JP2019039899A - Fine particle sensor and method of manufacturing fine particle sensor - Google Patents

Abstract

To provide a fine particle sensor which has a discharge element held airtightly inside with a simple structure, and a method of manufacturing the fine particle sensor.SOLUTION: A fine particle sensor 10 which is loaded in a vent pipe EP where a measurement object gas EG including fine particles S circulate so as to detect fine particles comprises: a gas intake discharge pipe 31 which discharges a measured gas SG after taking it in; a discharge element 60 which has a discharge electrode body 62 held at a discharge potential DV, the discharge element having an element tip part 60S positioned on a tip side GS of the discharge element, arranged in the gas intake discharge pipe, and electrifies fine particles in the measured gas through discharging, and a sealed part 60C positioned on a base end side GK of the element tip part, having the discharge electrode body arranged inside, and insulated from an outer surface 60CS; enclosure members 38, 39 held at a first potential SGND and enclosing an element base end-side part 60K, more on the base end side than the sealed part, of the discharge element; and an electrically conductive seal body 37 made of conductive glass, electrically conducting between the enclosure members and gas intake discharge pipe, and contacting and airtightly sealing an outer surface of the sealed part of the discharge element.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a fine particle sensor used by being attached to a metal vent pipe through which a measurement target gas containing fine particles flows, and a method for manufacturing the same.

  There is known a fine particle sensor that is used by being attached to a ventilation pipe and detects the amount of fine particles contained in a measurement target gas flowing through the ventilation pipe. For example, there is a particle sensor that is mounted on an exhaust pipe of an internal combustion engine (diesel engine, gasoline engine, etc.) and detects the amount of particles such as soot contained in the exhaust gas. More specifically, after taking in the exhaust gas flowing through the exhaust pipe and attaching the ions generated by air discharge to the fine particles in the intake gas to form charged fine particles, the exhaust gas is discharged to the exhaust pipe together with the intake gas. There is a fine particle sensor.

  The fine particle sensor includes, for example, an outer metal fitting, an inner metal fitting, and an insulating spacer. Of these, the outer metal fitting is a cylindrical member that is attached to the exhaust pipe and has a ground potential. Further, the inner metal fitting is a member that is disposed on the inner side in the radial direction of the outer metal fitting and insulated from the outer metal fitting and has a first potential different from the ground potential. The insulating spacer is a cylindrical member that is held between the inner metal fitting and the outer metal fitting to electrically insulate the two, and is exposed in the exhaust pipe and exposed to the exhaust gas. Such a fine particle sensor is disclosed in Patent Document 1, for example.

International Publication No. 2016/027894

  In this fine particle sensor, a discharge element having a discharge electrode body at a discharge potential is surrounded by an inner metal fitting at a first potential to form a Faraday cage, and is kept airtight. Specifically, the distal end portion of the discharge element is arranged in a gas intake / exhaust pipe that forms an inner metal fitting, and a plurality of cylindrical metal members that are connected to the gas intake / exhaust pipe at a base end side from the distal end portion are provided. Siege. On the other hand, the discharge element is held in these metal members with a compact of an insulating powder such as an insulator made of insulating ceramic or talc powder, and with the above-mentioned green compact that is in close contact with the discharge element and the metal member. The periphery of the element is hermetically sealed.

However, the particulate sensor of this form requires a discharge element, an insulator and a green compact that hold the discharge element in an airtight manner, a metal shell that surrounds and holds the discharge element, and has a complicated structure and tends to be expensive. .
The present invention has been made in view of such problems, and provides a particulate sensor having a simple structure and holding a discharge element in an airtight manner, and a manufacturing method thereof.

  One aspect of the present invention for solving the above-described problem is a fine particle for detecting the fine particles in the measurement target gas, which is attached to a metal vent pipe through which a measurement target gas containing fine particles flows and is grounded. A sensor, comprising a gas intake / exhaust pipe that discharges a gas to be measured, which is a part of the gas to be measured, into the inside thereof, and an insulating ceramic, and has a discharge potential different from the ground potential. A discharge element having a discharge electrode body, located on the distal end side of the discharge element, disposed in the gas intake / exhaust pipe, and by discharge between the discharge electrode body and the gas intake / exhaust pipe, A device tip portion for charging the fine particles in the gas to be measured, and a sealed portion located on the base end side of the device tip portion and having the discharge electrode body disposed therein and insulated from the outer surface Discharge element and above The first potential is different from the ground potential and the discharge potential. Among the discharge elements, the surrounding member surrounds the base end side portion of the base end side of the sealed portion, and is made of conductive glass. A fine particle sensor comprising: a conductive sealing body that conducts between an enclosing member and the gas intake / exhaust pipe, and is in close contact with the outer surface of the sealed portion of the discharge element and hermetically seals.

In this fine particle sensor, a conductive seal body made of conductive glass surrounds the outer surface of the sealed portion of the discharge element and is tightly adhered. For this reason, the discharge element is hermetically held by the conductive seal body in the sealed portion.
In addition, since the conductive sealing body is made of conductive glass and is electrically connected between the surrounding member set to the first potential and the gas intake / discharge pipe, the gas intake / discharge pipe is set to the first potential. Therefore, since a metal block-like member such as a metal shell is not required for electrical connection between the surrounding member and the gas intake / exhaust pipe, the fine particles having the discharge element held in an airtight manner while having a simple configuration. It can be a sensor.

  Since the discharge electrode body is disposed in the insulator in the sealed portion of the discharge element, the discharge electrode body is prevented from being short-circuited with the conductive seal body in the sealed portion. That is, the discharge element does not conduct with the conductive seal body in the sealed portion, and the discharge electrode body of the discharge element is set to the first potential, the surrounding member, the conductive seal body, and the gas intake. It is held in a Faraday cage consisting of a discharge pipe.

The gas intake / exhaust pipe is a tubular member that discharges the gas to be measured after it is taken into the interior, but in addition to a single pipe structure, a double pipe structure in which two pipes are arranged coaxially on the inside and outside, Also, those having a labyrinth structure in which the path of the gas to be measured flowing inside is complicated can be used.
Further, the gas intake / discharge pipe may be in a form in which the gas intake / discharge pipe is indirectly connected to the conductive seal body through another metal member in addition to the form in contact with the conductive seal body.

  Examples of the conductive glass that forms the conductive seal body include those in which conductive particles such as metal particles are dispersed in an insulating glass. In forming a conductive sealing body made of such conductive glass, the temperature of the conductive glass powder containing the insulating glass powder and the conductive powder is raised to a temperature equal to or higher than the softening point of the insulating glass powder. A technique for fusing powders together is mentioned. Examples of the conductive powder used for the conductive glass include metal powders such as copper powder, brass powder, and nickel powder, and non-metallic conductive powders such as graphite powder and carbon black. Examples of the insulating glass include calcium borosilicate glass, borosilicate glass, and soda lime glass. Moreover, the glass powder with a metal film which formed the metal film on the glass powder by plating etc. can also be used as electroconductive glass powder.

  In the fine particle sensor described above, one end of the discharge element is connected to the ground potential, and the element heater wiring for raising the temperature of the tip of the element is interposed between the element heater wiring and the discharge electrode body. Thus, it is preferable to have a shield electrode layer that electromagnetically shields the two, and the shield electrode layer is a fine particle sensor that is electrically connected to the conductive seal body.

In the fine particle sensor, the temperature of the tip of the element is increased in order to prevent foreign particles from adhering to the element tip exposed to the gas to be measured, or to remove the adhering particles. In order to make it possible, an element heater wiring for heating the tip of the element may be provided in the discharge element.
However, when an element heater wiring for heating the tip of the element is provided in the discharge element, an induced current flows through the element heater wiring due to discharge at the discharge electrode body. For this reason, in the control circuit that controls the fine particle sensor, the ground potential connected to one end of the element heater wiring fluctuates, so that noise may be superimposed on the output signal of the fine particle sensor.

Therefore, in this fine particle sensor, a shield electrode layer is provided between the element heater wiring and the discharge electrode body in the discharge element. The shield electrode layer is electrically connected to the conductive seal body and is set to the first potential, and electromagnetically shields between the element heater wiring and the discharge electrode body.
As a result, the induced current caused by the discharge at the discharge electrode body is suppressed from flowing to the element heater wiring, and the fluctuation of the ground potential and the accompanying superposition of noise on the output signal of the particle sensor are suppressed.
In addition, the shield electrode layer can be conducted to the conductive sealing body, and the shield electrode layer can be set to the first potential. For this reason, it is not necessary to provide wiring for supplying the first potential to the shield electrode layer of the discharge element in the fine particle sensor so that the shield electrode layer has the first potential.

  Furthermore, in the fine particle sensor described above, the discharge element has a shield electrode pad formed on the outer surface of the sealed portion and is electrically connected to the shield electrode layer, and the shield electrode layer includes the shield electrode pad. It is preferable that the fine particle sensor is connected to the conductive seal body through the gap.

  In this fine particle sensor, by providing a shield electrode pad conducting to the shield electrode layer on the outer surface of the sealed portion, the shield electrode layer can be easily brought to the first potential by being easily conducted to the conductive sealing body. In addition, since the conductive seal body is connected by the shield electrode pad having the spread, the shield electrode pad, that is, the shield electrode layer, and the conductive seal body can be reliably connected.

  Alternatively, in the fine particle sensor described above, the shield electrode layer has an extending portion that extends to the outer surface of the discharge element, and the shield electrode layer is formed on the conductive sealing body by the extending portion. A fine particle sensor formed by connection is preferable.

In this fine particle sensor, the shield electrode layer itself has an extended portion, and since this extended portion is connected to the conductive seal body, it is necessary to provide a via or the like connected to the shield electrode layer in the discharge element. The shield electrode layer can be connected to the conductive seal body with a simple structure.
In addition to the extending portion extending to the outer surface of the sealed portion, a shield electrode pad connected to the extending portion is provided on the outer surface of the sealed portion, and this shield electrode pad is also connected to the conductive seal body. You may do it.

  It is a particulate sensor given in any 1 paragraph of the above-mentioned, Comprising: The front end side part of the front end side among the surrounding members, the conductive seal object, and the tube base end of the base end side among the gas intake and exhaust pipe A cylindrical insulating spacer made of an insulating ceramic is provided on the outer side in the radial direction of the side portion, and the conductive sealing body is hermetically adhered to the inner peripheral surface of the insulating spacer, and the conductive sealing body is interposed therebetween. The tip side portion of the surrounding member and the tube base end side portion of the gas intake / exhaust pipe are preferably fine particle sensors fixed to the insulating spacer.

In this fine particle sensor, the inner peripheral surface of the insulating spacer and the conductive seal body are also tightly sealed, and the inner side of the insulating spacer is hermetically sealed between the base end side and the distal end side by the conductive seal body. Can be sealed.
In addition, a particulate sensor in which the front end side portion of the surrounding member and the tube base end side portion of the gas intake / discharge pipe are fixed to the insulating spacer can be configured through a conductive seal body having a simple configuration made of conductive glass.

  Further, in the fine particle sensor described above, the insulating spacer has a stepped spacer stepped portion projecting radially inward, and the tube proximal end portion of the gas intake / exhaust pipe is more than the proximal end side. A stepped shape with a reduced diameter on the distal end side, a tube stepped portion that is locked to the spacer stepped portion, and a tube proximal end portion that is positioned on the proximal end side with respect to the tube stepped portion and includes an edge on the proximal end side, The conductive seal body may be a fine particle sensor that is in contact with the tube base end.

In this particulate sensor, since the conductive seal body is in contact with the tube base end of the gas intake / exhaust pipe, the gas intake / exhaust pipe is surely set to the first potential via the conductive seal body. Can do.
The conductive seal body is in contact with the tube base end of the gas intake / exhaust pipe from the outside in the radial direction, the form in contact with the tube base end from the inside in the radial direction, the tube base end in the radially outside and The form etc. which contact from both inside can be employ | adopted.

  Further, the above-mentioned particulate sensor, which is made of an insulating ceramic, has a stepped holder step portion that is reduced in diameter on the outer peripheral surface from the proximal end side and locked to the tube step portion of the gas intake / discharge pipe. And an insertion hole through which an element insertion portion between the element tip portion and the sealed portion of the discharge element is inserted, the discharge element is held in the insertion hole, and the conductive sealing body A fine particle sensor including an element holder that comes into contact with the tip from the tip side is preferable.

  In this fine particle sensor, the holder step of the element holder is locked to the tube step of the gas intake / discharge pipe. Since the tube step portion of the gas intake / discharge pipe is locked to the spacer step portion of the insulating spacer, the element holder is indirectly locked to the insulating spacer. In addition, since the element holder is in contact with the conductive seal body from the front end side, the element holder can reliably prevent the conductive seal body from moving toward the front end side in the insulating spacer.

  Furthermore, in the particulate sensor according to any one of the above, the surrounding member is made of metal and has a bottomed cylindrical shape with a closed tip bottom on the tip side, and the discharge element is inserted into the tip bottom. And an inner cylinder that surrounds the element base end side portion of the discharge element from the outside in the radial direction, and the tip bottom portion of the inner cylinder is in contact with the conductive seal body from the base end side. It is better to use a fine particle sensor.

  In this particulate sensor, the surrounding member has an inner cylinder including the bottom of the tip, and by surrounding the element base end side portion of the discharge element from the radially outer side with the inner cylinder, a Faraday cage can be configured. Since the tip bottom part of this is in contact with the conductive seal body, the inner cylinder and the conductive seal body can be appropriately conducted, and the conductive seal body can be set to the first potential.

  Another aspect of the present invention for solving the above-described problem is that a measurement target gas containing fine particles is circulated and attached to a metal vent pipe having a ground potential, and the fine particles in the measurement target gas are detected. A method for manufacturing a fine particle sensor, comprising: a gas intake / exhaust tube that discharges a gas to be measured, which is a part of the gas to be measured, into the inside thereof; and a discharge different from the ground potential, comprising an insulating ceramic. A discharge element having a discharge electrode body to be an electric potential, located at a distal end side of the discharge element and disposed in the gas intake / exhaust pipe, between the discharge electrode body and the gas intake / exhaust pipe The tip of the element that charges the fine particles in the gas to be measured by the discharge of the gas, and the sealed object that is located on the base end side of the tip of the element and in which the discharge electrode body is disposed and insulated from the outer surface Part, having a discharge A first potential different from the ground potential and the discharge potential, and a surrounding member surrounding the base end side of the base end side of the sealed portion of the discharge element, and conductive glass A conductive sealing body that is electrically connected between the surrounding member and the gas intake / exhaust pipe, and is in close contact with the outer surface of the sealed portion of the discharge element and hermetically sealed. A sealing body forming step of forming the conductive sealing body by bringing the softened conductive glass into close contact with the outer surface of the sealed portion of the surrounding member, the gas intake and exhaust pipe, and the discharge element; A method of manufacturing a fine particle sensor is preferable.

  According to this manufacturing method, it is easy to form a fine particle sensor in a state where the conductive seal body is reliably conducted to the surrounding member and the gas intake / discharge pipe and the conductive seal body is in close contact with the sealed portion of the discharge element. be able to.

It is explanatory drawing concerning the embodiment and modification 1-3, and the state which applied the particulate sensor to the exhaust pipe of the engine mounted in the vehicle. It is a longitudinal cross-sectional view of the fine particle sensor which concerns on embodiment and modification 1-3. It is a longitudinal cross-sectional view in the longitudinal cross section parallel to FIG. 2 which expands and shows the connection of the discharge element in a separator among the fine particle sensors which concern on embodiment and modification 1-3. It is a longitudinal cross-sectional view in the longitudinal cross section orthogonal to FIG. 2 of the fine particle sensor which concerns on embodiment and modification 1-3. It is a disassembled perspective view which shows the structure of the fine particle sensor which concerns on embodiment and modification 1-3. Of the particulate sensor according to the embodiment, (6A) is a perspective view showing the form of the discharge element, and (6B) is an exploded perspective view showing the structure of the discharge element. It is explanatory drawing which shows the circuit structure of the fine particle detection system using a fine particle sensor. It is explanatory drawing which showed typically the mode of intake and discharge | emission of exhaust gas in the fine particle sensor which concerns on embodiment and modification 1-3. It is explanatory drawing explaining the sealing body formation process among the manufacturing methods of the fine particle sensor which concerns on embodiment and modification 1-3. (10A) and (10B) are perspective views showing the configuration of the discharge element, and (10C) are exploded perspective views showing the structure of the discharge element, among the particulate sensors according to the first modification. (11A) is a perspective view showing the form of the discharge element, (11B) is a partially enlarged perspective view showing the form near the sealed portion of the discharge element, and (11C) is a discharge. It is a disassembled perspective view which shows the structure of an element. Among the fine particle sensors according to the modified embodiment 3, (12A) is a perspective view showing the form of the discharge element, (12B) is a partially enlarged perspective view showing the form near the sealed portion of the discharge element, and (12C) is the discharge. It is a disassembled perspective view which shows the structure of an element.

(Embodiment)
Hereinafter, the particle sensor 10 and the particle detection system 1 according to the present embodiment will be described with reference to the drawings. FIG. 1 is an explanatory diagram for explaining a state in which the particulate sensor 10 is applied to the exhaust pipe EP of the engine ENG mounted on the vehicle AM. FIG. 2 is a longitudinal sectional view of the particle sensor 10 according to the embodiment. FIG. 3 is an enlarged longitudinal sectional view parallel to FIG. 2 showing the connection between the discharge element 60 and the discharge potential cable 82 and the element heater lead wires 84 and 86 in the separators 75 and 76 in the fine particle sensor 10. FIG. FIG. 4 is a longitudinal sectional view of the particle sensor 10 cut at a position shifted by 90 ° around the axis AX from FIG. FIG. 5 is an exploded perspective view of the particle sensor 10. FIG. 6 is a perspective view and an exploded perspective view of the discharge element 60 in the fine particle sensor 10. FIG. 7 is an explanatory diagram showing a circuit configuration of the control device 100 used in the particulate detection system 1. FIG. 8 is an explanatory view schematically showing the state of intake and exhaust of the exhaust gas EG in the particulate sensor 10. FIG. 9 is an explanatory diagram for explaining a sealing body forming step in the method for manufacturing the fine particle sensor 10.

  In this specification, as shown in FIG. 2 and the like, the protector 31 (gas intake / exhaust) in the axial direction GH (the direction in which the axis AX extends, the vertical direction in FIG. 2) along the axis AX of the particulate sensor 10 is shown. The side where the tube is disposed (downward in FIG. 2) is the tip side GS, and the side (upper side in FIG. 2) from which the electric wire 165 and the like on the opposite side extends is the base end side GK. In addition, the radially outward direction (leftward and outward in FIG. 2) with respect to the axis AX is defined as the radially outward DO, and the inward direction (leftward and rightward in FIG. 2) is defined as the radially inner DI.

  As shown in FIG. 1, the particle detection system 1 (hereinafter also simply referred to as the system 1) of the present embodiment includes a particle sensor 10 and a control device 100 that controls the particle sensor 10. Among these, the particulate sensor 10 is attached to an exhaust pipe EP (venting pipe) of an engine ENG (internal combustion engine) mounted on the vehicle AM, and soot in exhaust gas EG (measurement target gas) flowing through the exhaust pipe EP. Fine particles S are detected. Specifically, the particulate sensor 10 is fixed to a metal exhaust pipe EP, and a part of the tip side GS is disposed in the exhaust pipe EP and exposed to the exhaust gas EG (see FIG. 8).

  The control device 100 is connected to the fine particle sensor 10 via a discharge potential cable 82, element heater lead wires 84 and 86, and spacer heater lead wires 92 and 94 (see FIGS. 1 to 4 and 7). The discharge potential cable 82 is a coaxial cable, and the discharge potential lead 82L of the core wire (center conductor) is set to the discharge potential DV (see FIG. 7). On the other hand, the element heater lead wires 84 and 86 and the spacer heater lead wires 92 and 94 are thin and single-core insulation coated wires. The discharge potential cable 82 has a chassis ground potential CGND and is surrounded by a braided tube 23 in which a thin metal wire is knitted into a cylindrical shape.

  As shown in FIG. 7, the control device 100 roughly includes an ion source power supply circuit 110 and a measurement control circuit 120. Among these, the ion source power supply circuit 110 has a first output end 111 that is set to the sensor ground potential SGND and a second output end 112 that is set to the discharge potential DV. The second output end 112 is connected to a discharge potential lead wire 82 </ b> L that is a core wire of the discharge potential cable 82. The discharge potential DV is a positive high potential (for example, 1 to 2 kV0-p) half-wave rectified with the sensor ground potential SGND as a reference. The ion source power supply circuit 110 constitutes a constant current power supply in which the magnitude of the output current is feedback-controlled and the effective value becomes a predetermined current value (for example, 5 μA). The ion source power supply circuit 110 generates a discharge potential DV to be applied to a discharge electrode body 62 of a discharge element 60 described later (see FIGS. 2 and 6).

  On the other hand, the measurement control circuit 120 includes a signal current detection circuit 140, an element heater control circuit 150, and a spacer heater control circuit 160. Among these, the signal current detection circuit 140 has a first input terminal 141 and a second input terminal 142 that are set to the sensor ground potential SGND, and is between the first input terminal 141 and the second input terminal 142. The signal current Is flowing through is detected. The sensor ground potential SGND is higher than the chassis ground potential CGND (ground potential) by an offset voltage Voffset (specifically, 0.5 V).

  The element heater control circuit 150 is a circuit that controls energization to an element heater wiring 64 built in a discharge element 60 described later by PWM control (see FIG. 6). The element heater control circuit 150 has a first output end 151 connected to the element heater lead wire 84 and a second output end 152 connected to the element heater lead wire 86. Note that the second output end 152 and the element heater lead wire 86 are electrically connected to the chassis ground potential CGND. Further, the first output end 151 and the element heater lead wire 84 are set to the element heater potential EHV.

  The spacer heater control circuit 160 is a circuit that controls energization of a spacer heater layer 41HT of an insulating spacer 41 (described later) by PWM control (see FIG. 4). The spacer heater control circuit 160 has a first output end 161 connected to the spacer heater lead wire 92 and a second output end 162 connected to the spacer heater lead wire 94. Note that the second output end 162 and the spacer heater lead 94 are electrically connected to the chassis ground potential CGND. The first output terminal 161 and the spacer heater lead wire 92 are set to the spacer heater potential SHV.

  The ion source power supply circuit 110 is surrounded by an inner circuit case 170 having a sensor ground potential SGND. The first output end 111 of the ion source power supply circuit 110, the first input end 141 of the signal current detection circuit 140, and the secondary side iron core 131B of the insulating transformer 130 are electrically connected to the inner circuit case 170.

  The first output end 111 of the ion source power supply circuit 110 is electrically connected to the outer conductor 82D of the discharge potential cable 82.

  The insulating transformer 130 is a transformer in which the primary side and the secondary side are insulated, and the iron core 131 includes a primary side iron core 131 </ b> A that winds the primary side coil 132 and a secondary side iron core that winds the secondary side coil 133. It is configured separately from 131B. Of these, the primary iron core 131A is electrically connected to the chassis ground potential CGND. On the other hand, as described above, the secondary iron core 131B is electrically connected to the sensor ground potential SGND (the first output end 111 of the ion source power supply circuit 110).

  Furthermore, the measurement control circuit 120 including the signal current detection circuit 140, the element heater control circuit 150, and the spacer heater control circuit 160, the ion source power supply circuit 110, the inner circuit case 170, and the insulation transformer 130 are connected to the chassis ground potential CGND. The outer circuit case 180 is surrounded. Further, the second input terminal 142 of the signal current detection circuit 140, the second output terminal 152 of the element heater control circuit 150, the second output terminal 162 of the spacer heater control circuit 160, and the primary iron core 131A of the insulating transformer 130 are The chassis ground potential CGND is connected to the outer circuit case 180. In addition, the outer circuit case 180 is electrically connected to the braided tube 23 surrounding the discharge potential cable 82.

  The measurement control circuit 120 has a built-in regulator power supply PS that supplies a predetermined DC voltage. This regulator power supply PS is connected to an external battery BT mounted on the vehicle AM through a power supply wiring BC, and is driven by this battery BT. One end of the battery BT is connected to the chassis ground potential CGND. The measurement control circuit 120 includes a microprocessor 122 and can communicate with an electronic control unit ECU that controls the engine ENG via the communication line CC. Thereby, signals such as the measurement result (the magnitude of the signal current Is) of the signal current detection circuit 140 described above can be transmitted to the electronic control unit ECU.

  Further, part of the electric power input from the external battery BT to the measurement control circuit 120 through the regulator power supply PS is distributed to the ion source power supply circuit 110 through the insulation transformer 130. In the isolation transformer 130, a primary coil 132 that forms part of the measurement control circuit 120, a secondary coil 133 that forms part of the ion source power circuit 110, and an iron core 131 (primary iron core 131A, secondary coil). The side iron cores 131B) are electrically insulated from each other. For this reason, while the electric power is distributed from the measurement control circuit 120 to the ion source power supply circuit 110, the electric insulation between them can be maintained.

Next, the particle sensor 10 of the present embodiment will be described with reference to FIGS.
As shown in FIGS. 2 to 4, the particle sensor 10 has a straight bar shape extending in the axial direction GH. As will be described later, the fine particle sensor 10 generates ions CP by air discharge (specifically, corona discharge) between the protector 31 and the needle-like electrode portion 62D protruding from the element tip portion 60S. The discharge element 60 is provided. In addition, the fine particle sensor 10 includes a sensor ground member 30 that secures electrical insulation from the discharge element 60 and holds the discharge element 60 while being surrounded by a conductor having a sensor ground potential SGND to form a Faraday cage. Further, outside the sensor ground member 30, while securing electrical insulation, they are enclosed and held, and attached to the exhaust pipe EP, so that the chassis ground potential CGND is different from the sensor ground potential SGND. A chassis ground member 20 is provided.

  In the present embodiment, the sensor ground member 30 includes a protector 31, a conductive seal body 37, a second inner cylinder 38, and a first inner cylinder 39, which will be described later. The chassis ground member 20 includes a mounting bracket 21, an outer cylinder 22, a braided tube 23, and a braid holding bracket 24, which will be described later.

  Specifically, the fine particle sensor 10 includes a cylindrical mounting bracket 21 at its tip side GS. The mounting bracket 21 has a tool engaging portion 21H that bulges outward in the radial direction and forms an external hexagonal shape. Further, on the tip side GS from the tool engaging portion 21H, there is a cylindrical wall portion 21W that surrounds the outer periphery of a protector 31 (gas intake / exhaust pipe) described later. A male screw portion 21N for fixing the particulate sensor 10 to the exhaust pipe EP is formed on the outer periphery of the cylindrical wall portion 21W. Accordingly, the particulate sensor 10 is fixed to the exhaust pipe EP using a male screw portion 21N of the mounting bracket 21 and a metal mounting boss (not shown) separately installed on the exhaust pipe EP. For this reason, the mounting bracket 21 is set to the same chassis ground potential CGND as that of the exhaust pipe EP.

Further, a metal-made cylindrical outer cylinder 22 is fixed to the proximal end side GK of the mounting bracket 21. Specifically, the distal end portion 22S of the outer cylinder 22 is fitted on the base end portion 21K of the mounting bracket 21 and laser-welded, so that the mounting bracket 21 and the outer cylinder 22 are integrated.
The base end portion 22K on the base end side GK of the outer tube 22 is configured to have a diameter smaller than that of the front end portion 22S, and a grommet 46 made of insulating rubber is fitted into the tube via a braided tube 23 formed of a metal wire. The braided holding metal fitting 24 is covered and crimped, and the grommet 46, the braided tube 23, and the braided holding metal fitting 24 are held on the base end portion 22 </ b> K of the outer cylinder 22.

For this reason, by attaching the mounting bracket 21 of the fine particle sensor 10 to the exhaust pipe EP, the mounting bracket 21 and the outer cylinder 22, the braided tube 23, and the braided holding bracket 24 that are in conduction with the mounting bracket 21 are set to the chassis ground potential CGND.
The grommet 46 is inserted with a discharge potential cable 82, element heater lead wires 84 and 86, and spacer heater lead wires 92 and 94.

  In addition, the radially inner DI of the mounting bracket 21 is made of an insulating ceramic via an insulating holder 42 made of an insulating ceramic, a talc green compact 43, an insulating sleeve 44 made of an insulating ceramic, and a wire packing 45. A cylindrical insulating spacer 41 is held. The insulating holder 42, the talc green compact 43, the insulating sleeve 44, and the wire packing 45 are compressed in the axial direction GH by crimping and bending the proximal end 21KK of the mounting bracket 21 to the radially inner side DI.

Further, in the radially inner DI of the outer cylinder 22, in addition to the insulating spacer 41, the cylindrical first inner cylinder 39 and the second inner cylinder that surround the element base end side portion 60 </ b> K of the base end side GK of the discharge element 60. A cylinder 38 is arranged.
Although not described in detail, the insulating spacer 41 is an insulating spacer with a heater in which a spacer heater layer 41HT is formed on the outer peripheral surface, and the tip portion 41S of the insulating spacer 41 can be heated by energization.

In the insulating spacer 41, the discharge element 60 is held via the protector 31, the conductive seal body 37, the second inner cylinder 38, the element holder 71, and the like.
Among these, the discharge element 60 is a multilayer wiring board having a discharge electrode body 62 made of an insulating ceramic and having a discharge potential DV different from the sensor ground potential SGND and the chassis ground potential CGND. The discharge element 60 is located on the distal end side GS and is disposed in the protector 31. The discharge element 60 generates ions CP by discharge between the discharge electrode body 62 (specifically, the needle electrode portion 62D) and the protector 31. It has an element tip 60S that is generated and charges the fine particles S in the measurement gas SG. In addition, the discharge electrode body 62 (specifically, the discharge wiring 62L) is located inside and located on the base end side GK of the element front end portion 60S, and has a sealed portion 60C that is insulated from the outer surface 60CS. (See FIGS. 2, 4 and 6).

On the other hand, the protector 31 protects the element tip portion 60S of the discharge element 60 from water droplets and foreign matters, and converts the measured gas SG, which is part of the exhaust gas EG flowing through the exhaust pipe EP, to the element tip portion of the discharge element 60. It has a role to guide around 60S. The protector 31 has a cylindrical shape made of metal and is disposed on the tip side GS of the fine particle sensor 10. The protector 31 takes in the gas to be measured SG from the gas inlet 32I into the internal space K and then discharges it from the gas outlet 32O. In addition, the site | part of the front end side GS of the protector 31 becomes the taper-shaped taper part 32c which diameter-reduces as it goes to the front end side GS.
Further, the first inner cylinder 39 and the second inner cylinder 38 are set to the sensor ground potential SGND because the cable connecting portion 39C of the first inner cylinder 39 is connected to the outer conductor 82D. The element base end side portion 60K on the base end side GK with respect to the sealed portion 60C is surrounded.
Further, the conductive sealing body 37 is made of conductive glass, is in contact with the second inner cylinder 38 and the protector 31, and is in close contact with the outer surface 60CS of the sealed portion 60C of the discharge element 60. The element 60 is hermetically sealed.

Thus, in the fine particle sensor 10, the conductive sealing body 37 made of conductive glass surrounds the outer surface 60CS of the sealed portion 60C of the discharge element 60 and is tightly adhered. For this reason, the discharge element 60 is airtightly held by the conductive seal body 37 in the sealed portion 60C.
In addition, the conductive sealing body 37 is made of conductive glass, and is electrically connected between the second inner cylinder 38 that is set to the sensor ground potential SGND and the protector 31 via the first inner cylinder 39. For this reason, in order to set the protector 31 to the sensor ground potential SGND, there is no need for a metal block-like member such as a metal shell that conducts between the first inner cylinder 39 or the second inner cylinder 38 and the protector 31, and a simple configuration. Although it is the structure, it can be set as the fine particle sensor 10 which hold | maintained the discharge element 60 airtight inside.

  Next, the relationship between the insulating spacer 41 and the conductive seal body 37 will be described. The conductive sealing body 37 made of conductive glass is in airtight contact with the cylindrical inner peripheral surface 41 </ b> I of the insulating spacer 41. And, through this conductive sealing body 37, the distal end side portion 38S on the distal end side of the second inner cylinder 38, and the proximal end side portion 31K of the protector 31 located on the proximal end side GK, It is fixed to the insulating spacer 41.

As described above, in the fine particle sensor 10, the inner peripheral surface 41 </ b> I of the insulating spacer 41 and the conductive seal body 37 are also in airtight contact, and the seal between the discharge element 60 and the conductive seal body 37 is compatible. Thus, the gap between the proximal end side GK and the distal end side GS can be hermetically sealed by the conductive sealing body 37 inside the insulating spacer 41.
In addition, the conductive seal body 37 can be used to form the particle sensor 10 having a simple configuration in which the distal end side portion 38S of the second inner cylinder 38 and the tube proximal end side portion 31K of the protector 31 are fixed to the insulating spacer 41.

Further, the insulating spacer 41, the protector 31, and the conductive seal body 37 will be described. The insulating spacer 41 has a stepped spacer step portion 41D that protrudes radially inward DI. On the other hand, in the substantially cylindrical protector 31, the tube base end side portion 31K located on the base end side GK has a stepped tube step portion 31KD whose distal end side GS is smaller in diameter than the base end side GK. It has a tube base end portion 31KK that is located on the base end side GK from the tube step portion 31KD and includes a base end edge 31KF of the base end side GK. The tube step portion 31KD of the protector 31 is locked to the spacer step portion 41D of the insulating spacer 41 from the proximal end side GK toward the distal end side GS. That is, the protector 31 is fixed to the insulating spacer 41.
Moreover, the conductive seal body 37 is in close contact with the tube base end portion 31KK of the tube base end portion 31K of the protector 31 from the base end side GK, the radially inner DI, and the radially outer DO, and is electrically connected to the protector 31. (See FIGS. 2 and 4).

  Thus, in this particulate sensor 10, since the conductive seal body 37 is in contact with the tube base end portion 31KK of the protector 31, the protector 31 is securely connected to the sensor ground potential via the conductive seal body 37. SGND can be used.

The rectangular plate-shaped discharge element 60 is held by an element holder 71 made of an insulating ceramic. The element holder 71 has a stepped holder step portion 71D whose distal end side GS is smaller in diameter than the base end side GK on the outer peripheral surface 71R, and an insertion hole 71H through which the discharge element 60 is inserted. doing. In the insertion hole 71H, the discharge element 60 is surrounded by an element tip 60S projectingly arranged in the protector 31 on the tip side GS from the element holder 71 and the conductive seal body 37 in an airtight manner. An element insertion portion 60P located between the seal portion 60C and the seal portion 60C is inserted. The element insertion portion 60P of the discharge element 60 is held by the element holder 71 by the talc green compact 72 filled in the insertion hole 71H (see also FIG. 6).
Note that the holder step portion 71D of the element holder 71 is locked to the tube step portion 31KD of the protector 31 from the proximal end side GK toward the distal end side GS. In addition, the element holder 71 is in contact with the conductive seal body 37 from the tip side GS and holds the conductive seal body 37.

  As described above, in the fine particle sensor 10, the holder step portion 71D of the element holder 71 is locked to the tube step portion 31KD of the protector 31. Since the tube step portion 31KD of the protector 31 is locked to the spacer step portion 41D of the insulating spacer 41, the element holder 71 is indirectly locked to the insulating spacer 41. Moreover, since the element holder 71 is in contact with the conductive seal body 37 from the front end side GS, it is possible to reliably prevent the conductive seal body 37 from moving to the front end side GS within the insulating spacer 41.

In the fine particle sensor 10 of the present embodiment, the rectangular plate-like discharge element 60 is inserted into the insertion hole 71H of the element holder 71 made of an insulating ceramic, and the recess 71P having a large diameter in the insertion hole 71H is filled. The compressed talc green compact 72 is fixed to the element holder 71.
However, without using the talc green compact 72, the concave portion 71P of the element holder 71 is filled with cement and solidified, or the concave portion 71P of the element holder 71 is also filled with conductive glass forming the conductive sealing body 37, and the element The discharge element 60 may be fixed to the holder 71 and the element holder 71 and the conductive seal body 37 may be coupled.

  Further, the first inner cylinder 39 and the second inner cylinder 38 are made of metal, and the second inner cylinder 38 has a bottomed cylindrical shape in which the tip bottom portion 38SS of the tip side GS is closed. However, the tip bottom 38SS has an insertion hole 38SH through which the discharge element 60 is inserted. The second inner cylinder 38 surrounds the element base end side portion 60K of the discharge element 60 from the radially outer side DO. The distal end bottom portion 38SS of the second inner cylinder 38 is in contact with the conductive seal body 37 from the proximal end side GK.

  As described above, in the fine particle sensor 10, the first inner cylinder 39 and the second inner cylinder 38 have the second inner cylinder 38 including the tip bottom portion 38SS, and the element of the discharge element 60 is formed by the second inner cylinder 38. A Faraday cage can be configured by surrounding the base end side portion 60K from the radially outer side DO. In addition, since the bottom end portion 38SS of the second inner cylinder 38 is in contact with the conductive seal body 37, the second inner cylinder and the conductive seal body 37 are appropriately conducted, and the conductive seal body 37 is connected to the sensor ground. The potential SGND can be set.

  In the second inner cylinder 38, an element sleeve 73 made of an insulating ceramic is disposed in the distal end side portion 38S of the distal end side GS, and is fixed by caulking the distal end side portion 38S. The discharge element 60 is also inserted into the insertion hole 73H of the element sleeve 73 and extends to the proximal end side GK. Further, the base end side GK of the insulating spacer 41 and the second inner cylinder 38 surrounds the element base end side portion 60K of the discharge element 60, and includes an outer separator 74, a lower separator 75, and an upper separator 76 made of insulating ceramic. Is arranged.

  Of these, the outermost separator GS on the most distal side GS is inserted into the insulating spacer 41 and the second inner cylinder 38, and extends to the second inner cylinder 38 and the second inner cylinder 38. It is indirectly locked to the insulating spacer 41 via the base end side GK toward the front end side GS. Further, the separators 74 to 76 are covered by the first inner cylinder 39 or the second inner cylinder 38 from the radially outer side DO, and the upper separator 76 located at the most proximal side GK is the first inner cylinder 39. The base end side GK is also covered.

  The first inner cylinder 39 is provided with a cylindrical cable connection portion 39C protruding to the proximal end side GK, and the discharge potential cable 82 is inserted into the cable connection portion 39C and fixed by crimping. . More precisely, the outer conductor 82D of the discharge potential cable 82 is electrically connected to the first inner cylinder 39 in the cable connection portion 39C of the first inner cylinder 39. Thus, the first inner cylinder 39 is electrically connected to the first output end 111 and the inner circuit case 170 of the ion source power supply circuit 110 of the control device 100 via the outer conductor 82D of the discharge potential cable 82. Thus, the first inner cylinder 39, the second inner cylinder 38, the conductive seal body 37, and the protector 31 are all set to the sensor ground potential SGND, and surround the discharge element 60 with these to form a Faraday cage.

  Next, the structure of the discharge element 60 used in this embodiment will be described with reference to FIG. The discharge element 60 has a rectangular plate shape made of an insulating ceramic. Of the first surface 60A (upper surface in FIG. 6A), the discharge electrode pad 62P is disposed on the proximal side GK from the center and the distal side GS from the center. , A shield electrode pad 63P1 is formed. As shown in FIG. 3, a discharge potential lead wire 82 </ b> L that is a core wire of the discharge potential cable 82 is connected to the discharge electrode pad 62 </ b> P via a discharge potential connection terminal 81. As a result, the discharge electrode body 62 including the discharge electrode pad 62P is set to the discharge potential DV, and energization is controlled by the ion source power supply circuit 110 through the discharge potential cable 82 (see FIG. 7).

  On the other hand, the shield electrode pad 63P1 is formed so as to be positioned on the outer surface 60CS of the sealed portion 60C of the discharge element 60, and the conductive seal body 37 surrounding the outer surface 60CS and tightly adhering thereto. (See FIG. 2). Accordingly, the shield electrode portion 63 including the shield electrode pad 63P1 is set to the sensor ground potential SGND.

  Further, element heater pads 64P1 and 64P2 are formed on the second end surface 60B (lower surface in FIG. 6A) of the discharge element 60 on the base end side GK from the center (see FIG. 6B). As shown in FIG. 3, element heater lead wires 84 and 86 are connected to the element heater pads 64P1 and 64P2 via element heater connection terminals 83 and 85, respectively. Thereby, the element heater wiring 64 including the element heater pads 64P1 and 64P2 is energized and controlled by the element heater control circuit 150 through the element heater lead wires 84 and 86 (see FIG. 7).

  The discharge element 60 includes flat ceramic layers 61A to 61E made of insulating ceramic, and bonding layers 65A to 65D that are interposed between the ceramic layers 61A to 61E and are bonded to each other.

Among these, between the bonding layer 65A and the ceramic layer 61A, in a portion near the front end side GS, a substantially flat plate-like discharge wiring 62L and a discharge element extending from the discharge wiring 62L to the front end side GS Needle-like electrode portions 62D that project like needles from 60 element tip portions 60S are provided. The discharge wiring 62L is electrically connected to the discharge electrode pad 62P provided on the outer surface of the ceramic layer 61A, that is, the first surface 60A of the discharge element 60, through the discharge electrode via 62V provided in the ceramic layer 61A.
As can be easily understood from FIG. 6B, the discharge wiring 62L of the discharge electrode body 62 is not exposed to the outer surface 60CS in the sealed portion 60C of the discharge element 60 and is positioned inside the discharge element 60. doing. For this reason, even if the conductive seal body 37 is formed in close contact with the outer surface 60CS, the discharge wiring 62L of the discharge electrode body 62 does not conduct to the conductive seal body 37, and the two are insulated. .

Further, between the ceramic layer 61E and the bonding layer 65D, two flat plate-like element heater lead wires 64L1 and 64L2 that are parallel to each other and extend in the axial direction GH, and a meander connecting these tip side GSs. The element heater part 64HT which consists of a shape-like wiring is provided. The element heater lead wires 64L1 and 64L2 are respectively connected to element heater pads 64P1 and 64P2 provided on the outer surface of the ceramic layer 61E, that is, the second surface 60B of the discharge element 60, through the element heater vias 64V1 and 64V2 provided in the ceramic layer 61E. Conducted.
The element heater wiring 64 constituted by these prevents foreign particles such as soot from adhering to the element tip portion 60S of the discharge element 60 exposed to the gas to be measured SG, or removes the adhered foreign particles. In order to remove it, the element tip portion 60S is provided to raise the temperature.

As shown in FIG. 5, the element heater connection terminals 83 and 85 to which the element heater lead wires 84 and 86 are connected are in contact with the element heater pads 64P1 and 64P2. As described above, the element heater lead wire 86 is connected to the second output terminal 152 of the element heater control circuit 150 and is set to the chassis ground potential CGND. On the other hand, the element heater lead wire 84 is connected to the first output terminal 151 of the element heater control circuit 150, and is set to the element heater potential EHV (see FIG. 7).
As can be easily understood from FIG. 6B, the element heater lead wires 64L1 and 64L2 of the element heater wiring 64 are also not exposed to the outer surface 60CS in the sealed portion 60C of the discharge element 60. Located inside. For this reason, even if the conductive seal body 37 is formed in close contact with the outer surface 60CS, the element heater lead wires 64L1 and 64L2 of the element heater wiring 64 do not conduct to the conductive seal body 37, Insulated.

  In addition, a flat shield electrode layer 63 </ b> S is provided between the ceramic layer 61 </ b> B and the bonding layer 65 </ b> B near the tip side GS. The shield electrode layer 63S is provided on the outer surface of the ceramic layer 61A, that is, the first surface 60A of the discharge element 60 through the shield electrode vias 63V2 and 63V1 and the shield electrode pads 63P3 and 63P2 provided in the ceramic layers 61B and 61A, respectively. The shield electrode pad 63P1 is electrically connected. The bonding layer 65A is provided with a through-hole 65ATH that includes shield electrode pads 63P3 and 63P2 therein, and the shield electrode pads 63P3 and 63P2 are in contact with each other to be conductive. For this reason, when the conductive seal body 37 is formed in close contact with the outer surface 60CS of the discharge element 60, the shield electrode pad 63P1 conducts to the conductive seal body 37, so that the shield electrode layer 63S, the shield electrode via 63V1, The shield electrode portion 63 composed of 63V2 and the shield electrode pads 63P1, 63P2, 63P3 is electrically connected to the conductive seal body 37 and is set to the sensor ground potential SGND.

As described above, in the fine particle sensor 10 of the present embodiment, the element heater wiring 64 for heating the element tip portion 60S is provided in the element tip portion 60S exposed to the gas to be measured SG among the discharge elements 60. One end (element heater pad 64P2) of the element heater wiring 64 is connected to the chassis ground potential CGND via the element heater lead wire 86.
However, when the element heater wiring 64 is provided in order to heat the element tip portion 60 </ b> S, an induced current flows through the element heater wiring 64 due to the discharge in the discharge electrode body 62. For this reason, in the control device 100 (see FIG. 7) that controls the particle sensor 10, the chassis ground potential CGND connected to one end (element heater pad 64P2) of the element heater wiring 64 fluctuates. Noise may be superimposed on a signal (an output signal from the measurement control circuit 120).

  On the other hand, in this embodiment, as can be easily understood from FIG. 6B, the shield electrode layer 63S at the sensor ground potential SGND includes the discharge wiring 62L of the discharge electrode body 62 and the element heater lead of the element heater wiring 64. It is interposed between the wires 64L1 and 64L2 and the element heater portion 64HT, and electromagnetically shields between the discharge wiring 62L and the element heater lead wires 64L1 and 64L2 and the element heater portion 64HT.

As a result, the induced current caused by the discharge at the discharge electrode body 62 is suppressed from flowing to the element heater wiring 64, and the fluctuation of the chassis ground potential CGND and the output signal of the particulate sensor 10 (the output from the measurement control circuit 120) are accompanied accordingly. Signal) is suppressed from being superimposed with noise.
In addition, the shield electrode layer 63S is conducted to the conductive seal body 37 to be set to the sensor ground potential SGND. Specifically, since the shield electrode pad 63P1 that conducts to the shield electrode layer 63S is provided on the outer surface 60CS of the sealed portion 60C, the shield electrode layer 63S is easily conducted to the conductive seal body 37, and the shield electrode layer 63S is connected to the sensor ground. The potential SGND can be set. Therefore, it is not necessary to provide wiring for supplying the sensor ground potential SGND to the shield electrode layer 63S of the discharge element 60 in the fine particle sensor 10 so that the shield electrode layer 63S is set to the sensor ground potential SGND. Further, since the conductive seal body 37 is connected by the shield electrode pad 63P1 having the spread, the shield electrode pad 63P1 and thus the shield electrode layer 63S can be reliably connected to the conductive seal body 37.

Next, the structure of the protector 31 and the detection of the fine particles S in the fine particle sensor 10 will be described with reference to FIGS. 2, 4, 5, and 8. The protector 31 includes a cylindrical protector body 32 with a narrowed front end GS and a plurality (four in this embodiment) of trap members 33 to 36 housed in the protector body 32.
A plurality of gas intake ports 32I are formed in the base end side GK of the protector 31 (the protector main body 32) in a manner of being arranged at equal intervals in the circumferential direction (see FIG. 5). The gas to be measured SG including the fine particles S is taken into the internal space K of the protector 31 through the gas inlet 32I. The gas inlet 32I is located on the radially inner side DI of the cylindrical wall portion 21W of the mounting bracket 21. Further, a gas discharge port 32O for discharging the taken measurement gas SG is formed at the tip of the protector 31 (the protector main body 32). The gas discharge port 32 </ b> O is a circular opening whose center coincides with the axis AX of the particle sensor 10, and only one gas discharge port 32 </ b> O is provided at the tip of the protector 31.

  In the protector 31 (the protector main body 32), the element tip portion 60S of the discharge element 60 protrudes into the internal space K of the tip side GS relative to the element holder 71. Therefore, when corona discharge (air discharge) is generated between the protector 31 having the sensor electrode potential SGND with the needle electrode portion 62D as the discharge potential DV, ions in which oxygen molecules and the like are ionized in the internal space K. CP occurs. For this reason, when the gas to be measured SG is circulated in the internal space K, the ions CP adhere to the fine particles S in the gas to be measured SG, become charged fine particles SC, and are discharged from the gas discharge port 32O to the exhaust pipe EP. The amount of electricity corresponding to the discharged ions CPH discharged in this way is detected as the signal current Is.

  On the other hand, in order to suppress the discharge of the floating ions CPF that have not adhered to the fine particles S from the gas discharge port 32O, the protector 31 is routed through the protector 31 by the trap members 33 to 36. Is a maze. This is because the floating ions CPF in the measurement gas SG are efficiently attached to the trap members 33 to 36 having the sensor ground potential SGND.

  That is, the trap members 33 to 36 have plate-like portions 33b, 34b, 35b, 36b in which one or a plurality of through holes 33d, 34d, 35d, 36d are perforated, as can be understood from FIGS. Have. In addition, the through holes provided in the adjacent trap members are arranged so as not to overlap each other when viewed in the axial direction GH. For this reason, as shown by the dashed arrows in FIG. 8, when the gas to be measured SG flows through the through holes 33d, 34d, and 35d of the trap members 33 to 35, the gas to be measured SG is trapped from the trap members 34 to 36. The distribution path which advances in contact with the plate-like portions 34b, 35b and 36b is taken. For this reason, the floating ions CPF in the measurement gas SG also easily collide with or be attracted to the plate-like portions 34b to 36b of the trap members 34 to 36 that are set to the sensor ground potential SGND, and the floating ions CPF are discharged from the gas outlet. Exhaust from 32O is suppressed.

  The particle detection system 1 including the particle sensor 10 having such a configuration and the control device 100 connected thereto uses the particle sensor 10 having a simple structure and holding the discharge element 60 in an airtight manner. 1 can be an inexpensive system.

Next, a method for manufacturing the fine particle sensor 10 will be described with reference to FIG.
First, the previously formed discharge element 60 is inserted into the insertion hole 71H of the element holder 71, talc powder is filled in the recess 71P of the element holder 71 and compressed, and the element insertion part 60P of the discharge element 60 is compressed. Temporarily fixed to the holder 71.

  Next, the protector 31 is inserted into the insulating spacer 41, and the tube step portion 31KD of the protector 31 is engaged with the spacer step portion 41D of the insulating spacer 41. Further, the element holder 71 with the discharge element 60 is inserted into the protector 31 so that the holder step portion 71D of the element holder 71 to which the discharge element 60 is temporarily fixed is engaged with the tube step portion 31KD of the protector 31.

Thereafter, the insulating spacer 41 and the like are held so that the protector 31 is positioned below, that is, the insulating spacer 41 and the protector 31 are placed in a position in which the tip side GS faces downward. A predetermined amount of conductive glass powder is charged into the conductive glass powder, and the conductive glass powder charged around the discharge element 60 is compressed toward the tip side GS using a pressing jig (not shown).
Thereby, the outer surface 60CS of the sealed portion 60C on the base end side GK from the element insertion portion 60P in the discharge element 60 is surrounded by the compressed conductive glass powder.
Further, as described above, the tube base end side portion 31K of the protector 31 has the stepped tube step portion 31KD, and is located on the base end side GK with respect to the tube step portion 31KD, and the base end edge of the base end side GK. It has a tube base end 31KK including 31KF. For this reason, the conductive glass powder comes into contact with the tube base end portion 31KK of the protector 31 from the radially outer side DO.

  Separately, the element sleeve 73 is inserted into the distal end side portion 38S of the second inner cylinder 38, the distal end side portion 38S is crimped and deformed, and the element sleeve 73 is fixed in the distal end side portion 38S. The discharge element 60 is inserted into the insertion holes 38SH and 73H of the second inner cylinder 38 with the element sleeve 73, and the tip bottom portion 38SS of the second inner cylinder 38 is applied to the compressed conductive glass powder charged into the insulating spacer 41. Make contact.

Further, as a sealing body forming step, the compressed conductive glass powder charged into the insulating spacer 41 is in close contact with the outer surface 60CS of the sealed portion 60C of the discharge element 60, and the tip bottom portion 38SS of the second inner cylinder 38. And these are inserted in a cylindrical furnace (not shown) in the state which contacted the tube base end part 31KK of the protector 31. Then, the insulating spacer 41 is heated from the outside in the radial direction, the temperature is raised to a temperature slightly higher than the softening point of the conductive glass, the conductive glass powder is melted, and the conductive sealing body 37 made of conductive glass is obtained. Form.
Next, the insulating spacer 41 and the like are taken out from the cylindrical furnace, and a pressing jig (not shown) is used as indicated by an arrow in FIG. 9 while the conductive sealing body 37 is melted (conductive glass is softened). Then, a pressing force FP is applied to the element sleeve 73 downward, that is, toward the distal end GS. And it cools slowly, keeping this pressing force, and the electroconductive sealing body 37 is solidified. Thereby, the conductive sealing body 37 made of conductive glass is brought into close contact with the protector 31, the insulating spacer 41, the element holder 71, the talc green compact 72, the second inner cylinder 38, and the discharge element 60.

  Thus, the conductive seal body 37 is reliably brought into contact with the second inner cylinder 38 and the protector 31 without separately using a mold for forming the conductive seal body 37, and the sealed portion 60 </ b> C of the discharge element 60 is connected. It is possible to easily form the fine particle sensor 10 in a state where the conductive sealing body 37 is tightly adhered.

  In addition, in the above-described sealing body forming step, the conductive sealing body 37 made of conductive glass is formed in a state of being in close contact with the shield electrode pad 63P1 provided in the discharge element 60.

  Therefore, the shield electrode layer 63S can be reliably conducted to the conductive sealing body 37 via the shield electrode pad 63P1, and the shield electrode layer 63S can be reliably set to the sensor ground potential SGND.

  Furthermore, in the sealing body forming step described above, the conductive material is in close contact with both the inner peripheral surface 41I of the insulating spacer 41 and the distal end side portion 38S of the second inner cylinder 38 and the tube proximal end side portion 31K of the protector 31. A seal body 37 is formed.

For this reason, the conductive seal body 37 is also tightly adhered to the inner peripheral surface 41I of the insulating spacer 41, and the proximal end side GK and the distal end side GS are formed by the conductive seal body 37 on the radially inner side DI of the insulating spacer 41. Can be manufactured in a hermetic manner.
Further, the distal end side portion 38S of the second inner cylinder 38 and the tube proximal end side portion 31K of the protector 31 can be easily and reliably fixed to the inner peripheral surface 41I of the insulating spacer 41 via the conductive seal body 37.

  Thus, after forming the electroconductive sealing body 37, the insulating spacer 41 is inserted into the mounting bracket 21, and an annular insulating holder 42 and an annular talc green compact 43 made of talc powder are interposed therebetween. Then, the annular insulating sleeve 44 and the wire packing 45 are inserted, and crimping is performed so that the proximal end 21KK of the mounting bracket 21 is bent inward, and the insulating spacer 41 is held in the mounting bracket 21.

  Next, the outer separator 74 and the lower separator 75 are inserted into the second inner cylinder 38 in this order. Further, a discharge potential connection terminal 81 crimped to the tip of the discharge potential lead wire 82L of the discharge potential cable 82 is disposed at a predetermined position of the lower separator 75, and the discharge potential connection terminal 81 contacts the discharge electrode pad 62P of the discharge element 60. (See FIG. 3). As a result, the discharge potential DV generated at the second output end 112 of the ion source power supply circuit 110 in the control device 100 can be applied to the discharge electrode body 62 of the discharge element 60.

  Next, the upper separator 76 is set on the base end side GK of the lower separator 75, and the element heater connection terminals 83 and 85 crimped to the tips of the element heater lead wires 84 and 86 are arranged at predetermined positions of the upper separator 76, respectively. The element heater connection terminals 83 and 85 are brought into contact with the element heater pads 64P1 and 64P2 of the discharge element 60, respectively (see FIG. 3). As a result, the element heater control circuit 150 in the control device 100 can be applied to the element heater portion 64HT of the element heater wiring 64 of the discharge element 60.

Next, the first inner cylinder 39 is put on the upper separator 76 from the base end side GK, and the overlapping portions in the radial direction of the first inner cylinder 39 and the second inner cylinder 38 are caulked to be integrated.
Further, the periphery of the cable connecting portion 39C of the first inner cylinder 39 through which the discharge potential cable 82 is inserted is caulked to fix the discharge potential cable 82 to the cable connecting portion 39C, and the outer conductor 82D of the discharge potential cable 82. Is electrically connected to the cable connecting portion 39C. Accordingly, the sensor ground member 30 including the first inner cylinder 39 is electrically connected to the sensor ground potential SGND of the first output end 111 of the ion source power supply circuit 110 in the control device 100.

  On the other hand, spacer heater connection terminals 91 and 93 provided at the tips of the spacer heater lead wires 92 and 94 are joined to a spacer heater layer 41HT (a connection pad (not shown) of the insulating spacer 41).

Further, the outer cylinder 22 is externally fitted to the mounting bracket 21 so that the distal end portion 22S of the outer cylinder 22 overlaps the proximal end portion 21K of the mounting bracket 21, and the distal end portion 22S of the outer cylinder 22 is connected to the proximal end portion of the mounting bracket 21. Laser welding to 21K.
Next, the grommet 46 is inserted into the base end portion 22K of the outer cylinder 22, while the braided tube 23 and the braid holding metal fitting 24 are placed on the radially outer side DO of the base end portion 22K of the outer cylinder 22, and the periphery is crimped. As a result, the discharge potential cable 82, the element heater lead wires 84 and 86, and the spacer heater lead wires 92 and 94 in the grommet 46 are held by the grommet 46.

  Thus, the particulate sensor 10 and the particulate detection system 1 connected to the control device 100 are completed by the discharge potential cable 82, the element heater lead wires 84 and 86, the spacer heater lead wires 92 and 94, and the braided tube 23.

(Modification 1)
Next, a particle sensor 210 according to a first modification will be described with reference to FIGS. 10, 2, 4, and 9. The fine particle sensor 210 of the first modification is different from the fine particle sensor 10 of the embodiment in the form of the discharge element 260 (FIG. 10), and the point that the conductive seal body 237 has a two-layer structure (FIG. 2). FIG. 4 and FIG. 9) differ, and the others are the same. Therefore, different portions will be mainly described, and the same portions are denoted by the same reference numerals, and description thereof will be omitted or simplified.

  First, the structure of the discharge element 260 used in the fine particle sensor 210 of the first modification will be described with reference to FIG. The discharge element 260 is a rectangular multi-layer wiring board having the same shape as the discharge element 60 and made of an insulating ceramic. Also in this discharge element 260, the discharge electrode pad 62P having the same shape is formed at the same position as the discharge element 60 of the embodiment. Accordingly, the discharge electrode body 62 including the discharge electrode pad 62P is set to the discharge potential DV, and energization control is performed by the ion source power supply circuit 110 through the discharge potential cable 82 (see FIG. 7). The element heater pads 264P1 and 264P2 are also formed at the same positions as the element heater pads 64P1 and 64P2 in the discharge element 60 of the embodiment, and the element heater wiring 264 including the element heater pads 264P1 and 264P2 is an element heater lead wire. The power supply is controlled by the element heater control circuit 150 through 84 and 86.

However, in the discharge element 60 of the embodiment, the shield electrode pad 63P1 is formed on the first surface 60A (upper surface in FIG. 6A), whereas in the discharge element 260 of the first modification, the first surface 260A is different from the first surface 260A. A shield electrode pad 263P1 is formed on the opposite second surface 260B (the lower surface in FIG. 10A and the upper surface in FIG. 10B).
In addition, like the shield electrode pad 63P1 in the discharge element 60 of the embodiment, the shield electrode pad 263P1 is also formed so as to be positioned on the outer surface 260CS of the sealed portion 260C of the discharge element 260. It is electrically connected to a conductive sealing body 237 that surrounds 260CS and is in airtight contact (see FIG. 2). Therefore, the shield electrode portion 263 including the shield electrode pad 263P1 is also set to the sensor ground potential SGND.

  The structure of the discharge element 260 will be described. The discharge element 260 includes flat ceramic layers 261A to 261E made of insulating ceramic, and bonding layers 265A to 265D that are interposed between the ceramic layers 261A to 261E and are bonded to each other.

  Among these, as in the discharge element 60 of the embodiment, between the uppermost ceramic layer 261A and the bonding layer 265A in FIG. A needle-like electrode portion 62D that extends from the discharge wiring 62L to the tip side GS and protrudes in a needle shape from the element tip portion 260S of the discharge element 260 is provided. The discharge wiring 62L is electrically connected to the outer surface of the ceramic layer 261A, that is, the discharge electrode pad 62P provided on the first surface 260A of the discharge element 260 through the discharge electrode via 62V provided in the ceramic layer 261A.

  On the other hand, between the ceramic layer 261D and the bonding layer 265D that are the second from the bottom, like the element heater wiring 64 of the discharge element 60 of the embodiment, two flat plate linear shapes that are parallel to each other and extend in the axial direction GH. Element heater lead wires 264L1 and 264L2 and an element heater portion 264HT made of meander-like wiring connecting these tip side GS are provided. However, unlike the embodiment, the element heater lead wires 264L1, 264L2 are element heater pads 264P3, 264P4 provided in the through holes 265DTH2, 265DTH3 of the bonding layer 265D, and element heater vias 64V1, provided in the ceramic layer 261E. The element heater pads 264P1 and 264P2 provided on the outer surface of the ceramic layer 261E, that is, the second surface 260B of the discharge element 260 are respectively conducted through 64V2.

  In addition, similarly to the shield electrode layer 63S in the embodiment, a flat rectangular shield electrode layer 263S is provided between the ceramic layer 261B and the bonding layer 265B. However, the shield electrode layer 263S in the first modification has a rectangular flat plate shape extending to the base end side GK as compared to the shield electrode layer 63S in the embodiment.

  The shield electrode layer 263S is provided between the shield electrode vias 263V1, 263V2, 263V3, the shield electrode pads 263P2, 263P3, 263P4 provided in the ceramic layers 261C to 261E, and the bonding layer 265D and the ceramic layer 261E. The shield electrode pad 263P1 provided on the outer surface of the ceramic layer 261E, that is, the second surface 260B of the discharge element 260, is electrically connected through the shield wiring 263L having a substantially flat plate shape. The bonding layers 265B, 265C, and 265D are provided with through-holes 265BTH, 265CTH, and 265DTH1 that include shield electrode pads 263P4, 263P3, and 263P2 inside, respectively, via the shield electrode vias 263V3 and 263V2. Can be connected to each other.

  Therefore, when the conductive seal body 237 is formed in close contact with the outer surface 260CS of the sealed portion 260C of the discharge element 260, the shield electrode pad 263P1 conducts to the conductive seal body 237, and thus the shield electrode layer 263S. , Shield electrode vias 263V1, 263V2, 263V3, shield electrode pads 263P1, 263P2, 263P3, 263P4, and shield electrode part 263 including shield wiring 263L are all electrically connected to conductive seal body 237, and sensor ground potential SGND and Is done.

  Thus, since the shield electrode layer 263S is set to the sensor ground potential SGND and electromagnetically shields between the element heater wiring 264 and the discharge electrode body 62, an induced current due to discharge in the discharge electrode body 62 flows to the element heater wiring 264. Is suppressed, and fluctuation of the chassis ground potential CGND and accompanying noise superposition on the output signal of the particle sensor 210 are suppressed.

  In the discharge element 60 (see FIG. 6) of the above-described embodiment, the discharge wiring 62L of the discharge electrode body 62 to which a high voltage is applied, and the shield electrode pad 63P2 of the shield electrode portion 63 set to the sensor ground potential SGND Since they are close to each other, a short circuit may occur between them.

  On the other hand, in the fine particle sensor 210 of the first modification, as described above, the conductive seal is formed on the second surface 260B of the discharge element 260 opposite to the first surface 260A provided with the discharge electrode pad 62P. A shield electrode pad 263 </ b> P <b> 1 that conducts to the body 237 is provided. The discharge electrode body 62 extends from the discharge wiring 62L toward the first surface 260A (upward in FIG. 10C) by the discharge electrode via 62V and the discharge electrode pad 62P. The layer 263S is configured to extend toward the second surface 260B (downward in FIG. 10C). For this reason, the distance between the discharge electrode body 262 to which a high voltage is applied and the shield electrode section 263 that is set to the sensor ground potential SGND is between the discharge electrode body 62 and the shield electrode section 63 in the discharge element 60 of the embodiment. Therefore, the possibility of a short circuit between them can be reduced.

Next, the structure of the conductive seal body 237 in the particulate sensor 210 according to the first modification will be described. The fine particle sensor 10 according to the above-described embodiment has the conductive sealing body 37 made of conductive glass having a uniform composition.
On the other hand, the conductive seal body 237 according to the particle sensor 210 of the first modification is also the same shape as the conductive seal body 37 according to the embodiment. However, as indicated by broken lines in FIGS. 2, 4 and 9, the conductive seal body 237 is positioned on the first conductive seal body 237A located on the distal end side GS and on the proximal end side GK. It differs from the conductive seal body 37 of the embodiment in that it has a two-layer structure in the axial direction GH with a second conductive seal body 237B made of conductive glass different from the conductive seal body 237A.

Specifically, of the two-layer structure conductive seal body 237, the first conductive seal body 237A on the distal end side GS is made of ceramic in addition to adhesion to the tube base end portion 31KK of the protector 31 made of metal. In order to improve the adhesion between the discharge element 260, the inner peripheral surface 41I of the insulating spacer 41, and the element holder 71, it is made of conductive glass having a relatively low softening point and good adhesion.
On the other hand, the second conductive sealing body 237B on the base end side GK is a shield electrode that is exposed to the tip bottom portion 38SS of the second inner cylinder 38 made of metal and to the outer surface 260CS of the sealed portion 260C of the discharge element 260. In order to improve conductivity with the portion 263 (specifically, the shield electrode pad 263P1), the conductive glass is made of conductive glass having better conductivity than the conductive glass used for the first conductive seal body 237A.

Such a conductive seal body 237 is formed by heating and melting the conductive glass powder and then compressing the same as in the formation of the conductive seal body 37 in the manufacture of the fine particle sensor 10 of the embodiment.
However, with the insulating spacer 41, the protector 31, etc. in a posture in which the tip side GS faces downward, the conductive glass powder is put into the insulating spacer 41 and pressed to form a compressed conductive glass powder. In doing so, first, the conductive glass powder for the first conductive seal body 237A is charged. Thereafter, using a pressing jig (not shown), the conductive glass powder for the first conductive seal body 237A charged around the discharge element 60 is compressed toward the tip side GS. Furthermore, the conductive glass powder for the second conductive seal body 237B is charged, and again using a pressing jig, the two layers of the conductive glass powder are compressed toward the tip side GS, and the compressed conductive powder A glass powder is obtained. Thereafter, similarly to the formation of the conductive seal body 37, the two layers of compressed conductive glass powder that have been compressed are heated and softened, and then compressed to form the conductive seal body 237.

Also in the fine particle sensor 210 of the first modification, the discharge element 260 is held airtight by the conductive seal body 237 in the sealed portion 260C. Moreover, the second inner cylinder 38 and the protector 31 are electrically connected by the conductive seal body 237. For this reason, in order to set the protector 31 to the sensor ground potential SGND, there is no need for a metal block-like member such as a metal shell that conducts between the first inner cylinder 39 or the second inner cylinder 38 and the protector 31, and a simple configuration. Although it is a structure, it can be set as the fine particle sensor 210 which hold | maintained the discharge element 260 airtightly inside.
Further, since the shield electrode layer 263S is set to the sensor ground potential SGND via the shield electrode pad 263P1 conducted to the conductive seal body 237, the sensor ground potential SGND is applied to the shield electrode layer 263S of the discharge element 260 in the fine particle sensor 210. There is no need to provide wiring for supply.
In addition, since the conductive seal body 237 is connected by the shield electrode pad 263P1 having the spread, the shield electrode pad 263P1 and thus the shield electrode layer 263S can be reliably connected to the conductive seal body 237.

(Modification 2)
Next, a particle sensor 310 according to a second modification will be described with reference to FIG. The particulate sensor 310 of the second modification is different from the particulate sensors 10 and 210 of the embodiment and the first modification only in that the form of the discharge element 360 is different, and the others are the same. Therefore, different portions will be mainly described, and the same portions are denoted by the same reference numerals, and description thereof will be omitted or simplified.

  First, the structure of the discharge element 360 used in the particle sensor 310 of the second modification will be described with reference to FIG. The discharge element 360 is a rectangular wiring board having the same shape as the discharge element 60 and made of insulating ceramic. The discharge element 360 also has the same shape of discharge electrode pad 62P at the same position as the discharge element 60 of the embodiment. Accordingly, the discharge electrode body 62 including the discharge electrode pad 62P is set to the discharge potential DV, and energization control is performed by the ion source power supply circuit 110 through the discharge potential cable 82 (see FIG. 7). In addition, element heater pads 64P1 and 64P2 having the same shape are formed at the same position as in the embodiment (see FIG. 6), and the element heater wiring 64 including the element heater pads 64P1 and 64P2 passes through the element heater lead wires 84 and 86. The energization is controlled by the element heater control circuit 150.

However, in the discharge element 60 of the embodiment, the shield electrode pad 63P1 is provided on the first surface 60A (the upper surface in FIG. 6A), and in the discharge element 260 of the first modification, the second surface is opposite to the first surface 260A. A shield electrode pad 263P1 was formed on 260B (the lower surface in FIG. 10A and the upper surface in FIG. 10B).
On the other hand, in the discharge element 360 of the second modification, no shield electrode pad is formed on either the first surface 360A or the second surface 360B (the upper surface and the lower surface in FIG. 11A), and the shield electrode layer 363S extends. The protruding portion 363SE is exposed to the side portion 360CSS that forms the side surface of the discharge element 360 in the outer surface 360CS of the sealed portion 360C of the discharge element 360.

  For this reason, the shield electrode layer 363S of the second modification is electrically connected to the conductive seal body 37 that is hermetically adhered to the outer surface 360CS of the sealed portion 360C of the discharge element 360 in the extending portion 363SE. (See FIG. 2). Therefore, the shield electrode layer 363S is directly set to the sensor ground potential SGND.

  The structure of the discharge element 260 will be described (see FIG. 11). As with the discharge element 60 of the first embodiment, the discharge element 360 is a flat ceramic layer 361A to 361E made of insulating ceramic, and is bonded between the ceramic layers 361A to 361E so as to be interposed therebetween. It has layers 365A-365D.

  11C, between the uppermost ceramic layer 361A and the bonding layer 365A, in a portion near the tip side GS, as in the discharge element 60 of the embodiment, A needle-like electrode portion 62D that extends from the discharge wiring 62L to the tip end GS and protrudes in a needle shape from the element tip portion 360S of the discharge element 360 is provided. The discharge wiring 62L is electrically connected to the discharge electrode pad 62P provided on the outer surface of the ceramic layer 361A, that is, the first surface 360A of the discharge element 360, through the discharge electrode via 62V provided in the ceramic layer 361A.

  Also, between the lowermost ceramic layer 361E and the bonding layer 365D, as in the discharge element 60 of the embodiment, the element heater connecting the two element heater lead wires 64L1 and 64L2 and the tip side GS thereof. Part 64HT is provided. The element heater lead wires 64L1 and 64L2 are respectively connected to element heater pads 64P1 and 64P2 provided on the outer surface of the ceramic layer 61E, that is, the second surface 60B of the discharge element 60, through the element heater vias 64V1 and 64V2 provided in the ceramic layer 61E. Conducted.

  In addition, similarly to the shield electrode layer 63S in the embodiment, a shield electrode layer 363S having a substantially flat rectangular shape is provided between the ceramic layer 361B and the bonding layer 365B. However, in the shield electrode layer 363 </ b> S according to the second modification, a portion included in the sealed portion 360 </ b> C of the discharge element 360 is provided with an extending portion 363 </ b> SE that is wider than other portions.

  The extended portion 363SE of the shield electrode layer 363S is exposed to the side portion 360CSS of the outer surface 360CS in the sealed portion 360C of the discharge element 360 (see FIG. 11B).

  Therefore, when the conductive seal body 37 is formed in close contact with the outer surface 360CS of the sealed portion 360C of the discharge element 360, the extended portion 363SE of the shield electrode layer 363S comes into contact with the conductive seal body 37. Since it conducts (see FIG. 2), the shield electrode layer 363S is set to the sensor ground potential SGND. In the second modification, the shield electrode portion 363 is composed only of the shield electrode layer 363S including the extending portion 363SE.

  Thus, since the shield electrode layer 363S is set to the sensor ground potential SGND and electromagnetically shields between the element heater wiring 64 and the discharge electrode body 62, an induced current due to discharge in the discharge electrode body 62 flows to the element heater wiring 264. Is suppressed, and fluctuation of the chassis ground potential CGND and accompanying noise superposition on the output signal of the particle sensor 310 are suppressed.

  In the fine particle sensor 310 of the second modification, as described above, the extended portion 363SE exposed to the side portion 360CSS is provided instead of the first surface 360A provided with the discharge electrode pad 62P in the discharge element 360. It was. Therefore, the distance between the discharge electrode body 362 to which a high voltage is applied and the shield electrode portion 363 (shield electrode layer 363S) that is set to the sensor ground potential SGND is equal to the discharge electrode body 62 and the shield in the discharge element 60 of the embodiment. Since it is separated from the distance between the electrode part 63, the possibility that a short circuit occurs between them can be reduced.

Also in the particulate sensor 310 according to the second modification, the discharge element 360 is airtightly held by the conductive seal body 37 in the sealed portion 360C. Moreover, the second inner cylinder 38 and the protector 31 are electrically connected by the conductive seal body 37. For this reason, in order to set the protector 31 to the sensor ground potential SGND, there is no need for a metal block-like member such as a metal shell that conducts between the first inner cylinder 39 or the second inner cylinder 38 and the protector 31, and a simple configuration. In spite of the configuration, the fine particle sensor 310 in which the discharge element 360 is hermetically held can be obtained.
Further, since the shield electrode layer 363S is set to the sensor ground potential SGND via the extending portion 363SE that is conducted to the conductive seal body 37, the sensor ground potential SGND is applied to the shield electrode layer 363S of the discharge element 360 in the fine particle sensor 310. There is no need to provide wiring for supply.

  Moreover, in the discharge element 360 of the fine particle sensor 310 of the second modified embodiment, the shield electrode layer 363S itself has an extension part 363SE, and the extension part 363SE is connected to the conductive seal body 37. There is no need to provide vias or the like connected to the shield electrode layer 363S in the discharge element 360, and the shield electrode layer 363S can be connected to the conductive seal body 37 with a simple structure.

(Modification 3)
Next, a particle sensor 410 according to a third modification will be described with reference to FIG. The particle sensor 410 of the third modification is the same as the particle sensor 310 of the second modification except that the discharge element 460 is partially different from the discharge element 360, and the others are the same. Therefore, different parts will be mainly described, and description of similar parts will be omitted or simplified. Moreover, only the different part changes a code | symbol and the same code | symbol is used for the same part.

  That is, in the discharge element 460 in the fine particle sensor 410 according to the third modified embodiment, the position overlapping the extending portion 363SE in the bonding layer 465B positioned under the shield electrode layer 363S is the narrow constricted portion 465BC. Yes. Furthermore, in the ceramic layer 461C located in the lower layer of the bonding layer 465B, a semicircular recess 461CC is provided at a position overlapping the constricted portion 465BC (in the third modification, three on one side). (See FIG. 12C).

For this reason, in the discharge element 460 according to the third modification, like the discharge element 360 according to the second modification, the extended portion 363SE of the shield electrode layer 363S is located on the side of the outer surface 460CS in the sealed portion 460C of the discharge element 460. The part 460CSS is exposed (see FIG. 12B).
For this reason, the shield electrode layer 363S is electrically connected to the conductive seal body 37 that is hermetically in close contact with the outer surface 460CS of the sealed portion 460C of the discharge element 460 in the extended portion 363SE. The layer 463S is directly set to the sensor ground potential SGND.

  Therefore, similarly to the discharge element 360 of the second modification, it is not necessary to provide a via or the like connected to the shield electrode layer 363S in the discharge element 460, and the shield electrode layer 363S can be connected to the conductive seal body 37 with a simple structure.

  In addition, the discharge element 460 of the third modification differs from the discharge element 360 of the second modification in that the width of the bonding layer 465B and the ceramic layer 461C is narrower below the extension portion 363SE of the shield electrode layer 363S. A constricted portion 465BC and a semicircular recess 461CC are provided. For this reason, in the side part 460CSS of the discharge element 460, the extending part 363SE of the shield electrode layer 363S is exposed from the constricted part 465BC and the semicircular hollow part 461CC (see FIG. 12B).

  For this reason, in the discharge element 360 according to the second modification, the discharge according to the third modification is compared to the case where only the end face of the extending portion 363SE of the shield electrode layer 363S is in contact with and conductive with the conductive seal body 37. In the element 460, not only the end face but also the portion exposed from the constricted portion 465BC and the semicircular recess portion 461CC in the extended portion 363SE of the shield electrode layer 363S is in contact with the conductive seal body 37 and becomes conductive. Thus, the extending portion 363SE of the shield electrode layer 363S can be more reliably brought into contact with the conductive seal body 37 and conducted.

In the above, the present invention has been described with reference to the embodiment and the first to third modifications. However, the present invention is not limited to the above-described embodiment and the like, and can be appropriately modified and applied without departing from the scope of the invention. Needless to say, it can be done.
For example, in the embodiment, the shield electrode portion 63 such as the shield electrode layer 63 </ b> S is provided in the discharge element 60, and electromagnetic shielding is performed between the element heater wiring 64 and the discharge electrode body 62. However, when the generated noise is small, the shield electrode portion 63 such as the shield electrode layer 63S may not be provided in the discharge element 60.
Conversely, in order to more reliably perform electromagnetic shielding between the element heater wiring 64 and the discharge electrode body 62, a plurality of shield electrode layers 63S are provided, the shield electrode layer surrounds the discharge wiring 62L of the discharge electrode body 62, and the like. It can also be in the form.

  In the first modified example, the first conductive seal body 237A and the second conductive seal body 237B that overlap in two layers in the axial direction GH using the conductive glass having different characteristics as the conductive seal body 237 are shown. It is good also as a structure which overlaps three or more layers.

Moreover, in the modification 3, although the hollow part 461CC was provided in the ceramic layer 461C at three places on one side, the number of the hollows may be one or a plurality of appropriate numbers. Moreover, you may provide the hollow of the form similar to the constriction part 465BC of the bonding layer 465B as a hollow part in the ceramic layer 461C.
Alternatively, a shield electrode pad is provided at a position overlapping the extension portion 363SE among the side portions 360CSS and 460CSS of the discharge elements 360 and 460 of the modified embodiments 2 and 3, and the conductive seal body 37 is more reliably contacted. You may make it conduct | electrically_connect.

1 Particle Detection System 10, 210, 310, 410 Particle Sensor 30 Sensor Ground Member 31 Protector (Gas Intake / Exhaust Pipe)
31K (Protector's) tube proximal end portion 31KD (Protector's) tube step portion 31KK (Protector's) tube proximal end portion 31KF (Protector's) proximal end (base end side edge)
37,237 Conductive seal body 237A First conductive seal body 237B Second conductive seal body 38 Second inner cylinder (enclosure member, inner cylinder)
38S (second inner cylinder) front end side 38SS (second inner cylinder) front end bottom 38SH (second inner cylinder front end bottom) insertion hole 39 first inner cylinder (enclosure member)
39C (first inner cylinder) cable connecting portion 41 insulating spacer 41I (insulating spacer) inner peripheral surface 41D (insulating spacer) step portion 41HT spacer heater layers 60, 260, 360, 460 Discharge elements 60S, 260S, 360S, 460S (discharging element) element tip 60P, 260P, 360P, 460P (discharging element) element insertion part 60C, 260C, 360C, 460C (discharging element) sealed part 60CS, 260CS, 360CS, 460CS (sealed part) (Outside surface) 360CSS, 460CSS (Outside the outer surface of the part to be sealed) Side part 60K, 260K, 360K, 460K Element base end side part 461CC (of the discharge element) Recessed part 62 (Ceramic layer) Discharge electrode body 62L Discharge Wiring 62D Needle-like electrode portions 63, 263, 363 Shield electrode portion 63S, 62S, 363S Shield electrode layer 363SE (shield electrode layer) extension 63P1, 63P2, 63P3, 263P1, 263P2, 263P3 Shield electrode pad 64, 264 Element heater wiring 64P1, 64P2, 264P1, 264P2, 264P3, 264P4 Element heater pad 64HT, 264HT Element heater part 71 Element holder 71R (Element holder) outer peripheral surface 71D (Element holder) Holder step part 71H (Element holder) insertion hole 82 Discharge potential cable 82L Discharge potential lead 82D Outer conductor 84, 86 Element Heater lead wires 92, 94 Spacer heater lead wire AM Vehicle ENG Engine EP Exhaust pipe (vent pipe)
EG exhaust gas (measurement target gas)
SG Gas to be measured CGND Chassis ground potential (ground potential)
SGND Sensor ground potential (first potential)
DV Discharge potential Is Signal current 100 Control device 110 Ion source power supply circuit 130 Isolation transformer 140 Signal current detection circuit 150 Element heater control circuit 160 Spacer heater control circuit S Fine particle SC Charged fine particle CP Ion CPF Floating ion CPH Discharged ion GH Axial direction GS Tip Side (Axial tip side)
GK Base end side (Axis direction base end side)
DO Radial outside DI Radial inside

Claims (9)

A fine particle sensor for detecting the fine particles in the measurement target gas, in which a measurement target gas containing fine particles is circulated and attached to a metal ventilation pipe having a ground potential,
A gas intake / exhaust pipe that discharges the gas to be measured, which is a part of the gas to be measured, after being taken into the interior of the gas;
A discharge element having a discharge electrode body made of an insulating ceramic and having a discharge potential different from the ground potential,
Located on the distal end side of the discharge element and disposed in the gas intake / exhaust tube, the fine particles in the gas to be measured are charged by the discharge between the discharge electrode body and the gas intake / exhaust tube. Element tip, and
A discharge element having a sealed portion that is located on the base end side of the tip portion of the element and in which the discharge electrode body is disposed inside and insulated from the outer surface;
A first potential different from the ground potential and the discharge potential, and a surrounding member that surrounds the base end side portion of the discharge element, which is closer to the base end side than the sealed portion;
A conductive sealing body that is made of conductive glass, conducts between the surrounding member and the gas intake and discharge pipe, and tightly seals the outer surface of the sealed portion of the discharge element in an airtight manner; A particulate sensor comprising: The fine particle sensor according to claim 1,
The discharge element is
One end of which is connected to the ground potential, and an element heater wiring for raising the temperature of the tip of the element; and
A shield electrode layer that is interposed between the element heater wiring and the discharge electrode body and electromagnetically shields between the two,
The shield electrode layer is a fine particle sensor that is electrically connected to the conductive seal body. The fine particle sensor according to claim 2,
The discharge element is
A shield electrode pad formed on the outer surface of the sealed portion and conducting to the shield electrode layer;
The shield electrode layer is a fine particle sensor which is electrically connected to the conductive seal body through the shield electrode pad. The fine particle sensor according to claim 2,
The shield electrode layer is
Having an extension extending to the outer surface of the discharge element;
The shield electrode layer is a fine particle sensor which is connected to the conductive seal body at the extended portion. The fine particle sensor according to any one of claims 1 to 4,
A tube made of an insulating ceramic, arranged on the radially outer side of the proximal end side of the surrounding end of the surrounding member, the conductive sealing body, and the proximal end of the gas intake / exhaust pipe. Shaped insulating spacers,
The conductive seal body is hermetically adhered to the inner peripheral surface of the insulating spacer,
A fine particle sensor in which the distal end side portion of the surrounding member and the tube proximal end side portion of the gas intake / discharge tube are fixed to the insulating spacer via the conductive seal body. The fine particle sensor according to claim 5,
The insulating spacer is
Has a stepped spacer step protruding radially inward,
The tube proximal end side of the gas intake and discharge tube is
A stepped portion with a diameter reduced from the proximal end side to the proximal end side, a tube stepped portion that is locked to the spacer stepped portion, and
It has a tube base end portion that is located on the base end side from the tube step portion and includes an end edge on the base end side,
The conductive sealing body is
A particulate sensor in contact with the tube base end. The particle sensor according to claim 6,
Made of insulating ceramic,
On the outer peripheral surface, the diameter of the distal end side is smaller than the proximal end side, and a stepped holder step portion that is locked to the tube step portion of the gas intake and discharge pipe, and
Of the discharge element, having an insertion hole through which an element insertion portion between the element tip and the sealed portion is inserted,
Hold the discharge element in the insertion hole,
A fine particle sensor comprising an element holder in contact with the conductive seal body from the front end side. It is a particulate sensor given in any 1 paragraph of Claims 1-7,
The surrounding member is
Made of metal, with a bottomed cylindrical shape with a closed bottom on the tip side,
The bottom of the tip has an insertion hole for inserting the discharge element,
An inner cylinder surrounding the element base end side portion of the discharge element from the radially outer side;
The fine particle sensor, wherein the bottom end of the inner cylinder is in contact with the conductive sealing body from the base end side. A method of manufacturing a fine particle sensor in which a gas to be measured including fine particles is circulated and attached to a metal vent pipe having a ground potential and detects the fine particles in the gas to be measured,
A gas intake / exhaust pipe that discharges the gas to be measured, which is a part of the gas to be measured, after being taken into the interior of the gas;
A discharge element having a discharge electrode body made of an insulating ceramic and having a discharge potential different from the ground potential,
Located on the distal end side of the discharge element and disposed in the gas intake / exhaust tube, the fine particles in the gas to be measured are charged by the discharge between the discharge electrode body and the gas intake / exhaust tube. Element tip, and
A discharge element having a sealed portion that is located on the base end side of the tip portion of the element and in which the discharge electrode body is disposed inside and insulated from the outer surface;
A first potential different from the ground potential and the discharge potential, and a surrounding member that surrounds the base end side portion of the discharge element, which is closer to the base end side than the sealed portion;
A conductive sealing body that is made of conductive glass, conducts between the surrounding member and the gas intake and discharge pipe, and tightly seals the outer surface of the sealed portion of the discharge element in an airtight manner; With
A sealing body forming step of forming the conductive sealing body by bringing the softened conductive glass into close contact with the outer surface of the sealed portion of the surrounding member, the gas intake and exhaust pipe, and the discharge element; Manufacturing method of particulate sensor.

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