Patent Description:
Conventionally, among sealing devices, a sealing device has been known which is used for a rotating shaft of a construction machine, such as a power shovel or an arm crane, for example. Such a sealing device is sometimes provided with a metal protective ring fitted around a lip portion from the exterior side so as to prevent collision of foreign matter, such as stones, with the lip portion from the outside. Note that as a sealing device, there is disclosed the one that has a second metal ring fitted on the inner peripheral surface of an interior surface adhesion portion on the inner periphery side of a metal ring of an oil seal body with a predetermined fitting allowance, from one side in the axial direction (for example, see Patent Literature <NUM>).

Patent Literature <NUM>: <CIT>
<CIT> discloses a sealing device according to the preamble of claim <NUM>.

Further sealing devices are known from <CIT> and <CIT>.

A protective ring squashes a portion on the inner periphery side of an elastic portion that is provided around a tubular portion of a reinforcement ring in a sealing device. The protective ring is held on the inner periphery side of the tubular portion with a repulsive force (i.e., a frictional force) of rubber generated as the elastic portion provided on the inner periphery side of the tubular portion is squashed.

However, in a conventional sealing device with a protective ring, when a greater-than-expected external force is applied to the protective ring, the protective ring may be displaced from a predetermined position.

The present invention has been made in view of the foregoing problem, and it is an object of the present invention to suppress the displacement of a protective ring in a sealing device.

The object of the present invention is achieved with a sealing device according to claim <NUM>. A further advantageous development of the invention is defined by claim <NUM>.

With a sealing device according to the present invention, the displacement of a protective ring can be suppressed.

Hereinafter, a sealing device according to an embodiment of the present invention will be described with reference to the drawings.

Hereinafter, for convenience's sake of description, the direction of an arrow a (see <FIG>) along the direction of an axis x shall be assumed as the exterior side, and the direction of an arrow b (see <FIG>) along the direction of the axis x shall be assumed as the interior side. In addition, regarding the direction perpendicular to the axis x (hereinafter also referred to as a "radial direction"), a direction away from the axis x (i.e., the direction of an arrow c in <FIG>) shall be assumed as the outer periphery side, and a direction toward the axis x (i.e., the direction of an arrow d in <FIG>) shall be assumed as the inner periphery side.

<FIG> is a sectional view of a cross-section along the axis x for illustrating the schematic configuration of a sealing device <NUM> according to an embodiment of the present invention. In addition, <FIG> is an enlarged sectional view along the axis x for illustrating an engagement portion of the sealing device <NUM>. The configuration of the sealing device <NUM> according to the present embodiment will be described with reference to <FIG>.

As illustrated in <FIG>, the sealing device <NUM> according to the present embodiment includes an annular reinforcement ring <NUM> around the axis x, an annular elastic portion <NUM> around the axis x that is formed of an elastic material and includes a lip portion <NUM>, and an annular protective ring <NUM> around the axis x that is fitted on an inner periphery side d of the reinforcement ring <NUM>. The elastic portion <NUM> is attached to the reinforcement ring <NUM>. The reinforcement ring <NUM> includes a reinforcement ring tubular portion <NUM> formed in a tubular shape around the axis x. The protective ring <NUM> includes a protective ring tubular portion <NUM> formed in a tubular shape around the axis x, and an engagement portion <NUM> that is provided on an outer peripheral surface <NUM> of the protective ring tubular portion <NUM> and is adapted to engage with the inner periphery side d of the reinforcement ring <NUM>. Hereinafter, the structure of the sealing device <NUM> will be specifically described.

The reinforcement ring <NUM> is an annular metal member having the axis x as the center or the approximate center as illustrated in <FIG>. Examples of a metal member used for the reinforcement ring <NUM> include stainless steel and SPCC (cold rolled steel sheet). The reinforcement ring <NUM> is produced by subjecting such a metal member to press work or forging, for example. The reinforcement ring <NUM> includes the reinforcement ring tubular portion <NUM> that is a tubular portion having a cylindrical or approximately cylindrical shape and extending in the direction of the axis x, and a reinforcement ring disk portion <NUM> that is a hollow disk-like portion extending from one side of the reinforcement ring tubular portion <NUM>, that is, from an end portion on an interior side b to the inner periphery side d, for example.

The reinforcement ring tubular portion <NUM> is formed to allow the sealing device <NUM> to be fitted to the inner peripheral surface of a through-hole in an attachment target (both not illustrated). The reinforcement ring tubular portion <NUM> is fittable to the inner peripheral surface of the through-hole by contacting it via the elastic portion <NUM>. The reinforcement ring tubular portion <NUM> may be shaped such that its middle portion has a conical ring portion (not illustrated) formed thereon. Alternatively, the reinforcement ring tubular portion <NUM> may be fittable to the inner peripheral surface of the through-hole by partially and directly contacting it. The reinforcement ring tubular portion <NUM> is, when the sealing device <NUM> is fitted to the inner peripheral surface of the through-hole, fitted onto the inner peripheral surface of the through-hole such that the axis x of the sealing device <NUM> coincides with the axis x of a rotating shaft (not illustrated).

The reinforcement ring <NUM> has the elastic portion <NUM> attached thereto such that the elastic portion <NUM> covers the reinforcement ring <NUM> from the interior side (i.e., the direction of the arrow b) and the outer periphery side (i.e., the direction of the arrow c). That is, the reinforcement ring <NUM> reinforces the elastic portion <NUM>.

The elastic portion <NUM> is attached to the reinforcement ring <NUM> as described above. The elastic portion <NUM> is formed integrally with the reinforcement ring <NUM> so as to cover the reinforcement ring <NUM>. Examples of the elastic material for the elastic portion <NUM> include a variety of rubber materials. Examples of a variety of rubber materials include synthetic rubber, such as nitrile rubber (NBR), hydrogenated nitrile rubber (H-NBR), acrylic rubber (ACM), and fluorocarbon rubber (FKM). The elastic portion <NUM> is molded through cross-linking (or vulcanization) molding using a mold. During such cross-linking molding, the reinforcement ring <NUM> is disposed in the mold. The elastic portion <NUM> is bonded to the reinforcement ring <NUM> through cross-linking bonding, so that the elastic portion <NUM> and the reinforcement ring <NUM> are integrally molded. The elastic portion <NUM> includes a base portion <NUM>, a gasket portion <NUM>, a cover portion <NUM>, the lip portion <NUM>, and an inner peripheral surface <NUM>.

The base portion <NUM> is located near an end portion of the reinforcement ring disk portion <NUM> on the inner periphery side (i.e., the direction of the arrow d). The base portion <NUM> slidably supports a lip tip end portion <NUM> of the lip portion <NUM> while pressing the lip tip end portion <NUM> against the outer peripheral surface of the rotating shaft. The reinforcement ring disk portion <NUM> is partially embedded in the base portion <NUM>. The cover portion <NUM> is attached to the reinforcement ring disk portion <NUM> from the exterior side a as described above, and is provided such that it faces the exterior side a while having an annular shape around the axis x. The base portion <NUM> includes the inner peripheral surface <NUM> that is an annular surface located on the inner periphery side of the elastic portion <NUM>.

The gasket portion <NUM> is a portion of the elastic portion <NUM> covering the reinforcement ring tubular portion <NUM> of the reinforcement ring <NUM> from the outer periphery side c and the inner periphery side d. The gasket portion <NUM> has an outside diameter that is equal to or slightly greater than the inside diameter of the inner peripheral surface of the through-hole. Therefore, when the sealing device <NUM> is fitted to the inner peripheral surface of the through-hole, the gasket portion <NUM> is radially compressed between the reinforcement ring tubular portion <NUM> of the reinforcement ring <NUM> and the through-hole, and thus seals a gap between the inner peripheral surface of the through-hole and the reinforcement ring tubular portion <NUM> of the reinforcement ring <NUM>.

As the gasket portion <NUM> seals the gap between the inner peripheral surface of the through-hole and the reinforcement ring tubular portion of the reinforcement ring, the annular gap between the inner peripheral surface of the through-hole and the rotating shaft is sealed by the sealing device <NUM>. Note that the gasket portion <NUM> is not limited to the one that entirely covers the outer periphery side c and the inner periphery side d of the reinforcement ring tubular portion <NUM> as illustrated in <FIG>. For example, the gasket portion <NUM> may be the one that partially covers the outer periphery side c and the inner periphery side d of the reinforcement ring tubular portion <NUM>.

The cover portion <NUM> is a portion attached to the reinforcement ring disk portion <NUM> from the exterior side (i.e., the direction of the arrow a) at a position between the base portion <NUM> and the gasket portion <NUM>.

The lip portion <NUM> of the elastic portion <NUM> includes, at its tip end extending from the base portion <NUM> along the axis x, the lip tip end portion <NUM> that is formed to allow the outer peripheral surface of the rotating shaft (not illustrated) to be slidable thereon. The lip tip end portion <NUM> protrudes to the inner periphery side (i.e., the direction of the arrow d). The lip portion <NUM> has a conical tubular shape such that its diameter decreases toward the inner periphery side d in the direction toward the exterior side (i.e., the direction of the arrow a) along the direction of the axis x. That is, the lip portion <NUM> extends diagonally with respect to the axis x from the base portion <NUM> to a lip contact end <NUM> of the lip tip end portion <NUM> on the exterior side (i.e., the direction of the arrow a) and the inner periphery side (i.e., the direction of the arrow d) as viewed in cross-section along the axis x (hereinafter also referred to as "cross-section"). The lip portion <NUM> is provided with a recessed part on the outer periphery side (i.e., the direction of the arrow c) opposite to the lip tip end portion <NUM>. The recessed part has fitted therein a garter spring <NUM>, which is an annular elastic member, as a tightening force provision member.

The lip tip end portion <NUM> is an annular portion having a cross-section in a wedge shape protruding to the inner periphery side (i.e., the direction of the arrow d). The lip tip end portion <NUM> has the lip contact end <NUM> adapted to slidably contact the outer peripheral surface of the rotating shaft.

The garter spring <NUM> is a metal spring member, for example, and is adapted to radially urge the lip tip end portion <NUM> to the inner periphery side (i.e., the direction of the arrow d) and provide a tightening force with a predetermined magnitude that presses the lip tip end portion <NUM> against the outer peripheral surface of the rotating shaft. Note that the garter spring <NUM> is not limited to the one made of metal and may be the one made of a variety of other materials, such as resin, as long as the garter spring <NUM> can provide a tightening force.

The protective ring <NUM> is an annular metal member having the axis x as the center or the approximate center as illustrated in <FIG>. Examples of a metal member used for the protective ring <NUM> include stainless steel and SPCC (cold rolled steel sheet). The protective ring <NUM> is produced by subjecting such a metal member to press work or forging, for example. The protective ring <NUM> includes the protective ring tubular portion <NUM>, a protective ring disk portion <NUM>, and the engagement portion <NUM>. The protective ring tubular portion <NUM> of the protective ring <NUM> is fitted to the inner periphery side d of the reinforcement ring tubular portion <NUM> of the reinforcement ring <NUM> from the other side (i.e., in the direction from the exterior side a to the interior side b).

The protective ring tubular portion <NUM> is a tubular portion having a cylindrical or approximately cylindrical shape and extending in the direction of the axis x, for example. The protective ring tubular portion <NUM> is formed such that it can be fitted to an inner peripheral surface <NUM> of the reinforcement ring tubular portion <NUM> in the sealing device <NUM>, more specifically, to an inner peripheral surface <NUM> of the gasket portion <NUM> of the elastic portion <NUM> by contacting the inner peripheral surface. The protective ring tubular portion <NUM> may be shaped such that its middle portion has a conical ring portion (not illustrated) formed thereon. Alternatively, the protective ring tubular portion <NUM> may be fitted to the inner peripheral surface <NUM> of the reinforcement ring tubular portion <NUM> by at least partially and directly contacting the inner peripheral surface <NUM>. The protective ring tubular portion <NUM> is, when the sealing device <NUM> is fitted to the inner peripheral surface of the through-hole, fitted onto the inner peripheral surface <NUM> of the reinforcement ring tubular portion <NUM> such that the axis x of the sealing device <NUM> coincides with the axis x of the protective ring <NUM>.

The protective ring disk portion <NUM> is a hollow disk-like portion extending from the other side of the protective ring tubular portion <NUM>, that is, from an end portion on the exterior side a to the inner periphery side d. The protective ring disk portion <NUM> is arranged such that it faces the exterior side a when the protective ring <NUM> is attached to the inner peripheral surface <NUM> of the reinforcement ring tubular portion <NUM> of the reinforcement ring <NUM>.

The engagement portion <NUM> is provided on the protective ring tubular portion <NUM> of the protective ring <NUM> in the sealing device <NUM>. The engagement portion <NUM> is provided on the outer peripheral surface <NUM> of the protective ring tubular portion <NUM> as a surface to be fitted to the elastic portion <NUM>, specifically, the inner peripheral surface <NUM> that is a portion of the gasket portion <NUM> on the inner periphery side. The engagement portion <NUM> is formed in a recessed groove shape on the outer peripheral surface <NUM> of the protective ring tubular portion <NUM>, for example. The engagement portion <NUM> may be provided in an annular shape in the circumferential direction of the protective ring tubular portion <NUM> of the protective ring <NUM>. Alternatively, the engagement portion <NUM> may be provided at a plurality of positions in a scattered manner in the circumferential direction of the protective ring tubular portion <NUM> of the protective ring <NUM>.

The engagement portion <NUM> includes, on the outer peripheral surface <NUM> of the protective ring tubular portion <NUM>, an inclined surface <NUM> having a diameter that decreases in the direction from the exterior side a to the interior side b, and also includes, on the outer peripheral surface <NUM> of the protective ring tubular portion <NUM>, an upstanding wall portion <NUM> facing the other side, that is, the exterior side a. The upstanding wall portion <NUM> is provided upright so as to extend in the radial direction perpendicular to the direction of the axis x. That is, the upstanding wall portion <NUM> extends to a side opposite to the side along the direction from the interior side b to the exterior side a that is the direction in which the protective ring <NUM> would come off the sealing device <NUM> along the direction of the axis x.

Next, the function of the sealing device <NUM> with the aforementioned configuration will be described.

<FIG> is a sectional view of a cross-section along the axis for illustrating the schematic configuration of a sealing device as a reference example. As illustrated in <FIG>, a sealing device <NUM> according to the reference example does not include the engagement portion <NUM>, such as the one included in the sealing device <NUM>, in a protective ring tubular portion <NUM> of a protective ring <NUM>.

In the sealing device <NUM> according to the reference example with such a configuration, there may be a case where the protective ring <NUM> is displaced from a predetermined position when a greater-than-expected external force is applied to the protective ring <NUM>.

Meanwhile, in the sealing device <NUM> according to the present embodiment, as illustrated in <FIG>, the protective ring <NUM> is fitted to the inner periphery side d of the reinforcement ring tubular portion <NUM> from the exterior side a that is the other side in the direction of the axis x in the usage state of the sealing device <NUM>. Herein, the engagement portion <NUM> engages with the inner peripheral surface <NUM> provided on the inner periphery side of the gasket portion <NUM>.

In the usage state of the sealing device <NUM>, the engagement portion <NUM> of the protective ring <NUM> includes the upstanding wall portion <NUM> facing the other side, that is, the exterior side a on the outer peripheral surface <NUM> of the protective ring tubular portion <NUM>. The upstanding wall portion <NUM> is provided upright in the radial direction perpendicular to the direction of the axis x. Therefore, the upstanding wall portion <NUM> extends to a side opposite to the side along the direction from the interior side b to the exterior side a that is the direction in which the protective ring <NUM> would come off the sealing device <NUM> along the direction of the axis x.

As described above, according to the sealing device <NUM> with the engagement portion <NUM>, when a force acting toward the exterior side a is applied to the protective ring <NUM>, the upstanding wall portion <NUM> of the engagement portion <NUM> bites into the inner peripheral surface <NUM> of the gasket portion <NUM> of the elastic portion <NUM>. Therefore, the protective ring <NUM> becomes less likely to come off the sealing device <NUM>. Thus, according to the sealing device <NUM>, the displacement of the protective ring <NUM> can be suppressed.

Although an embodiment of the present invention has been described above, the present invention is not limited to the sealing device <NUM> according to the aforementioned embodiment, and includes all aspects encompassed by the claims of the present invention. In addition, the aforementioned configurations may be selectively combined as appropriate so as to achieve at least some of the aforementioned object and effects. For example, the shape, material, arrangement, size, and the like of each component in the aforementioned embodiment may be changed as appropriate depending on a specific usage pattern of the present invention.

For example, in the sealing device <NUM>, the upstanding wall portion <NUM> of the engagement portion <NUM> is not limited to the one that extends upward in the radial direction perpendicular to the direction of the axis x as illustrated in <FIG> as long as the upstanding wall portion <NUM> of the engagement portion <NUM> can bite into the inner peripheral surface <NUM> of the gasket portion <NUM> of the elastic portion <NUM>. The upstanding wall portion <NUM> may also be the one that extends upward to the exterior side a with respect to the radial direction, for example.

For example, in the sealing device <NUM>, the elastic portion <NUM> may include a dust lip that extends from the base portion <NUM> to the inner periphery side (i.e., the direction of the arrow d) and to the exterior side (i.e., the direction of the arrow a) in the direction of the axis x and that has a tip end portion with a diameter that decreases toward the inner periphery side d in the direction of the axis x.

Claim 1:
A sealing device (<NUM>) comprising:
an annular reinforcement ring (<NUM>) around an axis;
an annular elastic portion (<NUM>) around the axis, the annular elastic portion (<NUM>) being attached to the reinforcement ring (<NUM>), being formed of an elastic material, and including a lip portion (<NUM>); and
an annular protective ring (<NUM>) around the axis, the annular protective ring (<NUM>) being adapted to be fitted to an inner periphery side of the reinforcement ring (<NUM>), wherein
the reinforcement ring (<NUM>) includes a reinforcement ring tubular portion (<NUM>) formed in a tubular shape around the axis, and
the protective ring (<NUM>) includes a protective ring tubular portion (<NUM>) formed in a tubular shape around the axis, and an engagement portion (<NUM>) provided on an outer peripheral surface (<NUM>) of the protective ring tubular portion (<NUM>), the engagement portion (<NUM>) being adapted to engage with the inner periphery side of the reinforcement ring (<NUM>), wherein
the elastic portion (<NUM>) includes a gasket portion (<NUM>) attached to the reinforcement ring tubular portion (<NUM>),
the engagement portion (<NUM>) is adapted to engage with the gasket portion (<NUM>) on an inner periphery side of the reinforcement ring tubular portion (<NUM>),
the reinforcement ring (<NUM>) includes a reinforcement ring disk portion (<NUM>) extending from one end portion of the reinforcement ring tubular portion (<NUM>) in a direction of the axis toward an inner periphery side, and
the protective ring (<NUM>) is adapted to be fitted to the inner periphery side of the reinforcement ring tubular portion (<NUM>) from a side of another end portion of the reinforcement ring tubular portion (<NUM>) in the direction of the axis,
the sealing device (<NUM>) being characterized in that
the engagement portion (<NUM>) is formed in a recessed groove shape on the outer peripheral surface (<NUM>) of the protective ring tubular portion (<NUM>),
the engagement portion (<NUM>) includes an upstanding wall portion (<NUM>) on the outer peripheral surface (<NUM>) of the protective ring tubular portion (<NUM>), the upstanding wall portion (<NUM>) facing the side of the another end portion of the reinforcement tubular portion (<NUM>) when in the usage state of the sealing device (<NUM>), and
the upstanding wall portion (<NUM>) is configured to bite into an inner peripheral surface (<NUM>) of the gasket portion (<NUM>) when the sealing device (<NUM>) is in its usage state.