JP2001141573A - Temperature sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve responsiveness by filling a clearance between a housing and a thermal element with a small amount of a heat transfer material. SOLUTION: Two lead parts 3 are connected to a thermal element 2 constructed of a NTC thermistor. The thermal element 2 and the tips of the lead parts 3 are molded by means of a protective sealing layer 7. By insert molding of the base end side of the lead part 3, a resin base 4 having a connector part 8 is arranged. A cap-shaped housing 5 is put over the thermal element 2 and the lead parts 3 so as to be connected to the resin base 4. Inside the tip part of the housing 3, a clearance between its inside wall and the thermal element 2 (sealing layer 7) is tightly filled with a paste type heat transfer material 10 so that a clearance S is formed between the inner circumference wall part and the exposed parts in the lead parts 3. As the heat transfer material 10, a silicone compound with high heat conductivity is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature sensor in which a thermosensitive element is provided in a cap-shaped housing.

[0002]

As a temperature sensor used for detecting a water temperature of an automobile, for example, a thermistor sealed with epoxy resin in a cap-shaped metal housing and a tip connected to the thermistor are used. In some cases, a housing is connected to a resin base to which the base end side of the metal lead is connected while accommodating a plate-shaped metal lead. In this case, a connector housing is provided integrally with the resin base, and the base end side of the metal lead is insert-molded to form a connector portion having a terminal portion (base end portion of the metal lead) inside the connector housing. Are formed integrally.

In such a temperature sensor, for example, as disclosed in JP-A-8-184507, the entire interior of the housing, that is, the thermistor (sealing resin) and the metal leads and the inner wall of the housing are connected. In the meantime, it has been considered to fill a heat transfer material. According to this,
Due to the heat transfer material, compared to the case where there is an air layer inside,
Heat transfer from housing to thermistor (heat transfer speed)
And good responsiveness can be achieved. As the heat transfer material, a liquid having good heat conductivity such as silicone oil may be used.

However, when the heat transfer material is filled in the entire interior of the housing as described above, the heat transfer material also exists around the metal lead, and the amount of the heat transfer material charged increases. (For example, 0.5 ml or more), there is a problem that waste is increased. In addition, it is necessary to house a large amount of heat transfer material in the housing in advance and wipe off the protruding heat transfer material after connection with the resin base, which makes the assembly operation troublesome. In addition, the sealing between the housing and the resin base must be strictly performed so that the filled heat transfer material does not leak to the outside. Therefore, it is necessary to seal the gap, and the structure for that purpose is complicated.

The present invention has been made in view of the above circumstances, and has as its object to fill a space between a housing and a heat-sensitive element with a heat-transfer material to improve responsiveness.
It is an object of the present invention to provide a temperature sensor capable of reducing the amount of heat transfer material to be filled.

[0006]

In order to achieve the above object, a temperature sensor according to a first aspect of the present invention is connected to a resin base at a base end side in a state where a thermosensitive element is housed inside a front end portion. In the cap-shaped housing, a heat transfer material is filled between the inner wall of the distal end portion of the housing and the heat-sensitive element so that a space is formed around a lead portion connected to the heat-sensitive element. It is composed.

According to this, since the heat transfer material is interposed between the housing and the heat-sensitive element, the heat transfer (heat transfer speed) from the housing to the heat-sensitive element is improved, and the responsiveness is improved. Can be. At this time, the heat transfer material does not fill the entire internal space of the housing, but only fills the periphery of the heat sensitive element, and a space is provided around the lead portion. Can be reduced. In addition, when filling the heat transfer material, it is sufficient that a required amount of the heat transfer material is housed in the housing in advance and the heat sensitive element or the like is assembled, so that the assembling work can be easily performed. it can.

When a liquid material is used as the heat transfer material in the above-described configuration, it is necessary to take measures to prevent the heat transfer material from flowing from the peripheral portion of the heat-sensitive element to the space around the lead portion. It is also necessary to prevent the heat transfer material from leaking to the outside. In this case, as a simple configuration,
For example, a thermosensitive element is sealed with a resin, and the sealing resin is
Although it is conceivable to provide a seal portion in close contact with the inner surface of the housing to prevent the heat transfer material from flowing out, a high dimensional accuracy is required and a stress tends to act on the heat-sensitive element.

Therefore, a paste-like heat transfer material can be employed (the invention of claim 2). According to this, even if there is a gap between the heat-sensitive element (sealing resin) and the inner surface of the housing, the heat transfer material does not flow out from the peripheral portion of the heat-sensitive element, so that no special sealing structure is required. And a very simple configuration can be achieved. Also, no stress acts on the thermosensitive element. In addition, as such a paste-like heat transfer material, a silicone compound or the like can be employed.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a temperature sensor used for detecting, for example, a water temperature of an automobile will be described below with reference to the drawings. FIG. 1 shows a configuration of a temperature sensor 1 according to the present embodiment. The temperature sensor 1 includes, for example, a thermosensitive element 2 composed of an NTC type thermistor, and two lead portions 3 connected to the thermosensitive element 2. And a cap-shaped housing 5 provided so as to cover the heat-sensitive element 2 and the lead portion 3.

As shown in FIG. 2, each of the two lead portions 3 is made of a metal plate such as a copper plate, for example, and has a long narrow shape which is long in the vertical direction in FIG. More specifically, the lead 3 is located at the tip (lower end in FIG. 1) and has a thinner and thinner element connecting portion 3a, and is located at the base (upper end in FIG. 1). It has a form in which a slightly wide terminal portion 3b to be a terminal of a connector portion to be connected and a connecting portion 3c extending in a vertical direction so as to connect them are integrally provided. The upper end portion of the terminal portion 3b is provided with gold plating 6 (hatched in the drawing for convenience).

The heat-sensitive element 2 includes the two lead portions 3.
Are soldered to the element connection portions 3a so as to be sandwiched between the element connection portions 3a. Then, the thermosensitive element 2 and the element connecting portion 3a at the tip of both lead portions 3 are:
For example, the protective sealing layer 7 is formed by molding with an epoxy resin. In this state, the two lead portions 3 extend in parallel at a fixed interval, and at this time, the interval between the terminal portions 3b is slightly wider than the interval between the connecting portions 3b.

On the other hand, the resin base 4 integrally has a connector housing portion 4b having an open upper surface in FIG. 1 at a base end side (upper end side in FIG. 1) of a large-diameter cylindrical main portion 4a. The main portion 4a is integrally formed with a small-diameter projecting portion 4c extending downward from the center of the lower surface of the main portion 4a. A constricted portion 4d for caulking the housing 5 is formed on the outer periphery of the main portion 4a.

The two leads 3 are insert-molded in the resin base 4 so that their base ends are held by the resin base 4. At this time, almost the lower half of the terminal portion 3b of the lead portion 3 is embedded in the main portion 4a of the resin base 4, and the upper end portion (the portion where the gold plating 6 is applied) of the terminal portion 3b is formed as described above. The connector section 8 is located in the connector housing section 4b and configured to connect to an external circuit. Further, a portion of the connecting portion 3c of the lead portion 3 except for the lower end portion is embedded in the projecting portion 4c.

The housing 5 is formed of a metal (for example, brass) in the shape of a cylindrical cap having a vertically long surface and a closed lower surface. A large-diameter cylindrical portion 5a is provided at the base end (upper end in FIG. 1). It is constituted to have integrally. The cylindrical part 5
a has an inner diameter corresponding to the outer diameter of the lower end of the main portion 4a of the resin base 4, and the upper half of the peripheral wall portion is a thin portion 5b for caulking. The inner diameter of the hollow portion of the housing 5 corresponds to the outer diameter of the protruding portion 4c of the resin base 4, and a small diameter portion 5c having a slightly smaller diameter is provided at the lower end. .

The housing 5 has, in the hollow portion thereof, the thermosensitive element 2 (sealing layer 7), the connecting portion 3 of the lead portion 3,
With the protruding portion 4c of the resin base 4 inserted, the cylindrical portion 5 is fitted to the lower end of the main portion 4a of the resin base 4, and the thin portion 5b is located on the inner peripheral side with respect to the constricted portion 4d. By being caulked, it is connected to the resin base 4. At this time, the sealing layer 7 that seals the heat-sensitive element 2 is located within the small-diameter portion 5c at the distal end of the housing 5 with a slight gap between the small-diameter portion 5c and the inner peripheral surface. It has become so. A seal 9 for sealing is interposed between the resin base 4 and the housing 5.

The small-diameter portion 5c at the distal end of the housing 5 is densely filled between the inner wall thereof and the heat-sensitive element 2 (sealing layer 7) so as to form a paste-like conductive material. Heating material 10 is provided. At this time, the filling amount of the heat transfer material 10 is
A space S is formed between the portion of the connecting portion 3c of the lead portion 3 exposed from the projecting portion 4 and the inner peripheral wall portion of the housing 5 in a small amount (for example, about 0.1 ml). It has become. In this embodiment, a silicone compound (for example, Toshiba Silicone “YE6240”) is used as the heat transfer material 10. This heat transfer material 10
Has a thermal conductivity of 0.84 W / (m · K).

Here, the procedure for assembling the temperature sensor 1 configured as described above will be described with reference to FIG. That is, first, the step of soldering and connecting the element connection portions 3a of the two leads 3 to the thermosensitive element 2 is executed (step P).
1). At this time, the two lead portions 3 are provided as a connected body connected by the tie bar 11. Subsequently, the thermosensitive element 2 and the element connection part 3a are resin-molded to form the sealing layer 7 (step P2).

Next, the tie bar 11 is cut and removed, and the leads 3 are insert-molded to form the resin base 4 in a state in which the base end of the lead 3 is held (step P3). Then, a predetermined amount (approximately 0.1
ml) of the heat transfer material 10 (step P4), and then the heat-sensitive element 2 (sealing layer 7) and the protruding portion 4c of the resin base 4 are inserted into the housing 5 with the packing 9 interposed. The resin base 4 is fitted and connected (step P5). Thus, the temperature sensor 1 in which the paste-like heat transfer material 10 is filled between the inner wall of the distal end portion of the housing 5 and the heat-sensitive element 2 (the sealing layer 7) is formed.

In the temperature sensor 1 having the above structure, the heat transfer material 10 is provided between the housing 5 and the heat-sensitive element 2 (sealing layer 7).
, The heat transfer (heat transfer speed) from the housing 5 to the thermosensitive element 2 can be improved, and the response as a sensor can be improved. FIG. 3 shows a test result obtained by examining the responsiveness of the temperature sensor 1 of the present embodiment by the present inventor.

In this test, as shown in FIG.
In addition to the temperature sensor 1 of the present embodiment (which employs a silicone compound "YE6240" as the heat transfer material 10), for comparison, a liquid silicone oil (Shin-Etsu Silicone "KF96") as described in the conventional example is used for comparison. ) Were filled in the entire interior of the housing, and a temperature sensor in which no heat transfer material (filling material) was present (the inside of the housing was an air layer) was also tested. The silicone oil has a kinematic viscosity of 500 mm 2 / s and a thermal conductivity of 0.16 W / (m · K). The thermal conductivity of air is 0.024 W / (m · K).

In the test, a change in the resistance value over time when the temperature sensors were put into water at 100 ° C. from an atmosphere at 20 ° C. (the time when the change in the resistance value reached 63.2%) was measured. By examining two samples each. The result is shown in FIG. 6 changes in resistance
The average time to reach 3.2% is the temperature of the temperature sensor 1 of this embodiment.
Is 4.3 seconds, 6.5 seconds using liquid silicone oil, and 14.1 seconds using air layer. The response of the temperature sensor 1 of this embodiment is extremely good. It has become.

In this embodiment, the heat transfer material 10 is not filled in the entire inner space of the housing 5 but is filled only in the peripheral portion of the heat-sensitive element 2 (sealing layer 7).
Since the space S is provided around the (exposed portion of the connecting portion 3c), the filling amount of the heat transfer material 10 can be reduced. More specifically, in the conventional case where the entire inside of the housing is filled with the heat transfer material, a filling amount of 0.5 ml or more is required.
A filling amount of 1 ml was sufficient, and the filling amount could be significantly reduced.

Moreover, in this embodiment, since the paste-like heat transfer material 10 is employed, unlike the heat-transfer material such as the liquid-like material, the heat-transfer material 10 may flow in the housing 5 or leak to the outside.
Even if there is a gap between the sealing layer 7 that seals the thermosensitive element 2 and the inner peripheral surface of the housing 5, the heat transfer material 10 does not flow from the peripheral portion of the thermosensitive element 2 and move. As a result,
It is not necessary to provide a special seal structure for filling the heat transfer material 10 only in the peripheral portion of the heat sensitive element 2, so that the structure can be simplified and the assembling work can be simplified. Inconveniences such as an adverse effect on the characteristics due to the action of the stress can also be prevented.

As described above, according to this embodiment, the responsiveness can be improved by filling the heat transfer material 10 between the housing 5 and the heat-sensitive element 2 (sealing layer 7). Since the material 10 is filled only in the peripheral portion of the sealing layer 7, an excellent effect that the amount of the heat transfer material 10 to be filled can be reduced to a necessary minimum amount can be obtained. Moreover, in this embodiment, since the paste-like heat transfer material 10 is employed, the heat transfer material 1
There is no danger of zero flowing, and a simple configuration is sufficient, and advantages such as improved assembling workability can be obtained.

In the above embodiment, the heat transfer material 10 is
Although a silicone compound is used, various materials can be used for the heat transfer material, and by using heat transfer materials with various thermal conductivity, there is no need to change other parts In addition, a desired responsiveness can be obtained. In this case, a liquid heat transfer material can be employed by, for example, bringing the outer periphery of the sealing layer 7 into close contact with the inner peripheral surface of the housing 5 or providing a separate sealing material.

In the above embodiment, the terminal 3b
Although the lead portion 3 made of a plate-like metal integrally having the above structure is adopted, a configuration in which the thermal element is connected to the terminal portion buried in the resin base by a lead wire may be adopted. Further, as the material of the sealing layer for molding the thermosensitive element, various materials other than epoxy resin can be used, and glass and the like can be used.

In addition, the shape, structure, material and the like of the resin base and the housing constituting the temperature sensor can be variously modified, and the filling amount of the heat transfer material is merely an example. The present invention can be applied to various temperature sensors for various uses other than for detecting the water temperature of an automobile, for example, and the present invention can be appropriately modified and implemented without departing from the gist of the present invention.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention, and is a longitudinal sectional view of a temperature sensor.

FIG. 2 is a diagram showing a procedure for assembling a temperature sensor.

FIG. 3 is a diagram showing a test result of examining the responsiveness of a temperature sensor.

[Explanation of symbols]

In the drawing, 1 is a temperature sensor, 2 is a thermosensitive element, 3 is a lead part, 3a is an element connecting part, 3b is a terminal part, 3c is a connecting part, 4 is a resin base, 4b is a connector housing part, 4c is a protruding part, Reference numeral 5 denotes a housing, 7 denotes a sealing layer, 8 denotes a connector portion, 10 denotes a heat transfer material, and S denotes a space.

Claims (2)

[Claims] 1. A heat-sensitive element, a lead having a tip connected to the heat-sensitive element, a resin base connected to a base end of the lead and forming a connector, and the heat-sensitive element housed inside the tip. And a cap-shaped housing connected to the resin base on the base end side in a state in which the lead portion is formed in the housing so that a space is formed around the lead portion in the housing. A temperature sensor, wherein a heat transfer material is filled between an inner wall and the thermosensitive element. 2. The temperature sensor according to claim 1, wherein the heat transfer material is in the form of a paste.