JP6895357B2 - Sealing device - Google Patents

Description

The present invention relates to a sealing device that seals a gap between a peripheral surface of a shaft hole of a housing and a movable shaft inserted into the shaft hole.

In a device in which a movable shaft is assembled in a shaft hole of a housing, a lip seal is known as one of a sealing devices for sealing a gap between the peripheral surface of the shaft hole of the housing and the movable shaft inserted in the shaft hole. There is. This lip seal is fixed to the housing, and the tip of the lip abuts on the movable shaft and slides to seal the gap between the peripheral surface of the shaft hole of the housing and the movable shaft.

In order to ensure the sealability of the lip seal, it is necessary for the tip of the lip to apply a constant pressure to the surface of the movable shaft. Therefore, usually, the lip seal is made of an elastic material such as rubber, by the reaction force and the like deflection of the lip seal occurring when inserting the movable shaft in the Li Tsu Pushiru, sealing is ensured.

By the way, it is necessary to increase the press-fitting allowance when inserting (press-fitting) the movable shaft into the lip seal in order to ensure the sealing performance against the eccentricity (shaft runout) of the movable shaft inserted into the shaft hole of the housing. .. However, if the press-fitting allowance is increased, the amount of bending of the lip seal is increased, so that an excessive load is applied to the lip seal. As a result, there arises a problem that the tip of the lip is worn and the durability of the lip seal is lowered. In particular, when a resin having strong chemical resistance (for example, a fluorine-based resin) is used as the material of the lip seal, the resin is generally inferior in elasticity to rubber. Therefore, when the press-fitting allowance is increased, the durability of the lip seal is increased. The decrease becomes more remarkable.

Therefore, in order to improve the followability of the movable shaft to the eccentricity, for example, Patent Document 1 discloses a sealing device in which a bellows is provided between the lip seal and the attachment portion of the lip seal on the housing side.

As shown in FIG. 8, the sealing device disclosed in Patent Document 1 includes a lip seal 110 in which the lip tip portion contacts the outer periphery of the movable shaft 140, and a mounting portion 160 fitted to the inner peripheral surface of the housing 150. A bellows 120 is provided between the two. As a result, the bellows 120 flexibly expands and contracts following the eccentricity of the movable shaft 140, so that the sealing property can be maintained.

Japanese Unexamined Patent Publication No. 2006-177400

However, in the sealing device disclosed in Patent Document 1, in order to apply a constant pressure to the surface of the movable shaft to the tip of the lip, the bellows is compressed in a direction perpendicular to the axial direction of the movable shaft. Therefore, it is necessary to attach the sealing device to the housing.

Therefore, when the movable shaft is eccentric, the bellows on the eccentric side increases the degree of compression, so that a pressure higher than the set pressure is applied to the tip of the lip. As a result, there arises a problem that the friction at the tip of the lip increases at the site and the durability of the lip seal decreases.

On the other hand, since the bellows on the opposite side to the eccentric side has a reduced degree of compression, a pressure below the set pressure is applied to the tip of the lip. As a result, the sealing property of the lip seal is lowered at the site, and there arises a problem that the fluid in the device leaks to the outside.

Further, since the peaks and valleys of the bellows are formed along the direction perpendicular to the axial direction of the movable shaft, there is a gap between the peripheral surface of the shaft hole of the housing and the movable shaft inserted into the shaft hole. , Need to be large enough to accommodate the bellows. Therefore, the diameter of the shaft hole of the housing becomes large, which leads to an increase in the size of the housing.

The present invention has been made in view of the above problems, and a main object thereof is an eccentricity of a movable shaft in a sealing device for sealing a gap between a peripheral surface of a shaft hole of a housing and a movable shaft inserted into the shaft hole. It is an object of the present invention to provide a sealing device having high followability to a lip seal portion and suppressing deterioration of durability and sealing property of the lip seal portion.

The sealing device according to the present invention is a sealing device that seals the gap between the peripheral surface of the shaft hole of the housing and the movable shaft inserted into the shaft hole, and is a lip seal having a tip portion that abuts on the surface of the movable shaft. A bellows portion and a bellows provided at both ends of the lip seal portion, each having at least one or more annular peaks and / or valleys along the axial direction of the movable shaft. The and / or valley portion is characterized in that the movable shaft is separated from the surface of the movable shaft in a state where the movable shaft is inserted into the shaft hole.

According to the present invention, in a sealing device that seals the gap between the peripheral surface of the shaft hole of the housing and the movable shaft inserted into the shaft hole, the movable shaft has high followability to the eccentricity and the lip seal portion is durable. It is possible to provide a sealing device that suppresses deterioration of property and sealing property.

It is sectional drawing which shows typically the structure of the sealing apparatus in one Embodiment of this invention. FIG. 5 is a cross-sectional view schematically showing a state in which the sealing device shown in FIG. 1 is mounted in a housing of an apparatus. It is sectional drawing which showed the state when the axis of the movable shaft was eccentric by the distance L. (A) and (b) are conceptual diagrams explaining the reason why the bellows bends when the movable shaft is eccentric. It is sectional drawing which shows typically the structure of the sealing device in another embodiment of this invention. (A) is a cross-sectional view schematically showing a state in which the sealing device shown in FIG. 5 is mounted in the housing of the device, and (b) is a cross-sectional view when the axis of the movable shaft is eccentric by a distance L. It is sectional drawing which showed the state. (A) to (c) are cross-sectional views schematically showing the configuration of the sealing device in the modified example of this embodiment. It is sectional drawing which showed the structure of the sealing device provided with the conventional bellows.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following embodiments. In addition, changes can be made as appropriate without departing from the range in which the effects of the present invention are exhibited.

FIG. 1 is a cross-sectional view schematically showing the configuration of a sealing device according to an embodiment of the present invention. The sealing device in the present embodiment seals the gap between the peripheral surface of the shaft hole of the housing and the movable shaft inserted into the shaft hole in the device in which the movable shaft is assembled to the shaft hole of the housing. .. Further, in the present embodiment, the movable shaft can be applied to either a rotating shaft or an advancing / retreating shaft.

As shown in FIG. 1, the sealing device 10 in the present embodiment is provided at both ends of a lip seal portion 11 having a tip portion 11a that abuts on the surface 20a of the movable shaft 20 and both ends of the lip seal portion 11, and each of them is movable. Along the axis J direction of the shaft 20, a bellows 12 having at least one or more annular peaks 12a and / or valleys 12b is provided.

In the present embodiment, the bellows 12 provided at both ends of the lip seal portion 11 are exemplified, but are limited to those having two peaks 12a and one valley 12b, respectively. is not it. Further, the bellows 12 may be provided at both ends of the lip seal portion 11, and the number of peaks 12a and / or valleys 12b formed on each bellows 12 does not necessarily have to be the same. ..

The material of the lip seal portion 11 and the bellows 12 in the present embodiment is not particularly limited, but is preferably integrally formed of a resin member (for example, a fluororesin).

As shown in FIG. 1, the peak portion 12a and the valley portion 12b of the bellows 12 are separated from the surface 20a of the movable shaft 20 with the movable shaft 20 inserted into the shaft hole of the housing (not shown). That is, only the lip tip portion 11a is in contact with the surface 20a of the movable shaft 20.

FIG. 2 is a cross-sectional view schematically showing a state in which the sealing device 10 shown in FIG. 1 is mounted in the housing of the device.

As shown in FIG. 2, in the bellows 12 provided at both ends of the lip seal portion 11, the ends 13 of the bellows 12 are the inner wall surfaces 30a of the housings 30 and 31 whose end portions 13 are perpendicular to the axis J direction of the movable shaft 20. It is attached to the housings 30 and 31 in contact with 31a. At this time, the bellows 12 provided at both ends of the lip seal portion 11 are compressed in the axial J direction of the movable shaft 20 in a state of being attached to the housings 30 and 31. For example, after arranging the sealing device 10 in the housings 30 and 31, the housings 30 and 31 are tightened to each other with bolts 40, so that the bellows 12 provided at both ends of the lip seal portion 11 can be attached to the movable shaft 20. It can be compressed in the J direction of the axis.

As a result, the end portion 13 of the bellows 12 is pressed against the inner wall surfaces 30a and 31a of the housings 30 and 31, so that the sealing properties between the housings 30 and 31 and the sealing device 10 are ensured. At the same time, it is possible to prevent the lip seal portion 11 from rotating due to sliding with the movable shaft 20.

FIG. 3 is a cross-sectional view showing a state in which the axis J of the movable shaft 20 is eccentric to the axis J'by a distance L.

As shown in FIG. 3, the bellows 12 located on the side where the movable shaft 20 is eccentric (upper side in the figure) (hereinafter, referred to as “bellows on the eccentric side”) 12 is pushed up by the movable shaft 20 where the lip tip portion 11a is eccentric. Be done. As a result, the bellows 12 on the eccentric side bends in the direction in which the movable shaft 20 is eccentric (upper side in the drawing) with the end 13 of the bellows 12 pressed against the inner walls of the housings 30 and 31 as a fulcrum. Along with this, the bellows (hereinafter referred to as "bellows on the opposite side") 12 located on the side opposite to the eccentric side (lower side in the figure) of the movable shaft 20 also has the eccentric side with the end portion 13 of the bellows 12 as a fulcrum. Bends in the same direction as the bellows 12 (upper side of the figure). As a result, the lip tip portion 11a located on the side opposite to the eccentric side of the movable shaft 20 (lower side in the figure) is also in the direction in which the movable shaft 20 is eccentric (upper side in the figure) due to the bending of the bellows 12 on the opposite side. Move to. As a result, even if the movable shaft 20 is eccentric, the lip tip portion 11a can be moved following the eccentricity of the movable shaft 20.

Hereinafter, with reference to FIG. 4, the reason why the bellows 12 bends as described above when the movable shaft 20 is eccentric will be described. Here, FIG. 4A shows a conceptual diagram showing a state in which the movable shaft 20 is not eccentric, and FIG. 4B shows a conceptual diagram showing a state in which the movable shaft 20 is eccentric. For the sake of simplicity, in FIGS. 4A and 4B, the peak portion 12a and the valley portion 12b of the bellows 12 are omitted. Further, the inner peripheral portion of the mountain portion 12a formed in a ring shape is drawn by a straight line.

As shown in FIG. 4A, when the movable shaft 20 is not eccentric, the lip tip 11a is in contact with the surface of the movable shaft 20 in the radial direction with respect to the movable shaft 20 axis J. They are equidistant (up and down in the figure).

On the other hand, as shown in FIG. 4B, when the movable shaft 20 is eccentric by the distance L, the lip tip portion 11a located on the eccentric side is pushed up to the eccentric side (upper side in the figure) by the eccentricity of the movable shaft 20. .. As a result, the bellows 12 on the eccentric side bends in the direction in which the movable shaft 20 is eccentric (upper side in the drawing) with the end 13 of the bellows 12 pressed against the inner walls of the housings 30 and 31 as a fulcrum. Here, for convenience of explanation, the bending of the bellows 12 is exaggerated from the actual bending.

By the way, in the bellows 12 in the present embodiment, the annular peak portion 12a and the valley portion 12b are formed along the axial center J direction of the movable shaft 20. Therefore, the bellows 12 has contractility in the axial direction J direction, but hardly contracts in the circumferential direction of the peak portion 12a and the valley portion 12b. That is, the inner diameters of the annular peaks 12a and 12b hardly change. Therefore, when the bellows 12 on the eccentric side bends in the direction in which the movable shaft 20 is eccentric (upper side in the figure), the bellows 12 on the opposite side pushes the end portion 13 of the bellows 12 pressed against the inner walls of the housings 30 and 31. As a fulcrum, the inner diameters of the peaks 12a and the valleys 12b are maintained, and the bellows 12 on the eccentric side are bent in the same direction (upper side of the figure) by the same amount. As a result, the lip tip portion 11a located on the side opposite to the side where the movable shaft 20 is eccentric (lower side in the figure) is also in the direction in which the movable shaft 20 is eccentric (upper side in the figure) due to the bending of the bellows 12 on the opposite side. Moving.

As described above, according to the sealing device 10 in the present embodiment, even if the movable shaft 20 is eccentric, the bellows 12 on the eccentric side and the bellows 12 on the opposite side bend in the same direction in which the movable shaft 20 is eccentric. Therefore, the lip tip portion 11a can be moved following the eccentricity of the movable shaft 20. In particular, even when a resin having lower elasticity than rubber (for example, a fluororesin) is used as the material of the lip seal portion 11, the followability of the movable shaft 20 to the eccentricity can be ensured by the bending of the bellows 12. .. Therefore, since the press-fitting allowance of the lip seal portion 11 can be reduced, it is possible to suppress a decrease in the durability of the lip seal portion 11.

Further, since the bellows 12 on the eccentric side and the bellows 12 on the opposite side bend by the same amount in the eccentric direction, the pressure applied to the lip tip portion 11a on the eccentric side and the lip tip on the opposite side to the eccentric side There is almost no difference from the pressure applied to the portion 11a. Therefore, the pressure applied to the tip of the lip becomes larger than necessary in the peak and the valley as in the case of the conventional bellows formed along the direction perpendicular to the axis J direction of the movable shaft 20, and the lip seal. It is possible to effectively suppress a decrease in the durability of the portion, or conversely, a decrease in the pressure applied to the lip tip portion to a necessary level or less, resulting in a decrease in the sealing property of the lip seal portion.

Further, since the peak portion 12a and the valley portion 12b of the bellows 12 are formed along the axial center J direction of the movable shaft 20, the peak portion 12a and the valley portion 12b of the bellows 12 are formed along the axial center J of the movable shaft 20. It is not necessary to increase the gap between the peripheral surfaces of the shaft holes of the housings 30 and 31 and the movable shaft 20 inserted into the shaft holes, as compared with the conventional bellows formed along the direction perpendicular to the direction. Therefore, the expansion of the housing can be suppressed.

FIG. 5 is a cross-sectional view schematically showing the configuration of the sealing device 10 according to another embodiment of the present invention.

As shown in FIG. 5, in the sealing device 10 of the present embodiment, the bellows 12 provided at both ends of the lip sealing portion 11 have only one annular mountain portion along the axis J direction of the movable shaft 20. have.

Also in the bellows 12 of the present embodiment, since the annular mountain portion 12a is formed along the axial center J direction of the movable shaft 20, the bellows 12 has contractility in the axial center J direction, while the circumference of the mountain portion 12a. The direction hardly contracts. Therefore, even when the movable shaft 20 is eccentric, the bellows 12 is bent as shown in FIGS. 4A and 4B, so that the lip tip portion 11a is moved following the eccentricity of the movable shaft 20. be able to.

6 (a) is a cross-sectional view schematically showing a state in which the sealing device 10 shown in FIG. 5 is mounted in the housing of the device, and FIG. 6 (b) shows the axial center J of the movable shaft 20. , Is a cross-sectional view showing a state when eccentric to the axis J'by a distance L. As shown in FIG. 6A, the method of attaching the sealing device 10 to the housings 30 and 31 is the same as that shown in FIG. 2, and thus the description thereof will be omitted.

As shown in FIG. 6B, also in the sealing device 10 of the present embodiment, when the movable shaft 20 is eccentric, the bellows 12 on the eccentric side and the bellows 12 on the opposite side bend in the same eccentric direction. Thereby, the lip tip portion 11a can be moved following the eccentricity of the movable shaft 20.

In the present embodiment, the shape of the bellows 12 provided at both ends of the lip seal portion 11 has at least one or more annular peaks and / or valleys along the axis J direction of the movable shaft 20. There is no particular limitation as long as it has.

7 (a) to 7 (c) are cross-sectional views schematically showing the configuration of the sealing device in the modified example of the present embodiment.

In the sealing device illustrated in FIG. 7A, the area of the end portion 13 of the bellows 12 in contact with the inner wall surface of the housings 30 and 31 is smaller than that of the sealing device shown in FIG.

As described above, the bellows 12 provided at both ends of the lip seal portion 11 are compressed in the axial direction of the movable shaft in a state of being attached to the housings 30 and 31. As a result, the end portion 13 of the bellows 12 is pressed against the inner wall surfaces of the housings 30 and 31, so that the sealing property between the housings 30 and 31 and the sealing device is ensured. This sealing property is regulated by the surface pressure at the end portion 13 of the bellows 12 pressed against the inner wall surfaces of the housings 30 and 31, but this surface pressure varies depending on the material and shape of the bellows 12. Therefore, by appropriately setting the area of the end portion 13 of the bellows 12 that is in contact with the inner wall surface of the housings 30 and 31 according to the material and shape of the bellows 12, the housings 30 and 31 and the sealing device can be attached to each other. The sealability can be adjusted to the required range.

In the sealing device illustrated in FIG. 7B, the bellows 12 provided at both ends of the lip sealing portion 11 are composed of one peak portion and one valley portion, respectively, with respect to the sealing device shown in FIG. It is a thing.

Further, the sealing device illustrated in FIG. 7C has a recess 14 in a part of the end portion 13 of the bellows 12 which is in contact with the inner wall surface of the housings 30 and 31 with respect to the sealing device shown in FIG. Is provided. As a result, a space is formed between the end portion 13 of the bellows 12 and the inner wall surface of the housings 30 and 31 in a state of being in contact with the inner wall surface of the housings 30 and 31. As a result, even if the sealing property between the housings 30 and 31 and the sealing device deteriorates and the fluid in the device leaks to the outside, the fluid is temporarily allowed to enter the space formed in the recess 14. Can be stored. As a result, the time for the fluid in the device to leak to the outside can be delayed.

Although the present invention has been described above in terms of preferred embodiments, such a description is not a limitation, and of course, various modifications can be made. For example, in the above embodiment, when the movable shaft 20 is eccentric, the bellows 12 is bent in the eccentric direction of the movable shaft 20 with the end 13 of the bellows 12 pressed against the inner walls of the housings 30 and 31 as a fulcrum. As a result, the lip tip 11a was moved following the eccentricity of the movable shaft 20, but the end 13 of the bellows 12 was moved in the J direction of the axis 20 of the movable shaft 20 with respect to the inner wall surfaces of the housings 30 and 31. It may be attached so as to be slidable in the direction perpendicular to the above. As a result, in addition to the bending of the bellows 12, the sliding of the end portion 13 of the bellows 12 can further improve the followability of the movable shaft 20 of the lip tip portion 11a to the eccentricity.

10 Sealing device
11 Lip seal part
11a Lip tip
12 bellows
12a Yamabe
12b Tanibe
13 Bellows end 14 Recess
20 movable shaft
20a Surface of movable shaft
30, 31 housing
30a, 31a Inner wall surface of housing

Claims (3)

A sealing device that seals the gap between the peripheral surface of the shaft hole of the housing and the movable shaft inserted into the shaft hole.
A lip seal portion having a tip portion that abuts on the surface of the movable shaft,
A bellows provided at both ends of the lip seal portion, each having at least one or more annular peaks and / or valleys along the axial direction of the movable shaft.
The peaks and / or valleys of the bellows are separated from the surface of the movable shaft with the movable shaft inserted into the shaft hole .
The bellows provided at both ends of the lip seal portion are attached to the housing with the ends of the bellows in contact with the inner wall surface of the housing perpendicular to the axial direction of the movable shaft. , A sealing device that is compressed in the axial direction of the movable shaft. End of the bellows, the inner wall surface of the housing, slidably mounted in the axial direction perpendicular to the direction of the movable shaft, the sealing device according to claim 1. The sealing device according to claim 1, wherein the lip sealing portion and the bellows are integrally formed of a resin member.

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