Mixture-charged gas engine and method for compensating for volumetric efficiency deviations in a mixture-charged gas engine

Abstract

A mixture-charged gas engine includes at least one cylinder. A combustion chamber delimited by a cylinder head, a cylinder wall, and a piston, which can be moved in the cylinder, is arranged in the at least one cylinder, and the combustion chamber is divided into a main combustion chamber and at least one pre-chamber fluidically connected to the main combustion chamber via at least one firing channel. An air-/combustion gas mixture can be supplied to the main combustion chamber via an inlet valve during an intake stroke of the piston. The mixture-charged gas engine is characterized in that a separate combustion gas supply is provided for the at least one pre-chamber.

Claims

1. A mixture charged gas engine, comprising: at least one cylinder having a cylinder head and a cylinder wall; a piston movably arranged in said at least one cylinder, said piston, said cylinder head, and said cylinder wall delimiting a combustion chamber which includes a main combustion chamber; an inlet valve connected to said main combustion chamber, wherein said inlet valve admits an air-/combustion gas mixture into said main combustion chamber during an intake stroke of said piston; at least one pre-chamber including at least one firing channel that is fluidically connected with said main combustion chamber; a separate combustion gas supply provided for said at least one pre-chamber; at least one sensor configured to sense a volumetric efficiency parameter of said at least one cylinder; at least one valve arranged in a fluid path for combustion of said separate combustion gas supply and configured to allow an adjustable gas volume to be admitted into said at least one pre-chamber; and a controller coupled to said at least one sensor and said at least one valve, said controller including non-transitory executable instructions to: determine at least one of a cylinder specific volumetric efficiency and a cylinder bank specific volumetric efficiency from a volumetric efficiency parameter sensed by said at least one sensor; compare the at least one of said determined cylinder specific volumetric efficiency and said determined cylinder bank specific volumetric efficiency to a desired volumetric efficiency; and control said at least one valve to admit said adjustable gas volume into said at least one pre-chamber if the at least one of said determined cylinder specific volumetric efficiency and said determined cylinder bank specific volumetric efficiency is below said desired volumetric efficiency.

2. The mixture charged gas engine according to claim 1, wherein said at least one valve is at least one of a force-controlled valve and an electromagnetic valve.

3. The mixture charged engine according to claim 2, wherein said engine comprises at least two cylinders or at least two cylinder banks.

4. The mixture charged gas engine according to claim 3, further comprising an exhaust gas manifold fluidically connected with outlet valves of said at least two cylinders or said at least two cylinder banks and a turbo charger which is fluidically connected with said exhaust gas manifold, whereby exhaust gas flows to said turbo charger from said at least two cylinders or said at least two cylinder banks via said exhaust gas manifold.

5. The mixture charged gas engine according to claim 4, further comprising at least one catalytic converter assigned to at least one cylinder or at least one cylinder bank and arranged before said turbo charger in a flow direction of the exhaust gas such that an exhaust gas counter pressure of said at least one catalytic converter contributes to an equalization of a volumetric efficiency of said at least two cylinders or said at least two cylinder banks.

6. The mixture charged engine according to claim 2, wherein at least one of an opening degree, an opening point of time, and an opening duration of said at least one valve is adjustable.

7. A method for compensating volumetric efficiency deviations in a mixture charged gas engine, said method comprising: providing said mixture charged gas engine having at least two cylinders or at least two cylinder banks, said at least two cylinders or at least two cylinder banks each including: a cylinder head; a cylinder wall; a piston movably arranged in said at least two cylinders or said at least two cylinder banks, said piston, said cylinder head, and said cylinder wall delimiting a combustion chamber including a main combustion chamber; an inlet valve connected to said main combustion chamber, wherein said inlet valve admits an air-/combustion gas mixture into said main combustion chamber during an intake stroke of said piston; at least one pre-chamber including at least one firing channel that is fluidically connected with said main combustion chamber; and a separate combustion gas supply provided for said at least one pre-chamber; sensing at least one of a volumetric efficiency parameter of each of said at least two cylinders and said at least two cylinder banks via at least one sensor; and via a controller, determining the at least one of a cylinder specific volumetric efficiency and a cylinder bank specific volumetric efficiency from said sensed volumetric efficiency parameter; comparing the at least one of said cylinder specific volumetric efficiency and said cylinder bank specific volumetric efficiency having been determined, to a desired volumetric efficiency; and controlling at least one valve to supply an adjustable gas volume to an individual one of said at least one pre-chamber if the at least one of said cylinder specific volumetric efficiency and said cylinder bank specific volumetric efficiency having been determined, is below said desired volumetric efficiency.

8. The method according to claim 7, wherein said at least one valve is at least one of a force-controlled valve and an electromagnetic valve.

9. The method according to claim 7, wherein said controlling step includes adjusting at least one of an opening degree, an opening point of time, and an opening duration of said at least one valve.

10. The method according to claim 7, wherein said volumetric efficiency parameter is at least one of an exhaust gas temperature, a nitrogen oxide emission, and a cylinder pressure.

11. The method according to claim 7, further comprising the step of compensating one of cylinder individual volumetric efficiency deviations and cylinder bank individual volumetric efficiency deviations so that all of said cylinders are operated closer to a knocking limit.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings, wherein:

(2) FIG. 1 is a schematic partial view of an embodiment of a mixture charged gas engine according to the present invention; and

(3) FIG. 2 is an additional schematic view of the gas engine shown in FIG. 1.

(4) Corresponding reference characters indicate corresponding parts throughout the several views. The exemplification set out herein illustrates one embodiment of the invention and such exemplification is not to be construed as limiting the scope of the invention in any manner.

DETAILED DESCRIPTION OF THE INVENTION

(5) Referring now to the drawings, and more particularly to FIG. 1, a schematic partial detailed view of an embodiment of a mixture charged gas engine 1 is shown that includes at least one cylinder 3, wherein a combustion chamber 11, delimited by a cylinder head 5, a cylinder wall 7 and a piston 9 that is arranged movably in cylinder 3, is arranged in cylinder 3.

(6) Combustion chamber 11 is divided into a main combustion chamber 13 and a pre-chamber 15, wherein pre-chamber 15 is fluidically connected via an opening 17 with main combustion chamber 13. In FIG. 1, three openings 17 in the embodiment of firing channels 19 are shown. Pre-chamber 15 is therefore connected with main combustion chamber 13 through a plurality of firing channels 19.

(7) In an intake stroke of piston 9 an air-/combustion gas mixtureas symbolized herein by an arrow P.sub.1is admitted via an inlet valve 21 into main combustion chamber 13. For this purpose, a mixture line 23 can be provided through which the mixture is delivered to inlet valve 21 and via same further into main combustion chamber 13.

(8) In one compression stroke, the mixture in main combustion chamber 13 is compressed and is pressed through firing channels 19 into pre-chamber 15. Subsequent ignition and combustion of the mixture occurs. In an exhaust stroke of piston 9, exhaust gas is forced from main combustion chamber 13 via an outlet valve 25 into an exhaust line 27 and is thus evacuated from main combustion chamber 13. This is illustrated in FIG. 1 by an arrow P.sub.2.

(9) Gas engine 1 includes a separate combustion gas supply 29 provided for pre-chamber 15. With the assistance of separate combustion gas supply 29, it is possible to admit combustion gas into pre-chamber 15 in addition to the air-/combustion gas mixture that is admitted into main combustion chamber 13, thus increasing the volumetric efficiency of cylinder 3. It is, in particular, possible to overblow pre-chamber 15, whereby additional combustion gas is admitted into main combustion chamber 13 via firing channels 19, thereby enriching the air-/combustion gas mixture that is admitted into main combustion chamber 13 via inlet valve 21. In this manner, it is possible to further increase the volumetric efficiency of cylinder 3, whereby in particular a cylinder 3 that has a poor volumetric efficiency can be improved and can be adapted to cylinders that from the outset have a better volumetric efficiency. But even if gas engine 1 only includes one single cylinder 3, it is possible for pre-chamber 15 with the assistance of the separate combustion gas supply 29 to improve the volumetric efficiency of cylinder 3.

(10) Separate combustion gas supply 29 includes a fluid path 35, through which combustion gas can be admitted into pre-chamber 15. For this purpose, fluid path 35 can be connected via a fluid connection 31 with a storage container 33, such as a tank. No device for mixing the combustion gas with air is provided in fluid path 35, so that pure combustion gas is admitted to pre-chamber 15 via separate combustion gas supply 29.

(11) A valve 37 can be arranged in fluid path 35 for separate combustion gas supply 29 with the assistance of which a combustion gas volume that is admitted into pre-chamber 15 is adjustable. Valve 37 can be a force-controlled or an electromagnetic valve. Fluid path 35 can consist of fluid connection 31 and valve 37. It is thereby shown that combustion gas from storage tank 33 can be admitted to pre-chamber 15 via fluid path 35, consequently via fluid connection 31 and valve 37.

(12) In the design example of gas engine 1 illustrated in FIG. 1, the engine 1 features a pre-chamber spark plug 39. In this design, example pre-chamber 15 is designed as part of pre-chamber spark plug 39. It is, in particular, in the embodiment of a metal sleeve 41 that is provided on spark plug 39, wherein metal sleeve 41 is penetrated by firing channels 19. An electrode arrangement 43 for ignition of the combustible mixture is arranged in pre-chamber 15. Alternatively it is also possible that pre-chamber spark plug 39 is designed as a laser spark plug or as a Corona spark plug.

(13) As is further explained with reference to FIG. 2, gas engine 1 can include a plurality of cylinders 3, such as two cylinder banks each having a plurality of cylinders 3.

(14) A combustion gas volume admitted into pre-chamber 15 via separate combustion gas supply 29 can be adapted so that cylinder individual or cylinder bank individual volumetric efficiency deviations are compensated. It is, in particular, possible with the assistance of valve 37 to meter the combustion gas volume for pre-chamber 15 in order to increase the volumetric efficiency of cylinder 3. A mixture can hereby be produced in pre-chamber 15 that, compared to the mixture admitted into main combustion chamber 13, is more enriched with respect to stoichiometry. In particular, in order to keep pollutant emissions of the motor low, an as lean a mixture quality as possible in respect to stoichiometry is realized in main combustion chamber 13. A lambda value of approximately 1.7 can be set. Because of separate combustion gas supply 29, it is now possible to adjust a lambda value in the pre-chamber 15 in a range from the lower explosion limit to the upper explosion limit, such as at least 0.6 to a maximum of 1.2. On the one hand, the energy content in pre-chamber 15 is increasedin particular compared to an unflushed pre-chamber which is being supplied in a compression stroke of piston 9 with the mixture from main combustion chamber 13whereby the boosting effect of the ignition energy is increased; on the other hand, due to the already described effect of overblowing pre-chamber 15, the mixture that is present in main combustion chamber 13 is being enriched or, respectively, the volumetric efficiency of cylinder 3 is being improved.

(15) A controller 45 can be provided by which at least one parameter for a cylinder specific or cylinder bank specific volumetric efficiency can be captured. Valves 37 of pre-chambers 15 of various cylinders 3 are hereby controlled by controller 45 in such a manner that cylinder individual or cylinder bank individual volumetric efficiency deviations are adaptable through adjustment of the combustion gas volumes admitted into individual pre-chambers 15.

(16) In the illustrated embodiment, a cylinder pressure can be captured by controller 45 as a parameter. A cylinder pressure sensor 47 is arranged on cylinder 3 for this purpose, with which controller 45 is connected in order to capture the cylinder pressure in cylinder 3.

(17) Alternatively to the cylinder pressure that is captured with the assistance of cylinder pressure sensor 47, an exhaust gas temperature and/or nitrogen oxide emission can also be used as a parameter for control of valve 37. For this purpose, suitable sensors, shown as an exhaust gas temperature sensor 78 and a nitrogen oxide emission sensor 79, are provided in the region of cylinder 3 or, respectively exhaust, gas line 27 which are operatively connected with controller 45.

(18) Controller 45 can adjust an opening degree, an opening point of time and/or an opening duration of valve 37 or, respectively, of a plurality of valves 37 of various cylinders 3. In this manner, the combustion gas volume admitted into pre-chambers 15 can be varied. Control can occur hereby depending on the at least one parameter, in this case therefore depending on the cylinder pressure that is captured with the assistance of cylinder pressure sensor 47. To activate valve 37, controller 45 can be connected to valve 37 via a first operative connection 49.

(19) Pre-chamber spark plug 39 can also be controlled by controller 45, wherein controller 45 is connected with pre-chamber spark plug 39 for this purpose. Controller 45 can also be connected with inlet valve 21 via a second operative connection 51 and/or with outlet valve 25 via a third operative connection 53, so that these valves are also controllable through controller 45. It is, however, alternatively also possible that inlet valve 21 and/or outlet valve 25 are not force-controlled by controller 45, but instead, for example, through at least one cam shaft.

(20) Referring now to FIG. 2, an additional schematic illustration of the design example of gas engine 1 according to FIG. 1 is shown. Same and functionally same elements are identified with the same reference numbers, so that in this respect reference is made to the previous description. In FIG. 2 it is indicated purely schematically that gas engine 1 includes a plurality of cylinders 3. Gas engine 1 can moreover be designed as a V-engine that includes two rows of cylinders 3 positioned parallel to each other that are arranged in the form of a V relative to each other. The design example of gas engine 1 includes thus two cylinder banks, whereby in FIG. 2 only one cylinder bank 55 is illustrated schematically for the sake of clarity.

(21) FIG. 2 illustrates a turbo charger 57 which intakes an air-/combustion gas mixture 67 via a gas mixer 59, and compresses same.

(22) On the one hand, combustion air 61 and on the other hand combustion gas 63, which can be from storage container 33, is admitted to gas mixer 59, wherein combustion gas 63 is mixed with combustion air 61 in gas mixer 59, wherein the mixture is supplied to a compressor 65 of turbo charger 57 and is compressed by same. From there, mixture 67 reaches mixture line 23 which is herein equipped with a distribution structure through which the mixture is delivered to various cylinders 3 of cylinder bank 55.

(23) Via exhaust gas linesof which herein only one is identified with reference number 27 for the sake of claritythat are assigned to individual cylinders 3, exhaust gas comes into an exhaust gas manifold 69 which is connected fluidically via outlet valves 25 with cylinders 3; wherein exhaust gas manifold 69 is moreover fluidically connected with turbo charger 57, so that exhaust gas can flow from cylinders 3 via exhaust gas manifold 69 to turbo charger 57.

(24) The exhaust gas flows hereby through a turbine 71 of turbo charger 57 and propels it to a rotational movement. Turbine 71 is operatively connected via a shaft 73 with compressor 65, so that compressor 65 is propelled by turbine 71 via shaft 73 into a rotational movement

(25) In the illustrated embodimentviewed in flow direction of the exhaust gasa first catalytic converter 75 is arranged before turbo charger 57 and after cylinders 3 which, in this case, is arranged centrally before the inlet into turbo charger 57. Therefore, all of the exhaust gas flowing from cylinders 3 must pass catalytic converter 75 in order to reach turbo charger 57.

(26) In addition, a second catalytic converter 77 can be provided respectively after certain cylinders 3, whereby here only one of the second catalytic converters that are identified with reference number 77 is shown for the sake of clarity. It is possible, in particular, to cylinder individually vary the size of second catalytic converters 77. At the same time, it is clear that in FIG. 2 no catalytic converter 77 is provided on one of the cylinders 3. Central catalytic converter 77 is provided in particular so that no exhaust gas flow arises that has not passed through a catalytic converter.

(27) In the illustrated embodiment, therefore, several comparatively small catalytic converters 75, 77 are arranged in the region of exhaust gas manifold 69, wherein the arrangement of catalytic converters 75, 77 is selected so that the exhaust gas counter pressure of catalytic converters 75, 77 acting upon individual cylinders 3 or individual cylinder banks 55 results in that differences in the volumetric efficiency between individual cylinders 3 or cylinder banks 55 are compensated. Second catalytic converters 77 can be arranged in compensators which serve to dampen vibrations and to compensate for thermal expansion of exhaust gas manifold 69.

(28) This may, however, also be the case alternatively or in addition for first catalytic converter 75.

(29) Gas engine 1 can be operated with natural gas, biogas, a special gas or another gas, such as gas containing methane. Pure combustion gasin particular not an air-/combustion gas mixturecan be admitted via separate combustion gas supply 29 into pre-chamber 15.

(30) Gas engine 1 can be designed as a piston engine. In one embodiment, gas engine 1 serves to drive heavy land or water vehicles, for example mining vehicles, trains, whereby gas engine 1 is utilized in a locomotive or a rail car, or ships. Also, utilization of gas engine 1 for driving military vehicles, for example tanks, is possible. One embodiment of gas engine 1 is also used in stationary operation, for example for stationary energy supply for emergency power supply, continuous load operation or peak load operation, whereby gas engine 1 can drive a generator. Gas engine 1 is also suitable for use in an engine based cogenerator for stationary energy production. Also, stationary use of gas engine 1 to drive auxiliary units, for example fire pumps on drilling rigs, is possible. Moreover, utilization of gas engine 1 in the field of transportation of fossil raw materials and in particular fuels, for example oil and/or gas, is possible. Utilization of gas engine 1 in the industrial field or in the construction field, for example in construction machinery, is also possible. Gas engine 1 can be in the embodiment of a diesel engine, a gasoline engine, a gas engine for operation with natural gas, biogas, special gas or another suitable gas.

(31) Overall, a controlled overblowing of pre-chamber 15 is possible, whereby, if required, an increased combustion gas volume or respectively any combustion gas at all is metered into pre-chambers 15. This compensates cylinder specific deviations in the cylinder charge or, respectively, in the volumetric efficiency of cylinders 3. In particular, on cylinders 3 having a poor volumetric efficiency it is possible to increase the indicated efficiency of these cylinders through targeted enrichment of the mixture, in other words by adjusting a low lambda value. This has a positive effect on the mechanical overall efficiency of the engine. Cylinder individual or cylinder bank individual volumetric efficiency deviations can be compensated in such a manner that all cylinders are operated closer to a knocking limit.

(32) Overall it is possible with the assistance of mixture charged gas engine 1 or, respectively, with the described method to efficiently compensate cylinder individual or cylinder bank individual volumetric efficiency deviations and to thereby realize a more favorable performance of the engine.

(33) While this invention has been described with respect to at least one embodiment, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.