JPH0137927B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a heated object detection device that is incorporated into a heater such as a rice cooker, a rice cooker, or an electric pot.

<Prior art> In a heater such as a rice cooker, if the heating element is energized while the inner pot or other object to be heated is forgotten to be set,
The temperature of each component of the heater may rise abnormally, and in the worst case, it may damage the heater or even cause a fire, so do not start generating heat until you have confirmed that the inner pot or other object to be heated is set. It is requested that the body be energized.

In consideration of such requests, heated object detection devices have traditionally been incorporated into heaters.
Most conventional heated object detection devices have been of the center thermo type. This center thermo type heated object detection device uses a temperature-sensitive magnetic material to detect the presence or absence of an object to be heated, such as an inner pot, and detects the presence of a heated object, such as an inner pot, by detecting a temperature-dependent magnetic change in the temperature-sensitive magnetic material. This is a configuration in which the power to the heating element is cut off by operating a target switch. Therefore, the temperature at which electricity is cut off to the heating element is determined in advance depending on the type of temperature-sensitive magnetic material, and the temperature of the heating element is continuously detected to control the amount of electricity flowing to the heating element. Continuous temperature control is not possible.

In addition, if continuous temperature control is to be possible, a configuration is required in which the presence or absence of the heated object is detected at the bottom of the heated object, and the temperature is detected at the side surface of the heated object to perform temperature control. However, the number of detection points is two, the bottom part of the body to be heated and the side part, which increases the number of parts and increases the cost. There is a problem with temperature detection in terms of accuracy, and furthermore, there is a problem in that it is not possible to accurately detect when the rice is cooked.

In consideration of such problems, the applicant of this patent has provided a pair of contacts below the movable body that moves when the heated body is set, and which turns ON and OFF in accordance with the movement of the movable body. The application was filed for a heated object detection device with a temperature-sensitive element installed on the top of the movable body, but since the contact is located outside the movable body, the contact deteriorates due to adhesion of boiled liquid, dust, etc., and contact deterioration due to impact, resulting in poor durability. In addition, since the movable body and the contact points are separate bodies and cannot be made into a unit, not only is there a limit to miniaturization, but assembly is time-consuming, which poses problems in terms of productivity and cost. Ta.

As a detection device that addresses such problems, there is a heated object detection device disclosed in Japanese Utility Model Application Laid-Open No. 57-81279. As shown in FIG. 7, this heated object detection device is provided below an inner pot 81 and has a heat-sensitive element 84 inside and above a movable body 83 that is moved up and down by the inner pot 81. A movable contact 85 is connected to both ends of this heat-sensitive element 84. This movable contact 85 is attached along the upper surface of a lower plate 86 that constitutes the movable body 83, and a fixed shaft 87 passing through the center of the lower plate 86 is attached to the lower plate 86. It is attached so that it can be moved relatively. The fixed shaft 87 has a fixed contact 88 passing through the inside thereof in the vertical direction,
The upper end of the fixed contact 88 is configured to be able to freely come into contact with and separate from the movable contact 85.

In this heated object detection device, the inner pot 81
is not set, the external spring 89 inserted between the rice cooker main body 82 and the bottom plate 8
The movable body 83 is raised by the internal spring 90 inserted between the fixed shaft 87 and the fixed shaft 87, so that the fixed shaft 87 is relatively moved to a lowered position, and the fixed contact 88 is moved to the movable contact 85. become estranged from.

Conversely, when the inner pot 81 is set, the movable body 83
As the movable contact 85 is lowered, the fixed shaft 87 is relatively raised, and the fixed contact 88 comes into contact with the movable contact 85 and pushes it up. Therefore, the heat sensitive element 84 is connected to an external temperature detection heater etc. through these contacts 85 and 88, and the setting of the inner pot 81 is detected and temperature detection is started.

<Problems to be Solved by the Invention> However, in the above detection device, the contacts 85,
When 88 is turned on, the movable contact 85 is deformed by the same amount as the movement of the fixed shaft 87.
The disadvantage is that the amount of deformation is large. For this reason,
As the movable contact 85 is repeatedly deformed, its restoring force gradually decreases, and the movable contact 85 does not return to its original state even though the fixed contact 88 is not in contact with it. Therefore, even if an object to be heated such as the inner pot 81 is set, if the contacts 85 and 88 are not electrically connected, or if the set inner pot 81 moves even slightly, a connection failure between the contacts 85 and 88 may occur. There is a problem that this may occur.

Furthermore, since both of the contacts 85 and 88 are structured to turn on when the inner pot 81 is set, they are always energized during use, which eliminates the problem of premature deterioration of the contacts. be.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, an object of the present invention is to provide a heated object detection device that can improve the durability of the contacts and effectively prevent connection failures of the contacts.

<Means for Solving the Problems> In order to achieve the above object, the heated object detection device of the present invention includes: In addition to providing a temperature sensing element and a pair of contacts, one end of a fixed shaft that connects and separates the contacts by relative movement with the movable body is introduced into the space, and the distance between the contacts gradually becomes smaller as they move downward. It is formed of two elastic pieces arranged opposite each other so as to be narrow, and when the object to be heated is not set, it contacts both elastic pieces and presses the elastic pieces in a direction away from each other, and when the object to be heated is set, A short circuit member separating from the elastic piece is provided at one end of the fixed shaft.

<Function> According to the heated object detection device configured as described above, the pair of contacts is formed by two elastic pieces that are arranged opposite each other so that the distance between them gradually narrows as they go downward;
Moreover, since the shorting member is arranged to press these elastic pieces in the direction away from each other, when the shorting member moves with the relative movement of the fixed shaft, the amount of movement of the elastic pieces is smaller than the amount of movement of the intertwining member. The amount of deformation can be reduced.

In addition, the shorting member moves in close contact with the elastic piece, and the distance between the elastic pieces becomes narrower as they move downward, so the close contact between the shorting member and the elastic piece becomes stronger, and poor contact between the two is effectively prevented. can be prevented.

Furthermore, the short-circuiting member is used when setting the object to be heated.
Since it is separated from the elastic piece, no current flows through the contact when the heating element is activated, and deterioration of the contact can be almost eliminated.

<Example> Next, an example of the present invention will be described below with reference to the drawings.

FIG. 1 is a longitudinal sectional view showing a heated object detection device as an embodiment of the present invention.

This heated object detection device includes a cylindrical outer case 1 with a bottom, a heating element 2 that supports the outer case 1 in a suspended state in the center, and a cylindrical movable body provided inside the outer case 1 so as to be able to rise and fall. body 3, a coil spring 4 that imparts elasticity in the direction of pushing the movable body 3 out of the outer case 1, a pair of contacts 5 provided within the movable body 3, and a temperature sensing element provided at the upper part of the movable body 3. 6, and a fixed shaft 7 for bringing the contact 5 into and out of contact with each other.

The outer case 1 has an outward facing flange 11 at the upper end.
It is supported by the heat generating element 2 in a suspended state by this collar part 11, and has an outwardly extending raised part 11a at a predetermined position on the side wall, and this outwardly facing raised raised part 11a and the above-mentioned The heating element 2 is sandwiched between the flange 11 and the outer case 1 is securely fixed.

The heating element 2 is configured to function as a planar heating element by embedding, for example, a nichrome sheathed heater (not shown) in a predetermined position.

The movable body 3 has an upper plate 12 made of a material with high thermal conductivity and a lower plate 13 made of, for example, glass epoxy. 6 is installed. The side plate 15 is formed to hang down from the end of the fixture 14.

The lower plate 13 is formed to have a thin wall at the peripheral edge and a thick wall at the center, and is provided with a center hole 16 that passes through the fixed shaft 7 at the center of the thick wall, and a pair of contact points. A pair of insertion holes 17, 17 are provided sandwiching the center hole 16 in order to insert the contact bases 5a, 5a supporting the contacts 5, 5.

The contact bases 5a, 5a are connected to the through holes 17,
It is inserted into and supported by the center hole 17, and the upwardly projecting portion is bent at right angles toward the center hole 16. The contacts 5, 5 are connected to this contact base 5.
It is provided continuously at the end portions a and 5a, and consists of two elastic pieces facing each other such that the distance between them gradually narrows as the tip side goes downward. Note that the contact bases 5a, 5a are the contact bases 5a, 5a,
It is integrally formed from the same material as 5. and,
The contact bases 5a, 5a are formed by pulling out and raising inward predetermined positions that protrude downward from the insertion holes 17, 17.
The contact base portions 5a, 5a are prevented from being pulled out by contacting with a recess 13a formed on the lower surface of the contact base portions 5a, 5a.

The fixed shaft 7 is inserted between the contacts 5, 5,
One end thereof is introduced into the movable body 3. A short-circuiting member 20 is attached to one end of the fixed shaft 7 so as to be able to come into contact with and separate from the contacts 5, 5.

The short-circuiting member 20 is made of a good conductor such as metal, and the sides that contact the contacts 5 are each spherical. Then, when the movable body 3 is raised by the spring force of the coil spring 4, that is, when an object to be heated such as an inner pot is not set as described later, the short-circuiting member 20
It is formed in a size that can contact both contacts 5, 5 and separate them from each other, and can make both contacts 5, 5 electrically conductive.

Conversely, when the object to be heated is set, as shown in FIG. 5, 5 are separated from each other, and the fixed contacts 5, 5 can be turned off.

The connection between the movable body 3 and the lower plate 13 is achieved by forming a flange 3a inwardly bent at a predetermined position on the lower part of the movable body 3 and a recess 13b formed at a predetermined position on the lower face of the lower plate 13.
This is achieved by fitting the flange 3b into the lower part of the movable body 3 at a predetermined position on the lower part of the movable body 3 and bringing it into contact with the upper surface of the lower plate 13 at a predetermined position.

The temperature sensing element 6 is composed of an element whose resistance value changes depending on the temperature, such as a positive characteristic thermistor or an uncharacteristic thermistor.

The operation of the heated object detection device having the above configuration is as follows.

When an object to be heated such as an inner pot is not set, the upper part of the movable body 3 protrudes above the top surface of the heating element 2 due to the elastic force of the coil spring 4, as shown in FIG. In this state, as described above, the shorting member 20 is sandwiched between the contacts 5, 5 by the fixed shaft 7, and the contacts 5, 5 are pressed in the direction away from each other by the shorting member 20. It has become
The short-circuiting member 20 brings both contacts 5, 5 into conduction with each other, and turns the contacts into an ON state.

On the other hand, when the object to be heated 10 such as the inner pot is set, as shown in FIG. The member 20 is the contact point 5,5
Move away from the terminal and turn the contact OFF.

Therefore, it is sufficient to connect the switch 55 formed by the contacts 5, 5 in parallel with the temperature sensing element 6, for example, and only when the switch 55 is OFF, the heating element is activated depending on the resistance value of the temperature sensing element 6. 2 can be activated. Further, in this embodiment, since the contacts 5, 5 are provided inside the movable body 3,
Not only is it possible to reliably protect against boiling, etc. from the heated object 10 and significantly reduce the risk of malfunction, but also the contacts 5, 5 and the temperature sensing element 6 are integrated with the movable object 3. Since it can be made into a unit, it is possible to reduce the size and simplify the assembly.

Further, even if the movable body 3 is slightly lowered due to foreign matter, the contacts 5, 5 can be kept in the ON state, and the heating operation can be reliably prevented.

Furthermore, when the fixed contact shaft 7 moves relative to each other, the shorting member 20 moves while keeping the surfaces of the contacts 5, 5 in close contact with each other. can be prevented. Moreover, since the short-circuiting member 20 contacts the contacts 5, 5 in a state where they are pressed in directions away from each other,
Electrical connection between the two will be established reliably. Further, due to the relative movement of the fixed shaft 7, even if the amount of movement of the shorting member 20 in the axial direction of the fixed shaft 7 is large, the amount of deformation of the contacts 5, 5 will be
The amount of deformation of the contacts 5, 5 can be set to the minimum necessary.

FIG. 3 is a longitudinal cross-sectional view showing another embodiment of the heated object detection device, which differs from the embodiment shown in FIG. 1 in the configuration of the movable body 3, the bottom plate, the attachment of contacts, etc. .

Since this heated object detection device is similar to the above-mentioned embodiment, the same parts will be given the same reference numerals and only the different constituent parts will be explained.

The movable body 3 includes a side plate 31 integrally with a top plate 31a.
A bottom plate 32 is inserted into an outer plate 31 which is formed by hanging down b and also serves as a main body cover,
The pair of contacts 5, 5 are supported by the lower plate 32, and a fixed shaft 7 for supporting the shorting member 20 is provided passing through the lower plate 32. The lower plate 32 is formed to have a thick peripheral edge and a thin central area, and in particular, the peripheral edge is formed to have a thickness substantially equal to the height of the side plate 31b. Then, an insertion hole 33 for the contact bases 5a, 5a is provided in this thick part, and a center hole 3 through which the fixed shaft 7 passes is provided in the center of the thin part.
There are 4. The contact base portions 5a, 5a have a portion that protrudes upward from the insertion hole 33 and is bent inward along the upper surface of the thick portion of the bottom plate 32, and a portion of the contact base portion 5a that protrudes upward from the insertion hole 33 is bent inward along the upper surface of the thick portion of the bottom plate 32. Contact points 5, 5 formed of two elastic pieces are provided facing each other so that the distance between them gradually becomes narrower, and the contacts 5, 5 and the shorting member 20 are configured to be able to come into contact with each other. Further, an annular recess 35 is formed on the lower surface of the lower plate 32, and the outer case 1
A spring receiving portion 36 is formed at a predetermined position on the bottom surface of the coil spring 4 , and the coil spring 4 is provided between the annular recess 35 and the flare receiving portion 36 .

Note that the contact bases 5a, 5a are provided with raised parts 5b, 5b which are cut out and formed at predetermined positions, and these raised parts 5b, 5b are formed in the recessed part 32a formed on the lower surface of the bottom plate 32. The contact bases 5a, 5a are brought into contact with each other to prevent them from slipping out.

Therefore, in this embodiment as well, contacts 5 and 5 are turned OFF when the object to be heated is set, and contacts 5 and 5 are turned ON when the object to be heated is not set, and the object to be heated is turned OFF as in the above embodiment. Only when set, the heating element can be activated depending on the resistance value of the temperature sensing element.

FIG. 4 is a longitudinal sectional view showing an embodiment in which a heated object detection device is incorporated into a rice cooker.

41 is an outer case of the rice cooker, 42 is an inner pot storage container, 43 is a heat insulating material interposed between the outer case 41 and the inner pot storage container 42,
44 is an inner pot, 45 is a heating element that heats the inner pot 44 while supporting it, 46 is a nichrome sheathed heater embedded in the heating element, 47 is an inner pot detection device, and 48 is a lid. unit, 4
9 is a rice cooking switch. 60 is a lid heater, 61 is a one-touch pin, 62 is a pot lid, 63 is a heat-retaining heater, 64 is a temperature sensor, and 65 is a cord reel. Then, the inner pot detection device is installed inside the movable body that moves when the inner pot is set, and turns on and off in accordance with the movement of the movable body.
Specifically, the configuration is the same as that of the heated object detection device shown in the embodiment of FIG. 1 or 3.

FIG. 5 is an electrical circuit diagram of the rice cooker shown in FIG. 4.

51 is a comparator, to which a reference voltage is applied to the non-inverting input terminal through resistors 52 and 53;
4 and a temperature sensing element 6 composed of an NTC thermistor or the like, a voltage depending on the temperature of the inner pot 44 is applied to the inverting input terminal. A switching transistor 56 is given a base bias by a resistor 57 and the output terminal of the comparator 51, and a capacitor 58 for storing the cooking state is connected between its collector and emitter terminals.

Reference numeral 59 denotes a comparator, whose inverting input terminal is supplied with a reference voltage by resistors 70 and 71, and whose non-inverting input terminal is supplied with a state determination voltage by the terminal voltage of the capacitor 58. 72 is a switching transistor, resistor 73 and comparator 59
base bias is given by the output terminal of
A relay coil 74 is connected to the collector terminal. The relay contact 75 driven by the relay coil 74 can control energization of the rice cooking circuit (not shown).

In addition, 55 is turned off when the inner pot 44 is set.
This switch is turned on when the inner pot 44 is removed, and is composed of a pair of contacts 5, 5, which are connected in parallel to the capacitor 6 with a resistor 76 interposed therebetween.

Further, a capacitor 58 is connected to the positive voltage terminal Vcc with a rice cooker switch 49 and a resistor 77 interposed in series.

The operation of the rice cooker with the above configuration is as follows.

After putting rice and water in the inner pot 44 and setting it in the inner pot storage container 42, the lid unit 48 is closed to complete the preparation for the rice cooking operation. That is, the inner pot 44
By setting the inner pot detection device 47, the inner pot detection device 47 is lowered, and the connection between the pair of contacts 5 and 5 of the switch 55 is made.
Turn it OFF.

Then, while the temperature of the inner pot 44 is low, the comparator 51
outputs a low level signal to turn off the switching transistor 56, and if the temperature of the inner pot 44 rises, the comparator 51 outputs a high level signal to turn on the switching transistor 56.

Therefore, when the rice cooking switch 49 is turned on after the preparation for rice cooking is completed, the capacitor 58 changes to the power supply voltage.
The comparator 59 outputs a high level signal and turns on the switching transistor 72.
Therefore, the relay contact 75 is turned on, the rice cooker circuit is energized, and the rice and water in the inner pot 44 can be heated by the heating element 45.

When the temperature of the inner pot 44 rises to a predetermined temperature, the comparator 51 outputs a high level signal to turn on the switching transistor 56 and discharge the storage body of the capacitor 58, so that the comparator 59
outputs a low level signal and turns off the switching transistor 72, thereby turning off the relay contact 75, thereby cutting off electricity to the rice cooking and completing the rice cooking operation.

Also, if you take out the inner pot 44 during the rice cooking operation,
Since the switch 55 is turned on and the capacitor 58 is discharged, the rice cooking operation can be stopped.

Furthermore, even if the rice cooking switch 49 is turned on without setting the inner pot 44 at all, the pair of contacts 5 and 5 of the switch 55 are turned on and the capacitor 58 is short-circuited via the resistor 76, so no rice cooking is performed. Can prevent empty cooking.

FIG. 6 is an electrical heating diagram showing another configuration of the rice cooker. The difference from the electrical heating diagram in FIG. There are only points.

Therefore, in this case, the switch 55
Even if it is turned on, the accumulated charge in the capacitor 58 cannot be directly discharged, but it is possible to short-circuit both terminals of the temperature sensing element 6 and turn on the switching transistor 56 to discharge the accumulated charge in the capacitor 58. It works in the same way as the electrical circuit diagram shown in FIG.

<Effects of the Invention> As described above, according to the heated object detection device of the present invention, a pair of contacts is formed of two elastic pieces that are arranged opposite to each other so that the distance gradually narrows as one goes downward. Moreover, since the shorting member is arranged to press these elastic pieces in the direction away from each other, when the shorting member moves with the relative movement of the fixed shaft, the amount of movement of the elastic piece is smaller than the amount of movement of the shorting member. The amount of deformation can be reduced, and the durability of the elastic piece can be improved.

Furthermore, since the shorting member can be moved in close contact with the elastic piece, poor contact between the contacts can be effectively prevented.

Furthermore, the short-circuiting member is used when setting the object to be heated.
Since it separates from the elastic piece, no current flows through the contact when the heating element is activated, which has significant effects such as almost eliminating deterioration of the contact itself and improving durability.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing a heated object detection device as an embodiment of the present invention, FIG. 2 is a longitudinal sectional view showing a state in which a heated object is set in the heated object detection device, and FIG. The figure is a longitudinal sectional view showing a heated object detection device as another embodiment of the present invention, FIG. 4 is a longitudinal sectional view showing an embodiment in which the heated object detection device is incorporated into a rice cooker, and FIG. FIG. 4 is an electric circuit diagram of the rice cooker, FIG. 6 is an electric circuit diagram showing another configuration of the rice cooker, and FIG. 7 is a longitudinal cross-sectional view of a conventional heated object detection device. 3...Movable body, 5...Contact, 6...Temperature sensing element,
7...Fixed shaft, 10...Non-heating body, 12...Top plate, 13...Bottom plate, 15...Side plate, 20...
Shorting member.

Claims (1)

[Claims] 1 A heated device that has a movable body that moves when the heated body is set, is provided with a pair of contacts that turn ON and OFF in accordance with the movement of the movable body, and is equipped with a temperature sensing element that detects the temperature of the heated body. In a body detection device, a temperature sensing element and a pair of contacts are provided in a space surrounded and formed by a top plate, a side plate, and a bottom plate of a movable body, and the contacts are connected and separated by relative movement with the movable body. One end of the fixed shaft is introduced into the space, and the contact point is formed by two elastic pieces facing each other so that the distance gradually narrows toward the bottom. , characterized in that a short-circuiting member is provided at one end of the fixed shaft, which contacts both elastic pieces and presses the elastic pieces in a direction away from each other, and separates from the elastic pieces when the object to be heated is set. Heated object detection device.