Scavenger pump seal and radial shaft seal assembly therewith

A scavenger pump seal and radial shaft seal assembly therewith are provided. The scavenger pump seal includes an inner case configured for fixed attachment to a shaft for conjoint rotation with the shaft and an outer case configured for fixed receipt in a housing in which the shaft rotates. The inner case has an innermost wall sized for a press fit on the shaft and an outermost wall. An absorbent member is fixed to the inner case with the outermost wall overlying the absorbent member, thereby preventing the absorbent member from moving radially outwardly. The outer case has an outermost wall sized for fixed receipt in the housing, and facilitates preventing the egress of oil to the external environment.

BACKGROUND OF THE INVENTION

1. Technical Field

This invention relates generally to dynamic oil seals, and more particularly to radial shaft seals.

2. Related Art

Dynamic radial shaft oil seals are designed to have a so-called “oil-side” of the seal and an “air-side.” These designations pertain to the orientation of the seal when installed, with the oil-side facing the interior of the housing and being in communication with the oil, whereas the air-side faces outwardly and is exposed to the air.

During use, it is desirable to keep dust and other contaminants on the air-side of the seal while maintaining lubrication on the oil-side of the seal. It is known to incorporate spiral grooves in a seal lip to pump lubrication back to the oil-side of the seal, however, these grooves are not infallible. When oil flows past the grooves, it is generally free to reach the air-side of the seal, which not only depletes the oil supply, but, in addition to making an unsightly mess and further causing the build-up of dust and debris within the oil accumulated on the air-side of the seal, requires servicing and replacement of the seal, which can be costly. Accordingly, what is needed is a seal that both reliable keeps contaminants on an air-side of the seal from reaching an oil-side of the seal, while at the same time, preventing the egress of lubrication on the oil-side of the seal from reaching the air-side of the seal.

SUMMARY OF THE INVENTION

In general terms, this invention provides a scavenger pump seal for use with a radial shaft seal to return oil that leaks past the radial shaft seal back to the oil-side of the radial shaft seal, thereby preventing the oil from being depleted from the oil-side and reaching the air-side of the seal, and ultimately the outside environment.

In accordance with one presently preferred embodiment of the invention, the scavenger pump seal includes an annular slinger configured for operable attachment to a shaft for conjoint rotation therewith. An absorbent member is fixed to the annular slinger. The slinger has a wall with a portion aligned radially outwardly from and overlying the absorbent member with at least one opening in the wall through which oil contained within the absorbent member flows radially outwardly.

In accordance with another aspect of the invention, the wall of the slinger can provide a running surface along which a seal lip of a radial shaft seal runs.

In accordance with another aspect of the invention, the portion of the wall overlying the absorbent member includes a plurality of the openings.

In accordance with another aspect of the invention, the scavenger pump seal can include an annular deflector having a wall configured for operable attachment within a bore of a housing.

In accordance with another aspect of the invention, the absorbent member can be mechanically fixed to the annular slinger.

In accordance with another aspect of the invention, the annular slinger can extend axially into a u-shaped channel of the annular deflector for relative rotation therein.

In accordance with another aspect of the invention, a radial shaft seal and scavenger pump seal assembly is provided.

In accordance with another aspect of the invention, a radial shaft seal assembly is provided. The assembly includes a radial shaft seal having an outer case, a seal body attached to the outer case, and a seal lip extending radially inwardly from the seal body to form a seal between an air-side of the radial shaft seal and an oil-side of the radial shaft seal. Further, the assembly includes a scavenger pump seal having an inner case configured for fixed attachment to a shaft for conjoint rotation with the shaft and an outer case configured for fixed receipt in a housing in which the shaft rotates. The inner case has an innermost wall sized for a press fit on the shaft and an outermost wall. An absorbent member is fixed to the inner case on the air-side of said radial shaft seal with the outermost wall overlying the absorbent member to prevent the absorbent member from moving radially outwardly. The outer case has an outermost wall sized for fixed receipt in the housing on an air-side of the absorbent member to prevent oil from escaping to an outside environment

DETAILED DESCRIPTION OF PRESENTLY PREFERRED EMBODIMENTS

Referring in more detail to the drawings,FIGS. 1 and 2illustrate a radial shaft seal assembly10including a radial shaft seal11and a scavenger pump seal13constructed in accordance with one aspect of the invention. The assembly10is particularly suitable for use in a crankcase application, by way of example and without limitation, for sealing about a rotatable shaft, such as a crank shaft12. The radial shaft seal11has an oil-side O and an axially opposite air-side A, in relation to the orientation of the radial shaft seal11when installed, with the oil-side O facing the interior of the application being sealed and the air-side A facing the outside environment E of the application being sealed. The scavenger pump seal13returns any oil that leaks past the radial shaft seal11from the oil-side O to the air-side A back to the oil-side O, thereby preventing the oil from being depleted from the oil-side O, thereby maintaining the desired amount of oil within the oil-side O, while also preventing oil from reaching environment E, thereby preventing an unsightly mess.

The radial shaft seal11can be provided having a plurality of configurations, and is shown inFIGS. 1 and 2as includes a mounting portion, such as an outer case, also referred to as collar14, provided as a metal or polymeric annulus or ring structure sized for a press-fit within a bore of a housing15with an elastomeric seal material attached thereto to form a seal body16. The seal body16extends radially inwardly to provide a seal lip18that extends toward the air-side A. In addition to the seal lip, a separate seal lip20is attached to the elastic material of the seal body, such as a PTFE seal lip, by way of example, configured to extend toward the oil-side O axially along a seal wear surface, also referred to as running surface22. The seal lip20has an annular inner sealing surface24including one or more threads for sealed engagement with the running surface22. The threads extend helically to direct lubrication back to the oil-side O of the seal10when the shaft12. It should be recognized that the radial shaft seal11can be configured otherwise, having more or fewer seal lips, as desired. An important aspect of the radial shaft seal11is that it remains fixed via the collar14to the housing15and that it have one or more seal lips to inhibit oil from leaking from the oil-side O to the air-side A, though the radial shaft seal11need not be infallible as a result of the scavenger pump seal13and its ability to return any lubrication that leaks past the radial shaft seal11back to the oil-side O of the radial shaft seal11.

The scavenger pump seal13has a slinger, also referred to as an inner case26, with an absorbent member28fixed thereto for conjoint rotation with the shaft12and an annular deflector, also referred to as an outer case30, configured to be fixed with the housing15. Accordingly, the inner case26and outer case30rotate relative with one another in use. The inner case26is shown inFIGS. 1 and 2as being generally s-shaped in cross-section, including an axially extending radially innermost wall32, an axially extending outermost wall34and a radially extending intermediate leg36interconnecting the innermost and outermost walls32,34, wherein the walls32,34extend from the intermediate leg36in opposite directions from one another, thereby providing the generally s-shape. The innermost wall32has an inner surface sized for a line-to-line or slight interference press fit on the shaft12, thereby fixing the inner case26against relative movement with the shaft12, such that the shaft12and the inner case26rotate conjointly with one another. Further, the innermost wall32has an outer surface acting as the seal lip running surface22.

The outermost wall34extends from the intermediate leg36in an opposite axial direction from the innermost wall32. As best shown inFIG. 2, the outermost wall34has at least one, and preferably a plurality of through openings38spaced uniformly about the circumference thereof. As represented by arrow, the through openings38allow oil flow radially outwardly through the through openings38under centripetal force, such as while the shaft12and innermost wall32are rotating relative to the housing15and case30. The outermost wall34has an outer surface sized for a radial clearance fit with the housing bore15, thereby providing a gap therebetween. Further, to facilitate retaining the absorbent member28in fixed relation to the inner case26, an annular free end of the outermost wall34is curled radially inwardly to for a radially inwardly extending lip40that mechanically captures the absorbent member28between the lip40and the intermediate leg36in an interference clamping fashion, thereby preventing relative rotation between the inner case26and the absorbent member28.

The outer case30is generally u-shaped in cross-section, including an axially extending outermost wall42, an axially extending innermost wall44and a radially extending intermediate leg46spacing the walls42,44radially from one another in overlying relation. The innermost wall44has a radially inwardly facing inner surface sized for a slight clearance fit with the shaft12and a radially outwardly facing outer surface sized for a slight clearance fit with the absorbent member28, thereby allowing the inner case26and absorbent member28to rotate freely relative to the outer case30. The outermost wall42has a radially outwardly facing outer surface sized for a line-to-line or slight interference press fit within the bore of the housing15, thereby fixing the outer case30against relative movement with the housing15.

Upon assembling the scavenger pump seal13in the bore of the housing15and in its functional position relative to the radial shaft seal11, the inner case26is pressed on the shaft12and positioned to locate the running surface22beneath the seal lips18,20of the radial shaft seal11with the intermediate leg36of the inner case26remaining spaced from the radial shaft seal11so as to avoid friction there against. Further, the outermost wall42of the outer case30is pressed in the bore of the housing15to position the innermost wall44in a clearance fit beneath the absorbent member28and in a clearance fit above the shaft12and to fix the outermost wall42with the housing15. When assembled, the intermediate leg46of the outer case30is spaced from the inner case26and absorbent member28to prevent creating friction. As such, an end region of the inner case outermost wall34and a portion of the absorbent member28are received in a slight clearance fit within a generally u-shaped annular pocket48of the outer case30, thereby establishing a non-contact labyrinth therebetween.

In use, as oil eventually leaks past the seal lip or lips18,20of the radial shaft seal11, the oil comes into contact with the rotating inner case26. Some of the oil will be directly flung radially outwardly by the outmost wall34of the inner case26, wherein this oil can flow to a drain hole (not shown) at a bottom location of the engine housing15between the outermost wall42of the outer case30and the radial shaft seal11, which applies to all embodiments discussed hereafter. Upon flowing into the drain hole, the oil can return to the crank case or held in a retention location. In addition, some of the leaked oil will flow over the outmost wall34of the inner case26into the annular pocket48. Upon reaching the pocket48, the oil can be absorbed or wicked by the absorbent, wicking member28, e.g. open or closed cell foam or felt type material, which can be provided, cut and assembled from a strip of the absorbent material, which applies to all embodiments discussed herein. Then, as the absorbent member28rotates conjointly with the inner case26, the centripetal force of the rotating absorbent member28causes the oil to be flung radially outwardly through the through openings38, and from here, the oil flows to the aforementioned drain hole in the engine housing15, as discussed above. Accordingly, the oil that leaks past the radial shaft seal11to the air-side A thereof is automatically returned internally within engine, and thus, back to the oil-side O, thereby being prevented from reaching the environment E. This not only prevents an unsightly mess, but also extends the useful life of the radial shaft seal11and engine, as well as reducing the frequency of oil additions and changes.

InFIG. 3, a radial shaft seal assembly110including a radial shaft seal111and a scavenger pump seal113constructed in accordance with another aspect of the invention is shown, wherein the same reference numerals as used above, offset by a factor of 100, are used to identify like features. The scavenger pump seal113is substantially similar as described above for the scavenger pump seal13, and thus, only the notable difference is discussed further, with all remaining features remain the same. The scavenger pump seal113includes an inner case126having an innermost wall132, an outermost wall134and a radially extending intermediate wall136connecting the inmost and outermost walls132,134to one another. However, rather than retaining an absorbent member128with a circumferentially continuous annular lip, as discussed above, the inner case126has a plurality of radially inwardly extending tangs140. The tangs140are folded or otherwise bent over into a capturing relation with the absorbent member128to retain the absorbent member128in fixed relation axially between the tangs140and a radially extending intermediate leg136. The tangs140are spaced circumferentially from one another by gaps G, through which lubrication can pass for ready absorption by the absorbent member128. Otherwise, the scavenger pump seal113is the same as that discussed above.

InFIG. 4, a radial shaft seal assembly210including a radial shaft seal211and a scavenger pump seal213constructed in accordance with another aspect of the invention is shown, wherein the same reference numerals as used above, offset by a factor of 200, are used to identify like features. The scavenger pump seal213is substantially similar as described above for the scavenger pump seal13, and thus, only the notable difference is discussed further, with all remaining features remain the same. The scavenger pump seal213includes an inner case226(FIG. 4A) and an outer case230having an innermost wall244. However, rather than the innermost wall244extending axially to a free uncurled end, as in the previous embodiments, the innermost wall244has a radially outwardly extending end lip50. The end lip50can remain spaced from the absorbent member228, thereby preventing friction there against, or it could be brought into an interference fit, and regardless, the end lip50acts to prevent oil from leaking past the free end and escaping under the outer case230to the environment E. Otherwise, the scavenger pump seal213is the same as that discussed above.

InFIG. 5, a radial shaft seal assembly310including a radial shaft seal311and a scavenger pump seal313constructed in accordance with another aspect of the invention is shown, wherein the same reference numerals as used above, offset by a factor of 300, are used to identify like features. The scavenger pump seal313is substantially similar as described above for the scavenger pump seal213, and thus, only the notable difference is discussed further, with all remaining features remain the same. The scavenger pump seal313includes an inner case326(FIG. 5A) and an outer case330having innermost wall344. The innermost wall344has a radially outwardly extending end lip350. The end lip350is shown as being slightly curled to provide an annular channel52to further prevent oil from escaping past the lip350. The lip350remains spaced from the absorbent member328, thereby preventing friction there against, or it could be brought into an interference fit, and regardless, acts to prevent oil from leaking past the free end and escaping under the outer case230to the environment E. In addition, the inner case326has an annular reverse folded region54transitioning an innermost wall332with an intermediate leg336, thereby forming a recessed annular channel56. The reverse folded region54extends beneath a portion of the absorbent member328, thereby acting to further retain the absorbent member. Further yet, a lower corner58of the absorbent member328is chamfered, thereby creating an exposed, increased surface area for absorbance. Otherwise, the scavenger pump seal313is the same as that discussed above.

InFIG. 6, a radial shaft seal assembly410including a radial shaft seal411and a scavenger pump seal413constructed in accordance with another aspect of the invention is shown, wherein the same reference numerals as used above, offset by a factor of 400, are used to identify like features. The scavenger pump seal413includes an inner case426and an outer case430. The inner case426has a two part construction, including first and second inner case members426′,426″ constructed separately from one another and then fixed to one another. The first inner case member426′ is configured similar to the inner case26of FIG.1, however, it does not include a lip40for retaining the absorbent member428. As such, the second inner case member426″ is provided to retain the absorbent member428in fixed relation within the inner case426. The second inner case member426″ includes a cylindrical innermost wall432″ and a radially outwardly extending leg436″. The cylindrical innermost wall432″ is configured to be press fit on the shaft along with the first inner case member426′ and the radially outwardly extending leg436″ is configured to be press fit within an outermost wall434′ of the first inner case member426′, and thus, both the first inner case member426′ and the second inner case member426″ rotate conjointly with the shaft and with one another. Further, the second inner case member426″ includes a curled or folded lip440″ that extends in radially overlapping relation with the inner most wall432″ to facilitate retaining the absorbent member428in fixed relation with the inner case426, in addition to the absorbent member being sandwiched between the outermost wall434′ and the inner most wall432″. As such, the absorbent member426rotates conjointly with the inner case426, as discussed above for the previous embodiments.

In addition, the outer case430includes a two part construction, with an outermost wall442, an innermost wall444, and an intermediate leg446region pressed in the outermost wall442, or otherwise fixed thereto. As discussed above, the outermost wall442is configured to be fixed to the housing (not shown), and is shown as being formed as a single, monolithic piece of material with the outer case of the radial shaft seal411. Further, unlike the previous embodiments, the innermost wall444does not wrap beneath the absorbent member428, but rather, extends axially into the absorbent member428for relative rotational movement therein, such as in a slight clearance fit or line-to-line fit so as to minimize friction between the innermost wall444and the absorbent member428. As such, by extending the innermost wall444into the absorbent member428, a closed off cavity or chamber60is formed which prevents any leaked oil from by-passing the outer case430and the innermost wall444without first being absorbed by the absorbent member428. Accordingly, any oil leaking past the radial shaft seal411is assured of being absorbed by the absorbent member428, whereupon the oil is flung under centrifugal force radially outwardly through the through openings in the outer case430, as discussed above, and recycled, as discussed above.

InFIG. 7, a radial shaft seal assembly510including a radial shaft seal511and a scavenger pump seal513constructed in accordance with another aspect of the invention is shown, wherein the same reference numerals as used above, offset by a factor of 500, are used to identify like features. The scavenger pump seal513includes an inner case526and an outer case530. The inner case526has a two part construction, as discussed above for the embodiment ofFIG. 6, including first and second inner case members526′,526″. The first inner case member526′ is configured similar to the inner case26ofFIG. 1, however, it does not include a lip40to facilitate retaining an absorbent member528. Rather, the absorbent member528is sandwiched between an outermost wall534of the first inner case member526′ and a generally cylindrical innermost wall532″ of the second inner case member526″. As such, the absorbent member528is fixed for conjoint rotation with the first and second inner case members526′,526″ as well as with the shaft. The cylindrical innermost wall532″ is configured to be press fit within an enlarged annular counterbore62of an innermost wall532′ of the inner case526, thereby fixing the first and second inner case members526′,526″ to one another against relative rotation. Accordingly, the first inner case member526′ and the second inner case member526″ rotate conjointly with the shaft, and the absorbent member526rotates conjointly with the inner case526, as discussed above for the previous embodiments. Otherwise, the assembly510is generally the same as discussed above with regard to the assembly410ofFIG. 6.

InFIG. 8, a radial shaft seal assembly610including a radial shaft seal611and a scavenger pump seal613constructed in accordance with another aspect of the invention is shown, wherein the same reference numerals as used above, offset by a factor of 600, are used to identify like features. The scavenger pump seal613includes an inner case626and an outer case630. The inner case626has a two part construction, as discussed above for the embodiment ofFIG. 7, including first and second inner case members626′,626″. The first and second inner case members626′,626″ are configured the same as discussed above with regards to the seal assembly510ofFIG. 7. However, the outer case630is configured differently from the outer case530ofFIG. 7. Rather than the outer case630having an innermost wall extending into an absorbent member628, the outer case630has an innermost wall644configured to extend axially between the absorbent member628and the second inner case member626″ in a slight radial clearance fit therebetween, such as discussed above with regard to the seal assembly10ofFIG. 1. Otherwise, the assembly610is generally the same as discussed above with regard to the assembly510ofFIG. 7.

InFIG. 9, a radial shaft seal assembly710including a radial shaft seal711and a scavenger pump seal713constructed in accordance with another aspect of the invention is shown, wherein the same reference numerals as used above, offset by a factor of 700, are used to identify like features. The radial shaft seal711and the scavenger pump seal713are shown as separate components spaced axially from one another along a shaft. The radial shaft seal711is shown disposed on a wear sleeve64having a cylindrical wall65and upstanding leg66extending radially outwardly from the wall65. The wall66includes an annular lip67extending axially in overlying relation with the wall65.

The scavenger pump seal713includes an inner case726and an outer case730. The inner case726is generally c-shaped in axial cross-section having radially innermost and radially outermost annular walls732,734aligned radially with one another in spaced relation as a result of an intermediate leg736extending therebetween. The intermediate leg736of the inner case726faces the leg66of the wear sleeve64such that the innermost and outermost walls732,734of the inner case726extend away from the wear sleeve64. An absorbent member728is fixed within the inner case726in abutting relation with the intermediate leg736between the innermost and outermost walls732,734. The absorbent member728is shown in abutting relation with the outermost wall734and spaced from the innermost wall732to provide an annular gap between the absorbent member728and the innermost wall732. The outer case730is configured similarly as discussed above with regard to the outer case30, and thus, has an outermost wall742, an innermost wall744and an intermediate leg746. The outermost wall742is configured for fixed receipt in a housing and the innermost wall744is configured to extend in a clearance fit within the gap between the absorbent member728and the innermost wall732of the inner case726to establish a labyrinth passage. The absorbent member728can be fixed to the inner case726via any suitable mechanical or adhesive mechanism, including rivets or glues, for example, which applies equally to all embodiments discussed herein and illustrated inFIGS. 1-11.

InFIG. 10, a radial shaft seal assembly810including a radial shaft seal811and a scavenger pump seal813constructed in accordance with another aspect of the invention is shown, wherein the same reference numerals as used above, offset by a factor of 800, are used to identify like features. The seal assembly810is similar to the assembly710, including having a radial shaft seal811and a scavenger pump seal813provided as separate components spaced axially from one another along a shaft. The notable distinction between the seal assembly710and the seal assembly810is with regard to an outer case830of the scavenger pump seal813. Rather than an innermost wall832of outer case830extending axially beneath an absorbent member828of the scavenger pump seal813, the innermost wall832extends axially into the absorbent member828, as discussed above with regard to the scavenger pump seals413,513. Otherwise, the seal assembly810is the same as discussed regarding the seal assembly710.

InFIG. 10A, a radial shaft seal assembly810′ including a radial shaft seal811′ and a scavenger pump seal813′ constructed in accordance with another aspect of the invention is shown, wherein the same800series reference numerals as used inFIG. 10, however “primed”, are used to identify like features. The seal assembly810′ is similar to the assembly810, wherein the notable distinction between the seal assembly810and the seal assembly810′ is with regard to the addition of a dust lip68that is operably attached to an outer case830′ of the scavenger pump seal813′. The dust lip68is shown as being fixed to a radially extending wall of the outer case830′ with the dust lip68extending radially inwardly for running contact with the shaft812′. As such, debris is further inhibited from entering seal assembly810′. Otherwise, the seal assembly810′ is the same as discussed regarding the seal assembly810.

InFIG. 11, a radial shaft seal assembly910including a radial shaft seal911and a scavenger pump seal913constructed in accordance with another aspect of the invention is shown, wherein the same reference numerals as used above, offset by a factor of 900, are used to identify like features. The scavenger pump seal913includes an inner case926and an outer case930. The inner case926has a cylindrical innermost wall932, a frustroconical outermost wall934and an intermediate leg936extending radially therebetween and connecting the innermost and outermost walls932,934to one another. An absorbent member928is fixed to the inner case926radially inwardly from the outermost wall934, and is shown fixed in abutment with the outermost wall934and the intermediate leg936, such as via any suitable mechanical fastener or adhesive. The innermost wall932is configured for a press fit on a shaft such that the inner case926and absorbent member928rotate conjointly with the shaft. The outermost wall934diverges radially outwardly from the intermediate leg936to a free end. The free end of the outermost wall934extends in overlapping, radially spaced and aligned relation with at least a portion of an innermost wall944of the outer case930, and an outermost wall942of the outer case930is configured for a press fit into a housing. As discussed above, the radial shaft seal911is configured to run in sealed engagement with an outer surface of the innermost wall932, such that the innermost wall932functions as a wear sleeve. As the scavenger pump seal913rotates conjointly with the shaft, oil absorbed by the absorbent member928is flung radially outwardly along the frustroconical outermost wall934and out an annular gap formed between the free end of the outermost wall934and the outer case930, whereupon the oil is returned to the engine case.

InFIG. 11A, a radial shaft seal assembly910′ including a radial shaft seal911′ and a scavenger pump seal913′ constructed in accordance with another aspect of the invention is shown, wherein the same900series reference numerals as used inFIG. 11, however “primed”, are used to identify like features. The seal assembly910′ is similar to the assembly910, wherein the notable distinction between the seal assembly910and the seal assembly910′ is with regard to the addition of a dust lip968that is operably attached to an outer case930′ of the scavenger pump seal913′. The dust lip68is shown as being fixed to a radially extending wall of the outer case930′ with the dust lip968extending radially inwardly for running contact with a shaft. As such, debris is further inhibited from entering seal assembly910′. Otherwise, the seal assembly910′ is the same as discussed regarding the seal assembly910.

Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims and any claims ultimately allowed, the invention may be practiced otherwise than as specifically described.