JPH0222567Y2 - - 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. This invention relates to a temperature sensor for a cooker that prevents cooking.

BACKGROUND TECHNOLOGY As shown in FIG. 6, a conventional temperature sensor for a cooker is installed in an outer case 7 provided in the center of an annular heating plate 12 which has a built-in heater in the inner bottom of an outer pot (the same applies hereafter). The cooking inside the inner pot (not shown) placed on the heat sensitive body 1 is detected by the heat detection element 3, which is like a thermistor fixed in the surface of the upper cover plate 11 of the heat sensitive body 1, which moves up and down. The temperature of the product is detected and controlled by a control circuit to control energization of the hot plate 12. Two elongated parallel rod-shaped recesses 21, 2 are provided at a predetermined interval on the inner bottom of the case 2 of the heat sensitive element 1.
1' 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 provided in the center of the heat plate 12 to constantly raise the heat sensitive element 1 along the inner periphery of the outer case 7, and a compression coil spring 6 is provided in the bottom of the outer case 7 to keep the heat sensitive element 1 elevated at all times along the inner periphery of the outer case 7. A magnetic shielding plate 23 is erected to penetrate into the elongated hole 22.

When the inner pot is not placed in 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 opened, 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 8 is closed again, the control circuit stops operating, and the hot plate 1
The power supply to 2 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 and 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 to 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 disposed on the heat sensitive body 1 that moves up and down, and the direction of movement thereof is perpendicular to the longitudinal direction, so that the reed switch 8 is permanently deformed by the impact when the inner pot is put in and taken out of the outer pot. There are drawbacks that can occur, change the operating characteristics, and sometimes even lead to damage or non-operation.

Means for Solving the Problems The present invention eliminates such drawbacks of the conventional method and eliminates the drawbacks shown in Fig. 1 and 2.
As seen in the figure, there is an annular permanent magnet 4 magnetized in the thickness direction at the center of the bottom surface of the case 2 of the heat sensitive element 1, which moves up and down depending on the presence or absence of an object to be heated such as an inner pot, and its center hole. This is a temperature sensor in which a reed switch 8 is disposed in parallel in the vertical direction and the longitudinal direction, and a magnetic shielding tube is erected at the lower center of an outer case 7 that supports a heat sensitive element 1.

Function The contact point of the reed switch 8 whose longitudinal direction is arranged in the vertical direction of the heat sensitive element 1 is influenced by the magnetic flux from the annular permanent magnet 4, but when the heat sensitive element 1 is lowered, the reed switch 8 and the permanent magnet The reed switch 8 and the permanent magnet 4 are magnetically shielded by a magnetic shielding tube that descends together with the magnet 4 and stands upright on the outer case 2, and the amount of magnetic flux changes to switch the contacts of the reed switch 8. , the control circuit becomes operational.

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, a case 2 with a through hole 13 formed in the center of the bottom surface is covered with an upper lid 11, and an annular permanent magnet 4 magnetized in the thickness direction is fixed to the center of the bottom surface of the case 2. The heat detection element 3 is fixed to the inner lower surface of the upper cover plate 11 made of a material with good thermal conductivity by a fixing fitting 9, and a cylindrical protection tube 5 made of a non-magnetic material is fixed to the fixing fitting 9. The heat sensitive body 1 is thus formed. The protective tube 5 has a diameter sufficiently smaller than the inner diameter of the permanent magnet 4 and has a length that slightly protrudes outside the bottom surface of the case 2. Reed switch 8 connects the contact to protection tube 5
It is fixed in the protective tube 5 so that it is located opposite the center of the magnetic pole of the permanent magnet 4 within the protective tube 5, and its longitudinal direction is parallel to the direction of vertical movement of the heat sensitive element 1. Further, a through hole 14 through which the protective tube 5 can move in and out is provided in the bottom surface of the outer case 7, which is fixed to the center of the hot plate 12 and holds the heat sensitive element 1, and is made of a magnetic material along the inner edge thereof. A magnetic shielding tube 10 is fixed to the heat sensitive body 1 at a height near the outer surface of the case 2. This heat sensitive body 1
The heat sensitive body 1 is always placed between the outer wall of the outer case 7 and the inner wall of the outer case 7.
A coil spring 6 that raises the temperature is provided to form a temperature sensor.

When the inner pot is not placed and the heat sensitive element 1 is in the raised position as shown in FIG.
Since the permanent magnet 4 is further away from the reed switch 8, the magnetic flux from the permanent magnet 4 flows into the reed switch 8, the contact is closed, and the operation of the control circuit is stopped regardless of the temperature detection signal from the heat detection element 3. Power is cut off. When the inner pot is placed on the heat sensitive body 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 decreases rapidly, causing the reed switch 8 to open. When the reed switch 8 is in the released state, a magnetic shielding tube 10 is inserted between the reed switch 8 and the permanent magnet 4 to keep the contacts of the reed switch 8 in the open state. Therefore, the temperature detection signal from the heat detection element 3 participates in the operation of the control circuit. Conversely, when the heat sensitive element 1 rises, the reed switch 8 and the permanent magnet 4 separate from the magnetic shield tube 10, and the magnetic flux from the permanent magnet 4 affects the reed switch 8, causing the reed switch 8 to be in the closed state. Become.

Therefore, in the present invention, a permanent magnet 4 having a large amount of magnetic flux can be used, and a large amount of magnetic flux flows efficiently through the reed switch 8, so that switching of the contacts is reliable. In addition, since the permanent magnet 4 has a large magnetic pole area, there is no need to use a permanent magnet 4 with a large magnetic flux density. 8 has little effect on changes in the amount of magnetic flux flowing into the magnetic flux.
In addition, since the length direction of the reed switch 8 and the advancing/retracting direction of the heat sensitive element 1 are the same, the reed switch 8
The impact resistance of is increased.

In the embodiments described above, the reed switch 8 is in the closed state when the heat sensitive element is in the ascending position, and in the open state when it is in the descending position, but in other embodiments shown in FIGS. 4 and 5, the reed switch 8 is in the open state A magnetic shielding cylinder 10 connects the reed switch 8 and the permanent magnet 4 only in the upper position of the bottom surface of 7.
By configuring it to be inserted between
The reed switch 8 is in an open state when the heat sensitive element 1 is in the ascending position, and is in a closed state when it is in the descending position.

In the case of FIG. 4, the reed switch 8 is open, and in the case of FIG. 5, the reed switch 8 is closed. That is, this shows the reverse operation of the contact opening/closing shown in FIGS. 2 and 3 described above.

Effects of the invention As described above, according to the invention, the influence of lateral vibration due to the advance and retreat of the heat sensitive element 1 is small, the switching of the reed switch 8 is reliable, and the temperature sensor for cooking appliances is highly reliable and can withstand shocks. is obtained.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view of an embodiment of the temperature sensor in the cooking appliance of the present invention, FIG. 2 is a longitudinal sectional front view of the temperature sensor according to the present invention when the heat sensitive element is in the raised position, and FIG. FIG. 4 is a longitudinal sectional front view of another embodiment of the temperature sensor according to the present invention when the heat susceptor is in the ascending position, and FIG. 5 is a longitudinal sectional front view of the temperature sensor of FIG. Vertical front view when the heat sensitive body is in the lowered position, No. 6
The figure 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, 3... Heat detection element, 4... Permanent magnet, 5... Protection tube, 6...
... Coil spring, 7 ... Outer case, 8 ... Reed switch, 9 ... Fixing metal fittings, 10 ... Magnetic shielding tube,
11... Upper cover plate, 12... Heat plate, 13, 14...
...through 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 cooking appliance 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 due to The contact point of the reed switch 8 is arranged to face the center of the permanent magnet 4 which is magnetized in the axial direction, so that the reed switch 8 is moved in the axial direction by being suspended by the up and down movement of the heat susceptor 1. A cylindrical magnetic shield 10 made of a magnetic material that magnetically shields the space between the permanent magnet and the reed switch 8 is provided on the bottom surface of the supporting outer case 7.
A temperature switch for a cooker, characterized in that a temperature switch is installed vertically.