JPH0512809Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial field of application] The present invention relates to a temperature control device for electric heating appliances that uses a relay in combination with a semiconductor to reduce temperature changes and enable fine temperature control. .

[Conventional technology]

Conventionally, there are temperature control devices for electric heating appliances that connect only a relay or only a semiconductor switching element such as a thyristor or triax in series with a power supply to turn the load on and off. In a temperature control device for an electric heating appliance that uses only a relay, temperature control is performed using electrical contacts operated by the relay.

In addition, in a temperature control device for an electric heating appliance using a semiconductor switching element such as a thyristor or a triac, the semiconductor switching element is provided with heat dissipation fins.

As shown in FIG. 1, when controlling by relays, the range of temperature changes is large.

[Problem that the invention attempts to solve]

However, in a temperature control device for an electric heating device using a relay, the contact has a limited lifespan and the number of times it can be opened and closed is limited, so there is a problem that fine temperature control cannot be performed.

In addition, with the temperature control device of electric heating equipment using semiconductors, the number of ON and OFF operations is not a problem, but because a heat radiation fin is required, the shape of the temperature controller body that houses the temperature control device becomes large. There's a problem.

Therefore, the purpose of this invention is to reduce temperature changes.
An object of the present invention is to provide a temperature control device for an electric heating appliance that performs fine temperature control.

Another object of the present invention is to provide a temperature control device for an electric heating appliance that is compact, has a long life, and has control characteristics with little temperature difference, using a relay combined with a semiconductor switching element.

[Means for solving problems]

According to the present invention, in a temperature control device for an electric heating appliance in which load current is turned on and off by a semiconductor switching element such as a thyristor or a triax, one contact connected to the gate of the semiconductor switching element and the semiconductor a normally open two-pole single-throw relay having the other contact connected in parallel with a switching element, when said relay is energized by the output of the temperature control circuit, before said parallel connected contact closes; When the contact on the gate side is closed and the relay is in a de-energized state,
There is obtained a temperature control device for an electric heating appliance, characterized in that the parallel-connected contacts open before the gate-side contacts open.

〔Example〕

1 to 3 show an embodiment of the present invention.

Referring to the drawings, a temperature control circuit 1 includes a relay coil 2. This relay coil 2 operates two contacts 6 and 7 provided in a series circuit of a power source 3, a load 4, and a triac 5.

One end of one contact 6 is connected to the gate of the triac 5 via a resistor 8. Another contact 7 is connected between the power supply 3 in parallel with the triax 5. Temperature control circuit 1 causes current to flow through relay coil 2 based on its output. At this time, after the operating time of relay coil 2, contact 6 becomes
When turned on, a current flows to the gate of the triax 5, which turns on and current flows to the load 4. Next, contact 7 is turned ON by relay coil 2.
Then, the load current that has been bypassed between both ends of the triac 5 flows entirely to the contact 7. At this time, since the voltage at the time of closing the contact 7 is equal to the voltage drop of the triac 5, the load on the contact 7 is extremely small. Also, the load current flowing through the triax 5 is
Since only a short time elapses from when contact 6 is turned on until when contact 7 is turned on, the amount of heat generated by triax 5 is extremely small.

Next, when the temperature control circuit 1 loses its output and current no longer flows through the relay coil 2, the relay coil 2 returns to its normal state, and after that time, the contact 7 turns OFF.
Gate current flows from contact 6 through resistor 8, turning triac 5 ON. At this time, the load current flows through the triac 5. After that, contact 6 turns OFF and the gate current of triac 5 disappears. This triax 5 is turned off only after the AC power supply voltage drops to around zero voltage.

Therefore, even when contact 7 turns OFF, triax 5 turns ON instantaneously and lowers the voltage between contacts 7, reducing the load on contact 7.

Furthermore, since the load current flowing through the triax 5 at this time is only from the time when the contact 7 is turned off until the AC power supply voltage becomes near zero, the amount of heat generated from the triax 5 is extremely small.

In the temperature control circuit of an electric heating appliance operated in this manner, fine temperature control can be obtained when the load 4 is, for example, an electric carpet disposed in the carpet as a cord heater.

[Effect of idea]

As explained in the embodiments, according to the present invention, by using a relay in combination with a triax or a semiconductor switching element such as a thyristor, it is possible to control a temperature almost the same as that of a temperature control device using only a relay. The controller has a greater number of switching circuits than the conventional control shown in FIG. 1, allowing fine control with fewer changes.

In addition, the moment of turning on and breaking off the relay contact that opens and closes the load current is performed by semiconductor switching such as triac or SIRISK, so that only the merits of relays (no need for heat dissipation fins) and the merits of semiconductor switching elements (long life) are achieved. On the other hand, it is possible to provide a temperature control device for an electric heating appliance that is compact, has a long life, and has control characteristics with little temperature difference, and can overcome the disadvantages of both drawers and drawers.

[Brief explanation of drawings]

Fig. 1 is a circuit configuration diagram of a temperature control device for an electric heating appliance showing an embodiment of the present invention, Fig. 2 is a waveform diagram explaining the operation in the circuit configuration diagram of Fig. 1, and Fig. 3 is a diagram showing the temperature control device. Graph showing the state of control. FIG. 4 is a graph showing the state of conventional temperature control. 1...Temperature control circuit, 2...Relay coil, 4
...Load, 5...Triack, 6, 7...Contact.

Claims (1)

[Scope of utility model registration request] In a temperature control device for an electric heating appliance in which a semiconductor switching element such as a thyristor or a triax is used to turn on and cut off a load current, one contact connected to the gate of the semiconductor switching element is connected in parallel with the semiconductor switching element. a normally open two-pole single-throw relay with the other contact connected to the gate, and when the relay is energized by the output of the temperature control circuit, the gate side contact is A temperature control device for an electric heating appliance, characterized in that when the relay is closed and the relay is in a de-energized state, the parallel-connected contact is opened before the gate-side contact is opened.