US2673519A - Opposed piston pump - Google Patents

Description

March 30, 1 954 Filed Oct. 1, 1949 E. P. HALLIBURTON OPPOSED PISTON PUMP 4 Sheets-Sheet 1 INVENTOR ERLE P HALLIBURTON ATTORNEY March 30, 1954 E. P. HALLIBURTON 2,673,519 OPPOSED PISTON PUMP Filed Oct. 1, 1949 4 SheetsSheet 2 r x v Fla INVENTOR ERLE P. HALLI BURTON ATTORNEY March 1954 E P. HALLIBURTON 2,673,519

OPPOSED PISTON PUMP Filed Oct. '1, 1949 4 SheetsSheet 3 4 I6 28 L 6 3o 2s FIG. 8. H 0 24 INVENT OR ERLE P. HALLIBURTON ATTORNEY March 30, 1954 E, P. HALLIBURTON 2,673,519

OPPOSED PISTON PUMP Filed Oct. 1, 1949 4 Sheets-Sheet 4 VEL IN DEGREES CRANK TRA L o o o o O O m w n 'IHAVHJ. NOlSld IN NTOR BYM ATTORNEY Patented Mar. 30, 1954 UNITED STATES PATENT OFFICE OPPOSED PISTON PUMP Erie P. Halliburton, Los Angeles, Calif., assignor to Halliburton Oil Duncan, Okla.

ell cementing Company,

Application October 1, 1949, Serial No. 119,190 3 Claims. (01. 103l59) the limitations imposed as to over-all length. To further reduce the over-all length of the pump and also because the liquids being moved often contain sand or other abrasives which cause wear on pistons and cylinders, a short crank and hence a short stroke is desirable.

pump to surge. Moreover, a short crank either reduces the capacity of the pump to deliver a large volume per unit of time or requires that the pump be operated at high speed.

Theoretically, an ideal pump, insofar as smoothness in operation in the delivery of liquid is concerned, would be one in which the ratio of the connecting rod to the crank is very large. The piston movement would then approach that of simple harmonic motion if the crank were rotated at a constant velocity.

In designing pumps having a single piston in each cylinder, these considerations have resulted in a comprise. The connecting rod has usually been made from 4. to 6 times the length of the connecting rod to crank reduce the over-all length of the pump but cause the liquids being pumped as to be regarded as contrary to good engineering Greater ratios reduce the surge, and from that viewpoint are highly desirable, but increase the required length of the pump beyond reason and increase the weight.

In accordance With the present invention, it is proposed to provide a light weight, slow speed pump having a short connecting rod and a short movement approaching very crank but with piston displacement approaching very closely simple harmonic motion, so as to dearrangement is such that the combined movement of the two pistons and the cylinder creates liquid closely that which would be obtained by an ordinary pump with a connecting rod of great length.

The term opposed pistons as used herein, means that the two pistons in each cylinder of the pump travel toward and away from each other to eifect changes in volume or displacement in the cylinder. The pistons do not accelerate or travel in synchronism, however. The cylinder itin a cylinder.

One way in which the invention may be carried out is illustrated in the accompanying drawings in which:

Fig. 1 is a fragmentary view in side elevation present invention;

Fig. 2 is a fragmentary plan view of the pump of Fig. 1;

Fig. 3 is a view in vertical cross-section of one of the cylinders of the pump of Fig. 1;

Fig. 4 is a view in transverse cross-section through a portion of the pump of Fig. 1, the view being taken on the line 4-4 of Fig. 3;

Figs. 5, 6, 7, and 8 are diagrammatic representations of an oscillating cylinder in cross-section with opposed pistons therein connected to cranks spaced 180 degrees on a common crankshaft, the views representing the relative position of the parts of the pump of Figures 1 to 4 at degree intervals of rotation of the crank shaft and illustrating the principles of the invention; and

Fig. 9 is a chart in which crank travel is plotted against piston travel and illustrating the advantages of the present invention.

Referring to the ed upon a frame l2. All of the cylinders are alike and each is provided with two plungers or pistons these being designated 53 and M. For convenience, the piston i3 may be referred to as the crank-end piston and the piston ill as the headend piston although the cylinder I! actually has no head, being exactly alike at both ends. Suitable packing, such as the chevron washers-shown at 5 in Fig. 3 is provided between the pistons and the cylinder i.

Each cylinder H is mounted in the frame |2 for oscillating movement. To this end, each cylinder is provided with trunnions is mounted in supporting bearings Some-of the trunnions it are hollow, as shown in Fig. 4 and these provide a passageway for conducting liquid from the cylinder into the discharge opening H3 in the bearing ll. Chevron packing is provided between the trunnions l6 and the bearings i7.

All of the trunnions l6 are offset vertically from o the cylinders H which they the cylinders swing like a the center line of support, so that pendulum.

As shown in Figs. 3 and 4, inlet valves 25 are provided beneath each cylinder l, liquid to these being supplied through a hose or other flexible conductor as shown at 2|. Discharge valves 22 are provided between the cylinder H and the trunnions i5.

Oscillating movement of each cylinder H is controlled by its piston it. As shown in Fig. 3, each piston l3 is directly connected with the strap 23 around a disk 24. At a point oifset from its center, disk 24 is integrally connected to crankshaft 2E. The crankshaft 25 is mounted in suitable bearings 26 in the frame 12. Thus, it will be seen that the strap 23, disk 24 and crankshaft 25 constitute an eccentric. An ordinary crank could, of course, be used instead of the eccentric shown, the two being kinematically equivalent, and in the diagrams of Figs. to 8 cranks have been shown for ease in illustrating the operation.

In addition to tie provision of one eccentric disk 24 for each crank-end piston l3, there are two similarly constructed eccentric disks 2'! integrally connected to the crankshaft for each head-end piston M. In the arrangement shown there are thus three eccentrics or cranks for each cylinder, and these may be said to be a set of cranks. There are as many sets of cranks as there are cylinders. To avoid confusion in illustrating, Fig. 1 shows only one cylinder H with its piston actuating arrangement but it will be understood that all of the cylinders, no matter how many are used, have the same kind of piston actuating means. As shown in Fig. 1 and also as shown in Fig. 2, each head-end piston I4 is pivotally joined by cross connecting pin 3|] to two connecting rods 28 which are in turn directly connected to their respective straps 28 on eccentric disks 2?.

The disks 2'! for each cylinder are mounted alike and are spaced 180 degrees upon the crankshaft 25 from their cooperating disk 25 for the crank-end piston it. Only the piston it controls oscillating or swinging movement of the cylinder H as the crankshaft is rotated. The disks 2? drive the piston i4 through the connecting rods 28 and cross connecting pin the piston Hi with respect to the cylinder ii is different from that of piston IS with respect to the cylinder 1 i. The advantages of the present invention depend upon certain principles of operation in which the opposed pistons move in a.

30 but the motion of novel way, as will be apparent from a consideration of Figs. 5 to 9, inclusive, of the drawing.

Figs. 5 to 8 illustrate the basic principles of the invention. In these figure-s the same reference characters are used as those which designate corresponding parts in the structure shown in Figs. 1 to 4.

Thesefigures illustrate the'sequence of operation, during one complete revolution of the crank shaft, of the various parts of a single cylinder pump constructed in accordance with the invention. In these figures the crank 24 is shown as being of the same length as the crank 21. The pivot point for the cylinder (corresponding to the center of the trunnions H5 in Figs. 1 to 4.) is designated It. The exact center of the cylinder H is designated 3|. It will be seen that the distance from point It to point 3| is the same as the length of crank 24. It has been found by calculation that with these dimensions a very close approach to the desired simple harmonic motion is obtained and it has been found by experience that a pump having remarkable smoothness of operation is obtained when the parts are so constructed, but the advantages of the invention may be obtained, at least to some extent, if these dimensions are not followed exactly.

Fig. 5 shows the position of the parts when the cylinder H and cranks 24 and 21 are all horizontal with the pistons 13 and M near their inner positions. However, neither piston is then at its individual extreme inner position in the cylinder, as will be explained later. Except for a slight clearance, the net or resultant piston displacement in the cylinder H is zero when the parts are in the position of Fig. 5, and the pump has just completed its discharge or pump stroke. In traveling from the position shown in Fig. 5 to the position shown in Fig. 7, the pump makes its intake or suction stroke and in traveling from the position shown in Fig. 7 back to the position shown in Fig. 5, the pump makes its discharge stroke.

Assuming that the crankshaft 25 is rotated, as shown by the arrow, degrees to the right from the position shown in Fig. 5, the parts then take the position shown in Fig. 6. As the outer end of piston 23 is raised, the cylinder H is caused to swing to the right. The pistons are both leaving the center 3| of the cylinder by the time the parts are in the position shown in Fig. 6 but the piston l4 travels faster than the piston is during this 90 degrees of rotation. In fact, relative to the cylinder, the piston |3 travels slightly to the left of its position shown in Fig. 5 before .it moves to the right to take the position shown in Fig. 6. The initial cylinder motion to the right in Fig. 5 is greater than the initial motion of piston |3 in that direction. It will be seen that as a result of the cylinder motion, even by the time the parts take the position shown in Fig. 6, the piston i3 is still much closer to the center point 3| than is the piston l4.

Upon rotation of the crankshaft 25 another 90 degrees, as shown in Fig. '7, both pistons are near their outer positions but neither is at its individual extreme outer position, as will be explained later. Both are then equi-distant from the center point 3 I, and the net or resultant piston displacement in the cylinder is then a maximum and the intake stroke is completed.

Upon rotation of the crankshaft 25 the next 90 degrees, the parts take the position shown in Fig. 8. The cylinder H has now been forced to '6 swing to the left by the piston [3. The piston l4 positions shown in Fig. 5 and Fig. 7. The piston is then closer to the center point 3| than is the travel relative to the center of the cylinder is piston l3. quite different than it is relative to any other This construction causes variations in internal fixed point on the frame. Relative to the cylinvolume in the cylinder H which are remarkably der, the piston it does not reach the outer end close to ideal. As indicated above, an ideal single of its path of travel in the cylinder (the lowest piston reciprocating pump, insofar as smoothpoint on the curve 35 in Fig. 9) until after the motion is very undesirable. shown in Fig Likewise, the piston i3 reaches To illustrate and compare, in Fig. 9, angular the inner end of its path of travel after the crank travel for the discharge stroke of t o cranks have rotated some distance beyond the pumps is plotted against piston travel. The position shown in Fig. The pistons start and heavy curve 32 is the theoretic or ideal. It is a end their strokes in the cylinder at different curve of simple harmonic motion o th m ti times but the net or resultant effect of their obtained by the projection of uniform motion of Strokes is t t discharge Stroke of the p mp the crank pin of a pump on a diameter of the starts when the parts are in the position shown would be imparted to a piston in a fixed cylinder fi ShOWn i Fi if the piston were connected to the crank pin by AS ShOWH y curve oughout its entire a connecting rod of infinite length with the crank arge stroke, the pump has a net p s o dispin rotating at a constant angular velocity l m n w i h pl a h v ry l s ly th t of Th hghter curve ,3 of Fig 9 m t th 30 the simple harmonic motion curve shown at 32 a t al piston tr l i a ll designed ingle 1315- In all of the curves, it is assumed that the crankt pum iv t a t t; l t h shaft is being rotated at a uniform velocity. If particular pump selected for computing the data there is any Variation n velo ity during the used to make this curve is a, m de -n pump used StIOkG, Of OOUISG these curves 010 not hOld true. by the Halliburton Oil Well cementing Co., and 535 The lack f un rmity 0r synchronism of inkhewn as Model 1 h ti of connecting dividual piston movement illustrated by curves r d t r n is 4,2 35 and 36 is due to the fact that the pivot point Th dashed hne curve 34 of Fig" 9 Shows the E6 of cylinder H is offset from the center point 3| But while the piston I3 is traveling away from desirable to employ dimensions other than those the center of the cylinder l i during the initial here indicated as the most desirable It is obart of the discharge stroke of the pump, the vious therefore that while 0 piston M is traveling toward the piston is at a greater rate as shown by the slope of the lower is that piston displacement or Volume ing from the spirit of the invention or the scope As mentioned above, a peculiarity of this pump In a reciprocating pump frame, crankis t t t pistons do not travel in unison The shaIt mounted for rotation on the frame, cranks individual piston travel is such that each is not On the Crankshaft ngularly spac d Substa t a y '7 pistons in the cylinder and means connecting each-piston'to'one of said cranks.

2. In a multiple cylinder reciprocating pump, a frame, a crankshaft mounted for rotation on the frame, a plurality of sets of cranks, each set having at least two cranks on the crankshaft angularly spaced substantially 180 degrees, a plurality of cylinders, one for each set of cranks, trunnions fixed to the cylinders and arranged in lin and offset vertically from the centersof the cylinders, bearings for the trunnions secured to the frame whereby each cylinder is mounted for individual oscillation on the frame, twoopposed pistonsin each cylinder, and means connecting each piston to at least one crank on the crankshaft.

'3. In a reciprocating pump, the combination of a frame, a crankshaft mounted for rotation thereon, a plurality of cranks 0n the crankshaft angularly spaced substantially l80-degrees, a cylinder, means for'pivotally mounting the cylinder for oscillation on th frame, said means consisting of trunnions offset vertically from the center of the cylinder whereby the cylinder swings horizontally ERLE P. HALLIBURTON.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 837,342 Ross et a1. Dec. 4, 1906 68,703 Ross et a1. Oct. 22,1907

1,069,015 Jabusch July 29, 1913 1,286,122 Sargent Nov. 26, 1918 1,515,703 Ross Nov. 18,1924

1,713,344 Lewis May 14, 1929 1,724,553 Bennett Aug. 13, 1929 FOREIGN PATENTS Number Country Date 4,421 Great Britain '1880 14,798 Sweden Aug. 6,1901

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