US2112463A - Pumping mechanism - Google Patents

Description

March 29, 1938.. s. M. HULL 2,112,463

PUMPING MECHANISM Filed Dec. 11, 1933 2 Sheets-Sheet 1 J'noarzzbr:

i March 29, 1938. s. M. HULL PUMPING MECHANISM Filed Dec. 11, 1933 3 Sheets-Sheet? gazin MJZQZZL flwy a u n I 1 w I J I 55.

Patented Mar. 29, 1938 UNITED STATES PATENT OFFICE 3 Claims.

My invention relates to anovel form of pumping mechanism and method thereof, and is characterized by the employment of a plurality of co-acting and correlatively rotating -members, one of the said members serving as a rotatable casing; a liquid within the said casing member and maintained in operative relationship to the said members by centrifugal force; means for the furnishing of the fluid medium to be pumped, to the said members and for the withdrawal therefrom; and driving means for producing rotation of the said members. As will be fully apparent from this specification and appended drawings, I have discovered a new principle in the design of pumps which substantially eliminates sliding friction between the usual rotating means and the customary fixed casing. This I accomplish by substituting for the customary fixed casing a rotatable casing, preferably in the form of the common centrifuge bowl, within which is located a rotor or rotors in rotatable relationship thereto. While this rotor or rotors may be driven by providing gearing means between rotor and casing, or by an auxiliary driving means such as an electric motor, I prefer to effect rotation of the rotor or rotors within the said rotatable casing by the employment of a liquid between rotor and casing. This liquid, traveling at substantially the same speed as the casing, exercises a viscous drag upon the rotor and causes rotation thereof at a speed corresponding to the relative diameters of rotor and casing. It is thus evident that a liquid gearing is accomplished between casing and rotor and that the peripheral speeds of rotor and casing at the point of operative tangency will be substantially identical if the natural lag between the two be neglected. In practicing my invention, a number of designs may be employed to accomplish the phenomena of suction and pressuredelivery, but I prefer to furnish the rotor or rotors with a series of substantially uniformly located pockets on the periphery thereof, which pockets are successively emptied .of and filled by the liquid disposed between the rotor and the casing. To accomplish this purpose, the rotor or rotors are mounted ,on axes independent of the rotating casing, the said axes being radially displaced with respect to the center of rotation of the said casing. When a plurality of rotors is employed, they may be located Within the casing at uniformly distributed points, i. e., two rotors will be displaced in such a manner that the points of operating tangency thereof with the inside of the casing will belocated at 1 from each other; with three rotors their points I of tangency will be apart; while with four rotors, they may be distributed at each 90 around the circle. Since the rotors have their centers of rotation displaced with respect to the center of rotation of the casing within which they are located, it is apparent that, at the point of tangency thereof with the interior of the casing, the pockets located upon their peripheries will be radially submerged in a wall of liquid contained within the casing, While at a point from their points of tangency, the said pockets will be open to the atmosphere contained within the casing. The radial depth of the said liquid wall is, in practice, proportioned to the radial depths of the pockets on the said rotors and is maintained within the casing as a peripheral layer by the centrifugal force exerted by direct rotation and by the displaceably mounted lip located upon the outer. edge of the said casing. The radial width of this lip is also proportioned with respect to the radial depth of the said pockets and of the said liquid wall to maintain the liquid within the casing during rotation. At the same time, however, the radial width .of the lip is such that any substantial excess of liquid beyond that desired for complete filling of the pockets during rotation is thrown by centrifugal force outside of the .bowl and escapes into a vented housing appropriately fashioned around the said casing. This housing is designed to surround the casing and to provide a substantially tight sealing thereof from the outside environment, being mounted, if desired, upon the frame containing the driving means for the said casing and provided with a sealing means where the shaft connecting the driving means with the casing passes therethrough. This housing may also serve as a support for the axis of rotation of the rotor or rotors and is provided with a duct for the introduction of the fluid to be pumped. In addition, inlet and outlet connections of any suitable design may be furnished to allow ingress of liquid to a point within the rotating casing and for egress of any superfiuity thereof.

Leading from the pockets radially distributed on the periphery of the rotor as described above are small vents opening, from those portions of the pockets radially innermost to the center of rotation and leading to a vertical tubular support upon which is mounted the said rotor. Where tubular support and rotor are integral, these vents are provided with check valves opening radially inward to allow egress of the fiuidbeing pumped, from the said pockets during that portion of the rotation approaching the point of tangency between rotor and casing, i. e., the compression sector. At the same time, these valves prevent the backward flow of the fluid from the tubular support peripherally outward to the pockets during the remainder of the rotation, i. e., the induction portion of the cycle. When the rotor is mounted to revolve upon a fixed tubular support, the said vents leading from the pockets to the support remain unobstructed, the cut-off between pockets and tubular support being accomplished by radially slotting the said tubular support only through a length corresponding to the said compression sector.

I am aware that many rotary pumps have been designed where liquids have been employed as a sealing means between rotor and casing and for effecting displacement of the fluid to be pumped from between vanes or other members of the rotor, i. e., liquid piston'principle. In all cases which have come to my attention, however, a fixed casing of circular or elliptical design has been employed where the liquid sealing and displacing means has been caused to circulate at comparatively high speeds. The friction produced by such a liquid sliding over the inner surface of a fixed casing coupled with the surging of the liquid in some forms of design have caused marked loss in efficiency in devices based on this principle. By employing a rotating casing, such as I contemplate, with substantially identical peripheral speeds between casing and rotor, I accomplish an almost perfect type of rolling engagement between casing, liquid and rotor, and thus eliminate to a large degree the source of inefficiency so inherent in previous devices.

In the drawings, Fig. 1 is a horizontal, sectional View of my pump taken on line II of Fig. 2 illustrating the eccentric relationship of the rotor and bowl.

Fig. 2 is, a vertical, sectional view of the pump shown in Fig. 1.

Fig. 3 is a diagrammatic plane view of a slightly modified form of my invention.

Fig. 4 is a detailed, vertical sectional view of a modified form of rotor and mounting therefor.

Fig. 5 is a View similar to Fig. 2 illustrating the modified form of my invention shown diagrammatically in Fig. 3.

Fig. 6 is a vertical section view of a further modification illustrating the geared relationship between the rotors and bowl.

To make more apparent to those skilled in the art the principles and operating relationships of my novel design, I have caused one embodiment of my invention to be rep-resented diagrammatically in Figures 1 and 2 of the appended drawings, wherein Figure 2 represents an elevation in vertical section of the characteristic elements of my design, and Figure 1 represents a plan view in horizontal section along line II of Figure 2, looking from above. Referring initially to the vertical section represented in Figure 2, 6 is a rotatable casing, preferably in the form of a shell centrifuge bowl, mounted upon shaft 1, which leads to the driving means for effecting rotation. This driving means, not shown, may be an electric motor, belt-driven pulley or other desired means. Rotor 8 is located within casing 6 and is mounted integrally upon tubular shaft 9 which projects through the displaceably mounted cover plate ill of housing It] which tightly encloses casing 6 and is provided with a suitable sealing means I I around shaft 1. Where tubular support 9 projects through housing plate [0, a second sealing means I2 is also provided, while bearings l3 and Hi are suitably disposed between tubular shaft 9 and the surrounding portion of housing plate Hi to assume the vertical and radial thrusts exerted upon the said shaft. Sealing means I l is not necessary when the device is to be employed as a compressor, but in the case of use as an exhaustion or vacuum-producing means, it is important that sealing means II and I2 be provided to operate in a substantially air-tight manner to maintain the interior of housing II] at the pressure existing within casing 6. Lip I5 is displaceably mounted upon the upper periphery of casing 6 and is designed to project radially inward to an extent suficient to maintain the desired radial depth of liquid within casing 6, while at the same time lip l5 will allow any excess of the said liquid to be thrown outward into housing l0 and drained therefrom through vent I6. It will be observed that rotor 8 is mounted with its center of rotation radially displaced with respect to the center of rotation of casing 6 to such an extent that the periphery of rotor 8 is closely adjacent (point of tangency) to the interior wall of casing 6 at a point in line with the centers of rotation and to the side (left) toward which displacement of rotor 8 occurs. Rotor 8 is fashioned in the form of a gear having teeth 11 substantially uniformly disposed around the periphery thereof and forming pockets l3 between the said teeth. In practice, teeth I! are designed not as teeth but as separating membranes having a very narrow width at their crests to facilitate ease of piercing the liquid wall with which they engage. From their crests, these teeth increase gradually in thickness to form pockets therebetween with concave inner surfaces. While teeth I? form the sides of the said pockets, the ends therof are formed by the use of face-plates i9 and 2B, which are integrally fixed to the faces of the rotor and extend peripherally outward to a point flush with the external diameter of rotor 8. Where face-plates l9 and. 20 form the ends of pockets 18 they may be built up or otherwise fashioned on their interior surfaces to produce concave contours in a plane at right angles to the previously cited concave contours in order thus to provide a pocket surface which may easily be wiped entirely free from gas or other fluid by the liquid displacing means to be described later.

Leading from those portions of the pocket surfaces radially nearest to the center of rotation of rotor 8 are tubular vents 2! which connect the said pockets to the interior of tubular support 9. These vents 2| are provided with threads at their radially exterior termini, and check valves 22 provided with corresponding threads. are screwed into vents 2|. These valves 22 are so designed as to open inwardly and are shown in the customary form of ball checks, wherein the balls are seated by centrifugal force but are prevented from displacement into the tubular support oy cages. A liquid which is represented by the cross-hatched areas 23, forming a standing wall within casing 6 and lip I5, is provided in a quantity sufficient to provide a radial thickness thereof substantially equal to the total radial depth of pockets 18. This liquid may be water, mercury, oil or any other suitable liquid medium and when employed for the production of vacua, mercury is to be preferred by reason of its low vapor tension at ambient temperatures. If a vacuum lower than the vapor pressure of water at the temperature to be maintained within the device is notdesired, .water. may be .employed in this event, or when use of the mechanism as a compressor is contemplated, this water may be replenished or changed'to elTect cooling thereof by supplying a continuous stream through inlet 24 to casing 6. vIn the event that excess liquid isthus furnished, such excess will be automatically rejected around lip l5 and thrown off into housing I 6 fromwhich it may be drained through vent l6 through anysuitable sealing means.

Turning now to rotor 8, it is evident that the diameter thereof will be substantially smaller than the diameter of easing 6, and to an extent sufficient for complete clearance between the outer periphery of teeth l1. and the interior face of liquid 23, at a position 180 displaced from the .point where rotor 8 and casing 6 are in close proximity. Teeth l1 and pockets 18 are designed toprovide a suitable depth of the said pockets with respect to the diameters of rotor 8 and easing '6 and to the radialwidth of lip l5 as well as to the length of radial displacement between the centers of rotation of rotor 8 and casing 6 in such a; manner as to allow for the use of a radial depth of liquid 23 substantially equal to the depth of the said pockets. As shown, inlet 25 forms a means of entrance for the fluid medium being pumped through housing plate ID to the interior of easing 6 and thence at the right through the clearance between teeth I! and liquid 23 to pockets l8. As previously mentioned, the said fluid medium is exhausted through vents 2| and valves 22 to the interior of tubular shaft 9 and thence to connection at seal l2.

In Figure 1, as previously mentioned, is shown the plan view and horizontal section through lines taken at aa, looking down from above. Here, numbers have been employed corresponding to those usedin Figure 2 to denote identical elements of design. In this figure, a better representation is afforded of rotor 8, contours of teeth I! and of pockets l8, vents 2|, check valves 22, casing 6, and radial thickness of liquid as represented by circle 23. Circle 18 denotes the housing surrounding casing 6, while casing 6 is represented merely in horizontal section. A horizontal section of the tubular shaft support for rotor 8 is denoted by 9.

In Figure 4 is represented diagrammatically a modification of the design shown in Figures 1 and 2. Here, in place of the integral mounting of rotor 8 upon tubular shaft 9, with check valves 22 and vents 2! of Figure 2, tubular shaft 25 is rigidly mounted in the housing plate denoted by H! in Figure 2 and provided with anti-friction bearings 26 and 21 immediately above and below rotor 28. It is assumed that rotor 28 will be provided with teeth 28 and pockets 30, corresponding to the elements denoted by numerals I1 and I8 in Figures 1 and 2, while vents 3| lead from the radially innermost portions of the said pockets to the interior periphery of rotor 28. In this design, with the radial and axial thrusts of rotor 28 assumed by bearings 26 and 21, it is expediem to fashion that section of a fixed tubular support 25 located between bearings 26 and 21 in the form of. a cone with the interior periphery of rotor 28 being fashionedas a corresponding conical surface. Since these two conical surfaces denoted at their junction by numeral 32 are not load-bearing, and since their proximity can be closely adjusted and rigorously maintained by bearings'ZS and 21, the said conical surfaces may be accurately machined and ground to provide a suitably small clearance therebetween. Assuming that rotation of rotor '28 is effected in a counter-clockwise direction with a maximum clearance between teeth 29 and the interior liquid wall, as described under Figures 1 and 2 occurs at three oclock and that the teeth are at a point of substantial tangency with the interior surface of the casing (not shown) at nine oclock, tubular support 25 is provided along its conical face with a radial slot 33 extending in the plane of rotation of the said rotor from approximately twelve oclock to nine oclock. In this manner, during the compression portion of the revolution of rotor 28, the fluid medium displaced by the liquid form within pockets 38 is'given a means of escape from the said pockets to the interior of tubular support 25, while at thesame time the said pockets .are effectively out off from access to the said tubular support during the remainder of the revolution of the said rotor. In. this case, care should be taken that the conical surface separating rotor 28 from support 25 is located with relation to the depths of pockets 3i], and the radial thickness of liquid within the rotating casing to provide substantially complete displacement of the fluid medium being pumped, from the pockets to the said conical surface. These various factors may be so proportioned with respect to their dimensions and to the radial width of lip I5, shown in Figure 2, as to effect sufficient clearance between rotor 28 and the sealin'g liquid (not shown), and at the same time to effect complete filling of pockets 30 and vents is! up to the point of cut-off. It is self-evident that the design thus illustrated in Figure 4 may be applied to the embodiment of my invention as represented in Figure 3, wherein a plurality of rotors is employed.

Referring particularly to Figs. 3 and 5, a slight modification of my invention is shown wherein l0 indicates a casing similar to casing ID within which a bowl 6 is rotatably mounted upon shaft 1 which in turn may be supported in a bearing structure similar to structure ll. Two similar hollow shafts 9" protrude through casing l8", said shafts being interconnected exteriorly of the casing by the conduit l2" having a common outlet l3". Each shaft 9" is similar to'shaft' 25 shown in Fig. 4 and has similar frustro-conical bearing surfaces [4" and bearings 26" and 21". A rotor 28" is mounted upon each of the shafts 9" and is rotatable thereon. Each of the rotors 28" has teeth 29 and pockets 38", while vents 3|" lead from the radially innermost portions of said pockets to the interior periphery of rotor 28". each of the tubular shafts 9 similar to the slot 33 in Fig. 3.

The modification of my invention shown in Fig. 6 is similar in all respects to that shown in Fig. 5 with the exception that bowl 5" is positively geared to rotors 28" by means of gears 28a carried by each of the rotors 28".

Having thus set forth the fundamental principles upon. which my invention is based and the differentiation between my invention and the prior art, and having described a number of embodiments of my invention withrespect to the diagrammatic representations thereof, a brief description will be given of the manner of operation characteristic of the mechanism claimed herein. It is a matter of common knowledge that a liquid medium within a bowl or casing which is, rotated at .high' speed will rapidly migrate to the inner periphery of such a casing and assume A radial slot 33" is provided in F a vertical position therein, thus presenting a vertical face normal to a line drawn radially between the center of rotation and the periphery of such a casing. Such a liquid when subjected to high speeds of revolutionv will be subjected to high centrifugal force which causes a large increase in the viscous friction thereof and tends to render the liquid extremely compact and dense. In this condition its manner of behavior is more analogous to a semi-fluid or plastic medium than to the liquid state and it becomes very resistant toward any force tending to deform its assumed contour or location with respect to the casing within which it is held. By the interposition of a rotor or rotors as set forth above with the axes of rotation of the said rotors non-coincident with the axis of rotation of the liquid-containing casing, to a point where the teeth of the said rotors as described under Figures 1, 2, 3 and 4 will engage in the said liquid, it is apparent that the rotation of the casing and the liquid contained therein at high speeds will carry the rotor or rotors with them at substantially identical peripheral speeds of travel between casing and rotors. With appropriate design of teeth and pockets and suitable location of the rotors with respect to the casing, all as described above, and with a housing surrounding the said casing for separation thereof from the surrounding environment and for the carrying of the supports for the said rotors and other functioning means, it is evident that the fiuid medium, such as a gas existing with the said housing and also within the said casing, will be supplied to the said pockets at the point where a suitable clearance is provided between rotor and interior liquid wall. As the rotor continues to turn from this position of clearance to apoint where the teeth provided on its periphery engage with the interior vertical liquid surface, the fluid or gaseous contents of the said pockets will become trapped and will be progressively compressed from this point to the point where a clearance between rotor and casing becomes so small that the liquid medium carried within the said casing will completely dis-. place the said contents of the pockets and force the fluid or gaseous medium substantially completely from the said pockets and through the valving means shown and described under Figures l, 2 and 4. Following such complete displacement by the liquid, the teeth will again progressively emerge from the liquid and will be characterized by the presence of a substantially Torricellian vacuum therein, ready for re-filling by the fiuid or gaseous medium present Within the said housing. In this manner my device may function very effectively as a highly efficient vacuum pump or as a compressor with the ability to produce and maintain vacua of a high order when the liquid centrifugally held within the casing is mercury or some other liquid medium of low vapor pressure. It will be very evident to those skilled in the art that the only care necessary is to so adjust the length of teeth, depths of pockets, location of valving or cut-off means, spacing of rotor with respect to the casing, and suitable control of other characteristic features described and specified above, that clearance between rotor and liquid will occur at one point of the rotation and complete filling of the pockets by the said liquid at another point of rotation of the said rotor. That quite large pressures may be developed by such a pumping mechanism rotating at speeds of 1,800 to 3,600 B. P. M. will be evident from a consideration of the centrifugal forces involved in my device. thermore, my invention is capable of an extreme variation of size, it being possible to secure a freeair capacity of 25 to- 30 c. f. m. with a casing diameter of 8", a rotor diameter of 6.5", an overall thickness of rotor 1.5", a quantity of liquid (less than a pint) sufficient to form a radial thickness within the casing of approximately 1" and a speed of 3,600 R. P. M. With diameters of casing and rotor of 20" and 16 respectively and a speed of 3,600 R. P. M., with a thickness of rotor of approximately 2.5", a free-air capacity of 600 c. f. m. may be developed, while greater thicknesses of rotor with substantially the same diameters will increase this free-air capacity to 1,000 c. f. m. or more. When two or more rotors are employed in conjunction with a single casing, their speeds of rotation will be increased with respect to the speed of rotation of the casing in substantially the ratio of the casing diameter to the rotor diameter, and such increased speeds will more than compensate for the reduction in capacity due to their smaller sizes and wastage of space. Likewise, with the rotors distributed around the casing at regular intervals, as described above, a substantially uniform balance of thrust may be maintained upon the casing at all times.

In describing the type of rotor with its associated forms of teeth and pockets to be employed in the practice of my invention, I do not wish to be limited to any specific form of tooth profile. While under certain conditions the so-called teeth may be designed as thin sections or dividing septa, it

may be found desirable to fashion such profiles I in a manner corresponding to the customary generated profiling of gear teeth, or analogous thereto. It is evident that a profile form of tooth may be generated for each specific application and associated conditions wherein the teeth during immersion into or emergence from the peripheral liquid wall will present a surface relative to the face of the said liquid wall in a direction substantially relieving same at the points in question.

While I have described the principles of my I invention and its manner of functioning in detail, and have set forth certain relationships, dimensions and configurations of structural elements in a manner clearly to indicate the manner of functioning thereof, I do not wish to be limited to such elements, dimensions, and/or configurations, it being clearly understood that my representations have been purely diagrammatic and serve only to afford those sln'lled in the art of pump-ing mechanisms and. associated apparatus with sufficient information to reproduce the results of my invention. Furthermore, the term point of tangency has been employed in a purely relative sense, contact between rotor and casing occurring either actually, in the case of direct gearing, or being substantially effected by what I have chosen to term liquid gearing. In all cases the expression point of tangency denotes the point of minimum radial clearance between rotor and casing.

Having thus described the characteristic features of my novel pumping mechanism, I claim:

1. A pump, comprising in combination a stationary casing having an inlet therein, a rotatably mounted driven bowl in said casing having an inlet in the upper side thereof, a fluid in said bowl, a rotor in said driven bowl having a plurality of peripheral pockets therein mounted in eccentric relation with said driven. bowl, a hollow axle upon which said rotor is mounted, the

said rotor having passages from said pockets to the hollow axle, and valves in said passages.

2. A pump comprising, in combination, a stationary casing having an inlet therein, a rotatably mounted horizontally positioned driven bowl in said casing having an opening at one side thereof extending substantially the entire distance around the said bowl, a fluid in said bowl, a rotor in said driven bowl having a plurality of peripheral pockets therein mounted in eccentric relation with said driven bowl, a hollow axle upon which said rotor is mounted, the said rotor having passages from said pockets to the hollow axle, and valves in said passages.

3. A pump comprising, in combination, a stationary casing having an inlet therein, a rotatably mounted horizontally positioned driven bowl in said casing having an opening at one side thereof extending substantially the entire distance around the said bowl, power means for driving said bowl, a fluid in said bowl, a rotor in. said driven bowl having a plurality of peripheral pockets therein mounted in eccentric relation with said driven bowl, a hollow axle upon which 1 said rotor is mounted, the said rotor having passages from said pockets to the hollow axle, and

valves in said passages.

SIDNEY M. HULL.

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