|Publication number||USRE40764 E1|
|Application number||US 11/711,913|
|Publication date||Jun 23, 2009|
|Filing date||Feb 27, 2007|
|Priority date||Feb 25, 2004|
|Also published as||CA2497377A1, DE602005017841D1, EP1568857A1, EP1568857B1, US6901902|
|Publication number||11711913, 711913, US RE40764 E1, US RE40764E1, US-E1-RE40764, USRE40764 E1, USRE40764E1|
|Inventors||Tigree Milam Butcher, Milton Loman Griswold|
|Original Assignee||Freudenbery-Nok General Partnership|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (20), Referenced by (1), Classifications (11), Legal Events (3)|
|External Links: USPTO, USPTO Assignment, Espacenet|
The present invention relates to valve stem seals, and more particularly to a two-piece valve stem seal preferably for use in an internal combustion engine, but applicable to other valve stem sealing applications.
The primary function of a valve stem steal in an internal combustion engine, for example, is to allow adequate lubrication at the valve stem/valve guide interface while minimizing internal oil consumption. Valve stem seals of this general type are known in the prior art, as shown in U.S. Pat. Nos. 5,558,056; 4,947,811; 4,909,202; 3,554,562; and 3,554,180, for example. In addition, a two-piece valve stem seal of this general type is shown in U.S. Pat. No. 5,775,284, which is assigned to the same assignee as the present application and which has overlapping inventorship with the present invention.
A valve stem seal assembly generally includes a rigid shell structure and a seal body, with the assembly having a generally hollow interior adapted to receive a valve stem guide. Typically the shell structure supports the shell body, which surrounds the valve stem in order to essentially “meter” the provision of oil for lubricating the valve guide's inner diameter and the outer diameter of the valve stem. At the same time, however, the valve stem seal serves to minimize the amount of oil that can be drawn into the combustion chamber to pass to the engine's exhaust. If the rigid shell is not properly located in relation to the valve guide, the sealing element might not properly seat upon the valve stem thus causing non-uniform pressures at the cylinder and valve guide, undesirable wear patterns on the seal or valve stem and unpredictable lubrication of the valve stem and valve guide.
Some prior art valve stem seals have had histories of cracked flanges during vehicle operations due to shock waves and internal stresses at the flange portion of the valve stem seal. Some of such prior art valve stem seals also have not had sufficiently flat flange portions, thus further increasing the likelihood of flange cracking.
In addition some prior art two-piece valve stem seal assemblies have been difficult to assemble by their manufacturers, as well as presenting further difficulties to consequent manufacturers assembling the finished valve stem seal assembly into an engine or other device using such assemblies.
These problems sometimes have resulted from the need to assemble or insert the “upper” generally cylindrical shell portion of the vale stem seal assembly “upwardly” into the “lower” generally cylindrical shell portion from the “bottom” of the lower shell portion, i.e., from the end of the lower shell portion that bears against the engine's cylinder head or other such member of a device through which the valve stem extends. This difficulty sometimes results from the “upper”, end portion of the lower shell portion having a relatively small bearing surface (against which the insertion forces are directed) when compared to the bearing surface at the lower end of the lower shell portion.
With regard to the consequent manufacturer's assembly of the finished valve stem seal assembly into an engine or other device, the vigorous nature of various automated parts feeding and assembling apparatus can sometimes cause two-piece valve stem seal assemblies to separate during such operations. This of course can cause malfunction, or at least temporarily halt or slow down, such consequent assembly operations.
Although the two-piece valve stem seal assembly described and claimed in the above-mentioned U.S. Pat. No. 5,775,284 performs well and successfully overcomes various short-comings of the prior art, the present invention seeks to further improve upon that design and overcome these and other disadvantages of the prior art.
Other objectives of the present invention are: to provide a valve stem seal which will offer greater resistance to the forces exerted by the valve spring which causes the flange to crack; to prevent the sealing member of the assembly from separating from the valve guide; and to provide a flanged valve stem seal that will not rotate about the valve guide due to the rotational motion of the valve spring, thus minimizing torsional stresses on the valve's return spring and reducing wear.
According to the present disclosure, a two-piece valve stem seal assembly is provided for use in a valve containing device having a valve with a valve stem. A first shell includes a radially inwardly extending flange and a radially outwardly extending flange. A second shell includes a radially outwardly extending seat and a radially inwardly extending flange. A portion of the first shell extends axially within an inner surface of the second shell. The second shell further includes an axially extending engagement portion engaging a portion of an outer surface of the first shell in an interference fit therebetween. A resilient sealing body is supported by the first shell and has an opening therethrough for receiving a valve stem in sealing contact therewith.
AAccording to another aspect, a two-piece valve stem seal assembly according to the present invention for use in a valve-containing device having a valve with a valve stem thereon (such as an internal combustion engine, for example) which is a variation upon and an improvement over that of U.S. Pat. No. 5,775,284, generally includes a generally hollow first cylindrical shell (so-called “upper” shell) having a radially inwardly extending flange adjacent an axially outer end of the first shell and a radially outwardly extending flange adjacent an axially inward end of the first shell, and a generally hollow second cylindrical shell (so-called “lower” shell) having a radially outwardly extending seat adjacent an axially outer end thereof and a generally axially-extending engagement portion adjacent an axially inward end thereof. A portion of said first shell extends axially within an inner surface of the second shell, with the axially-extending engagement portion of the first shell grippingly engaging a portion of an outer surface of the first shell in an interference fit therebetween.
A resilient sealing body is supported by the first shell, said resilient sealing body having an opening therethrough for receiving the valve stem in sealing contact therewith when the valve stem seal assembly is assembled into the engine or other valve-containing device. The second shell can also include second a radially inwardly-extending flange adjacent an axially inward end thereof and generally adjacent the axially-extending engagement portion (on either axial side thereof).
Preferably, the improved two-piece valve stem seal includes rigid cylindrical shells, preferably composed of a metal or metal-containing material. The resilient sealing body can be composed of rubber or other resilient elastomers and is preferably bonded directly to the preferred metal casing of the first cylindrical shell. This allows the sealing body in many embodiments to remain stationary with the first cylindrical shell thus reducing wear of the sealing body's seal lip and extending product life. Such bonded resilient seal body also allows for easier seal installation and removal, greater support of the sealing body's sealing lip and superior control of oil metering for lubrication of the valve stem.
Additional objects, advantages, and features of the present invention will become apparent from the following description and the appended claims, taken in conjunction with the accompanying drawings.
Referring initially to
The valve stem seal assembly 10 also includes a resilient sealing member or body 18 that is preferably directly bonded to the rigid cylindrical shell 14. The inner surface of the first shell 14 engages the exterior surface of a second generally rigid shell 16. The second shell 16 is also of a metal-containing material, but which may be made of ceramic or other relatively hard and rigid materials. Although the second shell 16, like the first shell 14, is preferably generally hollow and cylindrical in shape, other shapes may be used depending on the needs of the specific application for the valve stem seal assembly. The resilient sealing body 18 is preferably made of rubber or a rubber-containing material but may alternately be composed of other resilient elastomers or plastic materials capable of seal in the given environment.
In the preferred embodiments shown in
The resilient sealing body 18 is preferably directly molded to the end wall 20 of the rigid cylindrical shell 14 and may be molded to the end wall 20 such that it completely surrounds the end wall 20. However, other variations may be used for connecting the sealing body 18 to the rigid cylindrical shell 14, such as by an interference fit, adhesives, epoxies or other known connections capable of creating a relatively fixed joint between the cylindrical shell 14 and the resilient sealing body 18. A rubber or other resilient elastomeric pad 28 (which can be integral with the sealing body 18) is also molded onto the interior wall of the rigid cylindrical shell 14 and is in contact with the valve guide 24 upon installation in an automotive cylinder head (or engine block assembly portion) 26. The preferred interference fit between the first cylindrical shell 14 and the second cylindrical shell 16 creates a retaining force to urge the rubber pad 28 into constant contact with the valve guide assembly 24.
The resilient sealing body 18 also preferably includes an annular sealing lip 38 at an “upper” or axially outer portion to seal with the valve stem 40 during engine operation. The resilient sealing body 18 also includes a concave groove 42 along an upper portion for receiving and retaining a spring member 12 (preferably a garter spring). The spring member 12 resiliently urges the resilient annular sealing lip 38 toward its contact with the valve stem 40 during engine operation. This spring member 12 and the annular sealing lip 38 function to control the amount of oil passing between the valve stem 40 and the valve stem seal assembly 10.
A “vertical” or axially-extending wall 30 of the second cylindrical shell 16 eliminates, or at least substantially minimizes, the possibility of the sealing body 18 of the valve stem assembly 10 separating from the valve guide 24 during operation of the vehicle. The second cylindrical shell 16 also includes a radially inwardly-extending flange 34 adjacent its axially inner or “upper” end and a radially outwardly-extending flange or seat 36 adjacent its axially outer or “lower” end. The second shell 16 thus provides a barrier of protection which protects the valve spring 32 from wearing against the cylinder head 26 during engine operation.
The second cylindrical shell 16 is manufactured separately from the first cylindrical shell 14, thus making it possible to reduce the occurrence of internal stresses in the second cylindrical shell 16. This also allows the second cylindrical shell's finger or seat 36 to have a flatness that can be more accurately controlled, which in turn will reduce the frequency of flange cracking. However, after such initial separate manufacturing operations, the second first shell 16 14 is typically inserted axially “upwardly” into the interior of the first second shell 14 16 from the first second shell 14's 16's axially inner end adjacent the flange or seat 36, which results in insertion forces being directed toward and against the axially outer (or “upper”) end of the first shell 14 rather from the more substantial flange or seat 36, which has a greater load-bearing surface, if the insertion direction could be reversed, as in the embodiments of the present invention shown in
Prior valve stem seal assemblies were forcibly rotated by action of the valve spring 32 during engine operation, which would subject the sealing lip 38 to torsional stresses, as well as axial forces from the reciprocating valve stem 40. However, with the preferred embodiments of the valve stem seal assembly 10 shown in
In various applications of the present invention, this gripping engagement of the engagement portion 152 (or other engagement portions in other embodiments) with the first shell 114 (or other first shells in other embodiments) may or may not be so close or tight that it prevents the first and second shells 114 and 116 from being rotatable with respect to each other, as discussed above in connection with
Because of the interference fit between the radially outwardly-extending flange 122 adjacent the axially inward (“lower”) end of the first shell 114 and the axially inwardly-extending flange 134 (with the engagement portion 152 thereon), and because of the gripping engagement of the engagement portion 152, the valve stem seal assembly 110 eliminates or at least substantially minimizes the tendency for the first and second shells 114 and 116 to become axially separated or disengaged from each other (either partially or completely) during assembly of the finished valve stem seal assembly 110 into an engine or other valve and valve stem-containing device. Regardless of this interference fit, however, the first shell 114 can be inserted axially “downwardly” from the axially inward end of the second shell 116 during assembly of the two components, which allows the flange or seat 136 to act as a load-bearing structure during such insertion, thus substantially eliminating the possibility of damage to either compound during such assembly. It should be noted that both of these advantages are provided by any of the various exemplary embodiments of the present invention illustrated in
Valve stem seal assembly 610 of
According to another aspect, a two-piece valve stem seal assembly according to the present invention for use in a valve-containing device having a valve with a valve stem thereon (such as an internal combustion engine, for example) which is a variation upon and an improvement over that of U.S. Pat. No. 5,775,284, generally includes a generally hollow first cylindrical shell (so-called “upper” shell) having a radially inwardly extending flange adjacent an axially outer end of the first shell and a radially outwardly extending flange adjacent an axially inward end of the first shell, and a generally hollow second cylindrical shell (so-called “lower” shell) having a radially outwardly extending seat adjacent an axially outer end thereof and a generally axially-extending engagement portion adjacent an axially inward end thereof. A portion of said first shell extends axially within an inner surface of the second shell, with the axially-extending engagement portion of the first shell grippingly engaging a portion of an outer surface of the first shell in an interference fit therebetween.
The foregoing discussion discloses and describes merely exemplary embodiments of the present invention for purposes of illustration only. One skilled in the art will readily recognize from such discussion, and from the accompanying drawings and claims, that various changes, modifications and variations can be made therein without departing from the spirit and scope of the invention as defined in the following claims.
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|Citing Patent||Filing date||Publication date||Applicant||Title|
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|International Classification||F16K41/08, F02N3/00, F16J15/32, F01L3/08|
|Cooperative Classification||F01L3/08, F01L2101/00, F16K41/08, F01L2101/02|
|European Classification||F16K41/08, F01L3/08|
|Oct 27, 2009||CC||Certificate of correction|
|Sep 6, 2012||FPAY||Fee payment|
Year of fee payment: 8
|Sep 8, 2016||FPAY||Fee payment|
Year of fee payment: 12