SU1584026A1 - Device for protecting of air-cooled apparatus from overheating - Google Patents

Abstract

The invention relates to the field of electrical engineering, in particular, to technological protection devices, and can be used to protect devices with forced air cooling from overheating when cooling conditions are disturbed. The purpose of the invention is to increase the reliability of protection by providing control over the entire range of changes in air flow, adjusting the value of this range and expanding the scope of application by providing protection to additional nodes. To do this, use sensor 1 of a monitored parameter, made in the form of an anemometer with a frequency output and a generator of 2 pulses connected to counter 3, which through parallel register 4 is connected to the address input of multiplexer 5, the corresponding analog inputs of which are connected to switch 7 , zero 8 and negative 9 threshold voltage. The output of multiplexer 5 is connected with isolating diodes 10 and 11. With a sharp increase in air flow, the frequency of clock pulses from sensor 1 increases and counter 3 sets multiplexer 5 to channels whose inputs are connected by switch 6 to negative threshold voltage source 9. At the output of multiplexer 5, a negative voltage appears, and through the decoupling diode 10 a signal is received to turn off the power supply circuit of the fan. At the same time, the power supply circuit of the protected device is disconnected, since a positive signal does not go through the decoupling diode 11. At a lower predetermined flow rate of air at the output of multiplexer 5, a zero voltage appears from a zero threshold voltage source and the protected device turns off. 1 hp f-ly, 1 ill.

Description

in -Kh

The invention relates to electrical engineering, in particular, to technological protection devices, and can be used to protect apparatus with forced air cooling from overheating in the event of a cooling failure.

The purpose of the invention is to increase the reliability of protection by ensuring the control of the entire range of changes in air flow, adjusting the magnitude of this range and expanding the scope by ensuring the protection of additional nodes.

The drawing shows a device for protection against overheating of air-cooled apparatuses.

The device contains a sensor 1 of a monitored parameter, made in the form of an anemometer with a frequency output for installation in air-cooled systems, a generator of 2 pulses connected respectively to the installation and counting inputs of the counter 3 of the counting, connected to the parallel register 4, which is connected to the address input of the multiplexer 5, the corresponding analog inputs of which through the switch 6 are connected to the outputs of sources 7–9 positive (IPPN), zero (INN) and negative threshold voltage, and output tipleksora 5 is connected to the cathode decoupling diode 10 and the anode decoupling diode 1 January.

The device works as follows.

Sensor 1 of the monitored parameter is an anemometer, on the axis of which a leaf is placed, interrupting the flux of radiation (for example, the flux of infrared radiation from the LED) during rotation of the impeller -. As a result, a current pulse is formed at the output of the photodiode, transformed by using the NAND inverters and the differential circuit into a positive pulse 1, which arrives at the installation input R of the counter 3 and sets the counter 3 to O. B is the period between two pulses of the sensor 1 and the counter 3 filled with pulses from the output of the generator 2.

On the binary outputs of counter 3, a binary number 2 code appears, corresponding to the number of 2 pulses received from the generator. This code

0

five

0

five

0

five

0

five

0

five

is fed to the input of the parallel register 4S which records it at the command of the pulse arriving at the clock input from sensor 1, and transmits throughout the period to the address input of the multiplexer 5, which connects its output, which is the main output of the device, to the analog input of the corresponding channel - mouth. Depending on the mode of operation, one or several analog inputs of multiplexer 5 are connected by switch 6 to the output of the MTP 7, and the rest are connected to the output of the TIN 8 or to the output of the source 9 of a negative threshold voltage. The voltage from the output of multiplexer 5 through the isolating diodes 10 or 11 is fed to the first or second additional outputs of the device.

For example, at the minimum specified air flow rate and with the measuring sensor 1, the input of the counter 3 from the generator 2 enters for a period of five pulses. The corresponding combination is written into a parallel register 4 and sets multiplexer 5 to the fifth channel, to the analog input of which the output 6 of the ICPN 7 is connected. From the output of multiplexer 5, the positive voltage goes to the amplifier input of the relay unit and closes the power circuits of the protected device, allowing its operation .

At the device output, a signal appears at a predetermined predetermined number of pulses (in this example, with five), corresponding to a specific air flow.

A change in the air flow rate greater or less than this flow rate causes the number of pulses to be more or less than five on the counter. Instead of positive voltage from IPPN 7, the input of multiplexer 5 receives a zero voltage in the TIN 8 and the relay unit shuts off the power circuits of the protected device, prohibiting its operation.

In real devices there are no absolutely identical products, so the air flow supplied for cooling varies in the range where the lower limit is determined by the design of the radiator and the heat load, and the upper limit depends on the variation of the radiator parameters and the power of the fan.

51

In the device, switch 6 does not have one but several serial analog outputs of multiplexer 5, which cover the whole range of cooling air flow, connected to the output of the IIPN 7.

Setting up the device at the limit of protection operation is carried out by changing the generator frequency in accordance with the equation

T / 2 2P / f,

where f is the frequency of the generator 2 pulses J

n is the number of binary bits of counter 3 of sensor 1; T - the period of the pulse

from the output of the sensor 1. When the fan is operated for a certain load, its parameters (in particular, the flow rate) are within certain limits4: and any disturbance in the cooling system leads to a change in these parameters.

Clogged tract leads to a reduction in flow through the load, and the separation of the tract causes either a decrease in flow or an increase depending on the location of the violation and the location of the device.

With a sharp increase in air flow, the frequency of the clock pulses from sensor 1 increases and the counter sets multiplexer 5 to the channels whose inputs are connected by switch 6 to source 9 of negative threshold voltage. At the output of multiplexer 5, a negative voltage appears, which through decoupling diode 10 goes to the first additional output of the device and then to the amplifier of the contactors block and disconnects the power supply circuit of the fan.

At the same time, q thereby turns off the power supply circuit of the device being protected, since the positive voltage across the bus driver 7 does not pass through the output diode 11 to the second additional output of the device.

The proposed technical solution makes it possible, in contrast to the well-known ones, not only to significantly expand the range of settings, the range of measurements of parameters, to improve the accuracy of the infusion, but also to reduce the size, weight, and improve the manufacturability of the performance.

five

Such capabilities greatly expand the functions of the device with a slight increase in energy costs.

Thus, the use of introduced features in a sentence provides, during its operation, the creation of a higher socially, Q useful result.

An additional advantage of the proposed device is the expansion of its technological capabilities. In comparison with analogues, jc which can be placed in the cooling path only after the object being cooled, the proposed device can be placed anywhere. Since it reacts to any violation of the cooling mode of the object, it records the reduction in consumption of the norm knife or an increase above the norm and includes the protection of the apparatus.

Claims (2)

25 claims 1, Device for protection against overheating of air-cooled apparatuses, containing sensor monitored This parameter is connected to the installation input of the counter, the counting input of which is connected to the output of the pulse generator, characterized in that, in order to increase reliability and expand the scope, the sensor of the monitored parameter is designed as an anemometer with a frequency output for installation in air systems cooling, the output of which is connected to the clock input of the entered parallel register, the inputs of which are connected to the corresponding outputs of the counter, the outputs of the parallel register ra connected to respective input terminals of address multiplexer inputted corresponding to the analog inputs of which are inputted through the switch connected to the outputs the input sources of positive, zero, and negative threshold voltages, the multiplexer output is the main output of the device. 2. The device according to claim 1, characterized in that, in order to expand the field of use by providing protection for additional nodes, the cathode of the first and the anode are second. The horned driving diodes fru and the cathode of the second diode are interconnected and connected respectively to the first and second additions to the multiplexer output, the anode to the primary outputs of the device.