Provided is a bellows pump device that is able to reduce fall of a discharge pressure of a transport fluid during contraction operation of a bellows. The bellows pump device supplies pressurized air to a hermetic discharge-side air chamber thereby to cause a bellows disposed within the discharge-side air chamber to perform contraction operation to discharge a transport fluid, and discharges the pressurized air from the discharge-side air chamber thereby to cause the bellows to perform expansion operation to suck the transport fluid. The bellows pump device includes an electropneumatic regulator configured to adjust an air pressure of the pressurized air to be supplied to the discharge-side air chamber, such that the air pressure is increased so as to correspond to a contraction characteristic of the bellows during the contraction operation of the bellows.

Pulse tube coolers and Gifford-McMahon coolers are used to cool nuclear spin tomographs and cryopumps. To supply cooled working gas, gas compressors and in particular helium compressors are used with rotational or rotary valves. The rate at which compressed helium is introduced into the cooling device and let out again lies in the range of 1 Hz. A problem of conventional screw or piston processors is that oil from the compressor mixes with the working gas and thus contaminates the cooling device. By providing a second compressor stage, a common pump device can be used to pump in both directions, which results in a two-stage compressor device. The working gas is compressed in each flow direction of the working liquid, in one flow direction in the first compressor stage and in the opposite flow direction in the second compressor stage. Thus, the efficiency of the compressor device is improved.

A liquid supply system includes first and second bellows 41 and 42 arranged in series in an expanding/contracting direction thereof in a vessel 12 and having first end portions respectively, which are close to each other and fixed to an inner wall of the vessel 12, and also having second end portions respectively, which are distant from each other and movable in the expanding/contracting direction. An inner space of the vessel 12 located outside the first bellows 41 serves as a first pump chamber P1. An inner space of the vessel 12 located outside the second bellows 42 serves as a second pump chamber P2. An inner space of the vessel 12 located inside the first and second bellows 41 and 42 serves as a sealed space R1. A shaft 15 to which the respective second end portions of the first and second bellows 41 and 42 are fixed is reciprocally moved to expand/contract the first and second bellows 41 and 42.

Disclosed is a conveying device for fluids with an inlet and an outlet and a conveying part which is connected therebetween and can be actuated by a drive part, wherein the conveying part has a fluid-tight media-separating device with a variable chamber volume, which becomes connected in a fluid-conducting manner via its receiving chamber to the inlet or the outlet, and which, by means of the drive part, receives fluid via the inlet as part of an intake stroke, increasing the chamber volume, and discharges the received fluid via the outlet as part of a discharge stroke, reducing the size of said chamber volume.