JP7530705B2 - Seal Structure - Google Patents

Description

The present invention relates to a seal structure .

Conventionally, the operating environment of the reducer mounted on a robot has become severer as the robot moves faster and more frequently. For example, during high-speed or high-temperature operation, the temperature of the reducer rises and the pressure inside the reducer may increase above the desired pressure. The increase in the internal pressure of the reducer may cause the oil seal to fall off the reducer.
In addition, the lubricant or external solvent may cause chemical changes such as hardening in the rubber material of the oil seal, resulting in deformation such as a reduction in the outer diameter. As the oil seal deforms, there is a risk that the oil seal may fall off the reducer.
In order to solve these problems, it is difficult to adequately prevent the oil seal from falling off the reducer simply by increasing the pressing force against the mounting portion of the oil seal, for example by increasing the outer diameter of the oil seal. Conventionally, there has been known a sealing device equipped with a retaining member for preventing the oil seal from falling off (for example, see Patent Document 1).

JP 2016-109190 A

However, the sealing device described above is equipped with a fixing member that detachably fixes the anti-slip member. This requires special members to be included in the configuration of the sealing device, such as the anti-slip member, the fixing member, and a member to which the fixing member is attached, which can complicate the device configuration.

The present invention provides a seal structure that can properly seal the inside with a simple configuration.

A seal structure according to one aspect of the present invention comprises a case, a shaft member disposed inside the case, a seal member for sealing between the case and the shaft member, and a connecting portion that connects an outer circumferential portion of the seal member that contacts the case and an inner circumferential portion of the seal member that contacts the shaft member and that is curved convexly inward in the axial direction , the outer circumferential portion of the seal member and the connecting portion having an embedded core, the core being formed from a metallic elastic material, the connecting portion having a curved portion that is curved convexly inward in the axial direction on the outer circumferential side, the curved portion extending from an outer end of the outer circumferential portion in the axial direction to an inner end of the outer circumferential portion in the axial direction on the outer circumferential portion. and a curved outer peripheral portion extending from an inner end of the curved outer peripheral portion in the axial direction to an outer end of the inner peripheral portion in the axial direction, the outer peripheral portion and the curved outer peripheral portion extending in the axial direction of the shaft member, the curved inner peripheral portion extending in a direction intersecting the axial direction of the shaft member, an area of a face of the curved inner peripheral portion on the inner peripheral portion side is larger than an area of a face of the curved outer peripheral portion on the outer peripheral portion side, and the core portion is embedded from an inner end of the outer peripheral portion in the axial direction through the curved outer peripheral portion and the curved inner peripheral portion to an end of the curved inner peripheral portion on the inner peripheral portion side .

With this configuration, the connecting portion that is curved convexly inward in the axial direction is subjected to an additional force that presses the outer periphery of the seal member against the inner periphery of the case due to the internal pressure from the inside of the axial direction. For example, by pressing the seal member toward the case more strongly than when the connecting portion is not curved, it is possible to prevent the seal member from coming off in the axial outward direction.
In addition, the curved portion is subjected to an additional force that presses the outer peripheral portion against the inner peripheral surface of the case due to the internal pressure from the axial direction. For example, compared to when a curved portion is not provided, the seal member can be pressed more strongly toward the case, thereby preventing the seal member from slipping outward in the axial direction. Furthermore, compared to when a curved portion is provided on the inner peripheral side, for example, the resistance between the shaft member and the seal member can be reduced.

In the aforementioned configuration, the force with which the inner circumferential portion presses the case may be increased as the pressure inside the case increases.

With this configuration, as the pressure inside the case increases, the lip portion presses the case more strongly, preventing the seal from slipping outward in the axial direction.

The present invention makes it possible to properly seal the interior with a simple configuration.

1 is a cross-sectional view showing a configuration of a rotary machine including a seal structure according to a first embodiment of the present invention; FIG. 2 is an enlarged cross-sectional view of the seal member shown in FIG. FIG. 11 is a cross-sectional view of a seal member according to a modified example of the first embodiment of the present invention. FIG. 2 is a cross-sectional view of a seal member according to an embodiment of the present invention. FIG. 6 is a cross-sectional view of a seal member according to a second embodiment of the present invention.

(First Reference Example )
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of a seal structure for a rotary machine according to the present invention will now be described with reference to the accompanying drawings.
Fig. 1 is a cross-sectional view showing a configuration of a rotary machine 1 equipped with a seal structure according to a first embodiment of the present invention . Fig. 2 is an enlarged cross-sectional view of a seal member 10 shown in Fig. 1.

As shown in FIGS. 1 and 2 , a rotary machine 1 of this embodiment includes a case 2 , a shaft member 3 , two bearings 4 , and a seal member 10 .
The outer shape of the case 2 is, for example, cylindrical.
The outer shape of the shaft member 3 is formed, for example, in a cylindrical shape. The shaft member 3 is disposed inside the case 2. The central axis O of the shaft member 3 is coaxial with the central axis of the case 2. The shaft member 3 rotates around the central axis O relative to the case 2.
The two bearings 4 are disposed between the case 2 and the shaft member 3 on each of the first end 1a side and the second end 1b side in the axial direction D of the rotating machine 1. The two bearings 4 support the shaft member 3 rotatably around the central axis O with respect to the case 2. The axial direction D is a direction parallel to the central axis O of the shaft member 3.

Each bearing 4 includes, for example, an outer race 5 , an inner race 6 , and a number of balls 7 .
The outer race 5 has an outer shape, for example, a circular ring shape. The outer race 5 is fitted inside the case 2 and contacts an inner peripheral surface 2A of the case 2.
The outer shape of the inner race 6 is, for example, annular. The inner race 6 is fitted onto the outside of the shaft member 3 and is in contact with an outer circumferential surface 3B of the shaft member 3.
The outer shape of each of the plurality of balls 7 is formed, for example, into a spherical shape. The plurality of balls 7 are arranged between the outer race 5 and the inner race 6. The plurality of balls 7 are arranged around the entire circumference at predetermined intervals in the circumferential direction. Each ball 7 rolls between the outer race 5 and the inner race 6.

The seal member 10 has an outer shape, for example, an annular shape. The seal member 10 is disposed on the first end 1a side in the axial direction D of the rotary machine 1, and outwardly of the bearing 4. The seal member 10 seals an annular space formed between the case 2 and the shaft member 3.
The seal member 10 includes, for example, a base portion 11 and a lip portion 12 .
The outer shape of the base portion 11 is formed, for example, in a circular ring shape in which the cross section along the axial direction D and the radial direction R is bent into an L-shape. The base portion 11 includes a core portion 21 and a covering portion 22 that covers the core portion 21. The core portion 21 is formed of an elastic material such as metal. The covering portion 22 is formed of an elastic material such as rubber or resin.

The base portion 11 includes an outer circumferential portion 11a that contacts the inner circumferential surface 2A of the case 2, and a connecting portion 11b that connects the outer circumferential portion 11a to the lip portion 12. The outer circumferential portion 11a and the connecting portion 11b are integrally formed.
The outer shape of the outer circumferential portion 11a is formed into a circular ring shape extending along the axial direction D.
The outer shape of the connecting portion 11b is formed in a circular ring shape extending radially inward from an end portion 11c on the axially outer side of the outer circumferential portion 11a.

The base portion 11 is fitted into the inner peripheral surface 2A of the case 2 with, for example, the outer peripheral portion 11a of the base portion 11 elastically deformed radially inward, thereby holding the seal member 10 in the case 2. The outer peripheral portion 11a is elastically deformed radially inward, and is pressed against the inner peripheral surface 2A of the case 2 by elastic force.

The lip portion 12 has an outer shape, for example, a circular ring shape protruding radially inward from the end 11d of the connecting portion 11b. The lip portion 12 is made of an elastic material such as rubber or resin. The lip portion 12 is formed integrally with the connecting portion 11b.
The lip portion 12 includes a dust lip 31 , a contact lip 32 and a spring ring 33 .
The outer shape of the dust lip 31 is formed, for example, in a circular ring shape that protrudes radially inward and inclined axially outward from the end 11d of the connecting portion 11b. A tip 31a of the dust lip 31 is pressed against and contacts the outer circumferential surface 3B of the shaft member 3. The dust lip 31 prevents foreign matter floating outside the rotating machine 1 from entering the internal space of the rotating machine 1 (the space surrounded by the case 2 and the shaft member 3).

The outer shape of the contact lip 32 is formed, for example, in a circular ring shape that protrudes radially inward from the end 11d of the connecting portion 11b so as to be inclined axially inward. A tip 32a of the contact lip 32 is pressed against the outer circumferential surface 3B of the shaft member 3.
The spring ring 33 is fitted into an annular recess 32b formed on the outer circumferential surface 32A of the contact lip 32. The spring ring 33 is a so-called garter spring, and is, for example, a ring-shaped spring formed by connecting both ends of a coil spring. The spring ring 33 is made of an elastic material. The spring ring 33 stretches elastically while attached to the contact lip 32. The spring ring 33 presses the tip of the contact lip 32 radially against the outer circumferential surface 3B of the shaft member 3 by elastic force, compressing and deforming the contact lip 32.
The contact lip 32 prevents liquid foreign matter from flowing into the internal space from outside the rotating machine 1 through the dust lip 31, and prevents liquid lubricant from flowing out from the internal space of the rotating machine 1 to the outside.

The seal member 10 is fixed to the case 2 via the base portion 11. The dust lip 31 and contact lip 32 of the lip portion 12 rotate relative to the outer circumferential surface 3B of the shaft member 3 when at least one of the case 2 and the shaft member 3 rotates relative to each other.

The inner circumferential portion 2a of the case 2 in contact with the seal member 10 includes an inner diameter changing portion 41 whose inner diameter length increases from the outer side toward the inner side in the axial direction D. An inner circumferential surface 41A of the inner diameter changing portion 41 is formed in a tapered shape that is inclined at a predetermined angle θ with respect to the axial direction D, for example.
The normal direction of the inner circumferential surface 41A of the inner diameter changing portion 41 is inclined at a predetermined angle θ with respect to the radial direction R. As a result, the normal reaction force RF of the inner diameter changing portion 41 of the case 2 against the force acting from the outer circumferential portion 11a of the seal member 10 to the inner circumferential portion 2a of the case 2 acts radially inward, inclining from the outer side toward the inner side in the axial direction D.

As described above, in the seal structure of the rotating machine 1 of the first reference example , the inner circumferential surface 41A of the inner diameter changing portion 41 of the case 2 is formed in a tapered shape inclined at a predetermined angle θ with respect to the axial direction D. As a result, the normal reaction force RF of the inner diameter changing portion 41 of the case 2 acts radially inward, inclining from the outer side toward the inner side in the axial direction D. For example, compared to a case in which the normal reaction force of the inner circumferential portion 2a of the case 2 is parallel to the radial direction, by pushing the seal member 10 inward in the axial direction D, it is possible to suppress the seal member 10 from slipping outward in the axial direction D.

In the above-described first reference example , the base portion 11 may be formed only by the outer circumferential portion 11a, and the seal member 10 may be formed by the base portion 11 (outer circumferential portion 11a), the connecting portion 11b, and the lip portion 12. In this case, the base portion 11 (outer circumferential portion 11a) is fixed to the case 2, and the connecting portion 11b connects the base portion 11 (outer circumferential portion 11a) and the lip portion 12.
In addition, in the above-mentioned first reference example , the lip portion 12 is in contact with the shaft member 3 , but this is not limited thereto, and the lip portion 12 may be in contact with another member arranged on the inner periphery of the case 2 .

(Modification of the first embodiment )
The following describes a modification of the first embodiment . Note that the same components as those in the first embodiment described above are given the same reference numerals, and descriptions thereof will be omitted or simplified.
FIG. 3 is a cross-sectional view of a seal member 10 according to a modification of the first reference example .
In the above-mentioned reference example , the inner circumferential portion 2a of the case 2 that contacts the sealing member 10 is provided with an inner diameter changing portion 41, but this is not limited to this, and the outer circumferential portion 11a of the sealing member 10 may be provided with an outer diameter changing portion 42.

As shown in FIG. 3, in the modification of the first embodiment , an inner circumferential surface 2A of an inner circumferential portion 2a of a case 2 that contacts a seal member 10 is parallel to an axial direction D.
The outer circumferential portion 11a of the seal member 10 includes an outer diameter changing portion 42 whose outer diameter length changes so as to increase from the outer side toward the inner side in the axial direction D in a natural state before the seal member 10 is attached to the case 2. In a natural state before the seal member 10 is attached to the case 2, an outer circumferential surface 42B of the outer diameter changing portion 42 (for example, the outer circumferential surface 42B indicated by the dashed line in FIG. 3 ) is formed in a tapered shape that is inclined at a predetermined angle θ with respect to the axial direction D.
With the outer circumferential portion 11a of the seal member 10 attached to the case 2, the force with which the outer circumferential portion 11a is pressed against the inner circumferential surface 2A of the case 2 is greater on the inner side than on the outer side in the axial direction D. As a result, the normal reaction force RF of the inner circumferential portion 2a of the case 2 against the force acting from the outer circumferential portion 11a of the seal member 10 to the inner circumferential portion 2a of the case 2 is greater on the inner side than on the outer side in the axial direction D.

As described above, in the seal structure of the rotary machine 1 according to the modified example of the first reference example , the outer peripheral surface 42A of the outer diameter changing portion 42 of the seal member 10 is formed in a tapered shape inclined at a predetermined angle θ with respect to the axial direction D in a natural state before being attached to the case 2. As a result, the normal reaction force RF of the inner peripheral portion 2a of the case 2 against the force acting from the outer peripheral portion 11a of the seal member 10 to the inner peripheral portion 2a of the case 2 is larger on the inner side than on the outer side in the axial direction D. For example, compared to a case in which the normal reaction force RF of the inner peripheral portion 2a of the case 2 is substantially the same magnitude on the outer side and the inner side in the axial direction D, the seal member 10 is held more strongly on the inner side in the axial direction D, thereby making it possible to prevent the seal member 10 from slipping out to the outside in the axial direction D.

Furthermore, in the modified example of the first reference example described above, the force of the case 2 acting on the base portion 11 is not limited to the outer diameter changing portion 42 of the sealing member 10 described above, and may be made greater on the outer side than on the inner side in the axial direction D by other configurations.
As a result, by holding the sealing member 10 more firmly on the inner side of the axial direction D compared to, for example, a case in which the force of the case 2 acting on the base portion 11 is smaller on the outer side than on the inner side in the axial direction D, the sealing member 10 can be prevented from slipping outward in the axial direction D.

( Embodiment )
Hereinafter, an embodiment of a seal structure for a rotary machine according to the present invention will be described with reference to the accompanying drawings. Note that the same reference numerals are used to designate the same components as those in the first embodiment , and the description thereof will be omitted or simplified.
FIG. 4 is a cross-sectional view of the seal member 50 according to the embodiment .
As shown in FIG. 4, a seal member 50 of the embodiment differs from the seal member 10 of the first embodiment described above in that it includes a base portion 51 instead of the base portion 11 of the first embodiment .
The seal member 50 includes, for example, a base portion 51 and a lip portion 12. The base portion 51 includes a core portion 52 and a covering portion 53 that covers the core portion 52. The base portion 51 includes an outer periphery portion 11a and a connecting portion 51b. The outer periphery portion 11a and the connecting portion 51b are integrally formed.
The lip portion 12 protrudes radially inward from an end portion 51d of the connecting portion 51b. The lip portion 12 is formed integrally with the connecting portion 51b.

The outer shape of the connecting portion 51b is formed in a circular ring shape that extends radially inward while curving convexly axially inward from an end 11c on the axially outer side of the outer circumferential portion 11a. The connecting portion 51b includes, for example, a curved portion 54 on the radially outer circumferential side. The outer shape of the curved portion 54 is formed in a circular ring shape that curves convexly inward in the axial direction D.
The curved portion 54 has, for example, a curved outer peripheral portion 54b extending from the axially outer end 11c of the outer peripheral portion 11a toward the inner tip portion 54a of the curved portion 54, and a curved inner peripheral portion 54c extending from the inner tip portion 54a toward the end 51d of the connecting portion 51b.

Since the curved portion 54 is disposed on the radially outer periphery side of the connecting portion 51b, the inner tip portion 54a of the curved portion 54 is disposed on the radially outer periphery side between the outer periphery portion 11a and the lip portion 12. Accordingly, the area of the inner surface 54C of the curved inner periphery portion 54c is formed relatively larger than the area of the inner surface 54B of the curved outer periphery portion 54b.
The direction of the internal pressure IP acting on the inner surface 54B of the curved outer peripheral portion 54b (pressure receiving direction) is the axially outward and radially inward direction. The direction of the internal pressure IP acting on the inner surface 54C of the curved inner peripheral portion 54c (pressure receiving direction) is the axially outward and radially outward direction. The internal pressure IP is, for example, the pressure in the internal space of the rotating machine 1.
As a result, an additional force is applied to the curved portion 54 by the internal pressure IP, pressing the outer circumferential portion 11 a against the inner circumferential surface 2 A of the case 2 .

As described above, in the seal structure of the rotary machine 1 according to the embodiment , the seal member 50 includes a curved portion 54 that is curved convexly axially inward on the radially outer periphery side of the connecting portion 51b that connects the outer periphery portion 11a and the lip portion 12. As a result, a force that presses the outer periphery portion 11a against the inner periphery surface 2A of the case 2 is additionally applied to the curved portion 54 by the internal pressure IP. For example, compared to a case in which the curved portion 54 is not provided like the connecting portion 11b of the first reference example , by pressing the seal member 50 toward the case 2 more strongly, it is possible to prevent the seal member 50 from slipping outward in the axial direction D.

In addition, since the curved portion 54 is formed on the connecting portion 51b, a force that the connecting portion 51b exerts on the base portion 11 by pressing the case 2 is additionally applied to the base portion 11. For example, by pressing the seal member 50 toward the case 2 more strongly than when the curved portion 54 is not formed on the connecting portion 51b, it is possible to prevent the seal member 50 from slipping outward in the axial direction D.
In the above-described embodiment , the seal member 50 has one curved portion 54 at the connecting portion 51b, but is not limited to this and may have a plurality of curved portions.

Furthermore, in the above-described embodiment , an increase means may be provided that increases the force with which the lip portion 12 presses the case 2 in response to an increase in the pressure inside the case 2. The increase means is not limited to being formed at the connecting portion 51b as described above, and may be formed at other portions of the seal member 50.
In addition, the increasing means is not limited to the curved portion 54 formed on the connecting portion 51b as described above, and may have another configuration. As a result, as the pressure inside the case 2 increases, the lip portion 12 presses the case 2 more strongly, thereby preventing the seal member 50 from slipping outward in the axial direction D.

( Second Reference Example )
Hereinafter, a second embodiment of the seal structure for a rotary machine according to the present invention will be described with reference to the accompanying drawings. Note that the same reference numerals are used to designate the same components as those in the first embodiment , and the description thereof will be omitted or simplified.
FIG. 5 is a cross-sectional view of a seal member 60 according to a second reference example .
5, compared with the seal member 10 of the first reference example described above, the seal member 60 of the second reference example is formed to have the same outer shape in its natural state before being attached to the case 2. Also, as in the modified example of the first reference example described above, the inner circumferential surface 2A of the inner circumferential portion 2a of the case 2 that contacts the seal member 60 is parallel to the axial direction D.
The seal member 60 of the second embodiment differs from the first embodiment and the modified example described above in that the seal member 60 has a thermal expansion coefficient relatively larger than that of the case 2 .
For example, the core 21 of the seal member 60 is made of a metal material having a thermal expansion coefficient relatively larger than that of the case 2 .

As described above, in the seal structure of the rotary machine 1 according to the second reference example , the seal member 60 has a relatively larger thermal expansion coefficient than the case 2. This makes the seal member 60 more likely to expand than the case 2 when the temperature rises due to the operation of the rotary machine 1. For example, compared to when the thermal expansion coefficients of the seal member 60 and the case 2 are approximately the same or when the thermal expansion coefficient of the seal member 60 is relatively smaller than the thermal expansion coefficient of the case 2, the seal member 60 is held more strongly by the case 2, and therefore the seal member 60 can be prevented from slipping outward in the axial direction D.

In the second reference example described above, the core 21 is formed from a metal material having a thermal expansion coefficient relatively larger than that of the case 2, but this is not limited to this and the core 21 may be formed from a material such as a resin material having a thermal expansion coefficient relatively larger than that of the case 2.
In the above-described second reference example , the thermal expansion coefficient of the core portion 21 is larger than that of the case 2, but this is not limited to this. For example, instead of or in addition to the core portion 21, the thermal expansion coefficient of the covering portion 22 may be larger than that of the case 2.

In the above-described second reference example , at least a part of the outer circumferential portion 11a and the connecting portion 11b of the base portion 11 and the lip portion 12 constituting the seal member 60 may be formed of a material having a thermal expansion coefficient larger than that of the case 2. As a result, at least a part of the outer circumferential portion 11a and the connecting portion 11b of the base portion 11 and the lip portion 12 constituting the seal member 60 are more likely to expand than the case 2 when the temperature rises. For example, compared to a case where the thermal expansion coefficients of the lip portion 12, the base portion 11 and the case 2 are approximately the same or the thermal expansion coefficients of the lip portion 12 and the base portion 11 are smaller than that of the case 2, the seal member 60 is held more strongly by the case 2, and therefore it is possible to prevent the seal member 60 from slipping outward in the axial direction D.

Furthermore, the above-described second reference example may include an increase means for increasing the force with which the lip portion 12 presses the case 2 as the temperature of the case 2 rises. The increase means is not limited to forming at least a portion of the seal member 60 from a material having a higher thermal expansion coefficient than the case 2 as described above, and may include other configurations. This makes it possible to prevent the seal member 60 from slipping outward in the axial direction D by the lip portion 12 pressing the case 2 more strongly as the temperature inside the case 2 rises.

In the above-described reference examples, embodiments, and modified examples, the rotating machine 1 may be, for example, a reducer such as an eccentric oscillating reducer or a rotating electric machine.
In addition, in the above-described reference examples, embodiments, and modified examples, the seal members 10, 50, 60 may be attached to members such as a motor flange and an oil seal flange instead of the case 2.
In addition, in the above-described reference examples, embodiments, and modified examples, the respective seal members 10 , 50 , and 60 may be simply referred to as the respective seals 10 , 50 , and 60 .

The embodiments of the present invention are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are within the scope of the invention and its equivalents as set forth in the claims, as well as the scope and spirit of the invention.

1...rotating machine, 2...case, 2a...inner peripheral portion, 3...shaft member, 10, 50, 60...sealing member (seal), 11...base portion, 11a...outer peripheral portion, 11b, 51b...connecting portion, 12...lip portion (inner peripheral portion), 21...core portion, 22...covering portion, 41...inner diameter changing portion, 41A...inner peripheral surface 41A,
42: outer diameter changing portion, 42B: outer peripheral surface, 54: curved portion, 54B, 54C: inner surface (surface), 54b: curved outer peripheral portion, 54c: curved inner peripheral portion

Claims (2)

Case and
A shaft member disposed inside the case;
a seal member that seals between the case and the shaft member;
a connecting portion that connects an outer circumferential portion of the seal member that contacts the case and an inner circumferential portion of the seal member that contacts the shaft member and that is curved convexly inward in the axial direction,
The outer periphery of the seal member and the connecting portion have an embedded core,
The core portion is formed of a metallic elastic material,
The connecting portion includes a curved portion that is curved convexly toward the inside in the axial direction on an outer circumferential side,
The curved portion is
a curved outer periphery extending from an outer end of the outer periphery in the axial direction to an inner end of the outer periphery in the axial direction;
a curved inner peripheral portion that turns back from an inner end of the curved outer peripheral portion in the axial direction and extends to an outer end of the inner peripheral portion in the axial direction;
having
the outer circumferential portion and the curved outer circumferential portion extend in the axial direction of the shaft member,
The curved inner peripheral portion extends in a direction intersecting the axial direction of the shaft member,
an area of a surface of the curved inner peripheral portion on the inner peripheral portion side is larger than an area of a surface of the curved outer peripheral portion on the outer peripheral portion side;
The core portion is embedded from an inner end of the outer peripheral portion in the axial direction through the curved outer peripheral portion and the curved inner peripheral portion to an end of the curved inner peripheral portion on the inner peripheral portion side.
Seal structure. The seal structure of claim 1, in which the force with which the inner periphery presses the case increases as the pressure inside the case increases.

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