IE921800A1

IE921800A1 - Flow meter

Info

Publication number: IE921800A1
Application number: IE921800A
Authority: IE
Inventors: Michael A Gunter
Original assignee: Baxter Int
Priority date: 1991-06-07
Filing date: 1992-07-01
Publication date: 1992-12-16
Also published as: JPH06500639A; AU655055B2; NZ243044A; BR9205555A; CA2086506A1; AU2179992A; MX9202716A; WO1992021939A1; EP0542985A1

Abstract

A turbine flow meter (10) with a rotor assembly (12) having an integral thrust and radial bearing (14). The bearing (14) has a substantially cylindrical can shape and is provided with a shaft bore (38) extending only partially therethrough so that the bearing can be mounted on a round nosed shaft (40) pointed in the upstream direction.

Description

TITLE: ••FLOW METER'· BACKGROUND OF THE INVENTION The present invention generally relates to flow meters. More particularly, the invention relates to turbine flow meters and rotor assemblies.

A turbine flow meter is a device that is used to measure the volumetric flow of a liquid. Such a flow meter generally includes an outer body suitably sized for the conduit to which it is attached. Within the outer body is located a rotor which rotates due to fluid flow within the body. The speed of rotation of the rotor theoretically is directly proportional to fluid velocity, or flow rate.

The rotor generally has a plurality of curved or angled blades so that a fluid stream will engage the blades and cause the rotor to rotate. As the rotor spins, the vanes pass through a magnetic field created by a permanent magnet in a magnetic pick-up assembly.

The magnetic pick-up includes a coil in addition to the magnet.

Each time a rotor vane passes the tip of the pickup assembly, an AC voltage pulse is induced in the coil.

Thus, a rotor with six blades will produce six pulses per revolution and these pulses are counted to determine rotational speed and hence, fluid velocity, or flow rate.

A typical small flow meter can revolve at approximately 10,000 rpm at the upper end of the flow range. Such a rotational speed will produce a series of pulses having a frequency of 1000 Hz.

Theoretically the rotor is freely suspended in the fluid stream so that the curved or angled blades are - 2 acted upon by the fluid stream. Since, in theory, the rotor neither receives nor injects any energy into the fluid stream, the rotor rotates neither faster nor slower than the fluid flow.

In practice, however, it is not possible to freely suspend the rotor. Instead, rotors generally are suspended at axial ends thereof by various arrangements or suspensions. Additionally, the rotor suspension must fulfill other functions. The suspension must prevent the rotor from being driven downstream by the dynamic pressure of the flowing fluid. It must also correctly position and orientate the rotor vis-a-vis the fluid stream.

In accomplishing the foregoing, the rotor suspensions must withstand the rigors of the fluid environment. Such rigors can include: temperature extremes; overspeeding; corrosion; abrasion; transients of pressure, temperature, and flow rate; and shock.

Further, turbine flow meters are often subject to high shock and intermittent use, especially when used, for example, in fill lines for pharmaceuticals or foods. As a result, turbine flow meters are subject to failure due to wear and tear resulting from intermittent operation, as well as frictional forces.

Typically three types of rotor suspensions or arrangements for axially supporting a turbine flow meter rotor have been used: (a) the journal bearing system; (b) the ball bearing system; and (c) the pivot bearing system. The journal bearing system operates on sliding friction. The ball bearing utilizes rolling friction.

The pivot bearing system experiences a combination of sliding and rolling friction. - 3 Though these systems offer different advantages, there are also disadvantages with the systems. The bearings in these systems typically produce a drag or retarding force against rotor rotation. The journal bearing although offering a relatively rugged design, suffers from a higher rotational drag than the ball bearing. The pivot bearing offers low starting drag, but, has a top operating speed that is lower than that of the two other bearing types.

SUMMARY OF THE INVENTION The present invention provides an improved turbine flow meter. To this end, the invention provides a rotor suspension assembly including an integral thrust and radial bearing.

In an embodiment, the invention provides a turbine flow meter wherein a rotor is supported on a bearing having a shaft bore extending partially therethrough, which bearing in turn is mounted on a round nosed shaft.

This construction affords the turbine flow meter high shock resistance, low rotor spin friction, longterm consistency of operation, easy repairability, and long wear. Further, this construction preferably is such that non-toxic materials are employed which provide for excellent cleanability and high temperature resistance.

Thus, this construction is particularly useful in the pharmaceutical and food industries.

The relationship of the shaft bore and shaft preferably are such that the point of support or balance of the rotor is positioned upstream of the midpoint of the bearing thereby providing for greater stability than was provided in prior designs.

In another embodiment, the thrust bearing is made of a high performance plastic so that the cooperation - 4 between the shaft and the bearing provides excellent shock resistance, and the pressure of the bearing due to fluid flow provides increased resistance to valve shock, etc. on the downstream side.

In another embodiment, the rotor is provided with bleed holes on the upstream end, which bleed holes provide flushing and cooling to the bearing.

In an embodiment, a turbine flow meter is provided comprising a body with an interior channel adapted to be coupled to a conduit through which a fluid is caused to flow. A magnetic pick up is operatively disposed in the body. A rotor assembly is disposed in the body, the assembly including an integral thrust and radial bearing on which said rotor is mounted.

In an embodiment, a flow meter rotor assembly is provided that comprises a rotor supported on an integral thrust and radial bearing.

In an embodiment, a turbine flow meter rotor bearing is provided having both thrust and radial bearing surfaces.

In another embodiment, the turbine flow meter comprises a body having a channel adapted to be coupled to a conduit having a flow of fluid therein. A support member is disposed in the body. The meter includes a round nosed shaft extending upstream from the support member and a substantially cylindrical can shaped bearing mounted on the shaft, the bearing having an end wall at its upstream end and a circumferential rabbet. A rotor is mounted on the bearing and seated within the rabbet.

In an embodiment, a turbine flow meter is provided comprising a body having a channel adapted to be coupled in fluid communication with a conduit that provides a flow of fluid therethrough. A support member is disposed - 5 within the body. The meter includes a round nosed shaft extending upstream from said support member and a substantially cylindrical can shaped bearing mounted on said shaft, said bearing having an end wall at its upstream end and a radial flange extending from about a circumference of said bearing. A rotor is mounted on the bearing and received in abutting relationship against the flange.

Additional features and advantages of the present 10 invention are described in, and will be apparent from, the detailed description of the presently preferred embodiments and from the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 illustrates a cross-sectional view of a 15 first turbine flow meter with a rotor having an integral thrust and radial bearing.

Figure 2 illustrates an exploded view of the assembly of the rotor of Figure 1.

Figure 3 illustrates a cross-sectional view of the 20 rotor of the flow meter of Figure 1.

Figure 4 illustrates a cross-sectional view of a second turbine flow meter rotor with an integral thrust and radial bearing.

Figure 5 illustrates an exploded view of the 25 assembly of the rotor of Figure 4.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS The present invention provides an improved rotor bearing system for a turbine type fluid flow meter. The invention provides an integration of a thrust bearing and a radial bearing in a turbine flow meter rotor. The resulting structure provides a turbine flow meter rotor - 6 10 that is easy to clean and service and that suffers minimal wear and tear, if any.

Referring to the Figures, and specifically Figures 1-3, there is illustrated a first turbine flow meter 10 having a rotor 12 with an integral thrust and radial bearing 14. The flow meter 10 includes a flow meter body 16, preferably made of stainless steel, within which is accommodated a magnetic pick-up 18 in addition to the rotor 12. The magnetic pick-up 18 is operatively disposed in a suitable well 20 of the flow meter body 16.

The rotor 12 is disposed within an axial conduit 22 within the flow meter body 16 such that the magnetic pick-up 18 is operative to detect rotation of the rotor 12. This is accomplished by detecting the movement of angular vanes 24 disposed on the rotor 12. As fluid flows from an upstream end 26 of the meter 10 to a downstream end 28 of the meter 10, the fluid engages the angled vanes 24 causing rotation of the rotor 12.

The rotor 12 itself preferably comprises both the bearing 14 and a substantially annularly shaped rotor body 32 from which the vanes 24 protrude. The vanes 24 are disposed about an outer circumference of the annular rotor body 32 which is received on the bearing 14 within a circumferential rabbet or recess 44 formed about the downstream end of the bearing 14. The vanes 24 preferably are integrally formed with the body 32. Preferably, the vanes 24 and body 32 are made of stainless steel.

The bearing 14 has a substantially cylindrical can shape (tophat shape). The bearing 14 includes a generally annular portion 34, an end wall 36 at its upstream end, and a shaft bore 38 that extends partially therethrough to form the annular portion 34. The bearing - 7 14 is received on an axially positioned round nosed shaft 40 supported on a support member 42 such that the bearing 14 is sufficiently spaced apart from the support member 42. In this way, the rotor 12 does not rub against the support member 42 as the rotor 12 rotates.

The interior of the bore 38 provides a radial bearing surface within the annular portion 34 and a thrust bearing surface on the interior side of the end wall 36. The round nose shape of the shaft 40 provides a smooth surface against which there is minimal contact by the end wall 36. Thus, wear and tear as well as friction are reduced. Further the thrust bearing surface is maintained upstream of the radial bearing surface, this providing for greater stability in operation.

In contrast to prior rotor suspensions, in the present construction, the rotor 14 is supported only from one support member, namely the support member 42. This contrasts sharply from prior rotor structures wherein it is necessary to support the rotor from two such support members.

The support member 42 also includes a plurality of linear vanes 60 that serve to straighten the flow of fluid through the body 16. Preferably, the support member 42 includes three linear vanes 60. The linear vanes 60 serve to direct the fluid flow through the vanes of the rotor 12.

Positioned upstream of the rotor 12 is a flow straightening member 62. The flow straightening member 62 includes linear vanes 64 similar in construction to the linear vanes 60 of support member 42. But, the flow straightening member 62 does not support the rotor 14. Similar to support member 42, however, the flow - 8 straightening member 62 also serves to direct the flow of fluid through the rotor vanes 24.

As illustrated, bleed holes or bores 50 and 52 are provided adjacent to or at the upstream end of the bearing 14. These bleed holes 50 and 52 provide a flow of fluid to the interior bearing surfaces. Specifically, fluid flow is provided to the shaft 40 and the interior wall of the shaft bore 38. This flow of fluid serves to cool, flush, and lubricate the bearing surfaces. Due to the flow of fluid, wear and tear on the bearing surface is decreased and the longevity thereof is increased.

The bearing 14 preferably is made of a high performance plastic material, e.g., ZYTREX 455 ™ having a finish of 30 μ.

By way of example and not limitation, an embodiment that has been found to function satisfactorily will be provided. Tolerances except where noted are as follows: .xx + 0.01; and .xxx + 0.005. The bearing 14 preferably is formed so that it has an overall length of about .549 inches and an overall diameter of about .360 inches. The rabbet 44 preferably has an axial length of about .344 inches and a radial depth of approximately .055 inches.

The upstream edge of the bearing 14 is provided with an approximately 40° chamfer 54 with respect to the axis there such that about .030 axial inches and .036 radial inches of material are removed from the upstream edge. Bleed holes 50 are bored so that they have a diameter of approximately .024 inches and such that they extend perpendicularly from the chamfer surface, i.e., it is also positioned at approximately 40° with respect to the axis of the bearing. The bleed holes 50 are positioned at 180° apart from each other. - 9 Bleed holes 52 preferably are bored to have a diameter of about .030 inches and spaced from the upstream end by approximately .012 inches. These holes 52 are then oriented perpendicularly with respect to the axis of the bearing 30. The bleed holes 52 are also spaced 180° apart from each other and 90° from the bleed holes 50.

The shaft bore 38, preferably is formed to be about .423 inches long and to have a diameter that initially is roughed out to approximately .156 inches before assembly and then reamed to approximately .158 to about .159 inches after press fitting.

The rotor body 32, thus, preferably has an inner diameter of about .254 inches and an outer diameter of about .360 inches to fit within the rabbet 44. The axial length of the body 32 is about .344 inches.

Referring now to Figures 4 and 5, there is disclosed another embodiment of the turbine flow meter rotor assembly 100. The assembly 100 includes a rotor 102 with an integral thrust and radial bearing 104. In this flow meter assembly 100, the bearing 104 includes a substantially cylindrical can shaped body. The body comprising a central annular portion 106, a closed upstream end wall 108, and a radial downstream flange 110. The bearing 104 is received on the round nosed shaft 112 in a manner similar to that of the bearing of the flow meter illustrated in Figures 1-3.

The rotor 102 preferably is similar to the rotor 14 illustrated in Figures 1-3. To this end, vanes 132 of the rotor 102 are secured to or formed with an annular body 134 that is received about the outer circumference of the annular portion 106 of the bearing 104 such that the body 134 abuts against the flange 110. It can be - 10 appreciated that in addition to an adhesive or press fitting of the annular body 134 to the bearing 104, the force exerted by the fluid flow will serve to secure the annular body 134 to the bearing 104.

By way of example, an embodiment that has been found to function satisfactorily is as follows. Preferably, the bearing 104 has an overall length of about .549 inches and an outer diameter at the central annular portion 106 of about .254 inches. The flange 110 preferably has an outer diameter of about .360 inches.

The bearing 104 also is provided with an approximately 40° chamfer at its upstream edge.

Bleed holes 120 and 122 are provided such that the holes 120 are drilled perpendicularly with respect to an axis of rotation of the bearing 14. Bleed holes 122 are drilled parallel to the axis of the bearing 104. The bleed holes 120 and 122 preferably are approximately .03 inches in diameter. The centers of the bleed holes 122 preferably are positioned along a diagonal and about .0625 inches from the outer circumference of the annular portion 106 of the bearing 104.

As with the bleed holes 50 and 52, the bleed holes 120 are spaced 180° apart while the holes 122 are spaced 180° apart with respect to each other and 90° apart from the holes 120.

The above-described flow meters are especially suitable for use in apparatus for filling medical fluid containers such as containers for housing intravenous fluid. Due to the on/off cycling required in operations to fill such containers, flow meters in such operations have a high rate of failure. The above-described rotor support assemblies serve to reduce or eliminate failures due to wear and tear of bearings. -lilt should be understood that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the present invention and without diminishing its attendant advantages. It is therefore intended that such changes and modifications be covered by the appended claims.

Claims

1. - 12 I CLAIM;

1. A turbine flow meter comprising: a body having an interior channel adapted to be coupled to a conduit through which a fluid is caused to 5 flow; a magnetic pick up operatively disposed in the body; and a rotor assembly disposed in the body, the assembly including an integral thrust and radial bearing on which 10 the rotor is mounted.

2. The turbine flow meter of Claim 1 including a round nosed shaft on which is mounted the bearing, the bearing having a shaft bore extending only partially therethrough. 15

3. The turbine flow meter of Claim 2 wherein the bearing includes bleed holes in communication with the shaft bore through which a portion of the fluid flows flushing and cooling the shaft and the bore in the bearing. 20

4. The turbine flow meter of Claim 1 wherein the bearing is constructed from plastic.

5. The turbine flow meter of Claim 1 including a round nosed shaft on which is mounted the bearing, the bearing having a substantially cylindrical can shape 25 with a shaft bore extending partially therethrough.

6. The turbine flow meter of Claim 1 wherein the rotor includes an annular rotor body and the bearing includes a circumferential rabbet within which the rotor body is seated. 30

7. The turbine flow meter of Claim 5 wherein the rotor includes an annular rotor body and the bearing includes a radial flange at one end against which the rotor is seated. - 13

8. A flow meter rotor assembly comprising a rotor supported on an integral thrust and radial bearing.

9. The flow meter rotor assembly of Claim 8 including a round nosed shaft on which is mounted the 5 bearing, the bearing having a shaft bore extending only partially therethrough.

10. The flow meter rotor assembly of Claim 9 wherein the bearing includes bleed holes in communication with the shaft bore through which a portion of the fluid 10 flows flushing and cooling the shaft and the bore in the bearing.

11. The flow meter rotor assembly of Claim 8 wherein the bearing is constructed from plastic.

12. The flow meter rotor assembly of Claim 8 15 including a round nosed shaft on which is mounted the bearing, the bearing having a substantially cylindrical can shape with a shaft bore extending partially therethrough.

13. The flow meter rotor assembly of Claim 12 20 wherein the rotor includes an annular rotor body and the bearing includes a circumferential rabbet within which the rotor body is seated.

14. The flow meter rotor assembly of Claim 12 wherein the rotor includes an annular rotor body and the 25 bearing includes a radial flange at one end against which the rotor is seated.

15. A turbine flow meter rotor bearing comprising both thrust and radial bearing surfaces.

16. The turbine flow meter rotor bearing of Claim 30 15 including a substantially cylindrical can shape and having a shaft bore extending only partially therethrough. - 14

17. The turbine flow meter rotor bearing of Claim 16 wherein the bearing includes bleed holes in communication with the shaft bore through which a portion of the fluid flows flushing and cooling the bore in the 5 bearing.

18. The turbine flow meter rotor bearing of Claim 15 wherein the bearing is constructed from plastic.

19. The turbine flow meter rotor bearing of Claim 16 wherein the bearing includes a circumferential rabbet 10 within which a rotor body can be seated.

20. The turbine flow meter rotor bearing of Claim 16 wherein the bearing includes a radial flange at one end against which a rotor can be seated.

21. A turbine flow meter comprising: 15 a body having a channel adapted to be coupled to a conduit having a flow of fluid therein; a support member disposed in the body; a round nosed shaft extending upstream from the support member; 20 a substantially cylindrical can shaped bearing mounted on the shaft, the bearing having an end wall at its upstream end and a circumferential rabbet; and a rotor mounted on the bearing and seated within the rabbet. 25

22. A turbine flow meter comprising: a body having a channel adapted to be coupled in fluid communication with a conduit with a flow of fluid therein; a support member disposed within the body; 30 a round nosed shaft extending upstream from the support member; a substantially cylindrical can shaped bearing mounted on the shaft, the bearing having an end wall at its upstream end and a radial flange extending from about a circumference of the bearing; and a rotor mounted on the bearing and received in abutting relationship against the flange.

23. A turbine flow meter according to any preceding claim substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

24. A flow meter rotor assembly according to any preceding claim substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

25. A turbine flow meter rotor bearing according to any preceding claim substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.