Internal-combustion engines – Poppet valve operating mechanism – Spring
Reexamination Certificate
1999-07-26
2001-08-14
Walberg, Teresa (Department: 3742)
Internal-combustion engines
Poppet valve operating mechanism
Spring
C123S090650, C251S337000
Reexamination Certificate
active
06273045
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The subject invention relates to a valve spring retainer for operatively retaining a return spring on the stem of a poppet valve in an internal combustion engine.
2. Description of the Prior Art
The use of valve spring retainers in internal combustion engines is well known. Self locking retainers are known wherein the retainer automatically locks on the valve stem as the retainer is pressed onto the valve stem by reaction with the spring during operation. Such a retainer typically includes a retainer flange extending annularly about a hole on a central axis for engaging the top of a spring. A ring is disposed below the flange and extends about the axis for surrounding a valve stem. An inner portion extends cylindrically about the axis and axially between the ring and the flange. A skirt portion is spaced radially from and extends cylindrically about the inner portion and depends axially from a root diameter adjacent the flange to a distal end diameter. A plurality of slots extend radially from the hole and divide the flange and the portions into sectors leaving the ring to interconnect the sectors. During operation the spring reacts against a retainer flange and urges the sectors to rotate into engagement with the stem to lock onto the stem. The spring is centered by the skirt. Such assemblies are shown in U.S. Pat. No. 5,293,848 to Rich et al and applicant's previous U.S. Pat. No. 4,879,978; 5,143,351; 5,226,229; and 5,255,640.
The slots dividing the retainer into sectors must be narrow to prevent the sectors from rotating excessively relative to one another because the sectors must react against one another in the circumferential direction to force the hole into locking engagement with the valve stem. Yet, it is difficult to fabricate a retainer with narrow slots due to the complexities of molding.
SUMMARY OF THE INVENTION AND ADVANTAGES
The subject invention provides an improved valve spring retainer for operatively retaining a return spring on a stem of a poppet valve in an internal combustion engine. The retainer includes a retainer flange extending annularly about and radially from a hole on a central axis to an outer periphery for engaging the top of a spring. A ring is disposed below the flange and extends about the axis for surrounding a valve stem. An inner portion extends cylindrically about the axis and axially between the ring and the flange. A plurality of slots extend radially from the hole to the periphery and divide the flange and the inner portion into sectors leaving the ring to interconnect the sectors. The retainer is characterized by the slots extending radially at a wide width and each of the sectors including a limit projection at the periphery to define a narrow width whereby the limit projections limit relative annular rotation between the sectors.
The invention also provides a method of fabricating such a retainer which is characterized by forming a limit projection at the periphery of each of the sectors to define a narrow width which is more narrow than the wide width.
Accordingly, the subject invention provides a retainer and method of fabricating same wherein the retainer is fabricated in an open position with wide slots to accommodate the molding process yet provides the requisite limiting of relative rotation between the retainer sectors during operation.
REFERENCES:
patent: 2855915 (1958-10-01), Norton
patent: 4201162 (1980-05-01), Speckhart
patent: 4665869 (1987-05-01), Hinz et al.
patent: 4829952 (1989-05-01), Barker
patent: 4838218 (1989-06-01), Sato et al.
patent: 5275376 (1994-01-01), Rich
patent: 5343835 (1994-09-01), Rhodes
patent: 5381765 (1995-01-01), Rhodes
patent: 5619961 (1997-04-01), Diggs
patent: 5873563 (1999-02-01), Hoving, III
Dahbour Fadi H.
Howard & Howard
Walberg Teresa
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