A fan control device for heat dissipation of LED screen

Abstract

The present invention discloses a fan control device for heat dissipation of an LED screen, comprising a thermostat, intermediate relays KA1 and KA2, a time controller KG, an ultraviolet sensor UV, a negative temperature coefficient thermistor Rt2, and fan motors FS1 and FS2. During the day, as sunlight irradiates and the temperature rises, the speeds of the fan motors FS1 and FS2 are adjusted by the changes in the resistance values ​​of the ultraviolet sensor UV and the negative temperature coefficient thermistor Rt2. When the temperature reaches the threshold value set by the thermostat, the fan motors FS1 and FS2 are operated at full power to quickly cool down the LED screen. Then, at night, due to the lack of sunlight, the speeds of the fan motors FS1 and FS2 are only affected by the changes in the resistance value of the negative temperature coefficient thermistor Rt2 through the connection of the time controller KG. The speed of the heat dissipation fan can be adjusted by the changes in the ultraviolet intensity and / or the internal temperature value at different time periods, thereby not only ensuring the timely heat dissipation effect of the LED screen, but also effectively extending the service life of the fan motor.

Description

Technical Field

[0001] The invention relates to a heat dissipation fan control device, in particular to a fan control device used for heat dissipation of an LED screen. Background Art

[0002] At present, most outdoor electronic billboards are LED screens. Since the LED screens of electronic billboards need to display different contents 24 hours a day, they generate a lot of heat. In order to control the temperature, existing billboards use fans to dissipate heat. After the LED screen is turned on, the cooling fan starts to work at a constant speed until the LED screen is turned off. However, the motor of the cooling fan will continue to heat up due to the long-term operation of the cooling fan, which is very likely to cause the motor to burn out. In order to reduce the working time of the cooling fan, a temperature sensor is currently set in the electronic billboard, and a temperature threshold is pre-set. After the LED screen is lit, the internal temperature value is detected by the temperature sensor. If the temperature value does not exceed the temperature threshold, the cooling fan does not work at this time. When the detected temperature value exceeds the set temperature threshold, the power is turned on to make the cooling fan work at a constant wind speed for heat dissipation. When the detected temperature is lower than the threshold again, the power is disconnected to stop the cooling fan immediately. Although this method eliminates the need for the cooling fan motor to work continuously for a long time, since it only controls the start and stop of the cooling fan by the temperature threshold, it will not only cause the fan to stop and start suddenly, which is not conducive to protecting the fan; but it also needs to wait until the internal temperature exceeds the temperature threshold before taking cooling measures, resulting in the inability to cool it down in time during the internal temperature rise process, and has a large hysteresis. Summary of the invention

[0003] In view of the problems existing in the above-mentioned prior art, the present invention provides a fan control device for LED screen heat dissipation, which can adjust the speed of the cooling fan according to the changes in ultraviolet intensity and / or internal temperature values ​​at different time periods, thereby not only ensuring timely heat dissipation of the LED screen, but also effectively extending the service life of the fan motor.

[0004] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a fan control device for heat dissipation of an LED screen, comprising a thermostat, an intermediate relay KA1, an intermediate relay KA2, a time controller KG, an ultraviolet sensor UV, a negative temperature coefficient thermistor Rt2, a fan motor FS1 and a fan motor FS2, the thermostat, the intermediate relay KA1, the intermediate relay KA2, the time controller KG, the negative temperature coefficient thermistor Rt2, the fan motor FS1 and the fan motor FS2 are all in a shell, and the ultraviolet sensor UV is fixed on the outer surface of the shell;

[0005] The two ends of the temperature sensor Rt1 in the thermostat are respectively connected to the positive and negative electrodes of the DC power supply, one end of the electric control switch S in the thermostat is connected to the positive electrode of the DC power supply, and the other end of the electric control switch S is connected in series with the electromagnetic coil of the intermediate relay KA1 and then connected to the negative electrode of the DC power supply;

[0006] One end of the time controller KG is connected to the positive pole of the DC power supply, and the other end of the time controller KG is connected in series with the electromagnetic coil of the intermediate relay KA2 and then connected to the negative pole of the DC power supply;

[0007] One end of the normally closed contact KA1-1 of the intermediate relay KA1 is connected to the positive electrode of the DC power supply, and the other end of the normally closed contact KA1-1 is connected in series with the ultraviolet sensor UV, the negative temperature coefficient thermistor Rt2 and the fan motor FS1, and then connected to the negative electrode of the DC power supply, and the fan motor FS2 is connected in parallel to both ends of the fan motor FS1;

[0008] The two ends of the normally open contact KA2-1 of the intermediate relay KA2 are connected in parallel to the two ends of the series circuit of the normally closed contact KA1-1 and the ultraviolet sensor UV, and the two ends of the normally open contact KA1-2 of the intermediate relay KA1 are connected in parallel to the two ends of the series circuit of the normally closed contact KA1-1, the ultraviolet sensor UV and the negative temperature coefficient thermistor Rt2.

[0009] Furthermore, a leakage protection switch QF is included, which is connected in series to the circuit between the positive pole of the DC power supply and the normally closed contact KA1-1. The leakage protection switch QF is added to protect the safety of the entire circuit.

[0010] Furthermore, the voltage of the DC power supply is 24V.

[0011] Compared with the prior art, the present invention adopts a combination of a thermostat, an intermediate relay KA1, an intermediate relay KA2, a time controller KG, an ultraviolet sensor UV, a negative temperature coefficient thermistor Rt2, a fan motor FS1 and a fan motor FS2. During the day, as the sunlight irradiates and the temperature rises, the speed of the fan motor FS1 and the fan motor FS2 is adjusted by the change of the resistance of the ultraviolet sensor UV and the negative temperature coefficient thermistor Rt2. When the temperature reaches the threshold set by the thermostat, the fan motor FS1 and the fan motor FS2 are operated at full power to quickly cool down the LED screen. Then, at night, due to the lack of sunlight, the speed of the fan motor FS1 and the fan motor FS2 is only affected by the change of the resistance of the negative temperature coefficient thermistor Rt2 through the connection of the time controller KG. There is no motor emergency stop or emergency start in the whole process, ensuring the running stability of the fan motor. Therefore, the present invention can adjust the speed of the cooling fan by the change of the ultraviolet intensity and / or the internal temperature value at different time periods, thereby not only ensuring the timely heat dissipation effect of the LED screen, but also effectively extending the service life of the fan motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a circuit schematic diagram of the present invention;

[0013] Figure 2 It is a schematic diagram of the appearance after the present invention is installed.

[0014] In the figure: 1. housing, 2. ultraviolet sensor UV. DETAILED DESCRIPTION

[0015] The present invention will be further described below.

[0016] like Figure 1 and 2 As shown, the present invention includes a thermostat, an intermediate relay KA1, an intermediate relay KA2, a time controller KG, an ultraviolet sensor UV2, a negative temperature coefficient thermistor Rt2, a fan motor FS1 and a fan motor FS2, the thermostat, the intermediate relay KA1, the intermediate relay KA2, the time controller KG, the negative temperature coefficient thermistor Rt2, the fan motor FS1 and the fan motor FS2 are all in a housing 1, and the ultraviolet sensor UV2 is fixed on the outer surface of the housing 1;

[0017] The two ends of the temperature sensor Rt1 in the thermostat are respectively connected to the positive and negative electrodes of the DC power supply, one end of the electric control switch S in the thermostat is connected to the positive electrode of the DC power supply, and the other end of the electric control switch S is connected in series with the electromagnetic coil of the intermediate relay KA1 and then connected to the negative electrode of the DC power supply;

[0018] One end of the time controller KG is connected to the positive pole of the DC power supply, and the other end of the time controller KG is connected in series with the electromagnetic coil of the intermediate relay KA2 and then connected to the negative pole of the DC power supply;

[0019] One end of the normally closed contact KA1-1 of the intermediate relay KA1 is connected to the positive electrode of the DC power supply, and the other end of the normally closed contact KA1-1 is connected in series with the ultraviolet sensor UV2, the negative temperature coefficient thermistor Rt2 and the fan motor FS1, and then connected to the negative electrode of the DC power supply, and the fan motor FS2 is connected in parallel to both ends of the fan motor FS1;

[0020] The two ends of the normally open contact KA2-1 of the intermediate relay KA2 are connected in parallel to the two ends of the series circuit of the normally closed contact KA1-1 and the ultraviolet sensor UV, and the two ends of the normally open contact KA1-2 of the intermediate relay KA1 are connected in parallel to the two ends of the series circuit of the normally closed contact KA1-1, the ultraviolet sensor UV and the negative temperature coefficient thermistor Rt2.

[0021] Furthermore, it also includes a leakage protection switch QF, which is connected in series to the circuit between the positive pole of the DC power supply and the normally closed contact KA1-1.

[0022] Furthermore, the voltage of the DC power supply is 24V.

[0023] First, set the temperature threshold on the thermostat, and set its connection time period (i.e., night time period) on the time controller KG; when the cooling fan control starts during the day, close the leakage protection switch QF. At this time, the temperature sensor Rt1 of the thermostat detects the temperature inside the shell in real time. When the detected temperature does not reach the temperature threshold, the electric control switch S of the thermostat is in the disconnected state, the electromagnetic coil of the intermediate relay KA1 is not energized, and the time controller KG is in the disconnected state, the electromagnetic coil of the intermediate relay KA2 is not energized, and the normally closed contact KA1-1, the normally open contact KA1-2, and the normally open contact KA2-1 are all in the initial state. At this time, the DC power supply passes through the normally closed contact KA1-1 and the ultraviolet sensor UV and negative temperature coefficient thermistor Rt2 provide power for fan motor FS1 and fan motor FS2, and two cooling fans rotate to perform heat dissipation. The ultraviolet sensor UV detects the intensity of ultraviolet rays received by the shell in real time, and its resistance decreases as the intensity of ultraviolet rays received increases. At the same time, the negative temperature coefficient thermistor Rt2 detects the internal temperature of the shell in real time, and its resistance decreases as the internal temperature increases. Due to the decrease in the resistance of both, the current of fan motor FS1 and fan motor FS2 increases, thereby increasing the speed of fan motor FS1 and fan motor FS2 and improving the heat dissipation efficiency. In this way, when the sunlight shines on the LED screen from weak to strong during the day, the speed of the cooling fan also changes from slow to fast.

[0024] Then, as the temperature continues to rise during the day, when the internal temperature value detected by the temperature sensor Rt1 reaches the set temperature threshold, the thermostat closes its electric control switch S, and then the electromagnetic coil of the intermediate relay KA1 is energized, causing the normally closed contact KA1-1 to open and the normally open contact KA1-2 to close. At this time, the power supply directly supplies power to the fan motor FS1 and the fan motor FS2 through the closed normally open contact KA1-2. The resistance changes of the ultraviolet sensor UV and the negative temperature coefficient thermistor Rt2 will not affect the speed of the fan motor FS1 and the fan motor FS2. The fan motor FS1 and the fan motor FS2 It is in full power output, and the temperature inside the shell is quickly cooled down; when the internal temperature is lower than the temperature threshold, the electric control switch S of the thermostat returns to the disconnected state, and the electromagnetic coil of the intermediate relay KA1 loses power, so that the normally closed contact KA1-1 is closed again and the normally open contact KA1-2 is disconnected again. At this time, the power supply is restored through the normally closed contact KA1-1, the ultraviolet sensor UV, and the negative temperature coefficient thermistor Rt2 to supply power to the fan motor FS1 and the fan motor FS2; the resistance changes of the ultraviolet sensor UV and the negative temperature coefficient thermistor Rt2 regulate the speed of the fan motor FS1 and the fan motor FS2;

[0025] When it enters night and reaches the connection time period set by the time controller KG, the time controller KG is in the connection state, so that the electromagnetic coil of the intermediate relay KA2 is energized, the normally open contact KA2-1 is closed, and the power is supplied to the fan motor FS1 and the fan motor FS2 through the closed normally open contact KA2-1 and the negative temperature coefficient thermistor Rt2; since there is no sunlight at night, there is no need to connect the ultraviolet sensor UV to the circuit. At this time, the speed of the fan motor FS1 and the fan motor FS2 is affected by the resistance change of the negative temperature coefficient thermistor Rt2; when the internal temperature reaches the set temperature threshold, the thermostat repeats the above process, so that the power is directly supplied to the fan motor FS1 and the fan motor FS2 through the closed normally open contact KA1-2, and the resistance change of the negative temperature coefficient thermistor Rt2 will not affect the speed of the fan motor FS1 and the fan motor FS2. The fan motor FS1 and the fan motor FS2 are at full power output, and the temperature inside the shell is quickly cooled down. When the connected time period of the time controller KG is exceeded (that is, after the night ends), the time controller KG returns to the disconnected state, causing the electromagnetic coil of the intermediate relay KA2 to lose power and enter the daytime state; this cycle is repeated.

Claims

1. A fan control device for LED screen heat dissipation, characterized in that: It includes a thermostat, an intermediate relay KA1, an intermediate relay KA2, a time controller KG, an ultraviolet sensor UV, a negative temperature coefficient thermistor Rt2, a fan motor FS1, a fan motor FS2 and a leakage protection switch QF. The thermostat, the intermediate relay KA1, the intermediate relay KA2, the time controller KG, the negative temperature coefficient thermistor Rt2, the fan motor FS1 and the fan motor FS2 are all in the shell, and the ultraviolet sensor UV is fixed on the outer surface of the shell; The two ends of the temperature sensor Rt1 in the thermostat are respectively connected to the positive and negative electrodes of the DC power supply, one end of the electric control switch S in the thermostat is connected to the positive electrode of the DC power supply, and the other end of the electric control switch S is connected in series with the electromagnetic coil of the intermediate relay KA1 and then connected to the negative electrode of the DC power supply; One end of the time controller KG is connected to the positive pole of the DC power supply, and the other end of the time controller KG is connected in series with the electromagnetic coil of the intermediate relay KA2 and then connected to the negative pole of the DC power supply; One end of the normally closed contact KA1-1 of the intermediate relay KA1 is connected to the positive electrode of the DC power supply, and the other end of the normally closed contact KA1-1 is connected in series with the ultraviolet sensor UV, the negative temperature coefficient thermistor Rt2 and the fan motor FS1, and then connected to the negative electrode of the DC power supply, and the fan motor FS2 is connected in parallel to both ends of the fan motor FS1; The two ends of the normally open contact KA2-1 of the intermediate relay KA2 are connected in parallel to the two ends of the series circuit of the normally closed contact KA1-1 and the ultraviolet sensor UV, and the two ends of the normally open contact KA1-2 of the intermediate relay KA1 are connected in parallel to the two ends of the series circuit of the normally closed contact KA1-1, the ultraviolet sensor UV and the negative temperature coefficient thermistor Rt2; the leakage protection switch QF is connected in series to the circuit between the positive pole of the DC power supply and the normally closed contact KA1-1; The voltage of the DC power supply is 24V.

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