Abstract: A cryogenic refrigerator includes a pressure feeding device, a refrigeration device, a high pressure passage, a low pressure passage, and at least one heat exchanger at the high pressure passage for refrigerating the refrigerant introduced at the high pressure passage by heat exchange, the heat exchanger including an active pressure drop type heat exchanger for declining pressure of the refrigerant at the high pressure passage before being introduced into the refrigeration device. The active pressure drop type heat exchanger declines the pressure of the refrigerant with a ratio equal to or greater than 5 percent out of 100 percent and refrigerates the refrigerant when a pressure difference between a pressure of the refrigerant before being introduced into the active pressure drop type heat exchanger and a pressure of the refrigerant before being introduced into the refrigeration device is defined as 100 percent.

Abstract: A cryogenic refrigerator includes a pressure feeding device, a refrigeration device, a high pressure passage, a low pressure passage, and at least one heat exchanger at the high pressure passage for refrigerating the refrigerant introduced at the high pressure passage by heat exchange, the heat exchanger including an active pressure drop type heat exchanger for declining pressure of the refrigerant at the high pressure passage before being introduced into the refrigeration device. The active pressure drop type heat exchanger declines the pressure of the refrigerant with a ratio equal to or greater than 5 percent out of 100 percent and refrigerates the refrigerant when a pressure difference between a pressure of the refrigerant before being introduced into the active pressure drop type heat exchanger and a pressure of the refrigerant before being introduced into the refrigeration device is defined as 100 percent.

Abstract: A rotary valve unit in a pulse tube refrigerator is quiet, and has high durability and improved refrigeration efficiency by restricting the generation of unidirectional flow. A center hole is formed on a sliding plane side as a recessed space in the sliding surfaces between the sliding plane and another sliding plane. Since the second center hole is in communication with a low pressure input port via a communication passage, the leakage between the sliding surfaces of the sliding planes can be introduced to the low pressure input port with low pressure.

Abstract: In a pulse tube refrigerator the refrigeration efficiency has been improved by reducing the on-off valve loss. A second space 47 in a cylinder member 41 is connected with a second high pressure on-off valve 23 and a second low pressure on-off valve 24. A buffer side on-off valve 25 is provided between the buffer space (a buffer tank 50) and the second space 47. By opening the buffer side on-off valve 25 before the second high pressure on-off valve 23 or the second low pressure on-off valve 24 is open, the pressure in the second space 47 can be the intermediate pressure. Since the pressure difference when the valves are open is decreased, the on-off valve loss can be decreased.

Abstract: A rotary valve unit in a pulse tube refrigerator is quiet, and has high durability and improved refrigeration efficiency by restricting the generation of unidirectional flow. A center hole is formed on a sliding plane side as a recessed space in the sliding surfaces between the sliding plane and another sliding plane. Since the second center hole is in communication with a low pressure input port via a communication passage, the leakage between the sliding surfaces of the sliding planes can be introduced to the low pressure input port with low pressure.

Abstract: A pulse tube refrigerator which reduces valve losses in a cycle and improves refrigeration efficiency includes a pressure oscillator, a refrigerating portion, a first middle pressure buffer tank, a first middle pressure buffer side valve, a second middle pressure buffer tank and a second middle pressure buffer side valve. A regenerator in the refrigerating portion and an outlet port and an inlet port of a compressor in the pressure oscillator are connected via a high pressure valve and a low pressure valve respectively. A high temperature heat exchanger of the refrigerating portion and the first middle pressure buffer tank and the second middle pressure buffer tank are connected via the first middle pressure buffer side valve and the second middle pressure buffer side valve. The first middle pressure buffer tank and the second middle pressure buffer tank include different middle pressures which are predetermined between an output pressure and an input pressure of the compressor.

Abstract: A pulse tube refrigerator includes a compressor, a first heat exchanger, a first regenerator, a first cold head, a first pulse tube, a first radiator, a second regenerator, a second cold head, a second pulse tube, a second radiator, an orifice and a buffer tank which are connected in series. A first cooling part consists of the first heat exchanger, the first regenerator, the first cold head, the first pulse tube and the first radiator. A second cooling part consists of the first radiator, the second regenerator, the second cold head, the second pulse tube and the second radiator. The first radiator forms not only the radiator of the first cooling part, but also the heat exchanger of the second cooling part.

Abstract: A pulse tube refrigerator includes a refrigerating portion including a regenerator, a low temperature heat exchanger, a pulse tube and a high temperature heat exchanger fluidically connected in this order. A first pressure oscillator includes a first compression source, a first high pressure supply valve, and a first low pressure supply valve. The regenerator is connected with outlet and inlet ports of the first compression source via the first high pressure supply valve and the first low pressure supply valve, respectively. A second pressure oscillator is provided independently of the first pressure oscillator and has a second compression source, a second high pressure supply valve, and a second low pressure supply valve. The high temperature heat exchanger is connected with outlet and inlet ports of the second compression source via the second high pressure supply valve and the second low pressure supply valve, respectively.

Abstract: A multi-type pulse-tube refrigerating system includes a common compressor 1 having a sucking port 1b and a discharging port 1a, a plurality of paralleled pressure changeover valve units 21, 22 and 23 connecting between the sucking port 1b and the discharging port 1a of the compressor 1, and a plurality of pulse-tube based cryogenic temperature generating devices 310, 410 and 510 connected to the respective pressure changeover valve units 21, 22 and 23. Employing such cryogenic temperature generating devices 310, 410 and 510, each of which is void of moving parts, limits vibrations. Moreover, instead of the pressure changeover valve units 21, 22 and 23, employing a common pressure changeover valve unit 24 for the units 21, 22 and 23 makes the refrigerating system more compact.

Abstract: In a pulse tube refrigerator the refrigeration efficiency has been improved by reducing the on-off valve loss. A second space 47 in a cylinder member 41 is connected with a second high pressure on-off valve 23 and a second low pressure on-off valve 24. A buffer side on-off valve 25 is provided between the buffer space (a buffer tank 50) and the second space 47. By opening the buffer side on-off valve 25 before the second high pressure on-off valve 23 or the second low pressure on-off valve 24 is open, the pressure in the second space 47 can be the intermediate pressure. Since the pressure difference when the valves are open is decreased, the on-off valve loss can be decreased.

Abstract: A pulse tube refrigerator includes a compressor, a first high pressure valve connected with the compressor, a first high pressure passage connecting the outlet port of the compressor with the first high pressure valve, a first low pressure valve connected with the compressor, first low pressure passage connecting the inlet port of the compressor with the first low pressure valve, a regenerator connected with the first high pressure valve and the first low pressure valve, a cold head connected with the regenerator, a pulse tube connected with the cold head a second high pressure valve connected with the pulse tube.

Abstract: A heat-regenerating type cryogenic cooling apparatus 101 includes a cryogenic temperature generating part 10 having a heat regenerator 11; and a pressure generating device 30 connected to the part 10, generating pressure vibration of a working gas therein, and having a compressor 31 with a discharging port 31a and a sucking port 31b, a high-pressure line 32 whose one end is in fluid communication with the discharging port 31a of the compressor 31, a low-pressure line 33 whose one end is in fluid communication with the sucking port 31b of the compressor 31, a high-pressure open/close valve 34 connected to the other end of the line 32, a low-pressure open/close valve 35 connected to the other end of the line 33, a high-pressure side line 36 connecting the valve 34 and the 10, a low-pressure side line 37 connecting the valve 35 and the part 10, and a high-pressure side buffer tank 38 as a high-pressure source connected to the midportion of the line 32.

Abstract: A higher temperature end of a pulse tube is connected to a lower side of a supporting member so as to position at a lower temperature end of the pulse tube at a lower position. Such a structure prevents free convection of a working gas in the pulse tube, which is a cause of reduced refrigerating efficiency. If a cold head is desired to be contacted with a member to be cooled down from its (lower) side, such a need can be satisfied by mounting the cold head on the lower temperature end of the pulse tube (a lower temperature end of a regenerator).

Abstract: A pulse tube refrigerator includes a regenerator including a cold end and a hot end, a cold head connected to the cold end of the regenerator, a pulse tube having a cold end and a hot end and connected at its cold end to the cold head, a pressure fluctuation source connected to the hot end of the regenerator, a buffer connected to the hot end of the pulse tube through an orifice, and an auxiliary buffer connected to the hot end of the pulse tube through a buffer side control valve. The buffer and the auxiliary buffer may be replaced by a single buffer connected to the hot end of the pulse tube through an orifice and a buffer side control valve which are arranged in parallel.

Abstract: A pulse tube refrigeration system includes a pressure wave generator generating continuous pressure wave of a working fluid: a regenerator having a low temperature end and a high temperature end connected to the pressure wave generator; a cold head connected at one end thereof to the low temperature end of the regenerator and producing a very low temperature; a pulse tube having a high temperature end and a low temperature end connected to the other end of the cold head; and a phase shifter adjusting a phase difference between a pressure oscillation and a displacement of the working fluid and transmitting an expansion work of the working fluid to the high temperature end of the regenerator in mechanical mode which is performed at the high temperature end of the pulse tube.

Abstract: In a Stirling engine, a thermal isolating space is provided between an expansion space and a heating portion so as to establish a thermal isolation of the expansion space from the heating portion.

Abstract: A thermally operated refrigerator includes a hot space absorbing a heat from an outer heat source at a high temperature, an ambient space having a first portion and a second portion, a heat accumulator disposed between the hot space and the first portion of the ambient space for establishing a first fluid circuit in which an amount of operating fluid is filled, a hot displacer whose reciprocal movement establishes a periodical movement of the operating fluid in the first fluid circuit for rejecting the heat absorbed at the hot space to the first portion of the ambient space, a cold space absorbing a heat from a load at a low temperature, a cooler disposed between the cold space and the second portion of the ambient space for establishing a second fluid circuit in which an amount of operating fluid is filled, a cold displacer whose reciprocal movement establishes a periodical movement of the operating fluid in the second fluid circuit for rejecting the heat absorbed at the cold space to the second portion of t

Abstract: An optically active compound represented by formula (I): ##STR1## wherein R.sup.1 represents an alkyl group having from 6 to 18 carbon atoms or an alkoxy group having from 6 to 18 carbon atoms; A represents ##STR2## or ##STR3## wherein ring ##STR4## represents a nitrogen-containing hetero-aromatic ring; n and m each represents 0 or 1; R.sup.2 represents an alkyl group having from 1 to 12 carbon atoms; and C* is an asymmetric carbon atom. The compound of formula (I) exhibits excellent physicochemical stability, a low temperature range for the chiral smectic C phase when used either alone or in combination with other compounds, and a rapid response.