JPH0612684B2 - Hot air temperature control device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a temperature control device for a hot air blower such as a hair dryer.

[Background Art] In a hot air blower such as a hair dryer, even if the ambient temperature changes depending on the season, or the air volume changes due to a decrease in the number of rotations of the fan or the suction port or the protruding port is blocked, A phase control type temperature control device capable of maintaining a constant air temperature and variably setting the air temperature is used.

An example of such a temperature control device is Jpn.
No. 7, and this temperature control device is shown in FIG. This temperature control device controls the commercial power supply 17 with a bidirectional phase control element 14 such as a triac to supply power to the heater 7. The phase angle of the phase control element 14 is controlled by the positive temperature coefficient thermistor 10a. The air temperature is controlled to be constant, and the air temperature is variably set by the micro-heater 10b arranged near the positive temperature coefficient thermistor 10a and the variable resistor 9 connected in series to the micro-heater 10a. It is a thing. The positive temperature coefficient thermistor 10a has a capacitor 16
Are connected in series, and the capacitor 16 is charged via the positive temperature coefficient thermistor 10a to control the conduction state of the trigger element 15 described later. In addition, the trigger element 15 connected between the connection point between the positive temperature coefficient thermistor 10a and the capacitor 16 and the gate of the phase control element 14 includes the positive temperature coefficient thermistor 10a and the capacitor 16 described above.
The phase control element 14 is triggered in accordance with the charging and discharging of. Further, the motor 5 for rotating the fan is connected to both ends of the commercial power supply 17.

The air temperature stabilizing operation of this warm air control device will be described.
When the air temperature rises due to a change in the air temperature due to external factors such as the ambient temperature and a decrease in the air volume, the temperature of the positive temperature coefficient thermistor 10a rises and the resistance value of the positive temperature coefficient thermistor 10a increases. When the resistance value of this positive temperature coefficient thermistor 10a rises, the capacitor 1
The charging speed of No. 6 decreases, and as a result, the phase angle of the phase control element 14 increases. When the phase angle of the phase control element 14 is increased, the electric power supplied to the heater 7 is reduced, so that the air temperature is reduced. Conversely, when the wind noise drops, the temperature of the PTC thermistor 10a drops, and the PTC thermistor 10a
, The phase angle of the phase control element 14 decreases, the power supplied to the heater 7 increases, and the air temperature rises. In this way, the air temperature of the warm air fan is maintained at a predetermined temperature. When setting the air temperature, the variable resistor 9 is used. For example, when the air temperature is set high, the resistance value of the variable resistor 9 is increased. That is, when the resistance value of the variable resistor 9 is increased, the micro heater 10
Since the power of b decreases, the temperature of the positive temperature coefficient thermistor 10a decreases, and the resistance value decreases, the phase angle of the phase control element 14 decreases and the power supplied to the heater 7 increases.
The wind temperature rises. On the contrary, when the air temperature is set low, the resistance value of the variable resistor 9 is decreased.

However, in this temperature control device, when the resistance value of the variable resistor 9 is reduced and the power supplied to the microheater 10b is increased for the purpose of setting the air temperature low, the following oscillation phenomenon occurs. That is, when the resistance value of the variable resistor 9 is decreased, the power of the micro-heater 10b increases, the temperature of the positive temperature coefficient thermistor 10a increases, the resistance value of the positive temperature coefficient thermistor 10a increases, and the phase angle of the phase control element 14 increases by 180 degrees. Therefore, the electric power supplied to the heater 7 is lost, the air temperature is lowered, and the air in the warm air fan becomes cold air. Then, the resistance value of the positive temperature coefficient thermistor 10a decreases, and the phase control element 14
Has a small phase angle, the electric power supplied to the heater 7 rises, and the temperature of the positive temperature coefficient thermistor 10a rises, resulting in an oscillation phenomenon that repeats the operation, causing inconvenience of unstable control of the air temperature.

[Object of the Invention] The present invention has been made in view of the above points, and an object of the present invention is to provide a temperature control device for a hot air blower capable of performing stable air temperature control without causing an oscillation phenomenon. To provide.

DISCLOSURE OF THE INVENTION (Embodiment) FIGS. 1 to 6 show an embodiment in which the present invention is applied to a hair dryer, and the present embodiment will be described below based on this hair dryer.

As shown in FIG. 6, this hair dryer has a substantially cylindrical body in which a grip portion 1b held by a user is formed in the lower portion and a rear portion is formed in a large diameter in the upper portion of the grip portion 1b. The portion 1a is formed. The casing 1 is formed by the grip portion 1b and the main body portion 1a. A suction port 2 is formed at the rear of the main body 1a, and a discharge port 3 is formed at the front end of the main body 1a.
Air is sucked from the suction port 2 and discharged from the discharge port 3 by a fan 4 rotated by a motor 5 arranged inside the large diameter portion 1a. A printed circuit board 6 on which electronic components constituting the temperature control circuit 6a of the present embodiment are mounted is arranged in front of the motor 5, and a main body portion is provided on a small diameter portion on the tip side.
A heater 7 for heating the air sucked into the inside of 1a is provided. The heater 7 is wound around the heater substrate 11 combined in a cross shape. A switch 8 for switching the hair dryer to "off", "cold air", or "warm air" is provided on the front side surface of the grip portion 1b. Below the switch 8, there is provided an adjusting knob 9c which is rotated by the user of the hair dryer to adjust the air temperature, and a variable resistor 9a for adjusting the air temperature which is varied by the adjusting knob 9c, and A variable resistor 9b, which will be described in detail later, is provided in the gripping portion 1b, which is adjusted according to variations in parts involved in wind temperature control. This variable resistor
Reference numerals 9a and 9b are for changing the amount of electricity supplied to the micro-heater 10b to give the positive temperature coefficient thermistor 10a a temperature difference with respect to the air temperature. A power cord 13 for supplying power to the internal circuit is led out from the lower portion of the grip portion 1b. The temperature sensor 10 in which the positive temperature coefficient thermistor 10a and the micro heater 10b are integrated is disposed in front of the heater 7 inside the main body 10a,
The temperature control circuit 6a is connected to the printed circuit board 6 via the heater substrate 11. In addition, the temperature control circuit 6
The temperature control device is composed of a, the temperature sensor 10, and the variable resistors 9a and 9b.

The circuit configuration of the temperature control device will be described with reference to FIG. The heater 7 is connected to a commercial power supply 17 in series with a bidirectional phase control element 14 such as a triac via a switch 8 and a noise prevention coil 23. A series circuit of the positive temperature coefficient thermistor 10a and the capacitor 16 is connected in parallel to the phase control element 14, and the connection point between the positive temperature coefficient thermistor 10a and the capacitor 16 and the phase control element 14 are connected.
SBS that triggers the phase control element 14 with the gate of the
A trigger element 15 such as is connected. Further, a series circuit of the micro-heater 10b and the variable resistors 9a and 9b is connected to both ends of the series circuit of the phase control element 14 and the heater 7. The motor 5 that rotates the fan 4 is connected to the commercial power supply 17 via the diode bridge 21 so as to operate at a voltage obtained by rectifying the commercial power supply 17, and is used for noise prevention in order to reduce noise generated by the motor 5. Coil 2
4, 25 and a capacitor 26 are provided. The capacitor 27 is a noise-preventing capacitor that removes noise generated by the phase control element 14 together with the coil 23.

Since the operation is similar to that of the conventional example, detailed description thereof will be omitted, and the operation relationship will be schematically described according to the operation system diagram of FIG. The air temperature T of the hair dryer is determined by the electric power P supplied to the heater 7, the air volume Q, and the room temperature Tr, and is related by the following equation.

T = k (P / Q) + Tr Then, the detected temperature T _P of the air temperature of the positive temperature coefficient thermistor 10a is
Micro heater determined by resistance value of variable resistors 9a and 9b
Determined at a temperature T _R of 10b, microheater 1 to the wind temperature T
A value obtained by adding the temperature T _R of 0b. The detected temperature T _P is also related to the resistance-temperature characteristic of the positive temperature coefficient thermistor 10a. The phase angle θ of the phase control element 14 is controlled according to the detected temperature T _P. At this time, the capacitor 16 and the trigger element 15
The breakover voltage of is involved. This phase control element 1
The phase angle θ of 4 determines the electric power P supplied to the heater 7. The electric power P supplied to the heater 7 is
It depends on the resistance value of.

The above-described configuration and schematic operation are substantially the same as those described in the conventional example. With the configuration as described above, the oscillation phenomenon occurs as described in the conventional example. Examining the maximum cause of this oscillation phenomenon is as follows. That is, when the temperature of the positive temperature coefficient thermistor 10a rises, the phase angle of the phase control element 14 becomes 180 degrees, so that the electric power supplied to the heater 7 is lost and the oscillation operation is performed. Therefore, in order to suppress the above oscillation phenomenon, a positive temperature coefficient thermistor
The resistance-temperature characteristic of the positive temperature coefficient thermistor 10a may be changed so that the phase angle of the phase control element 14 is unlikely to be 180 degrees even if the resistance value of 10a increases. However, it is necessary to keep the characteristics as they are at the present except the phase angle of 180 degrees of the phase control element 14 due to the problem of wind temperature controllability. Therefore,
The phase control element 14 has a phase angle of 180 degrees, which is a resistance for smoothing the change of the resistance-temperature characteristic of the positive temperature coefficient thermistor 10a near the phase angle of 180 degrees.
A resistor 28 having a resistance value near the resistance value of the positive temperature coefficient thermistor 10a corresponding to the degree is connected in parallel with the positive temperature coefficient thermistor 10a. By connecting the resistor 28 in parallel with the positive temperature coefficient thermistor 10a, the phase control element 14 which has conventionally shown the relationship between temperature and phase angle as shown by the broken line in FIG.
The change in the phase angle with respect to the temperature becomes smooth as indicated by the solid line. Therefore, even if the temperature of the positive temperature coefficient thermistor 10a rises, the phase angle of the phase control element 14 does not easily reach 180 degrees, and therefore the heater 7 The oscillation phenomenon in which the power supplied to the device increases and decreases repeatedly does not occur.

Further, in the temperature control device for the hot air blower, the temperature sensor 10
Variation in wind temperature at the set position, positive temperature coefficient thermistor 10a
The electric power of the micro-heater 10b fluctuates due to the fluctuation of the resistance-temperature characteristics of the above, or the fluctuation of the components related to the air temperature control such as the fluctuation of the resistance value of the heater 7, and thus the wind temperature may fluctuate. The relationship between the electric power and the temperature of the micro heater 10b is shown in FIG. As is clear from this graph, the air temperature variable range that is always set (for example, a (° C) to b in FIG.
(° C)). It is necessary to increase or decrease the electric power of the micro-heater 10b in parallel according to the above-mentioned variation state. Therefore, in this embodiment, the variable resistor 9b
Is equipped with. FIG. 5 shows the relationship between the resistance value of the variable resistor 9a and the electric power of the micro heater 10b using the resistance value of the variable resistor 9b as a parameter. That is, the variable resistor 9b allows the temperature variable range to be always within the set temperature range even if there is the above variation. This principle will be described. Now, let us assume that the state of variation is the state shown in FIG. At this time, according to FIG. 4, in order to set the temperature range to a (° C) to b (° C), the micro heater 10
It is necessary to set the power of b to P to S (W). Therefore, if the variable resistor 9b for adjusting the variation is set to FIG. 5 (e), the set temperature variable range (a (° C.) to b (° C.)) can be created. That is, the variation of the above components is corrected by the variable resistor 9b so that the air temperature adjustment by the variable resistor 9a is always constant. Therefore, when the variation state is shown in FIG. 4 (a), the resistance value of the temperature adjusting variable resistor 9b is changed to that shown in FIG. 5 (d) (micro heater 10b power Q
~ T (W), and when the variation state is shown in Fig. 4 (c), the resistance value of the variable resistor 9b is changed to that shown in Fig. 5 (f) (micro heater 10b power OR (R) (W)). Just set it. In addition, the connection position of the variable resistor 9b for temperature adjustment is the micro heater 10b.
Either in parallel or in series with. By including the variable resistor 9b in this way, even if there are variations in the components related to the air temperature control, the variable resistor 9a can always set a constant temperature range.

[Effects of the Invention] As described above, according to the present invention, the resistance for smoothing the change in the resistance vs. temperature characteristics of the positive temperature coefficient thermistor is connected in parallel with the positive temperature coefficient thermistor in the vicinity of the phase angle of 180 degrees of the phase control element. , The phase angle change with temperature of the phase control element is 18
It becomes smooth near 0 degrees, and therefore, even if the temperature of the PTC thermistor rises, the phase angle of the phase control element does not easily reach 180 degrees, and therefore the power supplied to the heater increases and decreases repeatedly. The effect that the oscillation phenomenon does not occur is achieved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIGS. 2 to 5 are operation explanatory diagrams of the same as above, and FIG. 6 is a sectional view showing an overall configuration of the same. FIG. 7 is a circuit diagram showing a conventional example. 4 is a fan, 5 is a motor, 7 is a heater, 9a and 9b are variable resistors, 10a is a positive temperature coefficient thermistor, 10b is a micro heater,
Reference numeral 14 is a phase control element, and 28 is a resistor.

Claims (1)

[Claims] 1. A motor for driving a fan, a heater for heating wind blown by the fan, a phase control element for phase-controlling a current flowing through the heater, and a phase control element for detecting a wind temperature. A positive temperature coefficient thermistor for controlling the air temperature to be constant, and a temperature variable setting means for variably setting the detection temperature of the positive temperature coefficient thermistor, wherein the temperature variable setting means heats the positive temperature coefficient thermistor. In a temperature control device for a hot air blower, which comprises an energization amount varying means for variably setting an energization amount to the micro-heater, in the resistance-temperature characteristic of the positive temperature coefficient thermistor near the phase angle of 180 degrees of the phase control element. A positive temperature coefficient thermistor connected in parallel with a resistance that smooths changes.