Double acting stirling engine phase control
AssigneeMechanical Technology Incorporated
InventorDavid M. Berchowitz
Life of this patent
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Abstract
A mechanical device for effecting a phase change between the expansion and compression volumes of a double-acting Stirling engine uses helical elements which produce opposite rotation of a pair of crankpins when a control rod is moved, so the phase between two pairs of pistons is changed by +.psi. and the phase between the other two pairs of pistons is changed by -.psi.. The phase can change beyond .psi.=90.degree. at which regenerative braking and then reversal of engine rotation occurs.
Claims25
A power control for a double-acting Stirling engine having N pistons, where N is an even number greater than three, said pistons being normally operatively coupled to an output shaft with a phase angle of 360.degree./N between thermodynamically connected pistons;
- said power control comprising:
- means for driving said output shaft;
- means for linking said pistons to said driving means, including a linking mechanism connected between each piston and said driving means;
- first means for shifting in a first angular direction the phase angle between said driving means and linking mechanisms associated with a first set of N/2 pistons, said first set consisting of every other piston in the thermodynamic loop;
- and
- second means for shifting in a second opposite angular direction the phase angle between said driving means and linking mechanisms associated with a second set of N/2 pistons, said second set consisting of the remaining alternate pistons in the thermodynamic loop.
A power control and motion conversion mechanism for a double-acting Stirling engine having N pistons, where N is an even number greater than three, said pistons being thermodynamically coupled in series and mechanically connected through a drive train to an output driveshaft with a phase difference of 360.degree./N between adjacent pistons;
- said power control comprising:
- helically threaded means for operatively connecting said pistons to said output driveshaft, said helically threaded means including at least one helically threaded member coupled to N/2 of said pistons, and at least one other helically threaded member connected to said output shaft and threadedly engaged with said one helically threaded member;
- first means for shifting the phase position of N/2 pistons relative to the output shaft;
- second means for shifting the phase position of the other N/2 pistons relative to the output shaft;
- and
- said first and second shifting means including means for axially moving said helically threaded members relative to each other to produce a rotation of said helically threaded members relative to each other, whereby the phase of said pistons relative to each other is changed.
A power control for a double-acting Stirling engine having N pistons, where N is an even number equal to or greater than four, said pistons being operatively coupled through a drive train to an output drive shaft with a phase difference of 360.degree./N;
- said power control comprising:
- a shifter for shifting the phase position of at least N/2 pistons relative to the other N/2 pistons which operate in a Stirling cycle working space bounded in part by the first mentioned N/2 pistons, said shifter including a set of crank discs, one each linked to each of said pistons, for converting the reciprocating motion of said pistons to rotating motion and a helical member having a helical connection between said crank discs and said output driveshaft;
- means for relatively axially moving said helical connection to cause N/2 of said crank discs to rotate relative to the other N/2 crank discs and thereby change the phase position of the pistons linked thereto relative to each other.
A phase shift mechanism for a double-acting Stirling engine having N pistons where N is an even number equal to or greater than four, and the nominal phase relationship between thermodynamically coupled pistons is 360.degree./N, said mechanism including:
- two sets of N/2 motion conversion devices for converting between reciprocating motion of said pistons and rotating motion of an output shaft, said devices including a pair of crankshafts having N/2 cranks set 720.degree./N apart and each linked to a piston;
- each piston linked to one crankshaft being thermodynamically connected to two other pistons on the other crankshaft;
- gear means connected between each of said crankshafts and an output gear on said output shaft and shiftable to change the phase between said crankshafts and thereby change the phase relationship between said piston pairs an equal and opposite amount, whereby the output power from said pistons changes by approximately equal amounts.
A mechanism for shifting the phase between pistons in a double-acting Stirling engine having N pistons where N is an even integer greater than three, and the nominal phase relationship between thermodynamically coupled pistons is 360.degree./N, said mechanism including:
- two sets of N/2 motion conversion devices for converting between reciprocating motion of said pistons and rotating motion of an output shaft, said motion conversion devices each including an externally geared crank disc to which said pistons are linked;
- means for shifting the phase angle between said two sets of motion conversion devices relative to each other and thereby shift the phase of the thermodynamically connected pistons;
- said phase shifting means including a set of linking gears mounted on a shaft and engaged with said crank discs, said linking gears and said discs being movable relative to each other in opposite directions on discs coupled thermodynamically adjacent pistons to produce a relative phase change between thermodynamically adjacent pistons.
Dependencies are inferred from the claim text.