Patent Description:
Conventionally, sealing devices are used to seal a gap between a rotating shaft and a through-hole into which the shaft is inserted. Some of such sealing devices are used for mechanisms such as differential mechanisms in vehicles that are exposed to foreign matter such as muddy water, rainwater, and dust. Some of such sealing devices have a side lip formed so as to extend to an open-air side to prevent entry of foreign matter. The side lip is in contact with a member such as a deflector extending radially from a shaft and thereby prevents foreign matter from entering the inside from the open-air side.

<FIG> is a cross-sectional view of a conventional sealing device in a state of being attached to a differential mechanism provided in a transaxle, for example. As illustrated in <FIG>, a conventional sealing device <NUM> includes an annular reinforcing ring <NUM> and an annular elastic body part <NUM> formed from an elastic body that is integrally formed with the reinforcing ring <NUM>, and the elastic body part <NUM> includes a seal lip <NUM>, a dust lip <NUM>, and a side lip <NUM>. The seal lip <NUM> in a usage state is in contact with an axle <NUM> of a differential mechanism <NUM> to thereby prevent lubricant in a housing <NUM> in which the differential mechanism <NUM> is housed from leaking out. The dust lip <NUM> is formed outside (at the open-air side of) the seal lip <NUM>, and is in contact with or adjacent to the axle <NUM> to thereby prevent foreign matter from entering into the housing <NUM> from the outer side. The side lip <NUM> extends toward the outer side on an outer periphery side of the dust lip <NUM>, and has a conical cylindrical shape that increases in diameter toward the outer side. As illustrated in <FIG>, the side lip <NUM> in the usage state prevents foreign matter from entering from the outer side, with a distal end edge of the side lip <NUM> being in contact with a sliding surface 113a of an annular deflector <NUM> fixed to the axle <NUM>. The side lip <NUM> is elastically deformed and curved in a state of being in contact with the deflector <NUM>, and a sliding resistance is generated between the side lip <NUM> and the sliding surface 113a of the deflector <NUM> during rotation of the axle <NUM>. Grease as a lubricant is applied to an inner peripheral surface of the side lip <NUM> to reduce the sliding resistance (for example, see Patent Literature <NUM>). Patent Literature <NUM> discloses a sealing device. Patent Literature <NUM> discloses a sealing device having the features of the preamble of claim <NUM>.

In the conventional sealing device <NUM>, the grease between the side lip <NUM> and the deflector <NUM> is used, as described above, to reduce the sliding resistance between the side lip <NUM> and the deflector <NUM>. However, there may be a possibility that the grease between the side lip <NUM> and the deflector <NUM> is removed by centrifugal force caused by rotation of the deflector <NUM>, resulting in a reduction in amount of the grease between the side lip <NUM> and the deflector <NUM>. A reduction in the amount of the grease between the side lip <NUM> and the deflector <NUM> increases the sliding resistance by the side lip <NUM> to the deflector <NUM>. This may facilitate wear on the side lip <NUM>, cause weakening by heat generation, and lead to a decrease in sealing performance of the side lip <NUM>.

Thus, the conventional sealing device used for the differential mechanism has been required to have a configuration that inhibits a reduction in amount of grease between the side lip and the deflector.

The present invention has been made in view of the above-described problem, and it is an object of the present invention to provide a sealing device capable of inhibiting a reduction in amount of lubricant between a side lip and a deflector.

To achieve the above object, a sealing device according to the present invention is provided as set forth in claim <NUM>. Advantageous further developments are set out in the dependent claims.

According to the sealing device according to the present invention, it is possible to inhibit a reduction in amount of lubricant between the side lip and a deflector.

Hereinafter, Embodiments of the present invention are described below with reference to the drawings.

<FIG> is a cross-sectional view taken along an axis line x for illustrating a schematic configuration of a sealing device <NUM> according to a first embodiment of the present invention. The sealing device <NUM> according to the first embodiment of the present invention is used to seal a gap between a through-hole and a shaft inserted through the through-hole, the through-hole and the shaft rotating relative to each other. The sealing device <NUM> is used, for example, for a device having a differential mechanism for absorbing a difference in rotational speed between right and left driving wheels during turning of a vehicle, a general purpose machine, or the like. Examples of the device having the differential mechanism include transaxles and differential devices. In the present embodiment, the sealing device <NUM> is used for a transaxle. Specifically, in the transaxle, the sealing device <NUM> is used for sealing between a through-hole formed in a housing and an axle as an output shaft of the differential mechanism, the axle being rotatably inserted through the through-hole, as described later. A component to which the sealing device <NUM> is applied is not limited to this specific example. The sealing device <NUM> can be applied to other rotating members in various machines.

Hereinafter, a direction directed by an arrow a in a direction of the axis line x (see <FIG>) represents an outer side, and a direction directed by an arrow b in the direction of the axis line x (see <FIG>) represents an inner side, for convenience of explanation. The outer side means a side facing the outside of a component to which the sealing device is applied, and the inner side means a side facing the inside of the component to which the sealing device is applied. More specifically, the outer side means a side facing the outside of the housing in the transaxle having a differential mechanism, and an atmosphere side, and the inner side means a side facing the inside of the housing in the transaxle. In a direction perpendicular to the axis line x (hereinafter also referred to as a "radial direction"), a direction away from the axis line x (a direction directed by an arrow c in <FIG>) represents an outer periphery side, and a direction approaching the axis line x (a direction directed by an arrow d in <FIG>) represents an inner periphery side.

The sealing device <NUM> includes a reinforcing ring <NUM> having an annular shape around the axis line x and an elastic body part <NUM> formed from an elastic body, is the elastic body part being attached to the reinforcing ring <NUM> and having an annular shape around the axis line x. The elastic body part <NUM> includes a seal lip <NUM> having an annular shape, the seal lip <NUM> contacting a shaft of the component to which the sealing device is applied such that the shaft is slidable, as described later, and a side lip <NUM> having an annular shape, the side lip <NUM> is provided on the outer side (an arrow a direction side) of the seal lip <NUM> and extending toward the outer side. In an inner peripheral surface 22a that is a surface of the side lip <NUM> on the inner periphery side, at least one circumferential groove <NUM> which is a groove having an annular shape around the axis line x is provided and at least one axial groove <NUM> which is a groove extending along a direction of the axis line x is provided. The circumferential groove <NUM> and the axial groove <NUM> are connected with each other. Hereinafter, a structure of the sealing device <NUM> will be described in detail.

As illustrated in <FIG>, the reinforcing ring <NUM> is an annular member centered about or substantially centered about the axis line x and is made of metal. A shape of a cross section along the axis line x (hereinafter also referred to simply as a "cross section") of the reinforcing ring <NUM> is an L shape or a substantially L shape. The reinforcing ring <NUM>, for example, includes a cylindrical part <NUM> that is a cylindrical or substantially cylindrical portion extending in the direction of the axis line x, and a disc part <NUM> that is a hollow disc-shaped portion extending toward the inner periphery side from an outer end portion of the cylindrical part <NUM>. The cylindrical part <NUM> is formed such that the sealing device <NUM> is allowed to be fitted to an inner peripheral surface of the through-hole formed in the housing of the transaxle, as described later. The cylindrical part <NUM> may be arranged to be fitted in direct contact with the inner peripheral surface of the through-hole, or may be arranged to be fitted in contact with the inner peripheral surface of the through-hole through a portion of the elastic body part <NUM>.

As illustrated in <FIG>, the elastic body part <NUM> is attached to the reinforcing ring <NUM>, and is integrally formed with the reinforcing ring <NUM> in such a manner that the elastic body part <NUM> covers the entire reinforcing ring <NUM> in the present embodiment. The elastic body part <NUM>, as described above, includes the seal lip <NUM> and the side lip <NUM> and also includes an annular dust lip <NUM> that is provided on the outer side (the arrow a direction side) of the seal lip <NUM> and that extends toward the axis line x. The elastic body part <NUM> further includes an annular lip waist portion <NUM>. The seal lip <NUM> is formed so as to be in contact with an axle of the differential mechanism such that the axle is slidable, as described later. The side lip <NUM> is formed so as to be in contact with an annular deflector fixed to the axle such that the deflector is slidable, and the side lip <NUM> extends toward the outer side on the outer periphery side of the dust lip <NUM> as described later. The dust lip <NUM> is provided on the outer side of the seal lip <NUM> and formed so as to be in contact with the axle such that the axle is slidable. In the elastic body part <NUM>, the lip waist portion <NUM> is a portion positioned in the vicinity of an end portion on the inner periphery side of the disc part <NUM> of the reinforcing ring <NUM>.

Specifically, the seal lip <NUM> is a portion that extends toward the inner side from the lip waist portion <NUM>, and an annular portion centered about or substantially centered about the axis line x, and is formed so as to face the cylindrical part <NUM> of the reinforcing ring <NUM>, as illustrated in <FIG>. The seal lip <NUM> has an annular lip distal end portion <NUM> at an inner end portion, the lip distal end portion <NUM> having a cross section shape formed in a wedge shape projecting toward the inner periphery side. A garter spring <NUM> is fitted at a position facing away from the lip distal end portion <NUM> on the outer periphery side of the seal lip <NUM>. The garter spring <NUM> presses the lip distal end portion <NUM> in a direction toward the axis line x to apply a tensional force of a predetermined magnitude to the lip distal end portion <NUM> against the axle such that the lip distal end portion <NUM> follows a displacement of the axle. The lip distal end portion <NUM> is in contact with an outer peripheral surface of the axle to seal between the sealing device <NUM> and the axle, as described later. As illustrated in <FIG>, a plurality of screw projections 25b are formed at equal angle intervals in a circumferential direction on a taper surface 25a of a conical surface shape of the lip distal end portion <NUM> on the outer side, the screw projections 25b extending diagonally with respect to a distal end of the lip distal end portion <NUM> and projecting to the inner periphery side. The screw projections 25b generate air flow from the outer side to the inner side when the axle is slid, to thereby prevent lubricant from leaking from the inner side. The elastic body part <NUM> may not be provided with the screw projections 25b.

The dust lip <NUM> extends toward the outer side and the axis line x from the lip waist portion <NUM>, more particularly, as illustrated in <FIG>, the dust lip <NUM> extends in a direction toward the outer side and the inner periphery side from the lip waist portion <NUM>. The dust lip <NUM> prevents foreign matter such as muddy water, sand, and dust from entering in a direction from the outer side toward the lip distal end portion <NUM>. In the dust lip <NUM>, in order that a negative pressure is not generated in a space between the dust lip <NUM> and the seal lip <NUM> in a usage state, a plurality of projections 23a projecting in the inner peripheral direction are formed at equal angle intervals in the circumferential direction so that a gap is formed by partially releasing the contact between the dust lip <NUM> and the axle to thereby suppress the generation of the negative pressure or eliminate the negative pressure. The dust lip <NUM> may be adjacent to the axle without being in contact with the axle, or may not have the projections 23a.

The elastic body part <NUM> includes a gasket part <NUM>, a rear cover part <NUM>, and a lining part <NUM>. In the elastic body part <NUM>, the gasket part <NUM> is a portion that covers the cylindrical part <NUM> of the reinforcing ring <NUM> from the outer periphery side. As described later, the thickness in the radial direction of the gasket part <NUM> is set so that, when, in the transaxle, the sealing device <NUM> is press-fitted into a through-hole through which the axle is inserted, the gasket part <NUM> is compressed between the through-hole and the cylindrical part <NUM> of the reinforcing ring <NUM> in the radial direction so that the gasket part <NUM> generates a fitting force of a predetermined magnitude in the radial direction. The rear cover part <NUM> is a portion that covers the disc part <NUM> of the reinforcing ring <NUM> from the outer side. The lining part <NUM> is a portion that covers the reinforcing ring <NUM> from the inner side and the inner periphery side.

As illustrated in <FIG>, the side lip <NUM> extends from the lip waist portion <NUM> toward the outer side, an end portion of the side lip <NUM> on the outer side is wider than an end portion of the side lip <NUM> on the inner side. The side lip <NUM>, for example, increases in diameter from the inner side to the outer side in the direction of the axis line x and has a shape such as a conical cylindrical or substantially conical cylindrical shape or a trumpet-like shape. As described above, in the inner peripheral surface 22a of the side lip <NUM>, one or more of the circumferential grooves <NUM>, which is annular around the axis line x, are formed and one or more of the axial grooves <NUM> extending along the direction of the axis line x are formed. Specifically, as illustrated in <FIG>, in the inner peripheral surface 22a of the side lip <NUM>, a plurality of the circumferential grooves <NUM> recessed from the inner peripheral surface 22a are formed, in addition, in the inner peripheral surface 22a of the side lip <NUM>, a plurality of the axial grooves <NUM> recessed from the inner peripheral surface 22a are formed. Numbers of the circumferential grooves <NUM> and the axial grooves <NUM> are not limited to the numbers illustrated in the figure. The illustrated numbers are example numbers.

<FIG> is an enlarged view illustrating a portion of the inner peripheral surface 22a of the side lip <NUM> where the circumferential grooves <NUM> and the axial grooves <NUM> are formed, the inner peripheral surface 22a being viewed in the radial direction. Specifically, as illustrated in <FIG> and <FIG>, the circumferential grooves <NUM> each extend in the shape of a circle or substantially circle centered or substantially centered about the axis line x. The circumferential grooves <NUM> are mutually concentric or substantially concentric circles. In the inner peripheral surface 22a, the circumferential grooves <NUM> are arranged at equal or substantially equal intervals in the direction of the axis line x.

Specifically, as illustrated in <FIG> and <FIG>, the axial grooves <NUM> extend parallel to or substantially parallel to the axis line x and are arranged at equal or substantially equal intervals in the circumferential direction in the inner peripheral surface 22a. The axial grooves <NUM> are connected or intersect with the circumferential grooves <NUM> and extend across, as illustrated in <FIG> and <FIG>, between the circumferential groove <NUM> at an innermost place and the circumferential groove <NUM> at an outermost place, for example. In an example illustrated in the figures, the axial grooves <NUM> reach and end at the circumferential groove <NUM> at the outermost place. However, the axial grooves <NUM> may penetrate through the circumferential groove <NUM> at the outermost place. Similarly, in the illustrated example, the axial grooves <NUM> reach and end at the circumferential groove <NUM> at the innermost place. The axial grooves <NUM> may penetrate through the circumferential groove <NUM> at the innermost place. The axial grooves <NUM> may not extend across between the circumferential groove <NUM> at the innermost place and the circumferential groove <NUM> at the outermost place but may each extend across between at least two of the adjacent circumferential grooves <NUM>. However, in this case, the axial grooves <NUM> each extend such that the circumferential groove <NUM> at the innermost place communicates with the circumferential groove <NUM> at the outermost place through part or all of the axial grooves <NUM>.

In the sealing device <NUM> in the usage state, as described later, a predetermined width (a seal width δ) of the inner peripheral surface 22a of the side lip <NUM> along the direction of the axis line x is in contact with the deflector. In the inner peripheral surface 22a, both or one of the circumferential grooves <NUM> and the axial grooves <NUM> are at least partly formed within a range of the seal width δ. The circumferential grooves <NUM> and the axial grooves <NUM> are also formed in an area on the inner side of the seal width δ. The circumferential grooves <NUM> and the axial grooves <NUM> may be formed in the area on the inner side of the seal width δ until a root of the side lip <NUM> (a part joined to the lip waist portion <NUM>) or until a midway portion through the side lip <NUM>. The circumferential grooves <NUM> and the axial grooves <NUM> do not reach an edge (a distal end edge 22b) on a distal end of the side lip <NUM>.

Note that the elastic body part <NUM> is integrally formed from an elastic material, and the seal lip <NUM>, the side lip <NUM>, the dust lip <NUM>, the lip waist portion <NUM>, the gasket part <NUM>, the rear cover part <NUM>, and the lining part <NUM> are respective portions of the elastic body part <NUM> that is integrally formed from the elastic material.

The metal material for the reinforcing ring <NUM> is, for example, stainless steel or SPCC (a cold rolled steel sheet). Examples of the elastic body of the elastic body part <NUM> include various rubber materials. The various rubber materials are, for example, synthetic rubber such as nitrile rubber (NBR), hydrogenated nitrile rubber (H-NBR), acrylic rubber (ACM), and fluororubber (FKM). The reinforcing ring <NUM> is manufactured by press working or forging, for example, and the elastic body part <NUM> is molded with a mold by cross-linking (vulcanization). During the cross-linking, the reinforcing ring <NUM> is placed in the mold, the elastic body part <NUM> is bonded to the reinforcing ring <NUM> by cross-linking bonding, and the elastic body part <NUM> is integrally molded with the reinforcing ring <NUM>.

Next, operation of the sealing device <NUM> having the above-described configuration will be described. <FIG> is a view for illustrating the sealing device <NUM> in a state of being attached to a transaxle <NUM> that is an example of a component to which the sealing device is applied, and a partial enlarged cross-sectional view along the axis line x enlargedly illustrating the vicinity of the sealing device <NUM> in the transaxle <NUM>. Note that <FIG> illustrates a state where the sealing device <NUM> is attached to a desired position of the transaxle <NUM> (hereinafter referred to as an "initial state"). In other words, the sealing device <NUM> is attached to the transaxle <NUM> in such a manner that a part of the side lip <NUM> on the distal end edge 22b side is in contact with a sliding surface <NUM> of an annular deflector <NUM> by the desired seal width δ, the deflector <NUM> being fixed to an axle <NUM> as an output shaft of the differential mechanism (not illustrated) of the transaxle <NUM>. The transaxle <NUM> is a well-known transaxle (see <FIG>), and a detailed description of the configuration is omitted herein. Note that the deflector <NUM> may be formed by a member separate from the axle <NUM>, or the deflector <NUM> may be formed by forming a part of the axle <NUM> to be annularly projected toward the outer periphery side.

As illustrated in <FIG>, the sealing device <NUM> is fitted to a through-hole <NUM> formed in a housing <NUM> of the transaxle <NUM>. The axle <NUM> is rotatably inserted through the through-hole <NUM>. Note that the transaxle <NUM> is provided with two through-holes and two axles for right and left wheels, the through-holes and the axles corresponding to respective wheels have similar configurations, respectively, and the through-hole <NUM> and the axle <NUM> correspond to each of the right and left wheels, respectively.

In the through-hole <NUM> in the housing <NUM>, a space between an outer peripheral surface 51a of the axle <NUM> and an inner peripheral surface 55a of the through-hole <NUM> is sealed by the sealing device <NUM>. Specifically, the sealing device <NUM> is fitted to the through-hole <NUM>, the gasket part <NUM> of the elastic body part <NUM> is compressed between the cylindrical part <NUM> of the reinforcing ring <NUM> and the inner peripheral surface 55a of the through-hole <NUM> so that the gasket part <NUM> is in close contact with the inner peripheral surface 55a of the through-hole <NUM>, thereby sealing between the sealing device <NUM> and the through-hole <NUM> on the outer periphery side. The lip distal end portion <NUM> of the seal lip <NUM> of the elastic body part <NUM> is in contact with the outer peripheral surface 51a of the axle <NUM> so that the axle <NUM> is slidable, thereby sealing between the sealing device <NUM> and the axle <NUM> on the inner periphery side. Thus, the lubricant stored in the housing <NUM> is prevented from leaking out to the outside.

A distal end edge of the dust lip <NUM> is in contact with the outer peripheral surface 51a of the axle <NUM> in such a manner that the axle <NUM> is slidable, thereby preventing foreign matter from entering into the housing <NUM> from the outside. The dust lip <NUM> may not be in contact with the axle <NUM>. The side lip <NUM> is in contact with the sliding surface <NUM> of the deflector <NUM>, in the range of the seal width δ of the part of the inner peripheral surface 22a on the distal end edge 22b side, thereby preventing the foreign matter from entering into the housing <NUM> from the outside. Specifically, in the initial state, the part of the side lip <NUM> on the distal end edge 22b side is partially curved or is elastically deformed, and the inner peripheral surface 22a is in contact with the sliding surface <NUM> of the deflector <NUM> in the range of the seal width δ from the distal end edge 22b.

As described above, the circumferential groove <NUM> and the axial groove <NUM> are formed within the range of the seal width δ. The circumferential groove <NUM> and the axial groove <NUM> extend in the portion of the inner peripheral surface 22a of the side lip <NUM> that is in contact with the sliding surface <NUM> of the deflector <NUM> in the usage state. In other words, a part of the pluralities of the circumferential grooves <NUM> and the axial grooves <NUM> are in contact with (or face) the sliding surface <NUM> of the deflector <NUM> and each forms a space (a channel) between the sliding surface <NUM> of the deflector <NUM> and the inner peripheral surface 22a of the side lip <NUM> that is in contact with the sliding surface <NUM>.

Grease as a lubricant is applied to the inner peripheral surface 22a of the side lip <NUM> to reduce a sliding resistance between the side lip <NUM> and the deflector <NUM>. The grease is applied to an area of the seal width δ and an area on the inner side of the area of the seal width δ in the inner peripheral surface 22a of the side lip <NUM>. More specifically, the grease is applied to at least a zone where the circumferential grooves <NUM> and the axial grooves <NUM> are formed in the area on the inner side of the area of the seal width δ, as well as to the area of the seal width δ. In other words, the grease is present in the circumferential grooves <NUM> and the axial grooves <NUM>.

In response to rotation of the axle <NUM>, the deflector <NUM> rotates and the sliding surface <NUM> of the deflector <NUM> slides over the inner peripheral surface 22a of the side lip <NUM>. The grease applied to the area of the seal width δ is suctioned to the outer side by the sliding surface <NUM> of the deflector <NUM>. In the sealing device <NUM> according to the present embodiment, the circumferential grooves <NUM> and the axial grooves <NUM> are formed, as described above, in the inner peripheral surface 22a of the side lip <NUM>, at least one of the circumferential grooves <NUM> is at least partially formed in the zone of the seal width δ, and at least part of the axial grooves <NUM> enters the zone of the seal width. Thus, even if the grease on the inner peripheral surface 22a of the side lip <NUM> in the zone of the seal width δ is suctioned out by the rotation of the deflector <NUM>, the grease in the axial grooves <NUM>, the grease in the circumferential grooves <NUM>, and the grease applied to the inner peripheral surface 22a of the side lip <NUM> are supplied, as indicated by dashed arrow lines P in <FIG>, to the zone of the seal width δ through the axial groove <NUM>. This, even if the grease on the inner peripheral surface 22a of the side lip <NUM> in the zone of the seal width δ is suctioned out by the rotation of the deflector <NUM>, enables the supply of the grease applied to the inner peripheral surface 22a to the inner peripheral surface 22a of the side lip <NUM> in the zone of the seal width δ through the circumferential grooves <NUM> and the axial grooves <NUM>. This can inhibit a reduction in amount of the grease on the inner peripheral surface 22a of the side lip <NUM> in the zone of the seal width δ.

In the transaxle <NUM>, the axle <NUM> may be displaced inwardly in the direction of the axis line x so that the sliding surface <NUM> of the deflector <NUM> may be displaced in the direction of the axis line x, or the axle <NUM> may be inclined with respect to the axis line x so that the sliding surface <NUM> of the deflector <NUM> may be inclined, due to dimensional tolerance and assembly errors of each configuration. When the transaxle <NUM> is operated, the axle <NUM> may be displaced in the direction of the axis line x or displaced diagonally with respect to the axis line x due to the gap between respective configurations. If such a displacement (looseness) occurs, the side lip <NUM> vibrates. Vibrations from the side lip <NUM> facilitate movement of the grease to the zone of the seal width δ through the circumferential grooves <NUM> and the axial grooves <NUM>. Thus, for a component with a substantial degree of looseness, such as a differential mechanism, to which the sealing device is attached, the circumferential grooves <NUM> and the axial grooves <NUM> of the side lip <NUM> work effectively.

In this way, the sealing device <NUM> according to the first embodiment of the present invention is capable of inhibiting a reduction in amount of lubricant between the side lip <NUM> and the deflector <NUM>.

The sealing device <NUM> can, as described above, inhibit a reduction in the amount of the grease on the inner peripheral surface 22a of the side lip <NUM> in the area of the seal width δ and keep lubrication between the side lip <NUM> and the deflector <NUM> within the seal width δ in a state that the grease is in at the start of use of the sealing device or in a state close to the state that the grease is in at the start of use of the sealing device. Thus, the sealing device can inhibit wear on the side lip <NUM> and weakening by heat generation and inhibit a reduction in sealing performance of the side lip <NUM> against foreign matter.

Next, a sealing device <NUM> according to a second embodiment of the present invention will be described. <FIG> is a cross-sectional view taken along the axis line x for illustrating a schematic configuration of the sealing device <NUM> according to the second embodiment of the present invention. The sealing device <NUM> according to the second embodiment of the present invention differs in axial groove structure from the sealing device <NUM> described above according to the first embodiment of the present invention. Hereinafter, components of the sealing device <NUM> according to the second embodiment of the present invention that are identical or similar in function to those of the sealing device <NUM> according to the first embodiment of the present invention are assigned the same reference signs, and descriptions thereof are omitted. Parts that differ between the sealing devices will be described.

The sealing device <NUM> has at least one axial groove <NUM> that differs from the axial groove <NUM> of the sealing device <NUM> described above in an inner peripheral surface 22a of a side lip <NUM>. In the present embodiment, the sealing device <NUM> has a plurality of the axial grooves <NUM>. <FIG> is an enlarged view illustrating a portion of the inner peripheral surface 22a of the side lip <NUM> where circumferential grooves <NUM> and the axial grooves <NUM> are formed, the inner peripheral surface 22a being viewed in the radial direction. As illustrated in <FIG> and <FIG>, the axial grooves <NUM> are grooves recessed from the inner peripheral surface 22a, extending in the inner peripheral surface 22a diagonally with respect to the axis line x. Specifically, the axial grooves <NUM> are diagonal with respect to the axis line x toward a rotation direction r of the axle <NUM>. In other words, the axial grooves <NUM> extend diagonally toward the rotation direction from the inner side to the outer side. If the axle <NUM> rotates in both a forward direction and a reverse direction, the rotation direction r is the forward rotation direction and the axial grooves <NUM> extend diagonally with respect to the axis line x toward the forward rotation direction of the axle <NUM>. The axial grooves <NUM> may extend diagonally with respect to the axis line x toward the reverse rotation direction of the axle <NUM>.

In a similar way to the axial grooves <NUM>, the axial grooves <NUM> are arranged at equal or substantially equal intervals in the circumferential direction in the inner peripheral surface 22a. The axial grooves <NUM> are connected or intersect with the circumferential grooves <NUM> and extend across, as illustrated in <FIG> and <FIG>, between the circumferential groove <NUM> at an innermost place and the circumferential groove <NUM> at an outermost place, for example. In an example illustrated in the figures, the axial grooves <NUM> reach and end at the circumferential groove <NUM> at the outermost place. However, the axial grooves <NUM> may penetrate through the circumferential groove <NUM> at the outermost place. Similarly, in the illustrated example, the axial grooves <NUM> reach and end at the circumferential groove <NUM> at the innermost place. The axial grooves <NUM> may penetrate through the circumferential groove <NUM> at the innermost place. The axial grooves <NUM> may not extend across between the circumferential groove <NUM> at the innermost place and the circumferential groove <NUM> at the outermost place but may each extend across between at least two of the adjacent circumferential grooves <NUM>. However, in this case, the axial grooves <NUM> each extend such that the circumferential groove <NUM> at the innermost place communicates with the circumferential groove <NUM> at the outermost place through part or all of the axial grooves <NUM>. In the inner peripheral surface 22a, in a similar way to the axial grooves <NUM> described above, both or one of the circumferential grooves <NUM> and the axial grooves <NUM> are at least partially formed within a range of a seal width δ. The grooves <NUM> and <NUM> are also formed in an area on the inner side of the seal width δ. The axial grooves <NUM> may be formed in the area on the inner side of the seal width δ until a root of the side lip <NUM> or until a midway portion through the side lip <NUM>. The axial grooves <NUM> do not reach a distal end edge 22b of the side lip <NUM>.

In the sealing device <NUM> in the usage state, the circumferential grooves <NUM> and the axial grooves <NUM> work and produce effects in a similar way to the circumferential grooves <NUM> and the axial grooves <NUM> of the sealing device <NUM>. Since the axial grooves <NUM> extend diagonally with respect to the axis line x in particular, the grease is readily supplied toward the distal end edge <NUM> of the side lip <NUM> through the axial grooves <NUM> in response to rotation of the axle <NUM>. In other words, when the axle <NUM> rotates, the axial grooves <NUM> act as screw grooves for the grease.

In this way, the sealing device <NUM> according to the second embodiment of the present invention is capable of inhibiting a reduction in amount of lubricant between the side lip <NUM> and the deflector <NUM>.

Next, a modified example of the axial groove in the sealing device <NUM> according to the second embodiment of the present invention will be described. As illustrated in <FIG>, the sealing device <NUM> may have an axial groove group <NUM> that includes an axial groove <NUM> for forward rotation and an axial groove <NUM> for reverse rotation instead of the axial groove <NUM> in the inner peripheral surface 22a of the side lip <NUM>. In a similar way to the above-described axial groove <NUM>, the axial groove <NUM> for forward rotation is a groove recessed from the inner peripheral surface 22a of the side lip <NUM>, extending diagonally with respect to the axis line x toward the forward rotation direction of the axle <NUM>. The axial groove <NUM> for reverse rotation is a groove recessed from the inner peripheral surface 22a of the side lip <NUM>, extending diagonally to a side opposite the axial groove <NUM>, i.e., extending diagonally with respect to the axis line x toward the reverse rotation direction of the axle <NUM>.

In the axial groove group <NUM>, the axial groove <NUM> for forward rotation and the axial groove <NUM> for reverse rotation are disposed so as to be symmetric or substantially symmetric about a line. The axial groove group <NUM> includes a plurality of the axial grooves <NUM> for forward rotation and the axial grooves <NUM> for reverse rotation as many as the axial grooves <NUM> for forward rotation. In the axial groove group <NUM>, the axial grooves <NUM> and the axial grooves <NUM> are formed at equal or substantially equal intervals in the inner peripheral surface 22a of the side lip <NUM>, respectively. In the axial groove group <NUM>, the axial grooves <NUM> and the axial grooves <NUM> may not be formed at equal intervals in the inner peripheral surface 22a of the side lip <NUM>, respectively. In the axial groove group <NUM>, only one axial groove <NUM> for forward rotation and only one axial groove <NUM> for reverse rotation may be formed.

The axial groove group <NUM> formed may be only one, or a plurality of the axial groove groups <NUM> may be formed. If a plurality of the axial groove groups <NUM> are formed, the axial groove groups <NUM> are formed at equal or substantially equal intervals in the inner peripheral surface 22a of the side lip <NUM>. The axial groove groups <NUM> may not be formed at equal intervals in the inner peripheral surface 22a of the side lip <NUM>. In an example illustrated in the figure, in the axial groove group <NUM>, the axial grooves <NUM> for forward rotation are disposed on a forward rotation direction side of the axial grooves <NUM> for reverse rotation but may be disposed conversely, i.e., the axial grooves <NUM> for forward rotation may be disposed on a reverse rotation direction side of the axial grooves <NUM> for reverse rotation.

The axial groove group of this modified example in the usage state works in a similar way to the axial grooves <NUM> of the sealing device <NUM> described above. In particular, when the axle <NUM> rotates in the forward direction, in response to the rotation of the axle <NUM>, the grease is readily supplied toward the distal end edge <NUM> of the side lip <NUM> through the axial grooves <NUM> for forward rotation. On the other hand, when the axle <NUM> rotates in the reverse direction, in response to the rotation of the axle <NUM>, the grease is readily supplied toward the distal end edge <NUM> of the side lip <NUM> through the axial grooves <NUM> for reverse rotation.

Next, a sealing device <NUM> according to a third embodiment of the present invention will be described. <FIG> is a cross-sectional view taken along the axis line x for illustrating a schematic configuration of the sealing device <NUM> according to the third embodiment of the present invention. The sealing device <NUM> according to the third embodiment of the present invention differs in axial groove structure from the sealing device <NUM> described above according to the first embodiment of the present invention. Hereinafter, components of the sealing device <NUM> according to the third embodiment of the present invention that are identical or similar in function to those of the sealing device <NUM> according to the first embodiment of the present invention are assigned the same reference signs, and descriptions thereof are omitted. Parts that differ between the sealing devices will be described.

The sealing device <NUM> has at least one axial groove <NUM> that differs from the axial groove <NUM> of the sealing device <NUM> described above in an inner peripheral surface 22a of a side lip <NUM>. In the present embodiment, the sealing device <NUM> has a plurality of the axial grooves <NUM>. <FIG> is an enlarged view illustrating a portion of the inner peripheral surface 22a of the side lip <NUM> where circumferential grooves <NUM> and the axial grooves <NUM> are formed, the inner peripheral surface 22a being viewed in the radial direction. <FIG> is an enlarged view illustrating the axial groove <NUM>. As illustrated in <FIG>, the axial grooves <NUM> are grooves recessed from the inner peripheral surface 22a. A circumferential width of an end portion of the axial groove <NUM> on the outer side (an outer side end portion 46a) is smaller than a circumferential width of an end portion of the axial groove <NUM> on the inner side (an inner side end portion 46b). The outer side end portion 46a is a portion where the axial groove <NUM> connects to the circumferential groove <NUM> on the outer side, and the inner side end portion 46b is a portion where the axial groove <NUM> connects to the circumferential groove <NUM> on the inner side.

The axial groove <NUM> is formed between the circumferential grooves <NUM> adjacent to each other. One or a plurality of the axial grooves <NUM> are formed in every space between the circumferential grooves <NUM> adjacent to each other. If a plurality of the axial grooves <NUM> are formed in every space between the circumferential grooves <NUM> adjacent to each other, the axial grooves <NUM> are arranged at equal or substantially equal intervals in the circumferential direction in the inner peripheral surface 22a. The axial grooves <NUM> may not be arranged at equal intervals in the circumferential direction in the inner peripheral surface 22a. The circumferential grooves <NUM> and the axial grooves <NUM> are formed in the inner peripheral surface 22a such that both or one of the circumferential groove <NUM> and at least one of the axial grooves <NUM> are at least partially positioned within a range of a seal width δ. The axial grooves <NUM> do not reach a distal end edge 22b of the side lip <NUM>.

In the sealing device <NUM> in the usage state, the circumferential grooves <NUM> and the axial grooves <NUM> work and produce effects in a similar way to the circumferential grooves <NUM> and the axial grooves <NUM> of the sealing device <NUM>. Since the axial grooves <NUM> each have a tapered shape from the inner side to the outer side in particular, the grease is readily supplied from the inner side to the outer side, i.e., toward the distal end edge <NUM> of the side lip <NUM>, through the axial grooves <NUM>. On the other hand, the entry of foreign matter such as muddy water, rainwater, and dust into the housing from the outside to the inner side through the axial grooves <NUM> is difficult.

In this way, the sealing device <NUM> according to the third embodiment of the present invention is capable of inhibiting a reduction in amount of lubricant between the side lip <NUM> and the deflector <NUM>. The sealing device is also capable of hindering the entry of foreign matter into the inside from the outside through the axial grooves <NUM>.

Although the embodiments of the present invention have been described above, the present invention is not limited to the sealing devices <NUM> to <NUM> according to the embodiments of the present invention, and includes any modes falling within the scope of the claims of the present invention. Respective configurations may be appropriately selectively combined to solve at least part of the above-described problems and achieve at least part of the above-described effects. For example, in the above-described embodiments, the shape, material, arrangement, size and the like of each component can be appropriately changed according to a specific use mode of the present invention.

Claim 1:
A sealing device (<NUM>; <NUM>; <NUM>) for sealing between a through-hole (<NUM>) and a shaft (<NUM>) inserted through the through-hole (<NUM>), the through-hole (<NUM>) and the shaft (<NUM>) rotating relative to each other, comprising:
a reinforcing ring (<NUM>) having an annular shape around an axis line (x); and
an elastic body part (<NUM>) formed from an elastic body, the elastic body part (<NUM>) being attached to the reinforcing ring (<NUM>) and having an annular shape around the axis line (x),
wherein the elastic body part (<NUM>) includes a seal lip (<NUM>) having an annular shape, the seal lip (<NUM>) contacting the shaft (<NUM>) such that the shaft (<NUM>) is slidable; and a side lip (<NUM>) having an annular shape, wherein
the side lip (<NUM>) is provided on an atmosphere side (a) of the seal lip (<NUM>) and extends toward the atmosphere side (a),
a part of the side lip (<NUM>) on a distal end edge (22b) side is configured to be in contact with a sliding surface (<NUM>) perpendicular to the axis line (x),
characterised in that
in a surface (22a) of the side lip (<NUM>) on an inner periphery side, at least one circumferential groove (<NUM>) that is a groove having an annular shape around the axis line (x) is provided and at least one axial groove (<NUM>; <NUM>; <NUM>, <NUM>; <NUM>) that is a groove extending along a direction of the axis line (x) is provided, and
the circumferential groove (<NUM>) and the axial groove (<NUM>; <NUM>; <NUM>, <NUM>; <NUM>) are connected with each other.