US2777394A - Pump for viscous fluids - Google Patents

Description

Jan. '15, 1957 J. MODROVSKY ET AL PUMP FOR VISCOUS mums 3 Sheets-Sheet 1 Filed Oct. 27. 1954 INVENTORS I ATTORNEYx Jan. 15, 1957 J. MODROVSKY ET AL 2,777,394

PUMP FOR vxscous FLUIDS Filed Oct. 27, 1954 5 Sheets-Sheet 2 I INVENTORS 4 5 2 27 W W v L aflb Q.

ATTO R N EYS 1957 J. MODROVSKY ET AL 2,777,394

PUMP FOR VISCOUS FLUIDS 3 Sheets-Sheet 5 60 INVENTORS BY 61711110114- m Filed Oct. 27, 1954 PUMP FORVISCOUS FLUIDS Joseph Modrovsky, River Edge, N. L, and: Walter A.

Sherwood, Hempstead,.N. Y., assignors'to 'llhe Farmingdale Corporation, Farmingdale, N. Y., a-corporation of New York Application October 27, 1 954, Serial"N0.,465,078 13 Claims. (Cl. 103-84) This invention relates to a pump for viscous fluids characterizedby the ability to deliver quantities of fluid at high pressures.

An object of the invention is ,to utilize, the shear-resistance of the fluid as a major causational factor in'creating a pressure condition.

Another object is to provide such a pump including a rotor and a stator, in'which therotor cannot-be stalled by any load. p

A furtherv object is to provide a, pump inwhich the rotor may be a plaincylindrical or frusto-conical body rotating on its axis.

A still further object is to provide a pump which has no valves, is completely reversible, can be operated at high speeds, is corrosion resistant and is-silent.

Another object is to provide certain improvements'in the form, construction and arrangement of the: parts, whereby the above-named'and other objects may effectively be attained.

Practical embodiments of the invention are represented in the accompanying drawings, in which:

Fig. 1 represents a vertical section onthe axis/of the pump with cylindrical rotor, the fluid supply and utilization elements being shown diagrammatically;

Fig. 2 represents a section on theline IIII of Fig. 1, looking in the direction of the arrows;

Fig. 3 represents a section on the line II--III of Fig. 1, looking in the direction of the arrows;

Fig. 4 represents a section'on the line IV--IV of Fig. 1, looking in the direction of=the arrows;

Fig. 5 represents, in perspective, a detail segment of one corner of the pump chamber, ,parts being cut away;

Fig. 6' represents a vertical sectiononthe, axis ofthe modified form of'pump in which the rotor isfrusto-conic, the fluid supply and utilization elements being shown diagrammatically, as in-Fig'. 1;

Fig. 7 represents a section 'on-the'line VII-VII of Fig. 6, looking in the direction of the arrows;

Fig. '8'represents a sectionon the-line VIII'-VIII of Fig. 6, looking in the direction ofthe arrows, and

Fig. 9 represents a section on the line lX---IX' of Fig; 6, looking in the direction of the arrows.

Referring to the drawings, and particularly Figs. 'lto 5 thereof, the pump is shown as comprising a cylinder block formedby upper and lowercomplementary halves 1, 2, having a cylindrical bore- 3 formed therein. The bore -3-is tightly closed atone end ofthe hea'd 4, while the opposite end-is closed by the head Sinwhich is journaled the rotor drive shaft 6; ashaft seal isindicated 'at7 and the shaft is surrounded, between the seal and' the interior of the cylinder, by an annular'recess Scon'stitutirlg a spill-way. The shaft is connected in a suitable manner to a source of power, indicated generally as the motor M.

The cylinder wall is providedwithradially extended slots 9, 10 along opposite sidesand in an axial plane, and the cylinder wall is beveled slightly (asindicated at 11, 11, 12, 12) adjacent its intersection with the ,saidslots and throughout ,a distance terminating shortofthecylnited States Patent 0 2,777,394 Patented Jan. 15, 1957 'inder ends (see Fig. 5). A rotor 13, in the form. of a plaincylindrical body is mounted on the drive shaft 61and has a diameter giving it approximately a free fit in the cylinder and a length such. that the end clearance, between the rotor and the heads 4 and 5, is as'smallasapossible without appreciable friction.

Each slot 9, 10 is occupied by a doctor blade or'vane 14, 15, respectively, preferably of metallic or nonametallic anti-friction material andshaped to bear lightlyagainst the surface of the rotor along narrow, diametrically opposite, zones extending the full length of the cylinder. The blades 14, 15 may be urged into engagement withthe rotor by means of springs '16, 17 alone or in combination with hydraulic means describedbelow.

Fluid inletconduits are shown in Fig. 2, the supply system-including a reservoir 18 (Fig. 1), a main inlet pipe ;19

' and conduits120, 21 drilled in the cylinder bloclcto conduct fluid, respectively, to beveled -zones ll and 12. Assuming the rotation of the rotor to be in the .direction indicated, said zones are on the downstream sides of the doctor blades. The fluid outlet system, shown in Fig. 3 is approximately theconverse of the inlet system, comprising conduits 22,23, disposed soas to conduct the fluid from the beveled'zones 11' and.12', respectively, to the outletpipe 24, whence the fluid under pressure. passes to any desired utilization apparatus, represented by the. cylinder and piston 25 .in Fig, 1. It will be noted thatthe zones 11' and 12' are on the upstream sides of the respective doctor blades.

Since itis reasonablefor the doctor blades to be urged against the rotor withaforce roughly proportional to the fluid pressure beingdeveloped in the pump, small additional conduits 26, 27 are provided to draw off fluid from points intermediate .the blades (in the circumferential.di-. rection) and to feed such fluid-into the slots 9, 10, in back of the respective blades. As shown, each such tap.- ofi is located. midway. between the blades, but other lo cations-may be adopted if desired.

'In operatiomthe reservoir 18 is provided with a quanof flowing, through the supply system 19, 20, 21 to the beveled zones 11, 12. in. the cylinder. Therotor is rotated, in the direction ofthearrows (Figs. 2, 3 and 4),.and the fluid in the zones 11, 12 is carried by the. moving surface of'the rotor in the direction of rotation thereof. The beveled zones 11' and 12 become filled with fluid almost instantly, as the fluid ismovedtoward them and because the circumferential flow is completely stoppedxby the blades 14,15. As .soon .as the said zones are. filled, the continuing. effort ,offluid entrained by the rotor and -en-: gaged therewith through its inherent viscosity, to follow themovement of the rotorsurface results in abuilding up. of pressures insaid .zones. The fluid under pressure is adapted to be-drawn off through the conduits 22, 23 and pipe 24, for utilizationlas may be desired. The pressure build-up extends back from the pressure zones a sufiicient distanceso that fluid under some pressure will pass throughthe conduits 26, 27 and will, as the pres: sure increases, hold the doctor blades more and more firmly against the. rotor surface, supplementing or even supplantingthe action:of springs 16, 17.

The presence of fluid inthe clearance at the ends of they rotoris unimportant except as it may thus asssit inlubricatingthe parts; Any such fluidwhich may leak out of, the, cylinder along the drive: shaft is collected in. the spillway recess 8 and mayreadily be returned, at low pressure, to the reservoir 18 through a pipe 28 (Fig, l). Endwise leakage canbe minimized, particularly whenhighpressure operation is contemplated, by the provision of end. seals of any type which will notadd' an. undesirablefriction factor; inFig. 1 such sealsare shown as ,being .piston rings 29 seated .in grooves 130. v,

The values of pressures developed by this pump are affected by several factors, including viscosity of the fluid, compatability of the fluid with the surfaces of the cylinder and the rotor, minimum clearance between said surfaces, and surface speed of the rotor. The pressure will reach a maximum for any given set of factors, and will be maintained at that maximum, so long as the rate of delivery through the outlet system remains less than the rate at which the fluid is capable of being fed to the pressure zones. Control of the delivery can be exercised by means of a valve of any customary type (not shown) on the outlet pipe 24. It will be apparent that the pump cannot be stalled, even when such a valve is closed completely, and that the pump can be driven at a constant rate and under substantially constant load to deliver fluid constantly or intermittently in quantities and at pressures within the predetermined limits.

The pump here shown and described has two doctor blades and two diametrically opposed pressure zones connected in parallel to the supply and delivery systems. The forces acting on the rotor surfaces are symmetrical, so that tendencies toward eccentricity are minimized. If one of the doctor blades and the adjacent beveled zones of the cylinder are eliminated it will be found that higher pressures with lower delivery rate can be obtained while the rotor is subjected to unbalanced radial forces originating in the single pressure zone. On the other hand, any plurality of doctor blades and pressure zones, uniformly spaced around the rotor, will constitute a balanced system; as the number is increased the possible maximum pressure becomes less and the rate of delivery becomes greater. The pump is fully reversible; upon rotating the rotor in the opposite direction the functions of the input and output systems are interchanged, with reverse opereation in the same manner and with the same efliciency.

In the modified form of pump shown in Figs. 6 to 9 the cylinder block is formed by upper and lower complementary halves 31, 32, having a frusto-conic chamber 33 formed therein. The chamber is closed at its larger end by the head 34 and the smaller end is closed by the head 35 in which is journaled the rotor drive shaft 36. A conventional shaft seal is indicated at 37, and there is formed around the shaft, between the seal and the interior of the cylinder, an annular recess 38. The shaft is intended to be driven, as before, by a motor M.

The chamber wall is radially slotted at 39, 40 along diametrically opposite lines and in an axial plane, and the chamber wall is preferably beveled slightly, at 41, 41, 42, 42, adjacent its intersection with said slots and for a distance terminating short of the ends of the chamber, comparable to the arrangement of which a detail is shown in Fig. 5. In this modification the rotor 43, mounted on the drive shaft 36, is frusto-conic in form, and preferably tapers slightly less steeply than the walls of the chamber (at least throughout a distance corresponding to the axial length of the beveled zones 41, 41', 42, 42'), the diameter of the small end of the rotor being no less than the diameter of the chamber at its smaller end and the length of the rotor being sufficiently less than the length of the chamber to provide a substantial clearance at either or both ends, depending upon the axial position of the rotor in the chamber. The larger end of the rotor is provided with a central bore 44 in which is fitted a movable ball or plug 45 urged outwardly by the spring 46 so as to bear against the head 34. The rotor is capable of slight motion in the axial direction, resulting in variation in the clearance between the frusto-conic surfaces of the rotor and stator, and the parts 45, 46 are designed to urge the rotor in the direction of reduced clearance.

Each slot 39, 40 is occupied by a doctor blade or vane 47, 48 respectively, preferably of metallic or non-metallic anti-friction material and shaped to bear lightly against the surface of the rotor along narrow, diametrically opposite, zones extending the full length of the chamber. The blades 47, 48 may be urged into engagement with the rotor by means of springs 49, 50 alone or in combination with hydraulic means as in the case of the blades 14, 15.

Fluid inlet conduits are shown in Fig. 7, the supply system including a reservoir 51 (Fig. 6), a main inlet pipe 52 and conduits 53, 54 drilled in the block to conduit fluid, respectively, to beveled zones 41 and 42. Assuming the rotation of the rotor to be in the direction indicated, said zones are on the downstream sides of the doctor blades. The fluid outlet system, shown in Fig. 8 is approximately the converse of the inlet system, comprising conduits 55, 56, disposed so as to conduct the fluid from the beveled zones 41' and 42, respectively, to the outlet pipe 57 whence the fluid under pressure passes to any desired utilization apparatus, represented by the cylinder and piston 58 in Fig. 6. It will be noted that the zones 41' and 42' are on the upstream sides of the respective doctor blades.

Small additional conduits 59, 60 (Fig. 9) are provided to draw ofi fluid from points intermediate the blades (in the circumferential direction) and to feed such fluid into the slots 39, 40, in back of the respective blades, in order to supplement (or supplant) the action of springs 49, 50.

In addition to (or instead of) the spring 46 and plug 45, it may be desirable to provide a spring 61 hearing against the head 35 and, through a thrust bearing 62, against a stop 63 on the drive shaft 36. Means for adjusting the degree to which this spring is compressed may be provided, for instance, by making the stop 63 in the form of a nut threaded on the drive shaft. The pipe 64- connects the chamber 38 with the reservoir 51, serving the same function'as the pipe 28 in Fig. 1.

The operation of this form of the pump is basically the same as described above in connection with the pump of Figs. 1 to 5. The tapering form of the rotor and chamber do, however, introduce certain additional considerations. Since the pressure developed in the field rcsponds to the law:

P pAV and VocN (Dia) .'.to obtain constant pressure along the rotor (i. e., from end to end of the beveled zones 41, 42), taking D1=large end diameter, and Dz=small end diameter, then h 1Z2 D2 h2 so that the rotor surface should taper less steeply than the stator chamber surface, as previously stated, providing increased clearance toward the large end, in order that the pressure may be developed approximately uniformly along the rotor.

The axial component of fluid pressure tends to move the rotor in the direction of increased clearance, this force being counterbalanced to a predetermined extent by the force of the springs 46 and/or 61. Since an increase of fluid pressure can cause axial movement of the rotor, it is evident that the arrangement shown tends to produce fluid pressure which is automatically stabilized at approximately a constant value. If adjustability is not required, the spring 61 and its associated parts may be omitted, leaving to the spring 46 the entire function of counterbalancing the axial pressure component. On the other hand, when the spring 61 is present the elements 44, 55 and 46 may be omitted, for instance, in pumps of certain sizes or for certain purposes.

As with the first shown form of pump, the tapering rotor pump may be made with more than two doctor blades or with only one, and is fully reversible. Except as noted, the two forms of the pump are subject to substantially the same remarks and exhibit comparable advantages.

It is known that certain surface treatments have the effect of varying the compatability or bond between fluids, such as oils, and solid surfaces. Aside from physical roughening or smoothing of a surface the presence or absence of certain greases is a factor, or film-forming materials such as the Swiss product called Aretol can be used-said product having the effect of preventing the spreading of oil film, i. e., being oleophobic. The synthetic plastic known as Teflon (Du Pont) has a similar effect. In general, greater pressures, volumes and efficiencics are obtained in a pump wherein the rotor surface has greater compatability for the fluid (oil) than has the stator surface.

In the pumps shown, the shear resistance and fluid wedge effect are utilized at their highest etficiency, in that the doctor blades constitute positive stops for the entrained fluid. If desired, the rotor of Figs. 69 may be mounted on a drive shaft at its larger end, requiring only obvious modifications in the spring or springs. Although the structure is described herein as a pump, it has been found that the operation is reversible; that is, the device can be operated as a motor by supplying fluid under pressure and thus causing the rotor to rotate.

What We claim is:

1. A pump for viscous fluids comprising, a fixed member having a surface the radial sections of which are circular, a rotatable member having a complementary surface also circular in section, concentric and interfitting with said first named surface with a clearance therebetween, at least one radially floating elongated axially disposed abutment slidably mounted in said fixed member, means acting to urge said abutment resiliently and continuously against the surface of said movable member along at least a major part of a generatrix of said surface, means for rotating the rotatable member, means for conducting fluid from a source of supply to the said clearance at a point downstream from each said abutment considered circumferentially with respect to the direction of rotation of the rotatable member, and means for withdrawing the fluid under pressure from a point adjacent to, and upstream from, each said abutment.

2. A pump according to claim 1 in which there are a plurality of abutments.

3. A pump according to claim 1 in which said surfaces are cylindrical.

4. A pump according to claim 3 in which the cylindrical surface of the fixed member defines a chamber within which the rotatable member is contained.

5. A pump according to claim 1 in which said surfaces are frusto-conic.

6. A pump according to claim 5 in which the frustoconic surface of the fixed member defines a chamber within which the rotatable member is contained,

7. A pump for viscous fluids comprising, a fixed member provided with a cylindrical chamber, cylinder heads closing both ends of said chamber, a drive shaft journaled in one of said cylinder heads on the axis of said chamber, a cylindrical rotor having its surface concentric and interfitting with the surface of the chamber with a clearance therebetween and being mounted on the drive shaft, at least one radially movable doctor blade mounted in a slot extending axially along the chamber wall for a substantial distance, means urging said blade toward said rotor surfce, means for conducting fluid from a source of supply to the said clearance at a point downstream from each said doctor blade and means for withdrawing fluid under pressure from a point adjacent to, and upstream from, each said doctor blade.

8. A pump according to claim 7 in which the bladeurging means includes a fluid circuit so disposed as to conduct pressure fluid from a point in the clearance spaced from any doctor blade to the slot in which a doctor blade is mounted.

9. A pump for viscous fluids comprising, a fixed member provided with a frusto-conic chamber, cylinder heads closing both ends of said chamber, a drive shaft journaled in one of said cylinder heads on the axis of said chamber, a frusto-conic rotor having its surface concentric and interfitting with the surface of the chamber with a clearance therebetween and being mounted on the drive shaft, at least one radially movable doctor blade mounted in a slot extending axially along the chamber wall for a substantial distance, means urging said blade toward said rotor surface, means for conducting fluid from a source of supply to the said clearance at a point downstream from each said doctor blade and means for withdrawing fluid under pressure from a point adjacent to, and upstream from, each said doctor blade.

10. A pump according to claim 9 in which the bladeurging means includes a fluid circuit so disposed as to conduct pressure fluid from a point in the clearance spaced from any doctor blade to the slot in which a doctor blade is mounted.

11. A pump according to claim 9 in which the rotor surface is less steeply tapered than the chamber surface.

12. A pump according to claim 9 in which the rotor is axially movable and which includes means urging the rotor in the direction of closer engagement with the chamber surface.

13. A pump according to claim 12 in which the rotor surface is less steeply tapered than the chamber surface.

References Cited in the file of this patent UNITED STATES PATENTS 658,364 Hancock Sept. 25, 1900 2,373,457 Chisholm Apr. 10, 1945 FOREIGN PATENTS 402,961 Italy Mar. 31, 1943

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