Power plants – Motor operated by expansion and/or contraction of a unit of... – Mass is a solid
Reexamination Certificate
1999-12-20
2001-05-08
Nguyen, Hoang (Department: 3748)
Power plants
Motor operated by expansion and/or contraction of a unit of...
Mass is a solid
C060S527000
Reexamination Certificate
active
06226992
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a heat converter engine, and more particularly, to an actuator assembly using a shape memory material that can be used as the driving force component in a heat converter engine that may be used as an alternative power source.
BACKGROUND INFORMATION
A class of materials called shape memory alloys (SMA) exhibits a non-linear relationship between stress and strain when exposed to temperature changes. These alloys undergo a temperature related phase change that allows the SMA to return to any mechanical configuration imposed on the SMA when it is annealed. When the SMA is below its critical temperature, it becomes malleable and may be deformed into any arbitrary shape. Upon heating the SMA above the critical temperature, it undergoes a change in crystal structure and quickly resumes its stiff original shape. Cooling the SMA to below the critical temperature will, again, cause it to return it to the cold malleable condition allowing it to be deformed, but always returning to its original shape when it is heated above the critical temperature. The best known SMA is Nitinol, a titanium nickel alloy, having 53.5-56.5% nickel content by weight. With a temperature change of as little as 18° F., Nitinol can exert a force of as much as 60,000 psi when exerted against a resistance to changing its shape.
Several prior art patents have disclosed the use of SMAs as actuators. For example, U.S. Pat. No. 4,932,210 to Julien et al. discloses the use of a shape memory alloy actuator for accurately pointing or aligning a moveable object. The SMA elements are arranged in a push-pull configuration so that one element in the activated state moves the object while another element on the opposite side in the soft state acts as a dynamic damper to prevent overtravel of the object. Similarly, U.S. Pat. No. 5,061,914 to Busch et al. discloses SMA actuators that are mechanically coupled to one or more movable elements such that the temperature induced deformation of the actuators exerts a force or generates motion of the mechanical element. However, these systems are used for precision type operations and produce little output power. These systems are not suitable for producing enough power to drive small pumps or motors, for example, a water pump in an automobile.
Several prior art patents also describe the use of SMAs to drive a shaft in a motor. For example, U.S. Pat. No. 4,665,334 to Jamieson discloses a rotary stepping device having a rotatable shaft which is driven by a coiled spring clutch. An actuator made of an SMA is heated and used to pull the spring clutch to tighten it and rotate the shaft. When the SMA is cooled it returns to its malleable state and releases the spring clutch which loosens from around the shaft and returns to its original position without rotating the shaft in the opposite direction. U.S. Pat. No. 4,027,479 to Cory discloses a heat engine with an endless belt which includes a number of high density elements secured to lengths of SMA wire. The belt is attached to a pulley connected to a shaft. Two portions of the belt are maintained at different temperatures and the belt is constrained to move the elements in a continuous path into a field attracting the elements at the hot portion and out of the field at the cold portion. The SMA wire in the cold portion is stretched and the SMA wire in the hot portion contracts resulting in higher element density on the portion entering the field and thus a net force drives the belt about the pulley. However, these systems are also limited in their energy output and their complicated construction makes them impractical for use in standard machinery such as an engine or motor.
SUMMARY OF THE INVENTION
A heat converter engine comprising a crank shaft, an actuator assembly coupled to the crank shaft, and a heating means. The actuator assembly includes a plurality of shape memory elements that are malleable when below a critical temperature and return to their original shape when above the critical temperature. The heating means raises the temperature of a first portion of the shape memory elements above the critical temperature and a cooling means lowers the temperature of a second portion of the shape memory elements below the critical temperature. This action of heating and cooling the shape memory elements causes rotation of the crank shaft.
REFERENCES:
patent: 3213606 (1965-10-01), Martin et al.
patent: 3229177 (1966-01-01), Clarke
patent: 3303642 (1967-02-01), Lee II
patent: 3317135 (1967-05-01), Feinberg
patent: 4027479 (1977-06-01), Cory
patent: 4665334 (1987-05-01), Jamieson
patent: 4932210 (1990-06-01), Julien et al.
patent: 5061914 (1991-10-01), Busch et al.
patent: 5543678 (1996-08-01), Hoiberg
patent: 5734219 (1998-03-01), Horski et al.
patent: 5742106 (1998-04-01), Muraji
patent: 5747951 (1998-05-01), Audren
patent: 5763979 (1998-06-01), Mukherjee et al.
Kutlucinar Iskender V.
Saul Andrew M.
Hycomp, Inc.
Kenyon & Kenyon
Nguyen Hoang
LandOfFree
Heat converter engine using a shape memory alloy actuator does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Heat converter engine using a shape memory alloy actuator, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Heat converter engine using a shape memory alloy actuator will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2504671