US2969684A - Liquid injector - Google Patents

Description

Jan. 31, 1961 o. E. WATSONl LIQUID INJECTOR Filed Dec. 1l, 1958 INVENTOR. Or/a M/Ja/ LIQUID INJECTOR Orla E. Watson, 2911 W. 67th St., Mission Hills, Kans. Filed Dec. 11, 1958, Ser. No. 779,584

6 Claims. (Cl. 74-49) rl`his invention relates to new and useful improvements in liquid injectors, and has particular reference to liquid injectors of the piston type.

Liquid injectors of the continuously driven piston type have heretofore been subject to substantial objectionability when used to inject liquids at a very low rate. In many applications it may be desired, for example, to inject liquids at the rate of say a fraction of a pint per hour or even less. In prior injectors within my knowledge, the delivery rate has been reduced by causing the piston to move at slower and slower rates of linear speed. The unavoidable leakage around a piston, while small, will be great enough to cause a serious and objectionable variation of the delivery rate, particularly when injecting against a substantial pressure. In some circumstances, as a matter of fact, the piston leakage may cause a complete failure of the pumping action of the piston, with the result that the injector becomes inoperative. ln other words, in any given piston arrangement, the rate of movement of the piston must he maintained above a certain minimum figure if the ratio of the unavoidable leakage to piston displacement is to be kept sufficiently small to be acceptable. Also, there is a definite practical limit in the smallness of size to which the piston may be reduced to decrease the delivery rate, since the proportion of the leakage to piston displacement increases disproportionately in very small pistons, and is also increased disproportionately due to any wear of the piston or cylinder.

The principal object of the present invention is, therefore, the provision of a piston-type uid injector which is continuously driven, and wherein the piston diameter and rate of travel are sufficiently large to hold piston leakage to an insignificant proportion of the total volume delivered, and wherein at the same time the overall delivery rate may be reduced to extremely low values by the introduction of an intermittent connection in the power drive to the piston, so that the piston actually completes only one stroke for a predetermined greater number of operations of its driving means.

Another object is the provision of a liquid injector of the character described wherein the number of operations of the piston driving means required to operate the injecting piston one time may be adjusted over a wide range. Y A further object is the provision of a liquid injector of the character described wherein the delivery rate may be still further adjusted by varying the length as well as the frequency of the piston stroke.

Other objects are simplicity and economy of construction, efficiency 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 drawings, wherein:

Fig. 1 is a vertical sectional view, with portions broken away, of a liquid injector embodying the present invention, showing the piston operating plunger in its operaice 2 tive position in solid lines and in its inoperative position in dotted lines,

Fig. 2 is a fragmentary sectional view taken 0n line I'I--II of Fig. 1, and

Figs. 3, 4 and 5 are sectional views taken respectively on lines III-III, IV-IV and V-V of Fig. 1.

Like reference numerals apply to similar parts throughout the several views, and the numeral 2 applies generally to a hollow housing having a front wall 4, back wall 6, bottom wall 8, end walls 10 and 12, and a removable cover 14 secured thereto by screws 16. An input shaft 18 extends through end wall 10 of said housing, being journalled in said end wall and in a bearing block 20 arising from bottom wall 8. The outwardly extended end of said shaft is adapted to be interconnected with and driven by an electric' motor or other suitable power source, not

shown.. Fixed on said shaft within the housing isa worml 22 which is meshed with a worm gear 24 fixed on a shaft 26 which is disposed above and at right angles to shaft 18, and which is journalled in front and back walls 4 .and 6 of the housing.

Also aiiixed to shaft 26 by means of key 28, is a cylindrical cam 30, the axis of which is parallel to but offset eccentrically from shaft 26. Mounted on cam 30 for rotation relative thereto is a rectilinear block 32 having a cylindrical opening formed therein for receiving the cam. A rectilinear box 34 surrounds block 32, said box being open at its top and bottom so that the block can slide vertically therein, and having a pair of matching horizontal slots 36 formed in the side walls thereof, shaft 26 extending outwardly through said slots. Atlixed to box 34, vand extending in a direction at right angles to shaft 26, is an arm 38 which is longitudinally adjustable in length by virtue o-f being formed in two sections 40 and 42, section 40 being welded or otherwise fixed to box 34, and being affixed adjustably to section 42 by set screws 44 threaded therein and extending through a longitudinally elongated 'slot 46 formed in section 42. At its outer end, section 42 carries a depending fork 48, the purpose'of which will be fully described below. Arm section 42 is prevented from pivoting vertically by a pair of pins 50 fixed in back wall 6 of the housing and extending respectively above and below arm section 42, as best shown in Figs. 1 and 5. Thus vas input shaft 18 is turned, it functions through worm 22, worm gear 24, shaft 26, cam 30, cam follower block 32 and box 34 to oscillate or reciprocate arm 38 longitudinally. The frequency and extent of this reciprocation are uniform so long as shaft 18 is turned at a uniform speed.

An injector pump housing 52 is shown as integral with end wall 12 of housing 2. It includes a central cylindrical chamber 54 in which a piston 56 is closely fitted for reciprocatory movement, said piston extending into housing 2 and being parallel to the direction of movement of arm 38. Housing 52 includes an intake port 58 interconnected with chamber 54 and in which reverse liow is prevented by the engagement of a ball valve 60 with a seat 62V, and anoutlet port 64 interconnected with chamber 54 and in which reverse flow is prevented by the engagement of a valve ball 66 with a seat 68. The operation of this type of pump is well known. When the piston is retracted to the left, ball 66 is seated firmly and ball 60 is unseated, and liquid from inlet port 58 is sucked into chamber 5'4. When the piston is advanced to the right, ball `66 is'seated and ball 66 is forced off its seat, and liquid is forced to outlet port 64. Adjacent the end of Y piston 56 within housing 2, a pin 70 is inserted fixedly through said piston, and has its end portions turned downwardly to be disposed closely adjacent a horizontal plate 72 which is secured to wall 6 by screws 74. This plate prevents the piston from turning about its axis. Fork 48 of arm 38 straddles the piston forwardly of pin 70. Thus when said arm is moved to the left by eccentric cam 30 as previously described, said fork will engage pin 70 and retract the piston. v

The piston is advanced to the right by means of a plumger 76 pivoted at one end between a pair of ears 78 aixed to box 34, by means of a pivot pin 80 parallel to shaft 26. Said plunger is normally disposed in axial alignment with piston 56 so that as it is moved to the right by the oscillatory movement of box 34, its outer end will engage and advance the piston to the right. The plunger is normally supported in its operative position by an arm 82 affixed thereto at the outer end thereof and extending longitudinally therefrom to overlie slidably the top surface of the piston. The plunger is urged pivotally downwardly toward said operative position at all times by a coil spring 84 bearing at its lower end against the upper surface of said plunger, at its upper end against a transversely extending bracket 86 affixed to section `40 of arm 38.

A planar, substantially circular indexing wheel 88 is carried on an axle 90 journalled in the front and back walls of housing 2, said axle being horizontal and parallel to shaft 2-6. The upper edge of said wheel is disposed just below the normal level of plunger 76, and the vertical plane of said wheel is disposed at one side of the plane of the vertical pivotal movement of said plunger. The peripheral edge of said wheel has a series of notches 92 formed therein at regularly spaced angular intervals. The wheel is turned in a clockwise direction as viewed in Fig. l, by a pawl 94 which is pivoted on the pivot pin 80 which also carries plunger 76, and which extends alongside the plunger. The outer end of said pawl rests on the edge of wheel 88, and is urged thereagainst by a coil spring 96 bearing at one end against said pawl and at its opposite end against bracket 86. The parts are so proportioned that for each oscillation of plunger 76 to the right, pawl 9'4 will turn wheel 88 one notch in a clockwise direction. Reverse rotation of wheel 88 is prevented by a dog 98 pivoted at 100 in a bracket 102 fixed to the lower surface of plate 72, said dog being urged against the wheel to engage the notches thereof by means of a coil spring 104 carried by said bracket.

Adjacent each notch 92 of wheel 88, a selector pin 106 is inserted slidably in a bore provided therefor in said wheel. Said pins extend parallel to the axis of the wheel, and are adapted to be moved longitudinally. Each pin has an operative and an inoperative position. In its operative position, the pin extends rearwardly from the back face of the wheel to such an extent that it projects beneath plunger 76, as illustrated by the lower pin in Fig. 4. In its inoperative position, the rearawrd end of the pin extends substantially llush with the rearward face of the wheel, as illustrated by the upper pin in Fig. 4. Aiiixed to the forward face of wheel 88 by screws 108 are a plurality of U- shaped springs 110, the legs of each of said springs bearing transversely against a pair of pins 106 and engaging selectively in either of a pair of peripheral grooves 112 or 114 formed in each of said pins. When the pin is moved so that spring 110 engages groove 112, the pin is held releasably in its operative position. When the pin is moved so that spring 110 engages groove 114, the` pin is held in its inoperative position. The forward end portions of the pins 106 are knurled to facilitate manipulation. Welded or otherwise iixed to the lower surface of plunger 76, directly adjacent wheel 88, is a lug 116 which normally rests on a rearwardly extending hub 118 of wheel 88 when the plunger is in its operative position with respect to piston S6.

In the operation of the device, the oscillation of plunger 76 by cam 30, as previously described, will cause said plunger to engage and advance piston S6 to the right during each oscillation, so long as said plunger remains in alignment with the piston, and fork 48 of arm 38 will retract the piston during the return stroke, thus causing regular operation of the injector pump. The degree to which the piston is retracted may be varied by loosening set screws 44 and changing the length of arm 38. Thus the length of the piston stroke may be changed at will, although the stroke of plunger 76 of course remains unchanged.

Plunger 76 will remain in its operative position relative to the piston only so long as the topmost selector pin 106 of index wheel 88 is in its inoperative position. However, if any one of said pins has been advanced to its operative position, said operative pin will eventually be moved to the top of the wheel, since the wheel is turned one station for each advance stroke of the plunger. As the plunger is retracted after the stroke which has brought the operative pin 106 to the top of the wheel, said pin engages lug 116 of the plunger and elevates the plunger to the dotted line position shown in Fig. l, against the pressure of spring 84. The plunger is then in an inoperative position relative to the piston, being out of axial alignment therewith. When the plunger is next advanced, it will be maintained in this inoperative position by virtue of the fact that pin 106 will be advanced simultaneously with the plunger, and the plunger end will pass above the end of the piston into overlapping relation therewith, and the piston will not be advanced. Since there are ten selector pins 106 in indexing wheel 83, and since only one of them need to be moved to its inoperative position, it will be apparent that the device may be set so that piston 56 is moved through only one stroke for every ten strokes of plunger 76. The piston may be caused to operate with greater frequency, as desired, by setting more of pins 106 in their operative positions. Obviously, a greater or smaller number of selector pins could be installed in wheel 88.if desired. It will be seen that plate 72 is provided at its edge with an upturned lip 120 which is adapted to engage pin 70 of the piston and thereby to limit the retraction or withdrawal stroke of the piston. This is to prevent the possibility that if valve ball 66 of the pump should leak, iluid being forced into chamber 54 therethrough between operations of the piston might force the piston so far rearwardly that plunger '76 could not fall into operative position therebehind when the neit inoperative pin 106 came to the top of wheel 88.

Thus it will be seen that a fluid injector has been produced wherein, while the piston speed and size are main tained suiciently great to render the unavoidable leakage around the piston inconsequential as a factor affecting the delivery rate, the overall delivery rate may still be reduced to the extremely low amounts often desired, by the introduction of an intermittent driving connection between the power source and the piston so that the frequency of the piston strokes may be varied and greatly reduced, and by the provision of means for reducing the length of the piston stroke.

While I have shown and described a specific embodiment of my invention, it will be readily apparent that many minor changes of structure and operation could be made without departing from the spirit of the invention as defined by the scope of the appended claims.

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

l. A device for dividing a reciprocable element comprising a reciprocable plunger so positioned that when driven in one direction it will engage and advance said element, a retracting member connected to and reciprocable with said plunger and so positioned that as said plunger is driven in the opposite direction said retracting member will engage and retract said element, means operable to drive said plunger continuously, said plunger being movable transversely to its direction of reciprocation to an inoperative position wherein reciprocation thereof will not advance said element, and means interconnected with and operable by said plunger driving means to move said plunger intermittently to its inoperative position.

2. The structure as recited in claim 1 wherein said retracting member is adjustably movable relative to said plunger in the direction of reciprocation thereof, whereby lost motion between said plunger and element may be introduced and the length of stroke of said element may be adjusted.

3. The structure as recited in claim l wherein said means operable to move said plunger to its inoperative position comprises an indexing wheel carried rotatably adjacent said plunger, a series of selector members carried in angularly spaced relation by said wheel and operable successively as said wheel is rotated to engage and move said plunger to its inoperative position, and means interconnected with and driven by said plunger driving means and operable to rotate said wheel intermittently.

4. The structure as recited in claim 3 wherein said selector members are each adjustably movable relative to said wheel to an inoperative position wherein it will not engage and move said plunger as said wheel is rotated.

5. A device for driving a reciprocable element comprising reciprocating means normally so positioned that when driven it will engage and drive said element, said reciprocating means including a plunger normally operatively aligned with said element, whereby to advance said element when moved in one direction but being movable transversely to its direction of reciprocation to an inoperative position out of alignment with said element, and deecting means operable to move said plunger intermittently to its inoperative position, said deecting means being interconnected with and operable by said reciprocating means, and constituting an indexing wheel carried rotatably adjacent said plunger, a series of selector members carried in angularly spaced relation by said wheel and operable successively as said wheel is rotated to engage and move said plunger to its inoperative position, each of said selector members being adjustably movable relative to said wheel to an inoperative position wherein it will not engage and move said plunger as said wheel is rotated, and means operable by said reciprocating means to turn said Wheel intermittently.

6. The structure as recited in claim 5 wherein said wheel turning means comprises a pawl connected to said reciprocating means and operable during each reciprocation thereof to turn said wheel sufficiently to bring the next successive selector member of said series into operative engagement with said plunger, provided said selector member is in its operative position relative to said wheel.

References Cited in the le of this patent UNITED STATES PATENTS 300,177 Whitney June 10, 1884 464,064 Downing Dec. 1, 1891 1,892,631 Quigg Dec. 27, 1932 2,334,943 Miller et al Nov. 23, 1943 2,389,475 Watson Nov. 20, 1945 2,633,801 Clements Apr. 7, 1953 2,797,584 Balsam July 2, 1957

Images