Abstract: A linear actuator is provided. The linear actuator comprises: a body; a shaft adapted to move linearly relative to the body; a driver adapted to drive the linear movement of the shaft; and a shape memory alloy component configured to compensate for thermal expansion or contraction of the linear actuator due to a change in temperature thereof.

Abstract: There is disclosed a flow control nozzle for controlling the flow of an incompressible fluid, the flow control nozzle having a flow area and comprising a deformable element comprising a shaped memory alloy (SMA) material wherein within a range of operating temperatures the SMA material is configured to reduce the flow area of the flow control nozzle as the operating temperature increases. The flow control nozzle is thus able to dynamically compensate for changes in operating temperature in order to maintain a constant flow.

Abstract: An actuation system, for example an actuation system for an aircraft control surface. The actuation system may include a rotary driver and three or more actuator modules, and each actuator module may be connected to the rotary driver such that the three or more actuator modules are configured to drive rotation of the rotary driver in combination.

Abstract: An actuator rod assembly for a blade pitch control system is provided herein. The actuator rod assembly includes a tubular outer rod and an inner rod. The outer rod has a first end and a second end. The inner rod has a first end and a second end and extends through the tubular outer rod. The inner rod is tensioned against the tubular outer rod so as to place the outer rod in compression.

Abstract: A linear actuator is provided. The linear actuator comprises: a body; a shaft adapted to move linearly relative to the body; a driver adapted to drive the linear movement of the shaft; and a shape memory alloy component configured to compensate for thermal expansion or contraction of the linear actuator due to a change in temperature thereof.

Abstract: A hydraulic damper comprises an outer cylinder, and an inner cylinder slidably mounted within the outer cylinder for movement relative to the outer cylinder along a longitudinal axis. The inner cylinder has a circumferential wall circumscribing a bellows assembly. The bellows assembly comprises a first bellows section, a second bellows section, a damping plate attached to and separating the first and second bellows sections, a first closure element closing an end of the first bellows section opposite the damping plate to define a first chamber, and a second closure element closing an end of the second bellows section opposite the damping plate to define a second chamber. The first closure element is attached to the inner cylinder for movement therewith relative to the outer cylinder. The second closure element is also attached to the inner cylinder for movement therewith relative to the outer cylinder.

Abstract: A rotary damper comprising a fixed structure, a rotor configured to rotate about an axis (R-R), and two opposing bellows. The bellows each extend between the rotor and the fixed structure and are attached thereto. The bellows each define a chamber for holding hydraulic fluid and are configured to expand and contract as the rotor rotates. The damper further comprises a damping orifice extending through the rotor or the fixed structure. The bellows are sealingly engaged around the damping orifice and the damping orifice permits fluid communication between the chambers defined by the bellows.

Abstract: An electrohydraulic spool valve, comprising: a spool, axially movable within a manifold; a position feedback system provided at a first end of the spool; and an end cap provided on said first end so as to form a first high pressure reservoir between the end cap and the first end of the spool. The end cap provided on the end of the spool partly defines the high pressure reservoir by containing the high pressure fluid in the vicinity of the spool end.

Abstract: A hydraulic spool valve assembly comprising a housing defining a bore having a longitudinal axis (L), a hydraulic spool valve, a sleeve disposed within the bore and a temperature compensation device disposed between the sleeve and the housing. The hydraulic spool valve having a first end for connection to a drive arm, and an opposing second end disposed within the bore. The sleeve disposed between the hydraulic spool valve and the housing. The temperature compensation device configured to expand in a first longitudinal direction in response to a temperature increase, to oppose movement of the sleeve in an opposing second longitudinal direction caused by the temperature increase.

Abstract: A drive lever comprising a first end for insertion into a slot of the hydraulic spool valve. The first end comprises at least two resilient members which resist radial compression (R1, R2) such that they exert a radially outward force (F1, F2) on one or more inner surfaces of the slot when inserted therein. This radially outward force (F1, F2) can account for any backlash that would otherwise be present between the drive lever and the slot due to manufacturing tolerances or wear.

Abstract: There is disclosed a flow control nozzle for controlling the flow of an incompressible fluid, the flow control nozzle having a flow area and comprising a deformable element comprising a shaped memory alloy (SMA) material wherein within a range of operating temperatures the SMA material is configured to reduce the flow area of the flow control nozzle as the operating temperature increases. The flow control nozzle is thus able to dynamically compensate for changes in operating temperature in order to maintain a constant flow.

Abstract: An actuator rod assembly for a blade pitch control system is provided herein. The actuator rod assembly includes a tubular outer rod and an inner rod. The outer rod has a first end and a second end. The inner rod has a first end and a second end and extends through the tubular outer rod. The inner rod is tensioned against the tubular outer rod so as to place the outer rod in compression.

Abstract: The present disclosure relates to an adjustment system a method for compensating for temperature variations in a spool valve. The spool valve and adjustment system may be parts in a duplex hydraulic actuator. The adjustment device comprises a spring, a pivot point, and a shape memory alloy (SMA) device. The spring and SMA device are disposed on either side of the pivot point to hold the pivot point in a first position. The SMA device is configured to change size in response to a temperature change so as move the pivot point to a second location. This may eliminate force fight in the duplex hydraulic actuator by preventing asynchronous activation of the spool valves due to thermal expansion within the spool valves.

Abstract: A hydraulic damper comprises an outer cylinder, and an inner cylinder slidably mounted within the outer cylinder for movement relative to the outer cylinder along a longitudinal axis. The inner cylinder has a circumferential wall circumscribing a bellows assembly. The bellows assembly comprises a first bellows section, a second bellows section, a damping plate attached to and separating the first and second bellows sections, a first closure element closing an end of the first bellows section opposite the damping plate to define a first chamber, and a second closure element closing an end of the second bellows section opposite the damping plate to define a second chamber. The first closure element is attached to the inner cylinder for movement therewith relative to the outer cylinder.

Abstract: A hydraulic spool valve assembly comprising a housing defining a bore having a longitudinal axis (L), a hydraulic spool valve, a sleeve disposed within the bore and a temperature compensation device disposed between the sleeve and the housing. The hydraulic spool valve having a first end for connection to a drive arm, and an opposing second end disposed within the bore. The sleeve disposed between the hydraulic spool valve and the housing. The temperature compensation device configured to expand in a first longitudinal direction in response to a temperature increase, to oppose movement of the sleeve in an opposing second longitudinal direction caused by the temperature increase.

Abstract: A drive lever comprising a first end for insertion into a slot of the hydraulic spool valve. The first end comprises at least two resilient members which resist radial compression (R1, R2) such that they exert a radially outward force (F1, F2) on one or more inner surfaces of the slot when inserted therein. This radially outward force (F1, F2) can account for any backlash that would otherwise be present between the drive lever and the slot due to manufacturing tolerances or wear.

Abstract: A spool for a hydraulic spool valve, comprising: a pressure chamber for connecting a pressure line to a hydraulic cylinder; at least one return chamber for connecting the hydraulic cylinder to a reservoir; and an actuator slot for receiving a drive lever; wherein the spool further comprises a fluid path connecting said pressure chamber to said actuator slot and a pressure plate movably mounted in the slot such that in use it is disposed between the fluid path and the drive lever.

Abstract: The present disclosure relates to an adjustment system a method for compensating for temperature variations in a spool valve. The spool valve and adjustment system may be parts in a duplex hydraulic actuator. The adjustment device comprises a spring, a pivot point, and a shape memory alloy (SMA) device. The spring and SMA device are disposed on either side of the pivot point to hold the pivot point in a first position. The SMA device is configured to change size in response to a temperature change so as move the pivot point to a second location. This may eliminate force fight in the duplex hydraulic actuator by preventing asynchronous activation of the spool valves due to thermal expansion within the spool valves.

Abstract: An electrohydraulic spool valve, comprising: a spool, axially movable within a manifold; a position feedback system provided at a first end of the spool; and an end cap provided on said first end so as to form a first high pressure reservoir between the end cap and the first end of the spool. The end cap provided on the end of the spool partly defines the high pressure reservoir by containing the high pressure fluid in the vicinity of the spool end.

Abstract: A seal comprising: a seal cap that provides a sealing surface; an elastomeric energizer; and a shape memory alloy structure; wherein the combination of the shape memory alloy structure and the elastomeric energizer is arranged to provide a sealing force to the seal cap; and wherein the shape memory alloy is arranged to change shape with temperature such that for a predetermined temperature range it compensates for changes in the elasticity of the elastomeric energizer so as to maintain the preload force on the seal cap.