Integral pump and flow meter device

• US 5,704,767 A
• Filed: 03/03/1997
• Issued: 01/06/1998
• Est. Priority Date: 01/11/1995
• Status: Expired due to Term

• Current Assignee: Micropump, Inc. (RELX PLC)
• Original Assignee: Micropump, Inc. (RELX PLC)
• Inventors: Johnson, Paul A.
• Primary Examiner(s): Thorpe, Timothy
• Assistant Examiner(s): THAI, XUAN MARIAN
• Application Number:
  US08/808,479
• Time in Patent Office: 309 Days
• Field of Search: 418/2, 418/40, 418/206.1, 418/206.5, 417/212, 73/229
• US Class Current: 417/43
• CPC Class Codes: F04C 11/00 Combinations of two or more machines or pumps, each being of rotary-piston or oscillating-piston type combinations of such pumps specially adapted for elastic fluids F04C23/00; Pumping installations F04C13/00 takes precedence; specially adapted for elastic fluids F04C23/00; fluid gearing F16H
• CPC Class Codes: F04C 13/00 Adaptations of machines or pumps for special use, e.g. for extremely high pressures of pumps specially adapted for elastic fluids F04C25/00
• CPC Class Codes: F04C 14/08 characterised by varying the rotational speed
• CPC Class Codes: F04C 2220/24 for metering throughflow
• CPC Class Codes: G01F 3/10 Geared or lobed impeller meters

Abstract

A pump housing is provided with a conduit extending through the housing between a pump inlet and pump outlet. A pump device is disposed within the housing and in communication with the conduit to pump fluid therethrough. A fluid flow meter also is disposed within the housing and in communication with the conduit to monitor fluid flow rate through the conduit. The fluid flow meter generates signals related to the fluid flow rate which are fed back to a control device operable to control the flow rate through the pump device. The flow meter may include a pair of meshed modified elliptical gears. The modified elliptical gears are based on a true elliptical shape, with bulged portions added between the major and minor axes of the elliptical shape. The modified elliptical gears have involute teeth that are relatively thick adjacent the minor axis and relatively thin adjacent the major axis.

Claims

1. A pump, comprising:

a pump housing defining an inlet and an outlet;

a conduit defined by the housing and extending between the inlet and the outlet to define a fluid flow path through the housing;

a pump device positioned within the housing and in communication with the conduit to propel fluid through the conduit; and

a fluid flow meter positioned within the housing and in communication with the conduit to measure the flow rate of fluid pumped through the conduit by the pump device, the fluid flow meter comprising first and second elliptical gears on respective rotational meter axes and being intermeshed with each other for counterrotation with respect to each other as urged by fluid propelled through the conduit by the pump device, the first elliptical gear having a major axis that passes through a perpendicular orientation relative to a major axis of the second elliptical gear at every 90°

of rotation of said elliptical gears, the elliptical gears being modified from a true elliptical profile to substantially eliminate gaps between the meshed elliptical gears as the elliptical gears counterrotate.

2. A pump according to claim 1, wherein the inlet and outlet are disposed on opposite sides of the housing.

3. A pump according to claim 1, wherein the pump device has at least one pump member rotatable about a pump member axis, the pump member axis and the rotational meter axes being substantially parallel to each other.

4. A pump according to claim 3, wherein the pump device has two pump members respectively rotatable about first and second pump member axes, the first and the second pump member axes and the first and the second rotational meter axes being disposed substantially in a common plane.

5. A pump according to claim 3, wherein the conduit extends perpendicular to the pump member axis through the pump device and extends perpendicular to the rotational meter axes through the fluid flow meter.

6. A pump according to claim 5, wherein the inlet and outlet are disposed on opposite sides of the housing, the flow across the pump member is from the inlet side of the housing toward the outlet side, and the flow across the fluid flow meter is from the outlet side of the housing toward the inlet side.

7. A pump according to claim 1, wherein the pump device comprises at least one rotating pump member positioned across the conduit, drivingly connected to a rotatable drive shaft held in the housing by a mount.

8. A pump according to claim 7, wherein a subconduit extends from the conduit to the mount, the subconduit being adapted to route fluid to the mount.

9. A pump according to claim 1, further comprising:

a pump motor operably connected to the pump device to drive the pump device; and

a control device operably connected to the flow meter and to the pump motor, the control device receiving fluid flow rate data from the flow meter, and the control device controlling the pump motor speed based on the fluid flow rate data.

10. A pump according to claim 1, wherein a magnet is connected to the first elliptical gear for rotation therewith, and a magnetic field sensor is positioned adjacent the magnet, the magnetic field sensor operable to sense variation in the magnetic field as the first elliptical gear rotates to sense rotation of the first elliptical gear.

11. A pump according to claim 1, wherein the pump housing is comprised of a plurality of stacked elements, each element being selectively formed such that the stacked elements together define a pump cavity, a flow meter cavity, and the conduit within the housing.

12. A pump according to claim 1, wherein the first and second elliptical gears are modified from a true elliptical profile by bulges in respective pitch shapes of the first and second elliptical gears, the bulges being located between major and minor axes of the respective pitch shapes.

13. A pump according to claim 12, wherein the first and second elliptical gears have teeth, the teeth near the major axis of the respective pitch shapes of the first and second elliptical gears being relatively smaller in the circumferential direction, and the teeth near the minor axis of the respective pitch shapes of the first and second elliptical gears being relatively larger in the circumferential direction.

14. A pump comprising:

a pump device having a variable operation rate and a flow meter operable to produce varying signals related to the flow rate produced by the pump device, the pump device and flow meter being housed adjacent each other within a pump housing, the flow meter comprising first and second elliptical gears intermeshed with each other for counterrotation with respect to each other as urged by fluid propelled past the first and second elliptical gears through the housing by the pump device, the first elliptical gear having a major axis that passes through a perpendicular orientation relative to a major axis of the second elliptical gear at every 90°

of rotation of said elliptical gears, the elliptical gears being modified from a true elliptical profile to substantially eliminate any gap between the meshed elliptical gears as the elliptical gears counterrotate;

an electric circuit interconnecting the flow meter and pump device; and

a control device connected to the electric circuit, with signals from the flow meter indicating pump flow rate being fed from the control device to the pump device to control the pump operation rate.

15. A pump according to claim 14, wherein the control device is operable to compare a selected flow rate with the pump flow rate indicated by the signals from the flow meter, the control device being operable to signal the pump device to increase pump operation rate when the selected flow rate is greater than the sensed pump flow rate, and operable to signal the pump device to decrease the operation rate when the selected flow rate is less than the sensed pump flow rate.

16. A pump according to claim 14, wherein the control device is mounted within the pump housing.

17. A pump according to claim 14, wherein the first and second elliptical gears are modified from a true elliptical profile by bulges in respective pitch shapes of the first and second elliptical gears, the bulges being located between major and minor axes of the respective pitch shapes.

18. A pump according to claim 17, wherein the first and second elliptical gears have teeth, the teeth near the major axis of the respective pitch shapes of the first and second elliptical gears being relatively smaller in the circumferential direction, and the teeth near the minor axis of the respective pitch shapes of the first and second elliptical gears being relatively larger in the circumferential direction.

19. A pump according to claim 17, wherein the teeth near the major axes of the pitch shapes of the intermeshed elliptical gears are relatively thinner and the teeth near the minor axes of the pitch shapes of the intermeshed elliptical gears are relatively thicker.

22. A pump according to claim 17, wherein the intermeshed elliptical gears each have pitch shapes having major and minor axes, the elliptical gears being modified from a true elliptical shape by the addition to the pitch shapes of bulges between the major and minor axes.

20. A pump comprising:

a housing with a conduit extending therethrough, the conduit having first and second opposing portions;

a pump device disposed within the housing adjacent the first portion; and

a flow meter disposed within the housing adjacent the second portion, the flow meter comprising a pair of intermeshed elliptical gears modified from a true elliptical shape so as to eliminate a gap tending to arise when major axes of the intermeshed elliptical gears are parallel, wherein the pump device is mounted on a drive shaft having an end rotatably mounted at a mount positioned between the pump device and the flow meter.

21. A pump according to claim 20, wherein a subconduit extends from the conduit at a position between the first and second conduit portions, the subconduit intersecting the drive shaft mount to direct fluid to the mount.

23. A pump, comprising:

(a) a pump housing defining an inlet, an outlet, and a conduit extending and defining a fluid flow path through the pump housing connecting the inlet with the outlet;

(b) a pump device enclosed within the housing and in communication with the conduit downstream of the inlet to propel liquid through the conduit, the pump device comprising plural pump members rotatable about respective pump member axes; and

(c) a fluid flow meter positioned within the housing and in communication with the conduit downstream of the pump device but upstream of the outlet to measure the flow rate of fluid propelled through the conduit by the pump device, the fluid flow meter comprising plural meter members respectively rotatable about first and second meter member axes as urged by the fluid propelled by the pump device, the pump member axes and the meter member axes being substantially parallel to each other and disposed substantially in a common plane.

24. The pump of claim 23, wherein the conduit extends perpendicularly to the pump member axes through the pump device, and perpendicularly to the meter member axes through the fluid flow meter.

25. The pump of claim 24, wherein the inlet and outlet are disposed on opposite sides of the housing, the flow across the pump member being from the inlet side of the housing toward the outlet side, and the flow across the fluid flow meter being from the outlet side of the housing toward the inlet side.

26. The pump of claim 23, wherein the pump housing comprises, in order, plural stacked elements, wherein a first stacked element defines the inlet and outlet, a second stacked element defines a pump cavity for the pump device, a third stacked element defines a conduit portion from the pump device to the fluid flow meter and from the fluid flow meter to the outlet, a fourth stacked element defines a fluid flow meter cavity for the fluid flow meter.

27. The pump of claim 23, further comprising a sensor for sensing rotation of the metering gears.

28. A pump, comprising:

(a) a housing defining a conduit extending therethrough, the conduit having first and second opposing portions;

(b) a pump device disposed within the housing adjacent the first portion, the pump device comprising plural pump members rotatable about respective pump member axes; and

(c) a flow meter disposed within the housing adjacent the second portion, the pump device further comprising a drive shaft having an end rotatably mounted at a mount positioned between the pump device and the flow meter, and the flow meter comprising plural meter members respectively rotatable about first and second meter member axes that are parallel to each other and to the pump member axes and disposed in a common plane.

29. The pump device of claim 28, wherein a subconduit extends from the conduit at a position between the first and second conduit portions, the subconduit intersecting the drive shaft mount to direct fluid to the mount.

30. A pump and flow sensor combination, comprising:

a pump housing having an inlet and an outlet and an inside surface;

a pump drive shaft connectable to a motor outside said pump housing and penetrating said pump housing;

a first gear and a second gear within said pump housing and enmeshed for opposite rotation, said first gear connected to said pump drive shaft for driven rotation therewith, said first and second gears being closely journaled partially by said inside surface of said pump housing and arranged to receive fluid from said inlet on a demeshing side of said first and second gears;

third and fourth gears arranged in said pump housing downstream of said first and second gears, said third and fourth gears enmeshed and closely journaled partially by said inside surface of said pump housing, a demeshing side of said third and fourth gears receiving flow from an enmeshing side of said first and second gears, and an enmeshing side of said third and fourth gears open to said outlet of said pump housing; and

said third and fourth gears driven by fluid pumped by said first and second gears; and

a sensor means for sensing a rotational speed of said third gear for determining the flow rate of liquid pumped by said first and second gears.

31. The pump and flow sensor combination according to claim 30, wherein said sensor means comprises a noncontact sensor.

32. The pump and flow sensor combination according to claim 31, wherein said noncontact sensor comprises a magnet mounted on said third gear and a magnet sensor mounted to said pump housing.