US3162131A

US3162131A - Pumping appartus

Info

Publication number: US3162131A
Application number: US298011A
Authority: US
Inventors: Claude A Clark
Original assignee: Dow Chemical Co
Current assignee: Dow Chemical Co
Priority date: 1963-07-29
Filing date: 1963-07-29
Publication date: 1964-12-22
Anticipated expiration: 1981-12-22

Description

Dec. 22, 1964 c. A. CLARK 3,

PUMPING APPARATUS Filed July 29, 1963 2 Sheets-Sheet 1 From f/u/d 5 W +727 INVENTOR Source C/a ude F). C/ark il/Q (/w Dec. 22, 1964 c. A. CLARK PUMPING APPARATUS 2 Sheets-Sheet 2 Filed July 29, 1963 INVENTOR. C/oc/de A C/ /k HGEA/T United States Patent 3,162,131 PUMPING APPARATUS Claude A. Clark, Houston, Tex., assignor to The Dow Chemical Company, Midland, lVlicir., a corporation of Delaware Filed July 29, 1963, Ser. No. 298,011 12 Claims. (Cl. 10338) 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 fluid 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 often 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 thepump 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 fluid 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 crank-shafts. These crankshafts operate through connecting rods to an equal-legged walking beam pinned at its centerline to a plunger crosshead. Similar planetary gears are used to drive the crank-shafts. Multiple disc clutches, one clutch being coupled between the frame of the pump and the planet carrier of each set of planetary gears, are used to establish and maintain the desired phase relationship between the crankshafts during operation. By slightly releasing one clutch to permit rotation of the planet carrier to which it is coupled by a pre determined amount the phasing of the planetary gears coupled to each crankshaft may be changed with respect to each other. shafts and hence the piston stroke may be changed in- The phase relationship between cranl versely with the discharge pressure to provide a hydraulic horsepower output desirably matched to the available horsepower of the prime mover.

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

FIG. 2 is a sectional view taken along the line 22 of FIG. 1;

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

FIG. 4 is a fragmentary end view of the drive gears showing chain drive coupling between the drive gears;

FIG. 5 is a side elevational view, in section, of a multiple disc clutch which is suitable for use with this invention;

FIG. 6 is a sectional view taken along the line 6-6 of FIG. 5; and

FIG. 7 is a sectional view taken along the line 77 of FIG. 5.

Referring to the drawing, there is shown variable volume pumping apparatus, indicated generally by the numeral 10, mounted on a common frame shown only in fragments. The apparatus includes a single action reciprocating piston-type pump 12 (see FIG. 3 especially) whose piston 14 is coupled to a crosshead plunger 15, adapted to reciprocate in the guide 15a, and to the center of an equal-legged walking beam 16 which in turn is coupled at its ends by connecting

rods

18, 20 to

crankshafts

22, 24, respectively, which are journaled in bearings 1?, 21 and 19a, 21a, for example.

Each of the

crankshafts

22, 24 has an end (25 in FIG. 2) which is rigidly mechanically coupled to the sun gear 34 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

ring gear

26, 28 of each of the planetary gear as

semblies

30,32 is rigidly mechanically coupled

toa shaft

36, 38. The

shafts

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

suitable bearings

40, 44 and 40a, 44a.

Spur gears 78, are carried by and coupled to the

shafts

36, 38, respectively. The gears 73, 80 are equal in diameter, have an equal number of teeth and are coupled together.

A spur gear 82 is carried on and coupled to the shaft 38. A prime mover, illustrated conveniently as a motor 86, is coupled to the gear 32 through a drive gear 84 which is carried on and coupled to the drive shaft 87.

The sun gears (34 in FIG. 2) of each of the assemblies '30, 32 are coupled to their

respective ring gears

26, 28

by pairs of planetary gears, the

planetary gears

46, 48 being shown in FIG. 2.

The planetary gears of each

planetary gear assembly

30, 32 are journaled on two shafts 5t), 52 (and S4, 56 in FIG. 1) which are parallel to the ring

gear driving shafts

36, 38 and which are fixedly connected by means of

disclike elements

59, 61, respectively, to a short

hollow shaft

58 or 69, each of which is parallel to and surrounds one of the extended end parts 23, 27 of the

respective crankshafts

22, 24 as shown. Each of the short hollow shafts 58, 60 has a flange 63, 65, respectively, which is rigidly coupled to the

elements

59, 61, respectively. The shafts 58,60 each are part of a multiple

disc clutch assembly

67, 69, respectively. Each of the

clutch assemblies

67, 69 is rigidly coupled to a frame element 71 whichis part of the frame of the pumping apparatus. Each of the disc-

like elements

59, 61 and the frame part 71 have a

bearing

99, 92 and 96a and 92a incorporated therein on which the crankshaft parts 23, 27 are carried.

Referring now to FIGS. 5, 6 and 7, as Well as to FIG. 1, the structure of the multiple disc clutch assembly 67 or 69 (perhaps more accurately called a brake in view of its use) is shown in detail.

The outer housing and frame part 1% of the clutch assembly is fixedly secured to the frame '71 of the pump assembly. The housing and frame part 100 is divided into two functional sections. The section 102, adjacent to the frame section 71, has a bore 1% and piston 166 disposed around a central tube 1% through which the drive shaft 36 (or 38) passes. A piston return spring 110, disposed between an outwardly extending flange 112 of the tube 108 and the piston 106, forces the piston 106 towards the end 114 of the section adjacent to the frame 71 except when the piston is forced forward by fluid, usually oil, pumped into the bore 104 into which the piston fits. Oil is pumped into and released from the bore by means of the line 111 which is also coupled to the clutch controller.

The second functional part 116 of the section 1%, which extends beyond the bore 104, has splines 118 on its inner wall surface and an inwardly extending flange 120 at its end which is remote from the frame section 71. A plurality of discs 122 are fitted on and carried by the hollow splined part in the space between the piston 1G6 and the inwardly extending flange 120.

A hollow tube 58, having longitudinally extending splines 126 on its outer surface, is telescoped within the outer housing and frame part 100 from the end thereof having the inwardly extending flange 120. The tube 58, as previously mentioned, is rigidly coupled to the planet carrier 59 (or 61) by means of its flange 63.

A plurality of discs 130 are fitted over and carried by the tube 58. The discs 122 and 138 are interleaved with one another, almost filling the space between the flange 120 and the forward end of the piston 106 when the piston is in its retracted position. i

In operation, let it be assumed that the

planet carriers

59, 61 are initially radially aligned with respect to one another. This can be determined by noting that the

markers

134, 136 on the

planet carrier discs

59, 61 are in the same relative position. The markers may be painted, cut, or etched onto the

carriers

59, 61 if the checking of their relative positions is to be determined visually (usually using a stroboscopic light source in so doing). Alternatively, magnetic or radioactive markers may be used and their positions noted during operation of the pump by suitable detectors which are generally well known in the art.

In this above described position, the throws of the

crankshafts

22, 24 are connected in an 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 from the gear 84 is coupled by means of the gear 32 to the shaft 38 and, by means of the spur gears 78, 80, to the shaft 36.

The shafts 36, 33 drive the ring gear (26 in FIG. 2) of each planetary assembly 39, 32, respectively. The sun gear (34 in FIG. 2) of each

assembly

36, 32 is coupled to the ring gear of its

assembly

30, 32 through the planetary gears (46, 48 in FIG. 2) of the

respective assembly

30 or 32. The planetary gears of the assembly are free to rotate on their shafts t), 52 and 54, 56, but these pairs of shafts are held in a predetermined position with respect to each other because oil, under pressure, is forced through the

lines

111, 113 forcing the piston (106 in FIG. 5) of each

clutch assembly

67 or 69 to advance, placing the

discs

122 and 130 in contact with each other (restrained by the flange 120) under sufiicient pressure to prevent any slippage of the discs and thus prevent the rotation of the tubular element 58 (or 69 for the assembly 69) which is rigidly coupled to the planet carrier 59 (or 61). The

shafts

59, 52 and 54, 56 are mounted in fixed position except when the hydraulic pressure driving the piston in one or both of the

clutches

67, 69 is released enough by suitable actuation of the clutch controller 89 to permit controlled slippage of the discs 130 on the tubular element 58. The planetary gears are, however, free to rotate on their shafts 50, 52 (or 54, 56).

When the stroke length of the piston 14 is to be changed, the clutch controller 89 is operated to partially release, momentarily, the pressure on the piston 106 of one of the

clutches

67, 69 to permit slippage of one of these clutches by a predetermined amount, thereby changing the phase relationship between the

crankshafts

22, 24 as one

planet carrier

59 or 61 changes its radial position (usually slowly) with respect to the other planet carrier. Such changing of position is usually at a slow rate as compared with the rate of rotation of the

crankshafts

22, 24. The length of the piston stroke is at a maximum when the

crankshafts

22, 24 are in phase as shown in FIG. 3 (rotating counter to one another). Piston stroke length decreases as the crankshafts become out-ot-phase with respect to each other, that is, the length of the piston stroke is at a minimum when one of the connecting

rods

18, 20 is at its most forward position with respect to the piston 14 and the other connecting rod is at its most rearward position with respect to the piston 14. Since both connecting

rods

18, 26 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, when the connecting rods are in maximum out-ot-phase relationship, is practically zero as the walking beam pivots around its point of attachment to the crosshead.

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

36, 38 has been in opposite radial direction because of the coupling together of the spur gears 78, 89.

The same changing iii-phase relationship of the crankshaft throws also may be achieved with the

clutches

67, 69 if the

drive shafts

36, 38 are coupled, as by the

spur gears

78a, 80a and chain drive 94 shown in FIG. 4, for example, to rotate in the sane radial direction. The pressure on the piston (106) of one of the clutches may be released sufiiciently to permit controlled rotation of one (usually) of the

planet carriers

59, 61, as previously described, thus changing the phase relationship between the crankshatts. The

crankshafts

22, 24 may be brought into a closer in-phase relationship by rotating either one of the planet carriers until the carriers are aligned to the required degree. Stated dilferently, if one planet carrier has been moved in relation to the other planet carrier to establish an out-of-phase relationship between the crankshafts, an in-phase relationship between the crankshafts may be accomplished by moving the earlier moved planet carrier until it is again aligned with the unmoved planet carrier. Alternatively, the previously unmoved planet carr-ier may itself be moved until it is aligned with the other planet carrier.

The apparatus described above provides means whereby, by changing the phase relationship between the crankshafts in appropriate amounts, constant horsepower 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 b ing displaced through the pump 12. As the pressure head increases one of .the clutches 6% or 62 is allowed to slip in a controlled manner to cause one of the

crankshafts

22 or 24 to be moved in an increasingly out-ofphase relationship with respect to the 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 32 does not cause the

shafts

36, 38 to be rotated at excessive speeds.

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

crankshafts

22, 24 and which are dniven by the ring gears 2s, 28.

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

ecause 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 bearings or to prevent the stalling of the prime mover. Conversely, a so-called high pressure fixed stroke piston pump is limited in the volume it can pump at lower pressures because of the safe r.p.m. rate of the crankshaft even though the connecting rod hearing may not be overloaded and the horsepower capabilities 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 more compact and lighter than a conventional unit of similar work capabilities.

An additional advantage of apparatus in accordance with this invention is that the

multiple disc clutches

67, 69 light in Weight yet can hold extreme loads without slippage. Such clutches, however, are easy to control, by suitably adjusting the pressure on the clutch actuating piston, to permit a controlled slow slippage to permit any desired movement of the planet carriers with respect to each other.

What is claimed is:

1. A mobile pumping unit comprising in combination a prime mover and a variable displacement pump, said pump comprising a frame, 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 crosshead being pivotally coupled to said central part of said Walking beam, 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 planetary gear and a ring gear, said planetary gear being coupled to a rotatable planet carrier element, one of said crankshafts being operatively coupled to the sun gear of one of planetary gear assemblies, the other of said pair of crankshafts being operatively coupled to the sun gear of the other of the planetary gear assemblies, a pair f drive shafts, means for coupling said prime mover to said drive shafts and for rotating each of said drive shafts at least approximately at the same rate, one of said drive shafts being operatively coupled to one of said ring gears, the other of said drive shafts being operatively coupled to the other of said ring gears, a pair of multiple disc clutches each having a fixed segment and a rotatable segment, the rotatable segment of each clutch being fixedly coupled to one of said planet carriers and the fixed segment of each clutch being rigidly coupled to said frame, and means for actuating said clutches independently of one another.

2. A pumping unit in accordance with claim 1, wherein said crankshafts are disposed parallel to one another.

3. A pumping unit in accordance with claim 1, wherein said drive shafts are disposed parallel with one another.

4. A pumping unit in accordance with claim 1, wherein the means for coupling the prime mover to the drive shafts includes means for rotating the drive shafts in opposite radial direct-ion to one another.

5. A pumping unit in accordance with claim 1, wherein each drive shaft passes through one of said clutches.

6. A pumping unit in accordance with claim 5, wherein said means for actuating said clutches includes a hydraulic system coupled to a piston of each clutch.

7. A pumping unit in accordance with claim 1, wherein said prime mover is coupled to said drive shaft through fixed-ratio gear means.

8. A pumping unit in accordance with claim 1, Wherein said prime mover is a gas turbine.

9. A pumping unit in accordance with claim 1, wherein said prime mover is a reciprocating piston-type internal combustion engine.

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

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

12. A pumping unit in accordance with claim 1, wherethe 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 FRAME, 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 CROSSHEAD BEING PIVOTALLY COUPLED TO SAID CENTRAL PART OF SAID WALKING BEAM, 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 PLANETARY GEAR AND A RING GEAR, SAID PLANETARY GEAR BEING COUPLED TO A ROTATABLE PLANET CARRIER ELEMENT, ONE OF SAID CRANKSHAFTS BEING OPERATIVELY COUPLED TO THE SUN GEAR OF ONE OF PLANETARY GEAR ASSEMBLIES, THE OTHER OF SAID PAIR OF CRANKSHAFTS BEING OPERATIVELY COUPLED TO THE SUN GEAR OF THE OTHER OF THE PLANETARY GEAR ASSEMBLIES, A PAIR OF DRIVE SHAFTS, MEANS FOR COUPLING SAID PRIME MOVER TO SAID DRIVE SHAFTS AND FOR ROTATING EACH OF SAID DRIVE SHAFTS AT LEAST APPROXIMATELY AT THE SAME RATE, ONE OF SAID DRIVE SHAFTS BEING OPERATIVELY COUPLED TO ONE OF SAID RING GEARS, THE OTHER OF SAID DRIVE SHAFTS BEING OPERATIVELY COUPLED TO THE OTHER OF SAID RING GEARS, A PAIR OF MULTIPLE DISC CLUTCHES EACH HAVING A FIXED SEGMENT AND A ROTATABLE SEGMENT, THE ROTATABLE SEGMENT OF EACH CLUTCH BEING FIXEDLY COUPLED TO ONE OF SAID PLANET CARRIERS AND THE FIXED SEGMENT OF EACH CLUTCH BEING RIGIDLY COUPLED TO SAID FRAME, AND MEANS FOR ACTUATING SAID CLUTCHES INDEPENDENTLY OF ONE ANOTHER.