JP5588471B2 - Particle detection system - Google Patents

Description

  The present invention relates to a fine particle detection system that detects the amount of fine particles in a gas to be measured flowing in a ventilation 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 detection system that can directly measure the amount of particulates in exhaust gas and detect the amount of particulates in exhaust gas downstream of the filter in order to detect filter malfunctions.

  For example, Patent Document 1 discloses a particle measurement processing method and apparatus. In Patent Document 1, gas containing ionized positive ion particles is mixed with exhaust gas containing fine particles taken into the channel from the exhaust pipe to charge the fine particles, and then discharged to the exhaust pipe. And the method of detecting the electric current (signal current) which flows according to the quantity of discharged | emitted charged fine particles and detecting the density | concentration of fine particles is disclosed.

WO2009 / 109688

In such a fine particle detection system, charged fine particles are discharged, while ion particles that have not adhered to the fine particles are collected by a collecting electrode. Therefore, it is conceivable to provide an auxiliary electrode having a potential different from that of the collecting electrode in order to assist the collection of ion particles by the collecting electrode. In installing the auxiliary electrode, an auxiliary electrode insulating member is interposed to insulate the collecting electrode, the exhaust pipe, and the like from the auxiliary electrode.
However, foreign substances contained in the gas to be measured (for example, soot and water droplets when the gas to be measured is exhaust gas of an internal combustion engine) may adhere to the insulating member. When such a foreign substance adheres to the surface of the insulating member and the insulating property of the insulating member decreases, there is a possibility that the auxiliary electrode cannot sufficiently assist the collection and the amount of fine particles cannot be detected appropriately.

  The present invention has been made in view of such problems, and provides a particulate detection system that recovers and maintains the insulation of an auxiliary electrode insulating member that contacts a gas to be measured.

  One aspect of the present invention for solving the above-described problem is a particulate detection system that detects the amount of particulates in a gas to be measured that flows in a ventilation pipe, and includes a detection unit that is attached to an attachment opening of the ventilation pipe. The detection unit includes a first discharge electrode and a second discharge electrode, and is electrically connected to the first discharge electrode of the ion source and the ion source that generates ions by an air discharge between the first discharge electrode and the second discharge electrode. The charged particles are made by attaching the ions to the fine particles to form charged fine particles, and the charged fine particles forming the collecting electrode for collecting the floating ions not attached to the fine particles among the ions, and the auxiliary electrode potential. An auxiliary electrode that is disposed in the fine particle charging unit and assists the collection of the floating ions by the collecting electrode, and is in contact with the gas to be measured and surrounds a part of the auxiliary electrode. Electrodes and above Interposed between the particle charging unit, the auxiliary electrode insulating member for electrically insulating the both, and a particle detection system having a heater, for heating the auxiliary electrode insulating member.

  In this fine particle detection system, an auxiliary electrode potential is set between the auxiliary electrode that assists the collection of floating ions by the collecting electrode of the fine particle charging portion and the fine particle charging portion, and electrically insulates both. It has an electrode insulation member. However, as described above, when foreign matter (soot, water droplets, etc.) contained in the gas to be measured adheres to the auxiliary electrode insulating member, the insulation between the fine particle charging portion and the auxiliary electrode is reduced, and the auxiliary electrode Potential may decrease. Then, trapping of floating ions cannot be performed properly, and not only charged fine particles but also floating ions are discharged from the charged particle portion, so that the detection accuracy of the amount of detected fine particles may be lowered.

  On the other hand, this system has a heater for heating the auxiliary electrode insulating member. Thereby, foreign matters such as moisture and soot adhering to the auxiliary electrode insulating member can be removed (evaporation and burning). Thus, in this system, the insulation between the charged particle part and the auxiliary electrode via the auxiliary electrode insulating member can be recovered or maintained by heating the heater so that the amount of fine particles can be detected appropriately in the system. Become.

  The heater may be formed in or on the auxiliary electrode insulating member to directly heat the auxiliary electrode insulating member, or another member may be interposed between the auxiliary electrode insulating member. It is good also as a structure heated indirectly.

  Furthermore, in the fine particle detection system described above, when the first electric potential member is the first discharge electrode of the ion source, the fine particle charging unit, and the member connected to the first electric potential member. The detection unit is connected to the vent pipe to be ground potential, and faces the inside of the vent pipe, and is between the first potential member and the inner surface of the vent pipe or the ground potential member. A particulate contact detection system that is interposed between the gas contact insulation member and the gas contact insulation member. Good.

The detection unit of this system has a gas contact insulating member that is interposed between the first potential member and the inner side surface of the ventilation pipe or the ground potential member and insulates both, and contacts the gas to be measured.
By the way, this system has a fine particle charging portion, and detects the amount of fine particles by detecting the amount of electric charges attached to the discharged fine particles and discharged from the fine particle charging portion. That is, the signal current that flows between the first potential that is the potential of the fine particle charging portion and the ground potential that is the potential of the vent pipe corresponds to the amount of charge discharged from the fine particle charging portion. However, if the insulation between the first potential member that is set to the first potential and the vent pipe or ground potential member that is set to the ground potential is low, it becomes difficult to detect this signal current, and the amount of fine particles is reduced. It cannot be detected properly.

  On the other hand, in the present system, the heater heats the gas contact insulating member as well as the auxiliary electrode insulating member. Thus, in this system, the insulation between the first potential member and the inner surface of the ventilation pipe or the ground potential member can be recovered or maintained by heating the heater. Thereby, the amount of fine particles can be appropriately detected. Further, since the heater is also used as a heater, it is possible to reduce the number of heaters and wiring members and spaces.

  Furthermore, in the fine particle detection system described above, the heater may be a fine particle detection system integrated with the auxiliary electrode insulating member.

  In this system, the heater is integrated with the auxiliary electrode insulating member. Thereby, while being able to reduce the installation space of a heater and being able to handle it integrally with an auxiliary electrode insulation member, attachment and wiring can be performed easily.

  Further, in the fine particle detection system described above, the vent pipe may be an exhaust pipe of an internal combustion engine, and the gas to be measured may be a fine particle detection system that is an exhaust gas flowing through the exhaust pipe.

The exhaust gas flowing through the exhaust pipe of the internal combustion engine may contain a large amount of soot (fine particles). For this reason, when soot accumulates on the auxiliary electrode insulating member or the like, the insulating property is likely to be lowered, and the amount of fine particles may not be detected properly.
In the present system, the auxiliary electrode insulating member can be heated by the heater to recover or maintain the insulating property, so that the detection of the particulate matter related to the exhaust gas can be appropriately performed.

It is explanatory drawing explaining the state which applied the embodiment and applied the particulate detection system to the exhaust pipe of the engine mounted in the vehicle. It is explanatory drawing which shows schematic structure of the microparticle detection system concerning embodiment. It is a longitudinal section showing the structure of the particulate detection system concerning an embodiment. It is sectional drawing which shows the structure of the microparticle detection system concerning embodiment, Comprising: It is a longitudinal cross-sectional view in the longitudinal cross section orthogonal to the cross section of FIG. It is a disassembled perspective view which shows the structure of the microparticle detection system concerning embodiment. FIG. 6 is an enlarged view of an auxiliary electrode body and an auxiliary electrode insulating pipe with a heater in the exploded perspective view shown in FIG. 5 showing the structure of the particulate detection system according to the embodiment. It is explanatory drawing which illustrates typically the mode of taking in of a microparticle, charging, and discharge | emission within a microparticle charging part among the microparticle detection systems concerning embodiment.

A fine particle detection system 1 according to the present embodiment will be described with reference to the drawings. The particulate detection system 1 of the present embodiment is mounted on an exhaust pipe EP of an engine ENG (internal combustion engine) mounted on a vehicle AM, and determines the amount of particulate S (soot) in the exhaust gas EG flowing in the exhaust pipe EP. Detect (see FIG. 1). The system 1 mainly includes a detection unit 10, a circuit unit 201, and a pressure feed pump 300 that is a compressed air source that generates compressed air AK (see FIG. 2).
The detection unit 10 is attached to an attachment part EPT in which an attachment opening EPO is perforated in the exhaust pipe EP (venting pipe). A part thereof (in FIG. 2, the right side (front end side) of the attachment portion EPT) is disposed in the exhaust pipe EP through the attachment opening EPO, and is in contact with the exhaust gas EG (measured gas).
The circuit unit 201 is connected to the detection unit 10 via a cable 160 made of a plurality of wiring materials outside the exhaust pipe EP. The circuit unit 201 includes a circuit that drives the detection unit 10 and detects a signal current Is described later.

First, the configuration on the electric circuit of the circuit unit 201 in the system 1 will be described. The circuit unit 201 includes a measurement control circuit 220 including a signal current detection circuit 230 and a heater energization circuit 226, an ion source power supply circuit 210, and an auxiliary electrode power supply circuit 240.
Among these, the ion source power supply circuit 210 has a first output terminal 211 having a first discharge potential PV1 and a second output terminal 212 having a second discharge potential PV2. Specifically, the second discharge potential PV2 is a positive high potential with respect to the first discharge potential PV1. More specifically, the second output terminal 212 outputs a positive pulse voltage of 1 to 2 kV0-p obtained by half-wave rectifying a sine wave of about 100 kHz with respect to the first discharge potential PV1. The ion source power supply circuit 210 constitutes a constant current power source that is feedback-controlled for its output current and autonomously maintains its effective value at a predetermined current value (for example, 5 μA).

  On the other hand, the auxiliary electrode power circuit 240 includes an auxiliary first output terminal 241 that is set to the first discharge potential PV1 and an auxiliary second output terminal 242 that is set to the auxiliary electrode potential PV3. Specifically, the auxiliary electrode potential PV3 is a positive DC high potential with respect to the first discharge potential PV1, but is lower than the peak potential (1-2 kV) of the second discharge potential PV2, for example, DC100 It is set to a potential of ~ 200V.

  Further, the signal current detection circuit 230 forming a part of the measurement control circuit 220 includes a signal input terminal 231 connected to the first output terminal 211 of the ion source power supply circuit 210 and a ground input terminal 232 connected to the ground potential PVE. Have. The signal current detection circuit 230 is a circuit that detects a signal current Is described later.

  The heater energization circuit 226 is a circuit that energizes and heats a heater 78 (described later) by PWM control. The heater energization end 226a connected to the first heater connection wiring 169a of the cable 160; A second heater energization end 226b connected to the second heater connection wiring 169b of the cable 160 is provided.

In addition, in the circuit unit 201, the ion source power supply circuit 210 and the auxiliary electrode power supply circuit 240 are surrounded by an inner circuit case 250 having a first discharge potential PV1. The first output terminal 211 of the ion source power circuit 210, the auxiliary first output terminal 241 of the auxiliary electrode power circuit 240, and the signal input terminal 231 of the signal current detection circuit 230 are connected to the inner circuit case 250.
In the present embodiment, the inner circuit case 250 accommodates and surrounds the ion source power circuit 210, the auxiliary electrode power circuit 240, and the secondary iron core 271B of the insulation transformer 270, and the first potential wiring of the cable 160. 165 is conducting.

  On the other hand, the insulation transformer 270 has an iron core 271 wound around a primary iron core 271A wound around a primary coil 272 and a secondary iron core 271B wound around a power circuit coil 273 and an auxiliary electrode power supply coil 274. It is configured separately. Among these, the primary side iron core 271A is conducted to the ground potential PVE, and the secondary side iron core 271B is conducted to the first discharge potential PV1 (the first output terminal 211 of the ion source power supply circuit 210).

Further, the ion source power supply circuit 210, the auxiliary electrode power supply circuit 240, the inner circuit case 250, and the measurement control circuit 220 including the signal current detection circuit 230 and the heater energization circuit 226 are connected to the ground input terminal 232 of the signal current detection circuit 230. And is surrounded by an outer circuit case 260 which is set to the ground potential PVE. Further, in addition to the ground input terminal 232 of the signal current detection circuit 230, the primary iron core 271 </ b> A of the isolation transformer 270 is connected to the outer circuit case 260.
In the present embodiment, the outer circuit case 260 includes an ion source power supply circuit 210, an auxiliary electrode power supply circuit 240, an inner circuit case 250, a signal current detection circuit 230, and a heater energization circuit 226 therein. In addition, the primary side iron core 271 </ b> A of the insulating transformer 270 is accommodated and surrounded, and is electrically connected to the ground potential wiring 167 of the cable 160.

The measurement control circuit 220 includes a regulator power source PS. The regulator power supply PS is driven by an external battery BT through the power supply wiring BC.
The measurement control circuit 220 includes a microprocessor 202 and can communicate with the control unit ECU that controls the internal combustion engine via the communication line CC. The measurement result (signal current Is) of the signal current detection circuit 230 described above. ), A value obtained by converting this into a fine particle amount, or a signal indicating whether or not the fine particle amount exceeds a predetermined amount can be transmitted to the control unit ECU. As a result, the control unit ECU can perform operations such as controlling the internal combustion engine and issuing a malfunction warning of a filter (not shown).

Part of the electric power input from the outside to the measurement control circuit 220 through the regulator power supply PS is distributed to the ion source power supply circuit 210 and the auxiliary electrode power supply circuit 240 via the isolation transformer 270. The insulating transformer 270 forms a primary coil 272 that forms part of the measurement control circuit 220, a power circuit coil 273 that forms part of the ion source power circuit 210, and a part of the auxiliary electrode power circuit 240. The auxiliary electrode power supply side coil 274 and the iron core 271 (primary side iron core 271A, secondary side iron core 271B) are insulated from each other. For this reason, while electric power can be distributed from the measurement control circuit 220 to the ion source power supply circuit 210 and the auxiliary electrode power supply circuit 240, insulation between them can be maintained.
In the present embodiment, the insulating transformer 270 also serves as an auxiliary electrode insulating transformer that supplies power to the auxiliary electrode power supply circuit 240.

  The pressure feed pump 300 takes in the ambient air (air) around itself and is directed toward an ion gas injection source 11 described later through an air feed pipe 310 having tip portions inserted into the outer circuit case 260 and the inner circuit case 250. Then, clean compressed air AK is pumped.

  Next, the cable 160 will be described (see FIG. 2). At the center of the cable 160, a second potential wiring 161 made of copper wire, an auxiliary potential wiring 162, a first heater connection wiring 169a and a second heater connection wiring 169b, and a hollow air pipe 163 made of resin are arranged. Yes. These radial circumferences are surrounded by an inner insulator layer 164.

Further, the inner periphery of the inner insulator layer 164 is surrounded by a first potential wiring 165 made of a braided copper fine wire. In addition, an insulating insulator coating layer 166 made of resin is disposed around the first potential wiring 165 in the radial direction. Further, the circumference in the radial direction is covered with a ground potential wiring 167 made of a braided copper fine wire. An insulating outer insulating coating layer 168 made of resin is formed around the ground potential wiring 167 in the radial direction for protection.
In addition, the cable 160 can circulate gas in the longitudinal direction of the cable 160 through the gas flow passage 163H in the air pipe 163.

As described above, the circuit unit 201 is connected to the cable 160 (see FIG. 2). Specifically, the second output terminal 212 of the ion source power supply circuit 210 is set to the second discharge potential PV2, and is connected to and conductive with the second potential wiring 161. The auxiliary second output terminal 242 of the auxiliary electrode power circuit 240 is set to the auxiliary electrode potential PV3 and is connected to and connected to the auxiliary potential wiring 162. Further, the first output terminal 211 of the ion source power circuit 210 is set to the first discharge potential PV1, the auxiliary first output terminal 241 of the auxiliary electrode power circuit 240, the signal input terminal 231 of the signal current detection circuit 230, and the inner circuit case 250. The first potential wiring 165 is connected to and conductive. In addition, the ground input terminal 232 of the signal current detection circuit 230 is connected to and connected to the outer circuit case 260 and the ground potential wiring 167 to be the ground potential PVE.
The first heater energization end 226a of the heater energization circuit 226 is connected to and conductive with the first heater connection wiring 169a, and the second heater energization end 226b of the heater energization circuit 226 is connected to and conduction with the second heater connection wiring 169b. doing.
In addition, the air supply pipe 310 of the pressure pump 300 is communicated with the air pipe 163 of the cable 160 through the inside circuit case 250.

  Next, the mechanical configuration of the system 1 will be described with reference to the longitudinal sectional views of FIGS. 3 and 4 and the exploded perspective views of FIGS. 5 and 6. 3 to 6, the upper side in the figure is the front end side, and the lower side in the figure is the base end side. Note that the description of the mechanical configuration of the circuit unit 201 described above is omitted.

  First, the detection part 10 is demonstrated (refer FIGS. 3-6). As described above, the detection unit 10 is mounted on the mounting portion EPT having the mounting opening EPO in the exhaust pipe EP (venting pipe) of the engine ENG (internal combustion engine), and contacts the exhaust gas EG (measured gas). The detection unit 10 is roughly composed of an ion gas injection source 11, a fine particle charging unit 12, a first conduction member 13, a needle electrode body 20, and an auxiliary electrode body 50 (auxiliary electrode) in terms of its electrical functions. Yes.

On the distal end side of the cable 160, a second potential wiring 161, an auxiliary potential wiring 162, a first heater connection wiring 169a, and a second heater connection wiring 169b are inserted through an insulating separator 85, and together with the separator 85, a metal The inner cylinder 80 is held inside. The air pipe 163 has an open end 163S in the inner cylinder 80, and the central vent 85H of the separator 85 serves as a passage for the compressed air AK discharged from the air pipe 163.
The inner cylinder 80 is externally fitted to the distal end side of the cable 160 and is caulked and connected to the first potential wiring 165 covering the outer side of the inner insulating layer 164 of the cable 160 to cover the first potential. The wiring 165 is electrically connected.

  The distal end side of the second potential wiring 161 of the cable 160 is connected to the extending portion 21 of the needle electrode body 20 in the separator 85 inside the inner cylinder 80. This needle-shaped electrode body 20 is made of a tungsten wire, and has a substantially straight rod-shaped extension portion 21 and a second discharge electrode that is located at the tip portion (upper end portion in the figure) and has a needle-like shape. It comprises a needle-like tip portion 22 formed. Further, the extension portion 21 of the needle electrode body 20 is covered with a cylindrical needle electrode insulating pipe 75 made of an insulating ceramic such as alumina and perforated in a holding portion 61 of a metal pipe holder 60. It is inserted into the needle electrode insertion hole 61 </ b> H and held by the holding portion 61 together with the needle electrode insulating pipe 75.

  Further, the distal end side of the auxiliary potential wiring 162 of the cable 160 is connected to the extending portion 51 of the auxiliary electrode body 50 in the separator 85 inside the inner cylinder 80. The auxiliary electrode body 50 is made of a stainless steel wire, and includes an approximately straight rod-like extension portion 51, a bent-back portion 52 bent back in a U-shape on the tip end side, and an auxiliary electrode portion 53 forming an auxiliary electrode. Become. It should be noted that the tip portion of the auxiliary electrode portion 53 is also shaped like a needle, which is a needle-like tip portion 53S. Further, the extension portion 51 of the auxiliary electrode body 50 is covered with an auxiliary electrode insulating pipe 79 with a heater, and is inserted into the auxiliary electrode insertion hole 61I drilled in the holding portion 61 of the pipe holder 60 together with the pipe 79. And is held by the holding portion 61. The auxiliary electrode insulating pipe 79 with a heater includes a cylindrical auxiliary electrode insulating pipe 77 made of an insulating ceramic such as alumina, a heater 78 formed and integrated on the surface, and an insulating ceramic layer 76 covering them. (See FIG. 6). The auxiliary electrode insulating pipe 79 with a heater has two heater terminals 78a and 78b of the heater 78 exposed on the base end side (lower side in FIG. 6). The heater 78 is made of tungsten, extends from the heater terminals 78a and 78b toward the distal end side (upward in FIG. 6), the heater lead portions 78r1 and 78r2, the first heater portion 78h1 positioned at the distal end portion, and the proximal end thereof. Two heating portions of the second heater portion 78h2 located on the side. The first heater part 78h1 and the second heater part 78h2 are connected in parallel. These are formed on the surface of the auxiliary electrode insulating pipe 77, and further, these surfaces are covered with an insulating ceramic layer 76 such as alumina to constitute an auxiliary electrode insulating pipe 79 with a heater.

  The first heater connection wiring 169a and the second heater connection wiring 169b of the cable 160 are connected to the heater connection terminals 170a and 170b in the separator 85 inside the inner cylinder 80, respectively. The heater connection terminals 170 a and 170 b extend to the front end side of the separator 85 in the inner cylinder 80 and are connected to the heater terminals 78 a and 78 b of the heater 78.

  The air pipe 163 of the cable 160 has an open end 163S in the inner cylinder 80 as described above. Further, a pipe holder 60 is fitted on the distal end side of the inner cylinder 80. For this reason, the compressed air AK released from the air pipe 163 passes through the ventilation hole 85H of the separator 85 and the ventilation through hole 61J drilled in the holding portion 61 of the pipe holder 60, and the discharge space DS ( (To be described later).

The pipe holder 60 shown in FIGS. 3 to 5 is made of stainless steel, has a solid columnar holding portion 61, and a cylindrical cylindrical wall portion 63 extending from the periphery of the holding portion 61 toward the tip side. Have Of these, the holding portion 61 has an annular holder flange portion 66 that bulges radially outward. In addition, the holding part 61 has a needle-like electrode insertion hole 61H, an auxiliary electrode insertion hole 61I, and a ventilation through-hole 61J extending in the vertical direction in the figure, and as described above, the needle-like electrode insertion hole The extension portion 21 of the needle electrode body 20 is inserted and held in 61H, and the extension portion 51 of the auxiliary electrode body 50 is inserted and held in the auxiliary electrode insertion hole 61I. On the other hand, the needle-like tip portion 22 of the needle-like electrode body 20 protrudes from the holding portion 61 toward the tip side on the radially inner side of the cylindrical wall portion 63.
The pipe holder 60 is fitted and fixed to the inner cylinder 80 and is electrically conductive. The pipe holder 60 and the inner cylinder 80 form the first conductive member 13 that surrounds the extending portion 21 of the needle electrode body 20 and the extending portion 51 of the auxiliary electrode body 50.

Further, a bottomed cylindrical nozzle member 30, specifically, a nozzle portion 31 that forms the bottom thereof is fitted into the distal end side (upper side in the drawing) of the cylindrical wall portion 63 of the pipe holder 60. The nozzle member 30 is also made of stainless steel, and includes a nozzle portion 31 located at the bottom, and a cylindrical tube wall portion 33 extending from the periphery of the nozzle portion 31 to the tip side. Among these, the nozzle portion 31 has a concave shape whose center is directed toward the distal end side, and a fine through hole is formed at the center to form the nozzle 31N. On the other hand, the cylindrical wall portion 33 is perforated with an intake port 33I (see FIG. 4) (opened toward the downstream side of the exhaust pipe EP). As will be described later, the intake port 33I is an opening for taking the exhaust gas EG into a mixed region MX (described later) formed by the nozzle member 30 and the mixed discharge member 40.
In addition, the nozzle member 30 is fitted and fixed to the pipe holder 60, and is electrically connected to the first discharge potential PV1.

In this way, the nozzle portion 31 of the nozzle member 30 is fitted into the distal end side (upper side in the drawing) of the cylindrical wall portion 63 of the pipe holder 60, whereby a discharge space DS is formed therebetween. In this discharge space DS, the needle-like tip portion 22 of the needle-like electrode body 20 protrudes from the holding portion 61 of the pipe holder 60, and this needle-like tip portion 22 is in contact with the opposing surface 31 T that forms the concave shape of the nozzle portion 31. Facing each other. Accordingly, when a high voltage is applied between the needle-shaped tip 22 and the nozzle portion 31 (opposing surface 31T), air discharge occurs, and N ₂ , O _2, etc. in the atmosphere are ionized, and positive ions (for example, N ³⁺ , O ^2+, hereinafter also referred to as ions CP). Further, the compressed air AK is also supplied to the discharge space DS through the ventilation through hole 61J of the holding portion 61 of the pipe holder 60. For this reason, the air AR originating from the compressed air AK is ejected from the nozzle 31N of the nozzle portion 31 toward the mixed region MX (described later) on the tip side at a high speed, and the compressed air AK (air AR) ), The ions CP are also injected into the mixing region MX.

Furthermore, a mixing / discharging member 40 (see also FIG. 5) is fitted on the tip end side (upper side in the drawing) of the cylindrical wall portion 33 of the nozzle member 30. The mixing and discharging member 40 is also made of stainless steel, and has a base end portion 41 located on the base end side (downward in the figure) and a cylindrical tip end side cylindrical wall portion extending from the periphery of the base end portion 41 to the tip end side. 43. Further, the distal end side of the distal end side cylinder wall portion 43 is closed by being covered with a lid member 48. Further, a discharge port 43O (opening toward the downstream side of the exhaust pipe EP) is formed in the distal end side cylindrical wall portion 43 at one location.
Of the mixed discharge member 40, the base end portion 41 is configured such that the inner space is narrowed in a slit shape by the collecting electrode 42 bulging inward. On the other hand, a cylindrical space is formed in the distal end side cylindrical wall portion 43. The collecting electrode 42 is formed with a notch 42K in accordance with the position of the inlet 33I of the nozzle member 30.
In addition, the mixed discharge member 40 is fitted and fixed to the nozzle member 30 and is electrically connected to the first discharge potential PV1.

  Thus, in the nozzle member 30, the front end side surface 31 </ b> S facing upward in the drawing of the nozzle portion 31, the cylindrical wall portion 33, and the base end portion 41 (collecting electrode 42) of the mixed discharge member 40, a substantially cylindrical space. Is formed. This space forms a cylindrical mixed region MX1 in the mixed region MX described later. On the other hand, the slit-shaped internal space formed by the collecting electrode 42 at the base end portion 41 of the mixed discharge member 40 forms a slit-shaped mixed region MX2. Further, the cylindrical space in the distal end side cylinder wall portion 43 forms a discharge path EX communicating with the discharge port 43O. In addition, a lead-in path HK communicating from the intake port 33I to the mixing region MX (columnar mixing region MX1) is formed by the cutout portion 42K of the collecting electrode 42.

  As will be described later, when the air AR containing the ions CP is ejected from the nozzle 31N at a high speed, the ejected air AR passes through the columnar mixing region MX1, the slit-shaped mixing region MX2, and the discharge path EX. And is discharged from the discharge port 43O. Furthermore, since the atmospheric pressure in the cylindrical mixing region MX1 decreases due to the flow of the air AR injected at a high speed, the exhaust gas EG outside the intake port 33I passes through the intake passage HK from the intake port 33I and passes through the mixing region MX (circle). The columnar mixed region MX1 and the slit-shaped mixed region MX2) are incorporated. The taken-in exhaust gas EGI is mixed with the air AR containing the ions CP in the mixing region MX, and is discharged from the discharge port 43O via the discharge path EX together with the air AR.

  Further, the extension part 51 of the auxiliary electrode body 50 and the auxiliary electrode insulating pipe 77 surrounding the extension part 51 described above extend to the tip side (upward in the drawing) from the pipe holder 60 and the nozzle member 30, and the extension part A bent-back portion 52 connected to 51 is located in the distal end side cylindrical wall portion 43 (discharge path EX) of the mixed discharge member 40. And the auxiliary electrode part 53 which faces the base end side (downward in the figure) is located in the slit-shaped mixed region MX2 formed by the base end part 41 of the mixed discharge member 40.

  As shown in FIG. 3, a substantially cylindrical first insulating spacer 121 made of an insulating ceramic such as alumina is disposed on the distal end side (upper side in the drawing) of the holder flange portion 66 of the pipe holder 60. A substantially cylindrical second insulating spacer 122 made of an insulating ceramic such as alumina is also arranged on the base end side (lower side in the figure) of the holder flange portion 66. Further, a metal shell 90 made of stainless steel is disposed around these radial directions (in the horizontal direction in the figure).

The metal shell 90 includes a cylindrical portion 91 and a flange portion 95. Among these, the substantially cylindrical tubular portion 91 holds a holding hole 91 </ b> H that holds the pipe holder 60, the first insulating spacer 121, and the second insulating spacer 122 therein. Further, the base end side of the cylindrical portion 91 is a female screw portion 92 having a female screw formed on the inner wall.
On the other hand, the flange portion 95 is a plate shape projecting radially outward from the distal end portion of the cylindrical portion 91 and has a substantially oval outer shape. Moreover, it has the bolt through-holes 95H and 95H penetrated in own thickness direction (2 places in this embodiment).

Further, the plug fitting 100 is screwed to the female threaded portion 92 of the cylindrical portion 91 of the metal shell 90 with a male threaded portion 102 having a male thread formed on the outer periphery thereof. The stopper metal 100 has a substantially cylindrical shape and surrounds the inner cylinder 80 in a non-contact manner. Further, the plug fitting 100 has a distal end pressing portion 101 having a flat distal end surface 101S formed on the distal end side (upward in the drawing) of the male screw portion 102 and having a smaller diameter than the male screw portion 102. Further, on the base end side (downward in the drawing) from the male screw portion 102, there is a hexagonal portion 103 that protrudes in a flange shape toward the outer side in the radial direction and has a hexagonal outer periphery.
When the male threaded portion 102 of the stopper fitting 100 is screwed into the female threaded portion 92 of the metallic shell 90, the stopper fitting 100 advances to the distal end side, and the distal end pressing portion 101 presses the second insulating spacer 122 toward the distal end side. Then, this 2nd insulation spacer 122 presses the holder flange part 66 of the pipe holder 60 toward the front end side. Further, the holder flange portion 66 presses the first insulating spacer 121 toward the distal end side. The first insulating spacer 121 is engaged with the holding hole 91 </ b> H of the cylindrical portion 91 of the metal shell 90 through the plate packing 124. Thereby, the pipe holder 60, the 1st insulating spacer 121, the 2nd insulating spacer 122, the plate packing 124, and the stopper metal fitting 100 are hold | maintained at the metal fitting 90, and are integrated.
In addition, a first insulating spacer 121 and a second insulating spacer 122 are interposed between the pipe holder 60 and the metal shell 90 so as to separate and insulate them from each other. Of the pipe holder 60, the holder flange portion 66 projecting outward in the radial direction and the metal shell 90 (cylindrical portion 91) are spaced apart from each other to maintain insulation therebetween. Yes. Further, the first insulating spacer 121 is interposed between the cylindrical wall portion 63 of the pipe holder 60 and the exhaust pipe EP in a state where the detection unit 10 is mounted on the exhaust pipe EP to separate and insulate the two. Yes.

As shown in FIG. 4, when the detection unit 10 is attached, the nozzle member 30, the mixed discharge member 40, and the like are inserted into the exhaust pipe EP from the attachment opening EPO of the attachment part EPT in the exhaust pipe EP. The stud bolts EPB and EPB provided adjacent to the mounting opening EPO are respectively inserted into the bolt through holes 95H of the flange portion 95 and fastened with nuts EPN. Thereby, the detection part 10 including the metal shell 90 is fixed to the attachment part EPT of the exhaust pipe EP.
An annular gasket holding groove 96 is formed around the holding hole 91H in the front end side surface 90S of the metal shell 90, and the mounting portion EPT of the exhaust pipe EP and the metal shell 90 are held by this gasket holding. They are hermetically coupled through a copper gasket 130 disposed in the groove 96.
Thereby, the gasket 130, the metal shell 90, and the stopper metal 100 are set to the same ground potential PVE as that of the exhaust pipe EP.

Furthermore, a cylindrical outer cylinder 110 made of stainless steel is connected to the base end portion 104 of the stopper fitting 100. The outer cylinder 110 surrounds the inner cylinder 80 and the distal end portion 160 </ b> S of the cable 160 from the outside in the radial direction, and the distal end portion 110 </ b> S is laser-welded to the base end portion 104 of the plug fitting 100 over the entire circumference.
In addition, the base end portion 110 </ b> K of the outer cylinder 110 is fixed to the cable 160 by caulking, with the outer shape being reduced in diameter from the distal end side. At the same time, the caulking portion 110KK of the base end portion 110K of the outer cylinder 110 passes through the outermost outer insulating coating layer 168 of the cable 160 and is electrically connected to the ground potential wiring 167 therein. Thus, both the outer cylinder 110 and the ground potential wiring 167 are set to the ground potential PVE, like the exhaust pipe EP, through the metal shell 90, the plug fitting 100, and the gasket 130 made of metal.
In the present embodiment, in order to prevent the front end portion 160S of the cable 160 from swinging in the outer cylinder 110, a cylindrical shape is formed between the front end portion 160S of the cable 160 and the outer cylinder 110 from insulating rubber. A grommet 125 is interposed.

Next, the electrical functions and operations of each part of the particulate detection system 1 of the present embodiment will be described with reference to FIG. 7 in addition to FIGS. FIG. 7 schematically shows the electrical functions and operations of the detection unit 10 of the system 1 for easy understanding, and there are portions different from the forms described in other drawings. Please note that.
The acicular electrode body 20 is connected to and electrically connected to the second output end 212 of the ion source power supply circuit 210 via the second potential wiring 161 of the cable 160. Accordingly, as described above, the needle-like electrode body 20 is set to the second discharge potential PV2, which is a positive half-wave rectified pulse voltage of 100 kHz and 1-2 kV0-p with respect to the first discharge potential PV1. .
Further, the auxiliary electrode body 50 is connected to and connected to the auxiliary second output terminal 242 of the auxiliary electrode power circuit 240 via the auxiliary potential wiring 162 of the cable 160. Therefore, as described above, the auxiliary electrode body 50 is set to the auxiliary electrode potential PV3 that is a positive DC potential of 100 to 200 V with respect to the first discharge potential PV1.
Further, the inner cylinder 80, the pipe holder 60, the nozzle member 30, and the mixing and discharging member 40 are connected to the first output terminal 211 of the ion source power supply circuit 210 and the auxiliary electrode power supply circuit 240 via the first potential wiring 165 of the cable 160. The auxiliary first output terminal 241, the inner circuit case 250 surrounding these circuits, and the signal input terminal 231 of the signal current detection circuit 230 are connected and conductive. These are the first discharge potential PV1.
In addition, the outer cylinder 110, the plug fitting 100, the metal fitting 90, and the gasket 130 are connected to the outer circuit case 260 and the signal surrounding the measurement control circuit 220 including the signal current detection circuit 230 via the ground potential wiring 167 of the cable 160. The current detection circuit 230 is connected to and connected to the ground input terminal 232. These are set to the same ground potential PVE as the exhaust pipe EP.

Accordingly, as described above, between the nozzle portion 31 (opposing surface 31T) that is set to the first discharge potential PV1 and the needle-like tip portion 22 that is set to the second discharge potential PV2 having a positive potential higher than the first discharge potential PV1. Then, air discharge, specifically, corona discharge occurs. More specifically, a positive needle corona PC in which a corona is generated around the needle-like tip 22 serving as the positive electrode is generated. As a result, N ₂ , O _2, etc. in the atmosphere (air) forming the atmosphere is ionized and positive ions CP are generated. Part of the generated ions CP is jetted toward the mixing region MX through the nozzle 31N together with the compressed air AK (air AR) supplied to the discharge space DS.
In the present embodiment, the needle-like tip portion 22 corresponds to the second discharge electrode, and the nozzle portion 31 of the nozzle member 30 corresponds to the first discharge electrode. Further, the pipe holder 60 (holding portion 61, cylindrical wall portion 63), the nozzle portion 31 (first discharge electrode), and the needle-like tip portion 22 (second discharge electrode) surrounding the discharge space DS are ionized. The source 11 and the ion gas injection source 11 are formed.

When the air AR is injected into the mixing region MX (cylindrical mixing region MX1), as described above, the atmospheric pressure of the cylindrical mixing region MX1 decreases, so that the exhaust gas EG passes through the intake passage HK through the intake passage HK. It is taken into the mixing area MX (cylindrical mixing area MX1, slit-shaped mixing area MX2). The intake exhaust gas EGI is mixed with the air AR, and is discharged from the discharge port 43O via the discharge path EX together with the air AR.
At this time, if the exhaust gas EG contains fine particles S such as soot, the fine particles S are also taken into the mixing region MX as shown in FIG. By the way, the injected air AR contains ions CP. For this reason, the fine particles S such as soot that are taken in are attached to the ions CP to become positively charged fine particles SC, and in this state, the air passes through the mixing region MX and the discharge path EX, and is discharged from the discharge port 43O. It is discharged together with AR.
On the other hand, among the ions CP ejected to the mixed region MX, the floating ions CPF that have not adhered to the fine particles S receive a repulsive force from the auxiliary electrode portion 53 of the auxiliary electrode body 50 and are collected at the first discharge potential PV1. The mixed discharge member 40 (base end portion 41, distal end side cylinder wall portion 43) forming the pole 42 adheres to each portion and is not discharged (captured).

As shown in FIG. 2, the discharge current Id is supplied from the second output end 212 of the ion source power supply circuit 210 to the needle-shaped tip 22 in accordance with the air discharge in the ion gas injection source 11. Most of the discharge current Id flows into the nozzle unit 31 as the power reception current Ij and flows to the first output terminal 211 of the ion source power supply circuit 210. On the other hand, the collection current Ih resulting from the charge of the floating ions CPF collected by the collection electrode 42 also flows to the first output terminal of the ion source power supply circuit 210. That is, a received collection current Ijh (= Ij + Ih) that is the sum of the received current Ij and the collected current Ih flows into the first output terminal 211 of the ion source power supply circuit 210.
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. Therefore, the signal current Is 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 first discharge potential PV1 and the ground potential PVE and balances. .
Therefore, the signal current Is corresponding to the charge amount of the discharged ions CPH discharged by the charged fine particles SC is detected by the signal current detection circuit 230, whereby the amount of the fine particles S in the exhaust gas EG can be detected.
In the present embodiment, the nozzle member 30, the mixed discharge member 40, and the lid member 48 that form the mixing region MX and the collecting electrode 42 correspond to the fine particle charging unit 12.

In addition, the pipe holder 60 (holding portion 61, cylindrical wall portion 63) and inner cylinder 80 are electrically connected to the fine particle charging portion 12 and the nozzle portion 31 of the nozzle member 30, while the extending portion 21 of the needle electrode body 20. And the circumference of the extending portion 51 of the auxiliary electrode body 50 is surrounded.
In the present embodiment, the pipe holder 60 (the holding portion 61 and the cylindrical wall portion 63) and the inner cylinder 80 correspond to the first conductive member 13. Among these, the pipe holder 60 is the first conduction member 13 and also a part of the ion gas ejection source 11 as described above.

Further, the metal shell 90, the plug metal fitting 100, and the outer cylinder 110 are electrically connected to the exhaust pipe EP and set to the ground potential PVE, while the fine particle charging unit 12 (the nozzle member 30 and the like) and the first conductive member 13 described above. It is electrically insulated from the inner cylinder 80 or the like. Of these, the cylindrical portion 91, the plug fitting 100, and the outer cylinder 110 of the metallic shell 90 are the outside of the exhaust pipe EP (of the particulate charging unit 12, the ion gas injection source 11, and the first conducting member 13). 3 and 4 surrounds a portion located below the exhaust pipe EP. Specifically, the proximal portion of the extended portion 21 of the needle electrode body 20 and the extended portion 51 of the auxiliary electrode body 50, the holding portion 61 of the pipe holder 60, and the circumference of the inner cylinder 80 are surrounded. It is out.
In the present embodiment, the metal shell 90, the plug metal fitting 100, and the outer cylinder 110 correspond to the outer surrounding portion 14.

As described above, the extension portion 51 of the auxiliary electrode body 50 is integrally formed by forming the periphery thereof on the auxiliary electrode insulating pipe 79 with a heater, specifically, the auxiliary electrode insulating pipe 77 and the surface thereof. It is surrounded by a heater 78 and an insulating ceramic layer 76 covering them.
Of the extended portion 51 of the auxiliary electrode body 50, as shown in FIGS. 3 and 6, the tip exposed surface 51c exposed from the auxiliary electrode insulating pipe 77 on the tip side and disposed in the fine particle charging portion 12 is: It is in contact with the exhaust gas EG (measured gas). Further, the inner side surface 12c of the fine particle charging unit 12 is also in contact with the exhaust gas EG.
Of the auxiliary electrode insulating pipe 77 of the heater-equipped auxiliary electrode insulating pipe 79 and the insulating ceramic layer 76 covering the auxiliary electrode insulating pipe 77, the tip-side surface 79 c is in contact with the exhaust gas EG and the inner side surface 12 c of the particulate charging unit 12. And the tip exposed surface 51c of the extended portion 51 of the auxiliary electrode body 50.

  On the other hand, in the system 1 of the present embodiment, the heater 78 (first heater portion 78h1) for heating the auxiliary electrode insulating pipe 77 and the insulating ceramic layer 76 (auxiliary electrode insulating member) of the auxiliary electrode insulating pipe 79 with heater is provided. Prepare. Thereby, foreign matters such as moisture and soot on the auxiliary electrode insulating pipe 79 with heater (tip-side surface 79c) can be removed (evaporated and burned out). Thus, in this system 1, by heating the heater 78, the fine particle charging portion 12 (inner side surface 12 c) and the extended portion 51 (tip exposed) of the auxiliary electrode body 50 via the auxiliary electrode insulating pipe 79 with heater (tip-side surface 79 c). The insulation between the surface 51c) can be recovered or maintained. Thereby, the amount of the fine particles S can be appropriately detected by the system 1.

  In the present embodiment, the first discharge potential PV1 corresponds to the first potential in the present invention. Of the auxiliary electrode insulating pipe 79 with a heater, the auxiliary electrode insulating pipe 77 and the insulating ceramic layer 76 correspond to the auxiliary electrode insulating member in the present invention.

  Further, the auxiliary electrode insulation pipe 79 with a heater is inserted into the auxiliary electrode insertion hole 61I drilled in the holding portion 61 of the pipe holder 60, and the first insulation is provided on the radially outer side on the distal end side of the pipe holder 60. Spacers 121 are arranged. The first insulating spacer 121 is interposed between the pipe holder 60 and the metal shell 90 to electrically insulate them, and in the exhaust pipe EP, the cylindrical wall portion 63 of the pipe holder 60 and the exhaust pipe They are electrically insulated from each other by interposing between them.

  Here, as shown in FIG. 3, the outer peripheral surface 63c of the cylindrical wall part 63 of the pipe holder 60 is in contact with the exhaust gas EG. The front surface 121c of the first insulating spacer 121 is interposed between the outer peripheral surface 63c of the cylindrical wall portion 63 of the pipe holder 60 and the inner surface EPi of the exhaust pipe EP, and contacts the exhaust gas EG. Both are electrically insulated.

  On the other hand, in the system 1 of this embodiment, the heater 78 includes the first insulating spacer 121 (grounding) in addition to the auxiliary electrode insulating pipe 77 and the insulating ceramic layer 76 (auxiliary insulating member) of the auxiliary electrode insulating pipe 79 with heater. The potential insulating member is also heated. That is, the heater 78 includes a second heater part 78h2 that heats the first insulating spacer 121 (the front end surface 121c) in addition to the first heater part 78h1. Thereby, in this system 1, the insulation between the cylindrical wall part 63 (outer peripheral surface 63c) and the exhaust pipe EP (inner side surface EPi) of the pipe holder 60 is obtained by heating the heater 78 (second heater part 78h2). Can also be recovered or maintained. Thereby, the amount of the fine particles S can be detected appropriately. In addition, since the heater 78 is used as a combined heater, it is possible to reduce the attachment of the heater 78 and wiring members and spaces.

In the present embodiment, the first conductive member 13 including the nozzle portion 31 (first discharge electrode) of the nozzle member 30 that is conductive to the first discharge potential PV1, the fine particle charging portion 12, and the pipe holder 60 is the first conductive member 13 in the present invention. One potential member. The outer surrounding portion 14 is a ground potential member in the present invention.
Further, the first insulating spacer 121 corresponds to the gas contact insulating member in the present invention.

  Furthermore, in the system 1 of this embodiment, the heater 78 is integrated with the auxiliary electrode insulating pipe 77 and the insulating ceramic layer 76 (auxiliary electrode insulating member) of the auxiliary electrode insulating pipe 79 with a heater. Accordingly, the mounting space for the heater 78 can be reduced, and the auxiliary electrode insulating pipe 77 and the insulating ceramic layer 76, which are auxiliary electrode insulating members, can be handled integrally, so that mounting and wiring can be performed easily.

The exhaust gas EG flowing through the exhaust pipe EP of the internal combustion engine may contain a large amount of soot (fine particles S). For this reason, soot is deposited on the auxiliary electrode insulating pipe 77 of the auxiliary electrode insulating pipe 79 with heater, the insulating ceramic layer 76 (auxiliary electrode insulating member), the first insulating spacer 121 (gas contact insulating member), and the like. Is likely to decrease, and the amount of the fine particles S may not be detected properly.
In the system 1 of the present embodiment, the heater 78 heats the auxiliary electrode insulating pipe 77 of the auxiliary electrode insulating pipe 79 with heater and the insulating ceramic layer 76 (tip-side surface 79c) or the first insulating spacer 121 (tip-side surface 121c). Thus, the insulating property can be recovered or maintained, so that the detection of the fine particles S related to the exhaust gas EG can be appropriately performed.

In the above, the present invention has been described with reference to the system 1 of the embodiment. However, the present invention is not limited to the above embodiment, and it can be applied without departing from the gist of the present invention. Nor.
For example, in the embodiment, the first insulating spacer 121 (gas contact insulating member) is disposed between the first potential member 13 (the outer peripheral surface 63c of the cylindrical wall portion 63 of the pipe holder 60) and the inner side surface EPi of the exhaust pipe EP. The intervening configuration is shown. However, although not shown, depending on the shape of the exhaust pipe EP and the outer surrounding part 14 (ground potential member), the outer surrounding part 14 extends into the exhaust pipe EP, and the outer surrounding part 14 becomes the exhaust gas EG (measured gas). It can also take the form which contacts. In this case, the gas contact insulating member 121 may be interposed between the first potential member 13 and the ground potential member 14.

In the above embodiment, the heater 78 includes the first insulating spacer 121 (ground potential insulating member) in addition to the auxiliary electrode insulating pipe 77 and the insulating ceramic layer 76 (auxiliary electrode insulating member) of the auxiliary electrode insulating pipe 79 with heater. However, it may be configured to heat only the auxiliary electrode insulating member.
In the above embodiment, the example in which the detection unit 10 and the circuit unit 201 are connected via the cable 160 has been shown. However, the detection unit 10 and the circuit unit 201 are connected without using the cable 160. It is good also as a form.

EP exhaust pipe EPi (exhaust pipe) inner surface EPO mounting opening EG exhaust gas EGI intake exhaust gas S particulate SC charged particulate CP ion CPF floating ion CPH exhaust ion Is signal current 1 particulate detection system 10 detection section 11 ion gas injection source (Ion source)
DS Discharge space 12 Particulate charging part (first potential member)
13 First conducting member (first potential member)
14 Outer enclosure (ground potential member)
20 Needle-shaped electrode body 22 Needle-shaped tip (of the needle-shaped electrode body) (second discharge electrode (ion source))
30 Nozzle member (ion source, particulate charging part)
31 Nozzle (first discharge electrode (ion source), fine particle charging unit)
31N nozzle PV1 first discharge potential (first potential)
PV2 Second discharge potential PV3 Auxiliary electrode potential PVE Ground potential 40 Mixed discharge member (particulate charging part)
MX mixing region 42 collecting electrode 48 lid member (particulate charging part)
50 Auxiliary electrode body (auxiliary electrode)
53 Auxiliary Electrode 60 (Auxiliary Electrode Body) Pipe Holder (First Conductive Member)
61 Holding part (first conductive member)
76 Insulating ceramic layer (auxiliary electrode insulating member)
77 Auxiliary electrode insulation pipe (auxiliary electrode insulation member)
78 Heater 79 Auxiliary electrode insulation pipe 80 with heater Inner cylinder (first conductive member)
90 Metal shell (outer enclosure)
100 Plug fitting (outer enclosure)
110 Outer cylinder (outer enclosure)
121 First insulating spacer (gas contact insulating member)
AK compressed air (gas)
AR Air (gas)
201 Circuit Unit 210 Ion Source Power Supply Circuit 220 Measurement Control Circuit 226 Heater Energizing Circuit 230 Signal Current Detection Circuit 240 Auxiliary Electrode Power Supply Circuit

Claims (4)

A fine particle detection system for detecting the amount of fine particles in a gas to be measured flowing in a vent pipe,
A detection unit mounted on the mounting opening of the vent pipe,
The detector is
An ion source including a first discharge electrode and a second discharge electrode and generating ions by air discharge between them;
Conducted to the first discharge electrode of the ion source to be set to the first electric potential, and the ions are attached to the fine particles to form charged fine particles, and among the ions, floating ions not attached to the fine particles are collected. A charged particle part that forms a collecting electrode,
An auxiliary electrode, which is an auxiliary electrode potential, disposed in the fine particle charging unit, and assists the collection of the floating ions by the collection electrode;
An auxiliary electrode insulating member that is in contact with the gas to be measured, surrounds a part of the auxiliary electrode, is interposed between the auxiliary electrode and the fine particle charging unit, and electrically insulates both; and
A fine particle detection system having a heater for heating the auxiliary electrode insulating member. The particulate detection system according to claim 1,
When the first electric potential member, the first discharge electrode of the ion source, the fine particle charging unit, and a member conducting to the first electric potential member,
The detector is
A ground potential member that is connected to the vent pipe to be a ground potential; and
Facing the inside of the vent pipe,
A gas contact insulating member that is interposed between the first potential member and the inner surface of the vent pipe or the ground potential member to electrically insulate both of the first potential member and the gas to be measured; ,
The heater is
A fine particle detection system which is a combined heater for heating the gas contact insulating member. The fine particle detection system according to claim 1 or 2,
The heater is
A fine particle detection system integrated with the auxiliary electrode insulating member. The fine particle detection system according to any one of claims 1 to 3,
The vent pipe is an exhaust pipe of an internal combustion engine,
The particulate matter detection system, wherein the gas to be measured is an exhaust gas flowing through the exhaust pipe.

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