Crankcase ventilation with exhaust gas

Abstract

Internal combustion engine, comprising: - at least one cylinder-piston unit (2) having a piston, - a crankshaft arranged rotatably in a crankcase (3), wherein the piston of the cylinder-piston unit (2) is mechanically connected to the crankshaft, preferably via a connecting rod, - an exhaust system (4) for discharging an exhaust gas from the at least one cylinder-piston unit (2) after combustion, wherein a crankcase ventilation system (5) is provided having a supply line (6) which is fluidically coupled to the exhaust system (4), such that an exhaust gas is passed from the exhaust system (4) via the supply line (6) of the crankcase ventilation system (5) into the crankcase (3) of the internal combustion engine (1).

Description

[0001] Crankcase ventilation with exhaust gas

[0002] The present invention relates to an internal combustion engine according to the preamble of claim 1 and method for operating an internal combustion engine .

[0003] Internal combustion engines known by the state of the art comprise :

[0004] - at least one cylinder-piston unit having a piston,

[0005] - an intake system for providing the cylinder-piston unit an airfuel-mixture and / or air for combustion,

[0006] - a crankshaft arranged rotatably in a crankcase , wherein the piston of the cylinder-piston unit is mechanically connected to the crankshaft , preferably via a connecting rod, and

[0007] - an exhaust system for discharging an exhaust gas from the at least one cylinder-piston unit after combustion .

[0008] In operation of an internal combustion engine the at least one cylinder-piston unit - forming a main combustion chamber - is provided by an air- fuel mixture during an intake stroke . Therefore , the air- fuel mixture can be supplied via the intake system to the at least one cylinder-piston unit .

[0009] During a subsequent compression stroke the air- fuel mixture is compressed by the piston in preparation for ignition .

[0010] After the power stroke - wherein the compressed air- fuel mixture is ignited and combusted - the exhaust gases build during combustion are expel though the exhaust system from the cylinderpiston unit and the process begins one more by the intake stroke .

[0011] Internal combustion engines designed to be operated according to this method are also known as four-stroke engines . During the compression stroke the piston is moved inside the cylinder to decrease the volume of the air- fuel-mixture for compression of the air- fuel-mixture , wherein the si ze or volume of the main combustion chamber is reduced .

[0012] The piston is therefore sealed with respect to an inner surface of cylinder to prevent a leakage of the air- fuel mixture from the main combustion chamber and allow an ef fective compression .

[0013] For sealing between the piston and the inner wall of the cylinder it is commonly known to use piston rings .

[0014] But in fact , it is also known, that such a sealing of the piston is never 100 per cent leak-proof , wherein a small share of airfuel mixture passes through leaks between the piston and the cylinder into the crankcase of the internal combustion engine .

[0015] This amount of air- fuel mixture passing into the crankcase is in almost all cases so small that it does not noticeably af fect the combustion process .

[0016] But - especially at stationary internal combustion engines having a high piston displacement - a risk is present that this air- fuel mixture present in the crankcase is ignited or combusted, wherein severe damage of the internal combustion engine can occur and there is a large risk of inj ury for an operator standing near the internal combustion engine .

[0017] Therefore , it is known in the state of the art to remove such ignitable and combustible gases and gas-mixtures from the crankcase using crankcase ventilation systems , wherein the crankcase is simply ventilated by air . Such systems have been used very ef fective with internal combustion engines combusting common fuels such as methane , propane and so on .

[0018] Nowadays internal combustion engines routinely also have to be able to deal with carbon dioxide neutral fuels such as e . g . hydrogen . The use of hydrogen and carbon dioxide neutral fuels has become more and more important to reduce emissions and to improve the environmental aspect of an internal combustion engine .

[0019] As such fuels may comprise a much higher inflammability and ignitability crankcases have to be ventilated much more intensely, wherein even an active ventilation using fans has to be provided to minimi ze the risk of an ignition or combustion of an air- fuel mixture inside the crankcase .

[0020] Such intricate ventilation systems require a large ef fort for production and lots of energy to operate , wherein the overall ef ficiency of the internal combustion engine is reduced and the ef forts to provide such a system are high .

[0021] The obj ect of the present invention is therefore to provide an internal combustion engine as well as a method for operating an internal combustion engine which at least partly improves upon the mentioned negative ef fects compared to the prior art and / or reduces the risks of combustions inside a crankcase and / or improves the overall ef ficiency and economic aspect of an internal combustion engines having a crankcase ventilation systems and / or reduce ef forts which are related with crankcase ventilation systems , in particular to provide a simpler crankcase ventilation system .

[0022] This obj ect is achieved with an internal combustion engine with the features of claim 1 as well as a method for operating an internal combustion engine with the features of claim 12 . According to the invention an internal combustion engine is provided, comprising :

[0023] - at least one cylinder-piston unit having a piston,

[0024] - a crankshaft arranged rotatably in a crankcase , wherein the piston of the cylinder-piston unit is mechanically connected to the crankshaft , preferably via a connecting rod,

[0025] - an exhaust system for discharging an exhaust gas from the at least one cylinder-piston unit after combustion, wherein a crankcase ventilation system is provided having a supply line which is fluidically coupled to the exhaust system, such that an exhaust gas is passed from the exhaust system via the supply line of the crankcase ventilation system into the crankcase of the internal combustion engine .

[0026] By use of a crankcase ventilation system introducing exhaust gases ton the crankcase the flammability and / or ignitability of gases or gas-mixtures in the crankcase can be decreased, as the oxygen concentration can be decreased in the crankcase .

[0027] In other words , by supplying exhaust gases into the crankcase the oxygen amount in the crankcase can be reduced above a level of oxygen required for a combustion .

[0028] Therefore , instead of a flushing of the crankcase with a large amount of air to dilute the air- fuel mixture inside the crankcase using only an small amount of exhaust gas it is possible to inhibit the flammability or ignitibility o f an air- fuel mixture inside the crankcase more ef fectively .

[0029] In fact of that , active ventilation systems such as fans are not necessary any more . The small amount of exhaust gas needed can , e . g . , be supplied using the exhaust pressure of the exhaust system . In certain embodiments of the invention, it can however still be conceivable to use fans or the like for an active ventilation of the crankcase with exhaust gas .

[0030] Therefore , the invention provides a way to use already present resources of the internal combustion engine to reduces the risks of combustions inside a crankcase .

[0031] Thereby, the overall ef ficiency and economic aspect of internal combustion engines can be improved .

[0032] Also , the ef forts which are related to provide an internal combustion engine with a crankcase ventilation system can be reduced .

[0033] Already present internal combustion engines can be upgraded with at least one crankcase ventilation system according to the invention .

[0034] All measures and features described in connection with the prior art can also be taken in connection with the invention .

[0035] The invention can preferably be used in conj unction with a reciprocating piston engine , in particular driving a generator for creating electrical energy . Combinations of internal combustion engines driving a generator are known as gensets .

[0036] In particularly preferred embodiments the complete or at least the maj ority of the gas for ventilating the crankcase is an exhaust gas of the internal combustion engine . Preferably at least 70% and / or 80% and / or 100% of the ventilation gas is exhaust gas . In other embodiments smaller amounts of exhaust gas in the ventilation gas can be used to decrease the combustibility of the gases in the crankcase . Advantageous embodiments are defined in the dependent claims .

[0037] The internal combustion engine can be provided by an intake system for providing the at least piston-cylinder unit with an air- fuelmixture and / or air for combustion .

[0038] It can be provided that the exhaust system comprises at least one exhaust turbine , wherein the supply line of the crankcase ventilation system branches of f the exhaust system downstream of the at least one exhaust turbine .

[0039] The expressions "downstream" or "upstream" present in this document can be understood as expressions in relation to an intended material flow . E . g . , downstream in the exhaust system has to be understood as a point in the exhaust system being passed by the exhaust gas at a later moment in time during operation of the internal combustion engine .

[0040] It can be provided that the at least one exhaust turbine is part of a turbocharger being mechanically coupled to a compressor arranged at the intake system .

[0041] It can be provided that the internal combustion engine comprises an exhaust gas recirculation (EGR) system, wherein an exhaust gas recirculation duct is fluidically connected to the exhaust system and the intake system and is provided to branch of f at least a part of the exhaust gas of the exhaust system and feed this exhaust gas into the intake system .

[0042] It can be provided that the supply line of the crankcase ventilation system branches of f the exhaust gas recirculation duct . The exhaust system - preferably the exhaust gas recirculation system - can be provided by at least one heat exchanger for cooling the exhaust gas , wherein the supply line of the crankcase ventilation system branches of f downstream of the at least one heat exchanger .

[0043] Furthermore , it can be provided that the exhaust system - preferably the exhaust gas recirculation system - comprises at least one condensate separator, wherein the supply line of the crankcase ventilation system branches of f downstream of the at least one condensate separator .

[0044] It can be provided that the heat exchanger for cooling the exhaust gas and the condensate separator are combined in one component part or be provided by separate components .

[0045] The supply line of the crankcase ventilation system can be provided by at least one mass and / or volume flow control device , preferably a gas valve and / or an ori fice, for controlling a mass and / or volume flow of exhaust gas .

[0046] It can be provided that the crankcase ventilation system comprises a discharge line fluidically coupled to the crankcase , through which the exhaust gas after passing the crankcase carrying particles , droplets , and / or other gases can be discharged from the crankcase .

[0047] The discharge line can be provided by at least one blow-by filter for separating particles , droplets , and / or other gases from the discharged gas of the crankcase .

[0048] It can be provided that the discharge line is fluidically coupled to the intake system, preferably upstream of the compressor, wherein the discharged gas of the crankcase is at least partially supplied via the intake system into the at least one cylinderpiston unit .

[0049] The internal combustion engine can be designed as a stationary reciprocating gas engine operated by hydrogen, preferably driving a mechanically coupled generator for providing electrical energy to a power grid .

[0050] Furthermore , protection is sought for a method for operating an internal combustion engine , preferably an internal combustion engine according to the invention, comprising combusting in at least one cylinder-piston unit of the internal combustion engine an air- fuel-mixture - preferably comprising hydrogen -, characteri zed by using exhaust gases resulting from a combustion process at least partially for ventilating the crankcase of the internal combustion engine .

[0051] It can be provided that the method further comprises supplying the exhaust gas after passing the crankcase - preferably after being separated from particles , droplets , and / or other gases - into the cylinder-piston unit as additive for the combustion process .

[0052] Further details and advantages of the invention are apparent from the accompanying figures and the following description of the drawings . The figures show :

[0053] Fig . 1 a fist embodiment of an internal combustion engine according to the invention, and

[0054] Fig . 2 a second embodiment of an internal combustion engine according to the invention . Fig . 1 illustrates a first embodiment of an internal combustion engine 1 according to the invention .

[0055] This internal combustion engine 1 comprises six cylinder-piston units 2 providing combustion chambers in which an air- fuel mixture is combusted .

[0056] This invention is , of course, not restricted to a single or six cylinder-piston units 2 used in the Figures serves only as an example . The invention can be used on an internal combustion engine 1 for one or more cylinder-piston units 2 .

[0057] The air- fuel mixture supplied can be mixed by a gas mixer (not illustrated in Fig . 1 ) upstream of the compressor 9 , wherein a fuel or a fuel mixture - e . g . , provided by a hydrogen supply grid - can be mixed with air and passed to the compressor 9 .

[0058] Alternatively, it can also be provided that the air- fuel mixture is provided in the cylinder-piston units 2 by mixing a separately supplied fuel - e . g . , a fuel supplied by a port inj ection valve directly into the cylinder-piston units 2 - and an air supplied via the intake system 10 inside the combustion chambers (wherein the combustion chambers are provided by the cylinder-piston units 2 ) .

[0059] In this speci fic embodiment of Fig . 1 the air for forming the airfuel mixture is supplied via the intake system 10 and the fuel - preferably hydrogen - is supplied via port inj ection valves provided for each cylinder-piston unit 2 (not illustrated) .

[0060] The air is supplied to the cylinder-piston units 2 through a compressor 9 of a turbocharger 8 , wherein the air can be cooled after compression by the compressor 9 in an intercooler 17 . The air compressed by the compressor 9 is succeed via the air filter 23 from the environment of the internal combustion engine 1 .

[0061] The compressor 9 of the turbocharger 8 is driven by a mechanically connected exhaust turbine 7 , which is arranged in the exhaust system 4 and driven by exhaust gasses resulting from the combustion inside the piston-cylinder units 2 .

[0062] The intercooler 17 and the compressor 11 can be bypassed by means of an intake bypass line 18 with a compressor bypass valve 19 , wherein a boost pressure can be adj usted by this compressor bypass valve 19 and with that boost pressure the piston-cylinder units 2 can be filled .

[0063] By changing the boost pressure , it is possible to vary the filling of piston-cylinder units 2 .

[0064] Furthermore , the intake system 10 comprises a throttle valve 22 , wherein an air mass supplied to the piston-cylinder units 2 can be controlled by the opening degree of the throttle valve 22 .

[0065] To avoid back fires inside the intake system 10 flame arrestors 24 are provided .

[0066] An exhaust system 4 for discharging an exhaust gas from the cylinder-piston units 2 after combustion is provided being connected to each cylinder-piston unit 2 .

[0067] In addition, the turbocharger 8 has an exhaust turbine 7 being arranged at the exhaust system 4 .

[0068] The turbocharger 8 can be bypassed by an exhaust bypass line 20 along with the turbine bypass valve 21 . By means of this turbine bypass valve 21 , an exhaust backpressure can be set which acts on the combustion chambers of the pistoncylinder units 2 .

[0069] Furthermore , the internal combustion engine 1 comprises an exhaust gas recirculation system 11 , wherein an exhaust gas recirculation duct 11 is fluidically connected to the exhaust system 4 and the intake system 10 and is provided to branch of f a part of the exhaust gas of the exhaust system 4 and feed this exhaust gas into the intake system 10 .

[0070] The exhaust gas recirculation duct 11 branches of f the downstream of the exhaust turbine 7 and the exhaust bypass line 20 of the exhaust system 4 .

[0071] The exhaust gas recirculation system 11 comprises a heat exchanger 13 for cooling the exhaust gas . Furthermore , the heat exchanger 13 is provide by a condensate separator 25 , wherein condensate build during cooling down the exhaust gas by the heat exchanger 13 can be led out from the system .

[0072] By use of the exhaust gas recirculation valve 26 a mass of exhaust gas gassed into the intake system 10 can be controlled and therefore an exhaust gas recirculation rate can be adj usted .

[0073] The piston of the piston-cylinder units 2 is mechanically connected via connecting rods with a crankshaft ( for reasons of clarity not shown) , wherein the crankshaft is ratably arranged inside the crankcase 3 .

[0074] For ventilation of the crankcase 3 - to evacuate air- fuel-mixture passed into the crankcase -a crankcase ventilation system 5 is provided . The crankcase ventilation system 5 comprises a supply line 6 which is fluidically coupled to the exhaust system 4 such that an exhaust gas is passed from the exhaust system 4 via the supply line 6 of the crankcase ventilation system 4 into the crankcase 3 of the internal combustion system 1 .

[0075] In particular, the supply line 6 of the crankcase ventilation system 5 branches of f the exhaust gas recirculation duct 12 downstream the exhaust turbine 7 .

[0076] The supply line 6 of the crankcase ventilation system 4 comprises at least one mass and / or volume flow control device , namely an ori fice 14 , for controlling a mass and / or volume flow of exhaust gas into the crankcase 3 .

[0077] After passing the crankcase 3 the exhaust gas - carrying particles , droplets , and / or other gases - can be discharged from the crankcase 3 via a discharge line 15 .

[0078] The discharge line 15 is fluidically coupled to the intake system 10 upstream of the compressor 9 , wherein the discharged gas of the crankcase 3 are supplied via the intake system 10 into the cylinder-piston units 2 .

[0079] Furthermore , the discharge line 15 comprises a blow-by filter 16 for separating particles , droplets , and / or other gases from the discharged gas of the crankcase 3 before passing the discharged gas into the intake system 10 .

[0080] Fig . 2 discloses a second embodiment of an internal combustion engine 1 according to the invention, wherein in contrast to the first embodiment the supply line 6 branches of f the exhaust system 4 downstream of the compressor and upstream of the exhaust gas recirculation system 12 .

[0081] Therefore , as the supply line 6 branches of f the exhaust system 4 upstream of the exhaust gas recirculation system 12 , the crankcase ventilation system 5 comprises at the supply line 6 a separate heat exchanger 13 for cooling the exhaust gas , wherein the heat exchanger 13 comprises a condensate separator 25 combined in one component part with the heat exchanger 25 .

[0082] The remaining characteristics essentially correspond with the characteristics disclosed by the first embodiment shown by Fig . 1 .

[0083] List of used reference signs :

[0084] 1 internal combustion engine

[0085] 2 cylinder-piston unit

[0086] 3 crankcase

[0087] 4 exhaust system

[0088] 5 crankcase ventilation system

[0089] 6 supply line

[0090] 7 exhaust turbine

[0091] 8 turbocharger

[0092] 9 compressor

[0093] 10 intake system

[0094] 11 exhaust gas recirculation system

[0095] 12 exhaust gas recirculation duct

[0096] 13 heat exchanger

[0097] 14 ori fice

[0098] 15 discharge line

[0099] 16 blow-by filter

[0100] 17 intercooler

[0101] 18 intake bypass line

[0102] 19 compressor bypass valve

[0103] 20 exhaust bypass line

[0104] 21 turbine bypass valve

[0105] 22 throttle valve

[0106] 23 air filter

[0107] 24 flame attestor

[0108] 25 condensate separator

[0109] 26 exhaust gas recirculation valve

Claims

Claims :

1. Internal combustion engine, comprising:- at least one cylinder-piston unit (2) having a piston,- a crankshaft arranged rotatably in a crankcase (3) , wherein the piston of the cylinder-piston unit (2) is mechanically connected to the crankshaft, preferably via a connecting rod,- an exhaust system (4) for discharging an exhaust gas from the at least one cylinder-piston unit (2) after combustion, characterized in that a crankcase ventilation system (5) is provided having a supply line (6) which is fluidically coupled to the exhaust system (4) , such that an exhaust gas is passed from the exhaust system (4) via the supply line (6) of the crankcase ventilation system (5) into the crankcase (3) of the internal combustion engine (1) .

2. Internal combustion engine according to claim 1, wherein the exhaust system (4) comprises at least one exhaust turbine (7) , wherein the supply line (6) of the crankcase ventilation system (5) branches off the exhaust system (4) downstream of the at least one exhaust turbine (7) .

3. Internal combustion engine according to claim 2, wherein the at least one exhaust turbine (7) is part of a turbocharger (8) being mechanically coupled to a compressor (9) arranged at the intake system (10) .

4. Internal combustion engine according to at least one of the preceding claims, wherein the internal combustion engine (1) comprises an exhaust gas recirculation system (11) , wherein an exhaust gas recirculation duct (12) is fluidically connected to the exhaust system (4) and the intake system (10) and is provided to branch off at least a part of the exhaust gas ofthe exhaust system (4) and feed this exhaust gas into the intake system (10) .

5. Internal combustion engine according to claim 4, wherein the supply line (6) of the crankcase ventilation system (5) branches off the exhaust gas recirculation duct (12) .

6. Internal combustion engine according to at least one of the preceding claims, wherein the exhaust system (4) - preferably the exhaust gas recirculation system (11) - comprises at least one heat exchanger (13) for cooling the exhaust gas, wherein the supply line (6) of the crankcase ventilation system (5) branches off downstream of the at least one heat exchanger (13) .

7. Internal combustion engine according to at least one of the preceding claims, wherein the supply line (6) of the crankcase ventilation system (5) comprises at least one mass and / or volume flow control device, preferably a gas valve and / or an orifice (14) , for controlling a mass and / or volume flow of exhaust gas.

8. Internal combustion engine according to at least one of the preceding claims, wherein the crankcase ventilation system (5) comprises a discharge line (15) fluidically coupled to the crankcase (3) , through which the exhaust gas after passing the crankcase (3) carrying particles, droplets, and / or other gases can be discharged from the crankcase (3) .

9. Internal combustion engine according to claim 8, wherein the discharge line (15) comprises at least one blow-by filter (16) for separating particles, droplets, and / or other gases from the discharged gas of the crankcase (3) .

10. Internal combustion engine according to claim 8 or 9, wherein the discharge line (15) is fluidically coupled to the intakesystem (10) , preferably upstream of the compressor (9) , wherein the discharged gas of the crankcase (3) is at least partially supplied via the intake system (10) into the at least one cylinder-piston unit (2) .

11. Internal combustion engine according to at least one of the preceding claims, wherein the internal combustion engine (1) is a stationary reciprocating gas engine operated by hydrogen, preferably driving a mechanically coupled generator for providing electrical energy to a power grid.

12. Method for operating an internal combustion engine (1) , preferably an internal combustion engine (1) according to at least one of the preceding claims, comprising combusting in at least one cylinder-piston unit (2) of the internal combustion engine (1) an air-fuel-mixture - preferably comprising hydrogen -, characterized by using exhaust gases resulting from a combustion process at least partially for ventilating the crankcase (3) of the internal combustion engine (1) .

13. Method according to claim 12, wherein the method further comprises supplying the exhaust gas after passing the crankcase (3) - preferably after being separated from particles, droplets, and / or other gases - into the cylinder-piston unit(2) as additive for the combustion process.

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