JP3062429B2 - Temperature detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature detecting device having a metal protection tube containing a temperature detecting element for detecting the temperature of an object to be measured.

[0002]

2. Description of the Related Art In general, as a temperature detecting element used in a temperature detecting device for detecting the temperature of an object to be measured, a temperature measuring resistor utilizing the property that the electric resistance of a metal changes with temperature is used. Thermocouples and the like that use the property (Seebeck effect) of joining two ends of two different metals and generating an electromotive force by a temperature change are widely known.

When a temperature is detected in a liquid or a high-temperature region, a metal protection tube for accommodating the temperature detection element is required to protect the temperature detection element.

Here, a conventional temperature detecting device having a metal holding tube will be described with reference to FIGS.

[0005] First, FIG. 2 shows a first prior art, in which a temperature detecting device 1 has a cylindrical metal holding tube 2 having a bottom portion 2 A at a tip end thereof, and an insertion tube extending axially through the inside of the metal holding tube 2. A hole 3, a temperature detecting element 4 inserted through the insertion hole 3 and disposed on the bottom 2 </ b> A side of the metal holding tube 2, and a temperature detection element 4 provided on the base end side of the metal holding tube 2. , A terminal box 5 having a signal circuit (not shown) or the like built therein, and the insertion hole 3
And a lead wire 6 connected between the temperature detecting element 4 and the terminal box 5.

Here, on the base end side of the metal holding tube 2,
A screw portion 2B, a nut portion 2C, and a male screw portion 2D are sequentially formed toward the distal end side, and the male screw portion 2B is screwed into an opening of the terminal box 5 to connect the terminal box 5 to the metal holding tube 2. Stick to On the other hand, the male screw portion 2D is fixed to an object to be measured (not shown).
The temperature detecting device 1 is mounted on the object to be measured by screwing it in using the device.

In the temperature detecting device 1 according to the prior art configured as described above, the temperature of the object to be measured is detected by the temperature detecting element 4 located at the bottom 2A of the metal holding tube 2, and detected by the temperature detecting element 4. The detected signal is led to a signal circuit in the terminal box 5 via the lead wire 6. Then, the signal circuit outputs the detection signal to the outside as an amplified output signal.

By the way, in the above-mentioned first prior art,
Since the hollow metal holding tube 2 having the bottom 2A at the tip is used, the holding tube 2 is formed with a large wall thickness in terms of strength. For this reason, there is a problem that the transmission speed of the heat transmitted to the temperature detection element 4 via the bottom 2A becomes slow, and when the temperature of the object to be measured changes, the response becomes poor.

In order to enhance the response, the metal holding tube 2 may be made thinner. However, the strength of the metal holding tube 2 is reduced, and the metal holding tube 2 is easily broken.

In order to solve this problem, a second prior art has been proposed.
As a third prior art, a temperature detecting device provided with a metal holding tube as shown in FIGS. 3 and 4 is known.

A temperature detecting device 11 according to a second prior art shown in FIG. 3 has an outer metal protection tube 12 and an inner metal protection tube 12 which is disposed inside the outer metal protection tube 12 and has only a bottom 13A protruding from the tip. A tube 13, an annular joint portion 14 for welding and joining the distal end side of the outer metal protective tube 12 and the outer periphery of the distal end side of the inner metal protective tube 13, and located near the bottom 13A in the inner metal protective tube 13; Temperature detecting element 1 provided
5 and a lead wire 16 inserted into the inner metal holding tube 13 and connecting the temperature detecting element 15 to a signal circuit in a terminal box (not shown).

A temperature detecting device 21 according to a third prior art shown in FIG. 4 is disposed on an outer metal holding tube 22 and a front end side of the outer metal holding space 22, and has a short small diameter with only a bottom portion 23A protruding from the front end. A distal end side metal protection tube 23, a joining portion 24 for welding the distal end of the outer metal holding tube 22 to a base end outer periphery of the distal side metal protection tube 23, and a bottom portion 23 </ b> A of the distal side metal protection tube 23. Temperature detection element 25 located near
And a lead wire 26 inserted into the outer metal holding tube 22 and connecting the temperature detecting element 25 to a signal circuit in a terminal box (not shown).

In the second and third prior arts configured as described above, the inner metal protection tube 13 and the distal metal protection tube 2
3 can be reduced in thickness, and the temperature detecting elements 15 and 2 can be reduced.
5 can increase the speed of heat transfer and the response speed.

[0014]

In the first prior art, the response speed to the temperature change of the object to be measured is slow because the thickness of the metal holding tube 2 is large. There's a problem.

Further, in the second prior art, although the thickness of the inner metal protective tube 13 can be reduced to increase the response speed to a temperature change, the inner metal protective tube 13 has a joint portion 14 formed by welding. Since it is provided on the distal end side of the outer metal protection tube 12 through the through hole, the strength at the joint portion 14 is low and there is a problem in durability. In addition, a pinhole was sometimes generated in the welded portion of the joint 14. For this reason, when these temperature detecting devices 11 are used for measuring the temperature of the liquid, the liquid to be measured penetrates into the temperature detecting element 15 side through the pinhole, and the detection sensitivity of the temperature detecting element 15 is reduced. Problem.

Further, the third prior art has the same problem as the second prior art.

That is, in the third prior art, the thickness of the tip-side metal holding tube 23 is reduced, so that the response speed to a temperature change can be increased. Since it is provided on the distal end side of the outer metal protection tube 22 through the intermediary 24, the strength at the joint 24 is low and there is a problem in durability. In addition, a pinhole was sometimes generated in the welded portion of the joint 24. For this reason, when these temperature detecting devices 21 are used for measuring the temperature of the liquid, the liquid to be measured penetrates into the temperature detecting element 25 side through the pinhole, and the detection sensitivity of the temperature detecting element 25 is reduced. Problem.

The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to provide a temperature detecting device having a metal holding tube capable of increasing the responsiveness and strength to a temperature change. .

[0019]

In order to solve the above-mentioned problems, a temperature detecting device according to the first aspect of the present invention is formed as a large-diameter cylindrical body having a large wall thickness, and the inside thereof is formed in an axial direction. A first metal protective tube that has become a first insertion hole extending, and a large-diameter cylindrical portion having a large wall thickness at the base end and a bottomed small-diameter cylindrical portion having a small wall thickness at the distal end. A second metal protection tube formed integrally with the large-diameter tubular portion and the small-diameter tubular portion and having a second insertion hole extending in the axial direction toward the bottom of the small-diameter tubular portion; A joining portion formed by integrally welding and joining a large-thickness portion on the distal end side of the first metal protection tube and a large-thickness portion on the base end side of the second metal protection tube; Metal protection tube and second
Is inserted between the first insertion hole and the second insertion hole which are communicated with each other by joining the metal protection tube, and is disposed at the small-diameter cylindrical portion of the second metal protection tube. And a temperature detecting element.

According to the above configuration, the distal end of the second metal holding tube is a small-diameter cylindrical portion having a small wall thickness, and the temperature detecting element is disposed at the bottom of the small-diameter cylindrical portion, so that the temperature detecting element is disposed. The thickness of the small-diameter cylindrical portion provided can be reduced, and the responsiveness of the object to be measured to a temperature change can be improved. In addition, since the first metal protection tube and the second metal protection tube are connected to each other at a portion having a large thickness by welding, the strength of the metal holding tube can be increased.

According to a second aspect of the present invention, the large-diameter cylindrical portion and the small-diameter cylindrical portion of the second metal holding tube are formed by cutting means.

According to the above configuration, no joining means such as welding is used between the large-diameter cylindrical portion located on the base end side of the second metal holding tube and the small-diameter cylindrical portion located on the distal end side. Second
Without forming a pinhole communicating with the insertion hole of
It is possible to prevent liquid or the like from entering from entering.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described below with reference to FIG.
This will be described in detail with reference to the accompanying drawings.

In the embodiment, the same components as those of the above-described prior art are denoted by the same reference numerals, and description thereof will be omitted.

In the figure, reference numeral 31 denotes a first metal holding tube constituting the temperature detecting device according to the present embodiment.
Reference numeral 1 denotes a large-diameter cylindrical body having a large wall thickness, and a first insertion hole 32 whose inside extends in the axial direction. Male thread 31A screwed to terminal box 5 described above and nut 3
1B and a male thread portion 31C are sequentially formed. And
The first metal holding tube 31 is screwed into a not-shown temperature measurement object (not shown) using the nut portion 31B, and thereby the first metal holding tube 31 (temperature detection device) is heated. Can be attached to

Reference numeral 33 denotes a second metal holding tube. The second metal holding tube 33 has a large-diameter cylindrical portion 34 located at the base end and having a large wall thickness, and a distal end of the large-diameter cylindrical portion 34. The small-diameter cylindrical portion 35 having a small thickness is formed integrally with the large-diameter cylindrical portion 34 by cutting the tip end side of the large-diameter cylindrical portion 34.
It consists of For this reason, the distal end side of the small-diameter cylindrical portion 35 becomes the small-diameter bottom portion 35A, and the second metal holding tube 23
Is a second insertion hole 36 extending in the axial direction from the opening of the large-diameter cylindrical portion 34 toward the bottom 35A of the small-diameter cylindrical portion 35.

Reference numeral 37 denotes a joint in which the thick portion on the distal end side of the first metal holding tube 21 and the thick portion on the base end side of the second metal holding tube 23 are integrally welded and joined. In the portion, the joining portion 37 can increase the strength by welding a portion having a large thickness. Also, joint 3
By connecting the first metal holding tube 31 and the second metal holding tube 33 at 7, the first insertion hole 32 and the second insertion hole 36 communicate with each other to form an insertion hole 38.

Reference numeral 39 denotes a temperature detecting element. The temperature detecting element 39 is composed of a resistance temperature detector, a thermocouple, or the like. The temperature detecting element 39 is inserted into the insertion hole 38 and has a second metal holding tube. 33 is disposed at the bottom 35A. Further, a detection signal detected by the temperature detecting element 39 is derived from the temperature detecting element 39 via a lead wire 40 inserted into the insertion hole 38 to a signal circuit in the terminal box. .

The temperature detecting device according to the present embodiment is constructed as described above, and its basic operation can be performed almost in the same manner as in the prior art. The temperature detecting element 39 detects the temperature of the object to be measured. This is detected as a detection signal and output to the outside as an output signal by a signal circuit in the terminal box.

Here, in the present embodiment, the temperature detecting element 39
Is located on the bottom portion 35A side where the thickness dimension located on the distal end side becomes the small small-diameter cylindrical portion 35, so that the small-diameter cylindrical portion 3
5, the heat transfer of the object to be measured can be enhanced, the temperature change of the object to be measured can be transmitted to the temperature detecting element 39 with good responsiveness, and the detection accuracy of the temperature detecting device can be improved.

The small-diameter cylindrical portion 3 of the second metal holding tube 33
5 is formed by cutting the distal end side of the large-diameter cylindrical portion 34, and the second metal holding tube 33 is not provided with a joining means such as welding. Formation can be prevented. Therefore, even when a liquid is used as the object to be measured,
Can be prevented from penetrating into the metal holding tube 33, and the responsiveness of the temperature detecting element 39 can be improved and protection can be achieved.

Further, the tip of the first metal holding tube 31 and the second
Is welded to the base end of the metal holding tube 33 by the joining portion 37, so that the joining portions are portions having a large wall thickness, so that the welding strength can be increased.

Further, the portion of the first metal holding tube 31 and the second metal holding tube 33 joined at the joining portion 37 is weak in strength only in the small-diameter cylindrical portion 35 on the distal end side. A portion extending in the axial direction becomes a large-diameter cylindrical portion 34 of the first metal holding tube 31 and the second metal holding tube 33 having a large wall thickness.
For this reason, the bending of the metal holding tubes 21 and 33 can be prevented,
Durability can also be increased.

On the other hand, the length of the first metal holding tube 21 is set to a size corresponding to the object to be measured, and the second metal holding tube 23 is connected to the first metal holding tube 21. If the tip is welded and joined by the joining portion 37, the holding tubes 31, 3
3 can be changed in length, and can correspond to various measurement objects.

[0035]

As described above in detail, according to the first aspect of the present invention, the tip side of the second metal holding tube is a small-diameter cylindrical portion having a small wall thickness, and the bottom of the small-diameter cylindrical portion has a temperature. Since the detection element is provided, the responsiveness to a temperature change of the object to be measured can be increased, and the detection sensitivity can be increased. In addition, since the first metal protection tube and the second metal protection tube are connected to each other at a portion having a large wall thickness by a welded joint, the strength of the metal holding tube is increased and the durability is improved. Can be enhanced.

According to the second aspect of the present invention, the small-diameter cylindrical portion of the second metal holding tube is formed by cutting to thereby provide the second metal holding tube.
No connection means such as welding is used between the large-diameter cylindrical portion located on the base end side of the metal holding tube and the small-diameter cylindrical portion located on the distal end side of the metal holding tube, so that the metal holding tube communicates with the second insertion hole. It is possible to prevent liquid or the like from entering from outside without forming a pinhole, and to protect the temperature detection element.

[Brief description of the drawings]

FIG. 1 is a partially broken front view showing a temperature detecting device according to an embodiment of the present invention.

FIG. 2 is a partially cutaway front view of the temperature detecting device according to the first conventional technique.

FIG. 3 is a longitudinal sectional view showing a distal end side of a metal holding tube and a temperature detecting element according to a second conventional technique.

FIG. 4 is a longitudinal sectional view showing a tip side of a metal holding tube and a temperature detecting element according to a third conventional technique.

[Explanation of symbols]

 31 1st metal holding tube 32 1st insertion hole 33 2nd metal holding tube 34 Large diameter cylindrical part 35 Small diameter cylindrical part 35A bottom 36 Second insertion hole 37 Joining part 38 Insertion hole 39 Temperature detecting element

Claims (2)

(57) [Claims] 1. A first metal protection tube formed as a large-diameter cylindrical body having a large wall thickness and having a first insertion hole extending inside in an axial direction, and a large wall thickness at a base end side. A large-diameter cylindrical part having a small-diameter cylindrical part with a small thickness on the tip side and a large-diameter cylindrical part is formed integrally with the large-diameter cylindrical part and the small-diameter cylindrical part is formed inside. A second metal protection tube serving as a second insertion hole extending in the axial direction toward the bottom portion; a large-thickness portion on the tip side of the first metal protection tube; and a base of the second metal protection tube. A joining portion formed by integrally welding a large-thickness portion on the end side, and a first insertion communicating by joining the first metal protection tube and the second metal protection tube with the joining portion Hole and second
And a temperature detecting element, which is inserted between the insertion hole and the small-diameter tube portion of the second metal protection tube and is disposed. 2. The temperature detecting device according to claim 1, wherein the large-diameter cylindrical portion and the small-diameter cylindrical portion of the second metal holding tube are formed by cutting means.