JPS60178517A - Temperature controller - Google Patents

Abstract

PURPOSE:To stabilize high-precision temperature control and electric power supply by providing the 2nd heater connected to the 1st heater for a part to be heated at distance from the part to be heated. CONSTITUTION:A cylindrical heater part 2 provided to a heater body housing 1 is inserted into a cup-shaped container 6 and a heater RL2 is applied with commercial electric power E to generate heat. Further, the housing 1 is mounted on the wall of the container 6, and a switch 9 for prevention against heating in the absence of an object of heating which operates therein is provided. In this case, the 2nd heater RL1 is connected to said heater RL2 and arranged at distance from the containter 6, for example, in an adapter 7 together with a control circuit X. The temperature of this heater RL1 is detected by a thermistor RTH to detect temperature equivalent to that of the heater RL2 of a heating part, and a triac T2 is brought under phase control based upon the detected temperature to control the inside of the container 6 to specific temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a temperature control device that maintains power consumption in a heater at a predetermined value regardless of voltage changes.

[Background technology]

Conventional examples are shown in FIGS. 1 to 3. FIG. 1 shows the external appearance, and numeral 1 is the heater main body housing, which has a built-in circuit shown in FIG. 2. 2 is a cylindrical heater part, and the heater R1 is made of ceramic or the like and has a sandwich-inch structure.
Insulated to prevent direct contact with water. 3 is a switch for preventing empty cooking, and the switch 3 is turned on when the cup-shaped container 6 is attached to the wall. 4 is a power cord, and 5 is a plug.

Next, the principle of operation of the circuit shown in FIG. 2 will be explained.

When switch 3 is turned on and commercial power E is applied,
Current flows through heater RL and generates heat. Since the heater R and the temperature sensor RjH, which is a positive characteristic coefficient (PCT) thermistor, are thermally coupled, the temperature of the temperature sensor RTH increases and the resistance increases, so the charging current to the capacitor C2 decreases. , the bidirectional switching element T, takes longer to reach the breakover voltage, and the phase angle becomes larger.

As a result, the conduction angle α of the triac T2 becomes small, and the voltage of the heater RL is controlled.

That is, by appropriately selecting one Curie point of the temperature sensor RTH, the resistance is controlled so that the temperature sensor RTH reaches that temperature.

The details are as follows. When the temperature is low and the resistance value of temperature sensor RTH, which is a positive temperature coefficient thermistor, is small,
With respect to the power supply voltage waveform shown by curve A1 in FIG. 3(A), the charging voltage Vc of time constant capacitor C2 is curve A1 in FIG. 3(A).
As shown in 2, the switch voltages Vs (+), Vs () of the bidirectional switching element T1 rise quickly and have an early phase.
, the trigger current flows through the triac T2 at an early phase as shown by curve B in the same figure (B), and the voltage across the triac T2 and the voltage across the heater RL are respectively shown in the same figure (C), ' (D) Curve 1+ +.

As shown by G1, the power supplied to the heater R becomes larger than before.

On the other hand, when the temperature is high and the resistance value of temperature sensor RTH is large, the charging voltage Vc of time constant capacitor C2 is
As shown by curve A3 in A), the switch voltage Vs (+) of the bidirectional switching element TI rises slowly and has a slow phase.
, Vs (), the trigger current flows through triac 1゛2 with a slow phase as shown by curve B2 in the same figure (B), and the voltage across triac T2 and heater RL
The voltages at both ends of the curves C2 and C2 in the same figure (C) and (D), respectively, are
As shown by D2, the power supplied to the heater RL becomes smaller than before.

In this way, the voltage supplied to heater RL is maintained within a substantially constant range regardless of temperature changes in heater R.

However, as shown in Fig. 2, in this circuit system, it is necessary to thermally supply the temperature sensor RTH to the heater RL.
It was necessary to house the circuit inside the housing 1. For this reason, when attached to the container 6, if hot water or the like boils, there is a drawback that reliability of the electronic circuit is significantly deteriorated due to temperature rise, humidity, etc. inside the housing 1. Also, if you use an adapter with a built-in circuit instead of the plug 5 to convert it from the housing I, at least three lead wires like a, b, and c are required because the heater RL and the sensors R and TH are placed close to each other. This was also a problem.

The circuit composed of the diodes DI and D2 and the resistor R1 is a circuit for removing hysteresis of the bidirectional switching element T1, and the circuit composed of the capacitor C1 and the coil 17 is a noise elimination circuit.

[Purpose of the invention]

An object of the present invention is to provide a temperature control device in which a temperature sensor and other electronic circuits are not thermally affected by a heated portion such as a container, and the constant power supply is highly reliable.

[Disclosure of the invention]

The temperature control device of the present invention includes a first heater set to a heated part, a second heater connected to the first heater and separated from the heated part, and a temperature control device of the second heater. The heater comprises a sensor and a control circuit that controls the power supplied to the first heater based on the temperature detected by the temperature sensor so that the power consumption of the first heater is maintained at a predetermined value. be. The temperature and temperature change of the second heater have a certain relationship with the temperature and temperature change of the first heater. Therefore, the power supply to the first heater can be controlled by detecting the temperature of the second heater. In this way, the temperature sensor can be separated from the heated section, the adverse thermal effects of the temperature sensor from the heated section can be avoided, and the reliability of power supply control can be improved. Further, the electronic circuits related to the temperature sensor are similarly not affected by the adverse effects of heat, and from this point of view as well, the above-mentioned reliability can be expected to be improved.

A first embodiment of this invention will be described based on FIGS. 4 and 5. In FIG. 4, 7 is an adapter used in place of the plug 5, and the circuit X shown in FIG. 5 is housed within this adapter 7. Circuit It has a temperature sensor RTH. Others are conventional examples (
(Fig. 1).

To explain the operation of the circuit, in the conventional example, the temperature sensor RTH directly detected and controlled the temperature of the heater, but since the circuit part was moved to the adapter 7 separated from the container 6, it was connected in series to the main heater RL2. The temperature sensor RTH is thermally coupled to a second dummy heater RLI connected to the
By controlling the temperature of this heater RTH, the main heater RL2 is also controlled at the same time. That is, when the voltage increases and the temperature of the second heater RLI rises, the temperature sensor RTH self-controls to reach the temperature at the cue point, and the phase angle of the triac T2 changes to increase the resistance value. (The power of the main heater RL2 can be kept constant.The cord 4 may also have two lead wires, d and e.

A second embodiment will be explained based on FIG. main first
A dummy second heater RLI is connected in parallel with the heater RL2. The rest is the same as the first embodiment. This also allows the power of the main heaters R1 and R2 to be constant. An example of the characteristics of the second embodiment is shown in FIG.

[A) Results of the invention]

According to this invention, since the temperature sensor is configured to be separated from the heated part, the temperature sensor is not affected by thermal effects from the heated part, and highly accurate temperature control and improved stabilization of power supply are achieved. It has the effect of being able to

[Brief explanation of the drawing]

Figure 1 is a perspective view of the exterior of the conventional example, Figure 2 is its circuit diagram,
3 is a waveform diagram of each part, FIG. 4 is a perspective view of the external appearance of the first embodiment of the present invention, FIG. 5 is its circuit diagram, and FIG. 6 is the second embodiment.
The circuit diagram of this embodiment and FIG. 7 are characteristic graphs. RLI...Second heater, RL2...First heater, R'rH...Temperature sensor, 6...Heated part RL Figure 2-)Electric EV (ACV)'; s7 Figure

Claims (1)

[Claims] A first heater set on the heated part, and a second heater connected to the first heater and separated from the heated part.
and the temperature sensor of this second heater, and the power supplied to the first heater based on the detected temperature of this temperature sensor so that the power consumption of this first heater is maintained at a predetermined value. A temperature control device comprising a control circuit for controlling the temperature.