JP5268193B2 - Gas sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas sensor capable of preventing entry of water to the inside (such as a terminal member, a gas detecting element) of the gas sensor from the outside, through a gap between the surface of an insertion hole of an elastic sealing member and the outer circumferential surface of a lead wire. <P>SOLUTION: The insertion hole surface 192 of an insulating member 190 includes a sealing-side surface (tapered surface 192b) facing the side of the elastic sealing member 115. The elastic sealing member 115 is provided with an insertion part 115d to be inserted in a through-hole 191 of the insulating member 190 and the insertion part 115d has a tip-side insertion hole surface 115f, positioned on the tip side in an axial direction in the insertion-hole surface 115b. The insertion part 115d is pressed against the sealing-side surface (tapered surface 192b) of the insulating member 190 and is elastically deformed so as to reduce the diameter of a tip-side insertion hole 115g, constituted of the tip-side insertion-hole surface 115f in an insertion hole 115c so as to make water tight the section between the tip-side insertion-hole surface 115f and the outer circumferential surface 116b of the lead wire 116. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a gas sensor.

  As a gas sensor, for example, a gas sensor that is attached to an exhaust pipe of an automobile and detects NOx concentration or oxygen concentration in the exhaust gas is known (for example, see Patent Document 1).

  The gas sensor disclosed in Patent Document 1 is a gas detection element extending in the axial direction, the gas detection element having the axial front end exposed to the gas to be measured, and a cylindrical casing member (externally extending in the axial direction and surrounding the gas detection element) Tube), a terminal member electrically connected to the gas detection element, and a lead wire electrically connected to the terminal member. Further, the gas sensor has an insertion hole surface through which a lead wire is inserted and forms an insertion hole extending in the axial direction, and the radial direction of the rear end opening portion located at the rear end in the axial direction of the casing member An insulating seal member disposed on the inner side, and an insulating member that is located on the axial front end side relative to the elastic seal member and is accommodated in the casing member, and having a through hole in which the terminal member is disposed. And. The lead wire extends to the outside of the gas sensor through the insertion hole of the elastic seal member.

JP 2009-47574 A

  In the gas sensor disclosed in Patent Document 1, the elastic seal member is pressed by a caulking portion that caulks the rear end opening of the casing member inward in the radial direction, and is elastically deformed so that the diameter of the insertion hole is reduced. Accordingly, the space between the insertion hole surface of the elastic seal member and the outer peripheral surface of the lead wire is watertight at a position on the radially inner side of the crimped portion. In this way, the problem that water enters the gas sensor (terminal member, gas detection element, etc.) from the outside through the gap between the insertion hole surface of the elastic seal member and the outer peripheral surface of the lead wire has been prevented. .

  However, in recent years, further improvement in waterproofness has been demanded for gas sensors. Specifically, water can be further prevented from entering the inside of the gas sensor (terminal member, gas detection element, etc.) from the outside through a gap between the insertion hole surface of the elastic seal member and the outer peripheral surface of the lead wire. There was a need for a gas sensor.

  The present invention has been made in view of the present situation, and from the outside to the inside of the gas sensor (terminal member, gas detection element, etc.) through the gap between the insertion hole surface of the elastic seal member and the outer peripheral surface of the lead wire. An object of the present invention is to provide a gas sensor that can further prevent water from entering.

One aspect of the present invention is a gas detection element extending in the axial direction, wherein the gas detection element whose tip end in the axial direction is exposed to a gas to be measured, a terminal member electrically connected to the gas detection element, and the terminal A lead wire electrically connected to the member, a cylindrical casing member extending in the axial direction and surrounding the gas detection element, the terminal member, and the lead wire, and an insertion hole through which the lead wire is inserted. An elastic seal member having an insertion hole surface that constitutes an insertion hole extending in the axial direction and disposed radially inside a rear end opening located at an axial rear end of the casing member, The rear end opening is elastically deformed so that the insertion hole is reduced in diameter by being pressed by a caulking part that is caulked radially inward, and the insertion hole surface is positioned at a position radially inward of the caulking part. Outer circumference of the lead wire An elastic seal member that is watertight between the elastic seal member and an insulating member that is positioned closer to the distal end side in the axial direction than the elastic seal member and is housed inside the casing member, the terminal member being disposed therein An insulating member having a through-hole surface constituting a through-hole, wherein the lead wire extends outside the gas sensor through the insertion hole of the elastic seal member. The through hole surface of the member includes a seal side surface facing the elastic seal member side, and the elastic seal member protrudes from the front end surface thereof toward the front end side and is inserted into the through hole of the insulating member. An insertion portion having a distal end side insertion hole surface located on the distal end side in the axial direction of the insertion hole surface. The distal end side insertion hole constituted by the distal end side insertion hole surface of the insertion hole is elastically deformed so that the diameter thereof is reduced, and the outer peripheral surface of the distal end side insertion hole surface and the lead wire Is a gas sensor that is watertight.

  In the gas sensor described above, as in the gas sensor disclosed in Patent Document 1, the elastic seal member is inserted into the insertion hole surface and the lead at the radially inner position of the crimped portion where the rear end opening of the casing member is crimped radially inward. The space between the outer periphery of the wire is watertight.

  Furthermore, in the gas sensor described above, the through hole surface of the insulating member includes a seal side surface facing the elastic seal member side. Further, in the gas sensor described above, the elastic seal member is an insertion portion that is inserted into the through hole of the insulating member, and has a distal end side insertion hole surface that is located on the distal end side in the axial direction among the insertion hole surfaces extending in the axial direction. The insertion part which has. The insertion portion is pressed against the seal side surface of the insulating member and elastically deforms so that the distal end side insertion hole constituted by the distal end side insertion hole surface of the insertion hole has a reduced diameter, and the distal end side insertion hole surface and the lead The space between the outer periphery of the wire is watertight.

  Thus, in the gas sensor described above, the elastic seal member is watertight between the insertion hole surface and the outer peripheral surface of the lead wire in the through hole of the insulating member in addition to the position on the radially inner side of the crimped portion. I have to. Therefore, compared with the conventional gas sensor, the above-described gas sensor allows water to flow from the outside to the inside of the gas sensor (terminal member, gas detection element, etc.) through the gap between the insertion hole surface of the elastic seal member and the outer peripheral surface of the lead wire. It is possible to further prevent entry.

  Furthermore, in the above gas sensor, the hole extends from the rear end surface of the insulating member (the surface forming the end surface on the elastic seal member side of the insulating member) to the front end side in the axial direction. It is preferable that the gas sensor includes a tapered surface that forms a tapered hole with a diameter decreasing toward the distal end side in the axial direction as the seal side surface.

  In the gas sensor described above, the through-hole surface of the insulating member is a hole extending from the rear end surface of the insulating member to the axial front end side as a seal side surface, and is tapered such that the diameter decreases from the rear end surface toward the axial front end side. It includes a tapered surface that forms a hole (for example, a truncated cone shape).

  In the assembly process of the gas sensor having such a configuration, in a state where the elastic seal member is disposed radially inside the rear end opening of the casing member, when the rear end opening is crimped radially inward, the elastic seal member is It is compressed radially inward and extends in the axial direction. At this time, the insertion portion of the elastic seal member is strongly pressed against the tapered surface of the insulating member, and due to the reaction force, the distal end side insertion hole is elastically deformed so that its diameter is reduced. Thereby, the front end side insertion hole surface and the outer peripheral surface of the lead wire can be brought into close contact with each other, and the space between the front end side insertion hole surface and the outer peripheral surface of the lead wire can be made watertight.

  Further, when the gas sensor is attached to an exhaust pipe or the like and used in a high temperature environment, the elastic seal member expands thermally. Since the elastic seal member tends to extend in the axial direction due to thermal expansion, the insertion portion of the elastic seal member is strongly pressed against the tapered surface. Thereby, in the insertion part of the elastic seal member, a force acts in the direction of further reducing the diameter of the distal end side insertion hole, so that the distal end side insertion hole surface and the outer peripheral surface of the lead wire can be more closely adhered.

  As described above, in the gas sensor described above, water can be further prevented from entering the gas sensor from the outside through the gap between the insertion hole surface of the elastic seal member and the outer peripheral surface of the lead wire.

  In addition, when the through-hole surface of an insulating member has only one seal | sticker side surface, a seal | sticker side surface is a taper surface. On the other hand, when there are a plurality of seal side surfaces (for example, when the seal side surface also has an annular surface described later in addition to the taper surface), one of the plurality of seal side surfaces is a taper surface.

  Further, the gas sensor according to any one of the above, wherein the gas sensor is located closer to the distal end side in the axial direction than a rear end surface of the insulating member (a surface forming an end surface on the elastic seal member side of the insulating member), and is on the elastic seal member side A first hole portion extending from the rear end surface to the annular surface of the through hole, and a second hole extending from the annular surface of the through hole toward the front end in the axial direction. It is preferable that the gas sensor includes an annular surface that forms a step with the portion as the seal side surface.

  In the gas sensor described above, the through-hole surface of the insulating member includes an annular annular surface that is positioned closer to the distal end side in the axial direction than the rear end surface of the insulating member as a seal side surface and faces the elastic seal member side. The annular surface forms a step between a first hole portion extending from the rear end surface to the annular surface of the through hole and a second hole portion extending from the annular surface to the axial front end side of the through hole. Is.

  In the assembly process of the gas sensor having such a configuration, in a state where the elastic seal member is disposed radially inside the rear end opening of the casing member, when the rear end opening is crimped radially inward, the elastic seal member is It is compressed radially inward and extends in the axial direction. At this time, the insertion portion of the elastic seal member extending in the axial direction is pressed against the annular surface of the insulating member to be compressed and elastically deformed so that the distal end side insertion hole is reduced in diameter in the first hole portion ( (Thickness increases). Thereby, the front end side insertion hole surface and the outer peripheral surface of the lead wire can be brought into close contact with each other, and the space between the front end side insertion hole surface and the outer peripheral surface of the lead wire can be made watertight.

  Further, when the gas sensor is attached to an exhaust pipe or the like and used in a high temperature environment, the elastic seal member expands thermally. Since the elastic seal member tends to extend in the axial direction due to thermal expansion, the insertion portion of the elastic seal member is strongly pressed against the annular surface. Thereby, in the insertion part of the elastic seal member, a force acts in the direction of further reducing the diameter of the distal end side insertion hole, so that the distal end side insertion hole surface and the outer peripheral surface of the lead wire can be more closely adhered.

  As described above, in the gas sensor described above, water can be further prevented from entering the gas sensor from the outside through the gap between the insertion hole surface of the elastic seal member and the outer peripheral surface of the lead wire.

  In addition, when the through-hole surface of an insulating member has only one seal | sticker side surface, a seal | sticker side surface is an annular surface. On the other hand, when there are a plurality of seal side surfaces (for example, when the seal side surface has the above-described tapered surface in addition to the annular surface), one of the plurality of seal side surfaces is an annular surface.

  The gas sensor according to any one of the above, wherein a gap is provided between a rear end surface of the insulating member (a surface forming an end surface on the elastic seal member side of the insulating member) and the elastic seal member. And good.

  As described above, when the gas sensor is attached to an exhaust pipe or the like and used in a high temperature environment, the elastic seal member thermally expands. For this reason, in the case of a gas sensor in which the elastic seal member is in contact with the entire rear end surface of the insulating member (there is no gap between the rear end surface of the insulating member and the elastic seal member), the elastic seal member that thermally expands is in the axial direction. Since it cannot extend to the front end side, it extends to the rear end side in the axial direction and jumps out of the gas sensor. Moreover, the portion of the elastic seal member that protrudes to the outside of the gas sensor does not tend to return to the inside of the gas sensor even if it is cooled thereafter. For this reason, the volume of the elastic seal member which jumps out of the gas sensor tends to increase as the elastic seal member repeats thermal expansion. Along with this, the volume of the elastic seal member located on the radially inner side of the caulking portion of the casing member is reduced, and the watertightness between the insertion hole surface and the outer peripheral surface of the lead wire may be lowered.

In contrast, in the gas sensor described above, a gap is provided between the rear end surface of the insulating member and the elastic seal member. For this reason, when the elastic seal member is thermally expanded, the elastic seal member can extend toward the front end side in the axial direction within the gap. Thereby, since the volume of the elastic seal member which jumps out of the gas sensor with thermal expansion can be reduced, the volume reduction of the elastic seal member located on the radially inner side of the caulking portion of the casing member can be suppressed. . Therefore, in the above-described gas sensor, it is possible to suppress a decrease in water tightness between the insertion hole surface and the outer peripheral surface of the lead wire at a radially inner position of the caulking portion of the casing member.
Furthermore, in any one of the gas sensors described above, there are a plurality of lead wires, the insulating member has the same number of through holes as the lead wires, and the elastic seal member is equal to the through holes. A plurality of the insertion portions, and each of the insertion portions is inserted into the through hole of the insulating member and pressed against the side surface of the seal, and elastically deformed so that the distal end side insertion hole is reduced in diameter. And it is good to set it as the gas sensor which makes watertight between the said front end side insertion hole surface and the outer peripheral surface of the said lead wire.

1 is a longitudinal sectional view of a gas sensor according to Example 1. FIG. It is a perspective view of a gas detection element. It is the B section enlarged view of FIG. It is the D section enlarged view of FIG. It is a longitudinal cross-sectional view of the gas sensor concerning Example 2. FIG. It is the C section enlarged view of FIG. It is the E section enlarged view of FIG. It is a longitudinal cross-sectional enlarged view of the conventional gas sensor.

Example 1
Next, Example 1 of the present invention will be described with reference to the drawings.
FIG. 1 is a vertical cross-sectional view (cross-sectional view cut in the direction of the axis AX) of the gas sensor 100 according to the first embodiment. The gas sensor 100 incorporates a gas detection element 120 capable of detecting a specific gas (NOx) in exhaust gas to be measured, and is used by being mounted on an exhaust pipe of an internal combustion engine. The axis AX is an axis of the gas sensor 100 and is an axis common to the gas detection element 120, the metal shell 101, the outer cylinder 114, the elastic seal member 115, and the insulating member 190.

  The gas sensor 100 has a cylindrical metal shell 101 in which a screw portion 101n for fixing to an exhaust pipe is formed at a predetermined position on the outer surface, and a plate shape that is held inside the metal shell 101 and extends in the axis AX direction. And a gas detection element 120 formed. Further, the gas sensor 100 includes a holding member 140 having an insertion hole 140c into which the rear end portion 120k (the upper end portion in FIG. 1) of the gas detection element 120 is inserted, and six holding members 140 held inside the holding member 140. A terminal member. In FIG. 1, only two of the six terminal members (specifically, the first terminal member 170b and the second terminal member 180b) are illustrated.

  As shown in FIG. 2, the gas detection element 120 includes an element part 121 formed in a plate shape extending in the axis AX direction (left-right direction in FIG. 2) and a heater part 122 formed in a plate shape extending in the axis AX direction. Are integrally formed. The gas detection element 120 has a front end portion 120s (left end portion in FIG. 2) that detects a specific gas (measured gas), and is located at a predetermined position on the rear end portion 120k (right end portion in FIG. 2). A total of six electrode terminal portions having a rectangular shape in plan view are formed. Specifically, the first electrode terminal portions 123, 124, 125 are formed at predetermined positions on the first plate surface 120a of the gas detection element 120, and the second electrode terminal portions 127, 127, are formed at predetermined positions on the second plate surface 120b. 128 and 129 are formed.

  The inside of the gas detection element 120 has a known structure. That is, the element unit 121 includes an oxygen concentration battery cell in which a porous electrode is formed on both sides of a solid electrolyte substrate, an oxygen pump cell in which a porous electrode is formed on both sides of the solid electrolyte substrate, and a porous material on a solid electrolyte plate. The NOx detection cell in which an electrode is formed and a spacer for forming a measurement gas chamber are configured. The solid electrolyte substrate is made of zirconia in which yttria is dissolved as a stabilizer, the porous electrode is mainly made of Pt, and the spacer is mainly made of alumina. Inside the measurement gas chamber, one porous electrode of the oxygen concentration battery cell, one porous electrode of the oxygen pump cell, and one porous electrode of the NOx detection cell are disposed so as to be exposed. This measurement gas chamber is formed at a predetermined position of the tip portion 120s of the element portion 121, and this portion corresponds to a detection portion. The heater 122 is formed by sandwiching a heating resistor pattern mainly composed of Pt between insulating substrates mainly composed of alumina.

  Of the first electrode terminal portions 123, 124, and 125 and the second electrode terminal portions 127, 128, and 129, four are porous electrodes (oxygen concentration battery cell, oxygen pump cell, NOx provided in the element portion 121). The remaining two are electrically connected to both ends of the heating resistor pattern provided in the heater section 122, respectively.

  The first electrode terminal portions 123, 124, and 125 and the second electrode terminal portions 127, 128, and 129 are electrically connected by elastic contact with the above-described terminal members, respectively (see FIG. 1). Specifically, the element contact portion located on the tip side of each terminal member is elastically applied to one of the first electrode terminal portions 123, 124, 125 and the second electrode terminal portions 127, 128, 129. Touch. For example, the first element contact portion 173b of the first terminal member 170b is elastically contacted and electrically connected to the first electrode terminal portion 124. In addition, the second element contact portion 183b of the second terminal member 180b is elastically contacted and electrically connected to the second electrode terminal portion 128 (see FIG. 1).

  Furthermore, different lead wires 116 are electrically connected to the six terminal members (first terminal member 170b, second terminal member 180b, etc.), respectively. Specifically, the lead wire 116 is electrically connected to the terminal member by gripping the core wire of the lead wire 116 by the lead wire gripping portion located at the rear end of the terminal member. For example, as shown in FIG. 1, the lead wire 116 is electrically connected to the first terminal member 170b by the core wire of the lead wire 116 being held by the first lead wire holding portion 177b of the first terminal member 170b. Is done. Further, the second lead wire gripping portion 187b of the second terminal member 180b grips the core wire of the other lead wire 116, so that the other lead wire 116 is electrically connected to the second terminal member 180b.

  The metal shell 101 has a through hole 101c penetrating in the direction of the axis AX, and is configured in a cylindrical shape having a shelf portion 101t projecting radially inward inside the through hole 101c. The metal shell 101 causes the front end 120s of the gas detection element 120 to protrude outward (downward in FIG. 1) and the rear end 120k of the gas detection element 120 protrudes outward (upward in FIG. 1). In this state, the gas detection element 120 is held in the through hole 101c.

  An annular ceramic holder 103, two talc rings 104 and 105 filled with powder, and a ceramic sleeve 106 are disposed inside the through hole 101c of the metal shell 101. Specifically, the ceramic holder 103, the talc rings 104 and 105, and the ceramic sleeve 106 are arranged in this order in a state of surrounding the gas detection element 120 in the radial direction (the lower end side in FIG. 1). ) To the rear end side in the axial direction (upper end side in FIG. 1).

  A metal cup 107 is disposed between the ceramic holder 103 and the shelf 101 t of the metal shell 101. A caulking ring 108 is disposed between the ceramic sleeve 106 and the rear end portion 101k of the metal shell 101. The rear end portion 101k of the metal shell 101 is crimped so as to press the ceramic sleeve 106 toward the distal end side via the crimping ring 108.

A metal (specifically, stainless steel) external protector 111 and internal protector 112 having a plurality of holes are attached to the front end of the metal shell 101 by welding so as to cover the front end 120s of the gas detection element 120. It has been.
On the other hand, an outer cylinder 114 (corresponding to a casing member) is attached to the rear end portion of the metal shell 103 by welding. The outer cylinder 114 has a cylindrical shape extending in the direction of the axis AX and surrounds the gas detection element 120.

  The holding member 140 is a cylindrical member made of an insulating material (specifically, alumina) and having an insertion hole 140c penetrating in the direction of the axis AX. The six terminal members (first terminal member 170b, second terminal member 180b, etc.) described above are arranged in the insertion hole 140c (see FIG. 1). At the rear end portion of the holding member 140, a collar portion 140k that protrudes radially outward is formed. The holding member 140 is held by the internal support member 118 by the flange portion 140k coming into contact with the internal support member 118. The internal support member 118 is held by the outer cylinder 114 by a caulking portion 114g that is caulked toward the radially inner side of the outer cylinder 114.

  An insulating member 190 is disposed on the rear end surface 140 b of the holding member 140. The insulating member 190 is made of an electrically insulating material (specifically, alumina) and has a cylindrical shape. The insulating member 190 is formed with a total of six through holes 191 penetrating in the direction of the axis AX. Each through-hole 191 is configured by a through-hole surface 192 (substantially cylindrical inner wall surface). In the through hole 191, the above-described lead wire gripping portion (first lead wire gripping portion 177b, second lead wire gripping portion 187b, etc.) of the terminal member is disposed.

  Further, an elastic seal member 115 made of fluororubber is disposed on the radially inner side of the rear end opening 114c located at the rear end in the axial direction (upper end in FIG. 1) of the outer cylinder 114 (see FIG. 1). . The elastic seal member 115 is formed with a total of six cylindrical insertion holes 115c extending in the direction of the axis AX. Each insertion hole 115 c is configured by an insertion hole surface 115 b (cylindrical inner wall surface) of the elastic seal member 115. One lead wire 116 is inserted through each insertion hole 115c. Each lead wire 116 extends to the outside of the gas sensor 100 through the insertion hole 115 c of the elastic seal member 115.

  As shown in FIG. 3, the elastic seal member 115 is pressed by a caulking portion 114 b that caulks the rear end opening 114 c of the outer cylinder 114 inward in the radial direction (the side from the left and right toward the axis AX in FIG. 3). The insertion hole 115c is elastically deformed so that its diameter is reduced (the dimension in the left-right direction is reduced in FIG. 3). As a result, the elastic seal member 115 brings the insertion hole surface 115b and the outer peripheral surface 116b of the lead wire 116 into close contact with each other at the radially inner position of the caulking portion 114b, and the outer peripheral surface of the insertion hole surface 115b and the lead wire 116. 116b is watertight. As a result, through the gap between the insertion hole surface 115 b of the elastic seal member 115 and the outer peripheral surface 116 b of the lead wire 116, the inside of the gas sensor 100 (the first terminal member 170 b, the second terminal member 180 b, and the gas detection element 120 is externally provided. Etc.) to prevent water from entering.

  Further, the elastic seal member 115 presses the insulating member 190 located on the front end side in the axis AX direction (lower side in FIG. 1) from the self to the front end side in the axis AX direction. Thus, the insulating member 190 and the holding member 140 are pressed and fixed between the elastic seal member 115 and the internal support member 118.

  Incidentally, in the gas sensor 100 according to the first embodiment, as illustrated in FIG. 3, the through-hole surfaces 192 of the insulating member 190 each include a tapered surface 192 b that is not parallel to the axis AX. The tapered surface 192b is a hole extending from the rear end surface 190b of the insulating member 190 on the elastic seal member 115 side to the front end side in the axis AX direction, and from the rear end surface 190b to the front end side in the axis AX direction (lower side in FIG. 3). A tapered hole (specifically a truncated cone shape) (referred to as a tapered hole 191b, see FIG. 4) is formed. The tapered surface 192b corresponds to a seal side surface facing the elastic seal member 115 side.

  Further, in the gas sensor 100 according to the first embodiment, as shown in an enlarged view in FIG. 4, the elastic seal member 115 includes six insertion portions 115 d that are inserted into the through holes 191 of the insulating member 190. Each insertion portion 115d has a truncated cone shape that fits into the taper hole 191b, and of the insertion hole surface 115b that extends in the axis AX direction (vertical direction in FIG. 4), the distal end side insertion hole surface positioned on the distal end side in the axial direction. 115f. The insertion portion 115d is pressed against the tapered surface 192b of the insulating member 190, and elastically deforms so that the distal end side insertion hole 115g constituted by the distal end side insertion hole surface 115f of the insertion hole 115c is reduced in diameter. The side insertion hole surface 115f and the outer peripheral surface 116b of the lead wire 116 are brought into close contact with each other. Thereby, the insertion part 115d is watertight between the front end side insertion hole surface 115f and the outer peripheral surface 116b of the lead wire 116.

  As described above, in the gas sensor 100 according to the first embodiment, the elastic seal member 115 is inserted in the through hole 191 of the insulating member 190 in addition to the radial inner position of the crimped portion 114 b of the outer cylinder 114. The space between the surface 115b (specifically, the front end side insertion hole surface 115f) and the outer peripheral surface 116b of the lead wire 116 is watertight. Therefore, in the gas sensor 100 of the first embodiment, compared with a conventional gas sensor (for example, the gas sensor of Patent Document 1), the gap between the insertion hole surface 115b of the elastic seal member 115 and the outer peripheral surface 116b of the lead wire 116 is passed. Further, it is possible to further prevent water from entering the inside of the gas sensor 100 (the first terminal member 170b, the second terminal member 180b, the gas detection element 120, etc.) from the outside.

Here, a mechanism for watertightness between the front end side insertion hole surface 115f and the outer peripheral surface 116b of the lead wire 116 will be described.
In the assembly process of the gas sensor 100 according to the first embodiment, the holding member 140, the insulating member 190, and the terminal member (the first terminal member 170b and the like) connected to the lead wire 116 are integrated, and the flange portion of the holding member 140 is integrated. 140k is brought into contact with the internal support member 118 held by the caulking portion 114g of the outer cylinder 114 (already welded to the metal shell 101) (see FIG. 1). At this time, the electrode terminal portion (first electrode terminal portion 124 and the like) of the gas detection element 120 fixed to the metal shell 101 is connected to the element contact portion of the terminal member (the first element contact portion of the first terminal member 170b). 173b, etc.) abut.

  Thereafter, each insertion portion 115 d is inserted (fitted) into the tapered hole 191 b of the insulating member 190 with respect to the elastic seal member 115 in which the lead wire 116 is inserted into the insertion hole 115 c. At this time, the elastic seal member 115 is disposed radially inside the rear end opening 114c of the outer cylinder 114. In this state, when the rear end opening 114c of the outer cylinder 114 is caulked inward in the radial direction, and the elastic seal member 115 is elastically compressed inward in the radial direction, the elastic seal member 115 is moved downward in the axial direction (downward in FIG. 1). ). At this time, the insertion portion 115d of the elastic seal member 115 is strongly pressed against the tapered surface 192b of the insulating member 190, and by the reaction force, the distal end side insertion hole 115g is elastically deformed so as to reduce its diameter (FIGS. 3 and 3). 4). As a result, as indicated by an arrow in FIG. 4, a force acts from the distal end side insertion hole surface 115 f of the elastic seal member 115 toward the outer peripheral surface 116 b of the lead wire. It is possible to make the space between the distal end side insertion hole surface 115f and the outer peripheral surface 116b of the lead wire 116 watertight by being in close contact with the outer peripheral surface 116b.

  Further, the gas sensor 100 of the first embodiment is used by being mounted on an exhaust pipe of an internal combustion engine. Therefore, the gas sensor 100 according to the first embodiment becomes a high temperature during use, and the elastic seal member 115 is thermally expanded. Since the elastic seal member 115 tends to extend in the direction of the axis AX due to thermal expansion, the insertion portion 115d of the elastic seal member 115 is strongly pressed against the tapered surface 192b. As a result, in the insertion portion 115d of the elastic seal member 115, a force acts in a direction to further reduce the diameter of the distal end side insertion hole 115g, so that the distal end side insertion hole surface 115f is more closely attached to the outer peripheral surface 116b of the lead wire 116. Can be made. In this way, the watertightness between the distal end side insertion hole surface 115f and the outer peripheral surface 116b of the lead wire 116 can be further enhanced. Therefore, in the gas sensor 100 of the first embodiment, water further enters the gas sensor 100 from the outside through the gap between the insertion hole surface 115b of the elastic seal member 115 and the outer peripheral surface 116b of the lead wire 116. Can be prevented.

  By the way, also in the conventional gas sensor 500, as shown in FIG. 8, the elastic seal member 515 is compressed radially inward at a position radially inward of the caulking portion 514b of the outer cylinder 514, and the insertion hole surface 515b and the lead wire are compressed. The space between the outer peripheral surface 516b of 516 is watertight. However, in the conventional gas sensor 500, the elastic seal member 515 is in contact with the entire rear end surface 590b of the insulating member 590 (there is no gap between the rear end surface 590b of the insulating member 590 and the elastic seal member 515). For this reason, when the elastic seal member 515 is thermally expanded when the gas sensor 500 is used, the elastic seal member 515 cannot extend to the axial front end side (downward in FIG. 8), so the axial rear end side (in FIG. 8). It extends upward) and jumps out of the gas sensor 500 (the pop-out amount increases).

  Moreover, the portion of the elastic seal member 515 that protrudes to the outside of the gas sensor 500 tends not to return to the inside of the gas sensor 500 even if it is subsequently cooled. Therefore, as the elastic seal member 515 repeats thermal expansion, the volume of the elastic seal member 515 that protrudes to the outside of the gas sensor 500 tends to increase. Accordingly, the volume of the elastic seal member 515 located on the radially inner side of the crimped portion 514b of the outer cylinder 514 decreases, and the insertion hole surface 515b and the lead wire 516 are located at the radially inner position of the crimped portion 514b. In some cases, watertightness between the outer peripheral surface 516b and the outer peripheral surface 516b may decrease.

  In contrast, in the gas sensor 100 according to the first embodiment, as shown in FIG. 3, a gap S is provided between the rear end surface 190 b of the insulating member 190 and the elastic seal member 115. For this reason, the elastic seal member 115 can extend toward the front end side in the axis AX direction (downward in FIG. 3) in the gap S when thermally expanding. Thereby, since the volume of the elastic seal member 115 that jumps out of the gas sensor 100 due to thermal expansion can be reduced, the volume of the elastic seal member 115 positioned on the radially inner side of the caulking portion 114b of the outer cylinder 114 is reduced. Can be suppressed. Therefore, in the gas sensor 100 of the first embodiment, the water tightness between the insertion hole surface 115b and the outer peripheral surface 116b of the lead wire 116 is reduced at the radially inner position of the caulking portion 114b of the outer cylinder 114. Can be suppressed.

  Note that the portion of the elastic seal member 115 that has expanded due to thermal expansion toward the front end side in the axial direction (downward in FIG. 3) in the gap S returns to the state before thermal expansion when cooled. Accordingly, the volume of the elastic seal member 115 located on the radially inner side of the caulking portion 114b of the outer cylinder 114 is reduced because the elastic seal member 115 is thermally expanded and extended in the gap S in the axial direction. There is almost no end.

(Example 2)
Next, Embodiment 2 of the present invention will be described with reference to the drawings.
FIG. 5 is a vertical cross-sectional view (cross-sectional view cut in the direction of the axis AX) of the gas sensor 200 according to the second embodiment. The gas sensor 200 of the second embodiment is different from the gas sensor 100 of the first embodiment in the shapes of the elastic seal member and the insulating member, and the other parts are the same. Therefore, here, it demonstrates centering on a different point from the gas sensor 100 of Example 1, and abbreviate | omits or simplifies description about another point.

  The insulating member 290 of the second embodiment is different in the shape of the through hole (thus, the shape of the through hole surface is different) as compared with the insulating member 190 of the first embodiment. Specifically, in Example 1, the through hole surface 192 of the insulating member 190 is provided with a tapered surface 192b as a seal side surface facing the elastic seal member 215 side (see FIG. 3). On the other hand, in the second embodiment, as shown in FIG. 6, in addition to the tapered surface 292 b, the circular holes 292 of the insulating member 290 are respectively provided as circular seal surfaces facing the elastic seal member 115 side. An annular surface 292d is provided.

  As shown in FIGS. 6 and 7, the tapered surface 292b is a hole extending from the rear end surface 290b forming the end surface on the elastic seal member 215 side of the insulating member 290 to the front end side in the axis AX direction, and extending from the rear end surface 190b to the axis line. A tapered (specifically, truncated cone shape) hole (referred to as a tapered hole 291b) having a diameter decreasing toward the distal end side in the AX direction (downward in FIGS. 6 and 7) is formed.

  The annular surface 292d is located on the tip end side in the axial direction from the rear end surface 290b of the insulating member 290 (downward in FIGS. 6 and 7), and has an annular shape facing the elastic seal member 215 side (upper side in FIGS. 6 and 7). Surface. The annular surface 292d includes a first hole portion 291c extending from the rear end surface 290b to the annular surface 292d in the through hole 291 of the insulating member 290, and an axial front end side from the annular surface 292d of the through hole 291 (see FIGS. 6 and 6). 7, a step is formed between the second hole 291 d extending downward). The first hole portion 291c includes a tapered hole 291b and a cylindrical first cylindrical hole 291f extending in the axis AX direction (vertical direction in FIGS. 6 and 7).

  Further, the elastic seal member 215 of the second embodiment is different in the shape of the insertion portion from the elastic seal member 115 of the first embodiment. Specifically, in Example 1, each insertion portion 115d has a truncated cone shape that fits into the tapered hole 191b. On the other hand, in the second embodiment, as shown in FIG. 6, each insertion portion 215d is shaped to fit into the first hole portion 291c (the tapered hole 291b and the first cylindrical hole 291f). That is, each insertion portion 215d has a shape having a truncated cone shape that fits into the tapered hole 291b and a cylindrical shape portion that fits into the first cylindrical hole 291f.

  Each insertion portion 215d has a distal end located on the distal end side in the axial direction (the lower side in FIG. 6) of the insertion hole surface 215b extending in the axis AX direction (the surface constituting the insertion hole 215c through which the lead wire 116 is inserted). A side insertion hole surface 215f is provided. Moreover, let the site | part comprised by the front end side insertion hole surface 215f among the insertion holes 215c be the front end side insertion hole 215g (refer FIG. 7).

  Each insertion portion 215d is pressed against the tapered surface 292b and the annular surface 292d of the insulating member 290 and elastically deforms so that the distal end side insertion hole 215g is reduced in diameter, and the distal end side insertion hole surface 215f and the lead wire 116 are The outer peripheral surface 116b is in close contact (see FIG. 7). As a result, the insertion portion 215d is watertight between the distal end side insertion hole surface 215f and the outer peripheral surface 116b of the lead wire 116.

  Thus, also in the gas sensor 200 of the second embodiment, the elastic seal member 215 has an insertion hole in the through hole 291 of the insulating member 290 in addition to the radially inner position of the crimped portion 114b of the outer cylinder 114. The space between the surface 215b (specifically, the front end side insertion hole surface 215f) and the outer peripheral surface 116b of the lead wire 116 is watertight. Therefore, even in the gas sensor 200 of the second embodiment, compared to the conventional gas sensor (for example, the gas sensor of Patent Document 1), the gap between the insertion hole surface 215b of the elastic seal member 215 and the outer peripheral surface 116b of the lead wire 116 is passed. Further, it is possible to further prevent water from entering the inside of the gas sensor 200 (the first terminal member 170b, the second terminal member 180b, the gas detection element 120, etc.) from the outside.

  In addition, in the gas sensor according to the second embodiment, the length of the portion (referred to as a seal portion) in which the space between the distal end side insertion hole surface 215f and the outer peripheral surface 116b of the lead wire 116 is watertight as compared with the gas sensor 100 of the first embodiment. (Referred to as the seal length). Specifically, the seal length L2 (see FIG. 7) of the second embodiment is considerably longer than the seal length L1 (see FIG. 4) of the first embodiment. Thereby, in the gas sensor of the second embodiment, compared with the gas sensor 100 of the first embodiment, the gas sensor 200 is externally provided through a gap between the insertion hole surface 215b of the elastic seal member 215 and the outer peripheral surface 116b of the lead wire 116. Water can be further prevented from entering the inside (the first terminal member 170b, the second terminal member 180b, the gas detection element 120, etc.).

Here, a mechanism for water-tightening between the distal end side insertion hole surface 215f and the outer peripheral surface 116b of the lead wire 116 will be described.
Even in the assembly process of the gas sensor 200 according to the second embodiment, the holding member 140, the insulating member 290, and the terminal member (the first terminal member 170 b and the like) connected to the lead wire 116 are integrated with each other. 140k is brought into contact with the internal support member 118 held by the caulking portion 114g of the outer cylinder 114 (already welded to the metal shell 101) (see FIG. 5). At this time, the electrode terminal portion (first electrode terminal portion 124 and the like) of the gas detection element 120 fixed to the metal shell 101 is connected to the element contact portion of the terminal member (the first element contact portion of the first terminal member 170b). 173b, etc.) abut.

  Thereafter, with respect to the elastic seal member 215 in which the lead wire 116 is inserted into the insertion hole 215c, each insertion portion 215d is inserted (fitted) into the first hole portion 291c (the tapered hole 291b and the first cylindrical hole 291f) of the insulating member 290. ) At this time, the elastic seal member 215 is disposed on the radially inner side of the rear end opening 114c of the outer cylinder 114. In this state, when the rear end opening 114c of the outer cylinder 114 is caulked inward in the radial direction and the elastic seal member 215 is elastically compressed inward in the radial direction, the elastic seal member 215 is axially distal (see FIGS. 5 and 5). 6 downward).

  At this time, the insertion portion 215d of the elastic seal member 215 (specifically, the portion of the insertion portion 215d facing the tapered surface 292b) is strongly pressed against the tapered surface 292b of the insulating member 290, and the reaction force causes the distal end The side insertion hole 215g (specifically, a portion of the distal end side insertion hole 215g located on the radially inner side of the tapered surface 292b) is elastically deformed so as to be reduced in diameter (see FIGS. 6 and 7). Further, at this time, the insertion portion 215d of the elastic seal member 215 is pressed against the annular surface 292d of the insulating member 290 to be compressed, so that in the first hole portion 291c (particularly, in the first cylindrical hole 291f). Then, the tip side insertion hole 215g is elastically deformed (thickness is increased) so as to reduce the diameter. As a result, as indicated by an arrow in FIG. 7, a force acts from the distal end side insertion hole surface 215f of the elastic seal member 215 toward the outer peripheral surface 116b of the lead wire, and therefore, the distal end side insertion hole surface 215f of the elastic seal member 215. Can be brought into close contact with the outer peripheral surface 116b of the lead wire, and the space between the distal end side insertion hole surface 215f and the outer peripheral surface 116b of the lead wire 116 can be made watertight.

  The gas sensor 200 of the second embodiment is also used by being mounted on the exhaust pipe of the internal combustion engine. Therefore, the gas sensor 200 of the second embodiment also becomes high temperature during use, and the elastic seal member 215 is thermally expanded. Since the elastic seal member 215 tends to extend in the direction of the axis AX due to thermal expansion, the insertion portion 215d of the elastic seal member 215 is strongly pressed against the tapered surface 292b and the annular surface 292d. As a result, in the insertion portion 215d of the elastic seal member 215, a force acts in a direction to further reduce the diameter of the distal end side insertion hole 215g, so that the distal end side insertion hole surface 215f is more closely attached to the outer peripheral surface 116b of the lead wire 116. Can be made. In this way, water tightness between the distal end side insertion hole surface 215f and the outer peripheral surface 116b of the lead wire 116 can be improved. Therefore, in the gas sensor 200 of the second embodiment, water further enters the inside of the gas sensor 200 from the outside through the gap between the insertion hole surface 215b of the elastic seal member 215 and the outer peripheral surface 116b of the lead wire 116. Can be prevented.

  Also in the gas sensor 200 of the second embodiment, as shown in FIG. 6, the gap S is provided between the rear end surface 290 b of the insulating member 290 and the elastic seal member 215. For this reason, the elastic seal member 215 can extend toward the front end side in the axis AX direction (downward in FIG. 6) in the gap S when thermally expanding. Thus, similarly to the gas sensor 100 of the first embodiment, the volume of the elastic seal member 215 that protrudes to the outside of the gas sensor 200 due to thermal expansion can be reduced, so that the inner side in the radial direction of the caulking portion 114b of the outer cylinder 114 can be reduced. The volume reduction of the elastic seal member 215 located at the position can be suppressed. Therefore, even in the gas sensor 200 of the second embodiment, the watertightness between the insertion hole surface 215b and the outer peripheral surface 116b of the lead wire 116 is reduced at the radially inner position of the caulking portion 114b of the outer cylinder 114. Can be suppressed.

  Note that the portion of the elastic seal member 215 that has been thermally expanded in the gap S toward the front end side in the axial direction (downward in FIG. 6) returns to the state before the thermal expansion when cooled. Therefore, the volume of the elastic seal member 215 located on the radially inner side of the caulking portion 114b of the outer cylinder 114 is reduced because the elastic seal member 215 expands due to thermal expansion toward the front end in the axial direction in the gap S. There is almost no end.

  In the above, the present invention has been described with reference to the first and second embodiments. However, the present invention is not limited to the above-described embodiments, and it can be applied as appropriate without departing from the scope of the present invention. Nor.

For example, in the first and second embodiments, the holding member 140 and the insulating members 190 and 290 are separated (two members), but the holding member and the insulating member may be configured integrally (one member). .
In the first and second embodiments, the gas sensor that detects the NOx concentration (NOx sensor) is exemplified as the gas sensor. However, the present invention can also be applied to a gas sensor (oxygen sensor) that detects the oxygen concentration.

100, 200 Gas sensor 114 Outer cylinder (casing member)
114b Clamping portion 114c Rear end opening 115, 215 Elastic seal member 115b, 215b Insertion hole surface 115c, 215c Insertion hole 115d, 215d Insertion portion 115f, 215f Tip side insertion hole surface 115g, 215g Tip side insertion hole 116 Lead wire 116b Outer peripheral surface 120 of lead wire Gas detection element 170b First terminal member 180b Second terminal member 190, 290 Insulating member 190b, 290b Rear end surface 191, 291 Through hole 191b, 291b Tapered hole 192, 292 Through hole surface 192b, 292b Tapered surface (Seal side)
291c 1st hole part 291d 2nd hole part 292d Annular surface (seal side)
AX axis S gap

Claims (5)

A gas detection element extending in the axial direction, the gas detection element having the axial direction tip side exposed to the gas to be measured;
A terminal member electrically connected to the gas detection element;
A lead wire electrically connected to the terminal member;
A cylindrical casing member extending in the axial direction and surrounding the gas detection element, the terminal member, and the lead wire;
An insertion hole into which the lead wire is inserted, and has an insertion hole surface that constitutes an insertion hole extending in the axial direction, and is disposed on the radially inner side of the rear end opening of the casing member located at the rear end in the axial direction. An elastic seal member that is elastically deformed so that the insertion hole is reduced in diameter by being pressed by a caulking portion that caulks the rear end opening radially inward, and is radially inward of the caulking portion. An elastic seal member that makes the space between the insertion hole surface and the outer peripheral surface of the lead wire watertight,
An insulating member that is located closer to the distal end side in the axial direction than the elastic seal member and is housed inside the casing member, and having a through hole surface that forms a through hole in which the terminal member is disposed. When,
A gas sensor comprising:
In the gas sensor in which the lead wire extends to the outside of the gas sensor through the insertion hole of the elastic seal member,
The through hole surface of the insulating member includes a seal side surface facing the elastic seal member side,
The elastic seal member is an insertion portion that protrudes from the front end surface thereof toward the front end side and is inserted into the through hole of the insulating member, and is located on the front end side in the axial direction of the insertion hole surface. Comprising an insertion portion having a distal end side insertion hole surface,
The insertion portion is pressed against the seal side surface of the insulating member and elastically deformed so that a distal end side insertion hole constituted by the distal end side insertion hole surface of the insertion hole has a reduced diameter, and the distal end side A gas sensor in which a space between the insertion hole surface and the outer peripheral surface of the lead wire is watertight. The gas sensor according to claim 1,
A taper surface, which is a hole extending from the rear end surface of the insulating member to the front end side in the axial direction and has a diameter that decreases from the rear end surface toward the front end side in the axial direction, is used as the seal side surface. Including gas sensor. The gas sensor according to claim 1 or 2, wherein
A ring-shaped annular surface that is located on the front end side in the axial direction with respect to the rear end surface of the insulating member and faces the elastic seal member, and extends from the rear end surface to the annular surface of the through hole. A gas sensor including, as the seal side surface, an annular surface that forms a step between the first hole portion and a second hole portion extending from the annular surface to the distal end side in the axial direction. The gas sensor according to any one of claims 1 to 3,
A gas sensor in which a gap is provided between a rear end surface of the insulating member and the elastic seal member. It is a gas sensor as described in any one of Claims 1-4, Comprising:
There are a plurality of the lead wires,
  The insulating member has the same number of through holes as the lead wire,
  The elastic seal member has the same number of the insertion portions as the through holes,
  Each insertion portion is inserted into the through hole of the insulating member and pressed against the seal side surface, and is elastically deformed so that the distal end side insertion hole has a reduced diameter, and the distal end side insertion hole surface And the outer peripheral surface of the lead wire are made watertight
Gas sensor.

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