Mitsubishi Denki Kabushiki Kaisha

Mitsubishi Materials Corporation

Masashi Nagao

Takashi Inaguchi

Hideto Yoshimura

Takahiro Matsumoto

Kazuki Moritsu

Mitsuhiro Kishida

Shuuichi Nakagawa

Shuji Ando

Shuichi Nakagawa

Takuo Takeshita

Kouichi Ishiyama

Yasuhiro Hanaue

Mitsuo Horikawa

Etsuji Kimua

A cryogenic refrigerator which is capable of preventing a deterioration in refrigerating performance and which has high efficiency includes: a first compressor; a first expander having at least one accumulator using an accumulating material comprising a rare earth alloy or compound which has a large specific weight at 10K or below or an accumulating material comprising helium; a sub-expansion space which effects further expansion of a working fluid introduced thereto from an expansion space of the first expander; and a second compressor which compresses the working fluid returning from the sub-expansion space.

Cryogenic refrigerator

An object of the present invention is to obtain a superconductive magnet, the size of which can be reduced by shortening the radial length of a magnetic device thereof and the refrigerating performance of which can be improved. A cylinder for fastening a refrigerator has an end facing an ambience of helium gas evaporating in a helium chamber and another end which is substantially horizontally fastened to a vacuum chamber. Further, the three-stage regenerative refrigerator is inserted and fastened to the cylinder for fastening the refrigerator. A heat insulator, such as a convection prevention tube, made of a hollow Teflon tube is wound around the outer surface of each stage of the cylinder of the three-stage regenerative refrigerator. The convection prevention tube is enclosed into a gap between the cylinder for fastening the refrigerator and the three-stage regenerative refrigerator without no undesirable gap so that heat convection of the helium gas is prevented.

Superconductive magnet

In a multi-stage cold accumulation type refrigerator including a compressor disposed at an ordinary temperature, a helium gas as a common operating fluid to be compressed by the compressor, and one or more expansion chambers and cold accumulators of different temperature levels; a cold accumulating member of the cold accumulators is formed of an alloy or compound containing a rare earth metal, so that the efficiency of the refrigerator can be improved. Further, a heat generation quantity due to sliding resistance of a seal is set to be smaller than a theoretical generated refrigeration quantity to be obtained on the assumption of isothermal expansion in the expansion chambers, so that the refrigerating capacity can be improved. The refrigerator is applied to a cooling device for cooling a superconducting magnet, SQUID, superconducting computer, infrared telescope, etc.

Multi-stage cold accumulation type refrigerator and cooling device

A cold accumulation type refrigerating machine having a high refrigeration efficiency. Rotation output of a stepping motor is converted to a reciprocative motion of a displacement member carrying a cold accumulator and disposed within a cylinder in which first and second closed chambers are defined above and below the displacement member, respectively. A compressed gas discharged from a compressor is introduced into the second closed chamber through the cold accumulator upon opening of a suction valve and undergoes expansion within the second closed chamber, the gas being then fed back to the compressor through the cold accumulator upon opening of an discharge valve, whereupon one cycle of refrigerating operation is completed. Rotation speed of the stepping motor is varied during every one cycle of operation by means of a pulse oscillation controller such that a time taken for the displacement member to reach a top dead center position from a time point at which the discharge valve is opened is increased while the remaining period of the one cycle is correspondingly shortened.

Cold accumulation type refrigerating machine

According to the present invention there is provided a regenerative refrigerator wherein a gas discharged from a compressor is introduced through a regenerator into a closed chamber whose internal volume changes with movement of a movable member, the movable member being disposed within a cylinder through a predetermined gap between its outer peripheral surface and the inner peripheral surface of the cylinder, and is allowed to expand therein, then is discharged again through the same route. In this regenerative refrigerator, the size, d, of the said gap is set in the range of 1/1000.ltoreq.d/D.ltoreq.1/100 relative to the inside diameter, D, of the cylinders or a gas convection preventing member is disposed in the said gap, or seals which are in contact with the inner peripheral surface of the cylinder are provided on the outer peripheral surfaces of both end portions of the movable member.

Regenerative refrigerator

A cryogenic refrigerator which is capable of preventing a deterioration in refrigerating performance and which has high efficiency includes: a first compressor; a first expander having at least one accumulator using an accumulating material comprising of a rare earth alloy or compound which has a large specific weight at 10 K. or below or an accumulating material comprising of helium; a sub-expansion space which effects further expansion of a working fluid introduced thereto from an expansion space of the first expander; and a second compressor which compresses the working fluid returning from the sub-expansion space.

A superconducting magnet which is capable of improving the refrigerating and the assembling characteristics and of composing in small size. A helium vessel 2 contains a cylindrical superconducting coil for cryogenically refrigerating it by liquid helium. A second and a first heat-shields 5 and 6 and a vacuum vessel 4 are coaxially provided so as to surround the helium vessel 2. Over the helium vessel 2, a L-letter shaped duct 50 is provided to be exposed to helium gas atmosphere being evaporated in the helium vessel 2. A refrigerator-mounting cylinder 51 has an end coupled to the L-letter shaped duct 50 through the bellows 52 and is mounted on an end surface of the vacuum vessel 4 substantially in parallel to the axial direction of the superconducting coil. A three-stage cold heat accumulation refrigerator 30 is inserted into and fixed to the refrigerator-mounting cylinder 51 for reliquefying the helium gas having been drawn into the L-letter shaped duct 50 by a third heat state 43.

Superconducting magnet and method for assembling the same

The present invention provides heat reserving materials comprising alloys of Ru and at least one rare earth metal which are represented by the formula (I):

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Amagasaki, Japan

Masashi Nagao