JP2007023850A - Boss part structure for sensor attachment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a boss part structure for sensor attachment suitably fixing a boss part and an exhaust system member by projection welding. <P>SOLUTION: In a boss part structure for sensor attachment fixing a lower edge outer circumference 11b of the boss part 11 to an opening edge part of an attachment hole 6a of a collecting part 6 over whole circumference thereof by projection welding under a condition where an inside of the annular boss part 11 is communicated to the attachment hole 6a of the collecting part 6, a welding ring 12 formed out of material softer than the collecting part 6 and the boss part 11 is put between the lower edge outer circumference 11b of the boss part 11 and the opening edge part of the attachment part 6a of the collecting part 6, and the three of those are fixed by projection welding under a condition where the three are put close. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a boss structure for mounting a sensor used for detecting the state of exhaust gas passing through an exhaust system member of an automobile.

  Conventionally, various sensors for detecting the state of exhaust gas are mounted on automobile exhaust system members, for example, branch pipes of exhaust manifolds, exhaust manifold assembly parts, downstream sides of catalytic converters, and the like (see Patent Document 1). ).

  One of such sensors is an oxygen sensor, in which a male screw formed on a sensing unit side of a holder unit is screwed into a female screw of a boss unit fixed to an opening edge of a mounting hole of an exhaust system member. It is fixed by doing.

Further, if the boss portion and the opening edge portion of the mounting hole of the exhaust system member are fixed by arc welding using a welding torch, it takes a long time and the workability is deteriorated.
Therefore, a technique is known in which an annular protrusion is provided on the outer periphery of the lower end of the boss portion, and the annular protrusion is brought into contact with the outer periphery of the opening edge of the mounting hole of the exhaust system member and both of them are projection welded ( Patent Document 2).
JP 2003-83061 A Japanese Patent Laid-Open No. 10-26037

  However, in the conventional invention, the opening edge portion of the mounting hole of the exhaust system member is formed as flat as possible in order to improve the adhesion with the annular projection of the boss portion. Since there is some inclination or unevenness due to errors in the processing accuracy of the edge, there is a gap between the annular protrusion of the boss and the opening edge of the mounting hole in the exhaust system member during projection welding. As a result, there is a problem that the portions where the gap is formed cannot be fixed well.

  The present invention has been made to solve the above-described problems, and the object of the present invention is to allow the boss portion and the exhaust system member to be allowed to be inclined or uneven at the opening edge of the mounting hole of the exhaust system member. The object is to provide a sensor mounting boss structure which can be fixed by projection welding.

  In the first aspect of the present invention, the inner side of the annular boss portion is communicated with the mounting hole of the exhaust system member, and the lower end outer periphery of the boss portion extends over the entire circumference thereof. In the sensor mounting boss structure fixed to the opening edge of the boss by projection welding, the boss and the exhaust system are disposed between the outer periphery of the lower end of the boss and the opening edge of the mounting hole in the exhaust system member. These three members are fixed by projection welding in a state of being in close contact with a weld ring formed of a softer material than the member.

  In the first aspect of the present invention, the inside of the annular boss portion is communicated with the mounting hole of the exhaust system member, and the lower end outer periphery of the boss portion extends over the entire circumference of the mounting hole of the exhaust system member. In the sensor mounting boss structure fixed to the opening edge of the boss by projection welding, the boss and the exhaust system are disposed between the outer periphery of the lower end of the boss and the opening edge of the mounting hole in the exhaust system member. Since these three members are fixed by projection welding in a state in which they are in close contact with each other with a weld ring formed of a softer material than the member, the weld ring functions as a sealing material and a welding material between the boss portion and the exhaust system member. Accordingly, the boss portion and the exhaust system member can be satisfactorily fixed by projection welding while allowing the inclination and unevenness at the opening edge of the mounting hole of the exhaust system member.

  Embodiments of the present invention will be described below with reference to the drawings.

In the first embodiment, an example will be described in which the exhaust system member is applied to a collecting portion of the exhaust manifold and the sensor is applied to an oxygen sensor for detecting the oxygen concentration in the collecting portion.
1 is an overall plan view showing the vicinity of a collective portion in which a boss portion structure for mounting a sensor according to a first embodiment of the present invention is adopted, FIG. 2 is a right side view thereof, and FIG. 3 is a cross section taken along line S3-S3 in FIG. FIG. 4 is an exploded view of the gathering portion, the boss portion, and the oxygen sensor, FIG. 5 is a perspective view of the welding ring, and FIGS. 6 and 7 are diagrams for explaining projection welding.

First, the overall configuration will be described.
As shown in FIGS. 1 and 2, in the sensor mounting boss structure of the present embodiment, the head flange 1, the four branch pipes 2 to 5, the collecting part 6, the catalytic converter 7, and the oxygen sensor 10. Is provided.
The upstream ends of the branch pipes 2 to 5 are connected to corresponding ports of the head flange 1 that are fastened to a cylinder head of an engine (not shown).
On the other hand, downstream end portions of the branch pipes 2 to 5 are connected to the upstream end portions of the collecting portion 6 in a state of being processed into a quarter circular cross section so that the entire outer shape is circular. Yes.
The downstream end portion of the collecting portion 6 is connected to the upstream end portion of the catalytic converter 7 in which the catalyst carrier 8 is accommodated, and the downstream end portion of the catalytic converter 7 is rearwardly omitted through the flange portion 9. Connected to side exhaust pipe.

An oxygen sensor 10 to be described later is attached to the middle part of the gathering part 6 via a boss part 11.
As shown in FIGS. 3 and 4, the oxygen sensor 10 is used for feedback control of the air / fuel ratio of the engine by detecting the oxygen concentration contained in the exhaust gas passing through the collecting portion 6. A wiring 10b placed outside the exhaust gas flow and electrically connected to a control device (not shown) is connected to one end of the main body 10a, and a hexagonal column shaped holder 10c is provided in the middle. The other end portion placed in the exhaust gas flow is provided with a sensing portion 10e having a plurality of pores 10d. Further, a male screw 10f is formed on the sensing unit 10e side of the holder unit 10c.

The boss portion 11 is formed in a cylindrical shape as a whole, and a female screw 11a that can be screwed into the male screw 10f of the holder portion 10c is formed inside thereof.
Moreover, the lower end outer periphery 11b of the boss | hub part 11 is being fixed to the opening edge part of the attachment hole 6a of the gathering part 6 by the projection welding mentioned later through the welding ring 12 of the substantially rhombus cross section shown in FIG.

  The oxygen sensor 10 is configured such that the male screw 10f of the oxygen sensor 10 is inserted into the assembly portion 6 from the female screw 11a of the boss portion 11 via the annular seal member S. 11 is fixed by being screwed into the female screw 11a.

  In the first embodiment, the gathering portion 6 and the boss portion 11 are made of stainless steel (for example, SUS430), and the welding ring 12 is formed of carbon steel, which is a softer material than the gathering portion 6 and the boss portion 11. .

Next, the operation will be described.
When the thus configured oxygen sensor 10 is attached to the boss portion 11, first, as shown in FIG. 6, the welding ring 12 and the inside of the boss portion are in communication with the mounting hole 6 a of the assembly portion 6. Then, the pair of electrodes T1 and T2 are disposed above the boss portion 11 and inside the assembly portion 6.

  Next, by moving the pair of electrodes T1 and T2 in the direction of the arrow, the welding ring 12 is sandwiched and pressed between the boss portion 11 and the assembly portion 6 as shown in FIG.

  At this time, since the upper and lower apexes 12a and 12b of the rhombus section of the welding ring 12 are deformed and bite so as to follow the lower end outer periphery 11b of the boss portion 11 and the opening edge of the mounting hole 6a over the entire circumference, these three The person can be brought into good contact with no gap.

  Next, by passing an electric current through the pair of electrodes T1, T2, the contact portion X1 between the upper top portion 12a (see FIG. 5) of the welding ring 12 and the lower end outer periphery 11c of the boss portion 11, and the lower top portion of the welding ring 12 These three members are fixed by melting the contact portion X2 between 12b (see FIG. 5) and the opening edge portion of the mounting hole 6a in the gathering portion 6 and performing projection welding.

  Therefore, the weld ring 12 can be used as a sealing material and a welding material for the boss portion 11 and the gathering portion 6.

  Here, in the conventional invention, the opening edge portion of the mounting hole of the exhaust system member is formed as flat as possible in order to improve the adhesion with the annular projection of the boss portion. Since there is some inclination and unevenness due to errors in the processing accuracy of the product shape and the opening edge, during projection welding, the annular protrusion of the boss part and the opening edge of the mounting hole in the exhaust system member There was a problem in that a gap was formed between them, and a portion where the gap was formed could not be fixed well.

  In the first embodiment, since the collecting portion 6 that is an exhaust system member is tubular, in particular, the opening edge portion of the mounting hole 6a of the collecting portion 6 is likely to be inclined or uneven.

  On the other hand, in the invention of the first embodiment, the upper and lower apexes 12a and 12b of the diamond-shaped cross section of the welding ring 12 are formed on the lower end outer periphery 11c of the boss portion 11 and the opening edge of the mounting hole 6a over the entire circumference. Since they are deformed so as to follow and bite in, these three components can be brought into full contact with no gap, thereby realizing good fixation during projection welding.

Next, after the annular sealing member S is arranged on the sealing surface 11c of the boss part 11, the sensing part 10e of the oxygen sensor 10 is inserted from above and arranged at the approximate center in the assembly part 6, and the oxygen sensor 10 The male screw 10f is screwed into the female screw 11a of the boss portion 11, and the seal surface 10g of the holder portion 10c and the seal surface 11a of the boss portion 11 are brought into close contact with each other via the seal member S, thereby completing the mounting of the oxygen sensor 10. (See FIG. 3).
Note that the sensing member 10e of the oxygen sensor 10 may be inserted into the assembly portion 6 in this state after the sealing member S is mounted in advance on the sealing surface 10g of the holder portion 10c of the oxygen sensor 10.

Next, the effect will be described.
As described above, in the sensor mounting boss structure of the first embodiment, the inner side of the annular boss 11 is communicated with the mounting hole 6a of the assembly 6, and the boss 11 In the boss part structure for sensor attachment in which the lower end outer periphery 11b is fixed to the opening edge of the attachment hole 6a of the assembly part 6 over the entire periphery by projection welding, the lower end outer periphery 11b and the assembly part 6 of the boss part 11 are fixed. Since the welding ring 12 formed of a softer material than the boss portion 11 and the gathering portion 6 is sandwiched between the opening edge portion of the mounting hole 6a in FIG. The welding ring 12 can function as a sealing material and a welding material between the boss portion 11 and the gathering portion 6, thereby allowing the boss portion 11 and the collecting portion to be gathered while allowing the inclination and unevenness of the opening edge of the mounting hole 6 a. The part 6 can be fixed by well projection welding.
In addition, since it is not necessary to separately forge the tip portion on the boss portion as in the conventional case, the thin groove shape formed on the forging die wears down and the durability time is shortened. By doing so, the boss portion 11 can be easily manufactured. Furthermore, the weld ring 12 can also be easily manufactured.

Example 2 will be described below.
In addition, the same code | symbol is attached | subjected about the structural member same as the boss | hub part structure for sensor attachment demonstrated in the said Example 1 in the said Example 2, the description is abbreviate | omitted, and only a different point is explained in full detail.

  FIG. 8 is a view for explaining the boss part structure for sensor mounting according to the second embodiment, and FIG. 9 is an exploded view thereof.

  As shown in FIGS. 8 and 9, in the sensor mounting boss structure of the second embodiment, a positioning portion 20 protruding in a columnar shape from the lower end outer periphery 11 b of the boss portion 12 is provided and welded to the positioning portion 20. It differs from the said Example 1 in the ring 12 being externally fitted.

  Accordingly, after the welding ring 12 is fitted and fitted in advance to the positioning portion 20 of the boss portion 11 and the boss portion 11 is disposed at the opening edge of the mounting hole 6a of the assembly portion 6, these contact portions are arranged. X1 to X3 can be melted and fixed by projection welding.

  Therefore, these three can be stably fixed in a state where the boss portion 11 and the welding ring 12 are positioned.

  The positioning portion 20 is not limited to a columnar shape as long as it can position the welding ring 12, and a plurality of claw-like members are provided downward from the outer periphery 11 b of the lower end of the boss portion 11. You may make it contact | abut.

Although the present embodiment has been described above, the present invention is not limited to the above-described embodiment, and design changes and the like within the scope not departing from the gist of the present invention are included in the present invention.
For example, the cross-sectional shape and thickness of the welding ring 12 can be set as appropriate.

Further, in the present embodiment, the case where the exhaust system member is applied to the exhaust manifold assembly portion and the sensor is applied to the oxygen sensor for detecting the oxygen concentration in the exhaust manifold portion has been described. However, the exhaust system member is connected to the exhaust manifold branch. It may be on the downstream side of the pipe or the catalytic converter, and is not limited to the gathering portion of the exhaust manifold.
Similarly, the sensor may be any sensor that is used to detect the state of the exhaust gas that passes through the exhaust system member. For example, a temperature sensor may be applied.

It is a whole top view which shows the collection part periphery as which the boss | hub part structure for sensor attachment of Example 1 of this invention was employ | adopted. It is a right view which shows the collection part periphery as which the boss | hub part structure for sensor attachment of Example 1 of this invention was employ | adopted. It is sectional drawing in the S3-S3 line of FIG. 2, and is a figure explaining the attachment state of a gathering part, a boss | hub part, and an oxygen sensor. It is sectional drawing in the S3-S3 line | wire of FIG. It is an exploded view of a gathering part, a boss part, and an oxygen sensor. It is a figure explaining projection welding. It is a figure explaining projection welding. It is a figure explaining the boss | hub part structure for sensor attachment of the present Example 2. FIG. It is an exploded view explaining the boss | hub part structure for sensor attachment of the present Example 2. FIG.

Explanation of symbols

S seal member X1, X2, X3 contact part 1 head flange 2, 3, 4, 5 branch pipe 6 collecting part 7 catalytic converter 8 catalyst carrier 9 flange part 10 oxygen sensor 10a main body 10b wiring 10c holder part 10d plural pores 10e sensing part 10f male screw 10g sealing surface 11 boss part 11a female screw 11b lower end outer periphery 11c sealing surface 12 welding ring 12a upper top part 12b lower top part 20 positioning part

Claims (1)

Assuming that the inside of the annular boss is in communication with the mounting hole of the exhaust system member, the outer periphery of the lower end of the boss is fixed to the opening edge of the mounting hole of the exhaust system member by projection welding over the entire circumference. In the sensor mounting boss structure
These bosses are in close contact with the outer periphery of the lower end of the boss portion and the opening edge of the mounting hole in the exhaust system member with a weld ring formed of a softer material than the exhaust system member interposed therebetween. A boss structure for mounting a sensor, characterized in that a person is fixed by projection welding.

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