US3430576A

US3430576A - Reciprocating pump

Info

Publication number: US3430576A
Application number: US633318A
Authority: US
Inventors: Lewis Tyree Jr
Original assignee: Individual
Current assignee: Liquid Carbonic Corp
Priority date: 1966-05-18
Filing date: 1967-03-02
Publication date: 1969-03-04
Anticipated expiration: 1986-03-04

Description

March 4, 1969 1... TYREE, JR

BECIPROGATING PUMP Sheet of 2 Filed March 2, 1967 MIL;

IN v E N T0 R LEW/5 73 1555 BYMMUKLUIQA 7212/ in.

ATTORNEYS March 4, 1969 L. TYREE, JR

RECIPROCATING PUMP Sheet 3 ofz Filed March 2, 1967 v Q Q 7 mg? INVENTQFZ LEW/5 TYPEE, 1/2 IMQMM JLQMZA grin ATTORNEYS United States Patent 3,430,576 RECIPROCATING PUMP Lewis Tyree, Jr., 9955 S. Hamilton Ave., Chicago, Ill. 60643 Continuation-impart of application Ser. No. 551,090, May 18, 1966. This application Mar. 2, 1967, Ser. No. 633,318 U.S. Cl. 103-178 Int. Cl. F04b 21/04, 15/06 31 Claims ABSTRACT OF THE DISCLOSURE This application is a continuation-in-part of my application Ser. No. 551,090, filed May 18, 1966, and now abandoned.

This invention relates to positive displacement, reciprocating pumps, and more particularly to pumps which are designed for pumping boiling liquids.

The term boiling liquids is used to describe liquids which, under their instant environmental conditions of temperature and pressure, are at or near their boiling points and is used herein to include cryogenic liquids. These liquids are sometimes called liquified gases because they are normally considered to be gases because they are generally present in the gaseous state at room temperature and atmospheric pressure. As a result of the imposition of pressure or the lowering of temperature, or both, these gases assume the liquid state. Examples of boiling liquids include, but are by no means limited to, liquid carbon dioxide, ammonia, Freon, nitrogen, air, oxygen and helium.

The design of a boiling liquid pump presents problems in a number of areas including problems relating to the unusual nature of the liquid, which problems may become manifest both in the driving mechanism and in the liquid-handling portion of the pump. One very important consideration of a piston-type boiling liquid tpump concerns the action in the pumping chamber during the suction stroke. Because the liquid being transferred is at or near its boiling point, the lowering of the fluid pressure on the suction stroke has the tendency to convert the liquid to vapor rather than to induce the liquid to flow into the pumping chamber. Various pumps have been designed to overcome this problem, such as those pumps disclosed in US Patents Nos. 3,011,450 and 3,- 023,710 which have proved quite successful for various applications. However, improved designs for boiling liquid pumps are always desired.

A principal object of the present invention is to provide an improved reciprocating, positive displacement pump which is simple in mechanical design. Another object is to provide a pump of this type which is especially designed for pumping boiling liquids. A further object is to provide a pump of this type which is especially designed for pumping liquids which are initially under relatively high pressures. A still further object is to provide a pump of the above general type which is capable of pumping at relatively high capacities using a short piston stroke. Yet another objectis to proved a pump for pumping a liquid under fairly high pressure which pump on the discharge stroke does only the work represented by the differential pressure between the inlet and the outlet pressures of the liquid. Still another object is to provide a piston pump of this type which does substantial work during both the discharge stroke and the intake stroke so that a motor of correspondingly lower power may be employed. A still further object is to provide a pump which can be inexpensively constructed and which includes a positive self-priming intake action which makes it especially suited for use in transferring boiling liquids. These and other objects of the invention are more particularly set forth in the following detailed description and in the accompanying drawings wherein:

FIGURE 1 is a vertical sectional view of a pump embodying various features of the invention;

FIGURE 2 is a horizontal sectional view taken generally along line 22 of FIGURE 1;

FIGURE 3 is an enlarged fragmentary view of a portion of FIGURE 1;

- FIGURE 4 is an enlarged perspective view of one element of the pump shown in FIGURE 1;

FIGURE 5 is a schematic view of an illustrative system employing the pump shown in FIGURE 1;

FIGURE 6 is an enlarged fragmentary sectional view of the pumping chamber of the pump illustrated in FIG- URE 1 at the beginning of the discharge stroke;

FIGURE 7 is a view similar to FIGURE 6 at a later point during the discharge stroke after the discharge valve has opened;

FIGURE 8 is a view similar to FIGURE 6 at the very end of the discharge stroke as the discharge valve has just closed; and

FIGURE 9 is a view similar to FIGURE 6 after more than half of the intake stroke has been completed.

The present invention provides a pump which is especially suited for pumping boiling liquids and which embodies principles which permit it to operate with a very short stroke and at a high number of piston strokes per minute. The high speed, short-stroke pumping of boiling liquids by the pump is facilitated by a design which contributes to the quick filling of the pumping chamber on each intake stroke and thus promotes high volumetric efficiency. This pump operation facilitates excellent utilization of a mechanical drive operating at a high rpm. and with a relatively low power consumption. The pump is especially suited for pumping liquids at superatmospheric pressures, and it is designed to perform work on the discharge stroke equal to the difference between the discharge pressure and the intake pressure, rather than having to perform work equal to the difference between the discharge pressure of the liquid and atmospheric pressure. Because the pump operates in this manner, it does not only work during the discharge stroke but shares the total work done between the intake stroke and the discharge stroke; thus, the pump provides more efficient utilization of the motor and transmission than would the normal piston pump which utilizes its drive for effective power transmission only 50 percent of the time, i.e., during the discharge stroke. A surge chamber may be included in combination with the pump sump to further insure favorable volumetric efliciency in certain pumping operations.

Now referring more particularly to the drawings, a pump 11, which is particularly designed for pumping boiling liquids, is illustrated in detail in FIGURE 1. The pump 11 includes pump body 12 comprising a pump casing 13, wherein a plunger 15 is reciprocally mounted, an upper cap 20 and a lower crank housing 21. The plunger 15 comprises a piston head portion 17 which is preferably formed integrally with a piston rod portion 19, as illustrated, although they may be formed separately and suitably joined. Suitable drive means 23 is generally supported in the crank housing 21 and comprises a shaft 25 mounted in suitable bearings, which shaft includes an off-center lobe 27 of a diameter slightly larger than the shaft. The lobe 27 is connected via a surrounding crank 29 to the lower end of the piston rod 19. The shaft 25 extends out of the crank housing 21 in one direction, and the extending end of the shaft is connected to suitable power means, such as an electric motor and transmission (not shown).

A pumping chamber 31, which is generally toroidal in shape, is located between the outer surface of the plunger 15 and the pump casing 13 at approximately the point of transition between the piston head portion 17 and the piston rod portion 19. Intake valve means 33 is located in a hollow interior portion of the plunger 15 and includes a ball 35 and an annular ball seat 37.

In the illustrated pump, a sump 39 which is located generally vertically above the plunger 15 is in fluid communication with the pumping chamber 31 through the hollow center of the ball seat 37, which forms the intake valve port that is closed by the ball 35, and generally radially extending passageway means 41 leading from the region of the valve ball 35 to the pumping chamber 31. The sump 39 comprises the hollow portion of the upper end of the pump casing 13 which is unoccupied by the piston head 17. An inlet to the sump 39 is provided in the upper cap 20 by a ring-shaped passageway 43 in the underside of the cap 20 and a connecting side entrance passageway 45, which is threaded to receive a liquid inlet line 47 (see FIG.

The pump casing 13 is provided with a side outlet 49 including an outlet passageway 51 which leads radially inward to the hollow center of the pump casing 13 in the region of the pumping chamber 31. Discharge valve means 53 is mounted in the side outlet 49. The outlet passageway 51 includes an internally threaded portion 55 which is employed in the mounting of the discharge valve means 53 and for connection with a discharge line 57 (see FIG. 5).

Although, as will be hereinafter explained, it is not necessary to operate the pump 11 with the plunger 15 disposed vertically, because the pump is illustrated in this orientation in FIGURE 1 and because it is preferably operated with this orientation, the description of various of the elements of the pump and its overall operation is described herein with reference to this vertical orientation for purposes of simplicity.

Now referring more specifically to drive means 23, because the crank 29 which is driven by the off-center lobe 27 will necessarily wobble with respect to the piston rod 19, the connection between the piston rod and the crank is made by a suitable ball bushing 61 which is seated in a suitable circular recess 63 provided near the bottom of the hollow piston rod. A ball joint screw 65 passes downward through the ball bushing 61 and is threadably received in a threaded hole provided at the top of the crank 29. A hex-shaped socket 67 is provided in the head of the screw 65 so that it can be tightened in the assembled position. A slidable collar 69 is seated atop the ball bushing 61 and in a larger diameter portion of the hollow axial center of the piston rod 19. A recess 71 in the underside of the collar accommodates the head of the ball joint screw 65. If desired, a rubber O-ring 73 may be provided in a peripheral groove formed in the exterior surface of the collar 69 to provide a seal at the bottom of the passageway through the hollow piston rod. A tapped hole 75 in the top of the collar 69 facilitates its removal if it should be desired to disassemble the pump.

Disposed above the collar 69 is a tubular spacer 77, and at the top of the tubular spacer, there is disposed a ball restrainer 79 which provides a concave socket 81 for receiving the bottom of the ball 35 and an upstanding post portion 83 for holding an intake valve spring 85.

An O-ring 87 may also be provided in a groove in the exterior of the ball restrainer 79 to provide a second seal in the internal hollow passageway through the plunger 15. A tubular ball spacer 89 is disposed about the upper post portion of the ball retainer and guides the intake ball 35 in its movement. Immediately above the ball spacer 89 is the annular ball seat 37 which is externally threaded and is screwed into the internally threaded upper end of the piston head 17 by a suitable tool which fits into slots 91 provided in the upper end of the ball seat 37. When tightened down, the ball seat exerts an axial force on the tubular ball spacer 89, ball restrainer 71, the spacer, the collar 69, and the ball bushing 61, holding all of them in the desired locations in the assembled plunger 15.

In assembly of the pump 11, the plunger 15 is connected to the crank 29 after the plunger is disposed within the pump casing 13. The only direct contact between the plunger 15 and the pump casing 12 is in the region of the piston head 17 whereat a plurality of piston rings 93 are provided in peripheral grooves in the piston head which provide a high pressure seal between the interior cylindrical surface of the upper hollow end of the casing 13 and the plunger 15 which serves as the upper seal for the pumping chamber 31. Slightly above the piston rings 93, a shallow but longer recess is cut in the piston head 17 wherein a rider strip 95 of a suitable material, such as bronze and Teflon, is provided to help maintain precise alignment between the plunger 15 and the casing 13 without creating high friction.

Whereas the piston rings 93 provide the seal at the upper end of the toroidal pumping chamber 31, high pressure packing 97 is used to seal the lower end. The actual lower boundary of the pumping chamber is provided by an annulus 99 having its upper portion shaped to mate with the contour of the transition surface between the piston head portion and the piston rod portion at the exterior surface of the plunger 15. A peripheral recess at the upper end of the annulus 99 accommodates a snap ring 101 which is seated in a groove provided in the interior wall of the pump casing 13 at a location adjacent the lower level of the outlet pasageway 51. The snap ring 101 locates the annulus 99 in the desired predetermined position within the pump casing 13, the annulus being inserted from below and being held against the underside of the snap ring by a force applied from therebeneath. The annulus 99 may be made of any suitable material, such as brass or glass-filled polytetrafiuoroethylene, *which is compatible with the liquid being pumped and which has sutficient rigidity to define the lower boundary of the pumping chamber 31 and, at the same time, to perform a bushing function adjacent the exterior surface of the plunger 15 which slidably reciprocates therethrough.

The high pressure packing 97 which serves as the high pressure seal at the lower end of the pumping chamber 31 is positioned immediately below the annulus 99 and is held in place (and in turn holds the annulus 99 in place against the snap ring 101) by means of a lower take-up nut 103. The take-up nut 103 has external threads on its lower end which engage mating internal threads provided at the bottom end of the hollow passageway in the pump casing 13. The upper end of the take-up nut 103 contacts the lower surface of the tubular packing 97. The upper end of the nut 103 is provided with an external groove and an internal groove. An O-ring resides in the external groove and provides a seal between the take-up nut 103 and the pump casing 13. A suitable seal 107 is likewise provided in the interior groove. In order to tighten the take-up nut 103 against the packing 97 and the annulus 99, a plurality of radial holes 109 are drilled in the sidewall of the nut to provide means for engagement and turning of the take-up nut 103 by a spanner. To provide access to the radial holes 109 in the take-up nut in the assembled position, the pump casing 13 is provided with a plurality of arcuate slots 111 through which a spanner can be inserted and turned. In the illustrated pump, three slots each about 90 wide are provided. A set screw 113 permits the nut 103 to be locked in place.

At its lower end, the take-up nut is provided with an internal peripheral recess 115 which accommodates a tubular bushing 117. The tubular bushing 117 provides a bearing surface for the lowermost portion of the reciprocating piston rod 19. Moreover, the tubular bushing 117 resides partly within the pump casing 13 and partly within the crank housing 21, wherein it is supported on a ledge (not shown), and thus provides positive alignment between the pump casing 13 and the crank housing 21. In the assembly of the pump 11 the bushing 117 may be inserted into the upper end of the crank housing 21, and the pump casing 13, with the nut .103 and packing 97 installed, lowered over it. After the plunger is connected to the crank 29, and its internal parts completely assembled, the final asembly of the pump body 12 takes place.

Four long cap screws 119 are used to bolt the upper cap to the crank housing 21, and clamp the pump casing 13 therebetween. As best seen in FIG. 2, one cap screw 119 is positioned at each corner of the cap 20 at a location exterior of a pump casing itself so that the four cap screws straddle the pump casing. The cap screws 119 pass through holes provided in the four corners of the upper cap 20 and screw into four threaded holes in the four corners of the top of the crank housing 21. Lockwashers 121 or any suitable locking means may be provided to assure the casing 13 is tightly held between the cap 20 and the crank housing 21.

The upper cap 21 is recessed in its underside to mate with the upper end of the pump casing 13. A suitable O-ring 123 is provided therebetween to assure there is a liquid-tight seal. As previously mentioned, the cap 20 includes the ring-shaped passageway 43 and the side entrance passageway 45. The cap 20 also contains a generally central bore 125 which in the illustrated embodiment extends in the vertical direction. The bore 125 is threaded and accepts the lower threaded arm 127 or a T member 129. The upper arm 131 of the T 129 has a threaded cap 133 screwed on the upper end thereof. The horizontal arm 135 of the T member 129 connects to the vapor return line 137 (FIG. 5). A funnel-shaped lower entrance 139 is formed in the cap 20 surrounding the lower end of the bore 125. A surge chamber 141 is formed by the vapor trapped in the capped upper arm 131. The function of the surge chamber 141 and the entrance 139 is explained more fully hereinafter in combination with the description of the operation of the pump.

In the intake valve means 33, as previously mentioned, the ball 35 is held in the normally closed position against the ball seat 37 by the compression spring 85, as shown in FIGURE 1. The ball 35 is provided with a cylindrical band 143 on its lower half to fit into the coils of the spring 85. Because the upper concave socket 81 of the ball restrainer is the same radius of curvature as the ball 35, a uniform gap is provided between the ball and the socket through which the ball 35 moves when the intake valve 33 opens. The socket 81 necessarily limits the distance the ball 35 can travel in opening the valve.

To assure that the liquid in the gap does not delay the opening of the valve on the intake stroke a vertical hole 145 is provided in the upper surface of the ball restrainer socket 81. Two diametrical holes 147 at right angles to each other extend through the upstanding post portion 83 of the ball restrainer 79 and connect with the vertical hole 145. The passageway network provided by the

holes

145 and 147 provide ready exit for the liquid from the region of the gap. The vertical hole 145 may be threaded to facilitate assembly and removal of the ball restrainer 79.

The passageway means 41 which provides communication from the interior of the plunger 15 to the pumping chamber 31 comprises a plurality of radially extending holes 149 in the piston head and aligned holes in the associated ball spacer 89. In the illustrated embodiment, eight holes radially spaced at 45 angles are provided in each. The ball spacer 89 is also provided with a plurality of smaller radial holes 153 which connect the lower interior region of the ball spacer 89 with the pumping chamber 31 via a shallow recess 155' provided in the interior wall of the plunger 15 and the holes 149 through the plunger wall. The establishment of fluid communication between the pumping chamber 31 and the lower region assures the intake valve 33 remains tightly closed during the discharge stroke. As will be explained more fully hereinafter, during the intake stroke of the pump, the inertia of the ball 35 in its liquid environment in conjunction with the high pressure region created is sufficient to overcome the force of the compression spring 85 and open the valve so that the liquid in the sump 39 will fill the pumping chamber.

The discharge valve means 53, which is disposed in the side outlet 43 of the pump casing, includes a thin circular discharge valve seat 157 having a central hole extending therethrough. The valve seat 157 resides adjacent the end wall of the opening in the side outlet of the pump casing and is sealed thereto via a suitable O-ring 159. A valve closure disc 161 having a flat surface is normally held in abutting relationship to the valve seat 157 by a compression spring 163. The compression spring 163 is connected to the valve closure disc 161 by encircling an end poriton of reduced diameter. The compression spring 163 is located in the desired position in the side outlet opening by a valve stopper 165 having a cylindrical portion upon which the compression spring is seated and an end portion of a larger diameter.

All the foregoing elements of the dischareg valve 53 are held in position in the passageway 51 within the side outlet 49 of the pump casing by a discharge valve guide or spider 157 which has four parallel legs 169 interconnected at the one end, as shown in FIGURE 4. The outer arcuate surface portions of the four legs 167 are provided with external threads 171 which mate with the internal threads 55 in the outlet passageway and thus permit the guide 167 to be screwed into a desired location in the side outlet. As best seen in FIGURES 6-9, the ends of the four legs 169 of the valve guide 167 engage the valve seat 157 at locations along its outer periphery and hold it in sealing relationship against the O-ring 159. In the central cylindrical chamber provided within the interstices of the four legs 169, the valve closure disc 161, the valve stopper 165 and the compression spring 163 are supported. As can be seen, the length of the cylindrical portion of the valve stopper determines the distance the discharge valve can open during the discharge stroke of the pump and so limits the movement of the disc 161 that misalignment of the valve disc and compression spring is avoided.

The illustrated pump 11 is designed to operate to transfer boiling liquids that are maintained in the liquid state by the imposition of both superatmospheric pressure and a lower than ambient temperature. However, it should be understood that the pump could be easily modified by one having the ordinary skill of the art in order to transfer a boiling liquid which is maintained in this condition by the lowering of temperature alone.

As an example, one system employing the pump 11 is illustrated in FIGURE 5, wherein it is used to transfer liquid carbon dioxide from a large tank 175 maintained under about 300 psi. and at about 0 F. In the illustrated system, the pump 11 is located at a vertical level below the liquid level in the tank 175. The tank 175 is connected with the inlet line 47 to the pump 11 via suitable tubing, and the vapor return line 137 from the pump 11 is connected to the tank at a slightly higher vertical level. Accordingly, when the valves (not shown) in the

lines

47 and 137 are opened the sump 39 of the pump 11 is flooded with liquid carbon dioxide. If the pump 11 is operated in close proximity to the storage tank 175, the hydraulic head of the liquid may be relied upon to keep the sump 39 full at all times. Moreover, if the pump 11 is close to the storage tank 175, the vapor return line 137 may be eliminated, and the vapor fraction, which invariably accompanies liquid near its boiling point, may be allowed to return to the storage tank by bubbling back through the supply line 47 or may be permitted to pass with the liquid through the pump. Of course, if no vapor return line is provided, in order to begin the pumping operation, the discharge from the pump will be bled to atmosphere until the sump has been filled and liquid is being pumped.

In the system illustrated in FIGURE 5, the pump 11 is being operated at a location remote from the tank 175. In such an instance, it is preferred to use an auxiliary, low pressure, high capacity pump 177 in the supply line at a location fairly close to the storage tank. Such a pump is commonly referred to as a fore pump. The function of the fore pump 177 is to circulate the boiling liquid from the storage tank 175 through the continuous circuit formed by the supply line 47, the sump 39, and the vapor return line 137. The fore pump 175 is normally operated to circulate a greater amount of liquid than the pump 11 In such an instance, it is preferred to use an auxiliary, low at all times.

The materials of construction of the pump 11 are of course dependent upon the intended use of the pump. It is well known in the art that a pump for transferring liquid helium or oxygen will usually be made of different construction materials than one intended to pump Freon or ammonia. The pump herein described is particularly constructed to transfer liquid carbon dioxide; and accordingly, the various materials of construction mentioned herein may be considered to be representative for a pump of this intended use. Where the particular materials of construction are not mentioned, suitable materials well known to the art are used.

In the operating the pump 11, the valves to the storage tank 175 are opened, and the sump 39 is filled with the boiling liquid to be transferred. When the supply line 47 and the vapor return line 37 are filled with liquid, a pocket of vapor is trapped in the threaded cap and the upper arm 131 of the T member 129. The vapor pocket is disposed axially above the plunger 15, and this pocket of vapor constitutes the surge chamber 141. To assure that there is always a pocket of vapor in this region, even if the boiling liquid being pumped into the sump 39 is slightly supercooled, the T 129 and the cap are made of a material having a relatively low thermal conductivity, as for example compared to cast iron which is one suitable material for the pump body 12. For example, stainless steel may be used for the T 129 and cap 133. By so preventing rapid heat transfer from the upper arm 131 of the T 129, it is assured that the vapor pocket is not condensed by the supercooled liquid.

After the sump 39 is filled, the motor is actuated to drive the plunger 15 in reciprocating motion, and pump ing begins. In the positions illustrated in FIGURES 1 and 6, the plunger 15 has just completed the intake stroke and is about the reverse direction. At this instant, both the intake valve 33 and the discharge valve 53 are closed.

FIGURE 7 shows the pumping chamber 31 just after the plunger 15 has reversed direction and begun its downward discharge stroke. As the piston head 17 moves downward, thereby squeezing the substantially incompressible liquid in the toroidal pumping chamber 31, the pressure in the chamber quickly exceeds the pressure in the outlet or discharge line 57, and the discharge valve 53 opens. In opening, the valve closure disc 161 is moved to the righthand side, overcoming the force of the compression spring 163, and permitting the liquid in the pumping chamber 31 to flow outward between the closure disc 161 and the valve seat 157. The liquid passes through the open region between the four legs of the valve guide 167 and eventually into the dicharge line 57.

The intake valve ball 35 remains seated so that the valve 33 is closed throughout the entire discharge stroke.

stroke. As previously indicated, fluid communication between the region below the ball 35 and the pumping chamber 31 is established via the eight generally radially extending holes 149 in the sidewall of the plunger 15, the generally shallow relief 155, and the plurality of holes 153 in the lower portion of ball spacer 89.

FIGURE 8 shows the pump 11 where the plunger 15 has reached the bottom of the discharge stroke. At this instant, the hydraulic pressure on both sides of the discharge valve disc 161 is equalized, and the compression spring 163 causes the disc to move to the left and close the discharge valve 53.

At the beginning of the intake stroke, as the plunger 15 begins to move upward through the sump 39 which is full of liquid, a high pressure zone is created generally adjacent the surface of the ball seat 37 as the piston head begins to move into a region occupied by an incompressible liquid. This high pressure zone is directed toward the intake valve ball and the pumping chamber by the interior generally conical shape of the ball seat 37, there by causing the opening of the intake valve 33, assisted by the inertia of the mass of the ball 35 in the surrounding liquid environment. The net result quickly overcomes the force of the compression spring and the residual pressure in the pumping chamber 31 and separates the ball 35 from the ball seat 37. The timing of the opening of the valve 33 with reference to the beginning of the intake stroke is a function of the linear velocity or acceleration of the piston head 17, the compressive strength of the compression spring 85, the mass of the hall (dependent upon the material from which it is made), the density and viscosity of the liquid which fills the sump 39, and the restrictions preventing the liquid from leaving the sump. All other factors being equal, the higher the speed at which the pump plunger is driven, the higher will be the pressure of the high pressure zone that is created. Therefore, if the pump 11 is designed to operate at a slower speed, a ball of larger mass may be employed to increase the assist from the inertia factor in opening the valve 33.

For the illustrated pump 11 which is designed to transfer liquid carbon dioxide at about 300 psi. and about 0 F., a ball 35 injection-molded of nylon having a diameter of 1 inch and a mass of about 9.7 grams and a compression spring 85 having a spring constant of about A per ounce are used. This combination is considered to be especially suitable for use in a pump designed to operate at a shaft 25 speed of about 500 to about 1200 revolutions per minute, and having a piston stroke of about 0.18 inch. Using this combination of ball and spring, the ball 35 is quickly displaced from the intake valve seat 37, opening the intake valve so that the liquid is forced therethrough into the ever-enlarging pumping chamber 31 by the high pressure zone as the piston head 17 continues its upward travel.

As should be clear from FIGURES l and 6, the gap between the ball 35 and the concave socket 81 provided in the ball restrainer 79, is less than the stroke of the piston. The mass of the ball 35 and the strength of the compression spring 85, discussed above, are also chosen so that the force of the spring is sufiiciently overcome so that ball 35 is seated in the socket 81 during the upward movement of the piston head 17 on the intake stroke. This position is shown in FIGURE 9 wherein the plunger 15 is illustrated after it has completed about two-thirds of its travel on the intake stroke. By having the ball 35 9 seated in the socket, and thus engaged by the ball restrainer 79 during the intake stroke, the ball rides with the restrainer 79 during the final portion of the intake '-stroke of the plunger. Thus, the ball 35 is given momentum which helps it to quickly close the intake valve 33 (working in combination with the force provided by the compression spring 85) as soon as the plunger reaches the end of the intake stroke. Preferably, the ball 35 is not engaged by the socket 81 until the plunger is on the last half of its stroke, when it will be decelerating, so that it is not given too much momentum which could cause it to rebound from the valve seat 37 and chatter, thus reducing volumetric efficiency.

The construction of the piston head 17 is such that the volume of liquid in the sump 39 displaced by the upward movement of the piston head and intake valve components is greater than the volume of liquid that can be accepted by the toroidal pumping chamber 31. This feature, plus providing the end of the piston head and the associated intake valve seat with an inwardly opening funnel-shaped entry portion, assures that complete filling of the pumping chamber 31 takes place on each intake stroke, Preferably at least about 10% more liquid is displaced than can be accepted. The illustrated pump 11 displaces an excess 'of: about The displacement of a greater amount of liquid than can be accepted by the pumping chamber 31 to accomplish this complete filling inherently causes the high pressure zone of liquid that is created, as hereinbefore discussed, to result in the formation of a high pressure wave which moves upward in the sump, in the same direction asthe upward axial movement of the piston head on the intake stroke. If not otherwise accommodated, this high pressure wave may cause a backup of the liquid .in the intake line. The occurrence of such a backup in the intake line during the time of the next intake stroke will hamper complete filling of the pumping chamber 31. However, when boiling liquids are being pumped, it is considered that there will often be sufficient vapor bubbles in the intake line to absorb a significant portion of the energy of the pressure wave. In such a case, the surge chamber may be omitted; however, its inclusion should further insure favorable volumetric efliciency.

To positively prevent such a backup, the surge chamber 141 is provided above the bore 125 provided in the upper cap 20. The bore 125 is coaxial with the plunger 15, and the entrance 139 to the bore is funnel-shaped and flares outward to cover an area nearly equal to the area of the cross section of the piston head 17. Preferably,

the area circumscribed by the circumference of the outer periphery of the funnel-shaped entrance 139 is equal to at least about 75% of the cross sectional area of the piston head 17. The funnel-shaped entrance 139 directs the upwardly moving high pressure wave generally into the region of the central bore 125. The bore 125 is axially in line with the plunger and leads to the surge chamber 141 which, in the illustrated embodiment, is directly vertically thereabove.

When the pump 11 is operating, the liquid level in the upper arm 131 of the tee is at about the dotted line L shown in FIG. 1, with the region thereabove being filled with the trapped vapor. Within the region of the bore 125, the high pressure wave is instantaneously embodied as a moving column of liquid. When this high pressure wave reaches the surge chamber 141, the trapped vapor in the surge chamber serves as a cushion to halt the fluid movement in this direction by first absorbing its momentum by compression of the vapor in the surge chamber. Then, a reversal occurs when the compressed vapor expands, causing fluid movement in the opposite direction back toward the piston head 17 and intake valve.

In order to halt the undesirable fluid movement away from the sump 39 by dissipating the high pressure wave and preferably to reverse its direction to movement back toward the plunger by the time the following discharge stroke is completed and the next intake stroke begins, the distance from the surge chamber 141 to the plunger s kept within a permissible maximum. Obviously, this is a matter of timing and accordingly is dependent upon the contemplated speed at which the pump 11 is to be run. For example, in a pump of this type which will operate at 300 reciprocations per minute, the distance from the plunger 15 to the surge chamber 141 may be greater thanun a like pump operating at 600 reciprocations per minute. However, in general, it is considered thatproximity of the surge chamber 141 to the piston head 17 is not detrimental so that a surge chamber located to be suitable for a pump operating at 600 reciprocations per minute is also suitable for operation at 300 reciprocations per minute.

Direction of the upwardly moving high pressure wave into the surge chamber 141 rather than into the intake line is facilitated by locating the funnel-shaped entrance 139 to the surge chamber 141 in direct axial alignment with the plunger 15 and is also facilitated by the placement of the entrance from the liquid inlet line generally out of axial alignment with the plunger. In the illustrated pump 11, the ring-shaped passageway 43 which surrounds the axially aligned surge chamber entrance 139 provides for a good supply of liquid to the entire sump 39 through a non-axially aligned entrance passageway. Moreover, preference of the high pr ssure wave for the surge chamber rather than the inlet line is also furthered by maklng the entrance area to the surge chamber (ie the circular area surrounded by the larger end of the funnel-shaped portion 139) larger than the cross sectional area of the ring-shaped passageway 43.

As an optional feature, a barrier disc 181 may be disposed between the top of the pump casing 13 and the underside of the upper cap 20. The barrier disc 181 contalns a plurality of orifices 183 of a particular design which prefer fluid flow therethrough in one direction over fluid flow in the opposite direction. The illustrated disc 181 is formed with venturi-shaped orifices 183, i.e., orifices which have a boundary surface of the shape of a hyperbolic surface of revolution, as best seen in FIG. 3. The orifices 183a in the area of the entrance to the surge chamber, i.e., those generally in the central region of the barrier disc 181, are formed with their wider openmg portions facing downward. The orifices 183]) in the peripheral region of the plate, which are immediately below the ring-shaped passageway 43, are arranged with their wider opening portions facing upward.

In general, the orifices 183 cover the entire disc 181 so as to keep the throttling effect of the disc 181 as low as possible. However, the disposition of the barrier disc to partially close the top of the sump 39 and provide some restriction to fluid flow upward therefrom is desirable, otherwise the center area where the orifices 183a lie could be left as merely an open hole the size of the entrance 139. This throttling effect assures that a hig pressure zone sufiicient in pressure to open the intake valve 33 on the intake stroke is created and is not immediately dissipated, as for example the case might be if the pump were operating at very slow speeds and/0r there was a very short hydraulic head above the sump so. that the liquid in the sump might more easily move with piston head 17.

As a result of the arrangement of the orifices 183b, the resistance provided to inlet flow of the liquid from the ring-shaped passageway 43 downward into the sump 39 is kept Within acceptable limits. However, the orifices 1831; provide an effective barrier to flow in the upward direction which could be caused by the high pressure wave. Thus, a further preference for upward flow into the surge chamber 141, rather than into the inlet line, is accomplished.

As previously indicated, the disposition of the concave socket 81 in the ball restrainer 79 only a short distanc below the ball 35 limits the distance the intake valve 33 can open and also imparts momentum to the ball. Therefore, as soon as the plunger 15 reaches the top of its stroke and the upward movement of the piston head 17 stops, the ball 35 continues upward due to its momentum and thus quickly closes the intake valve, assisted by the compression spring 85. At this point, the pumping chamber 31 is completely filled, and the position of the pump components is as shown in FIGURES 1 and 6, ready for the next discharge stroke to begin.

As previously stated, the pump 11 can be employed to pump various boiling liquids. The illustrated pump 11 has been used to transfer liquid carbon dioxide at an inlet pressure of about 300 psi and a temperature of about 0 F., pumping the liquid carbon dioxide at a discharge pressure of about 800 p.s.i. Such a pump having a piston head of about 2.23 inches, :1 piston rod diameter of about 1.5 inches and a stroke of 0.15 inch, driven by an electric motor and a gear transmission turning the shaft at about 500 r.p.m. will discharge about 0.8 gallon of liquid carbon dioxide per minute at 800 psi.

Moreover, as can be seen from the previously described operation, on the intake stroke the force the pump 11 is working against is equal to the cross sectional area of the piston rod (actually the cross sectional area of the piston head less the cross sectional area of the pumping chamber 31) (1.77 sq. in.) times 300 p.s.i.g. (the pressure in the sump) or about 530 pounds. On the discharge stroke, the pump works against a force approximately equal to the discharge pressure of 800 p.s.i.g. times the cross sectional area of the pumping chamber 31 (about 2.12 sq. in.), or a force of about 1695 pounds. However, on the discharge stroke of the pump, the movement of the plunger is aided by the 300 p.s.i.g in the sump 39 operating on the upper end of the piston head, i.e., 300 p.s.i.g. x 3.89 sq. in. or 1165 pounds. Thus, only the differential force must be overcome on the discharge or pumping stroke, equal to 1695 pounds minus 1165 pounds or about 530 pounds. However, because on the discharge stroke the pressure-energized packing is more heavily loaded, there may be slightly more frictional force to be overcome so that the total work performed on the discharge stroke may slightly exceed that done on the intake stroke. However, the maximum work which must be done by the drive means is considerably less than it would be if, on the discharge stroke, the force being overcome was proportional to the difference between atmospheric pressure and the discharge pressure, as is the case in many pumps. Accordingly, because the maximum work being performed is lower, a motor of correspondingly lower capacity may be employed. Also, because work is being done on both the intake and discharge strokes, more efficient use is made of the motor and the gear transmission.

In order to obtain a truly practical advantage from this feature in a pump, the efiective cross sectional area of the piston head (perpendicular to its axis) should normally be at least double that of the pumping chamber. It is considered that one would usually balance the proportion such that the force exerted upon the plunger by the liquid in the sump is at least one-third the product of the cross sectional area of the pumping chamber times the discharge pressure. Preferably, full advantage is taken by having the liquid in the sump exert a force greater than one-half the specified product so that, taking the increased frictional force on the discharge stroke into consideration, the work done on the two strokes can be nearly balanced, as indicated above, and a motor of proportionately lower power can be used.

In the operation of the illustrated pump 11, the surge chamber 141 is coaxial with the plunger and, under continuous operating conditions, the liquid level in the T 129 extends sightly above the branch arm 135 which connects with the vapor return line 137 to about the level L shown on FIG. 1. The distance from the liquid level L vertically to the top of the piston head 17 at the end 12 I of the intake stroke measures about 3 to 4 inches. The internal diameter of the T member 129 which screws into the bore measures slightly less than one inch, and the larger diameter of the funnel-shape entrance 139 measures about 1% inches. This arrangement is found to perform satisfactorily in the pump 11 when the shaft 25 is driven between about 500 r.p.m. and 1200 rpm.

As previously mentioned, although the pump 11 has been described with the plunger reciprocating vertically, which is its preferred orientation, it may be operated with the piston reciprocating horizontally or at an angle. If the pump 11 is operated with a horizontal orientation, the surge chamber 141 may simply be provided by connecting an elbow to the arm 131 of the T 129 and screwing the cap 133 on the end of the elbow. The vapor pocket for the surge chamber 141 is then formed in the upstanding leg of the elbow, and the surge chamber functions in substantially the same manner as that hereinbefore described. Of course, to merely modify the illustrated pump 11 in this manner would slightly increase the distance from the liquid level L to the plunger 15, and accordingly, depending upon the speed at which it is desired to run the pump, it may be desirable to shorten the other dimensions of the T to compensate for this slight change in distance.

Although the invention has generally been described with reference to the specific pump 11 illustrated in the drawings, it should be understood that such modifications as would be obvious to one having the ordinary skill in the art are within the scope of the invention which is defined in the appended claims. For example, the surge chamber may be omitted, as previously indicated, and the pump may still operate economically. Various features of the invention are described in the claims which follow.

What is claimed is:

1. A positive displacement reciprocating pump for transferring liquids under superatmospheric pressures, which pump comprises a pump body having a pumping chamber therein, a pump plunger axially movable in said pump body, a sump formed in said pump body which is adapted to connect with a source of liquid at superatmospheric pressure, inlet valve means between said sump and said pumping chamber, and discharge valve means between said pumping chamber and a discharge outlet, said sump being separated from said pumping chamber by at least a portion of said plunger so that the liquid in said sump exerts a force on said plunger in the same axial direction in which-said plunger moves during its discharge stroke, said pump plunger being proportioned so that the effective cross sectional area of said plunger against which the liquid in said sump bears is substantially larger than the cross sectional area of said pumping chamber so the force exerted on said plunger by the liquid in said sump materially assists the plunger discharge stroke thereby substantially lessening the work which would otherwise be required to drive said plunger on said discharge stroke, and means for reciprocatingly driving said pump plunger.

2. A pump in accordance with claim 1, wherein said plunger is designed to displace at least about 10% more liquid on the intake stroke than said pumping chamber can accept.

3. A pump in accordance with claim 1, wherein an inlet liquid line enters said sumpat a location substantially out of axial alignment with said plunger.

4. A pump in accordance with claim 3, wherein a barrier plate having orifices formed therein is disposed to divide said plunger from said inlet line, which orifices are shaped to prefer liquid flow from said inlet line toward said plunger as opposed to flow in the reverse direction.

5. A pump in accordance with claim 1, wherein the proportioning of said plunger is such that said force exerted by the liquid in said sump is greater than one-half the discharge pressure times said pumping chamber cross sectional area so that the work done by said drive means on both strokes is nearly equal.

6. A pump in accordance with claim 1, wherein said pumping chamber is generally toroidal in shape and is disposed exterior of said plunger at a location between the outer surface of said plunger and said surrounding pump body.

7. A pump in accordance with claim 6, wherein said intake valve is disposed within and carried by said plunger and wherein generally radially extending passageway means in said plunger links said pumping chamber in fluid communication with the port of said intake valve,

8. A pump in accordance with claim 7, wherein said intake valve contains a movable ball which is springbiased to a position closing said intake valve port and which opens inertially on the intake stroke of said plunger.

9. A pump in accordance with claim 8, wherein means is provided for limiting the distance said ball can move in opening said intake valve.

10. A pump in accordance with claim 8, wherein passageway means is included in said plunger for connecting substantially the entire region wherein said intake valve ball resides in fluid communication with said pumping chamber.

11. A pump in accordance with claim 9, wherein said limiting means comprises a socket into which said ball is seated and which socket is spaced from said port a predetermined distance so that said ball becomes seated therein during the last one-half of the intake stroke of said plunger whereby said ball is provided with momentum which facilitates the rapid closing of said intake valve upon completion of the intake stroke.

12. A pump in accordance with claim 11, wherein said socket-providing means includes passageway means for facilitating the exit of liquid from the region of said socket during said intake stroke.

13. A pump in accordance with claim 2 wherein a surge chamber is provided in association with said sump and extending from said sump in the direction of movement of said plunger on the intake stroke thereof, said surge chamber including a trapped pocket of gas and the distance between said surge chamber and the nearer end of said plunger being short enough so that a high pressure wave created by displacement of excess liquid on said in take stroke is dissipated or changed to movement toward such plunger by about the time said next intake stroke begins, wherein a passageway leading to said surge chamber is coaxial with said plunger and has a funnel-shaped entrance facing the head of said plunger, the area bounded by the larger end of said funnel-shaped entrance equaling at least about 75% of the cross sectional area of said plunger head, wherein an intake liquid line enters said sump through a ring-shaped passageway which surrounds said surge chamber entrance and which is substantially out of axial alignment with said plunger, wherein said pumping chamber is generally toroidal in shape and is disposed at a location between the outer surface of said plunger and said surrounding pump body, wherein said intake valve is disposed within and carried by said plunger and contains a movable ball which is springbiased to a position closing an intake valve port which ball opens inertially on the intake stroke of said plunger, wherein passageway means in said plunger links said toroidal pumping chamber in fluid communication with the port of said intake valve and substantially the entire region wherein said ball resides, wherein said plunger includes means providing a socket for limiting the distance said ball can move in opening said intake valve, said socket-providing means having passageway means formed therewithin for facilitating the exit of liquid from the region of said socket during said intake stroke, and wherein said drive means for reciprocating said plunger is connected to the end of said plunger opposite from said plunger head.

14. A positive displacement reciprocating pump for transferring boiling liquids that discharges only on one stroke, which pump comprises a pump body, a pump plunger axially movable in said pump body, a pumping chamber formed exterior of said plunger between the outer surface thereof and said pump body, a sump formed in said pump body, a discharge valve leading from said pump chamber for opening and closing an outlet therefrom, and an intake valve for opening and closing an otherwise open entrance from said sump to said pumping chamber, said intake valve being disposed within and carried by said plunger, and said plunger being designed to displace at least about 10% more liquid on the intake stroke than said pumping chamber can accept to assure complete filling of said pumping chamber on the intake stroke.

15. A pump in accordance with claim 14, wherein said intake valve contains a valve seat which defines an intake valve port and a movable ball which is spring-biased to a position closing said port, said ball being disposed so that it moves from said intake valve port in a relative direction opposite to the direction in which said plunger moves on the intake stroke, and said valve seat being formed to direct the high pressure zone which is formed by movement of said plunger through the liquid-filled sump toward said ball.

16. A pump in accordance with claim 15, wherein barrier means extending across said sump sufl'lciently restricts liquid movement from said sump in the direction of movement of said plunger on said intake stroke to assure that a high pressure zone is created which will quickly open said intake valve.

17. A pump in accordance with claim 14 wherein said intake valve is disposed Within and carried by said plunger and contains a movable ball that is spring-biased to a position closing an intake valve port, said ball being designed to inertially open said port on the intake stroke of said plunger, and wherein means is provided for limiting the distance said ball can move in opening said intake port, said limiting means including a socket into which said ball is seated, which socket is spaced from said port a predetermined distance so that said ball becomes seated therein during the last one-half of the intake stroke of said plunger whereby said ball is provided with momentum which facilitates the rapid closing of said intake valve upon completion of the intake stroke.

18. A pump in accordance with claim 14 for pumping liquids under superatmospheric pressure, wherein drive means for reciprocating said plunger is connected to the end of said plunger opposite from the head end of said plunger which enters said sump so that the pressure in said sump bears against said plunger head during said pump discharge stroke.

19. A pump in accordance with claim 18, wherein the cross sectional area of said plunger head is larger than the cross sectional area of said pumping chamber.

20. A pump in accordance with claim 14, wherein a surge chamber is provided in association with said sump and extending from said sump in the direction of movement of said plunger on the intake stroke thereof, said surge chamber including a trapped pocket of gas and the distance between said surge chamber and the nearer end of said plunger being short enough so that the high pressure wave created by displacement of excess liquid on said intake stroke is dissipated or changed to movement toward such plunger by about the time said next intake stroke begins, wherein a passageway leading to said surge chamber is coaxial with said plunger and has a funnelshaped entrance facing the head of said plunger, the area bounded by the larger end of said funnel-shaped entrance equaling at least about 75 of the cross sectional area of said plunger head, wherein an intake liquid line enters said sump through a ring-shaped passageway which surrounds said surge chamber entrance and which is substantially out of axial alignment with said plunger, wherein said pumping chamber is generally toroidal in shape, wherein said intake valve contains a movable ball which is spring-biased to a position closing an intake valve port which ball opens inertially on the intake stroke of said plunger, wherein passageway means in said plunger links said toroidal pumping chamber in fluid communication with the port of said intake valve and substantially the entire region wherein said ball resides, wherein said plunger includes means providing a socket for limiting the distance said ball can move in opening said intake valve, said socket-providing means having passageway means formed therewithin for facilitating the exit of liquid from the region of said socket during said intake stroke, wherein the cross sectional area of said plunger head is larger than the cross sectional area of said pumping chamber, and wherein drive means for reciprocating said plunger is connected to the end of said plunger opposite from said plunger head.

21. A positive displacement reciprocating pump for transferring liquids, which pump comprises a pump body having a pumping chamber formed therein, a pump plunger axially movable in said pump body, said plunger being designed to displace at least about 10% more liquid on the intake stroke than said pumping chamber can accept, a sump formed in said pump body, an intake valve for opening and closing an otherwise open entrance from said sump to said pumping chamber, and a surge chamber in open fluid association with said sump and extending from the sump in the direction of movement of said plunger on the intake stroke thereof.

22. A pump in accordance with claim 21, wherein the distance between said surge chamber and the nearer end of said plunger after completing said intake stroke is short enough so that the high pressure wave created by displacement of excess liquid on said intake stroke, which wave therefore moves in the direction of movement of said plunger on the intake stroke, is dissipated or changed to movement toward said plunger by about the time said next intake stroke begins.

23. A pump in accordance with claim 22, wherein said surge chamber includes a trapped pocket of gas.

24. A pump in accordance with claim 21, wherein a passageway leading to said surge chamber is coaxial with said plunger.

25. A pump in accordance with claim 24, wherein the entrance to said surge chamber passageway is funnelshaped and faces the head of said plunger.

26. A pump in accordance with claim 25, wherein the entrance to said surge chamber is frustoconical in shape having a larger end of a diameter at least equal to the diameter of a circle having an area about 75% of the cross sectional area of said plunger head.

27. A pump in accordance with claim 21, wherein an inlet liquid line enters said sump at a location substantially out of axial alignment with said plunger.

28. A pump in accordance with claim 27, wherein said entry of said inlet line is through a generally ring-shaped passageway which is located in surrounding relationship to said surge chamber entrance.

29. A pump in accordance with claim 27, wherein a barrier plate having orifices formed therein is disposed to divide said plunger from said inlet line, which orifices are shaped to prefer liquid flow from said inlet line toward said plunger as opposed to flow in the reverse direction.

30. A pump in accordance with claim 29, wherein said orifices are venturi-shaped.

31. A pump in accordance with claim 21 wherein said passageway leading to said surge chamber is at least partially axially aligned with said plunger.

References Cited UNITED STATES PATENTS 57,412 8/1866 Van der Weyde 103-224 2,837,898 6/1958 Ahlstrand l03-l78 ROBERT M. WALKER, Primary Examiner.

US. Cl. X.R. 103224 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,430,576 March 4, 1965 Lewis Tyree, Jr.

It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 70, "proved" should read provide Column 4, line I before "ball restrainer" insert the line 67, after "O-ring insert 105 Column 6, line 36, dischareg" should read discharge Column 7, line 26, cancel "In such an instance, it is preferred to use an auxiliary, low and insert in the circuit is pumping; thus the sump 39 is kept full line 40, cancel "the", first occurrence.

Signed and sealed this 14th day of April 1970.

(SEAL) Attest:

Edward M. Fletcher, Jr. E.

Attesting Officer Commissioner of Patents