JP7023159B2 - Manufacturing method of sensor element, gas sensor and gas sensor - Google Patents

Description

The present invention relates to a sensor element, a gas sensor, and a method for manufacturing a gas sensor, which are suitably used for detecting the gas concentration of a specific gas contained in a combustion gas such as a combustion engine or an internal combustion engine or an exhaust gas.

Conventionally, a gas sensor provided with a sensor element for detecting the concentration of a specific component (oxygen or the like) in the exhaust gas of an internal combustion engine has been used. This sensor element includes a detection unit having a solid electrolyte body and a pair of electrodes arranged on the solid electrolyte body, and detects an electromotive force generated between both electrodes according to the oxygen concentration in the gas to be detected. ..
By the way, the sensor characteristics also slightly fluctuate due to individual differences for each sensor element. Therefore, a technique has been developed in which sensor characteristics are measured for each sensor element and the sensor information is laser-marked on a gas sensor main body (metal outer cylinder) (see Patent Document 1). Then, when the control device (controller) is connected to the gas sensor in which the sensor element is assembled, this sensor information is read and the controller is calibrated (output value correction and rank correction).

JP-A-2007-212405 (Fig. 2)

By the way, there is a desire to manage the sensor information even at the stage of the sensor element before assembling to the gas sensor, and in this case, it is necessary to directly mark the sensor element with a laser or the like.
Therefore, as shown in FIG. 4, the surface of the sensor element 1000 is scanned by a laser or the like and scraped, and a plurality of engraved lines ML are provided to form the marking portion 200. Here, since the thickness of the element is reduced by the engraved line ML, if the scanning direction of the laser (the direction in which the engraved line ML extends) is along the width direction, a stress such as bending in the axis O direction of the sensor element 1000 is applied. At that time, it was found that the engraved line ML became a notch and became the starting point of breakage, and the sensor element 1000 was broken along the line B in the width direction.
Therefore, an object of the present invention is to provide a method for manufacturing a sensor element, a gas sensor, and a gas sensor in which damage to the sensor element is suppressed when a display unit composed of a plurality of engraved lines is provided on the surface of the sensor element.

In order to solve the above problems, the sensor element of the present invention is provided with a detection unit having one or a plurality of cells having a solid electrolyte body as an element main body and a pair of electrodes arranged on the solid electrolyte body on the tip side. It is a long plate-shaped sensor element extending in the axial direction, and a display unit containing information about the sensor element is formed on the surface of the sensor element. It is characterized by being composed of a plurality of separated engraved lines.

According to this sensor element, even if a stress such as bending in the axial direction is applied to the long plate-shaped sensor element at the time of assembly or the like, the extending direction of the engraved line follows the direction in which the stress is applied, so that the engraved line is cut. It is possible to suppress the occurrence of a notch and the starting point of breakage, and prevent the sensor element from breaking. Since the sensor element is short in the width direction, it does not become excessive even if a stress that bends in the width direction is applied, and even if the engraved line is along the axis direction, it is unlikely to break.

The gas sensor of the present invention is formed by assembling the sensor element inside the main metal fitting.
According to this gas sensor, damage to the sensor element can be suppressed even when stress is applied to the sensor element during assembly.

The method for manufacturing a gas sensor of the present invention is provided with a detection unit having one or a plurality of cells having a solid electrolyte body as an element main body and a pair of electrodes arranged on the solid electrolyte body on the tip side, and has a length extending in the axial direction. A method for manufacturing a gas sensor including a plate-shaped sensor element, wherein a laser beam is scanned on the surface of the sensor element in a direction along the axial direction, and the sensor is composed of a plurality of engraved lines separated from each other. The laser engraving step of forming a display unit containing information about the element, and the sensor element inside the main metal fitting so that the display unit of the sensor element protrudes toward the front end side or the rear end side of the tubular main metal fitting. It is characterized by having an assembly process for assembling.

According to this gas sensor manufacturing method, the display unit of the sensor element protrudes to the front end side or the rear end side of the main metal fitting, so that the display unit is read with the sensor element attached to the main metal fitting to read each sensor element. Sensor information can be managed.

According to the present invention, when a display unit composed of a plurality of engraved lines is provided on the surface of the sensor element, damage to the sensor element can be suppressed.

It is an external view of the sensor element which concerns on embodiment of this invention. It is a partial cross-sectional view which shows the mode of assembling a sensor element to a main metal fitting. It is sectional drawing which follows the axial direction of the gas sensor provided with the sensor element which concerns on embodiment of this invention. It is an external view which shows the state which marked the conventional sensor element.

Hereinafter, embodiments of the present invention will be described.
FIG. 1 is an external view of the sensor element 100 according to the embodiment of the present invention, FIG. 2 is a partial cross-sectional view showing a mode in which the sensor element 100 is assembled to the main metal fitting 30, and FIG. 3 is a gas sensor (oxygen sensor) provided with the sensor element 100. FIG. 1 is a cross-sectional view taken along the axis O direction of 1.

As shown in FIG. 1, the sensor element 100 has a long plate shape extending in the O-axis direction, and has a solid electrolyte body as an element body and a pair of electrodes (not shown) arranged on the solid electrolyte body. A detection unit 100a having one or a plurality of cells is provided on the front end side, and an electrode pad 121 is provided on the main surface on the rear end side. Although a total of five electrode pads 121 are provided, two of them are displayed in FIG. 1, and the other three, which are not shown, are provided on the back surface of FIG.

A display unit 40 containing information about the sensor element 100 is formed on the surface of the sensor element 100 on the front end side of the electrode pad 121 and on the rear end side of the center of the axis O direction. The display unit 40 is composed of a plurality of engraved lines ML that are separated from each other along the axis O direction.
Examples of the display unit 40 include symbols, character strings, numbers, barcodes, and the like, which are represented by the engraved line ML. Further, examples of the formation of the engraved line ML include laser engraving and the like. Further, the information included in the display unit 40 may be information about each sensor element 100, and corresponds to, for example, the output characteristics of the sensor such as the electromotive force of each sensor element 100, the type of the sensor, and the output characteristics. Rank value can be mentioned.

For example, in the case of laser engraving, the surface of the sensor element 100 is scraped by scanning the laser beam in a predetermined scanning direction to form engraved lines ML extending in the scanning direction one by one. Next, the laser beam is similarly scanned in the scanning direction from the positions separated in the direction orthogonal to the scanning direction to sequentially form a plurality of engraved line MLs.
In the present embodiment, the extending direction of each engraved line ML (that is, the scanning direction of the laser in this example) is set to be along the axis O direction.
As a result, even if stress such as bending in the axis O direction is applied to the long plate-shaped sensor element 100 at the time of assembly or the like, the extending direction of the engraved line ML is along the direction in which the stress is applied, so that the engraved line ML is cut. It is possible to prevent the sensor element 100 from breaking by forming a notch and suppressing the starting point of breakage. Since the sensor element 100 is short in the width direction, it does not become excessive even if a stress that bends in the width direction is applied, and even if the engraved line ML is along the axis O direction, it is unlikely to break.

Here, "the engraved line ML is along the axis O direction" means that the angle θ formed by the extending direction of the engraved line ML with the axis O is less than 45 degrees, preferably θ. It is less than 30 degrees. This is because the scanning direction of the laser beam at the time of laser engraving is not always completely parallel to the axis O direction, and there are manufacturing errors, tolerances, and the like.

Next, a method for manufacturing the gas sensor 1 according to the embodiment of the present invention will be described.
First, as described above, the laser beam is scanned on the surface of the sensor element 100 in the direction along the axis O direction to form a display unit 40 composed of a plurality of engraved MLs separated from each other (laser engraving step). ..
Next, as shown in FIG. 2, the sensor element 100 is assembled inside the main metal fitting 30 so that the display portion 40 of the sensor element 100 projects toward the rear end side of the tubular main metal fitting 30, and the sensor intermediate product 1x is attached. Manufacture (assembly process).
Then, the sensor information of the sensor element 100 can be managed by reading the display unit 40 exposed on the rear end side of the main metal fitting 30 with the CCD camera 500 or the like. Further, when the controller is connected to the gas sensor 1 in which the sensor intermediate product 1x is assembled, the controller may be calibrated (output value correction or rank correction) based on the sensor information read from the display unit 4.

Next, with reference to FIG. 3, the configuration of the gas sensor 1 in which the sensor intermediate product 1x is assembled will be described.
As shown in FIG. 3, the gas sensor 1 has a sensor element 100, a main metal fitting 30, a protector 24 attached to the tip of the main metal fitting 30, and the like.

The main metal fitting 30 is made of SUS430 and has a male screw portion 31 for attaching the gas sensor to the exhaust pipe and a hexagonal portion 32 to which an attachment tool is applied at the time of attachment. Further, the main metal fitting 30 is provided with a metal fitting side step portion 33 projecting inward in the radial direction, and the metal fitting side step portion 33 supports a metal holder 34 for holding the sensor element 100. .. A ceramic holder 35, a first talc 37, and a second talc 38 are arranged in order from the tip side inside the metal holder 34.
The sensor element 100 is fixed to the metal holder 34 by compressing and filling the first talc 37 in the metal holder 34. Further, by compressing and filling the second talc 38 in the main metal fitting 30, the sealing property between the surface of the sensor element 100 and the inner surface of the main metal fitting 30 is ensured. An alumina sleeve (insulation holder) 39 is arranged on the rear end side of the second talc 38. The sleeve 39 is formed in a cylindrical shape with a flat rear end facing surface, a shaft hole 39a is provided along the axis O, and the sensor element 100 is inserted therein. The crimping portion 30a on the rear end side of the main metal fitting 30 is bent inward, and the sleeve 39 is pressed toward the tip end side of the main metal fitting 30 via the stainless steel ring member 55.

Further, a metal protector 24 having a plurality of gas intake holes is attached to the outer periphery of the tip side of the main metal fitting 30 by welding while covering the tip portion of the sensor element 100 protruding from the tip of the main metal fitting 30. The protector 24 has a double structure, and has a bottomed cylindrical outer protector 41 having a uniform outer diameter on the outside and a bottomed cylindrical inner protector 42 having a smaller diameter than the outer protector 41 on the inside. Is placed.

On the other hand, the tip end side of the outer cylinder 25 made of SUS430 is inserted into the rear end side of the main metal fitting 30. The outer cylinder 25 has an enlarged tip portion 25a on the tip side fixed to the main metal fitting 30 by laser welding or the like. A separator 50 is arranged inside the rear end side of the outer cylinder 25, and a holding member 51 is interposed in a gap between the separator 50 and the outer cylinder 25. The holding member 51 is engaged with the flange portion 50a of the separator 50 and is fixed by the outer cylinder 25 and the separator 50 by crimping the outer cylinder 25.

Further, the separator 50 is provided with an insertion hole 50b for inserting the lead wires 11 to 15 from the front end side to the rear end side (note that the lead wires 14 and 15 are not shown). A connection terminal 16 for connecting the lead wires 11 to 15 and the electrode pad 121 (see FIG. 1) is housed in the insertion hole 50b. Each lead wire 11 to 15 is externally connected to a connector (not shown). An electric signal is input / output between the controller (external device) such as an ECU and the lead wires 11 to 15 via this connector. Further, although the lead wires 11 to 15 are not shown in detail, they have a structure in which the conductor wires are covered with an insulating film made of resin.

Further, on the rear end side of the separator 50, a substantially columnar rubber cap 52 for closing the opening 25b on the rear end side of the outer cylinder 25 is arranged. The rubber cap 52 is fixed to the outer cylinder 25 by crimping the outer periphery of the outer cylinder 25 inward in the radial direction while the rubber cap 52 is mounted inside the rear end of the outer cylinder 25. The rubber cap 52 is also provided with an insertion hole 52a for inserting the lead wires 11 to 15, respectively, from the front end side to the rear end side.

The present invention is not limited to the above embodiment, and the present invention is applied to, for example, a NOx sensor (NOx sensor element) for detecting the NOx concentration in the gas to be measured, an HC sensor (HC sensor element) for detecting the HC concentration, and the like. You may.
The method of forming the display unit is not limited to laser engraving.
Further, in the assembling step, the display portion of the sensor element may be assembled so as to protrude toward the tip end side of the main metal fitting. In this case, the display unit may be formed on the tip end side of the sensor element, and the sensor information may be managed by reading the display protruding toward the tip end side of the main metal fitting of the assembled sensor intermediate product. After that, a protector can be attached so as to cover the tip end side of the sensor element, and a gas sensor can be manufactured.

1 Gas sensor 30 Main metal fittings 40 Display unit 100 Sensor element O Axis line ML Engraved line

Claims (3)

A long plate-shaped sensor element extending in the axial direction, provided with a detection unit having one or a plurality of cells having a solid electrolyte body as an element main body and a pair of electrodes arranged on the solid electrolyte body on the tip side. ,
A display unit containing information about the sensor element is formed on the surface of the sensor element.
The display unit is a sensor element characterized by being composed of a plurality of engraved lines along the axial direction and separated from each other. A gas sensor in which the sensor element according to claim 1 is assembled inside a main metal fitting. A detection unit having one or a plurality of cells having a solid electrolyte body as an element main body and a pair of electrodes arranged in the solid electrolyte body is provided on the tip side, and a long plate-shaped sensor element extending in the axial direction is provided. It is a method of manufacturing a gas sensor.
A laser engraving step of scanning the surface of the sensor element with a laser beam in a direction along the axial direction to form a display unit containing information about the sensor element composed of a plurality of engraved lines separated from each other.
The gas sensor is characterized by having an assembling step of assembling the sensor element inside the main metal fitting so that the display portion of the sensor element protrudes toward the front end side or the rear end side of the cylindrical main metal fitting. Production method.

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