JPH0350819Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Field of Use The present invention relates to a safety device for a cooker that uses an inner pot for cooking and prevents dry cooking by providing a reed switch in the center of the bottom of an outer pot.

2. Description of the Related Art In a cooking device in which an inner pot is placed inside an outer pot for cooking, an annular heater or an annular heating plate with a built-in heater is heated by electricity at the inner bottom of the outer pot. These cookers are equipped with an annular heating plate 5 of an outer pot as shown in Fig. 4.
The heat sensitive body 1 is made to protrude from the upper surface, and the outer bottom of the inner pot is brought into contact with the surface of the heat sensitive body 1, and the temperature that changes depending on the food cooked in the inner pot is fixed to the back surface of the upper cover plate 21 of the heat sensitive body 1. The heat is detected by a heat detector 3 such as a thermistor, and the control circuit controls energization of the hot plate 5 to control the cooking quality of the inner pot. A recess 2 in which a bar-shaped permanent magnet 4 is housed is spaced from the center of the bottom of a bottomed cylindrical case 2 that is coupled to the upper cover plate 21 of the heat-sensitive element 1.
2 and a support plate 9 that supports a normally closed type reed switch 8 pass through the elongated hole 23. Further, between the bottomed outer case 6 which is fixed to the heat plate 5 and houses the heat sensitive body 1 and the case 2 of the heat sensitive body 1, there is a compression coil spring 6 which keeps the heat sensitive body 1 raised at all times, and a reed switch 8 at the upper end. A support plate 9 that holds the permanent magnet 4 on a flat surface and firmly supports the lower end on the bottom of the outer case is connected to the elongated hole 2.
3 to form a safety device.

When the inner pot is placed on the heat sensitive body 1, the heat sensitive body 1 is lowered by the inner pot's own weight against the biasing force of the compression spring 6, and as the heat sensitive body 1 is lowered, the permanent magnet 4 is also lowered. Since the reed switch 8 passes through the elongated hole 23 and is fixed to the support plate 9, its position can be moved.
Therefore, the magnetic flux flowing into the reed switch 8 decreases, the reed switch 8 becomes open, the temperature control circuit starts operating, and the hot plate 5 is energized. However, when the inner pot is not placed, the heat sensitive body 1 rises, and the reed switch 8 is closed by the magnetic flux of the permanent magnet 4, cutting off the current supply to the hot plate 5 and operating the safety device.

Problems to be Solved by the Invention However, in the conventional safety device that combines the reed switch 8 and the permanent magnet 4, it is necessary to strictly control the magnetic force of the permanent magnet 4. In addition, when the inner pot is placed on the heat sensitive body 1 and the heat sensitive body 1 is lowered, the magnetic force of the permanent magnet 4 is set to be greater than the upper limit value and less than the lower limit value so that the reed switch 8 reliably switches the magnetic force of the permanent magnet 4 according to the vertical movement distance of the heat sensitive body 1. There are drawbacks that must be selected. In addition, in the case of a safety device in which a bar-shaped permanent magnet 4 and a reed switch 8 are installed perpendicularly to the bottom surface of the case 2, and the permanent magnet 4 is moved parallel to the axial direction of the reed switch 8, when the permanent magnet 4 and the reed switch 8 are moved perpendicularly to each other. Similarly, the magnetic force of the permanent magnet 4 is selected to be greater than the upper limit value, and when the permanent magnet 4 moves away from the center of the reed switch 8, the contact is closed again, and the closed region where the polarity of the magnetic force is reversed is heat sensitive. The permanent magnet 4 has the disadvantage that it is difficult to select a permanent magnet 4 because it must be selected to be at least a lower limit value that does not fall within the vertical movement distance of the body 1.

Means for Solving the Problems The present invention eliminates the drawbacks of the conventional method and separates the permanent magnet 4 and the reed switch 8 into the heat sensitive body 1 and the outer case 7, respectively, and arranges the reed switch 8 in a closed state. At the same time, when the inner pot is placed on the support plate 9 that supports the reed switch 8 and the heat sensitive element 1 is lowered, the magnetic flux from the permanent magnet 4 is transferred to the reed switch 8.
This is a safety device for cooking appliances that has a magnetic shielding plate made of magnetic material installed at a position that blocks the flow of water into the cooking device.

Function: Therefore, when the heat sensitive element 1 descends, a magnetic shielding plate is placed between the permanent magnet 4 and the reed switch 8, so the magnetic flux of the permanent magnet 4 is blocked and the reed switch 8 is not affected. 8 will definitely switch.

Embodiment An embodiment of the cooking device of the present invention is shown in FIG. A rod-shaped permanent magnet 4 is housed and fixed in a recess 22 on the bottom surface of the heat sensitive body 1 parallel to the bottom surface, and an elongated hole 23 through which the reed switch 4 passes is provided parallel to and spaced apart from the recess 22 . In addition, the upper end of the reed switch 8 is supported on the outer case 2 so that it is parallel to and on the same surface as the permanent magnet 4, and the lower end is placed on the bottom surface of the outer case 2 so that the reed switch 8 moves up and down within the elongated hole 23. A support plate 9 for fixation is provided. The heat sensitive body 1 is attached to this support plate 9.
A safety device for the cooker is formed by fixing a magnetic shielding plate 10 that shields the magnetic flux of the permanent magnet 4 in the lowered position.

When the heat sensitive body 1 is in the raised position as shown in FIG. 1, the magnetic shielding plate 10 has no effect on the magnetic flux flowing into the reed switch 8 from the permanent magnet 4. However, as shown in FIG. 2, as the inner pot is placed on the heat-sensitive element 1 and the heat-sensitive element 1 is lowered, the magnetic flux from the permanent magnet 4 flows into the magnetic shielding plate 10 and the magnetic flux flowing into the reed switch 8 is at the lower limit. decreases rapidly below the value. Furthermore, when the temperature rises, it rapidly increases beyond the upper limit value, so that the reed switch 8 can be reliably switched by a small displacement during the descent and rise of the heat sensitive element 1. In other words, the magnetic force changes rapidly with respect to the amount of change in the heat sensitive body 1, and there is no influence of the amount of magnetic force of the permanent magnet 4 or non-uniformity of characteristics, and switching is good, improving the safety and reliability of the device.

FIG. 3 shows another embodiment of the present invention. A recess 24 having a through hole 25 therethrough is provided at the center of the bottom of the heat sensitive body 1, and an annular permanent magnet 4 is fitted into the recess 24. Further, a cylindrical magnetic shielding tube 12 having an outer diameter smaller than the inner diameter of the permanent magnet 4 is fixed in the bottom surface of the outer case 2 with its axis aligned with the through hole 25 by a collar at the lower end.
A protection tube 13 molded from resin and having one end open is inserted into the cylinder of the magnetic shielding tube 12 by penetrating the tip into the through hole 25 . Furthermore, a safety device is formed by arranging a contact point in the protective tube 13 at the center surface of the magnetic pole of the permanent magnet 4 and fitting the reed switch 8 therein.

As the heat sensitive body 1 rises and falls, the permanent magnet 4
The magnetic force of the permanent magnet 4 repeatedly increases and decreases rapidly, and the outer closed region disappears due to the arrangement of the magnetic shield cylinder 12, and the lower limit of the magnetic force of the permanent magnet 4 in the case of horizontal movement can be relaxed, and the magnetic pole of the permanent magnet 4 Since the surface faces the flange of the magnetic shielding tube 12, the magnetic shielding tube 1 is simple.
Case 2 is more effective in controlling the magnetic flux.

In the above embodiment, the permanent magnet 4 was moved together with the heat sensitive body 1, but on the other hand, the permanent magnet 4 was moved together with the outer case 2.
Alternatively, the reed switch 8 and the magnetic shield tube 12 may be provided on the heat sensitive body 1, or the permanent magnet 4 and the reed switch 8 may be fixed, and the magnetic shield tube 12 may be moved. Note that the shielding effect of moving the permanent magnet 4 and inserting the permanent magnet 4 into the magnetic shielding tube 12 causes the amount of magnetic flux from the permanent magnet 4 to decrease rapidly relative to the contact point of the reed switch 8.

Effects of the invention As described above, according to the invention, the restrictions on the selection of the permanent magnet 4 and the reed switch 8 can be relaxed, and the switching operation of the reed switch 8 can be made uniform and reliable, making it highly reliable and inexpensive. A cooker safety device that prevents dry cooking can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional front view of the heat-sensitive body portion of the embodiment of the safety device for a cooker of the present invention, FIG. 2 is a vertical cross-sectional front view of the heat-sensitive body when the heat-sensitive body is in the lowered position in FIG. FIG. 3 is a longitudinal sectional front view of a heat-sensitive part of a second embodiment of the present invention, and FIG. 4 is a longitudinal sectional front view of a conventional safety device of a cooking appliance. In addition, 1: heat sensitive body, 2: case, 3: heat detector, 4: permanent magnet, 5: hot plate, 6: coil spring,
7: Outer case, 8: Reed switch, 9: Support plate, 10: Magnetic shielding plate, 12: Magnetic shielding tube, 1
3: protection tube, 22, 24: recess, 23: slotted hole,
25: Through hole, 21: Upper cover plate.

Claims (1)

[Claims for Utility Model Registration] 1. Permanently caused by the temperature detection signal from the heat detector 3 in the heat sensitive body 1 protruding from the annular heat plate 5 disposed on the bottom of the outer pot and the descent of the heat sensitive body 1. In a cooking appliance equipped with a reed switch 8 that switches contacts in response to changes in the magnetic flux from the magnet 4, the reed switch 8 is arranged parallel to and on the same plane as the bar-shaped permanent magnet 4 arranged on the bottom surface of the heat sensitive element 1. The permanent magnet 4 in the lowered position of the temperature sensing element 1 is attached to a support plate 9 that supports the reed switch 8 and has a lower end erected on the bottom inner surface of the outer case 7 in which the temperature sensing element is housed.
A safety device for a cooking appliance, which is provided with a magnetic shielding plate 10 made of a magnetic material and facing the same. 2. In the cooking device, an annular permanent magnet 4 is installed through the bottom inner surface of the heat sensitive body 1, and a ring-shaped permanent magnet 4 is installed on the bottom inner surface of the outer case 7 in which the heat sensitive body 1 is housed on the same axis as the central axis of the permanent magnet 4. A practical device comprising a magnetic shielding cylinder 12 made of a magnetic material whose lower end is fixed with a collar, and a reed switch 8 erected within the magnetic shielding cylinder 12 with a contact point located on the center plane of the magnetic pole of the permanent magnet 4. A safety device for a cooker according to claim 1 of the patent registration claim.