JP2004190640A - Premixed forced ignition type gas engine - Google Patents

Premixed forced ignition type gas engine Download PDF

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JP2004190640A
JP2004190640A JP2002362768A JP2002362768A JP2004190640A JP 2004190640 A JP2004190640 A JP 2004190640A JP 2002362768 A JP2002362768 A JP 2002362768A JP 2002362768 A JP2002362768 A JP 2002362768A JP 2004190640 A JP2004190640 A JP 2004190640A
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gas
engine
fuel
fuel gas
ratio
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JP3814247B2 (en
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Hiroyuki Endo
浩之 遠藤
Yuji Oda
裕司 小田
Hiroyuki Ishida
裕幸 石田
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Mitsubishi Heavy Industries Ltd
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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
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/12—Improving ICE efficiencies
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/30—Use of alternative fuels, e.g. biofuels

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  • Combined Controls Of Internal Combustion Engines (AREA)
  • Combustion Methods Of Internal-Combustion Engines (AREA)
  • Output Control And Ontrol Of Special Type Engine (AREA)

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas engine capable of reducing throttle loss. <P>SOLUTION: First and second fuel gas supply pipes 111 and 112 to which first and second flow rate control valves 81 and 82 are respectively attached are connected to first and second fuel gas tanks 71 and 72 for respectively storing hydrogen gas and methane gas. A mixed fuel gas supply pipe 113 wherein the first and the second fuel gas supply pipes are aggregated are connected to a mixer 20, the mixed fuel gas wherein first fuel gas and second fuel gas are mixed is mixed with air flowing from an air cleaner 10 in the mixer. The mixture is pressurized by a turbocharger 30, cooled by a cooler 40, and is supplied to the engine 50. A controller 90 adjusts the opening of the first and the second flow rate control valves, and controls a mixing ratio of the hydrogen gas and the methane gas. For example, the ratio of the hydrogen gas is increased at low load, and the ratio of the hydrogen gas is reduced at high load. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、燃料ガスを空気と予め混合し、この燃料ガスと空気の混合気を点火手段で点火する、予混合強制点火式のガスエンジンに関する。
【０００２】
【従来の技術】
燃料ガスを空気と予め混合し、この燃料ガスと空気の混合気を点火手段で点火する、予混合強制点火式のガスエンジンが発電等に使用されている。例えば、特許文献１（特開２０００−３２０３６９号公報）に記載のガスエンジンがある。このようなガスエンジンにおいては使用するガス燃料は一種類であるので使用するガス燃料の可燃範囲内に混合比を制御する必要があり、例えば、都市ガスでは空気過剰率で１〜２．４程度で燃焼させる必要がある。
【０００３】
このために、低負荷域では空気量を減らすための絞りを必要とし、この絞りはスロットルロスとなりエンジンの熱効率を低下してしまう。また、高負荷域においてはこのスロットルが制限となってしまい、同じく熱効率が制限されるばかりか、夏場に空気密度が低下する際に出力が低下するという問題がある。
【０００４】
【特許文献１】
特開２０００−３２０３６９号公報
【０００５】
【発明が解決しようとする課題】
本発明は上記問題に鑑み、従来より高い空気過剰率で運転することで、スロットルロスの小さいガスエンジンを提供することを目的とする。
【０００６】
【課題を解決するための手段】
請求項１の発明によれば、燃料ガスと空気を混合して形成される予混合気に点火手段で点火する予混合強制点火式のガスエンジンであって、
互いに可燃範囲の異なる複数種類の燃料ガスを有し、該複数種類の燃料ガスを運転条件に応じた混合比で吸気管に供給することを特徴とするガスエンジンが提供される。
このように構成されるガスエンジンでは、運転条件に応じて可燃範囲を変更することができ運転条件に適した燃料ガスで運転ができ広い範囲で良好な燃焼を得ることができる。
【０００７】
請求項２の発明によれば、請求項１の発明において、エンジン負荷を検出し、エンジン負荷が小さい時には可燃範囲の広い燃料の割合を大きくし、エンジン負荷が大きい時には可燃範囲の広い燃料の割合を小さくすることを特徴とするガスエンジンが提供される。
このように構成されるガスエンジンでは、エンジン負荷が小さい時には要求発熱量は小さく、必要な燃料は少なくてよい、すなわち、大きな空気過剰率で運転することがのぞまれる。そこで、可燃範囲の広い燃料の割合を大きくして大きな空気過剰率で運転可能とする。
一方、エンジン負荷が大きいときにはノッキングが発生しやすいので可燃範囲の広い燃料の割合を小さくして燃焼速度を低下せしめてノッキングの発生を抑制する。
【０００８】
請求項３の発明によれば、請求項１の発明において、空気過剰率をもとめ、空気過剰率が大きいほど可燃範囲の広い燃料ガスの割合を大きくすることを特徴とするガスエンジンが提供される。
このように構成されるガスエンジンでは、空気過剰率が大きくなっても可燃範囲の広い燃料ガスの割合を大きくすることによりエンジンは良好に燃焼することができる。
【０００９】
請求項４の発明によれば、請求項１の発明において、ノッキングを検出し、ノッキングが発生したら可燃範囲の広い燃料ガスの割合を小さくすることを特徴とするガスエンジンが提供される。
このように構成されるガスエンジンでは、ノッキングは燃焼速度が大きくなりすぎることにより発生するものであるので、可燃範囲が広い燃料ガスの割合を小さくすれば燃料ガスが燃焼しにくい方向にシフトし燃焼速度が減少しノッキングの発生が抑制される。
【００１０】
請求項５の発明によれば、請求項１の発明において、失火を検出し、失火が発生したら可燃範囲の広い燃料ガスの割合を大きくすることを特徴とするガスエンジンが提供される。
このように構成されるガスエンジンでは、失火は燃料ガスが燃焼しうる可燃範囲を超える空気過剰率とされることにより発生するので、可燃範囲が広い燃料ガスの割合を大きくすれば燃焼しうる可燃範囲が拡大するので失火が抑制される。
【００１１】
請求項６の発明によれば、請求項１の発明において、エンジンが副室を備える副室式エンジンであって、副室に可燃範囲の広い燃料ガスを多く供給することを特徴とするガスエンジンが提供される。
このように構成されるガスエンジンでは、副室に可燃範囲の広い燃料ガスを多く供給することにより空気副室内における空気過剰率がばらついても安定して主混合気を着火させる火種を生成することができる。
【００１２】
【発明の実施の形態】
以下、添付の図面を参照して本発明の各実施の形態を説明する。
初めに、各実施の形態に共通なハード構成について説明する。図１が各実施の形態の構成を概念的に示す図であって、エアクリーナ１０に第１吸気管１０１の一端が取り付けられ、第１吸気管１０１の他端はターボチャージャー３０のタービン部３１に接続されている。
【００１３】
第１吸気管１０１には空気流量を計測する空気流量計１１が付設され、その下流には、エアクリーナ１０から吸い込まれた空気に燃料ガスを混入するためのミキサ２０が介装されている。
ターボチャージャー３０のタービン部３１の下流側には第２吸気管１０２を介して混合気を冷却するためのインタークーラー４０が接続され、インタークーラー４０には第３吸気管１０３を介してエンジン５０が接続され、エンジン５０は発電機６０を駆動する。エンジン５０の排気ガスが排気管１０４を介してターボチャージャー３０のコンプレッサ部３２に接続されている。
【００１４】
第１燃料ガスタンク７１には第１燃料ガスとしての水素（Ｈ2）ガスが貯蔵され、第２燃料ガスタンク７２には第２燃料ガスとしてのメタン（ＣＨ4）ガスが貯蔵されている。第１、第２燃料ガスタンク７１、７２には第１、第２燃料ガス供給管１１１、１１２が接続され、第１、第２燃料ガス供給管１１１、１１２にはそれぞれ第１、第２流量制御弁８１、８２が介装されている。
【００１５】
第１、第２燃料ガス供給管１１１、１１２は混合燃料ガス供給管１１３に集合され、混合燃料ガス供給管１１３はミキサー２０に接続され、第１燃料ガスと第２燃料ガスが混合された混合燃料ガスはミキサー２０においてエアクリーナ１０から流入した空気と混合され、ターボチャージャー３０で加圧され、その後、インタークーラー４０で冷却されてからエンジン５０に供給される。
【００１６】
図２はエンジン５０の構造を示す図であって、エンジン５０はシリンダ５１とシリンダ５１内を往復動するピストン５２を有する。シリンダ５１にはシリンダヘッド５３に形成されている吸気ポート５３ｉと排気ポート５３ｅが接続され、吸気ポート５３ｉと排気ポート５３ｅは、それぞれ、吸気弁５４ｉと排気弁５４ｅで開閉される。
【００１７】
シリンダヘッド５３の下部の中央部分には副室形成部材５５が埋め込まれている。副室形成部材５５の内部には上側の上部室５５ｕと下側の副室５５ｃが形成されており、上部室５５ｕと副室５５ｃは副室バルブ５５ｖが開いたときに連通され、閉じたときには非連通にされる。上部室５５ｕには副室用燃料管５５ｉが接続され燃料ガスが供給される。上部室５５ｕに供給される燃料ガスは副室バルブ５５ｖが開いたときに副室５５ｃに導入される。副室５５ｃに導入された燃料ガスは副室５５ｃに配設された点火栓５６により点火されて燃焼し、燃焼ガスを発生する。
【００１８】
副室内で生成された燃焼ガスは副室形成部材５５の下端に形成された複数の噴孔５５ｊからシリンダ５１内に噴出する。シリンダ５１内に噴出した燃焼ガスは、吸気ポート５３ｉからシリンダ５１内に導入されたメインの混合気（燃料ガス（＝第１燃料ガス＋第２燃料ガス）＋空気）を点火し、その結果生成される燃焼ガスによりエンジン５０は動力を発生して発電機６０を駆動し電力を生成する。
【００１９】
図１において、参照符号９０で示されているのはコントローラであって、各実施の形態において、コントローラ９０からの制御信号により第１、第２流量制御弁８１、８２の開度が調整され第１燃料と第２燃料の混合比が制御される。
【００２０】
以下、各実施の形態における第１燃料と第２燃料の混合比の制御について説明する。
初めに、第１の実施の形態における第１燃料と第２燃料の混合比の制御について説明する。第１の実施の形態においては、コントローラ９０に発電機６０から負荷を示す信号が送られる。コントローラ９０は図３に示すような負荷に対する第１燃料と第２燃料の混合比のマップを記憶しており、発電機６０から送られる負荷に応じた混合比となるように第１、第２流量制御弁８１、８２の開度を調整する。そして、図３に示されるように、負荷が小さい場合には水素ガスの割合が大きくされ、負荷が大きい場合には水素ガスの割合が小さくされている。
【００２１】
エンジン負荷が小さい時には要求発熱量は小さく、必要とされる燃料は少ないが、上述した第１の実施の形態のように、可燃範囲の広い燃料の割合を大きくすれば、大きな空気過剰率で運転可能となるので、スロットルで空気流量を絞る割合が小さくて済む。その結果、スロットルロスが減り、燃焼効率が向上する。
一方、エンジン負荷が大きいときにはノッキングが発生しやすいが、上述のように可燃範囲の広い燃料の割合を小さくすることにより燃焼速度が低下するのでノッキングの発生が抑制される。
【００２２】
なお、この水素ガスとメタンガスの混合ガスと、エアクリーナ１０から吸入される空気流量の比、すなわち、空気過剰率λは別途定められる。
例えば、負荷に応じて所要の燃焼ガス発熱量をもとめ、燃焼ガス発熱量から燃料ガス流量を求め、燃料ガス流量と負荷に応じて決まる空気流量から空気過剰率λは決定される。
【００２３】
次に第２の実施の形態について説明する。第１の実施の形態では上述のように負荷に応じて水素とメタンの混合比を制御していたが、この第２の実施の形態では空気過剰率λに応じて水素とメタンの混合比を制御するようにされている。
空気過剰率λは第１の実施の形態で説明したようにしてもとめる。そして、図４に示すような空気過剰率λと燃料ガスの混合比のマップを予め記憶しておき、空気過剰率λに対応した混合比になるように第１、第２流量制御弁８１、８２を制御する。図４に示されるように、空気過剰率λが大きいほど水素ガスの割合が大きくされ、空気過剰率λが小さいほど水素ガスの割合が小さくされている。
このように、第２の実施の形態では、空気過剰率λが大きい場合には可燃範囲の広い水素ガスの割合を大きくするので空気流量を絞らずに運転でき、第１の実施の形態で述べたように、スロットルロスが小さくて済む。
【００２４】
なお、第１の実施の形態の場合、第２の実施の形態の場合とも、例えば、図５に示すような負荷に対する空気過剰率λのマップを備えておけば、負荷に応じて所要の燃焼ガス発熱量をもとめ、燃焼ガス発熱量から燃料ガス流量を求め、燃料ガス流量と空気流量から空気過剰率λを計算する必要はなくなりコントローラ９０の計算負荷は低減する。
【００２５】
次に第３の実施の形態について説明する。この第３の実施の形態では、エンジン５０に図１に破線で示されるようなノックセンサ５１が付設されており、ノックセンサ５１がノッキングの発生を検出した場合には可燃範囲が広い水素ガスの割合を減少させる。このようにすることにより水素ガスに比べると燃え難いメタンガスの割合が増え、燃焼速度が低下して、ノッキングの発生が抑制される。
【００２６】
次に第４の実施の形態について説明する。この第４の実施の形態では、排気管１０５に排気ガスの圧力を検出する圧力センサ５２が取り付けられており、この圧力センサ５２の検出した排気ガスの圧力変動が予め定めた範囲を超えた場合に、エンジン５０が失火していると判定し、失火していると判定された場合には可燃範囲の広い水素ガスの流量を増大させる。失火は、空気過剰率λが大きくなりすぎて発生するものであるが、水素ガスは大きな空気過剰率λでも燃焼可能であるので水素ガスの割合を大きくすることにより失火を抑制することができる。
なお、失火判定は上述の方法の他にも色々な方法がありどのような方法でもよい。例えば、回転変動から検出する方法でもよい。
【００２７】
なお、燃料ガスはミキサ２０で第１吸気管１０１内に導入されるのみならず、エンジン５０の副室５５ｃにも導入される。副室５５ｃは第１〜３吸気管１０１〜１０３を通って導入される混合気を点火させる火種を形成するところであるので、副室５５ｃの局所的な空気過剰率λｓは、第１〜３吸気管１０１〜１０３を通って導入される混合気の空気過剰率λｍよりも大きくされている。図４、５に示した空気過剰率λは副室５５ｃに導入される燃料ガスとミキサ２０で第１吸気管１０１に導入される燃料ガスの合計に対する、吸入空気量の比である。
そして、副室５５ｃに導入するガスは可燃範囲の広い水素ガスの割合を大きくする。これはできるだけ広い条件で火種を形成できるようにするためである。
【００２８】
なお、各実施の形態で第１燃料として使用している水素の可燃範囲（空気過剰率）は０．１４〜１０．０であり、第２燃料として使用しているメタンの可燃範囲は０．６〜２．０である。
その他の燃料ガスの可燃範囲は以下のとおりである。
エタン ：０．４ 〜 １．９４
プロパン ：０．４ 〜 １．９６
ブタン ：０．３５ 〜 １．７６
エチレン ：０．１２ 〜 ２．５２
アセチレン ：０．０ 〜 ３．２８
【００２９】
【発明の効果】
各請求項に記載の発明は、燃料ガスと空気を混合して形成される予混合気に点火手段で点火する予混合強制点火式のガスエンジンであるが、互いに可燃範囲の異なる複数種類の燃料ガスを有し、該複数種類の燃料ガスを運転条件に応じた混合比で吸気管に供給するようにされており、運転条件に応じて可燃範囲を変更することができ運転条件に適した燃料ガスで運転ができ広い範囲で良好な燃焼を得ることができる。そして従来方式より高い空気過剰率で運転するのでスロットルロスが小さい。
【００３０】
特に請求項２の発明のように、エンジン負荷を検出し、エンジン負荷が小さい時には可燃範囲の広い燃料の割合を大きくし、エンジン負荷が大きい時には可燃範囲の広い燃料の割合を小さくれば、エンジン負荷が小さい時には可燃範囲の広い燃料の割合が大きいので高い空気過剰率で運転でき、エンジン負荷が大きいときには可燃範囲の広い燃料の割合が小さいので燃焼速度が低下しノッキングが発生しにくい。
特に請求項３の発明のように、空気過剰率をもとめ、空気過剰率が大きいほど可燃範囲の広い燃料ガスの割合を大きくすれば、空気過剰率が大きくなっても可燃範囲の広い燃料ガスの割合を大きくすることでエンジンは良好に燃焼することができる。
特に請求項４の発明のように、ノッキングを検出し、ノッキングが発生したら可燃範囲の広い燃料ガスの割合を小さくすれば、燃料ガスが燃焼しにくい方向にシフトし燃焼速度が減少しノッキングの発生が抑制される。
特に請求項５の発明のように、失火を検出し、失火が発生したら可燃範囲の広い燃料ガスの割合を大きくすれば、可燃範囲が拡大するので失火が抑制される。
特に請求項６の発明にように、エンジンが副室を備える副室式エンジンであって、副室に可燃範囲の広い燃料ガスを多く供給するようにすれば空気副室内における空気過剰率がばらついても安定して主混合気を着火させる火種を生成することができる。
【図面の簡単な説明】
【図１】本発明のハード構成を概略的に示す図である。
【図２】エンジンの詳細を示す図である。
【図３】負荷に対する水素とメタンの混合比を示すマップである。
【図４】空気過剰率λに対する水素とメタンの混合比を示すマップである。
【図５】負荷に対する空気過剰率λの値を示すマップである。
【符号の説明】
１０…エアクリーナ
１１…空気流量計
２０…ミキサ
３０…ターボチャージャー
４０…クーラー
５０…エンジン
５１…ノックセンサ
５２…圧力センサ
５５…副室形成部材
５５ｃ…副室
５５ｉ…副室用燃料管
５５ｊ…噴孔
５５ｖ…副室バルブ
５６…点火栓
６０…発電機
７１、７２…第１、第２燃料ガスタンク
８１、８２…第１、第２流量制御弁
９０…コントローラ
１０１、１０２、１０３…第1、第２、第３吸気管
１０４…排気管
１１１、１１２…第１、第２燃料ガス供給管
１１３…混合燃料ガス供給管[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a premixed forced ignition type gas engine in which a fuel gas is premixed with air and the mixture of the fuel gas and air is ignited by an ignition means.
[0002]
[Prior art]
2. Description of the Related Art A premixed forced ignition type gas engine in which a fuel gas is preliminarily mixed with air and a mixture of the fuel gas and air is ignited by ignition means is used for power generation and the like. For example, there is a gas engine described in Patent Document 1 (Japanese Patent Application Laid-Open No. 2000-320369). In such a gas engine, only one kind of gas fuel is used, so it is necessary to control the mixing ratio within the flammable range of the gas fuel used. For example, in city gas, the excess air ratio is about 1 to 2.4. Need to be burned.
[0003]
For this reason, in a low load region, a throttle is required to reduce the amount of air, and this throttle causes a throttle loss and lowers the thermal efficiency of the engine. Further, in a high load region, the throttle is limited, and thus not only the thermal efficiency is limited, but also the output is reduced when the air density is reduced in summer.
[0004]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 2000-320369
[Problems to be solved by the invention]
The present invention has been made in view of the above problems, and has as its object to provide a gas engine having a small throttle loss by operating at a higher excess air ratio than in the past.
[0006]
[Means for Solving the Problems]
According to the first aspect of the present invention, there is provided a gas engine of a premixed forced ignition type in which a premixed gas formed by mixing a fuel gas and air is ignited by ignition means,
There is provided a gas engine having a plurality of types of fuel gas having mutually different combustible ranges, and supplying the plurality of types of fuel gas to an intake pipe at a mixing ratio according to an operating condition.
In the gas engine configured as described above, the flammable range can be changed according to the operating conditions, and the gas engine can be operated with fuel gas suitable for the operating conditions, and good combustion can be obtained in a wide range.
[0007]
According to the second aspect of the present invention, in the first aspect of the present invention, the engine load is detected, and when the engine load is small, the proportion of fuel having a wide flammable range is increased, and when the engine load is large, the proportion of fuel having a wide flammable range is increased. The gas engine is characterized by reducing the size of the gas engine.
In the gas engine configured as described above, when the engine load is small, the required calorific value is small and the required fuel may be small, that is, it is desired that the gas engine be operated with a large excess air ratio. Therefore, the ratio of fuel having a wide combustible range is increased to enable operation with a large excess air ratio.
On the other hand, when the engine load is large, knocking is likely to occur. Therefore, the ratio of fuel having a wide flammable range is reduced to decrease the combustion speed, thereby suppressing knocking.
[0008]
According to a third aspect of the present invention, there is provided the gas engine according to the first aspect of the present invention, wherein the excess air ratio is determined, and the proportion of the fuel gas having a wider combustible range is increased as the excess air ratio increases. .
In the gas engine configured as described above, even if the excess air ratio increases, the engine can satisfactorily burn by increasing the ratio of the fuel gas having a wide flammable range.
[0009]
According to a fourth aspect of the present invention, there is provided the gas engine according to the first aspect of the present invention, wherein knocking is detected, and when knocking occurs, the proportion of fuel gas having a wide flammable range is reduced.
In a gas engine configured in this manner, knocking is caused by an excessively high combustion speed, so if the proportion of fuel gas having a wide flammable range is reduced, the fuel gas shifts in a direction in which combustion is difficult to burn, and combustion occurs. The speed is reduced, and the occurrence of knocking is suppressed.
[0010]
According to a fifth aspect of the present invention, there is provided a gas engine according to the first aspect of the present invention, wherein a misfire is detected, and when a misfire occurs, the proportion of fuel gas having a wide flammable range is increased.
In the gas engine configured as described above, misfire occurs due to an excess air ratio exceeding the flammable range in which fuel gas can burn, so if the proportion of fuel gas having a wide flammable range is increased, flammable Since the range is enlarged, misfire is suppressed.
[0011]
According to the invention of claim 6, according to the invention of claim 1, the engine is a sub-chamber type engine having a sub-chamber, wherein a large amount of fuel gas having a wide flammable range is supplied to the sub-chamber. Is provided.
In the gas engine configured as described above, by supplying a large amount of fuel gas having a wide flammable range to the sub-chamber, it is possible to generate a fire that stably ignites the main air-fuel mixture even if the excess air ratio in the air sub-chamber varies. Can be.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
First, a hardware configuration common to the embodiments will be described. FIG. 1 is a diagram conceptually showing a configuration of each embodiment. One end of a first intake pipe 101 is attached to an air cleaner 10, and the other end of the first intake pipe 101 is attached to a turbine unit 31 of a turbocharger 30. It is connected.
[0013]
An air flow meter 11 for measuring an air flow rate is attached to the first intake pipe 101, and a mixer 20 for mixing a fuel gas into air sucked from the air cleaner 10 is provided downstream of the air flow meter 11.
An intercooler 40 for cooling the air-fuel mixture is connected via a second intake pipe 102 to a downstream side of the turbine section 31 of the turbocharger 30, and an engine 50 is connected to the intercooler 40 via a third intake pipe 103. , The engine 50 drives the generator 60. The exhaust gas of the engine 50 is connected to the compressor section 32 of the turbocharger 30 via the exhaust pipe 104.
[0014]
The first fuel gas tank 71 stores hydrogen (H 2 ) gas as a first fuel gas, and the second fuel gas tank 72 stores methane (CH 4 ) gas as a second fuel gas. First and second fuel gas supply pipes 111 and 112 are connected to the first and second fuel gas tanks 71 and 72, respectively, and the first and second flow rate control are respectively connected to the first and second fuel gas supply pipes 111 and 112. Valves 81 and 82 are interposed.
[0015]
The first and second fuel gas supply pipes 111 and 112 are assembled to a mixed fuel gas supply pipe 113, and the mixed fuel gas supply pipe 113 is connected to the mixer 20 to mix the first fuel gas and the second fuel gas. The fuel gas is mixed with the air flowing from the air cleaner 10 in the mixer 20, pressurized by the turbocharger 30, and then cooled by the intercooler 40 before being supplied to the engine 50.
[0016]
FIG. 2 is a view showing the structure of the engine 50. The engine 50 has a cylinder 51 and a piston 52 reciprocating in the cylinder 51. An intake port 53i and an exhaust port 53e formed in a cylinder head 53 are connected to the cylinder 51, and the intake port 53i and the exhaust port 53e are opened and closed by an intake valve 54i and an exhaust valve 54e, respectively.
[0017]
A sub-chamber forming member 55 is buried in the lower central portion of the cylinder head 53. Inside the sub-chamber forming member 55, an upper upper chamber 55u and a lower sub-chamber 55c are formed, and the upper chamber 55u and the sub-chamber 55c are communicated when the sub-chamber valve 55v is opened and when the sub-chamber valve 55v is closed. Disconnected. The sub chamber fuel pipe 55i is connected to the upper chamber 55u, and fuel gas is supplied. The fuel gas supplied to the upper chamber 55u is introduced into the sub chamber 55c when the sub chamber valve 55v is opened. The fuel gas introduced into the sub-chamber 55c is ignited by an ignition plug 56 disposed in the sub-chamber 55c and burns to generate combustion gas.
[0018]
The combustion gas generated in the sub-chamber is injected into the cylinder 51 from a plurality of injection holes 55j formed at the lower end of the sub-chamber forming member 55. The combustion gas injected into the cylinder 51 ignites the main mixture (fuel gas (= first fuel gas + second fuel gas) + air) introduced into the cylinder 51 from the intake port 53i, and is generated as a result. The engine 50 generates power by the generated combustion gas to drive the generator 60 to generate electric power.
[0019]
In FIG. 1, reference numeral 90 denotes a controller. In each embodiment, the opening of the first and second flow control valves 81 and 82 is adjusted by a control signal from the controller 90, and The mixture ratio of the first fuel and the second fuel is controlled.
[0020]
Hereinafter, control of the mixture ratio of the first fuel and the second fuel in each embodiment will be described.
First, the control of the mixture ratio of the first fuel and the second fuel in the first embodiment will be described. In the first embodiment, a signal indicating a load is sent from the generator 60 to the controller 90. The controller 90 stores a map of the mixture ratio of the first fuel and the second fuel with respect to the load as shown in FIG. The openings of the flow control valves 81 and 82 are adjusted. Then, as shown in FIG. 3, when the load is small, the proportion of the hydrogen gas is increased, and when the load is large, the proportion of the hydrogen gas is decreased.
[0021]
When the engine load is small, the required calorific value is small and the required fuel is small. However, if the proportion of fuel having a wide flammable range is increased as in the above-described first embodiment, operation with a large excess air ratio is performed. Since it is possible, the rate of reducing the air flow rate with the throttle can be small. As a result, the throttle loss is reduced, and the combustion efficiency is improved.
On the other hand, when the engine load is large, knocking is likely to occur, but as described above, by reducing the proportion of fuel having a wide flammable range, the combustion speed is reduced, so that knocking is suppressed.
[0022]
The ratio of the mixed gas of the hydrogen gas and the methane gas to the flow rate of the air sucked from the air cleaner 10, that is, the excess air ratio λ is determined separately.
For example, the required calorific value of the combustion gas is determined according to the load, the fuel gas flow rate is determined from the calorific value of the combustion gas, and the excess air ratio λ is determined from the air flow rate determined according to the fuel gas flow rate and the load.
[0023]
Next, a second embodiment will be described. In the first embodiment, the mixture ratio of hydrogen and methane is controlled according to the load as described above. However, in the second embodiment, the mixture ratio of hydrogen and methane is controlled according to the excess air ratio λ. Have to be controlled.
The excess air ratio λ may be determined as described in the first embodiment. Then, a map of the mixing ratio between the excess air ratio λ and the fuel gas as shown in FIG. 4 is stored in advance, and the first and second flow control valves 81, so that the mixing ratio corresponds to the excess air ratio λ. 82 is controlled. As shown in FIG. 4, as the excess air ratio λ increases, the ratio of the hydrogen gas increases, and as the excess air ratio λ decreases, the ratio of the hydrogen gas decreases.
As described above, in the second embodiment, when the excess air ratio λ is large, the ratio of the hydrogen gas having a wide flammable range is increased, so that the operation can be performed without reducing the air flow rate, as described in the first embodiment. As described above, the throttle loss is small.
[0024]
In the case of the first embodiment and the case of the second embodiment, for example, if a map of the excess air ratio λ with respect to the load as shown in FIG. The calorific value of the gas is obtained, the fuel gas flow rate is obtained from the calorific value of the combustion gas, and the excess air ratio λ is not required to be calculated from the fuel gas flow rate and the air flow rate.
[0025]
Next, a third embodiment will be described. In the third embodiment, a knock sensor 51 as shown by a broken line in FIG. 1 is attached to the engine 50, and when the knock sensor 51 detects the occurrence of knocking, hydrogen gas having a wide flammable range is detected. Decrease the proportion. By doing so, the ratio of methane gas, which is less flammable than hydrogen gas, increases, the combustion speed decreases, and the occurrence of knocking is suppressed.
[0026]
Next, a fourth embodiment will be described. In the fourth embodiment, a pressure sensor 52 for detecting the pressure of the exhaust gas is attached to the exhaust pipe 105, and the pressure fluctuation of the exhaust gas detected by the pressure sensor 52 exceeds a predetermined range. Then, it is determined that the engine 50 has misfired, and if it is determined that the misfire has occurred, the flow rate of hydrogen gas having a wide flammable range is increased. Misfire occurs when the excess air ratio λ becomes too large. However, since hydrogen gas can be burned even with a large excess air ratio λ, misfire can be suppressed by increasing the proportion of hydrogen gas.
In addition, there are various methods for misfire determination other than the above method, and any method may be used. For example, a method of detecting from rotation fluctuation may be used.
[0027]
The fuel gas is introduced not only into the first intake pipe 101 by the mixer 20 but also into the sub chamber 55c of the engine 50. Since the sub-chamber 55c is to form a fire that ignites the air-fuel mixture introduced through the first to third intake pipes 101 to 103, the local excess air ratio λs of the sub-chamber 55c is The excess air ratio λm of the air-fuel mixture introduced through the tubes 101 to 103 is set to be larger. The excess air ratio λ shown in FIGS. 4 and 5 is the ratio of the intake air amount to the total of the fuel gas introduced into the sub chamber 55c and the fuel gas introduced into the first intake pipe 101 by the mixer 20.
The gas introduced into the sub-chamber 55c increases the proportion of hydrogen gas having a wide flammable range. This is to make it possible to form a fire under as wide a condition as possible.
[0028]
In each of the embodiments, the flammable range (excess air ratio) of hydrogen used as the first fuel is 0.14 to 10.0, and the flammable range of methane used as the second fuel is 0.1 to 10.0. 6 to 2.0.
The flammable ranges of other fuel gases are as follows.
Ethane: 0.4-1.94
Propane: 0.4 to 1.96
Butane: 0.35 to 1.76
Ethylene: 0.12 to 2.52
Acetylene: 0.0-3.28
[0029]
【The invention's effect】
The invention described in each claim is a premixed forced ignition type gas engine in which a premixed gas formed by mixing fuel gas and air is ignited by ignition means, but a plurality of types of fuels having different flammable ranges from each other. A plurality of fuel gases having a mixture ratio according to the operating conditions to be supplied to the intake pipe, and the flammable range can be changed according to the operating conditions. The gas can be operated and good combustion can be obtained in a wide range. And since it operates with a higher excess air ratio than the conventional system, the throttle loss is small.
[0030]
In particular, when the engine load is detected and the ratio of the fuel having a wide flammable range is increased when the engine load is small, and the ratio of the fuel having a wide flammable range is reduced when the engine load is large, the engine is detected. When the load is small, the ratio of the fuel having a wide flammable range is large, so that the operation can be performed at a high excess air ratio. When the engine load is large, the ratio of the fuel having a wide flammable range is small, so that the combustion speed is reduced and knocking does not easily occur.
In particular, as in the third aspect of the present invention, if the excess air ratio is determined and the proportion of the fuel gas having a wide flammable range is increased as the excess air ratio is increased, the fuel gas having a wide flammable range is increased even if the excess air ratio increases. The engine can burn well by increasing the ratio.
In particular, if knocking is detected and knocking occurs and the proportion of fuel gas having a wide flammable range is reduced as in the invention of claim 4, the fuel gas shifts in a direction in which it is difficult to burn, the combustion speed decreases, and knocking occurs. Is suppressed.
In particular, as in the fifth aspect of the present invention, if misfire is detected and a misfire occurs, the proportion of fuel gas having a wide flammable range is increased, so that the flammable range is expanded and misfire is suppressed.
In particular, as in the invention of claim 6, the engine is a sub-chamber type engine having a sub-chamber, and if a large amount of fuel gas having a wide combustible range is supplied to the sub-chamber, the excess air ratio in the air sub-chamber varies. However, it is possible to stably generate a fire that ignites the main air-fuel mixture.
[Brief description of the drawings]
FIG. 1 is a diagram schematically showing a hardware configuration of the present invention.
FIG. 2 is a diagram showing details of an engine.
FIG. 3 is a map showing a mixture ratio of hydrogen and methane with respect to a load.
FIG. 4 is a map showing a mixing ratio of hydrogen and methane with respect to an excess air ratio λ.
FIG. 5 is a map showing a value of an excess air ratio λ with respect to a load.
[Explanation of symbols]
Reference Signs List 10 air cleaner 11 air flow meter 20 mixer 30 turbocharger 40 cooler 50 engine 51 knock sensor 52 pressure sensor 55 sub-chamber forming member 55c sub-chamber 55i sub-chamber fuel pipe 55j injection hole 55v sub-chamber valve 56 ignition plug 60 generators 71 and 72 first and second fuel gas tanks 81 and 82 first and second flow control valves 90 controllers 101, 102 and 103 first and second. , Third intake pipe 104 ... exhaust pipes 111 and 112 ... first and second fuel gas supply pipes 113 ... mixed fuel gas supply pipes

Claims (6)

燃料ガスと空気を混合して形成される予混合気に点火手段で点火する予混合強制点火式のガスエンジンであって、
互いに可燃範囲の異なる複数種類の燃料ガスを有し、該複数種類の燃料ガスを運転条件に応じた混合比で吸気管に供給することを特徴とするガスエンジン。A premixed forced ignition type gas engine in which a premixed gas formed by mixing fuel gas and air is ignited by ignition means,
A gas engine comprising a plurality of types of fuel gases having mutually different combustible ranges, and supplying the plurality of types of fuel gases to an intake pipe at a mixing ratio according to operating conditions. エンジン負荷を検出し、エンジン負荷が小さい時には可燃範囲の広い燃料の割合を大きくし、エンジン負荷が大きい時には可燃範囲の広い燃料の割合を小さくすることを特徴とする予混合強制点火式ガスエンジン。A premixed forced ignition gas engine characterized by detecting an engine load and increasing the proportion of fuel having a wide flammable range when the engine load is small, and decreasing the proportion of fuel having a wide flammable range when the engine load is large. 空気過剰率をもとめ、空気過剰率が大きいほど可燃範囲の広い燃料ガスの割合を大きくすることを特徴とする請求項１に記載のエンジン。2. The engine according to claim 1, wherein the excess air ratio is determined, and the proportion of the fuel gas having a wider combustible range is increased as the excess air ratio increases. ノッキングを検出し、ノッキングが発生したら可燃範囲の広い燃料ガスの割合を小さくすることを特徴とする請求項１に記載のエンジン。The engine according to claim 1, wherein knocking is detected, and when knocking occurs, the ratio of fuel gas having a wide flammable range is reduced. 失火を検出し、失火が発生したら可燃範囲の広い燃料ガスの割合を大きくすることを特徴とする請求項１に記載のエンジン。2. The engine according to claim 1, wherein a misfire is detected, and when the misfire occurs, the proportion of fuel gas having a wide flammable range is increased. エンジンが副室を備える副室式エンジンであって、副室に可燃範囲の広い燃料ガスを多く供給することを特徴とする請求項１に記載のエンジン。2. The engine according to claim 1, wherein the engine is a sub-chamber type engine including a sub-chamber, and supplies a large amount of fuel gas having a wide combustible range to the sub-chamber.
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