US2713968A

US2713968A - Hydroturbine pump

Info

Publication number: US2713968A
Application number: US211166A
Authority: US
Inventors: Harold E Adams
Original assignee: Nash Engineering Co
Current assignee: Nash Engineering Co
Priority date: 1951-02-15
Filing date: 1951-02-15
Publication date: 1955-07-26
Anticipated expiration: 1972-07-26

Description

July 26, 1955 H. E. ADAMS HYDROTURBINE PUMP 6 Shets-Sheet 1 Harold 5. Adam"):

Filed Feb. 15 1951 lll ATTOR/f July 26, 1955 2,713,968

H.E.ADAMS HYDROTURBINE PUMP Filed Feb. 15, 1951 6 Sheets-Sheet 2 INVENTOR. Harold 5. Adams ATTORNEYS July 26, 1955 H. E. ADAMS HYDROTURBINE PUMP 6 Sheets-Sheet 3 Filed Feb. 15 1951 .m A a P L T I T {Na M Q M K k \N\ Q9 S S t INVENTOR. hmo/d 5 Adams %0W%.wvq ATTORWE July 26, 1955 H. E. ADAMS HYDROTURBINE PUMP 6 Sheets-Sheet 4 Filed Feb. 15 1951 NVE INVENTOR. Haro/d E. Adam %w M ATTOR/Yff? July 26, 1955 H. E. ADAMS HYDROTURBINE PUMP 6 Sheets-Sheet 5 Filed Feb. 15, 1951 INVENTOR. Ham/d E. Adams AT TORNEYS July 26, 1955 H. E. ADAMS I 2,713,968

HYDROTURBINE PUMP v Filed Feb. 15, 1951 6 Sheets-Sheet 6 IN VEN TOR. Harold 5 Adams Y' ite HYDROTURBINE PUMP Appiication February 15, 1951, Serial No. 211,166 24 Clairns. (C1. 23tl-79) This invention relates to gas pumps of the hydroturbine type. In a pump of this type a rotating ring of liquid is made to serve as the displacement medium. The well known Nash type compressor or vacuum pump is a good illustration of the type of structure to which the invention is applicable.

More specifically, the invention relates to improvements in pump structures of the kind disclosed in Adams Patents #1,847,548 and #1,847,586 of March 1, 1932, and #2,195,375 of March 26, 1940, wherein a rotor of uniform external diameter operates within an eccentric casing and cooperates with tapered conical port members which extend centrally into the rotor from opposite ends thereof.

Pumps of this nature have been found very satisfactory in the pumping of air and gas, also in the pumping of a mixture of gas, air or vapor with a small inclusion of liquid. The improvements disclosed in the above identified patents have extended the useful compression ratio as well as the absolute pressure range of this type of pump beyond that which was obtainable with the earlier designs of liquid ring pumps.

An important object of the present invention is to increase further the efiiciency of these pumps, and to enable them to operate over still greater compression ratios and over a still greater range of absolute pressures.

A further object is to enable a pump of given rotor diameter to be made of greater capacity than has been previously attainable.

Another object is to enable these pumps to operate with reduced cavitation and reduced noise.

It is yet another object to extend the operating limits of these pumps to lower absolute pressures more nearly approaching the vapor pressure of the liquid ring than has previously been possible.

A still further object is to provide a Wider range of operating rotational speeds.

Other objects and advantages will hereinafter appear.

In the drawing forming part of this specification:

Figures 1 to 5 are fragmentary, diagrammatic, sectional views illustrating a series of events occurring in one pumping cycle (half a revolution) of a conventional pump;

Figures 6 to 10 area similar series of views illustrating the corresponding events occurring in one pumping cycle of a pump embodying the improvements of the present invention, the sections being taken, respectively, upon section lines 6-6 to 10-10 of Figure 12, looking in the direction of the arrows;

Figure 11 is a longitudinal, vertical sectional view of a hydroturbine pump embodying one form of the present invention;

Figure 12 is a sectional view taken upon the line 12-12 of Figure 13 looking in the direction of the arrows, showing the construction of the casing or body and cone of the pump of Figure 11, and indicating in broken lines the outline of the shaft, the path of the rotor periphery, and the inner rotor boundary;

atet

Figure 13 is a fragmentary sectional view taken upon the line 13-13 of Figure 12 looking in the direction of the arrows, but with the cone and rotor of Figure 12 omitted;

Figure 14 is a fragmentary sectional view taken upon the line 14-14 of Figure 13 looking in the direction of the arrows;

Figure 15 is a view generally similar to Figure 12, but illustrating the casing employed in another form of the invention, the section being taken upon the line 15-15 of Figure 16 looking in the direction of the arrows;

Figure 16 is a sectional view taken upon the line 16-16 of Figure 15 looking in the direction of the arrows;

Figure 17 is a view similar to Figures 12 and 15, showing the casing employed in a third embodiment of the invention, the section being taken upon the line 17-17 of Figure 18 looking in the direction of the arrows;

Figure 18 is a sectional view taker1.upon the line 18-18 of Figure 17 looking in the direction of the arrows;

Figure 19 is a view similar to Figures 12, 15 and 17, but showing the casing employed in still another embodiment of the invention;

Figure 20 is a longitudinal sectional view taken upon the line 20-20 of Figure 19, looking in the direction of the arrows; and

Figure 21 is a fragmentary sectional view taken upon the line 21-21 of Figure 20, looking in the direction of the arrows.

In the operation of compressors or vacuum pumps of the hydroturbine type, the rotor of the pump revolves a liquid ring within an eccentric casing. Because of the centrifugal action induced by the rotor and the eccentric shape of the casing, a portion of the liquid is caused to flow outward from, and then to refill, the pockets or displacement buckets of the rotor, and thus to effect in alternation the intake and discharge strokes of the pump. Gas is drawn into the inner voids formed in the inner ends of these buckets as the ring approaches the major axis of the casing, and is forced inward as the ring approaches the minor axis or" the casing to compress and discharge the trapped gas. This complete action may take place several times during one rotation of the rotor, depending upon the number of eccentric lobes built into the casing.

The principal problems toward the solution of which the present invention is directed arise from the fact that the ported intake and discharge member disposed within the rotor is conical in shape. This conical shape has many advantages, particularly because of the fine operating clearance which can be secured and maintained between the cone and the rotor by relative axial adjustment of the cone and the rotor. The conical shape of the ported member, however, causes parasitic currents to be developed in the liquid ring, induces an unnecessarily large amount of liquid to be discharged with the gas, limits the compression ratio, and limits the capacity of the pump in relation to the rotor diameter.

In prior hydroturbine pumps it has been the practice first to provide the casing with a cylindrical bore of slightly larger radius than the rotor, whose axis is to coincide with the axis of the rotor shaft. Ordinarily, each lobe is then formed as a cylindrical bore, the cutting tool operating with a fixed radius but about a center which is uniformly offset relative to the axis of the first bore. Since the axes of the lobe bores extend parallel to the axis of the first bore, and all the bores are cylindrical, the lobe bores intersect the first bore along straight lines which are parallel to the bore axes and to one another. As a result of this construction comparatively narrow lands of uniform width are provided between the lobe bores. The inner surfaces of these lands, which are coaxial with the rotor and conform closely to it, are all that remain of the inner surface of the first bore after the lobe bores have been formed. Any plane which includes the shaft axis will intersect either the lands or the lobe boundaries in straight lines parallel to such axis.

The fact that the lobe elements extend parallel to the shaft axis while the inner chamber boundary is conical gives rise to difficulties which the present invention is designed to overcome. Diagrammatic Figures 1 to are successive, fragmentary longitudinal sectional views of a conventional conical pump and illustrate the nature of the difiiculty referred to. The section planes of Figures 1 to 5, respectively, correspond to the section planes of Figures 6 to 10, respectively, the latter section planes being indicated by section lines 66 to Iitilttl, respectively, of Figure 12.

Diagrammatic Figures 6 to are similar views of a pump embodying features of the present invention and illustrate how the difficulties are surmounted. Diagrammatic views 1 to 5 show the action of the liquid as it progresses from land to land in a prior art pump.

Figure 1 illustrates the casing 1, a head 2, a rotor 3 and a ported cone 4 of a conventional pump. The section is taken along the minor axial plane of the pump. Figure 2 is a sectional view similar to Figure 1 but taken a little later in the cycle after the bucket involved has reached inlet port 5. Figure 3 is a sectional view taken substantially upon the major axis of the pump chamber. Figure 4 is a section taken after tthe bucket involved has reached outlet port 6. Figure 5 is a section taken 180 after Figure l and again upon the minor axial plane of the pump chamber.

These figures show the relationship between the displacement chambers of the rotor buckets and the displacement chamber of the lobe itself in the conventional pump. The lobe displacement volume is, in every radial plane, of rectangular cross-section, whereas the corresponding rotor displacement is of tapering cross-section because of the conical form of the inner boundary of the chamber. Equal axial increments of a bucket are of non-uniform volume, whereas the corresponding equal axial increments of a lobe are of uniform volume. In other words, the opposed displacement values of the rotor and the lobe are not matched axially.

This unmatched displacement sets up an uneven action in the lobe, and also in the rotor. It sets up cross currents in the rotating ring, produces turbulence and loss of liquid, and reduces the compression ratio and the pumping capacity, all as will be more fully explained.

On the outward stroke of the liquid ring, the axially uneven amount of water leaving the rotor bucket has to adjust itself to the even cross-section of the lobe, and in so doing, the excess of liquid from the end of the chamber where the cone diameter is least, forces its way toward the opposite end of the chamber. The liquid, as coon as it gets more or less distributed over the symmetrical cross-section of the lobe on the outward stroke, has to again redistribute itself unevenly as it refills the tapered bucket bottom on the inward stroke.

Figure 1 shows the condition when a bucket passes a land 7. At this point the rotor bucket is substantially completely filled with liquid, or as nearly filled as it can be in view of the operating conditions which will be described. It is ready to start the suction stroke. Under these conditions, the difference in radius between the opposite sides or shrouds 8 and 9 of the rotor sets up an uneven centrifugal force across the bucket. This initiates a cross current which circulates in the direction shown by the arrows. The heavier mass of liquid opposite the small diameter of the cone moves out at the expense of the lighter mass opposite the larger end of the cone. The lobe 10, being of unvarying depth in each radial plane,

4 does not offset or correct this initial internal movement of the liquid and its momentum persists during the remainder of the cycle, as illustrated at Figures 2, 3, 4 and 5. This is a parasitic or nonuseful current which represents loss of efiiciency caused by the added friction.

The circulating movement has a number of disadvantageous consequences.

During the compression stroke, Figures 3, 4 and 5, the uniformly reducing lobe 10 is forcing the liquid ring back evenly into the rotor bucket. But there is then more than enough liquid opposite the larger end of the cone to completely fill the shallow end of the bucket. The inner free surface of the liquid ring forms generally a cylindrical surface parallel to the axis. It is approaching a conical surface as represented by the bottom of the rotor buckets, and the cone 4 with its ports 5 and 6. As the cylindrical front of the liquid ring first reaches the cone, much of the liquid is ejected out of the outlet port 6 at the larger diameter of the cone, as illustrated in Figure 4. As this front approaches the small end of the cone, so much liquid has been lost that there is an insufficient amount remaining to completely discharge the compressed gas out of the port at the smaller end of the cone, so that some residual gas is left in the bucket as it reaches the land, as shown in Figure 5.

This unexpelled gas, of course, expands at the next suction stroke, and it represents a net loss in capacity. This is equivalent to the clearance loss in a reciprocating piston type compressor. The parts may be shaped to minimize these losses, but they can not overcome the combined circulating losses and the attempt to fill the axially uneven bucket volume by a lobe of axially uniform displacement.

Some of the liquid is even caused to spill out through the inlet port 5 as indicated by the arrow of Figure 2.

In accordance with the present invention, these defects are overcome or greatly reduced by making the displacement of the lobe substanitally match axially the displacement of the rotor. In other words, the lobe is made deeper opposite the smaller end of the conical boundary of the rotor and shallower opposite the larger end of the conical boundary of the rotor.

By substantially proportioning the axial lobe displacement to the adjacent rotor volume, the two principal detrimental effects described above as present in the standard construction are substantially eliminated.

The principle of the invention is diagrammatically illustrated in Figures 6 to 10. These figures illustrate in fragmentary form a pump embodying the invention and a sequence of operating steps corresponding in phase to the operating steps illustrated in Figures 1 to 5, respectively.

In Figure 6, the casing 1a is shown as intersected by the section plane at a land 7a, the land being of uniform radius axially of the pump as before. The rotor 3a, the head 2a and the cone 4a are all shown in fragmentary form.

As seen in Figure 7, the lobe 10a has its inner wall sloped outward toward the left whereas the outer surface of the cone 4a is sloped inward toward the left. The slope of the lobe 10a is also illustrated in Figures 8 and 9. In Figure 10 the section plane again intersects a land 7a which like the land illustrated in Figure 6 is of uniform radius axially of the pump.

The cross-current circulation, which is initiated in the conventional pump by the uneven centrifugal force exerted when the rotor is filled with liquid, is absorbed and stopped by providing additional volume in the lobe opposite the small end of the cone. This volume is proportioned so that it substantially axially matches the uneven volume of the conical central section of the rotor.

Figure 7 illustrates an intermediate portion of the suction stroke. The fact that lodgment space is provided for the excess liquid thrown outward at the end of the rotor at which the cone diameter is smallest, avoids the initiation of a water circuit of the kind illustrated in Figures 1 to 5. In addition to stopping the recirculation friction losses, this also reduces the tendency of the conventional pump to spill sealing liquid out of the inlet port as is done in the conventional pump construction.

The same axially proportioned amount of liquid is directed around the lobe as illustrated in Figure 8. On the compression stroke, Figures 8 to 10, the liquid is directed back into the rotor in proportion to its axial displacement. As a result, the greater displacement requirement of the small cone end of the rotor is provided by the enlargement of the lobe at this end while the lesser dis placement requirement of the rotor at the large cone end is merely satisfied by the lesser volume of liquid supplied from the relatively shallow lobe end. Because there is not a great surplus volume of liquid forced inward by the lobe at the large cone end, the tendency to spill liquid through the outlet port at the large cone end is reatly reduced.

The inner free surface of the revolving liquid ring actually is forced into a conical surface of revolution during the compression stroke by the axially uneven lobe displacement, as seen in Figure 9. This conical surface more and more nearly matches that of the central cone as the compression stroke progresses. It is because the inner surface assumes this conical shape that the loss of liquid through the ports is so nearly eliminated.

The rotor of Figures 6 to 10 is more completely filled with liquid toward the conclusion of the compression stroke than formerly. The gas is more completely discharged, and there is therefore less gas to re-expand on the following suction stroke.

By following the principles of this invention the maximum use is made of the liquid seal. This results in increased efi'iciency, greater capacity, greater pressure range, and the ability to operate with the intake closer to the vapor pressure of the liquid seal.

The efficiency is increased by the elimination of parasitic friction losses, the reduction of loss of seal through the outlet, and the reduction of clearance losses by the 1016 complete refilling of the rotor upon the compression stroke. The capacity is increased for a given size of compressor by the more complete filling of the rotor on the compression stroke as previously outlined.

The possible maximum capacity of a given diameter rotor is also increased by this invention as will now be pointed out, and this is of great commercial importance.

It is a characteristic prerequisite of liquid ring type compressors, that for a given compression range all sizes must operate at a definite peripheral or tip velocity to develop the required kinetic energy in the liquid ring and most satisfactorily perform the work of compression over this pressure range.

Because of the above requirement, rotors of large diameter (and hence of large capacity) must operate at relatively low rotational speeds, while rotors of small diameter (and hence of small capacity) must operate at relatively high rotational speeds.

In a series of proportionate compressor sizes for a given pressure range, because of the requirement for the same peripheral rotor speed, the capacity will vary as the square of the rotor diameter, but the weight will vary roughly as the cube of the rotor diameter. Thus, greater capacity is obtained only through a disproportionate increase of weight and cost. Of further cost disadvantage is the fact that the larger pump must operate at a lower rotational speed. This requires a larger, more expensive electric motor when directly connected, or a larger speed reducing drive when not directly connected.

it is present general practice to size a series of compressors in diameter steps best matching commercial motor speeds. Variation in capacity is also attained by further dividing each rotor diameter series into several sizes by varying the length of the rotor. The rotor length can run from 10% to 40% of the rotor diameter.

eter in conventional pumps. Such pumps will not operate eificiently with rotor lengths greater than 40% of rotor diameter because of the unbalanced forces previously reviewed herein.

For the reasons stated above, it is clear that any improvement that provides an increase of maximum capacity for agiven diameter of rotor is of real commercial importance. The present invention enables the rotor length to be increased to at least 50% of the rotor diam- This constitutes an increase of 25% over the maximum capacity heretofore available.

The reason a pump embodying the present invention can operate with a rotor twenty-five per cent greater in length is that the lobe shape directs a smaller proportion of the liquid to the large cone end on the discharge stroke. Because the inner free surface of the reducing liquid ring tends to match the conical surface of the cone, the cone port for the rotor itself may be made longer before an excessive amount of sealing liquid will be lost through the port opening at the larger end of the cone.

The forced reverse vortex of the liquid ring on the compression stroke which closely matches the contour of the discharge ports allows greater energy to be retained in the liquid ring up to the final gas discharge. It is not partially lost by spillage out of the port at the larger diameter of the cone. As a result, the compressor can do more work for a given rotational speed. It can go to higher compression ratios. It can also cover the same pressure ranges as present designs but at lower rotational speeds. This lower possible speed results in stiil better efiiciency because of the reduced friction losses at the lower speeds. it also allows a greater overall operating speed range.

The reduction of parasitic currents and the reduction of liquid losses described allow this pump to achieve low absolute pressures at the intake more nearly approaching the vapor pressure of the sealing liquid. This is particularly beneficial in single or in multi-stage vacuum pumps.

in some forms of lobe shapes giving the required axial displacement pattern there results an improvement inthe cavitation characteristics of the unit as will be described later.

The foregoing description covers the principle of the invention and the principal advantages to be derived from it. Many designs of lobes can be contrived incorporating these principles. Several of the more advantageous forms are shown in Figures 11 to 22 and these will now be described.

In the pump of Figures 11 to 13, the body or casing la, supported by feet 11, forms the outer boundary for two working chambers in which the rotor 3a runs. The body 1a is formed with an inwardly extending partition flange 12 which meets and cooperates with the partition 8a that forms part of the rotor 3a.

The rotor 3a has its hub 14 keyed to a drive shaft 15. The shaft 15 is mounted in bearings 16 which are carried by brackets 17. The brackets 17 are secured by screws 13 to the respective heads 2a, and the heads in turn are secured upon the body it: by bolts 29 and nuts 21.

Ported cones 4a form the inner boundaries of the pumping chambers, being formed with inlet and dis charge passages through which gas is admitted to the pumping chambers and expelled therefrom. The cones 4a extend through the heads 19 and are formed with flanges 23 through which they are attached, by means of screws 24, to the respective heads 19. The heads 19 are provided with inlet and discharge passages which communicate with the corresponding passages of the cones.

It will be observed that the outer walls of the lobes 19a do not extend parallel to the axis of the shaft 15 but that each wall, as seen in Figure 11, extends at a slope opposite to that of the corresponding cone. This is a departure from the practice which has been invariably followed in the past.

According to prior practice the casting which is to form the casing or body is first bored by a lathe-carried tool. The tool is operated at a fixed radius and is caused to act upon the body casting as the casting is moved axially in a path at right angles to the plane of rotation of the tool. The resulting bore is cylindrical. Through out this first boring operation the axis of the casting is caused to coincide with the center of tool rotation at all times.

Each lobe is then bored by choosing an offset center and a fixed radius. As the boring tool is operated the casting is advanced axially, at right angles to the plane of tool rotation, so that the second cylinder is bored with its axis parallel to the axis of the first cylinder and sep arated from it by the amount of the offset. The other lobe is similarly bored by providing an equal but opposite offset for the tool center and by utilizing the same operating radius for the tool as was used in boring the first lobe.

When this practice is followed, every plane which includes the axis of the first bore will inevitably intersect either a land or a lobe of the casing in a straight line parallel to such axis as illustrated in Figures 1 to 5.

The casing of Figures 12 to 14 is constructed upon a different principle. The first bore is formed as before, the center 25 (Figure 12) being chosen for the tool and the casing being advanced so that its axis always includes that center. This results in the formation of the cylindrical surface segments 27 of the lands 7a.

The upper lobe is then bored with a constant radius R and with a variable offset 28 which increases from through 01 to 02 (Figure 13). This machining operation is performed by setting the body on the turn-table of the boring mill or lathe with the axis of the body tipped out of parallel with the machining axis by the amount of the slope required on the lobe. The boring mill or lathe tool travels parallel with the machining axis. The boring center which starts at 26 may thus be caused to progress outward to 2) in the course of the boring operation. The second lobe is bored according to the same principle, using the same radius throughout and the same initial and final offsets, the slope of the second lobe axis being equal but opposite to the slope of the first. V

The slopes of the lobe axes are so chosen as to secure substantially matching displacement volumes section for section of the rotor buckets and of the lobes, the slope of the lobe wall ftiBa along the major axial plane of the chamber being less than, and opposite to, that of the associated cone.

An added benefit that this type of lobe gives over and above matched displacement results from the fact that lands of tapering width are produced. The radius and initial offset may advantageously be so chosen, as illustrated in Figure 13, as to cause the lands "in to have a comparatively narrow width at the starting end and to widen out substantially toward the final end.

Because the lands taper, their edges are not crossed simultaneously by a rotor blade, but each blade passes progressively from land to lobe and vice versa. This is decidedly advantageous as compared with the abrupt change which occurs in conventional pumps when the entire edge of the blade does pass simultaneously from land to lobe or from lobe to land. This abrupt change in the conventional pump causes noise, vibration and cavitation under some operating conditions. With the tapered land, the shock is distributed over several degrees of rotation, the result being that the shock is considerably reduced in intensity and that the cavitation, noise and vibration are greatly reduced.

Another form of construction embodying the invention is illustrated in Figures and 16. The pump is like the pump of Figures 11 to 14 save that the lobes 1% are formed and constructed differently.

In this form of the invention the first or land bore is formed as before. Each lobe is formed with a uniform offset Oh and a variable radius. The initial radius Rb is relatively short, While the final radius Rel; is relatively long. The radii R112 of the two iobes is so chosen in relation to the offset that the land 71) is caused to taper to a comparatively slight Width at the end where the radius is greatest, this being the end where the cone diameter is least. The mean radius Rsl is desirably substantially the same as the radius which would be uniformly employed in forming the lobes of a conventional pump. Because the radius Rb is substantially less than the radius R112, the lands 7]: are of substantial Width where this lesser radius is used.

in this form of the invention each lobe is conical in form, the slope of the lobe cone being so chosen as to provide substantially the desired matched displacement of the lobe and the rotor, section for section axially of the rotor.

The machinin operation for forming either of the lobes 1% is performed by setting the body 1b on the turntable or face plate of the boring mill or lathe with the axis of the body parallel with the machining axis but offset from this axis the required amount Ob. The boring machine ram or lathe tool carriage, which holds the cutting tool, is set to travel axially at an angle with the machining axis the required number of degrees to give the taper desired to the inner surface of the lobe. The values for the offset Oh, the midpoint radius Rel and the taper may be readily determined to fulfill the requirements of the rotor and to produce the other characteristics desired.

As before, tapering lands result from the boring described, and these lands have the desirable characteristic that they are crossed progressively by each of the axially extending rotor blades. It is of interest to note that Whereas in the form of construction illustrated in Figures 12 to 14 the lands are narrowest at the end where the cone diameter is greatest and Widen out where the cone diameter is least, in the embodiment of Figures 15 and 16 the taper of the lands runs in the opposite direction.

The principles of Figures 13 and 16 may be combined to produce matched displacement, and this in such a way as to cause the lands to taper in either direction desired.

In Figures 17 and 18, both the offset and the radius of each lobe bore are caused to vary, the pump being otherwise like the pump of Figure 11. At the large cone end the minimum offset 00 is employed simultaneously with the minimum radius Re. The offset is gradually increased to a maximum of 002 while the radius is simultaneously increased to a maximum RC2. The mean offset 001 and the mean radius Rel occurring midway of the length of the bore may desirably be the same as the uniform offset and uniform radius employed in boring the lobe of a conventional pump.

This machining operation is performed by setting the body 1c on the turntable or face plate of the boring mil or lathe with the axis of the body tipped out of parallel with the machining axis by the amount required to produce the desired change of oifset, and with the machining axis initially offset from the body axis by the amount 00. The boring machine ram or lathe tool carriage, which holds the cutting tool, is set to travel axially at an angle with the machining axis to produce the desired variation of radius.

The offset and radius variations may be combined in various ways to produce matched displacement. The radius and offset may be concurrently increased as desired or one may be diminished While the other is increased so long as a relationship is shown which produces the desired matched displacement.

In Figures 19 to 21 disclosure is made of a hydroturbine pump embodying the invention and like the pumps described in the preceding figures except for a further variation of the body construction. The body is made to include lopsided lobes as embodied in Nash pumps known as the K type. Although Figure 19 is intended to illustra.e the present invention, it is desirable that the body construction of a standard or known K type pump first be made clear, and this may also be done by reference to Figure 19. The configuration of the pump body substantially as illustrated directly in the section plane of Figure 19 woud be typical of the unvarying cross-sectional shape and dimensions of a standard K type pump body.

In the section plane of Figure 19, the body is seen to comprise lands .31 and 32 whose inner surfaces are concentric with the shaft axis 33, the lands being disposed in alternation with

lobes

34 and 35. The lobes are duplicates of one another, but each of them is unsymmetrical with respect to the major axial plane 23-26) of the pump chamber. The lobe 34 is seen to have an arcuate surface 37 of comparatively small radius Rel whose center is located at 38, which surface merges into an arcuate surface 39 of comparatively large radius RdZ whose center is located at 40.

Since the cross-sectional shape of the standard K type pump is the same in every plane perpendicular to the shaft axis, it follows that every lobe element extends parallel to the shaft axis, and that the shape of the lobe section in every plane which includes the shaft axis is rectangular. The standard pump having K type lobes, therefore, presents the same problem of unmatched displacement of the lobe and rotor as the conventional pump in which the lobes are of symmetrical design.

In making the standard pump with K type lobes the general practice is to use a cutting tool which does not revolve about the cutting axis and to rotate the body relative to the tool. The tool is mounted for radial displacement toward and from the axis 33, about which the body turns and along which it is advanced, and is controlled by a cam which rotates in unison with the body. Both lobes of the standard pump may be formed at a single operation by this method.

The novel pump of Figures 19 to 21 bears the same relation to the standard K type pump that the pump of Figures 11 to 13 bears to the conventional pump having symmetrical lobes. shape is included, but the variable oliset principle is utilzed in order to provide matched displacement, section for section, of the lobe relative to the rotor.

In forming the upper lobe 34, for example, the cutting tool is controlled precisely as before, and the work is advanced toward the tool in the same direction as before, but the rotating work itself is tilted to cause the axis 33 of the body to be inclined relative to the axis of rotation, the direction of the. machining center line relative to the body being indicated by the line 331'. The work is advanced in the direction of the axis of rotation, but this axis now coincides with the line 33a instead of with the axis 33. This causes the centers of the arcuate surfaces 37 and 29 to progress outward relative to the body away from the minor axial plane of the body, which is at right angles to the major axial plane 2ii2(i, as the cutting progresses, so that the center of curvature of the surface 37 shifts progressively from 41 to 38 and the center of curvature of the surface 39 shifts progressively from 42 to 4b. The resulting lobe increases in depth toward the end of the chamber at which the small end of the cone will be located to provide the desired matched displacement. The slope of the upper lobe wall along the major axial plane is seen in Figure 20.

Since the lower lobe is required to have a slope opposite to that of the upper lobe, it is not possible to form both lobes at a single operation as before. The cam is accordingly designed to cause the cutting tool to be active only while traversing the sector of one lobe. The second lobe is formed in a manner identical with that described for the first. The body is, however, tilted in the opposite direction but atan equal inclination to the machining center line, the new direction of the machining center line relative to the body being indicated by the line 33b.

The K type cross-sectional The formation of the lobes in the manner described causes the lands to be bounded by

edges

43 and 44,

which converge toward one another as illustrated in they case of the land 31 in Figure 20. The edges of a land incline in the same direction in this instance, as shown in Figure 20. Although both edges are crossed progressively by each rotor blade they do not produce a marked variation of land width.

The avoidance of shock, strain, vibration and cavitation by providing for progressive change of conditions as the rotor turns, is disclosed in various forms and broadly claimed in my copending application, Serial No. 211,167 filed February 15, 1951 for Hydroturbine Pump, now Patent No. 2,672,277. a

I have described what I believe to be the best embodi ments of my invention. I do not wish, however, to be confined to the embodiments shown, but what I desire to cover by Letters Patent is set forth in the appended claims.

I claim:

1. In a hydroturbine gas pump, in combination, a rotor, chamber forming means enclosing the rotor and comprising an inner cone and a surrounding outer casing, said casing characterized by the fact that it is formed to define lobes which are of progressively increasing depth with respect to the rotor axis from the end at which the diameter of the cone is greatest toward the end at which the diameter of the cone is least.

2. In a hydroturbine gas pump, in combination, a rotor, chamber forming means enclosing the rotor and comprising, a ported cone which forms the inner chamber boundary, a lobed body which forms the outer chamber boundar said body being characterized by the fact that the lobe depth varies with respect to the rotor axis, lengthwise of the chamber, the depth of the lobe being increased as the cone diameter diminishes in order to provide substantially matched displacement volume section by section of the lobe and rotor.

3. in a hydroturbine gas pump, in combination, a rotor, chamber forming means enclosing the rotor and comprising an inner ported cone and an outer lobed body extending therearound; the rotor conforming interiorly to the contour of the cone, and being of uniform external diameters; the body being characterized by the fact that the lobe depth varies with respect to the rotor axis, lengthwise of the chamber, the depth of the lobe being increased as the cone diameter diminishes, in order to provide progressively more lodgment space for the liquid thrown outward, in compensation for the fact that the quantity of liquid thrown outward by the rotor is necessarily progressively increased from the larger end to the smaller end of the cone.

4. In a hydroturbine gas pump, in combination, a rotor, chamber forming means enclosing the rotor and comprising an inner ported cone and an outer lobed body extending therearound; the rotor conforming interiorly to the contour of the cone, and being of uniform external diameter; the body being characterized by the fact that the lobe depth varies with respect to the rotor axis, lengthwise of the chamber, the depth of the lobe being increased as the cone diameter diminishes in order to provide progressively more lodgment space for the liquid thrown outward by the rotor as the expanding portion of the lobe is traversed by the rotor, in compensation for the fact that the quantity of liquid thrown outward by the rotor is necessarily progressively increased from the larger end to the smaller end of the cone, and to cause progres-- sively more inward displacement of the liquid by the lobe from the larger end to the smaller end of the cone as the contracting portion of the lobe is traversed by the rotor.

5. A hydroturbine pump body adapted to form the outer boundary of a pumping chamber and formed with alternate lands and lobes, the lands being of cylindrical I contour and concentric with the body axis, and the lobes 1 1 being of progressively increasing depth with respect to the body axis lengthwise of the body.

6. In a hydroturbine gas pump, in combination a rotor, chamber forming means enclosing the rotor and comprising an inner ported cone which forms the inner boundary of the chamber, and an outer surrounding body having lobes, which forms the outer boundary of the chamber, the inner lobe surfaces being formed with centers of curvature uniformly offset from the rotor axis, but having its radius increased progressively from end to end, with the smallest radius at the same end as the largest diameter of the cone.

7. In a hydroturbine gas pump, in combination, a rotor, chamber forming means enclosing the rotor and comprising an inner ported cone which forms the inner boundary of the chamber, and an outer surrounding lobed body which forms the outer boundary of the chamber, the rotor conforming interiorly to the contour of the cone and being of uniform external diameter, said body being formed with lobes which vary in depth with respect to the rotor axis lengthwise of the chamber, the lobe depths being increased as the cone diameter diminishes in order to provide progressively more lodgment space for liquid thrown outward by the rotor in compensation for the fact that the quantity of liquid thrown outward is necessarily progressively increased from the larger to the smaller end of the cone, said lobes having their inner surfaces formed with centers of curvature uniformly offset from the rotor axis and having radii which increase progressively from the end corresponding to the largest I diameter of the cone to the end corresponding to the smallest diameter of the cone.

8. A hydroturbine pump body adapted to form the outer boundary of a pumping chamber, and formed with alternate lands and lobes, the lands being of cylindrical contour and concentric with the body axis, and the lobes being of progressively increasing depth with respect to the body axis lengthwise of the body, and having inner surfaces formed with centers of curvature uniformly offset from the body axis but having radii which increase progressively from the region of minimum lobe depth to the region of maximum lobe depth.

9. In a hydroturbine gas pump, in combination, a rotor chamber forming means enclosing the rotor and comprising an inner ported cone'which forms the inner boundary of the chamber, and a body having lobes which forms the outer boundary of the chamber, the inner lobe surfaces being arcuate and having uniform radii, but having their centers of curvature progressively offset from the rotor axis, the least offset being at the same end as the largest diameter of the conical boundary.

10. In a hydroturbine gas pump, in combination, a rotor, chamber forming means enclosing the rotor and comprising an inner ported cone which forms the inner boundary of the chamber, and a surrounding body having lobes which forms the outer boundary of the chamber, the rotor conforming interiorly to the contour of the cone and being of uniform external diameter, said pump being characterized by the fact that the lobe depth varies with respect to the rotor axis lengthwise of the chamber, the lobe depth being increased as the cone diameter diminishes, in order to provide progressively more lodgrnent space for liquid thrown outward by the rotor, in compensation for the fact that the quantity of liquid thrown outward by the rotor is necessarily progressively increased from the larger to the smaller end of the cone, said lobes having inner arcuate surfaces formed with uniform radii but with their centers of curvature offset progressively from the rotor axis, from the end corresponding to the largest diameter of the cone to the end corresponding to the smallest diameter of the cone.

11. A hydroturbine pump body adapted to form the outer boundary of a pumping chamber and formed with alternate lands and lobes, the lands being of cylindrical contour and concentric with the body axis, and the lobes being of progressively increasing depth with respect to the body axis lengthwise of the body, the lobes having inner arcuate surfaces of uniform radius but having their centers of curvature offset from the rotor axis by progressively increasing amounts from the region of minimum lobe depth to the region of maximum lobe depth.

12. In a hydroturbine gas pump, in combination, a rotor, chamber forming means enclosing the rotor and comprising an inner ported cone which forms the inner boundary of the chamber and a body having lobes which forms the outer boundary of the chamber, each of the lobes having an inner arcuate surface formed with a variable offset of its center of curvature from the rotor axis and with a variable radius, both the variable offset and the variable radius increasing progressively lengthwise of the chamber with the smallest offset and the smallest radius at the same end as the largest diameter of the inner conical boundary.

13. In a hydroturbine gas pump, in combination, a rotor, chamber forming means enclosing the rotor and comprising an inner ported cone which forms the inner boundary of the chamber, and a surrounding body having lobes which form the outer chamber boundary, the rotor conforming interiorly to the contour of the cone and being of uniform external diameter, said body being characterized by the fact that the lobe depths vary with respect to the rotor axis lenghwise of the chamber, the depths of the lobes being increased as the cone diameter diminishes in order to provide progressively more lodgment space for liquid thrown outward by'the rotor, in compensation for the fact that, the quantity of liquid thrown outward by the rotor is necessarily progressively increased from the larger end to the smaller end of the cone, each of said lobes having an inner arcuate surface formed. with a varying offset of its center of curvature from the rotor axis and a varying radius, both the offset and the radius increasing progressively from the end corresponding to the largest diameter of the inner conical boundary to the end corresponding to the smallest diameter of the inner conical boundary.

14. A hydroturbine pump body adapted to form the outer boundary of a pumping chamber and formed with a plurality of lobes, the lobes being of progressively increasing depth with respect to the body axis lengthwise of the body, and each having an inner arcuate surface formed with a variable offset of its center of curvature from the rotor axis and a variable radius, both the offset and the radius increasing progressively from the region of minimum lobe depth to the region of maximum lobe depth.

15. In a hydroturbine pump, in combination, a rotor having blades, chamber forming means enclosing the rotor and comprising an inner ported cone which forms the inner boundary, and a body which forms the outer boundary thereof, the body including a plurality of lobes which vary progressively in depth with respect to the rotor axis, in alternation with lands of cylindrical internal contour concentric with the rotor axis, each lobe having an inner arcuate surface formed with its center of curvature uniformly offset from the rotor axis, and with a variable radius which increases progressively from the end at which the cone diameter is largest to the end at which the cone diameter is smallest, the lands being thereby tapered in width and having their edges disposed to be crossed progressively by each rotor blade.

16. In a hydroturbine pump, in combination, a rotor having blades, chamber forming means enclosing the rotor and comprising an inner ported cone which forms the inner boundary of the chamber, and a body forming the outer boundary thereof, the body having a plurality of lobes which vary progressively in depth with respect to the rotor axis lengthwise of the chamber, in alternation with lands of cylindrical internal contour which are concentric with the rotor axis, each lobe having an inner arcuate surface formed with a uniform radius but with a variable oifset of its center of curvature from the rotor axis which increases progressively from the end at which the cone diameter is largest to the end at which the cone diameter is smallest, the lands being thereby caused to be tapered in width and having their edges disposed to be crossed progressively by each rotor blade.

17. In a hydroturbine pump, in combination, a rotor, chamber forming means enclosing the rotor and comprising an inner ported cone which forms the inner boundary of the chamber, and a body forming the outer boundary thereof, the body having a plurality of lobes which vary progressively in depth with respect to the rotor axis, in alternation with lands of cylindrical internal contour concentric with the rotor axis, each lobe having an arcuate inner surface formed with a varying offset of its center of curvature from the rotor axis and with a variable radius, both of which increase progressively from the end at which the cone diameter is largest to the end at which the cone diameter is smallest, the relative change of the offset and the radius being such that the lands are caused to be tapered in width and to have their edges crossed progressively by each rotor blade.

18. In a hydroturbine pump, in combination, a rotor having rotor enclosing blades, chamber forming means comprising a body which forms the outer chamber 1'- boundary, the body being formed with a plurality of lobes which are excentric with relation to the rotor axis in alternation with lands of cylindrical internal contour concentric with the rotor axis, the lands being formed to taper in width and having their edges disposed to be crossed progressively by each rotor blade.

19. In a hydroturbine gas pump, in combination, a rotor, chamber forming means enclosing the rotor and comprising an inner ported cone which forms the inner boundary of the chamber, and an outer lobed body which forms the outer surroundingwall of the chamber, the rotor conforming interiorly to the contour of the cone and being of uniform external diameter, the novel lobed body being characterized by the fact that the lobe depth varies with respect to the rotor axis lengthwise of the chamber, the lobe depth being increased as the cone diameter diminishes, in order to provide progressively more lodgment space for liquid thrown outward by the rotor in compensation for the fact that as the quantity of liquid thrown outward by the rotor is necessarily progressively increased from the larger to the smaller end of the cone, and by the further fact that each lobe is unsymmetrical with respect to an axial plane of the chamber along which the lobe depth is greatest.

20. In a hydroturbine gas pump including, in combination, a rotor, chamber forming means enclosing the rotor and comprising an inner ported cone which forms the inner boundary of the chamber, and a body having lobes which form the outer chamber boundary, said body being characterized by the fact that each lobe in every transverse plane is of unsymmetrical construction, having one arcuate portion of relatively small radius which has its center of curvature otfset from the rotor axis by a comparatively large amount and another arcuate portion of relatively large radius which has its center of curvature offset from the rotor axis by a comparatively small amount, and by the further fact that the lobe depth varies with respect to the rotor axis lengthwise of the chamber, said lobe being formed wih a bore of unvarying crosssectional dimensions whose centers of curvature progress in parallel relation away from a fixed axial plane which diverges from the rotor axis, and providing as the end of the chamber is approached at which the smaller end of the cone is disposed, to provide an ever increasing lobe depth toward said chamber end.

21. In a hydroturbine gas pump, in combination, a rotor, chamber forming means enclosing the rotor and comprising an inner ported cone which forms the inner boundary of the chamber, a body having lobes which forms the outer chamber boundary, said pump being characterized by the fact that the length of the pump chamber is not substantially less than the radius of the rotor, and by the further fact that the depth of the lobe increases with respect to the rotor axis as the diameter of the cone diminishes, substantially matched displacement of the lobe and rotor section for section lengthwise of the chamber being provided.

22. in a hydroturbine gas pump, in combination, a rotor, chamber forming means enclosing the rotor and comprising an inner ported cone which forms the inner boundary of the chamber, and an outer surrounding body having lobes which forms the outer chamber boundary, the rotor conforming interiorly to the contour of the cone and being of uniform external diameter, said pump being characterized by the fact that the lobe depth varies lengthwise of the chamber, the depth of each lobe being increased as the cone diameter diminishes in order to provide progressively more lodgment space for liquid thrown outward, by the rotor, in compensation for the fact that the quantity of liquid thrown outward by the rotor is necessarily progressively increased from the larger end to the smaller end of the cone, each of said lobes having an inner arcuate surface formed with a center of curvature variably offset from the rotor axis and a varying radius, at least the oifset or the radius increasing progressively from the end corresponding to the largest diameter of the inner conical boundary to the end corresponding to the smallest diameter of the inner conical boundary.

23. A hydroturbine pump body adapted to form the outer boundary of a pumping chamber and formed with a plurality of lobes, the lobes being of progressively increasing depth lengthwise of the body, each lobe having an inner arcuate surface formed with a center of curvature variably offset from the body axis and a variable radius, at least the offset or the radius increasing progressively from the region of minimum lobe depth to the region of maximum lobe depth.

24. In a hydroturbine pump, in combination, a rotor having blades, chamber forming means enclosing the rotor and comprising an inner ported cone which forms the inner boundary of the chamber, and a body which forms the outer boundary thereof, the body having a plurality of lobes which vary progressively in depth, in alternation with lands having cylindrical internal faces concentric with the rotor axis, each lobe having an inner arcuate face formed with a center of curvature variable offset from the rotor axis and with a variable radius, at least the offset or the radius increasing progressively from the end at which the cone diameter is largest to the end at which the cone diameter is smallest the relative change of the oifset and the radius being such that the lands are cause to be tapered in width so that their edges will be crossed progressively by each rotor blade.

References Cited in the file of this patent UNITED STATES PATENTS 2,210,152 Sacha Aug. 6, 1940