CS205654B1 - Pneumatic doser of extra small liquid amounts - Google Patents

Description

The invention provides a pneumatic dispenser of very small amounts of fluid.

The prior art dispensers of small amounts of fluid contain movable mechanical parts. These are capable of operating in less demanding operating conditions. Ioh reliability is mainly due to the quality and durability of moving mechanical parts.

These drawbacks are overcome by a pneumatic dispenser according to the invention, which consists of a dispensing element consisting of a fluid element with an outlet channel for dispensing the fluid on the stable side and a waste recirculation channel on the unstable side, the input for the control pulses being connected to the outlet control circuit. It consists of a control lmpulse generator, consisting of a flip-flop logic monostable flow element with variable pneumatic resistance and pneumatic capacitance in bad coupling, and a control lmpulz former, consisting of a flip-flop logic monostable flow element.

The low-volume pneumatic dispenser of the present invention thus formed does not contain any movable, flame-retardant parts and is suitable for dispensing very small quantities of aggressive liquid or gas with high accuracy and long-term stability under severe operating conditions.

205

20S 654

In the attached drawing, FIG. 1 shows a diagrammatic arrangement of parts of a pneumatic dispenser according to the invention, FIG. 2a is a schematic designation of a fluidized-bed logic monostable flow element; Fig. 2b is a state table and Fig. 2c is a table of pretensions of this fluidic logic monostable current element.

The schematic designation of the fluidized logic monostable current element is shown in FIG. 2a, where S and N are complementary outputs, P _y is a rladlaol pressure signal and P _Q jb the supply pressure. In the status table in Fig. 2b, the states of the output signals S and N are defined with respect to the control signal P _r. in the absence of a control signal, i. P 0 for the output signals holds S 1 1 and N-0, and for the state Q 2 2, in the presence of the control signal, i. P _r l l for the output signals, S 0 0 and R 1 apply. In the conversion table of FIG. 20 is defined as the initial state of the output signals and 6 as the final state with respect to the control signal value. If the outputs are in the initial state Q ·! and if the rladlaol signal reaches the value of P _r -0, the final state of the outputs will not change, so Q1.

If the outputs are in the initial state Q1 and if the rladlaol signal reaches the value P _r -1, the final state of the outputs will change or Q-2. further, if the outputs are in the default state of Q-2 and if the rladlaol signal reaches a value of P _r -1, the final state of the outputs will not change and Q-2. Finally, if the outputs are in the initial state Q-2 and if the rladlaol signal reaches the value P _r -0, the state of the outputs will change whether Q1.

The pneumatic dispenser of a very small amount of fluid B at a pressure P ^ (FIG. 1) consists of a dispensing element 10 controlled by a control signal P „and a pneumatic control circuit consisting of a pulse generator 20 and a thrust regulator 30. Napájaoím generator 20 with the pressure P ^ 1 the beamformer 30 supply pressure P _fl j SRAW the Medlov which mdže be any gas.

The dosing element 10 is formed of a monostable flow element that divides the dosed fluid into two outlet channels, the channel S on the stable side of the element being dosed from the standpoint of the element and the channel N on the unstable side waste, re-circulating. The logioc monostable flow element has the characteristics of a two-pole valve (flap), so that its flow cross section is either fully open or closed. The flow cross section lock is given by the length of the control pulse in the rladlao channel. The orthogonal control signal generator 20 is a logical monostable current element with variable pneumatic resistance R and capacitance C in the wrong coupling. Substituting in the mold 30 which is provided with solenoid current logical element, the set pressure P napájaoím _fl ^.

The accuracy of the metered amount of fluid B is dependent upon the stability of the frequency of the slopes P _r , the dynamic properties of the monostable flow elements and the constant pressure of the elements.

The amount of fluid B to be dosed is determined by the flow rate characteristic of the dosing element 10, the frequency of the pilot signal P _p and its frequency. The flow characteristic of the dosing element 10 is the volume or weight flow rate of fluid B oez

205 654 an open flow cross-section of the channel 6 of the stable side of the element from the pressure drop, geometry and dimensions of the element. The frequency of the control signal P _r is adjusted by changing the parameters of the feedback members R, 0 and alternating with the supply pressure P _n j.

The dosing volume can also be controlled by regulating the feed pressure ^P nl of the dosing fluid B.

By providing a flip binary or decimal frequency divider to the output of the 20 lm pulse generator, the possibility of integer frequency setting can be extended.

The present invention can also be used to provide a flush pulse device for ratio or drag flow control of multiple fluids.

Claims (2)

Pneumatic dispenser of very small amounts of fluid, characterized in that it consists of a dispensing element (10) consisting of a fluidized logic monostable flow element with an outlet channel (S) for dispensing the fluid (B) on the stable side with a waste recirculation channel (N) on the unstable side. the input for the control pulse is connected to the output of the pneumatic control circuit, which consists of a control pulse generator (20) consisting of a fluidized-bed logic monostable current element with variable pneumatic resistance (R) and a pneumatic capacitance (C) in bad coupling; ) of control pulses, consisting of a fluidic logic monostable current element. 2 drawings