Adjustable seat ramp utilizing active material actuation
An adjustable seat ramp adapted for use with a seat base and defining a first angle of inclination, includes a structure translatably disposed within or integrally formed with the base and presenting a first position, and further includes an actuator employing a shape memory material element and configured to cause the structure to translate to a second position, wherein a second angle of inclination is defined.
1. An adjustable seat ramp adapted for use with a seat base defining an engagement surface, wherein the surface defines a distal edge and an interior region, and the edge and region cooperatively define a first height, said ramp comprising:
a moveable structure disposed within the base, presenting a first position and orientation relative to the surface; and
an actuator drivenly coupled to the moveable structure and including an active material element operable to undergo a reversible change when exposed to or occluded from an activation signal,
wherein the actuator is configured to cause the moveable structure to translate to a second position or orientation and the moveable structure and base are cooperatively configured to modify the edge or region, so as to define a second height therebetween, as a result of the change, the actuator further includes an overload protector connected to the active material element opposite the moveable structure, and configured to present a secondary work output path, when the active material element is activated and the moveable structure is unable to be moved, the overload protector includes an extension spring in series connection to the active material element, the protector further includes a lever intermediate the active material element and spring, the lever defines first and second arms and a pivot axis, the active material element is attached to one of said arms and spaced from the axis a first distance, and the spring is attached to the other of said arms and spaced from the axis a second distance greater than the first.
2. The ramp as claimed in claim 1 , wherein the active material element is a shape memory alloy wire.
3. The ramp as claimed in claim 2 , wherein the moveable structure includes a panel and a pivot tube fixedly connected to the panel and rotatably coupled to a fixed member distending therefrom, and the wire is connected to the panel and to the fixed member at a point spaced from the tube.
4. The ramp as claimed in claim 1 , wherein the base includes a flexible outer covering section configured to facilitate the movement of the moveable structure to the second position or orientation.
5. The ramp as claimed in claim 1 , further comprising a locking mechanism configured to engage the structure when in the second position or orientation, so as to retain the locking mechanism in the second position or orientation, when the change is reversed.
6. The ramp as claimed in claim 5 , wherein the locking mechanism includes a second active material element operable to undergo a second change when exposed to an activation signal, and configured to cause the locking mechanism to disengage the structure, as a result of the change.
7. The ramp as claimed in claim 1 , further comprising
a return mechanism drivenly coupled to the moveable structure antagonistically to the actuator, and producing a biasing force less than the actuation force, such that the locking mechanism causes the moveable structure to move to the first position when the active material element is deactivated and allows the actuator to drive the moveable structure to the second position when the active material element is activated.
8. The ramp as claimed in claim 7 , wherein the return mechanism is selected from the group consisting essentially of compression, extension, leaf, torsion, hydraulic/pneumatic springs, elastomeric components, counterweights, and a second active material element.