A cryogenic pump system includes a supply of liquid natural gas, a source of hydraulic fluid, a cryogenic pump, and an electronic control module. The cryogenic pump is operatively arranged with the supply of liquid natural gas and the source of hydraulic fluid. The cryogenic pump is configured to operate using the source of hydraulic fluid to compress at least some of the supply of liquid natural gas for delivery to an engine. The electronic control module is operably arranged with the cryogenic pump and configured to selectively operate the cryogenic pump. Control strategies for operating the cryogenic pump system are disclosed which have reduced power demands.

A cryogenic pump system includes a supply of liquid natural gas, a source of hydraulic fluid, a cryogenic pump, and an electronic control module. The cryogenic pump is operatively arranged with the supply of liquid natural gas and the source of hydraulic fluid. The cryogenic pump is configured to operate using the source of hydraulic fluid to compress at least some of the supply of liquid natural gas for delivery to an engine. The electronic control module is operably arranged with the cryogenic pump and configured to selectively operate the cryogenic pump. Control strategies for operating the cryogenic pump system are disclosed which have reduced power demands.

There is provided a fluid circuit capable of continuously driving pressure-increasing devices with a simple configuration. A plurality of pressure-increasing devices are connected in parallel to a fluid supply device that delivers a working fluid. A stroke direction of the piston of each of the pressure-increasing device is switched by the working fluid. A phase of the piston of one pressure-increasing device is different from a phase of the piston of the other pressure-increasing device.