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US 4,283,995 AGranted
Reciprocating engines
AssigneeThe United States of America as represented by the Administrator of the National Aeronautics and Space Administration
InventorJames W. Akkerman
Life of this patent
Estimating the term…
Abstract
In a hydrazine powered engine, an intake valve arrangement for positively controlling the opening and closing of the poppet valve in a hot gas cylinder, the poppet valve being operated by the piston and gas pressure only. The poppet valve uses a pneumatic "spring" which holds the poppet valve against the piston while the valve is opened and closed. To accomplish this, a poppet valve is slidably mounted in a "pneumatic spring" chamber which reaches a pressure approaching the gas supply pressure and, during the opening of the valve, the "spring" chamber retains enough pressure to hold the poppet valve onto the piston. In addition, the bottom of the poppet valve can have a suction cup type configuration to hold the poppet valve on the piston during the down stroke.
Claims5
In a piston operating engine, a new and improved gas charging valve arrangement comprising:
- a cylinder containing a piston reciprocable within said cylinder between top center and bottom center positions, said cylinder having an upper transverse head cap provided with an inlet port including a valve seat disposed about the perimeter of said port;
- a high pressure plenum chamber means disposed on the side of said transverse head cap opposite the piston;
- means adapted to supply high pressure gas to said plenum chamber means;
- fluid communication means including gas valve means movable between open and closed positions for placing high pressure gas in said plenum chamber in communication with said piston and cylinder when in the open position thereby inducing a pressure drop in said plenum chamber, said gas valve means including a valve element having an upper cylindrical stem portion, a reduced diameter portion providing an annular shoulder means for sealingly engaging said valve seat when the gas valve means is in the closed position, and a lower pedestal portion engageable by said piston when at and near its top center position whereby said valve element is lifted by said piston from the valve seat to place said gas valve means in the open position;
- pneumatic gas chamber means disposed on the side of said transverse head cap which is opposite the piston, said pneumatic gas chamber means including an upper pneumatic spring body member having a blind bore opening downwardly and a juxtaposed lower valve body member having a guide bore aligned and communicating with said blind bore, said guide bore receiving said cylindrical stem portion of the valve element for sliding movement therein;
- a restricted flow passage for communicating high pressure gas between said plenum chamber means and said pneumatic gas chamber means whereby gas pressure in the pneumatic gas chamber means acts on the valve element in opposition to the force exerted on the valve element by said piston,
- said flow passage being of sufficiently small dimension to restrict the flow of gas therefrom upon the opening of said gas valve means such that the pressure in said pneumatic gas chamber means drops at a slower rate than the pressure in said plenum chamber on opening of said gas valve means so as to temporarily exceed the plenum chamber pressure for the period when the valve element is moved to open position and at the time the valve element is moved to closed position and the pneumatic gas chamber means thereby acts as a pneumatic spring retaining said valve element in constant contact with said piston and tracking the movement of the piston throughout said period.
4 more elements
In a piston operating engine, a new and improved gas charging valve arrangement comprising:
- a plurality of cylinders each containing a piston reciprocable therein between top center and bottom center positions, each said cylinder having an upper transverse head cap provided with an inlet port including a valve seat disposed about the perimeter of said port;
- a high pressure plenum chamber means disposed on the side of the transverse head caps opposite the piston;
- means adapted to supply high pressure gas to said plenum chamber means;
- communication means including gas valve means movable between open and closed positions for placing high pressure gas in said plenum chamber in communication with said pistons and cylinders when in the open position and thereby inducing a pressure drop in said plenum chamber, each said gas valve menas including a valve element having an upper cylindrical stem portion, a reduced diameter postion providing an annular shoulder means for sealingly engaging said valve seat when the gas valve means is in closed position, and a lower pedestal portion engageable by a piston when at and near its top center position whereby the valve element is lifted by the piston from the valve seat to place said gas valve means in the open position;
- a plurality of pneumatic gas chamber means disposed on the side of said transverse head cap which is opposite the pistons, each said pneumatic gas chamber means being defined by a first body member means having a cylindrical blind bore and a second body member having an enlarged diameter bore aligned with said blind bore and forming a guide bore receiving the cylindrical stem portion of a valve element for sliding movement therein;
- restricted flow passage means including a plurality of flow passages for communicating high pressure gas between said plenum chamber means and said pneumatic gas chamber means whereby the gas pressure in the pneumatic gas chamber means acts on said valve elements in opposition to the force exerted on the valve elements by said piston,
- each said flow passage being of sufficiently small dimension to restrict the flow of gas therefrom upon the opening of said gas valve means such that the pressure in said pneumatic gas chamber means drops at a slower rate than the pressure in said plenum chamber on opening of said gas valve means so as to temporarily exceed the plenum chamber pressure for the period when the valve element is moved to open position and at the time of valve element closing to thereby act as pneumatic springs retaining said valve elements in constant contact with said pistons and tracking the movement of the pistons throughout said period.
4 more elements
Dependencies are inferred from the claim text.