US3212447A

US3212447A - Pumps

Info

Publication number: US3212447A
Application number: US232366A
Authority: US
Inventors: Lindsay H Browne
Original assignee: Delaval Turbine California Inc
Current assignee: IMO Industries Inc; Delaval Turbine California Inc
Priority date: 1962-10-23
Filing date: 1962-10-23
Publication date: 1965-10-19
Anticipated expiration: 1982-10-19

Description

Oct. 19, 1965 1.. H. BROWNE 3,212,447

PUMPS Filed Oct. 23, 1962 3 Sheets-Sheet 2 INVE LINDSAY H. BROWNE ATTO EYS Oct. 19, 1965 1.. H. BROWNE 3,212,447

PUMPS Filed Oct. 23, 1962 3 Sheets-Sheet 3 INVENTOR.

LINDSAY H. BROWNE ATTCRNEYS United States Patent 3,212,441 PUMPS Lindsay H. Browne, Weston, Conn., assignor to De Laval Turbine Inc., Trenton, NJ a corporation of Delaware Filed Oct. 23, 1962, Ser. No. 232,366 Claims. (Cl. 103-152) This invention relates to pumps, and has particular reference to the pulsating type of pump in which an operating liquid is completely isolated from the liquid being pumped. Pumps of this general type are disclosed in my prior Patents Nos. 2,836,121, 2,869,468, 3,048,114 and 3,080,821, issued, respectively, May 27, 1958, January 20, 1959, August 7, 1962 and March 12, 1963. The present pump involves various features and mechanisms of the pumps disclosed in said patents, and reference may be made thereto for certain details.

The present invention relates particularly to pumps of this type which are of large capacity, though the invention is applicable to smaller pumps as well, the pumps being used to handle material such as heavy slurries, sludges, chemicals, particularly those of dangerous types, or sterile products. Pumps of this type operate on a hydraulic exchange principle wherein pressure energy is transferred from a driving medium such as oil to the hydraulic product by means of a pulsator element constituting a diaphragm or membrane separating the driving medium from the product. Pumps of the pulsator type have Wide application in industry because of their ability to develop extremely high pressures, notwithstanding the fact that the liquid being pumped may contain corrosive, abrasive, sterile or solid material. As discussed particularly in the first mentioned Patent 2,836,121, a pair of pulsators may be operated so that when supplied with a continuous flow of driving liquid they will provide a substantially continuous flow of the liquid being pumped. That patent also is concerned with minimizing the only deviation from precise continuity of flow, namely the occurrence of short transient pulses, which actually are more in the nature of sound waves than measurable deviations of flow rate.

In Patent 3,048,114, the pulsators are in the form of fairly large and heavy rubber tubes or thimbles. These pulsators and others shown in the first three of said prior patents are formed about perforated tubes into which oil, the driving liquid, is pumped under pressure to expand the pulsators, thereby forcing the hydraulic product out of the pumping chamber provided at the outside of the pulsators. Upon cessation of a pulse of hydraulic pressure within the pulsator, it relies solely upon its own elasticity to restore it to collapsed position, and also to return the driving liquid therein to the reservoir. Furthermore, depending upon the operating conditions of the pump, and the head at the pump inlet, the pulsator may be called upon to pull a vacuum in the pumping chamber thereby placing further reliance upon inherent elasticity of the pulsator to return it to collapsed position. From this it will be apparent that proper operation of the pump is highly dependent upon its pulsators, the failure of which will render the pump totally inoperative. While the pumps just mentioned have been highly successful in their various applications, they do have limitations when of large size and when extremely high operating pressures are involved. The cost of satisfactory pulsators increases disproportionately with size. Since the inherent elasticity of the pulsator is dependent upon for proper operation, including return of driving liquid to its reservoir, it follows that the thickness, strength and weight of a large pulsator must be great. One of the situations particularly involved is that of rubber extrusion. Under ideal operating conditions, the pressure gradient across the pulsator is always a minor fraction of the pressure head when high 3,212,447 Patented Oct. 19, 1965 pressures are, as usual, involved. Thus, theoretically, forgetting other factors, the pulsator might be infinitesimally thin. However, the ideal conditions may be seriously destroyed, even transiently, with resulting complete destruction of the pulsator. Most serious is the delayed closing of the outlet check valve for the pumped product at the end of a pressure pulse. Such delayed closing will result in the application of the full head pumped against on the outside of a pulsator when the oil within it is at the loW pressure of the reservoir by reason of the opening of the release valve therefor. The pulsator will be pressed upon the perforated interior core under the action of this discharge pressure, and extrusion of the pulsator material through the perforations will occur. Despite heavy wall thicknesses of the pulsators, as pressures pumped against rise higher in practice, they exceed the resistance to extrusion of even the heaviest pulsators.

Thick walled pulsators are further required solely to provide, in large size pumps, the restoration against an exterior vacuum as already indicated. Even in the case of pulsators which will operate under reasonably high discharge pressures, the heavy wall thicknesses involved, in the pulsating action, internal work within the materials of the pulsators to such an extent as to generate heat and otherwise damage the rubber or similar material, particularly since sufficiently thick walled pulsators cannot be practically made homogeneous but must be built up of concentric plies which tend to move relatively to each each other, disrupting such bonding as may have been used. Considering costs and down times for replacements, these heavy pulsators have not been completely satisfactory from an economical standpoint, despite the great advantages of this type of pump in its ability to handle problem liquids under unusual conditions.

In the last mentioned of the above patents, a departure from generally cylindrical pulsators is involved, in that the pulsators are formed of what, in practice, are actually truck tires. The operating flexing actions involved are of a far less destructive nature, bending rather than elastic tensioning operations being involved. Because of accompanying design characteristics, damage by high pressure gradients across a pulsator is minimized, to the end that the extrusion problem is avoided. Because of the nature of the pulsator, furthermore, its material cannot effect, by elastic action, the production of an intake suction, and restoration to collapsed condition is otherwise achieved.

However, pumps of this last type are rather limited in the volumetric displacement producible per stroke.

The foregoing discussion provides a background for examination of the greatly improved pump characteristics provided in accordance with the invention. While these will be better appreciated from the detailed description hereafter, the advantages are particularly gained by the use of novel pulsators which may be briefly described as follows:

The pulsators proper are cylindrical tubes of a rubber suitable for the materials being handled, usually being desirably of synthetic rubber. These tubes are relatively thin walled. The thin walls become permissible because, under any possible potentially damaging conditions they are pressed against close fitting cylindrical metal tube devoid of any irregularities or perforations into which extrusion could be possible. Wall thickness for avoidance of extrusion is thus completely unnecessary. The operation of the pulsator involves substantially solely its elongation in an axial direction. Rubbers are particularly resistant to damage when distortions imparted to them are of this type. Restoration to collapsed condition is produced mechanically and/or hydraulically but completely independently of any action of the material of the pulsator. As will become more evident hereafter, despite the thin walled pulsator structure it is prevented from distorting otherwise than as desired by sheathing it with a coil of wire or other mate-rial highly resistant to radial outward deformation. This coil has no, or negligible, spring action. Furthermore, in operation, it has no abrasive action on the exterior of the pulsator. As a result of the foregoing, pumps in accordance with the invention may be used to exert pressures far above the practical pressures achievable by previous pumps of this type.

The foregoing indicates generally the objectives achieved by the present invention. These and other objects of the invention, particularly relating to details of construction and operation, will become apparent from the following description, read in conjunction with the accompanying drawings, in which:

FIGURE 1 is a vertical sectional view through a pair of pulsators of a pump provided in accordance with the invention;

FIGURE 2 is a view, partly in vertical section and partly diagrammatic of the pump and associated parts involved in control of operation; and

FIGURE 3 is a sectional view of a control valve assembly and associated parts.

The construction of the pulsators and their associated parts constituting the major aspects of novelty, such construction will be first described with particular reference to FIGURE 1. In this figure the left-hand pulsator is shown in its collapsed condition while the right-hand pulsator is shown in its extended condition. Structurally the two are identical, and the description may be followed by reference to either.

Each pump chamber comprises a heavy generally cylindrical housing 2 suitable for the pressures involved and closed at its lower end except for the port 4 for the illflow and outflow of pumped liquid which port communicates with a manifold 6 associated with inlet and outlet check valves as will appear hereafter. The chamber is closed at its upper end by a cap 8 provided with a passage 10 communicating with a pipe fitting indicated at 12 for the inflow and outflow of driving oil. The cap is secured by bolts to clamp between it and the wall of the chamber the flanged support 14 for the pulsator, there being provided packing by means of suitable O-rings. Also secured by this arrangement, though without necessity for packing, is a flange 16 of a cylindrical tube 18 which terminates in a radial face 20.

In the lower end of the cylinder 18 there is secured a spider 22 which supports centrally a sleeve 24 serving to guide for reciprocatory movement a rod 26 surmounted by a collar 28 against which there bears the upper end of a compression spring 30 seated at its lower end on the spider. The guide sleeve 24 also serves to keep the spring 30 in central position. As will appear, in many instances, the spring 30 alone may suffice to provide upward movement of the rod 26 and its associated parts; but in the present instance the upper end of the rod 26 is shown as pivoted at 32 to a piston rod 34, the connections of which will be more fully described later.

Secured against upward movement relative to the rod 26 by a snap ring 42 there is a cup-shaped piston and clamping element 36 having the annular upturned flange 38 which terminates in the radial surface 40 having, at least externally, the same diameter as the lower edge 26 of the cylinder -18, and adapted to abut tightly against it (as shown in the left-hand pulsator assembly) so as to present externally in conjunction with the cylinder a smooth unbroken cylindrical surface. An O-ring packing 44 is provided to prevent any flow of liquid between the rod 26 and the cup 36.

A clamping plate 46 surrounds the lower end portion of the rod 26 and a nut 47 threaded on the lower end of this rod provides clamping of the lower end of the pulsator 48, desirably of a synthetic rubber, this pulsator being in the form of a cylinder having a radial bottom 52 surrounding the rod 26 and clamped thereto by the arrangement just described. The upper end of the pulsator is bonded at St) to a depending portion of the element 14, this serving as the mounting for its upper end.

The cylindrical portion of the pulsator 48 has, when it is in its collapsed position, an internal diameter which may be only very slightly larger than the external diameter of the cylinder 18 and the flange 38 of the cup member 36. Desirably, however, there is a slight clearance so that the pulsator never actually grips, due to its own elasticity, the exterior of the cylinder 18.

It will now be seen that between the pulsator and its assembly and the interior of the chamber walls there is a pumping space 54 which is varied in volume during operation. This has an annular extension as indicated at 56 between the cylindrical outer surface of the pulsator and the cylindrical inner wall of the chamber. This annular extension may be small radially since, as will appear, it has little volumetric change during operation.

The annular space just mentioned is vented at 58 for the initial removal of air and the further removal of accumulated air or gas, the vent being valved and closed during operation.

Located within the annular space 56 and surrounding the pulsator there is a wire or other coil 60. This may be first considered in the relation which it exhibits to the pulsator when the pulsator is collapsed as illustrated at the left in FIGURE 1. It is to be particularly stressed that the wire coil 60 is not a spring and has negligible spring action. It is so formed as to closely embrace the outer surface of the pulsator but without the exercise of any appreciable pressure thereon. In the condition now being described, its convolutions desirably abut each other though they may have slight clearance. The coil may be anchored against turning at its lower end as indicated at 62 and at its upper end as at 63 by the provision of downwardly and upwardly deflected ends entering openings in the plate 46 and in anchoring ring 14. But these anchorings are merely for positional stability: they do not imply the presence of torsion. Its upper end, in fact, may or may not be anchored at all, anchorage being rather immaterial. In the condition illustrated the coil is completely relaxed, with no tendency to contract or expand nor to exert any torque. In fact, its characteristics may be best indicated by pointing out that it may be very satisfactorily replaced by a nylon or similar cord or rope merely wound around the outside of the pulsator, such a cord or rope, of course, requiring securing at both its upper and lower ends.

The purpose and nature of operationof the coil 60 may be best understood by considering at this point the operation of a pulsator to the extent of matters so far described. As will appear, oil is introduced to the space within the tube 18 through the passage 10. Considering the initial situation represented in the left-hand pulsator of FIGURE 1, the spring 30 acts on the cup 36 through the rod 26 so as to close the region interiorly of the cylinder 18. In this initial condition the pulsator 48 is substantially in contact with the outside of the cylinder 18 and the outside of the flange 38 of the cup, though without exerting any substantial pressure thereon. It may, in fact, have slight clearance therewith. At the same time the coil 60 has its convolutions actually or substantially abutting each other as illustrated and the convolutions are in substantial engagement with the pulsator throughout its cylindrical exterior but without exerting any substantial compression thereon. Desirably there is a small average clearance at this time, with the relaxed coil merely leaning against the pulsator. It will be noted that the coil now presents to the pulsator What is essentially an internally grooved surface, the grooves being shallow and having a pitch corresponding to that of the convolutions of the coil.

In this rest position the pulsator may be slightl ten sioned between its upper anchorage and its lower clamped portion, but desirably this tension is slight and is not depended upon to pull the cup 36 upwardly, this condition of the cup being effected to a major extent by the action of the spring 30. In other words the pulsator is in a substantially slack condition.

As entry of the oil takes place, the pressure acting on the cup 36 will overcome the force of the spring 30 and the cup will move downwardly, the pulsator being extended lengthwise.

As the lengthwise extension of the pulsator takes place, its wall thickness will contract. This contraction will open an annular clearance between it and the cylinder 18 into which, initially, a film of oil will enter. As this action occurs the coil 60 will open up so that there will now be applied to the interior of the pulsator the pressure existing within the cylinder 18 while there will be ap plied to its exterior the pressure existing in the chamber 54 by way of its annular extension 56. It will be noted that because of the opening of the convolutions of the coil this pressure is applied directly to the pulsator and not to the convolutions of the coil, so that these convolutions are not pressed against the pulsator by the external pressure. It should be noted that the contact which exists between the pulsator and the coil is essentially at a helical ilne. A slight differential pressure corresponding to the elasticity of the pulsator will cause the pulsator to expand outwardly into contact with the coil, but if initial conditions were as described, this outward movement of the pulsator is only very slight, having solely the effect of increasing to a slight extent the annular clearance between the pulsator and the cylinder 18.

However, the coil 60 now has its major effect: its convolutions are placed in tension by the radial expansion of the pulsator, and being of substantially unyielding material if of metal, or having only a small capability of yielding in tension if of a material such as nylon cord or rope, it effectively provides a rigid limitation to the outward expansion of the pulsator. While the convolutions of the coil open up, and thus provide a helical space into which the pulsator might (theoretically) be extruded, the pressure gradient across the pulsator is never sufficient to provide any substantial extruding action, since the pressure exterior to the pulsator is, by even slight movement, brought essentially to the interior pressure, the gradient corresponding only to the slight elasticity of the pulsator material, and, if anything, the rubber of the pulsator merely hugs a quite small arc of each crosssection of the coil.

The coil has another eifect which is worth'noting. It might seem at first glance that possibly the pulsator could expand more at one portion of its length than another by enlarging the convolutions locally at the expense of robbing portions of the coil turns elsewhere. But this cannot occur because even slight friction at the contact of the coil convolutions with the pulsator will prevent any relative circumferential movement even if the coil is of such a pliant material as nylon. The result accordingly is that with the convolutions originally outlining a bounding cylinder, the boundary always remains essentially a cylinder of uniform diameter. The pressure gradient across all parts of the pulsator is also uniform because of the exposure of its internal and external surfaces to the pressure in the respective inner and outer chambers. The result, accordingly, is a distorting action on the pulsator which is almost completely by way of axial elongation, with no appreciable radial distortion, this being only to the slight extent already noted.

In this axial elongation, furthermore, there is no relative movement in an axial direction between the interior of the coil and the exterior of the pulsator. As any point on the exterior of the pulsator moves axially, the adjacent convolution moves correspondingly axially: both the pulsator and coil being free of contact with fixed surfaces throughout their axial lengths, the displacements of both at any level are proportional to the spacing of that level from their upper ends.

Looked at another way, the increase in pitch of the helix of the coil increases at the same rate as the increase in length of the pulsator. Thus no frictional forces involving work are set up. This, it may be noted, is in sharp contrast with what would occur in an attempt to reinforce the pulsator by molding a wire helix in its body. While on elongation, the helix and body as a whole would elongate simultaneously, from a three-dimensional standpoint there would be a tendency toward relative movement in View of the fact that the rubber in elongating must contract transverse and diiferential distortions in the transverse direction must therefore occur. Also, as a wire helix is extended there is a twist component imparted to its convolutions. This latter arrangement would, accordingly, involve internal frictional work :between the coil convolutions and the enclosing rubber, leading to heating and a strong tendency towards separation of internal surfaces. Such internal relative movements and resulting stresses are characteristic of a nonhomogeneous assembly of two materials with different elastic properties.

The right hand pulsator unit in FIGURE 1 illustrates the condition attained at the end of a pumping stroke. Here the assembly at the lower end of the pulsator closely approaches the bottom of the casing. At this point it may be particularly noted that the minimum Volumetric clearance may be quite small. This clearance, percentagewise of the initial volume is considerably smaller than that which can be attained in the case of the pulsator arrangements of the patents referred to above.

In the case of normal operation, an action essentially the reverse of what has been described takes place in the suction stroke. The interior of the cylinder 18 is put in communication with the oil reservoir, and the spring 30 (aided through the operating means for the rod 34, if this is used) restores the parts to the relaxed conditions shown at the left of FIGURE 1, providing suction of the pumped material from its supply. Free flow through the spider 22 takes place.

However, an abnormal condition may occur due to the failure of the delivery valve to close or to close promptly. In such case at the instant of communication of the interior of cylinder 18 with the oil reservoir there would exist a very large pressure gradient from the exterior to the interior of the pulsator. However, there is a dynamic action in that any movement of the

assembly

36, 46 in the closing direction relieves the external pressure until reverse fiow through the delivery valve can again increase it. The restoring action of spring 30 can well keep pace with the rate of pressure build up with movement, so that, and also because there is some resistance to outflow of oil, the portion of the pulsator 48 between the

edges

20 and 40 will not appreciably move inwardly. Stated in other words, the rapidity of upward movement of the lower part of the pulsator and its associated parts is so rapid that, due to resistances to flow, no pressure gradient can be built up until after the edge 40 engages the edge 20. After this occurs the interior of the cylinder 18 may be at atmospheric pressure, approximately, but the exterior pressure may well be several thousand pounds per square inch. The effect of this however, can now merely be to force the pulsator against the smooth cylindrical wall presented to it because of the smooth fit of the

edges

20 and 40 against each other. The oil film which exists between the exterior of cylinder 18 and the interior of the pulsator cushions the pulsator against being slapped against the cylinder, this oil being able to escape only slowly through the imperfect fit between the

surfaces

20 and 40. While this last fit may not be leak-proof, nevertheless, the fit of these flat edges is easily made such that no extrusion of rubber into the clearance will occur even under extreme pressure gradient conditions. This situation is in sharp contrast with that involved when the inner liner of a pulsator is perforated, even the smallest perforations which permit adequate flow being so large that extrusion can occur under high pressures even with heavy walled pulsators. Considering the conditions just mentioned, it is obvious that the results are achieved even if the pulsator wall is quite thin. A substantial thickness of the pulsator wall is desirable only to the extent of making it reasonably resistant to wear, although it will be evident from the foregoing description that wear conditions are almost totally absent, there being no possibility of unlubricated relative sliding movements.

The only other abnormal condition which might possibly arise would be in a :pumping stroke in case the bottom of the pulsator was arrested (for example by binding of the rod 26 or parts connected to it) and oil continued to flow inwardly under high pressure to the cylinder 18, or if because of an inlet valve defect, too much oil entered the pulsator and it was driven to a mechanically arrested position for example .by contact of head 28 with the upper end of a guide tube 24. Both of these situations represent highly improbable malfunctions. In such case the pulsator might be pressed outwardly tightly against the coil 60. However, even though this coil Was lengthwise expanded, the convolutions would still be so close together that extrusion between them would be considerably resisted unless the abnormal conditions were extensive. As will shortly appear, however, :provision is desirably made against the remote possibility of an overstroke condition.

From an opera-ting standpoint, it is evident that the useful action of the pulsator is essentially only at its lower end. The length of the pulsator in rest condition must be chosen so that the elongation is an acceptable percentage of its total length, and therefore there must be a considerable length of the pulsator as established by the length of the cylinder 18. An elongation of the order of 25% of the relaxed length of the pulsator is quite permissible with rubber type material normally usable.

As has already been indicated, the present invention relates primarily to the pulsators, and their associated parts, already described. The operating system for the pulsator is conventional and, in fact, may take various forms. However, to indicate more fully the pump as a whole, reference may now be made to FIGURES 2 and 3 which show the major operating parts corresponding to the disclosures of Patents 2,836,121 and 3,080,821. Reference may be made to these patents for details of construction and operation, there being disclosed herein only what is required for a general understanding of the pump and its operation.

Each header 6 is associated with inlet and outlet check valves, 66 and 68, respectively, controlling flow of the pumped liquid from a supply and to a delivery conduit 70 in conventional fashion.

The oil inlet fitting 12 of each unit is shown as associated with an assembly including a cylinder 74 within which there reciprocates a piston 72 carried by the rod 34 previously mentioned. The lower end of the cylinder 74 is in communication through a pipe 76 and fitting 78 with the oil space of an accumulator 80 in which a diaphragm 82 separates this oil space from a space 84 containing a gas under pressure. The particular pressure here used will, in general, depend upon the working pressure of the pump, but is such that, aided by the spring 30, it will collapse the pulsator against whatever suction conditions may exist. At the same time it will permit the piston 72 to be pulled down under the action of the driving oil in the working stroke of the pulsator. When this occurs the oil will be driven out of the cylinder 74 and returned to the accumulator or to other parts of the system connected therewith. The upper end of the cylinder 74 is connected through pipe 86 to a return outlet to the oil supply reservoir to take care of oil which may be driven past the piston. To maintain the accumulator in working condition, there is provided a pressure switch 90 responsive to its internal pressure which controls operation of a motor 92 driving a pump 94 which supplies makeup oil from a supply 96 through check valve 98 to the accumulator. Accordingly, if the pressure in the accumulator drops, due to oil leakage, oil is resupplied thereto to build up pressure in the usual fashion. T 0 limit the pressure there may be provided a relief valve 100 through which oil may also be returned to the supply. The lines 76 and 86' correspond to the

lines

76 and 86 but run to the companion pulsator assembly.

Driving oil is supplied under high pressure, and desirably continuously, from a motor driven pump 102 through a conduit 104 to the space 106 between the piston elements 110 and 112 of a spool valve 108 which reciprocates in a cylinder 109. Ports 114 and 116 control the inflow of driving oil to the passages 118 and 120 controlled by check valves 122 and 124 and communicating with the

passages

126 and 128 respectively in communication with the inlet fittings 12 of the respective pulsator units.

Ports

130 and 132, also controlled by the pistons 110 and 112 serve to control exhaust flows from the pulsators with delivery through

passages

134 and 136 and thence to return

pipes

138 and 140 communicating with the oil supply reservoir. End pistons 142 and 144 prevent leakage.

Rods

146 and 148 at the ends of the valve member 108 are engageable by

elements

150 and 152 adjustably connected to a slide 154 which is reciprocated to control the cycles of operation. The oil control elements and their operations are fully described in Patent 2,83 6,121 to which reference may be made for details of operation. Desirably the action is as described in said patent to provide substantially continuous flow from the pump. This is achieved by providing constant supply flow from the oil pump 102 with operations as detailed in the patent.

To prevent the possibility of over-drive of a pulsator, each pulsator assembly has associated with it a cylinder 155 having free communication with its oil inlet fitting 12. In the cylinder 155 there is a sleeve valve 156 arranged to control a port 157 communicating with an outlet passage 158 through which oil may be returned to the supply reservoir. A spring 162 normally holds the sleeve valve in its upper position against a snap ring 164 to close 011 the port 157. A collar 166 on the rod 34 is adapted to engage a collar 168 mounted by a spider arrangement and snap ring in the sleeve valve 156, this engagement taking place, however, only if the displacement of the pulsator, and hence of the rod 34 is abnormal. Under such an abnormal condition, the sleeve valve uncovers the port 157 to provide spillage of the driving oil through the outlet 158. Thus there is a positive protection against excess pulsator displacement if that should occur due to some misoperation. So long as the strokes are normal, the valve 156 remains inoperative.

As has already been noted, the rod 34 and its associated elements, its piston, cylinder, and accumulator system, need not be used, if a spring 30 is provided which is ample to collapse the pulsator assembly against the inlet suction. However, a spring has a variable force action, and particularly in large installations satisfactory springs may not be practical for various reasons. In such cases, therefore, the spring action may be augmented by that of an accumulator, as described, which has the further desirable characteristic of providing a substantially constant force through a considerable stroke. The pulsator collapsing system is, thus, susceptible to various modifications. The overall operation will have already become evident and need not be discussed in further detail. The special characteristics of operation of the pulsator have already been described.

It will be evident that various modifications may be made in the embodiment of the invention without departing from the scope thereof as defined in the following claims.

What is claimed is:

1. A pump comprising a chamber having at least one opening for the inflow and outflow of pumped fluid; a pulsator within said chamber provided by a cylinder of flexible elastic rubber-like material mounted at one end to a wall of said chamber and having its other end closed, said pulsator separating said chamber into an outer region surrounding the pulsator for reception of pumped fluid and an inner region within the pulsator for reception of driving fluid; means controlling flow of driving fluid into and out of said inner region; and means confining the ex terior of said pulsator-providing cylinder against substantial radial expansion to confine its expanding movements to a substantially axial stretch of the cylinder, said confining means being in the form of a closely wound helix of a material having little stretch under tension.

2. A pump comprising a chamber having at least one opening for the inflow and outflow of pumped fluid; a pulsator within said chamber provided by a cylinder of flexible elastic rubber-like material mounted at one end to a wall of said chamber and having its other end closed, said pulsator separating said chamber into an outer region surrounding the pulsator for reception of pumped fluid and an inner region within the pulsator for reception of driving fluid; means controlling flow of driving fluid into and out of said inner region; and means confining the exterior of said pulsator-providing cylinder against substantial radial expansion to confine its expanding movements to a substantially axial stretch of the cylinder, said confining means being in the form of a closely wound slack helix of a material having little stretch under tension.

3. A pump comprising a chamber having at least one opening for the inflow and outflow of pumped fluid; a pulsator within said chamber provided by a cylinder of flexible elastic rubber-like material mounted at one end to a wall of said chamber and having its other end closed, said pulsator separating said chamber into an outer region surrounding the pulsator for reception of pumped fluid and an inner region within the pulsator for reception of driving fluid; means controlling flow of driving fluid into and out of said inner region; and means confining the exterior of said pulsator-providing cylinder against substantial radial expansion to confine its expanding movements to a substantially axial stretch of the cylinder, said confining means being in the form of a closely wound helix of a material having little stretch under tension, the convolutions of said helix being substantially in contact with each other when the pulsator is collapsed.

4. A pump comprising a chamber having at least one opening for the inflow and outflow of pumped fluid; a pulsator within said chamber provided by a cylinder of flexible elastic rubber-like material mounted at one end to a wall of said chamber and having its other end closed, said pulsator separating said chamber into an outer region surrounding the pulsator for reception of pumped fluid and an inner region within the pulsator for reception of driving fluid; means controlling flow of driving fluid into and out of said inner region; and means confining the exterior of said pulsator-providing cylinder against substantial radial expansion to confine its expanding movements to a substantially axial stretch of the cylinder, said confining means being in the form of a closely wound slack helix of a material having little stretch under tension, the convolutions, of said helix being substantially in contact with each other when the pulsator is collapsed.

5. A pump comprising a chamber having at least one opening for the inflow and outflow of pumped fluid; a pulsator within said chamber provided by a cylinder of flexible elastic rubber-like material mounted at one end to a wall of said chamber and having a rigid end closure, said pulsator separating said chamber into an outer region surrounding the pulsator for reception of pumped fluid and an inner region within the pulsator for reception of driving fluid; means controlling flow of driving fluid into and out of said inner region; means confining the exterior of said pulsator-providing cylinder against substantial radial expansion to confine its expanding movements to a substantially axial stretch of the cylinder, said confining means being in the form of a closely wound helix of a material having little stretch under tension; and means for guiding said end closure in the direction of the axis of said cylinder.

6. A pump comprising a chamber having at least one opening for the inflow and outflow of pumped fluid; a pulsator Within said chamber provided by a cylinder of flexible elastic rubber-like material mounted at one end to a wall of said chamber and having a rigid end closure, said pulsator separating said chamber into an outer region surrounding the pulsator for reception of pumped fluid and an inner region within the pulsator for reception of driving fluid; means controlling flow of driving fluid into and out of said inner region; means confining the exterior of said pulsator-providing cylinder against substantial radial expansion to confine its expanding movements to a substantially axial strecth of the cylinder, said confining means being in the form of a closely wound slack helix of a material having little stretch under tension; and means for guiding said end closure in the direction of the axis of said cylinder.

7. A pump comprising a chamber having at least one opening for the inflow and outflow of pumped fluid; a pulsator within said chamber provided by a cylinder of flexible elastic rubber-like material mounted at one end to a wall of said chamber and having a rigid end closure, said pulsator separating said chamber into an outer region surrounding the pulsator for reception of pumped fluid and an inner region within the pulsator for reception of driving fluid; means controlling flow of driving fluid into and out of said inner region; means confining the exterior of said pulsator-providing cylinder against substantial radial expansion to confine its expanding movements to a substantially axial stretch of the cylinder, said confining means being in the form of a closely wound helix of a material having little stretch under tension, the convolutions of said helix being substantially in contact with each other when the pulsator is collapsed; and means for guiding said end closure in the direction of the axis of said cylinder.

8. A pump comprising a chamber having at least one opening for the inflow and outflow of pumped fluid; a pulsator within said chamber provided by a cylinder of flexible elastic rubber-like material mounted at one end to a wall of said chamber and having a rigid end closure, said pulsator separating said chamber into an outer region surrounding the pulsator for reception of pumped fluid and an inner region within the pulsator for reception of driving fluid; means controlling flow of driving fluid into and out of said inner region; means confining the exterior of said pulsator-providing cylinder against substantial radial expansion to confine its expanding movements to a substantially axial stretch of the cylinder, said confining means being in the form of a closely wound slack helix of a material having little stretch under tension, the convolutions of said helix being substantially in contact with each other when the pulsator is collapsed; and means for guiding said end closure in the direction of the axis of said cylinder.

9. A pump comprising a chamber having at least one opening for the inflow and outflow of pumped fluid; a pulsator within said chamber provided by a cylinder of flexible elastic rubber-like material mounted at one end to a wall of said chamber and having a rigid end closure, said pulsator separating said chamber into an outer region surrounding the pulsator for reception of pumped fluid and an inner region within the pulsator for reception of driving fluid; means controlling flow of driving fluid into and out of said inner region; means confining the exterior of said pulsator-providing cylinder against substantial radial expansion to confine its expanding movements to a substantially axial stretch of the cylinder; means for guiding said end closure in the direction of the axis of said cylinder; and a rigid cylinder Within the first mentioned cylinder having an end closable by said rigid end closure to present to the interior of said first mentioned cylinder an imperforate cylindrical surface.

10. A pump comprising a chamber having at least one opening for the inflow and outflow of pumped fluid; a pulsator within said chamber provided by a cylinder of flexible elastic rubber-like material mounted at one end to a wall of said chamber and having a rigid end closure, said pulsator separating said chamber into an outer region surrounding the pulsator for reception of pumped fluid and an inner region within the pulsator for reception of driving fluid; means controlling flow of driving fluid into and out of said inner region; means confining the exterior of said pulsator-providing cylinder against substantial radial expansion to confine its expanding movements to a substantially axial stretch of the cylinder; means for guiding said end closure in the direction of the axis of said cylinder; and a rigid cylinder within the first mentioned cylinder having an end closable by said rigid end closure to present to the interior of said first mentioned cylinder an imperforate cylindrical surface; said rigid cylinder closely fitting the interior of the first mentioned cylinder when the latter is in collapsed condition.

References Cited by the Examiner UNITED STATES PATENTS LAURENCE V. EFNER, Primary Examiner.

20 JOSEPH H. BRANSON, JR., Examiner.

Claims

1. A PUMP COMPRISING A CHAMBER HAVING AT LEAST ONE OPENING FOR THE INFLOW AND OUTFLOW OF PUMPED FLUID; A PULSATOR WITHIN SAID CHAMBER PROVIDED BY A CYLINDER OF FLEXIBLE ELASTIC RUBBER-LIKE MATERIAL MOUNTED AT ONE END TO A WALL OFG SAID CHAMBER AND HAVING ITS OTHER END CLOSED, SAID PULSATOR SEPARATING SAID CHAMBER IN AN OUTER REGION SURROUNDING THE PULSATOR FOR RECEPTION OF PUMPED FLUID AND AN INNER REGION WITHIN THE PULSATOR FOR RECEPTION OF DRIVING FLUID; MEANS CONTROLLING FLOW OF DRIVING FLUID INTO AND OUT OF SAID INNER REGION; AND MEANS CONFINING THE EXTERIOR OF SAID PULSATOR-PROVIDING CYLINDER AGAINST SUBSTANTIAL RADIAL EXPANSION OF CONFINE ITS EXPANDING MOVEMENTS TO A SUBSTANTIAL AXIAL STRETCH OF THE CYLINDER, SAID CONFINING MEANS BEING IN THE FORM OF A CLOSELY WOUND HELIX OF A MATERIAL HAVING LITTLE STRETCH UNDER TENSION.