Valve spring mechanism

Abstract

The present invention relates to a valve spring mechanism suitable for use with the inlet or exhaust valves of an internal combustion engine. More specifically, the invention provides a valve spring mechanism for a poppet valve (101) which comprises a valve head (102) and a valve stem (104). The mechanism comprises a piston (109) and cylinder (108) arrangement in which the cylinder (108) surrounds a portion of the valve stem (104). The piston (109) is slidingly and sealingly mounted on the valve stem (104), and the piston (109) and cylinder (108) define a chamber (110). The mechanism also comprises force transmitting means for transmitting the force produced on the piston (109) by gas pressure within the chamber (110) to the valve stem (104); and a spring (113) operating on the piston (109) and the stem of the valve for applying a force to the stem of the valve tending to close the valve in the event of failure of gas pressure within the chamber (110). The spring (113) is positioned so that it is maintained in a compressed condition during normal operation of the valve spring mechanism as a result of gas pressure within the chamber (110).

Dependencies are inferred from the claim text.