US2919591A - Operating mechanism for injectors - Google Patents

Description

Jan. 5, 1960 o. E. wATsoN 2,919,591

OPERATING MECHANISM FOR INJEcToRs Filed June l0, 1957 Afro/wey.

United States Patent C) OPERATINGv MECHANISM FOR INJECTORS Orla E. Watson, Mission Hills, Kans.

Application June 10, 1957, Serial No. 664,661

` s claims. (ci. 74141.s)

This invention relates to new and useful improvements in operating mechanisms for injectors, and has particular reference to injectors of thetype adapted to deliver iluid at very low rates. For example, such an injector is often used to add a demulsifying chemical solution to crude oil as it is pumped from the well, preparatory to cleaning said crude oil of impurities. In such applications, the amount of such chemical solution to be added is very low, amounting often only to 6-8 ounces in 24 hours of continuous operation, or even less.Y The operating mechanisms used for injectors in such applications have heretofore commonly included reciprocating or oscillating cams driven by a rotating cam actuator driven by some intermittent mechanism such as a ratchet. Diiculties have arisen with this type of mechanism due to the fact that the cam actuator movement is transmitted to the injector substantially as simple harmonic motion, with the result that the operation of the injector is started at a very low speed on each oscillation of the cam. With very low pumping rates, such a slow start of operation often will fail to unseat the check valves forming a part of the injector, due to the fact that all the uid actually moved at the start of the stroke may be lost through minute leaks in' the tubing connections, packing joints and the like of the injector system, with the result that the injector remains elfectively inoperative. Such minute leaks are virtually impossible to eliminate completely, and once a leakage path is thus established, it requires an increasingly greater rate of displacement to actuate the injector.

A11V important object of the present invention is, there' fore, the provision in an injector operating mechanism of the class described of a specially formed cam so related to its actuator that each stroke of the injector is initiated at the maximum rate of speed. Such a sudden start will cause immediate unseating of the injector valves and thus start operation of the injector, since the leakage may easily be kept sufficiently small as to be inadequate to pass the uid displaced by such a sudden commencement of operation. Once the injector valves are positioned properly, continued lluid delivery thereby may be maintained at lower pumping rates.

Another object is the provision of an operating mechanism of the class described wherein the cam is so disposed as to cause a faster operation of the injector during the uid delivery cycle of the injector than during the Huid intake cycle thereof. Since the uid must ordinarily be delivered against a much higher pressure than the intake pressure, faster operation during the delivery cycle assists in offsetting any system leakage as described above.

A still further object is the provision, in an operating mechanism of the character described, of a cam which has a substantial period of lost motion with respect to its actuator, whereby said cam may be oscillated manually and rapidly to prime the injector by lling all parts form the primingwfunction.

Other objects are simplicity and economy of construction, eiciency and dependability of operation, and adaptability for use in a wide variety of applications.

With these objects in view, as well as other objects which will appear in the course of the specification, reference will be had to the drawing, wherein:

Fig. 1 is a vertical sectional view through an injector and operating mechanism therefor embodying the present invention, taken approximately on line I-I of Fig. 2, with parts left in elevation, showing the parts at the completion of the fluid intake stroke in solid lines and at the completion of the fluid delivery stroke in dotted lines, and

Fig. 2 is a sectional view taken on line II--II of Fig. 1.

Like reference numerals apply to similar parts throughout both of the views, and the numeral 2 applies generally to an injector pump comprising a body member 4 having a straight-through passage 6 formed therethrough, one end of said passage being connected by a conduit 8 to a tank or other source, not shown, of the liquid to be pumped by the injector, and the other end of said passage being connected by a conduit 10 to the apparatus, not shown, to which the pumped liquid is to be delivered. Carried within the pump body are a pair of check valve balls 12 and 14 which cooperate respectively with valve seats 16 and 18 formed in said body to permit iluid ow through passage 6 in one direction only, as indicated by arrows 20.

A passageway 22 formed in body member 4 intersects passage 6 intermediate valves 12 and 14, and a piston or plunger rod 24 is disposed for longitudinal reciprocal movement in said passageway, leakage around said piston being prevented by a packing 26. It will be apparent the drawing, pressure in passage 6 will be reduced. This seats valve 14 iirmly, but unseats valve 12 and draws iluid into passage 6. When piston 24 is moved to the left, valve 12 will be seated, while valve 14 will be unseated and fluid delivered through conduit 10. The injector thus constitutes an ordinary positive displacement pump. The specific structure thereof is not pertinent to the present invention, and the drawing is somewhat schematic with respect thereto.

The operating mechanism forming the subject matter of the present invention is carried in a housing 28 which` is formed integrally or directly connected to injector body 4 and which serves as a frame for carrying the operating parts thereof. As shown, said housing comprises a hollow rectilinear box having a removable cover 39, and pump piston 24 'extends horizontally into the interior thereof. Carried in the housing is a lever 32, said lever having a tubular hub 34 pivoted on an axle 36 disposed in the lower portion of the housing. Said axle is journalled in a pair of bearing blocks 3 8 aixed respectively to opposite side walls of the housing by screws 40, and is disposed transversely to and downwardly offset from piston 24. Adjacent the upper end of the lever, a link 42 is pivoted thereto at 44, the opposite end of said link being pivoted at 46 to the inner end of piston 24, whereby oscillation of said lever will cause a corresponding reciprocation of the piston. Since the lever obviously need not be attached directly to the piston, and said conneetion could be through any suitable intervening means such as might be indicated by convenience or accessibility requirements, the piston 24 may be termed simply an operating member for the injector pump.

Carried in housing 28 is a shaft 48 which is parallel to axle 38 and disposed adjacent the free end of lever 32, said axle being journalled at one end in a bearing block 50 attached to a side wall of the housing, and extending through a stutng box 52 provided in the opposite wall of the housing to a point external to the housing.I Alever\54 isfafxed to the external end of the`4 shaft. Mounted on the shaftwithin the housing is a toothed ratchet wheel 56, said wheel having a tubular hub-58which rotatesfreely on the shaft. Fixedrigidly on shaft 481 adjacent the ratchet wheel, and extending radially, is an arm 60;V Pivoted A to the outer end of said arm; on-a pivot pin 62 parallel to shaft 48,is a pawl 64. As best shown in Fig.A l, said vpawly is provided with a tooth 66 which engages the-toothed periphery ofA wheel 56,` and" with any enlarged counterweight' 68v which urges said'toothinto engagement with theV wheel. Thus when lever` 54 is-V oscillated by any suitable means, shaft 48 and armv 60 will be 'correspondingly' oscillated. During clockwise movementV of said arm, as` viewed in Fig. l, pawl-tooth-66 will Vturn ratchet wheel 56 in the direction indicated by-arrow 70; During'counterclockwise movement of arm 60, the tooth moves*inoperatively over the ratchet'teeth: In order'toA prevent wheel 56 from turning in a reverseV direction while-pawl tooth 66 is inoperative, a holding dog 72 is pivoted at 74 to a lug 76 formed integrally withJ the housing, said dog having a tooth 78 which'engages theratchet teeth by gravity.

Axed in wheel 56, eccentrically' to the axis thereof, is an axle 80 on which is mounted a ball-bearing roller 82; said roller lying substantially in the plane of movement of lever 32. Said roller servesv as an actuatingmemberfo'r a cam 84 which comprises a substantially hookshapediextension of'r lever 32 lying in the plane of movement of the lever. Said cam extension substantially embraces shaft 48 and is operably engaged by roller 82. It will bei seen'thatV the cam presents a pair of confronting lobes 86 and 88 (Fig. l), lobe 86 being. disposed at the upper end of lever 32 proper and positioned to pass beneath shaft 48, and lobe 88 being disposed at the extreme end ofthe hook-shaped extension 84 and positioned to passabove shaft-48 as the lever is oscillated.

The operation of. vthe device is` believed to be readily apparent;` Lever' 54v may be oscillated by any suitable means; In the case of the oil well vapplication previously discussed, lever 54 may be linked directly to the oscillating beam of the main well pump so as to be operated thereby. As it oscillates, it functions through-arm 60 and pawl tooth 66 .to turn ratchet wheel 56 intermittently in a clockwise direction, as previously described. As said wheel turns from the solid line position in Fig. l, roller 82, will engage vcam lobe 86 and pivot lever 32 to the position shown in dotted lines, thereby moving piston 24 through vits tluid delivery stroke. As rotation of the ratchet wheel continues, the roller will engage cam lobe 88 and pivot the lever back to the solid line position, moving piston 24 through its uid intake stroke. The roller does not contact any portion of cam 84 except lobes 86 and 88.

It will be seen that since lobes 86 and 88 are spaced apart a distance greater than the diameter of roller 82, the roller will necessarily engage the cam lobes during only portions of the orbital movement of the roller. Generally, the operative sectors of the rotation of the roller are so disposed that the component of its movement in a direction at right angles to lever 32 is as great as possible, so that the speed of movement of the lever, and hence of the injector piston, is as rapid as possible commensurate With the speed of the ratchet wheel. As previously discussed, as rapid. piston movement as possible is, effective. in preventing failure of, the; injector valves 12 and 14 due to minute leakages, of fluid. More specifically, it will be seen that asthe roller engages each of the cam lobes, the roller is moving substantially at right angles to the lever, which provides that the pumping stroke will have the greatest possible initial speed. As previously explained,y a high starting speed isparticularly effective in causing. valves 12 ,andi 14 to open. efficiently, while thestroke may be `completed at a. relativelyv low speedv Also, it will be noted that operation of roller 82.0n cam lobe 86 moves piston 24 in its fluid delivery stroke, and that said lobe is closer to the pivot 36 of lever 32 than lobe 88, which operates to cause the fluid intake stroke. Thus the fluid delivery stroke is accomplished at a much greater speed than the intake stroke. Since the fluid delivery is ordinarily accomplished at a much higher pressure than the intake, this feature provides further insurance that the injector will function eiiiciently and will not fail at very low capacitiesu due to iluid leakage.

lt will be seen alsothat-with roller 82- advanced slightly from the solid lineposition of Fig.. 1, lever 32 can be oscillated freely by hand Without interference from the roller, simply by grasping the cam extension 84. Thus the injector can be operated very rapidly to prime it at the beginning of a period of operation. rlhis is considered a valuable feature of convenience. Access for manually turning the ratchet wheel and oscillating the lever may be had by removing cover 30. The housing would Y ordinarily be partially filled with oil to lubricate the operating parts.

While I have shown and described a specific embodiment of my invention, it will be apparent that many minor changesy of structure and operation could be madewithout departing from the spirit of the invention as' defined by the scope of the appended claims'.

What l claim as new and desire to protect by Letters Patent is:

l. For use in conjunction with an injector pump operable by reciprocal movement of an operating member, movement of said member in one direction causing uid intake by said pump and movement of said member in the oppositedirection causing fluid delivery by said pump, an operating mechanism-'comprising a frame, a lever pivoted in said frame on an axis transverse to the directionl of movement'of said operating member, means interconnecting said operating member to said lever at a point spaced apart from the axis ofthe lever, whereby oscillation of said lever will cause reciprocal movement of said operating member, a cam follower carried by said lever and including a pair of confronting lobes spaced apart angularly of said lever, a cam member carried for orbital rotation by said frame on an axis parallel to the axis of said lever and disposed intermediate said` follower lobes, the angular spacing between said Vlobes being less than the diameter of the orbit of said cam memberywhereby rotation ofthe latter will cause oscillation of said lever, the spacing between said follower lobes being substantially greater than the maximum dimension of said cam member in the plane of said lobes, whereby said cam member will have periods of lost motion with respect to said follower during each rotation of said cam member and whereby said lever may be oscillated manually to prime the pump at certain angular positions of said cam member, and means operable to rotate said cam member.

2. An injector operating mechanism as recited in claim l wherein said lobes are so positioned that they are engaged respectively by said cam member as said cam member is moving approximately at right angles to said lever, whereby the strokes of said follower member are initiated at the greatest possible velocity.

3. An injector operating mechanism as recited inclaim. l wherein said lobes are disposed at respectively greater and smaller distances from the lever axis, action of said cam member on the lobe closer. to said lever axis being operable to move said operating member in its flu-id delivery stroke, and wherein said lobes are so positioned.

as to be engaged respectively by said cam member as thelatter is moving approximately at right angles, to saidy lever.

(References on following page) y References Cited in the le of this patent UNITED STATES PATENTS y124,036 Cochran Feb. 27, 1872 318,259 Kay May 19, 1885 5 324,784 Pinkham Aug. 1s, 1885 6 Klausmeyer Jan. 15, 1924 Smith June 8, 1926 Belcher Mar. 4, 1930 Mouet May 12, 1936 Zaveruka Apr. 25, 1939

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