JPH029560Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a thermocouple suitable for use 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. 5, 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.
It is designed to prevent the release of unburned gas more than 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. Thermocouple B used in the ever-fired pilot burner 22 is made by inserting a core wire made of a different metal into an outer cylinder made of a heat-resistant metal with a gap around it, and joining the ends of the outer cylinder and the core wire to each other. However, in the conventional case, as shown in B' in FIGS. 6 and 7, the outer cylinder 1 and the core wire 2 having a circular cross section are joined by brazing or the like at the joint part 3. As shown by the broken line Vb in the figure, the time t1 from when heating starts until the thermoelectromotive force rises to a predetermined level Vo, and the time t3 from when heating stops until it falls to level Vo are both considerably large. There was a problem. As mentioned above, the shorter this time is, the less time it takes for unburned gas to be released, which is preferable from a safety standpoint.As a means for this purpose, it is conceivable to reduce the thermal inertia by downsizing the area around the joint 3 in particular. However, since the area attached to the joint 3 is heated by a burner and tends to cause thermal distortion and oxidation, downsizing this area is undesirable as it reduces strength and durability and increases electrical resistance. There was also a limit.

[Problem that the invention attempts to solve]

By changing the cross-sectional shape of the joint of this type of thermocouple, the present invention allows the thermoelectromotive force of the thermocouple to reach a predetermined level without substantially reducing the strength, durability, electrical characteristics, etc. of the joint. The aim is to reduce the time required to ascend or descend.

[Means for solving problems]

For this reason, the present invention provides a thermocouple of this kind, as shown in FIGS.
1a is deformed into a wide and flat shape, the tip end 10a of the outer cylinder 10 is deformed into a flat hollow shape, and the core wire 11 and the leading end of the outer cylinder 10 are integrally joined to each other.

(Function) Since the distal end portion 11a of the core wire 11 is deformed into a wide and flat shape, the length in the circumferential direction of the joint surface 12 with the distal end portion 10a of the outer tube 10 is larger than that in the conventional case.
When the thermocouple is heated by a burner or the like, the heat applied to the exposed portion of the outer surface of the bonding surface 12 is immediately transferred to the bonding surface 12, and since the length of this exposed portion is longer than before, the bonding The temperature of the surface 12 rises more quickly than before. In addition, when heating is stopped, the heat dissipation from the exposed portion is immediately caused by the bonding surface 12.
Since the bonding surface 12 is cooled, the temperature of the bonding surface 12 decreases more quickly than in the past.

(Effect of the invention) As described above, in the thermocouple of the invention, the temperature rise and fall speed of the most extreme joint surface 12 between the outer tube 10 and the core wire 11 are both high, so the thermoelectromotive force rises and falls to a predetermined level. The amount of time spent doing so will both decrease.

(Embodiment) In the embodiment shown in Figs. 1 to 3, the thermocouple B has an outer cylinder 10 made of a heat-resistant and corrosion-resistant metal such as stainless steel, and a constantan which has a large difference in thermoelectric power from stainless steel etc. The core wire 11 is made of different metals such as. The core wire 11 is formed by deforming the distal end 11a of a material with a circular cross section into a wide and flat shape using a press or the like, as shown in the figure, and the outer tube 10 is formed by deforming the distal half of the cylindrical material into a slightly narrower shape. It is formed by increasing the diameter and deforming the tip 10a into a flat hollow shape. As shown in FIG. 3, the cross-sectional shape of the tip 10a of the outer cylinder 10 is such that the entire circumference of the flat tip 11a of the core wire 11 has a narrow gap 1.
The leading edge of the outer cylinder 10 is bent slightly inward and abuts on the outer circumferential surface of the leading edge of the core wire 11, and is airtightly joined by brazing or the like, so that A joint surface 12 with one end exposed,
This joint surface 12 forms a hot junction of the thermocouple.

The base side of the outer cylinder 10 is fixed to a metal cylindrical support member 14 by brazing or the like, and the base side of the core wire 11 is bonded and fixed to a copper terminal piece 13 by brazing or the like to form a cold junction of the thermocouple. The terminal piece 13 is supported by a support member 14 via an insulator 15. The thermocouple B is attached to the main body of the gas appliance via the support member 14, and the terminal piece 13 is connected to the excitation coil 20a of the solenoid valve 20 via the thermocouple A (see FIG. 5).
connected to. Next, FIG. 4 shows a comparison of the thermoelectromotive force of the thermocouple B of the present invention with that of the conventional thermocouple B' shown in FIGS. 6 and 7. The length in the circumferential direction of the joint surface 12 between the tip 11a of the core wire 11 deformed into a wide flat shape and the tip 10a of the outer tube 10 is
Circular joint surface 3 of conventional product B' shown in Figures and Figure 7
It is larger than the length in the circumferential direction. When the hot junction of a thermocouple is heated by a burner, etc., the joint surface 1
Since the heat applied to the exposed portion of the outer surface of the bonding surface 12 is immediately transferred to the bonding surface 12, the longer the exposed portion is, the faster the temperature rise rate of the bonding surface 12 that generates thermoelectromotive force increases. Since the length of this exposed part is larger in this embodiment than in the conventional product, the thermoelectromotive force of thermocouple B of this embodiment increases as shown by the solid line Va in FIG. Time t1 required for conventional product B′
The predetermined level Vo is reached in a shorter time t2 than .
In addition, even if the burner goes out due to a gust of wind, heat dissipation from the long exposed portion will cause the bonding surface to
2 is immediately cooled, the cooling rate of the joint surface 12 is high. Therefore, the time t4 for the thermoelectromotive force of thermocouple B to drop to the predetermined level Vo from T when heating is stopped is shorter than the time t3 for the conventional product, and if this thermocouple B is used as a power source for a gas safety valve, no combustion occurs. The time for gas release is reduced and safety is higher.

Next, the effect when the thermocouple B of the present invention is used in the gas appliance shown in FIG. 5 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 24 will operate for a certain period of time, producing a spark at the ignition plug 25, causing both Gas from pilot burners 21 and 22 is ignited. The thermocouple B of the present invention and the thermocouple A for ignition are connected in series to the excitation coil 20a of the solenoid valve 20, and the former B is heated by the regular pilot burner 22, and the latter A is heated by the pilot burner 21 for ignition. Do it like this. In the one shown in FIG. 5, when the ignition pilot burner 21 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, and as mentioned above, the sum of the thermoelectromotive forces of the former B is applied to the excitation coil 20a. Since the temperature rise rate is high, the time required for the electromagnetic valve 20 to reach the holding level can be further shortened compared to conventional products. After the ignition pilot burner 21 is extinguished, the solenoid valve 20 is held only by the thermocouple B. In this state, if the normally lit pilot burner 22 goes out due to a gust of wind, the thermocouple B
The thermoelectromotive force quickly decreases and reaches a predetermined level Vo in a shorter time t4 than conventionally as described above, shutting off the solenoid valve 20 and stopping the release of green gas.

In the above embodiment, the cross-sectional area near the tip of the outer cylinder 10 and the core wire 11 is the same as that of the conventional example, but the cross-sectional area may be reduced to the extent that there is no functional problem. Since the thermal inertia of the thermoelectromotive force is reduced, the difference in temperature change between the hot junction and the cold junction during the transient state increases, and the rate of rise and fall of the thermoelectromotive force can be further increased.

[Brief explanation of the drawing]

1 to 5 are explanatory diagrams of an embodiment and operation of the thermocouple according to the present invention, and FIG. 1 is a front sectional view;
Fig. 2 is a sectional view of Fig. 1, Fig. 3 is a perspective view of Fig. 1, Fig. 4 is an explanatory diagram of the operation, Fig. 5 is a circuit diagram of gas equipment equipped with a gas safety valve, Fig. 6 and FIG. 7 are views corresponding to FIG. 1 and FIG. 3 of the conventional product, respectively. Explanation of symbols: 10... Outer tube, 10a... Tip, 11... Core wire, 11a... Tip, B... Thermocouple.

Claims (1)

[Scope of utility model registration request] In a thermocouple, a core wire made of a different metal is inserted into an outer tube made of a heat-resistant metal with a gap around it, and the outer tube and the tip of the core wire are joined to each other. A thermocouple characterized in that the outer tube is deformed into a flat shape, and the tip of the outer tube is also deformed into a flat hollow shape, and the core wire and the tip of the outer tube are integrally joined to each other.