GB1495662A - Apparatus for drawing measuring and discharging proportional amounts of fluid - Google Patents

Abstract

1495662 Automatic diluting device COULTER ELECTRONICS Inc 9 Jan 1975 [10 Jan 1974] 1022/75 Heading G1B [Also in Division B8] An automatic diluting device for drawing and diluting a first sample with a diluent wherein the sample and diluent are mixed in a precise ratio, comprises a diluent chamber 70 having a first reciprocable plunger 84 therein, a sample chamber 66 or 68 having a second reciprocable plunger 88 or 90 therein, coupling means which includes plate 86 for moving the first and second plungers equal distances in the chambers, and the volumes displaced on movement of the plungers for any equal distance being in fixed precise ratio to one another, drive means including a motor (38) Fig. 4 (not shown), having a rotary drive-shaft, cam means 40 secured to the shaft and having eccentric 50 which is coupled to plate 86 for reciprocating the plungers, the coupling means including eccentric follower means 96 which provides movement of plate 86 during first portions of each rotation of cam 40 and not during second portions, valve assembly 123, 124 having a chamber coupled to diluent chamber 70, diluent intake passage means and diluent discharge passage means coupled to the valve assembly, valve member 123 being shiftable between a first position wherein the valve chamber couples the diluent intake to diluent chamber (70) Figs. 7, 8 (not shown), and a second position wherein the valve chamber couples diluent discharge 118, 120 to diluent chamber 70, and shifting means 124 coupling member 123 to the eccentric for shifting the valve between first and second positions during the second portions of rotation of cam 40 i.e. when the plungers 90, 84, 88 are stationary. In the embodiment shown, there are two sample chambers 66, 68 providing different sample diluent volume ratios, the connection between the sample probe 22 and the selected sample chamber being provided on operation of knob 34 which rotates gears 132, 134 and rod 136 to alter liquid flow connections in switching valve assembly 140. Coupling means 86 &c. which reciprocates plungers 88, 84, 90 is linked to reciprocable member 123 of a spool valve, the spool valve having a first position in which diluent entry port 114 and exit port 122 are in alignment, so that on retraction of the plungers sample is drawn from a beaker into pipette 22, through switching valve assembly 140 and into a selected sample chamber 66 or 68 while diluent is drawn into chamber 70 from supply connection 200 through switching valve 140 and ports 122, 114, and a second position in which the sample is dispersed through pipette 22 and there are in communication in the spool valve entry and exit ports 116, 118 and entry and exit ports 114, 120 as shown, dispensed diluent then passing in part directly to diluent dispense probe 24 and in part through ports 118, 116 through valve 140 into the sample chamber being used by its side port 72 or 76, out of the sample chamber through its port 74 or 78, through valve 140 again and out by probe 22.