JP2013130154A - Device for detecting leakage of gas fuel - Google Patents

Device for detecting leakage of gas fuel Download PDF

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JP2013130154A
JP2013130154A JP2011281367A JP2011281367A JP2013130154A JP 2013130154 A JP2013130154 A JP 2013130154A JP 2011281367 A JP2011281367 A JP 2011281367A JP 2011281367 A JP2011281367 A JP 2011281367A JP 2013130154 A JP2013130154 A JP 2013130154A
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gaseous fuel
pressure
fuel
fuel injection
leakage
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JP5814776B2 (en
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Yoshio Saito
芳夫 齋藤
Tomotaka Furusu
智敬 古巣
Takayuki Shimazu
隆幸 島津
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Keihin Corp
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Keihin Corp
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Priority to PCT/JP2012/082750 priority patent/WO2013094589A1/en
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D19/00—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
    • F02D19/02—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures peculiar to engines working with gaseous fuels
    • F02D19/025—Failure diagnosis or prevention; Safety measures; Testing
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D19/00—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
    • F02D19/02—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures peculiar to engines working with gaseous fuels
    • F02D19/026—Measuring or estimating parameters related to the fuel supply system
    • F02D19/027—Determining the fuel pressure, temperature or volume flow, the fuel tank fill level or a valve position
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D19/00—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
    • F02D19/06—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures peculiar to engines working with pluralities of fuels, e.g. alternatively with light and heavy fuel oil, other than engines indifferent to the fuel consumed
    • F02D19/0623—Failure diagnosis or prevention; Safety measures; Testing
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D19/00—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
    • F02D19/06—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures peculiar to engines working with pluralities of fuels, e.g. alternatively with light and heavy fuel oil, other than engines indifferent to the fuel consumed
    • F02D19/0639—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures peculiar to engines working with pluralities of fuels, e.g. alternatively with light and heavy fuel oil, other than engines indifferent to the fuel consumed characterised by the type of fuels
    • F02D19/0642—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures peculiar to engines working with pluralities of fuels, e.g. alternatively with light and heavy fuel oil, other than engines indifferent to the fuel consumed characterised by the type of fuels at least one fuel being gaseous, the other fuels being gaseous or liquid at standard conditions
    • F02D19/0647—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures peculiar to engines working with pluralities of fuels, e.g. alternatively with light and heavy fuel oil, other than engines indifferent to the fuel consumed characterised by the type of fuels at least one fuel being gaseous, the other fuels being gaseous or liquid at standard conditions the gaseous fuel being liquefied petroleum gas [LPG], liquefied natural gas [LNG], compressed natural gas [CNG] or dimethyl ether [DME]
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/0025—Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
    • F02D41/0027—Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures the fuel being gaseous
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/22—Safety or indicating devices for abnormal conditions
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D19/00—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
    • F02D19/06—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures peculiar to engines working with pluralities of fuels, e.g. alternatively with light and heavy fuel oil, other than engines indifferent to the fuel consumed
    • F02D19/0663—Details on the fuel supply system, e.g. tanks, valves, pipes, pumps, rails, injectors or mixers
    • F02D19/0686—Injectors
    • F02D19/0692—Arrangement of multiple injectors per combustion chamber
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/22—Safety or indicating devices for abnormal conditions
    • F02D2041/224—Diagnosis of the fuel system
    • F02D2041/225—Leakage detection
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D2200/00—Input parameters for engine control
    • F02D2200/02—Input parameters for engine control the parameters being related to the engine
    • F02D2200/06—Fuel or fuel supply system parameters
    • F02D2200/0602—Fuel pressure
    • 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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/40—Engine management systems

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Health & Medical Sciences (AREA)
  • Biomedical Technology (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Combined Controls Of Internal Combustion Engines (AREA)
  • Output Control And Ontrol Of Special Type Engine (AREA)

Abstract

PROBLEM TO BE SOLVED: To provide a device for detecting leakage of gas fuel that can enhance precision in detecting leakage of gas fuel.SOLUTION: The device for detecting the leakage of the gas fuel is one for detecting the leakage of the gas fuel in a high-pressure side of a pressure reducing valve interposed in a gas fuel supply route ranging from a gas fuel tank up to a gas fuel injection valve, and includes a fuel injection integrated amount calculating means for calculating a fuel injection integrated amount that is an integrated amount of the gas fuel injected from the gas fuel injection valve, a leakage threshold value setting means for setting a leakage threshold value for determining the presence of the leakage of the gas fuel, based on the fuel injection integrated amount and gas fuel pressure in the high-pressure side of the pressure reducing valve, a pressure change amount calculating means for calculating a pressure change amount of the gas fuel in the high-pressure side of the pressure reducing valve, and a fuel leakage determining means for determining the presence of the leakage of the gas fuel when the pressure change amount is higher than the leakage threshold value.

Description

本発明は、気体燃料漏れ検出装置に関する。  The present invention relates to a gaseous fuel leak detection device.

従来から、車両の燃費性能及び環境保護性能を向上させる技術として、ガソリン等の液体燃料と圧縮天然ガス（ＣＮＧ）等の気体燃料とを選択的に切替えて単一エンジンに供給するバイフューエルシステムが知られている。このバイフューエルシステムでは、気体燃料を使用する場合に、ガスタンクに充填された高圧の気体燃料をレギュレータによって所望の圧力まで減圧した後、気体燃料専用の気体燃料噴射弁に供給することが一般的である。   Conventionally, as a technology for improving the fuel efficiency and environmental protection performance of a vehicle, there is a bi-fuel system that selectively switches between liquid fuel such as gasoline and gaseous fuel such as compressed natural gas (CNG) and supplies it to a single engine. Are known. In this bi-fuel system, when using gaseous fuel, it is common to reduce the high-pressure gaseous fuel filled in the gas tank to a desired pressure with a regulator and then supply it to a gaseous fuel injection valve dedicated to gaseous fuel. is there.

下記特許文献１には、ガスタンクからレギュレータに至る燃料供給経路からの気体燃料漏れを検出する技術として、車両の走行時に圧力センサの検出する気体燃料の単位時間当りの現在圧力変化量と予め設定した単位時間当りの基本圧力変化量との比が設定値以上である場合に気体燃料の漏れと判断する技術が開示されている。  In the following Patent Document 1, as a technique for detecting a gaseous fuel leak from a fuel supply path from a gas tank to a regulator, a current pressure change amount per unit time detected by a pressure sensor when the vehicle travels is set in advance. A technique is disclosed in which it is determined that gaseous fuel has leaked when the ratio of the change in basic pressure per unit time is equal to or greater than a set value.

特開平９−２４２６１４号公報JP-A-9-242614

上記従来技術では、気体燃料漏れの判断に変化要因（例えば気体燃料噴射弁からの気体燃料噴射による圧力変化要因）を含めて単位時間当たりの漏れ判定の閾値を設定しているため、変化要因分を考慮した閾値設定ができず、漏れ検出精度が悪い。   In the above prior art, since the determination of gas fuel leakage includes a change factor (for example, a pressure change factor due to gas fuel injection from the gas fuel injection valve), a threshold value for leak determination per unit time is set. The threshold setting considering the above cannot be made, and the leak detection accuracy is poor.

本発明は、上述した事情に鑑みてなされたものであり、気体燃料の漏れ検出精度を向上可能な気体燃料漏れ検出装置を提供することを目的とする。  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide a gaseous fuel leakage detection device that can improve the accuracy of gaseous fuel leakage detection.

上記目的を達成するために、本発明では、気体燃料漏れ検出装置に係る第１の解決手段として、気体燃料タンクから気体燃料噴射弁に至る気体燃料供給経路に介挿された減圧弁より高圧側の気体燃料漏れを検出する気体燃料漏れ検出装置であって、前記気体燃料噴射弁から噴射された気体燃料の積算量である燃料噴射積算量を算出する燃料噴射積算量算出手段と、前記燃料噴射積算量及び前記減圧弁より高圧側の気体燃料圧力に基づいて前記気体燃料漏れの有無を判定するための漏れ閾値を設定する漏れ閾値設定手段と、前記減圧弁より高圧側の気体燃料の圧力変化量を算出する圧力変化量算出手段と、前記圧力変化量が前記漏れ閾値より大きい場合に前記気体燃料漏れと判定する燃料漏れ判定手段とを備える、という手段を採用する。  In order to achieve the above object, in the present invention, as a first solving means related to a gaseous fuel leakage detection device, the pressure is higher than that of a pressure reducing valve interposed in a gaseous fuel supply path from the gaseous fuel tank to the gaseous fuel injection valve. A fuel injection integrated amount calculating means for calculating a fuel injection integrated amount that is an integrated amount of gaseous fuel injected from the gaseous fuel injection valve; Leakage threshold value setting means for setting a leakage threshold value for determining the presence or absence of the gaseous fuel leakage based on the integrated amount and the gaseous fuel pressure on the high pressure side from the pressure reducing valve, and the pressure change of the gaseous fuel on the high pressure side from the pressure reducing valve A pressure change amount calculating means for calculating the amount and a fuel leak determining means for determining that the gaseous fuel leak is detected when the pressure change amount is larger than the leak threshold are employed.

また、本発明では、気体燃料漏れ検出装置に係る第２の解決手段として、上記第１の解決手段において、前記燃料噴射積算量算出手段は、前記気体燃料噴射弁による気体燃料噴射時間と、前記減圧弁より低圧側の気体燃料の圧力及び温度に基づいて前記燃料噴射積算量を算出する、という手段を採用する。  Further, in the present invention, as a second solving means relating to the gaseous fuel leakage detection device, in the first solving means, the fuel injection integrated amount calculating means includes the gaseous fuel injection time by the gaseous fuel injection valve, The fuel injection integrated amount is calculated based on the pressure and temperature of the gaseous fuel on the low pressure side from the pressure reducing valve.

また、本発明では、気体燃料漏れ検出装置に係る第３の解決手段として、上記第１または第２の解決手段において、前記漏れ閾値設定手段は、前記減圧弁より高圧側に介挿された遮断弁の開弁時には、前記燃料噴射積算量及び前記減圧弁より高圧側の気体燃料圧力に基づいて前記漏れ閾値を設定する一方、前記遮断弁の閉弁時には、予め定められた遮断弁閉弁時閾値を前記漏れ閾値として設定する、という手段を採用する。  Further, in the present invention, as a third solving means relating to the gaseous fuel leakage detection device, in the first or second solving means, the leakage threshold value setting means is a shut-off inserted on a higher pressure side than the pressure reducing valve. When the valve is opened, the leak threshold is set based on the fuel injection integrated amount and the gaseous fuel pressure on the higher pressure side than the pressure reducing valve, while when the shut-off valve is closed, a predetermined shut-off valve is closed. A means of setting a threshold value as the leakage threshold value is adopted.

本発明によれば、気体燃料噴射弁から噴射された気体燃料の積算量である燃料噴射積算量、つまり気体燃料噴射弁からの気体燃料噴射による圧力変化要因を考慮して気体燃料漏れの有無を判定するための漏れ閾値を設定するので、気体燃料の漏れ検出精度を向上させることが可能となる。  According to the present invention, the fuel injection integrated amount that is the integrated amount of the gaseous fuel injected from the gaseous fuel injection valve, that is, the presence or absence of the gaseous fuel leakage is considered in consideration of the pressure change factor due to the gaseous fuel injection from the gaseous fuel injection valve. Since the leakage threshold value for determination is set, it is possible to improve the accuracy of detecting gaseous fuel leakage.

本実施形態に係る燃料噴射システムの概略構成図である。It is a schematic structure figure of a fuel injection system concerning this embodiment. ２ｎｄ−ＥＣＵ４がエンジン運転時に実施する気体燃料漏れ検出処理を表すフローチャートである。It is a flowchart showing the gaseous fuel leak detection process which 2nd-ECU4 implements at the time of engine operation. 高圧側燃圧と燃料噴射積算量に応じて設定される漏れ閾値を示す図である。It is a figure which shows the leak threshold set according to a high side fuel pressure and fuel injection integration amount.

以下、本発明の一実施形態について、図面を参照しながら説明する。
図１は、本実施形態に係る燃料噴射システムＡの概略構成図である。この燃料噴射システムＡは、液体燃料（例えばガソリン）と気体燃料（例えば圧縮天然ガス）とを選択的に切替えて単一エンジン（図示省略）に供給するバイフューエルシステムであり、液体燃料供給系１と、気体燃料供給系２と、１ｓｔ−ＥＣＵ（Electronic Control Unit）３と、２ｎｄ−ＥＣＵ４と、燃料切替スイッチ５とから構成されている。 Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of a fuel injection system A according to the present embodiment. The fuel injection system A is a bi-fuel system that selectively switches between liquid fuel (for example, gasoline) and gaseous fuel (for example, compressed natural gas) and supplies it to a single engine (not shown). And a gaseous fuel supply system 2, a 1st-ECU (Electronic Control Unit) 3, a 2nd-ECU 4, and a fuel changeover switch 5.

液体燃料供給系１は、液体燃料タンク１１と、液体燃料供給パイプ１２と、液体燃料噴射弁１３とから構成されている。液体燃料タンク１１は、液体燃料として例えばガソリンを貯蔵する耐腐食性容器であり、液体燃料を吸い上げて液体燃料供給パイプ１２へ送出するポンプ及びレギュレータ（図示省略）などを内蔵している。  The liquid fuel supply system 1 includes a liquid fuel tank 11, a liquid fuel supply pipe 12, and a liquid fuel injection valve 13. The liquid fuel tank 11 is a corrosion-resistant container that stores, for example, gasoline as the liquid fuel, and incorporates a pump and a regulator (not shown) that sucks the liquid fuel and sends it to the liquid fuel supply pipe 12.

液体燃料供給パイプ１２は、液体燃料タンク１１から液体燃料噴射弁１３へ液体燃料を配送するための配管である。液体燃料噴射弁１３は、例えばエンジンの吸気ポートに向けて噴射口が露出するように吸気管に装着された電磁弁（例えばソレノイドバルブ等）であり、２ｎｄ−ＥＣＵ４から入力される液体燃料噴射弁駆動信号に応じて所定量の液体燃料を噴射する。  The liquid fuel supply pipe 12 is a pipe for delivering liquid fuel from the liquid fuel tank 11 to the liquid fuel injection valve 13. The liquid fuel injection valve 13 is, for example, an electromagnetic valve (for example, a solenoid valve) attached to the intake pipe so that the injection port is exposed toward the intake port of the engine, and the liquid fuel injection valve input from the 2nd-ECU 4 A predetermined amount of liquid fuel is injected according to the drive signal.

気体燃料供給系２は、気体燃料タンク２１と、高圧ガス供給パイプ２２と、第１遮断弁２３と、第２遮断弁２４と、レギュレータ２５と、低圧ガス供給パイプ２６と、気体燃料噴射弁２７と、高圧側燃圧センサ２８と、低圧側燃圧センサ２９と、低圧側燃温センサ３０とから構成されている。  The gaseous fuel supply system 2 includes a gaseous fuel tank 21, a high pressure gas supply pipe 22, a first cutoff valve 23, a second cutoff valve 24, a regulator 25, a low pressure gas supply pipe 26, and a gaseous fuel injection valve 27. And a high pressure side fuel pressure sensor 28, a low pressure side fuel pressure sensor 29, and a low pressure side fuel temperature sensor 30.

気体燃料タンク２１は、気体燃料として例えば圧縮天然ガス（ＣＮＧ）が充填された高耐圧容器である。高圧ガス供給パイプ２２は、気体燃料タンク２１からレギュレータ２５へ高圧の気体燃料を配送するための高耐圧配管である。第１遮断弁２３は、高圧ガス供給パイプ２２の途中（気体燃料タンク２１に近い位置）に介挿された電磁弁であり、２ｎｄ−ＥＣＵ４から入力される第１遮断弁駆動信号に応じて開弁或いは閉弁する。  The gaseous fuel tank 21 is a high pressure vessel filled with, for example, compressed natural gas (CNG) as gaseous fuel. The high-pressure gas supply pipe 22 is a high-pressure pipe for delivering high-pressure gaseous fuel from the gaseous fuel tank 21 to the regulator 25. The first shut-off valve 23 is an electromagnetic valve inserted in the middle of the high-pressure gas supply pipe 22 (position close to the gaseous fuel tank 21), and opens according to the first shut-off valve drive signal input from the 2nd-ECU 4. Valve or close.

第２遮断弁２４は、高圧ガス供給パイプ２２の途中（レギュレータ２５に近い位置）に介挿された電磁弁であり、２ｎｄ−ＥＣＵ４から入力される第２遮断弁駆動信号に応じて開弁或いは閉弁する。なお、この第２遮断弁２４は、レギュレータ２５に対して一体的に組み込まれている場合もある。レギュレータ２５は、第２遮断弁２４の下流側に配置された減圧弁であり、第１遮断弁２３及び第２遮断弁２４の開弁時に気体燃料タンク２１から供給される高圧の気体燃料を所望の圧力まで減圧して低圧ガス供給パイプ２６へ送出する。  The second shut-off valve 24 is an electromagnetic valve inserted in the middle of the high-pressure gas supply pipe 22 (position close to the regulator 25), and is opened or closed according to the second shut-off valve drive signal input from the 2nd-ECU 4. Close the valve. The second shut-off valve 24 may be integrated with the regulator 25 in some cases. The regulator 25 is a pressure reducing valve arranged on the downstream side of the second cutoff valve 24, and the high-pressure gaseous fuel supplied from the gaseous fuel tank 21 when the first cutoff valve 23 and the second cutoff valve 24 are opened is desired. Then, the pressure is reduced to a low pressure gas supply pipe 26.

低圧ガス供給パイプ２６は、レギュレータ２５から気体燃料噴射弁２７へ低圧の気体燃料を配送するための低耐圧配管である。気体燃料噴射弁２７は、例えばエンジンの吸気ポートに向けて噴射口が露出するように吸気管に装着された電磁弁であり、２ｎｄ−ＥＣＵ４から入力される気体燃料噴射弁駆動信号に応じて所定量の気体燃料を噴射する。このように、高圧ガス供給パイプ２２及び低圧ガス供給パイプ２６は、気体燃料タンク２１から気体燃料噴射弁２７に至る気体燃料供給経路に相当する。  The low-pressure gas supply pipe 26 is a low-pressure pipe for delivering low-pressure gaseous fuel from the regulator 25 to the gaseous fuel injection valve 27. The gaseous fuel injection valve 27 is an electromagnetic valve mounted on the intake pipe so that, for example, the injection port is exposed toward the intake port of the engine. The gaseous fuel injection valve 27 is provided in accordance with a gaseous fuel injection valve drive signal input from the 2nd-ECU 4. A fixed amount of gaseous fuel is injected. Thus, the high-pressure gas supply pipe 22 and the low-pressure gas supply pipe 26 correspond to a gaseous fuel supply path from the gaseous fuel tank 21 to the gaseous fuel injection valve 27.

高圧側燃圧センサ２８は、レギュレータ２５より高圧側（上流側）、つまり高圧ガス供給パイプ２２の内部圧力（高圧側燃圧）を検出し、その検出結果を示す高圧側燃圧信号を２ｎｄ−ＥＣＵ４へ出力する。低圧側燃圧センサ２９は、レギュレータ２５よる低圧側（下流側）、つまり低圧ガス供給パイプ２６の内部圧力（低圧側燃圧）を検出し、その検出結果を示す低圧側燃圧信号を２ｎｄ−ＥＣＵ４へ出力する。低圧側燃温センサ３０は、低圧ガス供給パイプ２６の内部温度（低圧側燃温）を検出し、その検出結果を示す低圧側燃温信号を２ｎｄ−ＥＣＵ４へ出力する。  The high-pressure side fuel pressure sensor 28 detects the high-pressure side (upstream side) of the regulator 25, that is, the internal pressure (high-pressure side fuel pressure) of the high-pressure gas supply pipe 22, and outputs a high-pressure side fuel pressure signal indicating the detection result to the 2nd-ECU 4. To do. The low-pressure side fuel pressure sensor 29 detects the low-pressure side (downstream side) of the regulator 25, that is, the internal pressure of the low-pressure gas supply pipe 26 (low-pressure side fuel pressure), and outputs a low-pressure side fuel pressure signal indicating the detection result to the 2nd-ECU 4 To do. The low-pressure side fuel temperature sensor 30 detects the internal temperature (low-pressure side fuel temperature) of the low-pressure gas supply pipe 26 and outputs a low-pressure side fuel temperature signal indicating the detection result to the 2nd-ECU 4.

１ｓｔ−ＥＣＵ３は、エンジン状態を検出する各種センサ（図示省略）から入力される各種センサ信号に基づいて液体燃料噴射量を算出し、その算出結果に応じたパルス幅を有するパルス信号（液体燃料噴射弁駆動信号）を、燃料噴射タイミングに合わせて２ｎｄ−ＥＣＵ４へ出力する。なお、１ｓｔ−ＥＣＵ３に入力される各種センサ信号には、少なくとも、クランク軸が一定角度回転する時間を１周期とするクランクパルス信号、ピストンが上死点（ＴＤＣ）に到達する時間を１周期とするＴＤＣパルス信号、吸気温度を示す吸気温信号、吸気圧力を示す吸気圧信号、冷却水温を示す冷却水温信号などが含まれている。  The 1st-ECU 3 calculates a liquid fuel injection amount based on various sensor signals input from various sensors (not shown) for detecting the engine state, and a pulse signal (liquid fuel injection) having a pulse width corresponding to the calculation result. Valve drive signal) is output to the 2nd-ECU 4 in accordance with the fuel injection timing. The various sensor signals input to the 1st-ECU 3 include at least a crank pulse signal that takes a time for the crankshaft to rotate at a constant angle as one cycle, and a time for the piston to reach top dead center (TDC) as one cycle. A TDC pulse signal, an intake air temperature signal indicating the intake air temperature, an intake air pressure signal indicating the intake air pressure, a cooling water temperature signal indicating the cooling water temperature, and the like.

１ｓｔ−ＥＣＵ３は、クランクパルス信号からエンジン回転数を算出し、エンジン回転数及び吸気温度（冷却水温でも良い）を基に液体燃料噴射量を算出し、さらに液体燃料噴射量から燃料噴射タイミング（液体燃料を噴射すべきクランク軸角度）を算出する。なお、これら液体燃料噴射量及び燃料噴射タイミングの算出手法は従来と同様であるので、詳細な説明は省略する。  The 1st-ECU 3 calculates the engine speed from the crank pulse signal, calculates the liquid fuel injection amount based on the engine speed and the intake air temperature (or the cooling water temperature), and further calculates the fuel injection timing (the liquid injection timing from the liquid fuel injection amount). The crankshaft angle at which fuel is to be injected is calculated. Note that the calculation method of the liquid fuel injection amount and the fuel injection timing is the same as the conventional method, and detailed description thereof is omitted.

２ｎｄ−ＥＣＵ４は、高圧側燃圧センサ２８から入力される高圧側燃圧信号と、低圧側燃圧センサ２９から入力される低圧側燃圧信号と、低圧側燃温センサ３０から入力される低圧側燃温信号と、１ｓｔ−ＥＣＵ３から入力される液体燃料噴射弁駆動信号と、燃料切替スイッチ５から入力される燃料切替信号とに基づいて、液体燃料噴射弁１３、気体燃料噴射弁２７、第１遮断弁２３及び第２遮断弁２４を制御する。  The 2nd-ECU 4 includes a high pressure side fuel pressure signal input from the high pressure side fuel pressure sensor 28, a low pressure side fuel pressure signal input from the low pressure side fuel pressure sensor 29, and a low pressure side fuel temperature signal input from the low pressure side fuel temperature sensor 30. On the basis of the liquid fuel injection valve driving signal input from the 1st-ECU 3 and the fuel switching signal input from the fuel change-over switch 5, the liquid fuel injection valve 13, the gaseous fuel injection valve 27, and the first cutoff valve 23 And the second shut-off valve 24 is controlled.

具体的には、２ｎｄ−ＥＣＵ４は、燃料切替スイッチ５から入力される燃料切替信号を基にユーザによる液体燃料への切替操作を検知した場合、液体燃料噴射モードとなり、１ｓｔ−ＥＣＵ３から入力される液体燃料噴射弁駆動信号をそのまま液体燃料噴射弁１３へ出力する。  Specifically, the 2nd-ECU 4 enters the liquid fuel injection mode when it detects a switching operation to the liquid fuel by the user based on the fuel switching signal input from the fuel switch 5 and is input from the 1st-ECU 3. The liquid fuel injection valve drive signal is output to the liquid fuel injection valve 13 as it is.

また、２ｎｄ−ＥＣＵ４は、燃料切替スイッチ５から入力される燃料切替信号を基にユーザによる気体燃料への切替操作を検知した場合、気体燃料噴射モードとなり、第１遮断弁２３及び第２遮断弁２４を開弁させて気体燃料タンク２１から気体燃料噴射弁２７への気体燃料の供給を開始すると共に、１ｓｔ−ＥＣＵ３から入力される液体燃料噴射弁駆動信号のパルス幅を低圧側燃圧及び低圧側燃温に基づいて補正することにより、気体燃料に適したパルス幅を有するパルス信号（気体燃料噴射弁駆動信号）を生成して気体燃料噴射弁２７へ出力する。  Further, when the 2nd-ECU 4 detects a switching operation to the gaseous fuel by the user based on the fuel switching signal input from the fuel switching switch 5, the 2nd-ECU 4 enters the gaseous fuel injection mode, and the first cutoff valve 23 and the second cutoff valve 24 is opened to start supply of gaseous fuel from the gaseous fuel tank 21 to the gaseous fuel injection valve 27, and the pulse width of the liquid fuel injection valve drive signal input from the 1st-ECU 3 is set to the low pressure side fuel pressure and the low pressure side. By correcting based on the fuel temperature, a pulse signal (gaseous fuel injection valve drive signal) having a pulse width suitable for the gaseous fuel is generated and output to the gaseous fuel injection valve 27.

さらに、この２ｎｄ−ＥＣＵ４は、レギュレータ２５より高圧側の気体燃料漏れを検出する気体燃料漏れ検出装置としての役割を担っている。具体的には、２ｎｄ−ＥＣＵ４は、気体燃料漏れを検出するための機能として、燃料噴射積算量算出部４ａ（燃料噴射積算量算出手段）、漏れ閾値設定部４ｂ（漏れ閾値設定手段）、圧力変化量算出部４ｃ（圧力変化量算出手段）及び燃料漏れ判定部４ｄ（燃料漏れ判定手段）を備えている。  Further, the 2nd-ECU 4 plays a role as a gaseous fuel leakage detection device that detects gaseous fuel leakage on the higher pressure side than the regulator 25. Specifically, the 2nd-ECU 4 functions as a function for detecting gaseous fuel leakage as a fuel injection integrated amount calculation unit 4a (fuel injection integrated amount calculation unit), a leak threshold setting unit 4b (leakage threshold setting unit), a pressure A change amount calculation unit 4c (pressure change amount calculation unit) and a fuel leak determination unit 4d (fuel leak determination unit) are provided.

燃料噴射積算量算出部４ａは、気体燃料噴射弁２７から噴射された気体燃料の積算量である燃料噴射積算量を算出する。漏れ閾値設定部４ｂは、燃料噴射積算量及びレギュレータ２５より高圧側の気体燃料圧力（高圧側燃圧）に基づいて気体燃料漏れの有無を判定するための漏れ閾値を設定する。圧力変化量算出部４ｃは、レギュレータ２５より高圧側の気体燃料の圧力変化量を算出する。燃料漏れ判定部４ｄは、圧力変化量が漏れ閾値より大きい場合に気体燃料漏れと判定する。なお、これら気体燃料漏れを検出するための機能は、２ｎｄ−ＥＣＵ４に内蔵されたマイクロプロセッサが所定のプログラムを実行することで実現されるソフトウェア的な機能である。  The fuel injection integrated amount calculation unit 4 a calculates a fuel injection integrated amount that is an integrated amount of the gaseous fuel injected from the gaseous fuel injection valve 27. The leakage threshold setting unit 4b sets a leakage threshold for determining the presence or absence of gaseous fuel leakage based on the fuel injection integration amount and the gaseous fuel pressure on the higher pressure side than the regulator 25 (high pressure side fuel pressure). The pressure change amount calculation unit 4 c calculates the pressure change amount of the gaseous fuel on the high pressure side from the regulator 25. The fuel leak determination unit 4d determines that the fuel leak is gaseous when the pressure change amount is larger than the leak threshold. The function for detecting the gaseous fuel leakage is a software function realized by a microprocessor built in the 2nd-ECU 4 executing a predetermined program.

燃料切替スイッチ５は、ユーザの手動操作によって燃料の切替えを可能とするスイッチであり、そのスイッチの状態、つまりユーザによってエンジンで使用する燃料が液体燃料に切替えられたのか、或いは気体燃料に切替えられたのかを示す燃料切替信号を２ｎｄ−ＥＣＵ４に出力する。  The fuel change-over switch 5 is a switch that enables the fuel to be changed by a user's manual operation. The state of the switch, that is, whether the fuel used in the engine has been changed to liquid fuel or changed to gaseous fuel. A fuel switching signal indicating whether or not the vehicle has been switched is output to the 2nd-ECU 4.

以下では、上記のように構成された燃料噴射システムＡの動作、特に本実施形態の特徴である２ｎｄ−ＥＣＵ４による気体燃料漏れ検出動作について詳細に説明する。
図２は、２ｎｄ−ＥＣＵ４がエンジン運転時に実施する気体燃料漏れ検出処理を表すフローチャートである。なお、２ｎｄ−ＥＣＵ４は、エンジン運転中において図２に示す気体燃料漏れ検出処理を一定周期で繰り返し実施するものである。 Below, operation | movement of the fuel-injection system A comprised as mentioned above, especially the gaseous fuel leak detection operation | movement by 2nd-ECU4 which is the characteristics of this embodiment is demonstrated in detail.
FIG. 2 is a flowchart showing a gas fuel leakage detection process performed by the 2nd-ECU 4 during engine operation. Note that the 2nd-ECU 4 repeatedly performs the gaseous fuel leak detection process shown in FIG. 2 at a constant period during engine operation.

この図２に示すように、２ｎｄ−ＥＣＵ４は、気体燃料漏れ検出処理を開始すると、まず、現在の燃料噴射モードが気体燃料噴射モードか否かを判定し（ステップＳ１）、「Ｙｅｓ」の場合にはステップＳ２の処理へ移行する一方、「Ｎｏ」の場合にはステップＳ４の処理に移行する。  As shown in FIG. 2, when the 2nd-ECU 4 starts the gaseous fuel leakage detection process, it first determines whether or not the current fuel injection mode is the gaseous fuel injection mode (step S1). In step S2, the process proceeds to step S2, whereas in the case of “No”, the process proceeds to step S4.

上記ステップＳ１にて「Ｙｅｓ」の場合、つまり気体燃料噴射モードであって第１遮断弁２３及び第２遮断弁２４が開弁している場合、２ｎｄ−ＥＣＵ４（燃料噴射積算量算出部４ａ）は、気体燃料噴射弁２７から噴射された気体燃料の積算量である燃料噴射積算量を算出する（ステップＳ２）。具体的には、２ｎｄ−ＥＣＵ４は、低圧側燃圧センサ２９から入力される低圧側燃圧信号と、低圧側燃温センサ３０から入力される低圧側燃温信号とを基に低圧側燃圧及び低圧側燃温の今回値（現在値）を把握し、これら低圧側燃圧及び低圧側燃温の今回値と、気体燃料噴射弁２７による気体燃料噴射時間に基づいて燃料噴射積算量を算出する。  In the case of “Yes” in step S1, that is, in the gaseous fuel injection mode and when the first cutoff valve 23 and the second cutoff valve 24 are open, the 2nd-ECU 4 (fuel injection integrated amount calculation unit 4a). Calculates a fuel injection integrated amount that is an integrated amount of gaseous fuel injected from the gaseous fuel injection valve 27 (step S2). Specifically, the 2nd-ECU 4 determines the low pressure side fuel pressure and the low pressure side based on the low pressure side fuel pressure signal input from the low pressure side fuel pressure sensor 29 and the low pressure side fuel temperature signal input from the low pressure side fuel temperature sensor 30. The current value (current value) of the fuel temperature is grasped, and the fuel injection integrated amount is calculated based on the current values of the low-pressure side fuel pressure and the low-pressure side fuel temperature and the gaseous fuel injection time by the gaseous fuel injection valve 27.

続いて、２ｎｄ−ＥＣＵ４（漏れ閾値設定部４ｂ）は、高圧側燃圧センサ２８から入力される高圧側燃圧信号を基に高圧側燃圧の今回値を把握し、この高圧側燃圧の今回値と上記ステップＳ２にて算出した燃料噴射積算量に基づいて気体燃料漏れの有無を判定するための漏れ閾値を設定する（ステップＳ３）。具体的には、２ｎｄ−ＥＣＵ４には、予め実験等により求められた、高圧側燃圧と燃料噴射積算量と漏れ閾値との対応関係を示す３次元マップデータが設定されており、２ｎｄ−ＥＣＵ４は、高圧側燃圧の今回値と今回算出した燃料噴射積算量に対応する漏れ閾値を上記の３次元マップデータから取得する。  Subsequently, the 2nd-ECU 4 (leakage threshold setting unit 4b) grasps the current value of the high-pressure side fuel pressure based on the high-pressure side fuel pressure signal input from the high-pressure side fuel pressure sensor 28, and the present value of the high-pressure side fuel pressure and the above-described value. A leakage threshold for determining the presence or absence of gaseous fuel leakage is set based on the integrated fuel injection amount calculated in step S2 (step S3). Specifically, the 2nd-ECU 4 is set with three-dimensional map data indicating a correspondence relationship between the high-pressure side fuel pressure, the fuel injection integrated amount, and the leak threshold, which is obtained in advance through experiments or the like. Then, the current value of the high-pressure side fuel pressure and the leak threshold corresponding to the fuel injection integrated amount calculated this time are acquired from the above three-dimensional map data.

図３は、高圧側燃圧と燃料噴射積算量に応じて設定される漏れ閾値を示す図である。図３に示すように、第１遮断弁２３及び第２遮断弁２４の開弁時（気体燃料噴射モード時）には、燃料噴射積算量が時間の経過に伴って増加するので、この燃料噴射積算量、つまり気体燃料噴射弁２７からの気体燃料噴射による圧力変化要因を考慮して気体燃料漏れの有無を判定するための漏れ閾値を設定することにより、気体燃料の漏れ検出精度を向上させることができる。なお、本実施形態により設定した漏れ閾値は、従来の漏れ閾値より燃料噴射積算量分だけ大きくなる。  FIG. 3 is a diagram showing a leak threshold set in accordance with the high-pressure side fuel pressure and the integrated fuel injection amount. As shown in FIG. 3, when the first shut-off valve 23 and the second shut-off valve 24 are opened (in the gaseous fuel injection mode), the fuel injection integrated amount increases with time. To improve the accuracy of gas fuel leak detection by setting a leak threshold for determining the presence or absence of gas fuel leakage in consideration of the integrated amount, that is, the pressure change factor due to gas fuel injection from the gas fuel injection valve 27 Can do. Note that the leak threshold set by the present embodiment is larger than the conventional leak threshold by the fuel injection integrated amount.

一方、上記ステップＳ１にて「Ｎｏ」の場合、つまり液体燃料噴射モードであって第１遮断弁２３及び第２遮断弁２４が閉弁している場合、２ｎｄ−ＥＣＵ４（漏れ閾値設定部４ｂ）は、予め定められた遮断弁閉弁時閾値を漏れ閾値として設定する（ステップＳ４）。このように、第１遮断弁２３及び第２遮断弁２４の閉弁時（液体燃料噴射モード時）には、気体燃料噴射弁２７からの気体燃料噴射が実施されないので、気体燃料噴射による圧力変化要因を考慮して漏れ閾値を設定する必要はなく、漏れ閾値は燃料噴射積算量に拘らず固定値（遮断弁閉弁時閾値）で良い。  On the other hand, in the case of “No” in step S1, that is, in the liquid fuel injection mode and when the first cutoff valve 23 and the second cutoff valve 24 are closed, the 2nd-ECU 4 (leakage threshold setting unit 4b). Sets a predetermined shut-off valve closing threshold as a leak threshold (step S4). Thus, when the first shut-off valve 23 and the second shut-off valve 24 are closed (in the liquid fuel injection mode), the gaseous fuel injection from the gaseous fuel injection valve 27 is not performed, so that the pressure change due to the gaseous fuel injection It is not necessary to set the leak threshold value in consideration of the factors, and the leak threshold value may be a fixed value (threshold value when the shutoff valve is closed) regardless of the fuel injection integrated amount.

続いて、２ｎｄ−ＥＣＵ４（圧力変化量算出部４ｃ）は、上記ステップＳ３或いはステップＳ４の終了後、レギュレータ２５より高圧側の気体燃料の圧力変化量を算出する（ステップＳ５）。具体的には、２ｎｄ−ＥＣＵ４は、高圧側燃圧の今回値（今回の気体燃料漏れ検出処理の実行時に把握した高圧側燃圧）と前回値（前回の気体燃料漏れ検出処理の実行時に把握した高圧側燃圧）との差分を圧力変化量として算出する。  Subsequently, the 2nd-ECU 4 (pressure change amount calculation unit 4c) calculates the pressure change amount of the high-pressure side gaseous fuel from the regulator 25 after step S3 or step S4 ends (step S5). Specifically, the 2nd-ECU 4 determines the current value of the high-pressure side fuel pressure (high-pressure side fuel pressure grasped at the time of execution of the current gaseous fuel leak detection process) and the previous value (high-pressure side fuel pressure grasped at the time of execution of the previous gaseous fuel leak detection process). The difference from the side fuel pressure is calculated as a pressure change amount.

そして、２ｎｄ−ＥＣＵ４（燃料漏れ判定部４ｄ）は、上記ステップＳ５にて算出した圧力変化量が、上記ステップＳ３或いはＳ４にて設定した漏れ閾値より大きいか否かを判定し（ステップＳ６）、「Ｎｏ」の場合にはそのまま今回の気体燃料漏れ検出処理を終了する一方、「Ｙｅｓ」の場合にはレギュレータ２５より高圧側に気体燃料漏れが発生したと判定して今回の気体燃料漏れ検出処理を終了する（ステップＳ７）。  Then, the 2nd-ECU 4 (fuel leakage determination unit 4d) determines whether or not the pressure change amount calculated in step S5 is greater than the leakage threshold set in step S3 or S4 (step S6). In the case of “No”, the current gaseous fuel leakage detection process is finished as it is, whereas in the case of “Yes”, it is determined that the gaseous fuel leakage has occurred on the high pressure side from the regulator 25 and the present gaseous fuel leakage detection process is completed. Is finished (step S7).

以上のように、本実施形態によれば、気体燃料噴射弁２７から噴射された気体燃料の積算量である燃料噴射積算量、つまり気体燃料噴射弁２７からの気体燃料噴射による圧力変化要因を考慮して気体燃料漏れの有無を判定するための漏れ閾値を設定するので、気体燃料の漏れ検出精度を向上させることが可能となる。  As described above, according to the present embodiment, the fuel injection integrated amount that is the integrated amount of the gaseous fuel injected from the gaseous fuel injection valve 27, that is, the pressure change factor due to the gaseous fuel injection from the gaseous fuel injection valve 27 is taken into consideration. Since the leakage threshold value for determining the presence or absence of gaseous fuel leakage is set, it is possible to improve the accuracy of gaseous fuel leakage detection.

なお、本発明は上記実施形態に限定されず、以下のような変形例が挙げられる。
（１）上記実施形態では、高圧側燃圧と燃料噴射積算量と漏れ閾値との対応関係を示す３次元マップデータを用いて、第１遮断弁２３及び第２遮断弁２４の開弁時の漏れ閾値を設定する場合を例示したが、例えば高圧側燃圧と燃料噴射積算量を変数とする演算式を用いて漏れ閾値を算出するようにしても良い。 In addition, this invention is not limited to the said embodiment, The following modifications are mentioned.
(1) In the above embodiment, the leakage at the time of opening the first cutoff valve 23 and the second cutoff valve 24 using the three-dimensional map data indicating the correspondence relationship between the high-pressure side fuel pressure, the fuel injection integrated amount, and the leakage threshold. Although the case where the threshold value is set is illustrated, for example, the leak threshold value may be calculated using an arithmetic expression having the high-pressure side fuel pressure and the integrated fuel injection amount as variables.

（２）上記実施形態では、燃料噴射システムＡとしてバイフューエルシステムを例示して説明したが、気体燃料のみを単一エンジンに供給するモノフューエルシステムにおける気体燃料漏れの検出にも本発明を適用することができる。 (2) In the above embodiment, the bi-fuel system is exemplified as the fuel injection system A. However, the present invention is also applied to detection of gaseous fuel leakage in a mono-fuel system that supplies only gaseous fuel to a single engine. be able to.

Ａ…燃料噴射システム、１…液体燃料供給系、２…気体燃料供給系、３…１ｓｔ−ＥＣＵ、４…２ｎｄ−ＥＣＵ（気体燃料漏れ検出装置）、５…燃料切替スイッチ、２１…気体燃料タンク、２３…第１遮断弁、２４…第２遮断弁、２５…レギュレータ（減圧弁）、２７…気体燃料噴射弁、４ａ…燃料噴射積算量算出部（燃料噴射積算量算出手段）、４ｂ…漏れ閾値設定部（漏れ閾値設定手段）、４ｃ…圧力変化量算出部（圧力変化量算出手段）、４ｄ…燃料漏れ判定部（燃料漏れ判定手段）   DESCRIPTION OF SYMBOLS A ... Fuel injection system, 1 ... Liquid fuel supply system, 2 ... Gaseous fuel supply system, 3 ... 1st-ECU, 4 ... 2nd-ECU (gaseous fuel leak detection device), 5 ... Fuel changeover switch, 21 ... Gaseous fuel tank , 23 ... 1st shut-off valve, 24 ... 2nd shut-off valve, 25 ... Regulator (pressure reducing valve), 27 ... Gaseous fuel injection valve, 4a ... Fuel injection integrated amount calculating part (fuel injection integrated amount calculating means), 4b ... Leakage Threshold setting unit (leakage threshold setting unit), 4c ... pressure change amount calculation unit (pressure change amount calculation unit), 4d ... fuel leak determination unit (fuel leak determination unit)

Claims (3)

気体燃料タンクから気体燃料噴射弁に至る気体燃料供給経路に介挿された減圧弁より高圧側の気体燃料漏れを検出する気体燃料漏れ検出装置であって、
前記気体燃料噴射弁から噴射された気体燃料の積算量である燃料噴射積算量を算出する燃料噴射積算量算出手段と、
前記燃料噴射積算量及び前記減圧弁より高圧側の気体燃料圧力に基づいて前記気体燃料漏れの有無を判定するための漏れ閾値を設定する漏れ閾値設定手段と、
前記減圧弁より高圧側の気体燃料の圧力変化量を算出する圧力変化量算出手段と、
前記圧力変化量が前記漏れ閾値より大きい場合に前記気体燃料漏れと判定する燃料漏れ判定手段と、
を備えることを特徴とする気体燃料漏れ検出装置。 A gaseous fuel leakage detection device for detecting gaseous fuel leakage on the high pressure side from a pressure reducing valve inserted in a gaseous fuel supply path from the gaseous fuel tank to the gaseous fuel injection valve,
A fuel injection integrated amount calculating means for calculating a fuel injection integrated amount that is an integrated amount of gaseous fuel injected from the gaseous fuel injection valve;
A leakage threshold setting means for setting a leakage threshold for determining the presence or absence of the gaseous fuel leakage based on the fuel injection integrated amount and the gaseous fuel pressure on the higher pressure side than the pressure reducing valve;
Pressure change amount calculating means for calculating the pressure change amount of the gaseous fuel on the high pressure side from the pressure reducing valve;
Fuel leakage determination means for determining that the gaseous fuel leakage occurs when the pressure change amount is greater than the leakage threshold;
A gaseous fuel leak detection device comprising: 前記燃料噴射積算量算出手段は、前記気体燃料噴射弁による気体燃料噴射時間と、前記減圧弁より低圧側の気体燃料の圧力及び温度に基づいて前記燃料噴射積算量を算出することを特徴とする請求項１に記載の気体燃料漏れ検出装置。   The fuel injection integrated amount calculating means calculates the fuel injection integrated amount based on a gaseous fuel injection time by the gaseous fuel injection valve and a pressure and temperature of gaseous fuel on a lower pressure side than the pressure reducing valve. The gaseous fuel leak detection apparatus according to claim 1. 前記漏れ閾値設定手段は、前記減圧弁より高圧側に介挿された遮断弁の開弁時には、前記燃料噴射積算量及び前記減圧弁より高圧側の気体燃料圧力に基づいて前記漏れ閾値を設定する一方、前記遮断弁の閉弁時には、予め定められた遮断弁閉弁時閾値を前記漏れ閾値として設定することを特徴とする請求項１または２に記載の気体燃料漏れ検出装置。   The leak threshold setting means sets the leak threshold based on the integrated fuel injection amount and the gaseous fuel pressure on the high pressure side from the pressure reducing valve when the shut-off valve inserted on the high pressure side from the pressure reducing valve is opened. On the other hand, when the shut-off valve is closed, a predetermined shut-off valve closing threshold is set as the leak threshold. The gaseous fuel leak detection device according to claim 1 or 2, wherein
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