JPS6319990B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a submersible heating element used in electric water heaters, etc. When the heating element is dry energized, it senses a sudden temperature rise and opens the energizing circuit to prevent disconnection of the heating wire or abnormal heat generation. In addition to controlling the temperature of the object to be heated in the container, these two controls are performed using a single temperature controller, providing an economical, highly durable, and highly reliable submersible heating element. It is something to do.

Conventionally, submersible heating elements used in electric pots and the like have been covered with SUS 430 stainless steel plates. Since this heating element generates heat in water, the temperature of the heating element is low, so the heating density is usually about 5 to 15 W/cm ² and the heating element is miniaturized. For this reason, if a dry current is accidentally applied without adding water, the temperature rises rapidly, causing the heating wire to break or breaking the covering joint of the stainless steel plate.

In addition to the heating element, a liquid expansion type thermal sensor was placed in the water to control the temperature, or a temperature controller was installed outside the container to control the temperature. For this reason, even if the above-mentioned dry energization was performed, it was not possible to prevent the temperature of the heating element from rapidly rising because the heating element and the controller were separate bodies.

Various means have been proposed to prevent damage and fire caused by abnormal temperature rises, but none of them have the ability to control the temperature of the heated object, making them expensive. In particular, due to problems with workability and corrosion resistance, the heat generating member was roll-locked to the outer peripheral ends of two SUS430 stainless steel plates to maintain watertightness and press the heat generating member, which made it impossible to eliminate the above-mentioned drawbacks.

The present invention solves the above-mentioned drawbacks, provides economical efficiency, durability,
An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

In the figure, reference numeral 1 denotes a submersible heating element, which is watertightly attached to the inner bottom of a container 2 containing water or the like with a nut 5 together with a body stopper 4 and the like via packings 3 and 3'. This submersible heating element 1 has a bulging part 6a in the center of a round plate-shaped upper seam plate 6, a thermostat 7 is fixed to this bulging part 6a, and a spring 8 is used to heat-sensitively press and hold the thermostat 7 in the center part. A heat conductive plate 9 made of aluminum or iron plate having a thickness of t0.3 to 0.7 mm and having a through hole 9a and good heat conduction, and a heat generating material 10 made of a mica plate 10a and a heat generating wire 10b wound around the top and bottom of which have high heat resistance. It is sandwiched between upper and lower insulating materials 11 and 11' such as mica plates, and through holes 10c, 11a and 11' are formed in the center, respectively.
a, and through holes 9a, 10c, 11a, 11' of the heat conductive plate 9 and the heat generating member 12.
The thermostat 7 and the heat generating member 12
An insulator 1 having a lead hole 13a and a flange portion 13b for leading the lead wires 7a and 12a to the outside.
3, a mounting member 14 having a through hole 14a through which the insulator 13 passes, an engaging flange 14b, and a threaded portion 14c, and a stepped through hole 15a in the center that engages the engaging flange 14b of the mounting member 14. and a round plate-shaped lower seam plate 15.

As shown in FIG. 4, the thermostat 7 has a ceramic insulating body 7a, a fixed contact 7b, and a movable spring 7.
A fixed movable contact 7d is attached to the insulating body 7, a thermally responsive plate 7f is provided via a spacer 7e, and a sensitive plate 7g made of a material with good thermal conductivity such as an aluminum plate is connected to the insulating body 7.
A is stored in the heat-responsive plate 7f by the connecting insulator 7h.
The movement is transmitted to the movable spring 7c to close and open the movable contact 7d.

The thermally responsive plate 7f is thermally pressed against the top surface 6b of the bulge 6a of the upper seam plate 6 via the sensitive plate 7g,
The retaining spring 8 is held by engaging the claw 8a with the engaging protrusion 6c. The upper and lower seam plates 6 and 15 have a thickness of 0.3~
It is made of 0.6mm ultra-low carbon 16-19% chrome steel with less than 0.02% stainless steel plate containing 0.8-3% molybdenum and 0.5-1% niobium or titanium.

Then, the underwater heating element 1 is made by laminating the upper seam plate 6, the heat conduction plate 9, and the heat generating member 12 in this order.The lead wires 7a and 12a of the thermostat 7 and the heat generating member 12 are led out through the insulator 13, and the mounting member 14 is Fitted into the insulator 13, the lower seam plate 15 is further stacked, and the outer peripheral side edges 6d, 1 of the upper and lower seam plates 6, 15 are fitted.
5b are fitted and pressed vertically, and the outer peripheral end surface 1a is watertightly joined by welding. This bonding is usually performed by coating the outer peripheral end surface 1a with an inert gas such as argon gas, and melting and bonding using an electric arc.

As a result, the heat conduction plate 9 and the heat generating member 12 are clamped by the upper and lower seam plates 6 and 15, and the lead wires 7a and 12a are led out to connect the thermostat 7 and the heat generating plate 10 in series as shown in FIG. .

When the submersible heating element 1 of the above embodiment is used in an electric pot, it is as shown in Fig. 1. In Fig. 1, 16 is a base, 17 is a cord connector, 18 is a handle, and 19 is a lid. .

Next, the operation of the underwater heating element 1 will be explained.

When used in an electric pot as shown in FIG.
generates heat and heats the water via the upper and lower seam plates 6 and 15. At this time, the thermally responsive plate 7 of the thermostat 7
f is heat-sensitively attached to the top surface 6b of the bulge 6a of the upper seam plate 6, and since the bulge 6a protrudes into the water, its temperature is approximately the same as that of the water. Therefore, the thermally responsive plate 7f operates by sensing the water temperature. Moreover, the lower surface of the thermostat 7 is shielded from the heat generating member 12 by a heat conduction plate 9, which is made of a material with good heat conductivity and has most of its area in pressure contact with the upper seam plate 6. Since the temperature does not rise significantly above the water temperature, the thermostat 7 operates at a temperature that is more equal to the water temperature.

Next, when the submersible heating element 1 is not placed in the object to be heated and is energized dryly, when the heating member 12 generates heat, the heat conduction plate 9 and the upper seam plate 6 are rapidly heated, and the thermostat 7 is heated from the entire circumference. This causes the temperature to rise rapidly, causing the thermally responsive plate 7f to operate and move the movable contact 7d.
open. In particular, at this time, the upper seam plate is made of ferrite stainless steel containing chromium and molybdenum, and does not contain nickel, so the thermal conductivity is high and the temperature of the bulged portion 6a also rises rapidly.

The outermost diameter of submersible heating element 1 is 90 mm, reducing power consumption.
When conducting an experiment with the operating temperature of the 600W thermostat 7 at 96°C, the thermostat 7 operates approximately 50 to 65 seconds after power is started, and the temperature of the upper seam plate 6 reaches its maximum value.
The temperature is about 300 to 450℃, and the upper and lower seam plates 6 and 15
Abnormalities in the joints and disconnections of the heat generating plate 10 do not occur at all. Moreover, the thermal deterioration temperature of the stainless steel plates of the upper and lower seam plates 6 and 15 is about 650°C, so that corrosion resistance does not deteriorate.

As described above, in the underwater heating element of the present invention, the heat generating member and the heat conductive plate are sandwiched between the upper and lower seam plates, the outer peripheral end surfaces are watertightly joined, and the thermostat is attached to the upper seam plate via the heat conductive plate. The temperature of the heated object can be controlled by one thermostat, and
It is economical as it serves the dual function of preventing abnormal heat generation of the heating element itself.

In addition, if a thermostat is provided by providing a bulge on the upper seam plate, the temperature of the heated object can be controlled more accurately, and a thermally responsive plate can be pressed and held on the top surface of the bulge with a simple stop spring. This further enhances the above effects.

Furthermore, if stainless steel made by adding molybdenum and niobium or titanium to ultra-low carbon 18% chromium steel is used for the upper and lower seam plates, there will be no structural change in the stainless steel even when the upper and lower seam plates are welded together. Corrosion resistance does not deteriorate, and watertightness does not deteriorate even at high temperatures (400 to 600°C). Furthermore, since it contains almost no nickel, it has high thermal conductivity, and the thermostat heats up rapidly, especially when it is energized dry, providing safe and reliable operation.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway sectional view of an electric pot using the submersible heating element of the present invention, Fig. 2 is a partially cutaway sectional view of the same submersible heating element, and Fig. 3 is an exploded perspective view of the same. FIG. 4 is an enlarged sectional view of the main part, and FIG. 5 is a wiring diagram of the same. 1... Submersible heating element, 6... Upper seam plate, 6a
...Bulging portion, 7...Thermostat, 7a...Lead wire, 9...Heat conduction plate, 9a...Lead wire, 1
0... Heat generating material, 11... Upper insulating material, 11'... Lower insulating material, 12... Heat generating member, 14... Mounting member,
15...Lower seam board.

Claims (1)

[Scope of Claims] 1. A heat-generating member having a heat-generating material sandwiched between heat-resistant insulating materials is covered with an upper seam plate and a lower seam plate, a part of the upper seam plate is bulged upward, and A heat conductive plate made of a metal plate with good heat conductivity such as an aluminum plate is interposed between the heat generating members, a thermostat is positioned between the bulging part of the upper seam plate and the heat conducting plate, and this thermostat is bulged. Further, a mounting member is provided on the lower seam plate, the heat generating member is clamped and pressed by the upper seam plate and the lower seam plate, and the outer peripheral end surfaces of the upper seam plate and the lower seam plate are mounted. A submersible heating element is formed by watertightly connecting the thermostat and the electric lead wires of the heating member to the mounting member in an insulating manner. 2. The upper seam plate and lower seam plate are made of ferritic stainless steel made by adding molybdenum and niobium or titanium to ultra-low carbon 18% chromium steel with a carbon content of 0.02% or less, and the joints of the upper and lower seam plates are welded. An underwater heating element according to claim 1.