BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a drawing of magnetic domains in a natural state and exposed to a magnetic field;
FIG. 2 shows an electrical schematic of a magnetostrictive pump in accordance with an exemplary embodiment of the present invention; and
FIG. 3 shows a magnetostrictive pump construction in accordance with an exemplary embodiment of the present invention.
DETAILED DESCRIPTION OF THE PRESENT INVENTION
Referring to FIG. 1, there is generally shown at 10 a drawing of magnetic domains in a natural state and exposed to a magnetic field. In all ferromagnetic materials used in switching power supplies, there are polarized magnetic domains 12 which naturally occur in a random distribution 14. However, when the magnetic field is applied to the ferromagnetic material, the magnetic domains 12 move and realign in an ordered distribution 16 in the direction of the magnetic field. This realignment of domains creates a change in size dimensions 18 of the ferromagnetic material, an effect known as “magnetostriction.”
Referring now to FIG. 2, there is shown an electrical schematic of a current regulator 20 utilizing a magnetostrictive pump in accordance with an exemplary embodiment of the present invention. Current regulator 20 includes a current transformer 22 and a switching MOSFET 24. Physical expansion and contraction of ferromagnetic material 26 that comprises the core of the current transformer 22 at the circuit's fundamental switching frequency can be optimized by using a material that has a large coefficient of magnetostriction. The current transformer 22 is typically used in power supplies to reduce the energy losses from current sense resistors. Advantageously, by using the ferromagnetic material 26 with a large magnetostriction coefficient in the current transformer 22 between the ferromagnetic material 26 surrounded by the coils, the normal operation of the power supply can be maintained while also providing cooling to the power supply when used in conjunction with a magnetostrictive pump.
When the switching MOSFET 24 opens, the ferromagnetic material 26 expands or contracts (depending on the sign of the coefficient of magnetostriction) up to the point of saturation, at which point any additional expansion or contraction of ferromagnetic material 26 is negligible. The expansion and contraction can be configured to create an air flow proximate to the heat generating components, such as by using diaphragms, channels, or other suitable materials. The construction of the magnetostrictive pump is not limited to a current transformer 22, but can be implemented with any suitable device that uses ferromagnetic material to conduct magnetic flux, including but not limited to motors, relays, magnetic latches, or other devices which can be constructed from ferromagnetic materials having large magnetostriction coefficients.
Referring now to FIG. 3, there is shown at 30 a drawing of a current transformer pump construction in accordance with an exemplary embodiment of the present invention. If a current transformer 22 is constructed as shown in FIG. 3, the outer dimensions can be fixed by a copper wire 34, so as to force the ferromagnetic material 26 to expand inward and compress the walls of a diaphragm 36 and force air to move. Diaphragm 36 can be fabricated from natural or synthetic rubber, polymers, plastics, or other suitable materials, and can be provided with valves, tubing, channels, or other suitable devices to direct the flow of air or other coolants. The copper wire 34 can be embedded in a printed circuit board, fixed with a resin material, or can otherwise be disposed adjacent to ferromagnetic material 26. The volume of air that is moved is related to the applied magnetic field, the size of the magnetic device 30, the coefficient of magnetostriction of the ferromagnetic material 26, and the size of the diaphragm 36. The exemplary implementation of the invention shown in FIG. 3 is only slightly larger than the original component. The diaphragm mechanism 36 can be used in any suitable magnetic device to create multiple pumps inside a power supply. Because of the large number of irregularly-shaped surfaces inside of power supplies and other electrical equipment, the amount of air moving inside the power supply does not need to be large to overcome the viscous forces that create laminar flow and prevent cooling. Each pump can be sealed off from the internal power supply and the air can be routed through a cooling hose 38. However, the cooling hose 38 is not required for the invention to perform its intended function.
Though the invention has been described with respect to a specific preferred embodiment, many variations and modifications will become apparent to those skilled in the art upon reading the present application. It is therefore the intention that the appended claims be interpreted as broadly as possible in view of the prior art to include all such variations and modifications.
Patent Application
20080085197
