JPH0115887B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an oven temperature control device for controlling the temperature inside an oven in a heating device having a plurality of heaters inside the oven.

(Prior Art) Fig. 1 shows the electric circuit of a general microwave oven with a heater, in which 1 is a power supply, 2 is a power switch, 3 is a door switch, 4 is a timer for setting cooking time, and 4a is a timer switch. , 5 is a cooking switch, 6 is a magnetic switch, 6a to 6c are contacts of this magnetic switch, 7 is a shelf drive motor,
Reference numeral 8 indicates a changeover switch for switching between range cooking using microwave heating and oven cooking using heater heating, 9 a heater control switch, 10 an oven temperature setting circuit that controls the operation of this heater control switch, 11 and 12 heaters, and 13 a This is a microwave generation circuit that includes a magnetron. Note that 14 is a temperature control device portion of the oven.

In the case of oven cooking, the changeover switch 8 is connected as shown, and the food placed on the shelf in the oven is heated by the heater. In this case, multiple heaters are arranged inside the oven, for example, two heaters at the top of the oven and one heater at the bottom of the oven, and the temperature inside the oven is controlled by controlling the power supply to these heaters. I try to control it. That is, the temperature control device section 14 of the oven
, the oven temperature is set in advance by the oven temperature setting circuit 10, and by comparison with the oven temperature detection input, the control switch 9 is controlled on/off in a temperature range centered around this set temperature to turn on and off the heaters 11, 12. The power supply is controlled.

(Problem to be Solved by the Invention) In the above-mentioned conventional case, even if the oven detection section controls the temperature within ±5 degrees Celsius, the temperature inside the oven varies by ±2 degrees due to the temperature gradient between the temperature inside the oven and the temperature detection section.
The drawback was that it fluctuated greatly, such as in degrees Celsius.

This invention was made in view of the above circumstances, and uses a plurality of heaters with different capacities, each with a different on/off control temperature range,
By using a heater suitable for the oven set temperature and controlling only the large-capacity heater among multiple heaters on/off, fluctuations in the oven temperature can be reduced compared to conventional methods, and efficiency can be improved. The purpose of the present invention is to provide an oven temperature control device capable of good temperature control.

[Structure of the invention] (Means for solving the problem) A plurality of large and small heaters provided in an oven,
A heater control switch provided for each of the large and small heaters, a temperature detection means for detecting the temperature inside the oven, and a set temperature in the oven and the large and small heaters around the set temperature. a circuit that sets different on/off control temperature ranges for each of the heater control switches, and compares the oven internal temperature detected by the temperature detection means with a set temperature to execute on/off control of the heater control switch, The circuit has a comparator in it,
Approximately ±1℃, ±of the set temperature for each small heater
Control is performed with an on/off control temperature range of 3°C, and the plurality of heaters are energized simultaneously at the start of heating, and when the set temperature is maintained, the energization to the small heaters is switched and selected according to the set temperature, and the control is performed as described above. Only one of the large heaters is controlled on/off via a switch.

(Function) Before the temperature inside the oven reaches the set temperature, power is applied to multiple heaters of different capacities, and when the temperature inside the oven reaches the set temperature, power is applied to the small heater among the multiple large and small heaters according to the set temperature. At the same time, only the large heater is turned on and off.

Thereby, the temperature inside the oven can be efficiently controlled.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. FIG. 2 schematically shows an oven temperature control device according to the present invention, which is used by replacing the section 14 in FIG. 1. That is, in FIG. 2, 20 is a first heater, 21 is a second heater, 22 is a first heater control switch, 2
3 is a second heater control switch, 24 is an oven temperature setting and temperature width setting circuit, and when an oven temperature detection signal is input and the temperature inside the oven exceeds the set temperature range, the heater control switch 2 is activated.
The heaters 20 and 21 are controlled to be energized through the heaters 2 and 23. By the way, it goes without saying that the heaters 20 and 21 are small-capacity and large-capacity heaters, respectively, and their values are determined as appropriate.

FIG. 3 shows the setting circuit 24 of FIG. 2 described above in detail. A1 and A2 are comparators for temperature comparison, 25 is a temperature sensitive resistance element for oven temperature detection that provides different comparison inputs to comparators A1 and A2, and 26 is an oven temperature that sets the reference input for comparators A1 and A2. This is a variable resistance for setting. resistance 2
7 and 28 are used to set the sensitivity of the comparison inputs of comparators A1 and A2. For example, comparator A1 changes the output on/off state as the oven temperature changes within a temperature range of ±3°C to the set temperature. Invert. On the other hand, comparator A2 indicates that the oven temperature is ±1
The on/off state of the output is reversed as the temperature changes over a temperature range of °C. A relay 29 is operated by the output of the comparator A1, and the contacts of this relay correspond to the first heater control switch 22 described above.
Similarly, 31 is a relay operated by the output of the comparator A2, and the contacts of this relay correspond to the second heater control switch 23 described above. Temperature sensitive resistance element 25
The detected oven internal temperature is compared with a predetermined temperature range set by resistors 27 and 28 centered around the set temperature set by the variable resistor 26, and whether the oven internal temperature exceeds the upper limit temperature of the temperature range or the lower limit temperature is determined. Output signals are sent from comparators A1 and A2, respectively, depending on whether the
The relays 29 and 31 are operated by the output signal of
The heater control switches 22 and 23 are controlled to turn each heater 20 and 21 on and off.

For example, if a 400 watt heater is used as the first heater 20 and an 800 watt heater is used as the second heater 21, the operations of these heaters 20 and 21 will be as shown in FIGS. 4 and 5 according to the set temperature. works.

That is, as shown in FIG. 4, when the oven temperature set by the variable resistor 26 is high, both heaters 20 and 21 are turned on from the start of cooking until the oven temperature reaches the upper limit detection temperature a of the set temperature + 10°C. When the oven temperature reaches the upper limit detection temperature a, the second heater 21 is turned off, and the first heater 20 is turned off.
only is in the on state. In this state, the first heater 2
The small heater at 0 remains on, but the oven temperature begins to slowly drop to maintain the high temperature.
When the lower limit detection temperature b of −1° C. is reached, the second heater 21 is turned on again to raise the oven temperature. Thereafter, the oven temperature is controlled only by turning on and off the second heater 21 while the first heater 20 remains on. In this case, if the oven temperature does not decrease but increases even when the second heater 21 is turned off, the oven temperature is controlled according to the operation shown in FIG. 5, which will be described later.

FIG. 5 shows a case where the set temperature of the oven is low, and when cooking starts, the large and small heaters are similarly energized, and when the oven temperature reaches the detection temperature a, the large capacity second heater 21 is first turned off. Further, in this state, the small heater 20, which is the first heater 20, is turned on, so the oven temperature rises, and when the detected temperature c, which is the set temperature + 3° C., is reached, the small heater 20 is also turned off. In this state, the first heater 20 and the second heater 2
Since both of them are off, the oven temperature naturally starts to drop. When the oven temperature falls to the detected temperature b, the second heater 21 is turned on again, and the oven temperature begins to rise again. When the oven temperature reaches the detected temperature a, the second heater 21 is turned off and the oven temperature begins to fall again. Thereafter, the oven temperature is maintained and controlled at a low set temperature by turning on and off the second heater 21 while the first heater 20 remains off. In this case, if the oven temperature is set temperature - 3
When the temperature drops to the detected temperature d in °C, the first heater 2
By turning on 0 as well, the temperature is quickly raised again.

Therefore, when controlling the heater on and off to maintain the temperature inside the oven at a set temperature, if the set temperature is high, only the large capacity heater is controlled on and off while the small capacity heater is energized. Furthermore, when the set temperature is low, the small-capacity heater is turned off, and the on/off temperature is controlled using only the large-capacity heater. In other words, a large capacity unit is used to turn the heater on and off.
Since only one heater is used, temperature fluctuations are reduced. In addition, by changing the on/off control temperature range of each heater, it is possible to select whether the small capacity heater is turned on or off at high or low temperatures, allowing efficient on/off temperature control according to the set temperature. Can be retained.

Furthermore, by setting multiple heaters in different sizes and controlling the large capacity heaters on and off, it is possible to set the temperature over a wide range at high and low temperature settings, compared to when the total capacity is the same and the same heater is used. Since the temperature inside the oven can be maintained accurately, the food to be heated will not be affected by temperature changes inside the oven, and cooking will not fail.

In this way, the small-capacity first heater 20 and the large-capacity heater 21 are turned on and off at different temperature ranges.
Since it is turned off, it is possible to control so that only one of the two heaters is turned on or off while the set temperature is maintained, which can be expected to improve thermal efficiency and reduce the temperature difference within the refrigerator.

[Effects of the Invention] As explained above, according to the present invention, only the heaters suitable for the oven set temperature are selected by changing the on/off control temperature range of each heater provided in the oven. Oven temperature control allows for on/off control, which reduces fluctuations in oven temperature around the oven set temperature compared to conventional methods, and enables efficient temperature control and maintenance. equipment can be provided.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the electric circuit of a general microwave oven with a heater, FIG. 2 is a basic circuit diagram of an oven temperature control device according to an embodiment of the present invention, and FIG.
This figure is a block diagram showing in detail the oven temperature setting and temperature width setting circuits in FIG. 2, and FIGS. 4 and 5 are temperature curve diagrams for explaining the circuit operation of FIG. 2. 20, 21... Heater, 22, 23... Heater control switch, 24... Oven temperature setting and temperature width setting circuit, 25... Temperature sensitive resistance element, 26...
...Variable resistor for temperature setting, 27, 28...Resistor for temperature width setting, A1, A2...Comparator, 29, 31...
…relay.

Claims (1)

[Claims] 1. A plurality of large and small heaters provided in the oven, heater control switches provided corresponding to each of the large and small heaters, temperature detection means for detecting the temperature in the oven, and settings in the oven. temperature and the above-mentioned temperature centered around this set temperature,
A circuit that sets different on/off control temperature ranges for each of the small heaters and compares the oven internal temperature detected by the temperature detection means with a set temperature to execute on/off control of the heater control switch. The circuit that executes the on/off control has a comparator that controls the control switches of the large and small heaters with respective set on/off control temperature widths, and initially controls the plurality of heater control switches at the same time. When the heater is closed and the set temperature is maintained, energization to the small heater is switched and selected according to the on/off control temperature range of the control switch, and only one of the large heaters is controlled on/off via the control switch. An oven temperature control device characterized by: