SU940834A1 - Apparatus for metering liquids - Google Patents

Description

(54) DEVICE FOR DOSING LIQUIDS

one

The invention relates to laboratory equipment, namely, devices for dispensing liquids, and can be used in the practice of research laboratories (biochemical, clinical diagnostic and others) for various studies.

A device for metering liquids is known, B. A piston is driven by an electric motor by means of a slat and a reduction gear. On the shaft, driven in rotation by an electric motor, a disk is mounted, along the edge of which a slot is made, providing an intermittent luminous flux of the counting electronic device. The number of pulses counted by this device gives the exact amount of liquid delivered by the burette 1.

The disadvantages of such a device are the complexity of the design, due to the presence of an electric motor and a reduction gear, the degree of accuracy of the titration is not high enough, caused by the dependence on the gear pitch, low reliability and efficiency.

A device for dosing is known. liquids, in which the means for creating a vacuum for withdrawing a liquid is a pump with an integrated electric drive. The amount of liquid taken into the pipette is monitored using a photoelectric tracking device that automatically shuts off the pump as soon as a 5 column of liquid interrupts a beam of light transmitted through the pipette at a predetermined level 21.

The drawbacks of such a device are the complexity of the design, due to the presence of a power source, an electrically driven pump and a photoelectric tracking device, the accuracy of dosing is not enough, due to possible interruptions in the operation of the pump, low reliability and efficiency.

15

A device for dispensing liquids is known, which includes a chamber for liquids, provided with tubes with valves, and a device for setting and dispensing a dose 3.

20

This device, selected as a prototype, is characterized by insufficient dosing accuracy due to the use of / as a tool for dosing the FAIL.

The aim of the invention is to improve the accuracy and speed of dosing.

The goal is achieved by the fact that in the device for dosing, including

30 a fluid chamber equipped with tubes with valves, and a device for setting and dispensing a dose, the latter made in the form of a piezoelectric bimorph plate installed in the chamber, a pulse setting unit and a control unit connected to it, connected with an impulse quencher unit, made in the form of a digital converter connected to the pulse setting unit and a calibrated indicator device connected with it.

In addition, the device is equipped with a fluid chamber and tubes with valves installed above the plate, and the control unit contains a dose setting device, a pulse counter connected to it, installed between the plate and the output of the pulse setting unit and associated with the last feedback.

FIG. 1 schematically shows a general view of the proposed device; in fig. 1 is the same as the embodiment.

The metering device includes a chamber 1 comprising a piezoelectric bimorph plate 2 built in a cross section, connected by a tube 3 with a capacity 4 for a titrating fluid. The tube 3 is supplied with a valve 5 regulating the iodine of the liquid from the tank 4 to the chamber 1. The voltage on the plate 2 is supplied from an immersion unit made as an adjustable voltage source 6 through the switch 7. The number of pulses fed to the plate 2 is counted by the unit control, made in the form of a digital converter 8, and is read in units of volume from the calibrated indicator device 9.

The device works as follows.

When the key 7 is closed, a pulse from the source 6 is applied to the plate 2 and its piezoelectric element bends upward by a quantity strictly proportional to the amplitude of the voltage. In this case, an overpressure is created in the chamber 1, which is pre-filled with the titrating fluid, the valve 5 closes and some strictly defined volume of fluid is displaced from this chamber. The next time, when a reverse-polarity pulse is applied to the plate 2, the bending of its piezoelectric element occurs in another direction, when this vacuum is created in chamber 1, vacuum 5 is closed and a volume of liquid equal to the displaced volume is sucked from tank 4 through tube 3. Thus, camera 1 is brought back to the ready state for the next cycle. At the same time, in the device 9, the volume of the displaced fluid is noted, also depending on the magnitude of the pulse amplitude. After closing the key 7, the device operates in an automatic mode until the dosing is stopped, which is interrupted,

open the m of this key. Device 9 shows the exact amount of fluid dispensed by the device.

The device can only be configured to deliver a dose from the chamber {, which in this case can be made in the form of a cylinder with a plate fixed in its upper part and a bottom in the form of a cone with a metering hole at the top.

FIG. Figure 2 depicts one embodiment of a device for dispensing liquids, comprising an additional chamber 10 with a piezoelectric bimorph plate 11 embedded in a transverse cross section, a piping system 12 with four valves 13-16 connected to the container 17 of the metered liquid. For example The plate 11 is supplied from a pulse setting unit, which is made in the form of a generator of 18 rectangular pulses, controlled through a control unit, made in the form of a reversible pulse counter and a dose setting device 20. The dosing fluid is directed to the tube 21.

The device works as follows.

When a rectangular pulse is applied from the generator 18 to the plate, and its piezoelectric element is curved by an amount strictly proportional to the voltage. Suppose she bent up. At the same time, a vacuum occurs in the lower part of the chamber 10, as a result of which the plug 13 closes, the valve 14 opens and some liquid from the tank 17 enters this part of the chamber. In the upper part of Chamber 10, the pressure rises and a certain amount of liquid that has previously arrived at the bottom of the chamber, is pushed out of it and is directed to the tube 21.

When the plate 11 is deflected downward, a vacuum is created at the top of the chamber 10, as a result of which the valve 15 closes and the valve 16 opens and some volume of liquid enters this part of the chamber. At the same time, in the lower part of the chamber, the pressure rises, as a result of which the valve 14 is closed, and the valve 13 is opened and a certain amount of liquid which has previously entered this part of the chamber is pushed out of it and directed to the tube 21.

The high resolution of the device, due to the possibility of strictly controlling the degree of bending of the piezoelectric bimorph plate, allows to dose any required amount of fluid by specifying a certain number of rectangular and multi-waves on a calibrated dose setting device. The metering of the amount of dosing liquid is performed by a reversible pulse counter.

In addition, a piezoelectric bimorph plate provides high reliability in the operation of the proposed device, its speed and increased efficiency.

Claims (4)

1. A device for dispensing liquids comprising a chamber for liquids  equipped with valves and tubes, and a device for the collection and delivery of a dose, characterized in that, in order to improve the accuracy and speed of dosing, the device for the collection and delivery is up to. The circuit is made in the form of a piezoelectric bimorph plate installed in the chamber, a pulse setting unit connected to it and a control unit connected to the pulse setting unit. 2. The device according to claim 1, characterized in that the control unit is made in the video of the digital converter connected to the pulse setting unit and the calibrated indicator device associated with it. 3. The device according to claim 1, characterized in that it is provided with a chamber for liquids mounted above the plate and tricketed with valves. 4. A device according to claim 1, characterized in that the control unit comprises a dose setting device, a pulse counter connected to it, set by a meleda plate and an output of the pulse setting unit and associated with the last feedback. five Sources of information taken into account in the examination: 1.Patent of France No. 227332, cl. B 01 L 3/02, 1976. 2. The patent of Germany No. 2613340, cl. B 01 L 0 3/02, 1977. 3.Patent of France N ° 2287272, cl. B 01 L 3/02, 1976. J f hi 1 V 77/7777/7, FIG. / rff rff