US20080085197A1

US20080085197A1 - Magnetostriction air pump

Info

Publication number: US20080085197A1
Application number: US11/545,132
Authority: US
Inventors: Bryan Wayne McCoy; Jason Walter Swanson
Original assignee: Mobility Electronics Inc
Current assignee: Igo Inc
Priority date: 2006-10-09
Filing date: 2006-10-09
Publication date: 2008-04-10

Abstract

A magnetostriction based pump for cooling a power supply is provided. One exemplary embodiment of the invention utilizes one of the components that is already present in the power supply. The expense of the cooling system is minimized, as it is limited to a diaphragm and any channel routing. The airflow can be targeted at multiple devices by adding additional cooling channels or channeling the flow of air over multiple components.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

Cross reference is made to the following commonly assigned U.S. patent applications filed herewith: U.S. Ser. No. TBD, entitled “MAGNETOSTRICTION AIDED SWITCHING.”

FIELD OF THE INVENTION

The present invention is generally related to power supplies, and more specifically to heat reduction in power adapters and power converters.

BACKGROUND OF THE INVENTION

Notebook adapters, wall adapters, and car adapters all suffer from large power losses when voltage is converted from one form to another. The power that is not converted to a usable energy source is dissipated as heat to the environment. If a power supply maximum temperature was not regulated, the power supply could be made as small as part geometry would allow. However, due to guidelines by certification organizations such as Underwriters Laboratory (UL) and Technischer Überwachungsverein (TUV), the maximum temperature is usually limited to 85 degrees Celsius. In order to meet this limitation, the size of power supplies is typically increased in order to provide greater surface area for the dissipation of heat.
One way to reduce the size of the power supply is to use forced air-cooling/active cooling in which air is moved over the heat producing components in order to conduct the heat away from the main body of the power supply. The size can also be reduced by improving electrical efficiencies.
Prior active cooling solutions have used fans and diaphragm pumps. Fans can be positioned at one end of a power supply to push or pull air over the heated components. Diaphragm pumps use an electronically driven magnet to push and pull a diaphragm, moving air over a hot component or components, thus cooling in small bursts. The fan solution to active cooling is noisy, expensive, requires additional space, and has a short lifetime. Diaphragm pumps are expensive, large, draw ample amounts of energy/electricity and generally target only one hot component in a power supply.

SUMMARY OF INVENTION

The present invention achieves technical advantages as a magnetostriction based air pump for cooling a power supply. One exemplary embodiment of the invention utilizes one of the components that is already present in the power supply. The expense of the cooling system is minimized, as it is limited to a diaphragm and any channel routing. The airflow can be targeted at multiple devices by adding additional cooling channels or channeling the flow of air over multiple components.

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.

Claims

1. A magnetostriction pump comprising:

a structure of magnetostrictive material configured to form a passageway containing a coolant;

a magnetic field generator configured to create an alternating magnetic field in the structure of magnetostrictive material; and

wherein the coolant is forced through the passageway by expansion and compression of the structure of magnetostrictive material when the magnetic field generator operates.

2. The magnetostriction pump of claim 1 further comprising a diaphragm disposed in the passageway.

3. The magnetostriction pump of claim 1 further comprising a tube coupled to the passageway.

4. The magnetostriction pump of claim 1 further comprising a valve coupled to the passageway.

5. The magnetostriction pump of claim 1 further comprising a tube coupled to the passageway.

6. The magnetostriction pump of claim 1 wherein the structure of magnetostrictive material further comprises:

a circuit component having a magnetic flux conducting material; and

a magnetic shunt of magnetostrictive material configured to be attached to the magnetic flux conducting material of the circuit component so as to form the passageway.

7. The magnetostriction pump of claim 1 wherein the coolant is air.

8. A method for pumping a fluid comprising:

creating magnetic flux in a structure of magnetostrictive material, where the structure has a passageway;

disposing a coolant in the passageway; and

alternating the direction of the magnetic flux so as to cause the passageway to increase and decrease in volume due to magnetostrictive contraction and expansion, causing the coolant to flow in and out of the passageway.

9. The method of claim 8 further comprising causing the coolant to flow in one direction through the passageway.

10. The method of claim 8 wherein disposing the coolant in the passageway comprises disposing an air-filled diaphragm in the passageway.

11. The method of claim 8 wherein disposing the coolant in the passageway comprises disposing an air-filled diaphragm having a one-way valve on one end in the passageway.

12. The method of claim 8 further comprising directing the coolant onto an electrical component so as to provide cooling to the electrical component.

13. The method of claim 8 further comprising directing the coolant through tubing onto an electrical component so as to provide cooling to the electrical component.

14. The method of claim 8 further comprising directing the coolant through one or more channels onto an electrical component so as to provide cooling to the electrical component.