JPH01145538A - Thermistor type temperature sensor - Google Patents

Abstract

PURPOSE:To obtain a temp. sensor excellent in water resistance, by providing unevenness to the surface of the leaf spring and holder inserted in a base composed of a thermoplastic resin. CONSTITUTION:Silver electrodes are baked to both end surfaces of a cylindrical thermistor 1 having an NTC characteristic and held between the spherical protruding parts of leaf springs 2 composed of phosphor bronze. A protruding part 5 is provided to a holder 4 made of a thermoplastic resin to fix the leaf spring 2 and the part bent into an uneven shape of the leaf spring 2 is embedded in a base 3 made of a thermoplastic resin to be molded. When the leading end part 18 of a case 14 is inserted in a temp. detection place and mounted to an actual machine by the screw 19 provided to the case 14 in this constitution, the temp. change of a detection part is taken out of a terminal 7 as the temp. change of a thermistor. Since the close adhesiveness of the material of a base 3 to the contact surface of the leaf spring 2 and the holder 4 is well, a temp. sensor kept from the penetration of water from the outside and excellent in water resistance is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thermistor-type temperature sensor used to detect the temperature of engine cooling water in an automobile.

[Conventional technology]

A conventional temperature sensor for detecting the temperature of engine cooling water used in automobiles is as described in the published utility model No. 54-39084. The temperature detection thermistor is clipped with a leaf spring integrally molded with thermoplastic resin, and the chain leaf spring is connected to an external connection terminal.

[Problem that the invention seeks to solve]

The above-mentioned conventional technology does not take into consideration the airtightness of the leaf spring inserted into the thermoplastic resin base, and has a problem of poor water resistance.

An object of the present invention is to provide a material with excellent water resistance.

[Means for solving problems]

The above object is achieved by providing a plate spring inserted into a thermoplastic resin base and by providing irregularities on the surface of the holder.

[Effect]

Due to the unevenness provided on the surface of the leaf spring and holder, the peeling of the joint surface with the thermoplastic resin is prevented and suppressed by the uneven surface during a cold and heat durability test, and the airtightness of the leaf spring and holder is improved.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 8. 1 is a cylindrical thermistor with NTC characteristics, with silver baked on both end faces to serve as electrodes.

2 is a plate spring made of a phosphor bronze plate whose end surface of the thermistor is made into a spherical surface in contact with the silver electrode, and is set to sandwich the thermistor's picture electrode with a constant pressure. It was inserted when molding the base 3 of nylon 6). FIG. 2 shows the state in which the leaf spring 3 is inserted into the base 3. The holes of the leaf springs are aligned and positioned with the protruding parts 5 provided on the holder 4 made of thermoplastic resin (nylon 6 containing 30% glass), and the protruding parts 5 of the holder are fixed by heat melting.

One end of the leaf spring is provided with a projecting portion 6 that contacts the electrode of the thermistor, and the L-shaped bent portion of the child terminal 7 is fixed to the other end by welding. The shape of the portion of the leaf spring to be embedded in the base 3 is bent into an uneven shape as shown in FIG. 2, and the width is narrowed in several places so that D>d as shown in FIG.

FIGS. 4 and 5 are a front view and an AA sectional view of the holder. One end 8 of the holder 4 is semicircular to match the outer diameter of the cylindrical thermistor 1, and is used for positioning when the thermistor 1 is attached. The groove dimension W provided in the holder 4 is slightly larger than the width dimension of the leaf spring 2, and the leaf spring is inserted into the groove to position the leaf spring. In addition, the width and thickness of the holder are provided with several unevenness such that W>w and B>b.

Figures 6 and 7 show a thermistor holder 9 molded from thermoplastic resin (nylon 6 with 30% glass content), and the tip of the protruding portion 1o at the center is semicircular to suppress the cylindrical thermistor. It is.

Holes 12 are provided at the tips of protrusions 11 at both ends of the bottom of the thermistor holder 9, and are fitted with protrusions 13 on the base to position the thermistor holder in the axial direction. Further, the contact surface between the projecting portion 11 of the thermistor holder and the base 3 is made flat to prevent rotation in the rotational direction. Thermistor 1
Insert the base assembly with the thermistor holder 9 attached into the hollow case 14 made by cutting a hexagonal brass rod, and tighten the open end 15 of the case 14 to tighten the rubber ring O-ring 16 installed on the stepped part of the base. By fitting it into the triangular groove, water is prevented from entering inside the temperature sensor. In order to maintain the airtightness of the joint surface between the terminal 7 and the base 3,
A flexible epoxy resin adhesive 17 is applied.

The thermistor type temperature sensor configured in this manner is attached to an actual device using screws 19 provided in the case 14 such that the case tip 18 is inserted into the temperature detecting location. The temperature change of the detection section is taken out from the terminal 7 as a resistance change of the thermistor.

According to one embodiment of the invention, leaf spring 2. By providing concavities and convexities in the part embedded in the base 3 of the holder 4,
The adhesion between the base material, leaf spring, and holder joint surfaces can be improved, which prevents water from entering from the outside, resulting in a temperature sensor with excellent water resistance. There is. Furthermore, since the lead wire terminal can be eliminated and a temperature sensor with a direct-plug terminal can be used, the cost can be reduced.

〔Effect of the invention〕

According to the present invention, the temperature sensor is subjected to a cold and heat durability test (-20℃
*15 minutes -) 130'CX 15 minutes/1+J-1'km
During o cycles, air bubbles are generated from the joint surface of the terminal 7 and the base 3, resulting in poor airtightness, but with the product of the present invention, which has unevenness on the leaf spring and holder, no airtightness defects occur even after 50 cycles are completed. This has the effect of providing a temperature sensor with excellent water resistance.

[Brief explanation of the drawing]

Fig. 1 is a sectional front view of the present invention, Fig. 2 is a sectional front view of the holder assembly, Fig. 3 is a side view of the holder assembly, Fig. 4 is a front view of the holder, and Fig. 5 is an AA sectional view of the holder. , Figure 6 is a plan view of the thermistor holder,
FIG. 7 is an EE sectional view of the thermistor holder, and FIG. 8 is a front view of the thermistor holder. 1... Thermistor, 2... Leaf spring, 3... Base, 4... Holder, 14... Case.

Claims (1)

[Claims] 1. In the case where the thermistor is a heat-sensitive element and the thermistor is pressed into contact with a fixing plate with spring characteristics embedded in the base at the bottom of the case of a hollow case with only the top open, the fixing plate embedded in the base is made uneven. A thermistor type temperature sensor characterized by being molded.