JP5326854B2 - Temperature sensor and manufacturing method thereof - Google Patents

Description

  The present invention relates to a temperature sensor including a temperature-sensitive element whose electrical characteristics change with temperature.

As a temperature sensor for measuring the temperature of an automobile exhaust gas or the like, there is a temperature sensor using a temperature sensitive element such as a thermistor element whose resistance value changes with temperature.
As shown in FIGS. 8 and 9, the temperature sensor 9 is in a state in which the temperature sensing element 92 and a pair of signal lines 94 respectively connected to the pair of electrode wires 93 of the temperature sensing element 92 are exposed to the distal end side. And a built-in sheath pin 95.

The electrode line 93 and the signal line 94 can be welded by laser (Patent Document 1). That is, as shown in FIG. 10, a pair of electrode lines 93 and a pair of signal lines 94 are overlapped, and from a direction parallel to the overlapping surface, that is, the center of the electrode lines 93 and the center of the signal lines 94 From the direction perpendicular to the straight lines M1 and M2 connecting the two, the contact portion between the electrode line 93 and the signal line 94 is irradiated with the laser L to weld them together.
In such a state, laser irradiation is performed on the overlapping portion 914 of the electrode line 93 and the signal line 94, whereby the temperature sensor 9 is oriented with respect to the laser L oscillated in the fixed laser source. If reversed to the center, the overlapping portions 914 of the two sets of electrode lines 93 and signal lines 94 can be easily welded.

Japanese Unexamined Patent Publication No. 2000-97781

However, the temperature sensor 9 manufactured as described above is a junction between the electrode line 93 and the signal line 94 from the viewpoint of increased exhaust pipe vibration and exhaust gas temperature increase accompanying the recent increase in engine output. The strength becomes insufficient, and in some cases, there is a possibility of breaking at the weld.
The reason is considered to be that it is difficult to obtain a welded portion by laser welding as follows.

  That is, the portion where the electrode line 93 having a circular cross section and the signal line 94 are overlapped is a line contact. When the laser is irradiated from the direction perpendicular to the electrode line 93 and the signal line 94 and parallel to the overlapping surface with respect to the line contact portion, when viewed from the direction of the laser L, the overlapping portion A gap is likely to occur in 914. Therefore, the laser L passes through the surfaces of the electrode line 93 and the signal line 94, and a large energy is locally applied to the electrode line 93 and the signal line 94. As a result, the electrode line 93 and the signal line 94 may be exposed, peeled off, or sputtered (spattering of material), and the bonding strength may be reduced.

  In general, the electrode line 93 and the signal line 94 are made of different materials and have the same melting point with respect to the electrode line 93 and the signal line 94, that is, with respect to the electrode line 93 and the signal line 94. When laser welding is performed with the distance of the focal point F of the laser L being equal, melting variation due to a difference in melting point occurs, and the bonding strength may be insufficient. Here, the state where the distance of the focal point F of the laser L with respect to the electrode line 93 and the signal line 94 is more specifically, for example, as shown in FIG. 10, the position where the laser L is irradiated to the electrode line 93. This means that E1 and the position E2 at which the laser L is applied to the signal line 94 have the same distance from the focal point F.

  It should be noted that in order to easily weld the overlapping portions 914 of the two sets of electrode wires 93 and signal lines 94, it is also conceivable to irradiate the respective overlapping portions 914 with laser from an oblique direction. However, in this case, it is difficult to manage the laser irradiation angle, and the productivity may be reduced.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a temperature sensor excellent in bonding reliability between an electrode line and a signal line and a method for manufacturing the same.

According to a first aspect of the present invention, a temperature-sensitive element whose electrical characteristics change with temperature and a pair of substantially circular signal lines welded to a pair of substantially circular electrode wires of the temperature-sensitive element are exposed to the tip side. A temperature sensor with a built-in sheath pin,
In the cross section orthogonal to the axial direction, a straight line connecting the one electrode line and the signal line welded to each other at each center, and the other electrode line and the signal line welded to each other at each center. The connecting straight lines intersect each other non-parallel at an angle of 15 to 75 ° ,
A temperature sensor characterized in that a distance between centers of the pair of electrode lines is smaller than a distance between centers of the pair of signal lines, and the pair of electrode lines is located inside the pair of signal lines. (Claim 1).

According to a second aspect of the present invention, a temperature-sensitive element whose electrical characteristics change with temperature and a pair of substantially circular signal lines welded to a pair of substantially circular electrode wires of the temperature-sensitive element are exposed to the tip side. A method of manufacturing a temperature sensor having a built-in sheath pin
The center-to-center distance between the pair of electrode lines is smaller than the center-to-center distance between the pair of signal lines, and the pair of electrode lines are positioned inside the pair of signal lines,
In a cross section orthogonal to the axial direction, a straight line connecting one electrode line and the signal line welded to each other at each center, and the other electrode line and the signal line welded to each other at each center. With the electrode lines and the signal lines in contact with each other so that the connecting straight lines intersect each other non-parallel at an angle of 15 to 75 ° ,
Welding the electrode line and the signal line by irradiating a laser near a contact portion between the electrode line and the signal line from a direction parallel to a straight line connecting the centers of the pair of signal lines. The temperature sensor manufacturing method is characterized in that (claim 8 ).

In the temperature sensor according to the first aspect of the present invention, in the cross section orthogonal to the axial direction, the straight line connecting one of the electrode lines and the signal line welded to each other at the center and the other of the other welded to each other. The straight lines connecting the electrode lines and the signal lines at the respective centers are not parallel to each other. Therefore, when welding the overlapping portions of two sets of electrode lines and signal lines, respectively, the laser is overlapped with the overlapping portion of one electrode line and the signal line, and the overlapping portion of the other electrode line and the signal line. It becomes easy to irradiate from both directions.
That is, after irradiating the overlapping portion of one electrode line and the signal line from an oblique direction, for example, by inverting (rotating 180 °) the temperature sensor, the other electrode line and the signal line are overlapped. Similarly, it becomes possible to irradiate the laser beam from an oblique direction.

  In addition, as described above, since laser irradiation can be easily performed from an oblique direction with respect to the overlapping portion of the electrode line and the signal line, the laser energy is not applied to the electrode line or the signal line locally but to a certain large area. Can be granted. As a result, welding can be performed while preventing the electrode line and the signal line from being exposed, peeled off, and sputtered (spattering of the material). As a result, it is possible to prevent the bonding strength between the electrode line and the signal line from decreasing.

  Moreover, the fact that laser irradiation can be easily performed from an oblique direction with respect to the overlapping portion of the electrode line and the signal line means that the distance between the electrode line and the signal line from the laser light source can be easily changed. It becomes. Therefore, the distance from the focal point of the laser can be changed between the electrode line and the signal line. Therefore, when the electrode line and the signal line are made of different materials and have different melting points, the variation in melting caused by the difference in melting point can be suppressed by bringing the focal point closer to the higher melting point. As a result, the joint strength of the welded portion can be improved.

According to the second aspect of the invention, the laser is irradiated from an oblique direction to both the overlapping portion of one electrode line and the signal line and the overlapping portion of the other electrode line and the signal line. It becomes easy. As a result, welding can be performed while preventing the electrode line and the signal line from being exposed, peeled off, and spatter (spattering of the material), and the bonding strength between the electrode line and the signal line can be prevented from being lowered. it can.
Further, even when the electrode line and the signal line are made of different materials and have different melting points, it is possible to suppress the melting variation due to the melting point difference by bringing the focal point closer to the higher melting point.

  As described above, according to the present invention, it is possible to provide a temperature sensor excellent in bonding reliability between an electrode line and a signal line and a manufacturing method thereof.

In Example 1, (A) It is sectional drawing of an electrode wire and a signal wire | line, Comprising: The sectional view on the AA line of (B), (B) Side surface explanatory drawing of the front-end | tip part of a temperature sensor. FIG. 3 is an explanatory plan view of the tip portion of the temperature sensor in the first embodiment. FIG. 3 is a longitudinal sectional view of the temperature sensor in the first embodiment. In Example 1, (A) Explanatory drawing of the laser welding method of one electrode wire and a signal line, (B) Explanatory drawing of the laser welding method of the other electrode wire and a signal wire | line. FIG. 3 is an explanatory diagram of a positional relationship between electrode lines and signal lines in the first embodiment. In Example 2, (A) It is sectional drawing of an electrode wire and a signal wire | line, Comprising: BB sectional view taken on the line of (B), (B) Side surface explanatory drawing of the front-end | tip part of a temperature sensor. Explanatory drawing of the laser welding method of an electrode wire and a signal wire | line in Example 2. FIG. The longitudinal cross-sectional view of the temperature sensor in a prior art example. (A) It is sectional drawing of an electrode wire and a signal wire | line in a prior art example, Comprising: CC sectional view taken on the line of (C), (B) Side surface explanatory drawing of the front-end | tip part of a temperature sensor. Explanatory drawing of the laser welding method of an electrode wire and a signal wire | line in a prior art example.

In the first and second aspects of the invention, the temperature sensor is used, for example, for measuring the temperature of an exhaust system of an internal combustion engine, etc., and is used by being inserted into an exhaust pipe or the like.
And in this application, the side which inserts the said temperature sensor in an exhaust pipe etc., ie, the side in which the temperature sensing element was arrange | positioned, is demonstrated as a front end side, and the other side is demonstrated as a rear end side.
Moreover, the said temperature sensitive element can be comprised by the thermistor element from which an electrical resistance value changes with temperature, for example.

Further, the pair of straight lines intersect at an angle of 15 to 75 ° to each other (claim 1, claim 8).
Therefore , laser irradiation can be easily performed on the overlapping portion from an oblique direction having a sufficient angle with respect to the contact surface between the electrode line and the signal line. Energy can be applied. Thereby, it is possible to perform sufficient welding while preventing the aggression, peeling, and sputtering, and the bonding strength between the electrode line and the signal line can be improved.
In addition, since the distance between the electrode line and the signal line from the laser light source can be sufficiently changed, the distance from the laser focal point can be changed between the electrode line and the signal line. Therefore, even when the electrode line and the signal line are made of different materials and have different melting points, variation in melting caused by the difference in melting point can be sufficiently suppressed.

When the angle formed by the pair of straight lines is less than 15 °, the laser energy is applied to a sufficient area in the electrode lines and the signal lines when the overlap of the electrode lines and the signal lines is irradiated with the laser. May become difficult. As a result, there is a risk of occurrence of aggression, peeling, sputtering, and the like, and it may be difficult to improve the welding strength. In addition, when the electrode line and the signal line are made of different materials and have different melting points, it may be difficult to sufficiently suppress the melting variation due to the difference in melting point.
On the other hand, when the angle formed by the pair of straight lines exceeds 75 °, the laser energy applied to the electrode line and the laser applied to the signal line when the overlapping portion of the electrode line and the signal line is irradiated with laser. There is a possibility that the difference between the energy and the energy becomes too large. As a result, it may be difficult to perform welding with sufficient welding strength while preventing the electrode wire and the signal line from aggravating, peeling, and sputtering.

It is preferable that the diameter of the electrode wire is smaller than the diameter of the signal wire (claims 2 and 10).
Further, the electrode line and the signal line preferably have a melting point difference of 200 ° C. or more (claims 3 and 11 ).
In this case, the effect of suppressing the variation in melting by sufficiently changing the distance between the electrode line and the signal line from the laser light source and changing the distance from the laser focus between the electrode line and the signal line is sufficiently exhibited. be able to. That is, when the melting point difference between the electrode line and the signal line is 200 ° C. or more, in the arrangement of the electrode line and the signal line as in the conventional temperature sensor described above, the energy of the laser applied to the electrode line and the signal line is reduced. Since it is difficult to make a difference, there is a risk that variations in melting occur between the two. As a result, it may be difficult to obtain sufficient bonding strength. Therefore, in particular, in a configuration in which the melting point difference between the electrode line and the signal line is as large as 200 ° C. or more, by applying the present invention, it is possible to suppress the melting variation and ensure the bonding strength between the electrode line and the signal line. Can do.

The electrode wire is preferably made of platinum or an alloy thereof, and the signal wire is preferably made of stainless steel or a nickel-based alloy (claims 4 and 12 ).
In this case, it is possible to prevent the electrode wire from being oxidized during the firing of the temperature sensitive element and to sufficiently ensure the heat resistance of the signal wire in the use environment. And by setting it as the above material structures, since the melting | fusing point difference of an electrode wire and a signal wire becomes large, the effect by having applied this invention can fully be exhibited.

Moreover, it is preferable that the said temperature sensitive element is arrange | positioned between the said pair of electrode wire (Claim 5, Claim 13 ).
In this case, the temperature sensing element can be miniaturized and the responsiveness of the temperature sensor can be improved.

Further, the distance between the centers of the pair of electrode wires is minor than the distance between the centers of the pair of signal lines, and the pair of electrode wires are positioned inside of the pair of signal lines. (Claim 1 , Claim 8 ).
Therefore , the distance between the pair of electrode wires can be reduced, and accordingly, the temperature sensitive element can be reduced in size, and the responsiveness of the temperature sensor can be improved.

Moreover, it is preferable that the said temperature sensitive element is sealed with glass (Claim 6 , Claim 14 ).
In this case, deterioration of the temperature sensitive element can be suppressed, and a temperature sensor excellent in durability can be obtained.

Next, in the first invention, the pair of signal lines have a bent portion in a region between a welding region welded to the electrode wire and a holding region held by the sheath pin, and in the holding region The plane including the central axis of the pair of signal lines is preferably closer to the plane including the central axis of the pair of electrode lines than the plane including the central axis of the pair of signal lines in the welding region. 7 ).
In this case, the electrode line can be arranged at a position close to a plane including the center axis of the sheath pin. Thereby, the center of the temperature sensing element connected to the electrode wire can be brought closer to the center axis of the sheath pin, and the cover covering the temperature sensing element can be downsized. As a result, the responsiveness of the temperature sensor can be improved.

In the second invention, the pair of signal lines are provided with a bent portion in a region between a welding region welded to the electrode wire and a holding region held by the sheath pin, and the pair of signal wires in the holding region The signal line is arranged such that a plane including the central axis of the signal line is closer to a plane including the central axis of the pair of electrode lines than a plane including the central axis of the pair of signal lines in the welding region. It is preferable to weld the electrode wire (claim 15 ).
In this case, a temperature sensor with excellent responsiveness can be manufactured.

Further, when irradiating the laser, it is preferable to bring the focal point of the laser close to the electrode line and the signal line having the higher melting point.
In this case, the electrode line and the signal line can be melted in a well-balanced manner, and welding can be performed with sufficient strength while preventing the escaping, peeling, and sputtering.

Example 1
A temperature sensor according to an embodiment of the present invention will be described with reference to FIGS.
As shown in FIGS. 1 to 3, the temperature sensor 1 of this example is welded to a temperature sensing element 2 whose electrical characteristics change depending on temperature, and a pair of substantially circular electrode wires 3 of the temperature sensing element 2. A pair of signal wires 4 having a substantially circular cross section are housed in a state in which the signal wires 4 are exposed on the tip side.
As shown in FIG. 1 (A), in a cross section orthogonal to the axial direction, a straight line M1 connecting one electrode line 3 and the signal line 4 welded to each other at the center, and the other electrode line 3 welded to each other. And the straight line M2 connecting the signal line 4 at the respective centers are not parallel to each other.

Further, as shown in FIG. 5, the pair of straight lines M1 and M2 intersect each other with an angle θ of 15 to 75 °.
The electrode wire 3 is made of platinum or an alloy thereof, the signal wire 4 is made of stainless steel or a nickel-based alloy, and both have a melting point difference of 200 ° C. or more. More specifically, in this example, the electrode wire 3 is made of Pt-10Ir (a platinum alloy containing 10% by weight of iridium), and the signal wire 4 is made of SUS310S.

The temperature sensing element 2 is a thermistor element whose electrical resistance value changes with temperature. As shown in FIG. 2, the temperature sensitive element 2 is disposed between the pair of electrode wires 3.
Further, as shown in FIG. 1A, the distance between the centers of the pair of electrode lines 3 is smaller than the distance between the centers of the pair of signal lines 4.
Further, as shown in FIG. 1B, the temperature sensitive element 2 is sealed with glass 11.

Further, the pair of signal lines 4 has a bent portion 43 in a region between a welding region 41 welded to the electrode wire 3 and a holding region 42 held by the sheath pin 5. The plane including the central axis of the pair of signal lines 4 in the holding area 42 is closer to the plane P including the central axis of the pair of electrode lines 3 than the plane including the central axis of the pair of signal lines 4 in the welding area 41.
The welding region 41 is formed in the overlapping portion 14 of the electrode line 3 and the signal line 4, and welding is performed at the two points, and 2 between the pair of the electrode line 3 and the signal line 4. Two welds 141 are formed.

  As shown in FIG. 3, the sheath pin 5 is made of stainless steel covering the two signal lines 4, an insulating part 51 made of insulating powder such as magnesia disposed around the signal line 4, and an outer periphery of the insulating part 51. And an outer tube portion 52 made of A rib 12 that holds the sheath pin 5 is fixed to the outer periphery of the outer tube portion 52. The rear end portion of the rib 12 protects the sheath pin 5 and a lead (not shown) connected to the rear end portion. A protective tube 13 is fixed.

A cover 15 is fitted and welded to the outer periphery of the tip of the sheath pin 5.
As shown in FIG. 3, the cover 15 includes a large diameter portion 151 fitted into the sheath pin 5 and a small diameter portion 152 disposed on the outer periphery of the temperature sensitive element 2. And the front-end | tip part of the small diameter part 152 is obstruct | occluded by the substantially hemispherical shape.

In manufacturing the temperature sensor 1 of this example, the pair of electrode wires 3 and the pair of signal wires 4 are respectively laser-welded as follows.
That is, first, as shown in FIGS. 4A and 4B, in a cross section orthogonal to the axial direction, a straight line M1 that connects one electrode line 3 and the signal line 4 that are welded to each other at their respective centers, The electrode line 3 and the signal line 4 are arranged in contact with each other so that the straight line M2 connecting the other electrode line 3 to be welded and the signal line at each center is not parallel to each other.
In this state, the laser L is irradiated to the vicinity of the contact portion between the electrode line 3 and the signal line 4 from a direction parallel to a straight line connecting the centers of the pair of signal lines 4. Thereby, the electrode line 3 and the signal line 4 are welded.
In this example, the laser L is irradiated in the horizontal direction. Accordingly, the straight line connecting the centers of the pair of signal lines 4 is directed in the horizontal direction.

Here, in order to perform laser welding of the pair of electrode wires 3 and the pair of signal wires 4, respectively, the following operation is performed. First, as shown in FIG. 4A, laser welding is performed in a state where one electrode line 3 and the signal line 4 are arranged on the light source side of the laser L. Thereafter, as shown in FIG. 4B, the temperature sensor 1 is inverted 180 ° around its axis and aligned, and the other electrode line 3 and signal line 4 are arranged on the light source side of the laser L. . In this state, the overlapping portion 14 of the other electrode line 3 and the signal line 4 is again irradiated with the laser L from the same light source and welded.
Laser welding is performed at two locations in the longitudinal direction of the electrode wire 3 and the signal wire 4. As a result, as shown in FIG. 1B, two welds 141 are formed in the longitudinal direction.

Further, as shown in FIG. 4, when irradiating the laser L, the focal point F of the laser L is brought closer to the higher melting point of the electrode line 3 and the signal line 4. In this example, since the electrode line 3 has a higher melting point than the signal line 4, the focal point F is closer to the electrode line 3. More specifically, the position E1 at which the laser L is applied to the electrode line 3 is closer to the focal point F than the position E2 at which the laser L is applied to the signal line.
In this example, the focal point F is arranged on the side farther from the light source than the positions E1 and E2.

  In addition, the laser welding in this example can be performed using a generally well-known ordinary laser welding method. In other words, the laser oscillated in the oscillator is condensed using a lens, and a high energy is applied by irradiating the vicinity of the focal point to the welded portion, so that the electrode wire 3 and the signal wire 4 are melted and then re-applied. Solidify. Thereby, the electrode line 3 and the signal line 4 are joined.

Next, the function and effect of this example will be described.
In the temperature sensor 1 of this example, in a cross section orthogonal to the axial direction, a straight line M1 that connects one electrode line 3 and the signal line 4 that are welded to each other at each center, and the other electrode line 3 that is welded to each other. And the straight line M2 connecting the signal line 4 at the respective centers are not parallel to each other. Therefore, as shown in FIG. 4, when welding the overlapping portions 14 of the two sets of electrode lines 3 and the signal lines 4, the laser L is applied to the overlapping portion 14 of the one electrode line 3 and the signal line 4. It becomes easy to irradiate the other electrode line 3 and the overlapping portion 14 of the signal line 4 from an oblique direction.

  That is, as shown in FIG. 4 (A), after laser irradiation is performed on the overlapping portion 14 of one electrode line 3 and the signal line 4 from an oblique direction, the temperature sensor 1 is changed as shown in FIG. 4 (B). By reversing (rotating 180 °), the overlapping portion 14 of the other electrode line 3 and the signal line 4 can be similarly irradiated with laser from an oblique direction.

  Further, as described above, since the laser irradiation can be easily performed from the oblique direction to the overlapping portion 14 of the electrode line 3 and the signal line 4, the electrode line 3 and the signal line 4 are not locally but rather large. The energy of the laser 3 can be applied to the region. As a result, welding can be performed while preventing the electrode line 3 and the signal line 4 from being exposed, peeled off or sputtered. As a result, it is possible to prevent the bonding strength between the electrode line 3 and the signal line 4 from being lowered.

  In addition, the laser irradiation from the oblique direction to the overlapping portion 14 of the electrode line 3 and the signal line 4 can be easily performed, which means that the distance from the light source of the laser L between the electrode line 3 and the signal line 4 can be easily achieved. It can be changed. Therefore, the distance from the focal point F of the laser L can be changed between the electrode line 3 and the signal line 4. Therefore, by bringing the focal point F close to the electrode line 3 having a higher melting point, it is possible to suppress melting variations caused by the melting point difference between the electrode line 3 and the signal line 4. As a result, the joint strength of the welded portion can be improved.

Further, as shown in FIG. 5, the pair of straight lines M1 and M2 intersect each other with an angle θ of 15 to 75 °. Therefore, since the laser irradiation can be easily performed on the overlapping portion from an oblique direction having a sufficient angle with respect to the contact surface between the electrode line 3 and the signal line 4, the electrode line 3 and the signal line 4 are sufficiently large. The energy of the laser L can be applied to the region. Thereby, it is possible to perform sufficient welding while preventing aggression, peeling, and sputtering, and the bonding strength between the electrode wire 3 and the signal wire 4 can be improved.
Further, since the distance between the electrode line 3 and the signal line 4 from the light source of the laser L can be sufficiently changed, the distance from the focal point F of the laser L between the electrode line 3 and the signal line 4 can be changed. it can. Therefore, even when the electrode line 3 and the signal line 4 are made of different materials and have different melting points, it is possible to sufficiently suppress the melting variation due to the melting point difference.

  The electrode line 3 and the signal line 4 have a melting point difference of 200 ° C. or more. Therefore, the effect of suppressing the variation in melting by changing the distance from the light source of the laser L between the electrode line 3 and the signal line 4 and changing the distance from the focal point of the laser between the electrode line 3 and the signal line 4 is sufficiently obtained. It can be demonstrated.

  The electrode wire 3 is made of a platinum alloy, and the signal wire 4 is made of stainless steel. Therefore, it is possible to prevent the electrode wire 3 from being oxidized during the firing of the temperature sensitive element 2 and to sufficiently ensure the heat resistance of the signal wire 4 in the use environment. And by setting it as the above material structures, since the melting | fusing point difference of the electrode wire 3 and the signal wire | line 4 becomes large, the effect by having applied this invention can fully be exhibited.

Moreover, since the temperature sensitive element 2 is disposed between the pair of electrode wires 3, the temperature sensitive element 2 can be reduced in size, and the responsiveness of the temperature sensor 1 can be improved.
Further, the distance between the centers of the pair of electrode lines 3 is smaller than the distance between the centers of the pair of signal lines 4. Thereby, the space | interval between a pair of electrode wire 3 can be made small, and in connection with this, size reduction of the temperature sensing element 2 can be achieved and the responsiveness of the temperature sensor 1 can be improved.
The temperature sensitive element 2 is sealed with glass 11. Thereby, deterioration of the temperature sensing element 2 can be suppressed and the temperature sensor 1 excellent in durability can be obtained.

  The pair of signal lines 4 have a bent portion 43, and the plane including the central axis of the pair of signal lines 4 in the holding region 42 is more paired than the plane including the central axis of the pair of signal lines 4 in the welding region 41. It is close to the plane P including the central axis of the electrode line 3. Therefore, the electrode line 3 can be disposed at a position close to a plane including the central axis of the sheath pin 5. Thereby, the center of the temperature sensing element 2 connected to the electrode wire 3 can be brought closer to the center axis of the sheath pin 5, and the cover 15 covering the temperature sensing element 2 can be downsized. As a result, the responsiveness of the temperature sensor 1 can be improved.

  As described above, according to this example, it is possible to provide a temperature sensor excellent in bonding reliability between an electrode line and a signal line and a manufacturing method thereof.

(Example 2)
In this example, as shown in FIGS. 6 and 7, the distance between the centers of the pair of electrode lines 3 is larger than the distance between the centers of the pair of signal lines 4.
In this case, as shown in FIG. 7, when performing laser welding, the focal point F is disposed in front of the overlapping portion 14 of the electrode line 3 and the signal line 4, and the electrode line 3 is located above the signal line 4. It should be close to the focal point F. That is, the position E1 at which the laser L is applied to the electrode line 3 is closer to the focal point F than the position E2 at which the laser L is applied to the signal line 4.
Others have the same configuration as that of the first embodiment and have the same effects.

(Experimental example 1)
In this example, as shown in Table 1, a straight line M1 that connects one electrode line 3 and the signal line 4 welded to each other at each center, and the other electrode line 3 and the signal line 4 that are welded to each other are connected to each other. This is an example in which the influence on the bonding reliability by the angle θ (FIG. 5) formed by the straight line M2 connected at the center of the wire is investigated.

That is, the electrode wire 3 and the signal wire 4 were laser welded in seven states in which the angle θ shown in FIG. 5 was changed between 0 and 90 °. Here, laser welding was performed in the same manner as in Example 1 except for the angle θ.
Various conditions such as the energy of the laser L were the same at all levels. Ten samples were tested for each level.

The bonding reliability was evaluated in terms of aggression, peeling, spatter generation, and melting variation. Regarding the melting variation, when the mutual melting ratio of the electrode wire 3 and the signal wire 4 was within 35 to 65%, it was determined as a good product.
In addition, among 10 samples at each level, “◯” when there are 10 non-defective products for each evaluation item, “△” when 1 to 5 are defective, and when 6 or more are defective. “×”.
And, the level where all the above four evaluation items were “○” was passed “○”, the level without “×” was semi-passed “△”, and the level with “×” was rejected “×”. .

  As can be seen from Table 1, θ = 0 °, that is, the conventional temperature sensor is unacceptable, but when the straight line M1 and the straight line M2 are non-parallel, at least a semi-acceptable evaluation can be obtained. Furthermore, when θ was 15 to 75 °, all samples were non-defective in all items, and excellent bonding reliability could be secured.

(Experimental example 2)
In this example, as shown in Table 2, the materials of the electrode line 3 and the signal line 4 are variously changed, and the influence of the melting point difference between the electrode line 3 and the signal line 4 on the bonding reliability is examined.
In this example, the angle θ formed by the straight line M1 and the straight line M2 is 30 °. Other configurations and welding methods are the same as those in the first embodiment.
The evaluation method is the same as in Experimental Example 1.

The experimental results are shown in Table 2. In Table 2, “Inco 600” means Inconel 600 (registered trademark of Inconel). The “melting point difference” means a difference between the melting point of the electrode wire and the melting point of the signal line, that is, “melting point of the electrode wire” − “melting point of the signal line”.
“Pt-10Ir” means a platinum alloy containing 10% by weight of iridium, and “Pt-20Ir” and “Pt-30Ir” also conform to this. 100 Pt means pure platinum.

From Table 2, it can be seen that if the difference in melting point is 135 ° C. or higher, a certain degree of bonding reliability is obtained, and if the difference in melting point is 200 ° C. or higher, the bonding reliability can be sufficiently satisfied.
It can also be seen that when the melting point difference is as small as 67 ° C., the variation in melting between the electrode wire and the signal wire increases, and the bonding reliability decreases.

DESCRIPTION OF SYMBOLS 1 Temperature sensor 2 Temperature sensing element 3 Electrode wire 4 Signal wire 5 Seaspin

Claims (15)

A temperature sensitive element whose electrical characteristics change according to temperature, and a pair of substantially circular signal wires welded to a pair of substantially circular electrode wires of the temperature sensitive element, respectively, in a state of being exposed at the distal end side A temperature sensor comprising:
In the cross section orthogonal to the axial direction, a straight line connecting the one electrode line and the signal line welded to each other at each center, and the other electrode line and the signal line welded to each other at each center. The connecting straight lines intersect each other non-parallel at an angle of 15 to 75 ° ,
A temperature sensor, wherein a distance between centers of the pair of electrode lines is smaller than a distance between centers of the pair of signal lines, and the pair of electrode lines is located inside the pair of signal lines . 2. The temperature sensor according to claim 1, wherein the diameter of the electrode wire is smaller than the diameter of the signal wire .   3. The temperature sensor according to claim 1, wherein the electrode line and the signal line have a melting point difference of 200 ° C. or more.   4. The temperature sensor according to claim 1, wherein the electrode wire is made of platinum or an alloy thereof, and the signal wire is made of stainless steel or a nickel-based alloy.   5. The temperature sensor according to claim 1, wherein the temperature sensing element is disposed between the pair of electrode wires. In any one of claims 1 to 5, wherein temperature sensitive device is a temperature sensor, characterized in that are sealed with glass. The pair of signal lines according to any one of claims 1 to 6 , wherein the pair of signal lines have a bent portion in a region between a welding region welded to the electrode wire and a holding region held by the sheath pin, The plane including the central axis of the pair of signal lines in the holding region is closer to the plane including the central axis of the pair of electrode lines than the plane including the central axis of the pair of signal lines in the welding region. Temperature sensor. A temperature sensitive element whose electrical characteristics change according to temperature, and a pair of substantially circular signal wires welded to a pair of substantially circular electrode wires of the temperature sensitive element, respectively, in a state of being exposed at the distal end side A method of manufacturing a temperature sensor comprising:
The center-to-center distance between the pair of electrode lines is smaller than the center-to-center distance between the pair of signal lines, and the pair of electrode lines are positioned inside the pair of signal lines,
In a cross section orthogonal to the axial direction, a straight line connecting one electrode line and the signal line welded to each other at each center, and the other electrode line and the signal line welded to each other at each center. With the electrode lines and the signal lines in contact with each other so that the connecting straight lines intersect each other non-parallel at an angle of 15 to 75 ° ,
Welding the electrode line and the signal line by irradiating a laser near a contact portion between the electrode line and the signal line from a direction parallel to a straight line connecting the centers of the pair of signal lines. A method for manufacturing a temperature sensor. 9. The method of manufacturing a temperature sensor according to claim 8, wherein, when irradiating the laser, the focal point of the laser is brought closer to a higher melting point of the electrode line and the signal line. According to claim 8 or 9, the diameter of the electrode wire manufacturing method of the temperature sensor, characterized in that the diameter is smaller than the diameter of the signal line. According to any one of claims 8-10, and the electrode lines and the signal lines, the manufacturing method of the temperature sensor characterized by having a melting point difference of over 200 ° C.. The method of manufacturing a temperature sensor according to any one of claims 8 to 11 , wherein the electrode wire is made of platinum or an alloy thereof, and the signal wire is made of stainless steel or a nickel-based alloy. The method of manufacturing a temperature sensor according to any one of claims 8 to 12 , wherein the temperature sensitive element is disposed between the pair of electrode wires. According to any one of claims 8 to 13, said temperature sensitive element, method for producing a temperature sensor, characterized in that are sealed with glass. According to any one of claims 8 to 14, the pair of signal lines, the bent portion is provided in the region between the holding region which is held in the weld region and the sheath pin which is welded to the electrode line, the holding The plane including the central axis of the pair of signal lines in the region is closer to the plane including the central axis of the pair of electrode lines than the plane including the central axis of the pair of signal lines in the welding region. A method of manufacturing a temperature sensor, wherein the signal line is welded to the electrode line.

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