JP5782412B2 - 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, a gas containing ionized positive ion particles is injected from an injection hole, mixed with a gas to be measured containing fine particles taken into a channel, charged with fine particles, and then discharged. 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 particle detection system, the detection unit attached to the vent pipe and the drive detection circuit that drives the detection unit and detects the amount of particles are arranged apart from each other, and both are connected using a cable. There is a configuration one. This is because a ventilation pipe such as an exhaust pipe can be at a high temperature, so that heat from the exhaust pipe at a high temperature is not easily transmitted to the circuit, and the arrangement of the drive detection circuit is facilitated.
However, such a cable is composed of a plurality of conductors and insulators, and when the cable vibrates, static electricity due to friction is generated between the conductors and the insulator, and the surface of the insulator is charged. There is a case. And when such electrostatic charging occurs, there is a possibility that static noise is generated and the amount of fine particles cannot be detected properly.

  The present invention has been made in view of such problems, and provides a particulate detection system capable of appropriately detecting the amount of particulates while suppressing static electricity from being charged on the surface of an insulating layer in a cable. It is.

  One aspect of the present invention for solving the above-described problems is a particulate detection system that detects the amount of particulates in a gas to be measured that flows in the ventilation pipe, the detection section being attached to the ventilation pipe, and the detection A drive detection circuit that drives the unit and detects the amount of the fine particles, and a cable made of a plurality of wiring members that electrically connect the detection unit and the drive detection circuit, the detection unit, A first potential member that is a first potential, a second potential member that is a second potential different from the first potential, and a third potential that is a third potential different from the first potential and the second potential. The cable has a potential member, and the cable is connected to the second potential member, the second potential wire is connected to the first potential member, surrounds the radial periphery of the second potential wire, and is braided and spiraled. 1st which consists of at least any one of the strip | belt-shaped metal foil wound around A peripheral wiring, surrounding the radial direction of the second potential wiring, disposed between the second potential wiring and the first potential wiring, and insulating the 2-1 insulating layer between the second potential wiring and the third potential wiring; A third potential wiring which is electrically connected to the potential member, surrounds the radial periphery of the first potential wiring, and is composed of at least one of a braided or spirally wound metal foil, and the radial periphery of the first potential wiring And is disposed between the first potential wiring and the third potential wiring, and is integrated with the insulating 1-3 to 1-3 insulating layer and the 1-3 insulating layer to insulate the two. Covering the radial inner surface, and covering the radial outer surface integrally with the conductive first conductive coating layer contacting the first potential wiring and the 1-3 insulator layer, A conductive third conductive coating layer in contact with the third potential wiring, wherein the first potential wiring and the first potential wiring In the potential lines, with surrounds the second potential wiring doubly a particle detection system is a double surrounding cables surrounding the first potential wiring in the third potential wiring.

In this fine particle detection system, the double surrounding cable having the above-described configuration is used as a cable for connecting the detection unit and the drive detection circuit. In the double surrounding cable, the first potential wiring and the third potential wiring double surround the second potential wiring, and the third potential wiring surrounds the first potential wiring. Between the first potential wiring and the third potential wiring, an 1-3 insulator layer that insulates both is disposed. Moreover, the radially inner surface of the 1-3 insulator layer is covered with a conductive first conductive coating layer integrated with the 1-3 insulator layer, and the first potential wiring is the first potential wiring. 1 is in contact with the conductive coating layer. In addition, the radially outer surface of the 1-3 insulator layer is covered with a conductive third conductive coating layer integrated with the 1-3 insulator layer, and the third potential wiring is the first potential wiring. 3 is in contact with the conductive coating layer.
Here, a case where the first conductive coating layer and the third conductive coating layer are not provided on the radially inner surface and the radially outer surface of the 1-3 insulator layer is considered. When such a cable vibrates, static electricity due to friction is generated between the first potential wiring and the third potential wiring that are conductors and the insulating layer between 1-3 that is an insulator, and insulation between 1-3 is performed. The inner and outer surfaces of the body layer are easily charged.

  However, in this system, the first conductive coating layer and the third conductive coating layer are respectively provided integrally on the inner and outer surfaces of the 1-3 insulator layer. For this reason, even if the cable vibrates, the insulation layer between 1-3 does not touch the first potential wiring or the third potential wiring, and friction between them does not occur. The body layer is less likely to be charged by static electricity. That is, in this system, static electricity can be suppressed from being charged between the first potential wiring and the third potential wiring. Thus, the amount of fine particles can be detected appropriately.

  In addition, as the 1-3 insulating layer, the first conductive covering layer, and the third conductive covering layer, a fluorine-based insulating resin such as FEP is used for the 1-3 insulating layer, An example is one in which a conductive resin layer in which carbon is added to a resin is integrally formed.

  Further, in the fine particle detection system described above, the detection unit includes a first discharge electrode and a second discharge electrode, and an ion source that generates ions by an air discharge between the first discharge electrode and the second discharge electrode, and the first of the ion source. A portion of the gas to be measured that is conducted to one discharge electrode and circulates in the ventilation tube is mixed with the ions generated by the ion source, and the fine particles in the part of the gas to be measured are ionized. The charged fine particles to which the particles are attached are returned to the inside of the vent pipe, and the fine particle charging portion forming the collecting electrode for collecting the floating ions not attached to the fine particles among the ions, the first discharge electrode, and the fine particle charging A first conductive member that is the first potential member that is conductive to the first portion and the second potential electrode that is conductive to the second discharge electrode and the second potential member. Conductive member and above A first potential wiring that is connected to the first conductive member and has a ground potential member that is a third potential member and is a ground potential that is the third potential. And the third potential wiring, and the ground potential wiring conducting to the ground potential member double electromagnetically shields the second potential wiring conducting to the second electrode conducting member, and the ground potential wiring Therefore, it is preferable that the first potential wiring be a fine particle detection system in which the first potential wiring is electromagnetically shielded.

  In this system, the ground potential wiring as the third potential wiring is electrically connected to the ground potential member that is set to the ground potential, and the first potential wiring is electrically connected to the first discharge electrode and the fine particle charging portion of the ion source. 1 Conductive to the conducting member. Then, the first potential wiring of the first potential and the ground potential wiring of the ground potential double electromagnetically shield the second potential wiring of the second potential conducting to the second discharge electrode and the second electrode conducting member of the ion source. doing. Further, the first potential wiring of the first potential is electromagnetically shielded by the ground potential wiring of the ground potential.

Further, this system has the above-described fine particle charging unit, and the amount of charge returned from this to the vent pipe as charged fine particles corresponds to the amount of fine particles. Here, the signal current flowing between the first potential, which is the potential of the fine particle charging portion, and the ground potential conducted to the ventilation tube corresponds to the amount of charge returned from the fine particle charging portion to the ventilation tube. In this system, the first potential wiring is conducted to the fine particle charging unit, and the ground potential wiring as the third potential wiring is conducted to the ground potential member that is set to the ground potential. Further, the first potential wiring and the second potential wiring are respectively conducted to the first discharge electrode and the second discharge electrode of the ion source, and a discharge current flows between them.
For this reason, the first potential wiring, the second potential wiring, and the ground potential wiring have the double shield structure as described above and are electromagnetically shielded from each other. And less affected by external electromagnetic noise. Furthermore, as described above, since the influence of static electricity can be suppressed, the amount of fine particles can be detected appropriately.

  Further, in the fine particle detection system described above, the vent pipe may be an exhaust pipe of an on-board 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.

  When this system is mounted on a vehicle, the cable tends to vibrate as the vehicle is driven, and therefore friction is likely to occur in the cable. On the other hand, the cable used in this system has a double-enclosed cable structure and covers the inner and outer surfaces of the 1-3 insulator layer with the conductive first conductive coating layer and the third conductive coating layer. Even if the vibration due to the operation is applied to the cable, static electricity due to friction is hardly generated in the 1-3 insulator layer. For this reason, the amount of fine particles can be detected appropriately.

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 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 transverse cross section showing the structure of a cable among particulate detection systems concerning an 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 cable 160 (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, 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 electrically connected to the first output terminal 211 and is set to the first potential PV1, and an auxiliary second output terminal 242 that is set to the auxiliary electrode potential PV3. ing. Specifically, the auxiliary electrode 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 detects a signal current Is flowing between the signal input terminal 231 and the ground input terminal 232.

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 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 houses 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 also includes a first cable 160 described later. It is electrically connected to the potential wiring 165.

  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 and electrically insulates each other, but a common magnetic flux passes through both in terms of magnetic circuit. With such a configuration, a metamorphic 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).

Further, the measurement control circuit 220 including the ion source power supply circuit 210, the auxiliary electrode power supply circuit 240, the inner circuit case 250, and the signal current detection circuit 230 is connected to the ground input terminal 232 of the signal current detection circuit 230 and connected to the ground potential. It is surrounded by an outer circuit case 260 made of 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 this embodiment, the outer circuit case 260 includes the ion source power supply circuit 210, the auxiliary electrode power supply circuit 240, the inner circuit case 250, the measurement control circuit 220 including the signal current detection circuit 230, and the primary of the insulation transformer 270. The side iron core 271A is accommodated and surrounded, and is electrically connected to a third potential wiring 167 of the cable 160 described later.

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 the microprocessor 100 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 FIGS. 2 and 4). The cable 160 is a double-enclosed cable, and a second potential wiring 161 and auxiliary potential wiring 162 made of copper wire and a hollow air pipe 163 made of PTFE are arranged at the center of the cable 160. These radial circumferences are surrounded by an inner insulator layer 164. Specifically, first, the second potential wiring 161 and the auxiliary potential wiring 162 are respectively covered with an insulating second potential wiring covering layer 164a and auxiliary potential wiring covering layer 164b made of FEP. Further, an insulating inner insulating fiber made of glass fiber in which the fiber stretching direction is aligned with the longitudinal direction of the cable 160 around and between the second potential wiring covering layer 164a, the auxiliary potential wiring covering layer 164b, and the air pipe 163. It is surrounded by the member 164c. Further, an inner insulating coating layer 164d is formed by winding an insulating tape made of PTFE around the second potential wiring coating layer 164a, the auxiliary potential wiring coating layer 164b, the air pipe 163, and the inner insulating fiber member 164c. Thus, the periphery of the second potential wiring 161 in the radial direction is surrounded by the third potential wiring coating layer 164a, the inner insulating fiber member 164c, and the inner insulating coating layer 164d. In addition, the auxiliary potential wiring 162 is surrounded by three of the auxiliary potential wiring covering layer 164b, the inner insulating fiber member 164c, and the inner insulating covering layer 164d. That is, in the inner insulator layer 164 (insulator layer 2-1) composed of these second potential wiring covering layer 164a, auxiliary potential wiring covering layer 164b, inner insulating fiber member 164c and inner insulating covering layer 164d, The second potential wiring 161 and the auxiliary potential wiring 162 are surrounded around the radial direction.

Further, the inner periphery of the inner insulating layer 164 (inner insulating covering layer 164d) is surrounded by a first potential wiring 165 made of a braided copper fine wire. In addition, an insulating insulating coating layer 166 (an insulating layer between 1 and 3) made of FEP is disposed around the first potential wiring 165 in the radial direction. However, the radially inner surface 166U of the insulator coating layer 166 is integrated with the insulator coating layer 166, and is covered with a conductive first conductive coating layer 166a made of carbon-containing FEP. 165 is in contact with the first conductive coating layer 166a. Further, the radially outer surface 166S of the insulator coating layer 166 is also integrated with the insulator coating layer 166 and covered with a conductive third conductive coating layer 166b made of carbon-containing FEP. Further, the circumference in the radial direction is covered with a third potential wiring 167 made of a braided copper fine wire. Therefore, the third potential wiring 167 is also in contact with the third conductive coating layer 166b, not the insulator coating layer 166. An insulating outer insulating coating layer 168 made of FEP is formed around the third potential wiring 167 in the radial direction for protection. Thus, in this cable 160, the second potential wiring 161 and the auxiliary potential wiring 162 are surrounded by the first potential wiring 165 and the third potential wiring 167 through the inner insulator layer 164 and the insulator coating layer 166. It is a form that surrounds.
As described above, since the first conductive coating layer 166a and the third conductive coating layer 166b are integrally provided on the inner and outer surfaces 166U and 166S of the insulating coating layer 166 (insulating layer between 1-3), the cable 160 is provided. Even if it vibrates, friction does not occur between the insulator coating layer 166 and the first potential wiring 165 or the third potential wiring 167. For this reason, the insulator coating layer 166 is less likely to be charged with static electricity.

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 will be described below, in the present system 1, the third potential wiring 167 is connected to the ground input terminal 232 and the outer circuit case 260 of the signal current detection circuit 230 and is electrically connected to the ground potential wiring PVE. 167. Further, the ground potential PVE becomes the third potential that is the potential of the third potential wiring 167.

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 connected to and conductive with the second potential wiring 161 to be set to the second potential PV2. The auxiliary second output terminal 242 of the auxiliary electrode power circuit 240 is connected to and conductive with the auxiliary potential wiring 162 to be set to the auxiliary electrode potential PV3. Further, the first output terminal 211 of the ion source power circuit 210 is connected to 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 inner circuit case 250, and the first potential wiring 165. The connection and conduction are set to the first potential PV1. In addition, the ground input terminal 232 of the signal current detection circuit 230 is connected to and electrically connected to the outer circuit case 260 and the ground potential wiring 167 (third potential wiring) to be the ground potential PVE (third potential).
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 detection unit 10 will be described (see FIG. 2). 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 ejection source 11, a fine particle charging unit 12, a first conduction member 13, a needle electrode body 20, and an auxiliary electrode body 50 in terms of its electrical functions.

The extension portion 21 of the needle electrode body 20 is connected to the second potential wiring 161 of the cable 160. The needle-like electrode body 20 is made of a tungsten wire, and has a substantially straight rod-like extension portion 21 that is a second electrode conducting member (second potential member) and a tip portion of the extension portion 21 that is pointed like a needle. It has a needle-like tip 22 that forms the second discharge electrode of the ion gas injection source 11.
In addition, the extension portion 51 of the auxiliary electrode body 50 is connected to the auxiliary potential wiring 162 of the cable 160. This auxiliary electrode body 50 is made of a stainless steel wire, and has an approximately straight rod-like extension portion 51 and an auxiliary electrode portion 53 that is located at the tip end portion bent back in a U shape and forms an auxiliary electrode.

On the other hand, the first conduction member 13 that is a first potential member is connected to the first potential wiring 165 of the cable 160. The first conducting member 13 is made of metal and has a cylindrical shape, and is conducted to the first output terminal 211 of the ion source power supply circuit 210 through the first potential wiring 165 of the cable 160 and the inner circuit case 250, and the first potential PV1. It is said that.
Moreover, the 1st conduction | electrical_connection member 13 surrounds the radial direction periphery of the site | part located outside the exhaust pipe EP among the extension part 21 of the acicular electrode body 20, and the extension part 51 of the auxiliary electrode body 50. FIG.
Further, the compressed air AK is introduced into the first conducting member 13 through the gas flow passage 163H formed by the air pipe 163 of the cable 160. The compressed air AK is further pumped to the discharge space DS (described later) on the tip side (right side in FIG. 2).

  Further, the outer surrounding member 14 that is a ground potential member (third potential member) is connected to the ground potential wiring 167 (third potential wiring) of the cable 160. The outer surrounding member 14 is made of metal and has a cylindrical shape. The outer surrounding member 14 is located on the radially outer side of the first conducting member 13 and is attached to the exhaust pipe EP so as to conduct to the exhaust pipe EP. 3 potential).

Further, a nozzle portion 31 is fitted on the distal end side (right side in FIG. 2) of the first conducting member 13. 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.
The nozzle portion 31 is also electrically connected to the first conducting member 13 and is set to the first potential PV1.

As the nozzle portion 31 is fitted on the distal end side of the first conducting member 13, a discharge space DS is formed inside them. In this discharge space DS, a needle-like distal end portion 22 of the needle-like electrode body 20 protrudes, and this needle-like distal end portion 22 is a surface on the proximal end side of the nozzle portion 31 and a concave facing surface 31T. Facing each other. The discharge space DS is supplied with compressed air AK indicated by a white arrow through the ion source vent path RA. Accordingly, when a high voltage is applied between the needle-shaped tip 22 and the nozzle portion 31 (opposing surface 31T), an air discharge is generated, and N ₂ , O _{2 and the} like in the supplied compressed air AK are ionized, Positive ions (for example, N ³⁺ , O ^2+, hereinafter also referred to as ions CP) are generated. 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, the fine particle charging unit 12 is configured on the tip side (right side in FIG. 2) of the nozzle unit 31. An intake port 33I (opening toward the downstream side of the exhaust pipe EP) and a discharge port 43O are perforated on the side surface of the fine particle charging unit 12. Further, the fine particle charging unit 12 is electrically connected to the nozzle unit 31 and is set to the first potential PV1.

The fine particle charging unit 12 is configured such that the inner space is narrowed in a slit shape by the collecting electrode 42 bulging inward, and on the base end side (left side in FIG. 2) from this, A columnar space is formed between the nozzle portion 31 and the nozzle portion 31.
Of the spaces in the fine particle charging unit 12, the above-described cylindrical space is referred to as a cylindrical mixed region MX1. Moreover, let the slit-shaped internal space comprised by the collection electrode 42 be the slit-shaped mixing area MX2. Then, the cylindrical mixed region MX1 and the slit-shaped mixed region MX2 are collectively referred to as a mixed region MX. Further, a cylindrical space is formed on the tip side of the collecting electrode 42, and a discharge path EX communicating with the discharge port 43O is formed. In addition, a lead-in path HK that communicates from the inlet 33I to the mixing region MX (cylindrical mixing region MX1) is formed on the proximal end side of the collecting electrode 42.

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. 3 in addition to FIG. FIG. 3 schematically shows the electrical function and operation of the detection unit 10 of the system 1 for easy understanding.
The needle-like tip 22 of the needle-like electrode body 20 is connected to and connected to the second output end 212 of the ion source power supply circuit 210 through the second potential wiring 161 of the cable 160. Therefore, as described above, the needle-like tip portion 22 is set to the second potential PV2, which is a positive half-wave rectified pulse voltage of 100 kHz and 1-2 kV0-p with respect to the first potential PV1.
Further, the auxiliary electrode portion 53 of the auxiliary electrode body 50 is connected to and connected to the auxiliary second output terminal 242 of the auxiliary electrode power supply circuit 240 through the auxiliary potential wiring 162 of the cable 160. Therefore, as described above, the auxiliary electrode portion 53 is set to the auxiliary electrode potential PV3 that is a positive DC potential of 100 to 200 V with respect to the first potential PV1.
Further, the first conductive member 13, the nozzle unit 31, and the fine particle charging unit 12 are connected to the first output terminal 211 of the ion source power supply circuit 210 and the auxiliary first output of the auxiliary electrode power supply circuit 240 through the first potential wiring 165 of the cable 160. The 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 set to the first potential PV1.
In addition, the outer surrounding member 14 is connected and connected to the outer circuit case 260 surrounding the measurement control circuit 220 including the signal current detection circuit 230 and the ground input terminal 232 of the signal current detection circuit 230 through the ground potential wiring 167 of the cable 160. doing. 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 ejected toward the mixing region MX through the nozzle 31N together with the air AR originating from the compressed air AK 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 corresponds to the first discharge electrode. Further, the nozzle portion 31 (first discharge electrode) and the needle-like tip portion 22 (second discharge electrode) surrounding the discharge space DS serve as the ion source 11 and the ion gas injection source 11.

When the air AR is injected into the mixing region MX (columnar mixing region MX1) through the nozzle 31N of the nozzle portion 31, the pressure in the columnar mixing region MX1 decreases, so that the exhaust gas EG is drawn from the intake port 33I. Through HK, it is taken into the mixing area MX (columnar 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 have been taken in become ions positively charged fine particles SC to which the ions CP adhere, and in this state, the fine particles S pass through the mixing region MX and the discharge path EX and are removed from the discharge port 43O. It is discharged together with the intake / exhaust gas EGI and the air 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. 42 is attached to and captured by each part of the fine particle charging unit 12 that forms 42.

  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.

  The system 1 of the present embodiment is configured as described above, and uses a double surrounding cable 160 as the cable 160 that connects the detection unit 10 and the circuit unit 201. The double surrounding cable 160 doublely surrounds the second potential wiring 161 with the first potential wiring 165 and the ground potential wiring 167 which is the third potential wiring, and the first potential wiring 165 with the ground potential wiring 167. Besieged. And between the 1st electric potential wiring 165 and the ground electric potential wiring 167, the insulator coating layer 166 (insulator layer 1-3) which insulates both is arrange | positioned. Moreover, the radially inner surface 166U of the insulator coating layer 166 is covered with a conductive first conductive coating layer 166a integrated with the insulator coating layer 166, and the first potential wiring 165 is formed of the first potential wiring 165. 1 is in contact with the conductive coating layer 166a. In addition, the radially outer surface 166S of the insulator coating layer 166 is covered with a conductive third conductive coating layer 166b integrated with the insulator coating layer 166, and a ground potential wiring that is a third potential wiring. 167 is in contact with the third conductive coating layer 166b. Therefore, the insulator coating layer 166 is not in contact with the first potential wiring 165 or the ground potential wiring 167, and even if the cable 160 vibrates, the insulator coating layer 166 and the first potential wiring 165 or the ground potential wiring 167 There is no friction between the two. For this reason, the insulator coating layer 166 is hardly charged by static electricity. That is, in the present system 1, static electricity can be suppressed from being charged between the first potential wiring 165 and the ground potential wiring 167. Thus, the amount of fine particles S can be detected appropriately.

  Furthermore, in the system 1 of the present embodiment, the ground potential wiring 167 that is the third potential wiring is electrically connected to the outer surrounding member 14 (ground potential member) that is set to the ground potential PVE, and the first potential wiring 165 is The ion source 11 is electrically connected to the first discharge electrode (in the present embodiment, the nozzle portion 31) and the first conductive member 13 which is electrically connected to the fine particle charging portion 12. Then, the first potential wiring 165 having the first potential PV1 and the ground potential wiring 167 having the ground potential PVE are used to form the second discharge electrode (the needle-like tip 22 in the present embodiment) and the second electrode conducting member. (In the present embodiment, the second potential wiring 161 of the second potential PV2 that is electrically connected to the extending portion 21 of the needle electrode body 20 is electromagnetically shielded double. The first potential wiring 165 having the first potential PV1 is electromagnetically shielded by the ground potential wiring 167 having the ground potential PVE.

  The system 1 of the present embodiment includes the fine particle charging unit 12, and the amount of charge returned from here to the vent pipe EP as the charged fine particle SC corresponds to the amount of the fine particle S. Here, the signal current Is that flows between the first potential PV1 that is the potential of the fine particle charging unit 12 and the ground potential PVE that is conducted to the vent pipe EP is the amount of the charge that is returned from the fine particle charging unit 12 to the vent pipe EP. Corresponds to the quantity. In this system, the first potential wiring 165 is conducted to the fine particle charging unit 12, and the ground potential wiring 167, which is the third potential wiring, is conducted to the outer surrounding member 14 (ground potential member) that is set to the ground potential PVE. Yes. In addition, the first potential wiring 165 and the second potential wiring 161 are electrically connected to the first discharge electrode (nozzle portion 31) and the second discharge electrode (needle tip portion 22) of the ion source 11, respectively, and a discharge is generated therebetween. Current flows.

  For this reason, the first potential wiring 165, the second potential wiring 161, and the ground potential wiring 167 have the double shield structure as described above and are electromagnetically shielded from each other. It is less susceptible to the effects of current and external electromagnetic noise. Furthermore, as described above, since the influence of static electricity can be suppressed, the amount of fine particles S can be detected appropriately.

  Furthermore, when the system 1 of this embodiment is mounted on a vehicle, the cable 160 is likely to vibrate as the vehicle is driven, so that friction is likely to occur in the cable. On the other hand, the cable 160 used in the system 1 of the present embodiment has a double-enclosed cable structure, and the inner and outer surfaces 166U and 166S of the insulator covering layer 166 (insulator layer 1-3) are electrically conductive first conductive. Since the covering layer 166a and the third conductive covering layer 166b cover, even if the vibration due to driving of the vehicle is applied to the cable 160, static electricity due to friction is hardly generated in the insulating covering layer 166. For this reason, the amount of fine particles S can be detected appropriately.

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 above-described embodiment, in the cable 160, the first potential wiring 165 and the ground potential wiring 167 (third potential wiring) both show an example using a braided copper thin wire, but aluminum, copper, etc. These metal tapes (band metal foils) may be wound around the inner insulating coating layer 164d or the insulating coating layer 166 (insulator layer 1-3) in a spiral manner to constitute these. Alternatively, the metal tape may be wound around the braid and covered with a braid. Metal pipes such as copper pipes and aluminum pipes can be used in whole or in part.

EP Exhaust pipe EG Exhaust gas EGI Intake exhaust gas S Fine particles SC Charged fine particles CP Ion CPF Floating ions CPH Discharged ions Is Signal current 1 Fine particle detection system 10 Detection unit 11 Ion gas injection source (ion source)
12 Particulate Charger 13 First Conductive Member (First Potential Member)
14 Outer enclosure member (ground potential member, third potential member)
20 Needle-shaped electrode body 21 (of the needle-shaped electrode body) Extension part (second electrode conducting member, second potential member)
22 Needle-shaped tip (of the needle-shaped electrode body) (ion source, second discharge electrode)
31 Nozzle part (ion source, first discharge electrode, fine particle charging part)
PV1 First potential PV2 Second potential PV3 Auxiliary electrode potential PVE Ground potential (third potential)
42 Collection Electrode 50 Auxiliary Electrode 51 (Auxiliary Electrode) Extension 53 (Auxiliary Electrode) Auxiliary Electrode 160 Cable (Double Enclosed Cable)
161 Second potential wiring 164 Inner insulator layer (insulator layer between 2-1)
165 First potential wiring 166 Insulator coating layer (insulator layer between 1-3)
166a First conductive coating layer 166b Third conductive coating layer 166U (Insulator coating layer (insulator layer 1-3)) radially inner surface 166S (Insulator coating layer (between 1-3 insulator layers)) Radial outer surface 167 Ground potential wiring (third potential wiring)
168 Outer insulation coating layer AK Compressed air 201 Circuit part 210 Ion source power supply circuit 220 Measurement control circuit 230 Signal current detection circuit 240 Auxiliary electrode power supply circuit

Claims (3)

A fine particle detection system for detecting the amount of fine particles in a gas to be measured flowing in a vent pipe,
A detector attached to the vent pipe;
A drive detection circuit that drives the detection unit to detect the amount of the fine particles;
A cable composed of a plurality of wiring members that electrically connect between the detection unit and the drive detection circuit;
The detector is
A first potential member to be a first potential;
A second potential member having a second potential different from the first potential; and
A third potential member having a third potential different from the first potential and the second potential,
The above cable
A second potential wiring conducting to the second potential member;
A first potential wiring that is electrically connected to the first potential member, surrounds the periphery of the second potential wiring in the radial direction, and includes at least one of a braided and a spirally wound metal foil;
A 2-1 insulator layer surrounding the second potential wiring in the radial direction and disposed between the second potential wiring and the first potential wiring to insulate them;
A third potential wiring that is electrically connected to the third potential member, surrounds the periphery of the first potential wiring in the radial direction, and includes at least one of a braided and a spirally wound metal foil;
An insulative 1-3 insulator layer that surrounds the radial periphery of the first potential wiring and is disposed between the first potential wiring and the third potential wiring to insulate them;
A conductive first conductive coating layer that is integral with the 1-3 insulator layer and covers the radially inner surface thereof, and is in contact with the first potential wiring; and
A conductive third conductive coating layer that is integral with the 1-3 insulator layer and covers a radially outer surface thereof and is in contact with the third potential wiring;
The first potential wiring and the third potential wiring doubly surround the second potential wiring, and surround the first potential wiring by the third potential wiring. . The particulate detection system according to claim 1,
The detector is
An ion source including a first discharge electrode and a second discharge electrode and generating ions by air discharge between them;
A part of the gas to be measured, which is conducted to the first discharge electrode of the ion source and circulates in the ventilation tube, is mixed with the ions generated by the ion source, and is contained in the part of the gas to be measured. The fine particle charging unit configured to return the fine particles to the inside of the vent pipe as charged fine particles to which the ions are attached, and serves as a collecting electrode for collecting floating ions that are not attached to the fine particles among the ions.
A first conducting member that is the first potential member that is conducted to the first discharge electrode and the fine particle charging unit and is set to the first potential;
A second electrode conducting member which is the second potential member that is conducted to the second discharge electrode and is set to the second potential; and
A ground potential member that is electrically connected to the vent pipe, is the third potential member, and is a ground potential that is the third potential;
The cable is
The second potential wiring that conducts to the second electrode conducting member by the first potential wiring that conducts to the first conducting member and the third potential wiring that conducts to the ground potential member. A fine particle detection system in which the first potential wiring is electromagnetically shielded by the ground potential wiring. The fine particle detection system according to claim 1 or 2,
The vent pipe is an exhaust pipe of an on-board internal combustion engine,
The particulate matter detection system, wherein the gas to be measured is an exhaust gas flowing through the exhaust pipe.

Images