JP2017172396A - Engine system and control method for engine system - Google Patents

Engine system and control method for engine system Download PDF

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JP2017172396A
JP2017172396A JP2016057231A JP2016057231A JP2017172396A JP 2017172396 A JP2017172396 A JP 2017172396A JP 2016057231 A JP2016057231 A JP 2016057231A JP 2016057231 A JP2016057231 A JP 2016057231A JP 2017172396 A JP2017172396 A JP 2017172396A
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大樹 田中
Daiki Tanaka
大樹 田中
和伸 小林
Kazunobu Kobayashi
和伸 小林
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    • 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
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    • Y02T10/10—Internal combustion engine [ICE] based vehicles
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    • 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
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    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
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    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/30—Use of alternative fuels, e.g. biofuels

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Abstract

PROBLEM TO BE SOLVED: To provide an engine system and a control method for the engine system capable of substantially expanding an operation range by performing a superior control over ignition characteristic while keeping its relative simple configuration.SOLUTION: This invention is configured in such a way that at least a part of mixture gas is ignited under an excess air factor at the mixture gas of less than 1 at a recirculation gas cylinder 40d by controlling a supply factor of fuel gas in respect to oxygen contained in combustion air at the recirculation gas cylinder 40d to perform a partial oxidization reaction and modified gas K acting as combustion gas including high ignition gas of higher ignition characteristic than that of fuel gas is generated at the recirculation cylinder 40d so as to enable a modified gas recirculation operation state to be carried out, and when the operation is being kept under the modified gas re-circulation operation state, water-gas-shift reaction control in which at least a part of the modified gas is generated at the recirculation gas cylinder and flowed to catalyst 92 can be executed.SELECTED DRAWING: Figure 1

Description

本発明は、燃料ガスと燃焼用空気との混合気を圧縮着火させ燃焼させるエンジンシステム、及びその制御方法に関する。   The present invention relates to an engine system that compresses and ignites an air-fuel mixture of fuel gas and combustion air, and a control method thereof.

これまで、多気筒エンジンにおいて、燃料ガスと燃焼用空気とを含む混合気を燃焼する燃焼室を有する通常気筒を少なくとも１つ備えると共に、混合気の少なくとも一部を燃焼室にて燃焼させ部分酸化反応させて、燃料ガスよりも燃焼速度の速いガスを含む改質ガスへ改質する再循環気筒を少なくとも１つ備え、再循環気筒にて改質された改質ガスを、少なくとも通常気筒へ導くエンジンが知られている（特許文献１を参照）。
例えば、メタンを主成分とする燃料ガスを含む過濃混合気を燃焼させ部分酸化反応させることで、水素、一酸化炭素及びアセチレン等を含む燃焼速度の速い改質ガスを生成できる。燃焼速度の速い水素等を含む改質ガスを通常気筒へ導くことで、水素等の高い燃焼速度により、希薄限界、ＥＧＲ限界が拡大し、熱効率が向上する。 Conventionally, in a multi-cylinder engine, at least one normal cylinder having a combustion chamber for burning an air-fuel mixture including fuel gas and combustion air is provided, and at least a part of the air-fuel mixture is combusted in the combustion chamber for partial oxidation. At least one recirculation cylinder that reacts and reforms into a reformed gas containing a gas having a higher combustion speed than the fuel gas is provided, and the reformed gas reformed in the recirculation cylinder is guided to at least the normal cylinder An engine is known (see Patent Document 1).
For example, a reformed gas having a high combustion rate containing hydrogen, carbon monoxide, acetylene, and the like can be generated by burning a rich mixture containing a fuel gas containing methane as a main component and causing a partial oxidation reaction. By introducing the reformed gas containing hydrogen or the like having a high combustion speed to the normal cylinder, the lean limit and the EGR limit are expanded and the thermal efficiency is improved due to the high combustion speed of hydrogen or the like.

一方で、燃焼室に給気された燃料ガスと燃焼用空気との混合気を圧縮着火させ燃焼させる予混合圧縮着火エンジンにおいては、燃料ガスの燃焼速度よりも、着火性が重要になる。
説明を追加すると、例えば、ＳＩエンジンでは、火花点火により着火時期を制御できるが、予混合圧縮着火エンジンでは、起動からの経過時間、エンジン負荷、空気比等の変化により、自着火の起こるタイミングが変化し、運転が継続できなくなる場合がある。
そこで、特許文献２に開示の技術にあっては、予混合圧縮着火エンジンにおいて、燃焼室の一部に、混合気よりも当量比が大きい濃混合気からなる濃領域を形成する燃料供給手段を備えると共に、燃焼状態検出手段の検出結果に基づいて、当該燃料供給手段による燃料の供給条件を制御する制御手段を備えている。
そして、燃焼室での燃焼状態により、燃焼室に形成される濃領域の形成状態を変化させることで、予混合圧縮着火エンジンの着火時期を制御し、運転範囲の拡大を図っている。 On the other hand, in a premixed compression ignition engine that compresses and ignites an air-fuel mixture of fuel gas supplied to the combustion chamber and combustion air, ignitability is more important than the combustion speed of the fuel gas.
For example, in the SI engine, the ignition timing can be controlled by spark ignition in the SI engine, but in the premixed compression ignition engine, the timing at which self-ignition occurs due to changes in the elapsed time from the start, engine load, air ratio, etc. It may change and the operation may not be continued.
Therefore, in the technique disclosed in Patent Document 2, in the premixed compression ignition engine, a fuel supply means for forming a rich region composed of a rich mixture having a larger equivalence ratio than the mixture in a part of the combustion chamber. And a control means for controlling the fuel supply condition by the fuel supply means based on the detection result of the combustion state detection means.
Then, the ignition state of the premixed compression ignition engine is controlled by changing the formation state of the concentrated region formed in the combustion chamber according to the combustion state in the combustion chamber, thereby expanding the operating range.

米国特許出願公開第２００９／０３０８０７０号明細書US Patent Application Publication No. 2009/0308070 特開２００４−２６３６６５号公報JP 2004-263665 A

上記特許文献２に開示の技術では、ある程度の着火時期の制御はできるものの、その効果は限定的であり改善の余地があった。   Although the technique disclosed in Patent Document 2 can control the ignition timing to some extent, the effect is limited and there is room for improvement.

本発明は、上述の課題に鑑みてなされたものであり、その目的は、比較的簡易な構成を維持しながらも、着火性の制御を良好に行うことができると共に、その運転範囲を拡大することができるエンジンシステム、及びその制御方法を提供することにある。   The present invention has been made in view of the above-described problems, and an object of the present invention is to improve the ignitability while maintaining a relatively simple configuration and to expand the operating range. It is an object to provide an engine system that can be used and a control method thereof.

上記目的を達成するためのエンジンシステムは、
燃料ガスと燃焼用空気との混合気を圧縮着火させ燃焼させるエンジンシステムであって、その特徴構成は、
混合気を燃焼する通常気筒を少なくとも１つ備えると共に、混合気を燃焼すると共に燃焼後の燃焼ガスを少なくとも前記通常気筒へ再循環可能な再循環気筒を備え、
少なくとも前記通常気筒へ燃料ガスを供給する第１燃料ガス供給部と、前記再循環気筒へ燃料ガスを供給する第２燃料ガス供給部とを各別に備え、
前記再循環気筒から前記通常気筒へ導かれる前記燃焼ガスの少なくとも一部を水性ガスシフト反応させる触媒を備え、
前記再循環気筒での燃焼用空気に含まれる酸素に対する燃料ガスの供給比率を制御する形態で前記再循環気筒での混合気の空気過剰率を１より小さくして混合気の少なくとも一部を燃焼させ部分酸化反応させて燃料ガスよりも着火性の高い高着火性ガスが含まれる前記燃焼ガスとしての改質ガスを前記再循環気筒にて生成して再循環させる改質ガス再循環運転状態を実行可能に構成され、
前記改質ガス再循環運転状態にあるときに、前記再循環気筒にて生成される前記改質ガスの少なくとも一部を前記触媒へ通流させる水性ガスシフト反応制御を実行可能に構成されている点にある。 An engine system for achieving the above object is as follows:
An engine system that compresses and ignites an air-fuel mixture of fuel gas and combustion air, and its characteristic configuration is:
Including at least one normal cylinder for combusting the air-fuel mixture, and having a recirculation cylinder for combusting the air-fuel mixture and recirculating the combustion gas after combustion to at least the normal cylinder;
A first fuel gas supply unit for supplying fuel gas to at least the normal cylinder and a second fuel gas supply unit for supplying fuel gas to the recirculation cylinder;
A catalyst for causing a water gas shift reaction of at least a part of the combustion gas guided from the recirculation cylinder to the normal cylinder;
Combusting at least a part of the air-fuel mixture by reducing the excess air ratio of the air-fuel mixture in the recirculation cylinder to less than 1 in the form of controlling the supply ratio of fuel gas to oxygen contained in the combustion air in the recirculation cylinder A reformed gas recirculation operation state in which the reformed gas as the combustion gas containing the highly ignitable gas having higher ignitability than the fuel gas by the partial oxidation reaction is generated and recirculated in the recirculation cylinder. Configured to run,
The water gas shift reaction control that allows at least a part of the reformed gas generated in the recirculation cylinder to flow to the catalyst when in the reformed gas recirculation operation state is configured to be executable. It is in.

上記目的を達成するためのエンジンシステムの制御方法は、
燃料ガスと燃焼用空気との混合気を圧縮着火させ燃焼させるエンジンシステムの制御方法であって、その特徴構成は、
混合気を燃焼する通常気筒を少なくとも１つ備えると共に、混合気を燃焼すると共に燃焼後の燃焼ガスを少なくとも前記通常気筒へ再循環可能な再循環気筒を備え、
少なくとも前記通常気筒へ燃料ガスを供給する第１燃料ガス供給部と、前記再循環気筒へ燃料ガスを供給する第２燃料ガス供給部とを各別に備え、
前記再循環気筒から前記通常気筒へ導かれる前記燃焼ガスの少なくとも一部を水性ガスシフト反応させる触媒を備えた構成において、
前記再循環気筒での燃焼用空気に含まれる酸素に対する燃料ガスの供給比率を制御する形態で前記再循環気筒での混合気の空気過剰率を１より小さくして混合気の少なくとも一部を燃焼させ部分酸化反応させて燃料ガスよりも着火性の高い高着火性ガスが含まれる前記燃焼ガスとしての改質ガスを前記再循環気筒にて生成して再循環させる改質ガス再循環運転状態を実行するように制御され、
前記改質ガス再循環運転状態にあるときに、前記再循環気筒にて生成される前記改質ガスの少なくとも一部を前記触媒へ通流させる水性ガスシフト反応制御を実行するように制御される点にある。 An engine system control method for achieving the above object is as follows:
A control method for an engine system for compressing and igniting an air-fuel mixture of fuel gas and combustion air for combustion, the characteristic configuration of which is
Including at least one normal cylinder for combusting the air-fuel mixture, and having a recirculation cylinder for combusting the air-fuel mixture and recirculating the combustion gas after combustion to at least the normal cylinder;
A first fuel gas supply unit for supplying fuel gas to at least the normal cylinder and a second fuel gas supply unit for supplying fuel gas to the recirculation cylinder;
In a configuration including a catalyst that causes a water gas shift reaction of at least a part of the combustion gas guided from the recirculation cylinder to the normal cylinder,
Combusting at least a part of the air-fuel mixture by reducing the excess air ratio of the air-fuel mixture in the recirculation cylinder to less than 1 in the form of controlling the supply ratio of fuel gas to oxygen contained in the combustion air in the recirculation cylinder A reformed gas recirculation operation state in which the reformed gas as the combustion gas containing the highly ignitable gas having higher ignitability than the fuel gas by the partial oxidation reaction is generated and recirculated in the recirculation cylinder. Controlled to run,
Control is performed so as to execute water gas shift reaction control for allowing at least a part of the reformed gas generated in the recirculation cylinder to flow to the catalyst when in the reformed gas recirculation operation state. It is in.

図２に、縦軸を筒内ガス温度とし、横軸をクランク角度として、予混合圧縮着火エンジンの通常の予混合圧縮着火運転状態（図２で実線）と改質ガス再循環運転状態（ここでは、通常気筒へ燃焼ガスを再循環しない場合の通常気筒での混合気の着火性である基準着火性よりも高い着火性の改質ガスを再循環させる高着火性改質ガス再循環運転状態を意味するものとする：図２で一点鎖線）とにおいて、詳細化学反応計算により導出した、クランク角度に応じて筒内ガス温度の変化のグラフ図を示す。因みに、図２では、温度変化が変曲する点（図２にプロット）を着火点と定義し、当該着火点での筒内ガス温度を着火温度とする。
尚、図２の二点鎖線は、再循環気筒での燃焼用空気に含まれる酸素に対する燃料ガスの供給比率を制御する形態で再循環気筒での混合気の空気過剰率を１以上として再循環気筒から燃焼ガスとして改質ガスよりも着火性の低い燃焼排ガスを再循環させる排ガス再循環運転状態を示したものである。
本願の発明者らは、鋭意検討した結果、図２の詳細化学反応計算の結果に示すように、圧縮・膨張行程において、通常の予混合圧縮着火エンジンの予混合圧縮着火運転状態における着火温度に対して、改質ガス再循環運転状態における着火温度を低く（着火性を高く）できることを見出した。因みに、当該詳細化学反応計算は、圧縮比を２６、当量比を０．３、改質ガスに含まれる水素濃度を８％、給気量に対する改質ガス又は燃焼排ガスの再循環量の割合を２０％とした場合の計算結果である。また、発明者らは、後に示す実験結果においても、同様の傾向が示されることを確認している。
更に、発明者らは、上述した改質ガスには、一酸化炭素と水とが含まれており、当該一酸化炭素と水とを、触媒にて以下の〔式１〕に示す水性ガスシフト反応させることにより、改質ガスに含まれる水素の濃度を、以下の〔表１〕に示すように増加させることができることを化学平衡計算により明らかにした。
因みに、当該化学平衡計算は、当量比が１．５の混合気を燃焼室で燃焼させた場合で、排ガスの温度が４７７℃という条件で行ったものであり、各種気体の含有割合は水分を含まないドライベースのものである。 In FIG. 2, the vertical axis is the in-cylinder gas temperature, the horizontal axis is the crank angle, the normal premixed compression ignition operation state (solid line in FIG. 2) and the reformed gas recirculation operation state (here) Is a highly ignited reformed gas recirculation operation state in which the reformed gas having a higher ignitability than the reference ignitability, which is the ignitability of the air-fuel mixture in the normal cylinder, is not recirculated to the normal cylinder. In FIG. 2, a graph of the change in the in-cylinder gas temperature in accordance with the crank angle derived from the detailed chemical reaction calculation is shown. In FIG. 2, the point at which the temperature change is inflected (plotted in FIG. 2) is defined as the ignition point, and the in-cylinder gas temperature at the ignition point is defined as the ignition temperature.
Note that the two-dot chain line in FIG. 2 is a form in which the supply ratio of the fuel gas to the oxygen contained in the combustion air in the recirculation cylinder is controlled to recirculate the excess air ratio of the air-fuel mixture in the recirculation cylinder as 1 or more. The exhaust gas recirculation operation state in which the combustion exhaust gas having lower ignitability than the reformed gas as the combustion gas from the cylinder is recirculated is shown.
As a result of diligent study, the inventors of the present application, as shown in the result of detailed chemical reaction calculation in FIG. 2, set the ignition temperature in the premixed compression ignition operation state of the normal premixed compression ignition engine in the compression / expansion stroke. On the other hand, it has been found that the ignition temperature in the reformed gas recirculation operation state can be lowered (ignitability can be increased). Incidentally, in the detailed chemical reaction calculation, the compression ratio is 26, the equivalence ratio is 0.3, the hydrogen concentration contained in the reformed gas is 8%, and the ratio of the recirculation amount of the reformed gas or the combustion exhaust gas to the supply air amount is calculated. It is a calculation result in the case of 20%. The inventors have also confirmed that the same tendency is shown in the experimental results shown later.
Furthermore, the inventors include carbon monoxide and water in the above-described reformed gas, and the carbon monoxide and water are converted into a water gas shift reaction represented by the following [Formula 1] using a catalyst. It was clarified by chemical equilibrium calculation that the concentration of hydrogen contained in the reformed gas can be increased as shown in Table 1 below.
Incidentally, the chemical equilibrium calculation is performed when an air-fuel mixture with an equivalence ratio of 1.5 is burned in the combustion chamber and the temperature of the exhaust gas is 477 ° C. Does not contain dry base.

ＣＯ＋Ｈ2Ｏ→ＣＯ2＋Ｈ2・・・〔式１〕 CO + H 2 O → CO 2 + H 2 (Equation 1)

Figure 2017172396
Figure 2017172396

即ち、発明者らは、上記詳細化学反応計算、及び化学平衡計算により、再循環気筒での燃焼用空気に含まれる酸素に対する燃料ガスの供給比率を制御する形態で再循環気筒での混合気の空気過剰率を１より小さくして混合気の少なくとも一部を燃焼させ部分酸化反応させて燃料ガスよりも着火性の高い高着火性ガスが含まれる燃焼ガスとしての改質ガスを再循環気筒にて生成して再循環させる改質ガス再循環運転状態を実行可能に構成され、改質ガス再循環運転状態にあるときに、再循環気筒にて生成される改質ガスの少なくとも一部を触媒へ通流させる水性ガスシフト反応制御を実行可能に構成されている本発明を完成した。
当該発明により、再循環気筒での燃焼用空気に含まれる酸素に対する燃料ガスの供給比率の制御にて、改質ガスに含まれる高着火性ガスの含有割合を調整する形態で、着火性を制御でき、運転範囲の拡大を図ることができる。更に、当該発明にあっては、水性ガスシフト反応制御をも実行することができるから、改質ガスに含まれる高着火性ガスのうち水素の含有割合を調整する形態で、着火性を制御でき、より一層の運転範囲の拡大を図ることができる。
尚、当該明細書においては、燃焼室にて混合気が着火し易いことを、着火性が高いと表現し、燃焼室にて混合気が着火し難いことを、着火性が低いと表現することとする。
また、当該明細書においては、燃焼ガスは、改質ガスと燃焼排ガスとの双方を含む概念であるとする。 In other words, the inventors controlled the supply ratio of the fuel gas to the oxygen contained in the combustion air in the recirculation cylinder by controlling the mixture ratio in the recirculation cylinder by the above detailed chemical reaction calculation and chemical equilibrium calculation. A reformed gas as a combustion gas containing a highly ignitable gas having a higher ignitability than the fuel gas by burning at least a part of the air-fuel mixture with an excess air ratio less than 1 and causing a partial oxidation reaction to the recirculation cylinder The reformed gas recirculation operation state that is generated and recirculated is configured to be executable, and when in the reformed gas recirculation operation state, at least a part of the reformed gas generated in the recirculation cylinder is catalyzed. The present invention has been completed, which is configured so that water gas shift reaction control can be performed.
According to the present invention, the ignitability is controlled by adjusting the content ratio of the highly ignitable gas contained in the reformed gas by controlling the supply ratio of the fuel gas to the oxygen contained in the combustion air in the recirculation cylinder. The range of operation can be expanded. Furthermore, in the present invention, since water gas shift reaction control can also be performed, the ignitability can be controlled by adjusting the content ratio of hydrogen in the highly ignitable gas contained in the reformed gas, The operation range can be further expanded.
In this specification, the fact that the air-fuel mixture is easy to ignite in the combustion chamber is expressed as high ignitability, and the fact that the air-fuel mixture is difficult to ignite in the combustion chamber is expressed as low ignitability. And
In the specification, the combustion gas is a concept including both the reformed gas and the combustion exhaust gas.

上記目的を達成するためのエンジンシステムは、
燃料ガスと燃焼用空気との混合気を圧縮着火させ燃焼させる通常気筒を少なくとも一つ有すると共に、混合気を形成する燃料ガスを供給する第１燃料ガス供給部を有する予混合圧縮着火エンジンを備えたエンジンシステムであって、その特徴構成は、
混合気を燃焼すると共に燃焼後の燃焼ガスを前記通常気筒へ再循環可能な再循環気筒を有すると共に、前記再循環気筒へ燃料ガスを供給する第２燃料ガス供給部を前記第１燃料ガス供給部とは別に有する補助エンジンを備え、
前記再循環気筒から前記通常気筒へ導かれる前記燃焼ガスの少なくとも一部を水性ガスシフト反応させる触媒を備え、
前記再循環気筒での燃焼用空気に含まれる酸素に対する燃料ガスの供給比率を制御する形態で前記再循環気筒での混合気の空気過剰率を１より小さくして混合気の少なくとも一部を燃焼させ部分酸化反応させて燃料ガスよりも着火性の高い高着火性ガスが含まれる前記燃焼ガスとしての改質ガスを前記再循環気筒にて生成して再循環させる改質ガス再循環運転状態を実行可能に構成され、
前記改質ガス再循環運転状態にあるときに、前記再循環気筒にて生成される前記改質ガスの少なくとも一部を前記触媒へ通流させる水性ガスシフト反応制御を実行可能に構成されている点にある。 An engine system for achieving the above object is as follows:
A premixed compression ignition engine having at least one normal cylinder for compressing and igniting and burning an air-fuel mixture of fuel gas and combustion air and having a first fuel gas supply unit for supplying fuel gas forming the air-fuel mixture Engine system, and its characteristic configuration is
The first fuel gas supply includes a recirculation cylinder capable of combusting the air-fuel mixture and recirculating the combustion gas after combustion to the normal cylinder, and supplying a fuel gas to the recirculation cylinder. Auxiliary engine that has separate from the part,
A catalyst for causing a water gas shift reaction of at least a part of the combustion gas guided from the recirculation cylinder to the normal cylinder;
Combusting at least a part of the air-fuel mixture by reducing the excess air ratio of the air-fuel mixture in the recirculation cylinder to less than 1 in the form of controlling the supply ratio of fuel gas to oxygen contained in the combustion air in the recirculation cylinder A reformed gas recirculation operation state in which the reformed gas as the combustion gas containing the highly ignitable gas having higher ignitability than the fuel gas by the partial oxidation reaction is generated and recirculated in the recirculation cylinder. Configured to run,
The water gas shift reaction control that allows at least a part of the reformed gas generated in the recirculation cylinder to flow to the catalyst when in the reformed gas recirculation operation state is configured to be executable. It is in.

上記目的を達成するためのエンジンシステムの制御方法は、
燃料ガスと燃焼用空気との混合気を圧縮着火させ燃焼させる通常気筒を少なくとも一つ有すると共に、混合気を形成する燃料ガスを供給する第１燃料ガス供給部を有する予混合圧縮着火エンジンを備えたエンジンシステムの制御方法であって、その特徴構成は、
混合気を燃焼すると共に燃焼後の燃焼ガスを前記通常気筒へ再循環可能な再循環気筒を有すると共に、前記再循環気筒へ燃料ガスを供給する第２燃料ガス供給部を前記第１燃料ガス供給部とは別に有する補助エンジンを備え、
前記再循環気筒から前記通常気筒へ導かれる前記燃焼ガスの少なくとも一部を水性ガスシフト反応させる触媒を備えた構成において、
前記再循環気筒での燃焼用空気に含まれる酸素に対する燃料ガスの供給比率を制御する形態で前記再循環気筒での混合気の空気過剰率を１より小さくして混合気の少なくとも一部を燃焼させ部分酸化反応させて燃料ガスよりも着火性の高い高着火性ガスが含まれる前記燃焼ガスとしての改質ガスを前記再循環気筒にて生成して再循環させる改質ガス再循環運転状態を実行するように制御され、
前記改質ガス再循環運転状態にあるときに、前記再循環気筒にて生成される前記改質ガスの少なくとも一部を前記触媒へ通流させる水性ガスシフト反応制御を実行するように制御される点にある。 An engine system control method for achieving the above object is as follows:
A premixed compression ignition engine having at least one normal cylinder for compressing and igniting and burning an air-fuel mixture of fuel gas and combustion air and having a first fuel gas supply unit for supplying fuel gas forming the air-fuel mixture The engine system control method has the following features:
The first fuel gas supply includes a recirculation cylinder capable of combusting the air-fuel mixture and recirculating the combustion gas after combustion to the normal cylinder, and supplying a fuel gas to the recirculation cylinder. Auxiliary engine that has separate from the part,
In a configuration including a catalyst that causes a water gas shift reaction of at least a part of the combustion gas guided from the recirculation cylinder to the normal cylinder,
Combusting at least a part of the air-fuel mixture by reducing the excess air ratio of the air-fuel mixture in the recirculation cylinder to less than 1 in the form of controlling the supply ratio of fuel gas to oxygen contained in the combustion air in the recirculation cylinder A reformed gas recirculation operation state in which the reformed gas as the combustion gas containing the highly ignitable gas having higher ignitability than the fuel gas by the partial oxidation reaction is generated and recirculated in the recirculation cylinder. Controlled to run,
Control is performed so as to execute water gas shift reaction control for allowing at least a part of the reformed gas generated in the recirculation cylinder to flow to the catalyst when in the reformed gas recirculation operation state. It is in.

即ち、本発明のエンジンシステム及びその制御方法としては、外部出力を行うための通常気筒を有する予混合圧縮着火エンジンとは別に、改質ガスと燃焼排ガスとを含む燃焼ガスを生成するための再循環気筒を有する補助エンジンを備えるものをも権利範囲に含むものである。   That is, the engine system and the control method thereof according to the present invention include a regenerator for generating combustion gas including reformed gas and combustion exhaust gas separately from a premixed compression ignition engine having a normal cylinder for performing external output. Those having an auxiliary engine having a circulation cylinder are also included in the scope of rights.

エンジンシステムの更なる特徴構成は、
前記改質ガス再循環運転状態において前記再循環気筒での燃焼用空気に含まれる酸素に対する燃料ガスの供給比率を制御する形態で前記再循環気筒での混合気の空気過剰率を１より小さい範囲で制御する空気過剰率制御と、前記改質ガス再循環運転状態における前記水性ガスシフト反応制御との少なくとも何れか一方を実行する形態で、前記通常気筒での着火性を制御する着火性制御手段を備える点にある。 Further characteristic configuration of the engine system
The excess air ratio of the air-fuel mixture in the recirculation cylinder is smaller than 1 in the form of controlling the supply ratio of the fuel gas to the oxygen contained in the combustion air in the recirculation cylinder in the reformed gas recirculation operation state. An ignitability control means for controlling the ignitability in the normal cylinder in a form in which at least one of the excess air ratio control controlled by the control and the water gas shift reaction control in the reformed gas recirculation operation state is executed. It is in the point to prepare.

上記特徴構成によれば、改質ガス再循環運転状態における空気過剰率制御の実行により、改質ガスに対する、水素、一酸化炭素及びアセチレン等を含む高着火性ガスの含有割合を変更して、着火性をより細やかに制御でき、更に、改質ガス再循環運転状態における水性ガスシフト反応制御を実行することで、改質ガスにおける高着火性ガスとしての水素の含有割合を変更して、着火性をより細やかに制御できる。   According to the above characteristic configuration, by executing the excess air ratio control in the reformed gas recirculation operation state, the content ratio of the highly ignitable gas containing hydrogen, carbon monoxide, acetylene, etc. to the reformed gas is changed, The ignitability can be controlled more finely. Furthermore, by executing the water gas shift reaction control in the reformed gas recirculation operation state, the content ratio of hydrogen as a highly ignitable gas in the reformed gas is changed, and the ignitability is changed. Can be controlled more finely.

エンジンシステムの更なる特徴構成は、
前記通常気筒での着火時期を検出する着火時期検出手段を備え、
前記着火性制御手段は、前記着火時期検出手段にて検出される前記着火時期が目標着火時期よりも遅角化している場合に、前記通常気筒での着火性を向上させ、前記着火時期検出手段にて検出される前記着火時期が目標着火時期よりも進角化している場合に、着火性を低減させる点にある。 Further characteristic configuration of the engine system
Ignition timing detecting means for detecting the ignition timing in the normal cylinder,
The ignitability control means improves the ignitability in the normal cylinder when the ignition timing detected by the ignition timing detection means is retarded from a target ignition timing, and the ignition timing detection means In the case where the ignition timing detected at (1) is advanced from the target ignition timing, the ignitability is reduced.

本願に係る発明にあっては、通常気筒での着火時期を検出する着火時期検出手段を備え、着火性制御手段が、着火時期検出手段にて検出される着火時期が目標着火時期よりも遅角化している場合に、通常気筒での着火性を向上させ、着火時期検出手段にて検出される着火時期が目標着火時期よりも進角化している場合に、着火性を低減させることが好ましい。
上記特徴構成を備えることにより、着火時期を目標着火時期に制御する形態で、通常気筒の着火性をより適切な値に設定することができる。 The invention according to the present application includes ignition timing detection means for detecting the ignition timing in the normal cylinder, and the ignition timing control means is configured such that the ignition timing detected by the ignition timing detection means is delayed from the target ignition timing. If the ignition timing is improved, the ignitability in the normal cylinder is improved, and it is preferable to reduce the ignitability when the ignition timing detected by the ignition timing detection means is advanced from the target ignition timing.
With the above characteristic configuration, the ignitability of the normal cylinder can be set to a more appropriate value in a form in which the ignition timing is controlled to the target ignition timing.

エンジンシステムの更なる特徴構成は、
前記再循環気筒から前記通常気筒へ導かれる前記燃焼ガスを通流すると共に前記触媒が設けられる触媒流路と、前記触媒流路を通流する前記燃焼ガスに前記触媒をバイパスさせる触媒バイパス路と、前記触媒流路を通流する前記燃焼ガスの流量と前記触媒バイパス路を通流する前記燃焼ガスの流量との流量比を制御する流量比制御弁とを備え、
前記着火性制御手段は、前記水性ガスシフト反応制御において、前記流量比制御弁の開度を制御する形態で、前記触媒を通流させて前記水性ガスシフト反応させる前記改質ガスの流量を制御するシフト反応制御手段として働く点にある。 Further characteristic configuration of the engine system
A catalyst flow path through which the combustion gas guided from the recirculation cylinder to the normal cylinder flows and the catalyst is provided; a catalyst bypass path for bypassing the catalyst to the combustion gas flowing through the catalyst flow path; A flow ratio control valve for controlling a flow ratio between the flow rate of the combustion gas flowing through the catalyst flow path and the flow rate of the combustion gas flowing through the catalyst bypass path,
In the water gas shift reaction control, the ignitability control means controls the flow rate of the reformed gas that causes the water gas shift reaction to flow through the catalyst in the form of controlling the opening degree of the flow rate control valve. It works as a reaction control means.

上記特徴構成によれば、再循環気筒にて生成された改質ガスのうち、水性ガスシフト反応が行われる触媒を通流する流量を制御できる。
これにより、例えば、改質ガスに含まれる高着火性ガスとしての水素の含有割合の目標値が、改質ガス再循環運転状態における空気過剰率制御にて調整できる範囲の場合（例えば、改質ガスに対する水素の含有割合が０％以上８％程度以下の場合）には、改質ガス再循環運転状態における空気過剰率制御を実行することで、改質ガスに対する水素の含有割合を制御できるから、改質ガスの全量を触媒バイパス路に通流させる形態で、触媒の劣化を抑制できる。
一方、改質ガスに含まれる高着火性ガスとしての水素の含有割合の目標値が、改質ガス再循環運転状態における空気過剰率制御にて調整できる範囲を超える場合（例えば、改質ガスに対する水素の含有割合が８％を超える場合）には、改質ガス再循環運転状態における空気過剰率制御を実行すると共に、触媒に改質ガスを通過させて水性ガスシフト反応を行わせることで、改質ガスに対する水素の含有割合を、改質ガス再循環運転状態における空気過剰率制御にて調整できる上限値よりも高い値に調整できる。
これにより、触媒の劣化を抑制しながらも、運転範囲のより一層の拡大を実現できる。 According to the above characteristic configuration, it is possible to control the flow rate of the reformed gas generated in the recirculation cylinder through the catalyst in which the water gas shift reaction is performed.
Thereby, for example, when the target value of the content ratio of hydrogen as the highly ignitable gas contained in the reformed gas is within a range that can be adjusted by the excess air ratio control in the reformed gas recirculation operation state (for example, reforming When the hydrogen content to the gas is 0% or more and about 8% or less), the hydrogen content to the reformed gas can be controlled by executing the excess air ratio control in the reformed gas recirculation operation state. The deterioration of the catalyst can be suppressed in a form in which the entire amount of the reformed gas is passed through the catalyst bypass passage.
On the other hand, when the target value of the hydrogen content ratio as the highly ignitable gas contained in the reformed gas exceeds the range that can be adjusted by the excess air ratio control in the reformed gas recirculation operation state (for example, with respect to the reformed gas) When the hydrogen content exceeds 8%), the excess air ratio control in the reformed gas recirculation operation state is performed, and the reformed gas is allowed to pass through the catalyst to perform the water gas shift reaction. The content ratio of hydrogen to the quality gas can be adjusted to a value higher than the upper limit value that can be adjusted by controlling the excess air ratio in the reformed gas recirculation operation state.
Thereby, it is possible to further expand the operation range while suppressing deterioration of the catalyst.

エンジンシステムの更なる特徴構成は、
前記改質ガス再循環運転状態は、前記通常気筒へ前記燃焼ガスを再循環しない場合の前記通常気筒での混合気の着火性を基準着火性としたときに、前記基準着火性よりも低い着火性の前記改質ガスを再循環させる準高着火性改質ガス再循環運転状態と、前記基準着火性と同一の着火性の前記改質ガスを再循環させる基準着火性改質ガス再循環運転状態と、前記基準着火性よりも高い着火性の前記改質ガスを再循環させる高着火性改質ガス再循環運転状態と、を含むものであり、
前記シフト反応制御手段は、少なくとも前記準高着火性改質ガス再循環運転状態と前記基準着火性改質ガス再循環運転状態とにあるときに、前記流量比制御弁により前記触媒流路へ通流する前記改質ガスの流量を零とし、前記高着火性改質ガス再循環運転状態にあるときに、前記流量比制御弁により前記触媒流路へ通流する前記改質ガスの流量を零より大きい範囲で制御する形態で、前記水性ガスシフト反応制御を実行する点にある。 Further characteristic configuration of the engine system
The reformed gas recirculation operation state is lower than the reference ignitability when the ignitability of the air-fuel mixture in the normal cylinder when the combustion gas is not recirculated to the normal cylinder is set as the reference ignitability. The semi-highly ignitable reformed gas recirculation operation state for recirculating the reformed gas having the same property and the reference ignitable reformed gas recirculation operation for recirculating the reformed gas having the same ignitability as the reference ignitability And a high ignitability reformed gas recirculation operation state in which the reformed gas having an ignitability higher than the reference ignitability is recirculated,
When the shift reaction control means is at least in the semi-highly ignited reformed gas recirculation operation state and the reference ignitable reformed gas recirculation operation state, the shift ratio control valve passes the shift reaction control means to the catalyst flow path. The flow rate of the reformed gas flowing is zero, and when the highly ignitable reformed gas recirculation operation is in progress, the flow rate of the reformed gas flowing through the catalyst flow path by the flow rate control valve is zero. The water gas shift reaction control is performed in such a manner that it is controlled in a larger range.

上記特徴構成によれば、例えば、改質ガスに含まれる高着火性ガスとしての水素の濃度をそれほど高くする必要がないときには、改質ガス再循環運転状態として準高着火性改質ガス再循環運転状態及び基準着火性改質ガス再循環運転状態として、改質ガスに含まれる高着火性ガスとしての水素の濃度を所望の値に制御しながらも、触媒に通流する改質ガスの流量を零とすることで、触媒の劣化を防ぐことができる。
更に、例えば、改質ガスに含まれる高着火性ガスとしての水素の濃度を改質ガス再循環運転状態で生成可能な水素の濃度よりも高くする必要があるときには、触媒を通流する改質ガスの流量を零より大きい範囲で制御することで、改質ガスに含まれる高着火性ガスとしての水素の濃度を十分に高くすることができる。
尚、触媒への改質ガスの通流は、高着火性改質ガス再循環運転状態において、設定される空気過剰率が再循環気筒で失火が起きない範囲で最小の空気過剰率であるときに、行うことが好ましい。
また、排ガス再循環運転状態にない場合（再循環気筒の空気過剰率が１以上に設定される場合）には、触媒保護の観点から、触媒を通流する改質ガスの流量を零に維持することが好ましい。 According to the above characteristic configuration, for example, when it is not necessary to increase the concentration of hydrogen as the highly ignitable gas contained in the reformed gas, the quasi-highly ignitable reformed gas recirculation is performed as the reformed gas recirculation operation state. In the operating state and the reference ignitable reformed gas recirculation operation state, the flow rate of the reformed gas flowing through the catalyst while controlling the hydrogen concentration as the highly ignitable gas contained in the reformed gas to a desired value By setting the value to zero, deterioration of the catalyst can be prevented.
Further, for example, when it is necessary to make the concentration of hydrogen as a highly ignitable gas contained in the reformed gas higher than the concentration of hydrogen that can be generated in the reformed gas recirculation operation state, the reforming through the catalyst is performed. By controlling the gas flow rate in a range larger than zero, the concentration of hydrogen as a highly ignitable gas contained in the reformed gas can be made sufficiently high.
The flow of the reformed gas to the catalyst is a minimum excess air ratio within a range in which misfire does not occur in the recirculation cylinder in the highly ignitable reformed gas recirculation operation state. Furthermore, it is preferable to carry out.
When the exhaust gas recirculation operation state is not set (when the excess air ratio of the recirculation cylinder is set to 1 or more), the flow rate of the reformed gas flowing through the catalyst is maintained at zero from the viewpoint of catalyst protection. It is preferable to do.

エンジンシステムの更なる特徴構成は、
前記再循環気筒から前記通常気筒へ導かれる前記燃焼ガスを通流すると共に前記触媒が設けられる触媒流路を備え、
前記着火性制御手段は、前記改質ガス再循環運転状態にて設定される前記再循環気筒での空気過剰率に関わらず、前記燃焼ガスの全量を前記触媒へ通流する点にある。 Further characteristic configuration of the engine system
A catalyst flow path for passing the combustion gas guided from the recirculation cylinder to the normal cylinder and provided with the catalyst;
The ignitability control means is such that the entire amount of the combustion gas flows to the catalyst regardless of the excess air ratio in the recirculation cylinder set in the reformed gas recirculation operation state.

上記構成を採用することで、例えば、触媒をバイパスするバイパス路や触媒を通流する改質ガスの流量を制御する制御弁を備えない簡易な構成を採用しながらも、改質ガスに含まれる高着火性ガスとしての水素の濃度を、零から十分に高い値（例えば、１２．４％程度）の広い範囲で、好適に設定することができる。   By adopting the above configuration, for example, a simple configuration that does not include a bypass passage that bypasses the catalyst and a control valve that controls the flow rate of the reformed gas that flows through the catalyst is included in the reformed gas. The concentration of hydrogen as a highly ignitable gas can be suitably set within a wide range from zero to a sufficiently high value (for example, about 12.4%).

第１実施形態に係る予混合圧縮着火エンジンの概略構成図1 is a schematic configuration diagram of a premixed compression ignition engine according to a first embodiment. 詳細化学反応計算による予混合圧縮着火運転状態と、排ガス再循環運転状態と、改質ガス再循環運転状態の夫々における着火温度を示すグラフ図The graph which shows the ignition temperature in each of the premixed compression ignition operation state, exhaust gas recirculation operation state, and reformed gas recirculation operation state by detailed chemical reaction calculation 通常の予混合圧縮着火運転状態（基準着火性改質ガス再循環運転状態に対応）における運転可能範囲を示すグラフ図A graph showing the operable range in the normal premixed compression ignition operation state (corresponding to the standard ignitable reformed gas recirculation operation state) 排ガス再循環運転状態における運転可能範囲を示すグラフ図Graph showing the operating range in the exhaust gas recirculation operation state 高着火性改質ガス再循環運転状態における運転可能範囲を示すグラフ図The graph which shows the operation possible range in the high ignitability reformed gas recirculation operation state 運転可能範囲の低負荷側限界（左側限界）をＣＯＶ ｏｆ ＩＭＥＰ＝５％とし、運転可能範囲の高負荷側限界（右側限界）をＫＩ＝１００ｋＰａとした場合に、排ガス再循環運転状態と高着火性改質ガス再循環運転状態と基準着火性改質ガス再循環運転状態との夫々の運転可能範囲を重畳表示した場合のグラフ図When the low load side limit (left limit) of the operable range is set to COV of IMEP = 5% and the high load side limit (right limit) of the operable range is set to KI = 100 kPa, the exhaust gas recirculation operation state and high ignition are set. Graph when the operable range of the basic reforming gas recirculation operation state and the reference ignitable reforming gas recirculation operation state are displayed in a superimposed manner 運転可能範囲の低負荷側限界（左側限界）をηｉ＝４０％とし、運転可能範囲の高負荷側限界（右側限界）をＮＯｘ＝５０ｐｐｍとした場合に、排ガス再循環運転状態と高着火性改質ガス再循環運転状態と基準着火性改質ガス再循環運転状態との夫々の運転可能範囲を重畳表示した場合のグラフ図When the low load side limit (left side limit) of the operable range is ηi = 40% and the high load side limit (right side limit) of the operable range is NOx = 50 ppm, the exhaust gas recirculation operation state and high ignitability improvement Graph when the operating range of the gas gas recirculation operation state and the reference ignitable reformed gas recirculation operation state are displayed in a superimposed manner 改質ガスに対する、水素、一酸化炭素及びアセチレン等を含む高着火性ガスの含有割合の混合気の当量比依存性を示すグラフ図The graph which shows the equivalence ratio dependence of the gas mixture of the content rate of the highly ignitable gas containing hydrogen, carbon monoxide, acetylene, etc. with respect to reformed gas 第１実施形態及び第２実施形態において、改質ガスに含まれる高着火性ガスとしての水素濃度の当量比依存性を示すグラフ図The graph which shows the equivalence ratio dependence of the hydrogen concentration as highly ignitable gas contained in reformed gas in 1st Embodiment and 2nd Embodiment 各給気温度における着火時期の改質ガスに含まれる水素濃度依存性を示すグラフ図The graph which shows the hydrogen concentration dependence in the reformed gas of the ignition timing in each supply air temperature 第２実施形態に係る予混合圧縮着火エンジンの概略構成図Schematic configuration diagram of a premixed compression ignition engine according to a second embodiment 別実施形態に係る予混合圧縮着火エンジンの概略構成図Schematic configuration diagram of a premixed compression ignition engine according to another embodiment 別実施形態に係る予混合圧縮着火エンジンの概略構成図Schematic configuration diagram of a premixed compression ignition engine according to another embodiment

〔第１実施形態〕
第１実施形態に係るエンジンシステム１００、及びその制御方法は、図１に示すように、燃焼室に給気された燃料ガスＦ（例えば、都市ガス１３Ａ）と燃焼用空気Ａとの混合気Ｍを圧縮着火させ燃焼させる予混合圧縮着火エンジン本体４０に、混合気Ｍを燃焼する通常気筒４０ａ、４０ｂ、４０ｃと、混合気Ｍを含む混合気を点火プラグ（図示せず）により火花点火して燃焼すると共に燃焼後の燃焼ガス（後述する改質ガスＫ、燃焼排ガスＥを含む概念）を通常気筒４０ａ、４０ｂ、４０ｃへ再循環可能な再循環気筒４０ｄとを備えたエンジンにおいて、比較的簡易な構成を維持しながらも、着火性の制御を良好に行うことができると共に、その運転可能範囲を拡大できるエンジンシステム、及びその制御方法に関するものである。 [First Embodiment]
As shown in FIG. 1, the engine system 100 according to the first embodiment and the control method thereof include an air-fuel mixture M of fuel gas F (for example, city gas 13A) supplied to the combustion chamber and combustion air A. The premixed compression ignition engine body 40 for compressing and igniting the fuel is spark-ignited with normal cylinders 40a, 40b and 40c for combusting the air-fuel mixture M, and the air-fuel mixture containing the air-fuel mixture M by an ignition plug (not shown). In an engine having a recirculation cylinder 40d that can combust and recirculate combustion gas (concept including reformed gas K and combustion exhaust gas E described later) to normal cylinders 40a, 40b, and 40c, it is relatively simple. The present invention relates to an engine system that can satisfactorily control ignitability while maintaining a simple configuration and can expand the operable range, and a control method therefor.

〔第１実施形態〕
以下、図１〜１０に基づいて、第１実施形態に係るエンジンシステム１００について説明する。
当該第１実施形態に係るエンジンシステム１００は、ターボ過給式のエンジンとして構成されており、少なくとも１つ以上（当該第１実施形態では３つ）の通常気筒４０ａ、４０ｂ、４０ｃと、少なくとも１つ以上（当該第１実施形態では１つ）の再循環気筒４０ｄとを備えている。更には、着火時期や燃焼状態を検出するセンサ等の測定結果が入力され、その入力信号に基づいてターボ過給式エンジンの運転を制御するハードウェア群とソフトウェア群とから構成されているエンジンコントロールユニット（以下、制御装置５０と呼ぶ）を備えている。 [First Embodiment]
Hereinafter, based on FIGS. 1-10, the engine system 100 which concerns on 1st Embodiment is demonstrated.
The engine system 100 according to the first embodiment is configured as a turbocharged engine, and includes at least one normal cylinder 40a, 40b, 40c (three in the first embodiment) and at least one. Two or more recirculation cylinders 40d (one in the first embodiment). Furthermore, an engine control composed of a hardware group and a software group for inputting a measurement result of a sensor or the like for detecting an ignition timing or a combustion state and controlling the operation of the turbocharged engine based on the input signal. A unit (hereinafter referred to as a control device 50) is provided.

当該エンジンシステム１００は、詳細な図示は省略するが、給気本管２０から通常気筒４０ａ、４０ｂ、４０ｃの燃焼室（図示せず）へ給気弁（図示せず）を介して給気した混合気Ｍを、ピストンの上昇により圧縮して発火点まで昇温させることで、混合気Ｍを自己着火させて燃焼・膨張させることで、ピストンを押し下げて回転軸（図示せず）から回転動力を出力すると共に、燃焼により発生した燃焼排ガスＥは、通常気筒４０ａ、４０ｂ、４０ｃの燃焼室から排気弁（図示せず）を介して排気路２７に押し出され、外部へ排出される。ちなみに、当該エンジンシステム１００は、予混合圧縮着火エンジン本体４０の回転軸に発電機（図示せず）を連結して発電する、所謂、コジェネレーションシステムとして構成されている。
当該予混合圧縮着火エンジン本体４０は、燃焼室に混合気Ｍを圧縮して自己着火させる予混合圧縮着火運転を行って混合気Ｍを燃焼させるため、例えば、圧縮比を２１程度と高く設定することができ高効率であり、更に混合気Ｍの空気過剰率を、例えば、火花伝播下限以下の希薄状態で燃焼させることができるため低ＮＯｘを実現できる。 Although not shown in detail in the engine system 100, the air is supplied from the supply main pipe 20 to the combustion chambers (not shown) of the normal cylinders 40a, 40b, and 40c via an intake valve (not shown). By compressing the air-fuel mixture M by raising the piston and raising the temperature to the ignition point, the air-fuel mixture M is self-ignited and combusted / expanded, and the piston is pushed down to rotate from the rotating shaft (not shown). The combustion exhaust gas E generated by the combustion is pushed out from the combustion chambers of the normal cylinders 40a, 40b, and 40c to the exhaust passage 27 via an exhaust valve (not shown) and discharged to the outside. Incidentally, the engine system 100 is configured as a so-called cogeneration system in which a generator (not shown) is connected to the rotation shaft of the premixed compression ignition engine body 40 to generate power.
The premixed compression ignition engine body 40 performs a premixed compression ignition operation in which the mixture M is compressed and self-ignited in the combustion chamber to burn the mixture M. For example, the compression ratio is set as high as about 21. In addition, since the excess air ratio of the air-fuel mixture M can be burned in a lean state below the lower limit of spark propagation, for example, low NOx can be realized.

尚、給気本管２０から供給される混合気Ｍは再循環気筒４０ｄにも供給され、当該再循環気筒４０ｄは、詳細については後述するが、混合気Ｍを点火プラグにより火花点火して燃焼・膨張させ、ピストンを押し下げて回転軸から回転動力を出力する。そして、当該再循環気筒４０ｄにて燃焼ガスとして生成される改質ガスＫ又は燃焼排ガスＥは、その全量が通常気筒４０ａ、４０ｂ、４０ｃへ導かれることとなる。   Note that the air-fuel mixture M supplied from the air supply main pipe 20 is also supplied to the recirculation cylinder 40d. The recirculation cylinder 40d is ignited by a spark plug with a spark plug and burned, as will be described in detail later.・ Expand and push down the piston to output rotational power from the rotating shaft. The entire amount of the reformed gas K or the combustion exhaust gas E generated as the combustion gas in the recirculation cylinder 40d is led to the normal cylinders 40a, 40b, and 40c.

給気本管２０には、燃焼用空気Ａを浄化するエアクリーナ２１、燃焼用空気Ａに燃料ガスＦを適切な比率（空燃比）で混合するベンチュリー式のミキサ１４、及びミキサ１４にて混合された混合気Ｍを圧縮する過給機３０としてのコンプレッサ３１、当該コンプレッサ３１の昇圧により昇温した混合気Ｍを冷却するインタークーラ２２、開度調整により通常気筒４０ａ、４０ｂ、４０ｃ及び再循環気筒４０ｄへの混合気Ｍの給気量を調整可能なスロットル弁２３が、その上流側から記載の順に設けられている。
即ち、給気本管２０において、ミキサ１４で都市ガス等の燃料ガスＦと燃焼用空気Ａとを混合して生成された混合気Ｍは、過給機３０としてのコンプレッサ３１にて圧縮された後に、インタークーラ２２にて冷却され、スロットル弁２３を介して所定の流量に調整されて、通常気筒４０ａ、４０ｂ、４０ｃ、及び再循環気筒４０ｄの燃焼室へ導入される。 The supply main pipe 20 is mixed by an air cleaner 21 for purifying the combustion air A, a venturi mixer 14 for mixing the fuel gas F with the combustion air A at an appropriate ratio (air-fuel ratio), and a mixer 14. A compressor 31 as a supercharger 30 for compressing the air-fuel mixture M, an intercooler 22 for cooling the air-fuel mixture M heated by the pressure increase of the compressor 31, normal cylinders 40a, 40b, 40c and recirculation cylinders by adjusting the opening A throttle valve 23 capable of adjusting the amount of air-fuel mixture M supplied to 40d is provided in the order described from the upstream side.
That is, in the supply main pipe 20, the air-fuel mixture M generated by mixing the fuel gas F such as city gas and the combustion air A by the mixer 14 is compressed by the compressor 31 as the supercharger 30. Thereafter, it is cooled by the intercooler 22, adjusted to a predetermined flow rate via the throttle valve 23, and introduced into the combustion chambers of the normal cylinders 40a, 40b, 40c and the recirculation cylinder 40d.

ミキサ１４に燃料ガスＦを導く第１燃料ガス供給路１１には、ミキサ１４の上流側の給気本管２０における燃焼用空気Ａの圧力と第１燃料ガス供給路１１における燃料ガスＦの圧力差を一定に保つ差圧レギュレータ１２、ミキサ１４を介して通常気筒４０ａ、４０ｂ、４０ｃ及び再循環気筒４０ｄの燃焼室へ供給される燃料ガスＦの供給量を調整する第１燃料流量制御弁１３が設けられている。即ち、第１燃料ガス供給路１１、差圧レギュレータ１２、ミキサ１４、及び第１燃料流量制御弁１３が、少なくとも通常気筒４０ａ、４０ｂ、４０ｃへ燃料ガスを供給する第１燃料ガス供給部として機能する。   In the first fuel gas supply path 11 for introducing the fuel gas F to the mixer 14, the pressure of the combustion air A in the supply main pipe 20 upstream of the mixer 14 and the pressure of the fuel gas F in the first fuel gas supply path 11 are provided. A first fuel flow control valve 13 that adjusts the supply amount of the fuel gas F supplied to the combustion chambers of the normal cylinders 40a, 40b, 40c and the recirculation cylinder 40d via the differential pressure regulator 12 and the mixer 14 that keep the difference constant. Is provided. That is, the first fuel gas supply path 11, the differential pressure regulator 12, the mixer 14, and the first fuel flow control valve 13 function as a first fuel gas supply unit that supplies fuel gas to at least the normal cylinders 40a, 40b, and 40c. To do.

過給機３０は、通常気筒４０ａ、４０ｂ、４０ｃに接続される排気路２７に設けられる排気タービン３２に、通常気筒４０ａ、４０ｂ、４０ｃから排出される燃焼排ガスＥを供給し、排気タービン３２に連結される状態で給気本管２０に設けられるコンプレッサ３１により、通常気筒４０ａ、４０ｂ、４０ｃ及び再循環気筒４０ｄの燃焼室に給気される混合気Ｍを圧縮するターボ式の過給機３０として構成されている。即ち、当該過給機３０は、排気路２７を通流する燃焼排ガスＥの運動エネルギにより排気タービン３２を回転させ、当該排気タービン３２の回転力により給気本管２０を通流する新気としての混合気Ｍを圧縮して、通常気筒４０ａ、４０ｂ、４０ｃ及び再循環気筒４０ｄの燃焼室へ供給する、所謂、過給を行う。   The supercharger 30 supplies the combustion exhaust gas E discharged from the normal cylinders 40a, 40b, and 40c to the exhaust turbine 32 provided in the exhaust passage 27 connected to the normal cylinders 40a, 40b, and 40c. The turbocharger 30 compresses the air-fuel mixture M supplied to the combustion chambers of the normal cylinders 40a, 40b, 40c and the recirculation cylinder 40d by the compressor 31 provided in the supply main pipe 20 in a connected state. It is configured as. That is, the supercharger 30 rotates the exhaust turbine 32 by the kinetic energy of the combustion exhaust gas E flowing through the exhaust passage 27, and fresh air flows through the supply main pipe 20 by the rotational force of the exhaust turbine 32. The air-fuel mixture M is compressed and supplied to the combustion chambers of the normal cylinders 40a, 40b, 40c and the recirculation cylinder 40d.

予混合圧縮着火エンジン本体４０の回転軸（図示せず）には、当該回転軸（図示せず）の回転数を計測する回転数センサ（図示せず）が設けられており、制御装置５０は、当該回転数センサにて計測されるエンジン回転数を目標回転数に維持するべく、当該回転数センサの計測結果に基づいてスロットル弁２３の開度を制御する。
更に、予混合圧縮着火エンジン本体４０の回転軸（図示せず）には、当該回転軸のトルクを計測するトルク計測センサ（図示せず）が設けられており、制御装置５０は、例えば、回転数センサにて計測されるエンジン回転数と、トルク計測センサにて計測されるトルクに基づいて計算されるエンジン出力が目標出力となるように、第１燃料流量制御弁１３やスロットル弁２３の開度を制御する。
更に、予混合圧縮着火エンジン本体４０には、燃焼室での燃焼状態を検出する燃焼状態検出手段として、例えば５ｋＨｚから２５ｋＨｚまでの特定周波数帯域の振動の強度をノッキング関連値として検出可能なノックセンサ（図示せず）が設けられており、制御装置５０は、ノックセンサが検出する振動の強度がノッキング判定閾値（例えば、１００ｋＰａ）以上である場合に、ノッキングが発生していると判定する。
また、予混合圧縮着火エンジン本体４０には、燃焼室内の圧力を測定する筒内圧力センサ４１（着火時期検出手段の一例）を備え、着火時期判定部５２としての制御装置５０は、当該筒内圧力センサ４１にて測定される圧力が着火判定圧力を超えた時を着火時期として判定する。 The rotation shaft (not shown) of the premixed compression ignition engine body 40 is provided with a rotation speed sensor (not shown) for measuring the rotation speed of the rotation shaft (not shown). The opening degree of the throttle valve 23 is controlled based on the measurement result of the rotation speed sensor in order to maintain the engine rotation speed measured by the rotation speed sensor at the target rotation speed.
Further, a torque measuring sensor (not shown) for measuring the torque of the rotating shaft (not shown) is provided on the rotating shaft (not shown) of the premixed compression ignition engine main body 40. The first fuel flow control valve 13 and the throttle valve 23 are opened so that the engine output calculated based on the engine speed measured by the number sensor and the torque measured by the torque measurement sensor becomes the target output. Control the degree.
Further, the premixed compression ignition engine main body 40 has a knock sensor capable of detecting, for example, the intensity of vibration in a specific frequency band from 5 kHz to 25 kHz as a knocking-related value as combustion state detection means for detecting the combustion state in the combustion chamber. (Not shown) is provided, and the control device 50 determines that knocking has occurred when the intensity of vibration detected by the knock sensor is equal to or greater than a knocking determination threshold (for example, 100 kPa).
The premixed compression ignition engine body 40 includes an in-cylinder pressure sensor 41 (an example of an ignition timing detection unit) that measures the pressure in the combustion chamber, and the control device 50 as the ignition timing determination unit 52 includes the in-cylinder pressure sensor 41. When the pressure measured by the pressure sensor 41 exceeds the ignition determination pressure, the ignition timing is determined.

また、予混合圧縮着火エンジン本体４０の排気路２７には、排気路２７で排気タービン３２の上流側を通流する燃焼排ガスＥの温度を検出する温度センサＳ２が設けられており、制御装置５０は、当該温度センサＳ２にて検出される燃焼排ガス温度が失火判定閾値以下となる場合に、失火が発生していると判定する。
尚、失火とは、着火していてもトルクの変動が大きい状態（燃焼変動が大きい状態）も含むものとする。 In addition, the exhaust passage 27 of the premixed compression ignition engine body 40 is provided with a temperature sensor S2 for detecting the temperature of the combustion exhaust gas E flowing through the exhaust passage 27 upstream of the exhaust turbine 32, and the control device 50. Determines that a misfire has occurred when the combustion exhaust gas temperature detected by the temperature sensor S2 is equal to or lower than the misfire determination threshold.
In addition, misfire includes a state in which torque variation is large even when ignition is performed (a state in which combustion variation is large).

給気本管２０は、スロットル弁２３の下流側において、通常気筒４０ａ、４０ｂ、４０ｃへ混合気Ｍを導く第１給気支管２０ｘと、再循環気筒４０ｄへ混合気Ｍを導く第２給気支管２０ｄとに分岐されている。更に、第１給気支管２０ｘは、通常気筒４０ａ、４０ｂ、４０ｃの夫々へ混合気Ｍを導く複数の通常気筒用給気支管２０ａ、２０ｂ、２０ｃに接続されている。   The supply main pipe 20 includes a first supply branch pipe 20x that guides the mixture M to the normal cylinders 40a, 40b, and 40c and a second supply air that guides the mixture M to the recirculation cylinder 40d on the downstream side of the throttle valve 23. It branches off to the branch pipe 20d. Further, the first air supply branch pipe 20x is connected to a plurality of normal cylinder air supply branch pipes 20a, 20b, and 20c that guide the air-fuel mixture M to the respective normal cylinders 40a, 40b, and 40c.

再循環気筒４０ｄへ新気を供給する第２給気支管２０ｄには、ベンチュリー式のミキサ１６を介する形態で燃料ガスＦを供給する第２燃料ガス供給路２９が接続されており、当該第２燃料ガス供給路２９には、都市ガス１３Ａ等の燃料ガスＦの流量を制御する第２燃料流量制御弁１５が設けられている。第２燃料ガス供給路２９の第２燃料流量制御弁１５の上流側には、燃料ガスＦの供給圧を給気本管２０のコンプレッサ３１出口の過給圧まで昇圧するべく、圧縮機（図示せず）等が設けられている。
尚、詳細については後述するが、当該第１実施形態にあっては、再循環気筒４０ｄでの燃焼用空気Ａに含まれる酸素に対する燃料ガスＦの供給比率を制御する形態の一例として、制御装置５０が、第２燃料流量制御弁１５の開度を制御する形態で、再循環気筒４０ｄへ供給される混合気Ｍの空気過剰率を調整可能に構成されている。つまり、第２燃料ガス供給路２９、ミキサ１６、及び第２燃料流量制御弁１５が、第２燃料ガス供給部として機能する。これにより、再循環気筒４０ｄからは、再循環気筒４０ｄでの混合気Ｍの空気過剰率を１より小さくするときには、再循環気筒４０ｄにて混合気Ｍの少なくとも一部が燃焼して部分酸化反応して、水素、一酸化炭素及びアセチレン等を含み、燃料ガスＦよりも着火性の高い高着火性ガスが含まれる改質ガスＫが生成され、第２燃料流量制御弁１５を閉止して燃料ガスＦを供給しないときには、改質ガスＫがほぼ含まれない燃焼排ガスＥが排出されることになる。 A second fuel gas supply passage 29 that supplies fuel gas F in a form through a venturi mixer 16 is connected to the second supply branch pipe 20d that supplies fresh air to the recirculation cylinder 40d. The fuel gas supply path 29 is provided with a second fuel flow rate control valve 15 that controls the flow rate of the fuel gas F such as the city gas 13A. On the upstream side of the second fuel flow rate control valve 15 in the second fuel gas supply path 29, a compressor (see FIG. 5) is provided to increase the supply pressure of the fuel gas F to the supercharging pressure at the outlet of the compressor 31 of the supply main pipe 20. Etc.) are provided.
Although details will be described later, in the first embodiment, as an example of a mode for controlling the supply ratio of the fuel gas F to the oxygen contained in the combustion air A in the recirculation cylinder 40d, the control device 50 is a mode for controlling the opening degree of the second fuel flow rate control valve 15, and is configured to be able to adjust the excess air ratio of the air-fuel mixture M supplied to the recirculation cylinder 40d. That is, the second fuel gas supply path 29, the mixer 16, and the second fuel flow rate control valve 15 function as a second fuel gas supply unit. Accordingly, when the excess air ratio of the air-fuel mixture M in the recirculation cylinder 40d is made smaller than 1 from the recirculation cylinder 40d, at least a part of the air-fuel mixture M burns in the recirculation cylinder 40d and the partial oxidation reaction Then, the reformed gas K containing hydrogen, carbon monoxide, acetylene, etc. and containing a highly ignitable gas having a higher ignitability than the fuel gas F is generated, and the second fuel flow control valve 15 is closed to produce fuel. When the gas F is not supplied, the combustion exhaust gas E that does not substantially contain the reformed gas K is discharged.

再循環気筒４０ｄには、再循環気筒４０ｄからの燃焼ガスとしての改質ガスＫ又は燃焼排ガスＥを通流する燃焼ガス通流路２８が接続されており、当該燃焼ガス通流路２８には、その下流側が第１給気支管２０ｘに接続される流路部位と、その下流側が排気路２７に接続される流路部位とが、三方切換弁９０を介して設けられている。そして、制御装置５０は、当該三方切換弁９０の開度状態を切り換える形態で、再循環気筒４０ｄからの燃焼ガスを通常気筒４０ａ、４０ｂ、４０ｃへ戻す状態と、再循環気筒４０ｄからの燃焼ガスを排気路２７へ戻す状態とを切り換え可能に構成されている。ちなみに、当該第１実施形態にあっては、燃焼ガスは、すべて通常気筒４０ａ、４０ｂ、４０ｃへ戻すように、三方切換弁９０が切り換え制御される。
尚、燃焼ガス通流路２８の第１給気支管２０ｘに接続される流路部位には、燃焼ガスを冷却するためのＥＧＲクーラ９１が設けられており、当該ＥＧＲクーラ９１では、燃焼ガスが第１給気支管２０ｘの新気に混合されたときに結露しない温度まで、燃焼ガスを冷却する。 The recirculation cylinder 40d is connected to a combustion gas passage 28 through which the reformed gas K or the combustion exhaust gas E as the combustion gas from the recirculation cylinder 40d flows. A flow path portion whose downstream side is connected to the first air supply branch pipe 20 x and a flow path portion whose downstream side is connected to the exhaust passage 27 are provided via a three-way switching valve 90. The control device 50 switches the opening state of the three-way switching valve 90, returns the combustion gas from the recirculation cylinder 40d to the normal cylinders 40a, 40b, and 40c, and the combustion gas from the recirculation cylinder 40d. Can be switched between the state of returning to the exhaust passage 27. Incidentally, in the first embodiment, the three-way switching valve 90 is controlled so that all the combustion gas is returned to the normal cylinders 40a, 40b, and 40c.
In addition, an EGR cooler 91 for cooling the combustion gas is provided in a flow path portion connected to the first supply branch pipe 20x of the combustion gas flow path 28, and in the EGR cooler 91, the combustion gas is The combustion gas is cooled to a temperature at which condensation does not occur when mixed with fresh air in the first air supply branch pipe 20x.

更に、第１給気支管２０ｘで、燃焼ガス通流路２８が接続される部位の下流側には、第１給気支管２０ｘを通流する混合気Ｍの温度を測定する温度センサＳ１が設けられており、当該温度センサＳ１により測定される温度は、着火性制御手段５１としての制御装置５０が、着火時期を制御する際に用いられる。   Further, a temperature sensor S1 for measuring the temperature of the air-fuel mixture M flowing through the first air supply branch pipe 20x is provided downstream of the portion of the first air supply branch pipe 20x to which the combustion gas flow path 28 is connected. The temperature measured by the temperature sensor S1 is used when the control device 50 as the ignitability control means 51 controls the ignition timing.

燃焼ガス通流路２８で下流側が第１給気支管２０ｘに接続される流路部位（触媒流路の一例）で、ＥＧＲクーラ９１の上流側の流路部位（ＥＧＲクーラ９１と再循環気筒４０ｄとの間の流路部位：より具体的にはＥＧＲクーラ９１と三方切換弁９０との間の流路部位）には、改質ガスＫの少なくとも一部を以下の〔式１〕に示す水性ガスシフト反応させる触媒９２を備えている。当該触媒９２としては、酸化鉄、酸化クロム、酸化銅、酸化亜鉛などが例示されるが、水性ガスシフト反応させるものであれば、どのようなものでも適用できる。   The combustion gas flow passage 28 is a flow passage portion (an example of a catalyst flow passage) connected to the first supply branch pipe 20x on the downstream side, and a flow passage portion upstream of the EGR cooler 91 (EGR cooler 91 and recirculation cylinder 40d). In the flow path part between: and more specifically, in the flow path part between the EGR cooler 91 and the three-way switching valve 90), at least a part of the reformed gas K is represented by the following [Formula 1] A catalyst 92 for gas shift reaction is provided. Examples of the catalyst 92 include iron oxide, chromium oxide, copper oxide, and zinc oxide, but any catalyst can be used as long as it can cause a water gas shift reaction.

ＣＯ＋Ｈ2Ｏ→ＣＯ2＋Ｈ2・・・〔式１〕 CO + H 2 O → CO 2 + H 2 (Equation 1)

更に、燃焼ガス通流路２８で下流側が第１給気支管２０ｘに接続される流路部位（触媒流路）を通流する燃焼ガスに触媒９２をバイパスさせる触媒バイパス路９４を備えると共に、燃焼ガス通流路２８で下流側が第１給気支管２０ｘに接続される流路部位を通流する燃焼ガスと触媒バイパス路９４を通流する燃焼ガスとの流量比を制御する流量比制御弁９３を備えている。流量比制御弁９３は、触媒バイパス路９４にてバイパスされる触媒流路の開度を制御して触媒流路を通流する燃焼ガスの流量を制御する流量制御弁として設けられている。より具体的には、燃焼ガス通流路２８で下流側が第１給気支管２０ｘに接続される流路部位で、触媒９２の上流側の流路部位（触媒９２と再循環気筒４０ｄとの間の流路部位：より具体的には触媒９２と三方切換弁９０との間の流路部位）に設けられており、当該流路部位にて開度を制御する形態で、触媒９２を通流する燃焼ガスと触媒バイパス路９４を通流する燃焼ガスとの流量比を制御する。   Further, the combustion gas passage 28 is provided with a catalyst bypass passage 94 for bypassing the catalyst 92 to the combustion gas flowing through the passage portion (catalyst passage) downstream of the combustion gas passage 28 and connected to the first supply branch pipe 20x. A flow rate control valve 93 that controls the flow rate ratio of the combustion gas flowing through the flow path portion connected downstream to the first air supply branch pipe 20x and the combustion gas flowing through the catalyst bypass passage 94 in the gas flow path 28. It has. The flow ratio control valve 93 is provided as a flow control valve that controls the flow rate of the combustion gas flowing through the catalyst flow path by controlling the opening of the catalyst flow path that is bypassed by the catalyst bypass path 94. More specifically, the combustion gas passage 28 is connected to the first supply branch pipe 20x on the downstream side, and the upstream side of the catalyst 92 (between the catalyst 92 and the recirculation cylinder 40d). The flow path part: more specifically, the flow path part between the catalyst 92 and the three-way switching valve 90), and the opening of the flow path is controlled in the flow path part. The flow rate ratio between the combustion gas flowing through and the combustion gas flowing through the catalyst bypass 94 is controlled.

尚、各運転状態の詳細は後述するが、図２に、縦軸を筒内ガス温度とし、横軸をクランク角度として、予混合圧縮着火エンジンの通常の予混合圧縮着火運転状態と、改質ガス再循環運転状態（ここでは、通常気筒４０ａ、４０ｂ、４０ｃへ燃焼ガスを再循環しない場合の通常気筒４０ａ、４０ｂ、４０ｃでの混合気の着火性である基準着火性よりも高い着火性の改質ガスを再循環させる高着火性改質ガス再循環運転状態を意味するものとする：図２で一点鎖線）と、改質ガスよりも着火性の低い燃焼排ガスを再循環させる排ガス再循環運転状態との夫々において、詳細化反応計算により導出した、クランク角度に応じて筒内ガス温度の変化のグラフ図を示す。因みに、図２では、温度変化が変曲する点（図２にプロット）を着火点と定義し、当該着火点での筒内ガス温度を着火温度とする。
さて、本願の発明者らは、鋭意検討した結果、図２の詳細化学反応計算の結果に示すように、圧縮・膨張行程において、通常の予混合圧縮着火エンジンの予混合圧縮着火運転状態における着火温度に対して、排ガス再循環運転状態における着火温度を高く（着火性を低く）できると共に、改質ガス再循環運転状態における着火温度を低く（着火性を高く）できるという新たな知見を得た。因みに、当該詳細化学反応計算は、圧縮比を２６、当量比を０．３、改質ガスＫに含まれる水素濃度を８％、給気量に対する改質ガスＫ又は燃焼排ガスＥの再循環量の割合を２０％とした場合の計算結果である。 Details of each operation state will be described later. In FIG. 2, the normal premixed compression ignition operation state of the premixed compression ignition engine and the reforming are shown in FIG. 2 where the vertical axis represents the in-cylinder gas temperature and the horizontal axis represents the crank angle. Gas recirculation operation state (here, the ignitability higher than the reference ignitability, which is the ignitability of the air-fuel mixture in the normal cylinders 40a, 40b, 40c when the combustion gas is not recirculated to the normal cylinders 40a, 40b, 40c) It means a highly ignitable reformed gas recirculation operation state in which the reformed gas is recirculated: a one-dot chain line in FIG. 2) and an exhaust gas recirculation that recirculates the combustion exhaust gas having a lower ignitability than the reformed gas. The graph figure of the change of in-cylinder gas temperature according to a crank angle derived | led-out by detailed reaction calculation in each of an operating state is shown. In FIG. 2, the point at which the temperature change is inflected (plotted in FIG. 2) is defined as the ignition point, and the in-cylinder gas temperature at the ignition point is defined as the ignition temperature.
Now, as a result of diligent study, the inventors of the present application, as shown in the result of detailed chemical reaction calculation in FIG. 2, ignite the normal premixed compression ignition engine in the premixed compression ignition operation state in the compression / expansion stroke. Obtained new knowledge that the ignition temperature in the exhaust gas recirculation operation state can be made higher (lower ignitability) than the temperature, and the ignition temperature in the reformed gas recirculation operation state can be made lower (high ignitability). . Incidentally, the detailed chemical reaction calculation shows that the compression ratio is 26, the equivalence ratio is 0.3, the hydrogen concentration contained in the reformed gas K is 8%, and the recirculation amount of the reformed gas K or the combustion exhaust gas E with respect to the supply air amount. This is a calculation result when the ratio is set to 20%.

そこで、当該第１実施形態に係るエンジンシステム１００及びその制御方法にあっては、上述の知見に基づき、制御装置５０が、再循環気筒４０ｄでの燃焼用空気に含まれる酸素に対する燃料ガスの供給比率を制御する形態で再循環気筒４０ｄでの混合気Ｍの空気過剰率を１より小さくする制御の一例として、第２燃料ガス供給部としての第２燃料流量制御弁１５の開度を特定の開度として再循環気筒４０ｄでの混合気Ｍの空気過剰率を１より小さくして、混合気Ｍの少なくとも一部を燃焼させ部分酸化反応させて、水素、一酸化炭素、及びアセチレン等を含み、燃料ガスよりも着火性の高い高着火性ガスが含まれる燃焼ガスとしての改質ガスＫを再循環気筒４０ｄにて生成して再循環させる改質ガス再循環運転状態と、再循環気筒４０ｄでの燃焼用空気に含まれる酸素に対する燃料ガスの供給比率を制御する形態で再循環気筒４０ｄでの混合気Ｍの空気過剰率を１以上として再循環気筒４０ｄから燃焼ガスとして改質ガスＫよりも着火性の低い燃焼排ガスＥを再循環させる排ガス再循環運転状態とを切り換え制御する。   Therefore, in the engine system 100 and the control method thereof according to the first embodiment, based on the above knowledge, the control device 50 supplies fuel gas to oxygen contained in the combustion air in the recirculation cylinder 40d. As an example of control for reducing the excess air ratio of the air-fuel mixture M in the recirculation cylinder 40d to be less than 1 in the form of controlling the ratio, the opening degree of the second fuel flow rate control valve 15 as the second fuel gas supply unit is specified. As the opening degree, the excess air ratio of the air-fuel mixture M in the recirculation cylinder 40d is made smaller than 1, and at least a part of the air-fuel mixture M is burned and partially oxidized, thereby including hydrogen, carbon monoxide, acetylene, etc. A reformed gas recirculation operation state in which the reformed gas K as a combustion gas containing a highly ignitable gas having higher ignitability than the fuel gas is generated and recirculated in the recirculation cylinder 40d, and the recirculation cylinder 40d so In the form of controlling the supply ratio of the fuel gas to the oxygen contained in the combustion air, the excess air ratio of the air-fuel mixture M in the recirculation cylinder 40d is set to 1 or more and ignition from the recirculation cylinder 40d as the combustion gas is performed more than the reformed gas K. The exhaust gas recirculation operation state in which the combustion exhaust gas E having low properties is recirculated is switched and controlled.

更に、制御装置５０は、改質ガス再循環運転状態に切り換えているときに、再循環気筒４０ｄでの燃焼用空気に含まれる酸素に対する燃料ガスの供給比率を制御する形態で再循環気筒４０ｄでの混合気Ｍの空気過剰率を１より小さい範囲で制御する空気過剰率制御の一例として、第２燃料流量制御弁１５の開度を調整して、再循環気筒４０ｄでの混合気Ｍの空気過剰率を１より小さい範囲で制御する形態で、通常気筒４０ａ、４０ｂ、４０ｃでの着火性を制御する着火性制御手段としても機能する。   Further, the control device 50 controls the supply ratio of the fuel gas to the oxygen contained in the combustion air in the recirculation cylinder 40d when the recirculation cylinder 40d is switched to the reformed gas recirculation operation state. As an example of the excess air ratio control for controlling the excess air ratio of the air-fuel mixture M within a range smaller than 1, the opening of the second fuel flow control valve 15 is adjusted to adjust the air in the air-fuel mixture M in the recirculation cylinder 40d. It functions as an ignitability control means for controlling the ignitability in the normal cylinders 40a, 40b, 40c in a form in which the excess ratio is controlled within a range smaller than 1.

因みに、当該第１実施形態にあっては、着火性制御手段５１としての制御装置５０は、上述した空気過剰率制御に加え、改質ガス再循環運転状態において改質ガスＫの少なくとも一部を触媒９２へ通流させる水性ガスシフト反応制御を実行するシフト反応制御手段として働くように構成されている。ただし、当該第１実施形態にあっては、改質ガス再循環運転状態において設定される空気過剰率が再循環気筒４０ｄで失火が起きない範囲で最小の空気過剰率である下限空気過剰率（当該第１実施形態では、図９において一点鎖線で示すように、当量比が１．５のとき）であるときに、触媒９２に改質ガスＫを通流させるように制御される。
そこで、以下の説明においては、再循環気筒４０ｄでの混合気の空気過剰率が下限空気過剰率よりも大きい場合で、触媒９２に改質ガスＫを通流させない場合の制御について、まず説明する。 Incidentally, in the first embodiment, the control device 50 as the ignitability control means 51, in addition to the above-described excess air ratio control, supplies at least a part of the reformed gas K in the reformed gas recirculation operation state. It is configured to function as a shift reaction control means for executing a water gas shift reaction control to flow to the catalyst 92. However, in the first embodiment, the lower excess air ratio (the excess air ratio set in the reformed gas recirculation operation state is the minimum excess air ratio in a range where misfire does not occur in the recirculation cylinder 40d ( In the first embodiment, the reformed gas K is controlled to flow through the catalyst 92 when the equivalence ratio is 1.5 (as indicated by a one-dot chain line in FIG. 9).
Therefore, in the following description, control in the case where the excess air ratio of the air-fuel mixture in the recirculation cylinder 40d is larger than the lower limit excess air ratio and the reformed gas K does not flow through the catalyst 92 will be described first. .

制御装置５０は、再循環状態を、着火性が高い改質ガス再循環運転状態と、着火性が低い排ガス再循環運転状態とで切り換えると共に、改質ガス再循環運転状態に切り換えているときに、第２燃料流量制御弁１５の開度を調整して、再循環気筒４０ｄでの混合気Ｍの空気過剰率を１より小さい範囲で制御することで、エンジンシステム１００の着火性を良好に制御する。   The control device 50 switches the recirculation state between the reformed gas recirculation operation state with high ignitability and the exhaust gas recirculation operation state with low ignitability, and when switching to the reformed gas recirculation operation state. By adjusting the opening degree of the second fuel flow control valve 15 and controlling the excess air ratio of the air-fuel mixture M in the recirculation cylinder 40d within a range smaller than 1, the ignitability of the engine system 100 is controlled well. To do.

ちなみに、図８に、排ガス再循環運転状態（図８で、通常ＥＧＲ）と、改質ガス再循環運転状態（図８で、改質ＥＧＲ）との双方において、燃焼ガス（改質ガスＫ及び燃焼排ガスＥを含む）に含まれる水素、一酸化炭素、及び炭化水素（アセチレン含む）の混合割合を示す。ちなみに、当該データは、トルクが最大となる点火時期で、１．３６ｋＪ／ｃｙｃｌｅで運転したときに、再循環気筒のみから排出される燃焼ガスの実測データである。
図８に示すように、排ガス再循環運転状態（図８で、通常ＥＧＲ）では、水素等の高着火性ガスの燃焼ガスに対する割合は、ほぼ零であるが、改質ガス再循環運転状態（図８で、改質ＥＧＲ）で、当量比を１から増加（空気過剰率を１から減少）させるに従って、水素等の高着火性ガスの燃焼ガスに対する割合は、徐々に増加していることがわかる。因みに、当量比が１．５を超える場合には、再循環気筒で失火が発生するようになる。エンジンの運転状態や給気温度等の外部環境にもよるが、本発明のエンジンシステム１００における改質ガス再循環運転状態における再循環気筒での当量比は、１より大きく１．５以下（空気過剰率は、０．６７以上で１未満）であると言える。
尚、図８のグラフ図にあっては、排ガス再循環運転状態（図８で、通常ＥＧＲ）は、当量比が１．０の場合を指しているが、本発明にあっては、当量比が１．０未満（空気過剰率が１より大きい）のものも含むものとする。 Incidentally, FIG. 8 shows combustion gases (reformed gas K and reformed gas K and both in the exhaust gas recirculation operation state (normal EGR in FIG. 8) and the reformed gas recirculation operation state (reformed EGR in FIG. 8). The mixing ratio of hydrogen, carbon monoxide, and hydrocarbon (including acetylene) contained in (including combustion exhaust gas E) is shown. Incidentally, the data is measured data of combustion gas discharged only from the recirculation cylinder when operating at 1.36 kJ / cycle at the ignition timing at which the torque becomes maximum.
As shown in FIG. 8, in the exhaust gas recirculation operation state (usually EGR in FIG. 8), the ratio of highly ignitable gas such as hydrogen to the combustion gas is almost zero, but the reformed gas recirculation operation state ( In FIG. 8, the ratio of the highly ignitable gas such as hydrogen to the combustion gas gradually increases as the equivalence ratio is increased from 1 (the excess air ratio is decreased from 1) in reformed EGR). Recognize. Incidentally, when the equivalence ratio exceeds 1.5, misfire occurs in the recirculation cylinder. The equivalence ratio in the recirculation cylinder in the reformed gas recirculation operation state in the engine system 100 of the present invention is greater than 1 and 1.5 or less (air), depending on the external environment such as the engine operation state and the supply air temperature. It can be said that the excess ratio is 0.67 or more and less than 1.
In the graph of FIG. 8, the exhaust gas recirculation operation state (usually EGR in FIG. 8) indicates the case where the equivalence ratio is 1.0, but in the present invention, the equivalence ratio is Of less than 1.0 (excess air ratio is greater than 1).

更に、当該第１実施形態にあっては、制御装置５０は、第２燃料流量制御弁１５の開度を調整して、再循環気筒４０ｄでの燃焼用空気Ａに含まれる酸素に対する燃料ガスＦの供給比率を制御する形態で再循環気筒４０ｄでの混合気Ｍの空気過剰率を１より小さい範囲で制御することで、通常気筒４０ａ、４０ｂ、４０ｃへ燃焼ガスを再循環しない場合（上述した三方切換弁９０にて燃焼ガスを排気路２７の側へ導く制御を実行する場合）の通常気筒４０ａ、４０ｂ、４０ｃでの混合気Ｍの着火性を基準着火性としたときに、基準着火性よりも高い着火性の改質ガスＫを再循環させる高着火性改質ガス再循環運転状態と、基準着火性と同一の着火性の改質ガスＫを再循環させる基準着火性改質ガス再循環運転状態とを、改質ガス再循環運転状態として実行可能に構成されている。
即ち、制御装置５０（再循環状態切換手段の一例）は、第２燃料流量制御弁１５の開度を連続的に調整する制御のみにより、再循環気筒４０ｄでの燃焼用空気に含まれる酸素に対する燃料ガスの供給比率を制御する形態で、再循環気筒４０ｄでの混合気Ｍの空気過剰率を１より小さい範囲で制御することで、高着火性改質ガス再循環運転状態と、基準着火性改質ガス再循環運転状態と、排ガス再循環運転状態とを切り換え制御するように構成されている。
因みに、制御装置５０は、基準着火性改質ガス再循環運転状態では、改質ガスＫにおいて、高着火性ガスによる着火性を向上させる効果と、比較的比熱の高い二酸化炭素や水蒸気等による着火性を低減させる効果とがバランスする程度に、改質ガスＫに含まれる高着火性ガスの割合を制御するように、第２燃料流量制御弁１５の開度を調整する。 Further, in the first embodiment, the control device 50 adjusts the opening degree of the second fuel flow rate control valve 15, and the fuel gas F with respect to oxygen contained in the combustion air A in the recirculation cylinder 40d. When the excess air ratio of the air-fuel mixture M in the recirculation cylinder 40d is controlled within a range smaller than 1 in the form of controlling the supply ratio of the combustion gas, the combustion gas is not recirculated to the normal cylinders 40a, 40b, 40c (described above) Reference ignitability when the ignitability of the air-fuel mixture M in the normal cylinders 40a, 40b, and 40c is set as the reference ignitability when the three-way switching valve 90 performs control for guiding combustion gas to the exhaust passage 27 side. The high ignitable reformed gas recirculation operation state for recirculating the higher ignitable reformed gas K and the reference ignitable reformed gas recirculating for the same ignitable reformed gas K as the reference ignitability The circulation operation state is changed to the reformed gas recirculation operation state. To being executable configured.
In other words, the control device 50 (an example of the recirculation state switching means) controls the oxygen contained in the combustion air in the recirculation cylinder 40d only by controlling the opening degree of the second fuel flow rate control valve 15 continuously. By controlling the excess air ratio of the air-fuel mixture M in the recirculation cylinder 40d in a range smaller than 1 in the form of controlling the fuel gas supply ratio, the high ignitability reformed gas recirculation operation state and the reference ignitability It is configured to switch and control between the reformed gas recirculation operation state and the exhaust gas recirculation operation state.
Incidentally, in the reference ignitable reformed gas recirculation operation state, the control device 50 has an effect of improving the ignitability by the highly ignitable gas in the reformed gas K, and ignition by carbon dioxide or steam having a relatively high specific heat. The degree of opening of the second fuel flow control valve 15 is adjusted so as to control the proportion of the highly ignitable gas contained in the reformed gas K so that the effect of reducing the property is balanced.

説明を追加すると、制御装置５０は、着火性を向上させる場合、高着火性改質ガス再循環運転状態と基準着火性改質ガス再循環運転状態と排ガス再循環運転状態とを、着火性の低い燃焼ガスを再循環する運転状態から着火性の高い燃焼ガスを再循環する運転状態へ切り換え制御する。尚、制御装置５０は、切り換え時点での運転状態が、再循環する燃焼ガスの着火性が最も高い高着火性改質ガス再循環運転状態である場合、切り換え制御を行わない。   When the explanation is added, the control device 50, when improving the ignitability, determines the high ignitability reformed gas recirculation operation state, the reference ignitability reformed gas recirculation operation state, and the exhaust gas recirculation operation state. Switching control is performed from an operation state in which low combustion gas is recirculated to an operation state in which combustion gas with high ignitability is recirculated. Note that the control device 50 does not perform switching control when the operation state at the time of switching is a highly ignitable reformed gas recirculation operation state in which the ignitability of the recirculated combustion gas is highest.

一方で、制御装置５０は、着火性を低下させる場合、高着火性改質ガス再循環運転状態と基準着火性改質ガス再循環運転状態と排ガス再循環運転状態とを、着火性の高い燃焼ガスを再循環する運転状態から着火性の低い燃焼ガスを再循環する運転状態へ切り換え制御する。尚、制御装置５０は、切り換え時点での運転状態が、再循環する燃焼ガスの着火性が最も低い排ガス再循環運転状態である場合、切り換え制御を行わない。   On the other hand, when reducing the ignitability, the control device 50 performs combustion with high ignitability in the highly ignitable reformed gas recirculation operation state, the reference ignitable reformed gas recirculation operation state, and the exhaust gas recirculation operation state. The control is switched from the operation state in which the gas is recirculated to the operation state in which the combustion gas having low ignitability is recirculated. Note that the control device 50 does not perform the switching control when the operation state at the time of switching is an exhaust gas recirculation operation state in which the ignitability of the recirculated combustion gas is the lowest.

次に、当該第１実施形態に係るエンジンシステム１００、及び制御方法により、得られる運転可能範囲についての実験に関し、図３〜７に基づいて説明する。
当該実験は、これまで説明してきたエンジンシステム１００において、高着火性改質ガス再循環運転状態と基準着火性改質ガス再循環運転状態と排ガス再循環運転状態とを切り換えたときの運転可能範囲を確認するものであり、ボア×ストロークが１０４ｍｍ×１０８ｍｍ、排気量が１００２ｃｍ3、圧縮比が２４、燃焼室形状がドッグディッシュタイプ、回転数が１２００ｍｉｎ-1のエンジンを、以下の〔表２〕に示す条件で運転するものである。
ちなみに、当該エンジンにあっては、通常気筒の数を５とし、再循環気筒の数を１とし、改質ガス再循環運転状態及び排ガス再循環運転状態において、再循環気筒からの燃焼ガスは、すべて、通常気筒へ再循環する条件とした。 Next, an experiment on the operable range obtained by the engine system 100 and the control method according to the first embodiment will be described based on FIGS.
In the engine system 100 described so far, the experiment is based on the operable range when the high ignitable reformed gas recirculation operation state, the reference ignitable reformed gas recirculation operation state, and the exhaust gas recirculation operation state are switched. An engine having a bore x stroke of 104 mm x 108 mm, a displacement of 1002 cm 3 , a compression ratio of 24, a combustion chamber shape of a dog dish type, and a rotation speed of 1200 min -1 is shown in Table 2 below. The vehicle is operated under the conditions shown in FIG.
By the way, in the engine, the number of normal cylinders is 5, the number of recirculation cylinders is 1, and in the reformed gas recirculation operation state and the exhaust gas recirculation operation state, the combustion gas from the recirculation cylinder is All conditions were set to recirculate to the normal cylinder.

Figure 2017172396
Figure 2017172396

図３〜５には、以上の条件において、縦軸を給気温度とし、横軸を図示平均有効圧（以下、ＩＭＥＰと略称する場合がある）とした場合において、左側限界（低負荷側の限界：鎖線で図示）を図示平均有効圧の変動係数が５％となるときとし、右側限界（高負荷側の限界：二点鎖線で図示）をノッキング強度（以下、ＫＩと略称する場合がある）が１００ｋＰａとなるときとしたときの運転可能範囲を、図示している。ここで、図３〜５の等高線の数値は、図示熱効率を示すものであり、一点鎖線は、ＮＯｘ濃度が５０ｐｐｍとなるときを示している。
更に、図３は、通常の予混合圧縮着火運転状態のときの運転可能範囲（基準着火性改質ガス再循環運転状態のときの運転可能範囲に対応）であり、図４は、排ガス再循環運転状態のときの運転可能範囲であり、図５は、高着火性改質ガス再循環運転状態のときの運転可能範囲である。
因みに、図６は、高着火性改質ガス再循環運転状態と通常の予混合圧縮着火運転状態（基準着火性改質ガス再循環運転状態に対応）と排ガス再循環運転状態の夫々の運転可能範囲を重ね合わせて表示したものであり、実線で囲まれている領域が通常の予混合圧縮着火運転状態（基準着火性改質ガス再循環運転状態に対応）の運転可能範囲であり、一点鎖線で囲まれている領域が排ガス再循環運転状態の運転可能範囲であり、二点鎖線で囲まれている領域が高着火性改質ガス再循環運転状態の運転可能範囲である。 3 to 5, the left side limit (on the low load side) when the vertical axis is the supply air temperature and the horizontal axis is the indicated mean effective pressure (hereinafter sometimes abbreviated as IMEP) under the above conditions. The limit: indicated by a chain line) when the variation coefficient of the indicated mean effective pressure is 5%, and the right limit (high load side limit: indicated by a two-dot chain line) is sometimes referred to as knocking strength (hereinafter abbreviated as KI). ) Shows the operable range when 100 kPa is reached. Here, the numerical values of the contour lines in FIGS. 3 to 5 indicate the illustrated thermal efficiency, and the alternate long and short dash line indicates when the NOx concentration is 50 ppm.
Further, FIG. 3 shows the operable range in the normal premixed compression ignition operation state (corresponding to the operable range in the standard ignitable reformed gas recirculation operation state), and FIG. 4 shows the exhaust gas recirculation. FIG. 5 shows the operable range in the high ignitable reformed gas recirculation operation state.
Incidentally, FIG. 6 shows that the high ignitable reformed gas recirculation operation state, the normal premixed compression ignition operation state (corresponding to the reference ignited reformed gas recirculation operation state), and the exhaust gas recirculation operation state are possible. The range is displayed in an overlapping manner, and the area surrounded by the solid line is the operable range in the normal premixed compression ignition operation state (corresponding to the standard ignitable reformed gas recirculation operation state). The region surrounded by is the operable range in the exhaust gas recirculation operation state, and the region surrounded by the two-dot chain line is the operable range in the highly ignited reformed gas recirculation operation state.

図３〜５に示されるように、図４に示す排ガス再循環運転状態における運転可能範囲は、図３に示される通常の予混合圧縮着火運転状態（基準着火性改質ガス再循環運転状態に対応）における運転可能範囲に対し、高負荷側（グラフ図で右側）にシフトしており、着火性を低減していることがわかる。一方、図５に示す高着火性改質ガス再循環運転状態における運転可能範囲は、図３に示される通常の予混合圧縮着火運転状態（基準着火性改質ガス再循環運転状態に対応）における運転可能範囲に対し、低負荷側（グラフ図で左側）にシフトしており、着火性を向上していることがわかる。
従って、図６に示すように、基準着火性改質ガス再循環運転状態と排ガス再循環運転状態と高着火性改質ガス再循環運転状態とを切り換え可能とした場合の運転可能範囲は、図３に示す通常の予混合圧縮着火運転状態の運転可能範囲に比べて、２倍程度に拡大できていることがわかる。 As shown in FIGS. 3 to 5, the operable range in the exhaust gas recirculation operation state shown in FIG. 4 is the normal premixed compression ignition operation state (reference ignitable reformed gas recirculation operation state shown in FIG. It can be seen that the ignitability is reduced because the shift to the high load side (right side in the graph) is performed with respect to the operable range. On the other hand, the operable range in the highly ignitable reformed gas recirculation operation state shown in FIG. 5 is the normal premixed compression ignition operation state (corresponding to the reference ignitable reformed gas recirculation operation state) shown in FIG. It has been shifted to the low load side (left side in the graph) with respect to the operable range, and it can be seen that the ignitability is improved.
Therefore, as shown in FIG. 6, the operable range when the reference ignitable reformed gas recirculation operation state, the exhaust gas recirculation operation state, and the highly ignitable reformed gas recirculation operation state can be switched is shown in FIG. Compared to the operable range in the normal premixed compression ignition operation state shown in FIG.

因みに、図７は、縦軸を給気温度とし、横軸をＩＭＥＰとした場合において、左側限界（低負荷側の限界：２点鎖線のうち最も左側の線で図示）を図示熱効率が４０％となるときとし、右側限界（高負荷側の限界：一点鎖線のうち最も左側の線で図示）をＮＯｘ濃度が５０ｐｐｍとなるときとしたときの高着火性改質ガス再循環運転状態と通常の予混合圧縮着火運転状態（基準着火性改質ガス再循環運転状態に対応）と排ガス再循環運転状態の夫々の運転可能範囲を重ね合わせたものを図示している。
このような定義における運転可能範囲であっても、高着火性改質ガス再循環運転状態と通常の予混合圧縮着火運転状態（基準着火性改質ガス再循環運転状態に対応）と排ガス再循環運転状態の夫々の運転可能範囲を重ね合わせた運転可能範囲は、通常の予混合圧縮着火運転状態における運転可能範囲に比べ、拡大していることがわかる。 7 shows the left limit (low load side limit: indicated by the leftmost line of the two-dot chain line) when the vertical axis is the supply air temperature and the horizontal axis is IMEP. The thermal efficiency is 40%. When the right limit (high load side limit: the leftmost line of the alternate long and short dash line) is when the NOx concentration is 50 ppm, the high ignitable reformed gas recirculation operation state and the normal FIG. 2 illustrates a superposition of respective operable ranges of a premixed compression ignition operation state (corresponding to a reference ignitable reformed gas recirculation operation state) and an exhaust gas recirculation operation state.
Even in the operable range in such a definition, the high ignitable reformed gas recirculation operation state, the normal premixed compression ignition operation state (corresponding to the reference ignitable reformed gas recirculation operation state), and the exhaust gas recirculation It can be seen that the operable range obtained by superimposing the respective operable ranges of the operating state is larger than the operable range in the normal premixed compression ignition operating state.

以上の実験結果が示すように、当該第１実施形態に係るエンジンシステム１００、及びその制御方法にあっては、高着火性改質ガス再循環運転状態と基準着火性改質ガス再循環運転状態とを含む改質ガス再循環運転状態と排ガス再循環運転状態との切り換え制御により、運転可能範囲を大幅に拡大できる。
運転可能範囲を適切に拡大する観点から、制御装置５０が、ノックセンサ（図示せず）にて検出される振動の強度がノッキング判定閾値以上となる毎に、着火性を低減する必要があると判断し、制御装置５０が、高着火性改質ガス再循環運転状態と基準着火性改質ガス再循環運転状態と排ガス再循環運転状態とを、着火性の高い燃焼ガスを再循環する運転状態から着火性の低い燃焼ガスを再循環する運転状態へ切り換え制御する。 As the above experimental results show, in the engine system 100 according to the first embodiment and the control method thereof, the highly ignitable reformed gas recirculation operation state and the reference ignitable reformed gas recirculation operation state By switching control between the reformed gas recirculation operation state and the exhaust gas recirculation operation state, the operating range can be greatly expanded.
From the viewpoint of appropriately expanding the operable range, the control device 50 needs to reduce the ignitability every time the intensity of vibration detected by a knock sensor (not shown) is equal to or greater than the knock determination threshold. An operation state in which the control device 50 recirculates a highly ignitable combustion gas between the highly ignitable reformed gas recirculation operation state, the reference ignitable reformed gas recirculation operation state, and the exhaust gas recirculation operation state. To control the operation to recirculate the combustion gas with low ignitability.

更には、制御装置５０は、燃焼排ガスＥの温度を検出する温度センサＳ２の温度に基づいて失火が発生していると判定する毎に、着火性を向上する必要があると判断し、高着火性改質ガス再循環運転状態と基準着火性改質ガス再循環運転状態と排ガス再循環運転状態とを、着火性の低い燃焼ガスを再循環する運転状態から着火性の高い燃焼ガスを再循環する運転状態へ切り換え制御する。   Further, every time it is determined that misfire has occurred based on the temperature of the temperature sensor S2 that detects the temperature of the combustion exhaust gas E, the control device 50 determines that the ignitability needs to be improved, and high ignition. Recycling of highly ignitable combustion gas from the operating state of recirculating combustion gas with low ignitability between the ignitable reforming gas recirculation operation state, the standard ignitable reforming gas recirculation operation state and the exhaust gas recirculation operation state Control to switch to the operating state.

以上の如く、着火性制御手段５１としての制御装置５０は、改質ガス再循環状態と排ガス再循環運転状態との切り換え、特に、改質ガス再循環運転状態において再循環気筒４０ｄでの混合気Ｍの空気過剰率を１より小さい範囲で制御する空気過剰率制御を実行することで、図９に示すように、改質ガスＫに含まれる高着火性ガスとしての水素の濃度を制御する形態で、通常気筒４０ａ、４０ｂ、４０ｃでの着火性を制御している。
更に、当該第１実施形態にあっては、着火性制御手段５１としての制御装置５０は、改質ガス再循環運転状態にあるときで、再循環気筒４０ｄの空気過剰率が下限空気過剰率（図９で、当量比１．５）に設定されているときに、触媒９２へ改質ガスＫの少なくとも一部を通流させる水性ガスシフト反応制御を実行するシフト反応制御手段として働く。
説明を追加すると、図９に一点鎖線で示すように、当該シフト反応制御手段としての制御装置５０は、流量比制御弁９３の開度を制御し、触媒９２を通過する改質ガスＫの流量を増加する形態で、改質ガスＫに含まれる高着火性ガスとしての水素の濃度を増加させ、触媒９２を通過する改質ガスＫの流量を低減する形態で、改質ガスＫに含まれる高着火性ガスとしての水素の濃度を低減させる。 As described above, the control device 50 as the ignitability control means 51 switches between the reformed gas recirculation state and the exhaust gas recirculation operation state, in particular, the air-fuel mixture in the recirculation cylinder 40d in the reformed gas recirculation operation state. A mode of controlling the concentration of hydrogen as a highly ignitable gas contained in the reformed gas K as shown in FIG. 9 by executing the excess air ratio control for controlling the excess air ratio of M in a range smaller than 1. Thus, the ignitability in the normal cylinders 40a, 40b, and 40c is controlled.
Further, in the first embodiment, the control device 50 as the ignitability control means 51 is in the reformed gas recirculation operation state, and the excess air ratio of the recirculation cylinder 40d is the lower limit excess air ratio ( In FIG. 9, when the equivalence ratio is set to 1.5), it functions as a shift reaction control means for executing a water gas shift reaction control for causing at least a part of the reformed gas K to flow to the catalyst 92.
When the explanation is added, as indicated by a one-dot chain line in FIG. 9, the control device 50 as the shift reaction control means controls the opening degree of the flow rate control valve 93 and the flow rate of the reformed gas K passing through the catalyst 92. Is included in the reformed gas K in a form in which the concentration of hydrogen as a highly ignitable gas contained in the reformed gas K is increased and the flow rate of the reformed gas K passing through the catalyst 92 is reduced. Reduce the concentration of hydrogen as a highly ignitable gas.

当該構成を採用することにより、流量比制御弁９３の開度を制御して触媒９２を通流する改質ガスＫの流量と触媒バイパス路９４を通流する改質ガスＫの流量との比を制御する形態で、改質ガスＫに含まれる高着火性ガスとしての水素の濃度を制御することができる。
図９に一点鎖線で示すように、再循環気筒４０ｄの空気過剰率を下限空気過剰率に設定している状態で、上述の水性ガスシフト反応制御を実行することにより、通常気筒４０ａ、４０ｂ、４０ｃに導かれる改質ガスＫに含まれる高着火性ガスとしての水素の濃度は、８％程度から１２％程度の範囲で、制御することができる。上述したように、発明者らは、化学平衡計算により、水性ガスシフト反応により、改質ガスＫに含まれる高着火性ガスとしての水素の濃度を、ドライベースで、７．４％から１２．４％まで増加させることができることを確認している。このように、水性ガスシフト反応制御をも実行することにより、予混合圧縮着火エンジンの運転範囲の更なる拡大を図ることができる。 By adopting this configuration, the ratio of the flow rate of the reformed gas K flowing through the catalyst 92 by controlling the opening degree of the flow rate control valve 93 and the flow rate of the reformed gas K flowing through the catalyst bypass passage 94. Thus, the concentration of hydrogen as the highly ignitable gas contained in the reformed gas K can be controlled.
As indicated by the alternate long and short dash line in FIG. 9, the above-described water gas shift reaction control is executed in a state where the excess air ratio of the recirculation cylinder 40d is set to the lower limit excess air ratio, thereby normal cylinders 40a, 40b, 40c. The concentration of hydrogen as a highly ignitable gas contained in the reformed gas K led to can be controlled in the range of about 8% to about 12%. As described above, the inventors calculated the concentration of hydrogen as the highly ignitable gas contained in the reformed gas K from 7.4% to 12.4 on a dry basis by water-gas shift reaction by chemical equilibrium calculation. It is confirmed that it can be increased up to 50%. Thus, by further executing the water gas shift reaction control, the operating range of the premixed compression ignition engine can be further expanded.

ここで、着火性制御手段５１としての制御装置５０は、着火性制御として通常気筒４０ａ、４０ｂ、４０ｃの着火時期を目標着火時期（例えば、１０°ＡＴＤＣ）となるように制御する。
通常気筒４０ａ、４０ｂ、４０ｃの着火時期は、図１０に示すように、給気温度、及び通常気筒４０ａ、４０ｂ、４０ｃへ導かれる混合気Ｍの水素濃度に基づいて変化する。具体的には、着火時期は、給気温度の上昇に伴って早くなり、水素濃度の上昇に伴って早くなる傾向にある。そして、着火時期が、進角限界（５°ＡＴＤＣ）よりも早くなるとノッキングが発生し、遅角限界（１５°ＡＴＤＣ）よりも遅くなると失火が発生することとなる。
そこで、当該第１実施形態においては、着火時期判定部５２が、筒内圧力センサ４１にて測定される圧力が着火判定圧力を超えた時（例えば、クランク角度検出手段（図示せず）にて検出されるクランク角度）を着火時期として判定し、着火性制御手段５１としての制御装置５０は、判定された着火時期が通常着火時期よりも早いときには、上述した空気過剰率制御及び水性ガスシフト反応制御の何れか一方により、改質ガスＫに含まれる高着火性ガスとしての水素の濃度を低下させ、判定された着火時期が通常着火時期よりも遅いときには、改質ガスＫに含まれる高着火性ガスとしての水素の濃度を上昇させる形態で、着火時期が目標着火時期となるように制御する。 Here, the control device 50 as the ignitability control means 51 controls the ignition timing of the normal cylinders 40a, 40b, 40c as the target ignition timing (for example, 10 ° ATDC) as the ignitability control.
As shown in FIG. 10, the ignition timing of the normal cylinders 40a, 40b, and 40c changes based on the supply air temperature and the hydrogen concentration of the air-fuel mixture M guided to the normal cylinders 40a, 40b, and 40c. Specifically, the ignition timing tends to be earlier with an increase in the supply air temperature and earlier with an increase in the hydrogen concentration. When the ignition timing becomes earlier than the advance angle limit (5 ° ATDC), knocking occurs, and when the ignition timing becomes later than the retard angle limit (15 ° ATDC), misfire occurs.
Therefore, in the first embodiment, the ignition timing determination unit 52 determines that the pressure measured by the in-cylinder pressure sensor 41 exceeds the ignition determination pressure (for example, at a crank angle detection means (not shown)). The detected crank angle) is determined as the ignition timing, and the control device 50 as the ignitability control means 51 determines that the excess air ratio control and the water gas shift reaction control described above are performed when the determined ignition timing is earlier than the normal ignition timing. When one of the above reduces the concentration of hydrogen as a highly ignitable gas contained in the reformed gas K and the determined ignition timing is later than the normal ignition timing, the high ignitability contained in the reformed gas K Control is performed so that the ignition timing becomes the target ignition timing in the form of increasing the concentration of hydrogen as a gas.

〔第２実施形態〕
当該第２実施形態に係るエンジンシステム２００は、図１１に示すように、燃料ガスＦと燃焼用空気Ａとの混合気Ｍを圧縮着火させ燃焼させる通常気筒４０ａ、４０ｂ、４０ｃ、４０ｄを有すると共に、混合気Ｍを形成する燃料ガスＦを供給する第１燃料ガス供給部を有する予混合圧縮着火エンジン２００ｂを備えるのに加えて、燃料ガスＦと燃焼用空気Ａとを点火プラグ（図示せず）により火花点火して燃焼すると共に燃焼後の燃焼ガスを予混合圧縮着火エンジン２００ｂの通常気筒４０ａ、４０ｂ、４０ｃ、４０ｄへ再循環可能な再循環気筒８０ａ、８０ｂ、８０ｃ、８０ｄを有すると共に、再循環気筒８０ａ、８０ｂ、８０ｃ、８０ｄへ導かれる燃料ガスＦを供給する第２燃料ガス供給部を第１燃料ガス供給部とは別に有する補助エンジン２００ａを備えるものに関する。 [Second Embodiment]
As shown in FIG. 11, the engine system 200 according to the second embodiment includes normal cylinders 40a, 40b, 40c, and 40d that compress and ignite an air-fuel mixture M of fuel gas F and combustion air A and burn it. In addition to providing the premixed compression ignition engine 200b having the first fuel gas supply unit for supplying the fuel gas F forming the air-fuel mixture M, the fuel gas F and the combustion air A are ignited by a spark plug (not shown). ) And recirculation cylinders 80a, 80b, 80c, 80d capable of recirculating the combustion gas after combustion to the normal cylinders 40a, 40b, 40c, 40d of the premixed compression ignition engine 200b, An auxiliary engine having a second fuel gas supply part for supplying the fuel gas F guided to the recirculation cylinders 80a, 80b, 80c, 80d, separately from the first fuel gas supply part On those with a down 200a.

エンジンシステム２００に係る予混合圧縮着火エンジン２００ｂは、再循環気筒、燃焼ガス通流路、及び過給機３０を備えていない点以外は、第１実施形態に示した予混合圧縮着火エンジンと変わるところがない。そこで、以下の説明にあっては、上記第１実施形態に係る予混合圧縮着火エンジンと同一の構成及び制御については、説明を割愛する場合がある。
説明を追加すると、エンジンシステム２００に係る予混合圧縮着火エンジン２００ｂは給気本管２０から通常気筒４０ａ、４０ｂ、４０ｃ、４０ｄの燃焼室（図示せず）へ給気弁（図示せず）を介して給気した混合気Ｍを、ピストンの上昇により圧縮して発火点まで昇温させることで、混合気Ｍを自己着火させて燃焼・膨張させることで、予混合圧縮着火エンジン２００ｂのピストンを押し下げて回転軸（図示せず）から回転動力を出力すると共に、燃焼により発生した燃焼排ガスＥは、通常気筒４０ａ、４０ｂ、４０ｃ、４０ｄの燃焼室から排気弁（図示せず）を介して排気路２７に押し出され、外部へ排出される。ちなみに、当該エンジンシステム２００において予混合圧縮着火エンジン２００ｂは、回転軸に発電機（図示せず）を連結して発電する、所謂、コジェネレーションシステムとして構成されている。 The premixed compression ignition engine 200b according to the engine system 200 is different from the premixed compression ignition engine shown in the first embodiment except that it does not include a recirculation cylinder, a combustion gas passage, and a supercharger 30. There is no place. Therefore, in the following description, the description of the same configuration and control as those of the premixed compression ignition engine according to the first embodiment may be omitted.
If a description is added, the premixed compression ignition engine 200b according to the engine system 200 has an intake valve (not shown) from the supply main pipe 20 to the combustion chambers (not shown) of the normal cylinders 40a, 40b, 40c, and 40d. By compressing the air-fuel mixture M supplied through the piston by raising the piston and raising the temperature to the ignition point, the air-fuel mixture M is self-ignited to be combusted and expanded, so that the piston of the premixed compression ignition engine 200b is While pushing down to output rotational power from a rotating shaft (not shown), the combustion exhaust gas E generated by combustion is exhausted from the combustion chambers of the normal cylinders 40a, 40b, 40c, 40d through an exhaust valve (not shown). It is pushed out to the path 27 and discharged outside. Incidentally, in the engine system 200, the premixed compression ignition engine 200b is configured as a so-called cogeneration system that generates power by connecting a generator (not shown) to a rotating shaft.

給気本管２０には、燃焼用空気Ａを浄化するエアクリーナ２１、燃焼用空気Ａに燃料ガスＦを適切な比率（空燃比）で混合するベンチュリー式のミキサ１４、開度調整により通常気筒４０ａ、４０ｂ、４０ｃ、４０ｄへの混合気Ｍの給気量を調整可能なスロットル弁２３が、その上流側から記載の順に設けられている。
即ち、給気本管２０において、ミキサ１４で都市ガス等の燃料ガスＦと燃焼用空気Ａとを混合して生成された混合気Ｍは、スロットル弁２３を介して所定の流量に調整されて、通常気筒４０ａ、４０ｂ、４０ｃ、４０ｄの燃焼室へ導入される。 The supply main pipe 20 includes an air cleaner 21 for purifying the combustion air A, a Venturi mixer 14 for mixing the fuel gas F with the combustion air A at an appropriate ratio (air-fuel ratio), and a normal cylinder 40a by adjusting the opening degree. , 40b, 40c, 40d, a throttle valve 23 capable of adjusting the supply amount of the air-fuel mixture M is provided in the order described from the upstream side.
That is, in the supply main pipe 20, the air-fuel mixture M generated by mixing the fuel gas F such as city gas and the combustion air A in the mixer 14 is adjusted to a predetermined flow rate via the throttle valve 23. The normal cylinders 40a, 40b, 40c, and 40d are introduced into the combustion chambers.

ミキサ１４に燃料ガスＦを導く第１燃料ガス供給路１１には、ミキサ１４の上流側の給気本管２０における燃焼用空気Ａの圧力と第１燃料ガス供給路１１における燃料ガスＦの圧力差を一定に保つ差圧レギュレータ１２、ミキサ１４を介して通常気筒４０ａ、４０ｂ、４０ｃ、４０ｄの燃焼室へ供給される燃料ガスＦの供給量を調整する第１燃料流量制御弁１３が設けられている。即ち、第１燃料ガス供給路１１、差圧レギュレータ１２、ミキサ１４、及び第１燃料流量制御弁１３が、第１燃料ガス供給部として機能する。
制御装置５０は、第１燃料流量制御弁１３の開度を調整する形態で、混合気Ｍの空気過剰率を１より大きく設定して、通常気筒４０ａ、４０ｂ、４０ｃ、４０ｄの各燃焼室にて希薄燃焼するように、燃料ガスの供給量を制御する。 In the first fuel gas supply path 11 for introducing the fuel gas F to the mixer 14, the pressure of the combustion air A in the supply main pipe 20 upstream of the mixer 14 and the pressure of the fuel gas F in the first fuel gas supply path 11 are provided. A first fuel flow control valve 13 for adjusting the supply amount of the fuel gas F supplied to the combustion chambers of the normal cylinders 40a, 40b, 40c, and 40d via the differential pressure regulator 12 and the mixer 14 that keep the difference constant is provided. ing. That is, the first fuel gas supply path 11, the differential pressure regulator 12, the mixer 14, and the first fuel flow control valve 13 function as a first fuel gas supply unit.
The control device 50 adjusts the opening degree of the first fuel flow rate control valve 13 and sets the excess air ratio of the air-fuel mixture M to be larger than 1 so that the combustion chambers of the normal cylinders 40a, 40b, 40c, and 40d are provided. The amount of fuel gas supplied is controlled so that lean combustion occurs.

更に、予混合圧縮着火エンジン２００ｂには、ノッキング強度をノッキング関連値として検出するノックセンサ（図示せず）が設けられており、制御装置５０が、当該ノックセンサにて検出されるノッキング強度がノッキング判定閾値以上となる場合に、ノッキングが発生していると判定する。
また、予混合圧縮着火エンジン２００ｂには、燃焼室内の圧力を測定する筒内圧力センサ４１（着火時期検出手段の一例）を備え、着火時期判定部５２としての制御装置５０は、当該筒内圧力センサ８１にて測定される圧力が着火判定圧力を超えた時を着火時期として判定する。 Furthermore, the premixed compression ignition engine 200b is provided with a knock sensor (not shown) that detects knocking strength as a knocking related value, and the control device 50 knocks the knocking strength detected by the knock sensor. When the determination threshold value is exceeded, it is determined that knocking has occurred.
Further, the premixed compression ignition engine 200b includes an in-cylinder pressure sensor 41 (an example of an ignition timing detection unit) that measures the pressure in the combustion chamber, and the control device 50 as the ignition timing determination unit 52 includes the in-cylinder pressure. When the pressure measured by the sensor 81 exceeds the ignition determination pressure, the ignition timing is determined.

また、予混合圧縮着火エンジン２００ｂの排気路２７には、燃焼室での燃焼状態を検出する燃焼状態検出手段として、排気路２７を通流する燃焼排ガスＥの温度を検出する温度センサＳ２が設けられており、制御装置５０は、当該温度センサＳ２にて検出される燃焼排ガス温度が失火判定閾値以下となる場合に、失火が発生していると判定する。   The exhaust passage 27 of the premixed compression ignition engine 200b is provided with a temperature sensor S2 for detecting the temperature of the combustion exhaust gas E flowing through the exhaust passage 27 as a combustion state detecting means for detecting the combustion state in the combustion chamber. The control device 50 determines that misfire has occurred when the combustion exhaust gas temperature detected by the temperature sensor S2 is equal to or lower than the misfire determination threshold.

当該第２実施形態に係るエンジンシステム２００にあっては、上述した予混合圧縮着火エンジン２００ｂの通常気筒４０ａ、４０ｂ、４０ｃ、４０ｄの夫々に対し、燃焼ガス（改質ガスＫ及び燃焼排ガスＥを含む）を再循環（供給）する火花点火式の補助エンジン２００ａを備えている。
当該火花点火式の補助エンジン２００ａは、給気本管７０から再循環気筒８０ａ、８０ｂ、８０ｃ、８０ｄの燃焼室（図示せず）へ給気弁（図示せず）を介して給気した混合気Ｍを点火プラグ（図示せず）により火花点火させて燃焼・膨張させることで、火花点火式の補助エンジン本体８０のピストンを押し下げて回転軸（図示せず）から回転動力を出力すると共に、燃焼により発生した燃焼ガス（改質ガスＫ及び燃焼排ガスＥを含む）は、再循環気筒８０ａ、８０ｂ、８０ｃ、８０ｄの燃焼室から排気弁（図示せず）を介して燃焼ガス通流路２８に押し出される。 In the engine system 200 according to the second embodiment, combustion gas (reformed gas K and combustion exhaust gas E is supplied to each of the normal cylinders 40a, 40b, 40c, and 40d of the premixed compression ignition engine 200b described above. Including a spark ignition type auxiliary engine 200a for recirculation (supply).
The spark-ignition auxiliary engine 200a mixes the air supplied from the supply main pipe 70 to the combustion chambers (not shown) of the recirculation cylinders 80a, 80b, 80c, and 80d via the supply valve (not shown). The spark M is ignited by a spark plug (not shown) and burned / expanded to push down the piston of the spark ignition type auxiliary engine body 80 to output rotational power from a rotating shaft (not shown), Combustion gas (including reformed gas K and combustion exhaust gas E) generated by combustion is discharged from the combustion chambers of the recirculation cylinders 80a, 80b, 80c, and 80d through the exhaust valve (not shown). Extruded.

燃焼ガス通流路２８には、その下流側が予混合圧縮着火エンジン２００ｂの給気本管２０に接続される流路部位と、その下流側が予混合圧縮着火エンジン２００ｂの排気路２７に接続される流路部位とが、三方切換弁９０を介して設けられている。
ちなみに、当該第２実施形態にあっては、燃焼ガスはすべて、燃焼ガス通流路２８の予混合圧縮着火エンジン２００ｂの給気本管２０に接続される流路部位へ戻すように、三方切換弁９０が切り換え制御される。
尚、燃焼ガス通流路２８の予混合圧縮着火エンジン２００ｂの給気本管２０に接続される流路部位には、燃焼ガスを冷却するためのＥＧＲクーラ９１が設けられている。
更に、給気本管２０で、燃焼ガス通流路２８が接続される部位の下流側には、予混合圧縮着火エンジン２００ｂの給気本管２０を通流する混合気Ｍの温度を測定する温度センサＳ１が設けられており、当該温度センサＳ１により測定される温度は、着火性制御手段５１としての制御装置５０が、着火時期を制御する際に用いられる。 The combustion gas flow passage 28 is connected to a flow passage portion downstream of which is connected to the supply main pipe 20 of the premixed compression ignition engine 200b and to the exhaust passage 27 of the premixed compression ignition engine 200b. A flow path part is provided via a three-way switching valve 90.
Incidentally, in the second embodiment, the three-way switching is performed so that all the combustion gas is returned to the flow path portion connected to the supply main pipe 20 of the premixed compression ignition engine 200b of the combustion gas flow path 28. The valve 90 is controlled to be switched.
Note that an EGR cooler 91 for cooling the combustion gas is provided in a flow path portion of the combustion gas flow path 28 connected to the supply main pipe 20 of the premixed compression ignition engine 200b.
Further, the temperature of the air-fuel mixture M flowing through the air supply main 20 of the premixed compression ignition engine 200b is measured on the downstream side of the portion where the combustion gas passage 28 is connected in the air supply main 20. The temperature sensor S1 is provided, and the temperature measured by the temperature sensor S1 is used when the control device 50 as the ignitability control means 51 controls the ignition timing.

燃焼ガス通流路２８で下流側が給気本管２０に接続される流路部位（触媒流路の一例）で、ＥＧＲクーラ９１の上流側の流路部位（ＥＧＲクーラ９１と再循環気筒４０ａ、４０ｂ、４０ｃ、４０ｄとの間の流路部位：より具体的には三方切換弁９０と再循環気筒４０ａ、４０ｂ、４０ｃ、４０ｄとの間の流路部位）には、改質ガスＫの少なくとも一部を水性ガスシフト反応させる触媒９２を備えている。
更に、燃焼ガス通流路２８で下流側が給気本管２０に接続される流路部位（触媒流路）を通流する燃焼ガスに触媒９２をバイパスさせる触媒バイパス路９４を備えると共に、燃焼ガス通流路２８で下流側が給気本管２０に接続される流路部位を通流する燃焼ガスと触媒バイパス路９４を通流する燃焼ガスとの流量比を制御する流量比制御弁９３を備えている。流量比制御弁９３は、触媒バイパス路９４にてバイパスされる触媒流路の開度を制御して触媒流路を通流する燃焼ガスの流量を制御する流量制御弁として設けられている。より具体的には、燃焼ガス通流路２８で下流側が給気本管２０に接続される流路部位で、触媒９２の上流側の流路部位（触媒９２と再循環気筒４０ａ、４０ｂ、４０ｃ、４０ｄとの間の流路部位）に設けられており、当該流路部位にて開度を制御する形態で、触媒９２を通流する燃焼ガスと触媒バイパス路９４を通流する燃焼ガスとの流量比を制御する。 The combustion gas passage 28 is a flow passage portion (an example of a catalyst flow passage) connected to the supply main pipe 20 on the downstream side, and a flow passage portion upstream of the EGR cooler 91 (EGR cooler 91 and recirculation cylinder 40a, 40b, 40c, 40d: The flow path part between the three-way switching valve 90 and the recirculation cylinders 40a, 40b, 40c, 40d), more specifically, at least the reformed gas K A catalyst 92 that partially causes a water gas shift reaction is provided.
Further, the combustion gas passage 28 is provided with a catalyst bypass passage 94 for bypassing the catalyst 92 to the combustion gas flowing through the passage portion (catalyst passage) connected to the supply main pipe 20 on the downstream side, and the combustion gas. A flow rate control valve 93 is provided for controlling the flow rate ratio of the combustion gas flowing through the flow path portion connected to the supply main pipe 20 on the downstream side of the flow path 28 and the combustion gas flowing through the catalyst bypass path 94. ing. The flow ratio control valve 93 is provided as a flow control valve that controls the flow rate of the combustion gas flowing through the catalyst flow path by controlling the opening of the catalyst flow path that is bypassed by the catalyst bypass path 94. More specifically, the downstream side of the combustion gas passage 28 is connected to the supply main pipe 20, and the upstream side of the catalyst 92 (the catalyst 92 and the recirculation cylinders 40a, 40b, 40c). , 40d between the combustion gas flowing through the catalyst 92 and the combustion gas flowing through the catalyst bypass passage 94 in a form in which the opening degree is controlled in the flow path portion. To control the flow ratio.

給気本管７０には、燃焼用空気Ａを浄化するエアクリーナ７１、燃焼用空気Ａに燃料ガスＦを適切な比率（空燃比）で混合するベンチュリー式のミキサ６４、開度調整により再循環気筒８０ａ、８０ｂ、８０ｃ、８０ｄへの混合気Ｍの給気量を調整可能なスロットル弁７３が、その上流側から記載の順に設けられている。
即ち、給気本管７０において、ミキサ６４で都市ガス等の燃料ガスＦと燃焼用空気Ａとを混合して生成された混合気Ｍは、スロットル弁７３を介して所定の流量に調整されて、再循環気筒８０ａ、８０ｂ、８０ｃ、８０ｄの燃焼室へ導入される。 The supply main pipe 70 includes an air cleaner 71 for purifying the combustion air A, a venturi mixer 64 for mixing the fuel gas F with the combustion air A at an appropriate ratio (air-fuel ratio), and a recirculation cylinder by adjusting the opening degree. A throttle valve 73 capable of adjusting the supply amount of the air-fuel mixture M to 80a, 80b, 80c, and 80d is provided in the order described from the upstream side.
That is, the air-fuel mixture M generated by mixing the fuel gas F such as city gas and the combustion air A by the mixer 64 in the supply main pipe 70 is adjusted to a predetermined flow rate via the throttle valve 73. The recirculation cylinders 80a, 80b, 80c, and 80d are introduced into the combustion chambers.

ミキサ６４に燃料ガスＦを導く第２燃料ガス供給路６１には、ミキサ６４の上流側の給気本管７０における燃焼用空気Ａの圧力と第２燃料ガス供給路６１における燃料ガスＦの圧力差を一定に保つ差圧レギュレータ６２、ミキサ６４を介して再循環気筒８０ａ、８０ｂ、８０ｃ、８０ｄの燃焼室へ供給される燃料ガスＦの供給量を調整する第２燃料流量制御弁６３が設けられている。即ち、第２燃料ガス供給路６１、差圧レギュレータ６２、ミキサ６４、及び第２燃料流量制御弁６３が、第２燃料ガス供給部として機能する。   In the second fuel gas supply passage 61 for introducing the fuel gas F to the mixer 64, the pressure of the combustion air A in the supply main pipe 70 upstream of the mixer 64 and the pressure of the fuel gas F in the second fuel gas supply passage 61 are provided. A second fuel flow rate control valve 63 for adjusting the supply amount of the fuel gas F supplied to the combustion chambers of the recirculation cylinders 80a, 80b, 80c, 80d via the differential pressure regulator 62 and the mixer 64 that keep the difference constant is provided. It has been. That is, the second fuel gas supply path 61, the differential pressure regulator 62, the mixer 64, and the second fuel flow rate control valve 63 function as a second fuel gas supply unit.

制御装置５０が、再循環気筒８０ａ、８０ｂ、８０ｃ、８０ｄでの燃焼用空気に含まれる酸素に対する燃料ガスの供給比率を制御する形態で再循環気筒８０ａ、８０ｂ、８０ｃ、８０ｄでの混合気Ｍの空気過剰率を１より小さくする制御の一例として、第２燃料ガス供給部としての第２燃料流量制御弁６３の開度を特定の開度として再循環気筒８０ａ、８０ｂ、８０ｃ、８０ｄでの混合気Ｍの空気過剰率を１より小さくして、混合気Ｍの少なくとも一部を燃焼させ部分酸化反応させて、水素、一酸化炭素及びアセチレン等を含み、燃料ガスよりも着火性の高い高着火性ガスが含まれる燃焼ガスとしての改質ガスＫを再循環気筒８０ａ、８０ｂ、８０ｃ、８０ｄにて生成して再循環させる改質ガス再循環運転状態と、再循環気筒８０ａ、８０ｂ、８０ｃ、８０ｄでの燃焼用空気に含まれる酸素に対する燃料ガスの供給比率を制御する形態で再循環気筒８０ａ、８０ｂ、８０ｃ、８０ｄでの混合気Ｍの空気過剰率を１以上として再循環気筒８０ａ、８０ｂ、８０ｃ、８０ｄから改質ガスＫよりも着火性の低い燃焼排ガスＥを再循環させる排ガス再循環運転状態とを切り換え制御する。
更に、制御装置５０は、第２燃料流量制御弁６３の開度を調整して、再循環気筒８０ａ、８０ｂ、８０ｃ、８０ｄでの燃焼用空気に含まれる酸素に対する燃料ガスの供給比率を制御する形態で再循環気筒８０ａ、８０ｂ、８０ｃ、８０ｄでの混合気Ｍの空気過剰率を１より小さい範囲で制御することで、通常気筒４０ａ、４０ｂ、４０ｃ、４０ｄへ燃焼ガスを再循環しない場合（上述した三方切換弁９０にて燃焼ガスを排気路２７の側へ導く制御を実行する場合）の通常気筒４０ａ、４０ｂ、４０ｃ、４０ｄでの混合気Ｍの着火性を基準着火性としたときに、基準着火性よりも高い着火性の改質ガスＫを再循環させる高着火性改質ガス再循環運転状態と、基準着火性と同一の着火性の改質ガスＫを再循環させる基準着火性改質ガス再循環運転状態とを、改質ガス再循環運転状態として実行可能に構成されている。
即ち、制御装置５０は、第２燃料流量制御弁６３の開度を連続的に調整する制御のみにより、再循環気筒８０ａ、８０ｂ、８０ｃ、８０ｄでの燃焼用空気に含まれる酸素に対する燃料ガスの供給比率を制御する形態で再循環気筒８０ａ、８０ｂ、８０ｃ、８０ｄでの混合気Ｍの空気過剰率を１より小さい範囲で制御することで、高着火性改質ガス再循環運転状態と、基準着火性改質ガス再循環運転状態と、排ガス再循環運転状態とを切り換え制御するように構成されている。 The control device 50 controls the supply ratio of the fuel gas to the oxygen contained in the combustion air in the recirculation cylinders 80a, 80b, 80c, 80d, and the mixture M in the recirculation cylinders 80a, 80b, 80c, 80d. As an example of the control for making the excess air ratio less than 1, the opening degree of the second fuel flow control valve 63 as the second fuel gas supply unit is set to a specific opening degree in the recirculation cylinders 80a, 80b, 80c, 80d. The excess air ratio of the air-fuel mixture M is made smaller than 1, and at least a part of the air-fuel mixture M is burned to undergo a partial oxidation reaction, which contains hydrogen, carbon monoxide, acetylene, etc., and has a higher ignitability than fuel gas. A reformed gas recirculation operation state in which the reformed gas K as the combustion gas containing the ignitable gas is generated and recirculated in the recirculation cylinders 80a, 80b, 80c, 80d, and the recirculation cylinders 80a, 80b The recirculation cylinder 80a is configured such that the excess ratio of the air-fuel mixture M in the recirculation cylinders 80a, 80b, 80c, 80d is 1 or more in the form of controlling the supply ratio of the fuel gas to the oxygen contained in the combustion air at 80c, 80d. , 80b, 80c, and 80d, the exhaust gas recirculation operation state in which the combustion exhaust gas E having lower ignitability than the reformed gas K is recirculated is controlled.
Further, the control device 50 adjusts the opening degree of the second fuel flow control valve 63 to control the supply ratio of the fuel gas to the oxygen contained in the combustion air in the recirculation cylinders 80a, 80b, 80c, 80d. When the excess air ratio of the air-fuel mixture M in the recirculation cylinders 80a, 80b, 80c, and 80d is controlled within a range smaller than 1, the combustion gas is not recirculated to the normal cylinders 40a, 40b, 40c, and 40d ( When the control of guiding the combustion gas to the exhaust passage 27 side is performed by the three-way switching valve 90 described above) when the ignitability of the air-fuel mixture M in the normal cylinders 40a, 40b, 40c, and 40d is set to the reference ignitability Highly ignitable reformed gas recirculation operation state that recycles reformed gas K having higher ignitability than standard ignitability, and standard ignitability that recirculates reformed gas K having the same ignitability as standard ignitability Reformed gas recirculation operation Deliberately, it is executable configured as a modifying gas recirculation operating conditions.
That is, the control device 50 controls the amount of fuel gas with respect to oxygen contained in the combustion air in the recirculation cylinders 80a, 80b, 80c, and 80d only by control for continuously adjusting the opening degree of the second fuel flow control valve 63. By controlling the excess air ratio of the air-fuel mixture M in the recirculation cylinders 80a, 80b, 80c, and 80d in a form in which the supply ratio is controlled within a range smaller than 1, the highly ignitable reformed gas recirculation operation state and the reference The ignitable reformed gas recirculation operation state and the exhaust gas recirculation operation state are switched and controlled.

また、制御装置５０は、着火性制御手段５１として、改質ガス再循環状態と排ガス再循環運転状態との切り換え、特に、改質ガス再循環運転状態において再循環気筒８０ａ、８０ｂ、８０ｃ、８０ｄでの混合気Ｍの空気過剰率を１より小さい範囲で制御する空気過剰率制御を実行することで、図９に一点鎖線で示すように、改質ガスＫに含まれる高着火性ガスとしての水素の濃度を制御する形態で、通常気筒４０ａ、４０ｂ、４０ｃ、４０ｄでの着火性を制御している。
更に、着火性制御手段５１としての制御装置５０は、改質ガス再循環運転状態にあるときで、再循環気筒８０ａ、８０ｂ、８０ｃ、８０ｄの空気過剰率が下限空気過剰率（図９で、当量比１．５）に設定されているときに、触媒９２へ改質ガスＫの少なくとも一部を通流させる水性ガスシフト反応制御を実行するシフト反応制御手段として働く。 Further, the control device 50 switches the ignitability control means 51 between the reformed gas recirculation state and the exhaust gas recirculation operation state, particularly in the reformed gas recirculation operation state, the recirculation cylinders 80a, 80b, 80c, 80d. By executing the excess air ratio control for controlling the excess air ratio of the air-fuel mixture M in a range smaller than 1, the high ignitable gas contained in the reformed gas K as shown by a one-dot chain line in FIG. The ignitability in the normal cylinders 40a, 40b, 40c, and 40d is controlled by controlling the hydrogen concentration.
Further, the control device 50 as the ignitability control means 51 is in the reformed gas recirculation operation state, and the excess air ratio of the recirculation cylinders 80a, 80b, 80c, 80d is the lower limit excess air ratio (in FIG. When the equivalence ratio is set to 1.5), it functions as a shift reaction control means for executing a water gas shift reaction control for causing at least a part of the reformed gas K to flow through the catalyst 92.

以上の構成を採用することにより、着火性制御手段５１としての制御装置５０が、上記第１実施形態と同様の制御を実行することで、エンジンシステム２００の運転可能範囲を拡大するように、着火性の制御が適切に実行されることとなる。   By adopting the above configuration, the control device 50 as the ignitability control means 51 performs the same control as in the first embodiment, so that the operable range of the engine system 200 is expanded. Sexual control will be performed appropriately.

〔別実施形態〕
（１）上記第１、２実施形態において、通常気筒の数は、１つ以上であればいくつであっても構わないし、再循環気筒の数も、１つ以上であればいくつであっても、本発明の機能を良好に発揮できる。 [Another embodiment]
(1) In the first and second embodiments, the number of normal cylinders may be any number as long as it is one or more, and the number of recirculation cylinders may be any number as long as it is one or more. The functions of the present invention can be exhibited well.

（２）上記第１実施形態は、再循環気筒４０ｄの排気ポートに接続される燃焼ガス通流路２８は、給気本管２０に接続される構成を有すると共に、燃焼ガス（改質ガスＫ及び燃焼排ガスＥを含む）を、通常気筒４０ａ、４０ｂ、４０ｃのみに導く例を示した。
しかしながら、例えば、燃焼ガス通流路２８は、通常気筒４０ａ、４０ｂ、４０ｃに加えて、再循環気筒４０ｄにも燃焼ガス（改質ガスＫ及び燃焼排ガスＥを含む）を導く構成を採用しても構わない。 (2) In the first embodiment, the combustion gas passage 28 connected to the exhaust port of the recirculation cylinder 40d is connected to the supply main pipe 20, and the combustion gas (reformed gas K) And combustion exhaust gas E) are introduced only to the normal cylinders 40a, 40b, 40c.
However, for example, the combustion gas passage 28 adopts a configuration that guides the combustion gas (including the reformed gas K and the combustion exhaust gas E) to the recirculation cylinder 40d in addition to the normal cylinders 40a, 40b, and 40c. It doesn't matter.

（３）上記第１実施形態では、エンジンシステム１００が過給機３０を備える例を示したが、別に、当該過給機３０を備えない構成であっても、本発明の目的は良好に達成される。また、上記第２実施形態では、エンジンシステム２００の予混合圧縮着火エンジン２００ｂが、その出力を補うべく、過給機を備える構成を採用しても構わない。 (3) In the first embodiment, the example in which the engine system 100 includes the supercharger 30 has been described. However, the object of the present invention can be satisfactorily achieved even if the supercharger 30 is not included. Is done. Moreover, in the said 2nd Embodiment, the structure provided with a supercharger may be employ | adopted so that the premix compression ignition engine 200b of the engine system 200 may supplement the output.

（４）上記第２実施形態においては、単一の補助エンジン２００ａと単一の予混合圧縮着火エンジン２００ｂとを備える構成例を示したが、補助エンジン２００ａを複数備える構成や、予混合圧縮着火エンジン２００ｂを複数備える構成を採用することもできる。
また、補助エンジン２００ａは、回転軸に発電機（図示せず）を連結して発電する、所謂、コジェネレーションシステムとして構成しても構わない。 (4) In the second embodiment, a configuration example including a single auxiliary engine 200a and a single premixed compression ignition engine 200b has been described. However, a configuration including a plurality of auxiliary engines 200a, and premixed compression ignition. A configuration including a plurality of engines 200b may be employed.
The auxiliary engine 200a may be configured as a so-called cogeneration system that generates power by connecting a generator (not shown) to the rotating shaft.

（５）上記第１実施形態では、過給機３０として、ターボ式のものを備える例を示したが、スーパーチャージャ式のものとしても構わない。また、上記第１実施形態では、過給機３０として、単一のコンプレッサ３１と単一の排気タービン３２とを備える、所謂、一段過給の例を示したが、別に、二段以上の多段過給としても構わない。 (5) In the first embodiment, an example in which the turbocharger 30 is provided as the supercharger 30 has been described. However, a supercharger type may be used. Moreover, in the said 1st Embodiment, although the example of what is called a one-stage supercharging provided with the single compressor 31 and the single exhaust turbine 32 as the supercharger 30 was shown separately, two or more multistage is shown. It does not matter as supercharging.

（６）上記第１実施形態において、再循環気筒４０ｄにて生成された燃焼ガスとしての改質ガスＫ又は燃焼排ガスＥを、通常気筒４０ａ、４０ｂ、４０ｃ及び再循環気筒４０ｄに戻すことなく、排気路２７で排気タービン３２の上流側へ戻す構成例を示した。しかしながら、別に排気路２７で排気タービン３２の下流側に戻すように構成しても構わない。 (6) In the first embodiment, the reformed gas K or the combustion exhaust gas E as the combustion gas generated in the recirculation cylinder 40d is not returned to the normal cylinders 40a, 40b, 40c and the recirculation cylinder 40d. The structural example which returns to the upstream of the exhaust turbine 32 in the exhaust path 27 was shown. However, it may be configured to return to the downstream side of the exhaust turbine 32 by the exhaust passage 27 separately.

（７）上記第１、２実施形態では、制御装置５０は、高着火性改質ガス再循環運転状態と基準着火性改質ガス再循環運転状態と排ガス再循環運転状態とを切り換え制御する例を示した。
しかしながら、制御装置５０は、第２燃料流量制御弁の開度を調整して、再循環気筒での燃焼用空気Ａに含まれる酸素に対する燃料ガスＦの供給比率を制御する形態で再循環気筒での混合気Ｍの空気過剰率を１より小さい範囲で制御することで、通常気筒へ燃焼ガスを再循環しない場合の通常気筒での混合気Ｍの着火性を基準着火性としたときに、改質ガス再循環運転状態として、高着火性改質ガス再循環運転状態と基準着火性改質ガス再循環運転状態とに加え、基準着火性よりも低い着火性の改質ガスＫを再循環させる準高着火性改質ガス再循環運転状態を、実行可能に構成しても構わない。
即ち、制御装置５０は、第２燃料流量制御弁１５の開度を連続的に調整する制御のみにより、再循環気筒での燃焼用空気に含まれる酸素に対する燃料ガスの供給比率を制御する形態で再循環気筒での混合気Ｍの空気過剰率を１より小さい範囲で制御することで、高着火性改質ガス再循環運転状態と、基準着火性改質ガス再循環運転状態と、準高着火性改質ガス再循環運転状態と、排ガス再循環運転状態とを切り換え制御するように構成しても構わない。 (7) In the first and second embodiments, the control device 50 performs switching control between the highly ignitable reformed gas recirculation operation state, the reference ignitable reformed gas recirculation operation state, and the exhaust gas recirculation operation state. showed that.
However, the control device 50 adjusts the opening of the second fuel flow control valve to control the supply ratio of the fuel gas F to the oxygen contained in the combustion air A in the recirculation cylinder. When the excess air ratio of the air-fuel mixture M is controlled within a range smaller than 1, the ignitability of the air-fuel mixture M in the normal cylinder when the combustion gas is not recirculated to the normal cylinder is changed to the reference ignitability. As the quality gas recirculation operation state, in addition to the highly ignitable reformed gas recirculation operation state and the reference ignitable reformed gas recirculation operation state, the ignitable reformed gas K lower than the reference ignitability is recirculated. The quasi-highly ignitable reformed gas recirculation operation state may be configured to be executable.
That is, the control device 50 is configured to control the supply ratio of the fuel gas to the oxygen contained in the combustion air in the recirculation cylinder only by the control for continuously adjusting the opening degree of the second fuel flow control valve 15. By controlling the excess air ratio of the air-fuel mixture M in the recirculation cylinder within a range smaller than 1, the high ignitability reformed gas recirculation operation state, the reference ignitability reformed gas recirculation operation state, and the semi-high ignition It may be configured to switch and control the property reformed gas recirculation operation state and the exhaust gas recirculation operation state.

（８）上記第１、２実施形態では、燃焼状態を検出する手段として、ノックセンサ、排ガスの温度を検出する温度センサＳ２を備える例を示した。
他の例では、燃焼排ガスＥのＮＯｘ濃度を測定するＮＯｘセンサ（図示せず）を備えても構わない。
即ち、通常気筒からの燃焼排ガスＥが通過する排気路にＮＯｘセンサを備え、制御装置５０が、ＮＯｘセンサにて検出されるＮＯｘ濃度がＮＯｘ判定閾値（例えば、５０ｐｐｍ）以上となる毎に、着火性を低減する必要があると判断し、高着火性改質ガス再循環運転状態と基準着火性改質ガス再循環運転状態と排ガス再循環運転状態とを、着火性の高い燃焼ガスを再循環する運転状態から着火性の低い燃焼ガスを再循環する運転状態へ切り換え制御する。尚、制御装置５０は、切り換え時点での運転状態が、再循環する燃焼ガスの着火性が最も低い排ガス再循環運転状態である場合、切り換え制御を行わない。 (8) In the first and second embodiments, the example in which the knock sensor and the temperature sensor S2 for detecting the temperature of the exhaust gas are provided as means for detecting the combustion state has been described.
In another example, a NOx sensor (not shown) that measures the NOx concentration of the combustion exhaust gas E may be provided.
That is, the NOx sensor is provided in the exhaust passage through which the combustion exhaust gas E from the normal cylinder passes, and the controller 50 ignites each time the NOx concentration detected by the NOx sensor becomes equal to or higher than the NOx determination threshold (for example, 50 ppm). The high ignitability reformed gas recirculation operation state, the standard ignitable reformed gas recirculation operation state, and the exhaust gas recirculation operation state are recirculated. The control is switched from the operating state to the operating state in which the combustion gas having low ignitability is recirculated. Note that the control device 50 does not perform the switching control when the operation state at the time of switching is an exhaust gas recirculation operation state in which the ignitability of the recirculated combustion gas is the lowest.

（９）上記第１実施形態において、第１燃料ガス供給部として、図１に示すように、スロットル弁２３の上流側の給気本管２０に対して燃料ガスＦを混合するように、第１燃料ガス供給路１１、差圧レギュレータ１２、ミキサ１４、及び第１燃料流量制御弁１３を備える構成例を示した。
しかしながら、図１２に示すように、通常気筒４０ａ、４０ｂ、４０ｃの夫々に燃焼用空気を導く複数の通常気筒用給気支管２０ａ、２０ｂ、２０ｃの夫々に各別に燃料ガスＦを供給するように、第１燃料ガス供給部としての第１燃料ガス供給路１１、ミキサ１４、及び第１燃料流量制御弁１３を備えるように構成しても構わない。 (9) In the first embodiment, as shown in FIG. 1, the first fuel gas supply unit is configured to mix the fuel gas F with the supply main pipe 20 upstream of the throttle valve 23. The example of a structure provided with 1 fuel gas supply path 11, the differential pressure regulator 12, the mixer 14, and the 1st fuel flow control valve 13 was shown.
However, as shown in FIG. 12, the fuel gas F is supplied to each of the plurality of normal cylinder supply branch pipes 20a, 20b, 20c for guiding the combustion air to the normal cylinders 40a, 40b, 40c. The first fuel gas supply path 11 as the first fuel gas supply unit, the mixer 14, and the first fuel flow control valve 13 may be provided.

（１０）再循環気筒での燃焼用空気Ａに含まれる酸素に対する燃料ガスＦの供給比率を制御する形態の他の構成例につき、第１実施形態及び第２実施形態の変形例を以下に示す。因みに、第１実施形態でも第２実施形態でも実質的な構成及び制御形態は同様であるので、以下では、第１実施形態を例に、説明する。
上記第１実施形態において、再循環気筒４０ｄでの燃焼用空気Ａに含まれる酸素に対する燃料ガスＦの供給比率を制御する形態で再循環気筒４０ｄでの混合気Ｍの空気過剰率を１より小さい範囲で制御する一例として、第２燃料ガス供給部としての第２燃料流量制御弁１５の開度を特定の一定開度として再循環気筒４０ｄでの混合気Ｍの空気過剰率を１より小さい範囲で制御する構成例を示した。
再循環気筒４０ｄでの燃焼用空気Ａに含まれる酸素に対する燃料ガスの供給比率を制御する形態で再循環気筒４０ｄでの混合気Ｍの空気過剰率を１より小さい範囲で制御する他の例としては、第２燃料ガス供給部としての第２燃料流量制御弁１５の開度を特定の一定開度に維持した状態で、再循環気筒４０ｄへ燃焼用空気Ａを導く第２給気支管２０ｄにスロットル弁（図示せず）を設け、当該スロットル弁の開度を制御するように構成しても構わない。
あるいは、再循環気筒４０ｄのＥＧＲ率をバルブタイミングの制御や、再循環気筒４０ｄからの燃焼ガスを通流する燃焼ガス通流路２８に設けられる排気絞り弁（図示せず）の開度の制御により、再循環気筒４０ｄでの混合気Ｍの空気過剰率を１より小さい範囲で制御する。 (10) A modification of the first embodiment and the second embodiment will be described below with respect to another configuration example for controlling the supply ratio of the fuel gas F to the oxygen contained in the combustion air A in the recirculation cylinder. . Incidentally, since the substantial configuration and control mode are the same in both the first embodiment and the second embodiment, the first embodiment will be described below as an example.
In the first embodiment, the excess air ratio of the air-fuel mixture M in the recirculation cylinder 40d is smaller than 1 in the form of controlling the supply ratio of the fuel gas F to the oxygen contained in the combustion air A in the recirculation cylinder 40d. As an example of the range control, the degree of excess air of the air-fuel mixture M in the recirculation cylinder 40d is smaller than 1 with the opening of the second fuel flow control valve 15 as the second fuel gas supply unit being a specific constant opening. An example of the configuration controlled by is shown.
As another example of controlling the excess air ratio of the air-fuel mixture M in the recirculation cylinder 40d within a range smaller than 1 in the form of controlling the supply ratio of fuel gas to oxygen contained in the combustion air A in the recirculation cylinder 40d. In the second supply branch pipe 20d that guides the combustion air A to the recirculation cylinder 40d in a state where the opening degree of the second fuel flow rate control valve 15 as the second fuel gas supply unit is maintained at a specific constant opening degree. A throttle valve (not shown) may be provided and the opening degree of the throttle valve may be controlled.
Alternatively, the EGR rate of the recirculation cylinder 40d is controlled by the valve timing, and the opening degree of the exhaust throttle valve (not shown) provided in the combustion gas passage 28 through which the combustion gas from the recirculation cylinder 40d flows. Thus, the excess air ratio of the air-fuel mixture M in the recirculation cylinder 40d is controlled within a range smaller than 1.

（１１）燃焼状態を検出する手段について、説明を追加する。
上記実施形態において、ノッキング検出手段は、ノッキング強度を検出するノックセンサを備え、当該ノックセンサにて検出されるノッキング強度（振動の強度）に基づいて、着火性を低減するか否かを判定する例を示した。他の構成として、ノッキング頻度を検出する構成を採用し、ノッキング頻度に基づいて、着火性を低減するか否かを判定しても構わない。
また、筒内圧力センサにて筒内圧力を検出し、当該筒内圧力センサにて検出される筒内圧力に基づいて、ノッキングを検出することもできる。即ち、筒内圧力センサにて検出される筒内圧力に基づいて、着火性を低減するか否かを判定するように構成しても構わない。
また、失火を検出する手段の他の例としては、筒内イオン電流センサを備える構成があり、当該筒内イオン電流センサにて検出される筒内の着火炎のイオン電流に基づいて、失火を検出することができる。
また、ノッキングを検出する手段、失火を検出する手段及びＮＯｘセンサは、単体で備える構成を採用しても構わないし、組み合わせて備える構成を採用しても構わない。 (11) A description of the means for detecting the combustion state will be added.
In the above embodiment, the knocking detection means includes a knock sensor that detects the knocking strength, and determines whether to reduce the ignitability based on the knocking strength (vibration strength) detected by the knocking sensor. An example is shown. As another configuration, a configuration for detecting the knocking frequency may be adopted, and it may be determined whether to reduce the ignitability based on the knocking frequency.
Further, the in-cylinder pressure can be detected by the in-cylinder pressure sensor, and knocking can be detected based on the in-cylinder pressure detected by the in-cylinder pressure sensor. That is, it may be configured to determine whether to reduce the ignitability based on the in-cylinder pressure detected by the in-cylinder pressure sensor.
As another example of means for detecting misfire, there is a configuration including an in-cylinder ion current sensor, and misfire is detected based on the ion current of the in-cylinder ignition flame detected by the in-cylinder ion current sensor. Can be detected.
Further, the means for detecting knocking, the means for detecting misfire, and the NOx sensor may adopt a configuration provided alone or a configuration provided in combination.

（１２）上記第１実施形態では、触媒バイパス路９４及び流量比制御弁９３を備える構成例を示したが、図１３に示すように、当該触媒バイパス路９４及び流量比制御弁９３を備えない構成を採用しても構わない。
具体的には、再循環気筒４０ｄから通常気筒４０ａ、４０ｂ、４０ｃへ導かれる燃焼ガス（改質ガスＫ）を通流する燃焼ガス通流路２８（触媒流路の一例）に触媒９２を備え、着火性制御手段５１としての制御装置５０は、燃焼ガスの空気過剰率がいずれの値にある場合にも、燃焼ガス（改質ガスＫ）の全量を触媒９２へ導くように構成されている。
当該構成により、通常気筒４０ａ、４０ｂ、４０ｃへ再循環される改質ガスＫの水素濃度は、図９にて実線で示されるように、再循環気筒４０ｄへ導かれる混合気Ｍの当量比φ（空気過剰率の逆数）を１から１．５までの間で変化させた時に、当量比φに対して正の相関を有する状態で、零から１２％程度まで変化させることができる。 (12) In the first embodiment, the configuration example including the catalyst bypass passage 94 and the flow rate control valve 93 has been described. However, as illustrated in FIG. 13, the catalyst bypass passage 94 and the flow rate control valve 93 are not provided. A configuration may be adopted.
Specifically, the catalyst 92 is provided in the combustion gas passage 28 (an example of the catalyst passage) through which the combustion gas (reformed gas K) guided from the recirculation cylinder 40d to the normal cylinders 40a, 40b, and 40c flows. The control device 50 as the ignitability control means 51 is configured to guide the entire amount of combustion gas (reformed gas K) to the catalyst 92 regardless of the value of the excess air ratio of the combustion gas. .
With this configuration, the hydrogen concentration of the reformed gas K that is recirculated to the normal cylinders 40a, 40b, and 40c is equal to the equivalent ratio φ of the air-fuel mixture M that is guided to the recirculation cylinder 40d, as shown by the solid line in FIG. When the (reciprocal of the excess air ratio) is changed between 1 and 1.5, it can be changed from zero to about 12% in a state having a positive correlation with the equivalence ratio φ.

（１３）上記実施形態にあっては、制御装置５０は、排ガス再循環状態を実行するように構成している例を示した。しかしながら、本願にあっては、排ガス再循環状態を実行しないものも権利範囲に含むものとする。 (13) In the above embodiment, the control device 50 has been configured to execute the exhaust gas recirculation state. However, in the present application, those that do not execute the exhaust gas recirculation state are also included in the scope of rights.

（１４）上記第１実施形態にあっては、制御装置５０は、改質ガス再循環運転状態において設定される空気過剰率が再循環気筒４０ｄで失火が起きない範囲で最小の空気過剰率である下限空気過剰率（当該第１実施形態では、図９において一点鎖線で示すように、当量比が１．５のとき）であるときに、触媒９２に改質ガスＫを通流させる形態で、水性ガスシフト反応制御を実行する構成例を示した。
しかしながら、制御装置５０は、下限空気過剰率よりも大きい空気過剰率において、水性ガスシフト反応制御を実行しても構わない。
例えば、制御装置５０は、準高着火性改質ガス再循環運転状態と基準着火性改質ガス再循環運転状態と排ガス再循環運転状態とにおいて、流量比制御弁９３の開度を制御する形態で、触媒９２に通流する改質ガスＫの流量を零とし、高着火性改質ガス再循環運転状態において、流量比制御弁９３の開度を制御する形態で、触媒９２に通流する改質ガスＫの流量を零より大きい値に制御するように構成しても構わない。
当該制御は、触媒バイパス路９４及び流量比制御弁９３を備える他の実施形態においても好適に実行できる。 (14) In the first embodiment, the control device 50 has a minimum excess air ratio within a range in which misfire does not occur in the recirculation cylinder 40d in the reformed gas recirculation operation state. In a form in which the reformed gas K is caused to flow through the catalyst 92 when the lower limit excess air ratio is present (in the first embodiment, as shown by the one-dot chain line in FIG. 9, when the equivalence ratio is 1.5). In addition, a configuration example for executing the water gas shift reaction control has been shown.
However, the control device 50 may execute the water gas shift reaction control at an excess air ratio larger than the lower limit excess air ratio.
For example, the control device 50 controls the opening degree of the flow rate control valve 93 in the semi-highly ignited reformed gas recirculation operation state, the reference ignitable reformed gas recirculation operation state, and the exhaust gas recirculation operation state. Thus, the flow rate of the reformed gas K flowing through the catalyst 92 is set to zero, and the flow rate of the flow rate control valve 93 is controlled to flow through the catalyst 92 in the highly ignitable reformed gas recirculation operation state. The flow rate of the reformed gas K may be controlled to a value larger than zero.
This control can also be suitably executed in other embodiments including the catalyst bypass 94 and the flow rate control valve 93.

（１５）上記実施形態にあっては、着火時期検出手段として、筒内圧力センサ４１を備える例を示した。
当該着火時期検出手段としては、予混合圧縮着火エンジン本体４０の燃焼室内に設けられ、燃焼室内の自着火炎によるイオン電流を検出するイオンプロ―ブ、予混合圧縮着火エンジン本体４０に設けられ、エンジン本体の機関振動により着火を検出する加速度計を、好適に採用することができる。 (15) In the above embodiment, an example in which the cylinder pressure sensor 41 is provided as the ignition timing detection means has been described.
The ignition timing detection means is provided in the combustion chamber of the premixed compression ignition engine main body 40, provided in the premixed compression ignition engine main body 40, an ion probe for detecting an ionic current due to the self-ignition flame in the combustion chamber, An accelerometer that detects ignition by engine vibration of the engine body can be suitably employed.

（１６）上記第１実施形態にあっては、着火時期の制御に関し、着火性制御手段５１としての制御装置５０による空気過剰率制御及び水性ガスシフト反応制御を実行することにより、着火時期を目標着火時期に制御する構成例を示した。
本願にあっては、上記構成に加えて、制御装置５０が、インタークーラ２２による給気温度制御により、着火時期を制御する構成をも権利範囲に含むものである。
具体的には、制御装置５０は、着火時期判定部５２により判定された着火時期が、目標着火時期よりも早いときには、温度センサＳ１により測定される給気温度に基づいてインタークーラ２２による給気の冷却度合を高め、着火時期が目標着火時期よりも遅いときには、温度センサＳ１により測定される給気温度に基づいてインタークーラ２２による給気の冷却度合を低める形態で、着火時期を目標着火時期に制御する構成をも含むものである。 (16) In the first embodiment, regarding the ignition timing control, the ignition timing is set to the target ignition timing by executing the excess air ratio control and the water gas shift reaction control by the control device 50 as the ignitability control means 51. A configuration example to control at the time is shown.
In the present application, in addition to the above-described configuration, the control device 50 includes a configuration in which the ignition timing is controlled by the supply air temperature control by the intercooler 22 within the scope of the right.
Specifically, when the ignition timing determined by the ignition timing determination unit 52 is earlier than the target ignition timing, the control device 50 supplies air by the intercooler 22 based on the supply air temperature measured by the temperature sensor S1. When the ignition timing is later than the target ignition timing, the ignition timing is set to the target ignition timing in such a manner that the cooling degree of the supply air by the intercooler 22 is reduced based on the supply air temperature measured by the temperature sensor S1. This also includes a configuration to control.

尚、上記実施形態（別実施形態を含む、以下同じ）で開示される構成は、矛盾が生じない限り、他の実施形態で開示される構成と組み合わせて適用することが可能であり、また、本明細書において開示された実施形態は例示であって、本発明の実施形態はこれに限定されず、本発明の目的を逸脱しない範囲内で適宜改変することが可能である。   The configuration disclosed in the above embodiment (including another embodiment, the same shall apply hereinafter) can be applied in combination with the configuration disclosed in the other embodiment, as long as no contradiction occurs. The embodiment disclosed in this specification is an exemplification, and the embodiment of the present invention is not limited to this. The embodiment can be appropriately modified without departing from the object of the present invention.

本発明のエンジンシステム、及びその制御方法は、比較的簡易な構成を維持しながらも、着火性の制御を良好に行うことができると共に、その運転範囲を大幅に拡大することができるエンジンシステム、及びその制御方法として、有効に利用可能である。   The engine system of the present invention and the control method thereof are capable of well controlling the ignitability while maintaining a relatively simple configuration, and can greatly expand the operating range thereof. And as a control method thereof, it can be effectively used.

１１ ：第１燃料ガス供給路
１３ ：第１燃料流量制御弁
１５ ：第２燃料流量制御弁
２８ ：燃焼ガス通流路
２９ ：第２燃料ガス供給路
４０ ：予混合圧縮着火エンジン本体
４０ａ、４０ｂ、４０ｃ：通常気筒
４０ｄ ：再循環気筒
５０ ：制御装置
５１ ：着火性制御手段
５２ ：着火時期判定部
６１ ：第２燃料ガス供給路
６３ ：第２燃料流量制御弁
８０ ：補助エンジン本体
８０ａ、８０ｂ、８０ｃ、８０ｄ：再循環気筒
９０ ：三方切換弁
９２ ：触媒
９３ ：流量比制御弁
９４ ：触媒バイパス路
９１ ：ＥＧＲクーラ
１００ ：エンジンシステム
２００ ：エンジンシステム
２００ａ ：補助エンジン
２００ｂ ：予混合圧縮着火エンジン
Ａ ：燃焼用空気
Ｅ ：燃焼排ガス
Ｆ ：燃料ガス
Ｋ ：改質ガス 11: 1st fuel gas supply path 13: 1st fuel flow control valve 15: 2nd fuel flow control valve 28: Combustion gas flow path 29: 2nd fuel gas supply path 40: Premix compression ignition engine main body 40a, 40b 40c: normal cylinder 40d: recirculation cylinder 50: controller 51: ignitability control means 52: ignition timing determination unit 61: second fuel gas supply path 63: second fuel flow rate control valve 80: auxiliary engine main bodies 80a, 80b 80c, 80d: Recirculation cylinder 90: Three-way switching valve 92: Catalyst 93: Flow rate control valve 94: Catalyst bypass 91: EGR cooler 100: Engine system 200: Engine system 200a: Auxiliary engine 200b: Premixed compression ignition engine A: Combustion air E: Combustion exhaust gas F: Fuel gas K: Reformed gas

Claims (9)

燃料ガスと燃焼用空気との混合気を圧縮着火させ燃焼させるエンジンシステムであって、
混合気を燃焼する通常気筒を少なくとも１つ備えると共に、混合気を燃焼すると共に燃焼後の燃焼ガスを少なくとも前記通常気筒へ再循環可能な再循環気筒を備え、
少なくとも前記通常気筒へ燃料ガスを供給する第１燃料ガス供給部と、前記再循環気筒へ燃料ガスを供給する第２燃料ガス供給部とを各別に備え、
前記再循環気筒から前記通常気筒へ導かれる前記燃焼ガスの少なくとも一部を水性ガスシフト反応させる触媒を備え、
前記再循環気筒での燃焼用空気に含まれる酸素に対する燃料ガスの供給比率を制御する形態で前記再循環気筒での混合気の空気過剰率を１より小さくして混合気の少なくとも一部を燃焼させ部分酸化反応させて燃料ガスよりも着火性の高い高着火性ガスが含まれる前記燃焼ガスとしての改質ガスを前記再循環気筒にて生成して再循環させる改質ガス再循環運転状態を実行可能に構成され、
前記改質ガス再循環運転状態にあるときに、前記再循環気筒にて生成される前記改質ガスの少なくとも一部を前記触媒へ通流させる水性ガスシフト反応制御を実行可能に構成されているエンジンシステム。 An engine system that compresses and ignites an air-fuel mixture of fuel gas and combustion air,
Including at least one normal cylinder for combusting the air-fuel mixture, and having a recirculation cylinder for combusting the air-fuel mixture and recirculating the combustion gas after combustion to at least the normal cylinder;
A first fuel gas supply unit for supplying fuel gas to at least the normal cylinder and a second fuel gas supply unit for supplying fuel gas to the recirculation cylinder;
A catalyst for causing a water gas shift reaction of at least a part of the combustion gas guided from the recirculation cylinder to the normal cylinder;
Combusting at least a part of the air-fuel mixture by reducing the excess air ratio of the air-fuel mixture in the recirculation cylinder to less than 1 in the form of controlling the supply ratio of fuel gas to oxygen contained in the combustion air in the recirculation cylinder A reformed gas recirculation operation state in which the reformed gas as the combustion gas containing the highly ignitable gas having higher ignitability than the fuel gas by the partial oxidation reaction is generated and recirculated in the recirculation cylinder. Configured to run,
An engine configured to execute water gas shift reaction control that allows at least part of the reformed gas generated in the recirculation cylinder to flow to the catalyst when in the reformed gas recirculation operation state. system. 燃料ガスと燃焼用空気との混合気を圧縮着火させ燃焼させる通常気筒を少なくとも一つ有すると共に、混合気を形成する燃料ガスを供給する第１燃料ガス供給部を有する予混合圧縮着火エンジンを備えたエンジンシステムであって、
混合気を燃焼すると共に燃焼後の燃焼ガスを前記通常気筒へ再循環可能な再循環気筒を有すると共に、前記再循環気筒へ燃料ガスを供給する第２燃料ガス供給部を前記第１燃料ガス供給部とは別に有する補助エンジンを備え、
前記再循環気筒から前記通常気筒へ導かれる前記燃焼ガスの少なくとも一部を水性ガスシフト反応させる触媒を備え、
前記再循環気筒での燃焼用空気に含まれる酸素に対する燃料ガスの供給比率を制御する形態で前記再循環気筒での混合気の空気過剰率を１より小さくして混合気の少なくとも一部を燃焼させ部分酸化反応させて燃料ガスよりも着火性の高い高着火性ガスが含まれる前記燃焼ガスとしての改質ガスを前記再循環気筒にて生成して再循環させる改質ガス再循環運転状態を実行可能に構成され、
前記改質ガス再循環運転状態にあるときに、前記再循環気筒にて生成される前記改質ガスの少なくとも一部を前記触媒へ通流させる水性ガスシフト反応制御を実行可能に構成されているエンジンシステム。 A premixed compression ignition engine having at least one normal cylinder for compressing and igniting and burning an air-fuel mixture of fuel gas and combustion air and having a first fuel gas supply unit for supplying fuel gas forming the air-fuel mixture Engine system,
The first fuel gas supply includes a recirculation cylinder capable of combusting the air-fuel mixture and recirculating the combustion gas after combustion to the normal cylinder, and supplying a fuel gas to the recirculation cylinder. Auxiliary engine that has separate from the part,
A catalyst for causing a water gas shift reaction of at least a part of the combustion gas guided from the recirculation cylinder to the normal cylinder;
Combusting at least a part of the air-fuel mixture by reducing the excess air ratio of the air-fuel mixture in the recirculation cylinder to less than 1 in the form of controlling the supply ratio of fuel gas to oxygen contained in the combustion air in the recirculation cylinder A reformed gas recirculation operation state in which the reformed gas as the combustion gas containing the highly ignitable gas having higher ignitability than the fuel gas by the partial oxidation reaction is generated and recirculated in the recirculation cylinder. Configured to run,
An engine configured to execute water gas shift reaction control that allows at least part of the reformed gas generated in the recirculation cylinder to flow to the catalyst when in the reformed gas recirculation operation state. system. 前記改質ガス再循環運転状態において前記再循環気筒での燃焼用空気に含まれる酸素に対する燃料ガスの供給比率を制御する形態で前記再循環気筒での混合気の空気過剰率を１より小さい範囲で制御する空気過剰率制御と、前記改質ガス再循環運転状態における前記水性ガスシフト反応制御との少なくとも何れか一方を実行する形態で、前記通常気筒での着火性を制御する着火性制御手段を備える請求項１又は２に記載のエンジンシステム。   The excess air ratio of the air-fuel mixture in the recirculation cylinder is smaller than 1 in the form of controlling the supply ratio of the fuel gas to the oxygen contained in the combustion air in the recirculation cylinder in the reformed gas recirculation operation state. An ignitability control means for controlling the ignitability in the normal cylinder in a form in which at least one of the excess air ratio control controlled by the control and the water gas shift reaction control in the reformed gas recirculation operation state is executed. The engine system according to claim 1 or 2 provided. 前記通常気筒での着火時期を検出する着火時期検出手段を備え、
前記着火性制御手段は、前記着火時期検出手段にて検出される前記着火時期が目標着火時期よりも遅角化している場合に、前記通常気筒での着火性を向上させ、前記着火時期検出手段にて検出される前記着火時期が目標着火時期よりも進角化している場合に、着火性を低減させる請求項３に記載のエンジンシステム。 Ignition timing detecting means for detecting the ignition timing in the normal cylinder,
The ignitability control means improves the ignitability in the normal cylinder when the ignition timing detected by the ignition timing detection means is retarded from a target ignition timing, and the ignition timing detection means The engine system according to claim 3, wherein the ignitability is reduced when the ignition timing detected in step 1 is advanced from a target ignition timing. 前記再循環気筒から前記通常気筒へ導かれる前記燃焼ガスを通流すると共に前記触媒が設けられる触媒流路と、前記触媒流路を通流する前記燃焼ガスに前記触媒をバイパスさせる触媒バイパス路と、前記触媒流路を通流する前記燃焼ガスの流量と前記触媒バイパス路を通流する前記燃焼ガスの流量との流量比を制御する流量比制御弁とを備え、
前記着火性制御手段は、前記水性ガスシフト反応制御において、前記流量比制御弁の開度を制御する形態で、前記触媒を通流させて前記水性ガスシフト反応させる前記改質ガスの流量を制御するシフト反応制御手段として働く請求項３又は４に記載のエンジンシステム。 A catalyst flow path through which the combustion gas guided from the recirculation cylinder to the normal cylinder flows and the catalyst is provided; a catalyst bypass path for bypassing the catalyst to the combustion gas flowing through the catalyst flow path; A flow ratio control valve for controlling a flow ratio between the flow rate of the combustion gas flowing through the catalyst flow path and the flow rate of the combustion gas flowing through the catalyst bypass path,
In the water gas shift reaction control, the ignitability control means controls the flow rate of the reformed gas that causes the water gas shift reaction to flow through the catalyst in the form of controlling the opening degree of the flow rate control valve. The engine system according to claim 3 or 4, which functions as a reaction control means. 前記改質ガス再循環運転状態は、前記通常気筒へ前記燃焼ガスを再循環しない場合の前記通常気筒での混合気の着火性を基準着火性としたときに、前記基準着火性よりも低い着火性の前記改質ガスを再循環させる準高着火性改質ガス再循環運転状態と、前記基準着火性と同一の着火性の前記改質ガスを再循環させる基準着火性改質ガス再循環運転状態と、前記基準着火性よりも高い着火性の前記改質ガスを再循環させる高着火性改質ガス再循環運転状態と、を含むものであり、
前記シフト反応制御手段は、少なくとも前記準高着火性改質ガス再循環運転状態と前記基準着火性改質ガス再循環運転状態とにあるときに、前記流量比制御弁により前記触媒流路へ通流する前記改質ガスの流量を零とし、前記高着火性改質ガス再循環運転状態にあるときに、前記流量比制御弁により前記触媒流路へ通流する前記改質ガスの流量を零より大きい範囲で制御する形態で、前記水性ガスシフト反応制御を実行する請求項５に記載のエンジンシステム。 The reformed gas recirculation operation state is lower than the reference ignitability when the ignitability of the air-fuel mixture in the normal cylinder when the combustion gas is not recirculated to the normal cylinder is set as the reference ignitability. The semi-highly ignitable reformed gas recirculation operation state for recirculating the reformed gas having the same property and the reference ignitable reformed gas recirculation operation for recirculating the reformed gas having the same ignitability as the reference ignitability And a high ignitability reformed gas recirculation operation state in which the reformed gas having an ignitability higher than the reference ignitability is recirculated,
When the shift reaction control means is at least in the semi-highly ignited reformed gas recirculation operation state and the reference ignitable reformed gas recirculation operation state, the shift ratio control valve passes the shift reaction control means to the catalyst flow path. The flow rate of the reformed gas flowing is zero, and when the highly ignitable reformed gas recirculation operation is in progress, the flow rate of the reformed gas flowing through the catalyst flow path by the flow rate control valve is zero. The engine system according to claim 5, wherein the water gas shift reaction control is executed in a form in which control is performed in a larger range. 前記再循環気筒から前記通常気筒へ導かれる前記燃焼ガスを通流すると共に前記触媒が設けられる触媒流路を備え、
前記着火性制御手段は、前記改質ガス再循環運転状態にて設定される前記再循環気筒での空気過剰率に関わらず、前記燃焼ガスの全量を前記触媒へ通流する請求項３又は４に記載のエンジンシステム。 A catalyst flow path for passing the combustion gas guided from the recirculation cylinder to the normal cylinder and provided with the catalyst;
The ignitability control means allows the entire amount of the combustion gas to flow to the catalyst regardless of the excess air ratio in the recirculation cylinder set in the reformed gas recirculation operation state. The engine system described in. 燃料ガスと燃焼用空気との混合気を圧縮着火させ燃焼させるエンジンシステムの制御方法であって、
混合気を燃焼する通常気筒を少なくとも１つ備えると共に、混合気を燃焼すると共に燃焼後の燃焼ガスを少なくとも前記通常気筒へ再循環可能な再循環気筒を備え、
少なくとも前記通常気筒へ燃料ガスを供給する第１燃料ガス供給部と、前記再循環気筒へ燃料ガスを供給する第２燃料ガス供給部とを各別に備え、
前記再循環気筒から前記通常気筒へ導かれる前記燃焼ガスの少なくとも一部を水性ガスシフト反応させる触媒を備えた構成において、
前記再循環気筒での燃焼用空気に含まれる酸素に対する燃料ガスの供給比率を制御する形態で前記再循環気筒での混合気の空気過剰率を１より小さくして混合気の少なくとも一部を燃焼させ部分酸化反応させて燃料ガスよりも着火性の高い高着火性ガスが含まれる前記燃焼ガスとしての改質ガスを前記再循環気筒にて生成して再循環させる改質ガス再循環運転状態を実行するように制御され、
前記改質ガス再循環運転状態にあるときに、前記再循環気筒にて生成される前記改質ガスの少なくとも一部を前記触媒へ通流させる水性ガスシフト反応制御を実行するように制御されるエンジンシステムの制御方法。 A control method for an engine system for compressing and igniting a mixture of fuel gas and combustion air for combustion,
Including at least one normal cylinder for combusting the air-fuel mixture, and having a recirculation cylinder for combusting the air-fuel mixture and recirculating the combustion gas after combustion to at least the normal cylinder;
A first fuel gas supply unit for supplying fuel gas to at least the normal cylinder and a second fuel gas supply unit for supplying fuel gas to the recirculation cylinder;
In a configuration including a catalyst that causes a water gas shift reaction of at least a part of the combustion gas guided from the recirculation cylinder to the normal cylinder,
Combusting at least a part of the air-fuel mixture by reducing the excess air ratio of the air-fuel mixture in the recirculation cylinder to less than 1 in the form of controlling the supply ratio of fuel gas to oxygen contained in the combustion air in the recirculation cylinder A reformed gas recirculation operation state in which the reformed gas as the combustion gas containing the highly ignitable gas having higher ignitability than the fuel gas by the partial oxidation reaction is generated and recirculated in the recirculation cylinder. Controlled to run,
An engine that is controlled to execute water gas shift reaction control for allowing at least a part of the reformed gas generated in the recirculation cylinder to flow to the catalyst when in the reformed gas recirculation operation state. How to control the system. 燃料ガスと燃焼用空気との混合気を圧縮着火させ燃焼させる通常気筒を少なくとも一つ有すると共に、混合気を形成する燃料ガスを供給する第１燃料ガス供給部を有する予混合圧縮着火エンジンを備えたエンジンシステムの制御方法であって、
混合気を燃焼すると共に燃焼後の燃焼ガスを前記通常気筒へ再循環可能な再循環気筒を有すると共に、前記再循環気筒へ燃料ガスを供給する第２燃料ガス供給部を前記第１燃料ガス供給部とは別に有する補助エンジンを備え、
前記再循環気筒から前記通常気筒へ導かれる前記燃焼ガスの少なくとも一部を水性ガスシフト反応させる触媒を備えた構成において、
前記再循環気筒での燃焼用空気に含まれる酸素に対する燃料ガスの供給比率を制御する形態で前記再循環気筒での混合気の空気過剰率を１より小さくして混合気の少なくとも一部を燃焼させ部分酸化反応させて燃料ガスよりも着火性の高い高着火性ガスが含まれる前記燃焼ガスとしての改質ガスを前記再循環気筒にて生成して再循環させる改質ガス再循環運転状態を実行するように制御され、
前記改質ガス再循環運転状態にあるときに、前記再循環気筒にて生成される前記改質ガスの少なくとも一部を前記触媒へ通流させる水性ガスシフト反応制御を実行するように制御されるエンジンシステムの制御方法。 A premixed compression ignition engine having at least one normal cylinder for compressing and igniting and burning an air-fuel mixture of fuel gas and combustion air and having a first fuel gas supply unit for supplying fuel gas forming the air-fuel mixture A control method for an engine system,
The first fuel gas supply includes a recirculation cylinder capable of combusting the air-fuel mixture and recirculating the combustion gas after combustion to the normal cylinder, and supplying a fuel gas to the recirculation cylinder. Auxiliary engine that has separate from the part,
In a configuration including a catalyst that causes a water gas shift reaction of at least a part of the combustion gas guided from the recirculation cylinder to the normal cylinder,
Combusting at least a part of the air-fuel mixture by reducing the excess air ratio of the air-fuel mixture in the recirculation cylinder to less than 1 in the form of controlling the supply ratio of fuel gas to oxygen contained in the combustion air in the recirculation cylinder A reformed gas recirculation operation state in which the reformed gas as the combustion gas containing the highly ignitable gas having higher ignitability than the fuel gas by the partial oxidation reaction is generated and recirculated in the recirculation cylinder. Controlled to run,
An engine that is controlled to execute water gas shift reaction control for allowing at least a part of the reformed gas generated in the recirculation cylinder to flow to the catalyst when in the reformed gas recirculation operation state. How to control the system.
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