US1727168A - Fluid pump - Google Patents

Description

Sept. 3, 1929. n B. GREENFIELD FLUID PUMP Filed Dec. 12, 1925 venience tion is to provide Patented Sept. 3, 1929.

Uhll'llD STATES PATENT Oli'lilClE..y

BENJAMIN GREENFI'ELD, GI JACKSON HEIGHTS, NEW YORK, ASSIGNGR T0 COMBUS- IION UTILITIES CUREORATION,

F NEVI YORK, N. Y., A CORPORATION OF MAINE.

FLUID PUMP.

Application filed December The present invention relates to fluid pumps and more particularlyv to a novel flow restricting device designed for use in fluid feed systems supplied by high speed pumps.

lecausc they lend themselves readily to thermostatic vand similar automatic control and for many other reasons, electric motors are looked on Vith favor as the prime movers for fluid pumping units7 in particular those of small capacity. In many inst-ances7 however, the constant high speed characteristics of electric motors militates against their use as prime movers for small pumping units. For instance, it has been found iinpractieable to build either the reciprocating plunger or the revolving fan, gear or `rotor types of pumps in high speed (motor units of such small capacity as to' driven) deliver 'fluid only at the extremely low rate at which it is commonly used by domestic heating and rcfrigerating systems or the like. In order to use an electric motor as the prime mover for a pump supplying fluid at very low rates to a domestic house heater refrigeration system, it has been proposed to install a pump of a'larger and more convenient capacity and to allow the pump to build up high pressures behind an extremely small fixed orificey mounted in the delivery line from the pump. However, experience `has shown that the extremely small pinpoint orifices which it is necessary te use in the delivery line of 'a motor driven pump of convenient'siae 1n order to deliver fluid to a domesticoil burning furne-ce for instance, only at the rate required, are very unreliable and unsatisfactory because they freiuently. clog up with dust, rust scale and other foreign matter carried by the working fluid7 with consequentv interruption of the feed and great inconto the householder. c The' primary object of the present invena flow restricting device which will give satisfactory and reliable service when used iii fluid feed systems supplied by high speed pumps of the convenient capacity above referred to..

llith this object in view one feature of the invention contemplates a flow restricting device which will act to suitably limit the amount of fluid delivered-to a vfeed system by high speed pumping units and which is Ving constant speed 'driving arpump7 so designed that its best Serial No. 74,950.

.to the absence of such small pinpoint ori-A fices as are subjectk to stoppage.

Villiers the fluid feed requirements of a domestic heating system, for instance, vary over a wire range7 such combinations ofv high speed pumps and pinpoint orifices as are commonly employed for supplying fuel to such units willnot function satisfactorily unless some provision is made either for varying the speed and capacity of the pump er the volume of fluid passed by the orifice. In `Huid feed systems supplied by pumps a variation in the capacity of the pump is ordinarily accomplished either by varying the speed of the primemover driving the pump oi'` by varying the speed ratio between the prime mover and the pump. rllhus when a greater or decreased amount of fluid is required by the system the speed of the prime mover is changed accordingly, and whenever it is'desired to build up or reduce pressure on the discharge side of the pump the speed of the prime mover isincreased or decreased accordingly,` thereby increasing or decreasing the load on the pump and the amount of fluid handled by the pump. When an electric motor or other prime mover havcharacteristics is used for performance is attained at a high speed, additional equipment (such as rheostats, reduction gearing, etc.) must be employed if it is desired to run the pump at varying speed.

Another object of the present invention is to provide a` device for suitably governing the rate at which fluid is Adelivered t0 a feed system including a flow restricting device by a pumping unit having constant high speed characteristics.`

y N ith this object in view another feature of the invention contemplates the combination with a pump of convenient capacity having constant v speed characteristics' and arranged to deliver fluid through a reliable liowvrestricting deviceto a feeding system, of means for returning excess fluid handled by the pump from the delivery to the suction side of the pump, and a device acting in conjunction withsaid return means for proportioning the amount of fluid passed by the flow restricting device to the feed system in accordance with the varying demand on said system, without changing the speed of the prime mover driving the pump or the speed ratio between the prime mover and the pump. V

With these and other objects and features in view the invention consists in the novel flow restricting attachment for iiuid feed systems supplied by high speed pumps hereinafter described and part-icularly defined in the claims.

The various features of the invention are illustrated in the accompanying' drawings, in which Fig. 1 is a vertical sectional View with parts in elevation showing a standard type of fluid pump having a iow restricting device of the type embodying the preferred form of the present invention attached between its discharge chamber andthe delivery line;

Fig. v2 is a cross sectional view taken through the flow restricting attachment on vthe line 2 2 of Fig. 1, lookingin the direction of the arrows;

Fi 3 is a cross sectional view of the body ofthe pump taken on the line 3 3 of Fig. 1 looking in the direction of the arrows;

Fig. 4 is a cross sectional view through .the pump illustrating the flow governing ai'- rangement7 taken on the line 4-4 of Fig. 1 looking in. the direction of the arrows. and Fig. 5 is a cross sectional view of a closed gas chamber positioned on the delivery line of the pump for absorbing pulsations in the fluid supply.

In the drawings the numeral 10 indicates an electric motor having a shaft 12 coupled in alignment with the shaft 14 of a fluid pumping unit 16 by means of a flexible coupling 18. The motor 1() is designed to serve Y as the prime mover for pump 16 and is preferably of some suitable ystandard type. The

" pump 16 shown in the drawings is of the valveless oscillating rotor type, and while the design of and principle underlying this pump forms no part of the present inven` tion it will be hereinafter described as an aid to understanding t-lie invention.

The assembly of the pump 1G includes three main castings, namely a'central casting 2O housing the main body of the pump and enclosing a working cylinder 22 (see Fig. and two additional castings 24 and 26 which form respectively the end plates'for the `pump and working cylinder 22 and also serve to'hoiise bearings 28 and 30 in which the drive shaft 14 is ljournaled. Casting 26, which forms the end'plate of the pump lying nearest the motor 10, is provided with a ing base 34 on the motor.

mounting base 32 toinatch up with a mount- The mounting bases 34 and 32 of the motor and pump are kboth pi'eferably'tightly ybolted to a common base plate '36. Likewise the threecastings make up the pump assembly are preferably firmly bolted together and have their adjacent bearing 'surfaces `machined to forni tight leakage yon so as to ifill mostof the space enclosed by walls 42 of cylinder 22 between the inner surfaces of end plate castings 24 and 26. A cui'ved link 44 having knobs 46 at each end V(see Fig. 8) serves asia partition separating the suction side from the discharge side of the pump. ln order to suitably perform this function, link 44 has a depth equal to the length of cylinder 22 as measured by the distance separating the inner walls of castings 24and l26 (see F 1) and the knob 46 at one end of the link is journaled ina cylindrical groove 48 in pump casting 2O while the knob 46 at the other end' of link 44 is similarly jouriialed in a cylindrical groove 50 in the outer periphery or" the piston 40.

In operation fluid enters the suction side of the pump preferably from an' underground storage (not shown) through a feed pipe 52, which is threaded into a port 54 in castingpQO. From port 54 fluid enters a suction chamber 56 on the upper sider of link thil'ough a connecting port 58 and is continually pushed around the pump cylinder in a small clearance space 6() formed between the outer rim of piston 40 and the cylinder walls to a discharge or pressure chamber 62 on the underside of link 44. rlfhus as the pump shaft 14 rotates piston 40 wipes the inside of cylinder walls 42 with very close clearances but is prevented from turning with the shaft and eccentric Sv by reason of the tact that it is hinged at all times to cast ing 20 by link 44. i The opposite faces of link 44 are preferably machined to form a close sliding contact with the inner bearing surfaces of castings 24 and 26 in order to prevent any leakage between the suction chamber 56 and the discharge chamber 62,

thus permitting the pump to build up rela` tively high pressures whenever necessary.

The flow restricting device embodying the preferred form of the present invention is illustrated in the accompanying drawings as comprising essentially a small ypressure chamber 64 which for convenience may be built right into the end plate casting 2K4 of the pump (see Figs. 1 and 2), although this pressure chamber and the remaining' parts of the present flow restricting device may be attached to the feed system as a unit entirely distinct from the pump itself without departing from the true spirit of the invention. In the drawings an annular passa-ge 66 is shown connecting pressure chamber 62 with a port 68 which opens into chamber 64. A ucry small port 70 leads off from chamber 64 in a diiectionwhich permits it toregister at every revolution of shaft 14 with a radial aperture 72 in said shaft. Aperture 72 is cut through the outer wall of shaft 14 and opens into an axial recess 74 drilled in that end of the shaft which is journaledfin bearing 28. A deliveryv line 76 connects the pump 16 with the fluid feedl system which it is designed to serve, and pipe 76 is shown in the drawings as connected by a street L 7 8 with a port 80 built into casting 24, port 80 and recess 7 4 forming together a reservoir at the head of the feed system.

It has been found'impracticable to build even a pump of the valveless type illustrated in the drawings with sulliciently small clearances so that it can be satisfactorily used at motor speeds to deliver only `thevery limited quantities of fluid required by automatic domestic heating or refrigerating systems. According to the present invention, therefore, the pump for supplying fluid to the feed line of such a system is preferably chosen of a convenient capacity to afford Aeflicient and satisfactory operation and an overflow arrangement is provided whereby fluid handled by the pump in excess of the demands on the feed system may be returned to storage. The overflow arrangement illustrated in the drawings consists essentially of a chamber 82 built into casting 26 and opening` out through a. port 84, preferably into a pipe (no-t shown) for conducting excess fluid handled by the pump back to storage. Chamber 82 is connected by a passage 86 with a cylindrical chamber 88, also builtv into casting 26. A passage 90 shown in dotted lines in Fig. 1 is ported out into chamber 88 at 92 (see Fig. 3) and serves to connect this chamber to a. reservoir 94 in pump casting 20, reservoir 94 in turn coinmunie-ating with the passages 66 and 68 leading respectively to the pump discharge chamber 62 and to pressure chamber 64 of the flow restricting device. Reservoir 94 is normally sealed off at thel top by a plug 95.

Chamber 88 is illustrated in Figs. 1 and 4 as lying in a plane at right angles to the axis ofpump shaft 14 and is also illustrated as lying horizontally, although its position is not important. There is mounted in chamber 88 a piston or plunger 96 and a compression spring 98, spring 98 being arranged to act on one side of piston 96to force it toward vthe right as shown in Fig. 4, but not to the extent of closing port 92. Thus one end of spring 98 bears against piston 96 and the other is fixed to a head 100 on a bolt 102 which is adjustably mounted in a drilled nut 104 closing the left end of chamber 8 8. rlhat end of bolt 102 which projects through the nut 104 is normally covered by a cap 106. A passage 108 ap'- pearing in Vdotted lines in Fig. 4 is built into the walls of cylinder 88 and is ported out at 110 near the right end of the cylinder and again at 112 adjacent passage 86. Although for convenience the chambers 82 and 88 and the other parts of the overflow arrangement have been shown as built into the pump casting, this arrangement does no-tconstitute a ccessary part of the invention and the overflow system may be constructed as a unit separate and distinct from the pump assembly.`

. In operation oil or other fuel handled by the pump after being pushed from suction chamber 56 around cylinder 22 into discharge chamber 62 by the oscillating piston 40, is conducted through passages 66 and 68 into pressure chamber 64. The pressure built up by the pump Vin chambers 62 and 64 is substantially uniform for the reason that the pump is driven at constant speed by motor 10. Likewise a uniform and much lower pressure is built up in recess 74 and port 80 at the head of delivery line 76 as small jets of the fluid in chamber 64 are forced under pressure into recess k'74 each time the rotation of shaft 14 throws aperture 7 2 into register' for an instant with port (see Fig. 2). At the same time thatjliuid from the discharge side of the pump is admitted to chamber 64 of the flow restricting vdevice 'it is also normally flowing` through Y passage 90 and port 92 into the right end of .i

chamber 88, and owing to the pressure built up by the pump in chambers 62, 64 and 88 piston 96 is forced to the left so as to uncover more or less ofthe port 110 appearing in dotted lines in Fig. 8, the parts of the overflow arrangement being illustrated in Fig. 8 in the position which they assume when the'oil pump is not running.

As soon as sufficient pressure is built up at the right-hand end of chamber 88 toopen port 110, iiuid will pass from the right end of the chamber through port 110 andpassage 108 and out through port'112 into that part of chamber 88 on the left of piston 96. In passing from the right hand side to the left vhand side of piston 96 the fluid pressure will drop to substantially zero for the reason that the fluid is then free to pass by passage 86 and chamber 82 into port 84l and thence ,back to the oil storage tank (not shown).

In the drawings the bearing 30 in which i shaft 14 is journaled in casting 26 is shown as completely surrounded by the rfluid in chamber 82. In the event that the pump is used for supplying oil to an oil burner, cross ports 114 are preferably drilled in this bearing so that when the pumpis running, oil leaking through from the pump along between thesha-ft and the bearing will not find its way out of the pump and also so that air will not findy its way along the .shaft past packing gland 116 into the oil pump, particularly when it is idle. When the unit is not operating thel combined effect of the oil return pipe connecting chamber 82 With storage and of the pump suction 'pipe 52 Will maintain an oil pres- `sure at ports 11eL slightly less than atmosplierie. This may cause air to be drawn in along the shaft through stuffing gland 116 and out through ports 114 into chamber 82. Any air thus leaking through into chamber 82 Will pass out through port 84. As airbeen depleted, however, no air can enter thev pump itself nor the feed system of which it is a part. This arrangement is a distinct advantage in any oil burner feed system, since With a direct pump feed from storage to the oil burner a small air bubble passing to the burner operates momentarily to extinguish the flame, Which is obviously to be avoided.

As already pointedout the present flow restricting device is intended to function reliably Without stoppages to `suitably restrict the flow of fluid from a high speed pump Which may have a capacity greatly in excess of the demand. For instance, it is Well known that the amount of oil required by the burner in an installation of a house heating system of less than mammoth proportions makes a very small stream. In orderV to avoid the frequent stoppages resulting from the use of an orifice or pipe of the size needed to keep down the. flow of oil to such a burner to the required amount While at the same time employing a pump of convenient capacity having a thermostatically controlled motor drive, the present invention provides a flow restricting device in Which the smallest aperture may be greatly in excess of the minimum size which it is safe to use to avoid stoppages, for the reason that the device operates to pass fluid through the orifice and; into the feed system during only a very small percentage of the full Working stroke of the pump. With the small pinpoint orifices which are now in common use in the feed systems of domestic oil burners, for instance, the pressures built up at the pump side of the opening are sometimes enormous, Whereas by using a device such as that herein illustrated and described there is no necessity of loading the pump up with high pressures nor isl there any danger of interrupting the feed supply to the system by the stopping up or clogging of any small vorifice with the dustor rust scale carried by the Working `fluid.

The tension on spring 98 can be adjusted by set screw 102 after removing capV 106 to maintain any desired pressure Within practical limits at port and port 92, and by varying the back pressure on the pump and I the size of the drilled port 70, it is possible to regulate the amount of fluid passed to the feed system and to effect this regulation Without using any small pinpoint holes Which are subject to stoppage and hence unreliable. Thus the smallest orifice 70 in the Whole system need never be smaller than about g inch in diameter, because 'fluid is actually passing through this port only about 3%??? of the time. Assuming a motor speed of 1750 R. P. M., moreover, the impulses of fluid entering the feed line 7 6 come so rapidly that the pulsations can be readily absorbed by a small sealed air or gas chamber 118 in the feed line 76 (see Fig. 5).

The feed system described is particularly adaptedl for supplying fuel to oil burners because in addition to allowing for a reliable and continuous flow of oil to the burner under relatively lo-W and uniform pressure it permits of ready adjustment of the pressure and fuel feed in accordance With 'the heat demand on the system. VIt permits of a direct pump feed from underground storage or any other location to the burner and it permits the use of an air tight oil piping system With no outlet tol the air at any point except at the burner tip.

lla\fingl described the invention, what 1s claimed as new is: 1. In a fluid feed system the combination With a pump for supplying fluid thereto, of an aperture device for restricting the floivA of fluid from the pump to rsaid feed system, and an overflow passage intermediate the pump and said flow restricting device to take care of excess'iluid handled lby the pump, the smallest aperture in said flow restricting device through which all fluid delivered by the device flows having a cross-sectional area which is substantially uniformly dimensioned on two major axes intersecting at right angles and free ofv obstruction across the center of the. aperture from one side to the other.

, 2. in a Huid feed system vthe combination with a pump for supplying fluid thereto,

of a device for restricting thequantity of fluid passed from the pump to said system, said device comprising essentially a chamber, a passage connecting said chamber With the discharge side of the pump, a. rotatable shaft jcurnalled in a bearing, an axial recess in the journalled part of said shaft, a passage ported out from said chamber through said bearing and arranged to register at every lrevolution of the shaft with a radial aper-V ture in the recessed part of said shaft, and f neans connecting the axial recess in said shaft With said fluid feed system.

3. In a fluid feed system, the combination with a pump for supplying fluid thereto of a flow restricting device intermediate the pump and said system, said device comprising essentially a chamber, a passage connecting said chamber with the discharge side of ythe pump, a movable closure interposed between said chamber and said feed system, and mechanically operable means acting to intermittently displace said closure to allow a measured volume of fluid to pass from said chamber to said feed system.

l. In a fluid fuel system the combination with a pump for supplying fluid thereto, of a flow restricting device intermediate the pump and the system and an overflow arrangement intermediate the discharge side of the pump and said flow-restricting device, said arrangement including a chamber, a passage .connecting one end of said chamber with the pump side of the flow restricting device, a by-pass ported out in said chamber at two points, a plunger arranged to operate in said chamber between the ports of said by-pass under the back pressure built up on the pump, a compression spring arranged to act on said plunger in opposition to the pump pressure, and means for adjusting the tension on said spring to vary the back pressure built up on the pump and the amount of fluid passed through said bypass overflow arrangement.

5. In a fluid feed system the combination with a pumpfor supplying fluid thereto, of a device for restricting the flow of fluid from the pump tov said system, said device comprising essentially a rotatable shaft having its free end liournalled in an end plate of said pump, a pressure chamber housed in said end plate, a passage connecting said ch mber with the discharge side of the pump` another passage ported out from said chamber through the bearing in which said shaft is journalled, an axial recess in the journalled end of said shaft, a radial aperture in the wall of the recess arranged to register at every revolution of the shaft with the port in said bearing, and aconnection between the axial recess and said fluid feed system.

6. The combination with a valveless, oscillating rotor pump of the cla-ss described, of a flow-restricting device intermediate the discharge side of the pump and a delivery line from the pump` said device being built into the end plate of the pump housing the bearing in which the free end of the drive shaft is journalled and comprising essentially a pressure chamber, a passage connecting said chamber with the discharge side of the pump, another passage ported out from said chamber through the bearing in which said shaft is journalled, an axial recess in the end of said shaft, a radial aperture in the wall of said recess arranged to register at every revolution of the shaft with the port in said bearing, .and a connection between said axial recess and the delivery line from the pump.

7. In a fluid feed system the combination. with a pump and a delivery line leading from the discharge side of the 'pump to said system, of a device intermediate the pump and said delivery line for restricting the flow of fluid from the pump to the feed system,` and overflow means intermediate the pump and saidflow-rest-ricting device for taking care of fluid handled by the pump in excessof that passed tothe delivery line, said means comprising a chamber housed in an end plate of the pump, a return passage ported out from said chamber, another passage connecting said chamber with the pump side of the flow restricting device, and a pressure, relief valve intermediate said flow restricting device and said chamber.

8. The combination with a valveless oscillating rotor pump of the class described of 'a flow restricting device built into that end plate of the pump housing the bearing in which the free end of the drive shaft is journalled, an overflow chamber built into the other end plate of the pump, a passage connect-ing one end of said chamber with the pressure side of said flow restricting device, an overflow port opening out from the other side of said chamber, and a pressure relief valve housed in said end plate intermediate the overflow chamber and the pressure side of said flow restricting device.

9..-In a fluid feed system the combination with a pump for supplying fluid to said system, of a device for restricting` the flow'of fluid between the pump and the system, an overflow chamber, ay passage connecting the overflow chamber with the pump side of said flow restricting device, a by-pal s ported out in said passage at two points` and means governing the back pressure built up on said pump and the volume of fluid passed through said flow-restricting device, said means comprising essentially a plunger movably mounted in said passage between the ports of said by-pass, a compression spring arranged to act on said piston against the back pressure built up on said pump, and means for adjustingA the tension on said spring to by-pass fluid from the pressure side of the plunger' to the over-flow chamber in amounts proportional to the baclr pressure on the pump.

10. In a fluid feed system the combination with a pump for supplying fluid to said system, of a device for restricting` the flow of fluid between the pump and said system, means for taking carevof excess fluid handled by the pump and not passed through said flow restrict-ing device including an overflow chamber housed in that end plate of the pump in which the drive shaft is journalled, a device for governing the back pressure built up on the pump and the quantity of fluid passed through said flow-restricting device and said over-flow chamber respectively, and means adapted to prevent air from leaking into and fluid from leaking out of the pump along the drive shaft bearing in the end plate housing said overflow chamber, said means comprising essentially a passage ported out of said bearing into said overflow chamber.

1l. In a fluid feed system the combination With a. pump for supplying fluid thereto, of a device intermediate the feed system and the discharge side of the pump for restricting the rate at vvvhich fluid handled by the pump is .passed to thevfeed system, said device comprising essentially a movably mounted apertured closure interposed between the pump discharge and the feed system, together with means for intermittently moving said closure int-o position to pass a measured volume of fluid from said pump discharge through said aperture to said sys-l tom, and overflow means for carrying off all excess fluid handled by the pump and not passed'to the feed system.

12. In a fluid feed system the combination With a pump for supplying fluid thereto, of means for actuating said pump at high speed, a flow restricting device for intermittent passing of fluid from the pump to said feed system during a portion of each stroke of the pump, and means mounted in the delivery line of the pump for absorbing pulsations set up inthe fluid supply.

13. In a fluid feed system the combination With a pump for supplying fluid thereto, of a device for restricting the quantity of fluid device comprising essentially a chamber in open communication with the discharge side of the pump, a rotatable member adjacent aid chamber, an opening formed in said r0- tatable member in a position to receive fluid. from said chamber during a portion only of each revolution of said member, and means for conducting fluid delivered to said opening to said fluid feed system.

14. In a fluid feed system the combination with a pump for supplying fluid thereto, of a device for restricting` the quantity of fluid passed from the pump to. said system, said device comprising essentially a chamber, a connection between said chamber and the discharge side of the pump, a rotatable shaft journaled in a bearing, a radial aperture formed in the ljournaled portion of said shaft, a passage ported out from said chaml ber through said bearing and arranged to register with said radial aperture as the shaft revolves, and means connecting the radial aperture in said shaft with said fluid feed system.

15. In a fluid feed system the combination with a pump for supplying` fluid thereto, of an apertured device for restricting the flow of fluid from the pump to said feed system, the smallest aperture in said device through which all fluid delivered by the device flows being circular in cross-section and free of obstructions across the center thereof from one side to the other, and means for proportioning the Avolume of fluid passed by said flow restricting device in accordance with the demand on said system.

In testimony whereof I affix my signature.

BENJAMIN GREENFIELD.

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