JPS636989Y2 - - Google Patents

Description

[Detailed description of the invention] Technical field of the invention The invention detects the temperature of a pot using a temperature detection section made by winding a coil of magnetic material that causes a rapid change in magnetic permeability at the Curie point temperature, and uses the detection output to detect the temperature of a heater. The present invention relates to a temperature control device for a pressure cooker, which controls the temperature of the pot and the pressure inside the pot to be kept constant.

Purpose of the invention The purpose of the invention is to create a highly reliable configuration by using a temperature sensing section consisting of a coil wound around a magnetic member that undergoes a rapid change in magnetic permeability at the Curie point temperature, while also providing an extremely simple circuit. It is an object of the present invention to provide a temperature control device for a pressure cooker that has effects such as being able to control the temperature of a pot in a plurality of stages depending on the configuration.

Summary of the invention In order to achieve the above object, the present invention includes a plurality of cooking temperature sensing parts each having a coil wound around a magnetic member having a different Curie point temperature, and a lower Curie temperature than the magnetic member. and a heat-retaining temperature detecting part formed by winding a coil around a magnetic member having a heat-retaining temperature detecting part, and when the heat-keeping temperature detecting part is activated, the coil of the heat-keeping temperature detecting part is connected to the coil of the cooking temperature detecting part. The feature is that they are configured to be connected in parallel.

Embodiment of the invention Hereinafter, an embodiment of the invention will be described with reference to the drawings.

In Fig. 1, numeral 1 is a timer, which is a cam switch 1b and a timed operation that are closed in response to the time limit setting operation performed by rotating the operator 1a shown in Fig. 2 to the "high pressure cooking" side. The cam switch 1b is configured to be opened when the timed operation ends, and to be opened continuously when the operator 1a is rotated toward the "warm operation" side. It is configured to be closed. 2 is an AC power supply, one terminal of which is connected to the bus bar 3 via the cam switch 1b,
Connect the other terminal to the bus bar 4. 5 is a relay having an excitation coil 5a and a relay contact 5b; 6 is a heater for heating a pot (not shown) of the pressure cooker;
A series circuit between the heater 6 and the normally closed contacts (c-b) of the relay contact 5b is connected between the bus bars 3 and 4. Reference numeral 7 denotes a DC power supply circuit, which has a well-known configuration in which a rectifier diode 8, a resistor 9, a smoothing capacitor 10, and a voltage regulator diode 11 are connected between the bus bars 3 and 4 as shown in the figure.
A constant DC voltage is output between the bus bar 12 connected to the common connection point of the capacitor 10 and the bus bar 3. Reference numeral 13 denotes an oscillator that is supplied with power from between the busbars 3 and 12. When supplied with power, this oscillator oscillates at about 100 KHz and outputs a pulse signal Po as shown in FIG. 3A. Now, 14 and 15 are a plurality of, for example, two cooking temperature detection parts, and these are magnetic materials such as ferrite that cause sudden changes in magnetic permeability at mutually different Curie point temperatures (for example, 120°C and 113°C). (not shown) are wound with coils 14a and 15a, respectively. Reference numeral 16 denotes a heat-retaining temperature detection section, which is constructed by winding a coil 16a around a magnetic member (not shown) having a lower Curie point temperature (for example, 70° C.) than each of the magnetic members. Each of these temperature detection units 14, 15, and 16 is installed to be heat-conductively attached to the pot (not shown) to detect its temperature. When the temperature exceeds the temperature, the inductance of the coil corresponding to the magnetic member having the Curie point temperature among the coils 14a, 15a, and 16a rapidly decreases. 17 is a first changeover switch; 18 is a switch that closes the contacts (i-h) when the operator 1a of the timer 1 is rotated to the "high pressure cooking"side; A second changeover switch that closes the contacts (i-g) in conjunction with the rotation operation of the child 1a to the "warming operation" side, 19 is the output terminal O of the oscillator 13, and a switching device to be described later. Transistor 21 forming part of section 20
is a capacitor interposed between the base of
This capacitor 19 is connected to each of the above-mentioned changeover switches 17,
The coils 14a, 15 depending on the closed state of the coil 18.
A and 16a form a filter. That is, one end of the capacitor 19 on the transistor 21 side is connected to a series circuit between the coil 14a and the contact point (fd) of the first changeover switch 17, and the coil 15a.
to the bus bar 3 through a series circuit between the coil 16a and the contacts (fe) of the first changeover switch 17, and a series circuit between the coil 16a and the contacts (ig) of the second changeover switch 18. connected to the capacitor 19
One end on the oscillator 13 side is connected to the bus bar 3 via a resistor 22.
The coil 14 is connected to the coil 14 when the contacts (f-d) of the first changeover switch 17 are closed.
a is connected to the capacitor 19 to form a filter, and the contact point (fe) of the first changeover switch 17
When the gap is closed, the coil 15a is connected to the capacitor 19 to form a filter. When the contacts (i-g) of the second changeover switch 18 are closed, the switch is switched to a second state in which the coil 16a is connected to the capacitor 19 and a filter is formed. switch 1
When the contacts (i-h) of 8 are closed, the circuit is switched to the first state in which a current-carrying path for the timer motor 1c is formed via the busbars 3, 4 and the triax 23. Furthermore, the second changeover switch 1
When coil 8 is switched to the second state, coil 1
Either one of 4a and 15a and the coil 16a are connected in parallel. The switching section 20 also includes the relay 5, and this will be described below. That is, the PNP type transistor 21 has its emitter connected to the bus 3 and its collector connected to the bus 1 via the resistor 24.
2, and a smoothing capacitor 25 is connected in parallel with the resistor 24. Further, a resistor 2 constituting a voltage dividing circuit 26 is connected between the bus bars 3 and 12.
7 and 28 are connected in series. 29 is a comparator whose output terminal is connected to the bus 3 via the excitation coil 5a of the relay 5 and the flywheel diode 30 in parallel, and whose non-inverting input terminal (+) is connected to the collector of the transistor 21;
Moreover, the inverting input terminal (-) is connected to the output terminal of the voltage dividing circuit 26 (the common connection point of the resistors 27 and 28).

On the other hand, the gate of the triax 23 is connected to the resistor 3.
1 and the bus bar 12 via a thyristor 32, the gate of the thyristor 32 is connected to a resistor connected in series between the bus bars 3 and 12 via the normally open side contact (c-a) of the relay contact 5. 33 and 34 are connected to the common connection point. 35 is "high pressure cooking"
This is a light emitting diode for displaying that the switching is being carried out, and its anode is connected to the bus bar 3 via the contacts (i-h) of the second changeover switch 18, and its cathode is connected to the resistor 36 and the diode 8. It is connected to the bus bar 4 via. Reference numeral 37 denotes a light emitting diode for indicating that the "warming operation" is being performed, and its anode is connected to the bus bar 3 and its cathode is connected to the output terminal of the comparator 39 via a resistor 38. 40 is busbar 3 and 12
It is a voltage dividing circuit formed by connecting resistors 41 and 42 in series between them, and a common connection point of the resistors 41 and 42, which is an output terminal, is connected to the inverting input terminal (-) of the comparator 39. The non-inverting input terminal (+) of the comparator 39 is connected to a common connection point between the diode 35 and the resistor 36, and a diode 43 of the polarity shown is connected between this common connection point and the bus bar 12. There is.

Next, regarding the operation of this embodiment with the above configuration, the first
The explanation will be made with reference to FIG. 3, which shows the waveforms at points A and B in the figure. Place the food in the pot, close the lid, and turn the operator 1a of the timer 1 to the "high pressure cooking" side to set the timed operation time appropriately. coil 14a of the cooking temperature detection section 14 by closing the gap between f and d).
and a capacitor 19 form a filter. Then, in response to the rotating operation of the operator 1a, the cam switch 1b of the timer 1 is closed, and in conjunction with this, the contact (i) of the second changeover switch 18 is closed.
-h) is closed, the DC power supply circuit 7 operates at the same time as the cam switch 1b is closed, and a constant DC voltage is now output between the bus bars 3 and 12, and the oscillation circuit 13 is connected to the point A. The pulse signal Po will be output. At this point, the temperature detected by the cooking temperature sensor 14 is lower than 120°C, the inductance of the coil 14a is large, and the coil 14a has a large inductance.
A filter formed by 4a and a capacitor 19 allows the pulse signal Po to pass through. For this reason,
The transistor 21 is periodically turned on and off by the pulse signal Po, and the voltage indicated by the two-dot chain line in FIG. 3B is applied to the collector of the transistor 21, which is the point B in FIG. This voltage is generated every time Po falls, and this voltage is applied to the smoothing capacitor 2.
5 to the voltage V shown by the solid line in FIG. At this time, the voltage dividing circuit 26 is set in advance to output a voltage lower than the voltage V, and therefore the comparator 29 continuously outputs a high level signal. For this reason, the relay 5 is in a state where its excitation coil 5a is de-energized and the relay contact 5b
The normally closed contacts (c and b) of the heater 6 are closed, and therefore, electricity is applied to the heater 6 through the contacts (c and b) and the cam switch 1b, and heating of the pot starts. be done. In addition, when the normally closed side contacts (c and b) of the relay 5 are closed, the thyristor 32 is not triggered, so the try-out 2
3 is also not triggered and therefore timer motor 1c is not energized. This heating causes the temperature of the pot to rise, and the temperature reaches the point at time t ₁ shown in Figure 3.
When the temperature exceeds 120° C., the inductance of the coil 14a decreases rapidly, and the filter formed by the coil 14a and the capacitor 19 blocks the passage of the pulse signal Po, keeping the transistor 21 in an off state. Then, the voltage at point B decreases and the output of the comparator 29 is reversed to a low level signal, so that the excitation coil 5a of the relay 5 is energized and the relay contact 5
The normally open side contacts (ca) of b are closed. Therefore, the heater 6 is cut off, and the thyristor 32 is triggered and turned on, and accordingly, the triax 23 is triggered and the timer motor 1c is energized, thereby starting the timer 1 timer operation. . When the temperature of the pot drops to 120°C or less at time _t2 due to power outage of the heater 6, the inductance of the coil 14a is restored and a pulse signal is generated.
Po is now given to transistor 21,
Therefore, by the same operation as described above, the contacts (c-b) of the relay contact 5b are closed, and the heater 6 is energized again. After this, the heater 6 is repeatedly turned off and energized as described above due to a sudden change in the inductance of the coil 14a according to the pot temperature, and the temperature of the pot is increased by the magnetic member included in the cooking temperature detection section 14. curie point temperature barrel
"High-pressure cooking" is carried out at a temperature controlled around 120℃. Then, when the time limit set in the timer 1 has elapsed, the cam switch 1b is turned off and the "high pressure cooking" ends. Note that when "high-pressure cooking" is started with the contacts (fe) of the first changeover switch 17 closed, the temperature of the pot is determined by the magnetism of the cooking temperature detection section 15, as described above. The temperature is controlled at around 113°C, which is the Curie point temperature of the member, and therefore, in this case, the contact point (f-
d) "High-pressure cooking" is performed at a lower pressure than the state where the gap is closed. Then, in a state in which "high pressure cooking" is performed as described above, that is, in a state in which the contacts (i-h) of the second changeover switch 18 are closed, the light emitting diode 35 is connected to the contact point from the DC power supply circuit 7. (i-h) is energized and lights up,
The display indicates that "high pressure cooking" is being performed. When the light emitting diode 35 is turned on in this way, the light emitting diode 35 and the resistor 36
Since the voltage appearing at the common connection point of is higher than the voltage output from the output terminal of the voltage dividing circuit 40, the comparator 39 is in a state of outputting a high level signal.
Therefore, the light emitting diode 37 for displaying "warming operation"
is never lit.

On the other hand, when performing the "warming operation", the operator 1a of the timer 1 is rotated to the "warming operation" position. Then, the cam switch 1b of the timer 1 is closed, and in conjunction with this, the contacts (i-g) of the second changeover switch 18 are closed, and the coil of the heat-retaining temperature detection section 16 is closed. 16a and the capacitor 19 form a filter. Therefore, the power supply/disconnection of the heater 6 is controlled depending on the heat-retaining temperature detection section 16 in the same manner as in the case of "high-temperature cooking" described above, so that the temperature of the pot is controlled by the heat-retention temperature detection section 16. The "warming operation" is performed by controlling the temperature to around 70°C, which is the Curie point temperature of the magnetic member. Then, in a state in which the "warming operation" is performed in this way, that is, in a state in which the contacts (i-g) of the second changeover switch 18 are closed, the light emitting diode 35 is cut off and turned off. Therefore, the voltage at the common connection point of the light emitting diode 35 and the resistor 36 becomes approximately zero, and the output of the comparator 39 is inverted to low level. Therefore, in response to the inversion of the output of the comparator 39, the light emitting diode 37 is energized by the DC power supply circuit 7 and lights up, thereby providing an indication that the "warming operation" is being performed.

According to the present embodiment described above, when the contacts (i-h) of the second changeover switch 18 are closed for the "keep warm operation", the coil 16a of the keep warm temperature detection section 16 is set to the cooking temperature. Since the coils 14a and 15a of the detection units 14 and 15 are connected in parallel with the coil selected by the first changeover switch 17 and connected to both ends of the capacitor 19, the following effects can be obtained. . That is, in this way, one of the coils 14a and 15a and the coil 1
6a are connected in parallel, whether or not the pulse signal Po from the oscillator 13 is applied to the transistor 21 is determined by the coil 16a whose inductance decreases at a lower temperature (70° C.). The coils 14a, 15a are substantially disconnected from the capacitor 19. Therefore, there is no need for a switch to disconnect the coils 14a, 15a from the capacitor 19, and the circuit configuration can be simplified accordingly. Also, the second
Since the changeover switch 18 is configured to be linked to the time 1 operation, the operability is improved accordingly.

Effects of the Invention According to the present invention, as is clear from the above explanation, reliability is improved by using a temperature sensing section consisting of a coil wound around a magnetic member that causes a rapid change in magnetic permeability at the Curie point temperature. It is possible to provide a temperature control device for a pressure cooker, which has an extremely simple circuit configuration and has effects such as being able to control the temperature of a pot in multiple stages.

[Brief explanation of drawings]

The drawings relate to one embodiment of the present invention.
The figure is an electric circuit diagram, FIG. 2 is a front view of the timer operation part, and FIG. 3 is a waveform diagram of each part in FIG. 1. In the figure, 1 is a timer, 1c is a timer motor, 6 is a heater, 13 is an oscillator, 14 and 15 are cooking temperature detectors, 16 is a heat retention temperature detector, 14a and 15
a, 16a coil, 17 is the first changeover switch,
18 is a second changeover switch, 19 is a capacitor,
20 is a switching section.

Claims (1)

[Scope of utility model registration request] an oscillator; a switching unit that energizes the heater for heating the pot only during a period when the output from the oscillator is input; a timer having a timer motor that turns off the power after a preset time; and the pot. a plurality of cooking temperature sensing parts each having a coil wound around a magnetic member which causes a rapid change in magnetic permeability at mutually different Curie point temperatures; a heat-retaining temperature detecting section formed by winding a coil around a magnetic member having a lower Curie point than the magnetic member of the cooking temperature detecting section, and each of the temperature detecting sections interposed between the oscillator and the switching section. a capacitor that constitutes a filter; a first changeover switch that connects one of the coils of the plurality of cooking temperature detection sections to the capacitor to constitute a filter; and a current-carrying path for the timer motor. and a second state in which a filter is formed by connecting a coil of the heat-retaining temperature detection section to the capacitor, and a second state in which a filter is configured. 1. A temperature control device for a pressure cooker, characterized in that the coils of the heat-retaining temperature detection section and the cooking temperature detection section are connected in parallel when the temperature detection section is switched to a second state.