Hydrogen Fuel Pressure Energy Recovery for Hydrogen Engine Vehicles

A fuel system for a vehicle having a fuel tank for storing hydrogen fuel and an internal combustion engine, the internal combustion engine having a fuel delivery system for injecting the hydrogen fuel into at least one combustion cylinder, comprising:

• a compressor/expander in fluid connection between the fuel tank and the engine's fuel delivery system, the compressor/expander configured to:
• receive the hydrogen fuel from the fuel tank, deliver the hydrogen fuel at a desired fuel pressure to the fuel delivery system, operate in compressor mode when the hydrogen fuel in the fuel tank is below the desired pressure, and operate in expander mode when the hydrogen fuel in the fuel tank is above the desired pressure;
• a fuel tank pressure sensor for measuring the pressure of the hydrogen fuel at the outlet of the fuel tank;
• a fuel tank temperature sensor for measuring the temperature of the hydrogen fuel at the outlet of the fuel tank;
• an inlet metering valve at the inlet to the compressor/expander for metering flow timing and amount from the fuel tank to the compressor/expander;
• an outlet metering valve at the outlet from the compressor/expander for metering flow timing and amount from the compressor/expander to the fuel delivery system;
• a controller for receiving pressure and temperature measurements from the pressure sensor and from the temperature sensor, for storing data representing the desired pressure, and for calculating timing of the opening and closing of the inlet metering valve and the outlet metering valve to maintain the desired pressure at a delivery point to the fuel delivery system.