Shaft sealing device

Abstract

Provided is a shaft sealing device having high followability of a case with respect to a rotary shaft.　This shaft sealing device 1 comprises: a pipe 2 into which a rotary shaft 3 is inserted; a case 4 having an elastic part 40 having elasticity through which the rotary shaft 3 is inserted; a rubber hose 7 externally fitted to the case 4; a fastening member 8 for fastening the rubber hose 7 to the case 4; and sealing means 5, 6 for sealing a space between the rotary shaft 3 and the case 4. The case 4 is arranged axially outside an axial end part of the pipe 2, and a rigid member 41 having hardness higher than that of the elastic part 40 is installed on an inner diameter side of the fastening member 8 and axially outside the axial end part of the pipe 2.

Description

Shaft sealing device

[0001] The present invention relates to a shaft sealing device, and more particularly to a shaft sealing device for sealing a rotating shaft inserted into a pipe.

[0002] As shaft sealing devices for preventing leakage of sealed fluids around the rotating shaft of a rotary machine, for example, a mechanical seal consisting of a pair of annular sliding parts that rotate relative to each other and whose sliding surfaces slide against each other, or a seal ring that rotates and slides relative to the sliding surface of the rotating shaft or case, is known.

[0003] For example, Patent Document 1 discloses a shaft seal device used in a ship's propulsion system, which is mainly composed of a seal ring, a seal casing, a mating ring, a rubber tube, and multiple bands. The seal ring is attached to a propeller shaft inserted into a stern tube. The seal casing is fitted onto the propeller shaft. The mating ring is fixed to the seal casing and is slidable relative to the seal ring. The rubber tube is fitted over the seal casing and stern tube, and is fastened by a band to the seal casing and stern tube.

[0004] The seal casing is able to follow the propeller shaft due to elastic deformation of the rubber tube, even if the propeller shaft becomes eccentric or tilts due to engine vibration, water resistance, etc. This makes it easier for the shaft seal device shown in Patent Document 1 to maintain a sliding state between the seal casing and the mating ring.

[0005] JP 2005-214293 A (pages 6 and 7, Figure 1)

[0006] In a shaft seal device such as that described in Patent Document 1, the inner surface of the seal casing is brought into sliding contact with the propeller shaft, allowing the seal casing to follow the eccentricity and tilting of the propeller shaft. Therefore, it was necessary to satisfy the sliding properties of the propeller shaft and seal casing while also suppressing deterioration such as wear.

[0007] The present invention has been made in view of these problems, and has as its object to provide a shaft seal device in which the case has high followability to the rotating shaft.

[0008] To solve the above problem, the present invention provides a shaft seal device comprising: a tube through which a rotating shaft is inserted; a case having an elastic portion through which the rotating shaft is inserted; a rubber hose connecting the tube and the case; a fastening member for fastening the rubber hose to the case; and sealing means for sealing the gap between the case and the rotating shaft, wherein at least a portion of the case is disposed axially outward from the axial end of the tube; and a rigid member having a harderness than the elastic portion is disposed radially inward from the fastening member and axially outward from the axial end of the tube. This allows the force of the fastening member for securing the rubber hose to act on the rigid member, making the case less likely to deform toward the rotating shaft and ensuring a gap between the case and the rotating shaft. This allows the case to be made of an elastic material, improving the case's ability to conform to the rotating shaft.

[0009] The rigid member may be an endless tube, which can prevent the force of the fastening member from being applied to the elastic member.

[0010] The rigid member may be provided on the outer periphery of the elastic portion of the case, which makes it easier to assemble the rigid member to the elastic member.

[0011] The rigid member may be bonded to the outer periphery of the elastic portion of the case, thereby preventing the elastic member from slipping out of the rigid member.

[0012] The elastic portion of the case may comprise a hose attachment portion that overlaps the rubber hose in the radial direction and a seal portion where the sealing means is provided, and the rigid member may extend axially along the hose attachment portion, thereby allowing the seal portion to swing relative to the hose attachment portion without deformation of the hose attachment portion.

[0013] The case may be in axial contact with the pipe, thereby improving the ability of the case to follow the rotating shaft and shortening the axial dimension of the shaft sealing device.

[0014] It is a cross-sectional view of the shaft sealing device in Example 1 according to the present invention. It is a view of the main part of the shaft sealing device as seen from the axial direction. It is a view of the main part of the shaft sealing device in Example 2 according to the present invention as seen from the axial direction. It is a perspective view of the main part of the shaft sealing device in Example 2.

[0015] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A shaft sealing device according to an embodiment of the present invention will be described below with reference to the accompanying drawings.

[0016] A shaft sealing device according to a first embodiment will be described with reference to Figures 1 and 2. In the following description, the left side of the paper in Figure 1 will be referred to as the left side, and the right side of the paper will be referred to as the right side.

[0017] As shown in Figure 1, the shaft seal device 1 is a water-lubricated stern tube shaft seal applied to the inboard side of a propulsion device in a ship. The shaft seal device 1 seals a rotating shaft 3 that passes through a stern tube 2, preventing cooling water in the stern tube (sealed fluid side space S2) from leaking into the leakage side space S1 on the inboard side. The shaft seal device 1 is not limited to ships, and may be applied to rotating machinery such as automobiles and general industrial machinery. The cooling fluid is not limited to cooling water such as fresh water or seawater, but may also be oil, or may be changed as appropriate.

[0018] A propeller for propulsion is attached to the outboard end of the rotating shaft 3, i.e., the left axial end (not shown), and a stern tube bearing (not shown) that supports the rotating shaft 3 is disposed near the propeller.

[0019] The shaft seal device 1 is mainly composed of a case 4, a mating ring 5, a seal ring 6, a rubber hose 7, and a plurality of hose bands 8 as fastening members. The sealing means of this embodiment is composed of the mating ring 5 and the seal ring 6.

[0020] 1 and 2, the case 4 is configured in a flanged cylindrical shape with a through hole 4a formed therethrough in the axial direction, and is configured from a base material 40 as an elastic portion and a tubular member 41 as a rigid member. In Fig. 2, the tubular member 41 is given a dot pattern for easy identification.

[0021] The substrate 40 is made of isoprene rubber with a hardness of 95 (Shore A hardness) and is integrally formed into a flanged cylindrical shape including a hose attachment portion 42 extending in the axial direction and a seal portion 43 extending from the right axial end of the hose attachment portion 42 toward the outer diameter. Because the substrate 40 is made of isoprene rubber with a hardness of 95 (Shore A hardness), it has good processing precision. The substrate 40 is not limited to being made of isoprene rubber and may be made of any elastically deformable material, and may be changed as appropriate, but it is preferable that the substrate 40 has a higher hardness than the rubber hose 7.

[0022] The through hole 4 a is formed in the base material 40 , and the axis of the through hole 4 a is substantially aligned with the axis of the hose attachment portion 42 and the seal portion 43 .

[0023] The hose attachment portion 42 is formed in a cylindrical shape, and its outer peripheral surface 42a is substantially flush and extends in both the circumferential and axial directions. The hose attachment portion 42 is fitted into the tubular member 41, and the outer peripheral surface 42a of the hose attachment portion 42 and the inner peripheral surface 41a of the tubular member 41 are bonded together.

[0024] The cylindrical member 41 is made of stainless steel and is formed into a cylindrical shape. However, the cylindrical member 41 is not limited to being made of stainless steel, and may be made of other metals or resins as long as they are harder than the base material 40 and are not easily elastically deformed when fastened with the hose band 8 described below, and may be changed as appropriate.

[0025] The axial dimension of the tubular member 41 is substantially the same as the axial dimension of the hose attachment portion 42. That is, the tubular member 41 extends across the axial direction of the hose attachment portion 42.

[0026] The right axial end face of the cylindrical member 41 abuts against the left axial end face of a wall portion 43 a (described later) of the seal portion 43. The left axial end face of the cylindrical member 41 is substantially flush with the left axial end face 42 b of the hose attachment portion 42.

[0027] Returning to the description of the hose mounting portion 42, five equally spaced water passage grooves 44 extending in the axial direction are provided on the inner diameter side of the hose mounting portion 42 (see FIG. 2). The water passage grooves 44 are recessed from the inner circumferential surface 45a of the hose mounting portion 42 toward the outer diameter side and are open toward the inner diameter side. The water passage grooves 44 also penetrate the hose mounting portion 42 in the axial direction. The number and arrangement of the water passage grooves 44 may be changed as appropriate.

[0028] Between adjacent water passage grooves 44 in the circumferential direction, there is a radially thick convex portion 45 having an inner circumferential surface 45a. The inner diameter D1 of the inner circumferential surface 45a is formed to be larger by a factor of millimeters than the diameter D2 of the rotating shaft 3. The inner circumferential surface 45a is the portion of the case 4 with the smallest inner diameter.

[0029] As a result, when the case 4 is fitted onto the rotary shaft 3 and connected to the stern tube 2, the inner peripheral surface 45a is spaced apart from the rotary shaft 3 all around, forming a gap S3 therebetween. Note that the gap S3 is exaggerated in Figures 1 and 2 for ease of identification.

[0030] The protrusion 45 extends continuously from the left side to the right side in the axial direction, and its right end 45b in the axial direction protrudes further to the right in the axial direction than the wall 43a of the seal portion 43 (see FIG. 1).

[0031] The seal portion 43 has a disk-shaped wall portion 43a extending radially outward from the right axial end of the hose attachment portion 42, and a cylindrical portion 43b extending axially rightward from the outer diameter end of the wall portion 43a, and is formed in a stepped cylindrical shape with a larger diameter than the hose attachment portion 42. A socket 46 is fixed to a mounting hole 43c that penetrates the cylindrical portion 43b in the radial direction. A connector C (see FIG. 1) of a pipe (not shown) that supplies cooling water as the sealed fluid is connected to the socket 46.

[0032] 2 shows a configuration in which two sets of mounting holes 43c and sockets 46 are equally spaced, but this is not limiting and the number and arrangement may be changed as appropriate. Furthermore, the mounting holes may also penetrate the wall portion 43a in the axial direction. In other words, it is sufficient if cooling water can be introduced into the space S2.

[0033] 1, the mating ring 5 is an annular stainless steel plate that is fitted onto the rotating shaft 3. The inner diameter side end portion on the left axial end face is a sliding surface 5a on which sliding surfaces 60a, 61a of the seal ring 6 slide. Note that the mating ring 5 is not limited to being made of stainless steel.

[0034] The mating ring 5 is attached to the case 4 by inserting the male threaded portion of a bolt B, which is inserted through a washer W, into multiple equally spaced axial through holes 50 at the outer diameter end and multiple equally spaced axial through holes 47 in the seal portion 43 of the case 4, and screwing in double nuts N1 and N2.

[0035] In addition, an O-ring P is placed between the case 4 and the mating ring 5 in an annular groove 48 recessed axially to the left of the axial right end face of the seal portion 43 in the case 4, thereby preventing the cooling water introduced through the socket 46 from leaking into the inside of the ship.

[0036] A seal ring 6 is disposed on the inner diameter side of the seal portion 43. The seal ring 6 is fastened to the rotary shaft 3 by a garter spring 9 fitted thereon.

[0037] The seal ring 6 is made of nitrile rubber and is formed in an annular shape. The seal ring 6 is provided with a thin lip 60 that curves and extends obliquely toward the outer diameter direction, and a support leg 61 that is thicker than the lip 60 and located on the outer diameter side of the lip 60. The right end surface in the axial direction of the lip 60 is a sliding surface 60a, and the right end surface in the axial direction of the support leg 61 is a sliding surface 61a. Note that the seal ring 6 is not limited to being made of nitrile rubber.

[0038] In the assembled state of the shaft seal device 1 with the double nuts N1, N2 threaded together, the left axial end 6a of the seal ring 6 abuts against the right axial end 45b of the convex portion 45 of the case 4, and the sliding surfaces 60a, 61a of the seal ring 6 abut against the sliding surface 5a of the mating ring 5 so as to be relatively slidable. Note that in the assembled state of the shaft seal device 1, the left axial end 6a of the seal ring 6 and the right axial end 45b of the convex portion 45 of the case 4 may be slightly spaced apart.

[0039] The rubber hose 7 is made of chloroprene rubber having a hardness of 60 (Shore A hardness) and is formed in a cylindrical shape. In other words, it is made of rubber having a hardness lower than that of the base material 40.

[0040] The rubber hose 7 is fitted over the right end of the stern tube 2 in the axial direction and a cylindrical member 41 in the case 4, and a hose band 8 fitted over the rubber hose 7 is fastened to connect the stern tube 2 and the case 4. In other words, the hose attachment portion 42 in the case 4 overlaps the rubber hose 7 in the radial direction. In this embodiment, two hose bands 8 are used on each of the stern tube 2 side and the case 4 side, but the number and arrangement of the hose bands 8 may be changed as appropriate.

[0041] A tubular member 41 is disposed radially inward of the hose band 8 on the case 4 side. Because the tubular member 41 has an endless cylindrical shape, it is possible to prevent the force of the hose band 8 that secures the rubber hose 7 from being applied to the base material 40. This makes it possible to stably ensure the gap S3. Note that, compared to a structure that uses a rigid member that is not endless cylindrical, as in Example 2 described below, it is possible to more reliably ensure the gap S3.

[0042] Furthermore, when the stern tube 2 and the case 4 are connected by the rubber hose 7, the axial left end face 42b of the hose attachment portion 42 and the axial right end face 2a of the axial right end of the stern tube 2 are arranged opposite to each other in the axial direction and abut against each other, i.e., are arranged in a butted relationship. In other words, the case 4 and the cylindrical member 41 are arranged axially outward of the axial right end of the stern tube 2.

[0043] The rubber hose 7 is also pressed against the tubular member 41 by being fastened by the hose band 8. This provides a seal between the tubular member 41 and the rubber hose 7, and between the stern tube 2 and the rubber hose 7.

[0044] Next, the sealing function of the shaft seal device 1 will be described.

[0045] First, we will explain the normal state when the rotating shaft 3 is not eccentric or tilted. Referring to Figure 1, cooling water delivered by a pump (not shown) is introduced into the through-hole 4a in the case 4 through the connector C and socket 46, and is then discharged outside the ship through the gap S3 and the water passage groove 44. This cools the rotating shaft 3, the stern tube bearing (not shown), the mating ring 5, and the seal ring 6, while lubricating their sliding surfaces.

[0046] In addition, a portion of the cooling water passes through a communication groove 61 b ​​that penetrates the support leg 61 of the seal ring 6 in the radial direction, and flows in and out of an annular groove 62 formed by the lip 60 and the support leg 61 .

[0047] The lip 60 is pressed toward the mating ring 5 by the pressure of the cooling water in the annular groove 62, so that the sliding surface 60a of the lip 60 and the sliding surface 5a of the mating ring 5 are kept in close contact with each other.

[0048] Under normal circumstances, a gap S3 is formed between the rotating shaft 3 and the case 4 in the circumferential direction, so that the rotating shaft 3 is in a non-contact state with the inner peripheral surface 45a of the case 4 over the entire circumference. This makes the case 4 less susceptible to deterioration due to sliding heat generation and wear.

[0049] In addition, the case 4 is connected to the stern tube 2 via a rubber hose 7, which makes it difficult for vibrations from the stern tube 2 to be transmitted. This prevents the case 4 from moving significantly in the radial direction relative to the rotating shaft 3 due to vibrations from the stern tube 2.

[0050] Additionally, the left axial end face 42b of the rubber base material 40 abuts against the right axial end face 2a of the stern tube 2. This prevents the cooling water or contaminants from entering between the rubber hose 7 and the stern tube 2, or between the rubber hose 7 and the tubular member 41, when the cooling water flows into the stern tube 2 through the through-hole 4a and the water passage groove 44, and thus prevents unintended force from being generated in the rubber hose 7.

[0051] When the rotating shaft 3 is slightly eccentric or tilted relative to the axis of the case 4 due to vibration, wear of the stern tube bearing, etc., the gap S3 makes it difficult for the rotating shaft 3 to come into contact with the inner peripheral surface 45a of the case 4.

[0052] The sliding surface 60a of the seal ring 6 has a radial area that is equal to or larger than the gap S3 where it can be in sliding contact with the sliding surface 5a of the mating ring 5. This ensures that the sliding surface 60a of the lip 60 and the sliding surface 5a of the mating ring 5 remain in close contact with each other even if the rotating shaft 3 is eccentric within the gap S3.

[0053] Furthermore, when the rotating shaft 3 moves relative to the case 4 in the axial left direction, the axial left end 6a of the seal ring 6 abuts against the axial right end 45b of the convex portion 45 on the case 4, thereby preventing the seal ring 6 from moving excessively in the axial left direction, thereby maintaining a tight contact between the sliding surface 60a of the lip 60 and the sliding surface 5a of the mating ring 5.

[0054] Furthermore, when the rotating shaft 3 moves relative to the case 4 toward the right in the axial direction, the highly rigid support leg 61 mainly receives the force, and the lip 60 of the seal ring 6 is prone to deform toward the annular groove 62, so that the sliding surface 60a of the lip 60 and the sliding surface 5a of the mating ring 5 can be maintained in close contact with each other.

[0055] Furthermore, when the rotary shaft 3 tilts, a portion of the seal ring 6 is pressed against the axial right end 45b, and the other portion of the seal ring 6 located radially and axially opposite is pressed against the sliding surface 5a. In response, the wall portion 43a of the seal portion 43 mainly elastically deforms, causing the mating ring 5 to follow the tilting of the seal ring 6 and maintaining a tight contact state.

[0056] More specifically, the hose mounting portion 42 onto which the tubular material 41 is fitted is less likely to deform in shape, such as bending or curving its own axis, and therefore the case 4 is more likely to elastically deform around the wall portion 43a in the seal portion 43 extending radially outward from the hose mounting portion 42 as a base point.

[0057] In addition, since the highly rigid cylindrical material 41 abuts against the wall portion 43a, the case 4 is more likely to elastically deform with the cylindrical material 41 as the base point. Furthermore, since the rubber hose 7 is made of rubber that is less hard than the base material 40, it is possible to allow elastic deformation of the wall portion 43a.

[0058] On the other hand, the hose attachment portion 42 has the endless cylindrical member 41 that extends continuously in the axial direction of the hose attachment portion 42 fitted thereon, which facilitates elastic deformation of the seal portion 43. This is more pronounced compared to a structure in which the rigid member is divided in the circumferential direction as in Example 2 described below, a structure in which the rigid member is divided in the axial direction, or a structure in which the rigid member does not extend continuously in the axial direction of the hose attachment portion.

[0059] The rubber hose 7 is also prevented from deforming in such a way that the axis of the portion into which the stern tube 2 or the tubular member 41 is fitted is bent or curved. Furthermore, when a strong force acts on the rubber hose 7 from the base point between the axial left end face 42b and the axial right end face 2a, the tubular portion 43b can be tilted slightly relative to the stern tube 2, making it less likely to break.

[0060] Furthermore, if the rotating shaft 3 becomes eccentric or tilts to the extent that it comes into contact with the inner surface 45a of the case 4, the convex portion 45 having the contacting inner surface 45a will elastically deform in response to the eccentricity or tilt of the rotating shaft 3, making both the hose attachment portion 42 and the rotating shaft 3 less likely to be damaged.

[0061] Furthermore, each of the protrusions 45 has a convex shape formed on either side of the water passage groove 44, and therefore is easily elastically deformed in the circumferential direction, which makes it easier for each of the protrusions 45 to absorb the impact when the rotating shaft 3 comes into contact with it.

[0062] In addition, the load acting on the case 4 due to the tilting of the rotating shaft 3 or the transmission of the rotational force of the rotating shaft 3 is buffered by the base material 40, which is made of an integral rubber, making both the case 4 and the rotating shaft 3 less likely to break.

[0063] Furthermore, because the hose attachment portion 42 is bonded to the cylindrical member 41, even if a rotational force of the contacting rotary shaft 3 acts on the hose attachment portion 42, the entire hose attachment portion 42 is prevented from being twisted relative to the cylindrical member 41, and the substrate 40 is prevented from rotating in the circumferential direction relative to the cylindrical member 41. This makes it difficult for the substrate 40 to slip out of the cylindrical member 41.

[0064] Furthermore, even if the rotating shaft 3 comes into contact with the inner peripheral surface 45a of the hose attachment portion 42, the cooling water can pass through the water passage groove 44. This allows the hose attachment portion 42 and the rotating shaft 3 to be cooled.

[0065] As described above, the shaft seal device 1 of this embodiment uses a case 4 made of an elastic material to improve its ability to follow the rotating shaft 3, while still ensuring a sufficient gap S3 between the case 4 and the rotating shaft 3.

[0066] The shaft seal device 1 of this embodiment can be manufactured easily because the gap S3 can be secured. For example, compared to the configuration disclosed in Patent Document 1, which requires the gap between the inner peripheral surface of the seal casing and the propeller shaft to be adjusted in micron units, this can be manufactured very easily.

[0067] Furthermore, since the axial left end surface 42b of the base material 40 abuts against the axial right end surface 2a of the stern tube 2, the axial length of the shaft seal device 1 can be shortened.

[0068] In addition, since the axial left end surface 42b of the base material 40 abuts against the axial right end surface 2a of the stern tube 2, the case 4 is prevented from tilting relative to the axis of the stern tube 2 due to its own weight.

[0069] Furthermore, the shaft seal device 1 of this embodiment is easy to assemble because the tubular member 41 is provided on the outer periphery of the hose attachment portion 42. For example, assembly is easier than with a configuration in which a rigid member is provided on the inner periphery of the hose attachment portion or a configuration in which a rigid member is embedded in the hose attachment portion by molding or the like.

[0070] In addition, in the shaft seal device 1 of this embodiment, the cylindrical member 41 is provided on the outer periphery of the hose attachment portion 42, so even if the rotating shaft 3 comes into contact due to eccentricity or vibration, the two are less likely to be damaged.

[0071] Furthermore, in the shaft seal device 1 of this embodiment, the tubular material 41 is provided on the outer periphery of the hose attachment portion 42, so compared to a configuration in which a rigid member is embedded in the hose attachment portion by molding or the like, the outer diameter of the hose attachment portion 42 can be made smaller while ensuring the radial thickness of the convex portion 45.

[0072] The rigid member may be provided on the inner periphery of the hose attachment portion, or may be embedded in the hose attachment portion by molding or the like. Even with these configurations, a gap with the rotating shaft is maintained, and the sealing portion and rubber hose can elastically deform, thereby improving the case's ability to follow eccentricity and tilting of the rotating shaft.

[0073] The method of fixing the rigid member and the elastic portion may be changed as appropriate, such as embedding the rigid member in the hose attachment portion by molding, press-fitting the hose attachment portion into the tubular material, or fitting the tubular material and the hose attachment portion together with a concave-convex fit.

[0074] Next, a shaft seal device according to a second embodiment will be described with reference to Figures 3 and 4. Note that the description of the same configuration as in the first embodiment will be omitted.

[0075] The case 104 of the second embodiment is composed of a base material 40 and six plates 141 as rigid members. The plates 141 are arc-shaped and extend in the axial direction. The six plates 141 are equally spaced apart and spaced apart from one another in the circumferential direction. The plates 141 are also bonded to the outer peripheral surface 42 a of the hose attachment portion 42.

[0076] The six plates 141 can prevent the hose attachment portion 42 from being excessively elastically deformed when the rubber hose 7 is fastened with the hose band 8. In this way, the shape and arrangement of the rigid members may be changed as appropriate as long as they can prevent the elastic deformation of the hose attachment portion 42.

[0077] For example, the rigid member may be divided in the axial direction, i.e., may comprise a plurality of tubular rigid members that are short in the axial direction, or may be divided in both the circumferential direction and the axial direction, or the direction of division may be changed as appropriate. Furthermore, the axial dimension of the rigid member may be shorter than the axial dimension of the hose attachment portion, and the rigid member may be disposed only on the inner diameter side of the hose band 8.

[0078] Furthermore, if the structure is such that the rigid member is divided circumferentially, as in the plate material 141 of this embodiment, high precision is not required to fit the hose mounting portion 42 into the tubular material 41 without any gaps, as in the first embodiment, and therefore assembly is easy.

[0079] Furthermore, as in this embodiment, if the rigid member is divided in the circumferential direction, each rigid member may be bonded to the inner or outer peripheral surface of the rubber hose, or may be embedded in the rubber hose by molding or the like. Even in such a configuration, the rubber hose can be connected to the case by fastening it with a fastening member, while preventing excessive elastic deformation of the hose attachment portion of the elastic portion of the case. In this way, the case does not need to include a rigid member.

[0080] Although the embodiments of the present invention have been described above with reference to the drawings, the specific configuration is not limited to these embodiments, and the present invention also includes modifications and additions that do not deviate from the gist of the present invention.

[0081] For example, in the above-mentioned Examples 1 and 2, the sealing means was described as being configured as a mating ring and a seal ring, but this is not limited to this, and the structure may also be such that the seal ring fixed to the case slides against the rotating shaft to provide a seal, and the sealing means may be changed as appropriate.

[0082] In addition, in the above-described first and second embodiments, the seal ring is described as being separate from the case, but this is not limited to this. The case may also serve as the seal ring, for example, a part of the case may be a lip that slides against the rotating shaft.

[0083] In addition, in the first and second embodiments, the minimum inner diameter of the hose attachment portion is described as being larger than the diameter of the rotating shaft by a factor of millimeters, but this is not limited to this, and the diameter may be larger by a factor of centimeters or may be changed as appropriate.

[0084] In addition, in the first and second embodiments, the case and the stern tube are described as being in contact with each other in the axial direction, but this is not limiting and they may be spaced apart in the axial direction. With this configuration, the shape of the rubber hose can be greatly deformed from the point between the case and the stern tube.

[0085] REFERENCE SIGNS LIST 1 Shaft sealing device 2 Stern tube (tube) 3 Rotating shaft 4 Case 4a Through hole 5 Mating ring (sealing means) 6 Seal ring (sealing means) 7 Rubber hose 8 Hose band (tightening member) 40 Base material (elastic portion) 41 Cylindrical material (rigid member) 42 Hose attachment portion 43 Seal portion 45a Inner peripheral surface 104 Case 141 Plate material (rigid member) S1 Space on leakage side S2 Space on sealed fluid side S3 Gap

Claims

1. A shaft seal device comprising: a tube through which a rotating shaft is inserted; a case having an elastic part with elasticity through which the rotating shaft is inserted; a rubber hose connecting the tube and the case; a fastening member for fastening the rubber hose to the case; and a sealing means for sealing between the case and the rotating shaft, wherein at least a portion of the case is positioned axially outward from the axial end of the tube, and a rigid member having a harderness than the elastic part is disposed on the inner diameter side of the fastening member and axially outward from the axial end of the tube.

2. A shaft seal device as set forth in claim 1, wherein said rigid member is an endless cylinder.

3. A shaft seal device as set forth in claim 1, wherein said rigid member is provided on the outer periphery of said elastic portion of said case.

4. A shaft seal device as set forth in claim 3, wherein said rigid member is bonded to the outer periphery of said elastic portion of said case.

5. A shaft seal device as described in any one of claims 1 to 4, wherein the elastic portion of the case comprises a hose mounting portion which overlaps radially with the rubber hose and a seal portion in which the sealing means is provided, and the rigid member extends axially into the hose mounting portion.

6. A shaft seal device as set forth in claim 1, wherein said case abuts against said pipe in the axial direction.

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