Patent Description:
In a device such as a decelerator or the like, foreign substances such as abrasion powders of a gear and a bearing are mixed in a lubricant oil. It is known that a sealing device such as an oil seal used in the decelerator or the like is provided with an auxiliary lip in addition to a seal lip (main lip) for suppressing abrasion of the seal lip due to the foreign substances mixed in the lubricant oil. The auxiliary lip that is provided nearer to a sealed-fluid side than the main lip and configured to slide on a shaft can prevent the foreign substances from entering the main lip side. In such configuration, a grease is applied between the main lip and the auxiliary lip to prevent slide abrasion of the main lip.

However, if an application amount of the grease is insufficient, not only the foreign substances but also the sealed fluid such as lubricant oil or the like is prevented from entering the main lip side by the auxiliary lip and thus, the slide abrasion of the main lip may be accelerated.

<CIT>, <CIT>, <CIT>, <CIT> and <CIT>- <CIT> respectively disclose a sealing device having the features of the preamble of claim <NUM>.

An object of the present disclosure is to further develop a sealing device according to the preamble of claim <NUM> such as to suppress slide abrasion of the main lip in the sealing device.

This object is achieved by a sealing device having the features of claim <NUM>. Advantageous further developments are defined in the dependent claims.

The sealing device of the present disclosure is a sealing device for sealing an annular gap between a shaft and a housing rotating relatively, the sealing device including:.

According to the present disclosure, the foreign substances contained in the sealed fluid can be prevented from entering the main lip side by the auxiliary lip. Since the gaps connecting the region on the sealed-fluid side with the region on the opposite side thereto are formed due to the protrusions, the sealed fluid enters the main lip side. As a result, slide abrasion of the main lip can be suppressed. The sliding surface of each of the plurality of protrusions is configured to be in parallel with the slanted surface constituting the inner surface of the auxiliary lip in the cross section by the plane containing the central axis of the sealing device in a state where an external force does not act on the auxiliary lip. This suppresses variation in manufacturing in the height of the protrusions with respect to the slanted surface.

The sealing device may have a first sealing device including the main lip; and
a second sealing device fixed by fitting to an inner surface of the first sealing device and including the auxiliary lip.

The main lip and the auxiliary lip may be provided integrally.

The sealing device may have a first sealing device including the main lip; and
a second sealing device fixed by fitting to an inner surface of a shaft hole of the housing and including the auxiliary lip.

As described above, the slide abrasion of the main lip can be suppressed.

Hereinafter, embodiments for implementing the present disclosure will be described exemplarily in detail based on embodiments by referring to drawings. However, dimensions, materials, shapes, relative disposition and the like of components described in the embodiments are not intended to limit the scope of the present disclosure that is only limited by the scope of the appended claims.

By referring to <FIG> and <FIG>, a sealing device according to the first embodiment of the present disclosure will be described. <FIG> is a schematic sectional view of the sealing device according to the first embodiment of the present disclosure. The sealing device according to the present embodiment has a substantially rotationally symmetrical shape, and <FIG> illustrates a cross sectional view by a plane containing a central axis of the sealing device. <FIG> illustrates the sealing device in a state where an external force does not act on it, and in the figure, positions of the housing and the shaft when the sealing device is in use are indicated by dotted lines. <FIG> is an illustration of an auxiliary lip according to the first embodiment of the present disclosure. <FIG> is a cross sectional view indicated by AA in <FIG>, and <FIG> is a cross sectional view illustrating the auxiliary lip in a state where the shaft is inserted into the sealing device.

A sealing structure using the sealing device as an oil seal according to the present embodiment will be now described. The sealing device <NUM> can be suitably used for sealing an annular gap between a shaft <NUM> and a housing <NUM> that are rotated relatively in a decelerator, a servomotor or the like. In the figure, a region on the right side is a sealed region in which a sealed fluid such as oil e.g. lubricant oil is sealed, while a region on the left side is an opposite region to the sealed region, which is an atmospheric region here. Hereinafter, the side to be the sealed region side in use, that is, the right side in <FIG>, is called a "sealed-fluid side (O)", while the side to be the atmospheric region side, that is, the left side in <FIG>, is called an "opposite side (A)". The sealing device <NUM> is fixed by fitting to an inner surface of a shaft hole of the housing <NUM>. When the shaft <NUM> and the housing <NUM> are rotated relatively, the sealing device <NUM> remains stationary with respect to the housing <NUM>, while sliding occurs between the sealing device <NUM> and the shaft <NUM>.

The sealing device <NUM> will be explained in more detail. The sealing device <NUM> has a first sealing device <NUM> fixed by fitting to the inner surface of the shaft hole of the housing <NUM> and a second sealing device <NUM> fixed by fitting to the inner surface of the first sealing device <NUM>. The first sealing device <NUM> includes a reinforcing ring <NUM> and a seal body <NUM> made of a rubber-like elastic body provided integrally with the reinforcing ring <NUM>. The first sealing device <NUM> is fabricated by molding the seal body <NUM> by insert molding with the reinforcing ring <NUM> as an insert part. The reinforcing ring <NUM> has a cylindrical portion <NUM> and an inward flange portion <NUM> provided on an end portion of the cylindrical portion <NUM> on the opposite side (A). The seal body <NUM> includes an outer seal portion <NUM>, a main lip <NUM>, and a dust lip <NUM>. The outer seal portion <NUM> is configured to be in close contact with the inner surface of the shaft hole of the housing <NUM>. The sealing device <NUM> is fixed by fitting to the inner surface of the shaft hole of the housing <NUM>, preventing the sealed fluid from leaking from the gap between the sealing device <NUM> and the inner surface of the shaft hole of the housing <NUM>. The main lip <NUM> and the dust lip <NUM> are both configured to be slidable on the outer surface of the shaft <NUM>. The main lip <NUM> mainly functions to prevent the leakage of the sealed fluid. The main lip <NUM> has a garter spring <NUM> on the outer surface side of the main lip <NUM>, the garter spring <NUM> pressing a distal end of the main lip <NUM> on the radially inward side onto the shaft <NUM>. The dust lip <NUM> mainly functions to prevent foreign substances such as dusts from the outside from entering the sealed-fluid side (O).

The second sealing device <NUM> includes a reinforcing ring <NUM> and a seal body <NUM> made of a rubber-like elastic body provided integrally with the reinforcing ring <NUM>. The second sealing device <NUM> is fabricated by molding the seal body <NUM> by insert molding with the reinforcing ring <NUM> as an insert part. The reinforcing ring <NUM> has a substantially cylindrical portion <NUM> and an inward flange portion <NUM> provided on an end portion of the substantially cylindrical portion <NUM> on the sealed-fluid side (O). The seal body <NUM> includes an auxiliary lip <NUM> slidable on the shaft <NUM>. The second sealing device <NUM> is fixed by fitting to the inner surface of the first sealing device <NUM>. The substantially cylindrical portion <NUM> of the reinforcing ring <NUM> in the second sealing device <NUM> is fixed by fitting to a portion of the seal body <NUM> in the first sealing device <NUM>, the portion being located on the radially inward side of the cylindrical portion <NUM> of the reinforcing ring <NUM>. The auxiliary lip <NUM> of the second sealing device <NUM> is provided nearer to the sealed-fluid side (O) than the main lip <NUM>. The auxiliary lip <NUM> mainly functions to prevent the foreign substances such as metal powders contained in the sealed fluid from entering the main lip <NUM> side. The auxiliary lip <NUM> suppresses abrasion of the main lip <NUM>. Thus, the product life of the main lip <NUM> can be extended.

Grease is applied to the inner surfaces of both the main lip <NUM> and the auxiliary lip <NUM> of the sealing device <NUM>. This improves slidability between the main lip <NUM> and the shaft <NUM> and the slidability between the auxiliary lip <NUM> and the shaft <NUM>.

The auxiliary lip <NUM> will be explained in more detail. The inner surface of the auxiliary lip <NUM> has a slanted surface 221a whose diameter increases from the lip distal end toward the opposite side (A) of the sealed-fluid side (O). The inner surface of the auxiliary lip <NUM> has, in addition to the slanted surface 221a, a slanted surface whose diameter increases from the lip distal end toward the sealed-fluid side (O). These slanted surfaces intersect each other substantially perpendicularly at an intersection portion, which corresponds to the lip distal end. The slanted surface 221a is provided with a plurality of protrusions <NUM> with intervals in the circumferential direction, each of the protrusions <NUM> being slidable on the shaft <NUM>. Each of the protrusions <NUM> functions to form a gap S on both sides of each of the protrusions <NUM>, that is, on both sides in the circumferential direction. The gap S connects a region on the sealed-fluid side (O) with a region on the opposite side (A) as seen in <FIG>. Near the distal end of the slanted surface 221a in the auxiliary lip <NUM>, portions other than the gap S formed on the both sides of each of the protrusions <NUM> are in slidable contact with the shaft <NUM>.

A sliding surface 222a of each of the plurality of protrusions <NUM> is configured to be in parallel with the slanted surface 221a in cross section by the plane containing the central axis of the sealing device <NUM> in a state where the external force does not act on the auxiliary lip <NUM>. Note that the central axis of the sealing device <NUM> can also be referred to as a central axis of the second sealing device <NUM> in the present embodiment. The inner surface of each of the protrusions <NUM> has, in addition to the sliding surface 222a, a slanted surface 222b by which the height of the protrusion <NUM> decreases toward a base part of the auxiliary lip <NUM> from the sliding surface 222a.

The seal body <NUM> of the second sealing device <NUM> is fabricated by the insert molding as described above. After the insert molding is done and the insert-molded product is taken out of a die, a part of the molded product on the distal end side with respect to a part to be the auxiliary lip <NUM> is cut off and removed. The part to be removed is indicated as a removed part 221X by a dotted line in <FIG>. The height of the protrusions <NUM>, that is, the height from the slanted surface 221a to the sliding surface 222a, will be constant even if there are variations in positions at which the part 221X is cut off and removed, because the sliding surface 222a is configured to be in parallel with the slanted surface 221a in the cross section by the plane containing the central axis of the sealing device <NUM>. Therefore, the variations in the width of the gaps S formed by the protrusions <NUM> can be suppressed.

The sealing device <NUM> according to the present embodiment can prevent the foreign substances contained in the sealed fluid from entering the main lip <NUM> side due to the auxiliary lip <NUM>. At the same time, the sealed fluid is allowed to enter the main lip <NUM> side due to the gaps S connecting the region on the sealed-fluid side (O) with the region on the opposite side (A) formed by the protrusions <NUM>. This suppresses slide abrasion of the main lip in a case the application amount of the grease is insufficient.

The sliding surface 222a of each of the plurality of protrusions <NUM> is configured to be in parallel with the slanted surface 221a constituting the inner surface of the auxiliary lip <NUM> in the cross section by the plane containing the central axis of the sealing device <NUM> in the state where an external force does not act on the auxiliary lip <NUM>. This suppresses the variation in the height of the protrusions <NUM> with respect to the slanted surface 221a in manufacture. Thus, the variation in the width of the gaps S formed by the protrusions <NUM> can be suppressed.

Note that the number, arrangement, and height of the protrusions <NUM> can be appropriately set in view of usage environment. In the present embodiment, a plurality of sets of protrusions <NUM> are provided with intervals in the circumferential direction, each set consisting of two protrusions <NUM>. For example, four sets, eight in total, of protrusions <NUM> may be provided at <NUM>-degree intervals in the circumferential direction, or three sets, six in total, of protrusions <NUM> may be provided at <NUM>-degree intervals in the circumferential direction.

<FIG> illustrates the second embodiment of the present disclosure. In the first embodiment, the auxiliary lip is provided in the second sealing device that is fixed by fitting to the inner surface of the first sealing device. In the present embodiment, however, another structure will be described, in which a main lip and an auxiliary lip are integrally provided. <FIG> is a schematic sectional view of the sealing device according to the second embodiment of the present disclosure. The sealing device according to the present embodiment has a substantially rotationally symmetrical shape. <FIG> illustrates the sealing device in a sectional view by a plane containing the central axis of the sealing device. <FIG> illustrates the sealing device in a state where an external force does not act on it, where positions of the housing and the shaft when the sealing device is in use are indicated by dotted lines. Since a sealing structure using a sealing device 10X according to the present embodiment is similar to that of the first embodiment, the explanation will be omitted.

The sealing device 10X includes a reinforcing ring <NUM> and a seal body <NUM> made of a rubber-like elastic body provided integrally on the reinforcing ring <NUM>. The sealing device 10X is fabricated by molding the seal body <NUM> by insert molding with the reinforcing ring <NUM> as an insert component. The reinforcing ring <NUM> is constituted by a cylindrical portion <NUM> and an inward flange portion <NUM> provided on an end portion of the cylindrical portion <NUM> on the opposite side (A) of the sealed-fluid side (O). The seal body <NUM> includes an outer seal portion <NUM>, a main lip <NUM>, and a dust lip <NUM>. The outer seal portion <NUM> is configured to be in close contact with the inner surface of the shaft hole of the housing <NUM>. The sealing device 10X is fixed by fitting to the inner surface of the shaft hole of the housing <NUM>, preventing the sealed fluid from leaking from the gap between the sealing device 10X and the inner surface of the shaft hole of the housing <NUM>. The main lip <NUM> and the dust lip <NUM> are both configured to be slidable on the outer surface of the shaft <NUM>. The main lip <NUM> mainly functions to prevent the leakage of the sealed fluid. The main lip <NUM> has a garter spring <NUM> on the outer surface side of the main lip <NUM>, the garter spring <NUM> pressing the distal end of the main lip <NUM> on a radially inward side onto the shaft <NUM>. The dust lip <NUM> mainly functions to prevent the foreign substances such as dusts from the outside from entering the sealed-fluid side (O).

In the present embodiment, an auxiliary lip <NUM> is provided nearer to the sealed-fluid side (O) than the main lip <NUM>, and the main lip <NUM> and the auxiliary lip <NUM> are provided integrally. The auxiliary lip <NUM> mainly functions to prevent the foreign substances such as metal powders contained in the sealed fluid from entering the main lip <NUM> side. The auxiliary lip <NUM> suppresses abrasion of the main lip <NUM>, and the product life of the main lip <NUM> can be extended.

Grease is applied to the inner surfaces of both the main lip <NUM> and the auxiliary lip <NUM> of the sealing device 10X. This improves the slidability between the main lip <NUM> and the shaft <NUM> and the slidability between the auxiliary lip <NUM> and the shaft <NUM>.

The auxiliary lip <NUM> is provided with, similarly to the first embodiment, a plurality of protrusions <NUM> with intervals in the circumferential direction, each of the protrusions <NUM> being slidable on the shaft <NUM>. The structure, effects, and manufacturing methods and the like of the auxiliary lip <NUM> and the protrusions <NUM> are similar to the auxiliary lip <NUM> and the protrusions <NUM> of the first embodiment, of which explanation will be omitted.

The sealing device 10X according to the present embodiment configured as above achieves the similar effects to the first embodiment.

<FIG> illustrates the third embodiment of the present disclosure. In the first embodiment, the second sealing device having the auxiliary lip is fixed by fitting to the inner surface of the first sealing device. In the present embodiment, however, another structure will be described in which a second sealing device having an auxiliary lip is fixed by fitting to an inner surface of a shaft hole of a housing. <FIG> is a schematic sectional view of the sealing device according to the third embodiment of the present disclosure. The sealing device according to the present embodiment has a substantially rotationally symmetrical shape. <FIG> illustrates the sealing device in a sectional view by a plane containing a central axis of the sealing device is illustrated. <FIG> illustrates the sealing device in a state where an external force does not act on it, where positions of the housing and the shaft when the sealing device is in use are indicated by dotted lines. Since a sealing structure using a sealing device 10Y according to the present embodiment is similar to that of the first embodiment, the explanation will be omitted.

The sealing device 10Y is constituted by a first sealing device <NUM> fixed by fitting to the inner surface of the shaft hole of the housing <NUM> and a second sealing device <NUM> fixed by fitting to the inner surface of the shaft hole of the housing <NUM>. The first sealing device <NUM> includes a reinforcing ring <NUM> and a seal body <NUM> made of a rubber-like elastic body provided integrally with the reinforcing ring <NUM>. The first sealing device <NUM> is fabricated by molding the seal body <NUM> by insert molding with the reinforcing ring <NUM> as an insert component. The reinforcing ring <NUM> is constituted by a cylindrical portion <NUM> and an inward flange portion <NUM> provided on an end portion of the cylindrical portion <NUM> on the opposite side (A) of the sealed-fluid side (O). The seal body <NUM> includes an outer seal portion <NUM>, a main lip <NUM>, and a dust lip <NUM>. The structures, the roles and the like of the outer seal portion <NUM>, the main lip <NUM>, and the dust lip <NUM> are similar to the outer seal portion <NUM>, the main lip <NUM>, and the dust lip <NUM> described in the first embodiment, of which explanation will be omitted.

The second sealing device <NUM> includes a reinforcing ring <NUM> and a seal body <NUM> made of a rubber-like elastic body provided integrally with the reinforcing ring <NUM>. The second sealing device <NUM> is fabricated by molding the seal body <NUM> by insert molding with the reinforcing ring <NUM> as an insert component. The reinforcing ring <NUM> is constituted by an annular member. The seal body <NUM> includes an auxiliary lip <NUM> slidable on the shaft <NUM>. The second sealing device <NUM> configured is fixed by fitting to the inner surface of the shaft hole of the housing <NUM> to be adjacent to the first sealing device <NUM> nearer to the sealed-fluid side (O) than the first sealing device <NUM>. Thus, the auxiliary lip <NUM> of the second sealing device <NUM> is provided nearer to the sealed-fluid side (O) than the main lip <NUM>. The auxiliary lip <NUM> mainly functions to prevent the foreign substances such as metal powders contained in the sealed fluid from entering the main lip <NUM> side. The auxiliary lip <NUM> suppresses abrasion of the main lip <NUM>, and thus the product life of the main lip <NUM> can be extended.

Grease is applied to the inner surfaces of both the main lip <NUM> and the auxiliary lip <NUM> of the sealing device 10Y. This improves the slidability between the main lip <NUM> and the shaft <NUM> and the slidability between the auxiliary lip <NUM> and the shaft <NUM>.

Claim 1:
A sealing device (<NUM>, 10X, 10Y) for sealing an annular gap between a shaft (<NUM>) and a housing (<NUM>) rotating relatively, the sealing device (<NUM>, 10X, 10Y) comprising:
a main lip (<NUM>, <NUM>, <NUM>) slidable on the shaft (<NUM>); and
an auxiliary lip (<NUM>, <NUM>, <NUM>) provided nearer to a sealed-fluid side (O) than the main lip (<NUM>, <NUM>, <NUM>), and slidable on the shaft (<NUM>), wherein
an inner surface of the auxiliary lip (<NUM>, <NUM>, <NUM>) has a slanted surface (221a) of which a diameter increases toward an opposite (A) side to the sealed-fluid side (O) from a lip distal end; and
the slanted surface (221a) is provided with a plurality of protrusions (<NUM>, <NUM>, <NUM>) with intervals in a circumferential direction, each of the protrusions (<NUM>, <NUM>, <NUM>) being slidable on the shaft (<NUM>), on both sides of each of the protrusions (<NUM>, <NUM>, <NUM>) being formed gaps (S), and the gaps (S) connecting a region on the sealed-fluid side (O) with a region on an opposite side (A) thereto;
characterized in that
a sliding surface (222a) of each of the plurality of protrusions (<NUM>, <NUM>, <NUM>) is configured to be in parallel with the slanted surface (221a) in cross section by a plane containing a central axis of the sealing device (<NUM>, 10X, 10Y) in a state where an external force does not act on the auxiliary lip (<NUM>, <NUM>, <NUM>).