# US 11,905,980 B2 · Power transfer unit with breakout friction reduction and leakage reduction > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,905,980 B2 - Document ID: US11905980B2 - Status: Granted - Kind: B2 - Application number: 17/614,799 - Filed: 2020-05-26 - Published: 2022-07-21 - Granted: 2024-02-20 - Earliest claimed: 2019-06-26 - Assignees: Parker-Hannifin Corporation - Applicants: Parker-Hannifin Corporation - Inventors: Steven A. Krane; Dean R. Pollee; Scott N. Johns; David A. Scranton; Bernard J. Strehlow - Web page: https://patentgrep.com/patent/US11905980B2 ## CPC - F15B 20/004: {Fluid pressure supply failure} - B64C 13/42: having duplication or stand-by provisions - F15B 3/00: Intensifiers or fluid-pressure converters, e.g. pressure exchangers; Conveying pressure from one fluid system to another, without contact between the fluids {(fluid-driven pumps F04B9/08)} - F15B 2211/20507: Type of prime mover - F15B 2211/20538: constant capacity - F15B 2211/20569: capable of working as pump and motor - F15B 2211/20576: with multiple pumps - F15B 2211/20592: Combinations of pumps for supplying high and low pressure - F15B 2211/214: the pressure sources being hydrotransformers - F15B 2211/275: Control of the prime mover, e.g. hydraulic control - F15B 2211/40507: with constant throttles or orifices - F15B 2211/41563: being connected to a pressure source and a return line - F15B 2211/50518: using pressure relief valves - F15B 2211/50536: using unloading valves controlling the supply pressure by diverting fluid to the return line - F15B 2211/50563: the pressure control means controlling a differential pressure - F15B 2211/5157: being connected to a pressure source and a return line - F15B 2211/6355: having valve means - F15B 2211/7058: Rotary output members - F15B 2211/7142: the output members being arranged in multiple groups - F15B 2211/8633: Pressure source supply failure - F15B 2211/875: Control measures for coping with failures - F15B: SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR - B64C: AEROPLANES; HELICOPTERS ## Abstract A power transfer unit includes a first hydraulic circuit, a second hydraulic circuit fluidly connected to the first hydraulic circuit, a pump and motor assembly fluidly connected between the first hydraulic circuit and the second hydraulic circuit, an isolation valve arranged along the first hydraulic circuit and fluidly connected to an inlet of the pump and motor assembly. The isolation valve is movable between a closed position and an open position to prevent and enable high-pressure fluid flow to the inlet, respectively. An unloader valve is arranged along the second hydraulic circuit and fluidly connected to an outlet of the pump and motor assembly, and an orifice is arranged along the second hydraulic circuit and fluidly connected to the unloader valve to reduce back pressure in the second hydraulic circuit. ## Claims ### Claim 1 A power transfer unit comprising: a first hydraulic circuit; a second hydraulic circuit operatively coupled to the first hydraulic circuit; a pump and motor assembly fluidly connected between the first hydraulic circuit and the second hydraulic circuit; an isolation valve arranged along the first hydraulic circuit and fluidly connected to an inlet of the pump and motor assembly, wherein the isolation valve is movable between a closed position and an open position to prevent and enable high-pressure fluid flow to the inlet, respectively; an unloader valve arranged along the second hydraulic circuit and fluidly connected to an outlet of the pump and motor assembly; an orifice arranged along the second hydraulic circuit and fluidly connected to the unloader valve to reduce back pressure in the second hydraulic circuit; and an arming valve arranged along the first hydraulic circuit for piloting the isolation valve, wherein the arming valve is a three-way normally open solenoid valve. ### Claim 2 (depends on 1) The power transfer unit of claim 1 further comprising a low-pressure pilot pump arranged along the second hydraulic circuit and coupled for rotation with the pump and motor assembly. ### Claim 3 (depends on 2) The power transfer unit of claim 2, wherein the low-pressure pilot pump is communicatively coupled to the unloader valve and the isolation valve. ### Claim 4 (depends on 3) The power transfer unit of claim 3, wherein the low-pressure pilot pump is a gerotor. ### Claim 5 (depends on 1) The power transfer unit of claim 1 further comprising a check valve arranged along the second hydraulic circuit. ### Claim 6 (depends on 1) The power transfer unit of claim 1 further comprising a compensator valve that is arranged along the first hydraulic circuit and fluidly connected to the isolation valve. ### Claim 7 (depends on 6) The power transfer unit of claim 6, wherein the outlet of the pump and motor assembly is communicatively coupled with the compensator valve. ### Claim 8 (depends on 1) The power transfer unit of claim 1, wherein the first hydraulic circuit and the second hydraulic circuit are arranged for unidirectional flow from the first hydraulic circuit to the second hydraulic circuit. ### Claim 9 (depends on 1) The power transfer unit of claim 1, wherein the unloader valve is spring-biased in a normally open position. ### Claim 10 (depends on 1) The power transfer unit of claim 1, wherein the isolation valve is spring-biased in a normally closed position. ### Claim 11 (depends on 1) The power transfer unit of claim 1 further comprising a relief valve arranged along the second hydraulic circuit. ### Claim 12 (depends on 1) The power transfer unit of claim 1, wherein the pump and motor assembly includes a motor arranged along the first hydraulic circuit and a pump arranged along the second hydraulic circuit. ### Claim 13 (depends on 1) An aircraft control system comprising: a first hydraulic system; and a second hydraulic system independent from the first hydraulic system; wherein a power transfer unit according to claim 1 is connected between the first hydraulic system and the second hydraulic system for transferring power between the first hydraulic system and the second hydraulic system. ### Claim 14 A power transfer unit comprising: a first hydraulic circuit; a second hydraulic circuit operatively coupled to the first hydraulic circuit; a pump and motor assembly fluidly connected between the first hydraulic circuit and the second hydraulic circuit; an isolation valve arranged along the first hydraulic circuit and fluidly connected to an inlet of the pump and motor assembly, wherein the isolation valve is movable between a closed position and an open position to prevent and enable high-pressure fluid flow to the inlet, respectively; an unloader valve arranged along the second hydraulic circuit and fluidly connected to an outlet of the pump and motor assembly; an orifice arranged along the second hydraulic circuit and fluidly connected to the unloader valve to reduce back pressure in the second hydraulic circuit; and a low-pressure pilot pump arranged along the second hydraulic circuit and coupled for rotation with the pump and motor assembly, wherein the low-pressure pilot pump is communicatively coupled to the unloader valve and the isolation valve. ### Claim 15 (depends on 14) The power transfer unit of claim 14, wherein the low-pressure pilot pump is a gerotor.