US3037457A - Pumps - Google Patents

Description

June 5, 1962 B. STERNLICHT 3,037,457

PUMPS Filed Aug. 26, 1959 F16 l 2 Sheets-Sheet 1 INVENTORZ BENO STERNLICHT,

HIS ATTORNEY.

Wait/e June 5, 1962 B. STERNLICHT 3,037,457

PUMPS Filed Aug. 26, 1959 2 Sheets-Sheet 2 INVENTORZ BENO STERNLICHT,

HIS ATTORNEY.

United States Patent 3,037,457 PUMPS Beno Sternlicht, Schenectady, N.Y., assignor to General Electric Company, a corporation of New York Filed Aug. 26, 1959, Ser. No. 836,162 4 Claims. (Cl. 10384) The present application relates to pumps, and more particularly, to high pressure rotary pumps.

With the present advance in technology, new applications are creating a trend toward handling fluids at higher pressures and higher temperatures. Such applications exist in the control field wherein high pressures are transmitted by means of nonconventional fluids such as molten metals, for example, liquid sodium. Other applications of high pressure and high temperature equipment exist in extruding processes wherein molten materials such as molten glass are extruded into various shapes.

To generate pressures of a magnitude as great as 4,000 pounds per square inch and greater, devices such as screw pumps have been devised. In some instances multi-stage pumps have been utilized to achieve these high pressures. Many problems are encountered in the operation of such pumps which very often result in failure of the pump. The reason for such failure is that usually the rotor or other component is not capable of being adequately cooled and also because of the inherent limitations of the material of which the pump is constructed. Portions of the pump during operation become heated to a plastic state. In this condition the application of high pressure or the existence of rubbing contact culminates in failure of the pump.

The chief object of the present invention is to provide an improved single stage high pressure pump.

Another object is to provide a pump having no contacting parts in the fluid handling portions of the pump.

Another object is to provide a pump having a rotor with a cylindrical working surface which may be readily cooled to permit the handling of high temperature materials.

A still further object is to provide an improved pump capable of handling molten metals.

These and other objects of the invention will be more readily apparent from the following description.

One of the features of the present invention is a pump having a rotor with an outer cylindrical surface and a stator substantially enveloping said rotor. The stator is provided with a plurality of surfaces which converge toward the cylindrical surface of the rotor. Means are provided for supplying the fluid to be pumped into the area between the stator and the rotor. Rotation of the rotor generates high pressures in the converging areas between the rotor and the stator. Means are provided to discharge the high pressure fluid from the converging area of the pump. The term converging as used herein designates a decrease in the space between the surface of the rotor and the surface of the stator in the direction of rotation of the rotor.

The present invention will be more clearly understood from the detailed description of preferred embodiments described in the accompanying drawings, in which FIGURE 1 is a section-a1 view of a pump embodying the present invention,

FIGURE 2 is a sectional view of the pump shown in FIGURE 1 taken along the line 22,

FIGURE 3 is a sectional view of another embodiment of the pump shown in FIGURE 2,

FIGURE 4 is an exploded perspective view of the bearing portion of the pump shown in FIGURE '1,

FIGURE 5 is a diagrammatic view of the annular surfaces of the bearing shown in FIGURE 4 with their relationship to the rotor, and

3,037,457 Patented June 5, 1962 FIGURE 6 is a sectional view of one of the annular surfaces shown in FIGURE 4 modified to perform a pumping function.

Referring to FIGURE 1 there is shown a sectional view of the present invention comprising pump 2 having located adjacent thereto a stabilized bearing 3, a shaft 4 extends through the bearing and the pump portion. The pump 2 is provided with line 5 for supplying fluid and discharge line 6 for passing fluid from the pump. It will be appreciated that the eccentricity and clearances shown are exaggerated for the sake of clear illustration.

In order to maintain leakage from the pump at a minimum, suitable deflector plates 7 and 8 may be mounted on the shaft and arranged adjacent the pump. The hearing 3 comprises three bearing portions 10, 11 and 12 having eccentric surfaces, the orientation of which will be more fully described hereinafter.

The basis of operation of most bearings relies on the creation of a hydrodynamic wedge between the journal and bearing. The ability of the lubricant to provide such a wedge is partly the result of the viscosity and density of the fluid whereby the fluid resists changes in shape and also it is the result of the eccentricity and velocity of a shaft relative to the hearing. The magnitude and orientation of the hydrodynamic wedge of lubricant between the journal and bearing may be determined by use of well known Reynolds equation. Generally the distribution of pressure is such that it occurs in converging areas between the journal and bearing and increases as the clearance decreases. In diffusing areas the construction creates a vacuum condition wherein gas pockets are created and the lubricant film is not continuous.

Referring to FIGURE 2 there is shown a sectional view of the pump 2 shown in FIGURE 1 taken along the line 2-2. In this embodiment of the pump it will be noted that the shaft may have a hollow portion 22 and that the stator portion is provided with two semi-cylindrical portions 15 and 16 which are offset from the center of the shaft 0. By this construction the surface 1-5 has a center 0' and the surface 116 has a center 0''. The surfaces 15 and 16 are connected by step portions 17 and '17. This construction provides two converging areas 18 and 19 and upon rotation of the shaft 4 in the direction to positive pressures are generated in these converging areas. The pressure distribution is shown by the curves 20 and 21 (the distance between the stator surface and curve indicates the magnitude of the pressure). It will be noted that the pressures in the widest portions of the converging areas "18 and 19 are at their lowest values and tend to increase to a maximum at the points of minimum clearance between the shaft and the stator.

The present invention utilizes this uneven generation of hydrodynamic pressures to create a pumping effect. The fluid to be pumped must be supplied to the pump at a pressure greater than the pressure existing at the inlet or line 5 shown in FIGURE 2. The pressure in the converging wedge increases and the fluid at a higher pressure is discharged through the line 6 from the converging area 18. It will be appreciated that if a large amount of fluid is discharged through the line 6 the pressure curve 20 will show a degeneration at the point of discharge. The action of the pump will be similar in the converging area 19 with the pressure curve 21 being generated. Fluid is introduced through line 5' and discharged through line 6.

The pump described has a stator with a plurality of arcuate surfaces and a rotor that is cylindrical in shape. It will be appreciated that in cases where molten materials such as liquid sodium and liquid glass are being handled the temperature of the working portions of the pump are extremely high. In many instances the melting points of the pumped fiuid and the material of the pump structure are not separated by any appreciable margin. By providing the type of construction herein shown, it can be seen that coolants may be passed through the center of the shaft 4 and also if it is desired the pump may be suitably jacketed with coolant. This pump further operates on the basis of no rubbing contact between the components and no vanes are required on the rotor. Such vanes normally provide a cooling problem.

FIGURE 3 discloses a sectional view of another embodiment of the pump shown in FIGURE 2. The shaft 4 rotates in the direction a: and the stator in this particular embodiment is provided with three converging surfaces 39, 31 and 32 which are spaced at 120 intervals about the shaft axis. This construction creates three converging areas 33, 34, and 35. Passing fluid through the lines 5, 5' and S" into the wider portions of the converging areas will cause the creation of high pressure areas as shown by the curves 36, 37 and 38. This high pressure fluid may be discharged through the lines 6, 6' and 6" in a manner similar to that shown in FIGURE 2.

In horizontally supported shaft arrangements, the weight of the shaft causes the shaft to assume an attitude angle at relative to the direction of the gravity force on the shaft. The eccentric orientation of a shaft creates a force which acts in a direction through the center of the stator and rotor in a manner as to restore the shaft to a concentric position. Since the restoring force and the weight of the rotor act at an angle a to each other there is a resultant component of force created which tends to move the rotor axis in an oval path. In the case of a vertically disposed shaft this oval path will circumscribe the axis of the stator. In the case of a horizontal shaft this oval path will be spaced from the axis of the stator.

FIGURE 4 discloses a perspective exploded view of the stabilized bearing shown in FIGURE 1. The bearing 3 comprises three hearing portions 10, 11 and 12. The first bearing portion 16 has an eccentric surface 40, the second bearing portion 11 has an eccentric surface portion 41 and the third bearing portion has an eccentric surface 42.

In FIGURE 5 there is shown a partly diagrammatic sectional view taken normal to the axis of the shaft 4. The shaft 4 has a center axis 0, the surface 40 has a center axis 0', the surface 41 has a center axis 0'', and the surface 42 has an axis 0". It will be noted that the centers 0, O" and O are located at 120 intervals on a circle concentric with the axis 0. By this orientation of surfaces the bearing will have three converging areas with respect to the shaft 4. These converging areas will create hydrodynamic forces which have resultant forces which act to stabilize the shaft axis by counteracting any unbalanced forces acting on the shaft which are tending to make the shaft axis whirl in an oval path.

By referring to FIGURE 3 it can be seen that the construction disclosed has three converging areas equally spaced about the shaft. Each pressure distribution curve 36, 37 and 33 creates a resultant force which will tend to restrain any whirling motion of the axis 0 of the shaft 4.

By maintaining the shaft in its concentric position in the stator the shape of the converging areas will be maintained uniform thereby creating uniform pressure curves. This permits smooth operation of the pump and permits the discharge from each converging area to be passed to a common header. It will be appreciated that if these discharge pressures were unequal reverse flow could occur in at least one of the discharge openings 6, 6 or 6". A further difliculty would be encountered in that each discharge opening would provide fluid at a different pressure and this discharge pressure because of the whirling action of the rotor would have a fluctuating value. To avoid this, in the embodiment in FIGURE 1 the stabilizing bearing construction 3 is provided which is shown in FIGURES 4 and 5. In the embodiment of FIGURE 3 because of the particular orientation of the converging areas, resultant forces are created which are inclined to stabilize the position of the shaft 4.

In a manner similar to that shown in FIGURE 3 wherein the pump construction is inherently stable it is apparent that the construction shown in FIGURES 4 and 5 is also basically stable and can be adapted to incorporate therein a pumping action. Referring to FIGURE 6 there is shown a sectional view through the second bearing portion 11 which has an eccentric surface 41. It can be seen that by the use of an eccentric annular surface 41 that not only is a positive pressure distribution created as shown by the curve 47 but also a negative pressure distribution as shown by the curve 48. If it is desired to utilize the construction in FIGURE 4 as a pump the fluid may be introduced as desired in the area covered by the pressure distribution curve 48. Since this area of the hydrodynamic device is subject to a negative pressure due to the diffusing action of the rotor, there will be a tendency of the fluid to pass between the shaft and rotor by being drawn in by this negative pressure. As the fluid passes into the area enveloped by the curve 47 the pressure increases to a maximum at substantially the point of minimum clearance between the shaft 4 and the surface 41. In this area if it is desired the fluid may be discharged through a line 46. It will be appreciated that similar pressure distribution exists with respect with the first bearing portion 10 and the third bearing portion 12. However, the pressure distribution curves in these latter two cases will be transposed with respect to the pressure distribution shown in FIGURE 6. This last disclosed construction also is one wherein the rotor 4 has its axis substantially stabilized by the resultant forces created by the three high pressure arcas about the rotor. This latter construction also has the added advantage that the supply fluid is not required to over come any of the hydrodynamic forces created by the pump which is the case of the embodiment shown in FIGURES 2 and 3.

It will also be appreciated that the stabilizing action does not only occur with three converging areas but may occur with any number greater than three. It is also possible to vary the angular disposition, the clearance and length of the converging areas created by the action of the stator and rotor. This may be necessary in certain instances where the weight of the shaft is a considerable factor and has a large influence on the eccentricity of the shaft axis from the stator axis.

While there have been described preferred embodiments of the present invention, it will be appreciated that the invention is not limited thereto but that various modificaions may be made Without departing from the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent of United States is:

1. In a pump, the combination of a rotor having an outer cylindrical surface, a stator enveloping said rotor and defining a continuous annular area therebetween, the inner periphery of said stator being defined by a plurality of contiguous arcuate surfaces converging toward the cylindrical surface of the rotor, the axis of each arcuate surface being eccentric of the rotor axis, said converging surfaces being equally spaced about the axis of the stator and defining a step at each juncture between adjacent converging surfaces, means for supplying fluid between the stator and the rotor, rotation of the rotor causing the generation of high pressures in the converging areas between the rotor and the stator, means for discharging the fluid from the high pressure areas generated between the stator and the rotor, said means for supplying the fluid between the stator and the rotor being located in an area at a lower pressure than the area at which the fluid is discharged.

2. In a pump, the combination of a rotor having an outer cylindrical surface, a stator enveloping said rotor and defining a continuous annular area therebetween, the inner periphery of said stator being defined by at least three contiguous arcuate surfaces converging towards the cylindrical surface of the rotor, the axis of each arcuate surface being eccentric of the rotor axis, said converging surfaces being equally spaced about the axis of the stator and defining a step at each juncture between adjacent converging surfaces, means for supplying fluid between the stator and the rotor, rotation of the rotor causing the generation of high pressures in the converging areas between the rotor and the stator, the resultant forces of each of the high pressure areas acting on major portions of the annular surface of the rotor to stabilize the rotor in said stator to substantially limit the movement of the rotor axis during rotation thereof, and means for discharging fluid from at least one of the high pressure areas generated between the stator and the rotor.

3. The pump according to claim 2 in which a portion of all the converging surfaces lie in a common plane normal to the .axis of the rotor.

4. In a pump, the combination of a rotor having an outer annular surface, a stator enveloping said rotor and defining a continuous annular area therebetween, the

6 inner periphery of said stator being defined by three contiguous .arcuate surfaces converging toward the cylindrical surface of the rotor, said converging surfaces being equally spaced about the axis of the stator and defining a step at each juncture between adjacent converging surfaces, means for supplying fluid between the stator and the rotor at a pressure greater than that pressure generated by the rotation of the rotor at that point the fluid is supplied, and means for discharging the fluid from the space between the stator and the rotor at a pressure greater than the supply pressure.

References Cited in the file of this patent UNITED STATES PATENTS 1,975,965 Meyer Oct. 9, 1934 2,679,438 Love May 25, 1954 2,851,879 Weatherbee Sept. 16, 1958 FOREIGN PATENTS 720,485 Germany Apr. 9, 1942

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