CH645729A5 - MULTIPLE POSITION FLUID TRANSFER MECHANISM. - Google Patents

Description

The present invention relates to a multi-position fluid transfer mechanism, having an elongated movable arm supporting a fluid probe at a distal end for withdrawing and dispensing fluids.

Such fluid transfer mechanisms, known per se, serve to rapidly and precisely withdraw an amount of fluid in one position to bring it into a second position and dispense it.

The object of the present invention is to improve such a mechanism by providing it with means capable of agitating the transferred fluid in order to ensure that this fluid, if it is constituted by a mixture, remains very homogeneous during the transfer.

This object is achieved by the means defined in claim 1.

The drawing represents, by way of example, several embodiments of the subject of the invention.

Fig. 1 is a perspective view partly of a fluid transfer mechanism and partly of a chemical analysis apparatus.

Fig. 2 is a side plan view, partially in section, of an embodiment of the transfer mechanism.

Fig. 3 is an enlarged side view, partially in section, of an embodiment of the probe of the mechanism.

Fig. 4 is a top plan view along line 4-4 of FIG. 2.

Fig. 5 is a side view of the arm of the transfer mechanism taken along line 5-5 of FIG. 2.

Fig. 6 is an exploded perspective view of the transfer arm and the probe of FIG. 2.

Fig. 7 is a side view partially in section of a second embodiment of the transfer mechanism.

Fig. 8 is a block diagram of a device for controlling the fluid transfer mechanism.

Fig. 9 is a perspective view of another embodiment of the movable arm of the present mechanism.

Fig. 10A is an exploded view, partially in perspective, of the elements of the arm shown in FIG. 9.

Fig. 10B is an exploded view, partially in perspective, showing the vertical detection device as well as the drive and guide rods of the arm shown in FIG. 9.

Fig. 10C is an exploded view, partially in perspective, of the base and of the drive motors of the arm shown in FIG. 9.

Fig. 11 is an elevation view from the rear, representing the trajectory of the wires of the arm shown in FIG. 9, and fig. 12 is a view partly in elevation of the arm shown in FIG. 11.

The fluid transfer mechanism shown in fig. 1 is generally designated by 10. Three of these transfer mechanisms 10, 10 ′ and 10 ″ are illustrated in operation with a chemical reaction analysis apparatus 12. The apparatus 12 may include a sample reserve 14 and a reagent reserve 16. The transfer mechanism 10 can be used with any type of analysis or mixing system in which it is desirable to use its possibilities. For ease of description of the operation of the mechanism 10 and the inherent flexibility thereof, a particular analysis apparatus 12 will be described here.

This apparatus 12 comprises a test tube rotor 18 which comprises a plurality of test tubes or test tube cavities 20. The sample doses are taken or aspirated by the mechanism 10 from the sample reserve 14 and moved and dispensed in the test tubes 20. The sample doses are mixed with the reagent doses which are withdrawn and dispensed by the mechanism 10 'from the reserve 16 of the first reagent. A second reagent can be added to the test pieces 20 by the third mechanism 10 "from the reserve 16 or from a different reserve, not shown. The sample reserve 14 can include samples, controls and controls which are taken from the sample reserve 14 in a predetermined order and which are then analyzed by the apparatus 12 in the test tubes 20. These will preferably be supplied in the form of a renewable reserve, being cleaned in the apparatus 12 before arriving again at the dispensing position of the sample of the mechanism 10.

The sample reserve 14 comprises a plurality of cavities 22 in which the samples, the controls and the controls can be placed and can comprise one or more sampling positions or an arc defined by a fluid probe 24. The cavities 22 can be brought into the sampling positions by the rotation of the source 14. The probe 24 is turned on an arm 26 around a rod 28. The arm 26 is shown with the probe 24 in the dispensing position, engaged in one of the test pieces 20 of the rotor 18. The fluid withdrawn from the reserve 14 will be dispensed and may be mixed by a motor 30 causing the probe 24 to oscillate back and forth in the test piece 20. The mechanism 10 'operates in a similar manner to take a sample of one or more reagent containers 32 in the reserve 16. The 10 "mechanism can take a second dose of reagent from containers 32 or from another reserve or row of containers not shown.

The probe 24 rotates around the rod 28 and is driven vertically upwards and downwards along the rod 28 to collect and dispense the doses of liquid. The types of reserves as also the row of specimens 20 are indicated simply by way of illustration and the mechanisms 10, 10 'and 10 "could withdraw and dispense fluids from any position on an arc defined by the axis of the rod 28. The fluids may each be different for each operation of the mechanism 10 and it is very important that entrainment and contamination of fluids be eliminated since the fluids are bodily fluids of particular patients.

The operational positions of the mechanism 10 during each cycle will be as follows, describing the position of the probe 24, for convenience. The probe 24 will be in a rest position as located above the probe washer 34, in which the probe is washed both inside and outside and dried at the end of each cycle, this for the preparation of the next cycle. The probe 24 is first of all turned in the appropriate sampling position above one of the cavities 22, driven downwards in the cavity, until it reaches the fluid, then it sucks up the precise quantity desired fluid, finally it is withdrawn in its rotational position above the reserve 14, turned into a dispensing position above the test pieces 20, driven down into the test piece 20, where it dispenses the quantity of aspirated fluid, caused to oscillate to mix the fluids in the bowl 20, withdrawn upwards in its rotational position, turned to a position where it is located above the probe washer 34, driven in the probe washer 34 where it is washed and dried with all of the above fluids, then returned to its rest position above the probe washer 34. In a chemical analysis apparatus 12 using the above cycle, the test pieces 20 are advanced step by step by the rotor 18 from a position d in the direction A every 6 s and, from there, each of the mechanisms 10, 10 'and 10 "performs each of the movements mentioned above in less than 6 s. It can therefore be seen that it is of the utmost importance that each of the positions, vertical and rotary, be reached precisely and quickly by the probe 24.

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A first embodiment of the transfer mechanism 10 and the probe 24 is shown in FIGS. 2 to 6. The probe 24 shown in fig. 2 is illustrated engaged in one of the test pieces 20 of the rotor 18. The probe 24 oscillates back and forth, as shown by the arrow B, to mix the fluids in the test piece 20. The probe 24 is driven upwards and towards the bottom, along the axis of the rod 28, as shown by the arrow C, which engages it in the cavities 22 of the test pieces 20 and of the probe washer 34 and withdraws therefrom. The mechanism 10 can be mounted on any suitable surface such as a base plate 36 of the device 12.

The arm 26 is mounted on the rod 28 and is driven horizontally by a motor 38 and vertically by a motor 40. These motors 38 and 40 will preferably be stepper motors to produce very precise movement and alignment of the probe 24 In one example, the motor 38 moves the probe 24 along a horizontal arc over a stroke of 5/100 mm at each pulse it receives. In addition, the pulses can be applied to one and / or the other of the motors 38 and 40 at an increasing and decreasing frequency to accelerate the probe 24 at the start of the movement and reach a high speed of movement, then to decelerate it. so that the arm 26 does not stop suddenly and does not vibrate the probe 24 to spill the fluids therein. This is useful to allow a high number of arm movements to be carried out in a very short period of time and to achieve the precision necessary for each of the positions of the probe 24.

To achieve the speeds and the precision of movements of the probe 24, the rod 28 is provided with a large pitch thread intended to produce a movement at high speed necessary for the movements of the arm and of the probe. Only part 42 of the screw has been shown in detail. However, it should be understood that the threaded part 42 extends from one end to the other of the rod 28. The arm 26 is mounted on the rod 28 by means of a large pitch nut 44, screwed onto the rod , which is engaged in a passage 46 formed in the arm 26. The motors 38 and 40 can be mounted on a plate 48 located under the base plate 36 and can be mounted on this or can be mounted on another surface.

The motor 38 is provided with a drive shaft 50 passing through an opening 52 formed in the plate 48 and which carries a pulley 54. The latter supports a drive belt 56 also engaged on a pulley 58 mounted on a hub 60 The latter is rotatably mounted by a pair of bearings 62 and 64 on a sleeve 66. This sleeve 66 is keyed or otherwise fixed on the lower end, designated by 68, of the large pitch screw 28 at a end, and is keyed or otherwise fixed at its other end to the drive shaft 70 of the motor 40.

The hub 60 also carries a guide rod 72 mounted or fixed on it by a screw or other retaining means 74. The opposite end of the guide rod 72 is fixed in an upper retaining bearing 76 by a screw or other fixing means 78. The retaining bearing 76 comprises a bearing 80 retained in a slot or recess 82. The upper end 84 of the threaded rod 28 is rotatably engaged in the bearing 80. The guide rod 72 maintains the angular position of the arm 26 by a bearing 86 housed in a passage 88 of the arm 26. The bearing 86, for example a rolling bearing, surrounds the guide rod 72 allowing the arm 26 to easily move the rod 72 up and down while being positioned, like the probe 24, precisely.

When the motor 40 is activated, the threaded rod 28 rotates, driving the arm 26, and consequently the probe 24, up or down by means of the drive nut 44. The bottom of the guide rod 72 is mounted in the hub 60 so that, when the motor 38 is activated and the drive belt 56 rotates the hub 60, the guide rod 72 positions the probe 24 by rotation of the hub 60. The motor 40 can be operated in tandem with the motor 38 to maintain the position of the arm 26 on the rod 28 if the positioning of the arm 26 on the rod 28 is critical. If the arm 26 can be allowed to move slightly up and down when it is rotated by the motor 38, then the motor 40 need not be actuated. In this case, when the hub 60 rotates around the shaft 28, the arm 26 is driven slightly up and down on the shaft 28 because the nut 44 is driven by the threads 42 when the arm 26 is turned by the guide rod 72.

The upper position of the arm 26 and of the probe 24 can be ascertained by an optical reader 90 carried by the arm 26 which can be a conventional light switch in U or C which produces a signal when the path of the light between the branches is interrupted by a tab 92 depending on the upper retaining bearing 76 best visible in FIG. 4. The lower position of the arm 26 and of the probe 24 can be ascertained by a second optical switch 94 carried by the arm 26 below the switch 90, which is actuated by a tab 96 mounted on the rod 72. The legs 92 and 96 can be fixed or adjustable, if desired, to allow the highest position as well as the lowest position of the arm 26 and the probe 24 to be adjusted.

The position defined by the lug 92 will be the highest position in which the probe 24 is withdrawn from all the containers or cavities in which it can be placed so that it can be turned without being damaged. The lowest position defined by the tab 96 determines the position in which the probe 24 is engaged and the distance at which it is from the bottom of the test piece 20 in which it is engaged or from the probe washer 34. To give the mechanism 10 a certain flexibility, other legs and other readers could be used to define other positions, these readers being able to be mounted adjacent to the readers 94 and to have legs extending vertically upwards, parallel to the rod 72 and mounted thereon or on the hub 60.

The angular position of the arm 26 is determined by the horizontal drive motor 38 and can be checked by a coding wheel 98 which is fixed to a flange 100 of the hub 60 by a lower bearing 102. The coding wheel 98 rotates with the hub 60, and the angular position of this wheel and, consequently, of the arm 26 and of the probe 24 can be detected by an optical detector 104 mounted on the plate 48 by a mounting block 106. The coding wheel 98 can be used to determine the angular position of the probe 24 or can be just used as a means of controlling the position which has been determined by the number of drive pulses sent to the motor 40. Since each of the motors 38 and 40 will be of preferably a stepping motor driven by a precise value for each drive pulse sent to it, the vertical and rotational positions of the probe 24 can be determined simply by the number of pulses sent to the motor s 38 and 40. The legs 92 and 96 and the coding wheel 98 can then be used just to check the position determined by the drive motors.

The probe 24 is best represented in FIGS. 2 and 3. It comprises a central passage 108 which extends over the entire length and opens at its upper part into a bore 110 in which a fluid tubing 112 can be fixed to which is connected an ordinary fluid conduit 114. The passage 108 is preferably made of a non-reactive plastic material and extends to the lower end 116, in which it opens, which is the suction and delivery portion of the fluid of the probe 24. The end 116 and a pair of electrical conductors 118 and 120 pass through a non-conductive base sleeve 122. The latter is dimensioned so as to adapt to the internal dimensions of the test pieces 20, the recesses 22 and the probe washer 34.

The upper ends of conductors 118 and 120 are connected to a fluid detector circuit (fig. 8), which includes a power source, and to a detector determining when the stripped lower ends of conductors 118 and 120 come into contact with a surface. of fluid to produce a detection level for mechanism 10. The base 16 of the probe and the conductors 118 and 120 are kept at a distance so that the base 116 has minimal contact with the fluid in the cavities 22 and 32 of such

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so that there is a minimum quantity of fluid which is entrained outside the probe 24 and that a precise dose of fluid can thus be drawn in and dispensed.

The probe 24 is mounted in an opening 124 of a slider 126. The latter comprises a mounting block 128 coming from one piece with it or attached, which is pierced with a tapped hole 130 in which is engaged a type plunger with spring 132 which ensures the proper orientation of the probe 24. The elastic plunger 132 allows the probe 24 to move laterally and vertically if the probe 24 is brought against a solid object to prevent it from being damaged, as well as the mechanism 10. The vertical positioning of the probe 24 is maintained by a spring 134 which is screwed onto a threaded part 136 of the mounting block 128 at one end and which, at the opposite end, is screwed onto a threaded part 138 of the probe 24. Thus, if the probe 24 is brought to meet a solid object during its downward stroke, it will arise upward through the opening 124, which will prevent the mechanism 10 from being damaged. Such a faulty operation could occur without any fault of the mechanism 10, because the reserve 14 may not bring the cavities 22 into their correct position, as also the rotor 18 may not bring the test pieces 20 into their correct position; finally, a test piece 20 can also block.

The probe 24 oscillates from back to front, in order to agitate the fluids in the test pieces 20, on the slide 126 by the motor 30. The operation of the motor 30, the construction of the slide 126 and its mounting on the arms 26 are the better represented in fig. 5 and 6. The slide 126 has a pair of grooves 140 and 142 formed in each of its sides and which extend over its length. The upper part of the arm 26 has a channel 144 in which the slide 126 is adjusted, a lateral space being provided between the faces of the channel 144 and the grooves 140 and 142. The lateral faces of the channel 144 have a plurality of holes 146 which cross, which have a first dimension, exterior, and a second dimension, interior, weaker, opening in the channel 144. The holes 146 each have a rolling bearing 148 engaged in the portion of first dimension and extending partially in the channel 144 to engage in the respective grooves 140 and 142. The ball bearings 148 are held in the holes 146 by a pair of spring plates 150 and 152.

The spring plates 150 and 152 are fixed to the arm 26 by a plurality of screws 154 engaged in openings 156 which the plates present, and in tapped holes 158. The arm 26 has a base part 160 in which the passage is formed of nuts 46 and the passage of bearings 88. The base 160 can have grooves or slots 162 in its walls in which the conductors 118 and 120 and the tube 114 can be fixed. The slide 126 performs a reciprocating movement in the channel 144 controlled by the motor 30 by means of an eccentric shaft passing through an opening or slot 164 formed in the plate 126.

A second embodiment of the mechanism 10 comprises a probe 24 'as shown in FIG. 7. This mechanism 10, like also the probe 24 ′, performs the same operations as those described above. The substantially identical elements will be designated by the same reference numbers as those used in FIGS. 1 to 6 with the index 'to indicate small modifications, different reference numbers being used for elements which have undergone significant modifications.

The probe 24 ′ comprises a sampling and dispensing part 166, made of stainless steel, mounted on a non-conductive sleeve 168 by a threaded mount 170. This part 166 has a base 172 pierced with the suction and dispensing opening and which also serves to form a conductor of a capacitive level detection circuit shown in FIG. 8. The electrical connection with the part 166 is made by a block 174 which is welded or electrically connected in another way to an upper end 176 of the part 166 and which comprises an electrical conductor (fig. 8) connected with a usual way.

The upper end 176 of the part 166 will be provided with a fluid conduit which will be connected to it. The sleeve 168 is mounted in a slider 126 'which is screwed or otherwise fixed to a slider 178 mounted on the arm 26'. The motor 30 has an eccentric shaft 180 engaged in the drive slot 164 of the slide 126 '. The motor 38 drives a drive pulley 58 'by a belt 56. The hub 60' is fixed to the pulley 58 'and rotates therewith on a pair of bearings 182 and 184 which are mounted on a non-rotating journal 186 mounted on base plate 48.

The long threaded drive rod 28 'is rotatably mounted in a pair of bearings 188 and 190 mounted inside the sleeve 186. The bearings 182 and 188 are fixed by an inner shoulder sleeve 192 screwed or fixed with another way on the journal 186. The rod 28 'is mounted in the bearings 188 and 190 by its lower end 68'. The lower end 68 'of the rod 28' is fixed to the drive shaft 70 of the motor 40 by an elastic coupling 194. The latter is rigid in rotation and gives way axially relative to the rod 28 'to eliminate vibrations of the motor while connecting it, in operation, to the mechanism 10.

The hub 60 'comprises a flange 196 to which is fixed a coding skirt 198 which extends partially or completely around the hub 60' according to the maximum angle of rotation that the arm 26 'must be able to effect. The coding skirt 198 can be read by an optical reader 200 mounted on a plate 202 on the base plate 48. The coding position reader 200 can also be used to check the number of drive pulses sent to the motor 40 and ensure that the correct position of probe 24 'has been reached. The code can also be used as a primary position control for the 26 'arm, if desired.

The arm 26 ′ comprises the drive nut 44 engaged on the large-pitched rod 28 ′. The upper end of the large-pitched rod 28 'is not engaged in the upper retainer 76'. The latter also has the lower tab 92 cooperating with the reader 90 carried by the arm 26 '. The guide rod 72 'is mounted in the hub 60', is retained in the retaining device 76 'and is slidably engaged in the bearing 86, preferably a bearing of the rolling type, for easy movement of the arm 26 'up and down the guide rod 72'.

• A second guide rod, 204, has one end mounted in the hub 60 'and its other end mounted in the retaining device 76'. The guide rod 204 is engaged in a passage 206 formed in the arm 26 'which may or may not include a bearing. With the two parallel guide rods 72 'and 204, the upper end of the rod 28' can produce the movement of the arm 26 'to yield if the upper end was retained in the retainer 76'. The second guide rod 204 also ensures that the probe 24 'is correctly aligned and that the mechanism 10 has the desired robustness and safety.

The lowest position of the arm 26 ′ is shown in phantom in 208. This position 208 can be obtained either by counting the drive pulses sent to the motor 40, as indicated previously, or by one or more optical readers mounted on the arms 26 'similar to the reader 90, but distant from the latter, and which correspond to the position tabs mounted on the hub 60', not shown.

An embodiment of the control circuit 210 of the mechanism 10 is illustrated in FIG. 8. The control circuit 210 may be a part of the control of the analysis apparatus 12 or may be a separate control provided with one or more mechanisms 10, if desired. For the purpose of the description only, the command 210 is described with the probe 24 'of the mechanism 10, the probe 24' of the mechanism 10 'and the probe 24 of the mechanism 10 ". Generally, the apparatus of analyzes 12 is provided with substantially identical mechanisms 10, 10 'and 10 "and, therefore, of a single type of probe 24, 24'. Furthermore, as indicated above, only one mechanism 10 can work with the control 210.

Referring to the mechanism 10, the level detection circuit includes an oscillator 212 which provides a high frequency output

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on a pair of lines 214 and 216. We could also have a separate oscillator 212 with each of the probes 24 'for the mechanisms 10 and 10'. Line 214 connects the high frequency signal through a capacitor 218 with the probe 24 'on a line 220 and up to a resistor 222. When the probe 24' has its end 172 which does not reach the surface of the fluid sample 224, the current passes through the capacitor 218 and through the resistor 222 to go to ground. This level of current or voltage proportional to the current is detected by a detector 226 by a line 228 connected to the line 220 and to the resistor 222. When the end of the probe 172 reaches the surface of the fluid sample 224, in one of the cavities 22, a second current passage is formed through the capacitor 218, the line 220, the probe 24 'and the fluid in the cavity 22 which has a fluid resistance 230. The cavity 22 can be formed of a conductive material or may have an electronic mass associated closely with it which will act in the same way as the circuit described in relation to the mechanism 10 '.

By providing that the resistance 222 has a value substantially different from that of the fluid resistance 230, when the end of the probe 172 comes into contact with the fluid surface, the detector 226 detects the change in current and sends a signal of level detection at command 210 by a line 232. Command 210 can use this signal to command motor 40 and prevent the end of the probe from being immersed further in the fluid or to stop the probe at a precise distance from the below the surface 224 of the fluid, if desired. Thus, the probe 24 ′ can be used to aspirate or to withdraw the sample fluid in the cavity 22 without immersing the end of the probe 172 completely in the fluid, regardless of the level of the fluid 224 in the cavity 22.

The level detection circuit of the mechanism 10 'is illustrated in the case where the probe 24' is in one of the receptacles 32 of reagent which, usually, can be made of glass or another non-conductive material. In this case, the high frequency signal, of 100 kHz for example, is sent by the line 216, through a capacitor 234, to a resistor 236 and, by a line 238, to the probe 24 'and to the end 172. When the probe 24 ′ is located above the surface 240 of the reagent, the passage of current takes place through the resistance 236 towards the ground which is detected by a line 242 by a detector 244. This can be a separate detector or may be constituted by a part of the detector 226. When the end 172 of the probe comes into contact with the surface 240 of the fluid, a second current flow is established by the reagent fluid which has a fluid resistance 246.

The container 32, however, is made of a non-conductive material such as glass and, therefore, acts as a capacitami 248. The container 32 can be placed in a metal well or against a metal surface grounded in the reagent reserve 16 to close the electrical circuit. Likewise, the impedance value of the resistance 236 is chosen so as to be appreciably different from the impedance produced by the fluid resistance 246 and the container capacitance 248. When the current is established by the end 172 of the probe in contact with the surface 240 of the fluid, the detector 244 detects the difference in current and sends a level detector signal by a line 250 to the control 210. Again, the control 210 can engage the end 172 of the probe also far below the surface 240 that it is desirable for the particular operation. Capacities 218 and 234 and the alternating current signal prevent electrolysis of fluids.

The mechanism 10 "is illustrated with the probe 24 having the electrical wires 116 and 118. One of these wires, for example the wire 118, is connected to a signal source 252 which can be identical to the oscillator 212, if desired. In this case, the line 120 is connected to a detector 254 which does not receive signals when the probe 24 and the ends of the wires 118 and 120 are located above the surface 256 of the fluid. When the wires 118 and 120 enter in contact with the surface 256 of the fluid, in the reagent container 32, the signal from the source 252 on the line 118, sent through the fluid and through the line 120, is detected by the detector 254. The latter then sends a level detector signal, via a line 258, to the control 210 indicating that the end 116 has reached a known position relative to the surface 256 of the fluid, depending on the alignment with the wires 118 and 120.

The other functions of the control 210 are illustrated diagrammatically for a probe 24. The control 210 applies the appropriate number of drive pulses to the motor 38 by a line 260 to rotate the arm and, consequently, the probe 24 to the appropriate sampling position. Assuming, for example, that it is one of the sample cavities 22, the controller 210 will admit that the probe 24 has rotated by the correct value. The position can be checked to know that the arm 26 and, therefore, the probe 24 are in the proper position by reading the position of the coding wheel 98 by the reader 104. The command 210, after determining that the probe 24 is in the suitable position above the cavity 22 located in the pick-up position of the mechanism 10, then produces drive pulses sent to the vertical motor 40 by a line 262 to drive the probe 24 downwards in the direction of the surface of the fluid.

The level detector produces a signal when the end of the probe reaches the level of the fluid which is sent to control 210. The control then stops the driving pulses on line 262 or when the end of the probe is slightly below the surface of the fluid. The control 210 then actuates the fluid displacement device 264 by a line 266. The fluid displacement device 264 can be a piston device or other means for setting in motion a fluid connected by suitable valves to the fluid conduit 114. The piston will be moved the appropriate distance to withdraw or aspirate the desired quantity of fluid in the probe passage 108.

The dimensions of the probes 24 and 24 ′ will be chosen so that the volume of sample fluid or the volume of reagent fluid is entirely contained in the passage 108 or in the part 166. This substantially eliminates any entrainment problem when the probes are rinsed in the probe washer 34. Once the probe 24 has aspirated the desired dose of fluid, the command 210 produces pulses, sent to the motor 40 via the line 262,

to be moved up until the switch 90 is actuated by the tongue 92 indicating that the probe 24 and the arm 26 are in their upper position. When the arm and, consequently, the probe 24 have reached their upper or rotational position, the control 210 then sends the appropriate number of drive pulses by the line 260 to the motor 38 to rotate the probe 24 until in the dispensing position above the test piece 20 or other reaction vessel housed in the dispensing position. The angular position can again be checked by the coding wheel 98.

The probe 24 is then driven downwards into its lower dispensing position which will be determined by a switch such as the tongue 96 or by the number of drive pulses applied to the vertical motor 40. The command 266 then indicates to the displacement device of the fluid 264 that the probe 24 is in its dispensing position and that the device 264 dispenses the fluid in the probe 24. By a suitable valve device, it can also add an amount of diluent to the sample dose in the test piece 20. The control 210 then actuates the oscillating motor 30 by a line 268 to cause the probe 24 to oscillate back and forth and agitate the fluid in the test piece 20. The control 210 deactivates the motor 30 and then drives the probe 24 in its upper position by sending drive pulses to the motor 40.

The probe 24 is then rotated by the motor 38 in a position located above the probe washer 34 where it is driven downwards by the motor 40 in the probe washer and washed externally therein. The probe 24 can be washed internally by sending a washing fluid coming from a source 264 through the passage of probes 108 and 166. The probe is then brought back to its upper position by the motor 40 where it is maintained in a position where it is ready for the next cycle.

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Fig. 9 illustrates another embodiment of the fluid transfer device, generally designated by I, the arm being generally designated by II. The construction of arm II, as it appears most clearly in the exploded view of FIGS. 10A and 10B, comprises a support top plate 301 and a support base plate 302 which, together with threaded spacers 303, clamp three main elements together: a bearing support 304 having a bearing 305 pressed into each end to receive the rod described above, a nut 306 and a stirring motor 307 comprising an eccentric cam with ball bearing 307a mounted eccentrically.

The probe support arm 308 is mounted on the top surface of the top support plate 301 by four screws. The probe support arm 308 first serves as a support for a linearly oscillating assembly driven by the stirring motor 307 and which is held on the underside of the probe support arm 308 by two small plastic blocks, know the front guide support 309 and the rear guide support 310 as best shown in the exploded view of FIG. 10A. The linearly oscillating assembly slides from back to front under the effect of the eccentric cam 307a driven by the agitator motor 307.

Referring again to the exploded view of FIG. 10A, it can be seen that the linearly oscillating assembly comprises a clamp 312 which has two holes intended to receive probe guide tubes 313. These tubes are held on the clamp 312 with adhesive and screwed in an adjustable manner at 315 on the eccentric linkage 314 at the opposite end. The eccentric linkage 314 sends the driving force from the stirring motor 307 to the probe 311 pinched by means of the tubes 313.

One or more conductor wires 316 pass through one or more probe guide tubes 313 and serve as an electrical connection between the probe 311 and an electrical circuit for detecting the level of the liquid, not shown, intended to detect the surface of the samples or of the reagents, as previously described. The wire 316 is connected to a solder type terminal 317 on the side of the probe and is further screwed to a threaded rod 318 which, in turn, is silver welded to the probe 311 which sucks and dispenses the fluids. The opposite end of the wire 316 is attached to a printed panel 319 located behind the arm • and held by a metal strip 320, as shown in fig. 10C.

The threaded terminal 318 is silver welded to the probe 311 and is further screwed into a probe housing 321 which serves to protect the probe 311 from any damage and at the same time helps to keep its extension straight to penetrate a test tube. narrow.

When screwed into the probe housing 321, the probe 311 can be clamped into the clamp 312 of the linearly oscillating assembly. The probe 311 and the linearly oscillating assembly can then be adjusted to the suction and dispensing position of the liquid by mounting screws which fix guide supports 309 and 310 and pass through an elongated slot formed in the upper surface of the arm 308. supporting the probe as shown in fig. 9 and 10A.

As best appears in fig. 9, a detection switch 322 is preferably mounted on one side of the rear end of the probe support arm 308 in such a way that this detection switch 322 moves vertically between the branches of the detectors 323, of U-shape, comprising a light emitting diode (LED) to interrupt the transmission and indicate that a specific vertical position of the arm 308 and of the end of the probe 311 has been reached. The detectors 323 are held in position by a grooved vertical detection support 324 which allows vertical adjustment of each detector 323, as shown in FIG. 2B.

When the arm 308 and the switch 322 attached to it move vertically, the detectors 323 and the terminals of the electric wires 323a remain stationary vertically on the support 324, ensuring that the wires 323a do not twist during the vertical movement of the arm 308. Such kinking constitutes a problem always present in automatic equipment of this type when the wires of electrical elements are carried by mobile arms and when the movement of these arms or of their components produces a winding of the wires. In extreme situations, movement of the wires can create resistance and prevent the desired movement of the arm.

The construction of the drive device for the vertical and horizontal movements of the arm 308 is described with reference to FIGS. 2.2B and 2C.

The vertical movement is produced by a stepping motor 325 which drives a threaded rod 326 by an extension 327 and a coupling 328 which has a certain lateral flexibility to allow lateral and angular errors of alignment of the rod 326 when the latter turned.

The horizontal movement of the arm 308 is produced by a stepping motor 329 mounted on a motor support plate 330 which serves to drive a pulley 331 by a belt 332 and a pulley 333 with a drive ratio preferably from 4 to 1. The lower ends of the two guide shafts 334 and 334a are fixed in the pulley 331 and pass through bearing supports 304 and 346, respectively, to drive the plates 301 and 302 and the arm 308. Thus, the pulley 331 serves also main bearing of the journal type for the horizontal movement of the arm 308. The pulley 331 rests on a thin thrust washer 335 which reduces the wear and the friction between this pulley and the support plate of the motor 330.

The central hole 331a of the pulley 331 receives a lubricated stainless steel sleeve 336 which is fixed in a flat plate forming a bearing hub base 337. The plate 337 is wedged so as to determine the location of two conical holes on the opposite sides of the stainless steel sleeve 336 which receives the screw heads 338 serving as mechanical stops for the horizontal movement of the pulley 331. The setting is obtained by a small pin 339 pressed into a wall of the sleeve 336 and engaged in a notch 337a of the plate 337.

The base hub plate 337 is used to receive the vertical stepping motor 325 and to receive the entire fluid transfer device I. The plate 337 is pierced with two conical holes made in the vertical spacers 340 and 341 which support a mounting plate of a detector 342 carrying a segmented photoelectric sensor 343 as shown in FIG. 10C. As best shown in fig. 12, the photoelectric detector 343 is of the light-emitting diode type and is used to read a coding section 344 which confirms the horizontal position of the end of the probe 311 in the positions of fluid collection, dispensing, washing and oscillation. The optically coded section 344 is mounted on small spacers 345 on the base, threaded surface of the pulley 331 and rotates with this pulley in the horizontal mode. The spacers 345 which carry the optically coded section 344 also serve as stops for the mechanical stops 338 which limit the movement of the pulley 331 within a determined angular range.

When assembled, the pulley 331 slides over the sleeve 336 and rests against the support washer 335. The threaded rod 326, the coupling 328 and the shaft extension 327 are connected to each other and kept in alignment on the central opening of the steel sleeve 336 and screwed in an adjustable manner to the shaft of the vertical motor 325.

A bearing 346 for the shaft 334a is freely fixed by a push-type retaining ring 347 to the precision slot placed on one side of the top support plate 301 as shown in FIG. 10A.

Referring to fig. 9 and 10A, it can be seen that the guide shafts 334 and 334a have their conical ends held in a retaining plate 348. Besides the transmission of the movement

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rotary pulley 331, the guide shafts 334 and 334a produce a guide for the vertical movement of the arm 308. A shoulder washer in Nylon 349, which acts as a vertical support washer, and a allillon pliers 350 guide the vertical movement from the top of the threaded rod 326.

As shown in fig. 10A, a cover 351 having a lateral opening 351a covers a top plate 348 and is fixed by a screw 352 and by a spacer 348a. Clips 353 are held in holes made in the cover 354 and fix a free extension (not shown) of the tube 354 to the cover 351. The slightly shoulder end of the tube 354 provides a fluid conduit to the probe 311 which projects above the top end of the threaded stud 318 and which is welded thereto. The tube 354 is fixed to the stud 318 by a knurled nut 355.

During the operation of the arm 308, the wire 316 of the probe 311 moves inside the protection of the tube 313 during the oscillation of the probe 311. During the vertical movement of the arm 308, the movement of the wire 316 and the conducting wires 356 of the agitator 307 s are guided by a conduit through a stationary vertical sleeve 357 which is preferably attached to the sensor support 324 as shown in FIGS. 11 and 12. The pulley 331 is pierced with a through passage 331b which provides a conduit for the extensions of the wires 316 and 356 in the sleeve 357 as also for the extension of the detector wires 323a. The extensions of the wires passing through the passages 331b remain substantially stationary with respect to the rotation of the arm 308 and of the pulley 331 because the passage 331b is placed in close proximity, radially, to the axis of rotation of the helical shaft. 326 produced by the position of the pulley 331.

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10 sheets of drawings

Claims (27)

645,729 2 1. Multi-position fluid transfer mechanism, having an elongate movable arm supporting a fluid probe at a distal end for withdrawing and dispensing fluid, characterized by oscillating means mounted on said arm for oscillating said probe and agitating the fluid in which it is immersed. 2. Fluid transfer mechanism according to claim 1, characterized by a vertical rod movably connected to one end of said arm opposite to said distal end, first drive means for moving said arm in a translational movement relative to said rod and along the axis thereof, and second drive means for rotating said arm in a circular arc path around the axis of said rod. 3. Fluid transfer mechanism according to claim 2, characterized by means for accelerating said second drive means for a first part of the movement in said trajectory and decelerating said drive means for a last part of movement in said trajectory. 4. Fluid transfer mechanism according to claim 2, characterized in that the probe is mounted on said arm by means of biasing means keeping it in a first position, while allowing it to be placed in a second position when it comes into contact with a surface other than that of the fluid. 5. Fluid transfer mechanism according to claim 2, characterized in that said rod comprises a screw connected to said first drive means and which is screwed to said arm to move the latter up and down along said axis, when said rod is rotated by said first drive means. 6. Fluid transfer mechanism according to claim 2, characterized in that said first drive means' comprise a stepping motor for moving said arm, and in that it comprises means for controlling the position of said arm and said probe on said rod. 7. Fluid transfer mechanism according to claim 2, characterized in that it includes guide means connected to said rod to maintain the angular position of said arm, when the latter is moved up and down the along said axis of the rod by said first drive means. 8. Transfer mechanism according to claim 7, characterized in that it comprises a hub connected to said second drive means, said guide means comprising at least one upright mounted on said hub at one end, extending through said arm and connected to said rod at its other end. 9. Fluid transfer mechanism according to claim 1, characterized in that said oscillating means comprise a slide mounted on said arm and which carries said probe mounted on it at a distal end, an oscillating drive means being connected to the opposite end of said slide to oscillate the latter and the probe on the arm. 10. Fluid transfer mechanism according to one of claims 1 or 2, characterized in that said probe comprises level detection means arranged to react when it comes into contact with the surface of the fluid. 11. Fluid transfer mechanism according to claim 10, characterized in that said level detection means comprise a pair of electrical wires extending substantially parallel to an opening in the probe to form an electrical circuit through the fluid between said wires when these are in contact with the surface of the fluid. 12. Fluid transfer mechanism according to claim 10, characterized in that said level detection means comprise a metallic conducting suction part, which is connected to oscillating electronic means to allow the passage of an alternating current to through said fluid when said metal part comes into contact with it. 13. Fluid transfer mechanism according to claim 10, characterized in that it comprises means for accelerating said second drive means for a first part of the movement in said trajectory and decelerating said second drive means for a last part of the movement in said trajectory, guide means connected to said rod for maintaining the angular position of said arm when the latter is moved up and down along the axis of said rod by said first means of drive, means for controlling the position of said arm and said probe on said rod, and means for determining the angular position of said arm and said probe. 14. Fluid transfer mechanism according to claim 2, characterized in that said second drive means comprise a stepping motor for driving said arm, and in that it comprises means for determining the angular position of said arm and said probe. 15. Fluid transfer mechanism according to claim 14, characterized in that said means for determining the angular position of the arm comprise coding means driven in rotation with said arm and means for reading said coding means. 16. Fluid transfer mechanism according to claim 14, characterized by means for accelerating said second drive means for a first part of the movement in said trajectory and decelerating said second drive means for a last part of movement in said trajectory . 17. Fluid transfer mechanism according to claim 16, characterized in that these acceleration and deceleration means comprise means for changing the frequency of the drive pulses applied to said stepping motor. 18. Fluid transfer mechanism according to claim 14, characterized in that said first drive means comprise a stepping motor for moving said arm, and in that it comprises means for controlling the position of said arm and the probe on said rod. 19. Fluid transfer mechanism according to claim 18, characterized in that it comprises counting means for counting the number of drive pulses sent to each of said stepping motors corresponding to the positions of said arm. 20. Fluid transfer mechanism according to claim 1, characterized in that said oscillating means comprise: a watch for holding said probe adjacent to said distal end of said arm, at least one tubular element connected to said mount and extending substantially parallel to said arm, and drive means for producing a linear oscillation of said tubular element substantially along the axis thereof so as to produce an oscillation of the probe fixed to said mount. 21. Fluid transfer mechanism according to claim 20, characterized by a conductor passing through said tubular element to connect said probe to a level detection circuit. 22. Fluid transfer mechanism according to one of claims 20 or 21, characterized in that said tubular element is placed below said arm. 23. Fluid transfer mechanism according to one of claims 1 or 20, characterized by a switch projecting from the rear end of said arm opposite to said distal end to interrupt, in a given vertical position of the arm, an emitted light beam by a photoelectric detector, so as to indicate said vertical position reached by the arm. 24. Fluid transfer mechanism according to claim 23, characterized by a support for positioning one or more detectors in the vertical path of said switch. 25. Fluid transfer mechanism according to claim 24, characterized in that said detector is adjustable in position on said support. 5 10 15 20 25 30 35 40 45 50 55 60 65 3 645,729 26. Fluid transfer mechanism according to one of claims 1 or 20, characterized in that said second drive means comprise a pulley producing the horizontal rotation of said arm, this pulley being pierced with a through passage for wires conductors. 27. Fluid transfer mechanism according to claims 10 and 26, characterized in that said conductive wires comprise conductors connected to said level detection means and supported separately by said arm.