JPS5830511Y2 - Heat response device for rice cooker - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a thermally responsive device using a combination of a temperature-sensitive magnetic material and a permanent magnet, and more particularly to a thermally responsive device for a rice cooker that is used as a thermostat for a rice cooker and has an automatic expulsion function.

Conventionally, as a thermal response mechanism using a combination of a temperature-sensitive magnetic material and a permanent magnet, a temperature-sensitive magnetic material such as ferrite, which has a Curie point corresponding to the temperature to be detected, is fixed to the heat receiving part, and this temperature-sensitive magnetic material has a A permanent magnet is fixed to a movable plate biased by a spring member in a direction away from this, and the biasing force of the spring member is applied until the saturation magnetic flux density of the temperature-sensitive magnetic body reaches a single point when the temperature of the heat-receiving part reaches a single point. When it exhibits paramagnetism that rapidly decreases,
By setting the permanent magnet together with the movable plate so that it is pulled away from the magnetic attraction when the temperature drops,
There is a device that shuts off the heat source by changing the position of a movable plate, and is used as a thermostat for automatic rice cookers.

By the way, this heat-responsive mechanism is a non-returnable type that does not operate again unless a reset operation is performed once the heat-responsive mechanism is activated, as it is necessary to have both the function of monitoring the cooking state and the safety function of preventing empty cooking.

On the other hand, it is known that preferable rice cooking can be achieved by appropriate additional cooking, that is, by heating the rice again for a short time after the completion of normal rice cooking. However, there are many difficulties in making additional cooking possible.

It is also possible to use an automatic reset type thermal response device to enable additional cooking, but if you want to add a safety function to ensure that the operation stops, a separate temperature controller will be required. Therefore, the circuit becomes complicated.

The present invention aims to provide a heat-responsive device for a rice cooker that uses a non-returnable heat-response mechanism and has an automatic expulsion function and a security function.

The present invention regulates the separation distance of the permanent magnet in the first separation operation of the thermal response mechanism to a position where it can automatically return to the position by magnetic attraction force once the temperature-sensitive magnetic material returns to a ferromagnetic material, and This thermal response device is ideal for use in rice cookers, as it moves the device to a position that is beyond the reach of magnetic attraction during separation.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic cross-sectional view of an electric rice cooker, in which an annular electric heater board 2 is disposed on the inner bottom of the main body 1, and a thermal response mechanism 4 is attached to the center opening so as to come into elastic contact with the bottom surface of the inner pot 3. is,
The switch S1 is opened and closed by the vertical movement of the operating rod, so that the power supply to the electric heater panel 2 can be opened and closed.

FIG. 2 shows a cross-sectional view of an embodiment of the thermally responsive device according to the present invention.

In FIG. 2, a temperature-sensitive magnetic material 7 having a Curie point corresponding to the temperature to be detected is fixed to the bottom surface of the heat receiving plate 6 that closes the upper surface opening of the case 5, and this temperature-sensitive magnetic material 7 has a temperature that is sufficiently higher than the temperature to be detected. A permanent magnet 8 having a single high point is fixed to and facing a movable plate 10 together with a yoke 9, and a spring is provided between the heat receiving plate 6 and the movable plate 10 to bias the permanent magnet 8 away from the temperature-sensitive magnetic body 7. 11 is provided, and furthermore, an operating rod 12 for transmitting this positional displacement to the outside of the case 5 is provided vertically on the movable plate 10, thereby forming a non-return type thermally responsive mechanism 4.

That is, in the case of only this thermally responsive mechanism, the biasing force of the spring 11 and the position of the permanent magnet 8 when separated from the temperature-sensitive magnetic body 7 are determined when the temperature of the heat-receiving part reaches the detected temperature and the temperature-sensitive magnetic body 7 The permanent magnet 8 is pulled away from the temperature-sensitive magnetic body 7 to the bottom position of the case 5 only when the temperature-sensitive magnetic body 7 changes to paramagnetism. The magnetic attraction force that acts is set to be smaller than the biasing force of the spring 11 so that it does not automatically return.

Further, a housing 13 is provided at the bottom of the case 5, and the housing 1
3, the separation distance of the permanent magnet 8 in the first separation movement is regulated to a position where it can automatically return, and the permanent magnet 8 is placed in a position where the original magnetic attraction force does not reach in the next separation movement after automatic return.
As a mechanism for displacing the operating rod 12, a rotating plate 1 cooperates with a protrusion 121 provided on the operating rod 12 to restrict displacement of the operating rod 12.
4 are arranged.

The rotating plate 14 is shown in a perspective view in FIG.
It is attached to the shaft 15 fixed to the housing 13 through a slotted hole 122 provided in the longitudinal direction of the shaft 2, and is loosely fitted to the shaft 15, with one end on the housing 13 side and the other. It is biased in one direction of rotation by a spring 16 having a coil portion whose ends are respectively hooked to protrusions 144 on the rotating plate 14 side, and is biased to come into elastic contact with the operating rod 12. .

Furthermore, a notch 141 extending in the opposite direction to the direction in which the spring 16 is biased is formed on one side edge of the rotating plate 14, and a notch 141 that is centered on the axis 15 is formed on the inner edge of the notch 141 with respect to the axis 15. Two recesses 141a and 141C are provided so as to be located on a circle with radius r1, and the outer edge is located on a circle with radius r2, which is slightly larger than radius r1, and is located midway between recesses 141a and 141C. A recess 141b is provided at the position.

Furthermore, a portion 142 corresponding to the straight line connecting the shaft 15 and the recess 141C in the notch 141 is cut and raised on the side opposite to the operating rod 12.

These recesses 141 a , 141 b , 141 C
The relationship between the permanent magnet 8 and the protrusion 121 is that the set state is when the permanent magnet 8 is attracted to the temperature-sensitive magnetic body 7 and the protrusion 121 is in the recess 141a. 12 is prevented from moving downward at a predetermined position by engagement between the protrusion 121 and the recess 141b, and when the permanent magnet 8 is attracted to the temperature-sensitive magnetic body 7 from this state, the protrusion 121 is fitted into the recess 141C. There is.

FIG. 4 is a diagram showing the structure inside the casing 13 from the right side of FIG. A pin 123 is provided to open and close a limit switch 17 provided in the holder.

Next, FIG. 2 shows the opening/closing operation of the switch 17 according to the state due to the movement of the rotating plate 14 in conjunction with the reciprocating movement of the operating rod 12.
Referring also to Figures 5, 6, and 7, we will explain the thermal response device for a rice cooker and its operation when installed as shown in Figure 1. ″”°”°“゛”“.

14 is shown in a set state where it is locked by the protrusion 121,
In this state, the switch 17 is closed by the pin 123, power is supplied to the electric heater panel 2 of FIG. 1, and the rice cooking operation begins.

As the rice cooks and the water in the inner pot decreases, the temperature of the heat receiving part rises above the boiling point of water, and when the temperature-sensitive magnetic body 7 reaches a single point, the permanent magnet 8 is pulled away from the temperature-sensitive magnetic body 7 by the spring 11. be separated.

As a result, the operating rod 12 moves downward, but at the same time, the rotating plate 14, which is biased to rotate clockwise in the figure, also rotates, and as shown in FIG. 14
1b, and the rotating plate 14 is also prevented from rotating.

Then, the switch 17 is opened by the downward movement of the protrusion 121, the power supply is cut off, and the normal rice cooking operation is completed.

By the way, the separation distance of the permanent magnet 8 at this time is such that when the temperature of the heat-receiving part decreases and the temperature-sensitive magnetic body 7 returns to a ferromagnetic body, the magnetic attraction force that acts between the temperature-sensitive magnetic body 7 and the magnetic body 7 acts on the biasing force of the spring 11. Normally, the distance is set to about several mm so that the permanent magnet 8 can automatically return to the position where it attracts the temperature-sensitive magnetic body 7, and this is the radius r1 from the aforementioned axis 15 to the recess 141a.
It is determined by the difference between the radius r2 and the radius r2 to the recess 14b.

Therefore, when the temperature-sensitive magnetic body 7 exhibits ferromagnetism and the permanent magnet 8 is displaced to the attraction position from the state shown in FIG.
At the same time, the protrusion 121 also moves upward, and during this time the rotating plate 14 also rotates clockwise in the figure, so this time, as shown in FIG.
The protrusion 121 fits into the recess 141C.

Note that, at this time, the rotation plate 14 is partially engaged with not only the protrusion 121 but also the inner wall of the housing 13, thereby being prevented from rotating.

As a result, in the state shown in FIG. 6, the switch 17 is closed again by the pin 123, power supply is resumed, and the additional cooking operation begins.

Thereafter, when the temperature of the heat-receiving part reaches the temperature of the temperature-sensitive magnetic body 7, the permanent magnet 8 is separated from the temperature-sensitive magnetic body 7 again.

Here, by forming the cut and raised portion 142 on the rotary plate 14 directly below the protrusion 121, the protrusion 121
The cut-and-raise portion 142 is easily cut and raised as the operating rod 12 moves downward.
Since the rotating plate 14 is prevented from rotating by the inner wall of the housing 13, the rotating plate 14, which is still in elastic contact with the operating rod 12, is released from the operating rod 12. 14 on the surface facing the operating rod 12, and moves downward to just below the lower edge of the rotating plate 14, as shown in FIG.

As a result, the switch 17 is opened, the power is cut off, and the additional cooking operation is completed.

Note that in order to facilitate the insertion of the projection 121 into the cut and raised portion 142, it is preferable that the tip of the projection 121 be rounded.

In addition, the separation distance of the permanent magnet 8 at this time is such that even if the heat-receiving part temperature decreases and the temperature-sensitive magnetic body 7 returns to a ferromagnetic body, the magnetic attraction force acting between it and the temperature-sensitive magnetic body 7 is smaller than the biasing force of the spring 11. It is set to be small enough so that it does not return automatically.

Therefore, the additional cooking completion state shown in Fig. 7 is a stable state, and unless a reset operation is performed, it will not enter the set state and power will not be supplied. To reset to the set state, the operating rod 12 may be manually moved upward after the temperature-sensitive magnetic body 7 returns to a ferromagnetic body.

That is, since the lower edge of the rotating plate 14 is deformed so as to be inclined toward the notch 141, when the operating rod 12 is moved upward, the protrusion 121 moves toward the inclined edge of the rotating plate 14. 143 and is further moved upward, the rotating plate 14 rotates counterclockwise in the figure against the biasing force of the spring 16 due to the force.

When the protrusion 121 reaches the vicinity of the notch 141, the attractive force between the temperature-sensitive magnetic body 7 and the permanent magnet 8 acts, so the protrusion 121 moves upward rapidly, and when the protrusion 121 enters the notch 141, The rotating plate 14 is rotated clockwise by the spring 16, but the protrusion 121 further moves upward and instantly fits into the recess 141a, and the permanent magnet 8 is also attracted to the temperature-sensitive magnetic body 7, as shown in FIG. It becomes set state.

Checking the set status during such a reset operation is done in the first step.
As shown in the figure, the operating lever 18 is connected to the operating rod 12 so that it can be reset by pressing the push button 19, and the rice cooker main body 1 can be used to cook, recook, stop, etc. depending on the position of the push button 19. There is no need to worry about erroneous operation if you attach this symbol.

Furthermore, the electric circuit can be connected by connecting the switch 17 and the electric heater in series to the power source.

Note that the limit switch 17 does not necessarily need to be provided inside the casing 13; in this case, a long hole is provided in the casing 13, like the hole 122 of the operating rod 12, and the pin 1 is extended to the outside of the casing.
At 23, the switch can be opened and closed outside the housing.

As explained above, according to the present invention, a simple mechanism is provided in which a rotating plate is provided to cooperate with a protrusion provided on an operating rod, and a non-returnable thermal response device is used to remove a temperature-sensitive magnetic material. By regulating the first separation distance of the permanent magnet to a value that allows for automatic return, the rice cooker can be provided with an automatic expulsion function by restarting the power supply by automatic adsorption operation after the end of normal rice cooking operation. Since the second separation distance is a value that cannot be automatically restored, the operation completion state is a stable state and the safety performance is also good.

[Brief explanation of the drawing]

Fig. 1 is a schematic sectional view of an electric rice cooker, Fig. 2 is a longitudinal sectional view of an embodiment of the present invention, Fig. 3 is a perspective view of a rotating plate used in this, and Fig. 4 is a schematic sectional view of an electric rice cooker. Cross-sectional view seen from the right side of the figure,
5, 6, and 7 are longitudinal cross-sectional views showing the embodiment of FIG. 2 in different operating states. In the figure, 4 is a thermal response mechanism, 7 is a temperature-sensitive magnetic material, 8 is a permanent magnet, 11 is a spring, 12 is an operating rod, 14 is a rotating plate, 1
6 is a spring, 17 is a limit switch, 141 is a notch, and 142 is a cut-and-raise portion.

Claims (1)

[Scope of utility model registration request] A thermally responsive device equipped with a thermally responsive mechanism 4 configured to be able to attract and separate a permanent magnet 8 from a temperature-sensitive magnetic body 7 fixed to a heat receiving part 6, and to transmit the displacement of the permanent magnet 8 through an operating rod 12. In the casing 13 provided at the bottom of the thermal response mechanism 4, the shaft 15 is disposed perpendicularly so as not to impede the displacement of the operating rod 12, and is loosely fitted into the shaft 15. A substantially fan-shaped rotating plate 14 is provided,
The rotating plate 14 has three recesses 141 a from one side edge.
, 141b, and 141C are provided, and the lower edge is deformed toward the entrance of the notch 141, and the operating rod 12 is provided with a protrusion 121 that is higher than the plate thickness of the rotating plate 14, and the notch The relationship between the portion 141 and the protrusion 121 is such that the permanent magnet 8 is attracted to the temperature-sensitive magnetic body 7 and the protrusion 121 is
is fitted into the recess 141a as a set state,
The downward movement of the protrusion 121 caused by the first separation movement of the permanent magnet 8 from the set state is stopped by the recess 141b, and the permanent magnet 8
is regulated to a position where it can automatically return based on magnetic attraction force, and when the permanent magnet 8 is attracted from the separated state, the protrusion 121 is fitted into the recess 141C, and the rotation plate 14 is rotated. Furthermore, the rotary plate 14 is provided with a protrusion 121 during the second separation operation of the permanent magnet 8.
The protrusion 121 is provided with a cut and raised portion 142 that allows the downward movement of the protrusion 121.
A thermally responsive device for a rice cooker, characterized in that the is displaced against the elastic contact force of the rotary plate 14 to a position below the lower edge where the magnetic attraction force of the permanent magnet 8 does not reach.