Patent ES-293813-A1 (ES)
Title: Hot-gas reciprocating machine
IPC: F25B9/14
Filed: 1963-11-23
Abstract: In a thermo-dynamic reciprocating machine, e.g. a hot-gas engine or a cold-gas refrigerator, comprising at least two pairs of units which each include a compression piston, a cooler, a regenerator, a freezer or heater and an expansion piston, the pistons are reciprocated by fluid pressure transmitted thereto from at least two pump units. A cold-gas refrigerating machine is described. As shown, two pump units I and II are mounted in V-formation on a common crankcase 1, each pump unit comprising pistons 8 and 13 reciprocating in separate closed cylinders. Two pairs of cooling units are provided, of which one pair A1, A2 is shown, and each cooling unit comprises a compression piston 26, a cooler 24, a regenerator 23, a freezer 22 and an expansion piston 21. The spaces 31 of units A1 and A2 on the sides of pistons 26 remote from the working spaces are connected by ducts 32 and 33 respectively to the spaces on opposite sides of piston 13 of pump unit I while the corresponding spaces 30 adjacent pistons 21 are connected by respective ducts 34 and 35 to the spaces on opposite sides of the piston 8 of pump unit II. Each of the pistons 21 and 26 is connected by a shaft 49 to a valve member 50 having longitudinal bores 52 which is arranged to reciprocate in a cylinder 51 having fluid inlets connected to pipes 54 and 55 and fluid outlets connected to pipes 53 and 56. The pistons 8, 13, 21 and 26 of the machine are positioned ready for starting by moving a valve member 57 to a position in which the discharge of an oil pump 63 is connected via line 73, ports 71 and 69 to lines 55 and via line 73, ports 72 and 68 to a line 18 which communicates with chambers 16 on the ends of the cylinders containing the pistons 13 of pump units I and II. Thus, oil under pressure is delivered via bores 52 to the spaces 30 and 31 of the units to urge the pistons 21 and 26 inwardly such inward movement being terminated when the valve element 50 uncovers the fluid outlets connected to pipes 56 which communicate via ports 70 and 75 and line 76 with an oil reservoir 66 to which the inlet 65 of pump 63 is connected. The oil also acts to force pistons 8 and 13 of the pump units downwardly the pistons 8, 13, 21 and 26 are shown in their starting positions in Fig. 4. To start the machine valve member 57 is moved to close ports 68, 69, 70, 71, 72 and 75 and a motor (not shown) is energized to drive a crank-shaft 19 to drive pump pistons 8 and 13 which in turn act on the oil contained in spaces 30 and 31, ducts 32-35 and the cylinders of pistons 8 and 13, to reciprocate pistons 21 and 26. On starting, the working spaces of the cooling units communicate freely through a duct 80 which is subsequently closed by a valve 81 operated in dependence on the speed of the crank-shaft 19. If, during operation, the pistons move too far outwardly, the valve members 50 uncover fluid inlets connected via pipes 54 and line 73 to pump 63 so that oil is admitted to space 30 or 31 to prevent further outward movement of the pistons. Similarly, should the pistons move too far inwardly the valve elements 50 uncover fluid outlets connected via pipes 53 and line 76 to the oil reservoir 66 so that oil flows from the spaces 30 or 31 and further inward movement of the pistons is prevented. The seal between pistons 21 and 26 and their surrounding cylinders is provided by rolling diaphragms 84 and a substantially constant pressure difference between the working space and a space 90 on the side of the seal 84 remote from the working space is achieved by a control unit 85 comprising a piston 87 disposed in a cylinder 86 which is connected by pipes 89 and 91 with spaces 90 and 31 respectively. Oil from space 31 flows between the piston and cylinder to space 90 and thence via pipe 89 to a space 88 on one side of piston 87 which is arranged, when the desired pressure difference between spaces 31 and 90 obtains, to uncover a port 93 so that the oil is discharged. Should the pressure in space 31 increase piston 87 will move to close port 93 and thus increase the pressure in space 90. Since the pressure in space 31 is substantially equal to that in the working space the arrangement results in the desired constant pressure difference between the latter space and space 90. Each cooling unit is provided with a control unit 85. The second pair of cooling units (Figs. 1 to 3, not shown) is arranged so that the compression pistons are adjacent pump II and the expansion pistons adjacent pump I. The spaces 31 of these units are connected to opposite sides of piston 13 of pump II and the spaces 30 to opposite sides of piston 8 of pump I. In a modification (Figs. 5 and 6, not shown) the pump units are mounted in parallel on the crank-case with one pair of cooling units in front of and the other pair behind the plane of the pump units.