Quickly-releasable clutch
RELATED APPLICATIONS 
     The present application is related to my copending Application Ser. No. 07/134,384, now U.S. Pat. No. 4,804,022, filed the same day as this application and assigned to the same assignee. 
     BRIEF SUMMARY OF THE INVENTION 
     The invention relates to a quickly-releasable clutch. The invention is particularly useful in liquid dispensing apparatus for dispensing predetermined doses of a liquid into individual tubes used for artificial insemination of poultry, and is therefore described below with respect to this application. 
     In the artificial insemination of poultry, which is now a widely used technique, predetermined doses of semen are dispensed into small plastic tubes, which tubes are used for the artificial insemination. Apparatus is known for dispensing predetermined does of the semen into the individual tubes, as described for example in U.S. Pats. Nos. 3,593,761, 3,683,977 and 3,880,210. However, such known apparatus is generally of very complicated construction which is bulky and expensive to produce and to maintain. 
     BRIEF SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a new and improved quickly-releasable clutch. Another object of the invention is to provide such a clutch in an apparatus for dispensing predetermined doses of liquid into individual tubes, particularly useful for filling tubes for the artificial insemination of poultry. 
     According to the present invention, there is provided a quickly-releasable clutch, comprising a feed screw formed with a spiral thread on its outer surface; an inner sleeve to be coupled to the feed screw and formed with a hole; a ball received in the hole of the inner sleeve for coupling it to the feed screw; and operative means movable to a first position for forcing the ball into the spiral thread of the feed screw to couple it to the inner sleeve, and to a second position to permit the ball to disengage from the spiral thread of the feed screw and thereby to decouple it from the inner sleeve. The operator means comprises an outer sleeve overlying the inner sleeve and axially movable with respect thereto. The outer sleeve is formed with a first inner annular surface dimensioned to force the ball into the spiral thread of the feed screw in the first position of the operator means to couple the feed screw to the inner sleeve, and with a second inner annular surface dimensioned to permit the ball to disengage from the spiral thread and thereby to decouple it from the inner sleeve in a second position of the operator means. The clutch further includes a spring normally urging the outer sleeve to the first position wherein its first inner annular surface engages the ball and thereby couples the inner sleeve to the feed screw. The feed screw includes a limit engageable by the outer sleeve for moving the outer sleeve to its decoupling position at a predetermined limit of travel of the feed screw. The outer sleeve includes an outer annular surface exposed for manual gripping by the user to permit manual decoupling of the clutch. 
     It will thus be seen that the outer sleeve performs two important functions: first, it acts to automatically release the inner sleeve from the feed screw at the limit of travel of the feed screw; and second, it permits the user to manually release the inner sleeve from the feed screw in a convenient manner for manually repositioning the inner sleeve at any desired location with respct to the feed screw. 
     The invention is particularly useful with the liquid dispensing apparatus described in my above-cited copending application, and is therefore described below is this type of apparatus. 
     Further features and advantages of the invention will be apparent from the description below. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention is herein described, by way of example only, with reference to the accompanying drawings, wherein: 
     FIG. 1 is a top plan view illustrating one form of apparatus constructed in accordance with the present invention; 
     FIG. 2 is a fragmentary view illustrating the actuated position of the manipulator included in the apparatus of FIG. 1 
     FIG. 3 is a side elevational view showing the tube feeder in its normal or return position; 
     FIG. 4 is a view similar to that of FIG. 3 but showing the tube feeder in its actuated position; 
     FIG. 5 is a side elevational view illustrating the structure for presetting the quantity of liquid dispensed with each actuation of the dispensing device; and 
     FIG. 6 is a sectional view illustrating the structure of the quickly-releasable clutch used in the apparatus of FIG. 1; and 
     FIG. 7 is a diagram of the pneumatic control system used in the apparatus of FIGS. 1-6. 
    
    
     DESCRIPTION OF A PREFERRED EMBODIMENT 
     Broadly speaking, the apparatus illustrated in FIG. 1, includes a tube feed, generally designated 2, for feeding a plurality of tubes T indiviudally to a dispensing station; a dispensing device, generally desingated 4, at the dispensing station for dispensing a predetermined dose of the lquid with each actuation of the dispensing device; and a manipulator, generally designated 6, at the dispensing station and movable from a home position (FIG. 1) for receiving a tube T, to an actuated position (FIG. 2) bringing the tube into dispensing position with respect to the dispensing device 4. The illustrated apparatus further includes a pneumatic control system, illustrated in FIG. 7, controlling the tube feeder 2, dispensing device 4, and manipulator 6 such that when the tube feeder 2 is in its actuated position and a tube T is present in the manipulator 6, the manipulator is actuated from its home position (FIG. 1) to its actuated position (FIG. 2) to bring the fed tube into dispensing position with respect to the dispensing device 4, and then to actuate the dispensing device 4 to dispense a predetermined quantity of the liquid (e.g., semen, in this example) into the end of the tube T held by the manipulator. The latter tube is then mannually removed from the manipulator, whereupon a new tube is fed by the tube feeds 2, to the manipulator 6 for receiving another dose of the liquid from the dispensing device 4. 
     More particularly, the tube feeder 2 comprises a container 10 for containing a supply of the tubes T to be fed to the manipulator 6 at the dispensing station and to receive a dose of the liquid from the dispensing device 4. As shown particularly in FIGS. 3 and 4, the bottom of container 10 is closed by a wall 11 which is inclined so as to be at a lower elevation at its front than at its rear, and if formed with an elongated dispensing opening 11&#39; at its front end. A slide plate 12 underlies botton wall 11, and its front end is formed with a recess 14 for receiving a tube T. Plate 12 is slidable by an actuator A 1  from a normal position (FIG. 3) to an actuated position (FIG. 4) to convey the tube T in its recess 14 out of container 10 to the manipulator device 6 at the dispensing station in alignment with the dispensing device 4. 
     As shown in FIGS. 1 and 2, the front end of the slidable bottom plate 12 is formed with a rectangular slot 16 in alignment with manipulator 6. The manipulator comprises a lower arm 18 and an upper arm 20 pivotable over the lower arm along a horizontal axis 20&#39; (FIGS. 3, 4). Both arms 18 and 20 are pivotable together about a vertical axis 24 from a normal position (FIG. 1) to an actuated position (FIG. 2) by a piston-cylinder actuator A 2 . Slot 16 is sufficiently wide to accomodate this pivotal movement of the two arms. 
     The apparatus further includes three sensors, namely: sensor S 1  (FIGS. 3, 4) which is actuated by the tube-feeder actuator A 1  to sense the actuated position of the tube feeder; S 2  actuated by the tube feeder to sense the home or return position of the feeder; and sensor S 3  actuated by arm 20 of the manipulator 6 to sense when a tube is present and is clamped between the two arms 18, 20 of the manipulator. Sensor S 1  is actuated by the end of stem 22 of actuator A 1  ; sensor S 2  is actuated by an arm 24 carried by stem 22; and sensor S 3  is actuated by a threaded pin 25 carried by arm 20. These sensors are all of the pneumatic type and are used for controlling the actuators A 1 , A 2 , as well as a third actuator A 3  which actuates the dispensing device 4 as will be described more particularly below particularly with reference to FIG. 7. 
     The dispensing device 4 is of the syringe type. It includes a container 26 adapted to contain a supply of the liquid to be dispensed, a plunger 28 which is actuated to dispense a predetermined dose of the liquid with each actuation of the dispensing device, and a discharge nozzle 30 through which the liquid is dispensed. As shown in FIG. 1, when a tube T is initially fed to the manipulator 6, the manipulator is in its normal position wherein the tube is spaced from discharge nozzle 30; and when the manipulator 6 is pivoted by its actuator A 2  to the position illustrated in FIG. 2, the tube T clamped between the two arms 18, 20 of the manipulator is moved to bring the end of the tube into dispensing position contact with respect to the discharge nozzle 30. 
     Plunger 28 is actuated by a drive element 32 carried at the end of a feed screw 34 formed with an external spiral thread 36. Feed screw 34 is coupled to a ratchet wheel 38, via a clutch generally designated 40 in FIG. 6, such that when the clutch is engaged, the feed screw is moved linearly an increment of movement with each increment of rotation of the ratchet wheel. The ratchet wheel 38 is in turn rotated an increment of movement by a pawl 42 pivotably mounted by pin 44 to an arm 46 actuated by the pneumatic piston-cylinder actuator A 3 . 
     As shown particularly in FIG. 5, arm 46 is formed with a plurality of openings 48 spaced at different distances along its length from its pivotable axis. These openings are adaptable to selectively receive a coupling element in the form of a pin 50 carried by the outer end of the piston stem 52 of actuator A 3  for presetting the increment of movement of arm 46, and thereby of ratchet wheel 38 and feed screw 34, with each actuation of actuator A 3 . 
     The structure of clutch 40 coupling ratchet wheel 38 to feed screw 34 is clearly seen in FIG. 6. It includes a first, inner sleeve 54 enclosing feed screw 34 and of larger internal diameter than the outer diameter of the feed screw so as to provide an annular clearance therebetween. Sleeve 54 is secured to ratchet wheel 38 so as to be rotated therewith. Sleeve 54 includes an extension in the form of a collar 56 to which it is secured by means of external threads formed at one end 56&#39; of the sleeve extension receivable within internal threads formed in sleeve 54. 
     Sleeve extension 56 is also formed with an internal diameter larger than the external diameter of feed screw 34 so as to provide an annular clearance between the sleeve extension and the outer surface of the feed screw. Sleeve extension 56, however, is formed with a hole receiving a ball 58 of a diameter to be seatable within the groove of the spiral thread 36 formed on the outer surface of feed screw 34. 
     Clutch 40 further includes a second, outer sleeve 60 overlying extension 56 of sleeve 54 and axially movable with respect to it. Sleeve 60 is formed with a first inner annular surface 60a dimensioned to engage the ball 58 and to force it into the groove of the spiral thread 36 formed on the outer face of feed screw 34 so as to couple the feed screw to ratchet wheel 38 via sleeve 54 and its extensin 56. Sleeve 60 is formed with a second inner annular surface 60b, having a larger internal diameter than its annular surface 60a, so as to permit the ball 58 to disengage from the groove of the spiral thread 36 and thereby to decouple feed screw 34 from collar 56, of sleeve 54, and ratchet wheel 38. 
     Sleeve 60 is normally urged to its coupling position illustrated in FIG. 6, i.e., with its annular surface 60a engaging ball 58, by means of a spring 62 interposed between sleeve 60 and ratchet wheel 38 carried by sleeve 54. Sleeve 60, however, is movable axially against the force of spring 62, i.e., rightwardly in FIG. 6, to bring its annular surface 60b over ball 58, to permit the ball to unseat from the spiral groove 36 of feed screw 34, and thereby to decouple the feed screw from sleeve 54 and ratchet wheel 38. 
     Feed screw 34 carries a collar 64 at one end which engages sleeve 60 at a predetermined limit of travel of the feed screw to decouple the feed screw from ratchet 38. Collar 64 is presettable at the end of feed screw 34 by threads 66 to enable presetting this limit of travel of the feed screw. 
     Sleeve 60 may also be moved manually against the force of spring 62 in order to decouple the feed screw 34 from sleeve 54 and ratchet wheel 38; for this purpose, the sleeve may be formed with an outer knurled surface as shown in FIG. 1. Thus, whenever it is desired to return feed screw 34 to its initial position, or to preset it to any desired position, it is only necessary to grasp sleeve 60 and to move it rightwardly against the force of spring 62, to bring the inner annular surface 60b of the sleeve into alignment with ball 58; this permits ball 58 to unseat from the spiral thread 36 formed in the outer face of feed screw 34, and allows the feed screw to be manually moved to any desired position. 
     FIG. 7 illustrates the pneumatic circuit for operating the three actuators, namely: actuator A 1  of the tube feed 2, actuator A 2  for the manipulator 6, and the actuator A 3  for the dispensing device 4. This pneumatic circuit also includes the three sensors mentioned earlier, namely: sensor S 1  which senses the actuated position of the tube feed slide plate 12, sensor S 2  which senses the normal or return position of the slide plate, and sensor S 3  which senses the presence of a tube T between the arms 18, 20 of the manipulator 6. These sensors control control actuators A 1 , A 2 , A 3  via two pneumatic controllers C 1 , C 2 . 
     The illustrated apparatus operates as follows: 
     Container 10 is first filled with a supply of tubes T to receive the liquid to be dispensed, and compartment 26 of the dispensing device 4 is filled with the liquid to be dispensed. Piston stem 52 of the dispensing device actuator A 3  (FIG. 5) is coupled to the appropriate opening 48 in arm 46 according to the predetermined quantity of liquid to be dispensed with each actuation of the dispensing device. Driving element 32 may be manually positioned to engage the end of plunger 28 of the dispensing device by manually gripping sleeve 60 of clutch 40, and moving it rightwardly (FIG. 6) against spring 62, whereupon the inner annular surface 60b of sleeve 60 is brought to overlie ball 58. This decouples feed screw 34 from ratchet wheel 38 by permitting ball 58 to unseat from the spiral thread 36 of the feed screw 34, whereby the feed screw may be manually positioned as desired. 
     Actuator A 1  is actuated from its normal position (FIG. 3) to its actuated position (FIG. 4), thereby feeding a tube T between the two arms 18, 20 of the manipulator 6 in the dispensing station. Sensor S 1 , actuated by piston stem 22 (FIG. 4) of actuator A 1 , senses this actuated position of the tube feeder; and sensor S 3  actuated by arm 20 of manipulator 6 senses the presence of a tube clamped between the arms of the manipulator 6 in the dispensing station. 
     As shown in the pneumatic diagram of FIG. 7, sensors S 1  and S 2  control pneumatic controller C 1  so as to produce an output in pneumatic line 70 to actuators A 2  and A 3 . Actuator A 2  is first actuated to pivot the manipulator arms 18, 20 to their actuated position as illustrated in FIG. 2, bringing the end of the tube T, clamped between the arms, into dispensing position with respect to discharge nozzle 30 of the dispensing syringe 4; and then actuator A 3  is actuated to rotate ratchet wheel 38, via arm 46 and pawl 42, one increment of angular movement of sleeve 54. This angular movement of sleeve 54 is translated to an increment of linear movement of feed screw 34 by means of ball 58 seated within the spiral thread 36 of the feed screw 34. Accordingly, a predetermined quantity or dose of the liquid will be discharged via nozzle 30 into the tube T held by manipulator arms 18, 20. 
     The so-filled tube T is then manually removed from between the two arms 18, 20 of the manipulator 6 and is used for inseminating the chicken. As soon as the tube T has been removed from the between the manipulator arms 18, 20, this is sensed by sensor S 3 , which controls actuator A 1  to return the tube feeder 2. The return of the tube feeder is sensed by sensor S 2 , and when this has occurred, the two sensors S 2 , S 3  control pneumatic controller C 2  to actuate actuator A 1  of the tube feeder in order to feed the next tube to the dispensing station between the manipulator arms 18, 20. 
     While the invention has been described with respect to one preferred embodiment, it will be appreciated that many variations may be made. For example, the clutch mechanism 40 could include a plurality of balls 58, rather than a single ball, and could be used in many other applications. 
     Many other variations, modifications and applications of the invention will be apparent.