WO2004106910A1

WO2004106910A1 - Gas sensor and method of producing the same

Info

Publication number: WO2004106910A1
Application number: PCT/JP2004/007401
Authority: WO
Inventors: Hisaharu Nishio; Takashi Nakao; Kazuhiro Kouzaki; Yuuichi Yamada
Original assignee: Ngk Spark Plug Co., Ltd.
Priority date: 2003-05-29
Filing date: 2004-05-24
Publication date: 2004-12-09
Also published as: DE112004000050T5; DE112004000050B4; CN1701230A; CN100516859C

Abstract

The amount of use of a seal member for maintaining air-tightness between a sensor’s metallic-member body and element is reduced, sealing capability is enhanced, and the sensor is made shorter and smaller in size. In a gas sensor, a detection element (15) is positioned in a metallic-member body (2), an electrode layer on an outer peripheral surface is electrically connected, and a terminal member (31) is inserted in the element (15) so as to be electrically connected to an electrode layer on an inner peripheral surface. In order to retain a seal member (21), located between the metallic-member body (2) and the detection element (15), by compressing it toward the head side by a ceramic sleeve (25) having a flange (28), the seal member (21) is positioned more on the head side than rear ends (2b, 15c) of the metallic-member body and the detection element, respectively. Further, a sleeve head (26) is positioned more on the head side than a rear end (15c) of the detection element and compresses the seal member (21). The seal member (21) does not straddle on the terminal member in the axis (G) direction differently from conventional products, and this enables the amount of the seal member to be reduced.

Description

Gas sensor and its manufacturing method <Technical field>

The present invention relates to a gas sensor (hereinafter, simply referred to as a sensor) such as an oxygen sensor used for detecting an oxygen concentration in exhaust gas of an internal combustion engine.

Light

Background technology>

This kind of gas sensor has a detection element (hereinafter, simply referred to as an element) made of a cylindrical oxygen ion conductor whose front end is closed, having an electrode layer on the inner and outer surfaces, respectively. It is positioned and fixed within a surrounding metal fitting body. Then, the electrode layer on the outer peripheral surface is electrically connected to the metal fitting main body, and a terminal member (metal terminal) is inserted into the opening at the rear end of the detecting element from the internal connection terminal side on the distal end side to insert the inner peripheral surface. (See, for example, FIGS. 2 and 3 in Patent Document 1). This element is attached to the exhaust pipe of an internal combustion engine from the outside. The electrode layer (reference electrode layer) on the inner peripheral surface (inner surface) of the element is used as a reference oxygen gas (atmosphere), and the outer peripheral surface (outer surface). The electrode layer (measurement electrode layer) is brought into contact with the exhaust gas to generate an electromotive force (potential difference) between the two electrodes corresponding to the oxygen concentration difference on the inner and outer peripheral surfaces of the element, and controls the signal based on this electromotive force. It outputs to the circuit, detects the oxygen concentration, and controls the air-fuel ratio.

In the gas sensor having such a configuration, when the seal (airtightness and liquid tightness) between the inner peripheral surface (inner surface) and the outer peripheral surface (outer surface) of the element is broken, the exhaust gas enters the inside of the element. . Therefore, the reference oxygen gas on the inner surface side of the element is contaminated, and the ability to detect the oxygen concentration is reduced. In addition, various problems occur such as oil contained in the exhaust gas causing corrosion of the electrode layer on the inner surface. Therefore, it is necessary to ensure a seal between the inner peripheral surface of the main body and the outer peripheral surface of the element where exhaust gas can enter.

Under these circumstances, the gas sensor described in FIGS. 2 and 3 of Patent Document 1 Inside the (mounting bracket), near the rear end (upper end in the figure) of the element, and in the annular space of the outer peripheral surface of the terminal member (metal terminal) with the front end inserted inside the element, talc

(Talc powder) and other sealing materials are placed and filled, thereby holding the seal. That is, a ceramic sleeve is arranged at the rear end of the sealing material, and at a portion near the rear end of the bracket body, for example, a sleeve pressing and fixing is performed by bending the portion near the rear end inward and pressing the sleeve toward the front end side. The seal material was compressed by means to secure the seal.

[Patent Document 1] Japanese Utility Model Application Publication No. Sho 53-958584 (FIGS. 2 and 3) <Disclosure of the Invention>

However, in the sensors described in FIGS. 2 and 3 of Patent Document 1, the sealing material straddles the two components of the element and the terminal member in the axial direction. The arrangement area becomes longer. In such a sensor structure in which the length of the seal material in the axial direction is long, it is difficult to apply a uniform load to the seal material when compressing (pressing) the seal material and placing it inside the bracket body. It is easy to form a sealing material that is prone to have a portion where specific gravity does not increase partially. As for a sealing material having a portion where the specific gravity does not increase partially, the sealing performance as a sensor may be deteriorated without obtaining sufficient sealing performance. On the other hand, it is conceivable to increase the packing density of the sealing material having a long axial length by applying a high load, but this is not practical because the load may crack the detecting element.

Further, in such a gas sensor, an output connection cord is connected to the terminal member (metal terminal) to output to the control device. Here, in order to ensure the stability of the connection, water resistance, insulation, etc., the outside of the terminal fitting of the cord is usually covered with a rubber cap (rubber cover). There was a request like this. In other words, since the temperature of the metal fitting body that forms the sensor becomes high due to the heat of the exhaust gas, the rubber cap also becomes a high-Pen due to the propagation of this heat and the radiant heat. Therefore, even if a rubber material having high heat resistance is used for the rubber cap, it is necessary to take measures to protect against such heat damage. Because of this, rubber When the cap is fitted (set) to the gas sensor, it is necessary to keep a predetermined distance (distance) from the rear end of the bracket body to the tip of the rubber cap.

On the other hand, there has been a demand for downsizing and weight reduction of such sensors based on the mounting space and the like. However, in the sensors described in FIGS. 2 and 3 of Patent Document 1, there is a demand for downsizing of the sensor based on the requirement for maintaining such dimensions and the structure in which the arrangement region of the sealing material is long as described above. The problem is that they cannot respond to The present invention has been made in view of the above-mentioned problems of the conventional sensor, and aims to improve the sealing performance of the sensor between the metal body of the sensor and the element by using a sealing material, and to shorten or downsize the sensor. Its purpose is to aim.

In order to achieve the above object, the invention according to claim 1 is a metal fitting formed so as to surround a detection element having a cylindrical shape with a closed end and having an electrode layer on the inner and outer peripheral surfaces. Positioned inside the body, electrically connecting the electrode layer on the outer peripheral surface to the metal fitting body,

A gas sensor comprising a terminal member inserted into a rear end opening of the detection element from a front end side thereof and electrically connected to an extreme layer of the inner peripheral surface,

Disposing a sealing material in an annular space between an inner peripheral surface of the metal fitting body and an outer peripheral surface of the detection element;

A cylindrical ceramic sleeve provided with a convex portion on the outer peripheral surface has a sleep rear end positioned behind the rear ends of the metal fitting body and the detection element, and the sleeve front end positions the seal material on the front end side. To be compressible,

At a position near the rear end of the metal fitting main body, the seal material is compressed by the sleeve pressing and fixing means for fixing the sleeve in a state where the sleeve is pressed to the front end side via the convex portion of the ceramic sleeve. In a configuration for maintaining a seal between the main body and the detection element,

The sealing material is disposed only on the front end side from the rear ends of the fitting body and the detection element. The ceramic sleeve is coaxially arranged with respect to the detection element, and the end of the sleep thereof is positioned more distal than the rear end of the detection element, and the sealing material is compressed toward the distal end. It is characterized by the following.

In this specification, when referring to the gas sensor or its constituent members (components), the term “front end” or “front” refers to the lower end or lower side of the gas sensor or constituent member in FIG. 1; Refers to the top or top of the component.

According to the present invention described above, the following operations are provided. That is, in the sensor seal structure described in FIGS. 2 and 3 of Patent Document 1, the sealing material is attached to the outer peripheral surface of the part near the rear end of the element and the outer peripheral surface of the terminal member located behind the element. Are arranged in a state of straddling in the axial direction, the amount of the sealing material tends to increase, and the length of the sealing material in the axial direction increases, and as a result, it is difficult to increase the packing density of the sealing material. I got it. On the other hand, in the present invention, the sealing material is disposed only in the annular space between the inner peripheral surface of the metal fitting body (hereinafter, also simply referred to as the main body) and the outer peripheral surface of the element, and is compressed by the sleeve. It has a structure.

In other words, in the present invention, the ceramic sleeve is arranged coaxially with the detection element and the rear end side of the detection element is arranged inside the front end of the ceramic sleeve. That is, the compression is performed. As a result, the length of the sealing material in the axial direction can be made shorter than that of the conventional sensor structure, and the sealing material under the state of receiving the pressing force from the ceramic sleeve has a high density and a high specific gravity. It can be. As a result, it is possible to obtain a gas sensor having better sealing performance than the conventional one.

In addition, in the present invention, since the detection element is disposed inside the front end of the ceramic sleeve on the rear end side, the sleeve for compressing the sealing material is pressed to the front end side. The pressing and fixing means can be provided on the distal end side of the conventional sensor. As a result, even if the dimensions from the rear end of the main body to the rear end of the terminal member are secured as before, the position of the rear end of the main body can be set to the front end side, thereby shortening the sensor. be able to. According to the gas sensor of the present invention, as described above, the axial length of the sealing material can be shortened as compared with the related art, but the axial length is specifically,

It is preferable to set within the range of 1 O mm or less. If it is larger than 10 mm, it is difficult to apply a uniform load to the sealing material when the sealing material is pressed by the tip of the sleeve. The lower limit of the axial length is not particularly limited as long as the sealing performance between the inner peripheral surface of the detection element and the outer peripheral surface of the bracket body can be sufficiently obtained. Performance can be obtained. In this specification, the “length of the seal material in the axial direction” means the length between the end on the front end side and the end on the rear end side of the seal material that comes into contact with the detection element. And the length in the direction parallel to the axial direction of the detection element. Further, in the present invention, the form of the convex portion provided on the outer peripheral surface of the sleeve may be discontinuous in the circumferential direction when viewed from the axial direction, for example, in the form of an external gear. It is preferable that the flange is annular. This is because the sleeve itself can be satisfactorily pressed toward the distal end in the axial direction by using the convex portion formed of the annular flange. The convex portion may be provided on the outer peripheral surface of the sleeve. In the gas sensor according to claim 1, as in the invention according to claim 2, the convex portion has a tip of the ceramic sleep. Or it is good to be provided in the part near the tip. This is because, by doing this, the sleeve pressing and fixing means at the portion near the rear end of the main body can be positioned at the tip of the sensor as much as possible, so that the axial length of the bracket main body can be shortened. This is because the cost of the sensor can be reduced and the sensor can be shortened. The third aspect of the present invention is the gas sensor according to the first or second aspect, wherein the ceramic sleeve surrounds an outer peripheral surface of the terminal member. In this way, by surrounding the outer peripheral surface of the terminal member, in addition to protection of the inside of the sensor, the mounting of the terminal member is stabilized. In addition, a rubber cap that covers the terminal fitting of the connection cord connected to the terminal member is located near the rear end of the sensor. By attaching to the outside, it is easy to attach to the ceramic sleeve if it is attached. Therefore, it is also effective as a measure against heat damage of the rubber cap based on the heat dissipation of ceramic. The range of the surrounding axial direction may be a range that does not hinder the connection of the terminal fittings of the connection cord. As the sleeve pressing and fixing means, as described in claim 5, the sleeve pressing and fixing means is formed by caulking the periphery of a portion near the rear end of the metal fitting body to the rear of the convex portion of the sleeve. It is preferable to use a cover. However, the present invention is not limited to this as long as the sleeve is pressed and fixed to the distal end side via the convex portion of the ceramic sleeve. In addition, as will be described later in detail, for example, under a state in which another metal annular member is placed over the rear portion of the convex portion of the sleeve and pressed toward the distal end, the annular member is connected to the rear end of the fitting body. It may be fixed to the close part by welding or the like. That is, appropriate means can be used. Further, a preferred method for producing the gas sensor of the present invention is as described in claims 6 to 8. According to a sixth aspect of the present invention, in manufacturing the gas sensor according to the fifth aspect, the ceramic sleeve is arranged such that a rear end of the sleeve is located rearward of a rear end of the metal fitting body and the rear end of the detection element, and a sleep front end thereof. After arranging the see-through material to be compressible on the front end side, the ceramic sleeve is pressed to the front end side, and the seal material is compressed to the front end side by the sleep front end, and the sleeve is compressed in the sleeve. A method of manufacturing a gas sensor, characterized in that a peripheral edge of a portion near a rear end of the metal fitting body is swaged inward to cover a rear portion of the convex portion. According to a seventh aspect of the present invention, in manufacturing the gas sensor according to the fifth aspect, the rear end of the sleeve made of the ceramic is positioned behind the rear end of the metal fitting body and the detection element, and the sleeve end is formed by the front end of the sleeve. After arranging the seal material to be compressible on the distal end side, substantially simultaneously with pressing the ceramic sleep to the distal end side and compressing the seal material to the distal end side by the end of the sleeve, A method for manufacturing a gas sensor, wherein a peripheral edge of a portion near a rear end of the metal fitting body is swaged inward on a rear portion of the convex portion in the above. According to claim 8, the terminal member according to claim 6 or 7, after the peripheral edge of a portion near the rear end of the metal fitting body is swaged inward on the rear portion of the convex portion of the sleeve, and A gas sensor, wherein the gas sensor is inserted into the sleep, and inserted into the opening at the rear end of the detection element to be electrically connected to the electrode layer on the inner peripheral surface. As is apparent from the above description, in the gas sensor of the present invention, the axial length of the sealing member can be shorter than that of the conventional sensor structure. For this reason, the sealing material under the pressing force from the ceramic sleeve can be made to have a high density and a high specific gravity. be able to.

In addition, in the gas sensor of the present invention, since the detection element is arranged inside the front end of the ceramic sleeve at the rear end side, a slip for compressing the sealing material is pressed to the front end side. The sleeve pressing and fixing means at the portion near the rear end can be provided on the front end side of the conventional sensor. As a result, even if the dimensions from the rear end of the main body to the rear end of the terminal member are secured as before, the position of the rear end of the main body can be set to the front end side, so the sensor can be shortened. Can be.

Further, according to the method for manufacturing a gas sensor of the present invention, the ceramic sleeve is pressed to the tip side and the sealing material is compressed to the tip side by the sleeve tip, or the sealing material is pressed to the tip side. Approximately at the same time as the compression, the peripheral edge of the metal part body near the rear end is swaged inward to cover the metal part. For this reason, at the time of caulking, the sealing material is compressed, so that a high sealing property is ensured. In the method of manufacturing a gas sensor according to the present invention, the end of the sleeve of the ceramic sleeve may be brought into contact with the sealing material so that the ceramic sleep is pressed toward the end, or the sleeve of the ceramic sleeve may be pressed. Between the sleeve tip and the sealing material An intermediate member (for example, an annular plate member having a constant thickness) may be interposed therebetween to press the ceramic sleeper to the distal end side.

FIG. 1 is a half sectional front view showing an embodiment of a gas sensor of the present invention.

Fig. 2 is an enlarged view of part A (main part) of Fig. 1.

FIG. 3 is a cross-sectional front view showing the in-process product of the gas sensor of FIG. 1 (before assembling the terminal member).

Fig. 4 is a half cross-sectional front view of the state in which the gas sensor of Fig. 1 is attached to the exhaust pipe, and the terminal fitting of the cord with a rubber cap is connected to the terminal member.

FIG. 5 is an enlarged sectional view of a main part showing another example of the sleeve pressing and fixing means in the gas sensor of the present invention.

FIG. 6 is an enlarged sectional view of a main part showing another example of the sleeve pressing and fixing means in the gas sensor of the present invention.

FIG. 7 is an enlarged cross-sectional view of a main part showing another example of a projection on a ceramic sleeve. FIG. 8 is an enlarged cross-sectional view of a main part showing another example of a projection on a ceramic sleeve. FIG. 9 is an enlarged cross-sectional view of a main part in FIG. 2, in which an annular plate member is interposed between a tip end of a ceramic sleeve and a sealing material.

The symbols in the figure are as follows.

1 Gas sensor

2 Bracket body

2 b Rear end of bracket body

7 b Area near the rear end of the rear bracket body

1 5 Detector

1 5 b Rear end of detector

2 1 Sealing material

2 5 Ceramic sleeve

2 6 Tip of ceramic sleeve 2 7 Rear end of ceramic sleeve

2 8 Ceramic sleeve flange (convex)

3 1 Terminal material

H exhaust pipe

An embodiment of a gas sensor according to the present invention will be described in detail with reference to FIGS. In the figure, reference numeral 1 denotes the gas sensor (oxygen sensor) of the present example, and the bracket main body 2 is made of SUS430, and a small diameter is formed in a straight section with a thin circular cross section at the tip side (the lower side in the figure). At the upper end of the small-diameter hole 3, there is provided an inner peripheral step 4 having an upwardly tapering shape, and is located rearward from the rear end (upper end in the figure) of the inner peripheral step 4. Has a straight cylindrical inner peripheral surface 5 with a circular cross section larger in diameter than the small diameter holes 3. The inner peripheral surface behind the rear end of the cylindrical inner peripheral surface 5 is expanded upward from the cylindrical inner peripheral surface 5 via a tapered surface 6 having an enlarged diameter, and is formed into a large-diameter cylinder including a thin-walled cylindrical portion 7. It has a peripheral surface 8. As shown in FIG. 2, the rear end portion 7 b of the thin-walled cylindrical portion 7 is pressed from the cylindrical state coaxial with the sensor axis G by the force P to the tip side by the force P, and is bent inward. At the same time, it was caulked to the tip. The inner peripheral surface of the metal fitting body 2 has an inner peripheral surface that is the same as the axis of the sensor (the same as the axis of the screw 10 described below). It has a stepped cylindrical shape that expands coaxially.

On the other hand, a hexagonal portion 9 for mounting (screw-in) to the exhaust pipe H is provided in an expanded shape outside the portion corresponding to the cylindrical inner peripheral surface 5 and the tapered surface 6 in the metal fitting body 2. . A screw 10 for mounting is provided on the outer periphery of the lower part of the hexagonal portion 9, and a reduced diameter portion 11 whose outer diameter is reduced is provided on a tip side of the mounting screw 10, Here, a plurality of element protection caps 12 having gas circulation holes are fitted and fixed by welding or the like. The thin cylindrical portion 7 described above is connected to the upper portion of the hexagonal portion 9.

In this embodiment, a ring-shaped metal member is provided on the inner peripheral step 4 inside the bracket body 2 from the rear end side. (Made of SUS430) Packing 13 is set in a mounted state. A detection element 15 having a closed end 15a and a cylindrical shape is inserted from above into the metal fitting body 2 coaxially from the front end 15a side. However, the detecting element 15 is provided with an outer peripheral convex portion (flange) 16 provided so as to protrude outward on the outer peripheral surface slightly above the intermediate position, and the outer peripheral convex portion (flange) 16 is provided. However, it is positioned in a dead end shape on the inner peripheral step portion 4 inside the metal fitting body 2 via the metal packing 13. In this embodiment, the electrode layer (not shown) is formed on the outer peripheral surface on the distal end side of the element 15. The electrode layer (not shown) extends to the outer peripheral convex portion 16, and the metal fitting 13 is provided via a metal packing 13. It is electrically connected to the main unit 2. In addition, the outer peripheral convex portion 16 is formed such that the side on the tip end side corresponds to the taper angle of the inner peripheral step portion 4, and the outer diameter is set so as to fit within the cylindrical inner peripheral surface 5. ing. The width in the vertical direction (axis G) of the outer peripheral convex portion 16 is set to be smaller than the dimension in the vertical direction of the cylindrical inner peripheral surface 5. In addition, from the outer peripheral convex portion 16, the outer peripheral surface on the front end side is formed into a tapered shape with a gentle taper, and the outer peripheral surface on the rear end side is formed in a substantially straight shape. However, the inner and outer peripheral surfaces near the opening at the rear end 15b are chamfered.

By the way, above the outer peripheral convex portion 16 of the element 15 and between the outer peripheral surface 15 c of the element 15 and the cylindrical inner peripheral surface 5 of the main body 2, a metal (N i) wire Packing of 18 is arranged. Then, in the annular space formed by the inside of the enlarged-diameter cylindrical inner peripheral surface 8 which is the inner peripheral surface of the tapered surface 6 of the metal fitting body 2 and the thin cylindrical portion 7 and the outer peripheral surface 15 c of the element 15. In this embodiment, a sealing material 21 made of talc powder (or hexagonal boron nitride powder) is arranged (compressed and filled) in this embodiment. However, the sealing member 21 is arranged such that the rear end thereof is located closer to the front end side than the rear ends of the element 15 and the main body 2, and has a substantially wedge-shaped cross section in the present embodiment.

On the rear end side of such a sealing material 21, a ceramic sleeve 25 made of alumina or the like and formed in a substantially cylindrical shape and having an insulating property is arranged and fixed as follows. That is, the ceramic sleeve 25 has its tip 26 closer to the rear end 15 b of the element 15, the outer peripheral surface 15 c closer to the b, and the main body 2 thin inner cylindrical portion 7 inner peripheral surface 8. Between them, they are arranged coaxially with the element 15. And the tip 2 At 6, the sealing material 21 is compressed to the tip side, and the seal between the metal fitting body 2 and the element 15 is maintained. However, the sleeve 25 is provided with a convex flange 28 on the outer peripheral surface of the distal end 26 in the circumferential direction, and is fixed with the sleeve 25 pressed to the distal end side via the flange 28. The seal material 21 is compressed by the sleep pressing and fixing means to hold the seal between the metal fitting body 2 and the detection element 15. In the present embodiment, an O-ring packing 30 made of metal (SUS430) wire is arranged on the rear portion (the surface facing the rear end) 28 b of the flange 28, and in that state, as described above, The sleeve is pressed to the front end side by crimping and covering the periphery of the rear end portion 7b of the cylindrical portion 7 inside. At this stage, the in-process product shown on the left side of Fig. 3 is presented.

Before the peripheral edge of the portion 7b near the rear end of the thin-walled cylindrical portion 7 is swaged inward, a predetermined load (for example, as indicated by an arrow K in FIG. 3) It is preferable to press the ceramic sleeve 25 to the distal end side at 10 to 30 kN) to compress the sealing material 21 to the distal end side by the sleep distal end 26. In other words, under such a compressed state, the die D is pushed toward the front end, and the periphery of the part 7 b near the rear end of the metal fitting body 2 is added to the rear of the convex part 28 of the sleep 25. It is preferable to tighten and cover. This is because the sealing material 21 can be sufficiently compressed separately from the force-shrinkage, so that a higher sealing property is ensured. However, at the same time as compressing the sealing material 21 to the front end side, the peripheral edge of the part 7 b near the rear end of the bracket body 2 should be swaged inward to cover the rear part of the convex part 28 in the sleep 25. It may be.

On the other hand, such a ceramic sleeve 25 of the present embodiment has a flange 29 slightly projecting inward on the inner peripheral surface on the rear end 27 side, and inside this terminal member 3 1 for output. Is formed to be interpolated. In addition, the inner and outer peripheral surfaces of the sleep 25 have the same diameter (straight) except for the flanges 28 and 29, and in this embodiment, at least half of the rear end portion is the element 15 and the element 15. It protrudes rearward from the rear end of the bracket body 2 and is exposed to the outside. As described above, in the gas sensor 1 of the present embodiment, as shown in FIG. The ceramic sleeve 25 also functions as a protective cylinder for mechanically protecting the element 15 from the outside.

Then, the terminal member 31 formed into a tapered stepped cylindrical shape is attached to the in-process sensor shown in Fig. 3 by the ceramic sleeve 25 from the side of the internal connection terminal 33 on the tip side. The sensor shown in Figs. 1 and 4 is assembled by pressing the element 15 into the opening near the rear end 15b of the element 15 through the inside. The internal connection terminal 33 of the terminal member 31 is pressed into contact with an electrode layer (not shown) formed on the inner peripheral surface 15 d of the element 15 by its own panel property, and is electrically connected (conductive). ) Is held. As shown in FIG. 4, the axial length L 1 from the rear end 2 b of the main body 2 to the rear end 3 1 b of the terminal member 3 1 in the sensor 1 assembled in this manner is equal to the connection cord 40. When the constituent terminal fittings 43 are fitted and connected to the terminal members 31, the rubber cap 45 covering the terminal fittings 43 of the connecting cords 40 causes heat damage to the exhaust pipe. The length is set so that the necessary axial length S is held between the rear end 2 b of the main body 2 and the rubber cap 45 of the connection cord 40 so as not to be received.

In the above-described assembling, the terminal member 31 is inserted in advance into the opening of the rear end 15 b of the detection element 15 and electrically connected to the electrode layer on the inner peripheral surface thereof. 5 can be set, and the peripheral edge of the portion 7b near the rear end of the metal fitting body 2 can be swaged inward to cover. However, as described above, after the sleeve 25 is set and the peripheral edge of the portion 7b near the rear end of the bracket main body 2 is crimped inward, the terminal member 31 is inserted into the sleeve 25 from the front end side. When it is inserted into the opening of the rear end 15b of the detection element 15 and electrically connected to the electrode layer on the inner peripheral surface thereof, assembly becomes easy. That is, when the ceramic sleep 25 is set after the terminal member 31 is inserted into the detection element 15 in advance, the ceramic sleep 25 is set due to the inclination of the terminal member 31. It may interfere with the terminal member 31 or collide, making it difficult to set. However, when the terminal member 31 is inserted later, such a problem can be easily avoided.

In the present embodiment, the terminal member 31 has a small-diameter insertion guide portion 32, a portion of the internal connection terminal 33, an intermediate cylindrical portion 34, and a portion extending from the front end 31a to the rear end 31b. , It is formed by rolling a metal sheet made of SUS304 so as to form an external connection terminal 36 near the rear end via the constricted portion 35, and one side is cut along the axis. (See the figure on the right in Figure 3). However, the cut in the internal connection terminal 33 is formed unevenly in the axial direction, and when the device is set on the element 15, the internal connection terminal 33 has a portion formed on the inner peripheral surface 15 of the element 15 due to the panel characteristics. It is formed so as to be pressed against the electrode layer d. The rear end of the outer peripheral surface forming the external connection terminal 36 is formed in a chamfered shape, and is formed so as to be easily covered with the terminal fitting 43 constituting the connection cord 40. The connection cord 40 includes a terminal fitting 43, a rubber cap 45 covering the terminal fitting 43 (for example, formed of fluorine-based rubber), a lead wire 41, and a terminal fitting 43 at one end. And a crimping terminal 42 that is electrically connected to the other end while being crimped to the lead wire 41. Of these, the terminal fittings 4 3 have rigidity to reduce the diameter of the external connection terminal 36 of the terminal member 31 without being deformed when the terminal fittings 4 3 are fitted and connected to the outside of the terminal member 31. It is formed from a material (eg, Inconel 178). By attaching such a connection cord 40 to the gas sensor 1, an output signal from the detection element 15 of the gas sensor 1 can be transmitted to an external device (for example, an ECU) through the lead wire 41.

The connection cord 40 shown in FIG. 4 includes a rubber cap 45 having an L-shaped cross section as shown in FIG. 4 so as to cover the terminal fitting 43 when it is attached to the sensor 1. The inside of the rubber cap 45 near the opening is formed so as to be elastically fitted to the sleeve 25. Reference numeral 38 in the terminal member 31 is a stopper for preventing excessive insertion of the element 15, and is formed so as to protrude outward so as to be locked to the rear end 27 of the sleep 25. Then, 3 9 in the figure denotes a retaining after insertion of the terminal member, at the time揷入narrowed down by the spring resistance at an inner circumferential surface of the flange 2 9 of the rear end ² 7 ceramic Sleep 2 5 After passing through the flange 29, the flange 29 is opened at the tip of the flange 29 by a panel, and is formed in a tongue-like shape extending upward and in a notch shape in the intermediate cylindrical portion 34.

As shown in FIG. 4, such a sensor 1 is attached to the exhaust pipe H via a washer W by a screwing method. Then, to the external connection terminal 36 of the terminal member 31, By covering the terminal fittings 43 of the connection cord 40, conduction between them is maintained and used as a sensor. On the other hand, in the sensor 1 according to the present embodiment, the ceramic sleeve 25 is assembled coaxially so that the portion near the front end of the ceramic sleeve 25 overlaps the outer peripheral surface 15 c near the rear end 15 b near the element 15. ing. That is, the sealing material 21 exists only around the outer peripheral surface of the element 15 inside the main body ² and is not disposed so as to straddle the element and the terminal member in the axial direction as in the related art. The length L 3 in the axial direction of the sealing material 21 can be reduced. Therefore, the packing density of the sealing material 21 in a state of being compressed and filled by the pressing force of the sleeve 25 can be increased, and the gas sensor 1 having excellent sealing performance as compared with the conventional sensor structure can be obtained. be able to. In the present embodiment, the length L3 of the sealing material is 4 mm.

In addition, the position where the flange 28 of the sleeve 25 is formed is set on the outer peripheral surface of the distal end 26 while reducing the axial arrangement area of the sealing material 21, so that the position of the rear end 2 b of the main body 2 is Since it can be set at the tip side of 5, the sensor can be made shorter and, consequently, more compact. In addition, since the length is reduced, the length L2 from the exhaust pipe to the rear end of the sensor when the sensor 1 is mounted on the exhaust pipe H can be reduced, so that the mounting space can be reduced.

Further, in this embodiment, the rubber cap 45 of the connection cord 40 is elastically fitted (contacted) to the outer peripheral surface of the ceramic sleep 25 while maintaining the axial length S. . For this reason, heat damage to the rubber cap 45 can be reduced, the mounting of the cap can be stabilized, and the effect of preventing water and oil from entering the inside of the sensor can be kept high.

Note that, in the above embodiment, as a sleeve pressing and fixing means, a case where the flange (convex portion) 28 of the sleeve 25 is pressed to the front end side by caulking at a position near the rear end of the main body 2 is illustrated in FIG. It can also be embodied as shown. FIG. 5 shows another example of the slip pressing and fixing means. Only the differences from the above-described embodiment will be described, and the same portions will be denoted by the same reference numerals. The same applies to the following. That is, a ring 51 having an L-shaped cross section as shown in the figure is externally fitted to the outer peripheral surface of the portion 7 b near the rear end of the main body 2 through the vertical cylindrical portion 52, and the flat ring portion 53. O-ring packing It is arranged so that 30 is pressed. Then, the sleep is pressed to the distal end side as shown by the arrow P through the ring 51 to compress the sealing material 21, and under this state, the inner peripheral surface of the vertical cylindrical portion 52 and the main body 2 are compressed. The sleeve 25 is fixed to the main body 2 by welding between the rear end portion 7b and the outer peripheral surface of the portion 7b.

Further, as shown in FIG. 6, a screw 7 c is provided on an outer peripheral surface of a portion 7 b near the rear end of the main body 2, and a vertical cylindrical portion 6 2 of a ring 61 having an L-shaped cross section as shown in the figure is provided. A female screw is provided on the inner peripheral surface of the main body 2, and this is screwed into the screw 7 c of the main body 2, so that the O-ring packing 30 is inserted through the flat ring portion 63 protruding inside the upper end of the vertical cylindrical portion 62. By pressing, the sleep 25 may be compressed to the distal end side. Further, in the above-described embodiment, the convex portion of the ceramic sleeve 25 is an annular flange, but is not limited to this. Further, in the above-described embodiment, the protruding portion of the ceramic sleeve 25 is provided at the front end, but this position is, as shown in FIG. 7, for example, a position closer to the rear end than the front end 26 of the sleeve 25. It may be as. In FIG. 7, the sealing material is arranged so as to compress the sealing material 21 even at the tip end surface 28 a of the projection 28.

In FIG. 7, the sealing material 21 is also compressed at the distal end surface 28 a of the flange (convex portion) 28, but such a convex portion is not responsible for the compression of the sealing material. Is also good. FIG. 8 shows an example of this, in which the inner diameter of the tapered surface 6 near the tapered surface 6 of the inner peripheral surface 8 in the above-described embodiment is reduced, and the outer diameter of the sealing material 21 is reduced. . In FIG. 8, the sealing material 21 is compressed only at the tip 26 of the sleeve except for the flange (convex portion) 28 near the tip of the sleeve 25. As can be understood from this, the position of the protrusion 28 in the direction of the axis G may be any position from the viewpoint of reducing the amount of sealing material used. However, the rear end of the main unit is located more rearward as the position is closer to the rear end. The same applies to the case where the thickness of the projection 28 in the direction of the axis G is large.

Further, in each of the above-described embodiments, the structure in which the tip 26 of the sleeve 25 directly compresses the sealing material 21 has been exemplified. However, as shown in FIG. Constant thickness between the front end 26 of the seal material and the rear end (rear end face) 22 of the sealing material 21 An annular plate member 71 made of mica, SUS430 or the like may be interposed and compressed. When such an annular plate member 71 is interposed, the following effects are obtained. That is, when the gap between the inner peripheral surface of the sleeve 25 and the outer peripheral surface 15 c of the detection element 15 is set small, the detection element 15 is attached to the fitting body when the sleep 25 is placed (set). If the element 15 is eccentric with respect to the axis 2, the element 15 may be damaged due to excessive stress applied thereto and the element 15 being cracked. In order to prevent such damage, it is necessary to provide a certain gap between the outer peripheral surface of the element 15 and the inner peripheral surface of the sleeve 25. On the other hand, as such a gap becomes larger, there is a possibility that problems such as protrusion or leakage of the sealing material 21 from the gap may be caused. However, as shown in FIG. 9, when an annular plate member 71 is interposed between the front end 26 of the sleeve 25 and the rear end 22 of the seal member 21, the annular plate member By making the gap between the inner peripheral surface of 71 and the outer peripheral surface of element 15 small, the occurrence of such a problem can be prevented. In other words, as shown in FIG. 9, in the case where the annular plate member 71 is interposed, the gap between the outer peripheral surface of the element 15 and the inner peripheral surface of the sleeve 25 must be increased. This also has the effect of preventing the sealing material from protruding from the gap.

Further, in the above-described embodiment, the ceramic sleeve is configured to protrude from the rear end of the terminal member near the rear end thereof and surround the outer peripheral surface of the terminal member. However, the present invention is not limited to this. In other words, the length of the sleeve may be set appropriately, and the terminal member may be connected to the terminal of the cord for connection thereto.Therefore, the terminal member is not necessarily made of the ceramic sleeve. It does not need to protrude from the rear end.

Also, the ceramic sleeve is embodied as having the same diameter (straight) except for the protruding portion on the outer peripheral surface, but may be tapered. In particular, when the tapered end is formed with a gentle taper toward the rear end (upper end in the figure), the rubber cap of the terminal fitting of the cord is tapered to ensure stable fixation. .

Furthermore, as for the terminal member, the metal sheet is rolled into a cylindrical shape with ends in the circumferential direction. Although it was formed, it may be formed of a tubular material that is endless in the circumferential direction. The ceramic sleeve in the present invention is not limited to alumina as long as it has insulating properties. Also, the sealing material is not limited to talc or hexagonal boron nitride powder. Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention.

This application is based on a Japanese patent application filed on May 29, 2003 (Japanese Patent Application No. 2003-151795), the contents of which are incorporated herein by reference.

Claims

The scope of the claims

1. A detection element having a cylindrical shape with a closed end and having an electrode layer on the inner and outer peripheral surfaces is positioned in a metal fitting body formed so as to surround the outer peripheral surface, and the electrode layer on the outer peripheral surface is positioned. Electrically connected to the bracket body,

A gas sensor comprising a terminal member inwardly opened from a front end side of an opening at a rear end of the detection element and electrically connected to an electrode layer on the inner peripheral surface,

A cylindrical ceramic sleeve provided with a convex portion on the outer peripheral surface has a rear end of the sleeve positioned rearward of a rear end of the metal fitting body and the detection element, and a tip end of the sleeve causes the sealing material to move forward. To be compressible,

The sealing material is disposed only on the distal end side from the rear ends of the metal fitting body and the detection element, and the ceramic sleeve is coaxially arranged with respect to the detection element and the leading end of the sleeve is disposed behind the detection element. A gas sensor characterized in that the seal member is located closer to the distal end than the end and compresses the sealing material toward the distal end.

2. The gas sensor according to claim 1, wherein the protrusion is provided at a tip or a portion near the tip of the ceramic sleeve.

3. The gas sensor according to claim 1, wherein the ceramic sleep surrounds an outer peripheral surface of the terminal member.

4. The outer periphery of the detection element extending along the inner peripheral surface of the bracket main body and the axial direction The axial length of the sealing material disposed between the surface and the surface is 2 mn! The gas sensor according to any one of claims 1 to 3, wherein the gas sensor is within a range of 1 to 1 Omm.

5. The sleeve pressing and fixing means is formed by crimping a peripheral edge of a portion near a rear end of the metal fitting body on an inner side of a rear portion of the convex portion of the sleeve. The gas sensor according to any one of 1 to 4.

6. In manufacturing the gas sensor according to claim 5, the ceramic sleeve is positioned such that a rear end of the sleeve is located rearward of a rear end of the metal fitting body and the rear end of the detection element. After being arranged to be compressible on the distal end side, the ceramic sleeve is pressed to the distal end side and the sealing material is compressed to the distal end side by the sleep distal end. A method for manufacturing a gas sensor, wherein a peripheral edge of a portion near a rear end of the metal fitting body is swaged inward to cover the metal body.

7. In manufacturing the gas sensor according to claim 5, the ceramic sleeve is arranged such that a rear end of the sleeve is positioned rearward of a rear end of the metal fitting body and the rear end of the detection element, and the sealing material is formed by a front end of the sleeve. At the same time that the ceramic sleeve is pressed to the distal end side and the sealing material is compressed to the distal end side by the distal end of the sleeve, almost simultaneously with the rear end of the convex portion in the sleep, after the ceramic sleeve is compressed to the distal end side. A method for manufacturing a gas sensor, wherein a peripheral edge of a portion near a rear end of the metal fitting body is swaged inward to cover the metal body.

8. The terminal member according to claim 6 or 7, wherein, after a peripheral portion of a portion closer to a rear end of the fitting body is crimped inward on a rear portion of the convex portion of the sleeve, the terminal member is placed on the sleeve from the front end side. A method of manufacturing the gas sensor, wherein the gas sensor is inserted into the inside of the sensor element, and is inserted into an opening at a rear end of the detection element to be electrically connected to the electrode layer on the inner peripheral surface.