CN111271311B - A kind of electric fan to prevent overcooling control device - Google Patents

Abstract

The invention discloses a control device for preventing overcooling of an electric fan. The current temperature-controlled electric fans do not take into account factors such as the increase in the speed of the electric fan caused by the increase of the grid voltage during the late-night valley electricity. The invention includes a metal disc arranged in the center of the front protective cover of the electric fan and facing the direction of the blades, and a heater and a temperature sensor are arranged in the metal disc. The heater is powered by a constant current source and heats the metal disc. The temperature sensor is connected to the drive circuit through the temperature measurement and comparison circuit, the drive circuit is connected to the relay, and the output contact of the relay is connected in series in the electric fan motor circuit. In the present invention, the wind blown by the electric fan blows directly on the disc in the center of the front grille. Too low room temperature and too high grid voltage will make the temperature of the disc drop, so it is judged whether to disconnect the electric fan motor to prevent people from getting cold. The invention is simple in structure and strong in practicability, as long as the output of the relay of the control device is connected to the motor in series, and the invention has wide applicability.

Description

A kind of electric fan to prevent overcooling control device

technical field

The invention belongs to the technical field of automatic control, and in particular relates to a control device for preventing overcooling of an electric fan.

Background technique

Electric fans have the characteristics of good mobility, high cost performance and low power consumption, and are widely used in homes and offices. However, if you blow an electric fan for a long time when you sleep at night, it is easy to catch a cold and get sick. To this end, some people have proposed a temperature-controlled electric fan, such as the invention patent CN201711181556.5, by measuring the room temperature to control the speed of the electric fan or its switch state, so as to avoid the electric fan still running at high speed after the room temperature drops at night, which will cause people to catch cold. However, the reason why it is easy to catch cold by blowing an electric fan for a long time at night is not only the factor that the speed of the electric fan does not decrease accordingly after the room temperature is lowered, but also the increase of the speed of the electric fan caused by the increase of the grid voltage at night is also an important factor. Due to the high power load of the power grid during peak power periods, the voltage of the user's indoor line is often seriously low when the electric fan is used at night, so the wind speed gear setting of the electric fan is generally higher. When the power consumption is low in the middle of the night, the voltage in the user's room is often high, which leads to an increase in the speed of the electric fan. Therefore, in addition to lowering the room temperature in the middle of the night, the reason why blowing an electric fan at night causes the human body to catch a cold must also consider the factor that the grid voltage increases during the late-night valley electricity. However, none of the temperature-controlled electric fans proposed so far has taken into account the factor that the increase in the speed of the electric fan caused by the increase of the grid voltage during the late-night valley electricity period.

SUMMARY OF THE INVENTION

The purpose of the present invention is to aim at the deficiencies of the prior art, and to provide a control device for preventing overcooling of electric fans, which can not only prevent people from getting cold due to the fact that the room temperature is too low at night but the fan speed does not drop, but also prevent the fan from being caused by too high power grid voltage in the middle of the night. Excessive speed can cause people to catch cold.

The invention includes a metal disc arranged in the center of the front protective cover of the electric fan and facing the direction of the blades. The metal disc is provided with an installation hole, and the installation hole is provided with a heater and a temperature sensor.

The heater is powered by a constant current source to heat the metal disc.

The signal output end of the temperature sensor is connected to the signal input end of the temperature measurement and comparison circuit, the signal output end of the temperature measurement and comparison circuit is connected to the signal input end of the drive circuit, the signal output end of the drive circuit is connected to the input end of the relay, and the relay The output contacts are connected in series in the electric fan motor circuit.

One end of the DC power supply circuit is the power connection end, and the other end is connected to the constant current source, the temperature measurement and comparison circuit, and the driving circuit, respectively, to supply power for the constant current source, the temperature measurement and comparison circuit, and the driving circuit.

Further, the relay is a normally closed contact type relay.

The beneficial effects of the present invention include:

1. The present invention does not simply measure the room temperature to control the electric fan, but indirectly controls the temperature change of the metal disc blown by the wind blown by the electric fan. Because the temperature of the metal disc is measured under the action of the wind flow of the electric fan blade, it can better reflect the actual temperature felt by the human body than measuring the room temperature in other locations.

2. The present invention does not only measure the change of room temperature, but also considers the change of the fan speed caused by the change of the grid voltage, so as to avoid the problem that the room temperature does not change much, but the high speed of the grid voltage causes the personnel to catch cold.

3. In the present invention, the temperature sensor is placed inside the metal disc, and the metal heat capacity is large to prevent short-term room temperature changes or short-term grid voltage changes from falsely triggering the control circuit to work, to avoid frequent switching on or off of the electric fan motor current, and to improve Human comfort.

4. The present invention does not change the original control circuit of the fan, but only needs to connect the output of the relay of the control device to the motor in series, and has wide applicability.

Description of drawings

Fig. 1 is the structural representation of the present invention;

FIG. 2 is a schematic circuit diagram of the present invention.

Detailed ways

As shown in FIG. 1, a control device for preventing overcooling of an electric fan includes a metal disc 1 arranged in the center of the front protective cover of the electric fan and facing the direction of the blades. The metal disc 1 is provided with an installation hole, and the installation hole A heater 2 and a temperature sensor 3 are provided.

As shown in FIG. 2 , the heater 2 is powered by a constant current source 4 to heat the metal disc 1 .

The signal output end of the temperature sensor 3 is connected to the signal input end of the temperature measurement and comparison circuit 5, the signal output end of the temperature measurement and comparison circuit 5 is connected to the signal input end of the drive circuit 6, and the signal output end of the drive circuit 6 is connected to the input of the relay 7 terminal, the output contact of the relay 7 is connected in series in the electric fan motor circuit. One end of the DC power supply circuit 8 is the power connection terminal, which is connected to the commercial power in use, and the other end is respectively connected to the constant current source 4, the temperature measurement and comparison circuit 5, and the drive circuit 6, which are the constant current source 4, the temperature measurement and comparison circuit 5, The drive circuit 6 is powered.

The temperature sensor 3 measures the temperature of the metal disc, and the temperature measurement and comparison circuit 5 compares the measured temperature with the preset temperature, and controls the drive circuit 6 to output the relay drive current according to the comparison result, and controls the relay 7 to open and close. The output of the relay 7 is connected in series in the electric fan motor circuit to control the on-off of the motor current, thereby controlling the switch of the electric fan.

The electric fan motor circuit mainly includes a motor control circuit 9 and an electric fan motor 10 (the part inside the dashed frame in the figure), and the existing electric fan technology is unchanged.

The relay 7 adopts a normally closed contact type relay, and the temperature measurement and comparison circuit 5, the drive circuit 6, and the DC power supply circuit 8 are all mature prior art. Adjust the switch mode of the electric fan. The specific working method is:

When the electric fan motor is working, if the measured temperature is higher than the set temperature, the temperature comparison circuit will not output the signal, the drive circuit will not output the drive current, the coil of the normally closed contact relay does not flow through the coil, the contact is closed, and the electric The fan works under the original control circuit. On the contrary, if the measured temperature is lower than the set temperature, the temperature comparison circuit outputs the drive current, the contact of the normally closed contact relay is disconnected, the electric fan motor is disconnected, and the electric fan fan stops rotating, so as to avoid the person being blown from catching a cold. .

The specific working principle is: when the electric fan is working, the heater heats the metal disc under the set current, and the setting of the heating current should make the temperature of the metal disc 5-10 degrees higher than the room temperature at that time (set according to needs). When the room temperature and the rotational speed of the electric fan remain unchanged, the temperature of the metal disc also remains unchanged, the controller does not work, the contact of the output relay is normally closed, and the electric fan operates in the normal mode.

Case 1. When the room temperature drops, since the current through the heater is provided by the constant current source and does not change, the drop in room temperature will cause the temperature of the metal disc to drop. After the temperature measurement and comparison circuit determines, the drive circuit outputs the drive current and controls it. The relay contacts are opened, the fan motor current is cut off, and the fan blades stop. After the fan stops, the temperature of the metal disc slowly rises as the room temperature rises. When the temperature of the metal disc rises above the set value, the drive circuit no longer outputs the drive current, the control relay contacts are closed, the fan motor current is turned on, and the fan blades rotate again. The above adjustment process is carried out continuously, so as to avoid the person being blown cold when the room temperature is too low.

Case 2. When the grid voltage rises during the late-night valley electricity, the heating power does not change because the current through the heater is constant current, but due to the increase in the speed of the electric fan blades, the increase in the grid voltage will cause the metal circle When the temperature of the disk drops, the temperature measurement and comparison circuit controls the output of the drive circuit and the control relay contact is disconnected, the current of the fan motor is cut off, the fan blades stop, and the temperature of the metal disk slowly rises. When the temperature of the metal disc rises above the set value, the temperature comparison circuit stops outputting current, the control relay contacts are closed, the fan motor current is turned on, and the fan blades rotate again. The above adjustment process is carried out continuously to avoid people who are blown cold when the grid voltage is too high.

Case 3. The room temperature drops and the grid voltage rises at the same time. Since the current passing through the heater does not change, both the drop in room temperature and the rise in grid voltage will cause the temperature of the metal disc to drop. After the temperature measurement and comparison circuit judges, the output current of the drive circuit will control the relay contact to disconnect, and the fan will be disconnected. The motor current is cut off, the fan blades stop, and the temperature of the metal disc rises. When the temperature of the metal disc rises above the set value, the drive circuit stops outputting the drive current, the relay contacts are closed, the fan motor current is turned on, and the fan blades rotate again. The above adjustment process is continued to prevent the temperature of the metal disc from being too low to cause the person being blown to get cold.

Claims (2)

1. The utility model provides an electric fan prevents cold controlling means which characterized in that:

the electric fan comprises a metal disc (1) which is arranged in the center of a front protective cover of the electric fan and faces to the direction of a blade, wherein a mounting hole is formed in the metal disc (1), and a heater (2) and a temperature sensor (3) are arranged in the mounting hole;

the heater (2) is powered by a constant current source (4) and heats the metal disc (1);

the signal output end of the temperature sensor (3) is connected with the signal input end of the temperature measuring and comparing circuit (5), the signal output end of the temperature measuring and comparing circuit (5) is connected with the signal input end of the driving circuit (6), the signal output end of the driving circuit (6) is connected with the input end of the relay (7), and the output contact of the relay (7) is connected in series in the motor loop of the electric fan;

one end of the direct current power supply circuit (8) is a power connection end, and the other end of the direct current power supply circuit is respectively connected with the constant current source (4), the temperature measurement and comparison circuit (5) and the driving circuit (6) to supply power for the constant current source (4), the temperature measurement and comparison circuit (5) and the driving circuit (6).

2. The control device for preventing the electric fan from being too cold as claimed in claim 1, wherein: the relay (7) is a normally closed contact type relay.

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