An external cooling circuit for an integrated transaxle includes an integrated transaxle having a casing and a motor and a pump contained within the casing. The pump is connected to and actuable by an input shaft extending from the casing. The motor is connected to an output shaft extending from the casing. Hydraulic fluid is circulated in the casing by the pump to drive the motor. First and second ports are formed in the casing and a charge pump is contained within the casing. A reservoir is external to the casing. The reservoir is in fluid communication with the first and second ports of the casing such that the charge pump is configured to create a vacuum at the second port to cause hydraulic fluid to exit the casing through the first port, enter the reservoir, and re-enter the casing through the second port.

A cooling flow circuit is provided and includes a main line having first and second sections ported to piston extend and return sides of the gas turbine engine actuator, respectively, an orifice disposed along the main line between the first and second sections, a bypass line and a bypass valve. The bypass line is fluidly coupled to the first and second sections at opposite ends thereof, respectively. The bypass valve is disposed along the bypass line between the opposite ends thereof. The bypass valve has a variable flow area which is responsive to a pressure differential between the first and second sections.

A method and apparatus are presented. An active flow control system comprises a flow control valve, a manifold, and a temperature control system. The flow control valve is configured to control a flow of air into the manifold. The manifold is operatively connected to a number of actuators. The temperature control system is configured to heat at least a portion of the flow of air.

A method and apparatus are presented. An active flow control system comprises a flow control valve, a manifold, and a temperature control system. The flow control valve is configured to control a flow of air into the manifold. The manifold is operatively connected to a number of actuators. The temperature control system is configured to heat at least a portion of the flow of air.

A valving system has an actuator member connected to move with an actuator piston and change the position of a valve member. There is a smaller face fluid chamber acting on a small area piston face, and a larger face fluid chamber acting on a larger face of the actuator piston. The torque motor has an armature and a flapper caused to move by current received at the armature. The flapper moves between two fluid ports to control the pressure in the larger face chamber. The flapper further has a positioning extension engaging a first feedback spring operable between it and a forward face of the actuator piston and providing a spring force in combination with a spring force from the positioning extension. A control is operable to provide current to the armature to control the fluid received in the larger face chamber. The controller is programmed to associate the current supplied to the armature to an actual position of the valve member. A method is also disclosed.

A valving system has an actuator member connected to move with an actuator piston and change the position of a valve member. There is a smaller face fluid chamber acting on a small area piston face, and a larger face fluid chamber acting on a larger face of the actuator piston. The torque motor has an armature and a flapper caused to move by current received at the armature. The flapper moves between two fluid ports to control the pressure in the larger face chamber. The flapper further has a positioning extension engaging a first feedback spring operable between it and a forward face of the actuator piston and providing a spring force in combination with a spring force from the positioning extension. A control is operable to provide current to the armature to control the fluid received in the larger face chamber. The controller is programmed to associate the current supplied to the armature to an actual position of the valve member. A method is also disclosed.

A thermal management system includes a first hydraulic system for circulating a first hydraulic fluid at a first temperature and a second hydraulic system for circulating a second hydraulic fluid at a second temperature that is higher than the first temperature. The thermal management system also includes a sealed heat transfer device coupled between the first hydraulic system and the second hydraulic system. The sealed heat transfer device is not in flow communication with either of the first hydraulic system and the second hydraulic system. The sealed heat transfer device is configured to transfer heat from the second hydraulic fluid to the first hydraulic fluid.

A thermal management system includes a first hydraulic system for circulating a first hydraulic fluid at a first temperature and a second hydraulic system for circulating a second hydraulic fluid at a second temperature that is higher than the first temperature. The thermal management system also includes a sealed heat transfer device coupled between the first hydraulic system and the second hydraulic system. The sealed heat transfer device is not in flow communication with either of the first hydraulic system and the second hydraulic system. The sealed heat transfer device is configured to transfer heat from the second hydraulic fluid to the first hydraulic fluid.

A thermal management system is provided. The thermal management system includes a first hydraulic system for circulating a first hydraulic fluid at a first temperature, a second hydraulic system for circulating a second hydraulic fluid at a second temperature that is higher than the first temperature, and a heat exchanger coupling the first hydraulic system to the second hydraulic system, wherein the heat exchanger is configured to exchange heat between the first hydraulic fluid and the second hydraulic fluid.

Systems and methods for reducing the pressure of a first pressurized fluid, thereby reducing the temperature of the pressurized fluid, and utilization of the reduced-pressure and temperature fluid to cool a second fluid. Such an approach can enable a reduction in the size and weight of a hydraulic system, utilize waste energy in a system, and/or minimize electrical power requirements of a system, among other benefits.