US2483370A

US2483370A - Helical multiple pump

Info

Publication number: US2483370A
Application number: US677610A
Authority: US
Inventors: Moineau Adele
Original assignee: Robbins and Myers Inc
Current assignee: Robbins and Myers Inc
Priority date: 1946-06-18
Filing date: 1946-06-18
Publication date: 1949-09-27
Anticipated expiration: 1966-09-27

Description

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Sept. 27, 1949., R. J. L. MOINEAU HELICAL MULTIPLE PUMP Filed June 18, 1946 3 Sheets-Sheet 2 o INVENTOR. @INE '4/55/1 aufs Mol/mwa.

Sem 27, w49. R. J. L. MOINE/xu; 2,483,370

HELI CAL MULT IPLE PUMP Filed June 18, 1946 3 Sheets-Sheet 3 ATTORNEYS.

Patented Sept. 27, 1949 2,483,370 HELICAL MULTIPLE PUMP Ren Joseph Louis Moineau, Moineau, administratrix Louis Moineau, deceased,

Springfield, Ohio, a corporation & Myers, Inc., oi Ohio Paris, France; Adele of said Ren Joseph assignor to Robbins Application June 18, 1946, Serial No. 677,610

' (ci. 10a-s) Claims.

This invention relates to a helical multiple pump and more particularly to a multiple cylinder pump the individual cylinders of which embody the principles disclosed and claimed in my U. S. Patent No. 1,892,217, dated December 27, 1932.

In that patent I have described the theory of operation and general principles of pumps having internal and external helical gear elements, and in which the external element has one more thread than the internal element; for example, the external element may have a double thread whereas the internal element has a single thread, cr the external element may have a triple thread, while the internal element has a double thread.

Pumps operating upon the principles discussed in my above mentioned patent have numerous advantages which make their use desirable in cases where high capacity is desired.

It is therefore, an object of my invention to provide for the utilization of the principle disclosed in my above mentioned patent in multicylinder pumps whereby the output of the pump can be increased many times.

It is another object of my invention to provide a pump utilizing the principles mentioned above which will eliminate the need for thrust bearings because the operation of the pump is axially balanced. It is a further object of my invention to provide a pump along the lines discussed above which needs, however, only a single packing gland, and which will therefore be cheaper to maintain than conventional multicylinder pumps.

A still further object of my invention comprises the elimination of connecting rods such as are found in conventional pumps. In general, my objects include the provision of a multicylinder pump which will be completely balanced, which will have a high capacity, which will be inexpensive to maintain and which will have a minimum of moving parts.

These and other objects of my invention which will be pointed out in more detail hereinafter, or which will be apparent to one reading these specifications, I accomplish by that certain construction and arrangement of parts of which I shall now describe an exemplary embodiment.

Reference may be made to the drawings forming a part hereof and in which Figure l isa diagram illustrating the principle involved in the present invention.

Figure 2 is a diagrammatic representation in cross section of a simple embodiment of my invention.

Figure 6 is a cross-sectional view taken on the line 6 6 of Figure 4.

Briefly in the practice of my invention, assemble a pair of basic pump elements such as are illustrated in my above mentioned patent, and havingl one and two threads or teeth respectively, in axial relation so that the rotors of the two basic pumps are common; then with the external elements of the two pumps fixed, the common rotor may be gear driven, as will be de-1 scribed hereinafter, and if the common rotor has two portions of opposite hand so that the pump ing thrust is exerted in opposite directions, end thrust is eliminated.

From a study of my above mentioned patent it can be ascertained that assuming the external element to be fixed, the internal element will roll on the inside of the external element. The path of the axis of the internal element will be a circle; but the path of any point on the generating circle of the internal element, where the external element has a double thread and the internal element a single thread, will be in a straight line.

In Figure 1 I have shown the situation diagrammatically. The genera-ting circles of the rotor and stator are indicated respectively C1 and C2, the circle C1 having its center at O1, and the circle C2 having its center at O2. If now a gear P1 is so attached to the rotor that its center as seen on the diagram on Figure 1 is located at Oz with respect to the rotor generating circle C1, then during revolution of the rotor the center of the gear P1 will traverse the straight line O3 O4. In other words, as the rotor and its gear P1 rotate the center of the gear P1 oscillates back and forth in a straight line. The direction of the line of oscillation is dictated by the phase relationship between the stator and rotor and it follows that in order to produce a condition where the line O3 04 is at a right angles to the gear interaxial line O2 O5, careful orientationof the stator and rotor are necessary. In this situation the axis of the gear P1 is displaced a distance 01-0-1; from the axis of the rotor.

The gear P1 may be driven by a gear P2 Whose center O5 is on the perpendicular bisector of the line Oa, Ok. From a consideration of Figure 1, it

3 will be seen that the interaxial distance between the gears P1 and P2 will vary from a maximum O3, Os to a minimum 02, s.

The maximum of the possible differences between 0a, O5 and O2, Os is Os, 0s (1 cos e) a being defined by:

2Xeccentricty of pump (0 O2) tan a= --f--f It is known that for small values oi the angle a, (l cos a) is less than If, for example, the eccentricity of the pump is 2 mm., and the interaxial distance between the gears is 40 mm., and since the distance Oa, O3 is twice the eccentricity of the rotor Oi, O2, it will be seen that the tangent of the angle alpha is .1, and the angle alpha is a little less than 6 degrees, the cosine of 6 degrees is 0.995, from which it appears that the distance Oa, O will only differ from the distance 0s, O5 by one half of 1 percent.

As has been described above, the path of movement oi any point on the generating circle of the rotor will be a straight line, but depending upon the orientation of the stator this straight line may be horizontal or vertical, or at any angle in between. The situation shown in Figure 1 is that in which the stator is so oriented that this path of oscillation is perpendicular to a line connecting the axes of the gears. When the device is in use, the gear P1 will move to right and left of Figure 1, between the points Oa and 04, but since the variation from the proper pitch distance is only one-half of 1 percent, the drive will function properly.

In Figure 2 I have shown more or less diagrammatically how this principle may be utilized. I have indicated a pair of stator elements I0 and a pair of rotors I I,with the rotors I I being mounted on a single shaft I2. The rotors II will preferably be of opposite hand so that the pumping effect will be in opposite directions. It will be observed that the stators I0 have double threads, while the rotors II have single threads. A gear I3 is mounted on the shaft I2, which it will be noted, is eccentric to the rotors II. This eccentricity must be such that by virtue of its relation to the center of mass of the rotor, the center of the gear lies on the generating circle of the rotor, whereby the center straight line while the center of the rotor moves in a circular path. The gear I3 may be driven by a gear I4, through power applied to the shaft I5. The entire arrangement is enclosed within a housing IS, having an inlet port I1, communicating with the inner ends of the two pumps, and an exhaust port I8, communicating with the outer ends of the two pumps. In the device of Figure 2, the uid to be pumped enters through the port I1 and follows the direction of the arrows through the two pumps, and emerges through the port I8. It will be observed that end thrust is completely neutralized so that there is no need for any thrust bearing, and that the pum-p requires only a single packing gland at I9. Since there is no restriction in the mechanism which would prevent full reversibility, it is also possible to reverse the rotation of the mechanism, in which case the ports I8 and I1 of Fig. 2 will be in a reversed relationship to that described above.

In Figures 3, 4, 5 and 6, I have illustrated an of the gear oscillates in a' Li I) eight cylinder pump embodying the principles discussed hereinabove. As will be clear from the drawings, it comprises four pairs of pumping elements, each pair being axially aligned and the four pairs being uniformly distributed about the central axis of the pump. The various stators are indicated at 2D, and they are fixed in the housing. which is indicated generally at 2|. The rotors for each pair are indicated at 22, and may be continuous or integral, or they must be separate and joined together in the center within their respective ldriving pinions 23. This may be accomplished by taper pins 24, or in any suitable manner. The respective stators are so oriented (see Figure 5), that the paths of oscillation of the centers of the driving pinions 23 will be perpendicular to a line connecting the axis of the respective cylinders with the central axis of the pump. The four rotors for the eight stators are driven by a single central gear 25 keyed to the drive shaft 26.

The casing of the pump may be in three parts with a central portion 21 carrying the inlet and

exhaust ports

28 and 29 respectively, to which may be bolted the end casings which have already been designated as 2 I. For convenience in manufacture the casing elements l2l may be identical, in which event the element which is not at the driving end of the pump may have the cored opening 30 plugged as by a plug 3i. The cored opening in the drive end housing 2l may be further machined to provide a seat for the bushing 32, and have a packing gland arrangement 33. This will not be described in detail since it forms no part of my invention. However, it is signincant to note that in the entire pump the only packing gland required is at 33. The end of the shaft 26 may be splined as at 3Q for connection to a driving motor.

The inlet port 28 leads to the central portion of the pump from where the iiud is pumped outwardly through all eight cylinders, into the annular manifolds at each end of the pump indicated at 35. The manifolds 35 communicate with the ducts 36, and lead to the outlet port 29.

It will be clear from the foregoing that I have provided a multi-cylinder pump in which end thrust is entirely eliminated, and which is dynamically balanced so as to run smoothly and quietly. It will also be clear that I have eliminated all but a single packing gland.

While I have shown gear drives in the drawings, it will be understood that, provided the principles herein disclosed are observed, the drive may be accomplished by means of chain and sprocket drives or belt and pulley drives if desired. Numerous modifications may, of course, be made without departing from the spirit of my invention, and I do not therefore intend to limit myself as set forth in the claims which follow.

The term Moineau element as used in the claims, means an assembly of an external helical gear member and an internal helical gear member in which the external member has a double thread and the internal member has a single thread, whereby if the external element is held against movement, lany point on the generating circle of the internal element will oscillate in a line transverse to the axis thereof.

Having now fully described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A mechanism comprising a pair of hypocycloidal gear elements of the type in which the axis of the internal element moves in a circular path, the external element being fixed. an eccentric shaft for said internal element, a drive shaft for said pair of elements, and a driving connection between said drive shaft and said eccentric shaft, said elements being so oriented, and said eccentric shaft having such an eccentricity that the path of oscillation of said eccentric shaft is perpendicular to a line connecting the axis of said eccentric shaft and said drive shaft.

2. A pump having an inlet and an outlet, and comprising inner and outer helical screw elements in engagement, and cross-sectional shapes of hypocycloidal generation, the inner screw element having a single thread andthe outer element having a double thread, said outer element being xed, a shaft for said inner element, power transmission means on said shaft, a drive shaft for said pump and power transmission means on said drive shaft in operative relationship with said iirst mentioned power transmission means, said inner and outer elements being so oriented and the shaft for said inner element having such an eccentricity with respect to said inner Yelement that the path of oscillation oi said inner element shaft is perpendicular to a line connecting the axes of said shafts.

3. A multiple pump having an inlet and an outlet, and comprising two xed outer helical screw elements and two inner helical screw elements in engagement therewith respectively, each of said outer elements having two threads, and each of said inner elements having one thread, the threads of one engaging set of inner and cuter elements being of opposite hand from the threads of the other set of inner and outer elements, said inner elements being xed together to constitute a common rotor, a pinion on said rotor and a driving gear for said pinion,

the sets of said inner and outer elements being so oriented and said pinion having such eccentricity with respect to said rotor that the path of oscillation of said pinion is perpendicular to a line connecting the axis of -said pinion to the axis of said gear.

4. A pump according to claim 3 in which there are at least three pairs of interengaging sets of l elical elements, the elements of each pair being of oppositehand and each pair of said elements having a common rotor and fixed stators, said pairs being symmetrically distributed about the central axis of said pump, a pinion on each of said rotors and a single driving gear for all of said pinions on said central axis, said pairs ofy elements being so oriented and said pinions having such an eccentricity with respect ,to their respective rotors that the path of oscillation of each of said pinions is perpendicular to a line connecting the axis of the respective pinion with the central axis of the pump.

5. A pump acording to claim 4 comprising four pairs of interengaging sets of such elements.

. REN JOSEPH LOUIS MOINEAU.

REFERENCES CITED UNITED STATES PATENTS Number Name Date 2,329,386 Brennan Sept. 14, 1943 FOREIGN PATENTS Number Country Date 425,447 Great Britain Mar. 14, 1935 436,843 Great Britain Oct. 18, 1935 446,291 Great Britain Apr. 27, 1936