A rotary engine that generates electricity using differences in relative humidity. A water-responsive material expands and contracts as water evaporates which drives the rotation of two wheels. The rotary motion drives an electrical generator which produces electricity. In another embodiment, the water-responsive material is used to actuate an artificial muscle of a robotic device.

An actuator device includes an actuator member, a drive subject, a drive device, and a tension applicator. The actuator member is configured to be deformed in response to application of energy to the actuator member from an outside of the actuator member. The drive subject is coupled to the actuator member. The drive device is configured to apply the energy to the actuator member and thereby displace the drive subject in a deforming direction of the actuator member. The tension applicator is configured to apply the actuator member a tension, which enables correction of a tension change generated by at least one of elongation and contraction of the actuator member that is induced by natural deformation of the actuator member.

In an example, an engine includes a thermal expansion unit comprising expansion material that expands in response to a temperature increase of the expansion material and contracts in response to a temperature decrease of the expansion material. The engine includes a structure comprising a heat receiving region, wherein at least a portion of the thermal expansion unit is disposed within the structure. The heat receiving region is configured to transfer thermal energy from a source of thermal energy to the expansion material through a first thermal energy transference path. The transfer of thermal energy to the thermal expansion unit causes expansion of the expansion material within the thermal expansion unit. The expansion of the expansion material causes an increase in length of the thermal expansion unit. The increase in length of the thermal expansion unit causes establishment of a second thermal energy transference path through which thermal energy is transferred from the expansion material to outside the thermal expansion unit.

An engine includes a thermal unit, a force introducing unit applying a force to a shaft of the thermal unit in a first direction, and/or a switch assembly that switches between a first state and a second state. In the first state, the switch assembly transfers thermal energy from a source to the thermal unit, which causes the shaft to move in a second direction from a first position to a second position. The switch assembly switches to the second state (i) during movement of the shaft in the second direction, (ii) when the shaft reaches the second position, and/or (iii) when the shaft reaches a third position between the first position and the second position. In the second state, the switch assembly transfers thermal energy from the thermal unit to outside the thermal unit, which causes the shaft of the thermal unit to move in the first direction.

An impact drive type actuator (10) is comprised of a wire-shaped shape memory alloy (11) which contracts upon being electrified and heated, a disk-shaped insulating heat conductor (12) which contacts this wire-shaped shape memory alloy (11) and releases the heat which is generated at the wire-shaped shape memory alloy, and a drive circuit (16, 17) which instantaneously electrifies the wire-shaped shape memory alloy and instantaneously makes the wire-shaped shape memory alloy contract. According to this impact drive type actuator, it realizes a heat conduction structure which gives rise to a high heat dispersion action by the heat characteristics of the shape memory alloy, so it becomes possible to utilize the deformation by extension and contraction of a shape memory alloy which has a wire-shaped form, improve the speed and response of the deformation operation characteristics, and improve practicality.

An actuator includes a drum defining a longitudinal axis and having axially opposed first and second end portions that are rotatable relative to one another about the longitudinal axis. A shape memory element is wrapped around the drum and extends from the first end portion of the drum to the second end portion of the drum to actuate relative rotation of the first and second end portions of the drum about the longitudinal axis by activation of the shape memory element.

In one embodiment, the disclosed vortex generator may include a flap, a bearing configured to be mounted on a surface, an axle retained in the bearing, the flap attached to the axle such that the flap rotates relative to the bearing about the axle, and an actuator made of a shape memory alloy attached to the flap and to a support, the actuator shaped to receive the axle therethrough, such that a change in temperature of the actuator causes the actuator to rotate the flap relative to the bearing.

In a motor vehicle, a display device has a display area displaying an image projected by an optical device by way of a reflection area as a virtual image. The optical device has at least one reflector and an actuator which moves the reflector. The actuator includes a shape memory material, which is designed to be deformed by a temperature-dependent phase transition and thereby move the reflector. By the provision of a thermal shape memory actuator that functions without an electric current, the optical path can be changed, so that overheating of internal temperature-sensitive components of the display device can be prevented in a way that is particularly inexpensive and efficient in terms of installation space and it is also possible to dispense with electronic sensing, evaluation and activation entirely.

An actuator (12) includes a moving member (18) pivotally connected to a base unit (14) for rotation about an axis. The driving force for rotation of the moving member (18) relative to the base unit (14) is provided by a pair of antagonistically operating shape memory alloy (SMA) wires (48, 50) and transmitted via a torsional spring (56). An endoscope, or a snake-like robot (66), may include one or more of the actuators (12).

An actuator includes a drum defining a longitudinal axis and having axially opposed first and second end portions that are rotatable relative to one another about the longitudinal axis. A shape memory element is wrapped around the drum and extends from the first end portion of the drum to the second end portion of the drum to actuate relative rotation of the first and second end portions of the drum about the longitudinal axis by activation of the shape memory element.