JP2546310Y2 - Variable speed circuit of fan motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a variable speed circuit of a fan motor.

(B) Prior Art FIG. 3 is a circuit diagram showing a variable speed circuit of a fan motor prototyped by the applicant of the present invention before the present application, and the configuration excluding the thermistor described later is the inside of a fan housing (not shown). It is assumed to be provided in

In FIG. 3, resistors R ₁ and R ₂ are connected in series between a reference voltage V _ref and ground, and a thermistor R _S (temperature sensing element)
Is connected between the connection point of the resistors R ₁ and R ₂ and ground,
These connection points of R ₁ , R ₂ , and R _S are connected to the inverting input terminal (−) of the comparator CMP. That is, the comparator
A detection voltage corresponding to a temperature change inside the housing is applied to an inverting input terminal of the CMP. Specifically, the R _S
Has a negative temperature coefficient, so as the temperature inside the housing rises, the voltage applied to the inverting input terminal of the comparator CMP falls. Resistor R ₃ and capacitor C are connected in series between the reference voltage V _ref and ground, the connection point of the resistors R ₃ and the capacitor C is connected to the non-inverting input terminal of the comparator CMP (+). The capacitor C includes:
The resistor R ₃ and the charge by the time constant determined by the capacitor C is charged. Collector-emitter path of the transistor Q ₀ is connected between the connection point and ground of the resistor R ₃ and capacitor C. The transistor Q ₀ is turned on by applying a switching pulse KP generated when switching each phase of a fan motor (not shown) to the base, and discharges the electric charge stored in the capacitor C.
That is, the non-inverting input terminal of the comparator CMP
A sawtooth voltage is applied. Then, the detection voltage and the sawtooth voltage are level-compared by the comparator CMP,
The drive signal S is output.

FIG. 4 is a waveform diagram showing the operation of FIG. 3, where V _H is
Minimum ambient temperature of the thermistor R _S is a maximum voltage when the detectable minimum temperature in the thermistor R _S, V _L is the ambient temperature of the thermistor R _S is when the highest possible temperature detected by the thermistor R _S Voltage. When the sawtooth voltage a is higher than the detection voltage, a drive signal S of “1” for driving the fan motor is generated. Thereby, the fan motor, the detection voltage V _L, the period T ₁ by a drive signal S _1, S ₂ when V _H, T ₂ becomes (<T ₁₎ only driven it.

(C) Problems to be solved by the invention According to the configuration of FIG. 3, the fan motor is connected to the thermistor.
Depending on the detected temperature of the R _S, linear to variable speed drive can advantages are obtained in the range of the period T ₂ through T _1. However, on the other hand,
Since the minimum value of the sawtooth voltage a is smaller than the minimum value V _L of the detection voltage, a period that is not driven by the period T ₀ -T ₁ occurs to the fan motor. Thus, even if the temperature around the thermistor _RS rises, the drive signal S of "1" cannot always be applied to the fan motor, that is, the fan motor cannot be rotated at full speed. Accordingly, an object of the present invention is to provide a variable speed circuit of a fan motor that can constantly apply a drive signal S of “1” to the fan motor.

(D) Means for Solving the Problems The present invention has been made to solve the above problems, and is a method for performing charging with a time constant determined by a capacitor and a resistor and for switching each phase of a fan motor. A sawtooth voltage generating circuit for generating a sawtooth voltage having a predetermined period by applying a pulse to discharge, a detection voltage that changes based on a detection temperature of a temperature detection element having a negative temperature characteristic, and the sawtooth voltage. The fan motor is driven when the sawtooth voltage is higher than the detection voltage, and the fan motor is turned off when the sawtooth voltage is lower than the detection voltage. A comparison circuit that outputs a driving signal for the switching pulse in the variable speed circuit of the fan motor that drives the fan motor at a variable speed based on a change in the detection voltage. During the period in which the temperature detection element does not occur, the capacitor is charged to a first voltage higher than the maximum detection voltage detectable by the temperature detection element, and when the switching pulse occurs, the temperature detection element The first voltage higher than the minimum detectable detection voltage;
A sawtooth voltage control circuit that operates in response to the switching pulse so as to discharge the capacitor to a second voltage lower than a voltage, wherein the temperature sensing element detects a high temperature, and a minimum detectable by the temperature sensing element. When the detection voltage of
The fan motor is constantly rotated.

(E) Operation According to the present invention, since the minimum value of the sawtooth voltage obtained from the sawtooth voltage generation circuit is larger than the minimum value of the detection voltage,
A drive signal can always be applied to the fan motor.

(F) Embodiment The details of the present invention will be specifically described with reference to the drawings.

 FIG. 1 is a circuit diagram showing the circuit of the present invention.

In Figure 1, resistor R _4, the collector-emitter path of the R ₅ and the transistor Q ₁ is connected in series between the reference voltage V _ref and ground, switching pulses to the base of the transistor Q ₁
If KP is applied, the connection point of the resistors R _4, R ₅ the voltage V _r generated. Incidentally, as the voltage V _r becomes larger than the minimum voltage V _L which is determined by the detection temperature of the thermistor R _S, the value of the resistor R _4, R ₅ are assumed to be set. Collector-emitter path and a resistor R ₆ of the transistor Q ₂ is connected in series between the reference voltage V _ref and ground. Here, the transistor Q ₂ is connected to the resistor R ₄ ,
It is always driven by a voltage generated at the connection point of R _5. Collector-emitter path and a resistor R ₇ of the transistor Q ₃ are resistor R ₃
And is connected to the connection point of the capacitor C, also the transistor Q ₀ has a base connected to the collector of the transistor Q _3, the collector-emitter path is connected to the connection point of the resistors R ₃ and capacitor C. Here, the transistors Q ₀ , Q ₃
More Darlington transistor is configured, the transistor Q ₃ are irrespective of the switching pulse KP, it is always driven by the resistor R _6.

In Figure 1 the circuit configured as described above, the connection point potential of the resistor R ₃ and capacitor C, resistor R _4, descends from the connection point potential of R ₅ by the base-emitter voltage of the transistor Q ₂ transistor Q _This is a potential raised by the base-emitter voltage of ₃ , that is, equal to the potential of the connection point between the resistors R ₄ and R ₅ . Specifically, if the switching pulse KP is not generated, the resistance R ₃ and as a connection point potential of the capacitor C is substantially equal to the reference voltage V _ref, the capacitor C,
Charge is charged until the voltage between both ends of the capacitor C becomes substantially _Vref . Also, if the switching pulse KP occurs, the resistance R ₃ and as a connection point potential of the capacitor C is V _r, the charge of the capacitor C, transistor Q ₃ to the voltage across the said capacitor C becomes V _r, through the Q ₀ is discharged.

FIG. 2 is a waveform diagram showing the operation of FIG. 1. When the capacitor C charges and discharges based on the switching pulse KP, a saw-tooth voltage a having a maximum voltage V _ref and a minimum voltage V _r is generated. . When the detection voltage based on the thermistor R _S is V _H , the fan motor is driven by the drive signal S ₃ that becomes “1” only during the period T ₃ during the one generation period T ₀ of the sawtooth voltage a. _{If the} detection voltage based on _S is V _L , then V _r > V _L ,
By a drive signal S ₄ of "1", the fan motor will be driven at all times.

From the above, the temperature around the thermistor R _S is
When the maximum temperature that can be detected by R _S is reached, the drive signal S _{4 of} “1”
Is always applied to the fan motor, whereby the fan motor can rotate at full speed.

The circuit shown in FIG. 1 except for the thermistor R _S and the capacitor C can be made into an IC.

According to the present invention, since the minimum value of the sawtooth voltage obtained from the sawtooth voltage generation circuit is larger than the minimum value of the detection voltage based on the temperature detection element, the drive signal is transmitted to the fan motor. In addition to the fact that the fan motor can be constantly applied, that is, the fan motor can be linearly controlled at a variable speed according to the temperature detected by the temperature detecting element, the fan motor can be rotated at full speed.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing the circuit of the present invention, FIG. 2 is a waveform diagram showing the operation of FIG. 1, FIG. 3 is a circuit diagram showing a conventional circuit, FIG.
The figure is a waveform chart showing the operation of FIG. R _S …… Thermistor, CMP …… Comparator, Q ₀ , Q ₁ ,
Q _2, Q ₃ ...... _{transistor, R 3, R 4, R} 5, R 6, R 7 ...... resistance.

Claims (1)

(57) [Scope of request for utility model registration] 1. A sawtooth voltage for generating a sawtooth voltage of a predetermined period by performing charging by charging with a time constant determined by a capacitor and a resistance and applying a switching pulse for switching each phase of a fan motor to perform discharging. A generation circuit, compares the level of the detection voltage that changes based on the detection temperature of the temperature detection element having a negative temperature characteristic with the sawtooth voltage, and when the sawtooth voltage is higher than the detection voltage, the fan motor is turned on. A driving circuit for outputting a drive signal for bringing the fan motor into a non-driving state when the sawtooth voltage is lower than the detection voltage, and a comparison circuit for outputting a drive signal based on a change in the detection voltage. In a variable speed circuit of a fan motor that drives a motor at a variable speed, a period in which the switching pulse is not generated is higher than a maximum detection voltage detectable by the temperature detection element. The capacitor is charged to a high first voltage, and when the switching pulse occurs, the capacitor is charged to a second voltage higher than the minimum detection voltage detectable by the temperature detection element and lower than the first voltage. A sawtooth voltage control circuit that operates in accordance with the switching pulse so as to discharge, and when the temperature detection element detects a high temperature and a minimum detection voltage detectable by the temperature detection element is obtained, A variable speed circuit for a fan motor characterized by constantly rotating the fan motor.