JP7223635B2 - Gas sensor and method for manufacturing gas sensor - Google Patents

Description

TECHNICAL FIELD The present invention relates to a gas sensor suitably used for detecting the gas concentration of a specific gas contained in combustion gas or exhaust gas of a combustor or an internal combustion engine, and a method of manufacturing the gas sensor.

2. Description of the Related Art Conventionally, gas sensors have been used to detect the concentration of specific components (such as oxygen) in exhaust gas from internal combustion engines. This gas sensor is constructed by assembling sensor elements extending in the axial direction, and since various performances vary slightly due to variations in the manufacturing of each sensor element, it is necessary to label each element with an identification label, read the identification label, and calibrate the sensor. there is
Also, when the sensor element is assembled to the gas sensor, the sensor element is housed in an external part and becomes invisible. Therefore, a technique of laser-marking an identification mark on the outer cylinder has been reported (see Patent Document 1).

JP 2017-161325 A (paragraph 0087)

By the way, as an external part for housing the sensor element, a seamless cylindrical part made of metal such as an outer cylinder or a protector is used. As shown in FIG. 4, the seamless tubular portion 1000 is formed by pressing a plate material or extruding a metal material, instead of bending a plate into a tubular shape and joining the joints. There may be radial wrinkles 1010 due to extrusion.
Therefore, if a linear indication (for example, a bar code) 1200 extending along the radial direction of the tubular portion 1000 is attached, the indication 1200 may be confused with the wrinkles 1010, and the indication 1200 may not be accurately read.
SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a gas sensor having a linear mark that can be reliably read on the outer surface of a seamless cylindrical portion made of metal, and a method for manufacturing the gas sensor.

In order to solve the above problems, the gas sensor of the present invention comprises a sensor element extending in an axial direction, a metal shell for holding the sensor element, a front end side or a rear end side of the metal shell, and a rear end of the sensor element. and a seamless tubular portion made of metal that accommodates an end portion or a tip portion, wherein the tubular portion is fixed to the tip side of the metal shell and accommodates the tip of the sensor element. The protector has a plurality of gas intake holes, and the outer surface of the tubular portion is spaced apart in the circumferential direction of the tubular portion and the At least one linear mark extending along the axial direction and representing predetermined information is provided , and the linear mark is provided at a location spaced from the gas intake hole in the protector in the axial direction. Characterized by

A seamless metal cylindrical part is formed by pressing a plate material or extruding a metal material instead of bending a plate into a cylindrical shape and connecting it. wrinkles may occur.
Therefore, by providing linear marks on the outer surface of the cylindrical portion spaced apart in the circumferential direction of the cylindrical portion and extending along the axial direction of the cylindrical portion, the direction in which the linear marks extend and the wrinkles of the cylindrical portion are reduced. By making the directions in which the two extend in different directions, it is possible to prevent the linear marks from being confused and the linear marks from being read incorrectly, thereby reliably reading the linear marks.

In the gas sensor of the present invention, the information may represent the type of the protector.
According to this gas sensor, the type of protector can be reliably identified using the linear mark.

In the gas sensor of the present invention, the alignment mark for reading is a linear alignment mark that extends along the axial direction of the cylindrical portion and is longer than the linear mark on the outer side of the linear mark in the circumferential direction. may be provided in parallel with the
According to this gas sensor, alignment marks that are longer and easier to read than the linear marks can be read for alignment when reading the linear marks, so that the linear marks can be read more reliably.

The gas sensor manufacturing method according to the present invention includes a seamless tubular shape made of metal for accommodating the rear end portion or the front end portion of the sensor element on the front end side or the rear end side of the metal shell holding the sensor element extending in the axial direction. The tubular part is a bottomed tubular protector that is fixed to the front end side of the metal shell and accommodates the front end of the sensor element, and the protector has a plurality of gas intake holes, and linear marks are formed on the outer surface of the cylindrical portion, spaced apart in the circumferential direction of the cylindrical portion and extending along the axial direction of the cylindrical portion to represent predetermined information. 1. One or more of the protectors are provided by press stamping at a location spaced from the gas intake hole in the axial direction of the protector .
According to this gas sensor manufacturing method, the linear mark can be clearly formed to facilitate reading.

According to the present invention, it is possible to obtain a gas sensor having a linear mark that can be reliably read on the outer surface of a seamless cylindrical portion made of metal.

1 is a perspective view of a gas sensor (oxygen sensor) according to an embodiment of the invention; FIG. FIG. 4 is a perspective view showing linear marks on the outer surface of the protector; FIG. 4 is a diagram showing linear marks and alignment marks; FIG. 10 is a diagram showing a mode of reading a display on a cylindrical portion of a conventional gas sensor;

Embodiments of the present invention will be described below.
FIG. 1 is a perspective view of a gas sensor (oxygen sensor) 1 according to an embodiment of the invention.
As shown in FIG. 1, the gas sensor 1 has therein a plate-shaped sensor element (not shown) extending in the direction of the axis O, and has a cylindrical metal shell that holds the sensor element inserted therein. 30, a bottomed cylindrical protector 24 made of metal attached to the front end of the metal shell 30, a metal outer cylinder 25 attached to the rear end of the metal shell 30, and the like.

The metal shell 30 has a male threaded portion 31 for attaching the gas sensor to the exhaust pipe, and a hexagonal portion 32 for applying an attachment tool during attachment.
A metal protector 24 having a plurality of gas intake holes 26 and covering the tip of the sensor element protruding from the tip of the metal shell 30 is attached by welding to the outer periphery of the metal shell 30 on the front end side. The protector 24 has a double structure, in which a bottomed cylindrical outer protector having a uniform outer diameter and a bottomed cylindrical inner protector having a smaller diameter than the outer protector are disposed on the inner side. , the outer surface of the protector 24 consists of an outer protector.

On the other hand, the front end side of the outer cylinder 25 is fixed to the rear end side of the metal shell 30 by laser welding or the like. Furthermore, a heat-resistant tube 40 extends inside the rear end side of the outer cylinder 25 to cover lead wires drawn out through a sealing material (grommet) (not shown).
Furthermore, the outer surface of the protector 24 is provided with a plurality of linear marks 50, which will be described later.

Next, the linear mark 50 will be described with reference to FIG. As shown in FIG. 2 , the outer surface of the protector 24 is provided with a plurality of linear marks 50 spaced apart in the circumferential direction of the protector 24 and extending along the direction of the axis O of the protector 24 .
Here, the protector 24 is formed by pressing a metal plate, forms a seamless cylindrical portion, and has press wrinkles 24s in the radial direction, as in the case of FIG.
Accordingly, linear marks 50 are provided on the outer surface of the protector 24 so as to be spaced apart in the circumferential direction of the protector 24 and extend along the direction of the axis O of the protector 24. , the linear mark 50 can be reliably read by preventing the linear mark 50 from being read accurately due to confusion between the two.
Further, the linear mark 50 has higher reading accuracy than a mark (round or triangular) recognized by its shape.

Here, in this embodiment, the linear mark 50 represents the type of protector 24 . This is because there are multiple protectors that have the same shape but are made of different metals, and protectors are used according to the heat resistance required of the gas sensor. , and linear marks 50 for image recognition of the type.
Further, in this embodiment, the linear mark 50 and the positioning mark 60 below are provided by press stamping. As a result, the linear marks 50 and the alignment marks 60 can be formed clearly and easily read.

Further, in the present embodiment, linear alignment marks 60 for reading that extend along the direction of the axis O of the protector 24 and are longer than the linear marks 50 are provided on both outer sides of the linear marks 50 in the circumferential direction. A total of two are provided parallel to the mark 50 .
As a result, when reading the linear mark 50, the alignment mark 60, which is longer than the linear mark 50 and is easy to read, can be read, so the linear mark 50 can be read more reliably.
In order to make the alignment mark 60 easier to read, the alignment mark 60 may be made thicker than the linear mark 50 or the linear mark 50 may be thicker than the linear mark 50 so that the alignment mark 60 has a stronger contrast than the linear mark 50 . It is better to make the recess deeper.
The alignment marks 60 need only be located on at least one of the outer sides of the linear marks 50 in the circumferential direction.

Further, as shown in FIG. 3, in this embodiment, the linear marks 50 are provided in two stages in the direction of the axis O of the protector 24, and each stage has five linear marks, so a total of nine linear marks 50 are provided.
Here, the protector type is represented by the number of linear marks 50. The linear mark 51 at the upper left in FIG. 3 is always displayed, and the linear mark 50e at the lower right in FIG. 3 is normally not displayed. As a result, the linear mark 50 becomes vertically asymmetrical, so that the vertical direction (the direction of the axis O) when reading the linear mark 50 becomes constant, thereby improving the reading accuracy.
The linear mark 50e is not displayed from the linear mark 51 to the ninth linear mark 59, and the linear mark 50e is displayed when the tenth linear mark is required. In this case, the linear mark 50 is vertically symmetrical, and the vertical direction (the direction of the axis O) when reading the linear mark 50 is unknown. Since the shape mark 50 is symmetrical, there is no problem.

The present invention is not limited to the above embodiments, and can be applied to, for example, a NOx sensor (NOx sensor element) that detects the NOx concentration in the gas to be measured, an HC sensor (HC sensor element) that detects the HC concentration, and the like. You may
Further, the cylindrical portion is not limited to the protector, and may be, for example, an outer cylinder. Further, the presence or absence of joints in the cylindrical portion may be recognized visually or by a microscopic image of a cross section along the radial direction. In addition, the "metal" of the cylindrical portion also includes an alloy.
The information represented by the linear mark is also not limited to the above, and may be, for example, information of the sensor element inside the gas sensor.

Reference Signs List 1 gas sensor 30 metal shell 24 cylindrical portion (protector)
50, 51 to 59, 50e Linear mark 60 Alignment mark O Axis of cylindrical portion (axis line)

Claims (4)

an axially extending sensor element;
a metal shell that holds the sensor element;
a seamless cylindrical portion fixed to the front end side or the rear end side of the metal shell and made of a metal for accommodating the rear end portion or the front end portion of the sensor element, the gas sensor comprising:
The cylindrical portion is a bottomed cylindrical protector that is fixed to the front end side of the metal shell and accommodates the front end of the sensor element, the protector having a plurality of gas intake holes,
On the outer surface of the cylindrical portion, one or more linear marks are provided that are spaced apart in the circumferential direction of the cylindrical portion and extend along the axial direction of the cylindrical portion to represent predetermined information,
The gas sensor according to claim 1, wherein the linear mark is provided on the protector at a location spaced from the gas intake hole in the axial direction . 2. The gas sensor according to claim 1, wherein said information represents a type of said protector. A linear alignment mark for reading that extends along the axial direction of the cylindrical portion and is longer than the linear mark is provided outside the linear mark in the circumferential direction and parallel to the linear mark. The gas sensor according to claim 1 or 2, characterized by: A method for manufacturing a gas sensor in which a seamless cylindrical portion made of metal for accommodating the rear end portion or the front end portion of the sensor element is fixed to the front end side or the rear end side of the metal shell holding the sensor element extending in the axial direction. There is
The cylindrical portion is a bottomed cylindrical protector that is fixed to the front end side of the metal shell and accommodates the front end of the sensor element, the protector having a plurality of gas intake holes,
Linear marks are formed on the outer surface of the cylindrical portion of the protector and are spaced apart in the circumferential direction of the cylindrical portion and extend along the axial direction of the cylindrical portion to represent predetermined information. A method for manufacturing a gas sensor, characterized in that one or more holes are provided by press stamping at a location spaced apart from the hole in the axial direction .

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