JPS6355754B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a temperature control device for electric heating appliances such as electric carpets and electric floor heaters, and aims to improve comfort and temperature control accuracy.

The mainstream temperature control method for conventional electric heating appliances is to turn on and off a load such as a heater. In particular, temperature control devices using relay contacts have a problem with the lifespan of the relay contacts, and are relatively often limited by a timer or the like in order to reduce excessive on/off operations. Also, there are cases where a temperature difference is set between on and off, but in the latter case the temperature difference is relatively large, so the sense of temperature control is reduced, and in the former case, the timer time setting is fixed, so electric carpets etc. However, when the ambient temperature is low, the surface temperature of the carpet drops too much, causing the carpet to feel cold.

In view of the above points, the present invention aims to improve temperature control accuracy by setting a timer time appropriately depending on the ambient temperature.

FIG. 1 is a conventional temperature control characteristic diagram, which is a control method in which the heater off period is set at timer time t ₀ . This method uses the load temperature of the heater, etc., t _c at time t ₁ .
When the temperature reaches the set temperature T _s , the timer stops energizing the heater for time t ₀ and energizes the heater again at time t ₂ . The surface temperature of carpets, etc., is difficult to decrease, and conversely, if the ambient temperature is low, the surface temperature of carpets, etc., decreases greatly.
That is, the surface temperature of the carpet etc. changes depending on the ambient temperature, such as t _p at time t ₂ and T _p ' at time t ₄ . As a result, if the ambient temperature is low, you will feel cold.

FIG. 2 is a temperature control characteristic diagram in the present invention, in which the timer time is varied depending on the ambient temperature T _a . That is, assuming that the ambient temperature is T _aL from time t ₁ to time t ₂ , the surface temperature T _c of the carpet naturally decreases as heat dissipates faster.
At this time, if the timer time is fixed, the surface temperature of the carpet will drop too much and you will feel cold, but this will be alleviated if you shorten the t _a time. On the contrary t ₃
If the ambient temperature is T _{aH, which is high between time t4 and time t4 ,} the carpet surface temperature T _c will be difficult to fall, so the timer time tb can be long.
Set the timer time according to the ambient temperature T _a .

FIG. 3 is a circuit configuration diagram of a temperature control device that is an embodiment of the present invention. 1 is an AC power supply, 2 is a power switch, and 3 is a diode. This diode 3, a resistor 4, and a capacitor 5 form a control circuit. Configure power supply. A temperature sensor 6 is thermally coupled to the heater 7 and is connected in parallel to the AC power source 1. 8 is a temperature detection NPN transistor connected in series to the temperature sensor 6 via the base and emitter, and is connected to the AC power supply 1.
The current flowing through the temperature sensor 6 which is conductive at the half-wave voltage of is detected. 9 is a diode for protecting the base and emitter reverse voltage of the NPN transistor 8. 1
0 is a resistor connected to the collector of the NPN transistor 8 for temperature detection, and a capacitor 11 is connected in parallel with this resistor 10. 12 and 13 are resistors, and 14 is a variable resistor for temperature setting, which is connected in series with the resistors 12 and 13. 15 is a comparator, and this comparator 1
5 inputs the voltage of the capacitor 11 charged by the conduction of the temperature detection NPN transistor 8 and the temperature setting voltage set by the variable resistor 14;
If the temperature detected by the temperature sensor 6 is lower than the set temperature, an L signal is output, and if it is higher, an H signal is output. Note that A is a temperature detection circuit including the temperature sensor 6. 16 is a voltage drop resistor;
17 is a resistor, 18 is a constant voltage diode, 19,2
0 is a resistor, 21 is a PNP transistor, 22,2
3 is a resistor, 24 is an NPN transistor, and this
NPN transistor 24 drives relay 25,
The heater 7 is controlled by the contact 25'. 26 is a reverse voltage absorption diode, B is a timer circuit,
A diode 27, a resistor 28, and a capacitor 29 are connected in series, and the anode of the diode 27 is connected to the collector of the transistor 21. 30
is a resistance, which serves as a discharge resistance of the capacitor 29. A diode 31 is connected in a direction to block the discharge path of the capacitor 29, and is input to a comparator 32. 33 is resistance,
This resistor 33 is connected in series with a temperature-sensitive resistance element 34 that detects the ambient temperature, and forms a reference voltage for the comparator 32 and also sets a timer time. A diode 35 has a cathode connected to the midpoint between the resistor 33 and the temperature-sensitive resistance element 34, and an anode connected to the collector of the transistor 21. The output of the comparator 32 is connected to the collector of the transistor 8 via a diode 36 and a resistor 37.

The operation of the above circuit configuration will be explained. First, when the power switch 2 is closed, the control power supply V _DC is formed across the capacitor 5, and the AC power supply 1 is applied to the temperature sensor 6. The temperature sensor 6 has a negative impedance characteristic, and the impedance decreases as the temperature increases. The NPN transistor 8 that detects the current flowing through the temperature sensor 6 has a base grounded, and is conductive during a half cycle of the AC power supply 1 applied to the temperature sensor 6. That is, a current corresponding to the temperature detection impedance of the temperature sensor 6 becomes the collector current of the transistor 8, and the capacitor 11 is charged.
In short, when the temperature of the load is low, the impedance of the temperature sensor 6 is high and the collector current of the transistor 8 is small, so the voltage drop across the resistor 10 is low and the collector voltage of the transistor 8 is high. Conversely, when the temperature of the load increases, the impedance of the temperature sensor 6 decreases, the collector current of the transistor 8 increases, and the collector voltage decreases. The collector voltage of transistor 8 is input to the negative input terminal of comparator 15. A voltage set by the temperature setting variable resistor 14 is input to the + side input terminal of the comparator 15. For example, the set temperature T _s shown in Figure 2
If the carpet temperature T _c is lower than
The output becomes L, and the transistor 21 is turned on via the resistor 20 connected to the output of the comparator 15. When transistor 21 is turned on, transistor 24 is turned on via resistor 22, and relay 25 is energized. As a result, contact 25' of relay 25
is closed and the AC power source 1 is supplied to the heater 7.

On the other hand, in timer circuit B, when the transistor 21 is turned on, the capacitor 29 is charged via the diode 27 and the resistor 28, but the resistor 33 is short-circuited via the diode 35, and the relationship between the input terminal voltages of the comparator 32 is changed. Since V _T >V _C , and as a result, the output of the comparator 32 becomes H, the output is blocked by the diode 36. When the carpet temperature _Tc reaches the set temperature _Ts , the temperature detection circuit A
The output of the comparator 15 becomes H, and the transistor 2
1 turns off. Accordingly, transistor 24 is also turned off, relay 25 is deenergized, and power supply to heater 7 is stopped.

In the timer circuit B, when the transistor 21 is turned off, the capacitor 29 starts discharging via the resistor 28, and at the same time, a V _T voltage determined by the resistor 33 and the temperature-sensitive resistance element 34 is formed, and the input voltage of the comparator 32 is Since V _C >V _T , the output of the comparator 32 becomes L. As a result, one side input terminal of the comparator 15 of the temperature detection circuit A is held lower than the + side input terminal voltage via the diode 36 and the resistor 37, and the output of the comparator 15 is held at H. The temperature sensitive resistance element 34 has a negative characteristic to detect the ambient temperature of the carpet, and when the ambient temperature of the carpet is low, V _T
The voltage is high, and conversely, if it is high, the V _T voltage will be low. Therefore, as shown in FIG. 4, the terminal voltage V _C of the capacitor 29 decreases due to discharge, and the
The V _T voltage, which is the reference voltage for comparison, becomes V _TL when the ambient temperature is low, and as a result, the timer time limit becomes t _a
On the other hand, when the ambient temperature is high, V _TH becomes short, and the timer limit becomes tb. When the timer period determined by the ambient temperature has passed, the output of the comparator 32 becomes H again.
The negative input terminal of the comparator 15 of the temperature detection circuit A becomes the collector voltage of the transistor 8, and if the temperature detected by the temperature sensor 6 is lower than the set temperature _Ts , the relay 25 is energized again and the heater 7 is turned on. Supply power. Note that the constant voltage diode 18 is provided to stabilize the timer circuit B.

As described above, the temperature control device of the present invention prohibits re-supply of power to the load for the time set by the timer circuit after the power supply to the load is stopped by the ON/OFF signal of the temperature detection circuit. Therefore, it is possible to limit the ON/OFF operation of the relay contact that controls the load such as a heater, and as a result, the life of the relay contact can be extended. Furthermore, by lengthening the timer period when the ambient temperature of the load is high and shortening the timer period when the ambient temperature is low, the feeling of warmth and comfort can be improved when using the heating equipment that employs the temperature control device of the present invention. It is possible to improve sexual performance.

[Brief explanation of the drawing]

FIG. 1 is a control characteristic diagram of a conventional temperature control device, FIG. 2 is a control characteristic diagram of a temperature control device of the present invention, FIG. 3 is a circuit diagram of a temperature control device showing an embodiment of the present invention, and FIG. The figure is an operation diagram of the timer circuit in the temperature control device. 6... Temperature sensor, 7... Heater, A... Temperature detection circuit, 25... Relay, B... Timer circuit,
29...Timer capacitor, 34...Temperature-sensitive resistance element.

Claims (1)

[Claims] 1 A load such as a heater, a temperature sensor that detects the temperature of the load, a temperature detection circuit that outputs an on signal when the temperature detected by the temperature sensor is lower than a set temperature, and an off signal when it is higher, and the temperature sensor that detects the temperature of the load. A relay that receives ON/OFF signals from the detection circuit to control the power supply to the load, a temperature-sensitive resistance element that detects the ambient temperature of the temperature load, and a signal from the temperature-sensitive resistance element that causes the temperature to increase when the ambient temperature is high. and a timer circuit that sets a short time limit when the temperature is low, and after the power supply to the load is stopped by the off signal of the temperature detection circuit, the power supply to the load is not re-supplied for the time set by the timer circuit. Temperature control device characterized by prohibiting.