Patent GB-655896-A (GB)
Title: Improvements in fraction collection apparatus
IPC: G01N1/18
Filed: 1948-07-01
Abstract: <PICT:0655896/III/1> <PICT:0655896/III/2> Apparatus for collecting measured quantities of material in individual receptacles, e.g. a fraction-collector for chromatographic analysis (Fig. 1), comprises a movable support 10 for supporting receptacles in a row or rows extending in the direction of movement of the support, means 30 for mounting a material supply device 22 in position at the receptacle-charging station; means for moving said support step-by-step to carry said receptacles in succession to said station and beneath said device to receive a charge of material from said supply device; means for actuating said moving means; timing means for controlling the operation of the said actuating means whereby to pre-determine the duration of rest intervals of said support between successive step moves thereof; and indexing means associated with the means for moving the support and with the actuating means to pre-determine the number of step-by-step movements of the support corresponding to the number of the receptacles so that each receptacle receives a pre-determined quantity of material in turn. General (Fig. 1).-The liquid from supply 34 passes through valve 36 and through chromatographic tube 38, and drop by drop passes into tubes T held on a rack or circular rotary conveyer 10 which moves step-by-step so that each tube receives a pre-determined number of drops, the apparatus finally automatically stopping.  Rack 10 (Fig. 3).-Rack 10 supports (say) four circular rows of fifty tubes T, and is mounted in hub 64 rotatably mounted on shaft 60 and shaft extension 72 and hub 64 having lugs 102 by which the rack is rotated step-by-step by gear 100.  The cover 24 is transparent.  Post 30 (Fig. 1).-A hollow post 30 fixedly supports the liquid supply 34 and is journalled <PICT:0655896/III/3> <PICT:0655896/III/4> <PICT:0655896/III/5> <PICT:0655896/III/6> <PICT:0655896/III/7> <PICT:0655896/III/8> <PICT:0655896/III/9> <PICT:0655896/III/10> <PICT:0655896/III/11> at its ends 92 and 9 in the triangular frame, a stationary vertical frame member 89 passing throughout its length. Its position is indicated by an arrow 238 moving over scale 236, and it includes a sleeve 93 which rotates with post 30, and through which wires are fed to the timing device 22 which is also secured on the post 30.  Screw 94a allows adjustment of scale relative to sleeve 93. Drive for rack 10 (Figs. 8 and 9).-Motor M drives rack 10 through worm 150, worm-wheel 152, shaft 146, Geneva gear 124 and 122, worm 118, worm-wheel 116, shaft 110, gear 108, gear unit 98 and lugs 102 on rack 10.  The gear unit 98 is movable by knob 174 which actuates it through shaft 176, crank 180, link 184, lever 188 and fork 172. The gear unit has two integral gears 106 and 100 fixed thereto, and when moved upwards transmits the drive from gear 108 to the lugs 102 of rack 10 (whilst at the same time engaging gear 216 and so driving the other parts of the apparatus).  Indexing device and drive for post 30 (Figs. 5, 7 and 8).-The drive from motor M passes, as stated above, to gear 108, and when gear unit 98 is raised (as above) by knob 174 the drive is transmitted through gear 106, gear 216, shaft 200, gear 192, gear 194, gear 196, gear element 218, gear 228, gear 198, to sleeve 93 on which post 30 is fixed.  Gear 196 has fixed to its upper surface a disc 220, on the periphery of which is fixed gear element 218, a tooth 223 being cut out of disc 220 immediately beneath the gear element so that a "deep" tooth is formed.  Gear 228 is formed with six upper teeth 224 and three lower teeth 226 so that three "deep" teeth are formed to engage tooth 223.  By this means one complete revolution of gear 196 causes gear 198 to turn through one step and two teeth of the gear 226 are kept in engagement with disc 220 so that the post 30 is always held fixed between its movements. Its position can be adjusted by means of knob 206 which acts through bevel gears 212 and 214 so as to determine the number of tubes to be filled in the first row of tubes.  Positioning of post 30 (Figs. 12 and 13).-Gear 198 (driven as above) is integral with gear 246, and is brought into engagement with rotatable sleeve 93 (which carries post 30) by means of clutch 248, which is slidably splined to sleeve 93 and has teeth 250 engageable with gear 246, the clutch being operated by knob 252 which works a crank-pin 260 engaging fork 254 pivoted at 258. Teeth 250 are brought constantly into engagement with the teeth of gear 246 (to prevent lost motion) by means of spring 274 which is secured at 278 to cam 266, which is fixed to sleeve 93 and which, at the completion of the operation engages spring 270 and breaks switch 268 which stops the apparatus.  Thus the position of liquid supply 34 mounted on sleeve 93 may be adjusted at will by disengaging clutch 248, thus pre-determining the number of rows of tubes T to be filled. Liquid interception and control unit 22 (Figs. 15 and 16).-This unit 22 is adjustably fixed at 91a and 94a to post 30.  Liquid from liquid supply 34 passes drop by drop down transparent glass tube 42 whilst across its path shines a beam of light from lamp 46 on to light cell 44.  After the pre-determined number of drops has passed through the light beam as predetermined by counter 320 and set by knob 322 (not shown), the successive impulses registered by light cell 44 in the main electrical circuit cause the discharge of a coil and this causes the rack to move to its next position. An interceptor 282 is provided which is mounted at 286 on shaft 288 provided with crank 294; which crank is operated by solenoid 290 in one direction, and by spring 296 in the other direction, to pull the crank against cam surface 308, a hand adjustment 306 being provided for the latter.  When the main current fails solenoid 290 is discharged and crank 294 swings shaft 288 so that interceptor 282 is swung beneath the descending drops of liquid so that in the case of a current failure or at the end of the operation it prevents the tube T from being filled to over-flowing. Time switch (Fig. 19).-A time switch is included in the main circuit so that if the rack 10 fails to turn, the interceptor (see above) will be swung beneath the descending drops of liquid.  The time switch is driven from motor M1 which through reduction gearing 406 and clutch members 410, 412 drives screw shaft 424 which drives nut-like switch member 423.  Clutch member 410 is spring-influenced at 422, and magnetically influenced at 420 by clutch coil 418, the latter coil being in the main circuit.  When the rack has moved to its next position the motor M1 commences and switch member 423 begins to travel along screw 424.  If after a predetermined time the rack 10 has not again moved round to its next position, switch member 404 continues to move along screw 424, till finally it engages switch 400, and thus breaks the main circuit.  If the rack has moved round to its next position the motor is switched out and spring 422 returns everything to its original position.  Operation.-The requisite number of tubes T are placed in the rows on rack 10.  Knob 206 and pointer 238 are actuated to set the apparatus for the predetermined number of tubes, knob 322 is operated to determine the number of drops per tube, and main switch 356 (Fig. 1) is operated to switch the apparatus on.  The rack rotates and a pre-determined quantity of liquid is dropped into each tube in the row.  Then the post 30 swings automatically so that the liquid commences to drop into the second row, and the rack 10 continues to rotate step-by-step, and so on, until, finally, the last tube is filled and the apparatus stops of its own accord.