Lubricant free, reduced mass, free-piston, Stirling machine having reciprocating piston drivingly linked to rotary electromagnetic transducer moving in rotational oscillation
View Patent ↗A free-piston Stirling machine drivingly coupled to at least one rotary electromagnetic transducer. At least one pulley is oriented in a plane of a reciprocating piston connecting rod. At least one motion translating drive link connects the connecting rod to the pulley by at least two straps so that the pulley moves in rotationally oscillating motion. The two straps extend along an arcuate surface of the pulley into connection to the piston rod at two spaced locations. The pulley is linked to a rotary electromagnetic transducer so that both move in rotationally oscillating motion. Preferably a piston spring resonates the piston at an operating frequency of the Stirling machine and a torsion spring resonates the pulley in rotational oscillation at the operating frequency of the Stirling machine.
1. A drivingly coupled free-piston Stirling machine and at least one rotary electromagnetic transducer and having a casing, the Stirling machine including at least one piston reciprocating in its cylinder and having a connecting rod fixed to the piston, the coupled free-piston Stirling machine and rotary electromagnetic transducer more particularly comprising:
(a) at least one pulley oriented in a plane of the connecting rod and having an axis of rotation perpendicular to the plane, the pulley having an arcuate peripheral surface that extends adjacent to the connecting rod;
(b) at least one motion translating drive link drivingly connecting the connecting rod to the pulley by at least two straps and driving or being driven by the pulley in rotationally oscillating motion of the pulley,
(i) one strap being fixed to a side of the pulley that is distal from the piston and extending in a first direction (clockwise or counter clockwise) along a peripheral arcuate surface of the pulley into fixed connection with the connecting rod at a location along the piston rod that is nearer the piston than the pulley axis of rotation,
(ii) another strap being fixed to a side of the pulley that is proximal to the piston and extending opposite the first direction along a peripheral arcuate surface of the pulley into fixed connection with the connecting rod at a location along the piston rod that is farther from the piston than the pulley axis of rotation; and
(c) a mechanical drive link between each pulley and a rotary electromagnetic transducer and moving the rotary electromagnetic transducer and the pulley in rotationally oscillating motion.
2. A coupled free-piston Stirling machine and rotary electromagnetic transducer in accordance with claim 1 and further comprising:
(a) a piston spring linked to a piston, the piston spring resonating the piston and masses rigidly connected to the piston at an operating frequency of the Stirling machine; and
(b) a torsion spring linked to each pulley and resonating the pulley and masses rigidly connected to the pulley in rotational oscillation at the operating frequency of the Stirling machine.
3. A coupled free-piston Stirling machine and rotary electromagnetic transducer in accordance with claim 2 , wherein
(a) the free-piston Stirling machine is an alpha configuration machine including four said pistons and connecting rods that are thermodynamically interconnected for operating at phase angles of 0°, 90°, 180°, and 270°, the pistons being physically arranged to locate the piston rods of a first pair of pistons, that are operating at a 0° and 180°, in a first plane and to locate the piston rods of a second pair of pistons, that are operating at a 90° and 270°, in a second plane;
(b) a first said pulley positioned in the first plane between the piston rods of the first pair of pistons;
(c) a second said pulley positioned in the second plane between the piston rods of the second pair of pistons;
(d) at least four motion translating drive links, each drive link as previously recited and drivingly connecting a connecting rod to the adjacent pulley in its plane.
4. A coupled free-piston Stirling machine and rotary electromagnetic transducer in accordance with claim 3 , wherein each strap is mounted in an elastically pretensioned state.
5. A coupled free-piston Stirling machine and rotary electromagnetic transducer in accordance with claim 4 , wherein each pulley is fixed to a different torsion spring and each torsion spring extends from its associated pulley to a fixed connection to the casing.
6. A coupled free-piston Stirling machine and rotary electromagnetic transducer in accordance with claim 5 wherein each torsion spring is a rod or bar.
7. A coupled free-piston Stirling machine and rotary electromagnetic transducer in accordance with claim 4 wherein the straps that are fixed to a side of the pulley that is distal from the pistons are formed from a single length of strap material that extends a total of substantially 180° along a peripheral arcuate surface of the pulley to which they are connected and the straps that are fixed to a side of the pulley that is proximal to the pistons are formed from a single length of strap material that extends a total of substantially 180° along a peripheral arcuate surface of the pulley to which they are connected.
8. A coupled free-piston Stirling machine and rotary electromagnetic transducer in accordance with claim 7 wherein there is a second rotary electromagnetic transducer, one rotary electromagnetic transducer drivingly connected to one of said pulleys and the second rotary electromagnetic transducer drivingly connected to the other of said pulleys.
9. A coupled free-piston Stirling machine and rotary electromagnetic transducer in accordance with claim 8 wherein there is a third rotary electromagnetic transducer drivingly connected between the two pulleys.
10. A coupled free-piston Stirling machine and rotary electromagnetic transducer in accordance with claim 8 wherein the resonating piston spring linked to each piston comprises a pair of planar springs each extending between a fixed position relative to the casing to connection to its associated piston rod, the pair of planar springs for each piston being positioned on opposite sides of the pulley that is adjacent the piston rod to which the pair of planar springs is connected.
11. A coupled free-piston Stirling machine and rotary electromagnetic transducer in accordance with claim 10 wherein each piston rod has a flat planar surface facing its adjacent pulley, each flat planar surface positioned and extending along the piston rod for seating against the straps that are connected to the piston rod on which the surface is formed.
12. A coupled free-piston Stirling machine and rotary electromagnetic transducer in accordance with claim 11 wherein each torsion spring is a rod or bar.
13. A coupled free-piston Stirling machine and rotary electromagnetic transducer in accordance with claim 12 wherein there is a third rotary electromagnetic transducer drivingly connected between the two pulleys.
14. A coupled free-piston Stirling machine and rotary electromagnetic transducer in accordance with claim 1 , wherein the free-piston Stirling machine is a beta configuration Stirling machine.
15. A coupled free-piston Stirling machine and rotary electromagnetic transducer in accordance with claim 14 and further comprising:
(a) a piston spring linked to a piston, the piston spring resonating the piston and masses rigidly connected to the piston at an operating frequency of the Stirling machine; and
(b) a torsion spring linked to each pulley and resonating the pulley and masses rigidly connected to the pulley in rotational oscillation at the operating frequency of the Stirling machine.
16. A coupled free-piston Stirling machine and rotary electromagnetic transducer in accordance with claim 15 wherein:
(a) a second said pulley is positioned on the opposite side of the piston rod from the first said pulley;
(b) a second said motion translating drive link drivingly connects the connecting rod to the second pulley.
17. A coupled free-piston Stirling machine and rotary electromagnetic transducer in accordance with claim 16 , wherein each strap is mounted in an elastically pretensioned state.
18. A coupled free-piston Stirling machine and rotary electromagnetic transducer in accordance with claim 16 wherein each torsion spring is a rod or bar.