US2553336A - Pump - Google Patents

Description

May 15, 1951 R. K. SEDGWICK PUM 5 Sheets-Sheet 1 Filed Dec. 18, 1946 INVENTOR.

May 15, 1951 R. K. SEDGWICK PUMP .. VII: NN% T NW NW f N 0 Filed Dec. 18, 1946 l I I 15, 1951 I R. K. SEDGWICK 2,553,336

- PUMP Filed Dec. 18, 1946 5 Sheets-Sheet 3 y 15, l95l R. K. SEDGWICK 2,553,336

I x INVENTPR. gj% f gm,

0AM W y 15, 1951 R. K. SEDGWICK 2,553,336

PUMP

Filed Dec. 18, 1946 5 Sheets-Sheet 5 Patented May 15, 1951 PUMP Robert K. Sedgwick, Chicago, IlL,

assignor to American Steel Foundries, Chicago, 111., a cor--- poration of N evv Jersey Application December 18, 1946, Serial No. 716,996

This invention relates to pumps and. more particularly to a variable discharge pump comprising novel means for adjusting the discharge rate thereof.

Variable discharge pumps known in the prior art are adapted to afford a variable discharge rate while maintaining a substantially constant rotative or plunger speed. Such pumps are generally of the variable stroke type, utilizing no seated valves and consequently requiring that the fluid pumped be a high grade lubricating oil. Pumps of this type generally use a pintle or valve plate to accomplish the valving action and the rubbing of the associated parts .against the valving member necessitates lubrication thereof. Furthermore, pumps of this type are constructed with close clearances rather than tight seals, and as a result, such pumps are practically limited to pressures of the order of three thousand pounds per square inch, and most of such pumps areonly usable at such a pressure value fora short period of time.

There are man applications in industrial hydraulics for a pump capable of generating much higher pressures than that above mentioned and for maintaining such pressures for long periods of time. For this type of work the conventional reciprocating plunger pump utilizing seated Valves is still supreme. Some modifications of this basic construction known to the prior art involve variable stroke linkages adapted to reduce the stroke of the plunger when reduced discharge is desired. Other known modificationsutilize a swash plate, theangle of which is varied .to vary the plunger stroke. Such devices involve undesirable machine shop practices intheirconstruction, .and furthermore, the mechanical efficiency of these devices is considerably lessthan thatof a conventional crank and connectin rod mechanism.

Other applications requiring variable discharge combined with high pressure have been solved by utilizing a standard fixed stroke pump driven at variable speed by means of various power transmitting devices which also involve loss of efficiency and in many cases do not provide sufficient variation in the discharge rate.

A primary object of the present invention is to provide a variable discharge pump capable of continuous operation at relatively high pressures.

Another object of the invention is to design a variable discharge high pressure pump which will pump nonlubricating liquids.

Still another object of the invention isto design a pump such as above described which will have! 9 Claims. (01. 103-37) a discharge rate variable from the maximum capacity of the pump to substantially zero.

A further objectof the invention is to design a pump such as above described which has the same order of mechanical efiiciency as a standard triplex pump.

Another object is to design a variable discharge high .pressure pump which can be built by ordi nary machine shop techniques, thus eliminating nuisance? machining operations prevalent in the construction of known designs of pumps.

Still another object of the invention is to design a variable discharge high pressure pump in which the discharge may be varied while the pump is running at substantially constant speed.

The foregoing and other objects and advantages of the invention will .become apparent from a consideration of the following specification and the accompanying drawings, wherein:

Figure 1 is a side elevation, partly in section, illustrating a pump embodying the invention;

Figure 2 is a front view taken from the left as seen in Figure 1;

Figure 3 is a front view similar to Figure 2 with portions of the pump broken away to dis. close the internal structure thereof;

Figurev 4 is a fragmentary sectional .vieW of .the pump shown in Figure 1, taken in a vertical plane approximately bisecting the adjustable crank shaft and .its associated drive gear;

Figure 5 is a diagrammatic view illustrating the pump pistons operating in the neutral phase thereof whereat the discharge rate is substantially zero;

Figure 6 is a fragmentary horizontal sectional view taken through .apump embodying a modifie cation of the invention wherein the discharge rate may be manually adjusted without stopping the pump;

Figure 7 is a fragmentary front elevation of the structure shown in Figure .6, taken from the bottom thereof, a portion of the adjusting mechanism being shown in section on the line'11 of Figure 6, for the sake of clarity;

Figure 8 is a fragmentary horizontalsectional View through a pump embodying another modification of the invention; .and

Figure 9 is anenlarged sectional view taken on the line 99 of .FigureS.

Describing .the. invention in detail and referring first to the embodiment thereof illustrated in Figures 15 inclusive, the pump embodyingthe ing'apair of cr'a'nkshafts 4 and 6 operatively con-i nected in conventional manner to a plurality of connecting rods 8, each of which is connected by a wrist pin and crosshead assembly ID to a The plungers l2, as best plunger or piston 12. seen in Figure 3, are arranged in pairs reciprocal within a pump chamber l4 through conventional stufilng boxes l6, the chamber id being connected to a suction or inlet line i8 through a port having a one-way inlet valve 20, and bein connected to an outlet or discharge line 22 through a port spring-pressed valves of the seated type.

The crank shaft 4 is keyed in conventional manner to a gear 28 which is meshed with agear 28 rotatably mounted or journaled on the adjustable crank shaft 6, the gear 28 being meshed with a drive gear 30 adapted to be connected mechanism, such as a motor (not shown). The adjustable crank shaft 6 is keyed to a sector or s'egmentary gear 32 which meshes with an adjusting worm gear 34 rotatably mounted in lugs or bearings 36 rigidly connected to the outer face of the gear 28.

It will be understood that the basic principle involved in the above-described design of pump is that if two bodies are moving in the same chamber so as to displace fluid therefrom, the motion of one of the bodies may be reversed at some' point in the cycle so that its subsequent motion will partially or entirely cancel the displacement, ofthe other body and thus reduce the net displacement. Thus, referring to Figure 3, it will be seen that the pair of plungers l2 illustrated therein are driven to afford maximum discharge inasmuch as the pair of plungers are simultaneously withdrawn from and urged into the pump chamber 14. In this connection, it may be noted that under these conditions the tuated, thus affording maximum displacement.

Referring to Figure 5, which is a somewhat diagrammatic view illustrating a pair of the plungers 12 operating so as to afford minimum displacement which is substantially zero, it will be seen that the plunger l2 at the left of Figure 5, which is operated by the crank shaft 4, is at the extreme retracted position of the retraction phase of its cycle, while the piston l2 at the right of this figure, whichis operated by the adjustable crank shaft 6, is at the extreme advanced position of the advance phase of its cycle. Thus the motion of the respective plungers 12 in the arrangement shown in Figure cancel the displacement of each other so as to reduce the net discharge rate of the pump to a value of substantially zero.

It will be understood that the phase of the pistons l2 associated with the adjustable crank shaft 6 may be adjusted with respect to the phase of the pistons I2 operated by the crank shaft t to any value between the extremes illustrated in Figures 3 and 5 by stopping the pump and rotating the worm gear 34.manually, thus rotatin the adjustable crank shaft 6 while the crank shaft d remains stationary. Thus the discharge rate of the pump may be varied to any desired value between zero and maximum discharge.

If desired, a'sector or gear member 32 and worm gear 34 may be associated with the crank shaft 4 for adjusting the same relative to its associated gear 26 as above described in connection with the crank shaft 6.

other two pairs of plungers l2 are similarly ac-.

Referring now to the modification of the inhaving a one-way outlet valve 24. The valves and 24, as seen in Figure 3, are conventional in any convenient manner to an associated drivei vention illustrated in Figure 6, the embodiment shown therein comprises means for adjusting the adjustable crank shaft' without stopping the pump. In this embodiment of the invention, the pump mechanism is identical with that shown in Figures 1-5 and is thus not shown except for the mechanism adapted to adjust the adjustable crank shaft. In the arrangement of Figures 6 and '7, the drive gear, generally designated 52 is supported by the pump frame or housing, fragmentarily indicated at 54, and is adapted to be connected to an associated drive mechanism such as a motor (not shown). The drive gear E52 is disposed between and meshed with the crank shaft gears '56 and 58, the gear 56 being keyed to the nonadjustable crank shaft 6&3, and the gear 58 being rotatably mounted on the adjustable crank shaft 82. The gear 53 carries a plu-- rality of planetary gears 6 rotatably mounted on bearing pins 68 which are connected between the gear 58 and a gear housing 68. The planetary gears are meshed with a large sun gear it and a small sun gear 72. The large sun gear in is keyed to the adjustable crank shaft 62, and the small sun gear i2 is keyed to a pin If which is in turn keyed to a bevel gear 16 of a differential gear mechanism generally designated 78.

The differential gear mechanism 18 also comprises a bevel gear 83 connected to a handle 82 and rotatable within a frame 84, one end of which is mounted on the outer end of the crank shaft 6:) and the other end of which is mounted on the bevel gear 86 which is hollow and affords a journal for the outer end of the pin M. The

bevel gears 16 and are meshed with a plurality of pinion gears 86 rotatably mounted in a sprocket 88 which is connected by a chain 90 to a halfsize sprocket 92 pinned to:the crank shaft 60.

When the pump is running under normal operating conditions the bevel gear 8% is locked against rotation by a manually operated set screw 94. Inasmuch as the drive gear 52 is disposed between the crank shaft gears 55 and 58 these gears are turning in the same direction, and because of the half-sized sprocket 92, the sprocket 88 is rotating in the same direction as the gear 58 at half the speed thereof. Since the bevel gear Bil is locked against rotation, the bevel gear i6 is driven by the pinion gears at twice the speed of the sprocket'88, or in other. words, at the same speed as the crank shaft gear 58. Thus the small sunlge'ar l2 and the crank shaft gear 58 are rotating in the same direction at rotation of the gear 58 and the adjustable crank shaft 62, the set screw 94 is loosened and the bevel gear 80 is actuated by means of thehandle 82, thus causing the'large sun gear If! and the adjustable crank shaft 62 to rotate faster or slower than the gear 58 until a new discharge rate is achieved. The set screw 94 is then actuated to lock the bevel gear 88 against rotation, whereupon the pump operates at its new discharge rate until the same is further adjusted.

Referring now to the modification illustrated in Figures 8 and 9, the embodiment disclosed therein is substantially identical with that shown in Figures 6 and 7 except for the actuating means 9 corresponding to the parts shown in Figures '6 and 7 are identified by corresponding numerals. In this embodiment, the small sun gear I2 is actuated by an electric motor, generally designated I00, the armature I02 of which is keyed to the pin 74 supporting the gear I2 from the gear housing 68.

The motor I comprises a housing I03 fixed to the gear housing 68 and carrying a pair of rings I04 and I00 which are rotatably engaged with the positive and negative terminals I08 and I I0 of leads I00 and III. These leads are adapted to be connected by a switch H2 to leads H3 and H connected respectively to the positive and negative terminals of a source (not shown) of direct electric current. Under normal operating conditions with the pump operating at a predetermined discharge rate, the small sun gear I2 rotates with the housing 68 inasmuch as the armature I02 of the motor I00 is fixed to the housing I03 thereof by means of spring-pressed brake blocks I I4. When it is desired to rotate the sun gear 12 relative to the housing 68, thus varying the discharge rate of the pump by adjusting the phase of the plungers associated with the adjustable crank shaft '52 relative to the phase of the plungers associated with the crank shaft 60, a circuit is established by closing switch H2, which circuit may be traced from ring I0 3 through lead H6, brushes I28 and I3!) and ring I06. A parallel circuit is closed through the solenoid I I8. At the same time, a circuit is established through a ring I20 and a lead I2'I through the field I22 of the electric motor by means of a lead I24 and thence by lead I26 to a ring I21. The rings I20 and I 21 are rotatably engaged with the terminals I29 and I3I of leads I35 and I33 which are adapted to be connected by a pole changer switch I31 to the positive and negative terminals I 39 and MI of a source (not shown) of direct current. It will be understood that the armature I02 may be rotated in either direction by actuating the switch I31 to establish the desired polarity in the terminals I29 and I3I, as will be readily understood by those skilled in the art.

Under these conditions, the brake blocks H4 are spread by means of cams I34 operated by a bifurcated lever I36 which is in turn actuated by the solenoid II 8. The electric motor I00 at the same time rotates the small sun gear 12 with respect to the housing 68, thus rotating the crank shaft 62 with respect to the gear 58 and thereby varying the phase of the plungers actuated by the crank shaft 62. When the discharge rate of the pump has been adjusted as desired, the abovementioned electric circuits are broken, whereupon the lever I36 is released and the springpressed brake blocks H4 immediately interlock the armature I02 of the motor with the motor housing I03 which, as above noted, is fixed with respect to the gear housing 68. Under these conditions the crank shaft 62 again rotates with the gear 48 and the pump operates at the new discharge rate until further adjustment is desired.

It is to be understood that I do not wish to be limited by the exact embodiments of the device shown which are merely by way of illustration and not limitation as various and other forms of the device will, of course, be apparent to those skilled in the art without departing from the spirit of the invention or the scope of the claims.

I claim:

1. In a pump, a pump chamber, inlet and outlet valve means therefor, a pair of plungers re,- ciprocal within said chamber and a pair of cranks connected to respective plungers for actuation thereof, a gear fixed to one of said cranks, a gear journal on the other crank and capable of rotation relative thereto, means for driving said gears at substantially equal rates, and adjusting means for rotating said other crank relative to the second-mentioned gear while the same is being driven by said driving means, said adjusting means comprising a gear housing secured to said other gear, a planetary gear system in said housing comprising a plurality of planet gears pivoted thereto, a driving gear pivoted to said housing and meshed with said planet gears, a driven gear keyed to said other crank and meshed with said planet gears, and means for interlocking the driving gear with the housing and for rotating the driving gear relative thereto, said lastmentioned means comprising a differential gear mechanism including a bevel gear connected to said driving gear for rotation therewith, another level gear, a sprocket carrying a plurality of pinion gears meshed with said bevel gears, a

sprocket on said one crank having a diameter approximately one half of the diameter of the first-mentioned sprocket, a chain connecting said sprockets, means for locking said other bevel gear against rotation, and means for rotating said other bevel gear when said locking means is dissociated with respect thereto.

2'. In a pump, a pump chamber, inlet and outlet valve means therefor a pair of plungers reciprocal within said chamber, a pair of cranks connected to respective plungers for actuation thereof, a gear fixed to one of said cranks, a gear rotatable with respect to the other crank, means for driving respective gears at substantially equal rates, and adjusting means for rotating said other crank relative to the second-mentioned gear while the same is being driven by said driving means, said adjusting means comprising a gear housing secured to said other gear, a planetary gear system in said housing comprising a plurality of planet gears pivoted thereto, a driving gear pivoted to said housing and meshed with said planet gears, a driven gear keyed to said other crank and meshed with said planet-gears, and means for selectively interlocking the driving gear with the housing and rotating the driving gear relative thereto.

3. A variable discharge pump comprising a pump chamber, at least one pair of plungers reciprocal in said chamber, a pair of cranks operatively connected to respective plungers of said pair, and a pair of driving gears having operative connections to respective cranks, at least one of said connections comprising a pair of sun gears coaxial with respect to the related crank, one of the sun gears being keyed thereto, the related crank being rotatable relative to its driving gear, a planet gear meshed with said sun gears, and means for rotating the other sun gear.

4. A pump according to claim 3 wherein the last-mentioned means comprises an electrical motor having an armature shaft connected to said other sun gear and coaxial therewith, and releasable means are provided for interlocking said shaft with the related driving gear for rotation therewith.

5. A variable discharge pump comprising a pump chamber having suction and discharge ports, at least one pair of plungers reciprocal in said chamber, a pair of cranks each operatively was gear keyed to one crank/another .drivin'g. gear rotatable. with respect to the other crank, an adjusting sun gear keyed to said other crank, a planet gear carried by said other driving gear for rotation in unison therewithand meshed with said sun gear, another sun gear meshed with said planet gear, and means operatively connected to the second-mentioned sun gear'for rotating the latter at the same rate as the firstmentioned sun gear during normal operation of the pump and for varying the rotational rate of the second-mentioned. sun gear with respect to the rotational rate of the first-mentioned sun gear during adjustment of the discharge rate of the pump.

6. A pump according to claim 5 wherein the last-mentioned means comprises a motor carried by said other driving gear and connected to the second-mentioned sun gear.

7. A pump according to claim 5, wherein the last-mentioned means comprises a pair of bevel gears, one connected to the second-mentioned sun gear for rotation therewith, a member carrying a pinion gearmeshed with said bevel gears,

means for rotating said member, and means for.

locking the other bevel gear against rotation and for rotating said other bevel gear relative to said one bevel gear.

8. A pump according to claim 5, wherein the last-mentioned means comprises a bevel gear connected to said other sun gear for rotation therewith, amember carrying a pinion gear meshed with said bevel gear, another bevel gear fixed against rotation and meshed with said pinion gear, and means for rotating said member.

9. A variable discharge pump comprising a pump. chamber, atleast one pair of plungers reciprocal in said chamber, a pair of cranks operatively'connected to respective plungers of said pair, and a pair of driving'gears having opera-' tive connections to respective cranks, at least one of said connections comprising a pair of sun gears, one keyed to the related crank and the other being rotatable with respect thereto, the crank being rotatable relative to its driving gear, 10 a planet gear meshed with said sun gears, and means operatively connected to the other sun gear for rotating the latter at the same rate as said one sun gear during normal operation of the pump, and for varying the rotational rate of said 15 other sun gear with respect to that of said one sun gearduring adjustment of the discharge rate of the pump.

ROBERT K. SEDGWICK.

REFERENCES CITED The following references are of record in the file of this patent? V UNITED STATES PATENTS

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