Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
2000-04-11
2001-08-28
Mullins, Burton S. (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S152000, C310S156010, C310S0400MM, C219S201000
Reexamination Certificate
active
06281611
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally pertains to electrically energized heating devices, and more specifically, to a heating device that heats a substance via a contactless transfer of electromagnetic energy provided by a moving magnet.
BACKGROUND OF THE INVENTION
Portable hot plates are often used for warming and maintaining the temperature of heated beverages, such as coffee, tea, hot apple cider, etc., and food such as soups. These devices are also used in the laboratory for heating substances. Hot plates generally include a supporting surface upon which the base of a container (e.g., a coffee cup, chemistry flask, etc.) is placed while undergoing heat transfer from a heat source within the hot plate. An electric resistance heating element is typically used for the heat source and dissipates enough energy to achieve a moderately high to high temperature (e.g., up to several hundred degrees C.).
A major drawback of most portable hot plates is that they represent a significant risk of burning anyone who contacts the surface that supports a container to be heated when the surface is hot. Children are especially at risk. In order to maintain a beverage such as coffee at a desired temperature, it is necessary that the heat transferred from the hot plate to the container match the heat lost from the container (and the liquid contained therein) to the environment.
Since it is desirable to keep heated beverages hot, coffee cups and the like are typically made of materials that have a relatively low thermal conductivity, such as refractory materials, glass, plastic, etc. However, the insulating properties of these materials act as an impediment in heating a beverage in the container with a hot plate. As a result, the hot plate must be maintained at a temperature much higher than the desired temperature of the beverage. This temperature is often high enough to cause moderate to severe burns to anyone who accidentally touches the hot plate when it is at its normal operating temperature.
The manner in which hot plates are typically used exacerbates the foregoing problem. Most portable hot plates have a power switch, and may also include a temperature control. In order to heat something with a hot plate, it is necessary to at least turn the power switch on and it may be necessary to set the temperature control knob to a desired setting. It is not uncommon to accidentally leave a hot plate energized after it has been used. Furthermore, even if properly turned off after use, the power switch can easily be turned on by a curious child, posing a significant safety hazard for children, as well as a potential fire hazard.
It is therefore desirable to provide a portable apparatus for heating a substance, such as a beverage or food, that does not require the use of a high temperature heat source in the apparatus. Furthermore, it is desirable that such an apparatus only operate when the substance is being heated and automatically shut off when a container containing the substance is removed from the apparatus.
SUMMARY OF THE INVENTION
In accord with the present invention, a method and apparatus are defined to enable a substance to be safely heated without using a surface that is maintained at a high temperature to transfer heat into a container for the substance. The apparatus includes a container in which the substance is disposed and the container is adapted to be supported on a surface defined by a housing for a magnetic field generator that produces a varying magnetic field. A ferromagnetic conductor, preferably comprising a “lossy” ferromagnetic material such as “soft” iron, is disposed in a base of the container. When being heated by the apparatus, the base of the container is supported by the surface. The magnetic field generator disposed in the housing includes at least one permanent magnet. A prime mover, preferably an electric motor, is drivingly coupled to an element of the magnetic field generator, causing the element of the magnetic field generator to move relative to the ferromagnetic conductor in the base of the container. Movement of the element produces a varying magnetic field that induces an electrical eddy current to circulate within the ferromagnetic conductor. This electrical eddy current generates heat due to resistive losses, increasing the temperature of the ferromagnetic conductor. Heat is transferred from the ferromagnetic conductor to the substance disposed in the container through the base, thereby heating the substance.
In one embodiment, the element of the magnetic field generator includes a plurality of permanent magnets that are mounted on a movable support. This movable support rotated or reciprocated back and forth relative to the ferromagnetic conductor, so that a magnetic field is varied along a path that includes the ferromagnetic conductor.
In another embodiment, the element of the magnetic filed generator that is drivingly coupled to the prime mover comprises a magnetic flux shunt that is moved by the prime mover and periodically shunts the magnetic field produced by the one or more permanent magnet. Movement of the magnetic flux shunt thus varies the magnetic field along a path that includes the ferromagnetic conductor.
The container preferably includes an insulation layer around its sides or the sides comprise a material with good insulating properties. The insulating layer preferably includes an external wall and internal wall made of a low thermal conductivity material and separated by an air gap.
A further aspect of the present invention is directed to a method for heating a substance by inductively coupling a varying magnetic field to a ferromagnetic conductor disposed in a container in which the substance is disposed. The steps of this method are generally consistent with the functions provided by the elements of the apparatus discussed above.
REFERENCES:
patent: 2481196 (1949-09-01), Bulliet
patent: 3668448 (1972-06-01), Hayasaka
patent: 3672352 (1972-06-01), Summers
patent: 3836289 (1974-09-01), Wolford et al.
patent: 3942535 (1976-03-01), Schulman
patent: 3967146 (1976-06-01), Howard
patent: 4005346 (1977-01-01), Hisa
patent: 4038572 (1977-07-01), Hanagan
patent: 4038625 (1977-07-01), Tompkins et al.
patent: 4082936 (1978-04-01), Aoki et al.
patent: 4163164 (1979-07-01), Pieters
patent: 4338951 (1982-07-01), Saliga
patent: 4392071 (1983-07-01), Gauthier
patent: 4432363 (1984-02-01), Kakegawa
patent: 4443776 (1984-04-01), Cunningham
patent: 4461302 (1984-07-01), Phillipps et al.
patent: 4507048 (1985-03-01), Belenger et al.
patent: 4511777 (1985-04-01), Gerard
patent: 4564778 (1986-01-01), Yoshida
patent: 4665896 (1987-05-01), LaForge et al.
patent: 4679560 (1987-07-01), Galbraith
patent: 4736752 (1988-04-01), Munck et al.
patent: 4741339 (1988-05-01), Harrison et al.
patent: 4761527 (1988-08-01), Mohr
patent: 4798926 (1989-01-01), Sakai
patent: 4831299 (1989-05-01), Hayasaka
patent: 4927337 (1990-05-01), Lustwerk
patent: 5109843 (1992-05-01), Melvin et al.
patent: 5112200 (1992-05-01), Isaacson et al.
patent: 5146123 (1992-09-01), Yarr
patent: 5274207 (1993-12-01), Griffith
patent: 5314457 (1994-05-01), Jeutter et al.
patent: 5350413 (1994-09-01), Miller
patent: 5550452 (1996-08-01), Shirai et al.
patent: 5569156 (1996-10-01), Mussivand
patent: 5690851 (1997-11-01), Yoshioka et al.
patent: 5710502 (1998-01-01), Poumey
patent: 5945762 (1999-08-01), Chen et al.
patent: 5959433 (1999-09-01), Rohde
patent: 6011245 (2000-01-01), Bell
Hilton, Edgar F., et al. “Magnetic Suspension Controls for a New Continuous Flow Ventricular Assist Device.” ASAIO Journal, 1977, 43:M598-M603.
Kono, Satoshi, et al. “In Vivo and In Vitro Evaluation of the Pulsatile Mode of a Magnetically Suspended Centrifugal Pump.” ASAIO Journal, 1977, 43:M580-M584.
Xu, Longya, et al. “Analysis of a New PM Motor Design for a Rotary Dynamic Blood Pump.” ASAIO Journal, 1997, 43:M559-M564.
Yamane, Takashi, et al. “Fluid Dynamic Characteristics of Monopivot Magnetic Suspension Blood Pumps.” ASAIO Journal, 1997, 43:M635-M638.
Matsushita Electronic Components Web site. Mo
Chen James C.
Huston Darrin
Anderson Ronald M.
Light Sciences Corporation
Mullins Burton S.
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