JP2018194308A - Particulate sensor - Google Patents

Abstract

To provide a particulate sensor in which, even when an adhesive received in an adhesive reservoir is partially crushed into powder, the powder of the adhesive is made difficult to penetrate an air hole of a holder.SOLUTION: A holder 50 has: an insertion hole 52 which pieces the holder 50 in an axial direction GH and has a discharge electrode assembly 70 inserted thereto; and an air hole 57 which pieces the holder 50 in the axial direction and allows air AR introduced from an air inlet 15t into a sensor body part 5 to flow from a rear end side GK to a front end side GS in the axial direction GH. The insertion hole 52 includes an adhesive reservoir 52b which is opened to the rear end side in the axial direction GH and receives an adhesive 59. A rear end-side ventilation opening 55d opened to the rear end side GK in the axial direction GH, GH of the air hole 57 of the holder 50 is located nearer to the rear end side GK in the axial direction GH than a rear end-side receiving opening 52d opened to the rear end side GK in the axial direction GH, GH of the adhesive reservoir 52b.SELECTED DRAWING: Figure 12

Description

  The present invention relates to a fine particle sensor that detects the amount of fine particles in a gas to be measured flowing through a vent pipe.

  Sometimes you want to measure the amount of particulates in a gas. For example, in an internal combustion engine (for example, a diesel engine or a gasoline engine), fine particles such as soot may be contained in the exhaust gas. Exhaust gas containing such fine particles is purified by collecting the fine particles with a filter. However, when a problem such as breakage of the filter occurs, unpurified exhaust gas is directly discharged downstream of the filter. Accordingly, there is a need for a particulate sensor capable of directly detecting the amount of particulates in the exhaust gas and detecting the amount of particulates in the exhaust gas downstream of the filter in order to detect a filter failure.

  As such a fine particle sensor, Patent Document 1 has a sensor main body portion configured to extend in the axial direction, and a portion on the tip end side in the axial direction of the sensor main body portion is disposed inside the vent pipe. There is disclosed a fine particle sensor that detects the amount of fine particles in a gas to be measured that flows in a vent pipe.

JP 2012-194077 A

  The fine particle sensor (sensor body part) of Patent Document 1 includes an air intake part for taking air into the inside from the outside of the sensor body part, and a discharge electrode body (an insulating pipe covering the discharge electrode body part and its outer periphery) extending in the axial direction. And a holder for holding the discharge electrode body. Further, the fine particle sensor (sensor body portion) is a discharge counter electrode portion that is located on the tip end side in the axial direction from the holder and serves as a counter electrode of the discharge electrode body, and the discharge space in which the tip portion of the discharge electrode body is disposed. A discharge counter electrode that generates an air discharge with the tip of the discharge electrode body in the discharge space, and is located on the tip end side in the axial direction of the discharge counter electrode, and is generated by the air discharge. And a portion constituting a mixing space in which ions and a gas to be measured are introduced and mixed.

  Among these, the holder is an insertion hole that penetrates the holder in the axial direction and into which the discharge electrode body is inserted, and a vent hole that penetrates the holder in the axial direction, and is inserted into the sensor body through the air intake portion. The introduced air has a vent hole that flows from the rear end side to the front end side in the axial direction through the vent hole. The discharge counter electrode portion is a communication hole that communicates the discharge space and the mixing space, and has a communication hole through which the air flows from the rear end side in the axial direction through the communication hole to the front end side.

  In this fine particle sensor (sensor body part), the air introduced into the sensor body part through the air intake part flows in the sensor body part from the rear end side in the axial direction to the tip side, and then the holder After passing through the vent hole from the rear end side in the axial direction to the front end side and being introduced into the discharge space, the air was introduced into the mixing space from the discharge space through the communication hole, and thus occurred in the discharge space. The ion is introduced into the mixing space together with the air.

  By the way, in order to fix the discharge electrode body to the holder, the discharge electrode body may be adhered to the holder by an adhesive. Specifically, for example, an insertion hole (a through hole into which the discharge electrode body is inserted) of the holder is provided with an adhesive storage portion that opens to the rear end side in the axial direction and stores the adhesive, and the insertion hole of the holder With the discharge electrode body inserted therein, the discharge electrode body is bonded to the holder by housing (filling) the adhesive inside the adhesive housing portion. In addition, when using the sensor main body part of a particulate sensor attached to the exhaust pipe of an internal combustion engine, since the inside of a particulate sensor also becomes high temperature, it is preferable to use an inorganic adhesive with high heat resistance as an adhesive.

  However, the vibration of a ventilation pipe (for example, an exhaust pipe of an internal combustion engine) to which the sensor main body is attached may be transmitted to the adhesive stored (filled) in the adhesive storage section of the holder. Due to this vibration, a crack or the like is generated on the surface of the adhesive accommodated in the adhesive accommodating portion, so that a part of the adhesive is crushed into a powder, and this powdered adhesive (adhesive of the adhesive) There is a risk that the powder) is released to the outside of the adhesive accommodating portion. In particular, when an inorganic adhesive is used as the adhesive, the above-described adhesive powder is easily generated. In this fine particle sensor, the air introduced into the sensor main body through the air intake part flows in the sensor main body from the rear end side in the axial direction to the front end side, and then in the vent hole of the holder. It is configured to be introduced. For this reason, there is a possibility that the powder of the adhesive released to the outside of the adhesive accommodating portion may enter the vent hole of the holder together with the air.

  Further, in this fine particle sensor, air introduced into the vent hole of the holder passes through the holder vent hole from the rear end side to the front end side in the axial direction and is introduced into the discharge space. By being introduced from the discharge space into the mixing space through the communication hole, the ions generated in the discharge space are introduced into the mixing space together with the air. In particular, in this fine particle sensor, the communication hole that connects the discharge space and the mixing space is an orifice hole for injecting air from the discharge space to the mixing space, and has a minute inner diameter. For this reason, when the powder of the adhesive enters the vent hole of the holder together with air, the powder passes through the vent hole of the holder and is introduced into the discharge space, and communicates with the powder of the adhesive. There was a risk that the hole would be blocked (clogged). For this reason, it becomes impossible for air to flow into the mixing space, and ions generated in the discharge space may be introduced into the mixing space together with the air. As a result, there is a possibility that the amount of fine particles in the gas to be measured cannot be properly detected.

  The present invention has been made in view of such a problem, and even when a part of the adhesive contained in the adhesive containing part is crushed to produce an adhesive powder, the adhesive powder is It is an object of the present invention to provide a fine particle sensor that is difficult to enter a vent hole of a holder.

  One aspect of the present invention has a sensor main body that extends in the axial direction, and a portion of the sensor main body on the tip end side in the axial direction is disposed inside the vent pipe, and flows through the vent pipe. A particulate sensor for detecting the amount of particulates in a gas to be measured, wherein the particulate sensor has an air intake part for taking in air from the outside to the inside of the sensor body part, and the sensor body part includes: A discharge electrode body extending in the axial direction; a holder that holds the discharge electrode body; an adhesive that adheres the discharge electrode body to the holder; and a distal end side in the axial direction from the holder; A discharge counter electrode portion serving as a counter electrode of the electrode body, the discharge electrode body having a discharge space in which the tip portion of the discharge electrode body is disposed, and air discharge between the tip portion of the discharge electrode body in the discharge space Discharge counter electrode to be generated A portion that forms a mixing space that is located on the tip end side in the axial direction from the discharge counter electrode portion and that mixes the ions generated by the air discharge and the gas to be measured introduced and mixed, and The holder is an insertion hole that penetrates the holder in the axial direction and into which the discharge electrode body is inserted, and a vent hole that penetrates the holder in the axial direction, and is formed through the air intake portion. The air introduced into the inside has a vent hole that flows from the rear end side in the axial direction to the front end side through the vent hole, and the insertion hole opens to the rear end side in the axial direction. Including an adhesive accommodating portion for accommodating the adhesive, wherein the adhesive is accommodated in the adhesive accommodating portion, and the discharge counter electrode portion communicates with the discharge space and the mixing space. And the air is connected to the communication hole. The fine particle sensor has a communication hole that circulates from the rear end side to the front end side in the axial direction, and the air introduced into the sensor main body through the air intake section is connected to the sensor main body. The inside flows from the rear end side in the axial direction to the front end side, passes through the vent hole of the holder from the rear end side in the axial direction to the front end side, and is introduced into the discharge space. Air is introduced from the discharge space to the mixing space through the communication hole, so that the ions generated in the discharge space are introduced into the mixing space together with the air, and the holder The rear end side vent opening that opens to the rear end side in the axial direction of the vent hole is more than the rear end accommodation opening portion that opens to the rear end side in the axial direction of the adhesive accommodating section. Located on the rear end side of the direction This is a fine particle sensor.

  The fine particle sensor (sensor main body) described above includes a holder for holding a discharge electrode body (for example, a discharge electrode body having a metal discharge electrode main body and an electrically insulating pipe covering the outer periphery thereof), and a discharge electrode body. Adhesive. The holder has an insertion hole that penetrates the holder in the axial direction and into which the discharge electrode body is inserted. Further, the holder is a vent hole penetrating the holder in the axial direction, and the air introduced into the sensor body through the air intake portion passes from the rear end side in the axial direction to the front end side through the vent hole. It has a vent hole that circulates. Among these, the insertion hole includes an adhesive accommodating portion that opens to the rear end side in the axial direction. The adhesive is accommodated (filled) inside the adhesive accommodating portion.

  Further, in the fine particle sensor described above, the air introduced into the inside of the sensor body through the air intake part flows through the inside of the sensor body from the rear end side in the axial direction to the front end side, and passes through the inside of the vent hole of the holder. After the air passes from the rear end side to the front end side in the axial direction and is introduced into the discharge space, the air is introduced from the discharge space to the mixing space through the communication hole, so that ions generated in the discharge space are In addition, the structure is introduced into the mixing space.

  By the way, the vibration of the ventilation pipe which has attached the sensor main-body part may be transmitted to the adhesive agent accommodated in the adhesive agent accommodating part of a holder, for example. Due to this vibration, a part of the adhesive may be crushed into powder, and the powdered adhesive (adhesive powder) may be released to the outside of the adhesive container. And this particulate sensor is comprised so that the air introduced into the inside of a sensor main-body part through an air intake part may be introduce | transduced in the vent hole of a holder. For this reason, in the conventional fine particle sensor, there is a possibility that the powder of the adhesive released to the outside of the adhesive accommodating portion may enter the vent hole of the holder together with the air.

  On the other hand, in the fine particle sensor described above, the rear end side vent opening portion that opens to the rear end side in the axial direction in the vent hole of the holder is the rear end that opens to the rear end side in the axial direction of the adhesive accommodating portion. It is located on the rear end side in the axial direction with respect to the side accommodating opening. Thereby, even when a part of the adhesive accommodated in the adhesive accommodating part is crushed and the powder of the adhesive is generated, the powder of the adhesive does not easily enter the vent hole of the holder.

  The reason is that in the above-described fine particle sensor, the air introduced into the sensor main body through the air intake portion flows in the sensor main body from the rear end side to the front end side in the axial direction. This is because it is configured to be introduced into the vent hole. Specifically, the air flow direction in the sensor main body is a direction from the rear end side in the axial direction toward the front end side, with the rear end side in the axial direction being the upstream side and the front end side in the axial direction being the downstream side. On the other hand, the rear end side ventilation opening of the holder is arranged on the rear end side in the axial direction, that is, on the upstream side in the air flow direction with respect to the rear end side opening of the adhesive accommodating section. Because.

  As a result, when the powder of the adhesive is generated, the powder of the adhesive located in the adhesive container is unlikely to flow from the rear end side housing opening to the rear end side vent opening of the holder (it is difficult to reach). Therefore, it becomes difficult for the powder of the adhesive to enter the ventilation hole from the rear end side ventilation opening of the holder. Further, even when the powder of the adhesive is discharged from the rear end side housing opening to the outside of the adhesive housing portion due to vibration or the like, it is difficult for the adhesive powder to flow to the rear end side vent opening of the holder ( It becomes difficult for the adhesive powder to enter the vent hole from the rear end side vent opening of the holder.

  The fine particle sensor described above generates an air discharge between the distal end portion of the discharge electrode body and the discharge counter electrode portion in the discharge space, and then the ions generated by the air discharge in the mixing space. This is a fine particle sensor that generates charged charged fine particles by adhering to fine particles contained in a gas to be measured, and then detects the amount of fine particles in the gas to be measured based on the charge amount of the charged fine particles.

  On the other hand, in the above-mentioned fine particle sensor, even when adhesive powder is generated, the adhesive powder is difficult to enter into the vent hole of the holder, so the communication hole is blocked by the adhesive powder. (Clogging) is difficult to occur, and ions generated in the discharge space cannot be introduced into the mixing space together with air. As a result, it is possible to reduce the problem that the charged fine particles cannot be generated properly, and to reduce the problem that the amount of the fine particles in the gas to be measured cannot be detected properly.

  Further, in the fine particle sensor, the holder has a holder main body including the adhesive accommodating portion and a hollow cylindrical shape extending in the axial direction, and the holder main body at the rear end in the axial direction. A cylindrical portion that protrudes from the rear end surface positioned toward the rear end side in the axial direction, and a hollow portion that penetrates the cylindrical portion in the axial direction constitutes at least a part of the vent hole; and And the rear end side accommodation opening of the adhesive accommodating portion is open to the rear end surface of the holder main body, and the rear end side in the axial direction of the hollow portion of the cylindrical portion A fine particle sensor in which the opening opening is the rear end side ventilation opening may be used.

  In the above-described fine particle sensor, the holder includes a holder main body including the adhesive accommodating portion, and a cylindrical portion protruding from the rear end surface of the holder main body toward the rear end in the axial direction. In this holder, a hollow portion (hollow hole) penetrating the cylindrical portion in the axial direction constitutes at least a part of the vent hole, and an opening portion that opens to the rear end side in the axial direction of the hollow portion of the cylindrical portion is provided. It is a rear end side ventilation opening. Moreover, the rear end side accommodation opening part of the adhesive agent accommodating part is opening in the rear end surface of the holder main-body part.

  In the particulate sensor having such a holder, the rear end side ventilation opening is positioned on the rear end side in the axial direction with respect to the rear end side opening, so that the adhesive accommodated in the adhesive accommodating portion. Even when a part of the adhesive is crushed and adhesive powder is generated, the adhesive powder is less likely to enter the vent hole of the holder.

  Furthermore, in any one of the fine particle sensors, the adhesive may be a fine particle sensor that is a heat-resistant inorganic adhesive.

  In the fine particle sensor described above, an inorganic adhesive having heat resistance is used as an adhesive accommodated in the adhesive accommodating portion. When the sensor main body of the fine particle sensor is used by being attached to the exhaust pipe of an internal combustion engine, the inside of the sensor main body becomes high temperature. Therefore, it is preferable to use an inorganic adhesive having heat resistance as the adhesive.

  However, when an inorganic adhesive is used as the adhesive, cracks are likely to occur on the surface of the adhesive accommodated in the adhesive accommodating portion due to vibration, and a part of the adhesive is crushed and powdered. It becomes easy to become. On the other hand, in the above-described fine particle sensor, the rear end side ventilation opening is arranged on the rear end side in the axial direction with respect to the rear end accommodation opening, so that the adhesive contained in the adhesive accommodation portion Even when part of the powder is crushed and adhesive powder is likely to be generated, the adhesive powder is difficult to enter the vent hole of the holder.

It is the schematic which shows the state which mounted | wore the exhaust pipe of the engine of the vehicle with the particulate sensor concerning embodiment. It is a perspective view of the particulate sensor concerning an embodiment. It is a longitudinal cross-sectional view of the same particle sensor. It is another longitudinal cross-sectional view of the same fine particle sensor, and is a longitudinal cross-sectional view in a direction orthogonal to FIG. It is a longitudinal cross-sectional view of the state which attached the particulate sensor to the exhaust pipe. It is a disassembled perspective view of the particulate sensor. It is a cross-sectional view of the first cable and the second cable. It is a figure showing the schematic structure of the particulate detection system concerning an embodiment. It is a side view of the holder concerning an embodiment. It is a top view (plan view of the rear end side) of the holder. It is a bottom view (plan view of the front end side) of the holder. It is DD sectional drawing of FIG. It is EE sectional drawing of FIG. It is the B section enlarged view of FIG. It is the perspective view which looked at the holder in a particulate sensor from the rear end side. It is a figure which shows typically the mode of taking in of the microparticles | fine-particles in a microparticle sensor, charging, and discharge | emission.

(Embodiment)
Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram illustrating a state in which the particulate sensor 1 according to the embodiment is mounted on an exhaust pipe EP of an engine ENG (internal combustion engine) mounted on a vehicle AM. FIG. 2 is a perspective view of the particle sensor 1. FIG. 3 is a longitudinal sectional view of the particle sensor 1. FIG. 4 is another longitudinal sectional view of the fine particle sensor 1, and is a longitudinal sectional view in a direction orthogonal to FIG. FIG. 5 is a longitudinal sectional view of the sensor main body 5 attached to the exhaust pipe EP. FIG. 6 is an exploded perspective view of the particle sensor 1.
Of the axial direction GH (the direction along the axis AX, the vertical direction in FIG. 3) of the particulate sensor 1, the side (downward in FIG. 3) attached to the exhaust pipe EP (ventilation pipe) is the tip side GS, the exhaust pipe A side (upward in FIG. 3) arranged outside the EP is defined as a rear end side GK.

First, the particulate detection system 200 of the present embodiment will be described. As shown in FIG. 1, the particle detection system 200 includes a particle sensor 1 and a circuit unit 201 that drives the particle sensor 1.
The particulate sensor 1 is attached to an exhaust pipe EP of an engine ENG (internal combustion engine) mounted on the vehicle AM, and detects particulate S such as soot in the exhaust gas EG (measured gas) flowing through the exhaust pipe EP. Specifically, the sensor main body 5 of the particulate sensor 1 is fixed to the exhaust pipe EP, and the tip side portion of the sensor main body 5 is disposed in the exhaust pipe EP (see FIG. 5) and exposed to the exhaust gas EG. It is.

  The circuit unit 201 is connected to the sensor body 5 of the particulate sensor 1 through the first cable 90 and the second cable 100 outside the exhaust pipe EP. The circuit unit 201 has a circuit that drives the particle sensor 1 and detects a signal current described later.

  Here, the particle sensor 1 of the present embodiment will be described in detail. The particulate sensor 1 extends from the sensor body 5, a cable (first cable 90 and second cable 100) that electrically connects the sensor body 5 and the circuit unit 201, and the sensor body 5. And an air tube 40 (see FIGS. 2 and 3). Among these, the sensor main body part 5 has a sensor main body front end part 6 and a sensor main body rear end part 7 located on the rear end side GK. The sensor main body front end portion 6 is attached to a pipe mounting portion EPT of a metal exhaust pipe EP having a ground potential PVE, and the sensor main body rear end portion 7 is disposed outside the exhaust pipe EP (FIGS. 5 and 8). reference).

  In addition, the air tube 40 extending from the sensor body 5 is connected to an external pressure pump 330 (see FIG. 8). The first cable 90 and the second cable 100 extending from the sensor body 5 are connected to an external circuit unit 201 (see FIG. 8).

  The sensor body 5 includes an outer metal fitting 10, an inner metal fitting 30, a discharge electrode body 70, and an auxiliary electrode body 80 (see FIG. 3). Among these, the outer metal fitting 10 has a cylindrical shape extending in the axial direction GH, and surrounds the inner circumference of the inner metal fitting 30 in a state of being insulated from the inner metal fitting 30. The outer metal fitting 10 is attached to the pipe mounting portion EPT of the exhaust pipe EP, which is set to the ground potential PVE, and is set to the ground potential PVE (see FIGS. 5 and 8). The outer metal fitting 10 includes an outer first metal fitting 11 and a second outer metal fitting 15 welded to the rear end side GK of the outer first metal fitting 11.

  As shown in FIG. 6, the outer first metal fitting 11 is a cylindrical member made of stainless steel. The outer first metal fitting 11 includes a cylindrical first main body portion 11a, an annular metal fitting mounting portion 11c which is located on the distal end side GS of the first main body portion 11a and bulges radially outward, and a metal fitting mounting portion 11c. And an annular outer holding portion 11b (see FIG. 4) that bulges inward in the radial direction, and a cylindrical tip portion 11d that extends from the outer holding portion 11b to the tip side GS. The metal fitting attachment portion 11c has an annular sensor seat surface portion 11f located on the tip side GS (see FIGS. 3 and 4). Moreover, the gas introduction window 11h which consists of a notch of planar view U shape opened to the front end side GS is formed in the front-end | tip part 11d (refer FIGS. 3-6).

  Of the sensor main body 5 of the particle sensor 1, the portion from the metal fitting attachment portion 11c of the outer first metal fitting 11 to the tip side GS (the portion of the tip side GS including the metal fitting attachment portion 11c) is the aforementioned sensor main body tip portion. 6, the portion from the first main body portion 11a to the rear end side GK of the outer first metal fitting 11 (the rear end side GK portion including the first main body portion 11a) is the sensor main body rear end portion 7 described above.

  A fastening member 60 to be described later is rotatably arranged with respect to the outer first metal fitting 11 around the first main body portion 11a in the radial direction. The outer holding portion 11b is a portion that holds a cylindrical insulating spacer 47 made of alumina between the inner holding portion 51f of the inner metal fitting 30 (holder 50), which will be described later, and an annular first plate packing. 48 is engaged with the insulating spacer 47 through the entire circumference from the front end side GS.

  On the other hand, the metal fitting part 11c is a part that is engaged with the fastening member 60 and is attached to the pipe attachment part EPT of the exhaust pipe EP, as will be described later. Further, as will be described later, the sensor seat surface portion 11f indirectly contacts the tube seat surface portion EPZ of the tube mounting portion EPT via an annular copper gasket 18.

  As shown in FIG. 6, the second outer metal fitting 15 is a cylindrical member made of stainless steel, and has a first through hole 15b and a second through hole 15c extending in the axial direction GH (see FIG. 3). The front end of the second outer metal fitting 15 is inserted into the first main body 11a of the outer first metal fitting 11 from the rear end side GK and is welded over the entire circumference. The second outer metal fitting 15 is provided with a cylindrical air intake portion 15t that protrudes toward the rear end side GK (see FIGS. 4 and 6). The air intake portion 15 t is a part for taking in the air AR from the outside to the inside of the sensor main body 5, located on the rear end side GK of the sensor body 5 in the axial direction GH.

  An air tube 40 is connected to the air intake portion 15t, and is fixed by caulking with a cylindrical mounting ring 16. The air tube 40 extends from the air intake portion 15t toward the rear end side GK, and the other end portion of the air tube 40 is connected to a pressure feed pump 330 installed outside (see FIG. 8). Thereby, clean air (compressed air) AR generated by the pressure pump 330 is supplied into the second outer metal fitting 15 (in the sensor body 5) through the air tube 40.

  Further, two cables (the first cable 90 and the second cable 100) extend from the inside of the second outer metal fitting 15 toward the rear end side GK. Specifically, as shown in FIG. 3, a first O-ring 23 and a cylindrical first retainer 25 are inserted into the rear end side GK of the first through hole 15 b of the second outer metal fitting 15. The first cable 90 is held by the second outer metal fitting 15 in such a manner that the first cable 90 is inserted therethrough.

  The 1st retainer 25 has the cylindrical insertion part 25c located in the front end side GS of the axial direction GH, and the cylindrical crimping connection part 25b located in the rear end side GK rather than this. Among these, the insertion portion 25 c is a portion that is inserted into the first through hole 15 b of the second outer metal fitting 15 from the rear end side GK. Further, the caulking connection part 25 b is a part connected to the tip end part 97 b of the first ground potential wiring 97. The caulking connection portion 25b is caulked inward in the radial direction with the distal end portion 97b of the first ground potential wiring 97 inserted and disposed therein, thereby being connected to the distal end portion 97b of the first ground potential wiring 97. Conducted in pressure contact. Of the first retainer 25, a portion on the rear end side GK from the insertion portion 25 c (a portion including the caulking connection portion 25 b) is disposed so as to protrude from the rear end of the second outer metal fitting 15 to the outside of the second outer metal fitting 15. Has been.

  Furthermore, the 2nd O ring 24 and the cylindrical 2nd retainer 26 are inserted in the rear end side GK of the 2nd through-hole 15c of the 2nd outer metal fitting 15, The aspect by which the 2nd cable 100 was penetrated by these is inserted. Thus, the second cable 100 is held by the second outer metal fitting 15.

  The 2nd retainer 26 has the cylindrical insertion part 26c located in the front end side GS of the axial direction GH, and the cylindrical crimping connection part 26b located in the rear end side GK rather than this. Among these, the insertion portion 26 c is a portion that is inserted into the second through hole 15 c of the second outer metal fitting 15 from the rear end side GK. The caulking connection part 26 b is a part connected to the tip part 107 b of the second ground potential wiring 107. The caulking connection portion 26b is caulked inward in the radial direction with the distal end portion 107b of the second ground potential wiring 107 inserted and disposed therein, thereby being connected to the distal end portion 107b of the second ground potential wiring 107. Conducted in pressure contact. Of the second retainer 26, a portion of the rear end side GK from the insertion portion 26 c (a portion including the caulking connection portion 26 b) is disposed so as to protrude from the rear end of the second outer metal fitting 15 to the outside of the second outer metal fitting 15. Has been.

Next, the first cable 90 and the second cable 100 will be described. FIG. 7 is a cross-sectional view of the first cable 90 and the second cable 100.
The first cable 90 is a triaxial cable, and as shown in FIGS. 3 and 7, a discharge potential wiring 91 made of a copper core wire and a cylinder made of a braid knitted with a copper fine wire located on the outer side in the radial direction thereof. A first reference potential wiring 93 and a first reference potential wiring 93 that surrounds the discharge potential wiring 91 in the radial direction and is disposed between the discharge potential wiring 91 and the first reference potential wiring 93 to insulate them from each other. And an insulating layer 92. Further, the first cable 90 surrounds the periphery of the first reference potential wiring 93 in the radial direction, and includes a cylindrical first ground potential wiring 97 formed of a braided copper wire and a radial direction of the first reference potential wiring 93. An insulating second insulator layer 95 made of PTFE is provided surrounding the periphery and disposed between the first reference potential wiring 93 and the first ground potential wiring 97 to insulate them.

  Furthermore, as shown in FIG. 7, the first cable 90 is in close contact with the radial inner surface 95 b of the second insulator layer 95 to cover the radial inner surface 95 b and is in contact with the first reference potential wiring 93. A semiconductive coating layer 94; and a second semiconductive coating layer 96 that is in close contact with the radial outer surface 95c of the second insulator layer 95 to cover the radial outer surface 95c and contacts the first ground potential wiring 97. . The first semiconductive coating layer 94 and the second semiconductive coating layer 96 are made of carbon-containing FEP and have semiconductivity (conductivity). Further, the first cable 90 has an insulating outer insulating coating layer 98 made of FEP that covers the periphery of the first ground potential wiring 97 in the radial direction. As described above, the first cable 90 doublely surrounds the discharge potential wiring 91 with the first reference potential wiring 93 and the first ground potential wiring 97, and the first reference potential wiring 93 with the first ground potential wiring 97. It is a double siege cable that surrounds the cable.

  In the first cable 90, the distal end portion 91 b of the discharge potential wiring 91 extends in the distal end side (upward in FIG. 3) of the first cable 90 from the distal end of the first insulator layer 92. It is exposed outside. As shown in FIG. 3, the distal end portion 91 b of the discharge potential wiring 91 is connected to the rear end portion (exposed portion) of the first extension portion 71 of the discharge electrode body 70 by caulking connection with the first connection terminal 77. Has been. As a result, the discharge potential wiring 91 is conducted to the discharge electrode body 70.

  Note that the discharge potential connection portion 111 is a portion where the front end portion 91 b of the discharge potential wiring 91 and the rear end portion (exposed portion) of the first extension portion 71 of the discharge electrode body 70 are connected through the first connection terminal 77. (See FIG. 3). The discharge potential connection portion 111 is constituted by the tip end portion 91 b of the discharge potential wiring 91, the rear end portion (exposed portion) of the first extension portion 71 of the discharge electrode body 70, and the first connection terminal 77.

  Further, the tip end portion 93 b of the first reference potential wiring 93 is exposed to the outside of the first cable 90 in a form extending from the tip end of the first semiconductive coating layer 94 to the tip end side of the first cable 90. As shown in FIG. 3, the distal end portion 93b of the first reference potential wiring 93 is connected to the inner cylinder 31 of the inner metal fitting 30 (reference potential member). Thereby, the first reference potential wiring 93 is electrically connected to the inner metal fitting 30 (reference potential member).

  Further, the tip end portion 97 b of the first ground potential wiring 97 is exposed to the outside of the first cable 90 in a form extending from the tip end of the outer insulating coating layer 98 to the tip end side of the first cable 90. As shown in FIG. 3, the tip portion 97 b of the first ground potential wiring 97 is formed by a caulking connection portion 25 b of the cylindrical first retainer 25 inserted into the first through hole 15 b of the second outer metal fitting 15. It fits externally and is connected to the second outer metal fitting 15 (ground potential member) through the first retainer 25. Thereby, the first ground potential wiring 97 is electrically connected to the outer metal fitting 10 (ground potential member).

  Next, the second cable 100 will be described. This second cable 100 is also a triaxial cable, and, as shown in FIGS. 3 and 7, is composed of an auxiliary potential wiring 101 made of a copper core wire and a braid knitted on the outer side in the radial direction and knitted with a copper fine wire. A cylindrical second reference potential wiring 103 and a first PTFE made of PTFE that surrounds the periphery of the auxiliary potential wiring 101 in the radial direction and is disposed between the auxiliary potential wiring 101 and the second reference potential wiring 103 to insulate them from each other. 1 insulator layer 102. Further, the second cable 100 surrounds the circumference of the second reference potential wiring 103 in the radial direction, and has a cylindrical second ground potential wiring 107 made of a braided copper thin wire and a radial direction of the second reference potential wiring 103. An insulating second insulator layer 105 made of PTFE is provided surrounding the periphery and disposed between the second reference potential wiring 103 and the second ground potential wiring 107 to insulate them.

  Further, as shown in FIG. 7, the second cable 100 is in close contact with the radial inner surface 105 b of the second insulator layer 105 to cover the radial inner surface 105 b and is in contact with the second reference potential wiring 103. A semiconductive coating layer 104; and a second semiconductive coating layer 106 that is in close contact with the radial outer surface 105c of the second insulator layer 105 to cover the radial outer surface 105c and contacts the second ground potential wiring 107. . The first semiconductive coating layer 104 and the second semiconductive coating layer 106 are made of carbon-containing FEP and have semiconductivity (conductivity). Further, the second cable 100 has an insulating outer insulating coating layer 108 made of FEP that covers the periphery of the second ground potential wiring 107 in the radial direction. As described above, the second cable 100 double surrounds the auxiliary potential wiring 101 with the second reference potential wiring 103 and the second ground potential wiring 107, and the second reference potential wiring 103 with the second ground potential wiring 107. It is a double siege cable that surrounds the cable.

  In the second cable 100, the distal end portion 101 b of the auxiliary potential wiring 101 extends to the distal end side (upward in FIG. 3) of the second cable 100 from the distal end of the first insulator layer 102, and the second cable 100. It is exposed outside. As shown in FIG. 3, the front end portion 101 b of the auxiliary potential wiring 101 is connected to the rear end portion (exposed portion) of the second extension portion 81 of the auxiliary electrode body 80 by caulking connection with the second connection terminal 87. Has been. Thereby, the auxiliary potential wiring 101 is electrically connected to the auxiliary electrode body 80.

  A portion where the front end portion 101 b of the auxiliary potential wiring 101 and the rear end portion (exposed portion) of the second extension portion 81 of the auxiliary electrode body 80 are connected through the second connection terminal 87 is referred to as the auxiliary potential connection portion 112. (See FIG. 3). The auxiliary potential connection portion 112 includes a front end portion 101 b of the auxiliary potential wiring 101, a rear end portion of the second extension portion 81 of the auxiliary electrode body 80, and a second connection terminal 87.

  Further, the distal end portion 103 b of the second reference potential wiring 103 is exposed to the outside of the second cable 100 in a form extending from the distal end side of the second cable 100 to the distal end side of the first semiconductive coating layer 104. The tip 103b of the second reference potential wiring 103 is connected to the inner cylinder 31 of the inner metal fitting 30 (reference potential member) as shown in FIG. Accordingly, the second reference potential wiring 103 is electrically connected to the inner metal fitting 30 (reference potential member).

  Further, the tip portion 107 b of the second ground potential wiring 107 is exposed to the outside of the second cable 100 in a form extending to the tip side of the second cable 100 rather than the tip of the outer insulating coating layer 108. As shown in FIG. 3, the distal end portion 107 b of the second ground potential wiring 107 is formed by a caulking connection portion 26 b of the cylindrical second retainer 26 inserted into the second through hole 15 c of the second outer metal fitting 15. It fits externally and is connected to the second outer metal fitting 15 (ground potential member) through the second retainer 26. As a result, the second ground potential wiring 107 is electrically connected to the outer metal fitting 10 (ground potential member).

  Next, the fastening member 60 will be described. The fastening member 60 is rotatably arranged around the sensor body rear end portion 7 in the radial direction, specifically, around the radial direction of the first main body portion 11 a of the outer first metal fitting 11. The fastening member 60 is a cylindrical member including a male screw portion 61 and a tool engaging portion 63 located on the rear end side GK of the male screw portion 61 (see FIGS. 3 to 6). Of these, the male screw portion 61 is a cylindrical portion having a male screw formed on the outer periphery. On the other hand, the tool engaging portion 63 is a portion having a hexagonal outer shape, and is a portion to which the tool is engaged when the sensor main body portion 5 is attached to the pipe attachment portion EPT of the exhaust pipe EP.

  As shown in FIG. 5, the pipe mounting portion EPT of the exhaust pipe EP includes an annular pipe seat surface portion EPZ, and extends from the tube seat surface portion EPZ to the outside in the radial direction of the exhaust pipe EP, and a female screw is formed on the inner periphery. And a cylindrical female screw portion EPY. When the sensor main body 5 of the particulate sensor 1 is attached to the pipe attachment portion EPT of the exhaust pipe EP, the male screw 61 of the fastening member 60 is screwed into the female screw portion EPY of the pipe attachment portion EPT. The front end of the part 61 engages with the metal mounting part 11c of the outer first metal fitting 11 in the sensor main body front end part 6, and the sensor main body 5 including the outer first metal fitting 11 moves to the front end GS.

  And the sensor seat surface part 11f located in the front end side GS among the metal fitting attachment parts 11c contacts the pipe seat surface part EPZ of the pipe attachment part EPT indirectly through the gasket 18. The metal fitting part 11c is sandwiched between the male thread part 61 of the fastening member 60 and the pipe seat surface part EPZ of the pipe attachment part EPT, and the outer first metal part 11 is held by the pipe attachment part EPT, and the pipe attachment part EPT. The sensor body 5 is fixed in an airtight manner. Since the fastening member 60 is disposed so as to be rotatable with respect to the sensor main body 5, the mounting of the sensor main body 5 on the pipe mounting portion EPT is fastened without rotating the sensor main body 5. This can be done by rotating only the member 60.

  Next, the inner metal fitting 30 will be described. As shown in FIGS. 3 and 4, the inner metal fitting 30 has an outer cylindrical shape extending in the axial direction GH. As described above, the inner metal fitting 30 is separated from the outer metal fitting 10 and insulated from the outer metal fitting 10 in the radial direction. It is arranged in the state. The inner metal fitting 30 is connected to the external circuit unit 201 through the first reference potential wiring 93 of the first cable 90 and the second reference potential wiring 103 of the second cable 100, and has a reference potential PV1 different from the ground potential PVE. The The inner metal fitting 30 is configured by an inner cylinder 31, a holder 50, a nozzle member 35, a mixing and discharging member 37, and a lid member 39, which are arranged in order from the rear end side GK to the front end side GS (FIG. 3). FIG. 4 and FIG. 6).

  The holder 50 has a cylindrical holder body 51 made of stainless steel and a cylindrical portion 55 made of stainless steel and extending in the axial direction GH (see FIGS. 9 to 15). The holder 50 is fixed in such a manner that the rear end side GK portion is fitted in the distal end portion of the inner cylinder 31 (see FIG. 4).

  FIG. 9 is a side view of the holder 50. FIG. 10 is a top view of the holder 50 (a plan view of the holder 50 viewed from the rear end side GK). FIG. 11 is a bottom view of the holder 50 (a plan view of the holder 50 on the tip side GS). 12 is a cross-sectional view taken along the line DD of FIG. 13 is a cross-sectional view taken along line EE in FIG. FIG. 14 is an enlarged view of a portion B in FIG. However, in FIG. 14, some of the members located near the holder 50 are not shown. FIG. 15 is a perspective view of the holder 50 positioned in the sensor main body 5 of the particle sensor 1 as viewed obliquely from the rear end side GK. However, in FIG. 15, the illustration of members located near the holder 50 is partially omitted.

  The holder main body 51 is a hole that penetrates the holder main body 51 in the axial direction GH, and is a hole that penetrates the holder main body 51 in the axial direction GH. And the second insertion hole 53 into which the auxiliary electrode body 80 is inserted. Furthermore, the holder main body 51 has a through hole 56 that penetrates the holder main body 51 in the axial direction GH.

  A cylindrical cylindrical portion 55 is press-fitted and fixed in the through hole 56 of the holder main body 51 (see FIG. 13). The cylindrical portion 55 has a hollow cylindrical shape extending in the axial direction GH, and a part (a portion on the rear end side GK) of the cylindrical portion 55 extends from the rear end surface 51c located at the rear end of the axial direction GH in the holder main body 51. Projecting to the rear end side GK in the direction GH. The tubular portion 55 has a hollow portion 55b (hollow hole) that penetrates the tubular portion 55 in the axial direction GH.

  In the holder 50 of this embodiment, the hollow part 55b of the cylindrical part 55 and the through hole 56 of the holder main body part 51 constitute a vent hole 57 that penetrates the holder 50 in the axial direction GH. The air holes 57 are air holes through which the air AR introduced into the sensor body 5 through the air intake portion 15t flows from the rear end side GK to the front end side GS in the axial direction GH through the air holes 57 ( 4 and 13). Therefore, the air AR introduced into the sensor body 5 through the air intake 15t is the rear end side GK of the vent hole 57 of the holder 50 (specifically, the axial direction GH of the hollow portion 55b of the cylindrical portion 55). The rear end side vent opening 55d) that opens to the rear end side GK is introduced into the vent hole 57, flows in the vent hole 57 from the rear end side GK to the front end side GS in the axial direction GH, and the vent hole 57. From the front end side GS (opening at the front end side of the through hole 56 of the holder main body 51) to the outside of the vent hole 57.

  Further, the first insertion hole 52 is opened to the rear end side GK in the axial direction GH and has an adhesive accommodating portion 52b (adhesive accommodating space) for accommodating the adhesive 59, and the axial direction GH more than the adhesive accommodating portion 52b. The insertion hole main body portion 52c is positioned on the distal end side GS of the first GS (see FIGS. 10 to 12). By making the inner diameter (hole diameter) of the insertion hole main body 52c smaller than the inner diameter (hole diameter) of the adhesive accommodating part 52b, the first insertion hole 52 is a two-stage hole having a step. The insertion hole main body 52c has a cylindrical shape that extends straight in the axial direction GH, and is open to the distal end GS of the holder main body 51 (see FIG. 12).

  On the other hand, the adhesive accommodating part 52b has a cylindrical shape extending in the axial direction GH in an oval shape in plan view, and has a rear end accommodating opening 52d that opens to the rear end side GK in the axial direction GH. The rear end side accommodation opening 52 d of the adhesive accommodating portion 52 b is open to the rear end surface 51 c of the holder main body 51. The adhesive 59 is accommodated (filled) inside the adhesive accommodating portion 52b in a state where the discharge electrode body 70 is inserted (inserted) (see FIGS. 14 and 15). Thereby, since the discharge electrode body 70 is adhered to the holder 50, the discharge electrode body 70 can be fixed to the holder 50. The adhesive 59 does not fill the entire adhesive accommodating portion 52b, and the surface 59b (upper surface) of the adhesive 59 is more than the rear end side accommodating opening 52d (the rear end surface 51c of the holder main body 51). It is located on the tip side GS (downward).

  Also, the second insertion hole 53 opens to the rear end side GK in the axial direction GH and has an adhesive accommodating portion 53b (adhesive accommodating space) for accommodating the adhesive 59, and the axial direction GH more than the adhesive accommodating portion 53b. The insertion hole main body portion 53c is positioned on the distal end side GS of the first GS (see FIGS. 10 to 12). By making the inner diameter (hole diameter) of the insertion hole main body 53c smaller than the inner diameter (hole diameter) of the adhesive accommodating part 53b, the second insertion hole 53 is also a two-stage hole having a step. The insertion hole main body 53c has a cylindrical shape extending straight in the axial direction GH, and is open to the distal end GS of the holder main body 51 (see FIG. 12).

  On the other hand, the adhesive accommodating part 53b has a cylindrical shape extending in the axial direction GH in an oblong shape in plan view, and has a rear end side accommodating opening 53d that opens to the rear end side GK in the axial direction GH. The rear end side accommodation opening 53 d of the adhesive accommodating portion 53 b is open to the rear end surface 51 c of the holder main body portion 51. An adhesive 59 is accommodated (filled) inside the adhesive accommodating portion 53b in a state where the auxiliary electrode body 80 is inserted (inserted) (see FIGS. 14 and 15). Thereby, since the auxiliary electrode body 80 is adhered to the holder 50, the auxiliary electrode body 80 can be fixed to the holder 50. The adhesive 59 does not fill the entire adhesive accommodating portion 53b, and the surface 59b (upper surface) of the adhesive 59 is more than the rear end side accommodating opening 53d (the rear end surface 51c of the holder main body 51). It is located on the tip side GS.

  Therefore, in this embodiment, the rear end side vent opening 55d that opens to the rear end side GK of the axial direction GH in the vent hole 57 of the holder 50 (the rear end of the axial direction GH of the hollow portion 55b of the cylindrical portion 55). The portion opened to the side GK) is closer to the rear end side GK in the axial direction GH than the rear end side receiving openings 52d, 53d opening to the rear end side GK in the axial direction GH of the adhesive accommodating portions 52b, 53b. Is located (see FIG. 12).

  By the way, in this embodiment, since the sensor main body 5 of the particulate sensor 1 is used by being attached to the exhaust pipe EP of the engine ENG, the inside of the sensor main body 5 becomes high temperature. For this reason, it is preferable to use an adhesive having heat resistance as the adhesive 59. Therefore, in this embodiment, as the adhesive 59, a heat-resistant inorganic adhesive (adhesive containing a refractory ceramic and an inorganic polymer) is used. More specifically, Aron Ceramic C (trade name) manufactured by Toa Gosei Co., Ltd. is used. Accordingly, the discharge electrode body 70 and the auxiliary electrode body 80 can be maintained in a state of being bonded to the holder 50 even under a high temperature use environment, and the discharge electrode body 70 and the auxiliary electrode body 80 are fixed to the holder 50. Can be maintained.

  The holder 50 has an annular shape that bulges radially outward from the outer peripheral surface thereof, and has an inner holding portion 51f that holds the insulating spacer 47 between the outer holding portion 11b of the outer metal fitting 10 ( (Refer to FIGS. 10-12). The inner holding portion 51f is engaged with the insulating spacer 47 over the entire circumference from the rear end side GK via the annular second plate packing 49, and is insulated from the outer holding portion 11b of the outer first metal fitting 11. The spacer 47 is held therebetween (see FIGS. 3 and 4).

  The nozzle member 35 is a member made of stainless steel having a cylindrical shape, and is fixed to the front end portion of the holder 50 from the rear end side GK. The nozzle member 35 is located on the tip side GS in the axial direction GH with respect to the holder 50, and has a discharge counter electrode portion 35 d serving as a counter electrode of the discharge electrode body 70. The discharge counter electrode portion 35d has a discharge space DS in which a needle-like tip 73, which is the tip of the discharge electrode body 70, is disposed, and the discharge electrode body 70 is in contact with the needle-like tip 73 of the discharge electrode body 70 in the discharge space DS. An air discharge is generated between them.

  Specifically, the discharge counter electrode portion 35d includes a nozzle portion 35a and a rear end side cylindrical wall portion 35c located on the rear end side GK with respect to the nozzle portion 35a. Among these, the nozzle portion 35a has a tapered inner surface that decreases in diameter as it goes from the rear end side GK to the front end side GS in the axial direction GH, and at the front end portion thereof, the discharge space DS and a cylindrical mixing described later are provided. A communication hole 35f that communicates with the region MX1 (mixing space) is formed. The communication hole 35f is an orifice hole for injecting the air AR from the discharge space DS to the cylindrical mixing region MX1 (mixing space), and has a minute inner diameter.

  Furthermore, the nozzle member 35 has a cylindrical distal end side cylindrical wall portion 35b located on the distal end side GS in the axial direction GH with respect to the discharge counter electrode portion 35d. This tip side cylindrical wall portion 35b constitutes a cylindrical mixing space (referred to as cylindrical mixing region MX1) in which ions CP and exhaust gas EG (measurement gas) generated by air discharge are introduced and mixed. ing. The cylindrical mixing region MX1 (mixing space) communicates with the discharge space DS through the communication hole 35f of the nozzle portion 35a. In addition, the distal end side cylindrical wall portion 35b is provided with one gas intake port 35h that opens toward the downstream side of the exhaust pipe EP and is connected to the cylindrical mixing region MX1 (see FIGS. 3 and 4). ). Exhaust gas EG (gas to be measured) flowing through the exhaust pipe EP is introduced into the cylindrical mixing region MX1 (mixing space) through the gas inlet 35h.

  In the fine particle sensor 1 of the present embodiment, the air AR introduced into the sensor main body 5 through the air intake portion 15t flows in the sensor main body 5 from the rear end side GK to the front end side GS in the axial direction GH. After that, a flow path is formed that passes through the vent hole 57 of the holder 50 from the rear end side GK of the axial direction GH to the front end side GS and is introduced into the discharge space DS. Furthermore, in the particulate sensor 1, the air AR introduced into the discharge space DS is introduced from the discharge space DS into the cylindrical mixing region MX1 (mixing space) through the communication hole 35f of the nozzle portion 35a, whereby the discharge space DS. The ion CP generated in the inside constitutes a flow path into which the air AR is introduced into the cylindrical mixing region MX1 (mixing space) (see FIGS. 3, 4, 8, and 16).

  The mixed discharge member 37 is a stainless steel member having an outer cylindrical shape, and is fitted into the front end portion of the nozzle member 35 from the rear end side GK and fixed thereto. The mixed discharge member 37 includes a discharge rear end portion 37a positioned on the rear end side GK, and a cylindrical tube wall portion 37b extending from the peripheral edge of the discharge rear end portion 37a to the front end side GS. Among them, the discharge rear end portion 37a is provided with a collecting electrode 37c bulging radially inward, and the collecting electrode 37c forms a slit-shaped mixed region MX2 that is a slit-shaped space. Yes. The slit-shaped mixing area MX2 communicates with the aforementioned cylindrical mixing area MX1 (see FIG. 4).

On the other hand, a gas discharge path EX which is a cylindrical space is formed in the cylindrical wall portion 37b. This gas discharge path EX communicates with the slit-shaped mixing region MX2. Further, the cylindrical wall portion 37b is provided with one gas discharge port 37h that opens toward the downstream side of the exhaust pipe EP and is connected to the gas discharge path EX (see FIGS. 3 and 4).
The lid member 39 is a disk-shaped member made of stainless steel, and closes the distal end side GS of the mixed discharge member 37.

  The inner cylinder 31 is a cylindrical member made of stainless steel having a cylindrical shape extending in the axial direction GH (see FIGS. 3, 4, and 6). The inner cylinder 31 includes a semi-cylindrical first member 32 and a semi-cylindrical second member 34, and is formed by combining the first member 32 and the second member 34. The first member 32 and the second member 34 have the same shape. Specifically, the first member 32 and the second member 34 have a semi-cylindrical shape in which the inner cylinder 31 is divided into two equal parts in the axial direction GH.

  The first member 32 has a semi-cylindrical separator covering portion 32b and a semi-columnar contact conducting portion 32c located on the rear end side GK. Among these, the contact conduction part 32c has a cylindrical vent that penetrates the contact conduction part 32c in the axial direction GH. The second member 34 also has the same form as the first member 32.

  An electrically insulating separator 41 is accommodated in the inner cylinder 31 that is a combination of the first member 32 and the second member 34 described above (see FIGS. 3 and 4). Specifically, the separator 41 is accommodated in a cylindrical portion (cylindrical separator accommodating space) formed by the separator covering portion 32 b of the first member 32 and the separator covering portion of the second member 34. Thereby, the separator 41 is held by the inner cylinder 31.

The first reference potential wiring 93 and the second reference potential wiring are respectively formed in the two cylindrical contact surfaces formed by the contact conduction portion 32c of the first member 32 and the contact conduction portion of the second member 34. 103 and is arranged in contact with each other. As a result, the inner cylinder 31 comes into contact with the first reference potential wiring 93 and the second reference potential wiring 103 and becomes conductive.
The inner cylinder 31 is fixed inside the sensor body 5. Specifically, the front end portion of the inner cylinder 31 is externally fitted to the rear end portion of the holder 50, and this outer fitting portion (the front end portion of the inner cylinder 31 and the rear end portion of the holder 50) is welded, The tip of the inner cylinder 31 is fixed inside the sensor body 5.

  Further, the inner cylinder 31 is held by the metal holding member 42 in a state where the rear end portion is inserted and fixed inside the cylindrical metal holding member 42. Accordingly, the state in which the first member 32 and the second member 34 are combined to form the cylindrical inner cylinder 31 can be maintained, and the rear end portion of the inner cylinder 31 is fixed inside the sensor body 5. Is done. The rear end portion of the inner cylinder 31 and the metal holding member 42 are fixed by welding.

  The metal holding member 42 has a cylindrical side wall portion 42b extending in the axial direction GH and an annular bottom portion 42c connected to the rear end portion of the side wall portion 42b (see FIGS. 4 and 6). A circular vent 42d is provided in the bottom 42c. The air (compressed air) AR supplied into the second outer metal fitting 15 circulates from the rear end side GK of the axial direction GH to the front end side GS through the vent hole 42d of the metal holding member 42. To do.

  The rear end portion of the metal holding member 42 is disposed in a cylindrical insulating member 43 that is a combination of two semi-cylindrical insulating members 43 b and 43 c and is held by the insulating member 43. Further, an annular rubber member 44 is disposed on the rear end side GK of the insulating member 43, and a C-shaped washer 45 is disposed on the rear end side GK (see FIGS. 4 and 6). .

  The separator 41 is made of an electrically insulating member (ceramic mainly composed of alumina) and has a column shape extending in the axial direction GH (see FIGS. 3, 4, and 6). The separator 41 includes a first through hole 41b and a second through hole 41c that penetrate the separator 41 in the axial direction GH. The first through-hole 41b and the second through-hole 41c are separate and independent through-holes, and are separated in a direction (left-right direction in FIG. 3) perpendicular to the axial direction GH across the wall portion of the separator 41.

  Inside the first through hole 41 b of the separator 41, the distal end portion of the first cable 90 and the first extending portion 71 of the discharge electrode body 70 are inserted. In the first through hole 41 b, the discharge potential connection portion 111 (the front end portion 91 b of the discharge potential wiring 91 and the rear end portion of the first extension portion 71 of the discharge electrode body 70 are connected to the first connection terminal 77. The site | part connected through is arrange | positioned.

  Further, the distal end portion of the second cable 100 and the second extending portion 81 of the auxiliary electrode body 80 are inserted into the second through hole 41 c of the separator 41. In the second through hole 41 c, the auxiliary potential connection portion 112 (the tip portion 101 b of the auxiliary potential wiring 101 and the rear end portion of the second extension portion 81 of the auxiliary electrode body 80 are connected to the second connection terminal 87. The site | part connected through is arrange | positioned.

As a result, the discharge potential connection portion 111 that becomes the discharge potential PV2 and the auxiliary potential connection portion 112 that becomes the auxiliary potential PV4 are electrically insulated by the separator 41.
Therefore, the particulate sensor 1 of the present embodiment is a particulate sensor in which the discharge potential connection portion 111 and the auxiliary potential connection portion 112 are appropriately electrically insulated by the separator 41.

  Next, the discharge electrode body 70 will be described. The discharge electrode body 70 includes a discharge electrode main body portion 70A made of a tungsten wire, and a first insulating pipe 75 positioned around the discharge electrode main body portion 70A. As shown in FIG. 3, the discharge electrode main body portion 70 </ b> A includes a first extending portion 71 having a straight rod shape and a needle-like tip portion 73 that is located at the tip portion and has a needle-like shape. The discharge electrode main body 70A (needle tip 73) is connected to the external circuit unit 201 through the discharge potential wiring 91 of the first cable 90, and is set to the discharge potential PV2. The discharge potential PV2 is a positive high potential with respect to the reference potential PV1, and has a peak potential of 1 to 2 kV.

  The first extending portion 71 is covered with a cylindrical first insulating pipe 75 made of an insulating ceramic around its radial direction. However, the rear end portion of the first extending portion 71 is exposed without being covered with the first insulating pipe 75 in order to be connected to the front end portion 91 b of the discharge potential wiring 91 by the first connection terminal 77.

  On the other hand, the needle-shaped tip part 73 is disposed in the discharge space DS formed by the discharge counter electrode part 35d, and constitutes an ion source together with the discharge counter electrode part 35d. That is, as will be described later, the discharge counter electrode portion 35d having the reference potential PV1 and the needle-like tip portion 73 having the discharge potential PV2 generate an air discharge between them, and fine particles are generated by the air discharge. Ions CP to be attached to S are generated.

  Next, the auxiliary electrode body 80 will be described. The auxiliary electrode body 80 includes a supplementary electrode main body portion 80A made of stainless steel and a cylindrical second insulating pipe 85 positioned around the supplementary electrode main body portion 80A. As shown in FIG. 3, the auxiliary electrode body 80 includes a straight rod-shaped second extending portion 81, a bent-back portion 82 bent back in a U shape at the front end side GS, and a rear end from the bent-back portion 82. The auxiliary electrode portion 83 has a shape that extends toward the side GK and has a needle-like tip.

  The periphery of the second extending portion 81 is covered with a cylindrical second insulating pipe 85 made of an insulating ceramic. However, the rear end portion of the second extending portion 81 is exposed without being covered with the second insulating pipe 85 in order to be connected to the front end portion 101 b of the auxiliary potential wiring 101 by the second connection terminal 87. Further, the bent-back portion 82 is disposed in the gas discharge path EX.

  On the other hand, the auxiliary electrode portion 83 is disposed in the slit-shaped mixed region MX2. The auxiliary electrode body 80 (auxiliary electrode portion 83) is connected to the external circuit portion 201 through the auxiliary potential wiring 101 of the second cable 100, and is set to the auxiliary potential PV4. The auxiliary potential PV4 is a positive high potential with respect to the reference potential PV1, but is lower than the peak potential (1-2 kV) of the discharge potential PV2, for example, a potential of DC 100-200V.

  By the way, in the particulate sensor 1 of this embodiment, the separator 41 has the groove part 41f extended in the axial direction GH in the outer peripheral surface, as shown in FIG. The groove portion 41f extends from the front end to the rear end of the separator 41 in the axial direction GH in a form in which a part of the outer peripheral surface 41d of the separator 41 is recessed radially inward. And in the state which the outer periphery of the separator 41 was covered with the inner cylinder 31, the ventilation hole AH enclosed by the groove part 41f of the separator 41 and the inner peripheral surface of the inner cylinder 31 is formed (refer FIG. 4). Further, the vent hole AH communicates with the vent hole 57 of the holder 50.

  Therefore, in the fine particle sensor 1 of the present embodiment, even if the separator 41 is provided between the air intake portion 15t and the discharge space DS, the air AR taken into the sensor body 5 through the air intake portion 15t is appropriately used. In addition, it can be introduced into the discharge space DS on the tip side in the axial direction GH in the sensor main body 5.

  By the way, during operation of the engine ENG, the exhaust pipe EP to which the sensor main body 5 is attached vibrates, and this vibration is contained in the adhesive accommodating portions 52b and 53b of the holder 50. May be transmitted to. Due to this vibration, a crack or the like is generated on the surface 59b of the adhesive 59 accommodated in the adhesive accommodating portions 52b and 53b, and a part of the adhesive 59 is crushed into a powder form. The resulting adhesive 59 (adhesive 59 powder) may be discharged to the outside of the adhesive accommodating portions 52b and 53b.

  As described above, in the particulate sensor 1, the air AR introduced into the sensor body 5 through the air intake 15t passes through the sensor body 5 from the rear end side GK to the front end side GS in the axial direction GH. (From the top to the bottom in FIGS. 3 to 5), and then introduced into the vent hole 57 of the holder 50. For this reason, conventionally, in such a fine particle sensor, there has been a possibility that the powder of the adhesive released to the outside of the adhesive accommodating portion may enter the vent hole of the holder together with the air. Then, the communication powder 35f that connects the discharge space DS and the cylindrical mixing region MX1 is closed by the adhesive powder, and the ions CP generated in the discharge space DS are introduced into the cylindrical mixing region MX1 together with the air AR. There was a risk that it would be impossible.

  On the other hand, in the fine particle sensor 1 of the present embodiment, as described above, the rear end side vent opening 55d that opens to the rear end side GK in the axial direction GH in the vent hole 57 of the holder 50 has the adhesive accommodating portion. The rear end side GK in the axial direction GH (upward in FIGS. 3 to 5 and FIGS. 12 to 14) than the rear end side accommodation openings 52 d and 53 d that open to the rear end side GK in the axial direction GH of 52 b and 53 b. ). Thereby, even when part of the adhesive 59 accommodated in the adhesive accommodating portions 52b and 53b is crushed and powder of the adhesive 59 is generated, the powder of the adhesive 59 is retained in the vent hole 57 of the holder 50. It becomes difficult to enter.

  The reason for this is that in the particulate sensor 1 of the present embodiment, the air AR introduced into the sensor body 5 through the air intake 15t passes through the sensor body 5 from the rear end side GK in the axial direction GH to the front end side. This is because it is configured to flow into the GS and then be introduced into the vent hole 57 of the holder 50. More specifically, the flow direction of the air AR in the sensor main body 5 is such that the rear end side GK (upward in FIGS. 3 to 5) of the axial direction GH is upstream and the front end side GS of the axial direction GH (FIG. 3). The holder 50 is defined as a direction from the rear end side GK to the front end side GS in the axial direction GH (a direction from the upper side to the lower side in FIGS. 3 to 5) with the downstream side in FIG. The rear end side vent opening 55d is located on the rear end side GK in the axial direction GH, that is, on the upstream side in the flow direction of the air AR, relative to the rear end accommodation openings 52d and 53d of the adhesive accommodating portions 52b and 53b. This is because they are arranged.

  Thereby, the powder of the adhesive 59 located in the adhesive accommodating portions 52b and 53b is less likely to flow from the rear end side accommodating opening portions 52d and 53d to the rear end side vent opening portion 55d (difficult to reach). It is difficult for the powder of the adhesive 59 to enter the ventilation hole 57 from the rear end side ventilation opening 55d. Further, even when the powder of the adhesive 59 is discharged from the rear-end-side accommodation openings 52d and 53d to the outside of the adhesive-receiving portions 52b and 53b due to vibrations or the like, the powder of the adhesive 59 is not removed from the rear-end side ventilation openings. It becomes difficult to flow to 55d (it is difficult to reach), and the powder of the adhesive 59 hardly enters the ventilation hole 57 from the rear end side ventilation opening 55d.

  As will be described later, the fine particle sensor 1 of the present embodiment generates an air discharge between the needle-shaped tip 73 of the discharge electrode body 70 and the discharge counter electrode portion 35d in the discharge space DS, and thereafter In the cylindrical mixing region MX1 (mixing space), the charged CP is generated by attaching the ions CP generated by the air discharge to the particles S included in the exhaust gas EG (measurement gas). Thereafter, the amount of fine particles S in the exhaust gas EG is detected based on the charge amount of the charged fine particles SC.

  On the other hand, in the fine particle sensor 1 of the present embodiment, as described above, the powder of the adhesive 59 is difficult to enter into the vent hole 57 of the holder 50. Therefore, the discharge space DS is caused by the powder of the adhesive 59. The communication hole 35f that communicates with the cylindrical mixing region MX1 is less likely to be blocked (clogged), and the ions CP generated in the discharge space DS can be introduced into the cylindrical mixing region MX1 together with the air AR. It becomes hard to happen that it becomes impossible. As a result, it is possible to reduce the problem that the charged fine particles SC cannot be generated properly, and to reduce the problem that the amount of the fine particles S in the exhaust gas EG cannot be detected properly.

Next, the electrical function and operation of the particulate sensor 1 will be described (see FIGS. 8 and 16). By driving the external circuit portion 201, the nozzle portion 35a (discharge counter electrode portion 35d) of the inner metal fitting 30 set to the reference potential PV1 and the discharge electrode body 70 set to the discharge potential PV2 that is a positive potential higher than the nozzle portion 35a. Air discharge (corona discharge) occurs between the needle-shaped tip 73 and positive ions CP are generated in which N ₂ , O _2, etc. in the atmosphere (air) are ionized. On the other hand, the air AR is supplied into the discharge space DS from the rear end side GK. For this reason, some of the generated ions CP are ejected together with the air AR from the discharge space DS to the cylindrical mixing region MX1 through the communication hole 35f (orifice hole).

  When this air AR is injected into the cylindrical mixing region MX1, the pressure in the cylindrical mixing region MX1 decreases, so that the exhaust gas EG in the exhaust pipe EP is taken into the cylindrical mixing region MX1 from the gas inlet 35h. It is done. The intake gas EGI is mixed with the air AR, and is discharged from the gas discharge port 37h via the slit-shaped mixing region MX2 and the gas discharge path EX. At that time, fine particles S such as soot in the exhaust gas EG are also taken into the cylindrical mixing region MX1. The fine particles S adhere to the ions CP to become positively charged fine particles SC, and are discharged together with the air AR from the gas discharge port 37h in this state. On the other hand, among the ions CP ejected to the cylindrical mixed region MX1, the floating ions CPF that have not adhered to the fine particles S receive repulsive force from the auxiliary electrode portion 83 of the auxiliary electrode body 80 set to the auxiliary potential PV4, and are collected. By adhering to the electrode 37c, discharge from the gas discharge port 37h is suppressed.

  During the above-described air discharge, the discharge current Id is supplied from the external circuit portion 201 to the needle-like tip portion 73 of the discharge electrode body 70. Most of the discharge current Id flows into the nozzle portion 35a as the power receiving current Ij and returns to the circuit portion 201. On the other hand, the collection current Ih resulting from the charge of the floating ions CPF collected by the collection electrode 37 c also returns to the circuit unit 201. In other words, the received collection current Ijh (= Ij + Ih), which is the sum of the received current Ij and the collected current Ih, returns to the circuit unit 201.

  However, the power collection current Ijh is smaller than the discharge current Id by a current corresponding to the charge of the discharged ions CPH attached and discharged to the charged fine particles SC. For this reason, a signal current corresponding to the difference between the discharge current Id and the received and collected current Ijh (discharge current Id−received and collected current Ijh) flows between the reference potential PV1 and the ground potential PVE.

  Therefore, by detecting the signal current corresponding to the charge amount of the discharged ions CPH discharged by the charged fine particles SC, the amount of the fine particles S in the exhaust gas EG can be detected. For this reason, in the present embodiment, based on the charge amount of the charged fine particles SC (specifically, based on the signal current flowing between the reference potential PV1 and the ground potential PVE according to the charge amount of the charged fine particles SC). The amount of fine particles S in the exhaust gas EG (measured gas) is detected.

  As the “amount of fine particles S” detected by the fine particle sensor 1, a value proportional to the total surface area of the fine particles S in the exhaust gas EG may be obtained, or a value proportional to the total mass of the fine particles S may be obtained. May be obtained. Further, a value (concentration of fine particles S) proportional to the number of fine particles S contained in a unit volume of the exhaust gas EG may be obtained.

  In the above, the present invention has been described with reference to the embodiment. However, the present invention is not limited to the above-described embodiment, and it is needless to say that the present invention can be appropriately modified and applied without departing from the gist thereof.

  For example, in the embodiment, as the holder, the holder 50 composed of the two members of the holder main body 51 and the cylindrical portion 55 is shown. More specifically, the holder 50 in which the holder main body 51 and the cylindrical portion 55 are integrated by press-fitting and fixing the cylindrical tubular portion 55 into the through hole 56 of the holder main body 51. showed that. However, the holder may be formed by a single member. However, the rear end side vent opening that opens to the rear end side in the axial direction in the vent hole of the holder is more axial than the rear end accommodation opening that opens to the rear end side in the axial direction of the adhesive accommodating section. The holder is formed so as to be located on the rear end side.

DESCRIPTION OF SYMBOLS 1 Fine particle sensor 5 Sensor main-body part 10 Outer metal fitting 11 1st outer metal fitting 15 2nd outer metal fitting 15t Air intake part 30 Inner metal fitting 31 Inner cylinder 35d Discharge counter electrode part 35f Communication hole 41 Separator 50 Holder 51 Holder main-body part 51c Rear end surface 52 1st 1 Insertion hole 52b, 53b Adhesive accommodation part 52d, 53d Rear end side accommodation opening 53 Second insertion hole 55 Cylindrical part 55b Hollow part 55d Rear end side ventilation opening 57 Vent hole 59 Adhesive 70 Discharge electrode body 73 Needle Tip portion 80 Auxiliary electrode body 201 Circuit portion 330 Pressure pump AR Air DS Discharge space MX1 Cylindrical mixing region (mixing space)
EP exhaust pipe (venting pipe)
EG Exhaust gas (measured gas)
GH Axial direction GS Axial front end side GK Axial rear end side S Fine particle SC Charged fine particle CP Ion

Claims (3)

Fine particles in the gas to be measured which have a sensor main body portion extending in the axial direction, and a portion of the sensor main body portion on the tip end side in the axial direction is disposed inside the vent pipe, and circulates in the vent pipe A fine particle sensor for detecting the amount of
The fine particle sensor has an air intake part for taking air into the inside from the outside of the sensor body part,
The sensor body is
A discharge electrode body extending in the axial direction;
A holder for holding the discharge electrode body;
An adhesive for bonding the discharge electrode body to the holder;
A discharge counter electrode portion, which is located on the tip end side in the axial direction with respect to the holder and serves as a counter electrode of the discharge electrode body, and has a discharge space in which the tip end portion of the discharge electrode body is disposed; A discharge counter electrode portion for generating an air discharge with the tip of the discharge electrode body at
A position that is located closer to the distal end side in the axial direction than the discharge counter electrode portion, and that constitutes a mixing space in which the ions generated by the air discharge and the gas to be measured are introduced and mixed;
The holder is
An insertion hole that penetrates the holder in the axial direction and into which the discharge electrode body is inserted;
A vent hole penetrating the holder in the axial direction, and the air introduced into the sensor body through the air intake portion flows from the rear end side to the front end side in the axial direction through the vent hole. And vent holes to be
The insertion hole includes an adhesive accommodating portion that opens to the rear end side in the axial direction and accommodates the adhesive,
The adhesive is housed inside the adhesive housing section,
The discharge counter electrode portion is a communication hole that communicates the discharge space and the mixing space, and has a communication hole through which the air flows from the rear end side to the front end side in the axial direction through the communication hole.
In the fine particle sensor, the air introduced into the sensor main body through the air intake portion flows in the sensor main body from the rear end side to the front end side in the axial direction. The air is introduced into the discharge space through the vent hole from the rear end side in the axial direction to the front end side, and then the air is introduced from the discharge space into the mixing space through the communication hole. The ion generated in the discharge space has a configuration that is introduced into the mixing space together with the air,
The rear end side vent opening portion that opens to the rear end side in the axial direction of the vent hole of the holder is more than the rear end side opening portion that opens to the rear end side in the axial direction of the adhesive accommodating portion. And a particulate sensor located on the rear end side in the axial direction. The fine particle sensor according to claim 1,
The holder is
A holder main body including the adhesive accommodating portion;
A cylindrical part that extends in the axial direction and projects from the rear end surface of the holder main body located at the rear end in the axial direction toward the rear end in the axial direction, the cylindrical part A hollow portion penetrating in the axial direction comprises a cylindrical portion constituting at least a part of the vent hole,
The rear end side accommodating opening of the adhesive accommodating portion opens to the rear end surface of the holder main body portion,
The fine particle sensor in which an opening portion opened to the rear end side in the axial direction in the hollow portion of the cylindrical portion is the rear end side ventilation opening portion. The fine particle sensor according to claim 1 or 2,
The fine particle sensor, wherein the adhesive is a heat-resistant inorganic adhesive.

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