groove shoulder 21c side and the back surface 4c of the backup ring 4 formed in a corresponding tapered surface shape are fitted. Due to the resultant force, the backup ring 4 is prevented from being lifted from the mounting groove 21. This is because a part of the pressing load acting between the groove inner side surface 21a and the back surface 4c of the backup ring 4 acts in the direction of displacing the backup ring 4 to the inner peripheral side due to the shape characteristic due to the tapered surface. This is because the displacement force in the uplift direction generated by the deformation of is canceled out.

  Therefore, it is possible to effectively prevent the outer peripheral edge 4a of the backup ring 4 from interfering with the tapered surface 1b of the housing 1 and being caught between the groove shoulder 21c and being damaged. For this reason, the assembling work of the piston 2 can be easily performed.

  Next, FIG. 4 is a cross-sectional view of a mounting state in which the second embodiment of the sealing device according to the present invention is cut along a plane passing through the axis. In this embodiment, the backup ring 4 is disposed only on one side in the axial direction of the O-ring 3. Specifically, the piston 2 is inserted into the mounting groove 21 when the piston 2 is assembled into the housing 1. The backup ring 4 is disposed only at a position opposite to the direction.

  The mounting groove 21 formed on the outer peripheral surface 2a of the piston 2 has a tapered surface shape in which the groove inner surface 21a opposite to the direction in which the piston 2 is inserted into the housing 1 narrows the groove width toward the groove shoulder 21c. For example, the groove bottom surface 21e side is formed in a tapered surface shape so as to widen the groove width, and the other groove inner side surface 21b is formed in a planar shape substantially perpendicular to the axis. Further, the backup ring 4 is the same as that shown in FIG. 1 described above (first embodiment), that is, the outer peripheral edge 4a is larger in diameter than the outer peripheral surface 2a of the piston 2, The inner surface 4b facing the peripheral surface 1a with a minute gap and facing the O-ring 3 side has a planar shape substantially perpendicular to the axis, and is opposite to the O-ring 3, that is, the groove inner surface 21a side. The back surface 4c facing the surface has a tapered surface shape corresponding to the groove inner surface 21a.

  The configuration of the other parts is basically the same as that of the first embodiment shown in FIG. 1 described above.

  In the hydraulic apparatus having the above-described configuration, high hydraulic pressure is introduced or generated only in the space on the right side in FIG. 4. For this reason, the backup ring 4 is located on the opposite side of the mounting groove 21 from the high-pressure space. The O-ring 3 is supported by (on the left side in FIG. 4), and a part thereof is effectively prevented from protruding into the gap between the outer peripheral surface 2 a of the piston 2 and the inner peripheral surface 1 a of the housing 1.

  The mounting method of the O-ring 3 and the backup ring 4 in the mounting groove 21 is the same as described above, and the piston 2 is tapered on the inner periphery of the housing 1 after the O-ring 3 and the backup ring 4 are mounted. The surface 1b is inserted and incorporated from the left side in the figure. Further, the floating of the backup ring 4 during the insertion process is suppressed by the fitting force between the groove inner side surface 21a formed in a tapered surface and the back surface 4c of the backup ring 4 as in the first embodiment. It is possible to effectively prevent the outer peripheral edge 4a of the ring 4 from being caught between the tapered surface 1b of the housing 1 and the groove shoulder 21c and being damaged. For this reason, the assembling work of the piston 2 can be easily performed.

  Next, FIG. 5 is a cross-sectional view of a mounting state in which a third embodiment of the sealing device according to the present invention is cut along a plane passing through the axis. In this embodiment, the mounting groove 21 formed on the outer peripheral surface 2a of the piston 2 is tapered such that the groove inner side surface 21a opposite to the insertion direction of the piston 2 into the housing 1 narrows the groove width toward the groove shoulder 21c side. It is formed in a planar shape, in other words, a tapered surface shape that widens the groove width toward the groove bottom surface 21e side, and the other groove inner side surface 21b is formed in a planar shape substantially perpendicular to the axis.

  The O-ring 3 and backup rings 4 and 5 disposed on both sides in the axial direction are mounted in the mounting groove 21. Of the backup rings 4 and 5, one backup ring 4 is the same as that shown in FIG. 1 described above (first embodiment), that is, the outer peripheral edge 4 a is more than the outer peripheral surface 2 a of the piston 2. The inner surface 4b, which has a large diameter, opposes the inner peripheral surface 1a of the housing 1 with a minute gap and faces the O-ring 3 side, has a planar shape substantially perpendicular to the axis, and is opposite to the O-ring 3 The back surface 4c facing the side, that is, the groove inner surface 21a side, has a tapered surface shape corresponding to the groove inner surface 21a. Further, the other backup ring 5 has an outer peripheral edge 5a having a larger diameter than the outer peripheral surface 2a of the piston 2 and is opposed to the inner peripheral surface 1a of the housing 1 with a minute gap and faces the O-ring 3 side. 5b and the back surface 5c facing the groove inner side surface 21b side on the opposite side form a plane substantially perpendicular to the axis.

  The configuration of the other parts is basically the same as that of the first embodiment shown in FIG. 1 described above.

  In the hydraulic apparatus having the above-described configuration, the piston 2 reciprocates along the inner periphery of the housing 1 in the axial direction by alternately introducing hydraulic pressure into the space on both sides in the axial direction of the piston 2 as in the first embodiment. Alternatively, when the piston 2 is forcibly reciprocated in the axial direction along the inner periphery of the housing 1, high pressure is alternately generated in the spaces on both sides in the axial direction. When the hydraulic pressure in the right space in the figure rises, the O-ring 3 is supported by the inner side surface 4b of the backup ring 4, and when the hydraulic pressure in the left space in the figure rises, the O-ring 3 becomes the backup ring 5 The O-ring 3 is effectively supported by the backup rings 4 and 5 so that the O-ring 3 protrudes into the gap between the outer peripheral surface 2a of the piston 2 and the inner peripheral surface 1a of the housing 1. To prevent.

  The mounting method of the O-ring 3 and the backup rings 4 and 5 in the mounting groove 21 is the same as described in the first embodiment, and the piston 2 is mounted after the O-ring 3 and the backup rings 4 and 5 are mounted. The housing 1 is assembled by being inserted from the left side in the drawing in which the tapered surface 1b is formed. Further, the floating of the backup ring 4 during the insertion process is suppressed by the fitting force between the groove inner side surface 21a formed in a tapered surface and the back surface 4c of the backup ring 4 as in the first embodiment. It is possible to effectively prevent the outer peripheral edge 4a of the ring 4 from being caught between the tapered surface 1b of the housing 1 and the groove shoulder 21c and being damaged. For this reason, the assembling work of the piston 2 can be easily performed.

  Next, FIG. 6 is a cross-sectional view showing a fourth embodiment of the sealing device according to the present invention cut by a plane passing through the axis, and FIG. 7 is a perspective view of the backup ring 6 or 7 in FIG. FIG. 8 is a cross-sectional view showing the process of incorporating the piston 2 into the inner periphery of the housing 1 by cutting along a plane passing through its axis in this embodiment. In the first to third embodiments described above, the O-ring 3 and the backup ring 4 (and 5) are all mounted in the mounting groove 21 formed on the outer peripheral surface 2a of the piston 2, whereas this fourth mode. 6, the O-ring 3 and the backup rings 6 and 7 are mounted in a mounting groove 11 formed on the inner peripheral surface 1 a of the housing 1, as shown in FIG. 6.

  The mounting groove 11 formed on the inner peripheral surface 1a of the housing 1 has a tapered surface shape in which the groove inner side surfaces 11a and 11b on both sides in the axial direction narrow the groove width toward the groove shoulders 11c and 11d, in other words, the groove bottom surface 11e. It is formed in a tapered surface shape that widens the groove width toward the side. That is, the mounting groove 11 has a dovetail cross-sectional shape.

  On the other hand, at one axial end of the outer peripheral surface 2a of the piston 2, a tapered surface 2b having a small diameter toward the tip is formed.

  Similar to the first to third embodiments, the O-ring 3 is formed of a rubber-like elastic material into a circular shape with a circular cross section, and is formed with respect to the outer peripheral surface 2a of the piston 2 and the groove bottom surface 11e of the mounting groove 11. In other words, the cross-sectional diameter of the O-ring 3 in a non-mounted state is larger than the radial distance between the outer peripheral surface 2 a of the piston 2 and the groove bottom surface 11 e of the mounting groove 11. The outer peripheral surface 2a and the groove bottom surface 11e of the mounting groove 11 are mounted in a state of being appropriately compressed in the radial direction.

  The backup rings 6 and 7 are made of a synthetic resin material such as PTFE (tetrafluoroethylene) which is harder than the rubber-like elastic material of the O-ring 3 and has a low friction coefficient, and the inner peripheral edges 6 a and 7 a are formed from the inner diameter of the housing 1. Also, the O-ring 3 protrudes into the gap between the outer peripheral surface 2a of the piston 2 and the inner peripheral surface 1a of the housing 1 by hydraulic pressure. It is to prevent.

  Inner side surfaces 6b and 7b facing the O-ring 3 side of the backup rings 6 and 7 are formed in a planar shape substantially perpendicular to the axis, and are opposite to the O-ring 3, that is, groove inner side surfaces 11a and 11b. The back surfaces 6c and 7c facing the side have a tapered surface shape corresponding to the groove inner surfaces 11a and 11b. Further, as shown in FIG. 7, the backup rings 6 and 7 are cut at one place in the circumferential direction, and the cut portions 6d and 7d are so-called bias cut, that is, with respect to a plane passing through the axis. By making an appropriate inclination angle, the O-ring 3 is prevented from biting into the cut portion 6d (7d).

  In the hydraulic apparatus having the above-described configuration, the hydraulic pressure is alternately introduced into the space on both sides in the axial direction of the piston 2 so that the piston 2 reciprocates in the axial direction on the inner periphery of the housing 1 or the piston 2 moves to the housing 1. By forcibly reciprocating in the axial direction on the inner circumference, high pressure is alternately generated in the space on both sides in the axial direction. This hydraulic pressure also acts on the O-ring 3 through the backup ring 6 or 7 from the gap between the inner peripheral surface 1a of the housing 1 and the outer peripheral surface 2a of the piston 2, for example, the hydraulic pressure in the right space in FIG. In this case, the O-ring 3 is pressed against and supported by the inner side surface 6 b of the backup ring 6. When the hydraulic pressure in the left space in FIG. 6 increases, the O-ring 3 is pressed against the inner side surface 7 b of the backup ring 7. Supported.

  Specifically, for example, when the hydraulic pressure in the right space in FIG. 6 increases, the O-ring 3 moves to the relatively low pressure side (left side in FIG. 6) in the mounting groove 11 by this hydraulic pressure, and the backup ring 6 Since the inner surface 6b is pressed and deformed, the surface pressure against the outer peripheral surface 2a of the piston 2 and the groove bottom surface 11e of the mounting groove 11 is increased. On the other hand, for example, when the oil pressure in the left space in FIG. 6 increases, the O-ring 3 moves to the relatively low pressure side (right side in FIG. 6) in the mounting groove 11 by this oil pressure, and the backup ring 7. Since the inner surface 7b is pressed and deformed, the surface pressure against the outer peripheral surface 2a of the piston 2 and the groove bottom surface 11e of the mounting groove 11 is increased. For this reason, the seal surface pressure changes according to the introduction pressure, and an excellent sealing function is achieved.

  Further, the inner peripheral edges 6a, 7a of the backup rings 6, 7 are smaller in diameter than the inner peripheral face 1a of the housing 1 and face the outer peripheral face 2a of the piston 2 with a minute gap, so that the O-ring deformed by hydraulic pressure. 3 is effectively prevented from protruding into the gap between the outer peripheral surface 2 a of the piston 2 and the inner peripheral surface 1 a of the housing 1.

  Here, the method of inserting the piston 2 into the inner periphery of the housing 1 in the state shown in FIG. 6 will be described. In this assembly, the O-ring 3 and the backup ring 6 are first inserted in the mounting groove 11 on the housing 1 side in advance. , 7. Since the O-ring 3 is made of a rubber-like elastic material, the O-ring 3 can be easily fitted into the mounting groove 11 from the inner periphery of the housing 1 by deformation. On the other hand, the backup rings 6 and 7 are made of a hard synthetic resin material. However, since one place in the circumferential direction is divided, the backup rings 6 and 7 are deformed to a smaller diameter than the inner peripheral surface 1a of the housing 1. It can be elastically fitted into the mounting groove 11.

  Next, the piston 2 is inserted into the inner periphery of the housing 1 with the end having the tapered surface 2b as the head. In this insertion process, as shown in FIG. 8, the inner periphery of the O-ring 3 in the mounting groove 11 contacts the tapered surface 2 b of the piston 2, so that the frictional resistance causes the O-ring 3 to move through the mounting groove 11. And is pressed against the inner side surface 7 b of the backup ring 7. Further, since the O-ring 3 rides relatively to the large diameter side of the tapered surface 2b during the insertion process of the piston 2 and undergoes radial compression, a portion facing the small diameter side of the tapered surface 2b by the stress. 3b is pressed against the inner side surface 7b of the backup ring 7 while expanding toward the inner peripheral side. For this reason, a displacement force is given to the backup ring 7 so as to float from the mounting groove 11 to the inner peripheral side. .

  However, the groove inner surface 11b formed in a tapered surface shape that narrows the groove width of the mounting groove 11 on the groove shoulder 11d side and the back surface 7c of the backup ring 7 formed in a tapered surface corresponding thereto are fitted. Due to the resultant force, the floating of the backup ring 7 from the mounting groove 11 is suppressed. This is because part of the pressing load acting between the groove inner surface 11a and the back surface 7c of the backup ring 7 acts in the direction of displacing the backup ring 7 to the outer peripheral side due to the shape characteristic of the tapered surface. This is because the lifting force to the inner peripheral side generated by the deformation is offset.

  Therefore, it is possible to effectively prevent the inner peripheral edge 7a of the backup ring 7 from interfering with the tapered surface 2b of the piston 2 and being caught between the groove shoulder 11d and being damaged. For this reason, the assembling work of the piston 2 can be easily performed.

  As in the fourth embodiment, the O-ring 3 and the backup rings 6 and 7 are mounted in the mounting groove 11 formed on the inner peripheral surface 1a of the housing 1, and the second or third described above. Only the groove inner surface 11b on the side to which the O-ring 3 is pressed when the piston 2 is inserted and the back surface 7c of the backup ring 7 may be formed in the same manner as in FIG.

  Further, in each of the above-described embodiments, the inner surface of the mounting groove and the back surface of the backup ring in contact with the mounting groove are tapered surfaces that narrow the groove width on the groove shoulder side. The inner surface of the mounting groove is formed in a stepped surface that narrows the groove width on the shoulder side of the groove, and the back surface of the backup ring is formed in a corresponding cross-sectional shape. Even if it exists, it is possible to effectively prevent the backup ring from floating from the mounting groove.

  Further, the present invention can be similarly applied to packing other than the O-ring 3 as shown in the figure, for example, one using an X ring, a square ring, or the like.

It is sectional drawing of the mounting state which cut | disconnects and shows the 1st form of the sealing device which concerns on this invention by the plane which passes along an axial center. It is a perspective view of the backup ring 4 or 5 in FIG. It is sectional drawing which shows the process which inserts the piston 2 in the inner periphery of the housing 1, cut | disconnected by the plane which passes along the axial center. It is sectional drawing of the mounting state which cut | disconnects and shows the 2nd form of the sealing device which concerns on this invention by the plane which passes along an axial center. It is sectional drawing of the mounting state which cut | disconnects and shows the 3rd form of the sealing device which concerns on this invention by the plane which passes along an axial center. It is sectional drawing of the mounting state which cut | disconnects and shows the 4th form of the sealing device which concerns on this invention by the plane which passes along an axial center. It is a perspective view of the backup ring 6 or 7 in FIG. It is sectional drawing which shows the process which inserts the piston 2 in the inner periphery of the housing 1, cut | disconnected by the plane which passes along the axial center. It is sectional drawing of the mounting state which shows the conventional sealing device cut | disconnected and shown by the plane which passes along an axial center. It is sectional drawing which shows the behavior of the backup ring 104 in the conventional sealing device at the time of inserting the piston 102 in the inner periphery of the housing 101, cut | disconnected by the plane which passes along the axial center.

Explanation of symbols

1 Housing (peripheral member)
1a Inner peripheral surfaces 11, 21 Mounting grooves 11a, 11b, 21a, 21b Groove inner side surfaces 11c, 11d, 21c, 21d Groove shoulders 11e, 21e Groove bottom surface 2 Piston (inner peripheral member)
2a Outer peripheral surface 3 O-ring (packing)
4, 5, 6, 7 Backup ring 4a, 5a Outer peripheral edge 4b, 5b, 6b, 7b Inner side face 4c, 5c, 6c, 7c Rear face 6a, 7a Inner peripheral edge

Claims (1)

It is formed on either one of the inner peripheral surface (1a) of the outer peripheral member (1) and the outer peripheral surface (2a) of the inner peripheral member (2) arranged on the inner periphery so as to be movable in the axial direction, and is continuous in the circumferential direction. In the mounting grooves (21, 11), a packing (3) made of a rubber-like elastic material and a backup ring (4, 5, 5) made of a material harder than the packing (3) and cut in one circumferential direction. 6 and 7), and the packing (3) is pressed when the inner peripheral member (2) is inserted into at least the outer peripheral member (1) among the inner surfaces of the mounting grooves (21, 11). Groove inner side surfaces (21a, 11b) are formed in a shape narrowing the groove width on the groove shoulder (21c, 11d) side, and packing (3) is inserted when the inner peripheral member (2) is inserted into the outer peripheral member (1). ) Of the backup ring (4, 7) on the side to be pressed, Serial packing (3) and the opposite back (4c, 7c) is sealed and wherein the forming a shape corresponding to the groove side (21a, 11b).

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