JPS5827245Y2 - Overheat prevention device for gas appliances - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an overheat prevention device that automatically cuts off the gas supply to a gas burner when a gas appliance overheats abnormally.

Conventional overheating prevention devices come in two types: bimetal switches and temperature fuses, both of which cut off the electromotive current sent from the thermocouple to the solenoid valve coil, but bimetal switches have incomplete contacts. In such a case, the contact resistance becomes too high and the solenoid valve cannot be held open incompletely, and in the case of a temperature fuse, the attachment portion of the temperature fuse becomes loose, making it incompletely possible to keep the solenoid valve open.

In order to solve the above-mentioned drawbacks of the conventional device, this device demagnetizes and closes the solenoid valve by grounding the thermocouple circuit to the device body and causing the generated electromotive current to flow through the device body in the event of abnormal overheating. This provides a device in which the generated electromotive current does not pass through contacts or the like during normal operation.

The details of this invention will be explained below based on the attached drawings.

In the figure, 1 is a metal body of a gas appliance, and in the case of a water heater, the heat exchange part is optimal.

Reference numeral A denotes an overheating prevention device of this invention, which is installed inside a case 2 that is screwed to the container body 1.

Reference numeral 3 denotes an operating member fitted in the case 2 so as to be movable forward and backward, and is made of a material such as thermoplastic synthetic resin that has both electrical insulation properties and the property of melting at a relatively low temperature.

A contact portion 4 is integrally formed on the side of this member 3 facing the vessel body 1.

In the illustrated example, this contact portion 4 is formed in the shape of a protruding edge that extends around the entire circumference of the member 3, but it may not be formed all over the circumference and may be provided at several locations, or the member 3 may be made of metal and the contact portion Only part 4 may be electrically insulating and low-temperature melting.

Reference numeral 5 denotes a contact terminal, which is fixed to the member 3 by means such as screwing, and its tip 6 faces toward the container body 1.

In addition, in the illustrated example, a spring 7 is attached between the rear end of the case 2 and the rear end of the actuating member 3 to press the contact portion 4 of the member 3 against the container body 1, but the member 3 is heavy and is pressed by its own weight. You can do it like this.

In FIG. 1, 8 is a main burner of the gas appliance, and 9 is a pilot burner, both of which are supplied with gas from a gas supply pipe 10.

A solenoid valve 11 such as a pilot safety device is attached to the gas supply pipe 10, and the coil 12 of this valve 11 is connected to a thermocouple 13 heated by the pilot burner 9. The electromotive current generated excites the coil 12 to keep the valve 11 open.

A wire 14 electrically connects one end of the coil 12 and the minus side of the thermocouple 13, and the other end of the coil 12 and the plus side of the thermocouple 13 are grounded to the container body 1.

Further, a portion of the electric wire 14 is connected to the contact terminal 5 through the through hole of the case 2.

However, the electric wire 14 is made of a covered electric wire so that it does not come into electrical contact with anything other than the terminal 5.

This invention has the above-mentioned configuration, and under normal conditions, the tip end 6 of the contact terminal 5 is separated from the container body 1 as shown in FIG.

Therefore, the electromotive current generated in the thermocouple 13 due to the heating of the pilot burner 9 flows through the electric wire 14 to the coil 12, energizing the coil 12, and maintaining the solenoid valve 11 in an open state, so that gas is ejected from the main burner 8 and the pilot burner 9
is ignited.

1. If the temperature of the vessel body 1 becomes abnormally high due to some reason, the contact portion 4 will melt.

In this case, the actuating member 3 is moved to the third position by the action of the gravity tube or the spring 70.
Move toward the container body 1 as shown in the figure, and touch the tip 6 of the contact terminal 5.
Since the thermocouple contacts the vessel body 1, the negative terminal of the thermocouple is grounded, and no electromotive current flows through the coil 12, which is demagnetized and the solenoid valve 11 is closed.

This idea reduces the electromotive current generated by the thermocouple by bringing the contact terminal of the actuating member, which has a contact part made of a material that melts when the body reaches an abnormally high temperature, into contact with the body and grounding it. Since it demagnetizes the solenoid valve by releasing it, there is no risk of malfunctions due to poor contact during normal operation, and it has excellent responsiveness.

In addition, it has a simple structure and can be manufactured at a lower cost than a bimetallic switch, and has advantages such as being able to freely change the operating temperature by changing the material (melting point) of the operating member.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a gas appliance implementing this invention, and FIGS. 2 and 3 are enlarged longitudinal sectional views showing various states of the apparatus of this invention. 1... vessel body, 2... case, 3...
...Operating member, 4...Contact part, 5...-
・Contact terminal, 9... Pilot burner, 11.
... Solenoid valve, 13 ... Thermocouple.

Claims (1)

[Scope of utility model registration request] For gas appliances that have a solenoid valve that is held open by the electromotive current generated by a thermocouple heated by a pilot burner, electrical insulation is installed inside the case fixed to the surface of the gas appliance, where the temperature rises rapidly in the event of an abnormality. An actuating member having a high temperature and low temperature melting property is fitted, and the contact part of this member is pressed to the vessel body by a spring or its own weight, and the actuating member has a contact part that, when melted, contacts the surface of the gas appliance. An overheat prevention device for gas appliances equipped with a contact terminal that grounds the thermocouple circuit.