JPH0222568Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial application field This invention allows the heating plate to be controlled by a reed switch operated by a permanent magnet provided at the center of the bottom of the outer pot by placing an inner pot on it. Regarding a cooker temperature sensor for preventing overcooking.

BACKGROUND ART A conventional temperature sensor for a cooking device has an outer case 7 provided in the center of an annular heating plate 12 with a built-in heater in the inner bottom of an outer pot (not shown) as shown in FIG. Heat sensitive body 1 that moves up and down inside
A heat detection element 3 such as a thermistor fixed in the surface of the upper lid plate 11 detects the temperature of the cooked food in an inner pot (not shown) placed on the heat sensitive element 1, and a control circuit is activated. energization of the hot plate 12 is controlled. Two elongated parallel rod-shaped recesses 21 are provided at a predetermined interval on the inner bottom of the case 2 of the heat sensitive element 1.
21' is provided, and an elongated hole 22 is inserted between the recesses 21 and 21', and a rod-shaped permanent magnet 4 is installed in the recess 21, and a normally open reed switch 8 is installed in the other recess 21'. The upper part of the case 2 is covered with an upper cover plate 11. A compression coil spring 6 is embedded in the central part of the hot plate 12 to constantly raise the heat sensitive element 1 along the inner periphery of the outer case 7.
A magnetic shielding plate 2 is provided on the bottom inner surface of the outer case 7 and penetrates into an elongated hole 22 formed in the bottom surface of the heat sensitive element 1.
3 are erected.

When the inner pot is not placed inside the outer pot, that is, in the state shown in the figure, the magnetic flux from the permanent magnet 4 affects the reed switch 8, and the contact of the reed switch 8 is in the closed state, and the heat detection element 3 The operation of the control circuit is stopped regardless of the temperature detection signal, and the hot plate 1
The power supply to 2 is cut off. However, when the inner pot is placed inside the outer pot for cooking, the bottom of the inner pot touches the upper lid plate 11 of the heat sensitive element 1 and the heat sensitive body 1 is lowered, causing the magnetic shielding plate 23 on the bottom of the outer case 7 to The magnetic flux from the permanent magnet 4 to the reed switch 8 is cut off, the reed switch 8 is placed in an open state, the control circuit is activated, and the hot plate 12 is energized. Also, the heat detection element 3
detects the temperature of the inner pot, and the supply of electricity to the hot plate 12 is controlled. Therefore, if you remove the inner pot while the current is on, the heat sensitive element 1
increases, the magnetic flux from the permanent magnet 4 affects the reed switch 8, the reed switch is closed again, the control circuit stops operating, and the hot plate 12
Power is cut off and the temperature sensor works as a safety device.

Problems to be Solved by the Invention In the temperature sensor conventionally used as a safety device for cooking appliances, the reed switch 8 and the permanent magnet 4 are both rod-shaped, and are placed horizontally in parallel within the bottom of the case 2 of the heat-sensitive element 1. It is placed so as to be perpendicular to the direction in which the heat sensitive body 1 moves forward and backward. Therefore, due to non-uniform spacing between the permanent magnet 4 and reed switch 8 that occurs during installation, or lateral positional deviation of the heat sensitive element 1 when the heat sensitive element 1 moves up and down, the permanent magnet flowing to the reed switch 8 is This causes a change in the amount of magnetic flux from 4. Furthermore, since the magnetic shielding plate 23 penetrates into the elongated hole 22 between the reed switch 8 and the permanent magnet 4, the width of the elongated hole 22 must be made wide, and the permanent magnet 4 is Since the reed switch 8 is fixed on one side, the reed switch 8 is affected by the magnetic flux only from one side, and the magnetic flux from the permanent magnet 4 cannot efficiently flow into the reed switch 8. Therefore, it is necessary to select the material, size, etc. of the permanent magnet 4 so that the amount of magnetic flux is large.

In addition, the reed switch 8 is a heat sensitive body 1 that moves forward and backward.
Since the reed switch 8 is disposed in the reed switch 8 and its direction of movement is perpendicular to the longitudinal direction, the reed switch 8 may be permanently strained by the impact when the inner pot is moved in and out of the outer pot, changing its operating characteristics and sometimes causing breakage or failure. There are drawbacks to its operation.

Means for Solving the Problems The present invention eliminates the above drawbacks of the conventional method and solves the problems.
As shown in the figure, there is an annular permanent magnet 4 magnetized in the thickness direction at the center of the outer case 7, which is vertically installed from the center of the hot plate 12, and a circular permanent magnet 4 that is magnetized in the thickness direction, and is placed in the center hole in parallel with the vertical direction and the longitudinal direction. This is a temperature sensor in which a reed switch 8 is disposed, and a magnetic shielding cylinder 10 is vertically disposed above or below the upper inner surface of a heat sensitive body 1 supported by an outer case 7.

Function The contacts of the reed switch 8, which is disposed longitudinally in the vertical direction of the heat-sensitive element 1, are affected by the magnetic flux from the annular permanent magnet 4, but when the heat-sensitive element 1 descends, the reed switch 8 and the magnetic shielding cylinder At the same time, the magnetic shielding cylinder is lowered and inserted between the reed switch 8 and the permanent magnet 4, and the change in the amount of magnetic flux causes the contacts of the reed switch 8 to be switched, and the control circuit begins to operate.

Embodiment An embodiment of the temperature sensor for a cooker according to the present invention is shown in FIGS. 1 and 2. As shown in the drawing, there is an annular permanent magnet 4 magnetized in the thickness direction at the center of the bottom surface of the outer case 7, which is vertically disposed from the center of the hot plate 12.
is fixed thereto, and a through hole 13 extending along the inner wall of the permanent magnet 4 is provided in the center of the bottom of the outer case 7. Heat sensitive body 1 that moves up and down inside the outer case 7
The bottom of the case 2 has a hole 14 having a diameter larger than the outer diameter of the permanent magnet 4, and the upper surface of the case 2 is covered with an upper cover 11 made of a material with good thermal conductivity. The heat detection element 3 is fixed by a fixture 9, and a protective tube 5 made of a non-magnetic material penetrates into a hole 14 in the bottom of the case 2 from the center of the lower surface of the fixture 9 and is vertically provided therein. This protection tube 5
A cylindrical magnetic shielding tube 10 made of a magnetic material with a length that does not reach the permanent magnet 4 is provided around the outer periphery of the protective tube 5, and the contact position is located at the center of the magnetic pole of the permanent magnet 4 within the protective tube 5. Thus, the longitudinal direction of the reed switch 8 is fixed in the axial direction of the protection tube 5. A coil spring 6 is provided between the outer wall of the heat sensitive element 1 and the inner wall of the outer case 7 to constantly raise the heat sensitive element 1.

When the inner pot is not placed on this temperature sensor and the heat sensitive element 1 is in the raised position as shown in Fig. 2, the permanent magnet 4
Since the contact point of the reed switch 8 and the contact point of the reed switch 8 are at the same position and the magnetic shielding cylinder 10 is not inserted between them, the magnetic flux from the permanent magnet 4 flows into the reed switch 8, which is in the closed state, and the heat detection element 3 is in the closed state. Regardless of whether the temperature detection signal is output or not, the operation of the control circuit is stopped and the power supply to the hot plate 12 is cut off. Here, when the inner pot is placed on the heat sensitive element 1, as the heat sensitive body 1 descends as shown in Fig. 3, the magnetic flux flowing into the reed switch 8 from the permanent magnet 4 rapidly decreases.
The reed switch 8 becomes open. Here, referring to FIGS. 4 and 5, FIG. 4 shows that when the center position of the permanent magnet 4 is at the position surrounded by diagonal lines,
Indicates that the contact of reed switch 8 is closed,
Further, FIG. 5 shows that when the shield tube 10 is present, the closed region near the shield tube 10 becomes the open region. Therefore, when the heat sensitive element 1 descends to a certain extent, as shown in FIG. 4, a magnetic flux flows into the reed switch 8 with the opposite polarity to the magnetic flux that flows into the reed switch 8 from the permanent magnet 4 when the heat sensitive body 1 is in the ascending position. , it becomes closed again. Therefore, as in the present invention, by inserting the magnetic shielding cylinder 10 between the reed switch 8 and the permanent magnet 4, the permanent magnet 4
The magnetic flux of opposite polarity flowing from the reed switch 8 is sucked in, and as shown in FIG. 5, the reed switch 8 is kept open and the hot plate 12 is energized via the control circuit. Conversely, when the heat sensitive element 1 rises, the magnetic flux flowing into the reed switch 8 suddenly increases, causing the reed switch 8 to
becomes a closed state.

Therefore, in the present invention, a permanent magnet 4 having a large amount of magnetic flux is used, so that a large amount of magnetic flux flows efficiently through the reed switch 8, and the switching of the contacts is reliable.
In addition, since the permanent magnet 4 is attached to the outer case 7 in a direction perpendicular to the moving direction of the heat sensitive element 1, the amount of magnetic flux flowing into the reed switch 8 is reduced in response to vibrations caused by the upward and downward movement of the heat sensitive body 1. Less susceptible to change. In addition, since the length direction of the reed switch 8 coincides with the advancing and retracting direction of the heat sensitive body 1, the impact resistance of the reed switch 8 is increased.

In the above embodiment, the reed switch 8 is in the closed state when the heat sensitive element 1 is in the ascending position, and the control circuit is inoperative and inoperative when the reed switch 8 is in the open state when it is in the descending position. However, as in the other embodiments shown in FIG. 6 and FIG. When fixed, the reed switch 8 is in an open state when the heat sensitive body 1 is in the ascending position, and is in a closed state when it is in the descending position. In addition,
In FIGS. 6 and 7, the position of the shielding cylinder 10 is reversed compared to the previously described FIGS. 2 and 3,
In the case of FIG. 6, the reed switch is open, and in the case of FIG. 7, the reed switch is closed.

Effects of the invention As described above, according to the invention, the effect of lateral vibration when the heat sensitive element 1 moves forward and backward is small, the reed switch 8 can be switched reliably, and the cooking device is highly reliable and can withstand shocks. can be obtained.

[Brief explanation of the drawing]

Fig. 1 is an exploded perspective view of an embodiment of the temperature sensor for a cooker according to the present invention, Fig. 2 is a vertical cross-sectional front view of the temperature sensor of the present invention when the heat-sensitive element is in the ascending position, and Fig. 3 is the heat sensor in Fig. 2. FIG. 4 is a longitudinal sectional front view when the body is in a lowered position, FIG. 4 is a diagram of the closing/opening area of the contact of the reed switch 8 when there is no magnetic shield tube in the temperature sensor according to the present invention, and FIG. 5 is a temperature diagram according to the present invention. FIG. 6 is a longitudinal sectional front view of another embodiment of the present invention when the heat sensitive element is in the raised position;
FIG. 7 is a longitudinal sectional front view when the heat sensitive body in FIG. 6 is in a lowered position, and FIG. 8 is a longitudinal sectional front view of an example of a temperature sensor in a conventional cooking appliance. In addition, 1... Heat sensitive body, 2... Case of heat sensitive body 1, 3... Heat detection element, 4... Permanent magnet, 5...
Protection tube, 6...Coil spring, 7...Outer case, 8
... Reed switch, 10 ... Magnetic shielding tube, 11
... Upper cover plate, 12 ... Heat plate, 13 ... Through hole,
14...hole, 21, 21'...recess, 22...elongated hole, 23...shielding plate.

Claims (1)

[Claims for Utility Model Registration] Permanent magnet 4 is activated by the temperature detection signal from the heat detection element 3 disposed in the heat sensitive body 1, which moves up and down depending on whether or not a heated object is mounted, and by the vertical movement of the heat sensitive body 1.
In a temperature sensor for a cooker, in which energization to a heating hot plate 12 is controlled by switching the contacts of a reed switch 8 that undergoes changes in magnetic flux, the bottom surface of the outer case 7 of the heat sensitive element 1 has an annular shape and a thickness A permanent magnet 4 magnetized in the direction is arranged, a contact point of a reed switch 8 is opposed to the center of the permanent magnet 4, and the reed switch 8 is moved in the axial direction in the vertical direction of the heat sensitive body 1, A cooker comprising a cylindrical magnetic shielding cylinder 10 made of a magnetic material that magnetically shields between the permanent magnet 4 and the reed switch 8 from an upper lid body 11 that covers the upper part of the heat sensitive element 1. Temperature switch.