Fluid circulation device, installation and method using such a device

A fluid circulation device for a refrigerator or cryogenic liquefier, the fluid circulation device comprising:

• a casing which is sealed against the exterior of the device, and contains an electrical machine such as an electric motor or an alternator;
• a cycle gas circuit which subjects the cycle gas to a thermodynamic change between a minimal pressure and a maximal pressure when the device is operating;
• at least one unit to drive the cycle gas in the circuit, such as a compressor wheel, said drive unit being coupled in rotation to the electrical machine;
• an electrical junction box which is sealed against the exterior of the device, and in which there passes electrical circuitry having a first end connected to the electrical machine, and a second end connected to at least one electrical connector which opens onto the exterior of the junction box, and is situated on the exterior of the casing;
• a conveying duct configured to convey cycle gas under pressure, the conveying duct comprising a first end which is connected to a portion of the circuit in which the cycle gas is at a pressure higher than the minimal pressure, and a second end which communicates with the interior of the junction box,
• wherein the junction box comprises a passage for communication with the interior of the casing,
• wherein the fluid circuit comprises a cycle gas return duct, comprising a first end which communicates with the interior of the casing, and a second end which is connected to the circuit,
• wherein the conveying duct, the passage and the return duct are configured to collect a fraction of the cycle gas which flows in the circuit, in order to make the fraction of the cycle gas circulate in the junction box so as to cool the box before returning to the circuit.