JPH0587289U - Cooling fan for electric device - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a cooling fan for an electric device, which can save power consumption, reduce man-hours in the manufacturing process, and have wide adaptability for use. [Structure] A Hall effect sensitive IC circuit IC2 and an IC circuit IC3 for outputting a control signal (VCTRL) for pulse width modulation are connected to a drive IC circuit IC1. And the IC circuit
In addition to the thermal resistor RT and the capacitor C2, the resistor R
Connect 3 and R4 respectively.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an electric device cooling fan incorporated in an electric device, and more particularly to an electric device cooling fan capable of automatically adjusting a rotation speed of the fan according to a temperature change inside a circuit system of the electric device. .

[0002]

[Prior Art]

 Today, electric circuits are widely applied to various types of machinery and control equipment, and are extremely convenient for the modern life of mankind. However, since the electric circuit operates by the flow of current, the generation of Joule heat due to the heating effect of current is unavoidable. If this Joule heat cannot be eliminated, the temperature of the circuit system will rise, which may result in malfunction and damage of the circuit.

Therefore, as one of cooling methods for an electric device having an electric circuit, there is a method in which a circuit is forcibly cooled by a cooling fan. Of these, a relatively large number of speed-controlled cooling fans that are commonly used are those that use a step-down speed control circuit to drive an ordinary fan. That is, a thermal resistor (thermistor) with a large negative temperature coefficient is directly connected between the fan motor and the power supply, and the power supply from the power supply to the fan motor responds to the change in resistance value with respect to the temperature change of this thermal resistor. The voltage and current are changed to control the rotation speed of the fan motor.

In addition to the step-down speed control circuit, there is a speed control circuit using, for example, a voltage regulator. This is a voltage regulator and thermal resistor connected between the power supply and the fan motor.

[0005]

[Problems to be solved by the device]

 However, in the step-down speed control circuit, the thermal resistor having a large temperature coefficient cannot function normally when the consumption efficiency of the fan motor becomes excessive or the voltage of the input power source is low. On the contrary, there is a possibility that a large amount of Joule heat is generated to further raise the temperature inside the circuit system.

Further, in the voltage regulator type speed control circuit, it is necessary to connect a voltage regulator and a heat sensitive resistor between the power supply and the fan motor and additionally provide a power feeding circuit when designing the circuit system. Therefore, the space occupied by the circuit system increases. Even in this circuit, there is a possibility that the temperature inside the circuit system may further rise due to the Joule heat generation of the additional device.

Further, in any of the speed control circuits described above, in consideration of the low voltage starting of the fan motor, it is necessary to select a drive IC capable of operating at a low voltage, and further, a better motor. The design of the fan is required, and the selection of the fan casing material and the manufacturing process may be difficult.

The present invention has been made in view of the above conventional problems, and an object of the present invention is to provide a cooling fan for an electric device that can solve these problems.

[0009]

[Means for Solving the Problems]

 In order to achieve the above object, the present invention relates to a cooling fan for an electric device using a brushless DC motor, a drive circuit for driving and controlling the fan, and a detection circuit for detecting the rotation speed of the fan and outputting the rotation speed to the drive circuit. And a heat-sensitive resistor and a capacitor each having a negative temperature coefficient of resistance are connected, and a control signal for controlling the pulse width of the output pulse of the drive circuit according to the heat-sensitive temperature of the heat-sensitive resistor is output to the drive circuit. And a speed control circuit including a control signal output circuit.

Further, the present invention is characterized in that two resistors are further connected to the control signal output circuit.

[0011]

[Action]

 In the present invention configured as described above, when the thermal resistor detects the temperature change in the circuit system of the electric device, the control signal output circuit detects the rotation speed of the fan while the detection circuit detects the rotation speed of the fan. The control signal according to the temperature change is output to the drive circuit. The drive circuit modulates the pulse width of the output pulse based on this control signal and outputs it to the fan motor. Thus, the rotation speed of the fan is automatically adjusted according to the temperature change in the electric device so as to increase the fan speed when the temperature rises and decrease the fan speed when the temperature falls.

[0012]

【Example】

 Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is an exploded view of a cooling fan for an electric device according to an embodiment of the present invention. This cooling fan has a casing 100 having a storage chamber 101 for storing the blades 200 for generating an air flow, and three casings are provided on the front side of the casing 100 for storing the fan rotating shaft located at the center. A shaft accommodating portion 102 supported by the arms 104a, 104b, 104c is provided. Two ball bearings 110a and 110b are fitted inside the shaft accommodating portion 102, and a circuit board 500 on which a circuit described later is formed and the blades 200 welded on the circuit board 500 are fitted on the outside of the ball bearings 110a and 110b. The main body (stator) 400 of the brushless DC motor to be rotated is fitted. The power cord 510 and the heat-sensitive resistor 600 are pulled out from the wire drawing groove 103 of the arm 104c.

On the other hand, the rotor 210 of the brushless DC motor has the blades 200 mounted on the outer side thereof, and the ring-shaped permanent magnet 300 fitted on the inner side thereof. Then, according to the assembling order, the spring 113 for relaxing the impact is attached to the fan rotating shaft 211 of the rotor 210, and then the fan rotating shaft 211 is mounted on the ball bearing ring 110b in the shaft housing 102, the main body 400 of the brushless DC motor, the circuit board 500. Through the ball bearing 110a, and then penetrate the outside of the shaft accommodating portion 102. Then, the washer 111 is fitted to the outside of the fan rotation shaft 211 and fixed firmly with the ring 112. In this way, the cooling fan of the present proposal is assembled.

FIG. 2 is a circuit diagram showing an example of a pulse width modulation type fan speed control circuit formed on the circuit board 500 of FIG. In this circuit, the power supply voltage is applied to the circuit on the circuit board 500 and the brushless DC motor main body 400 (specifically, the amateur coil 410) via the reverse voltage protection diode D1. When the armature coil 410 is energized, a torque is generated by the interaction between the amateur coil 410 and the ring-shaped permanent magnet 300 to rotate the blade 200. At this time, the Hall effect sensitive IC circuit IC2, which is a detection circuit for detecting the rotational position of the motor to switch the phase of the brushless DC motor, operates under the condition that a constant bias current is applied by the resistors R1 and R2. The state of the magnetic field change between the coil 410 and the permanent magnet 300 is sensed (see FIG. 3 (A)).

The Hall effect sensitive IC circuit IC2 is a drive IC circuit that is a drive circuit for positive (V +) and negative (V-) voltages having waveforms as shown in FIGS. 3B and 3C, respectively. Output to IC1. The drive IC circuit IC1 compares these two input voltages with the internal voltage and shapes the input waveform to obtain the same FG waveform as shown in FIG. 3 (D). As will be described later, the in-phase pulse controls the pulse width of the output voltage of the semiconductor switches φ1 and φ2 having the waveforms shown in FIGS. 3 (E) and 3 (F), respectively. The magnetic poles of the winding groups L1 and L2 (that is, the amateur coil 410) of the brushless DC motor are switched according to the outputs of the semiconductor switches φ1 and φ2. The pulsating voltage generated during this switching operation is absorbed by the diodes D2 and D3 and the power stabilization Zener diode ZD1. The capacitor C1 supplies electric power for restarting the fan to the driving IC circuit IC1, and the fan is rotated by the driving system composed of the IC circuits IC1 and IC2.

A current limiting resistor R3 and a power supply voltage stabilizing Zener diode ZD2 are connected to the IC circuit IC3, which is a control signal output circuit, respectively. When the pulse generator (Frequency Generator; FG) of the driving IC circuit IC1 inputs the in-phase pulse, the IC circuit IC3 opens the collector and outputs it. Therefore, by using the resistor R4, the Hi-value of the IC circuit IC3 A match to the Lo state occurs. As a result, a trigger pulse signal having the waveform shown in FIG. 3 (D) is generated. A thermal resistor (thermistor; RT) and a capacitor C2 are connected to each of the IC circuits IC3, and the thermal resistor (RT) and the capacitor C2 form a pulse width sequence circuit. The IC circuit IC3 discharges all the electric charge stored in the capacitor C2 and recharges it at the rising and falling edges of the trigger pulse signal. At this time, the output Q (inverted output Q bar) is output and the level is changed from Lo (Hi) to Hi (Lo). On the other hand, when the capacitor terminal voltage (Vc) reaches a value equal to the reference voltage (Vth) by charging the capacitor C2, the IC circuit IC3 returns the output Q (inverted output Q bar) to Lo (Hi), After that, the capacitor C2 continues to be charged. This charging continues until the battery is full or the next discharge. The waveform thus formed is as shown in FIGS. 3 (G) and 3 (H). When the control voltage (VCTRL) signal shown in Fig. 3 (H) is fed back to the disable (Disable) input terminal of the driving IC circuit IC1 (Hi Disable → output Q, Lo Disable → output Q bar), The pulse signal as shown in Fig. 3 (E) and Fig. 3 (F), which was formed by the fan motor driving semiconductor switches φ1 and φ2 under a certain temperature, has its pulse width modulated, and the pulse signal shown in Fig. 3 (I) and A pulse with a waveform as shown in Fig. 3 (J) is output. With these outputs, the rotation speed of the fan is automatically adjusted according to the temperature change under the control of the thermal resistor (RT) and the IC circuit IC3.

Then, when it is necessary to apply a special treatment to the fan, the following example is used. First, adjustment of the same temperature-velocity characteristic is required only by replacing any one unit in one resistor (RC) of the pulse width sequence circuit. Also, when the fan's constant speed is any one of high speed, medium speed, and low speed, replace the thermal resistor in one resistor (RC) of the pulse width sequence circuit with a fixed resistor. Further, the high voltage low speed rotation circuit is as described above. Thus, when adapting to various characteristics, it suffices to simply replace electronic components in the manufacturing process with low technical work.

The IC circuits IC1, IC2, and IC3 are composed of CMOS units (Complement Metal-Oxide-Semiconductors) that require low power consumption in order to save energy.

In the cooling fan configured as described above, when the temperature in the circuit system of the electric device rises, the resistance value of the thermosensitive resistor RT decreases, so that the flow rate of the current increases and the rotational speed of the fan increases. Go up. Therefore, the amount of ventilation inside the circuit system increases and a large amount of jule heat is discharged, so that the normal operation of the circuit is maintained. On the other hand, when the temperature in the circuit system decreases, the resistance value of the thermal resistor RT increases, so the supply of current decreases, the fan speed decreases, and unnecessary noise also decreases.

As described above, when the cooling fan according to the present invention is used in an electric device, the same space as the space occupied by the conventional constant speed fan is sufficient, and it is not necessary to additionally design the power supply circuit. Furthermore, since the constant voltage directly input to the circuit system is received, it is not necessary to require the low-voltage operation characteristics of the fan to be controlled, and there are problems caused by the low-voltage start-up and input efficiency of the fan motor. The cost can be reduced and the manufacturing process can be simplified without any occurrence.

Also, the unit of the control circuit of the cooling fan of the present invention is extremely simple and can be completely installed in the conventional fan device. Moreover, since the power consumption of the control circuit unit used is extremely small, a large amount of Joule heat is not generated. Therefore, it is very easy to adjust the characteristics for the fan speed at the same temperature, and simply change the values of the resistors and capacitors in the circuit.

Further, the cooling fan of the present invention does not need to receive a high voltage, so that it is not necessary to reduce the winding diameter or increase the number of turns of the winding. Therefore, it is possible to employ a brushless DC motor of high voltage and low speed, which has been difficult to employ due to the conventional space and the difficulty of the manufacturing process.

Further, the cooling fan of the present invention can achieve the same effect of constant speed only by exchanging the electronic parts in the manufacturing process, and it can be operated at high speed, medium speed, and low speed like the conventional fan device. There is no need to change the number of windings or the wire diameter.

In addition, according to the cooling fan of the present invention, since a proper fan rotation speed can be obtained according to the temperature inside the circuit system, normal operation of the circuit is maintained, energy consumption is saved and noise is reduced. Reduction is achieved.

[0025]

[Effect of the device]

 As is clear from the above description, according to the present invention, energy can be saved, idle time in the manufacturing process can be reduced, and extremely wide applicability can be obtained.

[Brief description of drawings]

FIG. 1 is an exploded view of a cooling fan for an electric device according to an embodiment of the present invention.

FIG. 2 is a circuit diagram showing an example of a pulse width modulation type fan speed control circuit formed on the circuit board of FIG.

3A is a magnetic field change state diagram between a coil and a magnet sensed by IC2 in the circuit of FIG. 2, and FIG. 3B is I in the circuit of FIG.
Positive voltage waveform diagram output from C2, (C) Negative voltage waveform diagram output from IC2 in the circuit of Fig. 2, (D) Shaped positive / negative pulse input from IC2 in IC1 in the circuit of Fig. 2. Waveform diagram of the in-phase pulse obtained by processing, (E) is a waveform diagram of the output pulse of the semiconductor switch φ1 controlled by the in-phase pulse by IC1 in the circuit of Fig. 2, and (F) is the IC1 in the circuit of Fig. 2. Waveform diagram of the output pulse of the semiconductor switch φ2 controlled by the in-phase pulse, (G) is a pulse waveform diagram of the capacitor terminal voltage due to charging and discharging of the capacitor C2 in the circuit of FIG. 2, and (H) is Pulse waveform diagram of control voltage corresponding to charging / discharging of capacitor C2 output from IC3, (I) is Fig. 3
FIG. 3E is a pulse width modulation waveform diagram after the pulse has undergone waveform shaping by the control signal, and FIG. 3J is a pulse width modulation waveform diagram after the pulse in FIG. 3F has undergone waveform shaping by the control signal.

[Explanation of symbols]

Reference numeral 100 ... Casing 101 ... Storage chamber 102 ... Shaft storage portion 103 ... Line-out groove 104a, b, c ... Support arm 110a, b ... Ball bearing 111 ... Washer 112 ... Ring 200 ... Blade 211 ... Fan rotating shaft 300 ... Permanent magnet 400 … Brushless
Main body of DC motor 410 ... Amateur coil 500 ... Circuit board 510 ... Power cord 600 or RT ...
Thermal resistor IC1 ... IC circuit (driving circuit) IC2 ... IC circuit (detection circuit) IC3 ... IC circuit (control signal output circuit) C2 ... Capacitor R3, R4 ... Resistor

Claims (2)

[Scope of utility model registration request] 1. A cooling fan for an electric device using a brushless DC motor, a drive circuit for driving and controlling the fan, a detection circuit for detecting a rotation speed of the fan and outputting the rotation speed to the drive circuit, a thermal resistor and a capacitor. And a control signal output circuit for outputting a control signal to the drive circuit for controlling the pulse width of the output pulse of the drive circuit according to the heat-sensitive temperature of the heat-sensitive resistor, and a speed control circuit comprising: A cooling fan for an electric device, which is characterized in that 2. The cooling fan for an electric device according to claim 1, further comprising two resistors connected to the control signal output circuit.