(19)
(11)EP 2 143 930 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
02.05.2018 Bulletin 2018/18

(21)Application number: 08862107.3

(22)Date of filing:  20.11.2008
(51)International Patent Classification (IPC): 
F02D 41/00(2006.01)
F02B 43/00(2006.01)
F02D 19/02(2006.01)
F02M 21/02(2006.01)
F02M 21/04(2006.01)
F02D 23/00(2006.01)
(86)International application number:
PCT/JP2008/071590
(87)International publication number:
WO 2009/078258 (25.06.2009 Gazette  2009/26)

(54)

CONTROL METHOD OF GAS ENGINE SYSTEM AND THAT SYSTEM

STEUERVERFAHREN FÜR EIN GASMOTORENSYSTEM UND BESAGTES SYSTEM

PROCÉDÉ DE COMMANDE DE SYSTÈME DE MOTEUR À GAZ ET CE SYSTÈME


(84)Designated Contracting States:
AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MT NL NO PL PT RO SE SI SK TR

(30)Priority: 14.12.2007 JP 2007323877

(43)Date of publication of application:
13.01.2010 Bulletin 2010/02

(73)Proprietor: Mitsubishi Heavy Industries, Ltd.
Tokyo 108-8215 (JP)

(72)Inventors:
  • NISHIO, Hideki
    Yokohama-shi Kanagawa 236-8515 (JP)
  • SUZUKI, Hajime
    Yokohama-shi Kanagawa 236-8515 (JP)
  • SHIMIZU, Yuuichi
    Yokohama-shi Kanagawa 236-8515 (JP)

(74)Representative: Hoffmann Eitle 
Patent- und Rechtsanwälte PartmbB Arabellastraße 30
81925 München
81925 München (DE)


(56)References cited: : 
EP-A2- 0 812 980
JP-A- 2001 132 550
JP-A- 2006 249 954
JP-A- 2001 132 550
JP-A- 2005 256 674
JP-A- 2006 249 954
  
      
    Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


    Description

    BACKGROUND OF THE INVENTION


    Technical Field



    [0001] The present application relates to a method to control a gas engine and a gas engine system thereof, the engine being provided with: either a turbocharger or a supercharger through which air is supplied to the engine [henceforth in this application, whenever the word 'turbocharger' appears, it could equally well be replaced by 'supercharger']; a first gas control valve that controls flow-rates of fuel-gas to be supplied to each cylinder of the engine; whereby, the fuel-gas that is regulated by the first gas valve and the air that is supplied through the turbocharger are mixed so as to form a prescribed air-fuel ratio; and, the engine burns the supplied fuel-gas under conditions of the prescribed air-fuel ratio; specifically, the engine can be operated based on the air-fuel-ratio control with high precision, even in the case when a low calorific fuel gas that is prone to vary in calorific value is used.

    Description of the Related Art



    [0002] A conventional small gas engine, such as an engine with a cylinder bore of approximately 200 mm or less, usually adopts a fuel-gas mixing system in which fuel-gas and air are mixed upstream of air-inflow before a turbocharger, while the fuel-gas air mixture is supplied to the main combustion chambers i.e. cylinders, through the turbocharger (i.e. , a compressor thereof) and an air cooler.
    ]

    [0003] On the other hand, in conventional larger gas engines, fuel-gas is supplied into each cylinder, through a charging air inlet branch arm pipe just before each cylinder and through a gas supply control valve for each cylinder, as fuel-gas supply is required to be uniform all over the cylinders in amount as well as in gas concentration distribution, as a rule. In this manner, not only the air fuel ratios and the fuel quantities over the cylinders can be equalized but also the fuel-gas charging is streamlined; further, since fuel-gas and air are mixed just in front of each cylinder, the length of potentially flammable gas-air-mixture flow that is formed upstream of each cylinder can be shortened so as to enhance engine operational safety against explosion risks.

    [0004] Hereby, it is noted that the above-mentioned gas supply control valve for each cylinder is also called a first gas valve in this specification; and, the first gas valve is often termed a gas admission valve in the larger gas engine field, because it is the valve which is provided at each cylinder of the gas engine in principle; on the other hand, as described later in this specification, a term, namely, a second gas valve, is introduced for a fuel-gas supply control valve that supplies fuel-gas to suction air. Further, a fuel-gas supply line that is connected to the first gas valve is called a first gas line in this specification; in the same way, a second gas line is defined in response to the second gas valve.

    [0005] A patent reference 1 (JP2001-132550) discloses a technology in which fuel-gas supply methods of the mentioned smaller and larger gas-engines are combined. In a gas engine according to the reference 1, fuel-gas pressurized by means of a gas compressor is supplied to a cylinder inlet of a charging air passage or a cylinder, whereas fuel-gas that is not compressed by the compressor is supplied to the upstream side of air-inflow line before a turbocharger, from a gas inflow line (a gas source) before the gas compressor; further, the fuel-gas supply can be switched from the line toward the cylinder inlet, to the line toward the upstream side of the air-inflow line before the turbocharger and vice versa.

    [0006] In the larger gas engine in which fuel-gas is supplied to a cylinder inlet of a charging air passage or a cylinder, it is required that the fuel-gas pressure at the inlet of the cylinder be higher than the supercharged air pressure. As a result, in the case when a low calorific fuel gas i.e. a gas of a low calorific value such as coal mine methane-gas , a gas compressor of a large capacity is needed so as to compress a fuel-gas of low pressure (substantially less than an ambient pressure) and large flow rates.

    [0007] On the other hand, in a gas engine with a fuel supply system in which fuel-gas is supplied to the upstream side of the air in-flow line before the turbocharger, a flammable air fuel-gas mixture is compressed into a state of high temperature and a high pressure in response to a substantially adiabatic compression process through the turbocharger compressor; hence, potential risks of gas explosion are involved so long as the mentioned fuel supply system is employed.

    [0008] Against the above backdrop, a patent reference 2 (JP2006-244954) discloses a technology as to a gas supply device and an operation method thereof for the aforementioned larger gas engines. In the technology according to the reference 2, the fuel-gas device comprises:

    a second fuel-gas supply line, i.e. a second gas line, through which a part of fuel-gas is mixed with air that is inducted by the turbocharger compressor;

    a first fuel-gas supply line, i.e. a first gas line, through which the remaining part or the whole part of fuel-gas is mixed with air or air-fuel mixture at a gas supply branch arm pipe upstream of each cylinder;

    a gas supply control valve, i.e. a second gas valve, for suction air, the valve regulating fuel-gas amount (flow rates) to be supplied through the turbocharger compressor;

    a gas supply control valve, i.e. a first gas valve, for each cylinder, the valve regulating fuel-gas amount (flow rates) to be supplied through the gas supply branch arm pipe upstream of each cylinder;

    a gas (fuel-gas) compressor that is provided at the upstream side of the first fuel-gas supply line;

    whereby the amount (flow rates) of the fuel-gas through the second gas line is controlled by means of regulating opening levels of the second gas valve for suction air, so that the concentration of the supplied fuel-gas in the air fuel-gas mixture that flows through the turbocharger compressor is kept below the lower (lean) limit of flammability as to the fuel-gas.



    [0009] According to the above disclosure, potential risks of fuel-gas explosion that may occur in the neighborhood of the turbocharger compressor outlet are completely eliminated; further, the size and capacity of the gas (fuel-gas) compressor that compresses fuel-gas and supplies the fuel-gas to the gas supply branch arm pipe upstream of each cylinder can be reduced because of reduced power consumption, even in the case when a fuel gas with a low calorific value is used.

    [0010] Hereby, it should be noted in addition that the patent reference 2 utilizes a technology originated from larger gas engines that are provided with first gas valves in principle, whereas small gas engines are not provided with a first gas valve fitted to each cylinder in general; namely, a small gas engine includes a gas valve that supplies fuel-gas toward the air suction line of the engine. The gas valve that supplies fuel-gas toward the air suction line is termed a second gas valve in this specification.

    [0011] As described above, according to the reference 2, a gas engine can be realized, whereby a sufficient amount (flow rates) of fuel-gas can be secured and in addition, the fuel-gas compressor can be of a smaller size and capacity. However, a further advanced technology has been anticipated, whereby fuel-gas amount (flow rates) through the second gas line toward the turbocharger compressor can be precisely controlled with a simple mechanism, and the further advanced technology can provide a control method to be applied even to the case where the calorific value of the fuel-gas continuously varies.
    As a further document, JP 2001-132550 A refers to a gas fuel engine. JP 2006-249954 A refers to a gas supply device, wherein one part of fuel gas is mixed with air at an inlet of a supercharger. Another document is JP 2005-256674 A.

    SUMMARY OF THE INVENTION



    [0012] In view of the above-stated conventional technology and anticipated solutions thereof, the present disclosure is aiming at providing a method to control a gas engine and a gas engine system thereof, whereby high precision control of the air fuel ratio can be achieved even in the case when a low calorific value fuel gas that is prone to vary in calorific value is used.

    [0013] In order to achieve the goals as mentioned, the
    present specification discloses a method to control a gas engine that ignites and burns fuel-gas, the gas engine comprising the features of claim 1.

    [0014] According to the present invention, a part of the fuel-gas can be supplied to the engine suction air that is inducted by the turbocharger, in the case when the fuel-gas amount to be supplied is large as is the case when the fuel-gas is of a low calorific value, or the engine output is high; thus, an air fuel ratio control with precision can be realized, while necessary fuel amount is secured. In other words, the engine is provided with a mixer that mixes fuel-gas with the induced air so that the concentration of the fuel air mixture is smaller than a prescribed concentration below a lean
    limit of flammability as to the fuel-gas; thus, the fuel-gas compressor that is arranged on the first gas line toward each cylinder can be of a smaller size and capacity; further, potential fuel-gas explosion risks in the air supply passage can be removed; what is more, since the mixer yields an air fuel mixture of a prescribed concentration, the air fuel control at the first gas valve for each cylinder can be simplified.

    [0015] Moreover, in another aspect of the present invention, an opening level of the aforementioned first gas valve as well as an output of the engine is detected during operation so that the second gas valve for suction air is opened with an estimation that the fuel gas is of a low calorific value or the higher output of the engine is being required, in the case when the first gas valve for each cylinder is fully opened and the output of the engine is increasing.

    [0016] In this way, whether or not the fuel-gas supply through the mixer is necessary can be simply and pertinently judged; thus, an air fuel control with precision can be realized.

    [0017] In another aspect of the present invention, the second gas valve for suction air is closed with an estimation that the fuel-gas served for operation has changed into a fuel of a high calorific value or the output of the engine is reduced, in the case when the
    detected output of the engine becomes low and less than a prescribed value.

    [0018] In this way, an upper threshold value as to a maximum controllable fuel-gas flow rate is predetermined; and, in the case when a fuel-gas flow rate becomes less than the upper threshold value as a prescribed value, the second gas valve for suction air is closed and the whole fuel-gas flow rate is regulated only by means of the first gas valve for each cylinder. Thus, the fuel-gas flow rate can be simply controlled with precision.

    [0019] Further, the present invention provides a gas engine according to claim 4.

    [0020] Further, it is preferable that the mentioned mixer is of a venturi type, and the air and the fuel-gas are mixed so that the prescribed air fuel ratio can be achieved.

    [0021] As described above, the present invention can provide a method to control a gas engine and a gas engine, whereby an air fuel ratio control with high precision can be achieved even in the case when a low calorific fuel gas that is prone to vary in calorific value is used.

    [0022] To be more specific, an air fuel ratio control with precision can be realized, while necessary fuel amount is secured, in a manner that a part of the fuel-gas is supplied to the engine suction air that is inducted by the turbocharger, only in the case when the fuel-gas amount to be supplied is being increased as is the case when the fuel-gas is of a low calorific value, or the engine output is high. In other words, the gas compressor can be of a smaller size and capacity by means of providing a mixer that mixes fuel-gas with suction air so that the concentration of the air fuel mixture does not exceed a prescribed concentration value below a lean limit of flammability as to the fuel-gas, as well as by means of supplying fuel-gas through the mixer in the case when a larger amount of fuel-gas is required; further, potential fuel-gas explosion risks in the air supply passage can be removed; what is more, since the mixer yields an air fuel mixture of a prescribed concentration, the air fuel control at the first gas valve for each cylinder can be simplified.

    [0023] Moreover, whether or not the fuel-gas supply through the mixer is necessary can be simply and pertinently judged in this invention, and the second gas valve for suction air is scheduled to be opened in response to the judgment in the case when the first gas valve for each cylinder is fully opened and the output of the engine is being increased; thus, an air fuel control with precision can be realized.

    [0024] In addition, in the case when the engine output is lowered below a prescribed value, then, the second gas valve for suction air is closed; this also serves to achieve simple and precise control according to this invention.

    BRIEF DESCRIPTION OF THE DRAWINGS



    [0025] The present invention will now be described in greater detail with reference to the preferred embodiments of the invention and the accompanying drawings, wherein:

    Fig. 1 shows a two-dimensional schematic drawing of a gas engine system as an embodiment according to the present invention;

    Figs. 2a, 2b, and 2c show a diagram for controlling fuel gas supply according to the embodiment; and

    Figs. 3a, 3b, and 3c show a diagram for controlling fuel gas supply according to the conventional technology.



    [0026] It is noted that a related conventional technology is depicted not in the first place but in Figs. 3a, 3b, and 3c, as the conventional technology can be simply explained in contrast to the presented embodiment, i.e., the preceding figures.

    DETAILED DESCRIPTION OF THE INVENTION



    [0027] Hereafter, the present invention will be described in detail with reference to the embodiments shown in the figures. However, the dimensions, materials, shape, the relative placement and so on of a component described in these embodiments shall not be construed as limiting the scope of the invention thereto, unless especially specific mention is made.

    [0028] As described above, Fig. 1 shows a two-dimensional schematic drawing of a gas engine system as an embodiment according to the present invention; Fig. 2 shows a diagram for controlling fuel gas supply according to the embodiment; and Fig. 3 shows a diagram for controlling fuel gas supply according to the conventional technology.

    [0029] Hereupon, an explanation is given about a gas engine configuration, for an example, with a supercharged gas engine for driving a generator the engine which comprises a pre-chamber for ignition; however, the applications of the present invention are not confined to this example. In practical terms, the gas engine may be one without a pre-chamber. As depicted in Fig. 1, a generator 13 is a driven load as a preferable example; as a matter of course, a driven load is not limited to a generator.

    [0030] With reference to Fig. 1, the two-dimensional schematic drawing of a gas engine system will be explained. In the figure,
    the component with Numeral 1 is an engine (a gas engine);
    Numeral 4 shows a cylinder cover for each cylinder of the engine 1;
    Numeral 13 shows a generator driven directly by the engine 1;
    Numeral 14 shows a flywheel;
    Numeral 7 shows a shaft by which an exhaust gas turbine 7a drives a compressor 7b;
    Numeral 3 shows a charging air inlet branch arm pipe that is connected to the charge inlet of each cylinder cover 4;
    Numeral 2 shows a charging air manifold that connects the charge outlet of the compressor 7b with the charging air inlet branch arm pipe 3;
    Numeral 9 shows an air cooler that cools the charging air passing through the charging air manifold 2.

    [0031] Further,
    Numeral 5 shows an exhaust gas branch arm pipe that is connected to the exhaust outlet of each cylinder cover 4;
    Numeral 6 shows a main exhaust manifold, namely a concentrated volume for exhaust gas, the volume being introduced for what is called a constant super-charging system;
    Numeral 110 shows an exhaust gas outlet pipe through which engine exhaust gas is discharged from the outlet of the exhaust gas turbine 7a to the atmosphere;
    Numeral 11 shows an exhaust gas by-pass pipe that diverges from the inlet of the exhaust gas turbine 7a, bypasses the exhaust gas turbine 7a, and is connected to the exhaust gas outlet pipe 110 on the outlet side of the turbine 7a.
    Numeral 12 shows an exhaust gas by-pass valve the throat area of which is variable;
    Numeral 10a shows an air inlet passage toward the turbocharger through which ambient air is inducted toward the cylinders via the turbocharger compressor 7b;
    Numeral 10 shows a gas-air mixer that is provided part way along the air inlet passage 10a toward the turbocharger;
    Numeral 21 shows a gas supply source line through which fuel gas from a fuel-gas reservoir (not shown) is supplied to the engine, whereby a second gas line 211 toward suction air induced by the turbocharger or toward the gas air mixer, as well as a first gas line 212 toward each cylinder are branched from the gas supply source line 21.

    [0032] In relation to the above, the second gas line 211 is connected to the air-gas mixer 10 that is provided part way along the air inlet passage 10a toward the turbocharger, while the first gas line 212 branches, part way along the first gas line, toward a gas supply branch arm pipe 213 at each cylinder, the pipe 213 being connected to the charging air inlet branch arm pipe 3. The gas-air mixer is capable of supplying fuel-gas into the suction air so that the concentration of the air fuel mixture is kept lower than a prescribed concentration below a lean limit of flammability as to the fuel-gas; preferably, a mixer of a venturi type is used.

    [0033] In Fig. 1, Numeral 18 shows a gas compressor that is provided on the line 212, and pressurizes the fuel-gas so that the fuel-gas passing through the line 212 can flow into the boosted charging air;
    Numeral 19 shows a second gas valve for suction air, on the second gas line 211; this second gas valve controls fuel-gas flow through the line 211, with on-off (open-close) movements; Numeral 20 shows a first gas valve which is provided on the gas supply branch arm pipe to each cylinder; the fuel-gas flow through each valve 20 is controlled by varying its throat area so as to regulate the fuel-gas flow rate to each individual cylinder of the engine.

    [0034] Further, Numeral 15 shows an engine speed sensor that measures the rotational speed of the engine-generator; Numeral 013 shows a load sensor, namely, an engine load sensor; Numeral 17 shows a charging air pressure sensor that measures the pressure at the charging air manifold 2; Numeral 16 shows a charging air temperature sensor that measures the temperature at the charging air manifold 2; Numeral 021 shows a flow meter that measures the fuel-gas flow rate through the second gas line 211.

    [0035] Still further, Numeral 24 denotes an engine speed controller; Numeral 23 denotes an air-fuel ratio controller; Numeral 22 denotes a valve opening/closing controller; whereby,
    a detected engine speed signal from the engine speed sensor 15 is outputted to the engine speed controller 24, the air-fuel ratio controller 23, and the valve opening/closing controller 22;
    a detected engine load signal from engine load sensor 013 is outputted to the air-fuel ratio controller 23;
    a detected charging air pressure signal from charging air pressure sensor 17 is outputted to the air-fuel ratio controller 23 and the valve opening/closing controller 22;
    a detected fuel-gas flow rate signal from the flow meter 021 is outputted to the valve opening/closing controller 22.

    [0036] The engine speed controller 24 is generally an electric governor, and the controller regulates opening levels of the first gas valve 20 for each cylinder, as a feedback response to the detected engine speed signals from the engine speed sensor 15.

    [0037] The air-fuel ratio controller 23 regulates opening levels of the exhaust gas by-pass valve 12, with a means described later, in response to the detected engine speed signals from the engine speed sensor 15, the detected load signals from the load sensor 013, the detected charging air pressure signals from the charging air pressure sensor 17, and the detected charging air temperature signals from the charging air temperature sensor 16.

    [0038] During the gas engine operation, the fuel-gas from the gas supply (source) line 21 flows into the line 212, or flows into the lines 212 and 211. The second gas line 211 leads fuel-gas to the gas-air mixer 10 where the fuel-gas is mixed with the air flowing along the air inlet
    passage 10a toward the turbocharger; whereby, the air fuel mixture is inducted into the turbocharger compressor 7b. The mixture is pressurized into a state of high pressure and temperature, by a substantially adiabatic compression process through the turbocharger compressor 7b; the mixture is cooled by the air cooler 9 and flows into the charging air inlet branch arm pipes 3 after passing through the charging air manifold 2.

    [0039] The fuel-gas that flows into the line 212, namely, the first gas line 212, is compressed by the gas compressor 18; then, after passing through each gas supply branch arm pipe 213 to the engine cylinders, the fuel-gas flows to the charging air inlet branch arm pipes 3 and is mixed with the air or the before-described air fuel mixture through the charging air manifold 2.

    [0040] On the other hand, the exhaust gas from the cylinders of the engine 1 flows through the exhaust gas branch arm pipes 5, and enters the main exhaust manifold; then, the exhaust gas is led to the exhaust gas turbine 7a; and after driving the compressor 7b, the exhaust gas is discharged to the atmosphere through the exhaust gas outlet pipe.

    [0041] Further, when the exhaust gas by-pass valve 12 is opened in response to a control-order signal from the air-fuel ratio controller 23 in a manner as described later, then a part of the exhaust gas in the main exhaust manifold bypasses the exhaust gas turbine 7a, and is released directly toward the exhaust gas outlet pipe 11.

    [0042] With reference to the engine configuration stated thus far, the engine control method will now be described in detail.

    [0043] In the first place, a conventional control method as a contrasting example for the present invention is explained with Figs. 3a to 3c. Fig. 3a shows a load transition as to a conventional engine; Fig. 3b shows a transition as to an order signal that is transmitted to the first gas valve for each cylinder; and, Fig. 3c shows a transition as to an order signal that is transmitted to the second gas valve for suction air. As shown in Figs. 3a, 3b, and 3c, in the conventional control method, the opening levels of the first gas valve for each cylinder are controlled in response to the engine load levels so as to regulate the gas flow rates. Thus, in the conventional way whereby the second gas valve for suction air is not provided, only the first gas valve for each cylinder controls fuel amounts for each cylinder; namely, the conventional way corresponds to a manner in which the fuel order signal toward the second gas valve for suction air is always null in the embodiment of Fig. 1.

    [0044] On the other hand, Figs. 2a, 2b, and 2c explain a control method as an embodiment of this invention. Fig. 2a shows a load transition as to the engine according to an embodiment of this invention; Fig. 2b shows a transition as to an order signal that is transmitted to the first gas valve for each cylinder; and, Fig. 2c shows a transition as to an order signal that is transmitted to the second gas valve for suction air. In the embodiment as shown in Figs. 2a, 2b, and 2c, the second gas valve for suction air is opened in the case when the fuel-gas is of a low calorific value, or the engine output is high; and, fuel-gas is supplied to the engine both through the second gas valve for suction air and through the first gas valve for each cylinder. In the case when the fuel-gas is of a high calorific value, or in the case when the output of the engine is low, the second gas valve for suction air is closed; and, fuel-gas is supplied only through the first gas valve for each cylinder.

    [0045] To be more specific, the opening levels of the first gas valve for each cylinder and the load levels of the engine are detected; and, the second gas valve for suction air is opened, in the case when the opening levels of the first gas valve for each cylinder are full (i.e., 100%) or nearly full (i.e., more than a predetermined level) and the load levels of the engine are increasing as shown in the neighborhood of a time point A in Fig. 2c. Further, an air fuel mixture of a predetermined air fuel ratio is achieved at the before-mentioned mixer; in addition, the opening levels of the first gas valve for each cylinder are regulated so that the air fuel ratio of an air fuel mixture just before each cylinder is at a predetermined level (a final air fuel ratio as to an air fuel mixture that is burned in each cylinder). In this connection, it is noted that the opening levels of the first gas valve for each cylinder are lowered from a full level, while the opening levels of the second gas valve for suction air are full (100%) or near full, for example, during a time process from a time point A to a time point B in Fig. 2c.

    [0046] Further, the first gas valve for each cylinder regulates fuel-gas flow rates with regard to the levels of the engine load, while the second gas valve for suction air is fully (100%) opened; whereby, an air fuel mixture of a predetermined air fuel ratio the mixture which includes air inducted by the turbocharger, and fuel supplied through the first gas valve for each cylinder are mixed just before each cylinder so that a predetermined air fuel ratio for a final air fuel mixture is achieved. Hereby, it is reconfirmed that a final air fuel mixture means the air fuel mixture that is burned in each cylinder.

    [0047] Still further, under the condition that the second gas valve for suction air is opened and the levels of the engine load are detected, when the detected level of the engine load becomes less than a predetermined level, then the second gas valve for suction air is closed and the air fuel ratio control is performed only by the first gas valve for each cylinder, on the basis that the fuel-gas being used has a high calorific value or the output of the engine becomes low; this situation is depicted around a time point C in Fig. 2c.

    [0048] As described above, the maximum flow rate as a threshold value of the second gas valve for suction air is calculated in advance; and, when the flow rate through the mentioned valve becomes lower than or equal to the threshold value, then the second gas valve for inducted air is closed and only the first gas valve for each cylinder regulates the fuel flow rate. Thus, a simple control with precision can be achieved.

    [0049] In the embodiment as described above, by means of the manner that fuel gas is supplied to the suction air induced by the turbocharger only in the case when the fuel-gas supply is greater than at a predetermined rate, as is the case when the fuel-gas is of a low calorific value or the engine output is high, the required fuel gas supply is achieved with precision. Further, the described-embodiment is provided with a gas mixer that achieves a fuel gas mixture with a concentration below a lean limit of flammability as to the fuel-gas; and, a part of the required amount of fuel-gas is supplied through the mixer in the case when a larger fuel flow rate is needed; thus, the size and capacity of the gas compressor can be reduced; further, potential fuel-gas explosion risks in the air supply passage can be removed; what is more, since the mixer yields an air fuel mixture of a prescribed concentration, the air fuel control at the first gas valve for each cylinder can be simplified.

    [0050] Moreover, since whether or not the fuel-gas supply through the mixer is necessary can be simply and pertinently judged in the described embodiment, and the second gas valve for suction air is scheduled to be opened in response to the judgment in the case when the first gas valves for each cylinder are fully opened and the output of the engine is increasing, an air fuel control with precision can be realized.

    [0051] In addition, in the case when the output of an engine is lowered below a prescribed value, then, the second gas valve for suction air is closed; serving as a simple and precise control.

    Industrial Applicability



    [0052] The described embodiment provides a gas engine comprising:

    a first fuel-gas supply system in which fuel-gas is mixed with suction air inducted by a turbocharger of the engine and the fuel air mixture is fed to the engine through the turbocharger;

    a second fuel-gas supply system in which fuel-gas is supplied to a charge air passage of each cylinder;

    whereby potential fuel-gas explosion risks in the air supply passage, at the outlet of a turbocharger compressor, can be removed;

    moreover, in the case when fuel-gas of a low calorific value is used, less power is needed to drive the gas compressor than would otherwise be required, the gas compressor being provided in the second fuel-gas supply system for pressurizing the fuel-gas to the charge air passage of each cylinder;

    further, the size and capacity of the gas compressor is less than would otherwise be required.



    [0053] Thus, the embodiment disclosed in this specification is useful as an industrial technology.


    Claims

    1. A method to control a gas engine that ignites and burns fuel-gas, the gas engine comprising:

    a turbocharger that pressurizes ambient air and supplies the air to the engine to a plurality of cylinders;

    a first gas line (212), with a branch line coming off it for each cylinder;

    a first gas valve (20) for each cylinder, the valve being fitted on the gas supply branch line and being able to regulate the flow rate of the fuel-gas toward each cylinder;

    a gas compressor (18) that is provided on the first gas line (212) that compresses the fuel-gas toward the first gas valve through the first gas line so that the pressure through the first gas line (212) exceeds a pressure boosted by the turbocharger;

    whereby, the fuel-gas through the first gas line (212) and the air through the turbocharger are mixed to form an air gas mixture;

    and, the engine further comprises:

    a second gas line (211) toward suction air before the turbocharger the line which is branched from the gas supply source line;

    a second gas valve (19) for the suction air the valve which is provided on the second gas line (211) toward the suction air before the turbocharger, and is regulated with on-off movements; an air gas mixer (10) that is provided on the upstream air inflow line of the suction air toward the turbocharger, and mixes the fuel-gas through the second gas line with the ambient air induced toward the turbocharger,

    wherein the method comprises:

    opening the second gas valve (19) for the suction air in the case when the fuel-gas is of a low calorific value, or in the case when an output of the engine is high, so that fuel-gas is supplied to the engine both through the second gas valve for suction air and through the first gas valve for each cylinder;

    closing the second gas valve (19) for the suction air in the case when the fuel-gas is of a high calorific value, or in the case when an output of the engine is low, so that fuel-gas is supplied only through the first gas valve for each cylinder; and

    mixing the fuel-gas and the air by means of the air gas mixer (10) so as to form a mixture of a prescribed mixing ratio that is leaner than a lower limit of flammability as to the fuel-gas,

    wherein the air fuel-gas mixture is supplied to the turbocharger, while the remaining fuel-gas that is not supplied to the mixer from the gas supply source line is sent to each cylinder through the gas compressor and through the first gas line toward each cylinder, so that a prescribed air fuel ratio is formed in each cylinder by regulating the first gas valve for each cylinder;

    and, in the case when the fuel-gas is of a high calorific value, or in the case when an output of the engine is low, the second gas valve for suction air is closed so that the whole fuel-gas from the gas supply source line is directed toward each cylinder through the first gas line.


     
    2. The method to control a gas engine according to claim 1, the engine further comprising:

    a means to detect opening levels of the first gas valve; and

    a means to detect output levels of the engine; whereby, in response to the detected opening levels and the output levels, the second gas valve for the suction air is opened with an estimation that the fuel gas is of a low calorific value or the higher output of the engine is being required, in the case when the first gas valve for each cylinder is fully opened and the output of the engine is increasing.


     
    3. The method to control a gas engine according to claim 1, the engine further comprising:

    a means to detect opening levels of the first gas valve; and

    a means to detect output levels of the engine; whereby, in response to the detected opening levels and the output levels, the second gas valve for the suction air is closed with an estimation that the fuel-gas served for operation has changed into a fuel of a high calorific value or the output of the engine is reduced, in the case when the detected output of the engine becomes low and less than a prescribed value.


     
    4. A gas engine and a gas engine system thereof that ignites and burns fuel-gas, the gas engine comprising:

    a turbocharger that pressurizes ambient air and supplies the air to the engine to a plurality of cylinders;

    a charging air flow-rate control valve such as an exhaust gas by-pass valve that controls the flow rate of the charged air through the turbocharger into the cylinders, the control valve serving as a means to determine air flow rates when a prescribed air fuel ratio is achieved;

    a first gas line (212) toward the cylinders, the line communicating a gas supply branch arm pipe that is provided in front of each cylinder, with a gas supply source line;

    a first gas valve (20) for each cylinder, the valve being fitted on the gas supply branch arm pipe, the valve being able to regulate the flow rates of the fuel-gas toward each cylinder, through the first valve the valve acting as a fuel gas injector that injects fuel-gas into air boosted by the turbocharger, in front of each cylinder, so that the first gas valve injects a prescribed amount of fuel-gas in order to produce a to-be-burnt air fuel-gas mixture of a prescribed air fuel mixture;

    a gas compressor that is provided on the first gas line that compresses the fuel-gas toward the first gas valve through the first gas line so that the pressure through the first gas line exceeds a pressure boosted by the turbocharger;

    whereby, the engine further comprises:

    a second gas line (211) toward suction air before the turbocharger the line which is branched from the gas supply source line;

    a second gas valve (19) for the suction air the valve which is provided on the second gas line toward the suction air before the turbocharger, and is regulated
    with on-off movements;

    an air gas mixer (10) that is provided on the upstream air inflow line of the suction air toward the turbocharger, and mixes the fuel-gas through the second gas line with the ambient air induced toward the turbocharger; and

    a valve opening/closing controller (22) that is provided for controlling open/close of the second gas valve for the suction air;

    wherein the valve opening/closing controller (22) opens the second gas valve (19) for the suction air in the case when the fuel-gas is of a low calorific value, or in the case when an output of the engine is high so that fuel-gas is supplied to the engine both through the second gas valve for suction air and through the first gas valve for each cylinder; and

    wherein the valve opening/closing controller (22) closes the second gas valve (19) for the suction air in the case when the fuel-gas is of a high calorific value, or in the case when an output of the engine is low, so that fuel-gas is supplied only through the first gas valve for each cylinder;

    whereby, the air gas mixer (10) is capable of mixing the fuel-gas and the air so as to form a mixture of a prescribed mixing ratio that is leaner than a lower limit of flammability as to the fuel-gas, and the air fuel-gas mixture is supplied to the turbocharger, while the remaining fuel-gas that is not supplied to the mixer from the gas supply source line is sent to each cylinder through the gas compressor and through the first gas line toward each cylinder, so that a prescribed air fuel ratio is formed in each cylinder by regulating the first gas valve for each cylinder.
     
    5. The gas engine and a gas engine system thereof according to claim 4, whereby the air gas mixer (10) is of a venturi type, the mixer mixing the suction air with the fuel-gas through the second gas valve (19) and the second gas line (211) so that an air fuel mixture of a prescribed air fuel-gas ratio is achieved.
     


    Ansprüche

    1. Verfahren zur Steuerung eines Gasmotors, der Brenngas entzündet und verbrennt, wobei der Gasmotor umfasst:

    einen Turbolader, der die Außenluft komprimiert und die Luft einer Vielzahl von Zylindern im Motor zuführt;

    eine erste Gasleitung (212) mit je einer Abzweigleitung für jeden Zylinder, die davon abgeht;

    ein erstes Gasventil (20) für jeden Zylinder, wobei das Ventil in der Gasversorgungsabzweigleitung eingebaut und zur Regelung des Brenngasdurchsatzes zu jedem Zylinder geeignet ist;

    einen Gaskompressor (18), der in der ersten Gasleitung (212) eingebaut ist, der das Brenngas durch die erste Gasleitung zum ersten Gasventil hin komprimiert, sodass der Druck durch die erste Gasleitung (212) einen durch den Turbolader verstärkten Druck übersteigt;

    wobei das Brenngas durch die erste Gasleitung (212) und die Luft durch den Turbolader vermengt werden und ein Luft-Gas-Gemisch bilden;

    und der Motor weiter umfasst:

    eine zweite Gasleitung (211) zur Ansaugluft vor dem Turbolader, die von der Gasversorgungsquellenleitung abzweigt;

    ein zweites Gasventil (19) für die Ansaugluft, wobei das Ventil in der zweiten Gasleitung (211) zur Ansaugluft vor dem Turbolader eingebaut ist, und durch Ein/Aus-Bewegungen geregelt wird;

    einen Luft-Gas-Mischer (10), der in der davor angeordneten Zuleitung der Ansaugluft zum Turbolader hin eingebaut ist und das Brenngas durch die zweite Gasleitung mit der zum Turbolader geführten Außenluft mischt,

    wobei das Verfahren umfasst:

    Öffnen des zweiten Gasventils (19) für die Ansaugluft für den Fall, dass das Brenngas einen geringen Brennwert hat, oder für den Fall, dass eine Leistungsabgabe des Motors hoch ist, sodass Brenngas zum Motor sowohl durch das zweite Gasventil für Ansaugluft als auch durch das erste Gasventil für jeden Zylinder zugeführt wird;

    Schließen des zweiten Gasventils (19) für die Ansaugluft für den Fall, dass das Brenngas einen hohen Brennwert hat, oder für den Fall, dass eine Leistungsabgabe des Motors gering ist, sodass Brenngas nur durch das erste Gasventil für jeden Zylinder zugeführt wird; und

    Mischen des Brenngases und der Luft mithilfe des Luft-Gas-Mischers (10), sodass ein Gemisch in einem vorgegebenen Mischverhältnis entsteht, das magerer ist als eine Entflammbarkeitsuntergrenze in Bezug auf das Brenngas,

    wobei das Luft-Gas-Gemisch dem Turbolader zugeführt wird, während das verbleibende Brenngas, das dem Mischer nicht aus der Gaszuführleitung zugeführt wird, durch den Gaskompressor und durch die erste Gasleitung jedem Zylinder zugeführt wird, sodass sich in jedem Zylinder durch Regelung des ersten Gasventils in jedem Zylinder ein vorgegebenes Luft-Brennstoff-Gemisch bildet;

    und, für den Fall, dass das Brenngas einen hohen Brennwert aufweist, oder für den Fall, dass die Leistungsabgabe des Motors gering ist, das zweite Gasventil für die Ansaugluft geschlossen wird, sodass das gesamte Brenngas aus der Gasversorgungsquellenleitung durch die erste Gasleitung zu jedem Zylinder geleitet wird.


     
    2. Verfahren zur Steuerung eines Gasmotors nach Anspruch 1, wobei der Motor weiter umfasst:

    ein Mittel zur Erfassung der Öffnungsstufen des ersten Gasventils; und

    ein Mittel zur Erfassung der Leistungsabgabestufen des Motors; wobei das zweite Gasventil für die Ansaugluft als Reaktion auf die erfassten Öffnungsstufen und Leistungsabgabestufen mit einer Schätzung geöffnet wird, dass das Brenngas einen zu niedrigen Brennwert hat, oder die höhere Leistungsabgabe des Motors erforderlich ist, für den Fall, dass das erste Gasventil für jeden Zylinder vollständig offen und die Leistungsabgabe des Motors zunehmend ist.


     
    3. Verfahren zur Steuerung eines Gasmotors nach Anspruch 1, wobei der Motor weiter umfasst:

    ein Mittel zur Erfassung der Öffnungsstufen des ersten Gasventils; und

    ein Mittel zur Erfassung der Leistungsabgabestufen des Motors; wobei das zweite Gasventil für die Ansaugluft als Reaktion auf die erfassten Öffnungsstufen und Leistungsabgabestufen mit einer Schätzung geschlossen wird, dass sich das für den Betrieb gelieferte Brenngas in einen Brennstoff mit einem höheren Brennwert verwandelt hat, oder die Leistungsabgabe des Motors verringert wurde, für den Fall, dass die erfasste Leistungsabgabe des Motors abnimmt und unter einen vorgegebenen Wert sinkt.


     
    4. Ein Gasmotor und ein entsprechendes Gasmotorsystem, das Brenngas entzündet und verbrennt, wobei der Gasmotor umfasst:

    einen Turbolader, der die Außenluft komprimiert und die Luft einer Vielzahl von Zylindern im Motor zuführt;

    ein Steuerventil für den Durchsatz der zugeführten Luft, wie etwa ein Abgas-Bypassventil, das den Durchsatz der zugeführten Luft durch den Turbolader in die Zylinder regelt, wobei das Steuerventil als Mittel zur Erfassung des Luftdurchsatzes dient, wenn ein vorgegebenes Luft-Brennstoff-Verhältnis erreicht ist;

    eine erste Gasleitung (212) zu den Zylindern, wobei die Leitung ein vor jedem Zylinder zur Gasversorgung angeordnetes Abzweigrohr mit einer Gasversorgungsquellenleitung verbindet;

    ein erstes Gasventil (20) für jeden Zylinder, wobei das Ventil im Abzweigrohr zur Gasversorgung eingebaut ist, das Ventil zur Regelung des Brenngas-Durchsatzes durch das erste Ventil zu jedem Zylinder geeignet ist, wobei das Ventil als Brenngas-Injektor wirkt, der vor jedem Zylinder Brenngas in vom Turbolader komprimierte Luft einspritzt, sodass das erste Gasventil eine vorgegebene Menge Brenngas injiziert, um ein zu verbrennendes Luft-Brenngas-Gemisch in einem vorgegebenen Luft-Brennstoff-Verhältnis zu erzeugen;

    einen Gaskompressor, der in der ersten Gasleitung eingebaut ist, der das Brenngas durch die erste Gasleitung zum ersten Gasventil verdichtet, sodass der Druck durch die erste Gasleitung einen durch den Turbolader erhöhten Druck übersteigt;

    wobei der Motor weiter umfasst:

    eine zweite Gasleitung (211) zur Ansaugluft vor dem Turbolader, wobei die Leitung von der Gasversorgungquellenleitung abgezweigt wird;

    ein zweites Gasventil (19) für die Ansaugluft, wobei das Ventil in der zweiten Gasleitung zur Ansaugluft vor dem Turbolader eingebaut ist und durch Ein/Aus-Bewegungen geregelt wird;

    einen Luft-Gas-Mischer (10), der in der vorgelagerten Luftzufuhrleitung der Ansaugluft zum Turbolader eingebaut ist und das Brenngas durch die zweite Gasleitung mit der Außenluft zum Turbolader vermischt; und

    einen Auf/Zu-Regler (22) für das Ventil, der zur Regelung des Öffnen/Schließens des zweiten Gasventils für die Ansaugluft vorgesehen ist;

    wobei der Auf/Zu-Regler (22) für das Ventil das zweite Gasventil (19) für die Ansaugluft für den Fall öffnet, dass das Brenngas einen niedrigen Brennwert hat, oder für den Fall, dass die Leistungsabgabe des Motors hoch ist, sodass Brenngas sowohl durch das zweite Gasventil für Ansaugluft als auch durch das erste Gasventil für jeden Zylinder zugeführt wird; und

    wobei der Auf/Zu-Regler (22) für das Ventil das zweite Gasventil (19) für die Ansaugluft für den Fall schließt, dass das Brenngas einen hohen Brennwert hat, oder für den Fall, dass die Leistungsabgabe des Motors gering ist, sodass Brenngas nur durch das erste Gasventil für jeden Zylinder zugeführt wird;

    wobei der Luft-Gas-Mischer (10) in der Lage ist, das Brenngas und die Luft zu mischen, dass eine Mischung in einem vorgegebenen Mischverhältnis entsteht, das magerer ist als eine Entflammbarkeitsuntergrenze in Bezug auf das Brenngas, und das Luft-Brenngas-Gemisch dem Turbolader zugeführt wird, während das verbleibende Brenngas, das dem Mischer nicht aus der Gaszuführleitung zugeführt wird, durch den Gaskompressor und durch die erste Gasleitung jedem Zylinder zugeführt wird, sodass sich für jeden Zylinder durch Regelung des ersten Gasventils für jeden Zylinder ein vorgegebenes Luft-Brenngas-Gemisch bildet.


     
    5. Gasmotor und ein entsprechendes Gasmotorsystemzubehör nach Anspruch 4, wobei der Luft-Gas-Mischer (10) vom Typ Venturi ist, wobei der Mischer die Ansaugluft mit dem Brenngas durch das zweite Gasventil (19) und die zweite Gasleitung (211) mischt, sodass ein Luft-Brennstoff-Gemisch in einem vorgegebenen Luft-Brenngas-Verhältnis erzielt wird.
     


    Revendications

    1. Procédé pour commander un moteur à gaz qui allume et fait brûler un combustible gazeux, le moteur à gaz comprenant :

    un turbocompresseur qui met sous pression l'air ambiant et apporte l'air au moteur jusqu'à une pluralité de cylindres ;

    une première conduite de gaz (212), avec une conduite de bifurcation partant d'elle pour chaque cylindre ;

    une première soupape de gaz (20) pour chaque cylindre, la soupape étant installée sur la conduite de bifurcation d'alimentation en gaz et étant capable de réguler le débit du combustible gazeux vers chaque cylindre ;

    un compresseur de gaz (18) qui est disposé sur la première conduite de gaz (212) qui comprime le combustible gazeux vers la première soupape de gaz à travers la première conduite de gaz de telle sorte que la pression à travers la première conduite de gaz (212) dépasse une pression amplifiée par le turbocompresseur ;

    selon lequel, le combustible gazeux à travers la première conduite de gaz (212) et l'air à travers le turbocompresseur sont mélangés pour former un mélange air-gaz ;

    et, le moteur comprend en outre :

    une seconde conduite de gaz (211) vers l'air d'aspiration avant le turbocompresseur, laquelle conduite bifurque de la conduite de source d'alimentation en gaz ;

    une seconde soupape de gaz (19) pour l'air d'aspiration, laquelle soupape est disposée sur la seconde conduite de gaz (211) vers l'air d'aspiration avant le turbocompresseur, et est régulée par des déplacements marche-arrêt ;

    un mélangeur air-gaz (10) qui est disposé sur la conduite d'écoulement entrant d'air amont de l'air d'aspiration vers le turbocompresseur, et mélange le combustible gazeux à travers la seconde conduite de gaz avec l'air ambiant induit vers le turbocompresseur,

    dans lequel le procédé comprend :

    l'ouverture de la seconde soupape de gaz (19) pour l'air d'aspiration dans le cas où le combustible gazeux est d'une valeur calorifique faible, ou dans le cas où une sortie du moteur est élevée, de telle sorte que le combustible gazeux est apporté au moteur à la fois par la seconde soupape de gaz pour air d'aspiration et par la première soupape de gaz pour chaque cylindre ;

    la fermeture de la seconde soupape de gaz (19) pour l'air d'aspiration dans le cas où le combustible gazeux est d'une valeur calorifique élevée, ou dans le cas où une sortie du moteur est faible, de telle sorte que le combustible gazeux est apporté uniquement par la première soupape de gaz pour chaque cylindre ; et

    le mélange du combustible gazeux et de l'air au moyen du mélangeur air-gaz (10) de manière à former un mélange d'un rapport de mélange prescrit qui est plus pauvre qu'une limite inférieure d'inflammabilité quant au combustible gazeux,

    dans lequel le mélange air-combustible gazeux est apporté au turbocompresseur, alors que le reste du combustible gazeux qui n'est pas apporté au mélangeur depuis la conduite de source d'alimentation en gaz est envoyé à chaque cylindre à travers le compresseur de gaz et à travers la première conduite de gaz vers chaque cylindre, de telle sorte qu'un rapport air-combustible prescrit est formé dans chaque cylindre en régulant la première soupape de gaz pour chaque cylindre ;

    et, dans le cas où le combustible gazeux est d'une valeur calorifique élevée, ou dans le cas où une sortie du moteur est faible, la seconde soupape de gaz pour air d'aspiration est fermée de telle sorte que l'ensemble du combustible gazeux provenant de la conduite de source d'alimentation en gaz est dirigé vers chaque cylindre par la première conduite de gaz.


     
    2. Procédé pour commander un moteur à gaz selon la revendication 1, le moteur comprenant en outre :

    un moyen pour détecter des niveaux d'ouverture de la première soupape de gaz ; et

    un moyen pour détecter des niveaux de sortie du moteur; selon lequel, en réponse aux niveaux d'ouverture et aux niveaux de sortie détectés, la seconde soupape de gaz pour l'air d'aspiration est ouverte avec une estimation selon laquelle le combustible gazeux est d'une valeur calorifique faible ou la sortie plus élevée du moteur est requise, dans le cas où la première soupape de gaz pour chaque cylindre est totalement ouverte et la sortie du moteur augmente.


     
    3. Procédé pour commander un moteur à gaz selon la revendication 1, le moteur comprenant en outre :

    un moyen pour détecter des niveaux d'ouverture de la première soupape de gaz ; et

    un moyen pour détecter des niveaux de sortie du moteur; selon lequel, en réponse aux niveaux d'ouverture et aux niveaux de sortie détectés, la seconde soupape de gaz pour l'air d'aspiration est fermée avec une estimation selon laquelle le combustible gazeux servi pour le fonctionnement a changé en combustible d'une valeur calorifique élevée ou la sortie du moteur est réduite, dans le cas où la sortie détectée du moteur devient faible et inférieure à une valeur prescrite.


     
    4. Moteur à gaz et système de moteur à gaz associé qui allume et fait brûler du combustible gazeux, le moteur à gaz comprenant :

    un turbocompresseur qui met sous pression de l'air ambiant et apporte l'air au moteur jusqu'à une pluralité de cylindres ;

    une soupape de commande de débit d'air de charge telle qu'une soupape de dérivation de gaz d'échappement qui commande le débit de l'air chargé à travers le turbocompresseur jusque dans les cylindres, la soupape de commande servant de moyen pour déterminer des débits d'air quand un rapport air-combustible est atteint ;

    une première conduite de gaz (212) vers les cylindres, la conduite faisant communiquer avec un tuyau de bras de bifurcation d'alimentation en gaz qui est disposé devant chaque cylindre avec une conduite de source d'alimentation en gaz ;

    une première soupape de gaz (20) pour chaque cylindre, la soupape étant installée sur le tuyau de bras de bifurcation d'alimentation en gaz, la soupape étant capable de réguler les débits du combustible gazeux vers chaque cylindre, à travers la première soupape, la soupape agissant comme un injecteur de combustible gazeux qui injecte le combustible gazeux dans l'air amplifié par le turbocompresseur, devant chaque cylindre, de telle sorte que la première soupape de gaz injecte une quantité prescrite de combustible gazeux afin de produire un mélange air-combustible gazeux à faire brûler d'un mélange air-combustible prescrit ;

    un compresseur de gaz qui est disposé sur la première conduite de gaz qui comprime le combustible gazeux vers la première soupape de gaz à travers la première conduite de gaz de telle sorte que la pression à travers la première conduite de gaz dépasse une pression amplifiée par le turbocompresseur ;

    selon lequel, le moteur comprend en outre :

    une seconde conduite de gaz (211) vers l'air d'aspiration avant le turbocompresseur, laquelle conduite bifurque de la conduite de source d'alimentation en gaz ;

    une seconde soupape de gaz (19) pour l'air d'aspiration, laquelle soupape est disposée sur la seconde conduite de gaz vers l'air d'aspiration avant le turbocompresseur, et est régulée par des déplacements marche-arrêt ;

    un mélangeur air-gaz (10) qui est disposé sur la conduite d'écoulement entrant d'air amont de l'air d'aspiration vers le turbocompresseur, et mélange le combustible gazeux à travers la seconde conduite de gaz avec l'air ambiant induit vers le turbocompresseur ; et

    un dispositif de commande d'ouverture/fermeture de soupape (22) qui est prévu pour commander l'ouverture/fermeture de la seconde soupape de gaz pour l'air d'aspiration ;

    dans lequel le dispositif de commande d'ouverture/fermeture de soupape (22) ouvre la seconde soupape de gaz (19) pour l'air d'aspiration dans le cas où le combustible gazeux est d'une valeur calorifique faible, ou dans le cas où une sortie du moteur est élevée de telle sorte que le combustible gazeux est apporté au moteur à la fois à travers la seconde soupape de gaz pour air d'aspiration et à travers la première soupape de gaz pour chaque cylindre ; et

    dans lequel le dispositif de commande d'ouverture/fermeture de soupape (22) ferme la seconde soupape de gaz (19) pour l'air d'aspiration dans le cas où le combustible gazeux est d'une valeur calorifique élevée, ou dans le cas où une sortie du moteur est faible, de telle sorte que le combustible gazeux est apporté uniquement à travers la première soupape de gaz pour chaque cylindre ;

    selon lequel, le mélangeur air-gaz (10) est capable de mélanger le combustible gazeux et l'air de manière à former un mélange d'un rapport de mélange prescrit qui est plus pauvre qu'une limite inférieure d'inflammabilité quant au combustible gazeux, et le mélange air-combustible gazeux est apporté au turbocompresseur, alors que le reste du combustible gazeux qui n'est pas apporté au mélangeur depuis la conduite de source d'alimentation en gaz est envoyé à chaque cylindre à travers le compresseur de gaz et à travers la première conduite de gaz vers chaque cylindre, de telle sorte qu'un rapport air-combustible prescrit est formé dans chaque cylindre en régulant la première soupape de gaz pour chaque cylindre.


     
    5. Moteur à gaz et système de moteur à gaz associé selon la revendication 4, selon lequel le mélangeur air-gaz (10) est d'un type venturi, le mélangeur mélangeant l'air d'aspiration avec le combustible gazeux à travers la seconde soupape de gaz (19) et la seconde conduite de gaz (211) de telle sorte qu'un mélange air-combustible d'un rapport air-combustible gazeux prescrit est atteint.
     




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    Cited references

    REFERENCES CITED IN THE DESCRIPTION



    This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.

    Patent documents cited in the description