US1070706A - Driving mechanism for triplex pumps. - Google Patents

Description

S. W. LUITWIELER.

DRIVING MECHANISM FOR TRIPLEX PUMPS.

APPLICATION FILED DEC. 29. 1910.

Patented Aug. 19, 1913.

4 SHEETS-SHEET 1.

Samuel woodsjuiiwieler Wi t/1404mm 711213 6 Norm c 1 1 S. W. LUITWIELER.

DRIVING MECHANISM FOR TRIPLEX PUMPS.

APPLICATION FILED 1330.29, 1910.

Patented Aug. 19, 1913.

4 SHEETS-SHEET 2.

8 wue'nto z fin/mud Woods Zuiiu'ic (GT LLLL .J-U LU LLLL LLJJUJ LLL-LLLI wmwm s. W.- LUITWIELER. DRIVING MECHANISM FOR TRIPLEX PUMPS.

APPLICATION FILED DEC. 29, 1910.

Patented Aug. 19, .1913.

4 SHEETS-SHEET 3 Samuel E/oqds luii wiele r 1 11 5 flflozuu a s. W. LUI WIE BRQ DRIVING MECHANISM FOR TRIPLEX PUMPS.

APPLICATION FILED DEC. 29, 1910.

Patented Aug. 19, 1913.

4 SHBETSSHEET 4.

z .m Wm H Z w 6 SAMUEL w. LUITWIELEEOF ROCHESTER, new YORK.

DRIVING MECHANISM FOR TBIPLEX PUMPS.

ora-z To aZlw/wm it may concern:

Be it known that I, SAMUEL Woons LorrwmLEn, of Rochester, in the county of Monroe and State of New York, and. a citizen of the United States, have invented certain new and useful Improvements in Driving Mechanism for Triplex Pumps; and I do hereby declare the following to be a full, clear, and exact description of the same, reference being had to the accompanying drawings, forming a part of the specification, and to the reference-numerals marked thereon.

My present invention has for its object to provide mechanism for operating the reciprocating pistons or plungers of a multi-cylinder pum'p whereby a constant rotating driving power may be translated into a reciprocatory mot-ion of the pistons during their complete strokes in opposite directions and a relative uniform movement of the several pistons also attained whereby the pump will pr duce a steady discharge ot water en; tirely free from pulsation.v 1n carrying out this object my invention further comprehends an arrangement of parts where the pump plungers may be operated at a sutficiently high rate of speed to obtain any desired pressure of the water.

To these and other ends the invention consists in certain improvements and combinations of parts, all as will be hereinafter more fully described, the novel features being pointed out in the claim at the end of the specification.

In the drawings: is igure 1 is a View showing the side elevation of the pump driving mechanism, constructed in accordance with myinvention, connected to a pump; Fig. 2 is a top plan view thereof; Fig. 3 is a diagrammatic view illustrating the three-cams employed in operating a triplex pump, showing their relative arrangement; Fig. 4, is a similar view of a single cam and illus trating it in two differentpositions; Fig. 5 is a detail sectional view taken on the line 5"5 of Fig. 1', showing the bed frame in end'view and the cross heads guided thereon; Fig. 6 is a diagram showing the discharge and suction of a triplex pump operated by driving mechanism embodying my invent-ion; and Fig. 7 is a diagram showing the movement of a piston.

Similar reference numerals in the severalfigures indicate similar parts.

In the operation of all high-duty or pres- Sure reciprocating pumps the primary desid- Specification of Letters Patent.

Patented Aug. is, iais.

Application filed December 29, 1910. Serial No. 599,844.

eratum is to cause the water, or other liquid operated upon, to flow in a constant stream both in the intake or suction pipe and the outlet or discharge pipe, and to this end an air chamber is customarily employed in conjunction with the discharge pipe or chamber to reduce the pulsation or jar transmitted to the body of the water in the pump chambers as it is forced outwardly, and which is imparted to the water by the unequal rate of travel of the pistons during different portions of their strokes. The action just described will be recognized as that resulting from the uneven rate of movement during the reciprocation of pistons driven by rotating crank arms and equivalent eccentrics. A multi-cylinder pump provided with a plurality of double acting pistons operated by rotating crank arms of which the present well known type of triplex pumps is the best example is the nearest approach, so far as I am at present informed, to obtaining an even steady discharge of water. This type of pumping. apparatus in which perfection in construction and results are so far superior to previous accomplishments in this di rection that it has been generally accepted as the best that could be attained, still possesses numerous disadvantages. Of these the most important are the size and weight of the parts necessary to obtain the requisite piston stroke and the expensive and heavy foundations required for the apparatus. Even such a pump is subjected to considerable vibration occasioned by the variation of fact that on account of the unequal rate of travel of the pistons during each rotation of their respective cranks, a slight cessation occurs periodically in the movement of the water. So far as the stream itself is concerned the pulsation of the water may be minimized by the use'of the air chamber, al'- though' not entirely removed as evidenced by the spurting appearing at the end of a stream discharged from an open nozzle. The employing of the air chamber does not, however, reduce the vibration which this intermittent movement of the water imparts to the pump itself, and this is an important factor asit determines to a large extent the size and weight of the parts necessary to withstand the constant strain imparted to them..

In my'experiments T have'discovered that by employing a plurality of cams of peculiar shape, and by arranging them in particular angular relation to each other, power may be transmitted to the Water or fluid column to cause a constant and uniform fiow or rate of travel, one piston picking up the load before another piston releases it, this action continuing constantly and resulting in the production of a constant flow from the discharge pipeof the pump and without vibration in the pump itself. By overcoming theyinherent disadvantage in the operation of a pump in which the istons are not operated to produce this uniformity, I am enabled to produce a constant and steady flow from the discharge pipe of the triplex pump irrespective of whether the pump cylinders and their respective pistons be of the .single acting or double acting types, al-

though I prefer to employ the latter on account of the increased. volume of liquid which can be passed through the pump.

In illustrating one embodiment of mypresent invention I have shown it employed as a means of operating the three piston rods A, B and C of a triplex pump, comprising the casing D containing the usual pump cylinders and suction and discharge cham-v bers d, (1, respectively, but it will be understood that any usual or preferred pump casing and interior mechanism may be employed in lieu of the specific structure illustrated. The casing and pump driving. mechanism may be mounted u Tm any suitable base or support 13, an while these parts are shown in a horizontal position, it will be understood that they may be disposed vertically, should such an arrangement be desired.

In carrying out my invention I employ three similar peculiarly shaped cams A and G, constructed substantially as shown in detail in Fig. 4, which are arranged relatively to each other on the driving shaft F, as shown in Fig. 3. Each of the cams is oflset from the shaft at one side a greater distance than at the other, corresponding diameters in each cam being 120 apart. Considerable'importance is attached to laying out the working faces of thesecams to produce a uniform rate of travel of their pistons during that portion of the stroke when their respective pistons are working alone and carrying the whole load, to the. end thatthe objections due to a lack of uniformity in the rate of travel of a crank operated piston may be overcome. In addition to this those. portions of the cams lying between the parts of the faces just men'- tioned and the bases and points of the cams are equally important since they control the cooperative action of the pistons when two of them are working together, at those portions of the strokes where both are traveling in the same direction. At such times the decreasing movement of the first piston,

and when this reaches the end of, its stroke then the second piston must be carrying the full load. The third piston during this period is traveling in the opposite direction,

the cooperative action of the three pistons being such that when two of them are traveling in the same direction the volume of Water discharged by them is equal to the volume of the water discharged by the third piston operating in the opposite direction. This general explanation may be better comprehended from the diagram shown in Fig. 6, in which the suction and discharge action of three double acting pistons operated by cams shaped and arranged as set forth above is illustrated. In this diagram K indicates the zero line, L the line of maximum discharge during the travel of the pistons in one direction, and M the line of maximum discharge during the travel of the'pistons in the opposite direction. Let the full heavy line A represent the'volume ofthe Water discharged during the movement of the piston operated by the cam A, the-dot and dashline B the volume of the water dis- 5 charged by the movement of the piston operated by the cam B and the dotted line C the volume of the water discharged by the movement of the pistonv operated by the cam C. the pressure lines above the zero point K represent the amount of water discharged by the severalpistons during their movement in one direction, the same being true in respect to the ordinatesto the pressure 5 lines below the zero point which represent the volume of water discharged by the pistonsduring their movement in the opposite direction. The horizontal distances indicated in this diagram represent equal rotary 11o movements of the cams through angles of sixty degrees. During the first part of the movement of the piston A through an arc" of sixtyde rees the output or discharge increases uni ormly from zero to its maximum 5 quantity and {at the same time the discharge of piston C falls .nniformly from its maximum quantity to zero, the combine d outputs of the two pistons during this time being equal to the quantity of either plston 29 when working alone. Now while this increasing and decreasing of the discharge of q the two pistons is taking place the third piston B is moving in theopposite direction at a 11I1lfOI'II1 rate of travel, maintaining the water discharged at the maximum quantity 'and'thus giving a uniform pressure in the pump. This action reoccurslin every sub'-.

sequent period of rotation throu h arcs of sixty degrees, and at all pointso the rota- In this diagram the ordinates to tion of the cams the combined discharge of the three pistons is equal to twice the quantity discharged by any one of them when working alone. g

In the practical application ot the prin ciples applied to the operation of my pump driving mechanism, 1 provide each piston with a pair of cross heads It and k located at opposite sides of their respective cams which are preferably connected by tie rods 7' and la and in these heads I journal the bearing rollers acbb c0 which cooperate with the respective cams A, B and C. These rollers are applied as the simplest means of reducing the friction but their use introduces a new element to be considered in designing the Working faces of the cams, because as different portions of their faces roll into contact with the peripheries of the rollers the points of contact shift successively to one side or the other of the plane passing through the axes of rotation of the cams. and rollers. tice I obviate this difiiculty and obtain the outline of the true cam in the following manner: The movement to be imparted to each of the pistons to produce the diagram of discharge illustrated in Fig. -6 is plotted for a piston assho-wu in the dia ram Fig. 7, in which the lengths of the or inates indicate the distance the piston must travel for a given angular movement of a cam, the horizontal distances between said ordinates indicating equal angles, and the resultant or curve connecting said ordinates represents the movement ot the piston. Equidistant radii drawn from the center of the shaft F on which the'lengths determined by theordinates in Fig. 7 are measured will give a curve such as 11 shown in dotted lines in Fig. 4 passing through the centers of the bearing rollers a-a. Now by describing arcs on these radii of the same radius as the bearing rollers the necessary points are established defining the circumference of the cam, which when cooperating with hearing rollers will produce the proper movement of the piston irrespective of the 10021-- t-ion of the points of contact of said cam and rollers in reference to the, common plane of the axes of rotation of said parts.

A portion of the operating face of each cam lies nearest to the shaft 3F and is almost flat, providing a base asindicated at 1, while its opposite side or point, indicated by 2, is.

face of the cam, it will be seen that the lat ter during its rotation through an angle of 180 degrees will cause said rollers to travel ln prac-- upon describing a complete circle will cause them to be returned tothe full line position The cam rotating in the direction of the arrow, indicated :by 5 in Fig. 4, will at the commencement of its movement cause the flattened portion of its face 1 to roll, or travel, around the face of the roller a for a short distance only slightly displacing the roller laterally at first but continuing to move it with increasing speed until about the time the point '3 indicated on the cam comes into engagement with the face of the roller. From here on to the point 4: the swell of the cam is pronounced and will imparta uniform rate of travel to the roller a until the point i contacts with the roller, from which point the cam permits a gradual decreasing movement.

it will be appreciated that a cam constructed as thus described is capable of being rotated at a comparatively high speed since both rollers are in contact with opposite poi-nts on the face of the cam at all times there is no lost movement in the pump piston or plunger connected to them. Another important teature in the construction of the cams in the manner described is found in the fact that they are symmetrical, thus permitting them to be rotated-in (ither direction. This is a distinct advantage as it enables either half of a .cam face to be used as the working surface permitting it to be reversed on the shaft should occasion require, or the shaft with its several cams might be turned end for end.

Each of the cams A, l3" and 0 constructed in the manner described, are rigidly connected with the shaft F relatively to each other, as shown particularly in Fig. 3. In other words, lines representing corresponding diameters in each cam extend radially of the axis of rotation at equidistant angles. In the figure last referred to, there are also shown the several sets of rollers a and a J) and b and c and c coiiperating with their respective cams in the respective positions which they assume.

lhe driving shaft F is arranged transversely in front of the pump casing D and journaled in bearings f on a bed or table G, which may be separate from or constructed as part of the support or base E. This bed is slotted longitudinally to receive the several cams, the-slots extending centrally of the pump pistons or p'l-ungers and having v inner and outer cross heads "/1. and h are guided, these being arranged in pairs, those of each pair occupying positions at opporespective cams, the length of said rods being adjustable by meansof the nuts threaded on their extremities, as indicated, whereby the rollers may be adjusted relatively to each other to cause their proper cooperation with the-faces of the respective cams. The several yoke frames thus constructed are connected tothe ends of the piston rods A,

B and C as shown.

Any suitable source of power may be employed for rotating the driving shaft F and in the present instance I have shown the latter provided with the gear wheels F meshing with the pinions O on the-shaft 0',

carried in bearings on the base E, and provided with a gear wheel 0 to which power may be transmitted by the pinion on the armature shaft of an electric motor, which is omitted from the present illustration,

Referring again to the particular shape of the cams and their respective arrangement to each other, it will-be observed from an examination of Fig. 3, that the piston U operated by the cam C, is nearing the completion of its stroke in a direction toward the right in the illustration, and that at this time the cam A is picking up the load by commencing to move the piston A in a direction toward the right, while the cam B is operating the piston B in the opposite 'direction or toward the left at full speed, As the point and the base of the cam C pass into alinement with the centers of therollers c and 0 its respective piston reaches the limit of its outward movement in the cylinder and then commences to travel in a reverse direction to that described, or to- Ward the left, before the piston B, operated by the cam B, reaches the limit of its movement, and these alternating perfectly timed reciprocations of the'several pistons is such that a uniform pressure is at all times main tained upon the liquid in the pump chamber and the pipes connected thereto, so that there is no stopping orstarting of the liquid to create a jar or vibration and produce what is ordinarily termed Water hammer.

Numerous advantages are obtained by employing pump driving mechanism embodying my invention, the principal one of which is that'by reason of the fact that I am enabled to obviate all pulsation in the stream, a very high percentage of efficiency can beobtained from the pump, resulting in the saving of aE-igh percentage in the any of the commercial types of pumping apparatus in use at the present time. The

lack of vibration in the apparatus also'per mits the parts of the pump and driving mechanism to be made considerably lighter in weight than has heretofore been considered feasible in machines of this character. This it will beappreciated, also has an important bearing upon the original cost of manufacture, the expense of transportation and erection, and in the end lessens the ex pense of maintenance. By providing driving mechanism for a multi-cylinder pump whereby a continuous discharge may be obtained from the pump which is devoid of all pulsation, I am also able to increase the capacity of a pump having cylinders of given diameter and length of stroke. It may be conversely stated that driving mechanism for pumps embodying my present invention will enable a given quantity of water or other fluid to be handled by a pump of smaller dimensions than would be required where jar or vibration is imparted to the Water by the action-of the pistons. other point of advantage to be attributed to this mechanism is found in the fact that where it is desired to discharge a stream of water from an open pipe or nozzle, the stream being without pulsation may be disfact that the continuous uniform action of the pump plungers, when operated by my improved driving mechanism, produces such a perfect balance when working under full load that there is no back lash and the driving mechanism can, therefore, be geared directly to the-armature shaft. of an electric motor or other continuously operating source of driving power.

I claim as my invention;

In' a drivi mechanism for triplex pumps, the com inationwith a frame provided with longitudinally extending slots spaced apart, a transversely extending driving shaft journaled on the frame, open yoke frames guided in the slots of the bed frame at opposite sides of the driving shaft, and rollers journaled at the'ends of the yoke frame in alinement with the axis of the driving shaft, of three cams secured to the shaft, one of which rotates in each yoke frame and the corresponding slot in the bed frame, each of said cams having a point and a base portion offset unequal distances from opposite sides of its axis and having a contour so shaped that during each rotation it will reciprocate its cross head imparting thereto a lateral movement in opposite directions commencing with a con- 5 stantly increasing rate of movement until the maximum speed is attained, then continuing at a uniform rate of. travel and fin-- ishing with a constantly decreasing rate of travel, the several cams being disposed relatively onthe shaft so that"corresponding w .diametersof the several cams radiate at equidistant angles about the shaft.

' SAMUEL W. LUITWIELER. Witnesses:

FREDERICK W. SMITH,

G. WILLARD RICH.

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