RU1807464C - Liquid level regulator - Google Patents

Abstract

The invention relates to automatic control and can be used in systems for automatically controlling the level of liquid in a tank. The purpose of the invention is to increase accuracy and reliability. The controller contains a master / power supply 2 capacity 5, mounted vertically movable, in communication with a flow capacity 1, on which a level sensor 3 is connected, connected to an actuator mounted on the working fluid supply pipe 11. Stops 8 and 9 are fixed on the housing of the driving capacitor 5 with the possibility of contacting the level sensor 3, and the driving capacitor 5 is mounted on springs 6, the stiffness coefficient of which is determined by the formula: Where is the stiffness coefficient of the spring 6; S is the free surface area of the liquid in the master tank 5: g is the acceleration of gravity; n - the number of springs 6. 3 silt, -s Compressed air w ё

Description

The invention relates to automatic control and can be used in systems for automatically controlling the level of liquid in a tank.

The purpose of the invention is to improve the accuracy and reliability of the controller.

Figure 1 is a schematic diagram of a fluid level controller; Figures 2 and 3 show the principle of maintaining a constant level. , - -.

On the supply tank 1, the housing 2 is fixedly mounted with the level sensor 3 fixed on it, having a lever 4.

In the housing 2, a driving tank 5 is mounted with vertical movement and mounted on the springs 6 and screws 7, on which the stops 8 and 9 are fixed, while it is connected to the flow tank 1 by a flexible fluid supply pipe 11, on which the actuator is installed in the form of a membrane normally closed pneumatic controlled valve 12 associated with a level 3 sensor. .

The level sensor 3 is connected to the membrane valve 12 through an electro-pneumatic valve 13, which converts the electrical signal of the sensor into a pneumatic one. Power is supplied through switch 14. Drainage is made through valve 15.

The controller operates as follows .ZOM. ..; L.; -. .. ./. . ... ... .

At a normal liquid level in the supply tank 1 and the driving tank 5, the lever 4 of the level 3 sensor is switched to the lower position and does not touch the stops 8 and 9, its contacts are open and there is no signal at the output. The electro-pneumatic valve 13, without a signal, is closed and the pneumatic signal at its output is absent. The diaphragm valve 12, having no pneumatic signal at the input, is closed and liquid from the pipe 11, the reservoir 1 does not enter. When the liquid level in the supply tank 1 decreases, the level decreases: the liquid level in the supply tank 5 (by the principle of communicating vessels), the mass of liquid in the supply tank 5 decreases and it rises on the springs b until the lower stop 9 touches the lever 4 of the sensor 3 and further raising the lever 4 switches to the upper position and closes the contacts. An electrical signal is supplied to the electro-pneumatic valve 13, which is turned on and supplies compressed air to the membrane valve 12. The membrane valve 12 is opened and the liquid through the pipe 11 enters the tank 1. The level in the supply tank 1, and the investigator

but, in the setting tank 5, it rises, while under the influence of an increasing mass of liquid it sags on the springs 6 and starts up until the stop 8 is pressed

the lever 4 of the sensor 3 and switches it to the lower position, the contacts of the sensor 3 are opened, the electro-pneumatic valve 13 is de-energized, turns off the supply of compressed air to the membrane valve 12, connecting it to the atmosphere. The diaphragm valve 12 shuts off the fluid supply from the pipe 11 to the tank 1. At the next lowering of the liquid level in the supply tank 1, the cycle is repeated. In the process of repeating cycles, the liquid level in the tank 1 fluctuates by 0.3-0.5 mm, while the prototype level fluctuates by 15-30 mm, i.e. ten times more than the claimed controller.

Maintaining a constant level of this regulator is illustrated by the example of a household spring steelyard (Fig. 2). If the price of divisions on the steelyard between kilograms is 1 cm, and the height of the goods is also 1

see, then, sequentially hanging such weights on the steelyard, you can see that the upper edge of the weights will always be at the same level. The same thing happens with the tank filled with liquid (Fig.Z). For

of a given container, it is always possible to select a spring when, when filling the container with liquid or its flow rate, the level of this liquid will be constant, and the spring stiffness coefficient k will be straight

is proportional to the free surface of the liquid S ,, the density of this liquid p, the acceleration of gravity g and is determined by the formula

k S-p jj.

This formula is determined from the condition that the container is in equilibrium with the liquid and the spring force

 G F.. : ... .. -where G is the weight of the liquid (we neglect the weight of the container, since it is constant)

G Ah-S-pfl,

where V is the volume of fluid;

S is the free surface area;

p is the density of the liquid;

g is the acceleration of gravity;

Д - the height of the column of the poured liquid;

F Dh-k- according to Hooke's law;

Dx - the amount of compression of the spring; k is the stiffness coefficient of the spring, we equate

Ah-S p-g Ax-k.

But for the constancy of the level, it is necessary that the height of the column of the liquid to be added Ah equals the deflection (compression) of the spring Ah, i.e. Ah Ah.

Having reduced both sides of the equation by these quantities, we obtain

k.

T.O. this condition is necessary and sufficient to maintain a constant liquid level in the tank with high accuracy regardless of its flow rate. When setting the master capacitance to several springs, the stiffness coefficient k decreases by a factor of n, where n is the number of springs.

When using the proposed device, the accuracy of regulation is improved by eliminating the sticking of liquid on the sensor elements and the reliability of the regulator by eliminating the destruction of the sensor due to corrosion. This regulator is used in the complex for cleaning the dust and gas mixture of an asphalt mixing plant and allows to increase the reliability and reliability of the entire installation.

Claims (1)

The claims A liquid level regulator comprising a master tank installed with the possibility of vertical movement in communication with the supply tank, a level sensor associated with an actuator mounted on the working fluid supply pipe, characterized in that, in order to increase accuracy and reliability, it comprises a housing fixed to the supply container, in which a level sensor is fixed, the reference capacitance is mounted on the springs and has an emphasis fixed to it, in contact with a level sensor, moreover, the stiffness coefficient of the springs is determined by the formula V-s-r-d . - .-. Js f  -n where k is the stiffness coefficient of the spring; S is the free surface area of the liquid in the master tank; p is the density of the fluid; g is the acceleration of gravity; p is the number of springs.