Leaky gas spring valve for preventing piston overstroke in a free piston stirling engine
AssigneeSunPower Corporation
InventorWilliam T. Beale
Life of this patent
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Abstract
The invention is for the prevention of power piston overstroke in a Stirling cycle machine, wherein there is a gas valve which vents the gas spring acting upon the displacer. The valve and its accompanying control system switch on a leak in the gas spring to vent the gas spring upon piston stroke beyond a selected magnitude. This reduces the spring constant which reduces the displacer amplitude and phase lead over the power piston and thereby reduces power output.
Claims10
In a free piston Stirling machine, including a displacer reciprocally mounted in a working gas space and engaged by a gas spring and having a piston mounted for reciprocation in a cylinder and acted upon by the working gas, the improvement comprising:
- (a) means for detecting piston amplitude beyond a selected amplitude during its reciprocation;
- and
- (b) valve means connected in communication with the gas spring for permitting the connection of the gas spring to another gas space;
- and
- (c) actuating means connected between the detecting means and the valve means for opening the valve means in response to detection of piston amplitude in excess of said selected amplitude to reduce the spring constant and make the gas spring more lossy and thereby increase its damping and for closing the valve means in response to the absence of piston amplitude in excess of said selected amplitude.
A method for preventing piston overstroke in a free piston Stirling machine including a displacer reciprocally mounted in a working gas space and engaged by a gas spring and having a piston acted upon by the working gas, the improved method comprising:
- effecting the venting of the gas spring to reduce its effective spring constant and increase its damping lossiness in response to piston amplitude beyond a selected amplitude.
Dependencies are inferred from the claim text.