Non-contact shaft peripheral seal device

Abstract

To provide a non-contact shaft peripheral seal device capable of suppressing or preventing breakage of a cylindrical seal member caused by axial movement of a porous member.SOLUTION: A non-contact shaft peripheral seal device includes: a connection plate 14 having an opening through which a rotary shaft can penetrate and connected to a casing 8 in a state where the rotary shaft penetrates through the opening; a cylindrical porous member 18 for supplying a pressurized gas to an outer peripheral surface of the rotary shaft at a position outside the connection plate; a cylindrical seal member 22 that is disposed radially outward of the outer peripheral surface of the rotary shaft so as to seal a space between one open end of the cylindrical porous member and a peripheral edge of the opening of the connection plate through which the rotary shaft penetrates and extends, and that follows movement of the porous member; and a tension adjustment member 32 that adjusts tension of the seal member along a longitudinal direction of the rotary shaft so that a length of the seal member along the longitudinal direction of the rotary shaft is maintained within a predetermined range.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a non-contact shaft circumferential seal device, and more particularly to a non-contact shaft circumferential seal device that seals the outer periphery of a rotating shaft in a non-contact manner by supplying pressurized gas to the outer periphery of the rotating shaft. [Background technology]

[0002] A non-contact shaft circumferential seal device is known in which a pressurized fluid is supplied through a porous member arranged radially outward from the outer circumferential surface of a rotating shaft, thereby forming a fluid film between the outer circumferential surface of the rotating shaft and the porous member.

[0003] One known example of such a non-contact circumferential shaft sealing device is one in which a porous member that supplies pressurized fluid is allowed to move within a certain range in the radial or axial direction relative to a stationary member such as a housing, and the space between such a movable porous member and the stationary housing is sealed by a tubular member (bellows) made of a flexible material (Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2015-510091 Summary of the Invention [Problem to be solved by the invention]

[0005] However, since a non-contact shaft circumferential sealing device such as that disclosed in Patent Document 1 is used in a location where a rotating shaft passes through a partition wall that separates two regions where a pressure difference exists, the pressure difference between the two regions can cause the porous member to move in the axial direction.

[0006] When the direction of this movement is the direction in which the porous member moves away from the housing, a large tension (tension in the tensile direction) acts on the cylindrical sealing member, one end of which is attached to the stationary member (housing) and the other end to the porous member, and the cylindrical sealing member (bellows) is stretched. If the amount of this stretching exceeds the allowable limit, the cylindrical sealing member may be damaged, such as torn.

[0007] On the other hand, when the moving direction is the direction in which the porous member approaches the housing, or when a higher pressure acts on the outer surface of the sealing tubular member than on the inner surface, a force (stress in the compressive direction) acts on the sealing tubular member to shrink it in the axial direction, causing the sealing tubular member to bend radially inward, i.e., in the direction of the rotation axis. If the degree of this bending becomes large, the sealing tubular member may come into contact with the rotation axis and be damaged.

[0008] The present invention has been made in consideration of these points, and aims to provide a non-contact circumferential axial sealing device that can suppress or prevent damage to a tubular sealing member caused by axial movement of a porous member. [Means for solving the problem]

[0009] According to another preferred embodiment of the present invention, A non-contact shaft circumferential seal device that is attached to a casing having a wall portion through which a rotating shaft penetrates, and that forms a non-contact fluid film between the rotating shaft and the outer circumferential surface of the rotating shaft by a pressurized gas supplied to the outer circumferential surface of the rotating shaft, a connecting plate having an opening through which the rotating shaft can pass and connected to the casing with the rotating shaft passing through the opening; a cylindrical porous member that supplies pressurized gas to an outer peripheral surface of the rotating shaft at an outer position of the connecting plate; a cylindrical seal member disposed radially outward of the outer circumferential surface of the rotating shaft so as to seal between one open end of the cylindrical porous member and the periphery of the opening of the connecting plate through which the rotating shaft extends, and which follows the movement of the porous member; and a tension adjusting member that adjusts the tension of the seal member along the longitudinal direction of the rotating shaft so that the length of the seal member along the longitudinal direction of the rotating shaft is maintained within a predetermined range. A non-contact shaft circumferential seal device, is provided.

[0010] With this configuration, the tension adjustment member adjusts the tension of the sealing member along the longitudinal direction of the rotating shaft and maintains the length of the sealing member within a predetermined range, thereby preventing or suppressing situations such as the sealing member being stretched in the axial direction and torn, or bending radially inward and coming into contact with the rotating shaft and being damaged.

[0011] According to another preferred embodiment of the present invention, The tension adjusting member is a coil spring arranged along the longitudinal axis of the rotating shaft.

[0012] According to this configuration, the expansion and contraction of the coil spring can be utilized to prevent or suppress the seal member from extending beyond an allowable range or bending radially inward.

[0013] According to another preferred embodiment of the present invention, The coil spring is connected to the other open end of the porous member.

[0014] According to this configuration, Since the coil spring is located on the outside of the aircraft, it is easy to access the coil spring for maintenance, etc.

[0015] According to another preferred embodiment of the present invention, a cylindrical holder that holds the cylindrical porous member from the radially outer side and forms a fluid supply space between the cylindrical holder and the porous member; The coil spring has one end attached to one end of the holder, thereby being connected to the porous member.

[0016] According to this configuration, The structure in which the coil spring is connected to the holder, which is easy to process, makes manufacturing and maintenance easy.

[0017] According to another preferred embodiment of the present invention, The tubular seal member has a cylindrical body and flanges disposed on opposite ends of the cylindrical body and extending radially outward.

[0018] According to this configuration, Since the cylindrical seal member can be connected to the connecting plate or the holder by utilizing the flange, the manufacturing process of the non-contact shaft circumferential seal device is simplified.

[0019] According to another preferred embodiment of the present invention, One flange of the seal member is sandwiched between the periphery of the opening of the connecting plate and a connecting plate side pressing plate, The other flange of the seal member is sandwiched between the other end of the holder and a holder-side pressing plate.

[0020] According to this configuration, The cylindrical sealing member can be attached to the non-contact shaft circumferential seal device by the simple task of clamping one flange between the connecting plate and the connecting plate side pressure plate, and the other flange between the casing holder and the holder side pressure plate, making it easy to manufacture the non-contact shaft circumferential seal device.

[0021] According to another preferred embodiment of the present invention, A plate is provided that is disposed along the rotation shaft away from the connecting plate with the porous member therebetween, and the other end of the coil spring is connected to the plate.

[0022] According to this configuration, It is possible to connect the coil spring to the porous member with a simplified structure.

[0023] According to another preferred embodiment of the present invention, The device includes a rod-shaped member having a base end fixed to the connecting plate so as to extend from the connecting plate along the rotation axis, and the rod-shaped member has a large diameter portion at its tip end against which the end of the coil spring can abut, and the coil spring is sheathed on the rod-shaped member with one end abutting against the connecting plate and the other end abutting against the large diameter portion.

[0024] According to this configuration, Since it is possible to attach the coil spring close to the casing, the length along the axis of the rotating shaft of the non-contact shaft circumferential sealing device is shortened, and as a result, the non-contact shaft circumferential sealing device can be attached to the casing even when there is not much space around the casing.

[0025] According to another preferred embodiment of the present invention, The coil spring is a compression spring.

[0026] According to this configuration, The compression spring, which serves as a tension adjustment member, suppresses excessive stretching of the tubular sealing member, and prevents or suppresses the tubular sealing member from being stretched and damaged due to movement of the porous body member.

[0027] According to another preferred embodiment of the present invention, The coil spring is a tension spring.

[0028] According to this configuration, The tension spring, which serves as a tension adjustment member, prevents excessive bending (sagging) of the tubular sealing member, and prevents or suppresses the tubular sealing member from being pressed in the axial direction by the movement of the porous body member, bending inward, and being damaged by contact with the rotating shaft.

[0029] According to another preferred embodiment of the present invention, The porous member is made of a material selected from the group consisting of porous carbon, porous ceramics, and sintered metal.

[0030] In this manner, in the present invention, the porous member for supplying pressurized gas can be made of a material selected from a plurality of types of porous materials.

[0031] According to another preferred embodiment of the present invention, the coil spring is a compression spring interposed between the other end of the holder and the connecting plate, The porous member is made of a material selected from the group consisting of porous carbon, porous ceramics, and sintered metal.

[0032] With this configuration, the compression spring prevents the distance between both ends of the cylindrical sealing member from becoming shorter than a predetermined length, thereby preventing the cylindrical sealing member from bending inward, and as a result, preventing or suppressing the cylindrical sealing member from coming into contact with the rotating shaft and being damaged.

[0033] According to another aspect of the present invention, A non-contact shaft circumferential seal device that is attached to a casing having a wall portion through which a rotating shaft penetrates, and forms a non-contact seal between the rotating shaft and an outer circumferential surface of the rotating shaft by pressurized gas supplied to the outer circumferential surface of the rotating shaft, a mounting plate having an opening through which the rotating shaft can pass and connected to the casing with the rotating shaft passing through the opening; a cylindrical porous member that supplies pressurized gas to an outer peripheral surface of the rotating shaft at an outer position of the mounting plate; a cylindrical seal member arranged radially outward of the outer circumferential surface of the rotating shaft so as to seal between one open end of the cylindrical porous member and the periphery of the opening of the mounting plate through which the rotating shaft extends, the cylindrical seal member following the movement of the porous member; a tension adjusting member that adjusts the tension of the seal member along the longitudinal direction of the rotating shaft so that the length of the seal member along the longitudinal direction of the rotating shaft is maintained within a predetermined range, One end of the seal member is sandwiched between a peripheral edge of the opening of the mounting plate and a wall portion of the casing, the other end of the seal member is sandwiched between the other end of the holder and a holder-side pressing plate; A non-contact circumferential shaft seal device is provided.

[0034] According to another aspect of the present invention, There is provided a non-contact shaft circumferential seal device set comprising any one of the non-contact shaft circumferential seal devices described above and a sleeve fitted onto the rotating shaft so as to form an outer circumferential surface of the rotating shaft.

[0035] According to this configuration, the non-contact shaft seal can be easily installed in the device, and the operation of installing the non-contact shaft seal in the device can be easily performed. Furthermore, since there is no need to adjust the gap between the outer circumferential surface of the rotating shaft formed by the sleeve and the porous member, the performance of the non-contact shaft seal can be guaranteed. Effect of the Invention

[0036] According to the present invention, it is possible to provide a non-contact circumferential axial seal device that can suppress or prevent damage to a tubular seal member caused by axial movement of a porous member. [Brief description of the drawings]

[0037] [Figure 1] 1 is a longitudinal sectional view taken along a rotation shaft of a screw feeder in a state in which a non-contact shaft circumferential sealing device according to a first embodiment of the present invention is attached to the screw feeder. [Diagram 2] 1 is a diagram showing a non-contact shaft circumferential seal device of the first embodiment attached to a rotating shaft having a modified sleeve. [Diagram 3] FIG. 11 is a longitudinal sectional view taken along a rotation shaft of a screw feeder in a state in which a non-contact shaft circumferential sealing device according to a second embodiment of the present invention is attached to the screw feeder. [Figure 4] FIG. 11 is a longitudinal sectional view taken along a rotation shaft of a screw feeder in a state in which a non-contact shaft circumferential sealing device according to a third embodiment of the present invention is attached to the screw feeder. [Diagram 5]FIG. 11 is a longitudinal sectional view taken along a rotation shaft of a non-contact shaft circumferential sealing device according to a fourth embodiment of the present invention, in a state in which the non-contact shaft circumferential sealing device is attached to a screw feeder. [Figure 6] FIG. 11 is a longitudinal sectional view taken along a rotation shaft in a state in which a non-contact shaft circumferential sealing device according to a fifth embodiment of the present invention is attached to a screw feeder. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0038] The configuration of a non-contact shaft circumferential seal device according to a first embodiment of the present invention will be described below with reference to the drawings. Fig. 1 is a vertical cross-sectional view taken along a rotation axis of a non-contact shaft circumferential seal device according to a first embodiment of the present invention attached to a screw feeder.

[0039] The non-contact shaft circumferential sealing device of this embodiment is a non-contact shaft circumferential sealing device that forms a non-contact seal between the rotating shaft and a stationary member on the casing side through which the rotating shaft extends by sealing the outer surface of the rotating shaft with pressurized gas supplied to the outer periphery of the rotating shaft. The casing is assumed to be a container that contains a fluid such as gas, liquid, fluid, flowable powder, or powdered granules. The non-contact shaft circumferential seal device of this embodiment is applied to a screw feeder, which is a device that supplies powder, but is not limited to this. Therefore, the casing of the screw feeder in which the screw is disposed is the casing through which the rotating shaft passes.

[0040] In the non-contact shaft circumferential seal device 1 of this embodiment, the rotating shaft 2 comprises a rotating shaft main body 6 that rotates the screw 4 inside the machine, and a hollow cylindrical sleeve 10 that is fitted to the machine body side portion of the rotating shaft main body 6 and forms the outer circumferential surface of the rotating shaft 2 at the portion where the rotating shaft 2 penetrates the casing 8. The sleeve 10 is made of a metal suitable for the usage conditions, such as stainless steel, chrome-plated or nickel-plated steel, and is configured not to rotate relative to the rotating shaft main body 6 due to frictional force, etc.

[0041] The non-contact shaft circumferential sealing device 1 of this embodiment is equipped with a connecting plate 14 having an opening 12 through which the rotating shaft 2 can pass. When the non-contact shaft circumferential sealing device is attached to an object device such as a screw feeder, this connecting plate 14 is connected and fixed to a casing 8 of the object device with a connector such as a screw 16, with the casing 10 of the rotating shaft 2 passing through the opening 12, as shown in Fig. 1.

[0042] The non-contact shaft circumferential seal device 1 of this embodiment further includes a cylindrical porous member 18 that is disposed radially outward of the outer circumferential surface of the rotating shaft 2 (the outer circumferential surface of the sleeve 10) at an outer position (outside the machine position) of the connecting plate 14 and supplies pressurized gas to the outer circumferential surface of the rotating shaft 2 (the outer circumferential surface of the sleeve 10). In this embodiment, the porous member 18 is made of porous carbon. However, the porous member 18 may be made of other porous materials, porous ceramics, porous sintered metal, etc.

[0043] The inner diameter of the porous member 18 is set slightly larger than the outer diameter of the sleeve 10 so that when the porous member 18 is positioned radially outward of the sleeve 10, a gap of approximately 1 to 20 μm, preferably approximately 2 to 5 μm, is formed between the inner surface of the porous member 18 and the outer surface of the sleeve 10.

[0044] A cylindrical holder 20 that supports the porous member 18 from the radially outer side is disposed at a radially outer position of the porous member 18. The holder 20 has substantially the same axial length as the porous member 18. The holder 20 is configured to be integral with the porous member 18 and to be movable in the axial and radial directions.

[0045] The holder 20 is also formed with a recess 20a extending around the entire circumference on the inner peripheral surface at the center in the axial direction, and an air supply passage 20b penetrating the holder 20 in the radial direction and communicating at its tip side with the recess 20a. The recess 20a is configured such that the open end located on the inner peripheral side is covered with the porous member 18, and pressurized gas supplied to the recess 20a through the air supply passage 20b from a gas supply source (not shown) is supplied to the entire outer peripheral surface of the porous member 18 as indicated by arrow A. In this embodiment, the pressurized gas supplied is pressurized air, but other pressurized gases, such as argon, nitrogen, etc., can also be used depending on the mode of use.

[0046] The porous member 18 is fixed to the holder 20 by shrink fitting, adhesive, etc. Furthermore, the axial end face of the porous member 18 is sealed with epoxy resin or the like.

[0047] The pressurized gas supplied to the outer peripheral surface of the porous member 18 passes through the inside of the porous member 18, is ejected from the inner peripheral surface of the porous member 18, and is supplied to the outer peripheral surface of the sleeve 10, forming a layer of pressurized gas between the porous member 18 and the sleeve 10. This layer of pressurized gas forms a fluid film between the porous member 18 and the sleeve 10, and the sleeve 10 (rotating shaft 2) is supported by the non-contact shaft circumferential seal device 1 without contacting the porous member 18, which is a stationary member on the casing side.

[0048] The non-contact shaft circumferential seal device 1 further includes a cylindrical seal member 22. The seal member 22 has a cylindrical main body 22a, and an inboard flange 22b and an outboard flange 22c that are disposed on both ends of the cylindrical main body and extend radially outward. The seal member 22 is disposed radially outward of the outer circumferential surface of the sleeve 10 (rotating shaft 2) so as to seal between the inboard open end of the cylindrical porous member 18 and the periphery of the opening 12 of the connecting plate 14 through which the sleeve 10 (rotating shaft 2) extends.

[0049] The cylindrical sealing member 22 is formed from an elastic material such as synthetic rubber, impermeable canvas, etc., and seals the space inside the non-contact sealing device 1 between the inner surface of the porous member 18 and the outer surface of the sleeve 10 (rotating shaft 2) from the extra-machine space on the radially outer side.

[0050] The tubular sealing member 22 is fixed by having the flange 22b on the inside of the machine clamped between the connecting plate 14 and a ring-shaped connecting plate side pressure plate 26 fixed to the connecting plate 14 by screws 24, and the flange 22c on the outside of the machine clamped between the holder 20 and a ring-shaped holder side pressure plate 30 fixed to the holder 20 by screws 28.

[0051] The seal member 22 is made of an elastic material, and therefore deforms in response to the axial and circumferential movements of the porous member 18 and the holder 20 that constitute the non-contact shaft circumferential seal device 1 while maintaining a sealed state.

[0052] The non-contact shaft circumferential sealing device 1 further includes a tension adjustment member that adjusts the tension of the sealing member 22 along the longitudinal direction of the rotating shaft 2 so that the length of the sealing member 22 along the longitudinal direction of the rotating shaft 2 is maintained within a predetermined range.

[0053] In this embodiment, the tension adjusting member is a coil spring 32 arranged along the axis in the longitudinal direction of the rotating shaft. The coil spring 32 is a compression spring arranged in an orientation extending along the axial direction of the rotating shaft 2 between the axially outer end of the holder 20 and an annular plate 34 arranged at a distance from the connecting plate 14 along the rotating shaft 2 with the porous member 18 therebetween.

[0054] 1 shows only one coil spring 32, it is preferable to arrange a plurality of coil springs 32 at equal angular intervals around the rotation axis 2. Note that a plurality of coil springs may be arranged at unequal angular intervals. The annular plate 34 is fixed to the connecting plate 14 by a plurality of rods 36 (only one is shown in FIG. 1) arranged at equal angular intervals around the rotation axis 2. The plurality of rods 36 may be arranged at unequal angular intervals.

[0055] The seal member 22 is biased toward the casing 8 via the holder 20 by a coil spring 32, which is a compression spring, so as to assume a desired arrangement and shape, and is in a state in which a predetermined tension is applied.

[0056] With this configuration, even if a force is generated due to pressure inside the machine that, for example, moves the holder 20 and the porous member 18 toward the outside of the machine, the coil spring 32 restricts the amount of movement of the holder 20 and the porous member 18 toward the outside of the machine. As a result, the sealing member 22 connected to the porous member 18 is prevented from being stretched due to excessive tension being applied to it by the large movement of the porous member 18, thereby preventing the sealing member 22 from being damaged.

[0057] The non-contact shaft circumferential seal device 1 of this embodiment is preferably manufactured, transported, assembled, etc., as a set with the sleeve 10. For this reason, during transportation and assembly to a target device such as a screw feeder, the sleeve 10 is connected to the annular plate 34 by a set plate 38 having an L-shaped cross section and screws 40 and 42. Once the installation work to the screw feeder (target equipment), such as fixing the connecting plate 14 to the casing 8 and sheathing the sleeve 10 on the rotating shaft body 6, is completed, the set plate 38 and the screws 40, 42 are removed, and the sleeve 10 becomes rotatable integrally with the rotating shaft body 6.

[0058] By transporting the sleeve 10 as a set fixed to the non-contact shaft sealing device 1 in this manner, it becomes easy to align the porous member 18 with the sleeve 10 when assembling the non-contact shaft sealing device 1 to the target equipment. Furthermore, since there is no need to adjust the gap between the outer circumferential surface of the rotating shaft formed by the sleeve 10 and the porous member 18, the performance of the non-contact shaft sealing device 1 is guaranteed.

[0059] As shown in FIG. 2, a non-contact circumferential seal may be formed between the outer circumferential surface of a sleeve 44 fixed to a rotary shaft body 48 by a set screw 46 .

[0060] Next, a non-contact shaft circumferential seal device 50 according to a second embodiment of the present invention will be described with reference to Fig. 3. Fig. 3 is a view similar to Fig. 1, showing the configuration of the non-contact shaft circumferential seal device 50 according to the second embodiment.

[0061] The configuration of the second non-contact shaft circumferential seal device 50 is the same as that of the non-contact shaft circumferential seal device 1 of the first embodiment. The difference between the first and second embodiments is that the non-contact shaft circumferential seal device 50 of the second embodiment does not form a non-contact shaft circumferential seal with a rotating shaft whose outer circumferential surface is formed by a sleeve, but forms a fluid film (non-contact shaft circumferential seal) with the outer circumferential surface of a rotating shaft 52 that is not exteriorly fitted with a sleeve.

[0062] Next, a non-contact shaft circumferential seal device 70 according to a third embodiment of the present invention will be described with reference to Fig. 4. The configuration of the portion forming the non-contact shaft circumferential seal of the third non-contact shaft circumferential seal device 70 is the same as that of the non-contact shaft circumferential seal device 1 of the first embodiment. The non-contact shaft circumferential seal device 70 of the third embodiment differs from the non-contact shaft circumferential seal device 1 of the first embodiment in the arrangement of the coil spring, which is a tension adjusting member.

[0063] The non-contact shaft circumferential seal device 70 of the third embodiment is provided with a rod-shaped member 72 whose base end is fixed to the pressing plate 26 on the connecting plate 14 side and which extends parallel to the rotation shaft and through the pressing plate 30 on the holder 20 side. A large diameter portion 74 is provided at the tip (outside end) of this rod-shaped member. A coil spring 76, which is a compression spring, is fitted on the rod-shaped member 72 so as to be disposed between the large diameter portion 74 and the pressing plate 30 on the holder side.

[0064] With this configuration, even if a force acts to move the holder and porous member toward the inside of the machine, the coil spring 74 restricts the amount of movement of the holder 20 and porous member 18 toward the inside of the machine, and as a result, the main body portion 22a of the sealing member 22 connected to the porous member 18 and the holder 20 is prevented from bending radially inward and coming into contact with the outer peripheral surface of the rotating shaft (sleeve) and being damaged. In addition, the axial length is shortened, making the device more compact.

[0065] Next, a non-contact shaft circumferential sealing device 80 according to a fourth embodiment of the present invention will be described with reference to Fig. 5. The basic configuration of the fourth non-contact shaft circumferential sealing device 80 is the same as that of the non-contact shaft circumferential sealing device 70 according to the third embodiment. A non-contact shaft circumferential seal device 80 of the fourth embodiment differs from the non-contact shaft circumferential seal device 70 of the third embodiment in the location of the coil spring, which is a tension adjusting member.

[0066] As shown in FIG. 5, in the non-contact shaft circumferential seal device 70 of the fourth embodiment, a coil spring 82, which is a compression spring, is interposed between the pressure plate 26 on the connecting plate 14 side and the pressure plate 30 on the holder 20 side.

[0067] With this configuration, even if a force acts to move the holder and porous member toward the inside of the machine, the coil spring 82 restricts the amount of movement of the holder and porous member toward the inside of the machine, and as a result, the main body of the sealing member connected to the porous member is prevented from bending radially inward and coming into contact with the outer peripheral surface of the rotating shaft (sleeve), which would cause damage.

[0068] Next, a non-contact shaft circumferential seal device 90 according to a fifth embodiment of the present invention will be described with reference to Fig. 6. Fig. 6 is a view similar to Fig. 1, showing the configuration of the non-contact shaft circumferential seal device 90 according to the fifth embodiment.

[0069] The non-contact shaft circumferential seal device 1 of the first embodiment differs from the non-contact shaft circumferential seal device 90 of the fifth embodiment in the presence or absence of a connecting plate 14.

[0070] The non-contact shaft circumferential sealing device 70 of the fifth embodiment does not have a connecting plate 14, and the casing side pressure plate (mounting plate) 26' that holds one end of the sealing member is integrated with the connecting plate 14 of the non-contact shaft circumferential sealing device 1 of the first embodiment.

[0071] 6, the interior flange 22b of the cylindrical seal member 22 is sandwiched between the casing side pressure plate 26' and the casing 8. Furthermore, the casing side pressure plate 26' of the non-contact shaft circumferential seal 70 of this embodiment is fixed to the casing 8 by the rod 36 which is screwed into the casing 8.

[0072] Such a non-contact shaft circumferential seal 70 has an inexpensive and lightweight structure because it does not require a connecting plate.

[0073] The present invention is not limited to the above-described embodiment, and various changes and modifications are possible within the scope of the technical idea described in the claims.

[0074] In each of the above embodiments, a seal member having a cylindrical main body and flanges on both ends of the main body is used as the seal member, but a seal member having another shape, such as a bellows shape, may also be used.

[0075] In the above embodiment, a coil spring is used as the tension adjusting member, but other types of springs such as leaf springs, and further other elastic members may be used. [Explanation of symbols]

[0076] 1: Non-contact shaft seal device 2: Rotation axis 4: Screw 6: Rotating shaft body 8: Casing 10: Sleeve 12:Aperture 14:Connection plate 18:Porous material 20: Holder 20a: Recess 20b: Air supply path 22: Sealing material 22a:Main body 22b: Inboard flange 22c: Outer flange 26: Connection plate side pressure plate 30: Holder side pressure plate 32: Coil spring 34: Annular plate 36: Rod 38: Set plate

Claims

1. A non-contact shaft circumferential seal device that is attached to a casing having a wall portion through which a rotating shaft penetrates, and forms a non-contact seal between the rotating shaft and an outer circumferential surface of the rotating shaft by pressurized gas supplied to the outer circumferential surface of the rotating shaft, a connecting plate having an opening through which the rotating shaft can pass and connected to the casing with the rotating shaft passing through the opening; a cylindrical porous member that supplies pressurized gas to an outer peripheral surface of the rotating shaft at an outer position of the connecting plate; a cylindrical seal member that is disposed radially outward of the outer circumferential surface of the rotating shaft so as to seal between one open end of the cylindrical porous member and the periphery of the opening of the connecting plate through which the rotating shaft extends, and that follows the movement of the porous member; and a tension adjusting member that adjusts the tension of the seal member along the longitudinal direction of the rotating shaft so that the length of the seal member along the longitudinal direction of the rotating shaft is maintained within a predetermined range. A non-contact shaft circumferential seal device.

2. The tension adjustment member is a coil spring arranged along an axis in the longitudinal direction of the rotating shaft. The non-contact shaft circumferential seal device according to claim 1 .

3. The coil spring is connected to the other open end of the porous member. The non-contact shaft circumferential seal device according to claim 2 .

4. a cylindrical holder that holds the cylindrical porous member from the radially outer side and forms a fluid supply space between the cylindrical holder and the porous member; The coil spring is connected to the porous member by having one end attached to one end of the holder. The non-contact shaft circumferential seal device according to claim 3.

5. The tubular seal member has a cylindrical body and flanges disposed on both ends of the cylindrical body and extending radially outward. The non-contact shaft circumferential seal device according to claim 4.

6. One flange of the seal member is sandwiched between the periphery of the opening of the connecting plate and a connecting plate side pressing plate, the other flange of the seal member is sandwiched between the other end of the holder and a holder-side pressing plate; The non-contact shaft circumferential seal device according to claim 5.

7. A plate is provided that is disposed along the rotation shaft away from the connecting plate with the porous member therebetween, and the other end of the coil spring is connected to the plate. The non-contact shaft circumferential seal device according to claim 6.

8. a rod-shaped member having a base end connected and fixed to the connecting plate so as to extend from the connecting plate along the rotation shaft, The rod-shaped member has a large diameter portion at a tip end thereof against which an end of the coil spring can abut, and the coil spring is sheathed on the rod-shaped member with one end abutting against the connecting plate and the other end abutting against the large diameter portion. The non-contact shaft circumferential seal device according to claim 4.

9. A non-contact shaft circumferential seal device that is attached to a casing having a wall portion through which a rotating shaft penetrates, and forms a non-contact seal between an outer circumferential surface of the rotating shaft and the outer circumferential surface of the rotating shaft by pressurized gas supplied to the outer circumferential surface of the rotating shaft, a mounting plate having an opening through which the rotating shaft can pass and connected to the casing with the rotating shaft passing through the opening; a cylindrical porous member that supplies pressurized gas to an outer peripheral surface of the rotating shaft at an outer position of the mounting plate; a cylindrical seal member arranged radially outward of the outer circumferential surface of the rotating shaft so as to seal between one open end of the cylindrical porous member and the periphery of the opening of the mounting plate through which the rotating shaft extends, the cylindrical seal member following the movement of the porous member; a tension adjusting member that adjusts the tension of the seal member along the longitudinal direction of the rotating shaft so that the length of the seal member along the longitudinal direction of the rotating shaft is maintained within a predetermined range, One end of the seal member is sandwiched between a peripheral edge of the opening of the mounting plate and a wall portion of the casing, the other end of the seal member is sandwiched between the other end of the holder and a holder-side pressing plate; A non-contact shaft circumferential seal device.

10. A non-contact shaft circumferential seal device set comprising: the non-contact shaft circumferential seal device according to any one of claims 1 to 9; and a sleeve that is fitted onto a rotating shaft so as to form an outer circumferential surface of the rotating shaft.

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