WO2011074667A1 - Pm sensor - Google Patents

Pm sensor Download PDF

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Publication number
WO2011074667A1
WO2011074667A1 PCT/JP2010/072767 JP2010072767W WO2011074667A1 WO 2011074667 A1 WO2011074667 A1 WO 2011074667A1 JP 2010072767 W JP2010072767 W JP 2010072767W WO 2011074667 A1 WO2011074667 A1 WO 2011074667A1
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Prior art keywords
radiator
amount
wave ratio
standing wave
sensor according
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PCT/JP2010/072767
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French (fr)
Japanese (ja)
Inventor
正 内山
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いすゞ自動車株式会社
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Publication of WO2011074667A1 publication Critical patent/WO2011074667A1/en

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N9/00—Electrical control of exhaust gas treating apparatus
    • F01N9/002—Electrical control of exhaust gas treating apparatus of filter regeneration, e.g. detection of clogging
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N13/00—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00
    • F01N13/008—Mounting or arrangement of exhaust sensors in or on exhaust apparatus
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/14—Introducing closed-loop corrections
    • F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
    • F02D41/1444—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases
    • F02D41/1466—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases the characteristics being a soot concentration or content
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume, or surface-area of porous materials
    • G01N15/06—Investigating concentration of particle suspensions
    • G01N15/0606—Investigating concentration of particle suspensions by collecting particles on a support
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2560/00—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics
    • F01N2560/05—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics the means being a particulate sensor
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2560/00—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics
    • F01N2560/20—Sensor having heating means
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/40—Engine management systems

Definitions

  • the present invention relates to a PM sensor that can accurately detect the amount of PM.
  • a vehicle equipped with an internal combustion engine such as a diesel engine is equipped with a diesel particulate filter (hereinafter referred to as DPF) in the exhaust gas exhaust flow path from the internal combustion engine to the atmosphere.
  • DPF diesel particulate filter
  • Particulate matter such as SOF and SOOT is collected.
  • the DPF is a member that temporarily collects PM in a filter having a honeycomb pore shape (which may be a square pore) mainly made of ceramic.
  • DPF regeneration fuel injection for increasing the exhaust temperature is performed, the exhaust temperature is increased by this fuel injection, the DPF is heated, and the PM collected in the DPF is combusted.
  • the DPF regeneration is performed each time the vehicle travel distance reaches a predetermined value.
  • the amount of PM accumulated in the DPF (the PM amount is also called a PM load and indicates the degree of filter clogging). This is because it is difficult to detect.
  • the PM amount is detected from the pressure difference between the exhaust gas upstream and downstream of the DPF.
  • the PM amount detected from the pressure difference is not accurate.
  • an object of the present invention is to provide a PM sensor that solves the above-described problems and accurately detects the PM amount.
  • a PM sensor includes a radiator installed in an atmosphere through which exhaust from combustion flows, and an oscillation circuit that oscillates at the same frequency as the initial natural frequency of the radiator to generate a signal. And a standing wave ratio detection circuit for detecting a standing wave ratio when a signal from the oscillation circuit is fed to the radiator, and an amount of PM attached to the radiator is estimated from the standing wave ratio. And an estimation circuit.
  • the PM sensor of the present invention may include a heater for burning the PM adhering to the radiator.
  • the heater may burn the PM adhering to the radiator under the condition that there is no PM in the exhaust.
  • the heater may burn PM adhering to the radiator when the standing wave ratio detected by the standing wave ratio detection circuit reaches a threshold value.
  • the heater may burn the PM adhering to the radiator when the amount of PM estimated by the estimation circuit reaches a threshold value.
  • the radiator may be installed in an exhaust pipe extending from the diesel particulate filter to the atmosphere.
  • the radiator may be installed in a diesel particulate filter.
  • the radiator may be a dipole antenna in which two radiating elements are arranged on both sides of the gap.
  • the intensity of the signal output from the oscillation circuit may be a signal intensity at which radio waves do not leak outside the exhaust pipe.
  • the estimation circuit may determine the regeneration timing of the diesel particulate filter from the estimated PM amount.
  • the present invention exhibits the following excellent effects.
  • the PM sensor 1 oscillates at the same frequency as the initial natural frequency of the radiator 2 and the radiator 2 installed in the atmosphere in which the exhaust gas from combustion flows.
  • the generated oscillation circuit 3 the standing wave ratio detection circuit 4 for detecting the standing wave ratio when the signal from the oscillation circuit 3 is fed to the radiator 2, and the standing wave ratio is attached to the radiator 2.
  • an estimation circuit 5 for estimating the PM amount.
  • a DPF 23 is connected to a manifold side exhaust pipe 22 that exhausts exhaust from the internal combustion engine 21, and the radiator of the PM sensor 1 is disposed in the exhaust pipe 24 from the DPF 23 to the atmosphere. 2 is installed.
  • the exhaust pipe 24 is formed in, for example, a cylindrical shape or an elliptical cylindrical shape.
  • the radiator 2 includes two linear radiating elements 2a and 2b having an electrical length of 1 ⁇ 4 wavelength directed in opposite directions on both sides of the gap.
  • the two radiating elements 2a, 2b are arranged perpendicular to the axis of the exhaust pipe 24, and the radiating elements 2a, 2b cross the exhaust flow at right angles so as to face the upstream of the exhaust flow.
  • the radiating elements 2a and 2b may be parallel to the axis of the exhaust pipe 24, or may be in a direction intersecting with the axis of the exhaust pipe 24.
  • the angle formed by the radiating elements 2a and 2b with respect to the exhaust flow is It is not limited.
  • the radiator 2 may be formed by extending a conductor wire in the air, but here, the radiator 2 is formed by providing a copper foil on a rectangular parallelepiped base 2c made of ceramic by printing, bonding or the like.
  • the oscillation circuit 3 oscillates at the same frequency as the initial natural frequency of the radiator 2 known in advance and outputs a signal. Since the oscillation circuit 3 can be realized by a known technique, the details are omitted. It is desirable that the signal intensity be such that unnecessary radio waves do not leak outside the exhaust pipe 24.
  • the signal output from the oscillation circuit 3 is preferably a sine wave that does not include harmonics and has only a fundamental wave.
  • the standing wave ratio detection circuit 4 obtains the standing wave ratio by detecting the traveling wave power and the reflected wave power and calculating a definition formula described later. Since the standing wave ratio detection circuit 4 can be realized by a known technique, the details are omitted.
  • the estimation circuit 5 is a digital arithmetic circuit realized by an ECU (Engine Control Unit), for example.
  • the estimation circuit 5 estimates the amount of PM attached to the radiator 2 from the standing wave ratio, and then determines the regeneration time by estimating the amount of PM accumulated in the DPF 23 from the amount of PM attached to the radiator 2. Alternatively, the regeneration time can be determined from the amount of PM attached to the radiator 2. In these determinations, the relationship between the PM amount adhering to the radiator 2 and the PM amount accumulated in the DPF 23 in advance, or the relationship between the PM amount adhering to the radiator 2 and the regeneration timing of the DPF 23 is examined by experiments, etc. This is realized by setting a determination logic based on the relationship in the estimation circuit 5.
  • the signal (high frequency) from the oscillation circuit 3 is fed to the radiator 2 installed in the exhaust pipe 24. Since the radiator 2 is a half-wave dipole antenna, the natural frequency (also referred to as a natural resonance frequency) f of the radiator 2 is expressed by the equation (1) by the inductance L and the capacitance C of the radiator 2.
  • the standing wave ratio (standing wave ratio; SWR) becomes 1.
  • the standing wave ratio SWR is expressed by Expression (2) using traveling wave power Pf and reflected wave power Pr.
  • the impedance of radiator 2 is 75 ⁇ .
  • the detection of the reflected wave power Pr and the measurement of the standing wave ratio SWR are synonymous.
  • the amount of PM is also estimated from the impedance of radiator 2.
  • the measurement of impedance can be performed by a known technique, similarly to the measurement of the standing wave ratio SWR.
  • the estimation circuit 5 estimates the amount of PM adhering to the radiator 2 from the standing wave ratio SWR obtained by the standing wave ratio detection circuit 4. Since the amount of PM attached to radiator 2 and the impedance of radiator 2 are in a proportional relationship, the amount of PM may be estimated from the impedance of radiator 2. Further, the estimation circuit 5 determines the regeneration timing by estimating the PM amount accumulated in the DPF 23 from the estimated PM amount adhering to the radiator 2. Alternatively, the estimation circuit 5 determines the regeneration time of the DPF 23 based on the estimated amount of PM attached to the radiator 2.
  • the PM sensor 1 radiates from the standing wave ratio SWR when a signal having a predetermined frequency is fed to the radiator 2 installed in the atmosphere of the exhaust flow and a radio wave is radiated. Since the amount of PM adhering to the radiator 2 is estimated, the PM amount is accurately detected, and the PM amount of the DPF 23 is detected based on the detected PM amount of the radiator 2. As described above, the PM amount of the DPF 23 is detected more accurately than that estimated from the pressure difference of the exhaust gas.
  • the PM sensor 1 of the present invention is composed of the radiator 2 and a simple circuit, it is less expensive than the conventional configuration in which the PM amount is detected by a plurality of pressure sensors.
  • the PM sensor 1 of the present invention includes a heater 6 that burns the PM adhering to the radiator 2.
  • the heater 6 may be provided on the base 2c of the radiator 2.
  • the heater 6 is disposed inside the base 2c or on the opposite surface of the radiating elements 2a and 2b.
  • the PM sensor 1 provided with the heater 6 has a current flowing through the heater 6 at an appropriate time, the radiator 2 is heated, and PM adhering to the radiator 2 is burned and removed.
  • the resonance frequency returns to the initial value. Thereby, the standing wave ratio SWR of the radiator 2 is always kept in a range that can be accurately detected by the standing wave ratio detection circuit 4.
  • the estimation circuit 5 sets a threshold for the standing wave ratio SWR detected by the standing wave ratio detection circuit 4 or sets a threshold for the amount of PM attached to the radiator 2. Is set.
  • the amount of PM attached to the radiator 2 increases from 0 as time passes.
  • the standing wave ratio SWR detected by the standing wave ratio detection circuit 4 also increases from 1.
  • the estimation circuit 5 causes a current to flow through the heater 6 at an appropriate time. As a result, the PM amount decreases and returns to 0, and the standing wave ratio SWR decreases and returns to 1.
  • the standing wave ratio SWR reaches the threshold value
  • PM may be immediately removed from the heater 6 and the PM adhering to the radiator 2 may be removed regardless of the state of the internal combustion engine 21. Since the PM flowing out to the exhaust pipe 24 is not detected, the condition that the PM does not come to the exhaust pipe 24 after the standing wave ratio SWR reaches the threshold value (for example, the command value of the fuel supply amount to the internal combustion engine 21) PM is attached to the radiator 2 due to a current flowing through the heater 6 when the current is 0).
  • the threshold value for example, the command value of the fuel supply amount to the internal combustion engine 21
  • the estimation circuit 5 stores the PM amount detected immediately before the PM of the radiator 2 is removed, and this value is accumulated in the PM amount detected after the removal. Thereby, the cumulative value of the PM amount before and after the PM of the radiator 2 is removed is detected. Thereby, even when the span on which the PM that needs to be removed adheres to the radiator 2 is shorter than the span on which the PM that needs to be regenerated accumulates on the DPF 23, the detection of the amount of PM deposited on the radiator 2 is continued.
  • the estimation circuit 5 clears this accumulated value during DPF regeneration. Thereby, the total amount of PM flowing out from the DPF 23 to the exhaust pipe 24 after the DPF regeneration is estimated.
  • the radiator 2 of the PM sensor 1 is installed in the exhaust pipe 24 extending from the DPF 23 to the atmosphere so that PM flowing out from the DPF 23 to the exhaust pipe 24 is detected. 2 may be installed in the DPF 23. Further, when the radiator 2 is installed in the manifold side exhaust pipe 22, PM discharged from the internal combustion engine 21 is detected.
  • the radiator 2 is configured by a half-wave dipole antenna.
  • the present invention is not limited to this, and any type of the radiator 2 may be used. If the radiator is such that when the PM is not attached, all the supplied power is radiated as the traveling wave power Pf and there is no reflected wave power Pr, and when the PM is attached, the reflected wave power Pr is generated according to the amount of PM. Suitable for the present invention.

Abstract

Provided is a PM sensor which can accurately detect the amount of PM. The PM sensor is provided with a radiator (2) disposed within an atmosphere in which the exhaust from combustion flows, an oscillation circuit (3) which generates a signal by oscillating at the same frequency as the initial natural frequency of the radiator (2), a standing-wave ratio detection circuit (4) for detecting the standing-wave ratio when the signal from the oscillation circuit (3) is fed to the radiator (2), and an estimation circuit (5) for estimating the amount of PM attached to the radiator (2) from said standing-wave ratio.

Description

ＰＭセンサPM sensor
　本発明は、正確にＰＭ量を検出することができるＰＭセンサに関する。 The present invention relates to a PM sensor that can accurately detect the amount of PM.
　ディーゼルエンジンなどの内燃機関が搭載された車両には、内燃機関から大気までに至る排気ガスの排出流路にディーゼルパティキュレートフィルタ（Diesel Particulate Filter；以下、ＤＰＦという）が設置され、排気ガスに含まれるＳＯＦ、ＳＯＯＴなどの粒子状物質（Particulrate Matter；以下、ＰＭという）が捕集される。ＤＰＦは、主としてセラミックからなるハニカム細孔状（四角い細孔のものでもよい）のフィルタにＰＭを一時的に捕集する部材である。 A vehicle equipped with an internal combustion engine such as a diesel engine is equipped with a diesel particulate filter (hereinafter referred to as DPF) in the exhaust gas exhaust flow path from the internal combustion engine to the atmosphere. Particulate matter (Particulrate-Matter; hereinafter referred to as PM) such as SOF and SOOT is collected. The DPF is a member that temporarily collects PM in a filter having a honeycomb pore shape (which may be a square pore) mainly made of ceramic.
　捕集されたＰＭがＤＰＦに多く堆積すると、排気ガスが流れにくくなり、エンジンの排気圧力が上昇してエンジン特性が低下する。エンジン特性が低下しないよう、堆積したＰＭは燃焼により除去される必要がある。ＰＭが燃焼により除去される動作は、ＤＰＦ再生と呼ばれる。ＤＰＦ再生時には、排気温度を上昇させるための燃料噴射が行われ、この燃料噴射によって排気温度が上昇され、ＤＰＦが昇温され、ＤＰＦに捕集されているＰＭが燃焼される。 When a large amount of collected PM accumulates in the DPF, it becomes difficult for the exhaust gas to flow, the exhaust pressure of the engine rises, and the engine characteristics deteriorate. The accumulated PM needs to be removed by combustion so that the engine characteristics do not deteriorate. The operation in which PM is removed by combustion is called DPF regeneration. During DPF regeneration, fuel injection for increasing the exhaust temperature is performed, the exhaust temperature is increased by this fuel injection, the DPF is heated, and the PM collected in the DPF is combusted.
　このとき、ＤＰＦにＰＭが堆積しすぎていると、ＤＰＦ再生時の熱でＤＰＦが損傷してしまう。よって、ＤＰＦにＰＭが堆積しすぎないうちにＤＰＦ再生がなされる必要がある。しかし、従来は、ＰＭの堆積量が正確に計測されないので、ＰＭの堆積量に対して大きな安全係数が適用されてマージンが大きく確保され、ＰＭの堆積量が実際に許容できる量よりも少ない時期にＤＰＦ再生がなされる。このため、ＤＰＦ再生を実行する時間的な間隔が実際に必要な時間より短くなる。 At this time, if PM is accumulated too much on the DPF, the DPF is damaged by the heat generated during the DPF regeneration. Therefore, DPF regeneration needs to be performed before PM accumulates too much on the DPF. However, in the past, since the amount of PM deposition is not accurately measured, a large safety factor is applied to the amount of PM deposition, a large margin is ensured, and the amount of PM deposition is less than the actually allowable amount. DPF regeneration is performed. For this reason, the time interval for executing the DPF regeneration becomes shorter than the actually required time.
　しかし、必要以上に短い間隔でＤＰＦ再生が実行されると、燃料が余分に消費されることになり、燃費が悪化する。したがって、ＰＭの堆積量が正確に検出され、実際に堆積量が許容できる最大量に近づいた最も適切な時期にＤＰＦ再生が行われるようになるのが望ましい。 However, if DPF regeneration is executed at an interval shorter than necessary, extra fuel will be consumed and fuel consumption will deteriorate. Therefore, it is desirable that the amount of PM deposition is accurately detected, and the DPF regeneration is performed at the most appropriate time when the amount of deposition actually approaches the maximum allowable amount.
特開２００８－５４７０３２号公報JP 2008-547032 A 特開２００２－２８５８２２号公報JP 2002-285822 A 特開２００５－２１４０８４号公報JP 2005-214084 A
　従来、車両の走行距離が所定値に達するごとにＤＰＦ再生が行われるようになったのは、ＤＰＦに堆積したＰＭ量（ＰＭ量は、ＰＭロードとも呼ばれ、フィルタの詰まり具合を表す）を検出するのが困難であるからである。例えば、特許文献３の技術では、ＤＰＦの上流側と下流側の排気ガスの圧力差からＰＭ量が検出される。しかし、排気の流量・温度が内燃機関の状態変化に伴ってたえず変化するため、圧力差から検出されるＰＭ量は正確でない。 Conventionally, the DPF regeneration is performed each time the vehicle travel distance reaches a predetermined value. The amount of PM accumulated in the DPF (the PM amount is also called a PM load and indicates the degree of filter clogging). This is because it is difficult to detect. For example, in the technique of Patent Document 3, the PM amount is detected from the pressure difference between the exhaust gas upstream and downstream of the DPF. However, since the flow rate and temperature of the exhaust gas constantly change with changes in the state of the internal combustion engine, the PM amount detected from the pressure difference is not accurate.
　そこで、本発明の目的は、上記課題を解決し、正確にＰＭ量が検出されるＰＭセンサを提供することにある。 Therefore, an object of the present invention is to provide a PM sensor that solves the above-described problems and accurately detects the PM amount.
　上記目的を達成するために本発明のＰＭセンサは、燃焼による排気が流れる雰囲気中に設置された放射器と、該放射器の初期の固有周波数と同じ周波数で発振して信号を発生する発振回路と、該発振回路からの信号が前記放射器に給電されたときの定在波比を検出する定在波比検出回路と、この定在波比から前記放射器に付着したＰＭ量を推定する推定回路とを備えたものである。 In order to achieve the above object, a PM sensor according to the present invention includes a radiator installed in an atmosphere through which exhaust from combustion flows, and an oscillation circuit that oscillates at the same frequency as the initial natural frequency of the radiator to generate a signal. And a standing wave ratio detection circuit for detecting a standing wave ratio when a signal from the oscillation circuit is fed to the radiator, and an amount of PM attached to the radiator is estimated from the standing wave ratio. And an estimation circuit.
　本発明のＰＭセンサは、前記放射器に付着したＰＭを燃焼させるヒータを備えてもよい。 The PM sensor of the present invention may include a heater for burning the PM adhering to the radiator.
　前記ヒータは、排気中にＰＭがない条件にて、前記放射器に付着したＰＭを燃焼させてもよい。 The heater may burn the PM adhering to the radiator under the condition that there is no PM in the exhaust.
　前記ヒータは、前記定在波比検出回路が検出した定在波比が閾値に達したとき、前記放射器に付着したＰＭを燃焼させてもよい。 The heater may burn PM adhering to the radiator when the standing wave ratio detected by the standing wave ratio detection circuit reaches a threshold value.
　前記ヒータは、前記推定回路が推定したＰＭ量が閾値に達したとき、前記放射器に付着したＰＭを燃焼させてもよい。 The heater may burn the PM adhering to the radiator when the amount of PM estimated by the estimation circuit reaches a threshold value.
　前記放射器は、ディーゼルパティキュレートフィルタから大気に至る排気管内に設置されてもよい。 The radiator may be installed in an exhaust pipe extending from the diesel particulate filter to the atmosphere.
　前記放射器は、ディーゼルパティキュレートフィルタ内に設置されてもよい。 The radiator may be installed in a diesel particulate filter.
　前記放射器は、２つの放射素子がギャップの両側に配置されたダイポールアンテナであってもよい。 The radiator may be a dipole antenna in which two radiating elements are arranged on both sides of the gap.
　前記発振回路が出力する信号の強度は、排気管の外部に電波が漏れない信号強度であってもよい。 The intensity of the signal output from the oscillation circuit may be a signal intensity at which radio waves do not leak outside the exhaust pipe.
　前記推定回路は、推定したＰＭ量からディーゼルパティキュレートフィルタの再生時期を判定してもよい。 The estimation circuit may determine the regeneration timing of the diesel particulate filter from the estimated PM amount.
　本発明は次の如き優れた効果を発揮する。 The present invention exhibits the following excellent effects.
　（１）正確にＰＭ量を検出することができる。 (1) The amount of PM can be accurately detected.
本発明の一実施形態が示されるＰＭセンサの構成図である。It is a block diagram of PM sensor by which one Embodiment of this invention is shown. 本発明のＰＭセンサが設置された車両の排気管の構成図である。It is a block diagram of the exhaust pipe of the vehicle by which PM sensor of this invention was installed. 本発明のＰＭセンサにおけるＰＭ量と定在波比の時間遷移グラフである。It is a time transition graph of PM amount and standing wave ratio in PM sensor of the present invention.
　以下、本発明の一実施形態を添付図面に基づいて詳述する。 Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.
　図１に示されるように、本発明に係るＰＭセンサ１は、燃焼による排気が流れる雰囲気中に設置された放射器２と、放射器２の初期の固有周波数と同じ周波数で発振して信号を発生する発振回路３と、発振回路３からの信号が放射器２に給電されたときの定在波比を検出する定在波比検出回路４と、この定在波比から放射器２に付着したＰＭ量を推定する推定回路５とを備える。 As shown in FIG. 1, the PM sensor 1 according to the present invention oscillates at the same frequency as the initial natural frequency of the radiator 2 and the radiator 2 installed in the atmosphere in which the exhaust gas from combustion flows. The generated oscillation circuit 3, the standing wave ratio detection circuit 4 for detecting the standing wave ratio when the signal from the oscillation circuit 3 is fed to the radiator 2, and the standing wave ratio is attached to the radiator 2. And an estimation circuit 5 for estimating the PM amount.
　本実施形態では、図２に示されるように、内燃機関２１からの排気を排出するマニフォールド側排気管２２にＤＰＦ２３が接続され、そのＤＰＦ２３から大気に至る排気管２４内にＰＭセンサ１の放射器２が設置される。排気管２４は、例えば、円筒形あるいは楕円筒形に形成される。 In this embodiment, as shown in FIG. 2, a DPF 23 is connected to a manifold side exhaust pipe 22 that exhausts exhaust from the internal combustion engine 21, and the radiator of the PM sensor 1 is disposed in the exhaust pipe 24 from the DPF 23 to the atmosphere. 2 is installed. The exhaust pipe 24 is formed in, for example, a cylindrical shape or an elliptical cylindrical shape.
　図１に排気管２４内を透視して示されるように、放射器２は、１／４波長の電気長を持つ直線状の２つの放射素子２ａ、２ｂがギャップの両側に互いに反対方向に向けて配置された半波長のダイポールアンテナである。ここでは、２つの放射素子２ａ、２ｂが排気管２４の軸に直交させて配置され、放射素子２ａ、２ｂが排気流を直角に横断して排気流の上流に臨むようになっているが、放射素子２ａ、２ｂは、排気管２４の軸と平行であってもよく、あるいは排気管２４の軸と交差する向きであってもよく、放射素子２ａ、２ｂが排気流に対してなす角度は限定されない。 As shown in FIG. 1 through the inside of the exhaust pipe 24, the radiator 2 includes two linear radiating elements 2a and 2b having an electrical length of ¼ wavelength directed in opposite directions on both sides of the gap. Are half-wave dipole antennas. Here, the two radiating elements 2a, 2b are arranged perpendicular to the axis of the exhaust pipe 24, and the radiating elements 2a, 2b cross the exhaust flow at right angles so as to face the upstream of the exhaust flow. The radiating elements 2a and 2b may be parallel to the axis of the exhaust pipe 24, or may be in a direction intersecting with the axis of the exhaust pipe 24. The angle formed by the radiating elements 2a and 2b with respect to the exhaust flow is It is not limited.
　放射器２は、導体線が空中に張られることで形成されてもよいが、ここではセラミックで作られた直方体状の基体２ｃに印刷、接着等によって銅箔が設けられることで形成される。 The radiator 2 may be formed by extending a conductor wire in the air, but here, the radiator 2 is formed by providing a copper foil on a rectangular parallelepiped base 2c made of ceramic by printing, bonding or the like.
　発振回路３は、あらかじめ知られている放射器２の初期の固有周波数と同じ周波数で発振して信号を出力するものである。発振回路３は、公知の技術で実現できるので、詳細は省略する。信号の強度は、排気管２４の外部に不要な電波が漏れ出さない程度とするのが望ましい。発振回路３が出力する信号は、高調波を含まず基本波のみ有する正弦波であることが望ましい。 The oscillation circuit 3 oscillates at the same frequency as the initial natural frequency of the radiator 2 known in advance and outputs a signal. Since the oscillation circuit 3 can be realized by a known technique, the details are omitted. It is desirable that the signal intensity be such that unnecessary radio waves do not leak outside the exhaust pipe 24. The signal output from the oscillation circuit 3 is preferably a sine wave that does not include harmonics and has only a fundamental wave.
　定在波比検出回路４は、進行波電力と反射波電力を検出して後述する定義式を演算することで定在波比を求めるものである。定在波比検出回路４は、公知の技術で実現できるので、詳細は省略する。 The standing wave ratio detection circuit 4 obtains the standing wave ratio by detecting the traveling wave power and the reflected wave power and calculating a definition formula described later. Since the standing wave ratio detection circuit 4 can be realized by a known technique, the details are omitted.
　推定回路５は、例えば、ＥＣＵ（Engine Control Unit）で実現されるデジタル演算回路である。推定回路５は、定在波比から放射器２に付着したＰＭ量を推定した後、その放射器２に付着したＰＭ量からＤＰＦ２３に蓄積したＰＭ量を推定して再生時期を判定するか、あるいは放射器２に付着したＰＭ量から再生時期を判定することができる。これらの判定は、あらかじめ放射器２に付着したＰＭ量とＤＰＦ２３に蓄積したＰＭ量との関係、あるいは放射器２に付着したＰＭ量とＤＰＦ２３の再生時期との関係が実験等により調べられ、その関係に基づく判定ロジックが推定回路５に設定されることで実現される。 The estimation circuit 5 is a digital arithmetic circuit realized by an ECU (Engine Control Unit), for example. The estimation circuit 5 estimates the amount of PM attached to the radiator 2 from the standing wave ratio, and then determines the regeneration time by estimating the amount of PM accumulated in the DPF 23 from the amount of PM attached to the radiator 2. Alternatively, the regeneration time can be determined from the amount of PM attached to the radiator 2. In these determinations, the relationship between the PM amount adhering to the radiator 2 and the PM amount accumulated in the DPF 23 in advance, or the relationship between the PM amount adhering to the radiator 2 and the regeneration timing of the DPF 23 is examined by experiments, etc. This is realized by setting a determination logic based on the relationship in the estimation circuit 5.
　以下、本発明のＰＭセンサ１の動作が説明される。 Hereinafter, the operation of the PM sensor 1 of the present invention will be described.
　排気管２４内に設置された放射器２に発振回路３からの信号（高周波）が給電される。放射器２が半波長のダイポールアンテナであるから、放射器２の固有周波数（固有共振周波数とも言う）ｆは、放射器２のインダクタンスＬと静電容量Ｃとにより、式（１）で表される。 The signal (high frequency) from the oscillation circuit 3 is fed to the radiator 2 installed in the exhaust pipe 24. Since the radiator 2 is a half-wave dipole antenna, the natural frequency (also referred to as a natural resonance frequency) f of the radiator 2 is expressed by the equation (1) by the inductance L and the capacitance C of the radiator 2. The
Figure JPOXMLDOC01-appb-M000001
Figure JPOXMLDOC01-appb-M000001
　放射器２が給電された信号に完全に共振すると、放射器２に給電された電力は全て進行波となって放射器２から放射され、放射器２から給電側に戻る反射波の電力が０となり、スタンディングウェーブレシオ（定在波比；ＳＷＲ）が１になる。定在波比ＳＷＲは、進行波電力Ｐｆと反射波電力Ｐｒによる式（２）で表される。 When the radiator 2 completely resonates with the fed signal, all the power fed to the radiator 2 becomes a traveling wave and is radiated from the radiator 2, and the reflected wave power returning from the radiator 2 to the feeding side is zero. The standing wave ratio (standing wave ratio; SWR) becomes 1. The standing wave ratio SWR is expressed by Expression (2) using traveling wave power Pf and reflected wave power Pr.
Figure JPOXMLDOC01-appb-M000002
Figure JPOXMLDOC01-appb-M000002
　このとき、放射器２のインピーダンスは７５Ωとなる。 At this time, the impedance of radiator 2 is 75Ω.
　ところが、放射器２にＰＭが付着すると放射器２のインダクタンスＬやキャパシタンスＣが変化するため、放射器２の固有周波数ｆが変化し、放射器２のインピーダンスが変化する。放射器２の固有周波数ｆが放射器２にＰＭが付着していないときの初期値ｆ0から変化すると、発振回路３から周波数ｆ0の信号を給電された放射器２の定在波比ＳＷＲは、１より大きくなる。言い換えると、放射器２から給電側に戻る反射波の電力（反射波電力Ｐｒ）が０でなくなる。この反射波電力Ｐｒが検出されることで、定在波比ＳＷＲが測定される。よって、反射波電力Ｐｒあるいは定在波比ＳＷＲから放射器２に付着したＰＭ量が推定される。なお、反射波電力Ｐｒの検出と定在波比ＳＷＲの測定は同義である。また、放射器２のインピーダンスからでもＰＭ量が推定される。インピーダンスの測定は、定在波比ＳＷＲの測定と同様、公知技術で実施できる。 However, when PM adheres to radiator 2, inductance L and capacitance C of radiator 2 change, so that natural frequency f of radiator 2 changes, and impedance of radiator 2 changes. When the natural frequency f of the radiator 2 changes from the initial value f 0 when no PM is attached to the radiator 2, the standing wave ratio SWR of the radiator 2 fed with the signal of the frequency f 0 from the oscillation circuit 3. Is greater than 1. In other words, the power of the reflected wave returning from the radiator 2 to the power feeding side (reflected wave power Pr) is not zero. The standing wave ratio SWR is measured by detecting the reflected wave power Pr. Therefore, the amount of PM attached to the radiator 2 is estimated from the reflected wave power Pr or the standing wave ratio SWR. The detection of the reflected wave power Pr and the measurement of the standing wave ratio SWR are synonymous. The amount of PM is also estimated from the impedance of radiator 2. The measurement of impedance can be performed by a known technique, similarly to the measurement of the standing wave ratio SWR.
　この原理により、推定回路５は、定在波比検出回路４で求められた定在波比ＳＷＲから放射器２に付着したＰＭ量を推定する。放射器２に付着したＰＭ量と放射器２のインピーダンスは、比例関係にあるので、放射器２のインピーダンスからＰＭ量が推定されてもよい。さらに、推定回路５は、推定された放射器２に付着したＰＭ量からＤＰＦ２３に蓄積したＰＭ量を推定して再生時期を判定する。あるいは、推定回路５は、推定された放射器２に付着したＰＭ量に基づいてＤＰＦ２３の再生時期を判定する。 Based on this principle, the estimation circuit 5 estimates the amount of PM adhering to the radiator 2 from the standing wave ratio SWR obtained by the standing wave ratio detection circuit 4. Since the amount of PM attached to radiator 2 and the impedance of radiator 2 are in a proportional relationship, the amount of PM may be estimated from the impedance of radiator 2. Further, the estimation circuit 5 determines the regeneration timing by estimating the PM amount accumulated in the DPF 23 from the estimated PM amount adhering to the radiator 2. Alternatively, the estimation circuit 5 determines the regeneration time of the DPF 23 based on the estimated amount of PM attached to the radiator 2.
　以上説明したように、本発明のＰＭセンサ１は、排気流の雰囲気中に設置された放射器２に所定周波数の信号が給電されて電波が放射され、そのときの定在波比ＳＷＲから放射器２に付着したＰＭ量が推定されるようになっているので、正確にＰＭ量が検出され、検出された放射器２のＰＭ量に基づいてＤＰＦ２３のＰＭ量が検出されるので、従来のように排気ガスの圧力差から推定されるのに比べて、正確にＤＰＦ２３のＰＭ量が検出される。 As described above, the PM sensor 1 according to the present invention radiates from the standing wave ratio SWR when a signal having a predetermined frequency is fed to the radiator 2 installed in the atmosphere of the exhaust flow and a radio wave is radiated. Since the amount of PM adhering to the radiator 2 is estimated, the PM amount is accurately detected, and the PM amount of the DPF 23 is detected based on the detected PM amount of the radiator 2. As described above, the PM amount of the DPF 23 is detected more accurately than that estimated from the pressure difference of the exhaust gas.
　また、本発明のＰＭセンサ１は、放射器２と簡単な回路とから構成されるので、複数設けられた圧力センサによってＰＭ量が検出される従来の構成に比べて安価である。 Further, since the PM sensor 1 of the present invention is composed of the radiator 2 and a simple circuit, it is less expensive than the conventional configuration in which the PM amount is detected by a plurality of pressure sensors.
　ところで、放射器２にＰＭが付着すると、放射器２の定在波比ＳＷＲが大きくなる。付着したＰＭが大量になると定在波比ＳＷＲが無限大となり、ＰＭ量が正確に検出されなくなる。よって、適宜な時期に放射器２のＰＭが除去されるのが望ましい。そこで、図１に示されるように、本発明のＰＭセンサ１は、放射器２に付着したＰＭを燃焼させるヒータ６を備える。ヒータ６は、放射器２の基体２ｃに設けられるとよい。ヒータ６は、基体２ｃの内部、あるいは放射素子２ａ、２ｂの反対面に配置される。 By the way, when PM adheres to radiator 2, standing wave ratio SWR of radiator 2 increases. When the adhering PM becomes large, the standing wave ratio SWR becomes infinite, and the amount of PM cannot be accurately detected. Therefore, it is desirable to remove PM from radiator 2 at an appropriate time. Therefore, as shown in FIG. 1, the PM sensor 1 of the present invention includes a heater 6 that burns the PM adhering to the radiator 2. The heater 6 may be provided on the base 2c of the radiator 2. The heater 6 is disposed inside the base 2c or on the opposite surface of the radiating elements 2a and 2b.
　ヒータ６を備えたＰＭセンサ１は、適宜な時期にヒータ６に電流が流れ放射器２が加熱され、放射器２に付着しているＰＭが焼かれて除去されることにより、放射器２の共振周波数が初期値に戻る。これにより、放射器２の定在波比ＳＷＲが常に定在波比検出回路４で正確に検出可能な範囲に保たれる。 The PM sensor 1 provided with the heater 6 has a current flowing through the heater 6 at an appropriate time, the radiator 2 is heated, and PM adhering to the radiator 2 is burned and removed. The resonance frequency returns to the initial value. Thereby, the standing wave ratio SWR of the radiator 2 is always kept in a range that can be accurately detected by the standing wave ratio detection circuit 4.
　具体的には、推定回路５は、定在波比検出回路４により検出された定在波比ＳＷＲに対して閾値が設定されるか、あるいは放射器２に付着したＰＭ量に対して閾値が設定される。 Specifically, the estimation circuit 5 sets a threshold for the standing wave ratio SWR detected by the standing wave ratio detection circuit 4 or sets a threshold for the amount of PM attached to the radiator 2. Is set.
　図３に示されるように、時間経過に従い放射器２に付着したＰＭ量が０から増加していく。これに伴い定在波比検出回路４が検出する定在波比ＳＷＲも１から増加していく。定在波比ＳＷＲが閾値に達した後、適宜な時期に推定回路５がヒータ６に電流を流す。これにより、ＰＭ量が減少して０に戻り、定在波比ＳＷＲが減少して１に戻る。 As shown in FIG. 3, the amount of PM attached to the radiator 2 increases from 0 as time passes. Along with this, the standing wave ratio SWR detected by the standing wave ratio detection circuit 4 also increases from 1. After the standing wave ratio SWR reaches the threshold value, the estimation circuit 5 causes a current to flow through the heater 6 at an appropriate time. As a result, the PM amount decreases and returns to 0, and the standing wave ratio SWR decreases and returns to 1.
　なお、定在波比ＳＷＲが閾値に達したとき、内燃機関２１の状態とは無関係に直ちにヒータ６に電流が流れて放射器２に付着したＰＭが除去されてもよいが、その除去期間中には排気管２４に流れ出てきたＰＭが検出されないので、定在波比ＳＷＲが閾値に達した後、排気管２４にＰＭが来ない条件（例えば、内燃機関２１への燃料供給量の指令値が０のとき）においてヒータ６に電流が流れて放射器２に付着したＰＭが除去されてもよい。 Note that when the standing wave ratio SWR reaches the threshold value, PM may be immediately removed from the heater 6 and the PM adhering to the radiator 2 may be removed regardless of the state of the internal combustion engine 21. Since the PM flowing out to the exhaust pipe 24 is not detected, the condition that the PM does not come to the exhaust pipe 24 after the standing wave ratio SWR reaches the threshold value (for example, the command value of the fuel supply amount to the internal combustion engine 21) PM is attached to the radiator 2 due to a current flowing through the heater 6 when the current is 0).
　推定回路５は、放射器２のＰＭが除去される直前までに検出されたＰＭ量が記憶され、この値が除去後に検出されるＰＭ量に累積されるのが好ましい。これにより、放射器２のＰＭが除去される以前から以後にわたるＰＭ量の累積値が検知される。これにより、ＤＰＦ２３に再生が必要なＰＭが堆積するスパンより放射器２に除去が必要なＰＭが付着するスパンが短い場合でも、放射器２に堆積するＰＭ量の検出が継続される。 It is preferable that the estimation circuit 5 stores the PM amount detected immediately before the PM of the radiator 2 is removed, and this value is accumulated in the PM amount detected after the removal. Thereby, the cumulative value of the PM amount before and after the PM of the radiator 2 is removed is detected. Thereby, even when the span on which the PM that needs to be removed adheres to the radiator 2 is shorter than the span on which the PM that needs to be regenerated accumulates on the DPF 23, the detection of the amount of PM deposited on the radiator 2 is continued.
　推定回路５は、この累積値をＤＰＦ再生時にクリアする。これにより、ＤＰＦ再生後にＤＰＦ２３から排気管２４に流れ出たＰＭの総量が推定される。 The estimation circuit 5 clears this accumulated value during DPF regeneration. Thereby, the total amount of PM flowing out from the DPF 23 to the exhaust pipe 24 after the DPF regeneration is estimated.
　本実施形態では、ＰＭセンサ１の放射器２がＤＰＦ２３から大気に至る排気管２４内に設置されることで、ＤＰＦ２３から排気管２４に流れ出たＰＭが検出されるようにされたが、放射器２がＤＰＦ２３内に設置されてもよい。また、放射器２がマニフォールド側排気管２２に設置されると、内燃機関２１が排出するＰＭが検出される。 In the present embodiment, the radiator 2 of the PM sensor 1 is installed in the exhaust pipe 24 extending from the DPF 23 to the atmosphere so that PM flowing out from the DPF 23 to the exhaust pipe 24 is detected. 2 may be installed in the DPF 23. Further, when the radiator 2 is installed in the manifold side exhaust pipe 22, PM discharged from the internal combustion engine 21 is detected.
　本実施形態では、放射器２が半波長のダイポールアンテナで構成されたが、これに限らず放射器２の種類は何でもよい。ＰＭが付着していないとき供給された電力が全て進行波電力Ｐｆとして放射され反射波電力Ｐｒがなく、ＰＭが付着したときそのＰＭ量に応じて反射波電力Ｐｒが生じる放射器であれば、本発明に適する。 In the present embodiment, the radiator 2 is configured by a half-wave dipole antenna. However, the present invention is not limited to this, and any type of the radiator 2 may be used. If the radiator is such that when the PM is not attached, all the supplied power is radiated as the traveling wave power Pf and there is no reflected wave power Pr, and when the PM is attached, the reflected wave power Pr is generated according to the amount of PM. Suitable for the present invention.
　１　ＰＭセンサ
　２　放射器
　３　発振回路
　４　定在波比検出回路
　５　推定回路
　６　ヒータ 1 PM sensor 2 Radiator 3 Oscillation circuit 4 Standing wave ratio detection circuit 5 Estimation circuit 6 Heater

Claims (10)

  1. 　燃焼による排気が流れる雰囲気中に設置された放射器と、該放射器の初期の固有周波数と同じ周波数で発振して信号を発生する発振回路と、該発振回路からの信号が前記放射器に給電されたときの定在波比を検出する定在波比検出回路と、この定在波比から前記放射器に付着したＰＭ量を推定する推定回路とを備えたことを特徴とするＰＭセンサ。 A radiator installed in an atmosphere through which exhaust from combustion flows, an oscillation circuit that oscillates at the same frequency as the initial natural frequency of the radiator, and a signal from the oscillation circuit feeds the radiator A PM sensor comprising: a standing wave ratio detection circuit that detects a standing wave ratio when it is applied; and an estimation circuit that estimates the amount of PM attached to the radiator from the standing wave ratio.
  2. 　前記放射器に付着したＰＭを燃焼させるヒータを備えたことを特徴とする請求項１記載のＰＭセンサ。 The PM sensor according to claim 1, further comprising a heater for burning PM adhering to the radiator.
  3. 　前記ヒータは、排気中にＰＭがない条件にて、前記放射器に付着したＰＭを燃焼させることを特徴とする請求項２記載のＰＭセンサ。 3. The PM sensor according to claim 2, wherein the heater burns PM adhering to the radiator under a condition in which there is no PM in the exhaust.
  4. 　前記ヒータは、前記定在波比検出回路が検出した定在波比が閾値に達したとき、前記放射器に付着したＰＭを燃焼させることを特徴とする請求項２又は３記載のＰＭセンサ。 4. The PM sensor according to claim 2, wherein the heater burns PM adhering to the radiator when the standing wave ratio detected by the standing wave ratio detection circuit reaches a threshold value.
  5. 　前記ヒータは、前記推定回路が推定したＰＭ量が閾値に達したとき、前記放射器に付着したＰＭを燃焼させることを特徴とする請求項２又は３記載のＰＭセンサ。 The PM sensor according to claim 2 or 3, wherein the heater burns PM adhering to the radiator when the amount of PM estimated by the estimation circuit reaches a threshold value.
  6. 　前記放射器は、ディーゼルパティキュレートフィルタから大気に至る排気管内に設置されることを特徴とする請求項１記載のＰＭセンサ。 The PM sensor according to claim 1, wherein the radiator is installed in an exhaust pipe extending from a diesel particulate filter to the atmosphere.
  7. 　前記放射器は、ディーゼルパティキュレートフィルタ内に設置されることを特徴とする請求項１～６いずれか記載のＰＭセンサ。 The PM sensor according to any one of claims 1 to 6, wherein the radiator is installed in a diesel particulate filter.
  8. 　前記放射器は、２つの放射素子がギャップの両側に配置されたダイポールアンテナであることを特徴とする請求項１～７いずれか記載のＰＭセンサ。 The PM sensor according to any one of claims 1 to 7, wherein the radiator is a dipole antenna in which two radiating elements are arranged on both sides of a gap.
  9. 　前記発振回路が出力する信号の強度は、排気管の外部に電波が漏れない信号強度であることを特徴とする請求項１～８いずれか記載のＰＭセンサ。 The PM sensor according to any one of claims 1 to 8, wherein the intensity of the signal output from the oscillation circuit is a signal intensity at which radio waves do not leak outside the exhaust pipe.
  10. 　前記推定回路は、推定したＰＭ量からディーゼルパティキュレートフィルタの再生時期を判定することを特徴とする請求項１～９いずれか記載のＰＭセンサ。 10. The PM sensor according to claim 1, wherein the estimation circuit determines the regeneration timing of the diesel particulate filter from the estimated amount of PM.
PCT/JP2010/072767 2009-12-17 2010-12-17 Pm sensor WO2011074667A1 (en)

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JP6947980B2 (en) 2017-12-21 2021-10-13 富士通株式会社 Particulate matter detector and filter processing equipment

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JPH0466856A (en) * 1990-07-06 1992-03-03 Hitachi Cable Ltd Detecting device of ice and snow sticking on electric wire
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