JPH10122977A - Temperature sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably mount a lead wire in the axial direction of a sensor body and improve the thermal responsiveness and heat resistance by connecting the lead wires to meal films on the flat surfaces of projection parts protruded from both end surfaces of a cylindrical base body part 1a. SOLUTION: A ceramic base 1 has a structure in which square pole-like projection parts 1b are axially protruded from both end surface of a base body part 1a and integrally formed thereto. A thermosensitive metal film 2 is formed on the whole surface of the base body 1. The thermosensitive metal film 2 is formed of a material such as Pt, Ni, Cu, Fr or their alloys, and has a characteristic of changing the resistance value depending on temperature. To the thermosensitive metal film 2, a trimming circuit groove 3 is spirally formed to form a resistance circuit. A lead wire 4 is connected to one flat surface of side surfaces (side column surfaces of square pole) of the projection part 1b by means of electric welding, laser spot welding or the like. Finally, the whole body is coated with a ceramic coating agent 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature sensor, and more particularly to a temperature sensor for measuring an exhaust gas temperature of an automobile.

[0002]

2. Description of the Related Art As one of conventional temperature sensors, there is a so-called axial lead type temperature sensor. That is, a metal film such as Pt, Ni, Fe, Cu or an alloy thereof is deposited on a cylindrical ceramic substrate by a technique such as sputtering, vapor deposition, plating, or the like.
A resistance circuit is formed in a spiral shape by laser light or the like. Since such an axial type temperature sensor has a structure very similar to a metal film resistor, it has a feature that it can be manufactured at extremely low cost by the same method and equipment as the metal film resistor.

FIG. 6 is a view showing the appearance of an axial lead type temperature sensor. To manufacture such a temperature sensor, first, a temperature-sensitive metal film 52 is deposited on a ceramic substrate 51, and a trimming circuit groove 52a is formed by a laser beam or the like to form a sensor body 50. Next, the sensor body 5
Metal caps (usually made of SUS) 53 are attached by caulking to both ends of the “0” to mechanically and electrically connect the temperature-sensitive metal film 52 and the metal cap 53. Then, FIG.
The lead wire 5 held by the chuck 55 as shown in FIG.
4 (Material is copper, nickel, SUS, etc.) with metal cap 5
In the state of being pressed against the metal cap 3, the voltage of the welding power source 57 is applied between the electrode 56 in contact with the metal cap 53 and the chuck 55 to perform electric welding. Thereby, the tip of the lead wire 54 is melted and welded to the metal cap 53.

However, according to the above manufacturing method,
Since the sensor body 50 and the metal cap 53 are joined by caulking, when the sensor body 50 is used at an ambient temperature exceeding 300 ° C., the caulked portion is loosened due to a difference in thermal expansion coefficient between the ceramic base 51 and the metal cap 53. Connection failure occurs. Therefore, it cannot be practically used as a temperature sensor for measuring a temperature of 300 ° C. to 1000 ° C. Also,
In order to provide a temperature sensor having excellent thermal responsiveness, it is necessary to reduce the size. However, it is extremely difficult to attach the metal cap 53 to the ceramic base 51 having a diameter of 1.0 mm or less. Further, the heat capacity of the metal cap 53 also becomes a factor of deteriorating the thermal response.

Therefore, it is conceivable to manufacture a temperature sensor without using the metal cap 53. For example, a method is conceivable in which a thick metal film having good adhesion is formed (for example, 2 to 10 μm), and the lead wire 54 is directly joined to this portion as shown in FIG. However, in this case, since the lead wire 54 is strongly pressed against the metal film 58 formed on the end face of the sensor main body 50, the metal film 58 may be broken before welding. Further, as shown in (b), the tip of the lead wire 54, which should originally melt during welding, does not melt, and the metal film 58 around the portion pressed by the lead wire 54 is burned by a large current of welding. In some cases, it will be burned out, making connection impossible.

Therefore, as shown in FIG.
A method is conceivable in which the lead wire 54 is brought into contact with the end face 0 in parallel to perform welding. That is, a method in which a tip of the lead wire 54 is pressed by the pair of electrodes 56 and a current flows from the welding power source 57. According to this, the metal film 58 near the tip of the lead wire 54 is melted moderately, and an appropriate bonding state is obtained. However, the temperature sensor manufactured in this manner is not an axial lead type as shown in FIG. 10, so that the temperature sensor becomes longer in a direction perpendicular to the axial direction. Therefore, as shown in FIG.
When the sensor body 5 is used,
Since it is determined by the length in the axial direction of 0, it is necessary to increase the inner diameter. As a result, the size of the sheath tube 59 increases, which causes a decrease in thermal responsiveness and an increase in cost. This problem can be avoided by bending the lead wire 54 at a right angle as shown in FIG.
Another problem is that the wire is easily broken at the bent portion, and the strength of the lead wire 54 is deteriorated.

Therefore, as shown in FIG. 13, a method of welding the lead wire 54 not to the end face of the sensor body 50 but to the end of the cylindrical face is considered. However, in this case, as shown in FIG. 14, the connection between the sensor main body 50 and the lead wire 54 is made by joining the outer peripheral surfaces of two types of large and small cylindrical members. Therefore, there is a problem that the contact area is small, it is difficult to obtain a sufficient bonding strength, and the lead wire 54 is easily dropped.

As described above, the conventional temperature sensor provided with the metal cap 53 has a problem that a connection failure easily occurs at a high temperature and poor thermal response. Further, if an attempt is made to eliminate the metal cap in order to solve this problem, the joining of the lead wire 54 and the sensor main body 50 becomes difficult, or the joining strength or the lead wire 54 near the joining portion becomes difficult.
However, there was a problem that the mechanical strength became weak.

In view of the above-mentioned conventional problems, the present invention provides a temperature sensor excellent in thermal responsiveness and heat resistance in which a lead wire is stably mounted in an axial direction of a sensor body. Aim.

[0010]

The temperature sensor according to the present invention comprises:
A columnar base, and a base provided with a projection formed in both ends of the base in the axial direction and having a plane having a plane parallel to the axial direction on the surface, and provided on the surface of the base, A metal film that forms a resistance circuit whose resistance value changes according to temperature, a metal film provided on the surface of the protrusion,
A lead wire joined to the metal film on the flat surface of the projection and extending in the axial direction. In the temperature sensor configured as described above, since the lead wire is bonded to the metal film formed on a plane parallel to the axial direction of the protrusion, the bonding area increases, and the bonding strength of the lead wire increases. improves. In addition, because it does not use a metal cap, there is no loose connection even when used at high temperatures.
High connection reliability is obtained, and excellent thermal responsiveness is obtained due to small heat capacity.

In the above-mentioned temperature sensor, the projection may have a polygonal column shape whose height is in the axial direction. With this configuration, as shown in FIG. 4, for example, when the temperature sensor is transported using the work transport tray 61 having the groove 61a having the width W corresponding to the axial length of the trunk 1a, the trunk 1a The lower half is the groove 61a
In addition, the movement in the axial direction is restricted, and the polygonal columnar projections 1b ride on the banks of the grooves 61a to support the whole, so that they roll in the transport direction as compared with the case where the projections 1b are cylindrical. Is suppressed. Therefore, the stability of the sensor body at the time of joining the lead wires is improved, and the joining operation can be performed easily and reliably.

In the above-described temperature sensor, a metal film may be formed on the entire surface of the base to form the same metal film on each of the base portion and the protrusion. In this case, a necessary metal film is formed on the entire surface of the base by one film formation, so that the temperature sensor can be manufactured with a minimum number of manufacturing steps.

Further, a metal film may be provided on the surface of the projection, and a temperature-sensitive metal film may be further provided on the entire surface of the base including the portion. In this case, since the metal film of the protrusion is formed to have a double thickness, the joining workability and joining strength of the lead wire are further improved.

Further, a structure may be adopted in which a temperature-sensitive metal film is provided on the entire surface of the base, and a metal film is further provided on the protrusion. Also in this case, since the metal film of the protrusion is formed to have a double thickness, the joining workability and joining strength of the lead wire are further improved.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION

<< Embodiment 1 >> FIG. 1 is a diagram showing a temperature sensor according to a first embodiment of the present invention in the order of manufacturing steps ((a) to (e)). First, as shown in (a), a ceramic substrate 1 made of alumina, zirconia, or the like is formed by a molding method such as pressing or extrusion. Ceramic substrate 1
Has a structure in which quadrangular prism-shaped protrusions 1b are formed integrally from both end surfaces of a columnar base 1a so as to protrude in the axial direction. As the ceramic substrate 1, a high-purity product of 96% or more is used so that impurities at a high temperature do not affect the characteristics of the temperature-sensitive metal film.

Next, as shown in FIG. 1B, a temperature-sensitive metal film 2 is formed on the entire surface of the ceramic substrate 1 by a technique such as electroless plating, sputtering, or vapor deposition. The temperature-sensitive metal film 2 is P
t, Ni, Cu, Fe or an alloy thereof as a material,
It has the characteristic that the resistance value changes depending on the temperature. next,
As shown in (c), a trimming circuit groove 3 is formed in a spiral shape by laser light on the temperature-sensitive metal film 2 on the surface of the base portion 1a of the ceramic base 1, thereby forming a spiral resistance circuit. . Next, as shown in (d), the lead wire 4 is joined on one plane of the side surface (side pillar surface of the quadrangular prism) of the protrusion 1b by a method such as electric welding or laser spot welding. Finally, as shown in (e), the whole is coated with a ceramic coating agent 5. This is performed by a technique such as dip coating on ceramic paste or ceramic sputtering.

In bonding the lead wire 4 in the above (d), equipment as shown in FIG. 4 is used. Ceramic substrate 1
In order to form a resistance circuit in a spiral shape, the basic portion 1a must necessarily have a columnar shape, and therefore, when placed on a flat surface, it easily rolls like a roller.
Therefore, the lead wire 4 is moved in a certain position and direction in a stable state.
Although it was originally difficult to connect the main unit 1a to the work transfer tray 61 formed with a groove 61a having a width W slightly larger than the axial length of the main unit 1a.
The movement of a in the axial direction is restricted, and the projection 1b is a quadrangular prism, so that it does not easily roll naturally in the transport direction. Therefore, the lead wire 4 can be easily and reliably joined in a state where the ceramic base 1 is stable.

FIGS. 5A and 5B are views showing the details of the joining state between the lead wire 4 and the projection 1b. FIG. 5A is a plan view, FIG. 5B is a front view showing the welding electrode 56 together, and FIG. () Is a cross-sectional view of the joint. Since the surface of the protruding portion 1b for joining the lead wire 4 is flat, the joint area between the molten region A by welding and the lead wire 4 is smaller than that in the case where the lead wire is joined on a cylindrical surface as in the related art. The bonding strength increases accordingly. The temperature sensor manufactured in this way can stably and firmly join the lead wires, has excellent connection reliability, and does not use a metal cap unlike the conventional one, so it has heat resistance and heat resistance. Excellent responsiveness.

Embodiment 2 FIG. 2 shows a temperature sensor according to a second embodiment of the present invention in the order of manufacturing steps ((a) to (d)).
It is a figure shown to (f)). First, as shown in (a),
Ceramic substrate 1 made of alumina, zirconia, etc.
Is formed by a molding method such as pressing and extrusion. The ceramic base 1 has a structure in which quadrangular prism-shaped protrusions 1b are integrally formed by projecting in the axial direction from both end surfaces of a columnar base 1a. As the ceramic substrate 1, a high-purity product of 96% or more is used so that impurities at a high temperature do not affect the characteristics of the temperature-sensitive metal film. Next, as shown in (b), the base metal film 6 is selectively formed only on the protrusions 1b by a technique such as sputtering, thick film dipping, or plating. This is lead wire 4
The metal film thickness of the portion connecting
This is for improving the joining workability and joining strength of the lead wire 4. As the material of the base metal film 6, the ceramic base 1
With good adhesion and good heat resistance, for example,
Tantalum, chrome, etc. are suitable.

Next, as shown in FIG. 1C, a temperature-sensitive metal film 2 is formed on the entire surface of the ceramic substrate 1 by a technique such as electroless plating, sputtering, or vapor deposition. The temperature-sensitive metal film 2 is P
t, Ni, Cu, Fe or an alloy thereof as a material,
It has the characteristic that the resistance value changes depending on the temperature. next,
As shown in (d), a trimming circuit groove 3 is formed in a spiral shape by laser light on the temperature-sensitive metal film 2 on the surface of the base portion 1a of the ceramic base 1 to form a spiral resistance circuit. . Next, as shown in (e), the lead wire 4 is joined on one plane of the side surface (side pillar surface of the quadrangular prism) of the protrusion 1b by a method such as electric welding or laser spot welding. Finally, as shown in (f), the whole is coated with the ceramic coating agent 5. This is performed by a technique such as dip coating on ceramic paste or ceramic sputtering.

In the temperature sensor manufactured as described above, similarly to the temperature sensor of the first embodiment, the lead wire 4 can be connected stably and firmly. In addition, since the metal film of the protrusion 1b is formed to have a double thickness, bonding workability and bonding strength of the lead wire 4 are further improved. Further, since a metal cap is not used, heat resistance and thermal responsiveness are excellent. The temperature sensor manufactured as described above is 1000
At a high temperature of about 0 ° C., the underlying metal film 6
There is a concern that the metal diffuses into the inside and changes the characteristics of the temperature-sensitive metal film 2, particularly the TCR (temperature coefficient of resistance) and the resistance value. However, the base metal film 6 is deposited only on the protrusion 1 b. ,
Since it does not exist in the resistance circuit forming portion of the temperature-sensitive metal film 2,
It was confirmed that it had little effect.

Embodiment 3 FIG. 3 shows a temperature sensor according to a third embodiment of the present invention in the order of manufacturing steps ((a) to (d)).
It is a figure shown to (f)). First, as shown in (a),
Ceramic substrate 1 made of alumina, zirconia, etc.
Is formed by a molding method such as pressing and extrusion. The ceramic base 1 has a structure in which quadrangular prism-shaped protrusions 1b are formed integrally from both ends of a columnar base 1a so as to protrude in the axial direction. As the ceramic substrate 1, a high-purity product of 96% or more is used so that impurities at a high temperature do not affect the characteristics of the temperature-sensitive metal film. Next, as shown in (b), the entire surface of the ceramic substrate 1 is formed by a method such as electroless plating, sputtering, or vapor deposition.
The temperature-sensitive metal film 2 is formed. The temperature-sensitive metal film 2 is made of Pt, Ni,
The material is made of Cu, Fe, an alloy thereof, or the like, and has a characteristic that a resistance value changes depending on temperature.

Next, as shown in (c), only the protrusion 1b is selectively coated with the metal film 7 by a technique such as sputtering, thick film dipping, plating or the like. This is because the thickness of the metal at the part to which the lead wire 4 is connected is made thicker than the base part 1a, and the workability and the joining strength of the lead wire 4 are improved. As a material of the metal film 7, a material having good heat resistance, for example, tantalum, chromium, or the like is suitable. next,
As shown in (d), a trimming circuit groove 3 is formed in a spiral shape by laser light on the temperature-sensitive metal film 2 on the surface of the base portion 1a of the ceramic base 1 to form a spiral resistance circuit. . Next, as shown in (e), the lead wire 4 is joined on one plane of the side surface (side pillar surface of the quadrangular prism) of the protrusion 1b by a method such as electric welding or laser spot welding. Finally, as shown in (f), the whole is coated with the ceramic coating agent 5. This is performed by a technique such as dip coating on ceramic paste or ceramic sputtering.

In the temperature sensor manufactured as described above, similarly to the temperature sensor of the first embodiment, the lead wire 4 can be connected stably and firmly. In addition, since the metal film of the protrusion 1b is formed to have a double thickness, bonding workability and bonding strength of the lead wire 4 are further improved. Further, since a metal cap is not used, heat resistance and thermal responsiveness are excellent.

In each of the above embodiments, the shape of the projection 1b is a square pole, but this is merely an example. In addition, a polygonal pillar such as a hexagonal pillar or an octagonal pillar, or a cylinder is vertically divided. Such a semi-cylindrical shape can be applied. In short, any shape may be used as long as it has a plane portion substantially parallel to the axial direction of the temperature sensor as a bonding surface with the lead wire 4.

[0026]

The present invention configured as described above has the following effects. In the temperature sensor of the present invention, a lead wire is bonded to a metal film on a plane parallel to the axial direction on the surface of a polygonal pillar-shaped projection formed to protrude in the axial direction from both end surfaces of the columnar base. Therefore, the bonding area is large and the bonding strength is large. Therefore, the lead wire can be stably and firmly attached. In addition, since the configuration does not use a metal cap, there is no portion where the connection is loosened even when used under a high temperature, and the heat capacity is small. Therefore, it is excellent in heat resistance and heat responsiveness.

In the above-mentioned temperature sensor, if the projection is formed in a polygonal column shape having the height in the axial direction, for example, the protrusion has a groove having a width corresponding to the axial length of the main body. When transporting the temperature sensor using the work transport tray, the lower half of the main part fits into the groove to restrict axial movement, and the polygonal pillar-shaped projection rides on the bank of the groove to support the whole In addition, rolling in the transport direction is suppressed. Therefore, the stability of the sensor body at the time of joining the lead wires is improved, and the joining operation can be performed easily and reliably.

In the above-mentioned temperature sensor, when a metal film is formed on the entire surface of the base, and the respective metal films of the main part and the projection are formed as the same metal film, the film is formed once. As a result, a required metal film is formed on the entire surface of the base, so that the temperature sensor can be manufactured with a minimum number of manufacturing steps.

In the case where a metal film is provided on the surface of the protrusion and a temperature-sensitive metal film is further provided on the entire surface of the base including the portion, the metal film on the protrusion is double thickened. Since the film is formed, the joining workability and joining strength of the lead wire are further improved.

In a case where a temperature-sensitive metal film is provided on the entire surface of the substrate and a metal film is further provided on the protrusion, the metal film on the protrusion is formed to be double thick. Therefore, the joining workability and joining strength of the lead wire are further improved.

[Brief description of the drawings]

FIG. 1 shows a temperature sensor according to a first embodiment of the present invention;
It is a figure shown in the order of the manufacturing process.

FIG. 2 shows a temperature sensor according to a second embodiment of the present invention;
It is a figure shown in the order of the manufacturing process.

FIG. 3 shows a temperature sensor according to a third embodiment of the present invention;
It is a figure shown in the order of the manufacturing process.

FIG. 4 is a perspective view showing a work transfer tray common to each embodiment of the present invention.

FIG. 5 is a diagram showing a state of attachment of a lead wire in each embodiment of the present invention.

FIG. 6 is a view showing the appearance of a conventional axial lead type temperature sensor.

FIG. 7 is a diagram showing a welding process of a lead wire in a conventional temperature sensor.

FIG. 8 is a view showing a welding process of a lead wire in a conventional temperature sensor when a metal cap is not used.

FIG. 9 is a diagram showing a state where a lead wire is welded to an end face of a conventional temperature sensor.

FIG. 10 is a diagram showing a conventional temperature sensor having a lead wire attached to an end face.

11 is a diagram showing a state where the temperature sensor shown in FIG. 10 is housed in a sheath tube.

12 is a diagram showing a state where the lead wire of the temperature sensor shown in FIG. 10 is bent and housed in a sheath tube.

FIG. 13 is a diagram showing a state in which a lead wire is welded to a cylindrical surface near an end in a conventional temperature sensor.

FIG. 14 is a diagram showing a bonding state between a cylindrical surface near an end and a lead wire in a conventional temperature sensor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ceramic base 1a Main part 1b Protrusion part 2 Temperature-sensitive metal film 3 Trimming circuit groove 4 Lead wire 5 Ceramic coating agent 6 Base metal film 7 Metal film 55 Chuck 61 Work transfer tray 61a Groove A Melting area

Claims (5)

[Claims] 1. A base body comprising: a columnar base portion; and a projecting portion formed so as to protrude in the axial direction from both end surfaces of the base portion and having a flat surface parallel to the axial direction on the surface; and a surface of the base portion. A metal film that is provided on the upper surface and forms a resistance circuit whose resistance value changes according to temperature; a metal film that is provided on the surface of the protrusion; and a metal film that is bonded to the metal film on the plane of the protrusion. And a lead wire extending in the axial direction. 2. The temperature sensor according to claim 1, wherein the protrusion has a polygonal column shape with the axial direction as a height direction. 3. The method according to claim 1, wherein the metal film of the base portion and the metal film of the protrusion are the same metal film, and are formed by providing a temperature-sensitive metal film on the entire surface of the base. The temperature sensor according to claim 1. 4. The temperature sensor according to claim 1, wherein a metal film is provided on the surface of the protrusion, and a temperature-sensitive metal film is further provided on the entire surface of the base including the portion. 5. The temperature sensor according to claim 1, wherein a temperature-sensitive metal film is provided on the entire surface of the base, and a metal film is further provided on the protrusion.