A dynamic seal provides for the return of captured lubricant to the lubricant side regardless of the direction of rotation between the seal and the shaft. The seal uses bi-directional pumping elements to facilitate the hydrodynamic pumping of the captured lubricant in response to relative rotation. The seal includes a valve portion that can change a pumping rate of particular pumping elements such that more lubricant is pumped toward the lubricant side than the non-lubricant side.

FIELD

The present disclosure relates to dynamic seals, and more particularly, to a dynamic seal having bi-directional pumping elements.

BACKGROUND

Rotary shaft seals are used in many industries, such as the automotive industry, and in many applications that can require a symmetrically functioning dynamic seal (i.e., the seal must function effectively in both directions of shaft rotation). For example, such seals are used on transmissions, pinions, gears, axles, etc. The seal typically is used to retain a fluid and has two separate sides. The fluid can be any fluid desired to be retained by the seal as dictated by the application within which the seal is utilized. The fluid can be a lubricant. By way of non-limiting example, the fluid can be oil, water, chemicals, slurries, and the like. The fluid being retained by the seal is hereinafter referred to collectively as “lubricant.” A first side of the seal is exposed to the air or outside environment and is referred to herein as the “non-lubricant side.” A second side of the seal is a sealed fluid side that is exposed to the lubricant and is used to retain the lubricant on the second side and is referred to herein as the “lubricant side.” The lubricant may, however, leak from the lubricant side to the non-lubricant side due to the interaction of a contact surface of the seal with the shaft. Pumping elements disposed on the contact surface of the seal can capture the leaked lubricant and hydro-dynamically pump the captured lubricant across the contact surface and back to the lubricant side due to relative rotation between the seal and the shaft about which the seal is disposed.

Typically, the pumping elements are helical channels that spiral around the shaft. For the pumping action to work in both rotational directions of the shaft, some channels spiral around the shaft in a first orientation and pump lubricant toward the lubricant side when the shaft rotates in a first direction, and some channels spiral around the shaft in a second orientation and pump lubricant toward the lubricant side when the shaft rotates in a second direction. Thus, for a particular direction of shaft rotation, only one set of channels actively pumps captured lubricant back to the lubricant side. The other set of channels, however, may also capture lubricant and pump the captured lubricant further toward the non-lubricant side. Thus, it would be advantageous to reduce or eliminate the propensity for one of the sets of channels to pump captured lubricant further toward the non-lubricant side while allowing the other set of channels to pump captured lubricant to the lubricant side regardless of the direction of shaft rotation.

SUMMARY

A dynamic seal according to the present teachings advantageously provides for the return of captured lubricant to the lubricant side regardless of the direction of the relative rotation between the seal and the shaft. The seal uses bi-directional pumping elements to facilitate the hydrodynamic pumping of the captured lubricant in response to the relative rotation. The seal has a valve portion that can change a pumping rate of particular pumping elements such that more lubricant is pumped toward the lubricant side than the non-lubricant side.

In one aspect of the present teachings, a bi-directional, dynamic seal has a lubricant side and a non-lubricant side. There is a sealing portion with an active surface communicating with the non-lubricant side and operable to engage with the shaft. A plurality of pumping elements extends along the active surface. The pumping elements capture lubricant and pump the captured lubricant to at least one of the lubricant side and the non-lubricant side due to relative rotation between the shaft and the pumping elements. A valve portion is displaceable relative to the active surface and is operable to engage with the shaft. Rotation of the shaft rotationally displaces the valve portion relative to the active surface such that the displaced valve portion changes a pumping rate of at least one of the pumping elements.

In another aspect of the present teachings, a bi-directional, dynamic seal has an annular body with a lubricant side, a non-lubricant side, a central opening within which a shaft can be disposed, and a sealing portion having an active surface engaging with and sealing against a shaft disposed in the central opening. There is a first set of pumping channels in the active surface which is operable to capture lubricant and pump captured lubricant toward the lubricant side when the shaft rotates in a first direction and toward the non-lubricant side when the shaft rotates in a second direction opposite to the first direction. A second set of pumping channels in the active surface is operable to capture lubricant and pump captured lubricant toward the non-lubricant side when the shaft rotates in the first direction and toward the lubricant side when the shaft rotates in the second direction. A valving member is moveable relative to the active surface. The valving member inhibits pumping of captured lubricant in the second set of channels when the shaft rotates in the first direction and inhibits pumping of captured lubricant in the first set of channels when the shaft rotates in the second direction.

A method according to the present teachings includes capturing lubricant with pumping elements extending along an active surface of the seal. The captured lubricant is pumped toward the lubricant side with a first set of pumping elements when the shaft rotates in a first direction. Captured lubricant is pumped toward the lubricant side with a second set of pumping elements when the shaft is rotated in a second direction differing from the first direction. The second set of pumping elements is different than the first set. The pumping rate of the second set of pumping elements is reduced when the shaft is rotated in the first direction such that a pumping rate of the first set of pumping elements is greater than a pumping rate of the second set of pumping elements. A pumping rate of the first set of pumping elements is reduced when the shaft rotates in the second direction such that a pumping rate of the second set of pumping elements is less than a pumping rate of the first set of pumping elements.

DETAILED DESCRIPTION

The following description of the preferred embodiments is merely exemplary in nature and is not intended to limit the invention, its application, or its uses. In describing the various teachings herein, reference indicia are used. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features (e.g.,22,122,222, etc.).

Referring toFIGS. 1 and 2, a symmetrically functioning prior art dynamic seal20is shown. The annularly shaped seal20is disposed in a fixed housing22in a manner which is well known in the art and engages a rotary shaft24. A lubricant side26and a non-lubricant side28of seal20generally segregate a first chamber30of fixed housing22from an exterior or a second chamber32of fixed housing22.

Seal20includes an annularly shaped body portion34mounted to an annular insert36. Body portion34includes a primary sealing portion38having an active surface40that directly engages and seals against shaft24. Body portion34also includes a secondary sealing portion42whose lip seals against shaft24. Body portion34also includes a peripheral leg44that extends around insert36and seals against fixed housing22due to compression between fixed housing22and insert36.

Primary and secondary sealing portions38,42form a central opening46within which shaft24is disposed. Primary sealing portion38can have more surface contact with shaft24than secondary sealing portion42. Active surface40engages shaft24and includes a plurality of pumping elements50,52. Pumping elements50,52can take the form of grooves, as shown, or ridges that extend radially inwardly from active surface40. A first set of pumping elements50extends curvalinearly in a first orientation as they extend axially away from lubricant side26. A second set of pumping elements52extends curvalinearly in a second orientation as they extend axially away from lubricant side26. Pumping elements50,52are operable to capture lubricant that leaks past lip54of primary sealing portion38and pump the captured lubricant back toward lubricant side26. The differing orientations of first and second pumping elements50,52allow the pumping elements to pump the captured lubricant back to lubricant side26regardless of the direction of rotation of shaft24. When shaft24rotates in a first direction, the first set of pumping elements50are operable to pump captured lubricant back toward lubricant side26, while second set of pumping elements52are operable to pump captured lubricant back toward lubricant side26when shaft24is rotating in a second direction. Thus, pumping elements50,52are bi-directional pumping elements.

Both sets of pumping elements50,52are not actively pumping captured lubricant back toward lubricant side26for a particular direction of rotation of shaft24. Rather, the non-active set of pumping elements can cause lubricant captured therein to be slung further toward non-lubricant side28, thus reducing the effectiveness of the pumping action of the active set of pumping elements. To reduce the adverse effect of the non-active set of pumping elements, a seal120according to present teachings utilizes a valving member to reduce the pumping rate of the non-active pumping elements and, in some cases, may seal off the non-active set of pumping elements such that they provide no pumping action when the shaft is rotating in a direction that does not correspond to those pumping elements being active, as described below.

Referring now toFIGS. 3 and 4, a first embodiment of a seal120according to the present teachings is shown. Seal120is similar to prior art seal20with the primary difference being the configuration of the pumping elements on the active face and the addition of a valving portion160. Valving portion160extends from body portion134between primary and secondary sealing portions138,142. Primary and secondary sealing portions138,142and valving portion160can be unitary and integrally formed with body portion134, such as by a direct molding process. Alternatively, as shown inFIG. 6, secondary sealing portion142′ and valving portion160′ of seal120′ can be unitary and integrally formed with body portion134′, while primary sealing portion138′ is separately formed. Primary sealing portion138′ can be formed, such as through a direct molding process, and bonded to body portion134′.

Referring now toFIGS. 3-4and7-8, primary sealing portion138includes a non-contacting body portion141and an active surface140that at least partially engages shaft24. Active surface140defines a seal lip154that engages shaft24at lubricant side26. Valve portion160extends from body portion134and is disposed in gap164between primary and secondary sealing portions138,142. Valving portion160includes a non-contacting body portion166and a contacting portion168that contacts shaft24. Preferably, a gap169is maintained between body portion166of valving portion160and body portion141of primary sealing portion138.

Pumping elements156of seal120are formed by features on both primary sealing portion138and valving portion160. Specifically, a plurality of recesses174are coined, cut, or otherwise formed into active surface140, while contacting portion168of valving portion160includes a plurality of teeth176, which are configured to nest within recesses174. Recesses174and teeth176can be generally truncated triangular in shape and radially disposed around shaft24and can form mating saw-tooth-like patterns, as shown inFIG. 4.

Each recess174includes a bottom178and a pair of sidewalls180a,bthat extend therefrom toward non-lubricant side28. Sidewalls180aextend in a first angular direction (orientation) from bottom178along active surface140, while sidewalls180bextend in a second angular direction (orientation) from bottom178along active surface140. The different angular directions provide pumping of captured lubricant toward lubricant side26, regardless of the direction of rotation of shaft24, as described below.

Each tooth176has a top182and a pair of sidewalls184a,bthat extend therefrom toward non-lubricant side28along contacting portion168. Sidewalls184aextend in the first angular direction (orientation) generally parallel with sidewalls180a, while sidewalls184bextend in the second angular direction (orientation), generally parallel with sidewalls180b.

When in a relaxed neutral state, teeth176are generally centered within recesses174such that the width Wabetween sidewalls180a,184ais generally the same as the width Wbbetween sidewalls180b,184b. The gaps between sidewalls180a,184aform a first plurality of pumping channels186a, while the gaps between sidewalls180b,184bform a second plurality of pumping channels186b. Pumping channels186aare operable to capture lubricant that leaks past seal lip154and direct it back to lubricant side26when shaft24rotates in a first direction. Pumping elements186bare operable to capture lubricant that leaks past seal lip154and direct it back to lubricant side26when shaft24rotates in a second direction opposite to that of the first direction. As a result, pumping channels186a,186bcan capture lubricant that leaks past seal lip154and direct it back to lubricant side26regardless of the direction of rotation of shaft24.

Seal lip154may engage shaft24to form a static dam that generally block channels186a,186bduring a static condition of shaft24and inhibits lubricant from leaking from lubricant side26to non-lubricant side28. When shaft24rotates, lubricant can leak toward non-lubricant side28and across seal lip154. Lubricant leakage across seal lip154could be uncontrolled or could be controlled by designing seal lip154to allow lubricant leakage at a predetermined leakage rate.

Seal120is designed to capture the lubricant that leaks across seal lip154and to pump the captured lubricant back into lubricant side26. Specifically, valving portion160and active surface140work in combination through the interaction of recesses174and teeth176to adjust the configuration of pumping channels186a,186bto provide a pumping action that directs the captured lubricant back into lubricant side26, as described below. As an alternative, as shown inFIG. 5, a seal120″ can be provided with recesses174″ and teeth176″ having curvalinear channels186a″ and186b″ to provide a pumping action that directs the captured lubricant back into lubricant side26.

To capture and pump the leaked lubricant back to lubricant side26, contacting portion168of valve portion160and active surface140of primary sealing portion138can engage shaft24and rotationally deflect relative to body portion134due to contact friction with shaft24as shaft24rotates. Valve portion160and active surface140are secured to rotationally fixed body portion134to elastically resist rotational deflection. Valve portion160may engage with active surface140to resist rotational deflection. Respective rotational deflections of valve portion160and active surface140may be designed/controlled to create relative rotational movement therebetween. The person skilled in the art will appreciate that the relative rotational movement is dependent on many inter-related design factors for primary sealing portion138and valve portion160, such as contact loads from shaft24, shaft surface friction, which can further depend on shaft speed and diameter, contact friction between valve portion160and active surface140, structural geometry, material rigidity, etc. The skilled person will further appreciate that any combination of these factors can be modified for a particular shaft and seal configuration to advantageously realize the benefits of the present teachings.

The relative rotational movement between valve portion160and active surface140may change the configuration of the pumping elements156on active surface140to advantageously alter the pumping rate. In some embodiments, for example, valve portion160can change the cross-sectional area of one or both of channels186a,186b. In some embodiments, valve portion160can inhibit or block one or both of channels186a,186b.

The dynamics of pumping lubricant back into lubricant side26depends on numerous factors, including a pumping rate of captured lubricant to lubricant side26and a pumping rate of captured lubricant to non-lubricant side28, hereinafter referred to as first pumping rate and second pumping rate, respectively. Preferably, a steady state operation is realized in which pumping elements156create a positive net pumping rate (i.e., first pumping rate is greater than second pumping rate) regardless of a rotational direction of shaft24. A benefit of such a construction is that the net positive pumping rate can generally prevent lubricant buildup on non-lubricant side28of seal120. In some embodiments, another benefit is provided by maintaining active surface140in a lubricated state by permitting some pumping elements156to draw lubricant maintained in first chamber30of housing22through active surface140while other pumping elements156simultaneously return lubricant to the lubricant side26to prevent lubricant buildup on non-lubricant side28. Maintaining active surface140in a lubricated state may increase durability and effectiveness of seal120. In some embodiments, another provided benefit is that pumping elements156may return lubricant that may leak into and accumulate on non-lubricant side28of seal120during a static condition of shaft24.

In operation, rotation of shaft24can cause valve portion160to rotate relative to active surface140and change the widths Wa, Wbof channels186a,186b, as shown inFIGS. 7 and 8. More particularly, when shaft24rotates in a first direction, as shown inFIG. 7A, sidewall184bof teeth176moves toward sidewall180bof recess174, thereby reducing the width Wb. Simultaneously, sidewalls184aof teeth176move away from sidewalls180aof recesses174, thereby increasing the width Watherebetween. This change in widths Wa, Wbalters the cross-sectional areas of channels186a,186b, thereby altering the pumping characteristics such that channels186b(having the smaller reduced width) have a reduced pumping rate, while channels186a(having the larger increased width) have a greater pumping rate. The net result is that for this first direction of rotation of shaft24, pumping channels186ahave a greater pumping rate than pumping channels186b. Therefore, a net positive pumping rate is achieved and the captured lubricant is returned to lubricant side26at a faster rate (by pumping channels186a) than lubricant is pumped toward non-lubricant side28(by pumping channels186b).

In some instances, as shown inFIG. 7B, the rotation of valving portion160relative to active surface140can be such that sidewalls184bof teeth176engage with sidewalls180bof recesses174, thereby reducing the width Wbtherebetween (and the associated cross-sectional area) essentially to zero while maximizing the width Wa(and the associated cross-sectional area) between sidewalls184a,180a. As a result, the pumping rate of channels186bcan be effectively reduced to zero, while the pumping rate of channels186ais maximized, thereby resulting in a further increase in the net positive pumping rate.

Referring now toFIGS. 8Aand B, the effects of rotation of shaft24in a second direction opposite the first direction is shown. In particular, valving portion160rotates relative to active surface140such that sidewalls184bmove away from sidewalls180b, thereby increasing width Wb(and the associated cross-sectional area), while sidewalls184aapproach sidewalls180a, thereby reducing width Wa(and the associated cross-sectional area), as shown inFIG. 8A. As a result, the pumping rate of pumping channels186bis increased, while the pumping rate of pumping channels186ais decreased. Therefore, rotation of shaft24in the second direction can provide a net positive pumping rate wherein pumping channels186bdirect captured lubricant back to lubricant side26at a faster rate than pumping channels186adirect captured lubricant toward non-lubricant side28.

In some instances, as shown inFIG. 8B, the relative rotation between valving portion160and active surface140can result in sidewalls184acontacting sidewalls180a, thereby reducing the width Watherebetween (and the associated cross-sectional area) to essentially zero, while maximizing the width Wb(and the associated cross-sectional area) between sidewalls184b,180b. As a result, the pumping rate of channels186bis maximized, while the pumping rate of channels186ais essentially reduced to zero, thereby resulting in a further increase in the net positive pumping rate.

Thus, the relative rotation between valving portion160and active surface140due to rotation of shaft24can be advantageously utilized to reduce the pumping rate of one set of pumping channels while increasing the pumping rate of the other set of pumping channels, thereby ensuring a net positive pumping result regardless of the rotation of shaft24. The degree to which valving portion160rotates relative to active surface140can vary based on the construction of seal120and the interaction of these components with shaft24, as described above. Thus, it should be appreciated that seal120can be configured so that pumping channels186a,186bare either increased, reduced, or completely sealed due to the relative movement between valving portion160and active surface140, depending upon the particular design, configuration, and operation of seal120.

The person skilled in the art will appreciate that other channel configurations can be utilized in combination with the subsequent teachings of this disclosure to advantageously affect the pumping rate of the pumping elements. For example, the angles of pumping channels186a,186brelative to the rotational axis of shaft24could be increased or decreased. For another example, as illustrated inFIG. 5, pumping channels186a″,186b″ could be curved channels formed by sides of teeth176″ and recesses174″ that form generally helical channels having a variable slope as teeth176″ and recesses174″ extend along seal120″.

Referring now toFIGS. 9-11, a second embodiment of a seal220according to the present teachings is shown. Seal220is similar to seal120described above and, thus, only differences will be described herein. In seal220, pumping elements256are configured differently than pumping elements156utilized in seal120. In particular, recesses274on active surface240are axially spaced further away from seal lip254than is done in seal120. As a result, pumping channels286a,286bare further spaced away from seal lip254. Additionally, active surface240includes a plurality of pumping channels288a,288bthat extend from seal lip254into pumping channels286a,286b, respectively. Pumping channels288a,288bform the primary pumping channels through which lubricant is captured and directed back to lubricant side26. Pumping channels288a,288bhave dimensions that can remain constant between seal lip254and pumping channels286a,286b. Additionally, pumping channels288a,288bcan be open at seal lip254such that when shaft24is not rotating, lubricant can seep into pumping channels288a,288bfrom lubricant side26.

One set of pumping channels288aextends at a third angular direction (orientation) along active surface240, while the second set of pumping channels288bextend at a fourth angular direction (orientation) along active surface240. As a result, one set of pumping channels288a,288bcan provide a pumping action of captured lubricant back toward lubricant side26when shaft24rotates in a first direction, while the other set of pumping elements288a,288bprovides pumping action of captured lubricant back to lubricant side26when shaft24rotates in a second direction opposite to the first direction. It should be appreciated that while one set of pumping channels288a,288bis operable to pump captured lubricant toward lubricant side26for a particular rotation of shaft24, the other pumping channels288a,288bwill provide a pumping action of captured lubricant toward non-lubricant side28.

To reduce the pumping rate of the pumping channels288a,288bthat pump captured lubricant toward non-lubricant side28, valving portion260moves relative to active surface240during rotation of shaft24to minimize and/or prevent flow through the pumping channels288a,288bthat are pumping captured lubricant toward non-lubricant side28due to that particular direction of rotation of shaft24. In particular, as shown inFIG. 11A, when shaft24rotates in a first direction, valving portion260moves relative to active surface240such that sidewalls284bof teeth276move toward sidewalls280bof recesses274. As a result, the width Wb(and the associated cross-sectional area) of pumping channel286bis reduced and chokes or restricts the flow of lubricant in pumping channel288bfrom entering into channel286b. Simultaneously, the width Waof pumping channel286aincreases as sidewall284amoves away from sidewall280a. The increasing of the width Wa(and the associated cross-sectional area) of pumping channel286adoes not inhibit the flow of lubricant into or out of pumping channel288a. With this rotation, pumping channels288acan provide a greater pumping rate than channels288b. As a result, a net positive pumping rate is achieved wherein pumping channels288apump captured lubricant back to lubricant side26at a faster rate than pumping channels288bpump captured lubricant toward non-lubricant side28.

In some embodiments, as shown inFIG. 11B, it may be possible for valving portion260to move relative to active surface240a sufficient quantity such that sidewalls284bcontact sidewalls280band thereby block flow through channel288b. When this is the case, the pumping rate of channels288bis essentially reduced to zero, while the pumping rate through pumping channels288ais maximized.

When shaft24rotates in the second direction opposite to the first direction discussed above, valving portion260moves relative to active surface240in the other direction such that sidewalls284aapproach sidewalls280a, as shown inFIG. 11C. In this direction of rotation, lubricant flow through pumping channels288ais reduced due to the decrease in width Wa(and the associated cross-sectional area) as sidewalls284aapproach sidewalls280a. Simultaneously, the flow rate through pumping channels288bcan be the same or increase due to the increase in width Wb(and the associated cross-sectional area) as sidewalls284bmove away from sidewalls280b. As a result, a net positive pumping rate is achieved wherein channels288bpump captured lubricant back to lubricant side26at a faster rate than pumping channels288apump captured lubricant toward non-lubricant side28.

In some embodiments, as shown inFIG. 11D, valving portion260may move relative to active surface240a sufficient distance such that pumping channels288aare closed off by sidewalls284acontacting sidewalls280a. When this is the case, the rate of pumping in pumping channels288ais essentially zero, while pumping channels288bis maximized.

Thus, in seal220, pumping channels288a,288bcan be restricted and/or sealed to provide a positive net pumping rate such that captured lubricant is pumped back to lubricant side26at a faster rate than is pumped toward non-lubricant side28.

Referring now toFIGS. 12-14, a third embodiment of a seal320according to the present teachings is shown. Seal320is similar to seal120and220described above. Thus, only the differences will be described herein. In seal320, valving portion360is an integral component of primary sealing portion338. In particular, valving portion360is in the form of flexible fingers that deform during rotation of shaft24to restrict and/or block flow through either pumping channels388aor pumping channels388bdepending upon the direction of rotation of shaft24. Seal lip354includes a plurality of axially extending recesses390, which can be generally triangular in shape. Pumping channels388a,388bextend from recesses390in respective first and second angular directions (orientations) along active surface340. Fingers392extend from the center of recesses390toward lubricant side26and engage with shaft24. Each finger392is between a pair of adjacent pumping channels388a,388b.

During rotation of shaft24, fingers392deform/move relative to pumping channels388a,388b. In particular, as shown inFIG. 14A, when shaft24rotates in a first direction, fingers392move toward openings394b, thereby impeding lubricant flow in pumping channel388b. In some embodiments, fingers392may block openings394bto pumping channels388b, as shown inFIG. 14B. Movement of fingers392toward openings394brestricts or prevents the flow of lubricant in pumping channels388bwhile not interfering with the ability of pumping channels388ato pump captured lubricant back to lubricant side26. As a result, a net positive pumping rate can be achieved wherein pumping channels388aare operable to pump lubricant to lubricant side26at a faster rate than pumping channels388bare able to pump lubricant toward non-lubricant side28.

When shaft24rotates in a second direction opposite to the first direction, fingers392will deform/move toward openings394aand restrict flow of lubricant in pumping channels388a, as shown inFIG. 14C. In some embodiments, fingers392may block openings394ato pumping channels388a, as shown inFIG. 14D. Movement of fingers392toward openings394areduces or prevents lubricant from being pumped by pumping channels388atoward non-lubricant side28, while pumping channels388bare unimpeded and able to pump lubricant toward lubricant side26. As a result, a net positive pumping rate can be achieved with pumping channels388bpumping lubricant toward lubricant side26at a greater rate than the ability of pumping channels388ato pump lubricant toward non-lubricant side28.

Thus, in seal320, flexible fingers392are operable to restrict and/or block openings394a,394bto respective pumping channels388a,388b, depending upon the direction of rotation of shaft24. As a result, one of the sets of pumping channels388a,388bcan pump lubricant toward lubricant side26at a faster rate than the other set of pumping channels388a,388bcan pump lubricant toward non-lubricant side28. Accordingly, a positive net pumping rate can be achieved regardless of the direction of rotation of shaft24.

Referring now toFIGS. 15-16, a seal420according to a fourth embodiment in the present teachings is shown. Seal420is similar to seals120,220,320described above. As such, only the differences are described herein. In seal420, valving portion460is a separate and discreet component that is not part of body434. Rather, valving portion460is an annular flexible ring that is retained within primary sealing portion438. Specifically, primary sealing portion438includes an active surface440with a recessed section496that extends radially the entire circumference of active surface440. Recessed section496includes recesses474that each has a bottom478and sidewalls480a,480b. Recessed section496includes a continuous annular portion497that, in combination with recesses474, receives valving portion460.

Valving portion460includes an annular band section498from which teeth476extend. Band section498resides in annular portion497of active surface440with teeth476disposed in recesses474. Annular portion497can include an undercut482that is complementary with a sloping top surface499of band section498. Undercut482and sloping top surface499can facilitate retention of valving portion460in active surface440of primary sealing portion438when handling seal420and inserting the same around shaft24. This enables valve portion460to be inserted into seal420prior to putting seal420into service. Additionally, this engagement reduces the chance of valving portion460from falling off of primary sealing portion438during handling of seal420.

Valving portion460is operable to rotate relative to active surface440as a result of rotation of shaft24. The relative rotation is limited by the engagement of sidewalls484a,484bwith respective sidewalls480a,480bof recesses474. The sidewalls484awill move toward and/or engage with sidewalls480aor sidewalls484bwill move toward and/or engage with sidewalls480b, depending upon the direction of rotation of shaft24. As a result of this relative movement, the widths Wa, Wb(and the associated cross-sectional areas) of pumping channels486a,486bwill change to alter the pumping rates of pumping channels486a,486b. Thus, when shaft24rotates in a first direction, sidewalls484bcan approach and/or contact sidewalls480b, thereby reducing and/or eliminating lubricant flow through pumping channels486b. Simultaneously, pumping channels486aare enlarged, thereby facilitating the pumping of lubricant therethrough back into lubricant side26. As a result, a positive net pumping rate can be achieved.

Similarly, when shaft24rotates in a second direction opposite the first direction, sidewalls484aapproach and/or contact sidewalls480a, thereby reducing and/or eliminating lubricant flow through pumping channels486a. As a result, the pumping rate of channels486ais reduced and/or eliminated while the pumping rate of pumping channels486bis increased. Accordingly, pumping channels486bcan pump lubricant back to lubricant side26at a faster rate than pumping channels486acan pump lubricant toward non-lubricant side28. As a result, a positive net pumping rate is achieved.

Thus, seal420can utilize a valving portion460that is distinct and separate from body434of seal420. Valving portion460can move relative to active surface440to reduce/increase the size (and the associated cross-sectional area) of pumping channels486a,486bto advantageously allow a positive net pumping rate of lubricant back toward lubricant side26regardless of a direction of rotation of shaft24.

The seals120,220,320,420described herein can be made from a variety of materials. By way of non-limiting example, the materials can include elastomers, rubber, PTFE, TPV, and similar materials and combinations thereof.

While the seal according to the present teachings has been described with reference to specific examples and embodiments, it should be appreciated that these are merely exemplary and that changes and alterations can be made. For example, the various features of seals120,220,320,420can be intermixed or interchanged with one another to provide a desired bi-directional pumping result. Furthermore, the specific orientation and configurations of the various pumping channels can vary from that shown. For example, the pumping channels can have a decreasing cross-sectional area, as the channels extend, to provide a preferential pressure increase along the pumping channels. For example, when the pumping channels do not extend through the seal lip, having the pumping channels reduce in cross-sectional area as they approach the seal lip can advantageously cause a pressure buildup to occur, thereby facilitating the captured and pumped lubricant disrupting the engagement of the seal lip with the shaft and allowing lubricant to flow back into lubricant side26. Additionally, it should be appreciated that other sealing portions can be employed and/or it may be possible to eliminate a secondary sealing portion. Thus, the preceding description and illustrations are merely exemplary in nature and are not intended to limit the scope of the present teachings.