Micro pump

• US 6,716,002 B2
• Filed: 05/15/2001
• Issued: 04/06/2004
• Est. Priority Date: 05/16/2000
• Status: Expired due to Term

• Current Assignee: Minolta Co., Ltd. (Konica Minolta Inc.)
• Original Assignee: Minolta Co., Ltd. (Konica Minolta Inc.)
• Inventors: Higashino, Kusunoki
• Primary Examiner(s): Freay, Charles G.
• Assistant Examiner(s): GRAY, MICHAEL KUHN
• Application Number:
  US09/855,371
• Publication Number:
  US 20020009374A1
• Time in Patent Office: 1,057 Days
• Field of Search: 417/413.2, 417/413.3, 417/212, 417/322, 417/557
• US Class Current: 417/413.2
• CPC Class Codes: F04B 43/046 with piezoelectric drive

Abstract

The micro pump 100 comprises a first flow pass 115 for changing the flow pass resistance in accordance with the differential pressure, a second flow pass 117 wherein the percentage change in flow pass resistance relative to the differential pressure is less than that of the first flow pass 115, pressure chamber 109 connected to the first flow pass 115 and the second flow pass 117, and a piezoelectric element 107 for changing the pressure within the pressure chamber 109 so as to transport minute amounts of fluid with high precision using a simple construction. The ratio of the flow pass resistance of the first flow pass 115 and the flow pass resistance of the second flow pass 117 differs by changing the pressure within the pressure chamber 109 via the piezoelectric element 107, such that fluid can be transported in a standard direction and an opposite direction.

Claims

1. A micro pump comprising:

a first area including a first flow pass, said first area having a variable flow pass resistance in accordance with a difference in pressure between bilateral ends of the first flow pass area,

a second area including a second flow pass, said second area having a variable flow pass resistance is changed in accordance with a difference in pressure between bilateral ends of the second area, wherein a percentage change in the flow pass resistance of the second area in accordance with the difference in pressure between the bilateral ends of the second area is smaller than a percentage change in the flow pass resistance of the first in accordance with the difference in pressure between the bilateral ends of the first area;

a pressure chamber connecting the first flow pass to the second flow pass;

an actuator for changing a pressure force within the pressure chamber; and

a driver for selectively applying to said actuator voltage signals having a first waveform and a second waveform, wherein the voltage signals of the first waveform are for transporting fluid in the pressure chamber toward the first flow pass and the voltage signals of the second waveform are for transporting fluid in the pressure chamber toward the second flow pass.

2. A micro pump according to claim 1,

wherein the actuator changes the pressure force within the pressure chamber by changing a volume of the pressure chamber.

3. A micro pump according to claim 1,

wherein the first flow pass has uniform cross sectional configurations taken in planes that are orthogonal to flow directions, through the first flow pass,

wherein the second flow pass has uniform cross sectional configurations taken in planes that are orthogonal to flow directions through the second flow pass, and

wherein the ratio of the cross sectional area of the first flow pass relative to a flow pass length of the first flow pass is greater than the ratio of the cross sectional area of the second flow pass relative to a flow pass length of the second flow pass.

4. A micro pump according to claim 1,

wherein the first flow pass has a first cross sectional configuration taken in a first plane that is orthogonal to a flow direction through the first flow pass and has a second cross sectional configuration taken in a second plane that is parallel to the first plane and taken at a different position than that of the first plane with respect to the flow direction through the first flow pass, and

wherein a shape of the first cross sectional configuration is different from a shape of the second sectional configuration.

5. A micro pump according to claim 1,

wherein the first flow pass has a shape of which a center line thereof is not straight.

6. A micro pump according to claim 1,

wherein the first flow pass has an obstruction therein.

7. A micro pump according to claim 1,

wherein each of the first flow pass and the second flow pass has a tapered shape,

wherein aspect ratios of the tapered shapes are different from each other.

8. A micro pump according to claim 1,

wherein the actuator comprises a piezoelectric element.

9. A micro pump according to claim 1,

wherein the driver drives the actuator to repeatedly change a volume of the pressure chamber between a first volume and a second volume at specific intervals,

wherein at least one of the first and second waveforms has a first time period required to change the volume of the pressure chamber from the first volume to the second volume and a second time period required to change the volume of the pressure chamber from the second volume to the first volume, and

wherein the first time period and second time period are different from each other.

10. A micro pump according to claim 9,

wherein the at least one of the first and second waveform has a third time period, during which an amplitude of the voltage signal is not changed, between the first time period and the second time period.

11. A micro pump according to claim 1,

wherein the driver drives the actuator to repeatedly change a volume of the pressure chamber between a first volume and a second volume at specific intervals, and

wherein a time period of the first waveform required to change the volume of the pressure chamber from the first volume to the second volume is different from a time period of the second waveform required to change the volume of the pressure chamber from the first volume to the second volume for the purpose of changing direction of transport of the fluid.

12. A micro pump according to claim 9,

wherein the actuator comprises a piezoelectric element.

13. A micro pump according to claim 1,

wherein the driver drives the actuator to repeatedly change a volume of the pressure chamber between a first volume and a second volume at specific intervals,

wherein the first area has a first flow pass resistance characteristic when the fluid flows in a first direction and a second flow pass resistance characteristic when the fluid flows in a second direction opposite to the first direction, the first flow pass resistance characteristic having a pressure dependency greater than that of the second flow pass resistance characteristic,

wherein, in the first waveform, a time period for increasing the volume of the pressure chamber is identical to a time period for decreasing the volume, and

wherein, in the second waveform, a time period for increasing the volume of the pressure chamber is different from a time period for decreasing the volume.

14. A micro pump according to claim 13,

wherein the actuator comprises a piezoelectric element.

15. A micro pump comprising:

a pressure chamber for accommodating a fluid;

an actuator which is capable of repeatedly increasing and decreasing an internal pressure of the pressure chamber, in accordance with at least one of a first prescribed manner and a second prescribed manner,

a first flow pass connected with the pressure chamber, wherein the fluid is capable of flowing through the first flow pass to or from the pressure chamber, and

a second flow pass connected with the pressure chamber, wherein the fluid is capable of flowing through the second flow pass to or from the pressure chamber,

wherein, under the first prescribed manner, a first area including the first flow pass has a first flow pass resistance when the internal pressure is increased and a second flow pass resistance when the internal pressure is decreased, while a second area including the second flow pass has a third flow pass resistance that is greater than the first flow pass resistance when the internal pressure is increased and a fourth flow pass resistance that is smaller than the second flow pass resistance when the internal pressure is decreased,

wherein, under the second prescribed manner, the first area has a fifth flow pass resistance when the internal pressure is increased and a sixth flow pass resistance when the internal pressure is decreased, while the second area has a seventh flow pass resistance that is smaller than the fifth flow pass resistance when the internal pressure is increased and an eighth flow pass resistance that is greater than the sixth flow pass resistance when the internal pressure is decreased.

16. A micro pump according to claim 15, further comprising:

a driver, connected with the actuator, being capable of sequentially applying to the actuator voltage signals of a first waveform so that the actuator repeatedly increases and decreases the internal pressure of the pressure chamber in accordance with the first prescribed manner.

17. A micro pump according to claim 16,

wherein the first waveform comprises a rising time period during which an amplitude of the voltage signal is increased and a falling time period during which the amplitude of the voltage signal is decreased.

18. A micro pump according to claim 17,

wherein the rising time period and the falling time period respectively require a first time period length and a second time length.

19. A micro pump according to claim 18,

wherein the first time length is different from the second time length.

20. A micro pump according to claim 18,

wherein the first waveform further comprises, between the rising time period and the falling time period, a keeping time period during which an amplitude of the voltage signal is maintained.

21. A micro pump according to claim 18,

wherein the first time length and the second time length are identical.

22. A micro pump according to claim 21,

wherein the first waveform has a shape of a sine wave.

23. A micro pump according to claim 16,

wherein the driver is further capable of sequentially applying to the actuator second voltage signals of a second waveform that is different from the first waveform so that the actuator repeatedly increases and decreases the internal pressure of the pressure chamber in accordance with the second prescribed manner.

24. A micro pump according to claim 15,

wherein a cross sectional configuration of the first flow pass is identical to a cross sectional configuration of the second flow pass, and

wherein a length of the first flow pass is different from a length of the second flow pass.

25. A micro pump according to claim 15,

wherein a shape of the first flow pass is different from a shape of the second flow pass.

26. A micro pump according to claim 25,

wherein at least one of the first flow pass and the second flow pass has a tapered shape.

27. A micro pump according to claim 25,

wherein at least one of the first flow pass and the second flow pass has a cross sectional configuration which changes in a stepwise manner.

28. A micro pump according to claim 25,

wherein at least one of the first flow pass and the second pass has an obstruction therein.

29. A micro pump according to claim 15,

wherein the actuator comprises a piezoelectric element.

30. A micro pump according to claim 29, wherein the actuator further comprises:

an oscillating plate to which the piezoelectric element is disposed.

31. A micro pump according to claim 30,

wherein a main surface of the oscillating plate forms a wall of the pressure chamber.

32. A micro pump comprising:

a pressure chamber for accommodating a fluid;

an actuator which is capable of repeatedly pressurizing the fluid in the pressure chamber in accordance with a first prescribed manner and a second prescribed manner;

a first flow pass connected with the pressure chamber, wherein the fluid is capable of flowing through the first flow pass to and from the pressure chamber; and

a second flow pass connected with the pressure chamber, wherein the fluid is capable of flowing through the second flow pass to and from the pressure chamber,

wherein, under the first prescribed manner, a first area including the first flow pass has a first flow pass resistance when the fluid in the pressure chamber is pressurized, while a second area including the second flow pass has a second flow pass resistance that is greater than the first flow pass resistance when the fluid in the pressure chamber is pressurized, and

wherein, under the second prescribed manner, the first area has a third flow pass resistance when the fluid in the pressure chamber is pressurized, while the second area has a fourth flow pass resistance that is smaller than the third flow pass resistance when the fluid in the pressure chamber is pressurized.

33. A micro pump according to claim 32, further comprising:

a driver, connected with the actuator, being capable of sequentially applying to the actuator voltage signals of a first waveform so that the actuator repeatedly pressurizes the fluid in the pressure chamber in accordance with the first prescribed manner, and being capable of sequentially applying to the actuator voltage signals of a second waveform that is different from the first waveform so that the actuator repeatedly pressurizes the fluid in the pressure chamber in accordance with the second prescribed manner.

34. A micro pump according to claim 33,

wherein the first waveform comprises a rising time period during which an amplitude of the voltage signal is increased and a falling time period during which the amplitude of the voltage signal is decreased.

35. A micro pump according to claim 34,

wherein the rising time period and the falling time period respectively require a first time period length and a second time length.

36. A micro pump according to claim 35,

wherein the first time length is different from the second time length.

37. A micro pump according to claim 35,

wherein the first waveform further comprises, between the rising time period and the falling time period, a keeping time period during which an amplitude of the voltage signal is maintained.

38. A micro pump according to claim 35,

wherein the first time length and the second time length are identical.

39. A micro pump according to claim 38,

wherein the first waveform has a shape of a sine wave.

40. A micro pump according to claim 32,

wherein a cross sectional configuration of the first flow pass is identical to a cross sectional configuration of the second flow pass, and

wherein a length of the first flow pass is different from a length of the second flow pass.

41. A micro pump according to claim 32,

wherein a shape of the first flow pass is different from a shape of the second flow pass.

42. A micro pump according to claim 41,

wherein at least one of the first flow pass and the second flow pass has a tapered shape.

43. A micro pump according to claim 41,

wherein at least one of the first flow pass and the second flow pass has cross sectional configurations which change in a stepwise manner.

44. A micro pump according to claim 41,

wherein at least one of the first flow pass and the second flow pass has an obstruction therein.

45. A micro pump according to claim 32,

wherein the actuator comprises a piezoelectric element.

46. A micro pump according to claim 45, wherein the actuator further comprises:

an oscillating plate to which the piezoelectric element is disposed.

47. A micro pump according to claim 46,

wherein a main surface of the oscillating plate forms a wall of the pressure chamber.

48. A micro pump comprising:

a pressure chamber for accommodating a fluid;

an actuator which is capable of repeatedly increasing and decreasing an internal pressure of the pressure chamber in accordance with a first prescribed manner;

a first flow pass connected with the pressure chamber, wherein the fluid is capable of flowing through the first flow pass to or from the pressure chamber; and

a second flow pass connected with the pressure chamber, wherein the fluid is capable of flowing through the second flow pass to or from the pressure chamber,

wherein, under the first prescribed manner, a flow through the first flow pass shows a laminar flow when the internal pressure is increased and shows a turbulent flow when the internal pressure is decreased, while a flow through the second flow pass shows a laminar flow when the internal pressure is increased and shows a laminar flow when the internal pressure is decreased.

49. A micro pump according to claim 48, further comprising:

a driver, connected with the actuator, being capable of sequentially applying to the actuator voltage signals of a first waveform so that the actuator repeatedly increases and decreases the internal pressure chamber in accordance with the first prescribed manner.

50. A micro pump according to claim 49, wherein the first waveform comprises a rising time period during which an amplitude of the voltage signal is increased and a falling time period during which the amplitude of the voltage signal is decreased.

51. A micro pump according to claim 50, wherein the rising time period and the falling time time period respectively require a first time length and a second time length.

52. A micro pump according to claim 51, wherein the first time length is different from the second time length.

53. A micro pump according to claim 50, wherein the first waveform further comprises, between the rising time period and the falling time period, a keeping time period during which an amplitude of the voltage signal is maintained.

54. A micro pump according to claim 51, wherein the first time length and the second time length are identical.

55. A micro pump according to claim 54, wherein the first waveform has a shape of a sine wave.

56. A micro pump as claimed in claim 48, wherein the actuator is further capable of repeatedly increasing and decreasing the internal pressure of the pressure chamber in accordance with a second prescribed manner, and

wherein, under the second prescribed manner, a flow through the first flow pass shows a turbulent flow when the internal pressure is increased and shows a laminar flow when the internal pressure decreased, while a flow through the second flow pass shows a laminar flow when the internal pressure is increased and shows a laminar flow when the internal pressure is decreased.

57. A micro pump comprising:

a pressure chamber for accommodating a fluid;

an actuator having a driving element operably coupled to the pressure chamber, the actuator adapted to repeatedly increase and decrease an internal pressure of the pressure chamber in accordance with a first prescribed manner;

a first flow pass connected with the pressure chamber, wherein the fluid is capable of flowing through the second flow pass to or from the pressure chamber; and

a second flow pass connected with the pressure chamber, wherein the fluid is capable of flowing through the second flow pass to or from the pressure chamber,

wherein, under the first prescribed manner, a flow through the first flow pass shows a laminar flow when the internal pressure is increased and shows a turbulent flow when the internal pressure is decreased, while a flow through the second flow pass shows a laminar flow when the internal pressure is increased and shows a laminar flow when the internal pressure is decreased.

58. A micro pump according to claim 57, further comprising:

a driver, connected with the actuator, being capable of sequentially applying to the actuator voltage signals of a first waveform so that the actuator repeatedly increases and decreases the internal pressure of the pressure chamber in accordance with the first prescribed manner.

59. A micro pump according to claim 58,

wherein the first waveform comprises a rising time period during which an amplitude of the voltage signal is increased and a falling time period during which the amplitude of the voltage signal is decreased.

60. A micro pump according to claim 59,

wherein the rising time period and the falling time period respectively require a first time length and a second time length.

61. A micro pump according to claim 59,

wherein the first time length is different from the second time length.

62. A micro pump according to claim 59,

wherein the first waveform further comprises, between the rising time period and the falling time period, a keeping time period during which an amplitude of the voltage signal is maintained.

63. A micro pump according to claim 60,

wherein the first time length and the second time length are identical.

64. A micro pump according to claim 60,

wherein the first waveform has a shape of a since wave.

65. A micro pump as claimed in claim 57,

wherein the actuator is further adapted to repeatedly increase and decrease the internal pressure of the pressure chamber in accordance with a second prescribed manner, and

wherein, under the second prescribed manner, a flow through the first flow pass shows a turbulent flow when the internal pressure is increased and shows a laminar flow when the internal pressure is decreased, while a flow through the second flow pass shows a laminar flow when the internal pressure is increased and shows a laminar flow when the internal pressure is decreased.