JPH10300589A - Manufacture of thermistor type water temperature sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water temperature sensor excellent in airtightness. SOLUTION: A bottomed resin case 12 having an opening and provided with a screw at the outer circumferential part is produced at first. A thermistor element 1 connected with terminals 4a, 4b is then encased in the resin case 12 and the terminals 4a, 4b are led out to the outside of the resin case 12. Finally, a connector 7 is manufactured by insert molding at the opening of the resin case 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a thermistor type water temperature sensor for detecting a water temperature in a radiator of an automobile and used as a temperature detection sensor for engine control.

[0002]

2. Description of the Related Art A method of manufacturing a conventional thermistor type water temperature sensor will be described.

First, a thermistor element to which a terminal is connected is covered with a resin in a desired shape. Next, this was insert-molded to form a screw function on the outer peripheral portion and to form a connector.

[0004]

According to this method, when the thermistor element is insert-molded, the thermistor element is displaced, and the resin-exposed thermistor element is exposed to the outside, thereby deteriorating the airtightness. Had.

Accordingly, an object of the present invention is to provide a thermistor-type water temperature sensor having excellent airtightness.

[0006]

In order to achieve this object, a method of manufacturing a thermistor type water temperature sensor according to the present invention is directed to a method of manufacturing a bottomed resin case having an opening and having a screw function on an outer peripheral portion. Step 1, a second step of housing the thermistor element connected to the terminal in the resin case and pulling the terminal out of the resin case, and then inserting a connector into the opening of the resin case by insert molding. Since the method includes the third step of manufacturing, and the thermistor element is not exposed to the outside, the above object can be achieved.

[0007]

DETAILED DESCRIPTION OF THE INVENTION The invention according to claim 1 of the present invention comprises a first step of producing a bottomed resin case having an opening and having a screw function on the outer periphery, and then the resin case. A second step of accommodating a thermistor element having a terminal connected therein and pulling the terminal out of the resin case; and a third step of producing a connector by insert molding in the opening of the resin case. And a method for manufacturing a thermistor-type water temperature sensor, which is excellent in airtightness.

According to a second aspect of the present invention, in the first step, the resin case is made of one of a polyetherimide resin and a polyphthalamide resin. Method
A resin case having a screw function can be obtained.

According to a third aspect of the present invention, in the first step, a groove is formed in the outer peripheral portion on the other end side of the resin case, and at least one through hole is provided inside the groove. The method of manufacturing a thermistor-type water temperature sensor of
In this step, the resin flows into the groove through the through hole, so that the connection between the connector and the resin case can be strengthened.

An embodiment of the present invention will be described below with reference to the drawings. (Embodiment 1) FIG. 1 is a front sectional view of a thermistor-type water temperature sensor according to the present embodiment, and FIG. 2 is a side sectional view of the same. 1 is housed in a bottomed resin case 12, and a connector 7 is connected to an opening of the resin case 12. Here, the lead wires 2a, 2b are insulated tubes 3a, 3
b. A groove 8 is provided in the outer peripheral portion of the resin case 12 from the opening side, and two through holes 9, a hexagon nut 6, and a screw 10 are provided inside the groove 8. Further, the terminals 4a and 4b are used as terminals of the connector 7.

A method for manufacturing the thermistor type water temperature sensor will be described. First, transition metal oxides (Mn, Ni,
A pair of Ag electrodes are provided on the surface of a parallelepiped of a rectangular parallelepiped thermistor element 1 of 1.5 mm × 0.5 mm square made of Co). Next, one ends of lead wires 2a, 2b made of Ag-plated phosphor bronze covered with insulating tubes 3a, 3b made of a fluorine-based material are connected to the electrodes of the thermistor element 1. Next, the connection portion between the thermistor element 1 and the thermistor element 1 and the lead wires 2a and 2b is dipped in a thermosetting resin and dried.

Next, terminals 4a and 4b are connected to the other ends of the lead wires 2a and 2b. Here, lead wires 2a, 2b
Phosphor bronze is used for the terminals 4a and 4b so that they can be welded. To prevent oxidation, the terminals 4a and 4b have Sn
Plated.

Next, the terminals 4a and 4b are inserted into a terminal fixing block of an insert molding die, and the upright or laid-down thermistor element 1 is covered with a resin case 12 formed by injection molding. Then, the resin case 12 is pre-tightened, and immediately before the insert molding, the resin case 12 is fully tightened. The mechanical strength is large, and the insert molding is performed using a thermoplastic resin having poor water absorption. Form. Since the thermoplastic resin has poor fluidity, the thermoplastic resin is injected from the through hole 9 of the groove 8 provided on the outer peripheral portion of the resin case 12. This makes it easier for the thermoplastic resin to flow in the groove 8. The connector 7 is formed in a shape that can be fitted with a mating connector.

Here, important matters will be described. (1) At least one or more through holes 9 are provided. In the case where a plurality is provided, they are formed radially. A slit may be formed in the circumference of the opening of the resin case 12 instead of the through hole 9.

(2) At least one protrusion 13 is provided at the upper end of the opening of the resin case 12, and the protrusion 13 is melted during insert molding, so that the connection between the resin case 12 and the connector 7 can be further strengthened. At the same time, intrusion of liquid or gas such as moisture from the connection portion between the resin case 12 and the connector 7 can be prevented.

(3) Since the screw 10 is formed using the same material as the resin case 12, the screw 10 can be arbitrarily machined according to the screw shape on the side where the thermistor type water temperature sensor is mounted.

(4) The resin case 12 is made of either polyetherimide resin or polyphthalamide resin, and these resins have a mechanical strength similar to that of a metal such as brass. It is.

(5) A nut is provided near the opening of the resin case 12 so that the thermistor-type water temperature sensor can be attached using a wrench when it is attached.

(6) When the resin case 12 is made of the same material as the resin to be insert-molded, the weldability of the interface between the resin case 12 and the connector 7 is improved.

(7) By coating the surface of the screw 10 with a fluorine-based or silicon-based resin,
The airtightness between the zero and the side to which the thermistor-type water temperature sensor is attached is improved, and the airtightness is hardly removed.

(8) The terminals 4a and 4b are provided with at least one bent portion or uneven portion so that the connector 7
Can be prevented from coming off.

[0022]

According to the present invention, a thermistor-type water temperature sensor for controlling an engine, which is excellent in airtightness, can be obtained.

[Brief description of the drawings]

FIG. 1 is a front sectional view of a thermistor type water temperature sensor according to an embodiment of the present invention.

FIG. 2 is a side sectional view of the same.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Thermistor element 2a Lead wire 2b Lead wire 3a Insulation tube 3b Insulation tube 4a Terminal 4b Terminal 6 Nut 7 Connector 8 Groove 9 Through hole 10 Screw 12 Resin case 13 Projection

Claims (3)

[Claims] 1. A first step of producing a bottomed resin case having an opening and a screw function on an outer peripheral portion, and then accommodating a thermistor element having a terminal connected in the resin case and the terminal. A second step of drawing a connector out of the resin case, and a third step of producing a connector by insert molding in the opening of the resin case.
A method for manufacturing a thermistor-type water temperature sensor comprising the steps of: 2. The method for manufacturing a thermistor-type water temperature sensor according to claim 1, wherein in the first step, the resin case is made of either polyetherimide resin or polyphthalamide resin. 3. The method of manufacturing a thermistor-type water temperature sensor according to claim 1, wherein in the first step, a groove is formed in the outer peripheral portion on the other end side of the resin case, and at least one through hole is provided inside the groove. Method.