US3411452A - Pump - Google Patents

Description

ET AL 3,411,452

Nov. 19, 1968 J. J. CZARNECKI PUMP 3 Sheets-Sheet 1 Filed Oct. 7, 1966 INVENTORS JERZY J. CZARNECKI 8 PETER ARKWRIGHT 7/ A iiw ATTORNEYS Nbv. 19, 1968 J, czARNEcK ET AL 3,411,452

PUMP

3 Sheets-Sheet 2 Filed Oct. '7, 1966 INVENTORS :JERZY J. CZARNECKI 8 PETER ARKWRIGHT ATTORNEYS ET AL PUMP 5 Sheets-Sheet 5 .1. J. CZARNECKI RELIEF VALVE SERVO Nov. 19, 1968 Filed em.

COOLER INVENTORS JERZY J. CZARNECKI 8 PETER ARKWRIGHT ATTORNEYS RELIEF VALVE FiLTER BY QM,

REDUCTION {I64 PILOT VALVE F l G. 2

United States Patent 3,411,452 PUMP Jerzy J. Czarnecki, Princeton, and Peter Arkwright, Pennington, N .J assignors to De Laval Turbine Inc., Trenton, N..I., a corporation of Delaware Filed Oct. 7, 1966, Ser. No. 585,133 7 Claims. (Cl. 103152) ABSTRACT OF THE DISCLOSURE A pulsator pumping system comprising a pair of mechanic-ally connected pulsators is provided with a positive, reversible pump in its driving liquid system, which delivers driving liquid alternately to the pulsators. Make-up liquid is delivered by a second pump to the driving liquid system, and a combination of check valves and a relief valve permits flow of liquid from one side of the reversible pump to the other when the pressure differential becomes too high. Interconnections are provided for prepressurization of a collapsed pulsator by liquid delivered from the expanded pulsator.

This invention relates to pumps and has particular reference to pumps of the pulsator type such as those of Patents 2,836,121, 3,048,114, 3,080,821, 3,194,169, and 3,212,447.

Heretofore in pumps of this type it has been usual to provide the driving liquid from a reservoir to a phasing valve for distribution to two or more pulsators so operated that their joint delivery of pumped liquid was at a substantially continuous rate with minimum pulsations. During return strokes of the individual pulsators the driving liquid was returned to the reservoir. Since the supply to the pulsators has usually been at very high pressures, this circuit of the driving liquid involved considerable losses.

One of the objects of the present invention is to provide a system in which at least one pair of pulsators operates with direct flow from the collapsing one to the expanding one through a pump capable of producing high pressure, with only minor flow, essentially of make up nature, involving a reservoir. By this arrangement efficiency is substantially increased.

Other objects of the invention relate to the attainment of operations leading to satisfactory control and pumping, and these will become more apparent from the following description, read in conjunction with the accompanying drawings in which:

FIGURES 1A and 1B are sectional views showing a preferred type of pump provided in accordance with the invention; and

FIGURE 2 is a diagram showing particularly the driving and control means involved.

Referring first to FIGURES 1A and 1B, the latter being a continuation of the righthand portion of the former, with repetition of the elements constituting the central portion of the pump, there is provided a housing 2 having its respective ends closed by cap members 4 and 6 providing chambers for the pumped liquid which have respective connections 8, 9, 10 and 11 running to inlet and outlet check valve assemblies through which pumped liquid is drawn from a supply and discharged to a point of use. The inlet and outlet check valve assemblies are conventional and not illustrated, being of types shown in the patents previously referred to. The present pump is particularly designed to operate at high pressures and with large deliveries, though the aspects of the invention are equally applicable to pumps of small size and/or involving relatively low delivery pressures.

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Two pulsators are involved located at opposite ends of a rod 12 which passes through packing 14 in a central member which separates two regions receiving the driving liquid. As will be apparent from FIGURES 1A and 1B, the pump is symmetrical about this central member. The rod 12 connects the pulsator assemblies which are respectively designated 16 and 18. Since these are identical in form, a single description will suffice with the same numerals applied to both assemblies. Referring to either assembly, a rigid plate member 20 has secured to it a first pulsator section 22 which is connected by a rigid coupling ring 24 to a second pulsator section 26 which is anchored to a fixed member 28 secured in the housing. The use of two sections is to provide an extended working stroke, and each section is. of the type illustrated in Browne Patent 3,194,169, comprising a flexible, expansible member of a rubber-like material formed with annular folds within which are located rigid rings to maintain proper shape and control the desired expansion and contraction. In this type of pump oil is desirably used as the driving liquid, and the pulsator composition is chosen to be unatfective by the oil used, and also to be unalfective by the pumped liquid. Various synthetic rubbers are suitable for this purpose.

The respective left and righthand pumping chambers provided within the pulsators are designated 30 and 32. With these chambers there communicate the respective passages 36 and 38 for inflow and outflow of the driving liquid, these having connections as described hereafter.

Valve assemblies 40 and 42 are provided in association with the respective pulsators to cooperate with seats 44 and 46 formed at the ends of the members 28 which are annular in form. The valve assemblies are the same and only one need be described. Each comprises a valve member 48 having a body of rigid material and an extension 50 formed of a rubber which by conformity with a corresponding seat will provide a tight seal. Rings 52 located in grooves in the rod limit inward movements of the valve members 48 under the action of springs 54 backed up by rings 56 also in grooves in the rod. The valve members, during rod strokes, are accordingly removed from their seats by the rings 52, but seat under the forces of the springs 54 which are compressed by the rings 56.

Spiders 58 and 60 provide guidance for the rod 12 and hold in position liners 62 and 64 the cylindrical inner surfaces of which serve to mount the slide valves 66 and 68, the inner ends of which are of spider form engaged by springs 70 and 72 backed up by the spiders 58 and 60, the springs normally urging the valves 66 and 68 against stops provided by snap rings 78 and 80 located in grooves in the liner. The valve 66 is provided with an annular groove 82 having communication with its interior and arranged to provide communication through small holes 84 which are in communication with piping 86 (FIGURE 1A) which runs to a check valve 88 (FIGURE 1B) communicating through an opening 90 with the face of the valve seat 46 at a point beyond the region engaged by p the valve 48, the check valve 88 opening so as to permit flow from left to right. In identical fashion the valve 68 is provided with an annular groove 92 communicating with its interior and cooperating with small holes 94 through the liner 68 communicating with piping 96 connected through check valve 98 with an opening 100 in the seat 44 beyond the region engaged by the lefthand valve 48. Flow through the piping 96 is from right to left.

Openings 102 in the liner 62 communicate with a groove 106 which has an external connection to an oil supply reservoir, not illustrated in FIGURE 1A. Similarly, openings 104 in liner 64 communicate with an annular groove 108 also having an external connection to the reservoir. The openings 102 and 104 cooperate with the 3 respective valves 66 and 68 under some conditions as hereafter described.

The liners 62 and 64 are provided with large openings and 112, respectively, providing free communication between the interiors of the liners and the driving oil passages 36 and 38.

Referring to FIGURE 2, this diagrams the pump driving and control apparatus, and indicates some of the elements previously described such as the cross-connections 86 and 96, the check valves 88 and 98, the passages 90 and 100, and the various passages 106, 108, 36 and 38.

The driving liquid, oil under suitably high pressure is provided through the connections 114 and 116, and also relieved through these connections, by a reversible pump 118 driven by a motor 120 which will normally operate at constant speed.

The pump 118 is preferably a positive pump of the multiple piston type which may have its flow reversed by the tilting of a cam plate 122 which acts upon rotating pistons in individual cylinders having connection to valve passages in a valve plate adjacent to which the cylinders rotate. The passages are connected to the valve ports which serve for inflow and outflow reversibly depending upon the position of the cam plate 122. Pumps of this type are well known, the Lucas pump design being typical. When delivery is to be reversible or variable, provisions are made for tilting the cam plate 122, and in the present instance this is effected by connection of the cam plate to a piston 124 of a servo 126, the ends of the cylinder in which the piston moves being connected to lines 128 and 130 for the entrance and exit of piston-positioning oil. When a piston is at one limit of its movement the pump 118 will receive oil through connection 116 and deliver it through connection 114, and when the piston is at the other limit of its movement the pump will receive oil through connection 114 and deliver it through connection 116.

The respective lines 114 and 116 are connected through check valves to provide flow therefrom through an adjustable high pressure relief valve 136 if pressures become excessive. The downstream connection of the relief valve is to check valves 138 and 140 which may respectively deliver oil to the connections 114 and 116.

A constant delivery pump 142, such as a multiple screw pump is driven by a motor 144 which desirably operates at constant speed, the pump receiving oil from a reservoir 146 and delivering it through a filter 148. The outflow from the filter may pass through two connections. One of these is indicated at 150 and delivers oil through an adjustable reduction valve 152 to the line 154 which connects to the inputs of both check valves 138 and 140. This line provides makeup. Connection 150 also runs to an adjustable relief valve 156 which permits oil passage when the pressure exceeds a predetermined value. Oil flowing from the relief valve passes through a cooler 158 and back to the reservoir through connection 160. The second connection 162 from the filter 148 supplies oil to a pilot valve 164 from which outfiowing oil resulting from pressure relief passes through line 166 back to the reservoir 146. The pilot valve 164 has output connections at 167 and 169 through adjustable orifices, which may be in the form of adjustable valves 168 and 170, there orifices communicating with the servo lines 128 and 130.

The pilot valve 164 is of a conventional supply and relief type. Its usual moveable element is operated by a mechanical connection 172 through reduction gearing 174 by the motor 144. Its cycle is such as to produce reversal of the pump 118, by motion of piston 124, at a suitable cycling rate for operation as will now be described.

Assume at a start of operation that the lefthand pulsator (FIGURE 1A) is fully collapsed and the righthand pulsator (FIGURE 1B) is fully expanded. At this time the valve 40 closes the chamber 30 within the lefthand pulsator, limiting its further collapse by trapping the oil 4 therein and concurrently limiting further righthand movement of the rod 12.

The lefthand slide valve 66 closes off both ports 84 and 102, the closing off of the latter preventing communication between the region within the slide valve and the return line to the reservoir. On the righthand side of the pump. the pulsator is now fully expanded and the chamber 32 is at maximum volume.

Valve 42 is held open and well spaced from its seat 46 by the action of ring 52.

The righthand slide valve 68 opens the port 94 to the pressure within the chamber 32, and the port 104 is open to the line 108 running to the reservoir.

The beginning of the next stroke, which involves the lefthand movement of the rod 12, is initiated by the movement of the pilot valve 164 under the action of motor 144 through the reduction gearing 174 to effect positioning of the cam plate 122 of the pump 118 to cause that pump to pump oil from passage 38 (FIGURE 1B) through connection 116 and deliver this oil through connection 114 to the passage 36. The oil pressure forces the valve 40 from its seat so that oil enters the lefthand pulsator causing it to expand and force the product liquid outwardly from the left product chamber. Shortly after the rod 12 starts to move, the valve 40 is carried with it by the ring 52 opening a wide passage for oil flow into the chamber 30.

Simultaneously, the righthand pulsator is contracted by the pull of rod 12 and the product liquid accordingly enters the righthand product chamber from its supply.

The respective expanding and contracting actions of the pulsator continue, and during the major part of the stroke the righthand slide valve 66 remains in its initial position closing the ports 84 and 102.

The slide valve 68 moves at the very beginning of the stroke to close off the port 104 and thus cut off the communication between the chamber 32 and the oil reservoir, the slide valve 68 moving with ring 76 on the rod 12 under the action of the spring 72. Its movement terminates with its engagement with the fixed snap ring 80.

The conditions so achieved continue until near the end of the lefthand stroke of the rod 12. As the end of this stroke is approached, the port 84 is opened by engagement of the ring 74 'with the slide valve 66. Just before this occurs, but substantially simultaneously, the valve 42 will reach its seat, and while a definite volume of liquid will then be trapped in the chamber 32 some further move-ment of the rod 12 may occur due to the expansibility of the righthand bellows. But when the port 84 is opened, a small amount of high pressure driving oil may pass through the connection 86, check valve 88 and passage 90 to relieve excess pressure in the lefthand chamber 30 and raise the pressure in the chamber 32 in preparation for the next stroke. Slight further movement of the rod 12 causes the slide valve 66 to uncover the port 102 permitting flow to the reservoir with drop of pressure. But when this occurs the pressure within the chamber 32 which has been raised is maintained by the closure of check valve 88. In view of the communication with the reservoir any further driving oil through the passage 36 is diverted to the reservoir with cessation of expansion of the chamber 30.

The parts are now in their initial position first described except that the conditions are reversed between the righthand and lefthand elements. The plate 122 'will now be shifted by the pilot valve action on piston 124 to effect operations to move the rod 12 to the right with corresponding events. Since these events are the same except for the reversal of movement and elements, they need not be separately described.

Reference may now be made to various control actions, giving particular consideration to FIGURE 2.

The function of the cross-connections 86 and 96, including the respective check valves 88 and 98 is to depressurize the chamber approaching the end of its expansion stroke with utilization of the pressure to prepressurize the chamber which is about to begin its working stroke. When the prepressurizing occurs the pulsator chamber in which the pressure is caused to rise is closed by its valve 40 or 42. In explanation of the utility of the pressure transfer operation it may be pointed out that under the high pressures which are involved even rigid walls will yield to a considerable extent so that the geometry of chambers involved cannot be considered by any means fixed. When pressure is relaxed the volumes of the chambers which have been under high' pressure will decrease; and upon repressurizing the volumes will increase. In pumps of the general type herein being considered sudden relief of pressures will produce shocks essentially of a sound type which may be extremely violent giving rise to highly objectionable noise and vibration, resembling to a considerable extent the shocks produced by the ordinary phenomenon of water hammer. By permitting depressurizing through the cross-connections before relief of pressure by opening communication to the reservoir, the shock aspects are greatly reduced, and for this purpose it is desirable that the liquid transfer involved should be attenuated as by the small passages involved at 82 and 84 and restriction to free flow afforded through the pipe connections and the check valves. Under these conditions the pressure equalization takes place smoothly. At the same time, by reason of the pressure, the chamber which is about to receive driving liquid will be preliminarily expanded to take up the slack so that the oil driving pump 118 is relieved of this function. Reverse flows through the cross-connections are prevented by the check valves. At the end of a stroke the opening of the working chamber to the reservoir involves some loss of the driving oil from the theoretically closed system which involves the back and forth flow through the pump 118. The pump 142 is designed to provide make up and also take care of other aspects of operation involving loss of oil from the desirably closed system just mentioned. The pump 142 (which also supplies the small amount of oil necessary to operate the pilot valve 164) provides a desired pressure in the connection 154 through the reduction valve 152 with which there is associated the relief valve 156 which takes care of excess delivery, the pump 142 being desirably of a positive type (e.g., a screw pump) driven by a constant speed motor 144 to provide a volume flow of oil which is in excess of normal requirements. The check valves 138 and 140 provide flow from the line 154 to the respective connections 36 and 38 whenever these connections have pressures substantially less than the pressure in the line 154. This arrangement takes care of pressure deviations which may occur both in normal operation and due to deviations from normal operations which may well occur though in most cases they will not represent such abnormal operations as could be considered maloperations. Such deviations from normal operation may be due to such matters as temporary obstructions or overloads in the product connections of the pump- The check valves 132 and 134 in combination with the settable relief valve 136 and the check valves 140 and 138 serve also to take care of abnormal conditions. For example, if the pressure in the line 36 rises abnormally above the setting of the relief valve 136 there can be a flow through check valve 132, relief valve 136 and check valve 140 to bypass flow tothe line 38 which at such time will ordinarily be at the normal pressure of the system, considering motors 120 and 144 operating at substantially constant speeds, and therefore at speeds bearing a substantially constant ratio to each other. Normal adjustments should be such that the operation of the pump 118 should be reversed shortly after such delivery to the working chamber as would displace it to the end of its working stroke. If an ideal operation could be achieved in which the reversal of the operation of pump 118 could be timed precisely with the achievement of full expansion of the bellows, the working oil would be essentially of fixed volume transferred between the bellows. Obviously, this situation is unattainable due to the desirability of obtaining full strokes despite variations in the product delivery which in turn would impose variable loads on the pump 118 variably loading its motor to produce slight deviations in speed, expansibilities of oil spaces involved due to extremely high pressures as mentioned above, the inherent variations of volumes due to the bellows operating under different pressure conditions, etc. The make up and other provisions for flows described particularly in connection with FIGURE 2 take care of proper operation despite these disturbing factors.

While there has been illustrated a single pump unit having a pair of interconnected pulsators, and such a single unit may suflice in many instances for the desired pumping action, it may be noted that the units of a com plete pump may be multiplied as much as desired: for example, three units with three sets of paired pulsators. In such a case, it is desirable that the units should operate with displaced phases, and considering a cycle as involving a complete reciprocation of a rod 12 of a unit the phased displacements may be 60, i.e., the units would achieve ends of product pumping cycles at 60 intervals, there be ing for each unit two product pumping cycles in each complete cycle. This phasing can be achieved in an obvious fashion by having the drive 172 from the reduction gearing 174 for the respective pilot valves, one for each unit, so arranged as to operate the pilot valves with the corresponding phase differences. The result, of course, is to achieve more uniform flow.

It will be evident that achieved in accordance with the invention is the direct low-loss transfer of Working oil between the paired bellows of a unit, without involving a circuit including a reservoir such as 146 which may be small and of a volumetric capacity only sufiicient to take care of the make-up requirements as described.

It will be evident that various changes in details may be adopted without departure from the invention as defined in the following claims.

What is claimed is:

1. Pumping means including a pair of pump units, each of which comprises a flexible pulsator and an associated housing defining a driving liquid chamber and a driven liquid chamber separated by said pulsator and valved inlet and outlet connections to said driven liquid chamber; a positive pump of reversible flow type having connections to said driving liquid chambers so that said positive pump delivers driving liquid directly from one driving liquid chamber to the other, and vice versa; means for driving said positive pump to elfect flow reversal thereby, wherein the improvement comprises an auxiliary pump delivering make-up liquid under pressure, means delivering said make-up liquid to the driving liquid system between said positive pump and one of said driving liquid chambers, means delivering said make-up liquid to the driving liquid system between said positive pump and the other of said chambers, and valve means normally preventing flow of driving liquid between said systems except through said positive pump, but permitting flow between said systems if the difference in pressure between said systems exceeds a predetermined value.

2. Pumping means according to claim 1 in which the pulsators are mechanically connected so that as one driving liquid chamber is expanded the other is contracted and vice versa.

3. Pumping means according to claim 1 comprising means effecting closure of each driving liquid chamber at the condition of a minimum volume thereof to trap driving liquid therein.

4. Pumping means according to claim 2 comprising means effecting closure of each driving liquid chamber at the condition of a minimum volume thereof to trap driving liquid therein.

5. Pumping means including a pair of pump units, each of which comprises a flexible pulsator and an associated housing defining a driving liquid chamber and a driven liquid chamber separated by said pulsator and valved inlet and outlet connections to said driven liquid chamber, a pump supplying driving liquid under pressure, means delivering said driving liquid supplied by said pump alternately into the driving liquid chamber of one of said units and into the driving liquid chamber at the other of said units, means mechanically connecting said pulsators so that as one driving liquid chamber is expanded, the other is contracted, and means efiecting closure of each driving liquid chamber at the condition of minimum volume thereof to trap driving liquid therein, wherein the improvement comprises means effecting transfer of driving liquid under pressure from each driving liquid chamber at the end of its expansion to the other driving liquid chamber when the latter is closed thereby to relieve the pressure in the former and prepressurize the latter preparatory to its expansion.

6. Pumping means according to claim 5 in which each of said transfer-elfecting means includes a check valve to permit fiow only toward the collapsed chamber.

7. Pumping means according to claim 5 in which said pump and said means delivering said driving liquid supplied by said pump comprises a positive pump of the reversible flow type having connections to said driving liquid chambers so that said positive pump delivers driving liquid directly from one driving liquid chamber to the other.

References Cited UNITED STATES PATENTS 731,241 6/1903 Steiner 10346 2,625,886 1/1953 Browne 103-150 2,753,805 7/1956 Boivinet. 2,768,500 10/ 1956 Tyler. 3,164,101 1/ 1965 Van Nederynen 103152 3,192,860 7/1965 Hardison.

ROBERT M. WALKER, Primary Examiner.

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