JPS624835Y2 - - Google Patents

Description

[Detailed description of the invention] (a) Industrial application field The present invention relates to an electric water heater that uses a heating element to raise the water temperature.

(B) Prior Art In conventional water heaters of this kind, a technique is known that heats the water to make the water temperature uniform by effectively performing a convection action, as disclosed in Japanese Utility Model Application Publication No. 48-23354.

However, if for some reason the amount of stored hot water decreases and the heating element becomes dry, the bottom wall of the tank equipped with the heating element is heated by thermal conduction, and the thermally responsive switch installed on the bottom wall of the tank is activated. The power to the heating element must then be cut off to prevent further heating, and in consideration of the possibility of dry firing, it is usually desirable for the tank body to be made of metal. That is, when the heating element disposed inside the tank is in an empty state, the heating element becomes red hot, and its radiant heat hits the inner wall of the tank, raising the temperature.

Therefore, this type of tank is generally made of metal. However, these metal tanks have poor workability and cannot be mass-produced, resulting in high costs.

(c) Problems that the invention aims to solve This invention was developed in view of these points.The main tank is made of synthetic resin, which improves workability and makes it possible to manufacture it safely and inexpensively, making it suitable for mass production. At the same time, it is an object of the present invention to reliably and quickly cut off electricity to the heating element when the heating element is in a dry state.

(d) Means for solving the problem To this end, the present invention includes a main tank 2 made of synthetic resin and a metal auxiliary tank connected to the bottom of the main tank 2, as detailed in the examples. A tank 3, a heating element 8 installed in the bottom of the auxiliary tank 3, a metal cylindrical body 10 whose upper and lower ends are open and into which the heating element 8 is inserted with a gap in between, and the cylindrical body 10. Thermal melting legs 11 support the auxiliary tank 3 so as to be spaced apart from the bottom and side surfaces of the auxiliary tank 3 and the side surfaces of the main tank 2;
Thermal response detects a temperature rise on the bottom surface of the auxiliary tank 3 due to the melting of the cylindrical body 10 and falling onto the auxiliary tank 3, and cuts off the electricity to the heating element 8 when a predetermined temperature or higher is detected. Switch 9
It is composed of.

(E) Effect When the stored water decreases and the tank becomes empty, the radiant heat from the red-hot heating element 8 is blocked by the metal cylindrical body 10, so that the main tank 2 made of synthetic resin will not be burnt out. Of course, since the metal cylindrical body 10 is rapidly heated, the heat-melting legs 11 supporting it
quickly melts and falls downward, promoting heating of the bottom surface 7 of the auxiliary tank 3 to a higher temperature, improving the responsiveness of the thermally responsive switch 9, and quickly cutting off the current to the heating element 8. .

(f) Example An example of the present invention will be described below based on the drawings.
Reference numeral 1 designates an electric water heater main body, in which an auxiliary tank 3 is connected to the lower part of the main tank 2 located above, water is supplied from a water supply pipe 4 provided on one side of the auxiliary tank, and the main tank 2 is provided above the main tank 2. Hot water is pushed up and discharged from the hot water supply pipe 5.

The main tank 2 is made of synthetic resin, has an opening 6 formed at its lower part, and is connected to the opening 6 to which the auxiliary tank 3 made of metal is connected via a sealing material (not shown). .

The auxiliary tank 3 has a heating element 8, which is a rod-shaped heater tube, installed vertically on its bottom surface 7, and a heat-responsive switch 9 is installed on the outer bottom surface of the auxiliary tank 3 to connect the main tank 2 and the main tank 3. When the amount of water stored in the auxiliary tank 3 decreases and the tank becomes empty, the heat generated from the heating element 8 operates the thermally responsive switch 9 to cut off the electricity to the heating element 8. ing. Therefore, when the main tank 2 and the auxiliary tank 3 are full of water, the thermally responsive switch 9 does not operate.

Reference numeral 10 denotes a metal cylindrical body which is surrounded by the heating element 8 with a gap and installed vertically, and whose upper and lower ends are open, and whose lower part is connected to the auxiliary tank 3 with metal heat-melting legs 11,
11, and the upper part is located inside the main tank 2 above. Therefore, the heat-melting legs 11,1
1, the cylindrical body 10 is supported so as to be spaced from the bottom surface 7 and side surface of the auxiliary tank 3 and the side surface of the main tank 2. Therefore, when the water is full, hot water convection circulates around the metal cylindrical body 10 as shown by the arrow, and as a result, high-temperature hot water is reliably discharged from the hot water supply pipe 5.

On the other hand, when the stored water decreases and becomes empty, the radiant heat from the red-hot heating element 8 is transferred to the metal cylindrical body 1.
0, so that the main tank 2 made of synthetic resin will not be burnt out. Of course, since the metal cylindrical body 10 is rapidly heated, the heat-melting legs 1 supporting it
1 melts quickly, and the lower auxiliary tank 3
drop onto the bottom surface 7 of the auxiliary tank 3 to promote heating of the bottom surface 7 of the auxiliary tank 3 to a higher temperature, improving the responsiveness of the thermally responsive switch 9, and cutting off electricity to the heating element 8 when a predetermined temperature or higher is detected. do.

(g) Effects of the invention Due to the above structure, even if the main tank is made of synthetic resin, this invention is safe because it will not burn out when it is empty, and is more safe than conventional metal tanks. It is lightweight, easy to handle, and can be manufactured at low cost. Moreover, when the heating element is in a dry state, the power supply to the heating element can be cut off reliably and quickly.

[Brief explanation of the drawing]

The drawing is a longitudinal sectional view of the electric water heater of the present invention. 2... Main tank, 3... Auxiliary tank, 8... Heating element, 9... Heat-responsive switch, 10... Metal cylindrical body, 11... Heat melting leg body.

Claims (1)

[Scope of utility model registration request] A main tank made of synthetic resin, a metal auxiliary tank connected to the bottom of the main tank, a heating element installed in the bottom of the auxiliary tank, and the heating elements having upper and lower ends open so that there is a gap between them. a metal cylindrical body to be inserted into the auxiliary tank; a heat-melting leg body supporting the cylindrical body so as to be spaced from the bottom and side surfaces of the auxiliary tank and the side surface of the main tank; Detects a rise in temperature at the bottom of the auxiliary tank due to the cylindrical body falling onto the auxiliary tank due to melting of the legs during dry firing, and cuts off electricity to the heating element when a predetermined temperature or higher is detected. An electric water heater consisting of a thermally responsive switch.