JP6728076B2 - Particle sensor - Google Patents

Description

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

Sometimes you want to measure the amount of particles in the gas. For example, an internal combustion engine (for example, a diesel engine or a gasoline engine) may contain fine particles such as soot in its exhaust gas. The exhaust gas containing such fine particles is collected and purified by a filter. However, when a problem such as breakage of the filter occurs, the unpurified exhaust gas is directly discharged to the downstream side of the filter. Therefore, in order to directly measure the amount of fine particles in the exhaust gas and to detect a malfunction of the filter, there is a demand for a fine particle sensor capable of detecting the amount of fine particles in the exhaust gas downstream of the filter.

As such a particle sensor, in Patent Document 1, a sensor main body that is attached to a ventilation pipe to detect the amount of fine particles in a gas to be measured flowing through the ventilation pipe, and a circuit unit that drives the sensor main body are disclosed. There is disclosed a particle sensor including a cable that electrically connects the sensor and a sensor body.

JP2012-194077A

In the particle sensor of Patent Document 1, the sensor main body includes a reference potential member (casing) having a reference potential (sensor GND potential), a discharge electrode body (second electrode) having a discharge potential different from the reference potential, And an auxiliary electrode body (first electrode) having an auxiliary potential different from the reference potential and the discharge potential. In addition, a cable has a discharge potential wiring that conducts to the discharge electrode body, an auxiliary potential wiring that conducts to the auxiliary electrode body, and a cylindrical reference potential that surrounds the discharge potential wiring and the radial periphery of the auxiliary potential line. It has wiring (braid). Further, inside the sensor body, there are a discharge potential connecting portion in which the discharge potential wiring and the discharge electrode body are connected, and an auxiliary potential connecting portion in which the auxiliary potential wiring and the auxiliary electrode body are connected. It is arranged.

By the way, in the fine particle sensor of Patent Document 1, in order to generate an air discharge (corona discharge) in the discharge electrode body, a high discharge potential (for example, 1 to 2 kV) is applied to the discharge electrode body. .. Therefore, the discharge potential connecting portion also has a high potential (1 to 2 kV) equivalent to that of the discharge electrode body. On the other hand, the auxiliary potential applied to the auxiliary electrode body is a potential (eg, 100 to 200 V) that is extremely lower than the discharge potential. Therefore, the auxiliary potential connection has a potential (eg, 100 to 200 V) that is extremely lower than the discharge potential connection.

However, in the particle sensor of Patent Document 1, the discharge potential connecting portion and the auxiliary potential connecting portion are arranged close to each other inside the sensor main body. For this reason, there is a possibility that discharge or the like may occur between the discharge potential connection portion and the auxiliary potential connection portion, and it may not be possible to properly detect the amount of fine particles in the measurement gas that flows in the ventilation pipe.

The present invention has been made in view of the above problems, and provides a fine particle sensor in which a discharge potential connection portion and an auxiliary potential connection portion are appropriately electrically insulated.

One aspect of the present invention is configured to extend in the axial direction, and is mounted on a ventilation pipe to drive a sensor main body that detects the amount of fine particles in a gas to be measured flowing in the ventilation pipe, and the sensor main body. A fine particle sensor, comprising: a first cable and a second cable electrically connecting a circuit section and the sensor body section, wherein the sensor body section is a reference potential member serving as a reference potential; A discharge electrode body having a discharge potential different from a reference potential, and an auxiliary electrode body having an auxiliary potential different from the reference potential and the discharge potential, wherein the first cable is connected to the discharge electrode body. A discharge-potential wiring that conducts, and a cylindrical first reference-potential wiring that conducts to the reference-potential member and surrounds the circumference of the discharge-potential wiring in the radial direction, wherein the second cable is the auxiliary electrode body. An auxiliary potential wiring that is electrically connected to the reference potential member, and a cylindrical second reference potential wiring that is electrically connected to the reference potential member and surrounds the circumference of the auxiliary potential wiring in the radial direction. And a separator having a first through hole and a second through hole that penetrate the separator in the axial direction, wherein the particulate sensor is the discharge potential wiring of the first cable. And a discharge potential connecting portion to which the discharge electrode body is connected, and an auxiliary potential connecting portion to which the auxiliary potential wiring of the second cable and the auxiliary electrode body are connected, the discharge potential connecting portion Is disposed in the first through hole of the separator, and the auxiliary potential connecting portion is disposed in the second through hole of the separator, thereby the discharge potential connecting portion and the auxiliary potential connecting portion. Is electrically insulated by the separator, and the reference potential member is a tubular member having a tubular shape extending in the axial direction by combining a semi-cylindrical first member and a semi-cylindrical second member. And including a tubular member fixed inside the sensor body, wherein the tubular member is a combination of the first member and the second member in a manner of covering the outer periphery of the separator, The fine particle sensor holds the separator and is in contact with and electrically connected to the first reference potential wiring and the second reference potential wiring.

The above-described particle sensor is a sensor main body that extends in the axial direction, and includes a sensor main body that is attached to the ventilation pipe and detects the amount of particles in the gas to be measured flowing in the ventilation pipe. Furthermore, the above-described particle sensor includes a first cable and a second cable as cables that electrically connect the circuit body that drives the sensor body and the sensor body.

Further, in the above-described particle sensor, the sensor main body portion has a columnar separator extending in the axial direction. This separator has a first through hole and a second through hole that penetrate the separator in the axial direction. The first through hole and the second through hole are separate and independent through holes, and are two through holes that are separated in the direction orthogonal to the axial direction with the wall portion of the separator interposed therebetween.

Further, in the above-mentioned particle sensor, the discharge potential connecting portion is arranged in the first through hole of the separator, and the auxiliary potential connecting portion is arranged in the second through hole of the separator, thereby forming the discharge potential connecting portion. The auxiliary potential connection portion is electrically insulated by the separator. Here, the discharge potential connecting portion is a portion where the discharge potential wiring of the first cable and the discharge electrode body are connected. The auxiliary potential connecting portion is a portion where the auxiliary potential wiring of the second cable and the auxiliary electrode body are connected.

Therefore, the above-described particle sensor is a particle sensor in which the discharge potential connecting portion and the auxiliary potential connecting portion are properly electrically insulated by the separator.

Furthermore, in the above-mentioned particle sensor, the reference potential member includes a tubular member in which a semi-cylindrical first member and a semi-cylindrical second member are combined. The tubular member has a tubular shape extending in the axial direction and is fixed inside the sensor body.
Further, the tubular member holds the separator by combining the first member and the second member in such a manner as to cover (enclose) the outer periphery of the separator, and at the same time, the first reference potential wiring and the second reference potential wiring. It comes into contact with and conducts electricity.

In this way, the separator is held in such a manner that the outer periphery of the separator is covered (enclosed) by the tubular member fixed inside the sensor main body, so that the separator also passes through the tubular member. It will be fixed inside the section. Thereby, "the discharge potential connecting portion is arranged in the first through hole of the separator, and the auxiliary potential connecting portion is arranged in the second through hole of the separator, so that the discharge potential connecting portion and the auxiliary potential connecting portion are arranged. It is possible to stably maintain the “state where and are electrically insulated by the separator”.

Moreover, by combining the first member and the second member so as to cover the outer periphery of the separator to form the tubular member, not only the tubular member holds the separator, but also the tubular member The reference potential wiring and the second reference potential wiring can be brought into contact with each other to make them conductive. Accordingly, the first reference potential wiring and the second reference potential wiring can be easily and appropriately electrically connected to the reference potential member including the tubular member.

The first member and the second member that form the tubular member are, for example, a semi-cylindrical shape obtained by dividing the tubular member into two parts in the axial direction, and the first member and the second member are provided so as to cover the outer periphery of the separator. An example is one in which the inner peripheral surfaces of the first member and the second member are in contact with the outer peripheral surface of the separator when the tubular member is formed by combining the members. By using the first member and the second member having such a shape to form a tubular member by combining the first member and the second member in a manner of covering the outer periphery of the separator, the tubular member (first The member and the second member) can sandwich and hold the separator radially inward.

Furthermore, in the above-mentioned particle sensor, the sensor main body portion has a tubular holding member, and the tubular member has one end portion thereof inserted and fixed inside the holding member, It is preferable that the particle sensor is held by the holding member.

In the above-mentioned particle sensor, the tubular member in which the first member and the second member are combined has one end portion (one end portion of the first member and one end portion of the second member) inserted inside the tubular holding member. It is held by the holding member in a fixed state. As a result, the state in which the first member and the second member are combined to form a tubular member can be maintained.

Further, in any one of the fine particle sensors, the separator has a groove forming surface that forms a groove portion extending in the axial direction on an outer peripheral surface thereof, and the outer periphery of the separator is covered by the tubular member. In this state, a ventilation hole surrounded by the groove forming surface and the inner peripheral surface of the tubular member is formed, and the sensor main body is provided at the rear end in the axial direction with the outside of the sensor main body. From the inside of the sensor main body to have an air intake portion for taking in air, the air taken into the inside of the sensor main body through the air intake portion, through the ventilation hole, the inside of the sensor main body It is preferable to use a particle sensor having a form introduced on the tip side in the axial direction.

In the above-mentioned particle sensor, the separator has a groove forming surface which forms a groove extending in the axial direction on the outer peripheral surface thereof. Further, in a state where the outer periphery of the separator is covered with the tubular member, a ventilation hole surrounded by the groove forming surface of the separator and the inner peripheral surface of the tubular member is formed.

Further, in the above-described particle sensor, the air intake portion for taking in air from the outside of the sensor main body to the inside of the sensor main body is provided at the rear end of the sensor main body in the axial direction. Further, the sensor main body has a form in which air taken into the sensor main body through the air intake portion is introduced to the axial tip end side in the sensor main body through the ventilation hole.
Therefore, in the above-described particle sensor, the air taken into the sensor main body through the air intake can be appropriately introduced into the sensor main body at the tip end side in the axial direction through the ventilation hole.

As the groove portion of the separator, for example, a groove portion that extends from the front end to the rear end of the separator in the axial direction in a form in which a part of the outer peripheral surface of the cylindrical separator is recessed inward in the radial direction can be given. The groove is not limited to one, but a plurality of grooves may be provided. When a separator having a plurality of grooves is used, a plurality of vent holes can be formed.

Further, in any one of the fine particle sensors, the reference potential member includes a discharge counter electrode portion serving as a counter electrode of the discharge electrode body, and the fine particle sensor is provided between the discharge electrode body and the discharge counter electrode portion. An air discharge is generated, and the ions generated by the air discharge are attached to the fine particles contained in the gas to be measured to generate charged charged fine particles, and the measured object is measured based on the charge amount of the charged fine particles. A fine particle sensor that detects the amount of the fine particles in the gas may be used.

In the above-described particle sensor, the reference potential member includes the discharge counter electrode portion that is the counter electrode of the discharge electrode body. This fine particle sensor generates an air discharge between a discharge electrode body (discharge potential) and a discharge counter electrode part (reference potential), and causes ions generated by the air discharge to adhere to fine particles contained in a gas to be measured. Then, the charged fine particles are generated, and the amount of the fine particles in the gas to be measured is detected based on the charge amount of the charged fine particles.

On the other hand, the above-mentioned particulate sensor is a particulate sensor in which the discharge potential connecting portion and the auxiliary potential connecting portion are appropriately electrically insulated by the separator as described above. Therefore, in the above-mentioned particle sensor, there is no fear that discharge or the like will occur between the discharge potential connection portion and the auxiliary potential connection portion, and the discharge electrode body (discharge potential) and the discharge counter electrode portion (reference potential) will be generated. The air discharge can be appropriately generated. This makes it possible to properly detect the amount of fine particles in the gas to be measured.

It is a schematic diagram showing the state where the particulate sensor concerning an embodiment was attached to the exhaust pipe of the engine carried in vehicles. It is a perspective view of a particle sensor concerning an embodiment. It is a longitudinal cross-sectional view of the same particle sensor. FIG. 4 is another vertical cross-sectional view of the particle sensor, which is a vertical cross-sectional view in a direction orthogonal to FIG. 3. It is a longitudinal cross-sectional view of the state where the sensor main body of the particle sensor is attached to an exhaust pipe. FIG. 3 is an exploded perspective view of the particle sensor according to the embodiment. It is a cross-sectional view of a first cable and a second cable. 1 is a diagram showing a schematic configuration of a particle detection system according to an embodiment. It is a top view of the 1st member and the 2nd member which constitute an inner pipe (cylindrical member). It is a front view of the 1st member and the 2nd member. It is a top view of a separator. FIG. 12 is a vertical sectional view of the separator, which corresponds to the CC sectional view of FIG. 11. FIG. 4 is an explanatory diagram schematically showing how fine particles are taken in, charged, and discharged by a fine particle sensor. It is a longitudinal cross-sectional view of a particle sensor according to a modification. It is an exploded perspective view of the same particle sensor.

(Embodiment)
Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing a state in which the particle sensor 1 according to the embodiment is mounted on an exhaust pipe EP of an engine ENG (internal combustion engine) mounted on a vehicle AM. FIG. 2 is a perspective view of the particle sensor 1. FIG. 3 is a vertical sectional view of the particle sensor 1. FIG. 4 is another vertical cross-sectional view of the particle sensor 1, which is a vertical cross-sectional view in a direction orthogonal to FIG. FIG. 5 is a vertical cross-sectional view of the state where the sensor body 5 is attached to the exhaust pipe EP. FIG. 6 is an exploded perspective view of the particle sensor 1.
In the axial direction GH (the direction along the axis AX, the vertical direction in FIG. 3) of the particle sensor 1, the side (upper side in FIG. 3) attached to the exhaust pipe EP (vent pipe) is the tip side GS, and the exhaust pipe. The side disposed outside the EP (downward in FIG. 3) is the rear end side GK.

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

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

Here, the particle sensor 1 of the present embodiment will be described in detail. The particle sensor 1 extends from the sensor main body 5, a cable (first cable 90 and second cable 100) that electrically connects the sensor main body 5 and the circuit 201, and extends from the sensor main body 5. And an air tube 50 (see FIGS. 2 and 3). Among these, the sensor main body portion 5 has a sensor main body front end portion 6 and a sensor main body rear end portion 7 located on the rear end side GK. The sensor body front end portion 6 is attached to a pipe mounting portion EPT of a metal exhaust pipe EP having a ground potential PVE, and the sensor body rear end portion 7 is arranged outside the exhaust pipe EP (FIGS. 5 and 8). reference).

Further, the air tube 50 extending from the sensor body 5 is connected to the external pressure feed pump 330 (see FIG. 8). The first cable 90 and the second cable 100 extending from the sensor body 5 are connected to the external circuit unit 201 (see FIG. 8).

The sensor body 5 has an outer metal member 10, an inner metal member 30, a discharge electrode body 70, and an auxiliary electrode body 80 (see FIG. 3 ). Among these, the outer metal fitting 10 has a cylindrical shape extending in the axial direction GH, and surrounds the inner circumference of the inner metal fitting 30 in the radial direction in a state of being insulated from the inner metal fitting 30. The outer metal fitting 10 is attached to the pipe mounting portion EPT of the exhaust pipe EP having the ground potential PVE to have the ground potential PVE (see FIGS. 5 and 8). The outer metal fitting 10 includes an outer first metal fitting 11, an outer second metal fitting 13 that comes into contact with the outer first metal fitting 11 from the tip side GS, and a rear cover 15 welded to the outer first metal fitting 11 from the rear end side GK. Composed.

As shown in FIG. 6, the outer first metal member 11 is a cylindrical member made of stainless steel. The outer first metal fitting 11 includes a cylindrical first main body portion 11a, an annular outer holding portion 11b located on the tip side GS of the first main body portion 11a, and a radial outer side from the outer holding portion 11b. It is composed of a bulging annular metal fitting mounting portion 11c (see FIG. 4). In the sensor body 5 of the particle sensor 1, the portion from the metal fitting mounting portion 11c of the outer first metal fitting 11 to the tip side GS (the tip side GS including the metal fitting mounting portion 11c) is the above-mentioned sensor body tip portion. 6, the portion of the outer first metal fitting 11 from the first main body portion 11a to the rear end side GK (the portion of the rear end side GK including the first main body portion 11a) is the sensor main body rear end portion 7.

A fastening member 60, which will be described later, is rotatably arranged around the first main body portion 11 a with respect to the outer first metal fitting 11. The outer holding portion 11b is a portion that holds the cylindrical insulating spacer 47 made of alumina between the outer holding portion 11b and an inner holding portion 33b of the inner metal fitting 30, which will be described later. It is engaged with the insulating spacer 47 from the front end side GS over the entire circumference. On the other hand, the metal fitting mounting portion 11c is a portion that is engaged with the fastening member 60 and is mounted on the pipe mounting portion EPT of the exhaust pipe EP, as described later. A radially outer portion of the metal fitting mounting portion 11c is a first engaging portion 11cf that is recessed in the rear end side GK and has a reduced thickness in the axial direction GH. A second engaging portion 13bf of an outer second metal fitting 13 described later is engaged with the first engaging portion 11cf over the entire circumference.

As shown in FIG. 6, the outer second metal piece 13 is a cylindrical member made of stainless steel. The second outer metal fitting 13 extends from the outer first metal fitting 11 to the tip side GS and is arranged radially outside of the inner metal fitting 30 described later with a gap. Since the outer second metal fitting 13 is not joined to the outer first metal fitting 11 by welding or the like and only contacts the outer first metal fitting 11, it can be removed from the outer first metal fitting 11. The outer second metal member 13 includes a cylindrical second main body portion 13a and an annular plate-shaped sensor seat surface portion 13b that bulges radially outward from the rear end of the second main body portion 13a. The second main body 13a is provided with a gas introduction window 13h formed of a U-shaped cutout in plan view, which is open to the tip side GS of the second main body 13a.

The sensor seat surface portion 13b is a portion that is attached to the pipe mounting portion EPT of the exhaust pipe EP together with the metal fitting mounting portion 11c of the outer first metal fitting 11 described above. As will be described later, the sensor seat surface portion 13b indirectly contacts the pipe seat surface portion EPZ of the pipe mounting portion EPT at the distal end side GS via a ring-shaped copper gasket 18. On the other hand, the outer first metal fitting 11 is in contact with the sensor seat surface portion 13b from the rear end side GK. Further, the radially outer portion of the sensor seat surface portion 13b is a second engagement portion 13bf protruding toward the rear end side GK. As described above, the second engaging portion 13bf engages with the first engaging portion 11cf of the outer first metal fitting 11 over the entire circumference.

As shown in FIG. 6, the rear cover 15 is a cylindrical member made of stainless steel, and has a first through hole 15b and a second through hole 15c extending in the axial direction GH (see FIG. 3). A front end portion of the rear cover 15 is inserted into the first main body portion 11a of the outer first metal fitting 11 from the rear end side GK and welded over the entire circumference. The rear cover 15 is provided with a cylindrical air intake portion 15t protruding toward the rear end side GK. An air tube 50 is connected to the air intake portion 15t, and is swaged and fixed by a cylindrical mounting ring 16. The air tube 50 extends from the air intake portion 15t toward the rear end side GK, and the other end portion of the air tube 50 is connected to a pressure pump 330 installed outside (see FIG. 8). As a result, clean air (compressed air) AR generated by the pressure pump 330 is supplied into the rear cover 15 (in the sensor body 5) via the air tube 50.

Further, two cables (the first cable 90 and the second cable 100) extend from the inside of the rear cover 15 toward the rear end side GK. Specifically, as shown in FIG. 3, the first O-ring 23 and the cylindrical first retainer 25 are inserted in the rear end side GK of the first through hole 15b of the rear cover 15, and the first O-ring 23 and the cylindrical first retainer 25 are inserted into these. The first cable 90 is held by the rear cover 15 with the cable 90 inserted therethrough. Further, the second O-ring 24 and the cylindrical second retainer 26 are inserted into the rear end side GK of the second through hole 15c of the rear cover 15, and the second cable 100 is inserted through the second O-ring 24 and the cylindrical second retainer 26. The two cables 100 are held by the rear cover 15.

Next, the first cable 90 and the second cable 100 will be described. Note that FIG. 7 is a cross-sectional view of the first cable 90 and the second cable 100.
The first cable 90 is a triaxial cable, and as shown in FIGS. 3 and 7, a discharge potential wiring 91 made of a copper core wire and a cylinder made of a braid of copper thin wires, which is located outside in the radial direction thereof. The first reference potential wiring 93 and the discharge potential wiring 91, which surround the radial direction and are arranged between the discharge potential wiring 91 and the first reference potential wiring 93 to insulate the two, and are made of PTFE. And an insulator layer 92. Further, the first cable 90 surrounds the circumference of the first reference potential wiring 93 in the radial direction, and has a cylindrical first ground potential wiring 97 made of a braided thin copper wire, and a radial direction of the first reference potential wiring 93. It has an insulating second insulator layer 95 made of PTFE, which surrounds the periphery and is arranged between the first reference potential wiring 93 and the first ground potential wiring 97 and insulates them.

Further, as shown in FIG. 7, the first cable 90 is in close contact with the radially inner surface 95 b of the second insulator layer 95, covers the radially inner surface 95 b, and contacts the first reference potential wiring 93. It has a semi-conductive coating layer 94 and a second semi-conductive coating layer 96 that is in close contact with the radially outer surface 95c of the second insulator layer 95, covers the radially outer surface 95c, and contacts the first ground potential wiring 97. .. The first semiconductive coating layer 94 and the second semiconductive coating layer 96 are made of FEP containing carbon and have semiconductivity (conductivity). Further, the first cable 90 has an insulating outer insulating coating layer 98 made of FEP, which covers the radial circumference of the first ground potential wiring 97. In this way, the first cable 90 double-encloses the discharge potential wiring 91 by the first reference potential wiring 93 and the first ground potential wiring 97, and the first reference potential wiring 93 is surrounded by the first ground potential wiring 97. It is a double-enclosed cable that surrounds the.

In the first cable 90, the tip portion 91b of the discharge potential wiring 91 extends to the tip side (upper side in FIG. 3) of the first cable 90 than the tip of the first insulator layer 92, and the first cable 90 is formed. Exposed to the outside. As shown in FIG. 3, the tip portion 91b of the discharge potential wiring 91 is connected to the rear end portion (exposed portion) of the first extension portion 71 of the discharge electrode body 70 by caulking connection by the first connection terminal 77. Has been done. As a result, the discharge potential wiring 91 is electrically connected to the discharge electrode body 70.

It should be noted that the portion where the tip end portion 91b of the discharge potential wiring 91 and the rear end portion (exposed portion) of the first extension portion 71 of the discharge electrode body 70 are connected via the first connection terminal 77 is the discharge potential connection portion 111. (See FIG. 3). The discharge potential connection portion 111 is configured by the tip end portion 91 b of the discharge potential wiring 91, the rear end portion (exposed portion) of the first extension portion 71 of the discharge electrode body 70, and the first connection terminal 77.

Further, the tip portion 93b of the first reference potential wiring 93 is exposed to the outside of the first cable 90 so as to extend toward the tip side of the first cable 90 from the tip of the first semiconductive coating layer 94. The tip portion 93b of the first reference potential wiring 93 is connected to the inner cylinder 31 of the inner metal fitting 30 (reference potential member) as shown in FIG. As a result, the first reference potential wiring 93 is electrically connected to the inner fitting 30 (reference potential member).

Further, the tip portion 97b of the first ground potential wiring 97 is exposed to the outside of the first cable 90 in a form extending toward the tip side of the first cable 90 with respect to the tip of the outer insulating coating layer 98. As shown in FIG. 3, a cylindrical first metal member 21 inserted into the first through hole 15b of the rear cover 15 is externally fitted to the tip end portion 97b of the first ground potential wiring 97, and the first metal It is connected to the rear cover 15 (ground potential member) through the member 21. As a result, the first ground potential wiring 97 is electrically connected to the outer metal fitting 10 (ground potential member).

Next, the second cable 100 will be described. This second cable 100 is also a triaxial cable, and as shown in FIGS. 3 and 7, is composed of an auxiliary potential wiring 101 made of a copper core wire and a braid laid on the outer side in the radial direction and woven with a copper thin wire. A cylindrical second reference potential wiring 103 and the auxiliary potential wiring 101 are surrounded by the radial direction and are arranged between the auxiliary potential wiring 101 and the second reference potential wiring 103 to insulate them from each other and are made of PTFE. 1 insulator layer 102. Further, the second cable 100 surrounds the second reference potential wiring 103 in the radial direction and has a cylindrical second ground potential wiring 107 made of a braided copper thin wire and a radial direction of the second reference potential wiring 103. It has an insulating second insulator layer 105 made of PTFE, which surrounds the periphery and is arranged between the second reference potential wiring 103 and the second ground potential wiring 107 to insulate the two.

Further, as shown in FIG. 7, the second cable 100 adheres closely to the radially inner surface 105 b of the second insulator layer 105, covers the radially inner surface 105 b, and contacts the second reference potential wiring 103. It has a semiconductive coating layer 104 and a second semiconductive coating layer 106 that is in close contact with the radially outer surface 105c of the second insulator layer 105, covers the radially outer surface 105c, and contacts the second ground potential wiring 107. .. The first semiconductive coating layer 104 and the second semiconductive coating layer 106 are made of carbon-containing FEP and have semiconductivity (conductivity). Further, the second cable 100 has an insulating outer insulating coating layer 108 made of FEP, which covers the circumference of the second ground potential wiring 107 in the radial direction. Thus, in the second cable 100, the auxiliary potential wiring 101 is doubly surrounded by the second reference potential wiring 103 and the second ground potential wiring 107, and the second reference potential wiring 103 is surrounded by the second ground potential wiring 107. It is a double-enclosed cable that surrounds the.

In the second cable 100, the tip portion 101b of the auxiliary potential wiring 101 extends in the tip side (upper side in FIG. 3) of the second cable 100 than the tip of the first insulator layer 102, and the second cable 100 is formed. Exposed to the outside. As shown in FIG. 3, the tip portion 101b of the auxiliary potential wiring 101 is connected to the rear end portion (exposed portion) of the second extension portion 81 of the auxiliary electrode body 80 by caulking connection by the second connection terminal 87. Has been done. As a result, the auxiliary potential wiring 101 is electrically connected to the auxiliary electrode body 80.

It should be noted that the portion where the tip end portion 101 b of the auxiliary potential wiring 101 and the rear end portion (exposed portion) of the second extension portion 81 of the auxiliary electrode body 80 are connected via the second connection terminal 87 is the auxiliary potential connection portion 112. (See FIG. 3). The auxiliary potential connection portion 112 is configured by the tip end portion 101b of the auxiliary potential wiring 101, the rear end portion of the second extension portion 81 of the auxiliary electrode body 80, and the second connection terminal 87.

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

Further, the tip portion 107b of the second ground potential wiring 107 is exposed to the outside of the second cable 100 so as to extend to the tip side of the second cable 100 with respect to the tip of the outer insulating coating layer 108. As shown in FIG. 3, a cylindrical second metal member 22 inserted into the second through hole 15c of the rear cover 15 is externally fitted to the tip portion 107b of the second ground potential wiring 107, and the second metal It is connected to the rear cover 15 (ground potential member) through the member 22. As a result, the second ground potential wiring 107 is electrically connected to the outer metal fitting 10 (ground potential member).

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

As shown in FIG. 5, the pipe mounting portion EPT of the exhaust pipe EP has an annular pipe seat surface portion EPZ, and extends from the pipe seat surface portion EPZ to the outside in the radial direction of the exhaust pipe EP, and a female screw is formed on the inner periphery thereof. And a cylindrical female screw portion EPY formed therein. When the sensor body 5 of the particle sensor 1 is mounted on the pipe mounting portion EPT of the exhaust pipe EP, the male screw portion 61 of the fastening member 60 is screwed into the female screw portion EPY of the pipe mounting portion EPT. The tip of the portion 61 engages with the metal fitting mounting portion 11c of the outer first metal fitting 11 of the sensor body leading end 6, and the sensor body 5 including the outer first metal fitting 11 moves to the tip side GS.

Then, the sensor seat surface portion 13b of the outer second metal fitting 13 arranged on the tip side GS of the metal fitting mounting portion 11c indirectly contacts the pipe seat surface portion EPZ of the pipe mounting portion EPT via the gasket 18. The metal fitting mounting portion 11c and the sensor seating surface portion 13b are sandwiched between the male screw portion 61 of the fastening member 60 and the pipe seat surface portion EPZ of the pipe mounting portion EPT, and the pipe mounting portion EPT is provided with the outer first metal fitting 11 and the outer first fitting 11. The two metal fittings 13 are held, and the sensor main body portion 5 is airtightly fixed to the pipe mounting portion EPT. Since the fastening member 60 is rotatably arranged with respect to the sensor main body 5, the sensor main body 5 is fastened to the pipe mounting portion EPT without rotating the sensor main body 5. This can be done by rotating only the member 60.

Next, the inner fitting 30 will be described. As shown in FIGS. 3 and 4, the inner metal member 30 has a cylindrical outer shape extending in the axial direction GH, and is separated from the outer metal member 10 and insulated from the outer metal member 10 in the radial direction as described above. It is arranged in a closed state. The inner fitting 30 is connected to the external circuit portion 201 through the first reference potential wiring 93 of the first cable 90 and the second reference potential wiring 103 of the second cable 100, and has a reference potential PV1 different from the ground potential PVE. It The inner metal member 30 is composed of an inner cylinder 31, a pipe holder 33, a nozzle member 35, a mixing and discharging member 37, and a lid member 39, which are arranged in order from the rear end side GK to the front end side GS (FIG. 3, FIG. 4 and FIG. 6).
In the present embodiment, the inner fitting 30 corresponds to the reference potential member. The inner cylinder 31 corresponds to a tubular member.

The pipe holder 33 is a member having a cylindrical outer shape and made of stainless steel, and is fitted and fixed in the front end portion of the inner cylinder 31 at the rear end side GK. The pipe holder 33 has an inner holding portion 33b that holds the insulating spacer 47 between the pipe holder 33 and the outer holding portion 11b of the outer metal fitting 10, and the inner holding portion 33b is insulated via the annular second plate packing 49. The spacer 47 is engaged over the entire circumference from the rear end side GK (see FIGS. 3 and 4).

The nozzle member 35 is a member having a cylindrical outer shape and made of stainless steel, and the tip end portion of the pipe holder 33 is fitted from the rear end side GK and is fixed thereto. The nozzle member 35 has a nozzle portion 35a in which a center is formed in a concave shape toward the tip side GS and a fine through hole is formed in the center. Further, the nozzle member 35 has a cylindrical distal end side cylindrical wall portion 35b extending from the peripheral edge of the nozzle portion 35a to the distal end side GS. A cylindrical mixing region MX1 that is a cylindrical space is formed in the tip-side cylindrical wall portion 35b. Further, the front end side cylinder wall portion 35b is provided with one gas intake port 35h which opens toward the downstream side of the exhaust pipe EP and is connected to the cylindrical mixing region MX1 (see FIGS. 3 and 4). ..

Further, the nozzle member 35 has a cylindrical rear end side cylinder wall portion 35c extending from the peripheral edge of the nozzle portion 35a to the rear end side GK, and a cylindrical discharge space DS is formed inside thereof. Since the discharge space DS communicates with the inside of the rear cover 15, the air (compressed air) AR supplied into the rear cover 15 described above flows into the discharge space DS (FIGS. 3, 4, and 5). 8 and FIG. 13).

The mixing/discharging member 37 is a member made of stainless steel having an outer cylindrical shape, and is fitted into the tip end portion of the nozzle member 35 from the rear end side GK and is fixed thereto. The mixing and discharging member 37 includes a discharging rear end portion 37a located on the rear end side GK and a cylindrical tube wall portion 37b extending from the peripheral edge of the discharging rear end portion 37a to the front end side GS. Of these, the discharge rear end portion 37a is provided with a collecting electrode 37c that bulges inward in the radial direction, and the collecting electrode 37c forms a slit-shaped mixing region MX2 that is a slit-shaped space. There is. The slit-shaped mixing area MX2 communicates with the above-mentioned cylindrical mixing area MX1 (see FIG. 4).

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

Next, the inner cylinder 31 (cylindrical member) will be described. FIG. 9 is a plan view of the first member 32 and the second member 34 forming the inner cylinder 31 (a view from the front end side GS to the rear end side GK in the axial direction GH). FIG. 10 is a front view of the first member 32 and the second member 34, and corresponds to a B view of FIG. 9.

The inner cylinder 31 is a cylindrical cylindrical member made of stainless steel and extending in the axial direction GH (see FIGS. 3, 4, 6, 9, and 10). The inner cylinder 31 includes a semi-cylindrical first member 32 and a semi-cylindrical second member 34, and is formed by combining the first member 32 and the second member 34. The first member 32 and the second member 34 have the same shape. Specifically, the first member 32 and the second member 34 have a semi-cylindrical shape obtained by bisecting the inner cylinder 31 in the axial direction GH.

As shown in FIGS. 9 and 10, the first member 32 has a semi-cylindrical separator covering portion 32b and a semi-cylindrical contact conducting portion 32c located on the rear end side GK. Of these, the contact conducting portion 32c is located on the radially inner side (center side of the inner cylinder 31) and has a semi-cylindrical first contact surface 32f and a semi-cylindrical second contact surface 32g that extend in the axial direction GH. It has a cylindrical ventilation port 32d that is located on the radially outer side (the outer peripheral side of the inner cylinder 31) and that penetrates the contact conducting portion 32c in the axial direction GH.

As shown in parentheses in FIGS. 9 and 10, the second member 34 has a semi-cylindrical separator covering portion 34b and a semi-cylindrical contact conducting portion 34c located on the rear end side GK. Of these, the contact conducting portion 34c is located on the radially inner side (center side of the inner cylinder 31) and has a semi-cylindrical first contact surface 34f and a semi-cylindrical second contact surface 34g that extend in the axial direction GH. It has a semi-cylindrical ventilation port 34d that is located radially outside (outer peripheral side of the inner cylinder 31) and extends in the axial direction GH.

An electrically insulating separator 41 is housed inside the inner cylinder 31 that is a combination of the first member 32 and the second member 34 described above (see FIGS. 3 and 4 ). Specifically, the separator 41 is housed in a cylindrical portion (cylindrical separator housing space) formed by the separator coating portion 32b of the first member 32 and the separator coating portion 34b of the second member 34. As a result, the separator 41 is held by the inner cylinder 31.

The first member 32 and the second member 34 are arranged so that the first contact surface 32f of the first member 32 and the first contact surface 34f of the second member 34 are arranged to face each other, and thus the first contact surface 32f. And a first contact surface 34f are connected to form a cylindrical contact surface, and the second contact surface 32g of the first member 32 and the second contact surface 34g of the second member 34 are arranged to face each other. As a result, a cylindrical contact surface in which the second contact surface 32g and the second contact surface 34g are connected is formed, and the contact conducting portion 32c of the first member 32 and the contact conducting portion 34c of the second member 34 are connected to each other. Are face-to-face contact and are combined. At this time, the separator coating portion 32b of the first member 32 and the separator coating portion 32b of the second member 34 are connected to each other to form a cylindrical separator accommodating space.

The inner diameter of the cylindrical contact surface connecting the first contact surface 32f and the first contact surface 34f is equal to the outer diameter of the first reference potential wiring 93. The first reference potential wiring 93 is arranged inside the cylindrical contact surface that connects the first contact surface 32f and the first contact surface 34f. As a result, the first contact surface 32f and the first contact surface 34f of the inner cylinder 31 come into contact with the first reference potential wiring 93 and become conductive. Further, the cylindrical contact surface in which the second contact surface 32g and the second contact surface 34g are connected is equivalent to the outer diameter of the second reference potential wiring 103. The second reference potential wiring 103 is arranged inside the cylindrical contact surface that connects the second contact surface 32g and the second contact surface 34g. As a result, the second contact surface 32g and the second contact surface 34g of the inner cylinder 31 come into contact with the second reference potential wiring 103 and become conductive.

The inner cylinder 31 is fixed inside the sensor body 5. Specifically, the tip portion of the inner cylinder 31 (the tip portion of the separator coating portion 32b and the tip portion of the separator coating portion 32b) is externally fitted to the rear end portion of the pipe holder 33, and this external fitting portion (the inner tube 31 The front end of the inner cylinder 31 is fixed to the inside of the sensor main body 5 by welding the front end thereof to the rear end of the pipe holder 33).

The inner cylinder 31 has its rear end portion (specifically, the contact conducting portion 32c of the first member 32 and the contact conducting portion 34c of the second member 34) inserted inside the cylindrical metal holding member 42. It is held by the metal holding member 42 in a fixed state. As a result, the state in which the first member 32 and the second member 34 are combined to form the cylindrical inner cylinder 31 can be maintained, and the rear end portion of the inner cylinder 31 is fixed inside the sensor body 5. To be done. The rear end portion of the inner cylinder 31 (specifically, the contact conducting portion 32c of the first member 32 and the contact conducting portion 34c of the second member 34) and the metal holding member 42 are fixed by welding.

The metal holding member 42 has a cylindrical side wall portion 42b extending in the axial direction GH and an annular bottom portion 42c connected to the rear end portion of the side wall portion 42b (see FIGS. 4 and 6). A circular vent hole 42d is provided in the bottom portion 42c. The air (compressed air) AR supplied into the above-mentioned rear cover 15 flows from the rear end side GK in the axial direction GH to the front end side GS in the sensor main body 5 through the ventilation hole 42d of the metal holding member 42.

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

The separator 41 is made of an electrically insulating member (ceramic containing alumina as a main component) and has a columnar shape extending in the axial direction GH (see FIGS. 3, 4, 6, 11, and 12 ). The separator 41 has a first through hole 41b and a second through hole 41c that penetrate the separator 41 in the axial direction GH. The first through hole 41b and the second through hole 41c are independent and independent through holes, and are separated in the direction orthogonal to the axial direction GH (the horizontal direction in FIG. 3) with the wall portion of the separator 41 interposed therebetween.

Inside the first through hole 41 b of the separator 41, the tip end portion of the first cable 90 and the first extending portion 71 of the discharge electrode body 70 are inserted. Inside the first through hole 41b, the discharge potential connecting portion 111 (the tip portion 91b of the discharge potential wiring 91 and the rear end portion of the first extending portion 71 of the discharge electrode body 70) is connected to the first connecting terminal 77. The parts connected through) are arranged.

Further, the distal end portion of the second cable 100 and the second extending portion 81 of the auxiliary electrode body 80 are inserted inside the second through hole 41c of the separator 41. Then, inside the second through hole 41c, the auxiliary potential connecting portion 112 (the front end portion 101b of the auxiliary potential wiring 101 and the rear end portion of the second extending portion 81 of the auxiliary electrode body 80) is connected to the second connecting terminal 87. The parts connected through) are arranged.

As a result, the discharge potential connection portion 111 having the discharge potential PV2 and the auxiliary potential connection portion 112 having the auxiliary potential PV4 are electrically insulated by the separator 41.
Therefore, the particle sensor 1 of the present embodiment is a particle sensor in which the discharge potential connecting portion 111 and the auxiliary potential connecting portion 112 are properly electrically insulated by the separator 41.

By the way, in the present embodiment, when the inner cylinder 31 is formed by combining the first member 32 and the second member 34 so as to cover the outer circumference of the separator 41, the inner circumference of the first member 32 (separator covering portion 32b). The surface 32h and the inner peripheral surface 34h of the second member 34 (separator coating portion 32b) contact the outer peripheral surface 41d of the separator 41. Accordingly, the inner cylinder 31 (the first member 32 and the second member 34) can sandwich and hold the separator 41 inward in the radial direction. Further, the inner cylinder 31 is fixed inside the sensor body 5 as described above.

In this way, the separator 41 is held in such a manner that the outer circumference of the separator 41 is covered (enclosed) by the inner cylinder 31 (cylindrical member) fixed inside the sensor body 5, and thus the separator 41 is held. 41 is also fixed inside the sensor body 5 through the inner cylinder 31. As a result, the discharge potential connecting portion 111 is arranged in the first through hole 41b of the separator 41, and the auxiliary potential connecting portion 112 is arranged in the second through hole 41c of the separator 41. The state in which 111 and the auxiliary potential connecting portion 112 are electrically insulated by the separator 41 can be stably maintained.

Moreover, in the present embodiment, the inner cylinder 31 (cylindrical member) is formed by combining the first member 32 and the second member 34 so as to cover the outer periphery of the separator 41, so that the separator 41 is separated by the inner cylinder 31. In addition to holding the inner cylinder 31, the inner cylinder 31 is brought into contact with the first reference potential wiring 93 and the second reference potential wiring 103 to make them conductive. Specifically, the tip portion 93b of the first reference potential wiring 93 comes into contact with the first contact surface 32f of the first member 32 and the first contact surface 34f of the second member 34 to be conductive, and the second reference potential The tip portion 103b of the wiring 103 comes into contact with the second contact surface 32g of the first member 32 and the second contact surface 34g of the second member 34 to conduct electricity (see FIGS. 3, 9, and 10). As a result, the first reference potential wiring 93 and the second reference potential wiring 103 can be electrically connected to the inner fitting 30 (reference potential member) including the inner cylinder 31 simply and appropriately.

Next, the discharge electrode body 70 will be described. The discharge electrode body 70 is made of a tungsten wire and is arranged inside the inner metal fitting 30 in the radial direction so as to be insulated from the inner metal fitting 30. As shown in FIG. 3, the discharge electrode body 70 is composed of a straight rod-shaped first extending portion 71 and a needle-like tip portion 73 positioned at the tip portion thereof and having a needle-like pointed shape. The discharge electrode body 70 (needle-shaped tip portion 73) is connected to the external circuit portion 201 through the discharge potential wiring 91 of the first cable 90 and has the discharge potential PV2. The discharge potential PV2 is a positive high potential with respect to the reference potential PV1 and has a peak potential of 1 to 2 kV.

The first extending portion 71 is covered with a cylindrical first insulating pipe 75, which is made of insulating ceramic, around the radial direction thereof. However, since the rear end portion of the first extending portion 71 is connected to the front end portion 91b of the discharge potential wiring 91 by the first connecting terminal 77, the tungsten wire is exposed without being covered with the first insulating pipe 75. doing.

On the other hand, the needle-shaped tip portion 73 projects toward the tip side GS in the discharge space DS and faces the nozzle portion 35a, and constitutes an ion source together with the nozzle portion 35a. That is, as will be described later, the nozzle portion 35a having the reference potential PV1 and the needle-shaped tip portion 73 having the discharge potential PV2 generate the ion CP attached to the fine particles S by the air discharge generated therebetween. To generate.
In the present embodiment, the nozzle portion 35a corresponds to the discharge counter electrode portion that is the counter electrode of the discharge electrode body 70 (needle-shaped tip portion 73).

Next, the auxiliary electrode body 80 will be described. The auxiliary electrode body 80 is made of a stainless wire, and is arranged inside the inner metal fitting 30 in the radial direction so as to be insulated from the inner metal fitting 30. As shown in FIG. 3, the auxiliary electrode body 80 includes a straight bar-shaped second extending portion 81, a bending-back portion 82 bent back in a U-shape at its tip side GS, and a bending-back portion 82 to a rear end. The auxiliary electrode portion 83 extends to the side GK and has a needle-like sharp tip.

The second extending portion 81 is covered with a cylindrical second insulating pipe 85 made of insulating ceramic. However, since the rear end portion of the second extending portion 81 is connected to the front end portion 101b of the auxiliary potential wiring 101 by the second connecting terminal 87, the rear end portion is not covered with the second insulating pipe 85, and the stainless wire is exposed. doing. In addition, the bent back portion 82 is arranged in the gas exhaust path EX.

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

By the way, in the particle sensor 1 of the present embodiment, as shown in FIGS. 6 and 11, the separator 41 has, on its outer peripheral surface 41d, a groove forming surface 41g forming a groove portion 41f extending in the axial direction GH. .. The groove 41f extends from the front end to the rear end of the separator 41 in the axial direction GH in a form in which a part of the outer peripheral surface 41d of the separator 41 is recessed inward in the radial direction.

Two groove portions 41f (groove constituting surface 41g) are formed on the outer peripheral surface 41d of the separator 41. The two groove portions 41f (the groove forming surface 41g) are provided so as to face (backward) in the radial direction of the separator 41. Then, in a state where the outer circumference of the separator 41 is covered with the inner cylinder 31, the groove forming surface 41g of the separator 41 and the inner peripheral surface of the inner cylinder 31 (the inner peripheral surface 32h of the first member 32 and the inner peripheral surface of the second member 34). A vent hole AH surrounded by the surface 34h) is formed (see FIGS. 3 and 11). Note that, in FIG. 11, the inner cylinder 31 arranged on the outer periphery of the separator 41 is shown by a chain double-dashed line.

Furthermore, in the particle sensor 1 of the present embodiment, as described above, the sensor main body 5 is attached to the rear end of the sensor main body 5 in the axial direction GH (specifically, the rear cover 15) from outside the sensor main body 5. An air intake portion 15t for taking in the air AR is provided inside the. Further, in the sensor main body 5, the air AR taken into the sensor main body 5 through the air intake portion 15t is introduced to the tip end side in the axial direction GH in the sensor main body 5 through the ventilation hole AH. Has a morphology.

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

Next, the electrical function and operation of the particle sensor 1 will be described (see FIGS. 8 and 13). By driving the external circuit portion 201, the nozzle portion 35a (discharge counter electrode portion) of the inner metal fitting 30 set to the reference potential PV1 and the needle of the discharge electrode body 70 set to the discharge potential PV2 that is a positive potential higher than this. An air discharge (corona discharge) is generated between the positive end portion 73 and the end portion 73, and positive ions CP generated by ionizing N ₂ , O _{2 and the} like of the atmosphere (air) are generated. On the other hand, the air AR is supplied from the rear end side GK into the discharge space DS. Therefore, a part of the generated ions CP is jetted together with the air AR from the nozzle portion 35a to the cylindrical mixing region MX1.

When the air AR is injected into the columnar mixing region MX1, the atmospheric pressure in the columnar mixing region MX1 drops, so that the exhaust gas EG is taken into the columnar mixing region MX1 from the gas intake port 35h. The intake gas EGI is mixed with the air AR, and is discharged from the gas discharge port 37h via the slit-shaped mixing region MX2 and the gas discharge passage EX. At that time, the fine particles S such as soot in the exhaust gas EG are also taken into the cylindrical mixing region MX1. The fine particles S become positively charged charged fine particles SC to which the ions CP are attached, and in this state, they are discharged together with the air AR from the gas discharge port 37h. On the other hand, among the ions CP ejected to the cylindrical mixing region MX1, the floating ions CPF that have not adhered to the fine particles S are repelled by the auxiliary electrode portion 83 of the auxiliary electrode body 80 having the auxiliary potential PV4 and collected. By adhering to the pole 37c, discharge from the gas discharge port 37h is suppressed.

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

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

Therefore, the amount of the fine particles S in the exhaust gas EG can be detected by detecting the signal current corresponding to the charge amount of the discharged ions CPH discharged by the charged fine particles SC in the circuit unit 201. Therefore, in the present embodiment, based on the charge amount of the charged fine particles SC (specifically, based on the signal current flowing between the reference potential PV1 and the ground potential PVE according to the charge amount of the charged fine particles SC). , The amount of fine particles S in the exhaust gas EG (gas to be measured) is detected.

By the way, in the particle sensor 1 of the present embodiment, as described above, the separator 41 appropriately electrically insulates the discharge potential connecting portion 111 and the auxiliary potential connecting portion 112. For this reason, there is no possibility that discharge or the like will occur between the discharge potential connection portion 111 and the auxiliary potential connection portion 112, and the needle-like tip portion 73 (discharge potential PV2) of the discharge electrode body 70 and the nozzle portion that will be the discharge counter electrode portion. An air discharge can be appropriately generated between 35a (reference potential PV1). This makes it possible to properly detect the amount of the fine particles S in the exhaust gas EG (gas to be measured).

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

Next, a method of assembling the particle sensor 1 of this embodiment will be described.
First, the tip portion of the first cable 90 is inserted into the first through hole 41b of the separator 41, and the tip portion of the second cable 100 is inserted into the second through hole 41c. Then, outside the separator 41, the front end portion 91 b of the discharge potential wiring 91 and the rear end portion of the first extension portion 71 of the discharge electrode body 70 are connected by caulking connection of the first connection terminal 77. Further, the front end portion 101b of the auxiliary potential wiring 101 and the rear end portion of the second extending portion 81 of the auxiliary electrode body 80 are connected by caulking the second connection terminal 87.

After that, the first cable 90 is pulled back to the rear end side GK, and inside the first through hole 41b of the separator 41, the discharge potential connecting portion 111 (the tip portion 91b of the discharge potential wiring 91 and the first extension of the discharge electrode body 70). A portion where the rear end of the projecting portion 71 is connected through the first connecting terminal 77 is arranged. Further, the second cable 100 is pulled back to the rear end side GK, and inside the second through hole 41c of the separator 41, the auxiliary potential connecting portion 112 (the tip end portion 101b of the auxiliary potential wiring 101 and the second extension of the auxiliary electrode body 80) is inserted. A portion where the rear end of the output portion 81 is connected through the second connection terminal 87 is arranged.

Then, the first metal member 21 is externally fitted to the tip end portion 97b of the first ground potential wiring 97 of the first cable 90, and while the first metal member 21 is press-fitted into the first through hole 15b of the rear cover 15, the first cable 90 is attached to the rear cover. Insert through 15. Further, the second metal member 22 is externally fitted to the tip end portion 107b of the second ground potential wiring 107 of the second cable 100, and the second cable 100 is fitted into the second through hole 15c of the rear cover 15 while being pressed. Insert through 15. In addition, the metal holding member 42, the rubber member 44, and the washer 45 are previously inserted into the first cable 90 and the second cable 100. After that, the first O-ring 23 and the first retainer 25 are inserted from the rear end side GK into the first through hole 15b of the rear cover 15 in a manner of being fitted onto the first cable 90. Further, the second O-ring 24 and the second retainer 26 are inserted from the rear end side GK into the second through hole 15c of the rear cover 15 in a manner to be fitted onto the second cable 100.

Next, the inner cylinder 31 (cylindrical member) is formed by combining the first member 32 and the second member 34 so as to cover the outer periphery of the separator 41. As a result, the inner cylinder 31 holds the separator 41, and the inner cylinder 31 is brought into contact with the first reference potential wiring 93 and the second reference potential wiring 103 to be electrically connected. Then, the rear end portion of the inner cylinder 31 is inserted inside the metal holding member 42. Next, the cylindrical insulating member 43 is formed by the insulating members 43b and 43c while arranging the two semi-cylindrical insulating members 43b and 43c in combination between the metal holding member 42 and the rubber member 44. ..

After that, the tip of the inner cylinder 31 is inserted into the pipe holder 33, and both are welded. The nozzle member 35, the mixing and discharging member 37, and the lid member 39 are joined to the tip side GS of the pipe holder 33. As a result, the inner metal member 30 in which the discharge electrode body 70 and the auxiliary electrode body 80 are arranged is formed. Next, the rear end portion of the outer first metal fitting 11 is press-fitted into the front end portion of the rear cover 15 to join them together. The fastening member 60 is previously inserted into the outer first metal fitting 11. Then, by arranging the outer second metal fitting 13 on the tip side GS of the outer first metal fitting 11, the particle sensor 1 is completed.

(Variation)
The particle sensor 301 according to the modified embodiment is different from the particle sensor 1 of the embodiment in the structure of the rear end side GK of the sensor main body, and is otherwise the same. Therefore, here, the description will be focused on the points different from the particle sensor 1 of the embodiment, and the description of the same points will be omitted or simplified.

FIG. 14 is a vertical cross-sectional view of the particle sensor 301 according to the modification. FIG. 15 is an exploded perspective view of the particle sensor 301.
The particle sensor 301 according to the present modification is different from the particle sensor 1 according to the embodiment in some of the components constituting the sensor main body, and the other parts are the same. The sensor main body 305 of the present modified example includes an outer metal fitting 310 instead of the outer metal fitting 10 of the embodiment. The outer metal fitting 310 is the same as the outer metal fitting 10 of the embodiment in that the rear cover 15 is replaced with a rear cover 315, and is otherwise the same (see FIGS. 6 and 15).

Further, in the sensor main body 305 of the present modified embodiment, the first metal member 21 and the second metal member 22 are eliminated and the first retainer 25 is changed to the first retainer 325, as compared with the sensor main body 5 of the embodiment. However, the point that the second retainer 26 is changed to the second retainer 326 is different, and the others are the same (see FIGS. 6 and 15 ).

The rear cover 315 of the present modification is different from the rear cover 15 of the embodiment in that the length in the axial direction GH is shortened, and the other is the same (see FIGS. 3, 6, 14, and 15 ). ..

In addition, the first retainer 325 of the present modification has a longer length in the axial direction GH than the first retainer 25 of the embodiment. More specifically, the first retainer 325 corresponds to a component in which the first metal member 21 and the first retainer 25 of the embodiment are integrated. The first retainer 325 has a cylindrical insertion portion 325c located on the front end side GS in the axial direction GH and a cylindrical caulking connection portion 325b located on the rear end side GK.

Of these, the insertion portion 325c is a portion inserted into the first through hole 315b of the rear cover 315 from the rear end side GK. The caulking connection portion 325b is a portion connected to the tip end portion 97b of the first ground potential wiring 97. The caulking connection portion 325b is caulked inward in the radial direction with the tip portion 97b of the first ground potential wiring 97 inserted and arranged inside the caulking connection portion 325b. It is conductive in the pressed state. A portion of the first retainer 325 that is on the rear end side GK of the insertion portion 325c (a portion that includes the caulking connection portion 325b) is disposed so as to project from the rear end of the rear cover 315 to the outside of the rear cover 315.

Further, the second retainer 326 of the present modified embodiment also has a longer length in the axial direction GH than the second retainer 26 of the embodiment. More specifically, the second retainer 326 corresponds to a component in which the second metal member 22 and the second retainer 26 of the embodiment are integrated. The second retainer 326 has a cylindrical insertion portion 326c located on the front end side GS in the axial direction GH and a cylindrical caulking connection portion 326b located on the rear end side GK.

Of these, the insertion portion 326c is a portion inserted into the second through hole 315c of the rear cover 315 from the rear end side GK. The caulking connection portion 326b is a portion connected to the tip portion 107b of the second ground potential wiring 107. The caulking connection portion 326b is caulked inward in the radial direction with the tip portion 107b of the second ground potential wiring 107 inserted and arranged inside the caulking connection portion 326b. It is conductive in the pressed state. A portion of the second retainer 326 that is on the rear end side GK with respect to the insertion portion 326c (a portion that includes the caulking connection portion 326b) is arranged so as to project from the rear end of the rear cover 315 to the outside of the rear cover 315.

Also in the particle sensor 301 of this modification, the discharge potential connection part 111 and the auxiliary potential connection part 112 are appropriately electrically insulated by the separator 41, as in the particle sensor 1 of the embodiment. For this reason, there is no risk that discharge or the like will occur between the discharge potential connection portion 111 and the auxiliary potential connection portion 112, and the needle tip portion 73 (discharge potential PV2) of the discharge electrode body 70 and the nozzle portion serving as the discharge counter electrode portion. An air discharge can be appropriately generated between 35a (reference potential PV1). This makes it possible to properly detect the amount of the fine particles S in the exhaust gas EG (gas to be measured).

Next, a method of assembling the particle sensor 301 of this modified embodiment will be described.
First, similarly to the embodiment, the tip portion of the first cable 90 is inserted into the first through hole 41b of the separator 41, and the tip portion of the second cable 100 is inserted into the second through hole 41c. After that, the discharge potential connecting portion 111 is arranged inside the first through hole 41b of the separator 41, and further the auxiliary potential connecting portion 112 is arranged inside the second through hole 41c of the separator 41.

The first cable 90 and the second cable 100 have the rear cover 315, the first retainer 325, the second retainer 326, the rubber member 44, and the washer 45 inserted in advance. In addition, the first O-ring 23 and the insertion portion 325c of the first retainer 325 are inserted (press-fitted) into the first through-hole 315b of the rear cover 315 in advance, and the second O-ring 24 and the second O-ring 24 and the second retainer 325 are inserted into the second through-hole 315c. The insertion portion 326c of the retainer 326 is inserted (press-fitted) in advance.

Next, similar to the embodiment, the inner cylinder 31 (cylindrical member) is formed by combining the first member 32 and the second member 34 so as to cover the outer periphery of the separator 41, and the inner cylinder 31 separates the separator. 41 is held, and the inner cylinder 31 is brought into contact with the first reference potential wiring 93 and the second reference potential wiring 103 to make them conductive. Thereafter, similarly to the embodiment, the rear end portion of the inner cylinder 31 is inserted inside the metal holding member 42, and the insulating members 43b and 43c are combined between the metal holding member 42 and the rubber member 44 to insulate the insulating member 43. To place.

After that, the tip of the inner cylinder 31 is inserted into the pipe holder 33, and both are welded. The nozzle member 35, the mixing and discharging member 37, and the lid member 39 are joined to the tip side GS of the pipe holder 33. As a result, the inner metal member 30 in which the discharge electrode body 70 and the auxiliary electrode body 80 are arranged is formed. Next, the rear end of the outer first metal fitting 11 is press-fitted into the front cover 315 to join them. The fastening member 60 is previously inserted into the outer first metal fitting 11. Then, the outer second metal fitting 13 is arranged on the tip side GS of the outer first metal fitting 11.

Then, the caulking connection portion 325b of the first retainer 325 is caulked, so that the caulking connection portion 325b is brought into pressure contact with the tip end portion 97b of the first ground potential wiring 97 to make it conductive. Further, by caulking the caulking connection portion 326b of the second retainer 326, the caulking connection portion 326b is brought into pressure contact with the tip end portion 107b of the second ground potential wiring 107 to be electrically connected. As a result, the particle sensor 301 of this modification is completed.

In the above, the present invention has been described according to the embodiment and the modified embodiment, but the present invention is not limited to the above-described embodiment and the modified embodiment, and is appropriately modified and applied without departing from the scope of the invention. It goes without saying that you can do it.

For example, in the embodiment, the sensor body 5 including the rear cover 15 having the air intake portion 15t is used, and clean air (compressed air) AR generated by the pressure pump 330 installed outside is supplied to the air intake portion 15t. The fine particle sensor has a structure in which the air AR is supplied to the inside of the sensor main body 5 through the above and the air AR is circulated in the discharge space DS. However, the present invention can also be applied to a particle sensor that does not have such a configuration.

1,301 Particle Sensor 5,305 Sensor Body 10 Outside Metal Fittings 15,315 Rear Covers 15t, 315t Air Intake Portion 30 Inner Metal Fittings (Reference Potential Member)
31 Inner cylinder (cylindrical member)
32 1st member 34 2nd member 41 Separator 41b 1st penetration hole 41c 2nd penetration hole 41f Groove part 41g Groove constituent surface 42 Metal holding member (holding member)
35a Nozzle part (discharge counter electrode part)
50 Air tube 70 Discharge electrode body 73 Needle-shaped tip portion 80 Auxiliary electrode body 90 First cable 91 Discharge potential wiring 92 First insulator layer 93 First reference potential wiring 97 First ground potential wiring 98 Outer insulating coating layer 100 Second Cable 101 Auxiliary potential wiring 102 First insulator layer 103 Second reference potential wiring 107 Second ground potential wiring 108 Outer insulating coating layer 111 Discharge potential connection portion 112 Auxiliary potential connection portion 201 Circuit portion 330 Pressure pump AH Vent hole AR air AX Axis of fine particle sensor (sensor main body) GH Axis direction GS Axis front end GK Axis rear end EP EP Exhaust pipe (vent pipe)
EG Exhaust gas (measured gas)
S fine particles SC charged fine particles CP ions PV1 reference potential PV2 discharge potential PV4 auxiliary potential PVE ground potential

Claims (4)

A sensor main body that has a form extending in the axial direction and is attached to the ventilation pipe and detects the amount of fine particles in the gas to be measured flowing through the ventilation pipe,
A fine particle sensor comprising: a first cable and a second cable that electrically connect between a circuit unit that drives the sensor body and the sensor body.
The sensor body is
A reference potential member used as a reference potential,
A discharge electrode body having a discharge potential different from the reference potential, and
An auxiliary electrode body having an auxiliary potential different from the reference potential and the discharge potential,
The first cable is
Discharge potential wiring that is electrically connected to the discharge electrode body, and
A cylindrical first reference potential wiring that conducts to the reference potential member and surrounds the radial circumference of the discharge potential wiring;
The second cable is
Auxiliary potential wiring that conducts to the auxiliary electrode body, and
A second reference potential wiring having a cylindrical shape that is electrically connected to the reference potential member and surrounds a circumference of the auxiliary potential wiring in a radial direction;
The sensor body is
A separator having a columnar shape extending in the axial direction, including a separator having a first through hole and a second through hole penetrating the separator in the axial direction,
The particle sensor is
A discharge potential connecting portion in which the discharge potential wiring of the first cable and the discharge electrode body are connected,
An auxiliary potential connecting portion in which the auxiliary potential wiring of the second cable and the auxiliary electrode body are connected to each other,
The discharge potential connecting portion is arranged in the first through hole of the separator, and the auxiliary potential connecting portion is arranged in the second through hole of the separator, thereby the discharge potential connecting portion and the The auxiliary potential connecting portion is electrically insulated by the separator,
The reference potential member,
A tubular member having a tubular shape extending in the axial direction by combining a semi-cylindrical first member and a semi-cylindrical second member, wherein the tubular member is fixed inside the sensor main body. Including,
The tubular member is
By combining the first member and the second member in a manner of covering the outer periphery of the separator, the separator is held, and the first reference potential wiring and the second reference potential wiring are brought into contact with each other to conduct electricity. Particle sensor. The particle sensor according to claim 1, wherein
The sensor body has a tubular holding member,
The cylindrical member is a fine particle sensor held by the holding member in a state where one end of the tubular member is inserted and fixed inside the holding member. The particle sensor according to claim 1 or 2, wherein
The separator is
On the outer peripheral surface thereof, a groove forming surface forming a groove portion extending in the axial direction,
In a state in which the outer periphery of the separator is covered by the tubular member, forming a vent hole surrounded by the groove forming surface and the inner peripheral surface of the tubular member,
The sensor body is
At the rear end in the axial direction, there is an air intake part for taking in air from the outside of the sensor main body to the inside of the sensor main body,
The fine particle sensor having a form in which the air taken into the sensor main body through the air intake part is introduced to the tip end side in the axial direction inside the sensor main body through the ventilation hole. The particle sensor according to any one of claims 1 to 3,
The reference potential member includes a discharge counter electrode portion that is a counter electrode of the discharge electrode body,
The fine particle sensor generates an aerial discharge between the discharge electrode body and the discharge counter electrode part, attaches ions generated by the aerial discharge to the fine particles contained in the gas to be measured, and is charged. A fine particle sensor that generates charged fine particles and detects the amount of the fine particles in the gas to be measured based on the charge amount of the charged fine particles.

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