JP7465175B2 - Sensor manufacturing system and method for manufacturing sensor - Google Patents

Description

The present invention relates to a manufacturing system for a sensor having a sensor element for detecting a specific gas component, temperature, etc., and a manufacturing method for the sensor.

2. Description of the Related Art As sensors (gas sensors) for improving fuel efficiency and controlling combustion in internal combustion engines such as automobile engines, oxygen sensors that detect the oxygen concentration in exhaust gas and air-fuel ratio sensors are known.
Known examples of such gas sensors include a structure in which a sensor element having a detection portion that detects the concentration of a specific gas is held in a metal shell, and portions of the sensor element that protrude from the front and rear of the metal shell are covered and protected with metal members (such as an outer tube or a protector) (see, for example, Patent Document 1).

JP 2019-105620 A (FIG. 1)

However, the composition (material) of these metal parts may be changed depending on the application, such as the heat resistance required for the gas sensor, even if they have the same shape and size. For example, stainless steel is used for general use temperatures, but nickel alloys are used for use at higher temperatures. A large number of metal parts for each of these compositions are manufactured and stored in advance, and the desired metal part is taken out when assembling the sensor.
However, there are cases where the management tags of stored metal components fall off, making it impossible to identify their composition, or where they are mixed with components of different compositions. Furthermore, since these metal components have similar dimensions and appearances despite their different compositions, there is a problem that they cannot be distinguished from one another as is.

The present invention was made in consideration of this current situation, and aims to provide a sensor manufacturing system and a sensor manufacturing method that can accurately distinguish between metal members with different compositions and assemble them into a sensor.

The sensor manufacturing system of the present invention is a sensor manufacturing system comprising a sensor element and a metal member to be assembled to the sensor element, wherein the metal members are made of at least two or more types each having a different composition, the sensors are two or more types of sensors to which the metal members of each composition are assembled, and the system is characterized in comprising a discrimination means for discriminating the composition of the metal member or the composition of its material, a molding means for molding the metal member from the material, and an assembly means for assembling the metal member to the sensor element.

According to this sensor manufacturing system, the composition of the metal component or the composition of the material thereof is identified, so that metal components with different compositions can be accurately distinguished and assembled into the sensor.

In the sensor manufacturing system of the present invention, the determining means may determine a composition of the material before it is molded by the molding means.
According to this sensor manufacturing system, the composition of the metal member material is identified before the metal member is assembled into the sensor element, so that metal members with different compositions can be more accurately distinguished and assembled into the sensor. In addition, because the composition is identified in the material state, waste caused by molding the wrong material can be avoided.

In the sensor manufacturing system of the present invention, the determining means may determine the composition of the metal member after it has been molded by the molding means and before it is assembled.
According to this sensor manufacturing system, the composition of the material of the metal member after molding can be identified, so that metal members with different compositions can be more accurately distinguished and assembled into the sensor.

In the sensor manufacturing system of the present invention, the material and/or the metal member may have approximately the same dimensions for each composition.
If the materials or metal members have approximately the same dimensions for each composition, the compositions cannot be distinguished from their external shapes, making the present invention even more effective.

The sensor manufacturing system of the present invention may further include a material storage means for separately storing a plurality of the materials.
If the raw material is prepared and stored in a raw material storage means and taken out when molding is required, the selection of a raw material of an incorrect composition for molding increases the number of defective products, making the present invention even more effective.

In the sensor manufacturing system of the present invention, the determining means may be of a portable type.
According to this sensor manufacturing system, an operator can carry the discrimination means to any position in the system when necessary (for example, before introduction into the molding means, or before assembly after molding) and perform discrimination, making discrimination more reliable and increasing the degree of freedom in discrimination.

The sensor manufacturing method of the present invention is a method for manufacturing a sensor comprising a sensor element and a metal member assembled to the sensor element, and is characterized by comprising an identification process for identifying the composition of the metal member or the composition of its material, a molding process for molding the metal member from the material, and an assembly process for assembling the metal member to the sensor element.

This invention makes it possible to accurately distinguish metal parts with different compositions when assembling them into a sensor.

1 is a cross-sectional view taken along a longitudinal direction of a gas sensor manufactured by a sensor manufacturing system according to an embodiment of the present invention. FIG. 2 is a diagram showing the protector before it is attached. 11A and 11B are diagrams showing a manner in which a protector, which is a metal member, is assembled to a sensor element. FIG. 1 illustrates a system for manufacturing a sensor according to an embodiment of the present invention.

Hereinafter, an embodiment of the present invention will be described.
FIG. 1 is an overall cross-sectional view taken along the longitudinal direction of a sensor (oxygen sensor, which is a gas sensor) 200 manufactured by a sensor manufacturing system according to an embodiment of the present invention, and FIG. 2 is a view showing a protector 140 before being attached.
This sensor 200 is an oxygen sensor (full range air-fuel ratio gas sensor) that detects the oxygen concentration in the exhaust gas of an automobile or various internal combustion engines.

1, the sensor 200 includes a cylindrical metal shell 138 having a threaded portion 139 formed on its outer surface for fixing to an exhaust pipe, a plate-like sensor element 10 extending in the direction of axis O (the longitudinal direction of the sensor 200: the up-down direction in the figure), a cylindrical ceramic sleeve 106 and a ceramic holder 151 arranged so as to surround the radial periphery of the rear end side of the sensor element 10, a ceramic separator 166 arranged inside the tip side of an insertion hole 168 penetrating in the axial direction so as to surround the periphery of the rear end side of the sensor element 10, five terminal fittings 21 (only three are shown in FIG. 1) arranged between the sensor element 10 and the separator 166, a double protector 140 fixed to the tip side of the metal shell 138, and an outer cylinder 144 fixed to the rear end side of the metal shell 138.
The detection portion 10a at the tip of the sensor element 10 is covered with a porous protective layer 20 such as alumina.

The metal shell 138 is made of stainless steel, has a through hole 154 penetrating in the axial direction, and is configured in a generally cylindrical shape with a shelf portion 152 protruding radially inward from the through hole 154. The sensor element 10 is disposed in the through hole 154 so that the tip portion including the detection portion 10a of the sensor element 10 protrudes beyond its own tip. Furthermore, the shelf portion 152 is formed as an inward tapered surface that is inclined with respect to a plane perpendicular to the axial direction.

Inside the through hole 154 of the metal shell 138, an annular alumina ceramic holder 151, a powder packed layer 153 (hereinafter also referred to as the talc ring 153), and the above-mentioned ceramic sleeve 106 are layered in this order from the front end to the rear end, surrounding the radial periphery of the sensor element 10.
A crimped packing 157 is disposed between the ceramic sleeve 106 and a rear end portion 158 of the metallic shell 138. The rear end portion 158 of the metallic shell 138 is crimped so as to press the ceramic sleeve 106 against the front end side via the crimped packing 157.

The ceramic holder 151 is made of insulating ceramic (e.g., alumina), is formed in a roughly short cylindrical shape, and has a tip-facing surface 151a tapered toward the tip. A portion of the tip-facing surface 151a near the outer periphery is engaged with a shelf portion 152 of the metallic shell 138, and the ceramic holder 151 is pressed from the rear end side by a talc ring 153, so that the ceramic holder 151 is positioned within the metallic shell 138 and is fitted in with a gap.
Further, a recess 151h is formed on the tip side of the ceramic holder 151 so as to surround the insertion hole of the sensor element 10 and to be recessed rearward.

On the other hand, as shown in FIG. 1, a protector 140 which is a metallic cylindrical double protector having a plurality of holes and covers the tip portion (including the detection portion 10a) of the sensor element 10 protruding from the metallic shell 138 is attached by welding or the like to the outer periphery of the tip portion 138s (lower portion in FIG. 1) of the metallic shell 138.
The double protector 140 has a cylindrical inner protector 143 with a bottom that is disposed with a gap from the detection portion 10a, and a cylindrical outer protector 142 with a bottom that is disposed with a gap from the inner protector 143. Rear end portions 140e that form openings of the protectors 143 and 142 overlap and are welded to the outer surface of the tip portion 138s of the metallic shell 138.

2 shows the outer shape of the protector 140 before it is attached to the metal shell 138. The protector 140 is press-fitted into the metal shell 138 without crimping, and then laser-welded.
The protector 140 corresponds to the "metal member" in the claims.

An outer tube 144 is fixed to the outer periphery of the rear end of the metal shell 138 so as to cover the rear end of the sensor element 10 and the separator 166. In addition, a rubber grommet (sealing member) 170 is disposed in the opening at the rear end side (upper part in FIG. 1) of the outer tube 144. The rubber grommet (sealing member) 170 has lead wire insertion holes 170h through which five lead wires 146 (only three are shown in FIG. 1) electrically connected to the five terminal fittings 21 (only three are shown in FIG. 1) of the sensor element 10 are inserted.

A separator 166 is disposed at a distance from the metal shell 138 on the rear end side (upper side in FIG. 1) of the sensor element 10 protruding from the rear end 158 of the metal shell 138. The separator 166 is disposed around a total of five electrode pads (not shown) formed on the main surface of the rear end side of the sensor element 10. The separator 166 is formed in a cylindrical shape having an insertion hole 168 penetrating in the axial direction, and is provided with a flange portion 167 protruding radially outward from the outer surface. The separator 166 is held inside the outer tube 144 by abutting the flange portion 167 against a step portion of the outer tube 144 and tightening the outer tube 144 via a holding member 169.

Here, the outer tube 144 is crimped at three points on the rear end side of the grommet 170, the retaining member 169, and the metal shell 138 to form crimped portions C1, C2, and C3.

Next, a sensor manufacturing system according to an embodiment of the present invention will be described with reference to FIGS.
FIG. 3 is a diagram showing a manner in which a protector 140, which is a metal member, is assembled to the sensor element 10, and FIG. 4 is a diagram showing a sensor manufacturing system 300 according to an embodiment of the present invention.
As shown in FIG. 3, when the protector 140 is to be attached to the sensor element 10, an assembly A1 in which the sensor element 10 is held by the metal shell 138 is prepared in advance.
Then, the rear end portion 140e of the protector 140 is fitted onto the front end portion 138s of the metallic shell 138 of the assembly A1, and the rear end portion 140e is welded all around, thereby assembling the protector 140 to the sensor element 10.

In this embodiment, the protector 140 (each of the protectors 143, 142) is made of two types of material, stainless steel (e.g., SUS310S) and Ni alloy (NCF601: Inconel alloy). The sensors are two or more types of sensors to which the protectors 140 with different compositions are attached. Specifically, there is a sensor for normal use temperatures to which a protector 140 made of stainless steel is attached, and a sensor for high temperatures to which a protector 140 made of Ni alloy is attached.

As shown in FIG. 4, in a sensor manufacturing system 300, two types of coils 301, 303 are used for manufacturing the protector 140 (the protectors 143, 142), and management tags 301L, 303L indicating the material (SUS310S or NCF601) are attached to the coils 301, 303, respectively.
First, a strip unwound from a coil 301 is punched into a number of disk-shaped blanks 143x1 by a predetermined punching machine 310. Similarly, a strip unwound from a coil 303 is punched into a number of disk-shaped blanks 143x2 by a punching machine 310.
The raw materials 143x1 and 143x2 are respectively stored (kept) in cases (raw material storage means) 321 and 323. Management tags 321L and 323L indicating the material (SUS310S or NCF601) are also attached to the cases 321 and 323, respectively.

Next, the blanks 143x1 and 143x2 are drawn by a press drawing machine (forming means) 312 to form the cylindrical inner protector 143.
Here, for example, when blanks 143x1 are punched out from coil 301, coils 301 and 303 are transferred to an uncoiler each time a certain number of blanks 143x1 are punched out. However, the composition of coils 301 and 303 may become unknown due to, for example, management tags 301L and 303L falling off from each coil.
Similarly, there are cases where the management tags 321L, 323L of the cases 321, 323 fall off, or where material 143x2 of a different composition is mixed into the case 321.

Therefore, in this example, when the raw materials 143x1, 143x2 are introduced from each case 321, 323 into the press drawing machine 312, the composition of the raw materials 143x1, 143x2 is determined one by one by the determination means 350, and only the correct raw material 144x1 is introduced into the press drawing machine 312.
The discrimination means 350 may be, for example, a tester that uses eddy current to measure conductivity and discriminates the composition based on the difference in conductivity depending on the metal material. For example, Meiko's "Metal Tester" is a commercially available portable type tester. In the case of this metal tester, the conductivity is measured by contacting a probe extending from the main body with the surface of the material to be measured.
The discrimination means 350 may be any device capable of measuring differences in physical properties resulting from differences in the composition of materials, and may be, for example, a color difference meter that discriminates differences in the color tone of materials.

Although not shown, outer protector 142 is similarly punched out of coils 301 and 303 into a disk-shaped material for outer protector 142, and processed by a press drawing machine to form cylindrical outer protector 142.
After molding, the inner protector 143 and the outer protector 142 are stored in a case 325 in multiple pieces as necessary (or are drawn by the press drawing machine 312 without being stored and then continuously) and are then assembled into the assembly A1 (Figure 2).
Specifically, the inner protector 143 is press-fitted into the inside of the outer protector 142 to form an integrated protector 140. Meanwhile, the assembly A1 is gripped by a chuck 331 and fitted to the protector 140, and the rear end portion 140e is fully welded by a welding machine 335 to assemble the protector 140 to the sensor element 10, thereby forming an element assembly A2 in which the protector 140 is assembled to the sensor element 10.
Thereafter, the outer cylinder assembly A3, in which the grommet 170, the holding member 169, the separator 166, the terminal fittings 21 and the lead wires 146 are arranged inside and the crimped portions C1 and C2 are formed, is assembled to the element assembly A2, and the sensor 200 is manufactured.
The chuck 331 and the welding machine 335 correspond to the "assembly means" in the claims.

As described above, the composition of the protector 140 (its material) is identified before the protector 140 is attached to the sensor element 10, so that protectors 140 having different compositions can be distinguished without fail and attached to the sensor.
4, in this example, the discrimination means 350 discriminates the composition of the material 143x1 before it is formed by the press drawing machine (forming means) 312, and also discriminates the composition of the protector 140 after it is formed and before it is assembled. The discrimination means 350 may be configured to discriminate only the composition of the protector 140 after it is formed and before it is assembled.

In this example, the materials 143x1, 143x2 and the protector 140 (the inner protector 143 and the outer protector 142) have substantially the same dimensions for each composition. In such a case, the composition cannot be distinguished from the outer shape, so the present invention is even more effective.
Incidentally, "substantially the same dimensions" means that the difference in dimensions (length) is within 1%.

In this example, the device further includes cases (material storage means) 321 and 323 for separately storing the multiple materials 143x1 and 143x2, respectively.
If the materials 143x1 and 143x2 were prepared and stored in the cases 321 and 323 and taken out when molding was required, the number of defective products would increase when a material of an incorrect composition was selected and molded, making the present invention even more effective.
Of course, the present invention can also be applied to a system in which the materials 143x1 and 143x2 are not prepared in advance but are continuously sent to the press drawing machine (forming means) 312 in an assembly line.

In addition, in this example, the discrimination means 350 is a portable type. In this way, an operator can carry the discrimination means 350 to any position in the system when necessary (for example, before being introduced into the press drawing machine (molding means) 312 in FIG. 4, or before being assembled after molding) and make a discrimination, which makes the discrimination more reliable and increases the degree of freedom in discrimination.

The sensor manufacturing method according to the embodiment of the present invention can be implemented by performing the sensor manufacturing system according to the embodiment of the present invention in the above-described procedure shown in FIG. 4.

It goes without saying that the present invention is not limited to the above-described embodiment, but covers various modifications and equivalents within the spirit and scope of the present invention.
The composition of the metal member is not limited to the above.
The metal member may be any member that can be assembled to the sensor element, and examples of such members include a metal shell, an outer cylinder, and a metal terminal, in addition to a protector. Furthermore, "assembled to the sensor element" is not limited to a member that is directly connected to the sensor element, and may be a component of the sensor that is fixed to the sensor apart from the sensor element.
The material for the metal member may be a block body in a columnar shape or the like in addition to the plate-like shape described above. Such a block body may be formed into the metal member by machining or the like, or may be cut out from a raw material in a rectangular column or a cylindrical shape.

The sensor is not limited to a gas sensor, but may also be a temperature sensor. Gas sensors include oxygen sensors, full-range gas sensors, and NOx sensors. A cylindrical sensor element may also be used.

10 Sensor element 140 Protector (metal member)
143x1, 143x2 Metallic material 200 Gas sensor (sensor)
312 Press drawing machine (molding means)
321, 323 Case (material storage means)
331, 335 Chuck, welding machine (assembly means)
350 Discrimination means

Claims (7)

A sensor manufacturing system including a sensor element and a metal member to be assembled to the sensor element,
the metal member is made of at least two or more types of metal members each having a different composition, and the sensor is made of two or more types of sensors to which the metal members having the respective compositions are assembled,
A discrimination means for discriminating the composition of the metal member or the composition of its material;
a forming means for forming the metal member from the material;
an assembly means for assembling the metal member to the sensor element;
A sensor manufacturing system comprising: The sensor manufacturing system according to claim 1, characterized in that the discrimination means discriminates the composition of the material before it is molded by the molding means. The sensor manufacturing system according to claim 1 or 2, characterized in that the discrimination means discriminates the composition of the metal member after it has been formed by the forming means and before it is assembled. The sensor manufacturing system according to any one of claims 1 to 3, wherein the material and/or the metal member have approximately the same dimensions for each composition. The sensor manufacturing system according to claim 4, further comprising a material storage means for separately storing the plurality of materials. The sensor manufacturing system according to any one of claims 1 to 4, characterized in that the discrimination means is a portable type. A method for manufacturing a sensor including a sensor element and a metal member assembled to the sensor element, comprising the steps of:
A determination step of determining the composition of the metal member or the composition of its material;
a forming step of forming the metal member from the material;
an assembling step of assembling the metal member to the sensor element;
A method for manufacturing a sensor comprising the steps of:

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