WO2012087672A1

WO2012087672A1 - Fluid seal assembly

Info

Publication number: WO2012087672A1
Application number: PCT/US2011/064643
Authority: WO
Inventors: Albert Zhaokuan YE
Original assignee: Aktiebolaget Skf
Priority date: 2010-12-20
Filing date: 2011-12-13
Publication date: 2012-06-28
Also published as: WO2012087672A9

Abstract

A fluid seal assembly is disposed between an outer surface, i.e. engine block or any other part that requires application of the assembly and a rotatable member, such as, for example a shaft, wherein the assembly circumscribes the shaft and lubricated the shaft and the same rotates around the axis. The assembly includes a casing unit and a sealing ring unit presenting an active surface and a sealing lip engaging the cylindrical member. A pair of converging walls extending from the active surface to the sealing lip. One of these walls presents a continuous pattern of pumping elements integral for pumping the lubricant back to the shaft and between the shaft and the sealing ring unit.

Description

TITLE OF THE INVENTION

Fluid Seal Assembly

FIELD OF THE INVENTION

The present invention relates generally to fluid seals for use with relatively rotatable members, such as shafts and the like.

BACKGROUND OF THE INVENTION

Fluid seal assemblies of various types are used in numerous applications including and not limited to sealing vehicular engine crankshafts, transmission shafts, bearing lubrication systems, compressor shaft support assemblies, and the like. The fluid seal assembly is designed to retain and seal oil or grease in a predetermined location for lubricating the shaft and to prevent ingress of environmental

contaminants.

Typical fluid seal assembly includes a casing unit, a flexible sealing member having a sealing lip adapted to engage against a sealing surface of a relatively rotatable member, such as the shaft. The flexible sealing member includes a body portion extending to an annular flex portion of reduced cross-sectional thickness bonded to the metal case member and located intermediate the seal lip and metal case. The purpose of this flex section is to allow the seal lip to stay in continuous, intimate contact with the shaft it is to seal despite any lack of concentricity between the relatively rotating members, e.g. the rotating shaft and the stationery engine block into which the annular metal case member is installed.

It is important to constantly retain and seal oil or grease in a predetermined location for lubrication of the shaft and to prevent ingress of environmental contaminants. There are numerous prior art seal assembly designs, which are effective to return oil or other lubricant to the sealed cavity upon rotation of the shaft. In either case, relative motion between the shaft and the seal assembly serves to "pump" the oil, grease, or other sealed fluid back into the sealed region defined between the shaft and the seal assembly.

Various prior art references are known which disclose fluid seals adaptable to retain and seal oil or grease in a predetermined location for lubricating the shaft. These prior art references include and are not limited to United States Patent Nos. 3,501,155 to Dega et al.; 4,336,945 to Christiansen, et al.; 4,501,431 to Peisker et al., 4,667,968 to Nash et al., 4,886,281 to Ehrmann et al.; 4,969,653 to Breen, and 5,553,870 to Czekansky et al.

The United States Patent No. 3,501,155 to Dega et al. teaches a fluid seal assembly designed to seal a space between a rotatable shaft and a stationary member. The fluid seal assembly includes a casing unit and an elastomeric seal ring defining diverging walls extended to a seal lip frictionally engaging the shaft. An in-pumping region defined by a plurality of ribs are molded to the diverging walls and inclined in to different directions relative the seal lip.

The ribs fail to effectively out-pump the oil and then feed the oil back to the in-pumping region to avoid the oil spraying and to prevent wear and tear of the elastomeric seal sleeve as the same rotates relative the shaft. The ribs extend in one direction and create a plurality of passages thereby allowing the oil to spread away from the seal lip, thereby increasing the oil spray, which, in a long run, negatively impacts the seal life of the fluid seal assembly. In addition, the prior art design of the fluid seal assembly leads to early failure of its function as oil is sprayed at a relatively high speed, such as, for example, 2000 rpm.

The United States Patent No. 5,553,870 to Czekansky et al. discloses a fluid seal assembly having a case unit, a seal sleeve circumscribing a shaft rotatable about the axis and relative a stationary member. The seal sleeve includes a contact lip or an edge and a pumping labyrinth defined by vanes, which exist as triangular

embossments formed integrally with the contact lip. The vanes are not connected with one another to form a closed loop or closed area. The pattern of the vanes, as taught by the United States Patent No. 5,553,870 to Czekansky et al., allows the oil to spread away from the contact lip, thereby increasing the oil spray, which, in a long run negatively impacts a life span of the fluid seal assembly. In addition, the design of the fluid seal assembly taught by the United States Patent No. 5,553,870 to Czekansky et al. may lead to early failure of its function as the oil is sprayed at a relatively high speed.

Other prior art references teach various seal sleeve designs including a contact lip or an edge and a pumping labyrinth defined by a plurality of cavities formed in the contact lip. The pattern of the cavities captures portions of the oil into the cavities but fails to provide a mechanism, which would continuously capture the oil in order to prevent the oil from spread away from the contact lip, thereby increasing the oil spray, which in a long run negatively impacts a life span of the fluid seal assembly. The pattern of the cavities may also lead to early failure of its function as the oil is sprayed at a relatively high speed.

Hence, there is a need for an improved fluid seal and methods to eliminate problems associated with prior art designs such as failure to pump the oil back to in- pumping region to avoid oil spraying, static leakage of oil, clogging up the seals with carbonized oil, constant wear and tear and replacement of parts that negatively impact lifecycle of the fluid seals. The inventive concept as set forth further below improves the aforementioned prior art systems and methods.

SUMMARY OF THE INVENTION

A fluid seal assembly (the assembly) of the present invention has numerous applications including and not limited to sealing vehicular engine crankshafts, transmission shafts, bearing lubrication systems, compressor shaft support assemblies, and the like. The assembly is disposed between an outer surface, i.e. a housing or an engine block or any other part that requires application of the assembly and a rotatable member, such as, for example a shaft, wherein the assembly circumscribes the shaft and lubricated the shaft as the same rotates around the axis. The assembly includes a casing unit and a sealing ring unit. The casing unit presents a rigid member having a side wall and a flange radially extending from the side wall.

The sealing ring unit is secured to the flange of the casing unit through the collar member. The collar member includes a neck portion defined by an upper lip and a lower lip defining a nest or a void therebetween to sandwich the flange. The sealing ring unit further includes a seal sleeve. The seal sleeve includes a body having a spring retention groove defined in the reversed wall to retain a spring and a plurality of converging walls extending from the active surface to a sealing lip. One of the converging walls presents a continuous pattern of pumping elements integral with and extending outwardly from one of the converging walls. The pumping elements are interconnected with one another to define an apex thereby diverging from the apex to the sealing lip forming a closed gate.

As the lubricant enters between the sealing ring unit and the cylindrical member, it is directed away from the axis of rotation under the influence of centrifugal force and enters the closed gates thereby preventing the lubricant from spraying beyond the closed gates. The closed gates pump the lubricant back between the sealing ring unit and the cylindrical member for continuously lubricating the cylindrical member rotatable relative the sealing ring unit and prevent frictional engagement between the sealing ring unit and the cylindrical member.

An advantage of the present invention is to provide a fluid seal assembly that includes a seal sleeve that presents bi-directional helix design formed to out-pump the oil thereby feeding the oil back to in-pumping region to avoid the oil spraying and to prevent wear and tear of the seal sleeve as the same rotates relative the shaft thereby increasing lifespan of the assembly.

Another advantage of the present invention is to provide an improved fluid seal assembly that eliminates problems associated with prior art designs such as static leakage of oil, clogging up the spirals with carbonized oil that negatively impact lifecycle of the fluid seals.

Still another advantage of the present invention is to provide the fluid seal assembly with a continuous X-shaped straight helix rib pattern with controlled distance between the seal lip and the cross point of the X-shaped ribs thereby forming the gates openly exposed to the shaft to capture the oil and pump the oil back to the shaft.

Still another advantage of the present invention is to provide the fluid seal assembly design that offers a low pump rate decay.

Still another advantage of the present invention is to provide the fluid seal assembly design that extends life span of the fluid seal assembly and enhances seal reliability in bi-directional applications, especially at high speed.

Still another advantage of the present invention is to provide the fluid seal assembly that is cost effective in manufacturing.

Other advantages and meritorious features of this invention will be more fully understood from the following description of the preferred embodiment, the appended claims, and the drawings; a brief description of which follows. BRIEF DESCRIPTION OF THE DRAWINGS

Other advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

Figure 1 illustrates a partial cross sectional view of a seal assembly (the assembly) with a sealing ring having an active surface defining a pattern of helical ribs extending from the active surfaces to form a plurality of gates exposed to a shaft;

Figure 2 illustrates a cross sectional view of the assembly circumscribing a shaft and disposed between the shaft and a counter surface;

Figure 3 illustrates a partial cross sectional view of the active surface of the sealing ring with the pattern of helical ribs extending from the active surfaces to form a plurality of gates exposed to the shaft;

Figure 4 illustrates a partial cross sectional view of an alternative embodiment of the active surface of the sealing ring with an alternative embodiment of the pattern of helical ribs extending from the active surfaces to form a plurality of gates exposed to the shaft; and

Figures 5A and 5B illustrate schematic views of prior art designs.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the Figures, wherein like numerals indicate like or corresponding parts throughout the several views, a fluid seal assembly (the assembly) of the present invention is generally shown at 10 in Figure 1. The assembly 10 has numerous applications including and not limited to sealing vehicular engine crankshafts, transmission shafts, bearing lubrication systems, compressor shaft support assemblies, and the like, without limiting the scope of the present invention.

Referring back to Figure 1, a partial cross sectional view of the assembly 10. The assembly 10 includes a casing unit, generally indicated at 12 and a sealing ring unit, generally indicated at 14. The casing unit 12 presents a rigid member having a side wall 16 presenting a bonding portion and a flange portion 18 extending outwardly from the side wall 16. The flange portion 18 terminates into a free end 20. The flange portion 18 and the side wall 16 present a radius portion 22 defined therebetween. The sealing ring unit 14 is secured to the flange portion 18 of the casing unit 12 through a collar member 24. The collar member 24 includes a neck portion defined by an upper lip or inner bonding portion 26 and a lower lip or an outer bonding portion 28 defining a nest 30 or a void therebetween to sandwich the side wall 16. The inner bonding portion 26 further extends along the side wall 16 and the flange portion 18 thereby encapsulating at least the flange portion 18 forming a plurality of circumferential ribs 32.

The sealing ring unit 14 further includes a seal sleeve, generally indicated at 34. The seal sleeve 34 includes a body 36 presenting a reverse surface 38 and an active surface 40. A spring retention groove 42 is formed in the reserve surface 38 to retain a spring 44 thereby applying external pressure to the seal sleeve 34

circumscribing the shaft S.

A plurality of converging walls 46, 48, 50, and 52 are defined in the active surface 40 of the seal sleeve 34. The wall converging walls 48 and 50 interconnect to define a sealing lip 54. The seal sleeve 34 is formed from any suitable elastomeric materials, such as rubber, silicone, polyacrylic, fluoroelastomer, ethylene acrylic, hydrogenated nitrile or nitrile elastomer. The sleeve 34 may also be formed from other materials such as, for example, polytetrafluoroethylene (PTFE) without limiting the scope of the present invention. The seal sleeve 34 is injection molded but may be formed by many other suitable methods without limiting the scope of the present invention.

As best shown in Figure 3, one of the converging walls 48 presents a continuous pattern of pumping elements, generally indicated at 60. The patter 60 is integral with extends outwardly from the converging wall 48. The pattern 60 presents a plurality of pumping elements, generally indicated at 62. The pumping elements 62 are interconnected with one another to define an apex 64 thereby diverging from the apex 64 to the sealing lip 54 forming a closed gate, generally indicated at 66.

Each of the pumping elements 62 is further defined by a pair of ribs 68 and 70 raised from the converging wall 48 and diverging from the apex 64. As illustrated in Figures 3 and 4, each rib 68 and 70 presents a triangular cross section. Those skilled in the art will appreciate that the triangular cross section is illustrated herewith for exemplary purposes and is not intended to limit the scope of the present invention. Other configurations of the cross section may be used in the present invention. Each of the apexes 64 of each of the pumping elements 62 presents an equal distance, shown at 72 in Figures 3 and 4, defined between each of the apexes 64 and the sealing lip 54. Preferably, there is a substantially equal distance 72 defined between each apex 64 and the sealing lip 54, which preferably has a value within the range of about 0.024 inches and about 0.040 inches, but may have any other appropriate value.

Alluding to the above, as shown in Figure 4, each rib 68 and 70 extends further and beyond the apex 64 to ribs 74 and 76 to define an X-shaped structure, generally shown at 78 in Figure 4, thereby forming additional barrier to prevent the lubricant from spraying beyond the apex 64 and to provide structural reinforcement to the ribs 68 and 70 forming the closed gates. Each rib 68 and 70 of each pumping element connects with the ribs 68 and 70 of the adjacent pumping element to define a flat portion 80 therebetween to form additional barrier at the sealing lip 54.

As the shaft S rotates relative the housing H with the assembly 10 disposed therebetween, the lubricant enters between the sealing ring unit 14 and the shaft S and is directed away from the axis of rotation A under the influence of centrifugal force. The lubricant then enters the closed gates 66, which prevent the lubricant from spraying beyond the closed gates 66. The closed gates 66 facilitate pumping action of the lubricant thereby pumping the lubricant back between the sealing ring unit 14 and the shaft S for continuously lubricating the shaft S rotatable relative the sealing ring unit 14 and preventing factional engagement between the sealing ring unit 14 and the shaft S.

The assembly 10 of the present invention includes numerous advantages over the prior art references. Then advantage of the present invention is to provide a fluid seal assembly that includes a seal sleeve that presents bi-directional helix design formed to out-pump the oil thereby feeding the oil back to in-pumping region to avoid the oil spraying and to prevent wear and tear of the seal sleeve 34 as the same rotates relative the shaft S thereby increasing lifespan of the assembly 10. The assembly 10 of the present invention improves one of the prior art designs, as illustrated in Figure 5A, wherein ribs fail to effectively out-pump the oil and then feed the oil back to the in-pumping region to avoid the oil spraying and to prevent wear and tear of the elastomeric seal sleeve as the same rotates relative the shaft. The ribs extending in one direction without create plurality of passages allow the oil to spread away from the seal lip, thereby increasing the oil spray which in a long run negatively impacts the seal life of the fluid seal assembly.

Alluding to the above, the assembly 10 also improves another prior art design, as one illustrated in Figure 5B, presenting a plurality of vanes extending from a sealing lip and not connected with one another to form a closed loop or closed area, thereby failing to form the closed area in which the oil out-pumped is then pumped back to prevent the oil spraying to prevent wear and tear of the elastomeric seal sleeve as the same rotates relative the shaft. Other advantage of the present invention, as compared to prior art design illustrated in Figures 5 A and 5B, is a continuous X- shaped straight helix rib pattern 60 with controlled distance 72 between the seal lip 54 and the cross point 64 of the X-shaped ribs 68 and 70 forming the gates 66 openly exposed to the shaft S to capture the oil and pump the oil back to the shaft S.

While the invention has been described with reference to an exemplary embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.

Claims

I claim:

1. A seal assembly for providing a seal between a cylindrical member and a housing with the cylindrical member rotatable around an axis of rotation and relative the housing, said seal assembly comprising:

a casing unit defined by a side wall and a flange extending radially from said side wall;

a sealing ring unit secured to said flange and presenting an active surface and a sealing lip engaging the cylindrical member; and

a pair of converging walls extending from said active surface to said sealing lip and presenting a continuous pattern of pumping elements integral with extending outwardly from one of said converging walls and interconnected with one another to define an apex thereby diverging from said apex to said sealing lip forming a closed gate so that lubricant entering between said sealing ring unit and the cylindrical member and directed away from the axis of rotation under the influence of centrifugal force enters said closed gates thereby preventing the lubricant from spraying beyond said closed gates and pumping the lubricant back between said sealing ring unit and the cylindrical member for continuously lubricating the cylindrical member rotatable relative said sealing ring unit and preventing frictional engagement between said sealing ring unit and the cylindrical member.

2. The seal assembly as set forth in claim 1, wherein each of said pumping elements is further defined a pair of ribs raised from said converging wall and diverging from said apex.

3. The seal assembly as set forth in claim 1, wherein each of said ribs presents a triangular cross section.

4. The seal assembly as set forth in claim 1, wherein each of said apexes of each said pumping elements presents an equal distance defined between each of said apexes and said sealing lip so that the lubricant entering between said sealing ring unit and the cylindrical member and directed away from the axis of rotation under the influence of centrifugal force enters said closed gates thereby preventing the lubricant from spraying beyond said closed gates and pumping the lubricant back between said sealing ring unit and the cylindrical member for continuously lubricating the cylindrical member rotatable relative said sealing ring unit and preventing frictional engagement between said sealing ring unit and the cylindrical member.

5. The seal assembly as set forth in claim 1, wherein said equal distance defined between each of said apexes and said sealing lip is up to 0.040 inches.

6. The seal assembly as set forth in claim 1, wherein said equal distance defined between each of said apexes and said sealing lip is at least 0.024 inches.

7. The seal assembly as set forth in claim 1, wherein each of said ribs extends further and beyond said apex to define an X-shaped structure thereby forming additional barrier to prevent the lubricant from spraying and provide structural reinforcement to said ribs forming said closed gates.

8. The seal assembly as set forth in claim 1, wherein each said rib of each said pumping element connects with said rib of adjacent pumping element to define a flat portion therebetween to form additional barrier at said sealing lip.

9. The seal assembly as set forth in claim 1, wherein said sealing ring unit is formed from at least one of elastomeric materials, such as silicone, polyacrylic, fluoroelastomer, ethylene acrylic, polytetrafluoroethylene.

10. The seal assembly as set forth in claim 1, wherein said sealing ring unit includes a sleeve portion defining said active surface and a reverse surface, a collar member connected to said sleeve to secure said sleeve to said flange.

11. The seal assembly as set forth in claim 1 , wherein said collar member presents a neck portion extending to outer bonding portion and inner bonding portion defining a seat to receive said side wall.

12. The seal assembly as set forth in claim 1, wherein said sealing ring unit presents a spring retention groove defined in said reversed surface to retain a spring.

13. The seal assembly as set forth in claim 11, wherein said sealing ring unit is formed from any suitable elastomeric materials, such as rubber, silicone, polyacrylic, fluoroelastomer, ethylene acrylic, polytetrafluoroethylene.

14. A method of forming a seal assembly to provide a seal between a cylindrical member and a housing with the cylindrical member rotatable around a an axis of rotation and relative the housing, said method comprising the steps of:

forming a casing unit having a side wall and a flange extending radially from the side wall;

forming a sealing ring unit with an active surface to engage the cylindrical member; and

forming a pair of converging walls extending from the active surface with one of the converging walls defining a continuous pattern of pumping elements integral with extending outwardly from one of the converging walls connected to define an apex diverging to the cylindrical member to form a closed gate to direct the lubricant entering the closed gates to prevent the lubricant from spraying beyond the closed gates and to pump the lubricant back between the sealing ring unit and the cylindrical member to continuously lubricate the cylindrical member and to prevent frictional engagement between the sealing ring unit and the cylindrical member.

15. The method as set forth in claim 14, including the step of forming ribs of each of the pumping element by raising the ribs from one of the converging walls.

16. The method as set forth in claim 14, including the step of forming the ribs by connecting the ribs to an apex extending at equal distance defined between each of the apexes and a sealing lip of the active surface at up to 0.040 inches.

17. The method as set forth in claim 16, including the step of forming the ribs by connecting the ribs to the apex extending at equal distance defined between each of the apexes and the sealing lip of the active surface at least to 0.024 inches.

18. The method as set forth in claim 17, including the step of extending each of the ribs further and beyond the apex to define an X-shaped structure to form additional barrier to prevent the lubricant from spraying and to provide structural reinforcement to the ribs forming the closed gates.

19. The method as set forth in claim 18, including the step of connecting each the rib of each pumping element to the rib of adjacent pumping element to define a flat portion therebetween to form additional barrier at the sealing lip.

20. The method as set forth in claim 19, including the step of forming the sealing ring unit from at least one of elastomeric materials, such as silicone, polyacrylic, fluoroelastomer, ethylene acrylic, polytetrafluoroethylene.