JP5848670B2 - Particle detection system - Google Patents

Description

  The present invention relates to a particulate detection system that detects the amount of particulates in exhaust gas flowing through an exhaust pipe.

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. Moreover, the particulates accumulated in the filter are burned and removed by raising the temperature of the filter as necessary. However, when a problem such as breakage of the filter occurs, unpurified exhaust gas is directly discharged downstream of the filter.
Therefore, there is a need for a particulate detection system that can directly detect the amount of particulates in the exhaust gas and detect the amount of particulates in the exhaust gas in order to detect a filter failure.

  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 this fine particle detection system, the detection unit is mounted on the exhaust pipe, but the exhaust pipe connected to the internal combustion engine and its periphery can be heated by exhaust gas exhausted. However, if the heat from the exhaust pipe that has reached a high temperature is transmitted to the circuit part that has a circuit for generating an air discharge or detecting a signal in the particulate detection system, the characteristics of the circuit components used will change. As a result, temperature drift may occur, and signals may not be detected properly, and in some cases, circuit components may fail.

In order to solve this, it is conceivable to arrange the circuit unit away from the detection unit connected to the exhaust pipe, for example, by connecting the detection unit and the circuit unit with a cable. However, when the detection unit and the circuit unit are connected by a cable, the entire system becomes large.
On the other hand, it is also conceivable to cool the circuit of the circuit unit by flowing compressed air or the like. However, the fine particle detection system may detect a weak current signal of about pA, for example. For this reason, it has been found that when air is allowed to flow to cool a circuit (circuit component), static electricity due to friction between the circuit component and air causes noise and may affect particle detection.

  The present invention has been made in view of such a problem, and while suppressing the influence of heat transmitted from the exhaust pipe to the circuit section while reducing the size of the entire system, the amount of fine particles in the exhaust gas is appropriately set. It is intended to provide a particulate detection system that can detect easily.

  One aspect of the present invention for solving the above problems is a particulate detection system for detecting the amount of particulates in the exhaust gas flowing through the exhaust pipe, the detection unit mounted on the exhaust pipe, and the exhaust pipe A circuit unit having a circuit that is connected to the detection unit outside and drives the detection unit to detect the amount of the fine particles, a circuit surrounding member surrounding the circuit unit, and an outer surface of the circuit surrounding member And an exterior member having a compressed air port for allowing compressed air to flow in at a position facing the outer surface of the circuit surrounding member, and flows into the exterior member through the compressed air port. The fine particle detection system configured to cause the compressed air to flow into the gap between the outer side surface of the circuit surrounding member and the exterior member and to cool the circuit portion via the circuit surrounding member. A.

Since the detection unit is attached to the exhaust pipe, heat can be transferred from the exhaust gas or the exhaust pipe, resulting in a high temperature. For this reason, heat is transmitted from the detection unit having a high temperature to the circuit unit, and the circuit in the circuit unit is likely to have a high temperature.
On the other hand, this particulate detection system includes a circuit surrounding member that surrounds the periphery of the circuit unit, and an exterior member that surrounds the outer surface of the circuit surrounding member via a gap, and is compressed into the exterior member. Air is caused to flow in a gap between the outer surface of the circuit surrounding member and the exterior member, and the circuit portion is cooled via the circuit surrounding member.
For this reason, the heat of the exhaust pipe increases the temperature of the circuit portion, thereby suppressing the influence of heat that causes a temperature drift or failure of the circuit components.
Thus, in this system, the detection unit and the circuit unit are connected together, and the entire system is made compact, but the influence of heat transmitted from the exhaust pipe to the circuit unit is suppressed, and the amount of particulates in the exhaust gas is appropriately controlled. Can be detected.
In addition, since the circuit portion is surrounded by the circuit surrounding member and the compressed air is not directly applied to the circuit of the circuit portion, it is possible to reliably prevent noise caused by air flowing through the circuit portion from being superimposed on the signal. In addition, since the compressed air introduced from the compressed air port directly hits the outer surface of the circuit surrounding member, the circuit portion can be appropriately cooled via the circuit surrounding member.

The circuit unit is connected to the detection unit outside the exhaust pipe. However, in consideration of the influence of heat transmitted from the exhaust pipe to the circuit section, the circuit section may be arranged at a position farthest from the exhaust pipe in the detection section. For example, the circuit unit may be disposed on the opposite side of the exhaust pipe through the detection unit.
Examples of the compressed air source that generates compressed air flowing into the compressed air port include a reciprocating compressor, a scroll compressor, and the like, as well as various pumps that generate and pump compressed air.
In addition, the compressed air flowing in from the compressed air port is not only used for cooling the circuit unit, but also used for injecting the generated ions together with the compressed air into the mixing region of the fine particle charging unit in the ion source. it can. In this case, a part of the compressed air can be used for cooling and the other for the ion source. Alternatively, the compressed air used for cooling can be further used in the ion source. That is, the compressed air can be used both for cooling and for ejecting ions from the ion source.

  Furthermore, in the fine particle detection system described above, the exterior member surrounds at least a part of a portion of the detection unit located outside the exhaust pipe, and uses the compressed air that has cooled the circuit unit. In the detection unit, a fine particle detection system in which at least a part of a conductive member that conducts to the circuit is cooled may be used.

In this system, at least a part of the conducting member that conducts to the circuit of the circuit unit among the detection unit is cooled using compressed air that has cooled the circuit unit via the circuit surrounding member.
As a result, in addition to the circuit unit, at least a part of the conducting member that is conducted to the circuit of the circuit unit is cooled in the detection unit, so that the influence of heat transmitted from the exhaust pipe to the circuit of the circuit unit through the conducting member is further increased. Can be suppressed.

  Furthermore, in the particulate detection system according to any one of the above, the detection unit generates, by air discharge, an ion source that generates ions and an intake exhaust gas that is taken in from the exhaust pipe is generated by the ion source. Mixing with the ions, the ions are adhered to the fine particles in the intake exhaust gas to form a mixed region as charged fine particles, and floating ions that have not adhered to the fine particles are captured among the ions. A fine particle charging unit that forms a collecting electrode to be collected, and an air passage for an ion source that guides the compressed air that has cooled the circuit unit to the ion source, and the ion source generates the generated ions, A fine particle detection system that is an ion gas injection source having a nozzle portion that injects into the mixing region together with the compressed air supplied to itself may be used.

  In this system, the detection unit has an ion source air passage that guides the compressed air, which has cooled the circuit unit via the circuit surrounding member, to the ion source. And in an ion gas injection source, the produced | generated ion is injected to a mixing area | region from a nozzle part with the compressed air supplied to self. Thereby, the compressed air can be used for both cooling and gas injection source, and the system can be made compact.

  In addition, as a format of the air discharge performed with an ion source, corona discharge is mentioned, for example. Moreover, as an arrangement form of the discharge electrodes, even if two electrodes are arranged to face each other and an air discharge is caused between them, two electrodes are arranged adjacent to each other on the substrate. A creeping discharge (in the air) may be generated.

  Furthermore, in the fine particle detection system described above, the circuit surrounding member may be a fine particle detection system that is thermally insulated from the exterior member via the gap.

  In this system, the circuit surrounding member is thermally insulated from the exterior member via a gap. Although the exterior member can also become high temperature due to heat from the exhaust pipe, the circuit surrounding member is thermally insulated from this, so that the circuit forming the circuit part in the circuit surrounding member rises in temperature due to heat conduction from the exterior member. Can also be suppressed.

  Further, in any one of the above-described particulate detection systems, the compressed air port of the exterior member is disposed at a position facing the outer surface of the side portion of the exhaust pipe near the exhaust pipe in the circuit surrounding member. A fine particle detection system is good.

  In this system, the compressed air port of the exterior member is disposed at a position facing the outer surface of the side portion of the exhaust pipe near the exhaust pipe in the circuit surrounding member. For this reason, the side close to the exhaust pipe serving as a heat source in the circuit portion can be effectively cooled.

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 an expanded sectional view of the site | part of the upper side (front end side) among the longitudinal cross-sectional views shown in FIG. 2 which shows the structure of the microparticle detection system concerning embodiment. FIG. 3 is an enlarged cross-sectional view of a lower (base end) portion of the vertical cross-sectional view shown in FIG. 2 showing the structure of the particulate detection system according to the embodiment. It is sectional drawing which shows the structure of the fine particle 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 an expanded sectional view of the site | part of the upper side (front end side) among the longitudinal cross-sectional views shown in FIG. 5 which shows the structure of the microparticle detection system concerning embodiment. FIG. 6 is an enlarged cross-sectional view of a lower (base end) portion of the vertical cross-sectional view shown in FIG. 5 showing the structure of the fine particle detection system according to the embodiment. It is a disassembled perspective view which shows the structure of the microparticle detection system concerning 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. It is a longitudinal cross-sectional view which shows the structure of the site | part of the base end side among the microparticle detection systems concerning a deformation | transformation form.

(Embodiment)
The fine particle detection system according to the present embodiment will be described with reference to the drawings. The particulate detection system 1 (see FIG. 1) of the present embodiment mainly includes a detection unit 10, a circuit unit 201, an exterior member 14, and a pressure feed pump 300 that is a compressed air source that generates compressed air AK.
The detection unit 10 is mounted on a mounting portion EPT having a mounting opening EPO in an exhaust pipe EP of an internal combustion engine (not shown) mounted on a vehicle (not shown), and has a shape extending in a substantially cylindrical shape. Yes. A part (right side (front end side) of the attachment portion EPT in FIG. 1) is arranged in the exhaust pipe EP through the attachment opening EPO, and the remaining portion (left side of the attachment portion EPT in FIG. 1 (base end side) )) Is located outside the exhaust pipe EP.
The circuit unit 201 is connected to the base end side of the detection unit 10 outside the exhaust pipe EP. That is, the particulate detection system 1 of the present embodiment has a configuration in which the detection unit 10 and the circuit unit 201 are integrated so as not to be detachable without using a cable exposed to the outside. The circuit unit 201 includes a circuit that drives the detection unit 10 and detects a signal current Is described later.
The exterior member 14 surrounds a portion of the detection unit 10 located outside the exhaust pipe EP and the periphery of the circuit unit 201. The exterior member 14 has a compressed air port 70 into which the compressed air AK supplied from the pressure feed pump 300 flows.

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, an ion source power circuit 210, and an auxiliary electrode power circuit 240.
Among these, the ion source power supply circuit 210 has a first output terminal 211 having a first potential PV1 and a second output terminal 212 having a second potential PV2. Specifically, the second potential PV2 is a positive high potential with respect to the first 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 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 has an auxiliary first output terminal 241 that is set to the first potential PV1 and an auxiliary second output terminal 242 that is set to the third potential PV3. Specifically, the third potential PV3 is a positive DC high potential with respect to the first potential PV1, but is lower than the peak potential (1 to 2 kV) of the second potential PV2, for example, DC 100 to 200 V The potential is

  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.

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 a first circuit case 250 having a first 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 first circuit case 250. .
In the present embodiment, the first circuit case 250 is made of aluminum, encloses and surrounds the ion source power circuit 210, the auxiliary electrode power circuit 240, and the secondary iron core 271B of the insulating transformer 270, and will be described later. The first conductive member 13 is conductive.

  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. However, the insulating transformer 270 separates the primary side iron core 271A and the secondary side iron core 271B through a small gap by a fourth insulating spacer 126 (described later) made of an insulating resin, and electrically insulates each other. However, in terms of the magnetic circuit, both are configured such that a common magnetic flux passes through them, so that a transforming action as the insulating transformer 270 is achieved. Of the iron core 271, the primary iron core 271A is electrically connected to the ground potential PVE, and the secondary iron core 271B is electrically connected to the first electric potential PV1 (the first output terminal 211 of the ion source power supply circuit 210).

In addition, the measurement control circuit 220 including the signal current detection circuit 230 is surrounded by a second circuit case 260 that conducts to the ground input terminal 232 of the signal current detection circuit 230 and is set to the ground potential PVE. Furthermore, 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 second circuit case 260.
In the present embodiment, the second circuit case 260 is made of aluminum, and encloses and surrounds the measurement control circuit 220 including the signal current detection circuit 230 and the primary side iron core 271A of the insulation transformer 270. The member 14 is electrically connected.

  Furthermore, the ion source power supply circuit 210, the auxiliary electrode power supply circuit 240, the first circuit case 250, the insulation transformer 270, the measurement control circuit 220 including the signal current detection circuit 230, and the second circuit case 260 are grounded to the ground potential. It is surrounded by an exterior member 14 made of PVE.

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 (not shown) and can communicate with the control unit ECU that controls the internal combustion engine via the communication line CC. The measurement result of the signal current detection circuit 230 described above ( The magnitude of the signal current Is), a value obtained by converting this into the amount of fine particles, or a signal indicating whether or not the amount of fine particles 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.

As shown by white arrows in FIGS. 1, 4, and 6, the pressure feed pump 300 takes in the atmosphere (air) around itself and is connected to the compressed air port 70 of the exterior member 14. The compressed compressed air AK is pumped through. The pressure feed pump 300 is driven to send the compressed air AK through the air feed pipe 310 at all times during the operation of the internal combustion engine.
The air supply pipe 310 is connected to the compressed air port 70 of the exterior member 14 via a joint 283. Further, the exterior member 14 forms a continuous gap GP between which the compressed air AK flows between the circuit unit 201 and a part of the detection unit 10. The first conducting member 13 described later has an inflow hole 71 that guides the compressed air AK that has passed through the exterior member 14 to the inside. Further, an air passage RA for the ion source that guides the compressed air AK to the ion gas injection source 11 is formed inside the first conducting member 13.

  The second output end 212 of the ion source power supply circuit 210 is connected to and conductive with the acicular electrode body 20 (the extending portion 21 and the acicular tip portion 22 in the ion source 11). The auxiliary second output terminal 242 of the auxiliary electrode power circuit 240 is connected to and conductive with the auxiliary electrode body 50 (the extending portion 51 and the auxiliary electrode portion 53). Further, the first output terminal 211 of the ion source power circuit 210 includes 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, the first circuit case 250, and the first conduction. Connected to member 13 and conducting to each other. In addition, the ground input terminal 232 of the signal current detection circuit 230 is connected to the ground potential PVE and the second circuit case 260 and is electrically connected to each other.

Next, the mechanical configuration of the system 1 will be described with reference to the longitudinal sectional views of FIGS. 2 to 7 and the exploded perspective view of FIG. 2 to 8, the upper side in the figure is the front end side, and the lower side in the figure is the base end side. First, the mechanical configuration of the circuit unit 201 will be described.
The first circuit case 250 is made of aluminum, and includes a small cylindrical portion 252 having a small diameter positioned on the distal end side and a large cylindrical portion 253 positioned on the proximal end side and having a larger diameter than the small cylindrical portion 252. A case main body 251 and a disc-shaped first circuit case lid 254 which is a separate body (see FIGS. 4, 7, and 8).
The first circuit mold body 280 is accommodated in the large cylindrical portion 253 of the first circuit case main body 251, and the opening of the large cylindrical portion 253 is formed in the first circuit case lid 254 (lower side in FIG. 4). Is blocked. In addition to the ion source power supply circuit 210 and the auxiliary electrode power supply circuit 240, the first circuit mold body 280 includes the secondary iron core 271B and the power supply circuit wound around the secondary transformer core 271B among the insulating transformer 270 that supplies power to these circuits. The side coil 273 and the auxiliary electrode power source side coil 274 are integrally resin-molded. In addition, as shown by a broken line in FIG. 7, a surface 271BS of the secondary side iron core 271B that is disposed in close proximity to the primary side iron core 271A is exposed from the bottom surface of the first circuit mold body 280. The primary control core 271A in the measurement control circuit 220 is disposed so as to face the surface 271AS. As described above, the secondary iron core 271B is electrically connected to the first circuit case 250 (see FIG. 1).

On the other hand, in the small cylindrical portion 252 of the first circuit case 250, connection terminals 127 and 128 and a terminal holder 129 made of an insulating resin for fixing the connection terminals 127 and 128 are accommodated.
Among these, the connection terminal 127 is connected to the second output end 212 of the ion source power supply circuit 210 having the second potential PV2 on the base end side. On the other hand, the needle electrode body 20 is connected to the distal end side of the connection terminal 127. Further, the connection terminal 128 is connected to the auxiliary second output terminal 242 of the auxiliary electrode power circuit 240 having the third potential PV3 on the base end side. On the other hand, the auxiliary electrode body 50 is connected to the distal end side of the connection terminal 128.

Further, the first output terminal 211 of the ion source power supply circuit 210 and the auxiliary first output terminal 241 of the auxiliary electrode power circuit 240 that are set to the first potential PV1 are electrically connected to the first circuit case 250. Further, the small cylindrical portion 252 of the first circuit case 250 is connected to the inner cylinder 80 forming a part of the first conductive member 13 and is electrically connected to the first conductive member 13 including the inner cylinder 80.
The first circuit case 250 is accommodated in a first outer cylinder member 110 (described later) that forms part of the exterior member 14. In addition, the first circuit case 250 includes the first outer cylinder member 110 and the second circuit case 260 via the third insulating spacer 125 made of insulating resin and the fourth insulating spacer 126 made of insulating resin. Are spaced apart and insulated.

  On the other hand, the measurement control circuit 220 including the signal current detection circuit 230, the primary side iron core 271A of the insulation transformer 270, and the primary side coil 272 wound around this are integrally configured, resin molded, and second circuit mold. It is a body 290. And this 2nd circuit mold body 290 is accommodated in the 2nd circuit case 260 made from aluminum. Specifically, the second circuit case 260 is housed in a second circuit case body 261 having a substantially bottomed cylindrical shape, and is separated from the second circuit case main body 261 by a second circuit case lid 262 having an annular plate shape. The opening (lower side in FIG. 4) of the two-circuit case main body 261 is closed. A cable 160 described later is drawn out from the central through hole 262H of the second circuit case lid 262. Further, the primary side iron core 271A is arranged such that the surface 271AS is exposed from the upper surface of the second circuit mold body 290 (see FIG. 8) and faces the surface 271BS of the secondary side iron core 271B. .

The second circuit case 260 is housed in a second outer cylinder member 115 (described later) that forms part of the exterior member 14. In addition, the second circuit case 260 (second circuit case lid 262) is formed in the second outer cylinder via a circular disc-shaped metal disc spring 132 disposed on the bottom 117S of the second outer cylinder member 115. The member 115 is electrically connected to the ground potential PVE. Further, the reference potential of the measurement control circuit 220 and the primary iron core 271A of the insulation transformer 270 are also set to the ground potential PVE through the second circuit case 260.
Further, from the measurement control circuit 220 (second circuit mold body 290) accommodated in the second circuit case 260, the cable 160 including the communication line CC and the power supply wiring BC is connected to the second outer cylinder member 115 (exterior member). 14), and the measurement control circuit 220 is connected to the battery BT and the control unit ECU via the cable 160.
In the present embodiment, the large cylindrical portion 253 of the first circuit case 250 and the second circuit case main body 261 of the second circuit case 260 correspond to a circuit surrounding member that surrounds the circuit portion 201.

Next, the first outer cylinder member 110 and the second outer cylinder member 115 forming a part of the exterior member 14 will be described (see FIGS. 4, 7, and 8).
The first outer cylinder member 110 is made of stainless steel, and has a relatively small diameter and cylindrical first cylindrical portion 111 that accommodates the proximal end portion of the inner cylinder 80 and the small cylindrical portion 252 of the first circuit case 250 inside, and The first cylindrical portion 111 is located on the proximal end side and has a second cylindrical portion 112 that is larger in diameter than the first cylindrical portion 111 and accommodates the large cylindrical portion 253 of the first circuit case 250 inside. . Further, an annular flange portion 113 bulging radially outward from the proximal end portion of the second cylindrical portion 112, and extends from the second cylindrical portion 112 to the proximal end side (downward in the figure), and a male screw is formed on the outer periphery. And a proximal end threaded portion 114 that is screwed into the second outer cylinder member 115.

  On the other hand, the second outer cylinder member 115 is also made of stainless steel, and has a substantially bottomed cylindrical cylindrical portion 117 that houses a second circuit case 260 and a fourth insulating spacer 126 (described later), and the cylindrical portion 117. It has an annular flange portion 116 that is located at the tip of the bulge and bulges outward in the radial direction. Further, the distal end portion of the cylindrical portion 117 of the second outer cylinder member 115 is formed with an internal thread on the inner peripheral surface thereof to form a distal end thread portion 117a, and is screwed with the proximal end thread portion 114 of the first outer cylinder member 110. Match. An annular O-ring holding groove 113O is formed in the flange portion 113 of the first outer cylinder member 110, and a rubber made portion is provided between the O-ring holding groove 113O and the flange portion 116 of the second outer cylinder member 115. The O-ring 131 is disposed. As described above, the first outer cylinder member 110 and the second outer cylinder member 115 are accommodated in the first circuit mold body 280 and the second circuit case 260 surrounded by the first circuit case 250. The second circuit mold body 290 is accommodated in an airtight manner.

  Further, among the cylindrical portion 117 of the second outer cylinder member 115, an insertion hole 117H is provided in the bottom portion 117S on the proximal end side. The cable 160 is drawn out of the second outer cylinder member 115 through the insertion hole 117H. Further, the cable 160 is held on the bottom 117S of the second outer cylinder member 115 by the cable holders 133 and 134 attached to the bottom 117S.

  In addition, a compressed air port 70 is provided at a position facing the outer surface of the second circuit case main body 261 (circuit surrounding member) of the second circuit case 260 in the cylindrical portion 117 of the second outer cylinder member 115. ing. An air supply pipe 310 is connected to the compressed air port 70 via a joint 283 screwed thereto. Thereby, the compressed air AK from the pressure feed pump 300 flows into the first outer cylinder member 110 and the second outer cylinder member 115 (the exterior member 14) through the air supply pipe 310 and the compressed air port 70.

  Further, the fourth insulating spacer 126 is provided between the first circuit case 250 (first circuit case cover 254) and the second circuit case 260 (between the first circuit mold body 280 and the second circuit mold body 290). Has been placed. By means of the fourth insulating spacer 126 and the third insulating spacer 125, the first circuit case 250 is removed from the first outer cylinder member 110 and the second outer cylinder member 115 forming the exterior member 14 through the gap GP. They are spaced apart and are electrically and thermally insulated. In addition, the second circuit case 260 is electrically connected to the first outer cylinder member 110 and the second outer cylinder member 115, which also form the exterior member 14, through the disc spring 132. Specifically, the fourth insulating spacer 126 and the disc spring 132 are spaced apart from each other via the gap GP and are thermally insulated. Further, the fourth insulating spacer 126 is also used to dispose the primary side iron core 271A and the secondary side iron core 271B (these surfaces 271AS and 271BS) close to each other while being separated from each other. The fourth insulating spacer 126 (see also FIG. 8) is made of an insulating resin, has a substantially H-shaped cross section, the inner wall portion 126I has a disk shape, and a substantially cylindrical side tube portion 126S around it. Have. Further, the outer peripheral surface of the side cylinder portion 126S has a large number of concave grooves 126O that form passages through which the compressed air AK taken into the second outer cylinder member 115 is sent to the distal end side.

  In addition, a third insulating spacer 125 is disposed between the large cylindrical portion 253 of the first circuit case 250 and the second cylindrical portion 112 of the first outer cylinder member 110 to insulate them from each other. Yes. The third insulating spacer 125 (see also FIG. 8) is also made of an insulating resin and has a shape in which a cylinder extends from the outer peripheral edge of the ring. However, the outer surface has a plurality of concave grooves 125O that allow passage of compressed air AK in the first outer cylinder member 110 (second cylindrical portion 112) through the first cylindrical portion 111 further toward the distal end side. It is the form which was provided.

  Next, the detection unit 10 will be described (see FIGS. 2 to 3, 5 to 6, and 8). As described above, the detection unit 10 is attached to the attachment portion EPT having the attachment opening EPO in the exhaust pipe EP of the internal combustion engine (not shown). The detection unit 10 has a portion on the distal end side (a portion above the attachment portion EPT in the drawing) located in the exhaust pipe EP, while a remaining portion on the proximal end side (below the attachment portion EPT in the drawing). Side part) is located outside the exhaust pipe EP. The circuit unit 201 is connected to the side opposite to the exhaust pipe EP (base end side) via the detection unit 10. The detection unit 10 is roughly composed of an ion source (ion gas injection source) 11, a fine particle charging unit 12, and a first conduction member 13 in terms of its electrical functions.

  As shown in FIGS. 2 and 3, the needle electrode body 20 is connected to the connection terminal 127 connected to the second output end 212 of the ion source power supply circuit 210. The needle-like electrode body 20 is made of a tungsten wire, and has a substantially straight rod-like extension portion 21 and a needle-like tip portion 22 that is located at the tip portion (upper end portion in the drawing) and has a needle-like shape. It consists of. Further, the extension portion 21 of the needle-like electrode body 20 is covered with a cylindrical needle-like electrode insulating pipe 75 made of ceramic and perforated in the metal first pipe holder 60 and the second pipe holder 61. The needle-shaped electrode insertion holes 60 </ b> H and 61 </ b> H are inserted into the first pipe holder 60 and the second pipe holder 61 together with the needle-shaped electrode insulating pipe 75.

  The auxiliary electrode body 50 is connected to the connection terminal 128 connected to the auxiliary second output terminal 242 of the auxiliary electrode power circuit 240. The auxiliary electrode body 50 is made of a stainless steel wire, and includes a substantially straight rod-like extension portion 51, a bent-back portion 52 bent back in a U shape on the tip side, and an auxiliary electrode portion 53. 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 a cylindrical auxiliary electrode insulating pipe 77 made of ceramic, and the auxiliary electrode insertion hole 60 </ b> I is formed in the first pipe holder 60 and the second pipe holder 61. , 61I and held by the first pipe holder 60 and the second pipe holder 61 together with the auxiliary electrode insulating pipe 77.

On the other hand, as shown in FIGS. 3, 4, and 6, an inner cylinder 80 having a hollow cylindrical shape made of metal is inserted in the small cylindrical portion 252 on the distal end side of the first circuit case 250. Has been. Further, a second pipe holder 61 is disposed on the distal end side of the inner cylinder 80 so as to close the inner cylinder 80, and a first pipe holder 60 is disposed on the distal end side thereof.
In addition, the inner cylinder 80 is provided with inflow holes 71 (two in this embodiment). As will be described later, the inflow hole 71 flows in compressed air AK indicated by a white arrow passing between the first cylindrical portion 111 of the first outer cylinder member 110 and the small cylindrical portion 252 of the first circuit case 250. It is guided into the inner cylinder 80 through the hole 71. The compressed air AK introduced into the inner cylinder 80 passes further through the ventilation through holes 60J and 61J (see FIG. 6) perforated in the first pipe holder 60 and the second pipe holder 61 (upper side in the figure). ) In the discharge space DS (described later). Thus, the inflow hole 71, the inner cylinder 80, and the ventilation through holes 60 </ b> J and 61 </ b> J form an ion source ventilation path RA that pumps the compressed air AK toward the discharge space DS.
The inner cylinder 80 is electrically connected to the first output terminal 211 of the ion source power supply circuit 210 through the first circuit case 250 (small cylindrical portion 252), and is set to the first potential PV1.

The first pipe holder 60 and the second pipe holder 61 shown in FIGS. 3 and 6 are both made of stainless steel. Among these, the first pipe holder 60 has a substantially cylindrical main body 63 and an annular holder flange 66 that bulges radially outward from a position closer to the proximal end of the main body 63. . Moreover, the 2nd pipe holder 61 is a substantially cylindrical shape, and it is inserted by the base end side of the 1st pipe holder 60, and makes this integral. Further, the first pipe holder 60 and the second pipe holder 61 are respectively provided with needle-like electrode insertion holes 60H and 61H, auxiliary electrode insertion holes 60I and 61I, and ventilation through holes 60J and 61J extending in the vertical direction in the drawing. As described above, the extending portion 21 of the needle electrode body 20 is in the needle electrode insertion holes 60H and 61H, and the extension portion of the auxiliary electrode body 50 is in the auxiliary electrode insertion holes 60I and 61I. 51 is inserted and held. Further, the needle-like tip portion 22 of the needle-like electrode body 20 projects from the main body portion 63 on the tip side (upward in the drawing) of the main body portion 63.
The first pipe holder 60 and the second pipe holder 61 are fitted and fixed to the first pipe holder 60 to the second pipe holder 61 and the second pipe holder 61 to the inner cylinder 80, respectively. Even continuity. The first pipe holder 60, the second pipe holder 61, and the inner cylinder 80 form the first conductive member 13 that surrounds the extension portion 21 of the needle electrode body 20 and the extension portion 51 of the auxiliary electrode body 50. ing.

Furthermore, a bottomed cylindrical nozzle member 30 having a bottom on the tip side is fitted on the tip side (upward in the drawing) of the first pipe holder 60. This nozzle member 30 is also made of stainless steel. Further, the bottom portion on the tip side of the nozzle member 30 is a nozzle portion 31. The nozzle portion 31 has a concave shape whose center is directed to the tip side, and a fine through hole is formed at the center to form a nozzle 31N.
In addition, the nozzle member 30 is fitted and fixed to the distal end portion of the first pipe holder 60, and is electrically connected to the first potential PV1.

In this manner, the nozzle member 30 is fitted into the distal end side (upper side in the drawing) of the main body portion 63 of the first pipe holder 60, so that a discharge space DS is formed in these. In the discharge space DS, the needle-like tip portion 22 of the needle-like electrode body 20 protrudes from the first pipe holder 60, and the needle-like tip portion 22 is a surface on the base end side of the nozzle portion 31 and has a concave shape. It faces the opposing surface 31T. 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). The compressed air AK indicated by the white arrow is also supplied to the discharge space DS through the ventilation through holes 60J and 61J (the ion source ventilation path RA) drilled in the first pipe holder 60 and the second pipe holder. 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.

Further, a cylindrical relay cylinder 33 (see also FIG. 8) is fitted on the tip end side of the nozzle member 30. This relay cylinder 33 is also made of stainless steel, and an intake port 33I (see FIG. 6) (perforated toward the downstream side of the exhaust pipe EP) is perforated on a side surface thereof. As will be described later, the intake port 33I is an opening for taking the exhaust gas EG into a mixing region MX (described later) formed by the nozzle member 30, the relay cylinder 33, and the mixing and discharging member 40.
In addition, the relay cylinder 33 is fitted and fixed to the nozzle member 30 and is electrically connected to the nozzle member 30 to be set to the first potential PV1.

Furthermore, a mixing / discharging member 40 (see also FIG. 8) is fitted on the distal end side (upper side in the drawing) of the relay cylinder 33. The mixing and discharging member 40 is also made of stainless steel, is located on the base end side (lower side in the figure), has a base end portion 41 having a structure described below, and a cylinder extending from the periphery of the base end portion 41 to the front end side. And a distal end side cylindrical wall portion 43. Further, the distal end side cylindrical wall portion 43 is closed by covering the lid member 48 from the distal end side. 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 intake port 33I of the relay cylinder 33.
In addition, the mixed discharge member 40 is fitted and fixed to the relay cylinder 33 and is electrically connected to the first potential PV1.

  Thus, the front end side surface 31S of the nozzle portion 31 of the nozzle member 30 facing upward in the figure, the relay tube 33, and the base end portion 41 (collecting electrode 42) of the mixed discharge member 40 are schematically inside the relay tube 33. A cylindrical space is formed. This space forms a cylindrical mixed region MX1 in the mixed region MX. 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 space MX, and is discharged from the discharge port 43O via the discharge path EX together with the air AR.

  Further, the extension portion 51 of the auxiliary electrode body 50 and the auxiliary electrode insulating pipe 77 surrounding the auxiliary electrode body 50 described above are further provided than the auxiliary electrode insertion holes 60I and 61I in the first pipe holder 60 and the second pipe holder 61. It extends to the front end side (upper side in the drawing) and passes through the nozzle portion 31 of the nozzle member 30, the relay cylinder 33, and the mixing and discharging member 40. Further, the bent-back portion 52 connected to the extending portion 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 FIGS. 3 and 6, the front end side (upper side in the drawing) of the holder flange portion 66 of the first pipe holder 60 is made of an insulating ceramic such as alumina, and the main body portion 63 of the first pipe holder 60. The first insulating spacer 121 having a substantially cylindrical shape surrounding the connecting portion with the nozzle member 30 is disposed. Further, the proximal end side (lower side in the drawing) of the holder flange portion 66 is also made of an insulating ceramic such as alumina, and has a substantially cylindrical shape surrounding the proximal end portion of the first pipe holder 60 and the second pipe holder 61. A second insulating spacer 122 is disposed. Further, a metal spacer 123 that engages with the second insulating spacer 122 is fitted on the base end side periphery of the second insulating spacer 122. Further, a metal shell 90 and a plug metal fitting 100 made of stainless steel are arranged around these radial directions (left and right in the figure).

Among these, the metal shell 90 includes a cylindrical portion 91 and a flange portion 95. Among these, the substantially cylindrical tubular portion 91 has a holding hole 91H for holding the first pipe holder 60, the second pipe holder 61, the first insulating spacer 121, and the second insulating spacer 122 therein. ing. 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 metal shell 90, the stopper fitting 100 advances to the distal end side, and the distal end pressing portion 101 contacts the spacer 123 on the distal end side. Then, the second insulating spacer 122 is pressed to the tip side. Then, this 2nd insulation spacer 122 presses the holder flange part 66 of the 1st pipe holder 60 toward the front end side. Further, the holder flange portion 66 of the first pipe holder 60 presses the first insulating spacer 121 toward the tip 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. As a result, the first pipe holder 60, the second pipe holder 61, the first insulating spacer 121, the second insulating spacer 122, the spacer 123, and the plate packing 124 include the plug fitting 100 and the metallic shell that form part of the exterior member 14. 90, and surrounded.
In addition, a first insulating spacer 121 and a second insulating spacer 122 are interposed between the first pipe holder 60 and the second pipe holder 61 and the metal shell 90 and the plug metal fitting 100 so that they are separated and insulated. Yes. Of the first pipe holder 60, the holder flange portion 66 projecting radially outward and the metal shell 90 (cylindrical portion 91) are spaced apart from each other to maintain insulation therebetween. I'm leaning.

When mounting the detection unit 10, as shown in FIGS. 5 and 6, the nozzle member 30, the relay cylinder 33, the mixed discharge member 40, etc. are exhausted from the mounting opening EPO of the mounting unit EPT in the exhaust pipe EP. The stud bolts EPB and EPB provided adjacent to the mounting opening EPO are inserted into the pipe EP and inserted into the bolt through holes 95H of the flange portion 95, respectively, 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.
Further, the first cylindrical portion 111 of the first outer cylinder member 110 made of stainless steel already described is connected to the base end portion 104 of the stopper fitting 100.
Thereby, the gasket 130, the metal shell 90, the plug metal fitting 100, the first outer cylinder member 110, and the second outer cylinder member 115 are set to the same ground potential PVE as that of the exhaust pipe EP.

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. 9 in addition to FIGS. Note that FIG. 9 schematically shows the electrical function and operation of the detection unit 10 of the system 1 for easy understanding, and there are parts different from the forms described in other figures. 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. Therefore, as described above, the needle-like electrode body 20 is set to the second potential PV2, which is a positive half-wave rectified pulse voltage of 100 kHz and 1 to 2 kV0-p with respect to the first potential PV1.
The auxiliary electrode body 50 is connected to and conductive with the auxiliary second output terminal 242 of the auxiliary electrode power circuit 240. Therefore, as described above, the auxiliary electrode body 50 is set to the third potential PV3 that is a positive DC potential of 100 to 200 V with respect to the first potential PV1.
Further, the inner cylinder 80, the first pipe holder 60, the second pipe holder 61, the nozzle member 30, the relay cylinder 33, and the mixing and discharging member 40 are connected to the first output terminal 211 of the ion source power circuit 210 and the auxiliary electrode power circuit 240. The auxiliary first output terminal 241, the first 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 set to the first potential PV1.
In addition, the first outer cylinder member 110, the second outer cylinder member 115, the disc spring 132, the plug fitting 100, the metal shell 90, and the gasket 130 are the second circuit surrounding the measurement control circuit 220 including the signal current detection circuit 230. The case 260 and the ground input terminal 232 of the signal current detection circuit 230 are connected and conductive. These are set to the same ground potential PVE as the exhaust pipe EP.

Therefore, as described above, between the nozzle portion 31 (opposing surface 31T) set to the first potential PV1 and the needle-like tip portion 22 set to the second potential PV2 that is a positive potential higher than this, 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 22 and the nozzle portion 31 of the nozzle member 30 correspond to two electrodes that generate air discharge (corona discharge). Further, the nozzle member 30, the nozzle portion 31, and the needle-like tip portion 22 surrounding the discharge space DS serve as the ion source 11 and the ion gas ejection source 11.

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 that 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 set to the first potential PV1. The mixed discharge member 40 (the base end portion 41 and the distal end side cylindrical wall portion 43) forming 42 adheres to each portion and is not discharged (captured).

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 portion 31 of the nozzle member 30, the relay cylinder 33, the mixing 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 portion 12.

The first pipe holder 60, the second pipe holder 61, and the inner cylinder 80 are electrically connected to the fine particle charging unit 12 and the nozzle part 31 of the nozzle member 30 included therein, while the needle electrode body 20 is extended. The portion 21 and the extending portion 51 of the auxiliary electrode body 50 are surrounded in the radial direction.
In the present embodiment, the first pipe holder 60, the second pipe holder 61, and the inner cylinder 80 correspond to the first conduction member 13.
The ion gas ejection source 11, the fine particle charging unit 12, and the first conduction member 13 form a detection unit 10.

Further, the metal shell 90, the plug metal fitting 100, the first outer cylinder member 110, and the second outer cylinder member 115 are electrically connected to the exhaust pipe EP and set to the ground potential PVE, while the fine particle charging unit 12 (nozzle) The nozzle portion 31 of the member 30) and the first conductive member 13 (such as the inner cylinder 80) are electrically insulated.
In the present embodiment, the metal shell 90, the plug metal fitting 100, the first outer cylinder member 110, and the second outer cylinder member 115 correspond to the exterior member 14.
Of the exterior member 14, the cylindrical portion 91 of the metallic shell 90, the stopper fitting 100, and the first cylindrical portion 111 of the first outer cylindrical member 110 are the fine particle charging portion 12, the ion gas ejection source 11, and the first conduction. The member 13 surrounds a portion located outside the exhaust pipe EP (below the exhaust pipe EP in FIGS. 2 and 5). Specifically, the proximal portion of the extension portion 21 of the needle electrode body 20 and the extension portion 51 of the auxiliary electrode body 50, the diameters of the first pipe holder 60, the second pipe holder 61, and the inner cylinder 80. Surrounds the direction.

  As described above, through the compressed air port 70 provided in the second outer cylinder member 115 of the exterior member 14, the first outer cylinder member 110 and the second outer cylinder member 115 forming the exterior member 14 Compressed air AK from the pressure pump 300 flows in. Further, a gap GP through which the compressed air AK flows is formed between the exterior member 14 and the first circuit case 250 and the second circuit case 260. As a result, the compressed air AK flowing into the exterior member 14 flows through the gap GP, and passes through the first circuit case 250 (large cylindrical portion 253) and the second circuit case 260 (second circuit case body 261). Thus, the circuit unit 201 is cooled.

The compressed air port 70 is provided in the second outer cylinder member 115 of the exterior member 14 and faces the outer surface of the second circuit case main body 261 (circuit enclosure member) of the second circuit case 260. Is arranged. For this reason, the compressed air AK that has passed through the compressed air port 70 directly hits the second circuit case 260, and then flows through the gap GP between the exterior member 14, the first circuit case 250, and the second circuit case 260. Thus, the first circuit case 250 is also cooled. That is, the entire circuit unit 201 is cooled from the outside.
The circuit unit 201 is held in the exterior member 14 via the gap GP by the third insulating spacer 125, the fourth insulating spacer 126, and the disc spring 132. For this reason, the circuit unit 201 is thermally insulated from the exterior member 14.

  Further, the compressed air AK that has cooled the circuit part 201 passes between the small cylindrical part 252 of the first circuit case 250 and the first cylindrical part 111 of the first outer cylinder member 110, and Led during. In this process, the inner cylinder 80 as the first conductive member 13 is cooled from the outside.

  Furthermore, it flows into the inner cylinder 80 through the inflow hole 71 opened in the inner cylinder 80. In the inner cylinder 80, as described above, the extension portion 21 of the needle electrode body 20 surrounded by the needle electrode insulation pipe 75 and the extension portion of the auxiliary electrode body 50 surrounded by the auxiliary electrode insulation pipe 77 are provided. 51 is arranged. Therefore, the compressed air flowing in from the inflow hole 71 hits, and the extension part 21 of the needle electrode body 20 and the extension part 51 of the auxiliary electrode body 50 are cooled in the inner cylinder 80.

  Further, when the compressed air AK moves (circulates) to the tip side, the inner cylinder 80 is cooled from the inside. Thereafter, the compressed air AK is supplied to the ion gas injection source 11 through the ventilation through holes 60J and 61J.

Since the detection unit 10 is attached to the exhaust pipe EP, heat is transmitted from the exhaust gas EG or the exhaust pipe EP, and the temperature can be high. For this reason, heat is transferred from the detection unit 10 that has reached a high temperature to the circuit unit 201, and the circuit of the circuit unit 201 is also likely to have a high temperature.
On the other hand, in the system 1 of this embodiment, the large cylindrical portion 253 of the first circuit case 250 and the second circuit case body 261 of the second circuit case 260, which are circuit surrounding members surrounding the circuit portion 201, And the exterior member 14 (the 1st outer cylinder member 110, the 2nd outer cylinder member 115) which encloses the outer surface of these circuit surrounding members 253 and 261 via the space | gap GP is provided. Then, the compressed air AK flowing into the exterior member 14 is caused to flow into the gap GP between the outer surface of the circuit surrounding members 253 and 261 and the exterior member 14, and the circuit unit 201 is moved through the circuit surrounding members 253 and 261. It is cooling.
For this reason, the temperature of the circuit of the circuit unit 201 rises due to the heat from the exhaust pipe EP, and it is possible to suppress the influence of heat that causes a temperature drift or failure of circuit components.
Thus, in the system 1 of the present embodiment, the detection unit 10 and the circuit unit 201 are connected in series, and the entire system is made compact, but the influence of heat transmitted from the exhaust pipe EP to the circuit unit 201 is suppressed, and the exhaust gas is reduced. The amount of fine particles S in the EG can be detected appropriately.
Moreover, since the circuit unit 201 is surrounded by the circuit surrounding members 253 and 261 and the compressed air AK is not directly applied to each circuit such as the ion source power circuit 210 and the auxiliary electrode power circuit 240 of the circuit unit 201, the circuit unit 201 is It is possible to reliably prevent noise caused by the flow of the compressed air AK from being superimposed on the signal. In addition, since the compressed air AK introduced from the compressed air port 70 directly hits the outer surface of the circuit surrounding members 253 and 261 (in this embodiment, the second circuit case body 261 of the second circuit case 260), The circuit unit 201 can be appropriately cooled via the members 253 and 261.

Furthermore, in the system 1 of the present embodiment, the first conduction that is conducted to the ion source power supply circuit 210 and the auxiliary electrode power supply circuit 240 of the circuit unit 201 in the detection unit 10 using the compressed air AK that has cooled the circuit unit 201. The member 13, the extending part 21 of the needle electrode body 20, and the extending part 51 of the auxiliary electrode body 50 are cooled.
In addition to the circuit unit 201, in the detection unit 10, the first conduction member 13 that conducts to the ion source power supply circuit 210 and the auxiliary electrode power supply circuit 240 of the circuit unit 201, the extension part 21 of the needle electrode body 20, and the auxiliary electrode body By cooling at least a part (all three in this example) of the 50 extension parts 51, heat transmitted from the exhaust pipe EP to the ion source power supply circuit 210 and the auxiliary electrode power supply circuit 240 of the circuit part 201 through them is cooled. The influence can be further suppressed.

  Furthermore, in the system 1 of the present embodiment, the detection unit 10 has an ion source air passage RA that guides the compressed air AK that has cooled the circuit unit 201 to the ion source 11. And in the ion gas injection source 11, the produced | generated ion CP is injected to the mixing area | region MX from the nozzle part 31 with the compressed air AK supplied to self. Accordingly, the compressed air AK can be used for both cooling and gas injection source, and the system can be made compact.

Furthermore, in the system 1 of this embodiment, the circuit surrounding members 253 and 261 are thermally insulated from the exterior member 14 via the gap GP.
Although the exterior member 14 can also become high temperature due to heat from the exhaust pipe EP, the circuit surrounding members 253 and 261 are thermally insulated from this, and therefore, the ion source power supply circuit 210 that forms the circuit portion 201 in the circuit surrounding members 253 and 261. It is also possible to suppress the temperature rise of each circuit such as the auxiliary electrode power supply circuit 240 and the like due to heat conduction from the exterior member 14.

(Deformation)
Next, a modification of the above-described embodiment will be described with reference to FIG. In the particulate detection system 1 of the above-described embodiment, the compressed air port 70 is provided on the cylindrical wall (cylindrical portion 117) of the second outer cylindrical member 115 in the exterior member 14, and the compressed air port 70 is screwed. The air supply pipe 310 was connected via the joint 283 thus made, and the compressed air AK from the pressure pump 300 was allowed to flow into the exterior member 14. Accordingly, the compressed air AK that has passed through the compressed air port 70 is out of the large cylindrical portion 253 of the first circuit case 250 and the second circuit case main body 261 of the second circuit case 260 that are circuit surrounding members that surround the circuit portion 201. The second circuit case body 261 of the second circuit case 260 on the side away from the exhaust pipe EP directly hits.

  On the other hand, in the system 1A of the present modification shown in FIG. 10, the compressed air port 70A is provided on the cylindrical wall (second cylindrical portion 112) of the first outer cylindrical member 110 near the exhaust pipe EP in the exterior member 14. The compressed air port 70A is disposed at a position facing the outer surface of the large cylindrical portion 253 of the first circuit case 250 near the exhaust pipe EP, among the circuit surrounding members 253 and 261 surrounding the circuit portion 201. Has been. An air supply pipe 310A is connected to the compressed air port 70A via a joint 283A screwed thereto. Therefore, the compressed air AK pumped from the pressure pump 300 and passed through the compressed air port 70A directly hits the large cylindrical portion 253 of the first circuit case 250 near the exhaust pipe EP among the circuit surrounding members. .

As a result, the system 1A according to the present modified embodiment can effectively cool the side close to the exhaust pipe EP serving as a heat source in the circuit unit 201 in addition to the same effects as the embodiment.
In this modification, the large cylindrical portion 253 of the first circuit case 250 corresponds to the exhaust pipe side portion of the circuit surrounding member.

In the above, the present invention has been described based on the system 1 of the embodiment and the system 1A of the modified embodiment. However, the present invention is not limited to the embodiment and the modified embodiment, and may be appropriately selected without departing from the gist thereof. Needless to say, it can be changed and applied.
For example, in the above embodiment, the compressed air AK after the circuit unit 201 is cooled is the first conductive member 13 (inner cylinder 80), the extension part 21 of the needle electrode body 20, and the extension part of the auxiliary electrode body 50. All 51 were cooled. However, at least one of them may be cooled.
In the above-described embodiment, the compressed air AK used for cooling the circuit unit 201 via the circuit surrounding members 253 and 261 is used for cooling the extension portion 51 of the auxiliary electrode body 50 and the ion gas injection is further performed. The example which injected from the source 11 was shown. However, it may be used only for cooling the circuit unit 201 via the circuit surrounding members 253 and 261.

EP Exhaust pipe EPO Mounting opening EPT Mounting part EG Exhaust gas EGI Intake exhaust gas S Particulate SC Charged particulate CP Ion CPF Floating ion CPH Discharged ion Ijh Received collection current Is Signal current 1, 1A Particulate detection system 10 Detection part 11 Ion gas Injection source (ion source)
DS Discharge space 12 Particulate charging part 13 First conducting member 14 Exterior member 20 Needle-like electrode body 21 Extension part 22 (needle-like electrode body) Needle-like tip part (ion source)
30 Nozzle member (ion source)
31 Nozzle part (ion source, fine particle charging part)
31T (nozzle part) facing surface 31N nozzle 33 relay cylinder (particulate charging part)
33I Intake PV1 First potential PV2 Second potential PV3 Third potential PVE Ground potential 40 Mixing discharge member (particulate charging part)
MX mixing region MX1 cylindrical mixing region MX2 slit-shaped mixing region 42 collection electrode 43O discharge port 48 lid member (particulate charging unit)
50 Auxiliary electrode body 51 (Auxiliary electrode body) Extension part 53 (Auxiliary electrode body) Auxiliary electrode part 60 First pipe holder (first conduction member)
61 Second pipe holder (first conducting member)
60J, 61J Ventilation through hole (Ventilation path for ion source)
80 Inner cylinder (first conductive member)
90 Metal shell (exterior material)
100 Plug fitting (exterior material)
110 First outer cylinder member (exterior member)
115 Second outer cylinder member (exterior member)
126 Fourth insulating spacer 160 Cables 70, 70A Compressed air port 71 Inflow hole RA Air path for ion source AK Compressed air (gas)
AR Air (gas)
GP gap 300 pressure pump 201 circuit unit 210 ion source power supply circuit 211 first output terminal 212 second output terminal 220 measurement control circuit 230 signal current detection circuit 231 signal input terminal 232 ground input terminal 240 auxiliary electrode power circuit 241 auxiliary first output End 242 auxiliary second output end 250 first circuit case 253 large cylindrical portion (circuit surrounding member, exhaust pipe side portion)
260 2nd circuit case 261 2nd circuit case main body (circuit surrounding member)
270 Insulation transformer (auxiliary electrode insulation transformer)
271 Iron core 271A (of the insulation transformer) Primary side iron core 271B (of the insulation transformer) Secondary side iron core 272 (of the insulation transformer) Primary side coil 273 (of the insulation transformer) Power supply circuit side coil 274 (of the insulation transformer) ) Auxiliary electrode power supply side coil

Claims (5)

A particulate detection system for detecting the amount of particulates in exhaust gas flowing through an exhaust pipe,
A detection unit mounted on the exhaust pipe;
A circuit unit that is connected to the detection unit outside the exhaust pipe and has a circuit that drives the detection unit and detects the amount of the fine particles;
A circuit surrounding member surrounding the circuit portion;
An exterior member that surrounds the outer surface of the circuit surrounding member via a gap and has a compressed air port through which compressed air flows in at a position facing the outer surface of the circuit surrounding member,
The compressed air that has flowed into the exterior member through the compressed air port is caused to flow into the gap between the outer surface of the circuit surrounding member and the exterior member, and the circuit portion is interposed via the circuit surrounding member. A particulate detection system configured to cool the water. The particulate detection system according to claim 1,
The exterior member is
Surrounding at least a part of a portion of the detection unit located outside the exhaust pipe,
A fine particle detection system formed by cooling at least a part of a conducting member connected to the circuit in the detection unit using the compressed air that has cooled the circuit unit. The fine particle detection system according to claim 1 or 2,
The detector is
An ion source that generates ions by air discharge,
The intake exhaust gas taken in from the exhaust pipe is mixed with the ions generated by the ion source, and the ions are attached to the fine particles in the intake exhaust gas, thereby forming a mixed region for forming charged fine particles. In addition, a fine particle charging portion that forms a collecting electrode for collecting floating ions that did not adhere to the fine particles among the ions, and
The compressed air that has cooled the circuit unit has an ion source air passage that guides the ion source to the ion source;
The ion source is
The fine particle detection system which is an ion gas injection source which has the nozzle part which injects the produced | generated said ion to the said mixing area | region with the said compressed air supplied to self. The fine particle detection system according to any one of claims 1 to 3,
The circuit surrounding member is
The exterior member is a particulate detection system that is thermally insulated via the gap. The fine particle detection system according to any one of claims 1 to 4,
The compressed air port of the exterior member is
A fine particle detection system arranged at a position facing the outer surface of the side of the exhaust pipe close to the exhaust pipe in the circuit surrounding member.

Images