Multi-channel device for signalling liquid levels

 

(57) Abstract:

Use: agricultural equipment and machinery. The inventive multi-channel device for signaling levels fluid sprayers machines fertilization and sprinkler machines signal from the reference oscillator is fed to buffer amplifier and then to the voltage Converter, in which the signal is rectified and supplies DC generators, each of which is associated with a corresponding liquid level sensor with a resistive temperature dependence. When the location of the sensor in the liquid, its resistance is high and the voltage across it is passed as a logical unit on the display unit. When the location of the sensor outside of the liquid can be heated flowing through it current, its resistance decreases, which is passed as a logical zero. 1 C. p. F.-ly, 6 ill.

The invention relates to agriculture, and engineering.

A device for signalling liquid level, comprising a bridge circuit, one arm of which included temperature sensor, and the output of this circuit is connected with the input of the operational amplifier. When such a device Balan is of the resistance of the sensor. However, the drawback in this case is to maintain the balance of the bridge, because the operation occurs in a wide range of temperature not only during the season, but during the day, in addition, the electronic circuit must be located near the bridge to eliminate the influence of the connection conductors. This makes the device unsuitable for use under field conditions and conditions with severe climatic tests.

The application of the known multi-contact devices is as unacceptable due to the fact that it is often necessary to measure the levels of dielectric liquids.

Closest to the invention is a multichannel device for signaling levels of the liquid containing the reference signal generator mounted on the holder to each other, the fluid-level sensor with a resistive temperature dependence, the first output of each of which is grounded, and the second output through an appropriate unit of comparison is associated with a multi-channel display unit. When working with this device sensors that are located below the liquid level, have a temperature different from the temperature sensors located outside of the fluid that is logged. However, in this text the opportunity to use the device only in case of large temperature differences within the fluid, but this leads to a drift of the so-called baseline reference. In addition, when changing climatic conditions this device has very low accuracy.

The aim of the invention is to improve the accuracy of the device, ensuring it is working in a wide range of ambient temperatures without changing the accuracy and the choice of the working point of the sensor in any given place their characteristics.

This is achieved in that the device is equipped with buffer amplifiers, connected in series, a voltage Converter, rectifier and DC, and the output of reference signal generator connected to the input of the first buffer amplifier, and output buffer amplifier through a voltage Converter connected with the rectifier, the output of which is connected to the inputs of DC generators and the output of each of which is associated with the second output of the corresponding liquid level sensor with a resistive temperature dependence.

In addition, each level sensor is made in the form of a silicon wafer, with the external side of the surrounded low-alloy oxide of silicon and further conductive glass, which strengthened the conclusions of the sensor, two; in Fig.2 installing the sensors, General view; Fig.3 mount the sensors of Fig.4 the dependence of the resistance of the sensors from the input power; Fig.5 the dependence of the resistance of the temperature sensors of Fig.6 sensor.

The device includes a Converter 1 voltage in the form of a push-pull power amplifier with pulse transformer 2, a full-wave rectifier 3 with the capacity of the filter 4, the generators 5 DC installation resistors 6 residual current in the circuit of the sensor 7 (sensor with a resistive temperature dependence) and such sensors can be arbitrarily, depending on the type of tasks.

The unit of comparison is the diodes protect the inputs chip 8 from exceeding the voltage from the sensors 7, the resistive voltage divider 9 and 10, the logic inverter 11, the electronic key 12. The display unit includes LEDs 13. But the indication unit can be made in the form of a sound signaling device having a diode adder 14, the electronic key 15 and the piezoelectric call 16.

The device also includes a buffer amplifier 17, the generator 18 reference signal, the protection elements 19 power 20. The actual sensors through parts 21 are mounted in months the effect on the sensors 7, checking the level in the tank 24 of any liquid 25. The active element 26 of the sensor 7 is fixed in the tubular holder 27 with the sealing compound 28 for fixing and insulating the connecting conductors, the sensor may also have a protective housing 29. The composition of the sensor 7 includes silicon oxide 30 low-alloy with an electrical contact with the pins 31, and the whole structure is enclosed in a protective glass case 32 in which pins 31 strengthened through the conductive glass. The layer of silicon oxide 30 together with crystalline silicon 34 and form the working sensor element 7.

The device operates as follows.

The output signal of the generator 18 through a buffer amplifier 17 receives the voltage Converter 1, straightened rectifier 3 and through DC generators 5 are fed to the sensor 7. The short circuit current sensor 7 is practically no different from working due to the inclusion in the circuit of DC generators 5 resistors 6. When the immersion of any of the sensors 7 in the liquid the level of which is registered, immersed sensors have a temperature close to the temperature of the controlled fluid, and the current from the generators 5 and resistor 6 creates these sensors corresponding inverters 11 a zero signal.

The absence of contact sensor 7 with a controlled fluid leads to its self-heating and the reduction of resistance in several times when the voltage at the second terminals of the sensors 7, outside the liquid. Through the divider 9,10 this is the voltage across the element 11 a logical inverter, is passed as a logical zero, which is then inverted to a logical unit. This leads to the opening of the respective keys 12 and the ignition of the respective lamps 13. Diode adder 14 in this issue a permit for the audio signal through the electronic key 15 on the call 16.

The use of this device allows for low-voltage on-Board power machines to receive the differential signals from the sensors to tens of volts, which simplifies the selection signals, moreover there is a choice of the working point of the sensor, for example when the individual configuration of each control as dielectric and negelecting liquids with a high degree of accuracy and the ability to reconfigure the device quickly to any type of liquid, excluding impact of changes in external temperature, because the whole system is adjusted on the overall level. The device is simple to operate, technoly FLUID, containing the reference signal generator mounted on the holder to each other, the fluid-level sensor with a resistive temperature dependence, the first output of each of which is grounded, and the second output through an appropriate unit of comparison is associated with a multi-channel display unit, characterized in that it is provided with a buffer amplifier, connected in series, a voltage Converter, rectifier and DC, and the output of reference signal generator connected to the input of the first buffer amplifier, and output buffer amplifier through a voltage Converter connected with the rectifier, the output of which is connected to the inputs of the DC generator and the output of each of which is associated with the second output of the corresponding liquid level sensor with a resistive temperature dependence.

2. The device under item 1, characterized in that each level sensor with a resistive temperature dependence is made in the form of a silicon wafer, with the outer side by a layer of low-alloy of silicon oxide and further conductive glass, which strengthened the conclusions of the sensor, the entire sensor is enclosed in a protective glass case.

 

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