US2747510A

US2747510A - Pump for fluid and semi-fluid materials such as plaster and the like

Info

Publication number: US2747510A
Application number: US266226A
Authority: US
Inventors: Seggern Ernest A Von
Original assignee: SOUNDRIVE PUMP Co
Current assignee: SOUNDRIVE PUMP Co
Priority date: 1952-01-12
Filing date: 1952-01-12
Publication date: 1956-05-29
Anticipated expiration: 1973-05-29

Description

y 1956 E. A. VON SEGGERN 2,747,510

PUMP FOR FLUID AND SEMI-FLUID MATERIALS SUCH AS PLASTER AND THE LIKE 4 Sheets-Sheet 1 Filed Jan. 12, 1952 H INVENTOR.

[RA/Ear A. VON Jeaasezv Jeremy May 29, 1956 E. A. VON SEGGERN PUMP FOR FLUID AND SEMI-FLUID MATERIALS SUCH AS PLASTER AND THE LIKE 4 Sheets-Sheet 2 Filed Jan. 12, 1952 INVENTOR. ERNEsT .14. von 656650 mm. W m

Q U Q y 9, 1956 E. A. VON SEGGERN 2,747,510

PUMP FOR FLUID AND SEMI-FLUID MATERIALS SUCH AS PLASTER AND THE LIKE Filed Jan. 12, 1952 4 Sheets-Sheet 3 INVENTOR. [R/wssr 14. VOIV J's-6662M States Patent 6 PUD/ P FOR FLUID AND SEMI-FLUID MATERIALS SUCH AS PLASTER AND THE LIKE Ernest A. von Seggern, Burbank, Califi, assignor to Soundrive Pump Company, Hollywood, Calif., a corporation of California Application January 12, 1952, Serial No. 266,226

22 Claims. (Cl. 103-44) This invention relates to pumps for pumping liquids, and particularly to pumps for pumping viscous, abrasive materials which solidify with time. It relates specifically to pumps for pumping semi-fluid mixtures of pulverized solids and liquids which do not readily remain mixed in uniform proportions but tend to separate when being pumped or handled. Such mixtures may include several different solid materials in various states of pulveri'zation, in combination with one or more fluids as a vehicle. Examples of such mixtures are interior plaster and external stucco as used in the building trades and similar classes of cements and aggregates in suspension in water.

There are certain physical properties possessed by this class of semi-liquids that make them practicallyimpossible to pump by any known prior art device. The material is: (1) viscous, (2) abrasive, (3) non-homogeneous, (4) compressible, (5) unstable in mixture, (6) self-hardening with time.

It is accordingly a general object of the present invention to provide a pump which will handle fluids or semifluids having the above-named properties singly or in combination.

A further object is to provide a positive displacement pump capable of producing high discharge pressures in which the flow of liquid through the pump is slow and non-turbulent.

Another object is to provide a pump in which all the parts subjected to the abrasive action of the fluid are either made of rubber or rubber coated, or of equivalent flexible or elastic material capable of withstanding abrasion. 7

A further object is to provide a pump having a large compression ratio, that is, a large change'in displacement during the working cycle relative to the volume of the material acted upon.

Another object is to provide a pump in which substantially no pressure gradients or inertia forces are established in the fluid which tend to separate materials having different densities, or different size, or different hardness, or diiferent viscosity.

Another object is to provide a pump having a small and substantially smooth bore therethrough'at all points in which the flow of material is sufliciently fast and uniform so that at no point is the accumulation of static material possible.

A furtherobject is to'provide a pump of the above class which is simple in design, positive in action, and which will'not readily deteriorate or get out of order.

The pump of the invention, in its most elementary form, employs a flexible'tube, fitted with suitable valves at its intake and discharge ends. A means is provided for alternately contracting and expanding the cross-sectional area of this flexible tube, and comprises preferably a means for alternately raising and reducing the pressure on a hydraulic body which is arranged in a pressure transmissive relationship with the outside of the tube. On each pressure rise, the tube contracts, and on each pressure reduction, atmospheric pressure inside the tube causes an expansion. On each such expansion, the fluid or semi-fluid material to be pumped is drawn into the tube through its intake valve, and on each contraction, the material is evacuated through the discharge valve. This unit as thus broadly described provides a conduit of smooth interior, with a minimum of bends, turns, corner's or pockets, so that the pump is self-purging. That is to say, the material to be pumped is all moved along the tube, with a minimum tendency for any of the material to stagnate in corners, pockets, and the like. The unit as thus broadly described also has the feature of high compression ratio, or in other words, high ratio of displacement volume to total volume, with the result that a high ratio of flow rate to volume is achieved, and again, the tendency for stagnation in corners, bends or pockets is minimized. This high compression ratio also makes the pump self-priming.

In a more advanced form of the invention, two or more such pumpunits are used in a series multi-stage arrangement. Here, a longer pump is achieved, with corresponding addition of pumping effort. It will be seen that this multistage series arrangement, if the pumps are worked in unisomwill increase the displacement over the single type unit, without requiring that the multiple units discharge into a header, as is common with multiple cylinder pumps. In other words, the pump capacity is increased, While still keeping a single uniform flow conduit.

In a multiple-stage pump, the pressure per stage, required for unit discharge, can be reduced by synchronizing the successive stages to give what may be referred to as polyphase operation. Here, the contractive and expansive movements of the stages occur with a definite phase diiference. Taking a typical two-phase, system for simple illustration, the flexible tube of the second stage is expanded while the flexible tube of the first stage is contracted, and vice-versa. The stages in this case are seen to operate with 180 phase difference. A threestage pump may be operated with phase difference between stages, and so on. It will be seen that, considering the long flexible conduit running through the successive stages, alternate waves of contraction and expansion travel along the conduit, forcing the fluid or semi-fluid material along in a manner somewhat analogous to the peristaltic wave movement that occurs in the animal intestine.

In a preferred form of such a polyphase pump, a very important further improvement is achieved by designing successive stages to have successively decreasing displacement. The pump as described hereinabove discharges the pumped materialin surges or pulses. This pulsing efiect is very greatly reduced by the feature of successive reductions in displacement in the successive pump stages. For simple illustration, avtwo-stage polyphase pump will be considered, with the two stages operating with phase difference, and with the first stage designed to have double the displacement of the second. For convenience, let it be assumed that the second stage pumps one unit volume on each contraction of its flexible tube, while the first pumps two units of volume on each contraction. On the discharge (contraction) strokeof the first stage, two units of volume are discharged into the second stage. The second stage is then undergoing its intake or expansion stroke, and it fills with one of said unit volumes, while the other passes entirely through the second stage and is discharged therefrom. Then, on the intake stroke of the first stage, the first stage fills again with two unit volumes; while the second stage, then undergoing its contraction or compression stroke, discharges one unit volume. Thus the second stage discharges one unit volume on each of'its strokes, so that discharge is continuous- This discharge, while it may be called continuous, is still, however, possessed ofa Patented May 29, 1956 pulsating character, and a later described accumulator means is preferably employed to give the outflow a nearly uniform flow characteristic.

- Further details, features and accomplishments of the invention will be described or appear in the course of the following detailed description of an illustrative embodimentthereof, reference being had to the accompanying drawings, wherein:

. Figure 1 is a side elevational view of a pump in accord ance with the invention, parts of theexterior casing and framework being broken away;

Figure 2 is an end elevational view, looking from the right of the pump of Figure 1;

Figure 3 is a perspective view of the motive power unit of the pump of Figures 1 and 2;

Figure 4 is a vertical'longitudinal section taken on the line 4-4 of Figure 2;

a Figure 5 is a cross-sectional view taken on line 5-5 of Figure 4; Y

Figure 6 is a section taken on line 6-6 of Figure 4;

Figure 7 is a section taken on line 77 of Figure 4;

Figure 8 is a section taken on line 3-8 of Figure 4;

Figure 9 is a section taken on line 9-9 of Figure 4;

Figure 10 is a section taken on line 10-10 of Figure 4;

Figure 11 is a section similar to a portion of Figure 4 but showing another position in the operating cycle of the pump;

Figure 12 is a diagrammatic view of a three-cycle form of the pump; and

Figure 13 is a diagram of phase relations occurring in the pump of Figure 12.

In Figures 111 of the drawings, a multistage polyphase pump,'in this case a two-stage type, has been shown for illustrative purposes, and comprises in this instance a first stage I, and a second stage II, the first being hopper fed, and the second being arranged in series with the first, so that its intake directly receives the discharge from the first. The two stages are characterized by a long, relatively smooth conduit C extending therethrough, suitably valved, as described hereinafter, and principally made up of serially connected flexible tubes'Tl and T2 for the first and second stages, respectively. Liquid filled chambers C1 and C2, including contractive and expansive diaphragms Dl and D2, surround the two flexible tubes.

T1' and T2, respectively' They afford a simple and presently preferred embodiment of means for alternately increasing and reducing the external pressure on the flexible tubes and thereby alternately contracting and expanding the same to give the novel multistage pumping Further, a single frame by means of angle members 17. p

The illustrative pump is of a two-stag type; though-v as already mentioned, a single stage may be employed, and also additional stages may be provided if desired.

The present pump accordingly includes a first stage or unit I and a second stage or unit II. These pump units have tubular housings, including a rigid stationary and axially

movable housing sections

22 and 23, respectively in the case of stageI, and 24 and 25, respectively in the case of stage II, to house the aforementioned smooth conduit C. The axially

movable sections

23 and 25 are interconnected as later described to move 'in unison.

by the aforementioned sub-frame members 16,'in the manner clearly shown in Figure 6. As there shown, the

members 16 are formed with half-round seats to receive the lower halves of said housing sections, the other halves being supported by half-round straps 26 secured to members 16 as by screws 26a.

The pump includes a hopper 30, flange connected at the bottom, as at 31, to a tubular neck 32 extending upwardly from a tubular housing member 33 connected to the intake end of the aforesaid stationarily mounted housing member 22 of first pump unit I. This housing member 22 has towards its intake end a flared portion 50, to which is joined an outwardly offset box portion 51, terminating in an external flange 52. This flanged end abuts a flange. 53,011 the end of the tubular housing member 33, and the parts are held in assembly by means of bolts 54 passing through flange 53 and through a retainer ring 55 engaging in back of flange 52.

Contained within tubular member 33 is a snugly fitted plug 56, secured in position by a clamp screw 57 mounted in a pivoted frame 58. This plug has a large fluid passage 60 communicating at one end with the passage 61in neck 32., which in turn communicates with hopper'3tl. At its other end, passage 60 communicates with a port 62 in a valve seat ring 63 screwthreadedly joined to the inner end of plug 56. A second ring 64 is screwthreadcdly joined to ring 63, and the tworings cooperate to define a tapered valve seat 65, and also an annular seat for a rubber sealing ring 66 which is partially exposed through tapered seat 65. A valve ball 67 seats against this valve seat and sealing ring, being normally held closed by a spiral spring 68 seated in an annular groove formed within ring 64, as shown. The aforementioned plug 56 is readily removable from the assembly by loosening screw 57 and swinging frame 58 out of the way, and serves as a means for readily removing the valve for inspection or, repair.

A retainer ring 7%) received inside box 51 engages flange 53 and has an inwardly extending annular flange 71 overhanging and engaging the projecting end of valve seat ring 64. Flexible tube T1, preferably composed of rubber or equivalent elastic material, is disposed in a concentric position inside tubular housing member 22, being of a diameter to provide an annular space 73 between said tube and housing member 22. At the lefthand or intake end of the pump unit, an end portion of this rubber tube is clamped and sealed between outer and inner conical clamping and sealing rings 74 and '75, respectively, the former having an end flange 76 screwed into retainer ring 70, and the latter being shaped at its forward or large end to slide snugly inside flange '76. while forming with member 74 a conical channel within which the end portion of the rubber tube is snugly clamped when the two rings have been moved into assembly. 7 a

The righthandor discharge end of rubber tube Tl is clamped and sealed at the righthand end of the afore mentioned axially movable housing member 23 between outer and inner clamping rings 82 and 33, respectively. The outer ring 82 has converging conical surfaces 84 and 85, forming an apex of just slightly less diameter than the outside diameter of rubber tube Tl. The rubber tube T1 is accordingly constricted slightly by engagement with this apex, but its end portion is expanded Slightly, into a conical or flared shape, by being gripped between the conical surface 85 and a parallel conical surface 87 on the inner ring 33. The latter has at its end an external The inside surface of ring 83 converges toward the dis ,The

stationary sections

22 and 24 are rigidly supported A charge end'of the pump, giving a converging discharge passageway 89. The two clamping ringsSZ and 83- are secured in assembly by means of a retainer ring 9t? screwed on'over outside clamping ring 82 and siidable inside the bore of housing member 23. This ring 9!).

has a portion normally projecting from the end of housing member 23, and which is axially positioned by means arrests of a positioning ring 92 threaded thereto and adapted to engage the end of housing member 23. As will be seen, the retainer ring. 96 also has wall portion 93 which engages the ends of both of the clamping. rings to secure them properly in assembly.

The two

housing sections

22 and 23 of the pump are joined by a flexible diaphragm. member D1 comprising in this instance an annulus of generally U or horseshoe shape in section. It resembles, and may actually be, an ordinary rubber tire casing. The inner edges or beads of this tire-like diaphragm engage the two

housing members

22 and 23 near the confronting ends thereof and each edge is clamped between an inner annular check plate 96, shaped to conform to its inner periphery, and screwthreadedly mounted on the end of the corresponding housing tube, and a pair of outer clamping rings 97 and 98 shaped to conform to its outer periphery, the former being screwthreaded to the outside of the latter. The clamping rings 98 are slidabl-y mounted on the tubular housing members, and are set up by means of rings 99 threaded onto the housing members. The clamping ring 97 is capable of adjustment relative tothe ring 98', and is set up or locked by means of locking ring 100 screwed onto ring 98.

The right hand end or extremity 80 of housing part 23 is enlarged and of square cross section, and secured to this extremity 86 is a hollow block unit 105' serving both as a means for interconnecting: and reciprocating the movable housing members 23' and 25, and also as a housing containing an intake check valve for the sec ond pump unit 21. This unit 105 includes 'a square frame 106 which abuts squared extremity 80 of housing section 23, and surrounds the positioning ring 92. As shown in Figure 8, the unit 105 also includes' two ver-- tical side plates 107 whose edges abut the edges of frame 106. As shown in Figure 4 it also includesa plate or frame 168 which engages the opposite edges of side plates 107, and also abuts the squared extremity 140 of second stage movable housing section 25. The members 106, 107' and 168 will be seen to form a box, open at top and bottom, and the inside surface of plate 108 is slanted to provide a tapered seat for a complementary tapered valve body 110'. The latter has a fl'uid passageway 111 controlled by check valve ball 112. The ball 112 is provided with seat ring 113 (Figure 7) screwed into the front face of plug 110, and seats on saidring and on a rubber sealring 114 lodged in a recess formed between said seat ring and the adjacent surface of'memher 110*. The opening of seat ring 113 aligns with the opening in retainer ring 90 and also with the end of discharge passageway 89 of pump unit- 20. Beyond seat ring 113, fluid passageway 111- has a diverging section 120, and then a converging section 121, the end of the latter aligning with port 122 in wall 108 (Figure 7). Spring'124 for valve ball 112 is lodged in a seat formed at the apex of the fluid passageway through plug 1'10, as clearly shown.

The valve body 110 is secured in position by means of a bar 130 secured to its upper edge, and hold-down screws 131 threaded into side plates 107 (Figure 8), the screws 131. having intermediate flanges 132 received in notches formed in the two ends of the bar 130,, all as clearly shown in Figure 8. it will be seen that operation of the screws- 131 serves either to secure the valve body tightly in position in its box, or to force the valve body upwardly there from. The latter operation is of advantage in that the valve body may otherwise tend to become tightly wedged in place after a period of use.

Long screws 141 extend through the flanges afforded by the squared extremities 80' and 140' of the movable housing sections 23 and 25' of the first and second pump stages, passing through the square ring 106,.the side plates 107, and the wall 108, thus tying said members together in rigid assembly.

Flexible tube T2, preferably rubber, or the equivalent, is disposed in a concentric position inside the

housing sections

24 and 25 of pump unit II, an annular space 146 being provided between said tube and the housing members 24 and- 25. At the lefthand or intake end of the second pump unit, anend portion of the tube is clamped and sealed between outer and inner conical clamping rings 147' and 148,. which are generally like the corresponding clamping rings 74 and at the intake end of the first pump unit.

Clamping ring 147 is received snugly inside the end portion of housing member 25, its extremity beingscrewthreaded for engagement inside a retainer ring 149 seated inside the end of housing member 140, said retainer ring having an. inwardly extending annular flange abutting the end of clamping ring 147 and engaging an external anular flange 150 formed around the exterior of clamping. ring 143, the flange 150 seating inside the conical surface of ring 147, as shown. Theendportion of the rubber tube is thus clamped tightly and sealed between the adjacent conical surfaces of the two clamping

rings

147 and 148, and the ring 148 has a fluid passage 152 which is flush at one end with the port 122 and at the other with the interior surface of the tube T2.

At theopposite end, the' rubber tube T2 is clampedand sealed between outer and inner clamping rings and'1'61, respectively, the former having conical surfaces 162- and- 163- form-ing an apex of just slightly less diam eter than the normal outside diameter of sleeve 145. The rubber tube T2 is accordingly constricted slightly by engagement with thisapex, but its end portion is expanded slightly, into a conical or flared shape, by being gripped between the conical surface 163 and a conical surface onthe outside of inner clamping ring 161. The latter has at its end an external annular flange 165 which seats inside the conical surface 163 of the outer ring, leaving a conical channel of proper dimensions to tightly grip' the end portion of the rubber tube. A discharge fitting flange-connected to the discharge end of housing member 24 has a fluid passage which is flush with the fluid passage through clamping ring 161 and this fitting 170 includes an internally threaded boss 171 adapted for coupling to a suitable delivery pipe or hose, not shown. The two clamping rings 1'69 and 161 are secured in assembly with one another by means of a retainer ring 172' screwed on over outsideclamping. ring 160 and slidable inside the bore of housing member 24, this retainer ring 172 including an internal annular flange 173 at its rearward endwhich engages behind the flange 165 to secure the parts in assembly; A positioning ring 175 screwed onto the end of retainer ring 172 and received between a counterbore sunk into' the end of housing member 24 and an annular channel formed in fitting 1 70 secures the clamping

ring assembly

160, 161 rigidly to the discharge end of the pump.

The two

housing sections

24 and 25 of second pump unit II are joined by flexible diaphragm D2, similar tothe diaphragm D1 of the firstd'escribed pump unit, and again comprising, in this instance, an annulus of generally U or horseshoe shape in section, resembling an ordinary rubber tire casing, which in practice it may actually be. The inner edges or beads of this tire-like diaphragm engage the two housing members 24 and 25' near the confronting ends thereof and each is confined between a retainer ring 181 screwed onto the end of the corresponding pump and housing member, and a clamping ring 182 slidable on the housing member and set up by a retainer ring 183 screwthreaded onto the housing member, as at 184. Attention is at this time called to the fact that the flexible diaphragm D2 is internally supported by rings 181 having. outside diameters substantially less than the outside diameters of the corresponding plates or rings- 96 which clamp the insides of the flexible diaphragm D1 of the first pump unit-. In practice, the area included within the outside periph- 7 7 cries of rings 181 is made to be approximately half the area included within the outside peripheries of rings 96, giving the second pump unit half the effective displacement of the first unit.

As a preferred but optional feature, the flexible diaphragm D2 is spring-clamped between two dished clamping rings 199, which rings are connected for movement toward and from one another by means of long bolts 191, compression springs 192 being placed on the bolts at one end, in a manner to, urge the two clamping plates 190 toward one another, and so tend to compress the diaphragm. This device functions to smooth out ripples in the delivery rate from the pump, in a manner to be explained hereinafter.

The pump is provided with sheet metal side walls 193 rising from frame 10, the forward edges of which are connected to triangular front plates 194 which follow the contour of the aforementioned hopper 30 and may be welded or otherwise secured thereto. Rising from opposite edges of frame 10 are channel members 195,

which join with the rearward edges of side walls 193, and a horizontal rock shaft 196 extending between and pivotally mounted on said channels 195 carries a supporting frame 197 for electric drive motor M. In the present embodiment, the machine has been provided with an air compressor, driven by the same electric motor M that powers the pump, such air compressor being used to provide a source of compressed air for use in spraying or delivering the plaster or other material pumped by the pump of the invention. Such air compressor has been shown at A, mounted on the same framework 197 that carries the electric motor, and belt Connected to said motor as indicated at 198. It is to be understood, however, that this air compressor forms no part of the present invention and has only been illustrated as it forms a part of the present embodiment of the invention.

The shaft of motor M has a known type of springactuated variable diameter V-pulley 200, connected by belt 201 to a pulley 292 which drives reduction gear unit 203. Rocking movement of motor M and its shaft accomplished by adjustment of rock shaft 196 shifts the belt running on the pulley 200 either toward or away from the axis of the motor shaft, thereby varying the effective diameter of the pulley, and hence the speed of drive, in a manner well known and unnecessary to illustrate herein. Such rocking adjustment of shaft 196 is accomplished through an arm tightly mounted on the rock shaft, to which is connected, by a ball and socket joint 205, the end of an adjustment shaft 206 which is screwthreadcd in a bracket member 287 secured to the hopper 39, the shaft 2G6 having a manually operating crank 209 on its end. Operation of this crank then moves the shaft 206 in an axial direction, and so swings arm 294, rock shaft 196, and therefore the motor M, thereby effecting variation in the speed of drive of the pump.

The power take-oft" shaft from reduction gear unit 203 carries crank 210, connected by connecting rod 211 to one arm 212 of a bell crank 213. This bell crank includes a shaft or axle 214, pivotally mounted to sub frame 14, and provided with a pair of upwardly extending arms 216 which are pivotally connected at their upper ends to trunnions 217 extending oppositely from the side plates 107 of the aforementioned central drive unit 105. Operation of drive motor 41 thus results in oscillation of bell crank 213, whose upwardly reaching arms 216 oscillate the member 195 rigidly connected between the two ends of the two pump units in a direction axially of the pumps. The fact that the driving connections between the bell crank arms 216 and the drive unit 105 travel in an are about the axis of the bell crank, is of no significance since the entire central section of the pump, between the two flexible diaphragms D1 and D2, is flexibly mounted and can move a short 8 distance up and down along with its axial translation without any difiiculty whatsoever.

In the operation of the pump, therefore, the pump drive unit reciprocates in a direction axially of tubes T1 and T2, carrying with it the two movable housing sections 80 and of the two pump units. It will be seen that in this operation, the portions of chambers C1 and C2 defined by the diaphragms D1 and D2 are alternately compressed and expanded, it being noted that when one diaphragm chamber is compressed the other is expanded, and vice versa. The stroke of the reciprocating parts is made such that the inner clamping members 96, in the case of diaphragm D1, and 181, in the case of diaphragm D2, do not quite engage one another at the extreme limit of compression.

At the time of assembly of the pump, the chambers Cl. and C2, within the diaphragms D1 and D2 and the tubular pump housings, outside of the rubber tubes T1 and T2, are entirely filled with-a suitable liquid, such as water. This is easiest accomplished by submerging the tubular housing sections, such as 22 and 23, together with the interconnecting diaphragm, in water, the rubber tube and its end mountings being removed. To fill the diaphragm, a flexible tube can be inserted, and with its end reaching to the high point of the diaphragm, suction applied to the tube will remove the air and permit complete filling. With the housing still submerged, the rubber tube, together with its end mountings, is inserted from the lefthand end of the housing, and the retainer ring 92 screwed in place. Suitable seals are provided, as indicated in the drawings, so that the assembly can then be removed from the water in which it has been submerged, and the',water, will then not leak from the chamber C1. A similar and entirely evident operation is employed to fill the chamber C2 of the second stage.

The change in volume. of the space inside each diaphragm, due to the alternate compression and expansion as described hereinabove, is transmitted to the rubber tube by the water enclosed within the diaphragm and in the space surrounding the tube. For instance when the movement of the driven end 23 of the pumping unit I is toward its fixed end 22, the volume of the diaphragm space D1 decreases, and the rubber tube T1 is compressed radially by the water while its length is being shortened by the movement of the driven end. Both effects reduce the volume of the space inside the rubber tube T1. Conversely, when the movement of the driven end of the pumping unit is from its fixed end, the volume of the diaphragm unit is increased, and the rubber tube is expandcd and at the same time elongated. Both actions increase the volume of the space inside the rubber tube. It is seen that when the volume of the space inside the tube T1 increases, fluid material in hopper 30 is drawn in through the inwardly opening check valve 67, while the valve 112 is held closed, and conversely, when the volume of the space in the tube T1 decreases, the fluid material in the tube is forced out through the outwardly opening check valve 112, while the intake valve 67 is closed.

' Since the driven ends of the two pumping units I and II are joined together, they are each subject to the same longitudinal displacement or stroke. However, the two pumping units are preferably so designed that the volume displacement of the first unit I is substantially twice that of the second unit II. In the present embodiment, this result has been accomplished by making the effective piston area of the diaphragm D1 substantially twice that of the effective piston area of the diaphragm D2, as has already been explained. It should be apparent, in this regard, that the effective piston area depends almost entirely upon the diameter of the rigid internal diaphragmclamping and bracing rings, 96 in the case of diaphragm D1 and 181 in the case of diaphragm D2, the actual effective area being slightly greater than the area of the rigid clamp rings. By making the former of substantially twice the area of the latter, the diaphragm D1 has subsesame stantially twice the piston area or volumetric displacement as the diaphragm D2. Pump I, thus provided with twice the volumetric displacement of pump 11, pumps. substantially twice the volume of fluid as pump II on each stroke. It may be said that the action. of the diaphragm D1 is to pump two unit volumes of fluid on each stroke, as compared with one unit volume for the diaphragm D2. In operation, the first pump unit I, on its expansion stroke, will therefore fill itself with two units of volume of fluid from the hopper 30 while the pump unit ll is discharging one unit of volume of fiuid through its discharge outlet. Conversely, while pump I is discharging two units of volume of fluid into the pump ll durin its compression. stroke, pump II is filling itself with one unit of volume of fluid,.while the remaining one unit of volume is discharged from the discharge outlet. In this way, the pump assembly is made double acting, that is, one unit of volume of fluid is discharged from the system during the forward stroke and another during the return stroke. therefore discharges continuously.

The discharge rate tends to vary from minimum to maximum and then back to minimum during each stroke of the pump. The delivery rate from the pump is made much more uniform by the use of the spring-actuated clamping members 190 engaged with the diaphragm D2 of the second pump unit. The operation of the spring clamping means acting on the second diaphragm in smoothing out ripples in the discharge fromthe pump will now be considered. At the outset, or in neutral position (Figure I the diaphragm D2 is slightly flattened owing to the pressure exerted by springs 182 through plates 190. As the center section then moves toward the left, the two-unit volume which is exhausted by pump unit I on each leftward stroke is delivered into pump unit II. One unit volume is delivered from pump unit II, and the other unit volume fills in the expanded space owing to the expasion of. diaphragm DZ. At the mid-point of this stroke, the diaphragm D2 is partially expanded owing to separation of the adjacent ends of housing members 23' and 140', and in addition, the pumping pressure then existing inside the diaphragm D2 is suflicient that said diaphragm has become somewhat further expanded against the springactuated clamping plates. This extra expansion is subtractive from the peak fluid delivery from the pump unit I'l. Then, at the end of the leftward stroke, as pump pressure and flow from pump unit 1 tends to fall to its minimum, the spring-actuated clampingv plates 190 close in on' diaphragm D2, and delivery from the pump unit II is thus kept up by the resulting volume reduction. of diaphragm D2. Correspondingly, on the rightward stroke, the diaphragm is somewhat expanded against springs 182 in passing through the mid-portion of the stroke, subtracting from the flow rate, and somewhat contracted by the springs at the end of the stroke, thus tending to keep the flow up when it otherwise tends to slow or stop- The spring-actuated clamp on the diaphragm D2 thus causes the diaphragm to function as an accumulator, or filter, smoothing out ripples inthe' flow from the pump by cutting down the flow at the peaks and adding: to the flow at the depressions.

The pumping system as described in the foregoing is of a two stage, two cycle type, the two stages being phased 180 apart. As explained, this system discharges on each stroke, but the discharge is of a pulsating character. The pulsations are somewhat smoothed and reduced by use of the spring clamping device employed on the diaphragm member of the second stage, but the pulsating character of the discharge is still in evidence. Improvement in this regard is possible by addition of further stages, properly phased, and in- Figures 12 and 13 I have diagrammatically indicated a three phase version of pump in accordance with the invention, the three stages of the pump operating with 120 phase difference.

The pump diagrammed in Figure 12 will be understood as capable of physical embodiment in structures The pumping system as thus described invention.

similar to those explained. and illustrated hereinabove', as. will be understood by those skilled in the art. As only diagrammatically indicated in. Figure 12, therefore, the pump in this instance has three

successive stages

200, 201. and 202., wherein. is defined a long continuous conduit made up flexible, elastic tubes 203', 204' and 205', respectively. A. housingv for the first stage comprises

housing parts

206 and 207, connected by flexible diaphragmv 208,. and insimilar manner, second stage housing comprises parts 209 and 210', connected by diaphragm 21.1, while the third stage housing comprises parts 212' and 213' connected by diaphragm 214'. The housing parts as described will. be understood to be connected in the above-described manner to the ends of the flexible tubes, and the adjacent ends of the housing members of successive stages. will be understood as connecting to one another, as in the embodiment previously described. An intake valve 215 is employed at the intake end of first. stage tube 203, and exhaust valve 216' is placed at the discharge end of tube 203, this valve 216 being seen to discharge into the intake end of second stage tube 204. At the discharge end of tube 204 is an exhaust valve 217', whose discharge is received by the. intake end of tube 205- of third stage 202'.

Liquid chambers 218" are formed in the successive stages inside the housing sections and. diaphragm and aroundthe outsides of. the successive flexible tubes, as will be understood- The pumping system. as thus described is driven at two 0 points, first, at the junction of the first stage unit with the second, and second, at the junction of the second stage unit with the third. I have here indicated a suitable driving means merely in a simple diagrammatic form, from which those skilled in the art will. readily understand. the As diagrammatically indicated, therefore, I. may employ, at each driving point, a slotted bar 225', projecting. laterally from. the interconnectedhousing portions, and receiving. a crank pin 226" carried by a crank disc 227', the two crank. discs being synchronized or interconnected with one another, as indicated conventionally by the dashed. line 228. To accomplish the desired phase relations, the second driving. point is driven with 60 phase lagwith respect to thefirst. That is to say, and assuming for illustrative purposes that both crank discs are rotating in a clockwise direction, the crank pin which corresponds to the driving point between. the'second and third pump stages has. a. phase lag of 60 with respect to the crank. pin. corresponding to the driving point between the first and second stages, as clearly illustrated in Figure 12. It will become evident. as the description proceeds that the actual directions of rotation of the cranks are immaterial, so long as the second crank pin has a 60 lag with respect to the first.

Figure 1-2. shows. the pump with the first stage fully contracted, the second. stage partially contracted, and the third stage partially expanded, and for purposes of description, this will be taken. as the beginning or 0 position of the cycle. Figure 13 shows, in diagram, the positions of the three pump stages at 60 intervals throughout a full 360 cycle. From an. inspection of this figure, and a comparison thereof with Figure 12,. it will. readily be apparent that the three stages 200', 201" and202' are all gradually expanded and then contracted, but with 120 of phase difference between successive stages.

As in the first-described. embodiment, the successive: stages are preferably provided with decreasing volumetric displacements, in the ratio of 3:2:1. That is to say, the diaphragm of first stage 200" is designed to pump three units of volume on each contraction, the diaphragm of stage 201 is designed to pump two units of volume on each contraction, and the diaphragm of stage 202' is designed to pump one unit of volume on each contraction. Accordingly, during each contraction of stage 209, three units of volume are pumped into stage 201', and on each contraction of stage 201', two units of volume are pumpedthereby in'tostage 202-, while on each contraction of stage 202', one unit of volume is discharged therefrom. It will be evident that, as with the first-described embodiment, the

stages

201 and 202, on their expansion strokes, are incapable of retaining all of the material taken in, and the excess is therefore discharged during the expansion stroke. In a three phase system such as diagrammed in Figures 12 and 13, this results in continuous discharge from the exhaust end of the third stage. There is of course still superimposed on this continuous discharge a certain degree of ripple, but not sufllcicnt to be objectionable under ordinary circumstances. Further improvement, of course, would result from use of further stages in a multi-phase system, but it is believed that a three phase system is adequate for all practical purposes. Also, of course, spring clamping means employed on the second and third diaphragms, like the device 182 of the first embodiment, may be employed, if desired, and will function as an accumulator to further remove ripples from the outflow. Such a device is indicated onthe third diaphragm in Figure 12, at 214.

The pumping of viscous, non-homogeneous semi-fluids such as plaster and stucco presents peculiar problems not found in the pumping of ordinary liquids. The tendency of the mixture to separate and harden and form lumps in the pump and in the piping can lead to either stoppage of pumping, or destruction of the pump. Since the material sets with time like cement, it is evident that if at any point in the pump or piping a stagnant pocket is formed, the material which first fills the pocket will remain and eventually harden. Such deposits have a marked tendency to grow larger or break loose as they impede the flow of material, and they may eventually cut off the flow entirely or, if they form in or pass into that portion of the pump which undergoes volume change, they may cause.

signed to have a small and substantially uniform cross section throughout its lengh with a minimum of turns so that flow of material through the pump is substantially equivalent to the flow in a straight pipe. If the cross section is small enough relative to the volume of material pumped, a positive forward flow will exist at all times at all points in the pump and no accumulation of material is possible. Thus, by continuous and complete purging of the system of all old material with freshly prepared mixture, the tendency to harden in the pump is avoided.

Hardening and formation of lumps is also associated with the problem of separation. Practically all plasters and stuccos are a three phase system of fluid (usually water), binder (usually gypsum or cement), and an aggregate (usually sand or one of several types of less dense material such as vermiculite). Such mixtures are purely mechanical and are unstable in the sense that an uneven distribution of the materials is readily produced by the action of inertia forces, pressure gradients, or simple straining. These forces are effective because of differences in density and viscosity of the material, and differences in size of the solid particles.

When separation occurs between the liquid and the solid material, the latter is no longer in a fluid state and packs into lumps and prevents further operation of the pump. A similar difiiculty takes place if the coarser aggregates are separated from the more finely powdered cement or hinder. This is particularly true when the aggregate is ordinary sand, which. is much denser than the other components of the mixture. Aside from the inability of the pump to function when separation of the material takes place, the usefulness of the material as a plaster or stucco is greatly impaired thereby and it becomes useless if separation is at all pronounced.

. It is accordingly necessary to avoid the establishment of large inertia forces or pressure gradients in the material, which enhance separation. The present pump isdesigned to operate at a low speed (typically R. P. M.) which permits the material to flow slowly and smoothly into and through the pump. It has a large volume displacement relative to its own internal volume which makes possible the combination of large pumping rate with low operating speed and small internal volume. V

This latter combination is of the utmost importance. Since most plasters and similar material are quite volume compressible due principally to the inclusion of air, the necessity for a large volume change relative to the internal volume, or in other words, a high compression ratio, is apparent in order to maintain a large volume flow against relatively high back pressure. In actual practice, the pressure change through the pump is of the order of one hundred pounds per square inch, while the volumetric etficiency, due to compressibility of the material, may be as low as fifty per cent.

There are, then, a number of major features which a successful plaster pump should have. It should be self purging. It should pump the fluid with a smooth, quiet flow. It should have a large compression ratio. And it should be self priming. Combined with these are also the ability to withstand abrasion, and a means for obtaining a positive displacement in the pump without having critical clearances. The present pump has been shown to fully meet these various requirements.

It will be understood that the drawings and description are for illustrative purposes only, and that various changes in design, structure and arrangement may be made without departing from the spirit and scope of the appended claims.

I claim:

1. In a pump, the combination of: a flexible tube, an intake valve in communication with one end of said tube, an exhaust valve in communication with the other end of said tube, another flexible tube having one end in communication with said exhaust valve of said first-mentioned tube, chamber means for each of said tubes for enclosing a hydraulic liquid body therearound, liquid displacing means for each of said liquid bodies for accomplishing successive expansion and contraction of the tubes, the liquid displacing means for the liquid body around said firstmentioned tube having a greater volumetric liquid displacement perstroke than the liquid displacing means for the liquid body around the second-mentioned tube, and means for actuating the liquid displacing means for the two tubes with a phase difference such that the expansion period for the second tube overlaps a substantial portion of the contraction period for the first tube, all in such manner that the liquid displacing means of larger volumetric displacement pumps .material from the first tube both into and through the second tube during the period of overlapping first tube contraction and second tube expansion.

2. A pump according to claim 1, wherein the phase difference between the liquid displacing means is substantially 3. The pump of claim 1 wherein at least one of said chambers comprises liquid body accumulator means to smoothen ripples in the pump discharge. I

4. A pump according to claim 1, wherein the liquid displacing means for the first liquid body has substantially twice the volumetric liquid displacement as the liquid displacing means for the second liquid body.

5. A pump according the claim 4, wherein the phase difference between the liquid displacing means is substantially 180.

6. In a pump, the combination of: a flexible tube, an intake valve in communication with an intake end of said tube, an exhaust valve in communication with an exhaust end of said tube, another flexible tube, said second-mentioned tube having an intake end communicating with 3 said exhaust valve of said first-mentioned tube, chamber.

means for each of said tubes for enclosing a liquid body therearound, and a contracting and expanding means for each of said tubes having operative connection with opposite ends of the tube and operable to move said ends toward and from one another to alternately longitudinally expand said tube and permit it to longitudinally contract, said contracting and expanding means including. also liquid displacing means for elevating and-reducing the hydraulic pressure on the liquid body surrounding the associated tube in step with movement of said tube ends toward and from one another.

7. The pump of claim 6, wherein the contracting and expanding means for the tubes are interconnected to operate with a substantial phase difference.

8. The pump of claim 6, wherein the contracting and expanding means for the twotubes are interconnected to operate with a phase difference of 180 9'. The pump of claim 6, wherein the liquid displacing means for the liquid body surrounding the first tube has a substantially greater volumetric displacement than the liquid displacing means for the liquid body surrounding the second tube.

10. The pump of claim 6-, wherein the liquid displacing means for the liquid body surrounding the first tube has substantially double the volumetric displacement of the liquid displacing means for the liquid body surrounding the second tube.

11. The pump of claim 9, wherein. the liquid displacing. means for the liquid body surrounding the first tube has substantially double the volumetric displacement of the liquid displacing means for the liquid body surrounding the second tube.

12. In a pump, the combination of: a flexible tube,

clamping and sealing means at both ends of said tube for clamping said tube and sealing therearound at both its ends, an intake valve communicating with one end of said tube, an exhaust valve communicating with the opposite end of said tube, a longitudinally expansive and contractive housing surrounding said tube and joining said clamping and sealing means at the two ends of the tube, there being a space to be filled by a liquid body inside said housing and around the outside of said tube, and means for alternately longitudinally contracting and expanding said housing, whereby to alternately contract said tube in a longitudinal direction and simultaneously contract the same laterally by external liquid pressure compression, and elongate said tube longitudinally and simultaneously allow it to expand laterally by reduction of the external liquid pressure.

13. in a pump, the combination of: a tube made of flexible material impervious to the fluid being pumped; an inlet valve in communication with one end of said tube and an outlet valve in communication with the other end of said tube; a housing enclosing the outer side walls of said flexible tube, said housing including a diaphragm; a relatively incompressible fluid completely filling the space between the outer walls of said tube and the inner walls of said housing and said diaphragm; and means for alternately applying and releasing pressure to said diaphragm whereby a hydraulic pressure is transmitted by said fluid to the outer walls of said flexible tube and said tube is alternately compressed and expanded and its internal volume is alternately decreased and increased thereby and the fluid to be pumped is drawn in through said inlet valve and discharged from said outlet valve.

14. In a pump, the combination of: a tube made of flexible material impervious to the fluid being pumped; an inlet valve at one end of said tube and a discharge valve at the other end of said tube; a housing enclosing the outer side walls of said elastic tube, said housing being attached to the ends of said tube and including a diaphragm which is movable in a line parallel to the length axis of said tube and which produces a change in the volume enclosed by said diaphragm and housing when moved along said line; a relatively incompressible fluid completely filling 14 the space between the housing and the outer walls of the said tube; means for moving said valves relative to'each other in a reciprocating motion in a line parallel to the length axis of said tube whereby said tube is alternately stretched and relaxed and simultaneously said diaphragm associated with said housing. is moved to alternately change the volume enclosed by said housing and the outer walls of said tube, whereby the tube is subjected to hydraulic pressure when said tube is relaxed, and said hydraulic pressure is released when said tube is stretched, causing the internal volume of said tube to be alternately increased and decreased due both to elongation and expanding and by relaxing and compressing, and fluid is.

caused to flow into said tube through said inlet valve and to be discharged through. said outlet valve because of the alternating volume change in said tube.

15. In a pump, the combination of: a flexible tube, clamping and sealing means at bothends of said tubefor clamping said tube and sealing therearound at'both its ends, an intake valve communicating with. one end of relatively moving said housing parts toward and from one another along said axis.

16. The subject matter of claim 15, wherein said diaphragm is substantially U-shaped in cross section, with its two top portions connected to the two housing parts.

17. In a pump, the combination of: first and second flexible tubes, clamping and sealing means at both ends of each of said tubes for clamping said tubes and sealing therearound at both ends thereof, an intake valve communicating with an intake end of said first tube, an exhaust valve communicating With the opposite end of said first tube, an intake end of said second tube connected to reccive the discharge from said exhaust valve, 21 housing structure around each of said tubes comprising two housing parts movable toward and from one another along the axis of the associated tube, said housing parts being sealingly joined and operatively connected to the clamping and sealing means at the two ends of the associated tube, flexible diaphragms joining the two parts of each of said housing structures and functioning therewith to form expansive and contractive liquid chambers around said flexible tubes, and driving means for moving the two housing parts of said housing structures alternately toward and from one another.

18. The subject matter of claim 17, wherein said driving means is arranged to move the two housing parts of one housing structure toward one another while moving the two housing parts of the other apart, and vice versa, whereby to accomplish oppositely phased expansion and contraction of the two liquid chambers.

19. The subject matter of claim 18, wherein the eifective liquid displacing area of the diaphragm associated with the first tube is substantially twice that of the diaphragm associated with the second tube.

20. In a pump, the combination of: first and second axially aligned flexible tubes, said tubes each having an intake end and a discharge end, the tubes being arranged with the discharge end of the first tube adjacent the intake end of the second tube, connecting means operatively interconnecting the discharge end of the first tube with the intake end of the second tube, an intake valve at the intake end of the first tube, a discharge valve at the discharge end of the first tube, said discharge valve arranged to discharge into the intake end of the second tube, housing means for each of the tubes 'including two separate housing parts, one connected and sealed to each end of the respective tube, means stationarily mounting the housing parts connected to the intake end of the first tube and the discharge end of the second tube, the remaining housing parts being joined to said connecting means, a flexible diaphragm connecting the two housing parts of each of said housing means, so as to form therewith a liquid chamber surrounding the tube, and driving means operatively connected with said connecting means for reciprocating said connecting means and the housing parts joined thereto along the axis of the tubes, in such manner that said diaphragms and liquid chambers are expanded and contracted in opposite phase.

21. The subject matter of claim 20, wherein the effective liquid displacing area of the diaphragm associated with the first tube is substantially twice that of the diaphragm associated with the second tube. V

22. In a pump, the combination of three axially aligned flexible tubes connected end to end in a series arrangement, a two-part tubular housing means for each tube and a flexible diaphragm for each housing connecting said two parts thereof for relative movement toward and from one another along the axis of the tubes, one part of each such housing means being connected to one end of the associated tube and the other to the other end of said tube, the housing parts corresponding with confronting ends of successive tubes being interconnected with one another for corresponding movement,v and the remaining housing parts, corresponding with therintake end of the first tube and the discharge end of the third tube, being stationarily mounted, said housing means and diaphragms forming liquid chambers surrounding the tubes, an intake valve opening to the intake end of the first tube, said valve being connected to the stationarily mounted housing part for the first tube, a valve at the juncture of the first and second tubes connected to the interconnected housing parts of the first and second tubes and serving as a discharge valve for the first tube and an intake valve for the second tube, a valve at the juncture of the second and third tubes connected to the interconnected housing parts of the second and third tubes and serving as a discharge valve for the second tube and as an intake valve for the third tube, and driving means operatively connected with the interconnected housing parts of the first and second tubes and with the interconnected housing parts of the second and third tubes for reciprocating said interconnected housing parts along the axis of said tubes, with said interconnected housing parts of the second and third tubes lagging the interconnected housing parts of the first and second tubes by a phase angle of substantially References Cited in the file of this patent UNITED STATES PATENTS 2,046,491 Scott July 7, 1936 2,291,912 Meyers Aug. 4, 1942 2,626,569 Knudson Jan. 27, 1953 FOREIGN PATENTS 287,267 Great Britain Mar. 22, 1928 641,453 France Apr. 16, 1928