JP2018054314A - PM sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a PM sensor in which the support mechanism of a sensor unit is improved.SOLUTION: Provided is a PM sensor comprising: a sensor unit having a case, a porous body contained inside the case and arranged in an exhaust gas passage, a pair of electrodes facing each other across the porous body, and a plurality of heaters, separated from each other in a prescribed direction, for generating heat upon application of electricity; and a support member in contact with a portion between adjacent heaters the outer face of the sensor unit and supporting the sensor unit to the case.SELECTED DRAWING: Figure 6A

Description

  The present invention relates to a PM sensor that detects particulate matter (hereinafter referred to as “PM”) contained in exhaust gas.

  Conventionally, a capacitance PM sensor is known as a sensor that is provided in an exhaust system of an internal combustion engine and detects PM in exhaust gas discharged from the internal combustion engine. The capacitive PM sensor includes a case member having an accommodation space for taking in a part of exhaust gas, and a porous body and at least a pair of electrodes arranged to face each other with the porous body interposed therebetween. The sensor part which has is provided.

  An electrostatic capacitance type PM sensor measures the amount of PM using the fact that the capacitance value between electrodes changes due to PM deposited on a porous body (see, for example, Patent Document 1). The PM sensor described in Patent Document 1 has an electric heater for periodically burning and removing PM deposited on the porous body in order to continuously measure the amount of PM. The electric heater is provided in the sensor unit, and is supported by the case member in a state of being surrounded by the cylindrical holding member together with the porous body and the electrode.

JP 2006-008863 A

  An object of this invention is to provide PM sensor which improved the support structure of the sensor part.

  A PM sensor according to the present invention includes a case, a porous body housed in the case and disposed on an exhaust gas passage, a pair of electrodes facing each other with the porous body interposed therebetween, and a predetermined direction A plurality of heaters that are separated from each other and that generate heat based on energization, and a sensor portion that is in contact with a first portion that is a portion between adjacent heaters on the outer surface of the sensor portion. And at least one support member for supporting the case with respect to the case.

  According to the present invention, temperature unevenness of the porous body when the heater generates heat can be suppressed. Therefore, PM deposited on the porous body can be uniformly incinerated and removed. Moreover, damage to the porous body due to thermal stress can be prevented, and durability of the PM sensor can be improved.

Schematic configuration diagram of an exhaust system to which the PM sensor of the present embodiment is applied Partial sectional view schematically showing a PM sensor of the present embodiment The perspective view which shows a sensor part typically An exploded perspective view schematically showing the sensor unit The top view which shows notionally the state in which the heater is supported by the support member A plan view conceptually showing the structure of the heater AA sectional view of FIG. The figure which shows the temperature distribution of the heater in FIG. 6A BB sectional view of FIG. CC sectional view of FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The embodiment described below is an example, and the present invention is not limited to this embodiment.

  FIG. 1 shows an internal combustion engine 1, an exhaust system 2, and a PM sensor 3 according to the present invention. The internal combustion engine 1 is typically a diesel engine. The exhaust system 2 generally includes an exhaust pipe 5 constituting an exhaust passage 4, an oxidation catalyst 6, and a PM filter 7. The oxidation catalyst 6 is provided upstream of the PM filter 7 in the exhaust passage 4. The PM filter 7 is typically a diesel particulate filter.

  The PM sensor 3 is provided upstream or downstream of the PM filter 7 in the exhaust passage 4. When the PM sensor 3 is provided upstream of the PM filter 7 (more specifically, between the oxidation catalyst 6 and the PM filter 7), the PM sensor 3 typically has a PM accumulation amount in the PM filter 7. Used for estimation of When the PM sensor 3 is provided on the downstream side of the PM filter 7, the PM sensor 3 is typically used for failure determination of the PM filter 7 or the like. FIG. 1 shows an example in which the PM sensor 3 is provided upstream of the PM filter 7. The PM sensor 3 is configured to take a part of the exhaust gas inside, perform a predetermined process on the taken-in exhaust gas, and then discharge the exhaust gas to the exhaust passage 4.

  Next, the PM sensor 3 according to the present embodiment will be described with reference to FIGS. As shown in FIG. 2, the PM sensor 3 includes an attachment part 8, a case member 9, a sensor part 10, and a control part 12.

  2 to 8 shown below, the L axis, the W axis, and the T axis are drawn. The L axis, the W axis, and the T axis indicate the length direction, the width direction, and the height direction of the PM sensor 3, respectively, and the directions are orthogonal to each other.

  Specifically, in the case of the present embodiment, the length direction of the PM sensor 3 coincides with the axial direction of the case member 9 (vertical direction in FIG. 2). Further, the width direction and the height direction of the PM sensor 3 are radial directions of the case member 9 and coincide with two directions orthogonal to each other.

  Furthermore, in the following description, the length direction, the width direction, and the height direction of the PM sensor 3 may be described as a length direction L, a width direction W, and a height direction T, respectively. Moreover, the positive direction side (lower side in FIG. 2) of the length direction L is referred to as the front end side, and the negative direction side (upper side in FIG. 2) is referred to as the rear end side. Moreover, the positive direction side (upper side of FIG. 6A) of the height direction T is called one side, and the negative direction side (lower side of FIG. 6A) is called the other side.

  The attachment portion 8 is for attaching the PM sensor 3 to the boss 13 of the exhaust pipe 5. A through hole that penetrates the exhaust pipe 5 is formed in the boss 13, and a female screw 14 is formed on the inner peripheral surface of the through hole.

  The mounting portion 8 is provided with a head 15 having a hexagonal outer peripheral surface at the rear half (upper half in FIG. 2), and a female screw at the tip half (lower half in FIG. 2). A male screw 16 that can be screwed together is formed. Further, the attachment portion 8 is provided with a through hole 19 into which the conducting wires 17 and 18 (see FIGS. 3A and 3B) drawn from the sensor portion 10 can be inserted.

  The case member 9 includes an outer case 20 and an inner case 21. The outer case 20 has, for example, a cylindrical shape. The front end portion and the rear end portion of the outer case 20 are not closed and are openings having a predetermined inner diameter φ1. The outer case 20 has a rear end portion fixed to the tip end portion of the attachment portion 8.

  The inner case 21 has, for example, a bottomed cylindrical shape. The length of the inner case 21 in the length direction L is larger than the size of the outer case 20 in the length direction L. Further, the outer diameter φ2 of the inner case 21 is smaller than the inner diameter φ1 of the outer case 20.

  In addition, the rear end portion of the inner case 21 is not closed and is an opening portion having a predetermined inner diameter φ3. Furthermore, a plurality of inlets 22 formed of through holes are formed in a portion near the rear end of the inner case 21 in a state of being spaced apart at equal intervals along the circumferential direction of the inner case 21. In FIG. 2, only one inlet 22 is provided with a reference symbol.

  In addition, a bottom 23 is provided at the tip of the inner case 21 and is almost closed. More specifically, at least one outlet 24 formed of a through hole having a smaller diameter than the inner diameter φ3 is formed at the approximate center of the bottom 23.

  The inner case 21 is housed in the inner space 25 of the outer case 20, and the rear end portion is fixed to the distal end portion of the attachment portion 8. In a state where the outer case 20 and the inner case 21 are fixed to the mounting portion 8, the central axes of the outer case 20 and the inner case 21 are coaxially located.

  Furthermore, the distal end portion of the inner case 21 protrudes further toward the distal end side than the distal end edge of the outer case 20. In this state, a cylindrical gap 26 is formed between the outer peripheral surface of the inner case 21 and the inner peripheral surface of the outer case 20.

  The front end of the gap 26 is open, and the outer space 27 on the outer side in the radial direction of the outer case 20 communicates with the gap 26. Further, the rear end portion of the gap 26 communicates with the rear end portion of the inner space 28 of the inner case 21 through the inlet 22.

  In this way, the exhaust gas flowing into the gap 26 from the outer space 27 can flow into the inner space 28 of the inner case 21 through the gap 26. The exhaust gas flowing into the inner space 28 of the inner case 21 flows out to the outer space 27 through the outlet 24 formed in the bottom 23 of the inner case 21. That is, the exhaust gas circulates through the route of the outer space 27 → the gap 26 → the inlet 22 → the inner space 28 of the inner case 21 → the outlet 24 → the outer space 27.

  The sensor unit 10 is supported inside the inner case 21 via a support member 11 and a seal member 11a. A support structure for the inner case 21 of the sensor unit 10 will be described later.

  3A and 3B, the sensor unit 10 includes at least two electrodes 29 (five electrodes 29a to 29e in FIGS. 3A and 3B) and at least one porous body 30 (see FIG. 3A and FIG. 3B). 3A and 4B include four porous bodies 30a to 30d) and at least one heater 31 (five heaters 31a to 31e in FIGS. 3A and 3B).

  The electrode 29 (29a-29e) consists of a substantially rectangular flat conductor extended in the length direction L and the width direction W. The electrodes 29 are arranged in a state in which the electrodes 29 are separated from each other by a predetermined interval in a direction that coincides with the height direction T. And regarding the electrode 29 adjacent to the height direction T, when one electrode 29 is connected to the 1st terminal of the electrostatic capacitance detection circuit (not shown) with which the control part 12 is provided, the other The electrode 29 is connected to a second terminal of a capacitance detection circuit (not shown).

  Specifically, in the case of the sensor unit 10 shown in FIGS. 3A and 3B, the first, third and fifth electrodes 29a, 29c and 29e from one side in the height direction T (upper side in FIGS. 3A and 3B). Is connected to the first terminal via a conducting wire 17.

  In addition, the second and fourth electrodes 29 b and 29 d from one side in the height direction T are connected to the second terminal via the conducting wire 17. In this way, a capacitor is constituted by a pair of electrodes 29 adjacent in the height direction T.

  The porous body 30 (30a-30d) consists of the combination of the some rectangular-plate-shaped partition 32 which consists of an insulator porous ceramic sheet, for example. The partition walls 32 are each formed in a rectangular plate shape that extends in a direction that coincides with the length direction L and that is parallel to the height direction T. The partition walls 32 are arranged in the space between the electrodes 29 adjacent to each other in the height direction T with an interval in the direction matching the width direction W.

  In this way, the space between the electrodes 29 adjacent to each other in the height direction T is partitioned in the width direction W by the plurality of partition walls 32, thereby extending in the length direction L and adjacent to the width direction W. A rectangular parallelepiped cavity 33 and a second rectangular parallelepiped cavity 34 are formed.

  The adjacent first cuboid cavity 33 and second cuboid cavity 34 are adjacent to each other in the width direction W when the rear end side of the first cuboid cavity 33 is closed and the front end side is open. The front end side of the cavity 34 is closed, and the rear end side is open.

  That is, the first rectangular parallelepiped cavity 33 and the second rectangular parallelepiped cavity 34 adjacent to each other in the width direction W are open at opposite ends with respect to the length direction L, and are also closed at opposite ends. Such a relationship applies to all combinations of the first cuboid cavity 33 and the second cuboid cavity 34 as well.

  3A and 3B, the space between the electrodes 29 adjacent to each other in the height direction T is not partitioned in the height direction T by the porous body 30, and is formed into five rectangular parallelepiped cavities only in the width direction W. Partitioned. Moreover, in FIG. 3A and FIG. 3B, in the 1st rectangular parallelepiped cavity 33 and the 2nd rectangular parallelepiped cavity 34, the edge part regarding the closed length direction L is attached | subjected.

  In the present embodiment, the four porous bodies 30 (30a to 30d) are arranged adjacent to each other with respect to the height direction T via the electrode 29 and the heater 31. The porous bodies 30 adjacent to each other in the height direction T have a structural relationship reversed with respect to the length direction L.

  That is, the combination of the first cuboid cavity 33 and the second cuboid cavity 34 adjacent in the height direction T also has the same relationship as the relationship between the first cuboid cavity 33 and the second cuboid cavity 34 adjacent in the width direction W. ing.

  The heater 31 (31a to 31e) is formed by embedding a planar or plate-like conductor in an insulator ceramic sheet 35 (five ceramic sheets 35a to 35e in FIGS. 3A and 3B). Generates heat when energized.

  The heater 31 is stacked on one side (the upper side in FIGS. 3A and 3B) in the height direction T of the electrode 29. In addition, among the heaters 31, the second to fifth heaters 31 b to 31 e from one side with respect to the height direction T have porous bodies 30 (30 a to 30 d) stacked on one side with respect to the height direction T. That is, the heaters 31 b to 31 e are sandwiched between the electrode 29 and the porous body 30.

  On the other hand, in the heater 31a on the most side in the height direction T, the porous body 30 does not exist on one side in the height direction T. That is, the heater 31 a is not sandwiched between the electrode 29 and the porous body 30.

  Next, the configuration of the heater 31 and the support member 11 according to the present embodiment will be conceptually described with reference to FIGS. 4 to 8 conceptually show the configuration of the heater 31 and the support member 11. 4-8, only the one heater 31 in the sensor part 10 is shown, and the electrode 29 and the porous body 30 are abbreviate | omitted. Therefore, the heater 31 in FIGS. 4 to 8 conceptually shows the sensor unit 10.

  As shown in FIGS. 4, 5, 6 </ b> A, and 8, the heater 31 is configured with heater elements 36 (361 to 364) embedded in an insulating ceramic sheet 35. The heater elements 361 to 364 are flat conductors extending in the width direction W, and are made of a metal material such as a tungsten alloy or a nickel alloy. The heater elements 361 to 364 are arranged apart from each other in the length direction L.

  Conductive wires 18 and 18 for supplying electric power to the heater elements 361 to 364 are connected to both ends of the heater elements 361 to 364 in the width direction W. The conducting wires 18, 18 extend in the length direction L, are exposed from the rear end side of the heater 31, and are connected to the control unit 12.

  The support member 11 (111 to 113) is a cylindrical member made of ceramic, for example. The support member 11 is externally fitted to the sensor unit 10 in a region between the heater elements 36 adjacent in the length direction L. More specifically, the support member 11 is externally fitted to the sensor unit 10 so that the distances from the two heater elements 36 adjacent in the length direction L are equal.

  That is, the support member 11 is fitted on the center in the region between the heater elements 36 in the length direction L. Further, the support member 11 is fitted into the inner peripheral surface of the seal member 11 a fitted into the inner case 21. In this way, the sensor unit 10 is supported by the support member 11 inside the case member 9.

  The inner peripheral surface 40 of the support member 11 is defined by both side surfaces (upper and lower side surfaces in FIG. 7) in the height direction T of the sensor unit 10 and both side surfaces (both side surfaces in the left and right direction in FIG. 7) in the width direction W. It has a shape along the outer peripheral surface 44. The outer peripheral surface 41 of the support member 11 has a shape that is slightly larger than the outer peripheral surface 44 of the sensor unit 10.

  The inner peripheral surface 42 of the seal member 11 a has a shape that follows the outer peripheral surface 41 of the support member 11. The outer peripheral surface 43 of the seal member 11 a has a shape that follows the inner peripheral surface of the inner case 21.

  There are gaps 42a to 42d between the outer peripheral surface 44 of the sensor unit 10 other than the portion where the support member 11 is fitted and the inner peripheral surface 42 of the seal member 11a. The gaps 42a to 42d are partitioned by the support member 11 so that the exhaust gas cannot flow.

  In addition, the shape of the support member 11 is set so that the cross-sectional area when cut by a virtual plane parallel to the inner peripheral surface 40 that contacts the sensor unit 10 is larger than the area of the inner peripheral surface 40. Yes. The shape of the support member 11 will be described in more detail with reference to FIG. 6A. FIG. 6A shows the shape of a cross section (A-A cross section in FIG. 4) when the support member 11 is viewed from a direction orthogonal to the length direction L.

  In FIG. 6A, the dimension in the length direction L on the inner peripheral surface 40 where the support member 11 contacts the sensor unit 10 is L1. The dimension in the length direction L of the outer peripheral surface 41 where the support member 11 abuts on the seal member 11a is L2. In the present embodiment, L1 <L2. Further, the dimension in the length direction L of the support member 11 gradually increases from the inner peripheral surface 40 toward the outer peripheral surface 41.

  Returning to FIG. 2, the control unit 12 is an ECU (Electronic Control Unit) or the like, and includes a sensor regeneration control unit 45 and a PM amount deriving unit 46 as functional blocks. Each functional block 45, 46 is realized by, for example, a microcomputer that executes a program.

  The sensor regeneration control unit 45 energizes each heater 31 at a predetermined timing (more specifically, according to the capacitance of each capacitor (that is, the electrode 29 forming a pair)) to make the porous body porous. The PM deposited on the body 30 is burned (that is, sensor regeneration processing is performed).

  The PM amount deriving unit 46 estimates the total PM amount in the exhaust gas in accordance with the amount of change in capacitance during a predetermined period (for example, from the end of the sensor regeneration process to the start of the next sensor regeneration process).

  Since the sensor regeneration process and the estimation of the total PM amount described above are described in detail in Japanese Patent Application Laid-Open No. 2006-008863 and the like, detailed descriptions thereof are omitted here.

  Next, the operation of the PM sensor 3 will be described with reference to FIGS. In FIG. 1, a part of the exhaust gas discharged from the internal combustion engine 1 is taken into the PM sensor 3.

  More specifically, as shown in FIG. 2, the exhaust gas flows into the inner space 28 of the inner case 21 from the inlet 22 through the gap 26. The exhaust gas flows into the second rectangular parallelepiped cavity 34 from the opening on the rear end side of the porous body 30.

  Here, since the end of the second rectangular parallelepiped cavity 34 on the downstream side (front end side) of the exhaust gas passage is closed, the exhaust gas passes through the partition wall 32 and enters the first rectangular parallelepiped cavity 33. Inflow. The first rectangular parallelepiped cavity 33 is closed at the upstream side (rear end side) of the exhaust gas passage, so that the exhaust gas flows into the outer space from the downstream (front end side) opening of the first rectangular parallelepiped cavity 33. To 27.

  As described above, the PM amount deriving unit 46 is based on the amount of change in capacitance (more specifically, the amount of change in a predetermined period) obtained from the capacitor (paired electrode 29) via the lead wire 17. The total PM amount in the exhaust gas discharged from the internal combustion engine 1 is estimated. In addition, the sensor regeneration control unit 45 energizes the heater 31 via the conductor 18 at a predetermined timing, and burns the PM deposited on the porous body 30.

  Next, main actions and effects of the PM sensor 3 according to the present embodiment will be described. According to the PM sensor 3 according to the present embodiment, temperature unevenness in the length direction L during sensor regeneration processing can be suppressed.

  In other words, in the case of the PM sensor 3 according to the present embodiment, the support member 11 for supporting the sensor unit 10 inside the inner case 21 is provided on the outer peripheral surface 44 of the sensor unit 10 with respect to the length direction L. It is fitted only on the part that does not exist.

  By doing so, heat insulation is achieved in a portion where the heater element 36 does not exist, and the temperature distribution in the heater 31 can be made substantially uniform with respect to the length direction L as shown by the solid line in FIG. 6B. In addition, the broken line of FIG. 6B shows the temperature distribution in the heater 31 when the support member 11 is not externally fitted for comparison.

  Further, in the PM sensor 3 according to the present embodiment, the support member 11 is externally fitted to the sensor unit 10 so that the distance in the length direction L from the heater element 36 adjacent in the length direction L is equal. Has been.

  By doing so, the distance from the heater element 36 is long, and the temperature is kept at the portion where the temperature is the lowest in the heater 31, so that the temperature distribution in the heater 31 can be made more uniform. Further, by keeping the heater 31 warm, power consumption for maintaining the heater 31 at a desired temperature can be suppressed.

  In the PM sensor 3 according to the present embodiment, the cross-sectional area when the support member 11 is cut along a virtual plane parallel to the inner peripheral surface 40 in contact with the sensor unit 10 is The dimension in the length direction L of the support member 11 is gradually increased from the inner peripheral surface 40 toward the outer peripheral surface 41 so as to be larger than the area.

  That is, the dimension in the length direction L on the inner peripheral surface 40 where the support member 11 contacts the sensor unit 10 is the dimension in the length direction L at a predetermined position on the outer peripheral side of the surface where the support member 11 contacts the sensor unit 10. Smaller than.

  By doing so, the area of the inner peripheral surface 40 where the support member 11 abuts on the sensor unit 10 can be made as small as possible, and the portion of the sensor unit 10 where the temperature is lowered can be kept warm. Moreover, since the amount of heat that can be accumulated in the support member 11 can be increased, the heat retention effect by the support member 11 can be enhanced, and the temperature decrease in the portion where the heater 31 is not disposed can be more effectively suppressed. It becomes possible.

  Moreover, the following effect | action and effect can be acquired by suppressing the temperature nonuniformity regarding the length direction L of the sensor part 10. FIG.

  If the temperature distribution in the length direction L of the sensor unit 10 is uneven, the amount of PM burned and removed in the regeneration process may be uneven.

  According to the PM sensor 3 according to the present embodiment, it is possible to suppress unevenness in the temperature distribution in the length direction L of the sensor unit 10, and thus suppress unevenness in the amount of PM burned and removed in the regeneration process. Can do. Therefore, PM can be uniformly burned and removed in the regeneration process.

  Further, if the temperature distribution in the length direction L of the sensor unit 10 is uneven, the expansion amount in the length direction L in the insulator ceramic sheet 35 in which the porous body 30 and the heater element 36 are embedded is uneven, Damage such as cracks may occur due to thermal stress.

  According to the PM sensor 3 according to the present embodiment, the unevenness of the temperature distribution in the length direction L of the sensor unit 10 can be suppressed, and thus the length direction L in the porous body 30 and the insulator ceramic sheet 35 can be suppressed. Unevenness of the expansion amount can be suppressed. Therefore, it is possible to prevent the porous body 30 and the heater element 36 from being damaged such as cracks.

  The embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and may be appropriately combined or modified without departing from the spirit of the present invention. Is possible.

  In the sensor unit 10 according to the above-described embodiment, the positional relationship between the electrodes 29 (29a to 29e) and the heater 31 (31a to 31e) in the height direction T can be reversed.

  The heater 31 (31a to 31e) may be provided with at least one heater 31 (any one of the heaters 31a to 31e). In particular, in the case of the present embodiment, it is preferable to apply to a structure in which at least one of the heaters 31a and 31e arranged on both ends in the height direction T exists.

  As shown in FIG. 3A, when the configuration in which the heaters 31 (31 a to 31 e) are stacked in the height direction T is adopted, it is not necessary to apply the configuration of the characteristic portion of the present invention to all the heaters 31. That is, the present embodiment as described above is applied to at least one heater 31 (for example, the heater 31a disposed on the most side in the height direction T) among the plurality of heaters 31 stacked in the height direction T. What is necessary is just to employ | adopt the structure of the heater 31 which concerns on a form.

  Further, the structure of the heater 31 is not limited to the structure shown in FIGS. For example, the number of heater elements 36 constituting the heater 31 may be other than four.

  Further, the shapes of the outer case 20 and the inner case 21 are not limited to the case of the present embodiment described above. For example, as the outer case 20 and the inner case 21, those having a polygonal cross-sectional shape with respect to a virtual plane orthogonal to the central axis can be adopted.

  Further, in the case of the above-described embodiment, the support member 11 is configured in a cylindrical shape continuous over the entire circumference in the circumferential direction of the case member 9, and such a support member 11 is formed on the outer peripheral surface of the sensor unit 10. , And is fitted around the entire circumference in the circumferential direction. However, the support member 11 is not limited to such a configuration.

  For example, the support member 11 is formed as a partial cylinder having a discontinuous portion at one place in the circumferential direction, and a configuration in which only a part in the circumferential direction of the outer peripheral surface of the sensor unit 10 is supported is adopted. You can also. Further, the support member 11 may be divided into a configuration in which the case member 9 (the outer case 20 and the inner case 21) is divided (for example, divided into two) in the circumferential direction.

  Moreover, in this Embodiment, although the sealing member 11a has been arrange | positioned at the outer peripheral side of the supporting member 11, it is not limited to this. For example, the outer peripheral surface 41 of the support member 11 can be brought into contact with the inner peripheral surface of the case member 9 (inner case 21).

  Moreover, in this Embodiment, although it was set as the structure which contact | abuts the outer peripheral surface 41 of all the supporting members 11 (111-113) to the inner peripheral surface 42 of the sealing member 11a, it is not limited to this. For example, a gap may be provided between the outer peripheral surface 41 of some of the support members 11 (for example, 112) and the inner peripheral surface 42 of the seal member 11a.

  Further, in the present embodiment, one support member 11 is disposed in the portion between the heater elements 36 on the outer peripheral surface 44 of the sensor unit 10, but the present invention is not limited to this. For example, a plurality of support members 11 may be disposed between the heater elements 36. Alternatively, the support member 11 may have a shape having a plurality of contact surfaces 40 in the length direction L, and a single support member 11 may support a plurality of locations in the length direction L of the sensor unit 10.

  In the present embodiment, the sensor unit 10 includes a porous body disposed on the exhaust gas passage, at least a pair of electrodes opposed to each other with the porous body interposed therebetween, and a heater. Although the electrostatic capacity type has been described as an example, the present invention is not limited to this. The sensor unit 10 may be, for example, a known electrical resistance type.

  That is, in the present invention, the type of the sensor is not particularly limited, and any sensor of the present invention can be used as long as a heater that burns and removes PM is provided in the sensor part supported through the support member inside the case. Configuration can be applied.

  The PM sensor according to the present invention is suitably used for a vehicle equipped with an internal combustion engine such as a diesel engine or a gasoline engine.

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Exhaust system 3 PM sensor 4 Exhaust passage 5 Exhaust pipe 6 Oxidation catalyst 7 PM filter 8 Attachment part 9 Case member 10 Sensor part 11, 111, 112, 113 Support member 11a Seal member 12 Control part 13 Boss 14 Female screw DESCRIPTION OF SYMBOLS 15 Head 16 Male screw 17, 18 Conductor 19 Through-hole 20 Outer case 21 Inner case 22 Inlet 23 Bottom 24 Outlet 25, 28 Inner space 26 Gap 27 Outer space 29, 29a, 29b, 29c, 29d, 29e Electrode 30, 30a , 30b, 30c, 30d Porous material 31, 31a, 31b, 31c, 31d, 31e Heater 32 Partition 33 First cuboid cavity 34 Second cuboid cavity 35, 35a, 35b, 35c, 35d, 35e Insulator ceramic sheet 36, 361, 362, 363, 364 Heater element 40, 42 Inner peripheral surface 41, 43, 44 Outer peripheral surface 42a, 42b, 42c, 42d Gap 45 Sensor regeneration control unit 46 PM amount deriving unit

Claims (3)

Case and
The porous body housed in the case and disposed on the exhaust gas passage, and the pair of electrodes facing each other with the porous body interposed therebetween, are separated from each other in a predetermined direction and generate heat based on energization. A sensor unit having a plurality of heaters;
At least one support member that contacts the first portion, which is a portion between adjacent heaters, on the outer surface of the sensor portion, and supports the sensor portion with respect to the case;
PM sensor comprising: The dimension in the predetermined direction of the contact surface that contacts the sensor part of the support member is smaller than the dimension in the predetermined direction other than the contact surface.
The PM sensor according to claim 1. The at least one support member is a plurality of support members,
Each of the support members abuts on the different first portions on the outer surface of the sensor unit.
The PM sensor according to claim 1.

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