Portable cryogenic power system for pneumatically operated tools

摘要

A compact, lightweight, portable cryogenic system for powering small pneumatic hand tools. A unitary manifold for providing a fluid fill path and a fluid vent path is mounted to the upper surface of a small dewar for containing a cryogenic liquid under pressure. The manifold is provided with partially threaded inner passageways for externally mounting a vent valve, pressure gauge and first relief valve, and for internally mounting a fill check valve and an economizer check valve. The economizer check valve is coupled to the inlet of a small heat exchanger comprising a length of finned tubing coiled in a stack about the manifold on top of the dewar and prevents back-flow of fluid to the dewar. A pneumatic circuit breaker valve coupled between the outlet of the heat exchanger and the inlet of a pneumatic hose having a disconnect valve at the outlet enables small pneumatic hand tools to be removably connected to the pneumatic hose and powered by cryogenic liquid vaporized in the heat exchanger. The pneumatic circuit breaker valve limits the flow rate of cryogenic vapor to the tool to a predetermined maximum, and a second relief valve coupled between the heat exchanger outlet and the circuit breaker valve limits pressure build-up in the heat exchanger to a predetermined maximum.PPA shroud having handle portions for carrying the unit is secured to the upper peripheral portion of the dewar with a fluid clearance between the lower edge of the shroud and the upper surface of the dewar periphery so that the ambient air freely flows past the heat exchanger.