Internal-combustion engines – Poppet valve operating mechanism – Tappet
Reexamination Certificate
1999-07-20
2001-07-24
Walberg, Teresa (Department: 3742)
Internal-combustion engines
Poppet valve operating mechanism
Tappet
C123S188200, C123S188300
Reexamination Certificate
active
06263849
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
Not Applicable
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable
MICROFICHE APPENDIX
Not Applicable
BACKGROUND OF THE DISCLOSURE
The present invention relates generally to poppet valves for internal combustion engines, and more particularly, to a hollow poppet valve which is able to maintain a very high strength-to-weight characteristic. Although the present invention is adapted for use with many different types of hollow poppet valves, it is especially advantageous when used with an ultra light poppet valve, and will be described in connection therewith.
Internal combustion engine poppet valves have been commonly fabricated by machining, forging, or extruding a solid blank of high-strength, heat resistant metal, and then subjecting the blank to various finish machining and/or grinding operations. In some applications, performance requirements have made it necessary to provide a valve having a hollow stem into which a coolant, such as a sodium-potassium mixture, may be added during the fabrication process. Prior to the early 1990s, such hollow stems were formed by means such as drilling or extruding, or by forging the stem over a mandrel or a removable core, or by cold forming a tubular blank to a desired stem diameter, then shaping the fillet portion and then attaching separate cap and tip members.
A true ultra light engine poppet valve was first illustrated and described in U.S. Pat. No. 5,413,073, assigned to the assignee of the present invention and incorporated herein by reference. In the incorporated patent, the poppet valve comprises a stem element which includes an integral tip portion and a fillet portion, and a cap member which is welded to the fillet portion. Preferably, the stem including the fillet portion is fabricated by means of a deep drawing process wherein a starting blank in the form of a sheet-like disk is subjected to a plurality of cold drawing steps. The wall thickness of the stem, after the deep drawing is completed, is substantially less than that of the fillet portion or the tip portion. These steps result in an elongated flared cup wherein the outer edge of the flared fillet portion is substantially the thickness of the starting blank.
In the above-described ultra light poppet valve structure, the flared fillet region terminates in a generally radially extending edge or rim, which is received against a shoulder defined by a depression formed in the cap. The depth of the depression is approximately equal to the thickness of the fillet region. The cap is then welded to the outer edge of the flared fillet portion. Depending upon the configuration of the particular valve, the seat face of the poppet valve may be defined by either the fillet portion, or the cap member, or both.
Although the above-described poppet valve structure has proven itself to be generally satisfactory as far as fabrication and performance within the engine, it has become apparent that there are various engine applications which require an overall strength, and especially a fatigue strength, which is greater than can readily be accomplished by the above-described known and conventional method of joining the cap member to the fillet portion.
BRIEF SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide an improved hollow poppet valve having substantially improved fatigue strength and durability in the region of the weld of the fillet and cap member.
It is a related object of the present invention to provide an improved ultra light poppet valve which accomplishes the above-stated object and which is configured to substantially reduce the occurrence of stress concentration, resulting from a combination of the configuration and location of the weld joint between the cap member and the fillet portion.
The above and other objects of the invention are accomplished by the provision of a hollow poppet valve for use in an internal combustion engine, the poppet valve comprising a stem portion, a tip portion, a cap portion, and a flared fillet portion defining a transition region between the stem portion and the cap portion. The flared fillet portion has a wall thickness and a downwardly extending, generally cylindrical portion defining an inside fillet radius. One of the cylindrical portion and the cap portion defines a seat face adapted for sealing engagement with a valve seat. One of the cylindrical portion and the cap portion define a generally cylindrical internal surface and the other of the cylindrical portion and the cap portion define a generally cylindrical external surface, the internal and external surfaces being generally concentric and closely spaced apart.
The improved hollow poppet valve is characterized by the inside fillet radius being greater than about 0.3 times the wall thickness of the fillet portion. A weld consumes substantially the entire axial extent of the interface of the internal and external surfaces. The generally cylindrical portion and the cap portion cooperate to define an annular, horizontal interface disposed immediately radially inward from the interface of the internal and external surfaces.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
is a partly broken away, axial cross-section of a prior art hollow poppet valve.
FIG. 2
is a view similar to
FIG. 1
, illustrating an ultra light poppet valve made in accordance with the present invention.
FIG. 3
is a greatly enlarged, fragmentary axial cross-section illustrating the present invention in greater detail.
FIG. 4
is a view similar to
FIG. 3
, illustrating an alternative embodiment of the present invention.
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patent: 5771852 (1998-06-01), Heimann, Jr. et al.
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patent: 683057 (1952-11-01), None
Bonesteel David L.
Ecklund Leslie L.
Froehlich Michael J.
Killian Michael L.
Kline Philip M.
Dahbour Fadi
Eaton Corporation
Kasper L. J.
Walberg Teresa
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