JP6576876B2 - Method for manufacturing gas sensor element - Google Patents

Description

  The present invention relates to a method of manufacturing a gas sensor element used for combustion control of an internal combustion engine.

2. Description of the Related Art Conventionally, a gas sensor is known that includes a gas sensor element that is used by being attached to an exhaust pipe of an internal combustion engine such as an automobile and detects the concentration of a specific gas (for example, NOx (nitrogen oxide) or oxygen) in the exhaust gas. Yes. In such a gas sensor, the gas sensor element includes a cell having an oxygen ion conductive solid electrolyte body and a pair of electrodes disposed on the solid electrolyte body, and in this cell, the oxygen concentration in the gas to be detected is adjusted. The corresponding electromotive force is measured. In order to protect the gas sensor element from water and soot in the gas to be detected, the outer surface of the detection portion at the tip of the gas sensor element is also covered with a protective layer made of a porous layer.
This protective layer can be manufactured by immersing the gas sensor element in a slurry in which ceramic particles are dispersed and forming a slurry film at the tip portion of the gas sensor element, followed by firing (Patent Document 1).

The protective layer can be formed, for example, as shown in FIG.
First, the rear end portion of the cylindrical (cup-type) gas sensor element 50 is held by the jig 302, and the tip end portion of the gas sensor element 50 is immersed in the dip tank 300 storing the slurry to form a slurry film. Next, the jig 302 is turned upside down and moved to the firing furnace 100 so that the front end of the gas sensor element 50 faces upward and the opening at the rear end faces downward.
The firing furnace 100 includes a conveyor (an endless track transport path) 102 having an oval track, an oval guide 104 erected along the inner periphery of the conveyor 102, and a predetermined portion of the conveyor 102. And a plurality of holding units 110 that convey on the conveyor 102, and a pressing jig 220 that arranges the holding units 110 at predetermined positions on the conveyor 102.
The holding part 110 has a substantially rectangular base 112, a circular cylindrical part 114 placed on the base 112 and viewed from above, and a pin 110 p that protrudes upward from the center of the cylindrical part 114. The individual gas sensor elements 50 are installed in the holding section 110 by inserting and holding the pins 110 p in the openings of the gas sensor elements 50.

The gas sensor element 50 is sequentially supplied from the supply position P on the conveyor 102 with its own opening facing downward, and is placed on the holding part 110 (the pin 110p) disposed on the conveyor 102 at the supply position P. After the installation, the holding unit 110 is conveyed on the conveyor 102 to the inside of the furnace body 106, and the slurry film is baked. Thereafter, the gas sensor element 50 is unloaded from the firing furnace 100 system at the unloading position Q outside the furnace body 106 and moves to the next step. The empty holding unit 110 from which the gas sensor element 50 has been taken out sequentially returns to the supply position P.
Here, when the gas sensor element 50 is installed on the holding unit 110, the cylindrical portion 114 of each holding unit 110 is pressed by the pressing jig 220 so that the holding unit 110 (the pin 110p thereof) is arranged at the supply position P. Is positioned so as to contact the guide 104. This is because, when the pin 110p on the cylindrical portion 114 is displaced with respect to the supply position P, the pin 110p contacts the edge or inner surface of the gas sensor element 50 without being aligned with the opening of the gas sensor element 50. This is because the electrode 50 formed on the inner surface of the opening may be scraped off.

JP 2002-323471 A

By the way, when conveying the gas sensor element 50 to the furnace body 106 of the baking furnace 100, the conveyor 102 is preferably linear in order to accurately control the heating rate and the heating pattern. Therefore, if there is room in the gas sensor element production line, the entire conveyor 102 may be straightened and the gas sensor element 50 may be supplied from one end of the conveyor 102.
On the other hand, if there is not enough space on the production line, the conveyor 102 must be made into an oval track and connected endlessly as described above. Of these, the linear conveyance path 102L shown in FIG. It is necessary to assign to the introduction part to 106. In this case, the supply position P for supplying the gas sensor element 50 is the arcuate conveyance path 102c on the upstream side of the linear conveyance path 102L as described above.

Here, as shown in FIG. 6, the pressing jig 220 has a bifurcated portion 222 that is bifurcated (Y-shaped). And while accommodating the cylindrical part 114 in the inner surface of the branch part 222, the arcuate shape of the guide 104 so that the center line (the bisector of the opening angle of the branch part 222) LB coincides with the supply position P. The cylindrical portion 114 is pressed against the part and positioned at the supply position P.
However, as shown in FIG. 7, when the cylindrical portion 114 is pressed by the pressing jig 220, the cylindrical portion 114 is positioned while being held on the inner surface of the branch portion 222 at a position shifted from the center line LB (supply position P). In this state, the gas sensor element 50 may be installed. In this case, as described above, the gas sensor element 50 is damaged, or the electrode formed on the inner surface of the opening is scraped, so that there is a problem that productivity and yield are lowered.
This is because when the supply position P is the arcuate conveyance path 102c, the columnar part 114 is pressed against the arcuate guide 104 which is unstable compared to a straight line, and therefore the columnar part 114 is easily displaced on the guide 104. It is thought to be.

  That is, an object of the present invention is to provide a method for manufacturing a gas sensor element, in which a holding unit that holds and conveys a gas sensor element can be positioned and arranged with high accuracy at a predetermined portion on an endless track conveyance path.

The method of manufacturing a gas sensor element according to the present invention is such that a gas sensor element extending in the axial direction is supplied from a predetermined supply position above the endless track transport path, thereby being circular in top view arranged at the supply position on the endless track transport path. The gas sensor element is installed on a holding part having a column part, and the gas sensor element is conveyed by the holding part on the endless track transport path, and is disposed at a predetermined position on the endless track transport path. In the method of manufacturing a gas sensor element that performs a predetermined process on the gas sensor element, the endless track transport path connects the pair of opposing linear transport paths and the pair of facing arc-shaped transport paths endlessly, Comprising an arcuate guide along the inner circumference of the arcuate conveyance path;
The supply position is any one of the arcuate conveyance paths, the processing unit is disposed so as to include the linear conveyance path connected to the downstream of the supply position, and an engagement part is provided at the center of the column part, The gas sensor element is installed on the holding part by engaging the engaging part with one end side of the gas sensor element, the column part is in contact with the arc-shaped guide, and the outer periphery of the arc-shaped guide and the column part When the angle formed by two tangents to the outer periphery is θ, it has a bifurcated bifurcated portion, and the inner surface of the bifurcated portion is pressed with a pressing jig whose opening angle φ is smaller than θ. The column portion is pressed against the arcuate guide while accommodating the column portion, and the holding portion is arranged at the supply position.

  According to this method of manufacturing a gas sensor element, since the opening angle φ of the branching portion is less than the angle θ, the component force in the pressing direction of the pressing force of the pressing jig is relative to the component force in the vertical direction. Become bigger. For this reason, the force acting on the inner surface of the branch portion so as to deviate in the direction perpendicular to the pressing direction with respect to the supply position is reduced, while the force pressing the column portion is relatively increased. As a result, it is possible to suppress the column part, and hence the holding part from being displaced from the supply position, and to position and arrange the holding part to the supply position with high accuracy.

In the method for manufacturing a gas sensor element of the present invention, a straight portion that extends parallel to the bisector of the opening angle φ may be provided at the tip of the branch portion.
According to this method of manufacturing a gas sensor element, both straight portions serve as guides and the column portions are introduced into the inner surface of the branch portion, and the column portions are held between both straight portions, so that the column portions are provided at the supply position. On the other hand, it is possible to further suppress the positioning in a direction perpendicular to the pressing direction.

  According to the present invention, the holding unit that holds and conveys the gas sensor element can be positioned and arranged with high accuracy at a predetermined portion on the endless track conveyance path.

It is a top view explaining an example of composition of a pressing jig used for a manufacturing method of a gas sensor element concerning an embodiment of the present invention. It is a figure which shows angle (theta) which two tangents of the outer periphery of a circular arc guide, and the outer periphery of a cylindrical part make. In the manufacturing method of the gas sensor element concerning the embodiment of the present invention, it is a figure showing positioning of a holding part by a pressing jig. It is a schematic diagram which shows the pressing force applied to a cylindrical part by a pressing jig. It is a figure explaining an example of the manufacturing line containing the baking furnace of a gas sensor element. It is a top view of the baking furnace of FIG. It is a figure which shows the position shift of a holding | maintenance part when using the conventional pressing jig.

Hereinafter, with reference to FIGS. 1-4, the manufacturing method of the gas sensor element which concerns on embodiment of this invention is demonstrated. In addition, since the manufacturing method of the gas sensor element which concerns on embodiment of this invention is the same as the manufacturing method of the conventional gas sensor element except the pressing jig 20 differing, in order to demonstrate the manufacturing method of the conventional gas sensor element Reference is made to FIG. 5 and FIG. The furnace body 106 and the pin 110p shown in FIG. 5 correspond to a “processing section” and an “engaging section” in the claims, respectively.
FIG. 1 is a top view for explaining an example of the configuration of the pressing jig 20, and FIG. 2 is a diagram showing an angle θ formed by two tangents t1 and t2 between the outer periphery of the arcuate guide 104 and the outer periphery of the cylindrical portion 114.

As shown in FIG. 1, the pressing jig 20 has a bifurcated portion 22 that is bifurcated (Y-shaped). Then, the cylindrical portion 114 is pressed along the center line (the bisector of the opening angle φ of the branching portion 22) LB while accommodating the cylindrical portion 114 on the inner surface of the branching portion 22.
Further, straight portions 22s extending in parallel with the bisector LB are provided at the tips of the respective branch portions 22, and the tip sides of the straight portions 22s have chamfered portions 22e whose diameters are tapered toward the outside. Forming. Furthermore, the front end side of the chamfered portion 22e is a horizontal portion perpendicular to the bisector LB. The interval D between the straight portions 22s is slightly larger than the diameter of the cylindrical portion 114.
Here, as shown in FIG. 2, when the cylindrical portion 114 is brought into contact with the arc-shaped portion of the guide 104 (corresponding to the “arc-shaped guide” in the claims), the outer periphery of the arc-shaped guide 104 and the cylindrical portion 114. An angle formed by two tangents t1 and t2 with the outer circumference of the circle is θ. Then, the opening angle φ of the pressing jig 20 is defined to be less than θ. The opening angle φ is preferably 90 degrees or less.

Then, as shown in FIG. 3, the cylindrical portion 114 is pressed against the arcuate guide 104 and supplied so that the bisector LB coincides with the supply position P while accommodating the cylindrical portion 114 on the inner surface of the branch portion 22. Position to position P.
Here, as shown in FIG. 4, when the cylindrical portion 114 is pressed with the pressing force F by the pressing jig 20 along the bisector LB, the component forces along the branching portion 22 of the pressing force F are respectively F1. , F2. The component forces in the bisector LB direction (pressing direction) of F1 (F2) and the vertical direction thereof are Fy and Fx1, respectively.

In the present invention, the opening angle φ of the branch portion 22 is less than θ, and Fy is relatively larger than Fx1. In particular, when φ ≦ 90 degrees, Fx1 ≦ Fy. Therefore, the force Fx1 acting so that the cylindrical portion 114 is displaced in the Fx1 direction with respect to the supply position P on the inner surface of the branching portion 22 is reduced, while the force pressing the cylindrical portion 114 in the pressing direction by the force Fy is relatively large. Become. As a result, it is possible to suppress the cylindrical portion 114 and thus the holding portion 110 from being displaced with respect to the supply position P, and to position and arrange the holding portion 110 to the supply position P with high accuracy.
On the other hand, when the opening angle is larger than θ as in the conventional branch portion 222, Fx2 is relatively larger than Fy, and the cylindrical portion 114 is in the Fx1 direction with respect to the supply position P on the inner surface of the branch portion 22. Strength to sag is increased. Therefore, as shown in FIG. 7, it is considered that the cylindrical portion 114 is held and positioned on the inner surface of the branch portion 222 at a position shifted from the bisector LB that is the stable point of the original branch portion 222. .

  Further, when the straight portions 22s are provided at the tips of the respective branch portions 22, both the straight portions 22s serve as guides so that the columnar portion 114 is introduced into the inner surface of the branch portion 22, and the columnar portion 114 is between the straight portions 22s. Therefore, it is possible to further suppress the cylindrical portion 114 from being displaced in the Fx1 direction with respect to the supply position P.

The reason why the holding part 110 has the cylindrical part 114 is that the cylindrical part 114 smoothly moves toward the supply position P on the outer periphery of the arcuate guide 104 when pressing (positioning) with the pressing jig 20. This is because movement and positioning are ensured.
Further, the reason why the pin 110p is arranged at the center of the cylindrical portion 114 is that the cylindrical portion 114 moves (rotates) on the outer periphery of the arcuate guide 104 as described above, and therefore the pin 110p does not exist at the rotation center. This is because the pin 110p is displaced from the supply position P.

It goes without saying that the present invention is not limited to the above-described embodiments, and extends to various modifications and equivalents included in the spirit and scope of the present invention.
Examples of the gas sensor element 50 include a cylindrical element having an inner electrode and an outer electrode on the inner surface and the outer surface of a bottomed cylindrical solid electrolyte body as described above.
The engaging part should just be arrange | positioned in the center of the cylindrical part 114, for example, may be the concave groove which accommodates the one end side of the gas sensor element 50 instead of the pin 110p.
Further, it is only necessary that one engaging portion is disposed on the cylindrical portion 114.
Further, the shape of the holding part 110 is not limited to the above as long as it has the cylindrical part 114. For example, the base part 112 may be omitted and only the cylindrical part 114 may be provided.
In the present embodiment shown in FIG. 5, the processing section (furnace body) 106 is arranged so as to include a pair of linear conveyance paths 102L and one arcuate conveyance path 102c therebetween. The processing unit only needs to include at least one linear conveyance path 102L connected downstream of the supply position P. Two or more processing units may be arranged in the transport direction, and different processing may be performed on the gas sensor element 50 in each processing unit.

20 pressing jig 22 branching portion 22s straight portion 50 gas sensor element 102 endless track transport path (conveyor)
102c Arc-shaped conveyance path 102L Linear conveyance path 104 Arc-shaped guide 106 Processing section (furnace)
110 holding part 110p engaging part (pin)
114 Column (Cylinder)
P supply position LB bisector t1, t2 of opening angle φ Two tangents

Claims (2)

By supplying a gas sensor element extending in the axial direction from a predetermined supply position above the endless track transport path, on the holding section having a circular column portion in a top view disposed at the supply position on the endless track transport path. A gas sensor in which the gas sensor element is installed, the gas sensor element is transported by the holding unit on the endless track transport path, and a predetermined process is performed on the gas sensor element by a processing unit disposed at a predetermined position of the endless track transport path In the manufacturing method of the element,
The endless track transport path connects an endless pair of opposing linear transport paths and a pair of opposing arc transport paths, and includes an arc guide along the inner periphery of the arc transport path. ,
The supply position is any one of the arcuate conveyance paths, and the processing unit is disposed so as to include the linear conveyance path connected downstream of the supply position,
An engaging portion is provided at the center of the column portion, the engaging portion is engaged with one end side of the gas sensor element, and the gas sensor element is installed in the holding portion.
When the column part is brought into contact with the arcuate guide, and an angle formed by two tangents between the outer periphery of the arcuate guide and the outer periphery of the column part is θ,
A pressing jig having a bifurcated bifurcated portion, and an opening angle φ of the bifurcated portion being less than θ, the columnar portion being placed on the arcuate guide while accommodating the columnar portion on the inner surface of the bifurcated portion. A method of manufacturing a gas sensor element, wherein the gas sensor element is pressed and the holding portion is disposed at the supply position.   The method of manufacturing a gas sensor element according to claim 1, wherein a straight portion extending in parallel with a bisector of the opening angle φ is provided at a tip of the branch portion.

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