JPS6110192Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to the structure of a water temperature meter unit that measures water temperature by directly immersing it in the water to be measured.
It is characterized in that a pipe-shaped thermistor element is fitted into a convex portion provided at the bottom of the inner surface of a metal case, and is pressed down with a metal disk.

As shown in Fig. 1, in a conventional water temperature meter unit, a disc-shaped thermistor element 1 with electrodes provided on the top and bottom is soldered at one end to the bottom of the inner surface of a metal case 2 with a hollowed out interior. Generally, the lead wire 3 is taken out by soldering, and the opening of the metal case 2 is sealed with an insulating resin 4. This unit is mainly used to measure the temperature inside automobile radiators, but due to its structure, problems with vibration resistance remain.

The present invention addresses this problem by providing a water temperature meter unit that can use conventional general-purpose thermistor materials and has excellent vibration resistance by integrating the thermistor element and metal case. .

The present invention will be explained by way of examples with reference to FIGS. 2 to 4. The thermistor material is tempered with a known Mn-Ni-Cr composition, formed into a pipe shape using an extrusion method, cut, and fired. Place electrodes on the inside and outside of the pipe. FIG. 2 shows a pipe-shaped thermistor element 5 having this negative temperature coefficient, and electrodes 7 are provided on the inner and outer walls of the thermistor element 6. The dimensions of this thermistor element 5 are an outer diameter of 5 mmφ,
The inner diameter is 3mmφ and the height is 8.7mm. On the other hand, as shown in FIG. 3, the metal case 8 is made of brass, for example, and is hollowed out leaving a protrusion 9 with a diameter of 2.9 mmφ and a height of 8.5 mm at the bottom of its inner surface. Further, the outer upper part of the case 8 is threaded for a radiator device. Then, as shown in FIG. 4, the pipe-shaped thermistor element 5 is fitted into the convex portion 9 of the metal case 8, and electrically connected to the metal case 8. Next, a metal disk 11 integrated with a lead wire 10 having a diameter of 5.1 mm and a fold of 2 mm is placed over the element 5, and the element 5 is pressed into the case 8. As a result, the lead wire 10 and the electrode 7 on the outside of the element 5 are electrically connected and taken out to the outside. The opening of the metal case 8 was sealed with an insulating resin 12 or the like as before, except for the lead wire 10. The resistance value of this water temperature gauge unit is 40
It is 600Ω at ±0.2℃ and 77.0Ω at 100±0.2℃. In addition, as a result of vibration testing this water temperature meter unit in accordance with JIS, D1601, the resistance value change rate after the test was ±3.2% compared to ±5% when using a 1.7 mm thick disk type thermistor element. It was within Furthermore, as a result of accelerated testing, out of 50 disk-type thermistor elements tested, 10 had disconnections between the metal case and the soldered part of the element, and 4 had disconnections between the element and the lead wire. In the unit, under the same test conditions, there were only four disconnections at the connection between the metal disk and the lead wire, and there were no contact failures between the metal case and the element or between the element and the metal disk.

As described above, the water temperature meter unit of the present invention not only has a pipe-shaped thermistor element that is resistant to vertical loads, but also has excellent vibration resistance including the element holding means, and is extremely effective against severe vibration modes such as those found in automobiles. It is industrially useful as an automobile part.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a conventional water temperature meter unit;
Figures 3 and 3 are cross-sectional views of the pipe-shaped thermistor element and metal case that constitute the unit of the present invention;
The figure is a sectional view showing one embodiment of the water temperature meter unit according to the present invention. 5... Pipe-shaped thermistor element, 7... Electrode,
8...Metal case, 9...Protrusion, 10...Lead wire, 11...Metal disk.

Claims (1)

[Scope of utility model registration request] A pipe-shaped thermistor element with a negative temperature coefficient with electrodes attached to the inner and outer walls is fitted into a convex part provided on the bottom of the inner surface of the metal case, and this thermistor element is connected to the metal using a metal disc with lead wires attached. A water temperature gauge unit that is pressed into the case.