JPH023050Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field This invention relates to a temperature control device for an electric oven for cooking food.

BACKGROUND OF THE INVENTION In recent years, with the trend of so-called home-made cooking in which breads, cakes, etc. are prepared at home, various electric ovens having low temperature setting circuits for yeast fermentation have been proposed. Further, since yeast fermentation requires stable temperature control, these electric ovens are equipped with various temperature control devices.

For example, in Utility Model Publication No. 57-18941, a roasting chamber equipped with a heater and an electrical equipment room equipped with a thermostat are separated by a partition plate, and a thermostat is attached to the partition plate via a mounting bracket. A diode is connected with a lead wire and placed close to the partition plate, and the temperature is controlled by operating a thermostat using the conduction heat from the partition plate and the self-heating of the diode. Further, in Utility Model Publication No. 57-25045, an inner case equipped with a heater is housed in an outer case, and a part of the side wall surface of the inner case is provided with a ventilation hole that protrudes into the inner and outer cases to introduce heated air. There is a method in which a temperature regulator is attached to the protrusion via bolts and nuts, and the temperature is controlled by operating the temperature regulator using conductive heat from the wall surface and heated air flowing through the ventilation holes.

In other words, the former has a structure in which the thermostat is operated by conductive heat from the partition plate and self-heating of the diode, while the latter operates the thermostat by conductive heat from the side wall of the inner case and heated air inside the inner case flowing through the ventilation holes. The structure operates the regulator, and all of the above have a structure in which energization to the heater is intermittently controlled by a thermostat made of one slowly moving bimetal, so the temperature of the furnace chamber and partition wall is controlled. The influence of the temperature difference (the time difference between when the furnace chamber reaches the set temperature and when the thermostat itself reaches the set temperature) and the operating characteristics (set temperature tolerance) of the thermostat made of a retractable bimetal is unavoidable and is shown in Figure 3. As shown in the figure, the first control (at startup) has a so-called overshoot in which the control temperature moves significantly up and down relative to the set temperature, and even after the second time, the interval between off and on operations relative to the set temperature is long, resulting in a temperature difference called daylight. This method has the disadvantage of a large differential, and is problematic as a temperature control device for yeast fermentation, which requires stable temperature control.

Purpose of the invention This invention addresses the shortcomings of conventional temperature control devices using slow-acting bimetallic thermostats, which are the temperature difference between the furnace chamber and the bulkhead and the operating characteristics of the thermostat. The present invention proposes a temperature control device for an electric oven that prevents overshoot, reduces differentials from the second time onwards, and enables stable temperature control for yeast fermentation.

Disclosure of the invention This invention consists of a furnace chamber in which multiple heaters are arranged,
In an electric oven, the electric oven is heated and shielded by the furnace chamber and a partition wall, and has an electrical equipment room equipped with a control device consisting of a changeover switch for selecting the combination of the heaters and a timer for setting the heating time. The thermostats TH ₁ and TH ₂ are equipped with control heaters R _{1 and} R ₂ that serve as heat sources for on/off control of _the respective thermostats, and have different calorific values such that R ₁ < R ₂ . control heater R ₁
A temperature control device circuit is constructed by connecting thermostat TH ₁ , control heater R ₂ , and thermostat TH ₂ in series, and connecting thermostat TH ₁ and control heater R ₂ in parallel to form a temperature control device circuit. A temperature control device for an electric oven, consisting of a small control heater _R1 connected to the power supply side of the heater circuit, and a thermostat _TH2 connected to the heater side of the heater circuit.

In other words, a high-precision thermostat is achieved by using a temperature control device in which two thermostats made of quick-acting bimetal, which have relatively poor temperature control, and two control heaters with different heating chambers that control on/off of these thermostats are connected in series. It achieves high-precision temperature control comparable to that of a temperature control device using a furnace, and stably manages the temperature inside the furnace.

Example This invention will be explained below based on the drawings.

The embodiment shows a temperature control device of this invention connected to a low temperature setting circuit for yeast fermentation.

In the figure, 1 is a furnace chamber, and a plurality of heaters R _A , R _B , and R _C connected in series are arranged in the furnace chamber.

2 is an electrical equipment room, and the electrical equipment room is connected to the furnace room 1 and the partition wall 3.
It is partitioned off and kept away from heat. Also,
Inside there are contacts a, b, which select the heater combination.
A changeover switch 4 having a switch 4 and a timer 5 for selecting the energization time are provided, and are connected in series with the heaters R _A , R _B , and R _C arranged in the furnace chamber 1, respectively.
Between the contact a of the changeover switch 4 and the heater R _A , there are two series-connected instant-break bimetal thermostats (hereinafter simply referred to as "thermostats") TH ₁ and TH 2 and the thermostats TH 1 and TH ₂ connected in series. The amount of heat generated as the heat source for on/off control is R ₁ <
Two control heaters R _{1 and} R 2 different from R ₂ are arranged in close contact with the heat sensitive parts of thermostats TH ₁ and TH ₂ ,
Control heater R ₁ and thermostat TH ₁ are connected in series, and control heater R ₂ and thermostat TH ₂ are connected in series, and thermostat TH ₁ and control heater R ₂ are connected in parallel to form a temperature control device circuit. Connect the control heater _R1 , which generates a small amount of heat, to the contact a of the changeover switch 4, and turn on the thermostat.
A temperature control device 6 of this invention is installed in which TH ₂ is connected to heater _RA .

Note that the thermostat used in the temperature control device 6
TH ₁ and TH ₂ are identical devices connected in series. Furthermore, although the amount of heat generated by the control heaters R ₁ and R ₂ changes depending on the set operating temperature, R ₁ < R ₂ is always maintained.
is set to 7 is an AC power supply.

In the above configuration, when the changeover switch 4 is connected to the contact c, the heaters R _A , R _B ,
A high temperature setting circuit is configured to energize R _C , and contact b
When connected to , a medium temperature setting circuit is configured that energizes heaters R _A and R _B , and the temperature in the furnace is controlled by a timer 5 in a timed manner. When connected to contact a, a low temperature setting circuit is constructed that energizes only the heater R _A , and the temperature inside the furnace is controlled by the timer 5 in a timed manner. It is controlled intermittently by device 6.

The low temperature setting circuit will be explained below.

When the timer 5 is set to a little less than 1 hour required for yeast fermentation, the circuit of power supply 7 - changeover switch 4 - control heater R ₁ - thermostat TH ₁ - thermostat TH ₂ - heater R _A - timer 5 - power supply 7 is configured. , the control heater R ₁ continues to heat up for a certain period of time until it reaches the set operating temperature of the thermostat TH ₁ with the set amount of heat generated, and after a certain period of time, the thermostat TH ₁ reaches the set operating temperature and turns off. . However, at this point, the temperature inside the furnace has not reached the temperature of around 38°C required for yeast fermentation. Note that during the above operation, the control heater _R2 is not energized and does not generate heat.

At the same time as thermostat TH ₁ is turned off, the circuit of power supply 7 - changeover switch 4 - control heater R ₁ - control heater R ₂ - thermostat TH ₂ - heater R _A - timer 5 - power supply 7 is configured, and the control heater
R ₂ is the thermostat TH ₂ with the set calorific value
The heating state is continued for a certain period of time until the set operating temperature is reached, and the heating state of the thermostat TH ₁ by the control heater R ₁ is also continued, so that the heating value is set to R ₁ < R ₂ . Thermostat heated by heater R ₂
Even after TH ₂ reaches the set operating temperature and turns off faster than thermostat TH ₁ , thermostat TH ₁ continues to be off, and all circuits turn off to control the temperature for the first time (at startup). ends. However, at this point, the temperature inside the furnace has reached around 38°C, which is required for yeast fermentation. Furthermore, the timer 5 continues to measure time.

All circuits are turned off and the thermostat TH ₂
When the thermostat reaches the set on-temperature due to natural cooling, the circuit except for thermostat TH ₁ is configured again. In this case, one thermostat TH ₁ is connected to the other thermostat TH ₂
is heated by control heater _R2 ,
The heating state by control heater _R1 continues, and since it is in a higher temperature state than thermostat _TH2 , the thermostat is lowered due to the natural cooling time difference.
TH ₂ does not return to the ON state first, and temperature control from the second time onwards is performed by the thermostat.
Only TH ₂ is used to repeatedly turn off and turn on at short intervals.

Then, when the timer 5 completes the timing operation, the yeast fermentation is also completed.

In other words, the first control (at startup) is performed in two stages using thermostats TH ₁ and TH ₂ .
After the first control, the thermostat TH ₂ is used to repeatedly turn off and on at short intervals, and as shown in Figure 2, it is possible to prevent overshoot and reduce the differential. This allows stable temperature control.

Effects of the invention The temperature control device of this invention has a simple structure consisting of a thermostat made of two quick-acting bimetals and a control heater for controlling the thermostat on and off, yet it can control the temperature with high precision. Because it can be manufactured easily and inexpensively, it is not only ideal as a temperature control device for low-temperature setting circuits for yeast fermentation in electric ovens, but also as a temperature control device for other electric cooking appliances that heat and cook food using heating elements. It has excellent features such as being applicable to

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of an electric oven in which the temperature control device of this invention is incorporated into a low temperature setting circuit. FIG. 2 is a graph showing the control performance of the temperature control device of this invention with respect to the set temperature. FIG. 3 is a graph showing control performance of a conventional temperature control device with respect to set temperature. 1... Furnace room, 2... Electrical equipment room, 3... Partition wall, 4...
...Selector switch, 5...Timer, 6...Temperature control device, 7...AC power supply, R _A , R _B , R _C ... Heater,
a, b, c...Contact, _TH1 , _TH2 ...Quick-acting bimetal thermostat, _R1 , _R2 ...Control heater.

Claims (1)

[Scope of utility model registration request] An electrical equipment room having a furnace chamber in which a plurality of heaters are arranged, and an electrical equipment room that is heated and cooled by the furnace chamber and a partition wall, and that is equipped with a control device consisting of a changeover switch that selects the combination of the heaters and a timer that sets the energization time. In the oven, two parts made of quick-acting bimetallic
The thermostats TH ₁ and TH ₂ are equipped with control heaters R _{1 and} R ₂ that serve as heat sources for on/off control of the respective thermostats and have different calorific values such that R ₁ < R _{2 .} The control heater R ₁ and thermostat TH ₁ and the control heater R ₂ and thermostat are arranged in series in close contact with the heat-sensitive part.
Connect TH ₂ in series and thermostat TH ₁
and control heater _R2 are connected in parallel to form a temperature control device circuit. Control heater _R1 , which generates a small amount of heat, is connected to the power supply side of the heater circuit, and thermostat _TH2 is connected to the heater side of the heater circuit. Temperature control device for electric oven connected to.