Internal-combustion engines – Poppet valve operating mechanism – Spring
Reexamination Certificate
2002-03-11
2003-03-18
Denion, Thomas (Department: 3748)
Internal-combustion engines
Poppet valve operating mechanism
Spring
C123S090660, C123S090670, C123S188170, C267S158000, C251S337000
Reexamination Certificate
active
06532925
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to internal combustion engines, specifically springs for urging the intake and exhaust valves toward the closed position during operation of the engine.
2. Description of the Related Art
Use of springs to maintain internal combustion engine exhaust and intake valves in a closed position is known in the art. Springs which are used in existing engine combinations include coil springs, torsion bars, “hairpin” springs, and other such springs. However, such springs require an additional mechanism or retainer to keep the spring engaged with the exhaust and intake valves.
Previous methods of maintaining the spring engaged with the valve have included the use of additional flanges (U.S. Pat. No. 3,097,633) or the use of separate retainers (U.S. Pat. No. 972,434), as discussed above. These approaches require additional parts to be used with the valve spring, thereby increasing the cost and complexity of installation. When utilizing additional retainers for the spring, both the spring and retainer must be installed and connected rather than a single piece being installed.
What is needed is a valve spring which does not require additional elements or mechanisms such as retainers to maintain engagement with the exhaust and/or intake valves but which does provide ease of installation.
SUMMARY OF THE INVENTION
The present invention provides a bias element which urges the valves in an internal combustion engine toward their closed positions and includes a pair of arms and a bight portion connecting the two arms. Each arm has an aperture therein with at least one arm having an aperture that is keyhole-shaped, or having a first portion and second portion that is larger than the first portion. The arm which has the keyhole-shaped aperture is in operative biasing engagement with the head portion of a valve stem and the keyhole-shaped aperture engages the valve stem such that the first portion of the aperture is in locking engagement with the neck portion of the valve stem. The other arm engages the shank portion of the valve stem when the bias element is positioned on the head or block.
The bias element is a one-piece valve spring and retainer thereby overcoming the above described problems by reducing the number of parts machined or required and by eliminating the need for a separate spring retainer. Furthermore, by being only one piece, the spring and retainer may be installed easily in the engine without requiring that a spring be installed and then a separate retainer installed and attached to the spring.
In one form, the present invention provides a bias element for an internal combustion engine, which engine has an intake valve and an exhaust valve with each valve including a valve stem and having an open position and a closed position. Each valve stem has an end portion and a shank portion. The bias element urges the respective valve toward its closed position and includes a first arm, a second arm, and a bight portion therebetween. The first arm includes an aperture therein having a keyhole shape with a first portion and a second portion, in which the second portion is larger than the first portion. The first arm is in operative biasing engagement with the end portion of the valve stem with the first portion of the aperture being in locking engagement with the neck portion. The second arm has an aperture therein through which the shank portion of the valve stem extends.
The present invention further provides a method of assembling a valve spring and retainer to a valve or block wherein the spring and retainer have upper arm and a lower arm with each arm having an aperture therein, aligning the spring and retainer with a valve stem, sliding the valve stem through the apertures in both arms of the valve spring and retainer, and sliding the upper arm laterally to thereby lockingly engage the valve stem.
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Baker & Daniels
Chang Ching
Denion Thomas
Tecumseh Products Company
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