Granted Patent B2

US 8,290,724 · App. 12/291,337 · Granted Oct 16, 2012

Abstract

Claims (48)

1. A method for calibrating a synthetic jet ejector having an actuator equipped with an actuator coil, the method comprising:

taking a first measurement DCR 1 of the DC resistance of the actuator coil;

adjusting the actuator drive voltage V d to achieve a maximum displacement x 0 at a frequency w 0 ;

measuring the input current I in and input voltage V in required to achieve the maximum displacement x 0 at the frequency w 0 ;

calculating the Back Electromotive Force (B EMF ), wherein B EMF =V in −I in *DCR 1 ;

storing the calculated value of B EMF in a memory device associated with the synthetic jet actuator; and

using the calculated B EMF to calibrate the synthetic jet ejector.

2. The method of claim 1 , further comprising:

taking a second measurement DCR 2 of the DC resistance of the actuator coil.

3. The method of claim 2 , further comprising:

setting V d to a nominal value at the frequency w 1 ; and

increasing B EMF until B EMF =B EMFT , where B EMFT is the Back Electromotive Force at which x=x 1 and v=v 0 , wherein v 0 (t)=dx 0 /dt, wherein x 1 is the measured maximum displacement, and wherein v is the measured velocity.

4. The method of claim 2 , wherein the actuator is adapted to operate at a frequency w 1 ≠w 0 , wherein B EMF1 is the value of B EMF at w 1 , and wherein B EMF1 =B EMF *x 1 /x 0 .

5. The method of claim 2 , wherein the actuator is adapted to operate at a displacement x 1 ≠x 0 , wherein B EMF1 is the value of B EMF at x 1 , and wherein B EMF1 =B EMF *x 1 /x 0 .

6. The method of claim 1 , further comprising:

periodically measuring DCR and calculating B EMF such that B EMF =B EMF0 .

7. The method of claim 6 , wherein B EMF is calculated from DCR in accordance with the equation B EMF =V in −I in *DCR.

8. The method of claim 1 , wherein the input current I in and input voltage V in are measured at x 0 and w 0 .

9. A method for calibrating a synthetic jet ejector, comprising:

providing a synthetic jet ejector equipped with a coil, wherein the coil causes a diaphragm to vibrate about a first axis which is perpendicular to a major surface of the diaphragm;

applying a periodic force such that the diaphragm is deflected from a resting position to a maximum displacement d 0 along the first axis, wherein d 0 is equal to the desired maximum displacement of the diaphragm during operation of the synthetic jet ejector;

measuring the electromagnetic force voltage across the coil; and

using the measured electromagnetic force to calibrate the synthetic jet ejector.

10. The method of claim 9 , wherein the periodic force moves the synthetic jet ejector along the first axis.

11. The method of claim 9 , wherein the coil is an actuator coil, and wherein the electromagnetic force voltage is measured across the leads of the coil.

12. The method of claim 9 , wherein the periodic force is created by shaking the synthetic jet ejector.

13. The method of claim 12 , wherein the synthetic jet ejector is shaken along the first axis.

14. A method for determining the Back Electromotive Force (B EMF ) in a coil of a synthetic jet ejector, comprising:

providing a synthetic jet ejector equipped with a first coil, wherein the first coil causes a diaphragm to vibrate about a first axis which is perpendicular to a major surface of the diaphragm;

providing a second coil; and

using the second coil to determine B EMF ;

wherein the B EMF is determined by utilizing the second coil to determine the B EMF voltage across the first coil.

15. The method of claim 14 , wherein the first and second coils are co-wound.

16. The method of claim 14 , wherein the first and second coils are wound about a common axis.

17. The method of claim 16 , wherein the second coil has a larger average diameter than the first coil.

18. The method of claim 16 , wherein the second coil has a larger minimum diameter than the first coil.

19. The method of claim 16 , wherein the second coil is vertically disposed along the first axis with respect to the first coil.

20. The method of claim 14 , further comprising a third coil, wherein the second and third coils are used to determine B EMF .

21. The method of claim 20 , wherein the first and second coils are used to detect offsets or abnormalities in the motion of the first coil.

22. A method for determining Back Electromotive Force (B EMF ) in a synthetic jet ejector having first and second actuators, comprising:

deactivating the first actuator while operating the second actuator, thereby placing the synthetic jet ejector into a first operational state;

determining the Back Electromotive Force (B EMF1 ) of the first actuator while the synthetic jet ejector is in the first operational state;

deactivating the second actuator while operating the first actuator, thereby placing the synthetic jet ejector into a second operational state; and

determining the Back Electromotive Force (B EMF2 ) of the second actuator while the synthetic jet ejector is in the second operational state.

23. The method of claim 22 , wherein the first and second actuators are disposed in a common housing.

24. The method of claim 22 , wherein the first and second actuators are equipped with first and second drive coils, and wherein B EMF1 and B EMF2 are determined using a third coil.

25. The method of claim 22 , wherein the measured values of B EMF1 and B EMF2 are used to modify drive characteristics of the first and second actuators.

26. The method of claim 22 , wherein the measured values of B EMF1 and B EMF2 are used to modify the operational characteristics of the synthetic jet ejector.

Assignments (15)