RU2290611C2 - Device for volumetric batching of fluid - Google Patents

Abstract

FIELD: measuring technique.

SUBSTANCE: device comprises measuring vessel, stop, air bell, diaphragm, air tube, pickup of mutual movement of the bell and air tube, atmospheric pressure gage, gage of pressure of fluid at the entrance to the batcher, computing-control device, and actuating mechanisms in the lines for supplying fluid to the batcher. The bottom of the air bell points upward, is mounted inside the measuring vessel, and can move inside the vessel from its bottom to the stop. The stop is mounted on the inner side of the vessel for permitting movements. The diaphragm is built in the bottom of the air bell and is rigidly connected with the air tube that is connected with the pickup of mutual movements mounted on the outer side of the bottom of the air bell. The pickup of mutual movements the atmospheric pressure gage, gage of pressure of fluid at the entrance to the batcher are connected with the computing-control device that is connected to the actuating mechanisms in the line for supplying fluid to the batcher.

EFFECT: enhanced precision of batching.

3 cl, 1 dwg

Description

Technical field

The invention relates to the field of portioned dosing of liquid media, for example volumetric dispensers, and can be used in various fields of technology.

State of the art

Volumetric fluid dispensers are known, for example, according to AC 1118862, AC 1337670, patent of the Russian Federation 2054631, containing a measuring vessel and additional elements (membranes, bellows, floats, air tubes, etc.) that provide improved metering accuracy. In patent application 99124335/20 (025757) (prototype), a dispenser is provided with an additional double bellows associated with an air tube, the inner cavity of the bellows communicating with the atmosphere, which allows for changes in atmospheric pressure. The disadvantages of this device are: 1) the need to ensure a tight connection of the air tube with the membrane and with the bellows under the condition of their mutual movement; 2) a progressive deterioration in metering accuracy due to changes in membrane elasticity; 3) dosing error caused by a change in the buffer capacity of the air in the dispenser with a change in the dose.

SUMMARY OF THE INVENTION

The proposed device is devoid of the described disadvantages, has higher reliability and metering accuracy. This is achieved by introducing additional elements: an air bell and a movable stop in a measuring container, a liquid pressure sensor at the inlet of the dispenser and an atmospheric pressure sensor, as well as a control device with the possibility of computational operations that take into account the influence of the above parameters on the metering accuracy. At the same time, the presence of an air bell and an emphasis ensures the exclusion of a dosing error due to a change in the buffer volume of air.

The proposed device is shown in the drawing and contains a measuring tank 1 with a stop 2 located on its inner surface 2 with a scale 3, an air bell 4 with a membrane 5 located on it, an air tube 6 and a sensor for mutual movement of the bell and tube 7, an atmospheric pressure sensor 8, a sensor fluid pressure at the inlet to the dispenser 9, a control device with computational functions (WUU) 10, locking-actuating organs 11 and 12 on the lines of fluid supply and dose. In this case, the air bell is located upside down inside the measuring tank with the possibility of moving in it from the bottom of the measuring tank to the stop, the air tube is fixedly mounted in the membrane, and the sensors of mutual movement, atmospheric pressure and liquid pressure at the inlet of the dispenser are connected to the WUU, and the last with executive bodies.

Device operation

In the initial position, the container 1 is empty, the air bell 4 is in the container 1 and lies on its bottom. The executive body 11 is closed, and the body 12 is open. At the command of the VUU, the organ 11 opens and the organ 12 closes, the liquid begins to flow into the tank 1 from the source of the liquid (supply tank, pump, etc.). The liquid enters the open bottom end of the bell 4, displacing air from it through the tube 6. As soon as the liquid level in the tank 1 and the bell 4 rises to the lower edge of the tube 6, the air outlet from the bell 4 stops, and the air available in the bell 4 lifts it synchronously with a rise in the liquid level in the tank 1. When the upper edge of the bell 4 reaches the stop 2, the bell stops, the liquid level in it rises, the air inside it is compressed, its pressure increases, and the membrane 5 together with the tube 6 moves up. In this case, the mutual displacement sensor 7 is triggered, the signal from it enters the VUU 10, the latter is triggered by closing the organ 11 and opening the organ 12. The dose is stopped, and the dose accumulated in the tank 1 is output from the dispenser, for example, into a container. At the same time, the signals from the atmospheric pressure sensor 8 and the liquid pressure sensor at the inlet to the dispenser 9 are constantly supplied to the VUU. The VUU 10 processes all the signals entering it, generating a control signal to stop the dose dialing according to the algorithm described below.

заданному, т.е. каждому V_зад соответствует свой

. Далее начинается сжатие воздуха в колоколе 4, причем выполняется (в изобарических условиях) соотношение Р·V=Р₀·V₀. Таким образом, срабатывание датчика 7 происходит в момент, когда V=P₀V₀/P, т.е. образуется статическая погрешность дозирования ΔV=V₀-V=V₀(1-Р₀/Р)=V₀(1-Р₀f/F), зависящая от Р₀, V₀, т.е. величин переменных. Величина V₀ (буферный объем воздуха) в устройстве - прототипе определяется заданной величиной дозы и в каждом случае дозирования случайна. В предложенном устройстве величина буферной емкости постоянна (равна объему колокола от нижнего края воздушной трубки до днища колокола), а погрешность дозирования за счет изменения V₀ и P₀ учитывается в ВУУ 10 по алгоритму, приведенному выше, что позволяет рассчитать необходимую величину положения упора 2.Consider the conditions for measuring the dose in the tank 1 and bell 4. Before the dose is set, the bell has atmospheric pressure P ₀ , and the air volume in the bell at the time the liquid level rises to the lower edge of the tube 6 is denoted by V ₀ . Further, the bell rises until it stops at a stop 2. Further, the liquid level in the bell rises slightly, the air volume in the bell decreases to V, and its pressure reaches P. When the membrane area is 5f, the force F = P · f acts on it from below, and when it reaches the magnitude of the gravity of the moving parts (membrane and air tube), then at this moment the membrane rises and the sensor 7 is activated, the dose is cut off. Let it be necessary to measure the volume of liquid V _ass , for this, the stop 2 is set so that the volume of liquid in the tank 1 (from the bottom to the lower edge of the tube 6) is equal to

given, i.e. each V _ass corresponds to its

. Then begins the compression of the air in the bell 4, and is satisfied (in isobaric conditions) the ratio P · V = P ₀ · V ₀ . Thus, the operation of the sensor 7 occurs at the moment when V = P ₀ V ₀ / P, i.e. a static dosing error ΔV = V ₀ -V = V ₀ (1-P ₀ / P) = V ₀ (1-P ₀ f / F) is formed, depending on P ₀ , V ₀ , i.e. quantities of variables. The value of V ₀ (buffer volume of air) in the device is a prototype is determined by the specified dose and in each case, the dosage is random. In the proposed device, the value of the buffer capacity is constant (equal to the volume of the bell from the lower edge of the air tube to the bottom of the bell), and the dosing error due to changes in V ₀ and P _{0 is} taken into account in WUU 10 according to the algorithm above, which allows you to calculate the required position of the stop 2 .

In addition, it is known that changes in the liquid pressure at the inlet to the dispenser also cause a metering error (see, for example, the device according to AC 1118862), therefore this value is also measured by the sensor 9 and fed to the VUU 10.

The advantages of the proposed device are determined by the fact that: 1) the proposed device compensates for the static dosing error caused by the variable values of the buffer capacity of the air, atmospheric pressure and liquid pressure at the inlet of the dispenser, as a result of which the accuracy of dosing is increased; 2) in addition, in the proposed device excluded rigid, but with the ability to move the connection of the membrane with the air tube and the bellows, which increases reliability; 3) in addition, the membrane in the proposed device has a significantly smaller area, and the air tube has a length, which reduces the weight of the moving parts of the membrane unit, the constant load on the membrane, which increases the reliability of the entire device.

Claims (4)

1. Volumetric liquid dispenser containing a measuring container, a membrane, an air tube, actuators for supplying liquid to a measuring container and dose selection and a control device, characterized in that it is additionally equipped with an air bell, an emphasis, a sensor for mutual movement of the bell and air tube, a sensor atmospheric pressure and a liquid pressure sensor at the inlet to the dispenser, with the air bell located upside down in the measuring tank between the bottom of the measuring tank and the stop, the stop is placed on the inner surface measuring capacity, the mutual displacement sensor is located on the outer surface of the bottom of the air bell and is in communication with the air tube, the membrane is rigidly connected to the bottom of the air bell and the air tube, the control device is connected to the mutual displacement sensor, atmospheric pressure sensor, liquid pressure sensor at the inlet of the dispenser and with actuators on the fluid supply lines to the dispenser and dose selection. 2. The dispenser according to claim 1, characterized in that the emphasis placed on the inner surface of the measuring tank is arranged to move along the vertical wall of the measuring tank. 3. The dispenser according to claim 1, characterized in that the air bell is made with the possibility of its movement inside the measuring container from the bottom of the latter to the stop. 4. The dispenser according to claim 1, characterized in that the control device is arranged to process signals from the atmospheric pressure sensor and the liquid pressure sensor at the inlet of the dispenser and calculate the static metering error, for example, according to the formula ΔV = V ₀ (1-fP ₀ / F), where P ₀ , V ₀ - atmospheric pressure and the initial volume of air in the bell, f and F, respectively, the membrane area and the force acting on the membrane.