JPH083198Y2 - Fan motor controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Purpose of the Invention [Field of Industrial Application] The present invention relates to a fan motor controller, and more particularly to a fan motor controller that controls the speed of the fan motor according to temperature.

[Prior art]

Cooling fan motors are often used to remove the internal heat of electronic devices and increase the reliability of the electronic devices. The actual usage of this cooling fan motor is that the power switch of the mounted electronic device is ON. At the same time, the fan motor is also driven so that the fan 9 is always driven at a high speed, and the temperature inside the electronic device 8 is detected by the sensor 9 as shown in JP-A-58-129524 and FIG. When a certain temperature is reached, the fan motor is passed through the amplifier 10 and control circuit 11.
There is also a configuration in which the fan motor 12 is started when 12 is started to start cooling the equipment and when another set temperature is reached.

[Problems to be solved by the device]

In the actual usage of the cooling fan motor in the conventional technology, the fan motor with a simple structure in which the power switch is turned on and the fan motor is always driven at high speed always drives the fan motor, so power is wasted and noise of the fan motor is generated. Are scattered in the office, which causes discomfort in the office.

Further, the structure shown in FIG. 6 that detects the temperature inside the electronic device, starts the fan motor when a certain temperature is reached, starts cooling, and stops the fan motor when a separately set temperature is reached, Although the power consumption can be suppressed to some extent, since the fan motor control is ON / OFF control, the start and stop of the fan motor is constantly repeated, and the noise at the start of the fan motor increases conversely, which increases the noise in the office. There is an inconvenience that the discomfort is not sufficiently reduced.

(2) Configuration of the Invention [Means for Solving the Problems] A fan motor control device of the present invention is a device for controlling the speed of a fan motor by the output of a temperature detection device, and an operational amplifier that operates at a power supply voltage. , The output of a sawtooth wave oscillator composed of a resistor and a capacitor inserted on the input side and the output side of the operational amplifier is connected to one input terminal of the comparison amplifier, and to the other input terminal of the comparison amplifier, A reference voltage obtained by dividing the power supply voltage by a resistance and a temperature-sensitive resistor having a negative temperature coefficient is added, a Zener diode is connected in parallel to the temperature-sensitive resistor, and the Zener voltage of this Zener diode is converted to the sawtooth wave. Below the maximum value of the oscillator output,
The output of the comparison amplifier is amplified to supply power to the fan motor so that the duty ratio of the output of the comparison amplifier increases when the ambient temperature rises and decreases when the ambient temperature decreases, and the duty ratio decreases below a certain temperature. Is maintained at some value greater than zero.

[Action]

In the fan motor control device of the present invention, the output of the sawtooth wave oscillator driven by the power supply voltage and the reference voltage obtained by dividing the power supply voltage by the resistance and the temperature sensitive resistor are compared by the comparison amplifier, The voltage difference between the output voltage of the sawtooth wave oscillator and the comparison voltage becomes the output of the comparison amplifier, and the voltage proportional to the output is supplied to the fan motor, and the fan motor rotates.

The reference voltage changes according to the resistance value of the temperature sensitive resistor, and its value decreases as the temperature rises.Therefore, when the temperature rises, the output voltage of the comparison amplifier increases and the speed of the fan motor increases. Then, the fan motor is driven at a speed that is substantially proportional to the temperature, and the change in speed stops in a region exceeding a certain temperature range, and is fixed at a substantially constant speed.

[Example of device]

 An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit diagram of a control device according to the present invention. In this example, a power supply voltage V is applied to a + input terminal of an operational amplifier A-1 by a resistor R ₁
And it gives a reference voltage obtained by dividing by R _2, a feedback resistor R ₄ between said input terminal and an output terminal, also - to connect a resistor R ₅ between the input terminal and the output terminal, the - input terminal A sawtooth wave oscillator is formed by connecting a capacitor C ₁ between the ground and the ground, the output of the sawtooth wave oscillator is added to the-input terminal of the comparison amplifier A-2, and the + terminal of the comparison amplifier A-2 is connected. Resistance to power supply voltage V
The reference voltage shown in FIG. 2 obtained by dividing the temperature-sensitive resistor R ₇ having a negative temperature coefficient with R ₆ and having the zener diode D _Z connected in parallel is added to the comparator amplifier A-2. The output is amplified via the transistors TR ₁ , TR ₂ and TR ₃ , smoothed via a smoothing circuit composed of a choke coil L and a capacitor C ₂ , and supplied to a fan motor.

The operation of the controller of FIG. 1 according to the present invention will be described in detail below. In the sawtooth wave oscillator composed of the operational amplifier A-1, the resistors R _{1 to} R ₅ and the capacitor C ₁ , the capacitor C ₁ is charged and its terminal voltage is the voltage Vh at the + side terminal of the operational amplifier A-1. Becomes equal to, the voltage of the-side terminal of the operational amplifier A-1 connected to the capacitor C ₁ also becomes Vh and the capacitor
The electric charge of C ₁ is discharged through the resistor R ₅ and the operational amplifier A-1,
When the terminal voltage of the capacitor C ₁ reaches Vl, discharging is stopped and charging is started again. The terminal voltage of the capacitor C ₁ is the second
It changes in a sawtooth shape as shown in the figure, and its high potential is Vh,
The low potential is Vl.

Vh and Vl are equivalently set by the resistors R _{1 to} R ₄ , and the relationship between the voltage and the resistor is determined by the following equation.

The negative side input terminal of the comparison amplifier A-2 has the above-mentioned capacitor
The voltage of C ₁ is applied, and the reference voltage obtained by dividing the power supply voltage by the resistor R ₆ and the temperature sensitive resistor R ₇ is applied to the + terminal of the comparison amplifier A-2. When the voltage of the negative terminal of 2, that is, the voltage of the capacitor C ₁ exceeds the reference voltage, an output is generated in the comparison amplifier A-2 in the range of the voltage above the reference voltage, and the fan is generated via the transistors TR ₁ to TR _3. Rotate the motor.

The value of the reference voltage varies with temperature inside of the electronic apparatus is temperature-sensitive resistor R ₇ is detected, the temperature-sensitive resistor R ₇ is the temperature in the electronic apparatus is high because it has a negative temperature coefficient Since the resistance value of the temperature-sensitive resistor R ₇ becomes low and the reference voltage becomes low, an output is generated in the comparison amplifier A-2 at a low value of the voltage of the capacitor C ₁ which is the input voltage of the comparison amplifier A-2, and the voltage generation range. Becomes wider, a large output voltage is generated and the fan motor is rotated at a higher speed. On the contrary, when the temperature inside the electronic device becomes low, the resistance value of the temperature-sensitive resistor R ₇ becomes high and the reference voltage becomes high.
When the voltage of C ₁ is high, the output is generated in the comparison amplifier A-2,
Therefore, the generated voltage is lowered and the rotation speed of the fan motor is reduced.

Therefore, Vh should be set so that the reference voltage is between Vh and Vl, which is the voltage range of the input voltage of the comparison amplifier shown in FIG.
By selecting the temperature-resistance characteristics of Vl and the temperature-sensitive resistor R ₇ , the fan motor can be rotated at a speed that approximately corresponds to the temperature inside the electronic device. Further, as shown in FIG. 3, if the value of the reference voltage at the highest temperature is set to a value lower than Vl, such as', at a temperature above the temperature at which the reference voltage becomes lower than Vl, the function of the comparison amplifier stops and the output becomes maximum. Fixed to the value, the fan motor rotates at high speed. Also, if the reference voltage value at the lowest temperature is set to a value higher than Vh, such as ", the temperature of the reference voltage becomes higher than Vh. The temperature of the reference amplifier stops and the output of the comparison amplifier does not occur. However, in the present invention, in order to prevent the fan motor from stopping at this low temperature, the zener voltage of the zener diode D _Z connected in parallel with the temperature sensing resistor R ₇ is used in the comparison amplifier A in this invention. -2 is set to a value lower than the maximum value Vh of the input voltage.As a result, as shown in Fig. 4, the value of the reference voltage "does not exceed this Zener voltage, so no matter how low the internal temperature of the electronic device becomes, An output voltage corresponding to the Zener voltage is generated, and the fan motor starts rotating at a very constant speed.

FIG. 5 is a characteristic diagram when the fan motor is rotationally driven by the control device according to the present invention, and shows the relationship between the temperature of the temperature-sensitive resistance portion and the rotational speed of the fan motor.

Curve A is the Zener diode D _Z in the circuit of FIG.
In case of not using, the rotation speed is saturated at a temperature of about 70 degrees, and it has stopped from 500 rotations at about 20 degrees.

Curve B shows the case of using the Zener diode D _{Z. The} curve where the rotation speed is saturated at a temperature of about 70 degrees is the same as curve A, but about 500 rotations are maintained even at temperatures below 20 degrees. The effect of a Zener diode connected in parallel with the temperature-sensitive resistor appears.

[Effect of device]

The present invention provides a sawtooth wave voltage which is an output of a sawtooth wave oscillator composed of an operational amplifier which operates at a power supply voltage as described above, and a resistor and a capacitor which are interposed between an input and an output of the operational amplifier. Has a resistance and a negative temperature coefficient, and the zener diode is connected in parallel.The output is generated only when it exceeds the reference voltage obtained by dividing the power supply voltage with the temperature-sensitive resistance. As a result of the reference voltage changing corresponding to the temperature detected by the temperature sensitive resistance, the output voltage changes corresponding to the temperature, the speed of the fan motor changes corresponding to the temperature, and the electronic device can be cooled efficiently. Noise can be reduced regardless of temperature by setting the saturation value of the maximum speed and the minimum speed, and the fan motor rotation can be maintained above the minimum speed limit value, so a stable cooling fan motor control device can be obtained. It is possible.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a fan motor control device of the present invention, FIGS. 2 to 4 are comparison diagrams of the sawtooth wave voltage and a reference voltage of a comparison amplifier, and FIG. 5 is a control device of the present invention. FIG. 6 is a characteristic diagram showing the operating characteristic of the operated fan motor, and FIG. 6 is an explanatory diagram of a fan motor control device according to the prior art. R _{1 to} R ₁₄ ...... Resistance, A-1 ...... Operational amplifier, A-2 ......
Comparative amplifier, C ₁ , C ₂ …… Capacitor, TR _{1 to} TR ₃ …… Transistor, D ₁ …… Diode, L …… Choke coil,
D _Z …… Zener diode

Claims (1)

[Scope of utility model registration request] 1. A device for controlling the speed of a fan motor by the output of a temperature detecting device, which comprises an operational amplifier operating at a power supply voltage, and a resistor and a capacitor interposed between the input side and the output side of the operational amplifier. A reference obtained by connecting the output of the sawtooth wave oscillator to one input terminal of the comparison amplifier and dividing the power supply voltage into the other input terminal of the comparison amplifier with a resistance and a temperature sensitive resistance having a negative temperature coefficient. A voltage is applied, and a Zener diode is connected in parallel to the temperature-sensitive resistor.The Zener voltage of the Zener diode is set to the maximum value of the sawtooth wave oscillator output or less, and the output of the comparison amplifier is amplified to power the fan motor. The duty ratio of the output of the comparison amplifier rises when the ambient temperature rises, decreases when the ambient temperature rises, and falls below a certain temperature. There control device for the fan motor, characterized in that it is maintained larger than zero is value.