WO2015143315A1

WO2015143315A1 - Lip seal having a base member and a lip member

Info

Publication number: WO2015143315A1
Application number: PCT/US2015/021741
Authority: WO
Inventors: Roel MAES; Garry G. Miller; Diego RIBERA ALDAMA; Jon M. Lenhert
Original assignee: Saint-Gobain Performance Plastics Corporation
Priority date: 2014-03-21
Filing date: 2015-03-20
Publication date: 2015-09-24

Abstract

A lip seal includes a base member and a lip member. The base member can include a polymer and can encapsulate the lip member. A method of forming a lip seal includes providing a lip member and forming a base member that encapsulates the lip member. The method can include injection molding a thermoplastic polymer to encapsulate a portion of the lip member.

Description

LIP SEAL HAVING A BASE MEMBER AND A LIP MEMBER

FIELD OF THE DISCLOSURE

The present disclosure relates to lip seals, and more particularly to lip seals having a base member and a lip member.

RELATED ART

A rotary or reciprocating machine can feature an enclosed internal mechanism that drives a shaft that will, in some cases, pass through the housing of the machine on one or both ends. In such cases, a lip seal can be disposed near an exit point to retain a lubricating fluid, such as oil or grease, in the housing as well as keep out contaminants, such as moisture and dust. The lip seal can have an outer diameter that provides a seal against the housing, and a sealing lip that provides a seal against the shaft. The sealing lip should exert a radial load on the shaft that provides sufficient sealing properties without excessive friction losses or wear. There exists a need for a lip seal having improved sealing properties. There also exists a need to simplify the process of manufacturing of a lip seal.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments are illustrated by way of example and are not limited in the

accompanying figures.

FIG. 1 includes a cross-sectional illustration of a lip seal according to this disclosure; FIG. 2 includes an illustration of a top view of a lip member according to this disclosure;

FIG. 3 includes an illustration of a top view of another lip member according to this disclosure;

FIG. 4 includes an illustration of a top view of another lip member according to this disclosure;

FIGs. 5 and 6 include illustrations of a top view and a side view, respectively, of another lip member according to this disclosure;

FIGs. 7 and 8 include top views of illustrations of lip members according to this disclosure;

FIGs. 9 and 10 include cross-sectional illustrations of lip members according to this disclosure;

FIG. 11 includes a cross-sectional illustration of a lip seal according to this disclosure; FIG. 12 includes a cross-sectional illustration of a lip seal according to this disclosure; and FIG. 13 includes a cross-sectional illustration of a lip seal according to this disclosure. Skilled artisans appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the invention.

DETAILED DESCRIPTION

The following description in combination with the figures is provided to assist in understanding the teachings disclosed herein. The following discussion will focus on specific implementations and embodiments of the teachings. This focus is provided to assist in describing the teachings and should not be interpreted as a limitation on the scope or applicability of the teachings. However, other embodiments can be used based on the teachings as disclosed in this application.

The terms "comprises," "comprising," "includes," "including," "has," "having" or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a method, article, or apparatus that comprises a list of features is not necessarily limited only to those features but may include other features not expressly listed or inherent to such method, article, or apparatus. Further, unless expressly stated to the contrary, "or" refers to an inclusive-or and not to an exclusive-or. For example, a condition A or B is satisfied by any one of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present).

Also, the use of "a" or "an" is employed to describe elements and components described herein. This is done merely for convenience and to give a general sense of the scope of the invention. This description should be read to include one, at least one, or the singular as also including the plural, or vice versa, unless it is clear that it is meant otherwise. For example, when a single item is described herein, more than one item may be used in place of a single item. Similarly, where more than one item is described herein, a single item may be substituted for that more than one item.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The materials, methods, and examples are illustrative only and not intended to be limiting. To the extent not described herein, many details regarding specific materials and processing acts are conventional and may be found in textbooks and other sources within the sealing arts. The lip seal can have a base member and a lip member. The base member can include a polymer and encapsulate the lip member. In an embodiment, the lip member can include holes near the perimeter of the lip member. In another embodiment, the perimeter of the lip member can have a polygonal shape. The method of forming the lip seal can include providing a lip member and forming a base member that encapsulates the lip member. For example, the method can include injection molding a thermoplastic polymer to encapsulate a portion of the lip member. Thus, the lip seal can be formed using a relatively simple process geared for high volume production. The concepts are better understood in view of the embodiments described below that illustrate and do not limit the scope of the present invention.

FIG. 1 illustrates a side view of a cross section of a portion of an embodiment of the lip seal 10 including a lip member 20 and a base member 30. As illustrated in FIG. 1, the lip member 20 can be encapsulated by the base member 30. The lip member 20 has a lip perimeter 21 and can extend radially inwardly from the lip perimeter 21 to a lip edge 23. From a side view, the lip member 20 can curve to the lip edge 23. Further, the lip member 20 can have a major surface 25 and an opposing major surface 27.

The lip member 20 can have a thickness T calculated by measuring the distance between the major surfaces 25 and 27 of the lip member 20. In an embodiment, the thickness T of the lip member is such that it can exert sufficient force against the shaft. For example, the thickness T can be at least 0.25 mm, at least 0.35 mm, at least 0.45 mm, at least 0.55 mm, at least 0.65 mm, or at least 0.75 mm. In another embodiment, the thickness T of the lip member is such that the lip member is flexible enough to reduce friction and wear. For example, the thickness T may be no greater than 1.45 mm, no greater than 1.35 mm, no greater than 1.25 mm, no greater than 1.15 mm, or no greater than 1.05 mm. Moreover, in a particular embodiment, the lip member can have a thickness in a range of any of the above maximum and minimum values, such as from 0.45 mm to 1.45 mm, 0.65 to 1.25 mm, or 0.75 to 1.05 mm.

FIG. 2 is a top-view illustration of the major surface 25 of the lip member 20 before the lip member 20 is partially encapsulated by the base member 30 (not illustrated in FIG. 2). From this view, a portion of the major surface 27 near the lip edge 23 defines a space 24 that is adapted to fit a shaft. As illustrated in FIG. 2, the space 24 can be an annular space that is adapted to fit a radial shaft.

In the embodiment as illustrated in FIG. 2, the lip member 20 has coupling holes 29 that extend into the thickness T of the lip member from the major surface 25, the major surface 27, the lip perimeter 21, or any combination thereof. The coupling holes 29 can receive a portion of the base member 30 to assist in retaining the lip member 20 in the base member 30.

The coupling holes 29 can provide greater retention of the lip member 20 in the base member 30. In an embodiment, the number of coupling holes 29 in the lip member 20 can be at least two, at least four, or at least six. Although the lip member 20 can include a large number of coupling holes, a limit can be placed on the number of coupling holes for simplifying manufacturing or maintaining the structural integrity of the lip member 20. In another embodiment, the number of coupling holes in the lip member 20 may be no greater than twenty, no greater than fifteen, or no greater than ten. Moreover, the lip member 20 can have a number of coupling holes 29 that falls within a range of any of the maximum and minimum values described above, such as in a range of two to twenty coupling holes, four to fifteen coupling holes, or six to ten coupling holes. In a more particular embodiment, the lip member 20 has eight holes. However, the lip member 20 can include only one coupling hole 29. In an embodiment, the holes 29 extend at least partially through the thickness T of the lip member or extend through the entire thickness T of the lip member.

As illustrated in FIG. 2, the coupling holes 29 can be spaced apart from the lip perimeter 21. In an embodiment, the distance one or more of the coupling holes 29 is spaced from the perimeter can be at least 2 mm, at least 5 mm, or at least 11 mm. The coupling holes 29 can be spaced close enough to the lip perimeter 21 so that the coupling holes 29 can receive a portion of the base member. In another embodiment, the distance one or more of the coupling holes 29 is spaced from the lip perimeter 21 may be no greater than 35 mm, no greater than 25 mm, or no greater than 15 mm. As compared to one another, the coupling holes 29 may be substantially the same distance from the lip perimeter 21 or one or more holes 29 may be a different distance from the lip perimeter 21 as compared to another one of the coupling holes 29.

Different shapes of coupling holes may be used for the lip member. In FIG. 2, the coupling holes 29 have a circular shape. The coupling holes can have a polygonal shape, such as a triangle, a rectangle (for example, a square), a hexagon, or an octagon. In another embodiment, the coupling holes may be elliptical. In a further embodiment, irregular or other shapes may be used. FIG. 3 includes an illustration of a lip member 30 similar to lip member 20 except that the coupling holes 29 are replaced by coupling holes 39 that have a semicircular shape. In another embodiment, the coupling holes 29 may be replaced by holes that have a crescent shape. After reading this specification, skilled artisans will be able to determine shapes for the holes to be used in a particular application.

FIG. 4 includes a top-view illustration of another embodiment of a lip member 40 before being encapsulated by a base member. As illustrated in the embodiment of FIG. 4, the lip member 40 can include coupling holes 49 at the lip perimeter 41. In such an embodiment, the coupling holes 49 are only partially enclosed by the lip member 40 such that the coupling holes 49 extend from the lip perimeter 41 inwardly toward the space 24 of the lip member 40. Each of the coupling holes 49 has a width 492 at the lip perimeter 41 that is narrower than a width at a location spaced away from the lip perimeter 41, such as the width 494. The coupling holes 49 at the lip perimeter 41 may provide better retention in the base member when the coupling holes 49 are such that the width at location spaced apart from the lip perimeter 41 is greater than the width at the lip perimeter 41. In the embodiment as illustrated in FIG. 4, the width 494 is greater than the width 492. For example, in the particular embodiment illustrated in FIG. 4, the lip member 41 can have a dove tail feature at the perimeter that includes the coupling holes 49. In another embodiment, other shapes for the holes at the lip perimeter may be used if needed or desired for a particular application.

FIGs. 5 and 6 include a top view illustration and a side view illustration, respectively, of another embodiment of a lip member 50 before being encapsulated by a base member. In this embodiment, the coupling holes 59 are slots extend from the lip perimeter 51 towards the space 24 between surfaces 25 and 27. The coupling holes are covered at surfaces 25 and 27 and open at the lip perimeter 51. Each of the holes 59 have a sufficient width to allow the polymer of the base member to flow into it during injection molding.

The shape of the lip perimeter can be adapted to fit many different applications. For example, the lip perimeter can have a shape that improves ease of installation or resistance to rotational movement. As illustrated in FIGs. 2 to 5, the lip perimeter can have a polygonal shape, particularly an octagon. The lip perimeter can have other polygonal shapes, such as a triangle, a square, a rectangle, a pentagon, a hexagon, or a heptagon. In a particular embodiment, the polygonal shape has at least three sides, has at least four sides, has at least five sides, has at least six sides, has at least seven sides, or has at least eight sides. In a further embodiment, the polygonal shape has no greater than twelve sides, no greater than eleven sides, no greater than ten sides, or no greater than nine sides. Moreover, a certain embodiment of the perimeter can have a polygonal shape having a number of sides in a range of any of the above maximum and minimum values, such as in a range of three to twelve sides, five to eleven sides, or six to ten sides. FIGs. 7 and 8 illustrate further embodiments of other lip members before being encapsulated. In FIG. 7, a lip member 70 has a lip perimeter 71 that has a circular shape. In FIG. 8, a lip member 80 has a lip perimeter 81 that has an elliptical shape. In a further embodiment (not illustrated), the lip perimeter can have an irregular shape to fit a specific application. Although coupling holes are not pictured in FIGs. 6 and 7, any lip member described herein can include any of the holes as previously described.

Further, a surface of the lip member can include an etched portion in addition to, or instead of, coupling holes. The etched portion refers to a portion of the surface of the lip seal that has been etched by an etchant. The etchant can include a sodium-based etchant.

In an embodiment, the etched portion has a greater surface roughness Ra than portions of the surface of the lip member that are not etched. In a particular embodiment, the surface roughness Ra of the etched portion is greater than the surface roughness of the non-etched portion by at least two times, by at least three times, by at least four times, or by at least five times.

The etched portion can promote adhesion of the base member to the lip member but can interfere with the sealing properties of the lip member. Thus, in an embodiment, a surface including an etched portion is configured such that when the lip seal is applied to the shaft, a non-etched portion is nearer to the shaft than the etched portion.

The surface of the lip member facing the shaft can include enhancements adapted to retain lubricant, such as adapted to collect small amounts of leakage that pass the initial seal and entrain it such that it can be fed back into the sealing area. The enhancements can include one or more of ribs, indents, protrusions, or any combination thereof. FIGs. 9 and 10 illustrate cross-sectional views of embodiments of lip members including the enhancements, cut along an axial plane before being encapsulated by a base member (not illustrated). As illustrated in FIG. 9, the enhancements can include protrusions 105 on a portion of major surface 27 of the lip member 90 near edge 23. In an embodiment, the protrusions 105 are manufactured by making a spiral cut along the surface 27. The spiral cut can form a thread along the surface 27 that pumps the oil away from the lip. As illustrated in FIG. 10, the enhancements can include indents 115 on a portion of major surface 27 of the lip member 100 near edge 23. In an embodiment, the indents 115 are manufactured by embossing the surface 27.

Any of the lip members previously described can include a polymer. The polymer can be described in terms of its properties. For example, the polymer of the lip member can have a desired Vicat softening point temperature sufficient to endure the injection molding environment without being deformed or damaged. A Vicat softening point is used determine the softening point for materials that have no definite melting point, such as plastics. The Vicat softening point is the temperature at which the material is penetrated to a depth of 1 mm by a flat-ended needle with a 1 mm² circular cross section. In a certain embodiment, the polymer of the lip member can have a Vicat softening point temperature sufficient to maintain its structure during the molding process. For example, the polymer of the lip member can have a Vicat softening point temperature of at least 80°C, at least 90°C, at least 100°C, or at least 110°C. Although no particular upper limit is set on the Vicat softening point temperature, the polymer of the lip member may have a Vicat softening point temperature of no greater than 425°C, no greater than 375°C, or no greater than 325°C. Moreover, in a particular embodiment, the polymer of the lip member can have a Vicat softening point temperature in a range of any of the maximum or minimum values discussed above, such as in a range of 80°C to 425°C, 90°C to 375°C, or 100°C to 325°C. In more particular embodiment, the polymer of the lip member can have a Vicat softening point temperature that is greater than the melting point of the polymer of the base member, as discussed later in more detail.

The polymer of the lip member can be described in terms of its composition. For example, the polymer can include a fluoropolymer. In a particular embodiment, the fluoropolymer can include a polytetrafluoroethylene (PTFE), a perfluoroalkoxy polymer (PFA), a fluorinated ethylene -propylene polymer (FEP), a ethylene-tetrfluoroethylene copolymer (ETFE), a polychlorotrifluoroethylene (PCTFE), a polyvinylidene fluoride (PVDF), a polyvinylfluoride (PVF), or any combination thereof. In another embodiment, the polymer of the lip member can include a polymer other than a fluoropolymer. For example, the lip member can include a high density polyethylene (HDPE), a high molecular weight polyethylene (HMWPE), an ultra high molecular weight polyethylene (UHMWPE), a cross- linked polyethylene (PEX), a high density cross-linked polyethylene (HDXLPE), or any combination thereof.

The polymer can be present in the polymer material in an amount that provides a reasonable wear rate under mild conditions, such as a low pressure difference across the lip seal. In an embodiment, the amount of polymer in the polymer material of the lip member can be reduced to accommodate a filler, which can improve the lubrication and wear rate of the lip member under more extreme conditions. For example, the polymer may be present in the polymer material of the lip member in an amount of no greater than 98 wt%, no greater than 95 wt%, or even no greater than 92 wt%. In a further embodiment, the polymer can be present in the polymer material of the lip member in an amount sufficient to maintain the structural integrity of the lip member. For example, the polymer can be present in the polymer material of the lip member in an amount of at least 60 wt%, at least 70 wt%, at least 85 wt%, or even at least 88 wt%. Moreover, the polymer can be present in the polymer material of the lip member in an amount in a range of any of the maximum and minimum values described above, such as in the range of 70 to 98 wt%, 80 to 95 wt%, or even 85 to 92 wt%. The above values are based on the total weight of the seal main body.

Any of the previously described lip members can also include a filler. For example, the filler can improve the lubrication and wear rate of the lip member. In an embodiment, the filler can be present in the material in an amount of at least 2 wt%, at least 5 wt%, or at least 8 wt%. Too much filler may adversely affect the sealing properties or structural integrity of the lip member, such as by making the lip member too stiff. Lip seals depend on the lip member to stretch and be resilient. Thus, the fillers are present in the polymer material in an amount of no greater than 40 wt%, no greater than 30 wt%, no greater than 25 wt%, no greater than 15 wt%, or no greater than 12 wt%. Moreover, in yet another embodiment, the filler can be present in the lip member in an amount within a range of values described above, such as from 2 wt% to 30 wt%, 5 wt% to 25 wt%, or even from 8 wt% to 15 wt%. The above values are based on the total weight of the lip member. In a further embodiment, the filler is present in the polymer material such that the lip member has an elongation-at-break of 15% to 25%, as measured according to ASTM D 412.

In an embodiment, the filler can include a metallic filler, a glass fiber, a polymer powder, a ceramic, an aramid, a carbon, a molybdenum disulfide, or any combination thereof. An example the filler includes a wallonstonite, a mica, a barium sulfate, a tungsten disulfide, a nickel powder, a polyphenyl sulfide (PPS), a crosslinked polytetrafluoroethylene, a polyimide (PI), a polyether ether ketone (PEEK), a bronze, a silicon carbide, a boron nitride, a carbon fiber, a powder coated with various metallic, a polybenzimidazole (PBI), or any combination thereof.

The base member and its interface with the lip member will now be described. As stated previously, the base member encapsulates the lip member. In an embodiment, the base member is injection molded to encapsulate the lip member and does not exist in final form independent of the base member. FIGs. 1 and 11 illustrate the structure of the base member 30 and the interface between the lip member 20 and the base member 30. In the cross- sectional view illustrated in FIG. 1, the axial plane cuts through a portion of the lip member 20 having a hole 29. FIG. 11 illustrates a cross-sectional view of the lip seal illustrated in FIG. 1 in which the axial plane cuts through a portion of the lip member that does not show the coupling hole 29.

The base member 30 has a major surface 31 and an opposing major surface 32, and the base member 30 can have a proximal side surface 33 and an opposing distal side surface 34. Further, the shape of the base member can vary depending on the desired application.

The base member 30 can encapsulate the lip member 20 between the major surfaces

31 and 32 such that the lip member extends from the base member through the proximal side surface 33. A wall 35 and an opposing wall 36 can extend into the thickness of the base member 30 from the proximal side surface 33. The walls 35 and 36 can extend in directions parallel or non-parallel to each other and in directions parallel or non-parallel to the major surfaces 31 and 32. Further, the 35 and 36 walls can be connected by a third wall 37, defining a cavity that encapsulates a portion of the lip member 20.

In an embodiment, the base member can fill one or more coupling holes in the lip member resulting in a protrusion extending through at least a portion of the lip member. FIG. 1 illustrates a protrusion 38 of the base member that fills a coupling hole 29. The protrusion

38 and the base member 30 can be of a single construction, such as a single monolithic piece.

The protrusion 38 can extend from the wall 35, the wall 36, or both. As illustrated in FIG. 1, the protrusion 38 can extend through the entire thickness T of the lip member such that the protrusion 38 connects wall 35 to wall 36 through the coupling holes 29. In another embodiment, the protrusions can extend through only a portion of the thickness T of the lip member. The number and shape of the protrusions can be determined by the number and shape of the coupling holes.

The base member can include a polymer. The polymer of the base member can be a moldable polymer, such as an injection-moldable polymer or a transfer-moldable polymer. As discussed below in connection with embodiments of the method, the polymer of the base member is capable of being injection molded or transfer molded to encapsulate the lip member.

The polymer of the base member can be described in terms of its plastic point temperature. For example, to avoid deforming the lip member during injection molding, the polymer of the base member can be a polymer having a plastic point temperature that is less than the Vicat softening point temperature of the polymer of the lip member. In an embodiment, the polymer may have a plastic point temperature of no greater than 400°C, no greater than 350°C, no greater than 300°C, or no greater 275°C. In another embodiment, the plastic point of the polymer of the base member can be high enough to withstand particular operating temperatures. For example, the plastic point temperature of the polymer of the base member can be at least 85°C, at least 95°C, at least 105°C, at least 115°C, at least 125°C, or at least 135°C. Moreover, the polymer of the base member can have a plastic point temperature that is in a range of any of the minimum and maximum plastic point temperature values discussed above, such as in a range of 85°C to 400°C, 105°C to 350°C, or even 125°C to 275°C.

The polymer of the base member can be described in terms of its flowability characteristics. For example, the polymer of the base member can be a non-newtonian fluid at injection. As such, the polymer of the base member can have a melt viscosity, at 200°C and 50% relative humidity, of at least 10 cP, at least 20 cP, at least 30 cP, at least 40 cP, at least 50 cP, at least 60 cP, at least 70 cP, at least 80 cP, at least 90 cP, or at least 100 cP. In a further embodiment, the melt viscosity of the polymer of the base member is not so high that it becomes difficult to control during injection molding. For example, the polymer of the base member may have a melt viscosity, at 200°C and 50% relative humidity, of no greater than 1,000 cP, no greater than 900 cP, no greater than 800 cP, no greater than 700 cP, no greater than 600 cP, or no greater than 500 cP. Moreover, the polymer of the base member can have a melt viscosity, at 200°C and 50% relative humidity, in a range of any of the minimum and maximum values described above, such as in a range of 10 cP to 1,000 cP, 40 cP to 800 cP, 80 cP to 600 cP, or 100 cP to 500 cP.

The polymer of the base member can be described in terms of its composition. For example, the polymer of the base member can include a fluoropolymer, a polyketone, a polyether, a polyester, a polyurethane, a polyamide, a polyolefin, a styrenic block copolymer, or any combination thereof. In an embodiment, the polymer of the base member can include a nitrogen-containing polymer. As stated previously, the polymer of the base member can include a fluoropolymer. The fluoropolymer can include a polytetrafluoroethylene (PTFE), a perfluoroalkoxy polymer (PFA), a fluorinated ethylene-propylene polymer (FEP), an ethylene-tetrfluoroethylene copolymer (ETFE), polychlorotrifluoroethylene (PCTFE), a polyvinylidene fluoride (PVDF), a polyvinylfluoride (PVF), or any combination thereof. As stated previously, the polymer can include a polyketone. The polyketone can include a polyether ether ketone (PEEK), a polyether ketone (PEK), a polyaryl ether ketone (PAEK), a polyether ketone ketone (PEKK), or any combination thereof. In an embodiment, the polymer of the base member is a liquid crystal polymer.

A separate component can be disposed on the base member. For example, a band can be disposed on the distal side surface of the base member, on the proximal side surface of the base member, or on both the distal and proximal side surfaces of the base member. When there is more than one band disposed on the seal main body, as illustrated in FIG. 12, the bands can include different materials or the same material. For example, the band can include a metal or an elastomer, such as an elastomer o-ring. In FIG. 12, the base member 230 includes a band 234, which is an elastomer o-ring disposed on the distal side surface 34 of the base member, and a band 233, which is an annular metal ring disposed on the proximal side surface 33 of the base member. The band 233 can be a metal wire. To minimize the effect of extreme temperatures on the lip seal, the material of the band, such as the material of the band 233, can be selected to have a thermal expansion coefficient that is greater than the thermal expansion coefficient of the seal main body. Further, in an embodiment, the band can have a thermal expansion coefficient that matches the thermal expansion coefficient of the seal housing. Additionally, the material of the elastomer o-ring can provide structural support for the lip seal and can limit or prevent rotation of the seal in the housing.

FIG. 13 illustrates another embodiment where an elastomer layer 60 can be disposed between the base member and the lip member to assist in retaining the lip member in the base member, if needed or desired.

The lip seal as a whole can be described in terms of its leakage rate. As used herein, leakage rate is a measure of the amount of a fluid that passes through the lip seal over a specified amount of time per unit of shaft circumference, for example ml/hr/mm, tested at a specified pressure and shaft speed.

When tested at a shaft surface velocity of 8.7 meters per second (m/s) and a pressure difference across the lip seal of 70 kPa, the lip seal may have a leakage rate of no greater than 0.1 mL/hr/mm, no greater than 0.09 mL/hr/mm, no greater than 0.08 mL/hr/mm, no greater than 0.07 mL/hr/mm, no greater than 0.06 mL/hr/mm, no greater than 0.05 mL/hr/mm, no greater than 0.04 mL/hr/mm, no greater than 0.03 mL/hr/mm, no greater than 0.02 mL/hr/mm, or no greater than 0.01 mL/hr/mm. Although it may be desirable to have no leakage at all, a small amount of leakage may occur, such as at a rate of at least 0.0001 mL/hr/mm, at least 0.001 mL/hr/mm, at least 0.002 mL/hr/mm, at least 0.003 mL/hr/mm, at least 0.004 mL/hr/mm, or at least 0.005 mL/hr/mm. Moreover, the lip seal can have a leakage rate value in a range of any of the minimum and maximum values described above, such as in a range of 0.0001 to 0.1 mL/hr/mm, 0.001 to 0.09 mL/hr/mm, or 0.005 mL to 0.08 mL/hr/mm.

The method of forming a lip seal can include providing a lip member and a polymer, and encapsulating the lip member with the polymer. In an embodiment, the lip member is in accordance with a lip member described in this disclosure, and the polymer is in accordance with a polymer of the base member described in this disclosure. The polymer can be in any form, such as grains or powders.

Encapsulating the lip member with the polymer can include injection molding the polymer to form a base member that encapsulates the lip member. The injection molding can include providing a mold, disposing the lip member in the mold, and injecting the polymer into the mold.

During the injecting of the polymer into the mold, the polymer can reach a peak temperature that is less than the Vicat softening point of the lip member. For example, the peak temperature of the polymer during injection molding may be no greater than 320°C, no greater than 300°C, no greater than 280°C, no greater than 260°C, no greater than 240°C, no greater than 220°C, or no greater than 200°C. In another embodiment, the peak temperature is sufficient to reach a desired viscosity to inject into a mold. For example, the peak temperature can be at least 60°C, at least 80°C, at least 100°C, at least 120°C, at least 140°C, at least 160°C, at least 180°C, or at least 200°C. Moreover, the peak temperature of the polymer of the base member can be in a range of the minimum and maximum values described above, such as in a range of from 60°C to 320°C, from 100°C to 300°C, from 140°C to 280°C, or from 200°C to 260°C.

A molding pressure during injection molding can be at least 1 MPa, at least 10 MPa, at least 50 MPa, at least 60 MPa, at least 70 MPa, at least 80 MPa, at least 90 MPa, or at least 100 MPa. Further, the molding pressure during injection molding may be no greater than 1,000 MPa, no greater than 500 MPa, no greater than 450 MPa, no greater than 400 MPa, no greater than 250 MPa, no greater than 300 MPa, no greater than 250 MPa, or no greater than 200 MPa. Moreover, the molding pressure during injection molding can be in a range of any of the minimum and maximum values described above, such as in a range of from 1 MPa to 1,000 MPa, from 10 MPa to 500 MPa, from 50 MPa to 300 MPa, or from 100 MPa to 200 MPa.

After the polymer is injected into the mold, the polymer can harden over the lip member to form an overmolded lip seal including a lip member encapsulated by a base member. The resulting article is ejected from the mold and can be applied to a shaft, such as a radial shaft.

As discussed above, the base member can be made from a moldable material. Thus, the method can be geared toward high volume production and toward lip seals having a variety of shapes and sizes. In addition, a lip seal in accordance with this disclosure can have improved sealing properties, such as an improved leakage rate.

Many different aspects and embodiments are possible. Some of those aspects and embodiments are described below. After reading this specification, skilled artisans will appreciate that those aspects and embodiments are only illustrative and do not limit the scope of the present invention. Embodiments may be in accordance with any one or more of the items as listed below.

Item 1. A lip seal comprising:

a lip member; and

a base member including a polymer that encapsulates a portion of the lip member, wherein a part of the base member extends through a thickness of the lip member.

Item 2. A lip seal comprising:

a lip member having a perimeter in a form of a polygonal shape; and

a base member including a polymer that encapsulates a portion of the lip member.

Item 3. A lip seal comprising:

a lip member having two opposing major surfaces, one of the major surfaces including an etched portion; and

a base member including a polymer that encapsulates a portion of the lip member, the base member contacting the etched portion of the lip member.

Item 4. A lip seal comprising:

a lip member; and

a base member including a polymer that encapsulates a portion of the lip member, wherein the lip seal has a leakage rate of no greater than 0.1 mL/hr/mm when tested at a shaft surface velocity of 8.7 m s and a pressure difference across the lip seal of 70 kPa.

Item 5. A method of forming a lip seal, the method comprising:

providing a lip member; and

injection molding a thermoplastic polymer to form a base member that encapsulates the lip member.

Item 6. The method of item 4, further comprising inserting the lip member into a mold without deforming or without flexing the lip member.

Item 7. The method of items 5 or 6, wherein during injection molding, the thermoplastic polymer reaches a peak temperature, and the lip member includes a polymeric material that has a Vicat softening point temperature that is greater than the peak temperature. Item 8. The method of any one of items 5-7, wherein the peak temperature is at least 60°C, at least 80°C, at least 100°C, at least 120°C, at least 140°C, at least 160°C, at least 180°C, or at least 200°C.

Item 9. The method of any one of items 5-8, wherein the peak temperature is no greater than 320°C, no greater than 300°C, no greater than 280°C, no greater than 260°C, no greater than 240°C, no greater than 220°C, or no greater than 200°C.

Item 10. The method of any one of items 5-9, wherein the peak temperature is in a range of from 60°C to 320°C, from 100°C to 300°C, from 140°C to 280°C, or from 200°C to 260°C.

Item 11. The method of any one of items 5-10, wherein a molding pressure during injection molding is at least 1 MPa, at least 10 MPa, at least 50 MPa, at least 60 MPa, at least 70 MPa, at least 80 MPa, or at least 90 MPa, or at least 100 MPa.

Item 12. The method of any one of items 5-11, wherein a molding pressure during injection molding is no greater than 1,000 MPa, no greater than 500 MPa, no greater than 450 MPa, no greater than 400 MPa, no greater than 250 MPa, no greater than 300 MPa, no greater than 250 MPa, or no greater than 200 MPa.

Item 13. The method of any one of items 5-12, wherein a molding pressure during injection molding is in a range of from 1 MPa to 1,000 MPa, from 10 MPa to 500 MPa, from 50 MPa to 300 MPa, or from 100 MPa to 200 MPa.

Item 14. The method of any one of items 5-13, wherein the thermoplastic polymer has a melt viscosity, at 200°C and 50% relative humidity, of at least 10 cP, at least 20 cP, at least 30 cP, at least 40 cP, at least 50 cP, at least 60 cP, at least 70 cP, at least 80 cP, at least 90 cP, or at least 100 cP.

Item 15. The method of any one of items 5-14, wherein the thermoplastic polymer has a melt viscosity, at 200°C and 50% relative humidity, of no greater than 1,000 cP, no greater than 900 cP, no greater than 800 cP, no greater than 700 cP, no greater than 600 cP, or no greater than 500 cP.

Item 16. The method of any one of items 5-15, wherein the thermoplastic polymer has a melt viscosity, at 200°C and 50% relative humidity, in a range of from 10 cP to 1,000 cP, from 40 cP to 800 cP, from 80 cP to 600 cP, or from 100 cP to 500 cP.

Item 17. The method of any one of items 5-16, wherein the thermoplastic polymer is a non-newtonian fluid during injection molding. Item 18. The lip seal or method of any one of the preceding items, wherein the base member comprises a fluoropolymer, a polyketone, a polyether, a polyester, a polyurethane, a polyamide, a polyolefin, a styrenic block copolymer, or any combination thereof.

Item 19. The lip seal or method of any one of the preceding items, wherein the base member comprises a nitrogen-containing polymer.

Item 20. The lip seal or method of any one of the preceding items, wherein the base member comprises a fluoropolymer.

Item 21. The lip seal or method of item 20, wherein the fluoropolymer comprises perfluoroalkoxy polymer (PFA), fluorinated ethylene-propylene polymer (FEP), ethylene - tetrfluoroethylene copolymer (ETFE), polychlorotrifluoroethylene (PCTFE), polyvinylidene fluoride (PVDF), polyvinylfluoride (PVF), or any combination thereof.

Item 22. The lip seal or method of any one of the preceding items, wherein the base member comprises a polyketone.

Item 23. The lip seal or method of any of the preceding items, wherein the base member comprises a polyether ether ketone (PEEK), a polyether ketone (PEK), a polyaryl ether ketone (PAEK), a polyether ketone ketone (PEKK), or any combination thereof.

Item 24. The lip seal or method of any one of the preceding items, wherein the base member comprises a liquid crystal polymer.

Item 25. The lip seal or method of any one of the preceding items, wherein the lip member comprises a material that has a Vicat softening point that is greater than a plastic point temperature of the polymer of the base member.

Item 26. The lip seal or method of any one of the preceding items, wherein the lip member comprises a fluoropolymer.

Item 27. The lip seal or method of any one of the preceding items, wherein the lip member comprises a polytetrafluoroethylene (PTFE), a perfluoroalkoxy polymer (PFA), a fluorinated ethylene -propylene polymer (FEP), a ethylene-tetrfluoroethylene copolymer (ETFE), a polychlorotrifluoroethylene (PCTFE), a polyvinylidene fluoride (PVDF), a polyvinylfluoride (PVF), or any combination thereof.

Item 28. The lip seal or method of any one of items 1-25, wherein the lip member comprises a polymer other than a fluoropolymer.

Item 29. The lip seal or method of any one of items 1-25 and 28, wherein the lip member comprises a high density polyethylene (HDPE), a high molecular weight polyethylene (HMWPE), an ultra high molecular weight polyethylene (UHMWPE), a cross- linked polyethylene (PEX), a high density cross-linked polyethylene (HDXLPE), or any combination thereof.

Item 30. The lip seal or method of any one of the preceding items, wherein the lip member comprises a filler.

Item 31. The lip seal or method of any one of the preceding items, wherein the lip member comprises a filler in an amount, by total weight of the lip member, of no greater than 40 wt%, no greater than 30 wt%, no greater than 25 wt%, no greater than 15 wt%, or no greater than 12 wt%.

Item 32. The lip seal or method of any one of the preceding items, wherein the lip member comprises a filler in an amount, by total weight of the lip member, of at least 2 wt%, at least 4 wt%, at least 6 wt%, at least 8 wt%, or at least 10 wt%, based on a total weight of the lip member.

Item 33. The lip seal or method of any one of the preceding items, wherein the lip member comprises a filler in an amount, by total weight of the lip member, in a range of 2 wt% to 30 wt%, 4 wt% to 25 wt%, or 8 wt% to 15 wt%.

Item 34. The lip seal or method of any one of the preceding items, wherein the lip seal further comprises an elastomer layer disposed between the base member and the lip member.

Item 35. The lip seal or method of any one of the preceding items, wherein:

the lip member has a coupling hole extending through a thickness of the lip member; and a part of the base member extends through the coupling hole of the lip member.

Item 36. The lip seal or method of item 35, wherein the coupling hole is spaced apart from a perimeter of the lip member.

Item 37. The lip seal or method of item 35, wherein:

the coupling hole extends from a perimeter of the lip member into a thickness of the lip member; and

the coupling hole has a diameter at the perimeter and a maximum diameter in the thickness of the lip member that is greater than the perimeter dimension.

Item 38. The lip seal or method of item 35, wherein the lip member has a dove tail feature at the perimeter that includes the coupling hole.

Item 39. The lip seal or method of any one of the preceding items, wherein the lip member comprises at least one coupling hole, at least two coupling holes, at least three coupling holes, at least four coupling holes, at least five coupling holes, at least six coupling holes, at least seven coupling holes, or at least eight coupling holes. Item 40. The lip seal or method of any one of the preceding items, wherein the lip member comprises no more than twenty coupling holes, no more than fifteen coupling holes, no more than twelve coupling holes, or no more than ten coupling holes.

Item 41. The lip seal or method of any one of the preceding items, wherein the lip member comprises a number of coupling holes in a range of from one to twenty, from five to fifteen, or from six to ten.

Item 42. The lip seal or method of any one of the preceding items, wherein the lip member has a perimeter that is in the form of a polygonal shape having at least three sides, at least four sides, at least five sides, at least six sides, at least seven sides, or at least eight sides.

Item 43. The lip seal or method of any one of the preceding items, wherein the lip member has a perimeter that is in the form of a polygonal shape having no greater than twelve sides, no greater than eleven sides, no greater than ten sides, no greater than nine sides, or no greater than eight sides.

Item 44. The lip seal or method of any one of the preceding items, wherein the lip member has a perimeter that is in the form of a polygonal shape having a number of sides in a range of from three sides to twelve sides, from five sides to eleven sides, or from six sides to ten sides.

Item 45. The lip seal or method of any one of the preceding items, wherein the lip member has a perimeter that is circular or elliptical.

Item 46. The lip seal or method of any one of the preceding items, wherein the lip seal has a leakage rate of no greater than 0.09 mL/hr/mm, no greater than 0.08 mL/hr/mm, no greater than 0.07 mL/hr/mm, no greater than 0.06 mL/hr/mm, no greater than 0.05 mL/hr/mm, no greater than 0.04 mL/hr/mm, no greater than 0.03 mL/hr/mm, no greater than 0.02 mL/hr/mm, or no greater than 0.01 mL/hr/mm, when tested at a shaft surface velocity of 8.7 m/s and a pressure difference across the lip seal of 70 kPa.

Item 47. The lip seal or method of any one of the preceding items, wherein the lip seal has a leakage rate of at least 0.0001 mL/hr/mm, at least 0.001 mL/hr/mm, at least 0.002 mL/hr/mm, at least 0.003 mL/hr/mm, at least 0.004 mL/hr/mm, or at least 0.005 mL/hr/mm, when tested at a shaft surface velocity of 8.7 m/s and a pressure difference across the lip seal of 70 kPa.

Item 48. The lip seal or method of any one of the preceding items, wherein the lip seal has a leakage rate in a range of 0.0001 to 0.1 mL/hr/mm, 0.001 to 0.09 mL/hr/mm, or 0.005 to 0.08 mL/hr/mm, when tested at a shaft surface velocity of 8.7 m s and a pressure difference across the lip seal of 70 kPa. Item 49. The lip seal or method of any one of the preceding items, wherein the fluid used to measure the leakage rate is a fluid having a viscosity of at least 0.60 cP at 50°C.

Item 50. The lip seal or method of any one of the preceding items, wherein the lip member has two opposing major surfaces and one of the major surfaces includes an etched portion; and

the base member contacts the etched portion of the lip member.

Item 51. The lip seal or method of item 50, wherein the etched portion has a greater surface roughness Ra than portions of the surface of the lip member that are not etched.

Item 52. The lip seal or method of item 51, wherein the surface roughness Ra of the etched portion is greater than the surface roughness of the non-etched portion by at least two times, by at least three times, by at least four times, or by at least five times.

Item 53. The lip seal or method of item 51, wherein the major surface including the etched portion also includes a non-etched portion, and, when the lip seal is applied to the shaft, the non-etched portion is nearer to the shaft than the etched portion.

EXAMPLES

The concepts described herein will be further described in the following examples, which do not limit the scope of the invention described in the claims. Some of the parameters below have been approximated for convenience.

Each of Example 1, Example 2, and Comparative Example 1 describe the leakage rate of sample lip seals. The sample lip seals were mounted in a test chamber on a radial wear sleeve having a circumference of approximately 104 mm. Oil, spray nozzles, and electric heaters were placed in the test chamber. The chamber was regulated with ambient air or nitrogen. Any leakage that passed through the lip seal was collected directly or within a weighted absorbent material, and then post-test quantified by volume or weight gain.

The testing in each of the Examples and Comparative Example included a preliminary sequence and two principal sequences. The preliminary sequence ran for about 2 hours at 5,000 rpm without a pressure difference across the lip seal. The first and second sequences each ran for about 8 hours each at 5,000 rpm with a pressure difference across the lip seal of 70 kPa. A new lip seal was tested for each sequence.

Example 1

The sample lip seals used in Example 1 were manufactured by inserting a PTFE lip member into a mold and injection molding a PA66 nylon polymer at a temperature of no greater than 120°C, and then allowing the polymer to cool to form a base member that encapsulates the lip member. The results of the testing for Example 1 are included in Table 1 below.

Table 1

Example 2

The sample lip seals used in Example 2 were manufactured by inserting a PTFE lip member into a mold and injection molding a polyketone (Fluoroloy A22 brand, Saint-Gobain Performance Plastics Corporation, Garden Grove, California) at a temperature of no greater than 120°C, and then allowing the polymer to cool to form a base member that encapsulates the lip member. The results of the testing for Example 2 are included in Table 2 below.

Table 2

Comparative Example 1

The sample lip seals used in Comparative Example 1 were conventional lip seals manufactured by inserting a PTFE lip member into a metal casing and clamping the metal casing over the lip member. The results of the testing for Comparative Example 1 are included in Table 3 below.

Table 3

According to Tables 1 and 2, the sample lip seals of Examples 1 and 2 including an injection molded base member were able to complete the first and second sequences with, if any, only slight wetting and no collectable leakage, whereas, according to Table 3, the conventional lip seals of Comparative Example 1 allowed a collectable amount of leakage with a pressure difference of 70 kPa across the lip seal. Thus, based on the Examples and Comparative Example described above, the lip seals described herein having an injection molded base member encapsulating the lip member have an improved leakage rate over conventional lip seals having a metal casing clamped over a lip member.

Note that not all of the activities described above in the general description or the examples are required, that a portion of a specific activity may not be required, and that one or more further activities may be performed in addition to those described. Still further, the order in which activities are listed is not necessarily the order in which they are performed.

Benefits, other advantages, and solutions to problems have been described above with regard to specific embodiments. However, the benefits, advantages, solutions to problems, and any feature(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential feature of any or all the claims.

The specification and illustrations of the embodiments described herein are intended to provide a general understanding of the structure of the various embodiments. The specification and illustrations are not intended to serve as an exhaustive and comprehensive description of all of the elements and features of apparatus and systems that use the structures or methods described herein. Separate embodiments may also be provided in combination in a single embodiment, and conversely, various features that are, for brevity, described in the context of a single embodiment, may also be provided separately or in any subcombination. Further, reference to values stated in ranges includes each and every value within that range. Many other embodiments may be apparent to skilled artisans only after reading this specification. Other embodiments may be used and derived from the disclosure, such that a structural substitution, logical substitution, or another change may be made without departing from the scope of the disclosure. Accordingly, the disclosure is to be regarded as illustrative rather than restrictive.

Claims

WHAT IS CLAIMED IS:

1. A lip seal comprising:

a lip member; and

2. A lip seal comprising:

a lip member having a perimeter in a form of a polygonal shape; and

3. A lip seal comprising:

4. A lip seal comprising:

a lip member; and

a base member including a polymer that encapsulates a portion of the lip member, wherein the lip seal has a leakage rate of no greater than 0.1 mL/hr/mm when tested at a shaft surface velocity of 8.7 m/s and a pressure difference across the lip seal of 70 kPa.

5. A method of forming a lip seal, the method comprising:

providing a lip member; and

6. The method of claim 5, further comprising inserting the lip member into a mold without deforming or without flexing the lip member.

7. The method of any one of claims 5-6, wherein the thermoplastic polymer is a non-newtonian fluid during injection molding.

8. The lip seal or method of any one of the preceding claims, wherein the base member comprises a fluoropolymer, a polyketone, a polyether, a polyester, a polyurethane, a polyamide, a polyolefin, a styrenic block copolymer, or any combination thereof.

9. The lip seal or method of any one of the preceding claims, wherein the base member comprises a liquid crystal polymer.

10. The lip seal or method of any one of the preceding claims, wherein:

11. The lip seal or method of claim 10, wherein the coupling hole is spaced apart from a perimeter of the lip member.

12. The lip seal or method of claim 10, wherein: the coupling hole extends from a perimeter of the lip member into a thickness of the lip member; and

13. The lip seal or method of any one of the preceding claims, wherein the lip member has a perimeter that is in the form of a polygonal shape having at least three sides, at least four sides, at least five sides, at least six sides, at least seven sides, or at least eight sides.

14. The lip seal or method of any one of the preceding claims, wherein the lip seal has a leakage rate of no greater than 0.09 mL/hr/mm, no greater than 0.08 mL/hr/mm, no greater than 0.07 mL/hr/mm, no greater than 0.06 mL/hr/mm, no greater than 0.05 mL/hr/mm, no greater than 0.04 mL/hr/mm, no greater than 0.03 mL/hr/mm, no greater than 0.02 mL/hr/mm, or no greater than 0.01 mL/hr/mm, when tested at a shaft surface velocity of 8.7 m/s and a pressure difference across the lip seal of 70 kPa.

15. The lip seal or method of any one of the preceding claims, wherein

the lip member has two opposing major surfaces and one of the major surfaces includes an etched portion; and

the base member contacts the etched portion of the lip member.