US3102487A

US3102487A - Pumping apparatus

Info

Publication number: US3102487A
Application number: US205369A
Authority: US
Inventors: Nelson D Griswold
Original assignee: Dow Chemical Co
Current assignee: Dow Chemical Co
Priority date: 1962-06-26
Filing date: 1962-06-26
Publication date: 1963-09-03
Anticipated expiration: 1980-09-03

Description

P 3, 1963 N- D. GRISWOLD 3,102,487

PUMPING APPARATUS Filed June 26, 1962 I i INVENTOR.

5 +70 Ne/son D. Gr/lswo/o BY W QGENT ited States This invention relates to pumps and particularly to reciprocating piston pumps which are capable of delivering varying volumes of fluid while the piston or pistons of the pump reciprocate at a substantially constant stroke rate.

Other so-called variable volume pumps have been known for many years for specific uses, but for one reason or another these pumps are not well adapted for use in mobile service, such as oil and :gas well treating service, for example. Such service requires maximum utilization of available horsepower to thereby deliver the maximum volume of pumped fiuid against whatever pressure may develop without exceeding the strength limits of the equipment. Such requirements necessitate minimum weight and bulk consistent with the achieving of other requirements, and ease and reliability in controlling the ,variable volume feature of the pump while under load. Exceptional reliability is necessary because the pump will be used in remote areas where facilities are not available for making major repairs and because in well treating service equipment breakdown can result in great damage to the well under treatment. For example, a pump breakdown during a well cementing job could result in the cement setting up in the well casing before displacement can be effected between the casing and well bore wall.

In conventional well treating pumping units, a power source or prime mover, usually an internal combustion engine, transmission (which may include a torque converter) and the pump are disposed on a truck.

Any reduction in weight which can be achieved in the coupling of power to the pump of the treating unit would permit the construction of a lighter treating unit or would permit the construction of a treating unit having an increased pumping capacity (either in volume or pressure, or both) for given gross weight limitations.

Accordingly, a principal object of this invention is to provide improved variable volume pumping apparatus which is suitable for use in treating earth wells.

Another object of this invention is to provide an improved variable volume pumping apparatus which is compact in size with respect to its pumping capacity and power utilization over a wide range of pumping pressures.

A further object of this invention is to provide an improved mobile fiuid pumping system for well treating service or the like.

In accordance with this invention a piston type positive displacement pump achieves an infinitely variable stroke between maximum and minimum limits through a controlled variable phase relationship between two mechanically interlocked crankshafts. These crankshafts operate through connecting rods to an equal-legged walking beam pinned at its centerline to a plunger crosshead. Similar planetary gears, with the planet carriers interconnected by means of a worm and worm wheel, are used to drive the crankshafts and also to establish and maintain the desired phase relationship between the crankshafts during operation. By rotating the worm and thus changing the phase of the planetary gears coupled to each crankshaft, the phase relationshipbetween crankshafts output desirably matchedto the available horsepower of the prime mover.

ice

The invention, as well as additional objects and advantages thereof, will best be understood when the following detailed description is head in connection with the accompanyingydrawing, in which FIG. 1 is a simplified plan view partly bnoken away and in section, of apparatus in aCCOTdE1I1C with this invention;

FIG. 2 is a sectional view taken along the line 2--2 of FIG. 1; and

FIG. 3 is a sectional view taken along the line 33 of FIG. 1.

Referring to the drawing, there is shown variable volume pumping apparatus, indicated generallyby the numeral 10 mounted on a common frame (not shown). The apparatus includes a single action reciprocating piston-type pump 12 (see FIG. 3 especially) whose piston 14 is coupled to a orosshead plunger 15, adapted toreciprocate in the guide 15a, and to the center of an equallegged walking beam 16 which in turn is coupled at its ends by connecting rods '18, 29 to

orankshafts

22, 24, respectively, which are journaled in

bearings

19, 21 and 19a, 21a, for example.

Each of the

crankshafts

22, 24 has an end 23, 25 which is'rigidly' mechanically coupled to the ring,

gear

26, 28 of a

planetary gear assembly

30, 32, respectively. The planetary gear assembly 30, shown in section in FIG. 2, is the same as the assembly 32 which is shown in plan in FIG. 1.

The sun gear (see FIG. 2 sun gear 34) of each of the

planetary gear assemblies

30, 32 is rigidly mechanically coupled to a

shaft

36, 38. The

shafts

36, 38 are disposed parallel to each other and are supported by

suitable bearings

40, 44 and 40a, 44a. The sun gears of each of the

assemblies

30, 32 are coupled to their

respective ring gears

26, 28 by pairs of planet gears, the planet gears 46, '48 being shown in FIG. 2.

The planet gears .ofeach

planetary gear assembly

30, 32 are journaled on to shafts 50, 5'2 (and 54, :56 in FIG. 1) which are parallel to the sun

gear driving shafts

36, 38 and which are fixedly connected by means of

brackets

59, 61, respectively, to a hollow shaft 58 or 60, each of which is concentric with and surrounds one of the

respective shafts

36, 38 as shown. Each of the holr low shafts 58, 60 is supported in position by two

bearings

62 and 64 and 62a and 640, respectively. .A spur gear 78, is disposed on and rigidly coupled to each of the hollow shafts 58, 60, respectively, the spur gears 73, 80 being equal in size and in the number of teeth they contain. The spur gear 78' is driven by means of a gear 84 which is coupled to a prime mover such as a motor 86, JfOI' example. i

-A rotatable shaft 70',- having worms 72, 74- in spaced apart relationship along its length, is disposed transversely with respect to the shafts '36, 38. The

worms

72, 74 engage the teeth of worm wheels 66, 68, respectively, which are fixedly coupled to the ends of the

shafts

36, 38 which are remote from the

gear assemblies

30, 32, thepitch of the worms in each being equal and in the same. direction of rotation so that each of the worm wheels 66 and 68 can be turned the same amount in the same direction at the same time. A turning or control wheel 76 is rigidly mechanically coupled to one end of the shaft 70 whereby the shaft 70 is rotated when the wheel 76 is rotated.

Each of the

bearings

19, 19a, 21, 21a, 40, 40a, 62, 62a, 64, 64a, the pump 12, guide 15a and shaft 70' are mounted on common framework for the apparatus, which framework also carries the power source 86, the framework being attached to or supported by the mobile unit, e.-g. a truck, which carries the apparatus.

In operation the apparatus, as shown, has the hand wheel T '76 arbitrarily positioned so that the angle A is equal to the throws of the

crankshafts

22, 24 are connected in a in-phase rotational relationship, and move the piston 14 of the pump .12 backwards and forward in the pump cylinder 88 at maximum stroke length as power is transmitted from the gear 84 to the gear 78 and thence to the gear 80 to drive the shafts 58, 60.

The shafts 58, 60 drive the planet gears (46, 48 in FIG. 2) of each

planetary gear assembly

30, 32, respectively. The planet gears of each planetary gear assembly are free to rotate on their

shafts

50, 52 and 54, 56. These pairs of shafts are themselves, however, held in a predetermined position with respect to the shaft 58, 6t), respectively, to which they are secured, as mentioned previously. The worm wheels 66, 68, as mentioned previously, each engage with one of the

segments

72, 74 and are each coupled in a fixed relationship with one of the

shafts

36, 38. 7 Because the

shafts

36, 38 which drive the sun gears (34 in FIG. 2) are mounted in fixed position except when the wheel '76 is rotated, the rotating of the power driven planet gears (46, 48 in FIG. 2) results in the rotation of the

ring gears

26, 28 which are rigidly and fixedly coupled tothe oranksh-af-ts 22, '24.

' When the stroke length of the piston 14 is to be changed, the shaft 70 is turned (as by turning the wheel 76, for example), the amount of the turning depending upon the degree of phase change desired. As the shaft 70 rotates the

worms

72, 74 rotate and cause the worm wheels 66, '68 to turn. Such turning is usually at a slow rate as compared with the rate of rotation of the

crankshafts

22, 24. The shafts 58, 60, to which the planet gears ('46, 48in FIG. 2 are also mechanically coupled, are rotated as the

spur wheels

78 and 80 rotate. The

worm segments

72, 74 each have the same pitch and their flights turn in the same direction so, with the

crankshafts

22, 24 rotating in opposite directions -(one clockwise, one counter-clock'wise) the relative phasing between the

crankshafts

22, 24 is changed as the

shafts

36, 38 are rotated. By in phase is meant that the crank throws viewedfrom the ends of the crankshafts occupy mirror image positions as in FIG. 3 where angles A and A are the same; when angles A and A diifer the crankshafts are out of phase." The angular difference between the angles A and A can be varied by suitably turning wheel 76 and therefor shaft 70, thereby. providing for a variation in the piston stroke length from a maximum to a .minimum. The length of the piston stroke is at a maximum when the cranksha-

fts

22, 24 are in phase as shown. Piston stroke length decreases as the crankshafts become out of phase with respect to each other, that is, when angles A and A (FIG. 3) differ from each other. When the length of the piston stroke is at a minimum one of the connecting rods 218, 20' will be at its most forward position with respect to the piston 14 and the other connecting rod will be at its most rearward position with respect to the piston. Since both connecting

rods

18,20

' are connected to the walking beam 16 which is coupled at its center to the crosshead 15, the movement of the piston 14 is a resultant of the movement of the two connecting rods 18, 20' and is, at minimum stroke, practically zero as the walking beam pivots around its point of attachment to thecrosshead.

When the phase relationship of the crankshafts is at an intermediate point between the in-phase relationship and the maximum out-of-phase relationship there will be some rocking of the walking beam about its point of attachment to the crosshead, and also some forward and backward motion of the piston -14.

It should be noted that in the apparatus thus far described, the rotation of the

drive shafts

56, 58 has been in opposite radial direction because of the coupling together of the

spur gears

78, 80. Thus, even though the rotation of the

shafts

36, 3 8 is in the same direction, the phase relationship of the crankshaft throws is changed as the

shafts

36, 38 rotate.

The apparatus described above provides means whereby 4 constant horespower may be applied to the pump .12 even though the pressure head against which the pump works may vary over a wide range. When the pressure head is low enough to permit such operation, keeping the two crankshafts operating on an in-phase relationship results in maximum volume being displaced through the pump 12. As the pressure head increases the wheel 76 is rotated to cause the crankshafts to be moved in an increasingly out-of-phase relationship with respect to each other so that the available driving horsepower may be used to drive the piston '14 in increasingly shorter strokes and thus deliver less volume at a higher pressure.

Also, since the pump output can be continuously varied between practically no output and maximum output, there is no need for a torque converter or an additional speed varying transmission to be interposed between the power source and the pump apparatus providing the coupling.

between the power source 86 and the gear 84 does not cause the

shafts

56, 58 tobe rotated at excessive speeds.

While the apparatus has been illustrated as driving a single barrel, single action reciprocating piston pump, a triplex pump, either single or double acting, or other multiple cylinder pump may be coupled to suitable crankshafts which are substituted for the crank-

shafts

22, 24 and which are driven by the ring gears 26, 28.

The apparatus of the invention permitsthe power source to operate at a substantially constant rpm. rate even though the pumping rate varies widely. Thus, this apparat-us is well adapted to be driven by turbines or by an internal combustion piston-type engine operating at an optimum r.p.m. rate.

Because the pump is driven by two crankshafts, the bearing loading on the individual connecting rods is reduced. A single pump may'deliver either a large volume at moderate pressures or smaller volume at high pressures,

' In fixed stroke reciprocating piston-type pumps a so-called .high volume pump has a relatively low maximum pumping pressure in order to prevent overloading of the connecting rod hearings or to prevent the stalling of the prime bilities of the prime mover are not exceeded.

Pumping apparatus in accordance-with this invention is more versatile than conventional apparatus in that it is good both as. a high pressure-low volume pump and as a low pressure-high volume pump and it admits of continuous variation of the relationship between pressure or volume driving operation. Also, because no intermediate torque converter or speed varying transmission is used, the apparatus is come compact and lighter than a conventional unit of similar work capabilities.

What is claimed is:

1. A mobile pumping unit comprising in combination a prime mover and a variable displacement pump, said pump comprising a cylinder and piston reciprocal therein, a crosshead, means for mechanically coupling the piston to the crosshead to reciprocate the piston with reciproca tion of the crosshead, a walking beam having a central part and two end parts, said Walking beam being pivotally coupled at its central part to the crosshead, a pair of crankshafts, each of said crankshafts having at least one throw, a pair of connecting rods, one of said connecting rods being pivotally coupled to one end part of said walking beam and to a throw on one of said pair of crankshafts, the other connecting rod being pivotally coupled to the other end of the walking beamand to a throw on said other crankshaft, a pair of planetary gear assemblies each comprising a sun gear, at least one planet gear and a ring gear, one of said crankshafts being operatively coupled to the ring gear of one of said planetary gear assemblies, the other of said pair of crankshafts being operativelyv coupled to the ring gear of the other of said planefor rotating each of said drive members at the same rate,

one of said drive members being operatively coupled to one of said planet gears, the other of said drive members being operatively coupled to the other of said planet gears,

a pair of phase control shafts, one of said phase control shafts being coaxially aligned with one of said drive shafts, the other of said phase control shafts being coaxially aligned with the other of said drive shafts, said phase control shafts each being coupled to one of said sun gears, a pair of worm wheels, one of'said worm wheels being operatively coupled to one of the phase control shafts and the other being operatively coupled to the other of the phase control shafts, and at least one drive worm coupled to said worm Wheels for varying the radial position of the sun gear in one planetary assembly with respect to its planet gear and for varying the radial position of the sun gear in the other planetary assembly with respect to its planet gear whereby the throw of one crankshaft has its radial position changed with respect to the radial position of. the corresponding throw of the other crankshaft.

2. A pumping unit in accordance with claim 1, wherein 7 drive members in opposite radial direction to one another.

it t 6 5. A pumpingunit in accordance with clairn 1, wherein said drive worm is disposed along arod-like shaft.

6. A pumping unit in accordance with claim 5, wherein i said means to rotate the Worm wheels comprises a control combustion engine.

. 10. A pumping unit in accordance with claim 1, wherein said rotatable drive members comprise hollow shafts each of which surrounds one of saidphase control shafts.

1.1. A pumping unit in accordance with claim 1, wherein the sun gear, planet gear and ring gear in one planetary gear assembly are the same as the corresponding part in the other planetary gear assembly.

12. A pumping unit in accordance with claim 1, wherein the longitudinal axis of the crank throw of each crankshaft is ofiset from the longitudinal axis of its crankshaft by an equal amount;

13.. A pumping unit in accordance with claim 1, wherein the point of coupling of the crosshead to the Walking beam is along a line perpendicular to and bisecting a line drawn between the points of coupling of the connecting rods to the walking beam.

No references cited.

Claims

1. A MOBILE PUMPING UNIT COMPRISING IN COMBINATION A PRIME MOVER AND A VARIABLE DISPLACEMENT PUMP, SAID PUMP COMPRISING A CYLINDER AND PISTON RECIPROCAL THEREIN, A CROSSHEAD, MEANS FOR MECHANICALLY COUPLING THE PISTON TO THE CROSSHEAD TO RECIPROCATE THE PISTON WITH RECIPROCATION OF THE CROSSHEAD, A WALKING BEAM HAVING A CENTRAL PART AND TWO END PARTS, SAID WALKING BEAM BEING PIVOTALLY COUPLED AT ITS CENTRAL PART TO THE CROSSHEAD, A PAIR OF CRANKSHAFTS, EACH OF SAID CRANKSHAFTS HAVING AT LEAST ONE THROW, A PAIR OF CONNECTING RODS, ONE OF SAID CONNECTING RODS BEING PIVOTALLY COUPLED TO ONE END PART OF SAID WALKING BEAM AND TO A THROW ON ONE OF SAID PAIR OF CRANKSHAFTS, THE OTHER CONNECTING ROD BEING PIVOTALLY COUPLED TO THE OTHER END OF THE WALKING BEAM AND TO A THROW ON SAID OTHER CRANKSHAFT, A PAIR OF PLANETARY GEAR ASSEMBLIES EACH COMPRISING A SUN GEAR, AT LEAST ONE PLANET GEAR AND A RING GEAR, ONE OF SAID CRANKSHAFTS BEING OPERATIVELY COUPLED TO THE RING GEAR OF ONE OF SAID PLANETARY GEAR ASSEMBLIES, THE OTHER OF SAID PAIR OF CRANKSHAFTS BEING OPERATIVELY COUPLED TO THE RING GEAR OF THE OTHER OF SAID PLANETARY ASSEMBLIES, A PAIR OF ROTATABLE DRIVE MEMBERS, MEANS FOR COUPLING SAID PRIME MOVER TO SAID DRIVE MEMBERS AND FOR ROTATING EACH OF SAID DRIVE MEMBERS AT THE SAME RATE, ONE OF SAID DRIVE MEMBERS BEING OPERATIVELY COUPLED TO ONE OF SAID PLANET GEARS, THE OTHER OF SAID DRIVE MEMBERS BEING OPERATIVELY COUPLED TO THE OTHER OF SAID PLANET GEARS, A PAIR OF PHASE CONTROL SHAFTS, ONE OF SAID PHASE CONTROL SHAFTS BEING COAXIALLY ALIGNED WITH ONE OF SAID DRIVE SHAFTS, THE OTHER OF SAID PHASE CONTROL SHAFTS BEING COAXIALLY ALIGNED WITH THE OTHER OF SAID DRIVE SHAFTS, SAID PHASE CONTROL SHAFTS EACH BEING COUPLED TO ONE OF SAID SUN GEARS, A PAIR OF WORM WHEELS, ONE OF SAID WORM WHEELS BEING OPERATIVELY COUPLED TO ONE OF THE PHASE CONTROL SHAFTS AND THE OTHER BEING OPERATIVELY COUPLED TO THE OTHER OF THE PHASE CONTROL SHAFTS, AND AT LEAST ONE DRIVE WORM COUPLED TO SAID WORM WHEELS FOR VARYING THE RADIAL POSITION OF THE SUN GEAR IN ONE PLANETARY ASSEMBLY WITH RESPECT TO ITS PLANET GEAR AND FOR VARYING THE RADIAL POSITION OF THE SUN GEAR IN THE OTHER PLANETARY ASSEMBLY WITH RESPECT TO ITS PLANET GEAR WHEREBY THE THROW OF ONE CRANKSHAFT HAS ITS RADIAL POSITION CHANGED WITH RESPECT TO THE RADIAL POSITION OF THE CORRESPONDING THROW OF THE OTHER CRANKSHAFT.