JPS6219952Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to improving the insulation of the wire junction between the thermocouple and the compensating conductor of a thermocouple thermometer that detects the temperature of internal combustion engines, high-temperature furnaces, etc.

The thermocouple wire and the compensation conductor are welded or brazed at the joint, so that the ends of the wires are exposed and electrically connected. Normally, the compensating conductor is not a single wire in order to provide flexibility, but a stranded wire or a bundled wire consisting of several to several tens of thin wires with a diameter of 0.3 mm or less is used. Therefore, these strands are extremely difficult to weld because they are easily burnt out, and when brazing, the outer part of the strands is not brazed due to the disorder of the strands during cutting, resulting in the whiskers shown in Figure 1a. As the tip bounces off, it may come into contact with one of the wires, causing a short circuit between the two wires, resulting in unmeasurable or unstable contact, resulting in unstable measured values and loss of reliability of measured values. It had a built-in problem.

Furthermore, in order to improve the airtightness of the thermocouple opening, it is known to cover the wire joint portion with insulating rubber. However, this one has a different purpose and has a separate tube cut out at one point for each line, which covers only the strands. By the way, the position of the above-mentioned flying whiskers is not specified, and several lines or two lines may appear. For this reason, when the tube is fitted, it is difficult to completely fit the tube into the tube, and there is a considerable amount of movement in which the whiskers protrude from the cut grooves and come into contact with each other. In order to prevent this, it is necessary for the operator to inspect whether or not the hair is sticking out, and this problem cannot be solved for mass production. As a technology that can solve this problem, a technique for insulating two conductive wires from each other was published in Japanese Patent Application Laid-Open No. 54-61682.
number is known. This product has an elastic insulating tube interposed between the conductors and is built into an insulator with cracks in the axial direction, and is used to coat the metal tube and perform drawing processing, etc. However, since the tube is hollow, when processing the metal tube. The cross-sectional shape is not constant and the position of the line is also unstable, making it uneasy to prevent whiskers.

The purpose of this invention is to provide a thermocouple thermometer of stable quality for mass production by completely isolating the two wires by using a partition member with a shape different from that described above, which has a complete insulation effect against whiskers. .

Embodiments will be described below based on the drawings. Thermocouples are inserted into a metal protective tube 1 of a temperature detection plug and are insulated from each other by being inserted through an insulating insulating tube 1a. The thermocouple wires 2 and 3 have one temperature-sensing end connected to each other by welding or brazing, and the opposite end of the wire protrudes from the metal protection tube 1. Compensating conductor wires 4 made of an alloy having low electrical resistance and equal thermoelectric properties are connected to each pole side of this protruding end. Normally, this compensating lead wire requires flexibility, so a bundled wire is used and insulating coatings 4a, 4b, 4c are applied, and the wires 5, 6 are joined to the thermocouple wire with their polarities matched, The lines are spaced a few mm apart. A partition plate 7a having a gourd-shaped cross section with a constriction in the center and equally sized bulges on both sides is inserted into the gap between the two lines. The partition plate 7a is made of synthetic rubber or resin, such as silicone rubber, which has excellent insulation and heat resistance.
Both ends of the gourd have a length that reaches the inner wall of an insulating ring 9 inserted into a sleeve 8 to be described later that seals the joint, and the length is approximately equal to the exposed length of the joint between the thermocouple wire and the compensation conductor wire. made of equal length. Therefore, by inserting this partition plate 7a, each wire on the positive and negative electrode sides is completely separated from the partition wall, and the inside of the sealing part is divided into two chambers. The thin insulating ring 9 that covers the outer periphery of the partition plate 7a and the compensation conductor 4 is made of heat-resistant synthetic rubber or resin with good insulation, and the exposed wires are insulated around them by an insulating material. They are housed in each room. A metal sleeve 8 is further placed on the outer periphery of the insulating ring 9 over the insulator tube and the compensating conductor, and a metal protective tube 1 is placed at the end of the insulating ring 9.
and the compensating conductor are welded or brazed and fixed by caulking. Further, if the inner wall of the sleeve 8 is coated with a heat-resistant insulating film, such as a ceramic coating, the insulating ring 9 is not necessary.

In this way, this invention interposes a partition plate that is in contact with the inner wall of the sleeve and has a constricted center between the two wires, the thermocouple wire and the compensation conductor wire, so that the protruding wires, such as whiskers, do not cross the partition plate. Short circuit between two wires can be prevented. Furthermore, an insulating member containing the two wires and the partition plate is provided, and each wire is housed in a completely separate chamber, so that the unjoined wire at the end of the bundled wire can be completely insulated. Therefore, it is possible to completely prevent a situation in which temperature measurement becomes unstable or impossible, and the reliability of the meter is improved. Furthermore, the process of mounting the partition plate/insulating member does not require the operator to identify the mounting state, so it has a practical feature that enables mass production through automation.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the sleeve of the sealing part of the thermocouple cut away, and Fig. 2 is a diagram showing the position taken along the line A-A in Fig. FIG. 1... Metal protection tube, 2, 3... Thermocouple wire,
5, 6... Compensation conductor wire, 7a... Partition plate, 8...
...Sleeve, 9...Insulation ring.

Claims (1)

[Scope of utility model registration request] In a thermocouple thermometer housed in a temperature detection plug, the part sandwiched between the two wires is constricted between the two wires of the positive and negative electrodes at the junction of the thermocouple wire and the wire of the compensating conductor. A partition member made of a heat-resistant insulating elastic material having a gourd-shaped cross-sectional shape with a bulge and a full interior is inserted to create two isolated chambers in the detection plug sealing part, and the partition member and the two wires are separated from each other. 1. A thermocouple thermometer, characterized in that it is covered with a metallic sleeve via an insulating ring or an insulating layer of an insulating coating that encloses the two chambers and completely isolates the two chambers.