US2677966A - Mechanical movement - Google Patents

Description

May 11, 1954 H. G. MUELLER MECHANICAL MOVEMENT Filed Dec. 1, 1952 3 Sheets-Sheet l nnentor (Ittorneg nm. kom

HERMAN @M4/MLA M /wg May 11, 1954 H. G. MUELLER MECHANICAL MOVEMENT 3 Sheets-Sheet 2 Filed Dec. l, 1952 abn Gttorneg May 11, 1954 H. G. MUELLER MECHANICAL MOVEMENT 5 Sheets-Sheet 5 Filed Dec. l, 1952 Snventor HERMAN G. MUEL/a M /ZlI/meg Patented May 11, 1954 UNITED STATES ijATNT OFFICE 6 Claims.

This invention relates generally to pumps and more particularly to hydraulic multi-cylinder liquid pumps driven from an external power source and customarily usedV in lifting the liquid to be pumped, by suction, from a sump and forcing it against hydraulic pressure into a discharge line.

This application is an improvement of my pump disclosed in Patent No. 2,607,296, issued August 19, 1952.

ln my said patent, I disclose a pump having two double acting parallel cylinders, each containing a piston'. Each piston is actuated by a pair of equal cams mounted on and rotated by a common shaft, the pair of cams for one piston being disposed at an angle of ninety degrees from the pair of cams for the other piston. Each cam operates two followers, one on either side of each cam. The four followers for each pair of cams are mounted on two cross heads disposed between the pair of cams and rigidly tied together with tie rods. The cross head nearest the piston is rigidly secured tothe piston rod for actuating its piston.

In the pump disclosed in my said patent, I have disclosed the roller followers mounted on two cross heads rigidly tied together with tie rods. The pistons are at their greatest distance from the center of the cams when they are in the extreme left position and nearest the center of the cams when in extreme right position. On the forward stroke, the right rollers supply the thrust of the piston, discharging the liquid out of the crank end of the cylinder, and these rollers will necessarily be securely in contact with the cams. Due to the tension in the tie rods and cross heads, the left rollers may move out of contact with the cams during this stroke, leaving a small clear ance between the cams and rollers. When the cams have rotated one hundred eighty degrees from the extreme left position, the crank end dead center is reached and as the cams move past dead center and begin the return stroke, the thrust from the piston is reversed for dischargn ing the liquidA from the head end of the cylinder. This reversal suddenly brings the left rollers in contact with the cams and relieves the stress on the right rollers but, on the return stroke, less clearance between the cams and right rollers results since the tension is relieved in the tie rods.

After the cams have turned one hundred eighty degrees further, bringing the piston back to the extreme left position, the right rollers will again suddenly contact the cams relieving the left rollers. Thus, a metallic take-up may occur at each dead center, causing a knock twice per revolution which may damage the cams and rollers.

This knock may be reduced considerably and, in some cases, entirely removed by pre-stressing the tie rods. However, it becomes apparent that with a piston thrust of thirty-two thousand pounds, normal for a seven inch stroke pump, this pre-stress in the tie rods and cross heads will have to be somewhat in excess of thirty-two thousand pounds or about thirty-six thousand pounds, so that on the forward stroke when the tie rods are in tension, the pre-stress is still sufficient to hold the left rollers on the cams. Thus, the load on the right rollers on the forward stroke will be the thirty-two thousand pound thrust of the piston plus the excess of the prestress above thirty-two thousand pounds, holding the left rollers on the cams, or a total equal to the pre-stress of thirty-six thousand pounds.

On the return stroke, the left rollers assume the piston thrust and no part of the piston thrust is carried by the tie rods. The total load on the left rollers will be that due to the pre-stress in the tie rods plus the piston thrust, totaling thirtytwo thousand pounds plus thirtyssix thousand pounds, or sixty-eight thousand pounds. Thus, the load on the left rollers is more than double the piston thrust and will require over-sizing to give the same life as that for the right rollers,

It is, accordingly, an object of this invention to provide a novel cam and follower mechanism in combination with a cam actuated double acting pump.

Another object of the invention is to provide a double acting cam actuated pump in combination with a novel means for eliminating noise and wear in the cam and follower piston drive assembly.

Another object of the invention is to provide a novel spring arrangement to continuously maintain roller followers in contact with a driving cam in a double acting pump.

Another object of the invention is to provide a novel means incorporating a novel fluid pressure device for continuously maintaining the followers in contact with the cam surface in a double acting pump.

Another object is to provide a pump which will be enicient in use and economical to manufacture.

Another object of my invention is to provide a liquid pump capable of high speeds while eliminating the noise and wear usually incidental to such pumps.

With the above and other objects in view, the present invention consists of the combination and arrangement of parts hereinafter more fully described, illustrated in the accompanying drawings, and more particularly pointed out in the appended claims, it being understood that changes may be made in the form, size, proportions, and minor details of construction without departing from the spirit or sacrificing any of the advantages of the invention.

In the drawings:

Fig. 1 is a longitudinal sectional View of a double acting pump incorporating my novel cam arrangement;

Fig. 2 is an enlarged sectional View of the cam assembly shown in Fig. 1; and

Fig. 3 is an enlarged sectional view of another embodiment of the invention showing the cam assembly.

Referring now to the drawings, Figs. 1 and 2 show a crank case i mounted on skids 2. Top covers l are provided on the crank case I for ready access to piston rod packing cases 5 and 6. A main cover l' is disposed on the top of the crank case i. The fluid casing 3 is disposed longitudinally of the crank case l and has formed therein liquid pumping cylindrical portions 9 connecting closed chambers i@ and il. Apertures Iii in the casing il have seats I 3 for seating inverted conical shaped valve heads i5 guided by stems i5. Covers IT have depending cylindrical portions IS with coil springs I9 therearound to urge the valve heads i5 into sealing relationship with seats I5. Covers I'i close apertures 2Il in the discharge chests 2i in the upper part of casing 8.l Discharge outlet 22 leads outwardly from chests 2 A shaft 29 is journalled in a sleeve 36 and is transversely mounted below the casing 8 and has iixedly mounted thereon two impellers 3|, one with right and the other with left hand vanes disposed in annular casings 33 on opposite ends of shaft 29 and to increase the pressure of uid entering annular casings 33 from the inlet line 35 and passing through to the chambers IIJ and E i through a valved suction passage (not shown).

Crank case I has hub member 6| Two pair of eccentric hubs |56, one pair for each piston, are cast integral with hub member 6I one pair being spaced ninety degrees from the other. The throw of each eccentric is preferably made equal to onehalf the piston stroke. Around each eccentric is shrunk a hardened and ground cam ring 59.

Engaging each cam ring 59 are two follower roller tires 69 shrunk over and encircling roller bearings 8c mounted on transversely extending shafts le. One shaft I is integral with cross head 'i2 and the other is integral with cross head lab. Each pair of main cross heads 'i2 and 72b are tied together with two main tie rods 56 and two lighter auxiliary tie rods 56h. Main tie rods 55 have nuts 55 at their inner ends with integral heads 551; at the outer end for removal through the opening closed by cover 51. The auxiliary tie rods have nuts 55o at either end for adjusting the tension in helical springs 56d. This tension is adjusted to insure contact of the idling followers on their cams with either stroke of the piston and is constant and independent of the tension in the main tie rods 56 applied during the forward stroke of the piston and relieved during the return stroke.

Guideways f and 'I6 can he adjusted vertically with shims in order to adjust the clearances between the upper guideway 'I6 and the lower guideway I5 and the tires 69a so that tires 69a can roll on either the upper or the lower guideways "I6 or l5 and clear the opposed guideway.

The inner ends of the main tie rods 56 extend through apertures 55j in cross heads "I2 and 12b and are secured to third cross heads 12a by nuts 55. Extension rods 53 have tapered ends 58C which are fitted into tapered aperture 58g in cross heads i2a and locked therein by keys 58a. The other ends of the extensions 58 are threaded internally for threadably engaging the threaded ends of piston rods 5I with nuts 8 I. Splash plates 62 are secured between nuts 8| and cross head extensions 58. The extensions 58 are oil sealed by packing boxes 6. Piston rods 5| have conventional piston heads 33 secured thereto in the cylindrical portions 9 of the casing 8 by the internally threaded end 84 of extensions 85 of the rods 5I serving as a tail rod of the same diameter as the piston rods 5| to equalize the displacements of fluid from either side of the piston heads 83. On either side of the piston heads 83 are mounted conventional rubber packings 86 secured with follower plates 8l.

The rubber packings 86 ride on hard liners 89 sealed with a conventional rubber gasket 9 I The piston rods 5I and the tail rods 85 pass through duplicate stuffing boxes 5 and 82 with conventional duplicate rubber packings 53 and S4 and follower glands 55 and 96. The liners 89 are pressed into the cylindrical portions 9 of the casing 8. It will be evident that the two chambers ill and II are duplicates of each other and have duplicate liners, pistons, rods, and packing boxes for each cylinder.

A pulley IUD is mounted on the shaft 63 and rotative force is transferred to the shaft 29 by V-belts. The shaft 63 is driven from a main power source such as a gas engine, diesel engine, steam engine, or electric motor. It will be evident that any form of drive may be used between shaft 63 mounted in the crank case I and shaft 29 mounted in the casing 33.

In operation, the shaft 63 is rotated by a suitable power source, thereby rotating the pulley IGI) mounted thereon to drive the shaft 29 carrying the impellers 3|, The rotation of the shaft 63 with cams 5S attached thereto causes the reciprocaticn of the piston rods 5| and the pistons 83 attached thereto. The discharge Valves I5 in the chambers I0 and I I on each end of the cylindrical portions 9 of the casing 8 open and close in accordance with the pressure variations caused by movement of the pistons 83. The fluid entering chambers I0 and II is placed under pressure by the impellers 3| to follow the pistons 83 and to prevent cavitation.

On the discharge stroke of the pistons 83, the discharge Valves I5 are opened by pressure on their under side from the pistons 83 and the discharge valves then communicate chambers I0 or I I to the discharge chest 2| which is open to all four discharge valves I5 and leads to the discharge line 22.

One embodiment of the improved cam follower arrangement is shown in Fig. 1 with an enlarged view in Fig. 2. At each end of main tie rods 5B, steel plates 58h are disposed around tie rods 56 and resilient platens 51a made of rubber or other suitable material are disposed between cross heads 'I2 and 12b and steel plates 58D. The cross heads 'I2 and '12b are slidably mounted on tie rods 56 by clearance holes 567 to permit a small relative movement between the tie rods t and cross heads and 12b with changes of tension in the tie rods between the fcrw'ard and return strokes and to permit alternate compression and expansion of the two rubber platens lila.

rl'he inner or left ends of tie rods 5t are secured to the third cross head lZa by nuts and this cross head '52a is in turn secured to extension rod 53 which actuates the piston. The auxiliary tie rods 55h are threaded at either end to receive nuts 55e and are also slidably mounted on cross heads l2 and 12b through clearance holes 46a. Helical springs 56d are adjusted for tension with nuts 55C to give a constant load of the followers E9 on the cams d during each idle stroke.

Thus, with proper adjustments of nuts 55e to control the compression in springs iab and with proper adjustment of nuts 55 for pre-stressing the compression in rubber platens dla, no excessive loads on the working stroke beyond that of the piston thrust is applied and the followers always remain in contact with the cams on the idle stroke.

In the embodiment of the invention shown in Fig. 3, the piston rod E55 is shown connected to the cross head l'ia. rlhe only tie rods les pass through close ttng holes i59a in cross heads Elia and extend through clearance holes i597; in cross head H217, through clearance holes ic in cross head i120, and through close fitting holes 259e in cross head Il?. The inner ends of rods (5t are threaded to receive nuts iii and have heads 1550i at the outer ends thereof. The nuts 55 engage cross heads l'l2a and the heads I55a engage the cross heads H2. Cylindrical pistons i832 are forged integral with cross heads Elib and extend into close tting cylinders m5 bored in cross heads liga. Each piston H12 is tted with conventional chevron layer or plastic packings ills and adjustable gland itil to form an cil type seal between pistons ist and cylinder bores its.

Oil feeder holes it are drilled through pistons itl and out one side of cross heads Hab. Oil supply line lill is connected t0 holes i through check valves Hi8. One end of line lill is provided with swivel joints ist and constant length pipe nipples iis which contain a constant volurne of oil. The oil for the cylinders E82 is supplied by a constant displacement oil pump lil which is driven by a chain it and sprockets il? from the main shaft its. A spring loaded oil relief valve H3 is fitted in the pump discharge to maintain a constant pressure of about seventy-five pounds per square inch in the oil supply line lill and cylinders lsb when the main pump is operated.

Similarly, on the right ends of tie rods 53, cylindrical pistons id'la are forged integral with cross heads H120 extending into cylinders iiliia bored in cross heads V52. Similar chevron packings wie are adjusted by glands idea forming an oil tight seal between pistons iiiZa and cylinder bores Nida. Similarly, oil feeder holes llliia pass through pistons i021; and out the side of cross heads i'ic and are supplied with oil through check valves iila from oil line i ill.

When the main piston is being drawn forward toward the center of the cams it, the load will be applied to followers 659e moving piston lilZa approximately ten-thousandths of an inch into cylinder I 85a until check valve i @da closes. After check valve ilc closes, the oil in cylinder Milla will be compressed until the pressure acting on the piston area equals or slightly exceeds the pistn thrust. This thrust will be transmitted by tension in tie rods |56 to cross head i'iZa and in turn by tension in extension 25d to the piston, leaving cross head H2!) unloaded. Since at this point oil pressure in oil line it? is increased and is decreased in hole it, check valve i will open, exerting a small pressure on piston m2 which multiplied by the area of piston i552 is the load applied to idling follower its at this point of the stroke and which insures its contact with the cam.

When the crank end of the stroke is reached and the piston is reversed, the load will be applied to follower It, moving oilpiston W2 inte cylinder 85 until check valve HB8 closes, thereby building up the oil pressure in cylinder i to the amount needed to actuate the piston through cross head lilla. Simultaneously, cross head i'igc and follower Issa will be unloaded and oil will enter from oil line lill through check valve iila, exerting this small ypressure on piston iilZd to maintain follower U59@ in contact with cam its during its idle stroke.v The pressure in line lill is adjustable by relief valve H3 so the follower lead on the idle stroke is readily7 adjustable.

Thus, the reversals ofthe cylinders at dead center are eased, the rollers always remain in contact with the cams, the roller maximum load is only a small adjustable amount in excess of the piston thrusts, and all metallic shocks are eliminated, insuring a quietly operating pump and no brinelling of the rollers on the earns.

in my improved pump with the pistons operated by properly designed cams, much higher speeds are permitted, giving not only a constant flow without pulsations but also easing valve impacts and all knock between cams and followers are entirely eliminated.

In the foregoing specication, I have set forth the invention in its preferred practical forms but am aware that the structure shown is capable of modifications within a range of equivalents without departing from the invention which is to be understood is broadly novel as is commensurate with the appended claims.

What I claim is:

1. A shaft oscillating mechanism comprising a shaft, a first cross head attached to said shaft and movable therewith, a second cross head, tie rods extending through said cross heads, a rst auxiliary cross head associated with the first cross head and a second auxiliary cross head associated with the second cross head, a follower on each auxiliary cross head, a cam engaging the followers, andmeans disposed between each of said first cross head and said first auxiliary cross head and between said second cross head and said second auxiliary cross head to apply a pressure therebetween, said means comprising an oil cylinder on one cross head and a piston operable therein, and means to supply oil under pressure to said cylinder.

2. A shaft oscillating mechanism comprising a shaft, a first cross head attached to said shaft and movable therewith, a second cross head, tie rods extending through said cross head, a first auxiliary cross head associated with the first cross head and a second auxiliary cross head associated with the second cross head, a follower on each auxiliary cross head, a cam engaging the followers, and means disposed between each of said cross heads and each auxiliary cross head to apply a pressure therebetween, said means disposed between said cross heads comprising a cylinder on one cross head and a piston operably associated with the cylinder, a piston in the cylinder engaging the auxiliary cross head, means to supply oil to said cylinder, and a check valve between said oil supply means and said cylinder.

3. The mechanism recited in claim 2 wherein the means to supply oil to the cylinder comprises a pressure regulated oil supply means, a bifurcated pipe line having a branch to each cylinder conducting oil from the supply to each of said cylinders, and a check valve in each branch of the line whereby oil is allowed to flow from said supply to said cylinders and the flow of oil from said cylinders is opposed by said check valves.

4. A shaft oscillating mechanism comprising a shaft, a rst cross head attached to said shaft and movable therewith, a second cross head, tie rods extending through said cross head, a first auxiliary cross head associated with the first cross head and a second auxiliary cross head associated with the second cross head, a follower cn said auxiliary cross heads, a cam engaging the followers, and means disposed between each of said cross heads and each auxiliary cross head to apply a pressure therebetween, said means disposed between said cross heads comprising a cylinder on the cross head and a piston operably associated therewith on the auxiliary cross head, means to supply oil to said cylinder, a check valve between said oil supply means and said cylinder, and a pressure regulating means between said cil supply source and said cylinder.

5. A shaft oscillating mechanism comprising a shaft, a first cross head attached to said shaft and movable therewith, a second cross head, tie rods extending through said cross head, a first auxiliary cross head associated with the first cross head and a second auxiliary cross head associated with the second cross head, a follower on each auxiliary cross head, a cam engaging the followers, and means disposed between each of said cross heads and each auxiliary cross headto apply a pressure therebetween, said means disposed between said cross heads comprising a cylinder on the cross head and a piston opera-bly associated therewith on the auxiliary cross head, means to supply oil to said cylinder, and a check valve between said oil supply means and said cylinder, said pressure source being attached to a xed part of the machine.

6. A mechanism comprising cams, means to rotate the cams, two followers disposed on opposite sides of said cams, cross heads attached to said cams, tie rods extending through said cross heads, a resilient platen disposed on each of said cross heads, means on each tie rod engaging one resilient platen and means on the tie rod engaging the other resilient platen and an end of said tie rod opposite said one platen connecting said tie rods, a shaft, auxiliary tie rods connecting said cross heads, and resilient means on said auxiliary tie rods urging said cross heads toward each other.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 544,380 Roberts Aug. 13, 1895 1,070,706 Luitwieler Aug. 19, 1913 1,191,256 Wllers July 18, 1916 1,382,450 Baker June 2l, 1921 1,411,517 Reineke Apr. 4, 1922 2,607,296 Mueller Aug. 19, 1952 FOREIGN PATENTS Number Country Date 440,724 Italy Oct. 16, 1948

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