Smart Pump
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Power-Adaptive Hydraulic Control Systems Start With The Smartpump Innovation

The best example of a power-adaptive hydraulic pump is the human heart. It must be capable of operating at 180 beats per minute for full emergency power, yet also operate at minimum standby demand, (60/minute) and every position between the two as commanded by the brain and sensory system.

To date, the Space Shuttle's hydraulic system has not been power adaptive. At liftoff, the Shuttle's engines develop 7,000,000 pounds of thrust. The thrust vector of the gimbal-mounted rocket motors is controlled by hydraulic servoactuators powered by seven Abex 3000 psi variable flow constant pressure axial piston pumps. This is the biggest use of hydraulic power in the whole bird; all other functions, such as landing gear and flight controls, are minor loads compared to liftoff.

The pumps in the boosters are finished with their job when they're jettisoned, but the three pumps on the orbiter must continue to function for the duration of the mission. When the system pressure is higher than the load requires, unnecessary energy is transferred to the hydraulic fluid in the form of waste heat. This waste heat must be dissipated in heat exchangers and coolant--a serious weight penalty.

NASA asked Abex to investigate a modification to the hydraulic pumps in order to lower this weight penalty.

The Abex solution: a variable flow pump with electronic pressure control which will allow the system pressure to be changed in response to the pressure load demand. Test stand results demonstrate an energy savings of 32% to 40% on the pump alone when the pressure is dropped from 3000 to 1000 psi.

By incorporating the SMARTPUMP modification, NASA engineers estimate the net weight savings after removal of water boilers would be over 5000 pounds.