DE2231254A1 - COMBUSTION ENGINE PROCESS FOR CHARGED MIXED INTAKE IN EXTERNAL IGNITION ENGINES TO REDUCE EXHAUST POLLUTANT EMISSIONS WITHOUT A LOSS OF PERFORMANCE AND INCREASE IN CONSUMPTION - Google Patents

Description

Dr.-Ing. Erhard MuIhILaeg
61 Darrnstadt-EbersLadt
Ostpreußenstrasse 19

Internal combustion engine method for supercharged Mixture-sucking spark-ignition internal combustion engines to reduce exhaust pollutant emissions without sacrificing performance and increasing fuel consumption and Piston internal combustion engine for carrying out the method

The invention relates to a two-stroke or four-stroke working, a mixture prepared from liquid light fuel (e.g. gasoline, alcohol) and air sucking in externally ignited internal combustion engine and has set itself the goal of this most widespread engine type by a new and specially coordinated combination of per se known individual measures der.Abgasurboauflad, the charge cooling and the measures for mixture depletion a decisive reduction of the 'emission of the limited exhaust gas pollutants carbon monoxide (CO), hydrocarbons (HC) and nitrogen oxides (NO) achieve zxi without that compared to the free-sucking normal operation with a fuel-enriched, rich, high-performance mixture (air ratio / L = approx. 0.85) or with a lean, fuel-efficient mixture containing excess air ( ? L = approx. 1.1 at full load), a deterioration in performance or consumption occurs, as is the case with the Case with the currently applied and planned measures to reduce exhaust gas pollutant emissions is the case with naturally aspirated engines, such as a two-bed catalytic converter system for nitrogen oxide reduction that works with a rich mixture and with controlled air injection that saves power and increases consumption.

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tion in the first bed and for the oxidation of the excess CO and HC as well as the ammonia (NH ₃ ) produced by side reactions in the downstream second bed or, as in the case of the controlled exhaust gas recirculation, which also requires a rich mixture for reasons of acceptable driving behavior and good burnout efficiency, to reduce the NO - Emission in combination with an additional thermal exhaust gas reactor and a controlled air injection or, finally, as with the technically not yet solved single-bed catalyst system for the simultaneous reduction of the emission of CO, HC and NO, which not only reduces performance and also increases consumption in one very narrow range around the stoichiometric composition of the mixture is required, but also on a practicable, extremely selectively working catalyst not yet found and on a complex control device for maintaining the A. -mixture with very narrow tolerances is instructed.

Compared to these futuristic and costly exhaust gas detoxification measures, which only take place in the exhaust system , so become effective after the engine combustion chamber, the exhaust gas decontamination process according to the invention is also effective Using the combination according to the invention is known per se and proven measures carried out, which without exception influence the gasoline engine combustion itself and in the sense that at the same time the emission of CO, HC and NO is decisively reduced, without the already To have to accept the disadvantages mentioned in terms of performance and consumption, but on the contrary in principle even make it possible to improve performance and consumption.

The aim according to the invention is achieved in detail in that by known per se, also in combination Applicable measures, such as generating a rotary motion or directed turbulent flow of the cylinder

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charge in the engine combustion chamber, appropriate arrangement of two spark plugs, extension of the spark duration, increase in ignition voltage (Hesselman ignition coil), protruding spark plug double electrodes, carburetor with variable air funnel (constant pressure carburetor), controlled mixture preheating, controlled hot cooling, fine atomization by means of thermal spray disintegration of the fuel Charge stratification in the spark plug area by means of appropriately directed semi-direct or direct fuel injection into the cylinder as well as by utilizing the centrifugal effects when the cylinder charge rotates violently around the axis of the combustion chamber in the piston and / or in the cylinder head, the mixture - with the exception of the very low nitrogen oxide emissions idling · and the lowest power range - can be emaciated to such a large extent in the entire operating range without misfiring and without an impermissible increase in CH emissions (e.g. / L = - 1.4) that the NO emissions are significantly reduced, 'and that according to a further feature of the invention at the same time for the purpose of at least compensation or better permissible overcompensation of the reduction in the mixture calorific value h caused by the mixture lean and thus the maximum output, a correspondingly coordinated charging is carried out by means of an exhaust gas turbocharger and that, according to a further feature of the invention, at the same time, in order to reduce the increase in nitrogen oxide formation caused by the temperature-increasing precompression in the exhaust gas turbocharger, a correspondingly controlled cooling of the fuel / air mixture supplied to the engine under excess pressure by means of a cooling air or a liquid cooling medium charged charge cooler or by means of a known injection of an expediently dosed amount of water is applied in such a way that this cooling is preferably carried out with the aid of known control systems.

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gen is intensified with increasing charge and thus increasing power, which is considered more desirable As a side effect, the internal combustion engine achieves a predetermined output with a lower thermal load (lower temperature of critical components of the engine) and also with less mechanical stress (lower peak pressure, lower friction) and with lower fuel consumption (lower wall and friction losses) than achieved without cooling the one under boost pressure Fuel / air mixture.

In a further embodiment of the method according to the invention, for the purpose of an even further reduction proposed for the formation of nitrogen oxides, an additional one known per se, with regard to a still sufficient one Driving behavior (acceleration capacity) controlled external or internal exhaust gas recirculation or exhaust gas Use restraint and the resulting loss of maximum performance over the entire speed range, if possible to compensate by a corresponding intensification of the exhaust gas turbocharging, whereby a Enlargement of the positive gas exchange work or, if necessary, a reduction in the negative gas exchange work fuel consumption can be reduced.

Finally, it is also proposed instead of exhaust gas recirculation or exhaust gas retention or parallel to it to apply a delayed ignition, whereby - as known especially by reducing the maximum combustion temperature, the formation of nitrogen oxides is considerably reduced can be and also via an increase in the exhaust gas temperature, in particular that which takes place in the exhaust system Post-oxidation of the hydrocarbons still contained in the exhaust gas is favored.

The loss of maximum power caused by the delayed ignition should, according to the invention, be achieved by an intensive

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reduction of exhaust gas turbocharging can be compensated, which at the same time also increases fuel consumption due to the delayed ignition again by increasing the positive gas exchange work or possibly reducing the negative gas exchange work can be reduced.

The inventive method, which is except for Reciprocating piston engines also in rotary piston internal combustion engines can be applied, is explained again below with reference to two exemplary examples.

In Fig. 1 is in a schematically simplified manner Basic method according to claim 1, in which, for the sake of simplicity, a r.och further Exhaust gas improvement - especially with regard to nitrogen oxide emissions - by adding exhaust gas recirculation or exhaust gas retention is dispensed with, but the one that can be achieved with little effort here Not shown later setting of the ignition point according to claim 3 is applied: The intake air initially passes through the air intake line after passing through a filter (not shown) la into the exhaust-gas-heated intake air preheating device via the exhaust gas bypass 20 2, depending on the pressure in the boost pressure line 10a with the aid of the boost pressure sender 9a and the exhaust gas heating control flap 19a as well as other not shown known control system parts to be heated, so especially with Idle and in the lower power range a rich mixture can be avoided and also the especially critical warm-up period overcome with a less enriched mixture than without intake air preheating can be.

In the warmed-up state, the intake air is preheated from a certain power in the lower range turned off in order to avoid unnecessarily high nitrogen oxide

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tion in the overlying one, with one that can no longer be neglected Avoid nitrogen oxide emission-afflicted performance range.

By preheating the intake air, the Operating states the fuel / air mixture preparation in the downstream suction carburetor 4a, to which the fuel is float-regulated via the fuel supply line 3a Way is supplied, improved, although only one carburetor in question to solve the problem comes, which by means of a variable air funnel (constant pressure carburetor) or circulating air, (ümluftvergaser) or other well-known Measures ensures the best possible atomization quality for this type of mixture formation device.

To improve the mixture preparation and thus with the Mixture leaning option contributes significantly to the fact that in the almost entire operating range from the exhaust gas-acted radial turbine 7 driven radial compressor 6 of the exhaust gas turbocharger group 8 for the purpose the compensation according to the invention or even moderate Overcompensation of the loss of maximum power caused by the leaning compresses the fuel / air mixture will. This can be caused by a temperature increase and turbulent flow processes as well as other, measures known from rotary atomizers are quasi-homogenized.

Of course, a pressure carburetor arranged after the centrifugal compressor 6 can also be used which the mixture preparation is improved in that Combustion air flows through it, which increases the temperature during the compression process in the centrifugal compressor has experienced.

Finally, for the implementation of the method, the requirement for a special is essential large mixture leaning possibility is still of great importance that an Otto engine is used which is operated from the outset with a comparatively lean mixture due to its combustion process can be.

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In the Otto Kub piston internal combustion engine shown in FIG 15a is, for example, the so-called Audi Kitteldruckmotor, in which the comparatively wide mixture leaning possibility primarily to the intensive one, which increases the burn-through speed and perhaps a certain peripheral stratification of the charge also resulted in the rotation of the cylinder charge by Due to the axis of the 'combustion chamber' arranged in the piston ' is, which with the help of a correspondingly shaped intake channel 14 (swirl channel) already during the intake stroke is generated in a known manner.

As can be seen from the diagram shown in FIG. 2 relating to full load, because of the with the Compression in the radial compressor 6 accompanying temperature increase of the mixture, which leads to a corresponding Increase in the maximum combustion temperature, which leads to the exemplary mixture leaning to / L = 1.4 achieved reduction in NO concentration partially reversed (see point B with point A). In order to greatly reduce this negative side effect of charging, another basic feature of the In the process, the pre-compressed mixture is cooled in the charge cooler 11a in such a way that in the power range which is essentially above the power range with activated intake air preheating, with increasing power and thus increasing pressure in the supercharger pressure line 10a, the cooling effect by enlarging the amount of liquid flowing into the charge cooler 11a via the coolant inlet 12a per unit of time Coolant by means of a correspondingly increasing opening of the arranged in the coolant drain and from the boost pressure sensor 9a influenced coolant amount control valve 13a is increased.

As can be seen from FIG. 2, for example, a reduction in the nitrogen oxide concentration from point is achieved as a result B to point C.

From the same figure it can also be seen how, by adding the exhaust gas recirculation, which is known per se

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a particularly extensive reduction in the nitrogen oxide concentration can be achieved. One then arrives at a concentration that is marked by the point D •. This is so low that the decisive nitrogen oxide emissions resulting as the product of the concentration and the amount of exhaust gas per unit of time were emitted despite the increase in the per unit of time as a result of the higher charge density compared to the free-aspirating engine with the same power and operated at / \ = 0.85 The amount of exhaust gas is considerably smaller. This increase in the charge density can be taken from the diagram shown in FIG .max. mean indicated pressure p ^ than is achieved with the high-performance mixture A = 0.85 operated naturally aspirated engine. To 1.20 on the basis of a charge cooling to 4O ⁰ C results in an increase in the charge density of * * = 1.8 kg / m ^3.

In Fig. 4, the more complex system for implementing the additional exhaust gas recirculation is schematically simplified working procedure shown. The exhaust gas recirculation is here in the sense of the task solution by means of an exhaust gas recirculation line 22 branching off from the turbine exhaust gas discharge line 18 and an in Electronically controlled exhaust gas recirculation regulating flap 23 controlled as a function of suitable operating parameters. To increase the nitrogen oxide-reducing effect of the exhaust gas recirculation, the recirculated V / ground exhaust gases in a known manner, for example by ribbing the exhaust gas recirculation line and additionally by exposure to airflow or cooling air. The recirculated exhaust gases can continue through known filters, such as cyclones, ceramic filters, steel v / olle with ceramic coating, can be cleaned. In the case of

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In the case of play, they open into the air intake line la upstream of the intake air throttle valve 5b and are then in the radial compressor 6 of the exhaust gas turbocharger group 8 together with the intake air on the at least to compensate for the process-typical ' extensive mixture leaning-related loss of power required boost pressure brought, with an advantageous intimate mixing of the recirculated exhaust gases with the combustion air takes place.

The again provided cooling of the charge takes place in a charge air cooler 11b which is now acted upon by cooling air 12e, whose cooling effect is carried out with the aid of a pulse-generating engine temperature sensor 9b, an electronic Control unit. 4c and an electronically controlled cooling air fan 13b depending on the Engine temperature assigned to engine power (e.g. cylinder head temperature) is regulated, advantageously also the ambient temperature and the warm-up included in the control process, which essentially includes the already specified rule law for the exhaust gas recirculation-free system according to FIG. 1 is the basis.

In the system according to FIG. 4, the preheating is also regulated in the exhaust-gas-heated intake air preheating device 2 electronically depending on the engine temperature with the help of the exhaust gas heating control flap 19b. The control law corresponds again essentially to that, as it is with the exhaust gas recirculation-free Plant according to Fig I has been listed, the advantages just mentioned occur again. In the example, an electronic gasoline injection known per se is injected into the intake manifold 10c Injection nozzle 4b is provided, its opening time with the aid of an electronic control unit 4c, to which the conventional main control variables labeled 4d (Speed, pressure and temperature in the Laded, return line 10c) and the correction variables (cold start and warm-up mixture setting etc.) can be entered.

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In an unconventional way, a thermal jet disintegration and thus a fine atomization is enforced when injecting the fuel, which promotes a lean mixture without side effects, the Fuel in which is under relatively high pressure

Fuel supply line 3b with the aid of a regulated, for example electrically heated, fuel preheating device 14b brought to such a high constant temperature that it is not yet in the thermally insulated fuel supply line 3b is vaporized, but only when injecting into the under much lower pressure standing charge air line 10c enters.

The system according to FIG. 4 also has a gasoline internal combustion engine underlying that because of their advanced combustion process and therefore because of their comparatively good slimming possibility for the implementation of the method is in turn predestined. It does not work with an orderly rotation of the cylinder charge around the combustion chamber axis, but it does by igniting a zv / corner correspondingly directed flow shortly before the onset of ignition with the help of very low pinch gaps and a so-called three-ball vortex pan combustion chamber also comparatively high burn rate achieved.

Finally, it should be noted that it is still within the scope of the invention Procedure is when the Otto engine is not through an exhaust gas turbocharger, but is charged by a mechanically driven charger, e.g. centrifugal compressor or Roots blower. This would have the advantage of a better acceleration behavior, but the disadvantage of the performance-sapping and consumption-increasing mechanical drive from the crankshaft.

The so-called Comprex process, which works with an exhaust gas pressure wave exchange machine, is also used for charging in question, with overall roughly the same consumption

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with respect to the exhaust gas turbocharging as advantage a better torque characteristic and, related to a better acceleration performance sov7ie the possibility of a incorporated exhaust gas recirculation has, on the other hand the disadvantage of a, however, v / enig Lo ^J ~ tung consuming mechanical drive and the gevzichtigeren disadvantage of a much larger volume of construction and increased cost price owns.

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Claims (3)

Dr.-Ing. Erhard Mühlberg Darmstadt-Eber Stadt Ostpreußenstrasse 19 Patent claims 1. / Method for two-stroke or four-stroke working, a 'prepared mixture of liquid light fuel and air sucking in externally ignited (Otto) internal combustion engine, characterized in that for the purpose of a decisive reduction in emissions of the exhaust gas pollutants carbon monoxide (CO), hydrocarbons (HC ) and nitrogen oxides (NO) ^v and. at the same time in order to avoid a loss of performance or an increase in consumption compared to the non-exhaust-gas improved and fuel-enriched (rich) high-performance mixture (e.g. air ratio / L = approx. 0.85) or with a lean, consumption-optimized mixture containing excess air (e.g. / L = approx. 1.1) operated naturally aspirated internal combustion engine through measures known per se, which can also be used in combination, the mixture - with the exception of idling, which has very low nitrogen oxide emissions anyway, and the lowest power range - in the entire operating range without misfiring and without an unacceptable increase in HC Emission can be emaciated to such an extent (eg / L- 1.4) that the NO emission is decisively reduced, and that according to a further feature of the invention at the same time for the purpose of at least compensation or, better still, permissible overcompensation of the the intensive lean mixture caused a considerable decrease tion of the lower mixture heating value h and thus reduction of the maximum output a correspondingly coordinated, known per se 309884/0031 charge is carried out by means of an exhaust gas turbocharger utilizing exhaust gas and that after a Another feature of the invention also at the same time for the purpose of at least reducing the temperature-increasing Pre-compression in the exhaust gas turbocharger caused a certain increase in nitrogen oxide formation a correspondingly controlled cooling of the fuel / air mixture supplied to the engine under excess pressure by means of a charge cooler which is known per se and which is acted upon with cooling air or a liquid coolant, or by means of an injection known per se an expediently dosed amount of water is applied in such a way that, with the aid of known control systems, the cooling effect preferably also occurs Increasing charge and thus increasing power is intensified, which is a beneficial side effect the internal combustion engine has a predetermined output with a lower thermal load (lower temperature of critical components of the engine) and also with less mechanical stress (lower peak pressure, lower friction) and with lower fuel consumption (lower Wall and friction losses) than without cooling the fuel / air mixture under boost pressure . 2. The method according to claim 1, characterized in that for the purpose of going even further " the reduction of nitrogen oxide formation in the engine is also known per se, with regard to a still sufficient driving behavior (acceleration ability) controlled external or internal exhaust gas recirculation or exhaust gas retention is applied and that the resulting loss of maximum performance is possible in the entire operating speed range by a corresponding intensification of the exhaust gas turbocharging. 3 0 98 84/00 3 1 Chen becomes _f whereby the fuel consumption can also be reduced by increasing the positive gas exchange work or possibly by reducing the negative gas exchange work. Method according to Claim 1 or 2, characterized in that, for the purpose of one more further reduction in the formation of nitrogen oxide in the engine, which does not inadmissibly impair driving behavior Delayed ignition is applied, which also causes an increase in the exhaust gas temperature in particular the post-oxidation occurring in the exhaust system the hydrocarbons still contained in the exhaust gas is favored, and that by the Delayed ignition leads to a loss of maximum output due to a corresponding intensification of the exhaust gas turbocharging is compensated, whereby the occurring as a result of the delayed ignition increase in fuel consumption again by increasing the positive gas exchange work or, if necessary, reducing it the negative gas exchange work can be reduced. 309884/0031 / Γ Read more