JPH0444436B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thermocouple heated by a pilot burner for ignition, among thermocouples used as a power source for a gas safety valve that shuts off gas when extinguishing a burner.

[Prior art]

This type of gas safety valve uses, for example, a solenoid valve 20 as shown in FIG. 6, and two thermocouples A, which are heated by an ignition pilot burner 21 and a permanent pilot burner 22, as power sources for an excitation coil 20a. Using B, pilot burner 2 for ignition
If the always-fired pilot burner 22 goes out after the start-up is completed when 1 is extinguished, close the solenoid valve 20 and turn off the ever-fired pilot burner 22 and the main burner 2.
This is to prevent the release of unburned gas from 3. When starting to use the gas appliance, the solenoid valve 20 must be held open by another means until the thermoelectromotive force of the thermocouples A and B rises to the holding level of the solenoid valve 20. In addition, if each burner 21, 22 is extinguished due to a gust of wind, thermocouples A, B
Since unburned gas is released until the electromotive force of A and A decreases to the holding level of the solenoid valve 20,
It is desired that the time required for the thermoelectromotive force of B to rise or fall to a predetermined holding level is short. The thermocouple A used in the ignition pilot burner 21, which operates only during startup, is made by joining together one end of a pair of wire rods made of different metals. As shown in A', wire rods 1 and 2 made of different metals with a uniform circular cross section over their entire length are butt welded at the joint 3, so that, for example, as shown by the broken line Vb in FIG. Time t1 to rise to level Vo, time t3 to fall to level Vo from T when heating is stopped
The problem was that they were all quite large. As mentioned above, it is preferable that this time, particularly the time required to rise to a predetermined level, is shorter, since this reduces the amount of time the solenoid valve must be held open by other means during startup. One possible means for this is to reduce the diameters of the thermocouple wires 1 and 2, especially the diameters of the wires 1 and 2 near the joint 3, but the area around the joint 3 is heated by a burner, etc., and thermal distortion occurs. Reducing the diameter of the wire improves its strength and oxidation.
This was undesirable because it caused a decrease in durability and an increase in electrical resistance.

[Purpose of the invention]

The present invention was made to solve the above problem, and by changing the cross-sectional shape of the thermocouple heated by this type of ignition pilot burner while maintaining the cross-sectional area near the joint, By shortening the time required for the thermoelectromotive force of this thermocouple to rise to a predetermined level without reducing strength, durability, electrical characteristics, etc., the solenoid valve is held open by another means during startup. The purpose is to shorten the time required.

[Structure of the invention]

In order to achieve the above object, the present invention consists of a pair of wire rods made of different metals, one end of which is joined to each other, and this joint is heated by an ignition pilot burner that operates only at the time of starting, and is heated by an ignition pilot burner that operates only at the time of starting. In a thermocouple of a gas safety device that is connected to an excitation coil of a solenoid valve installed in a gas passage together with a thermocouple for a normal flame that is heated by In addition, the cross-sectional shape near the joint is formed into a shape that increases the surface area compared to the cross-sectional area.

〔Effect of the invention〕

The thermocouple heated by the pilot burner for ignition according to the present invention having such a configuration has a cross-sectional area of both dissimilar metal wires that is substantially constant over the entire length including the joint portion, and a connecting portion that generates a thermoelectromotive force. Since the cross-sectional shape in the vicinity is shaped to increase the surface area, the surface area (i.e. heat receiving area and heat dissipating area) increases near the connection part without changing the heat capacity.
The rate of temperature rise near the junction increases. The time required for the thermoelectromotive force to rise to a predetermined level is therefore reduced, thereby reducing the time during which the solenoid valve must be held open by other means during start-up. Moreover, the cross-sectional area of the thermocouple junction remains unchanged;
Furthermore, since the ignition pilot burner only heats the gas appliance for a short time when the gas appliance is started, the strength, durability, and electrical characteristics of the joint area will not deteriorate.

Embodiment In the embodiment shown in FIGS. 1 and 2, a pair of wire rods 10 and 11 made of different metals (for example, chromel and constantan, stainless steel and constantan, etc.) are butted together at one end and welded to form a joint 12. The thermocouple A is formed by flattening the vicinity of the joint portion 12. As a result, wire rods 10, 11
Although the cross-sectional area is approximately constant over the entire length including the vicinity of the joint 12, the surface area near the joint 12 increases. An insulator 13 is placed in the middle of each wire rod 10, 11.
Provide reinforcement and support for the equipment.

In the embodiments shown in FIGS. 1 and 2, the joint portion 12 is flattened into a plane within the plane including the wire rods 10 and 11, but it is flattened into a spindle-shaped cross section as in the joint portion 12a in FIG. Alternatively, it may be flattened in a plane orthogonal to each of the wire rods 11 and 12, as in the joint portion 12b in FIG. Furthermore, joint part 1
The cross-sectional shape near 2 is preferably flat as described above from the viewpoint of processing, but any shape may be used as long as the cross-sectional area is approximately the same as that of the other parts of the wire rods 10 and 11 and the surface area is larger than that of the other parts. Any cross-sectional shape is acceptable.

Next, FIG. 5 shows a comparison of the thermoelectromotive force of the thermocouple A of the present invention with that of the conventional thermocouple A' having a circular cross section shown in FIGS. 7 and 8. That is, when the thermocouple A of the present invention is heated by a burner or the like, the surface area (heat receiving area in this case) near the joint 12 is large, so the thermoelectromotive force increases as shown by the solid line Va in FIG. , the time t required for the conventional product A′ with the same cross section
The predetermined level Vo is reached in a time t2 shorter than 1. In addition, if the burner goes out due to a gust of wind, etc., the surface area around the joint 12 (heat radiation area in this case) is large, so the thermocouple A
The time t4 for the thermoelectromotive force to drop to the predetermined level Vo is shorter than the time t3 in the conventional product.

Next, the effect when the thermocouple A of the present invention is used in the gas appliance shown in FIG. 6 will be explained. If the knob of the gas appliance is held in the pressed state when starting, gas will be ejected from the ignition pilot burner 21 and the permanent pilot burner 22, and at the same time the ignition device 26 will operate for a certain period of time, producing a spark at the ignition point 27, causing both The gas from the pilot burners 21 and 22 is ignited. The thermocouple A of the present invention and the thermocouple B for constant flame are connected in series to the excitation coil 20a of the solenoid valve 20, and the former A is heated by the pilot burner 21 for ignition, and the latter B is heated by the constant flame pilot burner 22. I'll do what I do. In the one shown in FIG. 6, when the pilot burner 21 for ignition is operating at the initial stage of starting, the sum of the thermoelectromotive forces of both thermocouples A and B is applied to the excitation coil 20a.
Since the heat receiving area of the solenoid valve 20 is large, the time required for the solenoid valve 20 to reach the holding level can be further shortened compared to conventional products. This reduces the time it takes to manually hold the solenoid valve 20 open during startup, making it easier to use.
Alternatively, a small device that automatically performs such holding will be sufficient. After the ignition pilot burner 21 is extinguished, the solenoid valve 20 is held only by thermocouple B, and in this state, thermocouple A
acts as a resistance to reduce the current in the exciting coil 20a, but since the cross-sectional area of the thermocouple A is not even partially small in diameter, it does not have any adverse effect on the holding of the solenoid valve 20. Also, thermocouple A
Since it is only heated by the ignition pilot burner 21 at the time of starting, durability does not deteriorate even if the surface area is large. Therefore, the thermocouple A according to the present invention is particularly suitable for use as a thermocouple that is heated only at the time of starting by the ignition pilot burner 21 of the safety device for gas appliances shown in FIG.

[Brief explanation of drawings]

1 to 6 are explanatory diagrams of the embodiment and operation of the present invention, in which FIG. 1 is a front view of a thermocouple, FIG. 2 is a sectional view taken from FIG. 1, and FIGS. 3 and 4. 2 is a diagram corresponding to another embodiment, FIG. 5 is an explanatory diagram of the operation, FIG. 6 is a circuit diagram of a gas appliance equipped with a gas safety valve, and FIGS. 7 and 8 are diagrams corresponding to conventional products. 1 and 2 are equivalent views. Explanation of symbols, 10, 11...Wire rod, 12, 12
a, 12b...Joint part, 20...Solenoid valve, 21...
... Pilot burner for ignition, 22... Pilot burner for constant flame, A... Thermocouple, B... Thermocouple for constant flame.

Claims (1)

[Claims] 1 The ends of a pair of wire rods made of different metals are joined to each other, and this joint is heated by an ignition pilot burner that operates only at the time of startup, together with a constant-fire thermocouple that is heated by a constant-fire pilot burner. In a thermocouple of a gas safety device connected to an excitation coil of a solenoid valve provided in a gas passage, the cross-sectional area of both wires is substantially constant over the entire length including the vicinity of the joint, and the cross-sectional shape of the wire near the joint is A thermocouple for gas safety equipment, characterized in that the thermocouple is formed into a shape that increases the surface area compared to the cross-sectional area.