| Thermally driven piston assembly and position control therefor -> Monitor Keywords |
|
|
  Thermally driven piston assembly and position control thereforUSPTO Application #: 20070243073Title: Thermally driven piston assembly and position control therefor Abstract: A thermally driven piston assembly comprises a material that undergoes a dimensional change when subjected to a temperature change in the temperature range of interest. The dimensional change imparts movement which effects an end result such as actuation, shock absorption, clutch action, braking, or mechanical power. The assembly can further comprise position sensing means for sensing movement of the component of interest, and passive and/or active heating and/or cooling means for effecting the temperature change. (end of abstract)
Agent: National Aeronautics And Space Administration Langley Research Center - Hampton, VA, US Inventors: Donald L. Thomsen, Robert G. Bryant USPTO Applicaton #: 20070243073 - Class: 417207000 (USPTO) Related Patent Categories: Pumps, By Heating Of Pumped Fluid The Patent Description & Claims data below is from USPTO Patent Application 20070243073. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application is a continuation-in-part application of commonly-owned application Ser. No. 11/374,480 entitled "Thermally Driven Piston Assembly and Position Control Thereof," filed Mar. 8, 2006, which is hereby incorporated by reference in its entirety. ORIGIN OF THE INVENTION [0002] The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor. BACKGROUND OF THE INVENTION [0003] 1. Field of the Invention [0004] This invention relates to actuator or damping devices utilizing a piston. More specifically, the invention is a thermally driven piston assembly and position control system therefor with the piston being able to function as an actuator or a damping device. [0005] 2. Description of the Related Art [0006] Past linear actuators requiring a transmission system to convert a motor's rotational energy into linear displacement are not practical in many space-restricted applications. More recently, linear actuators using hydraulic or pneumatic driven pistons or made from stacks of piezoelectric materials that can generate a strong linear force have been used when space is at a premium. However, hydraulically/pneumatically driven pistons require a pump to effect volumetric or pressure changes that move a piston. Piezoelectric-based linear actuators have low strain characteristics, thereby limiting their linear travel. [0007] Currently, a variety of muscle-like polymer materials are being evaluated for use in actuator or damping devices owing to their ability to undergo large changes in strain and stiffness when activated. However, there is a need to provide simple and efficient actuator "packages" for these materials that capitalize on their large strain characteristics to achieve a linear actuator or damping response. Further, since several of these polymer materials have a tendency to exhibit creep, the actuator package that includes such polymer materials must be able to compensate for a material's creep characteristics. SUMMARY OF THE INVENTION [0008] Accordingly, it is an object of the present invention to provide the means to generate a linear response using a muscle-like polymer material. [0009] Another object of the present invention is to provide the means to generate and control the response of a muscle-like polymer in order to compensate for the material's creep characteristics. [0010] Still another object of the present invention is to generate a tunable damping response using a muscle-like polymer material. [0011] In accordance with one embodiment of the present invention, a thermally driven piston assembly has a housing that remains rigid throughout a temperature and load range of interest. A first material is slidingly fitted in a hollow portion of the housing such that the first material is limited to movement along a single dimension of the hollow portion. The first material is one (e.g., a liquid crystal elastomer) that undergoes a stiffness change and/or a dimensional change when subjected to a temperature change in the temperature range of interest. When subjected to the temperature change while in the housing, the first material is restricted to changing dimensionally along the single dimension. At least one plug of a second material is slidingly fitted in the housing's hollow portion adjacent the first material. The second material retains its shape and size throughout the temperature range of interest. As a result, the plug moves in the housing's hollow portion along the aforesaid single dimension in correspondence with the dimensional change of the first material or the plug's movement is damped by the stiffness change in the first material. A position control system can be provided if the first material has inherent creep characteristics. Further embodiments may utilize active heating and/or cooling means to effect the material's shape change. [0012] Other features and advantages of the invention will be apparent from the following detailed description taken in conjunction with the following figures, wherein like reference numerals represent like features. BRIEF DESCRIPTION OF THE DRAWINGS [0013] FIG. 1 is a perspective view of a thermally driven piston assembly providing linear motion or damping forces in accordance with an embodiment of the present invention; [0014] FIG. 2 is a perspective view of a thermally driven piston assembly providing linear motion simultaneously in two opposing directions in accordance with another embodiment of the present invention; [0015] FIG. 3 is a perspective view of a thermally driven piston assembly that can generate a tension force in accordance with another embodiment of the present invention; [0016] FIG. 4 is a side view of a thermally driven piston assembly of FIG. 2 further including a controllable heater for actuating the assembly's thermally-active shape changing material; [0017] FIG. 5 is a graph of temperature versus enthalpy change for a liquid crystal elastomer; [0018] FIG. 6 is a schematic view of the thermally driven piston assembly of FIG. 1 further including a position control system coupled thereto to detect and compensate for creep inherent in the assembly's thermally-active shape changing material; [0019] FIG. 7 is a part cross-sectional, part schematic view of another embodiment of a piston assembly in accordance with the present invention. Continue reading... Full patent description for Thermally driven piston assembly and position control therefor Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Thermally driven piston assembly and position control therefor patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Thermally driven piston assembly and position control therefor or other areas of interest. ### Previous Patent Application: Laser shock peened gas turbine engine compressor airfoil edges Next Patent Application: Hydraulic control unit Industry Class: Pumps ### FreshPatents.com Support Thank you for viewing the Thermally driven piston assembly and position control therefor patent info. IP-related news and info Results in 2.48695 seconds Other interesting Feshpatents.com categories: Novartis , Pfizer , Philips , Polaroid , Procter & Gamble , |
||
