EP0916820A1 - Method of operating a petrol engine and petrol engine for using the method - Google Patents

Abstract

The operating process supplies a first part mass of gasoline to a cylinder cavity giving a compression ratio of over 12:1 and without ignition plug in an amount sufficiently low to avoid detonations. The second part mass of gasoline is introduced into the combustion chamber in the region of TDC in combination with exhaust products from the combustion of the first part mass, so that it burns with little ignition distortion. The engine has a fuel supply device (7) which can dose the two part masses of gasoline in a set timed sequence into the combustion cavity (5) of the cylinder (2).

Description

The present application relates to a method for Operation of a petrol engine according to the generic term of Claim 1 and a gasoline engine to carry out of the procedure.

Lately, the increasing traffic density of vehicles and machines with petrol engines has led to an increasing environmental pollution, and on the other hand, governments and institutions around the world are issuing a flood of regulations to reduce the consumption and pollutant emissions of petrol engines. With regard to gasoline engines, catalysts have been developed to reduce pollutant emissions, particularly nitrogen oxides, while the reduction in CO ₂ emissions has generally been brought about by lowering fuel consumption.

As z. The latest development was a vehicle with a Gasoline engine with direct injection to the public presented at the fuel with a relatively high Pressure of approximately 50 bar directly into the cylinder is injected, the air-gasoline ratio up to Can be 40: 1 and a relatively high for gasoline engines Compression of 12.5: 1 is used. This is at referred to this vehicle as the upper limit above which it comes knocking on an uncontrolled combustion indicates. According to the factory, this engine is used for Reduced consumption and increased performance.

In addition to the petrol engine, there is the self-igniter working diesel engine, which is a very high Compression ratio and no throttle bodies for Filling control and therefore with a large excess of air can work. From this it is known that, for. B. at comparable mileage essentially identical vehicle using the current one Gasoline engine that meets emissions standards emits about 40% more carbon dioxide than if it were with one also comply with the current emissions standards Diesel engine would be driven. It can be done in one urban driving cycle this difference over 60% be. But it is also known that the same Operating conditions a diesel engine more particles and soot generated as a gasoline engine.

From the literature, e.g. B. from automotive Taschenbuch, Bosch, 19th edition 1984, is also that So-called hybrid process known, the mixture in Area of the spark plug is enriched to such an extent that a safe ignition is guaranteed, the combustion in the Medium but in the case of a heavily emaciated mixture, that is to say diesel-like partial load consumption should take place.

Furthermore are from the above literature Multi-fuel engines known, some with very high Compression ratios of 25: 1 work, but with a fuel with very different qualities works as may be necessary in the military. Both However, engine shapes have not proven themselves in practice.

It is based on this known prior art Object of the present invention, a method for Operation of a gasoline engine and a device for Perform the procedure to specify the one Petrol engine emits significantly less carbon dioxide than conventional petrol engines, with or without Direct injection and significantly fewer particles and soot generated as a diesel engine under comparable Operating conditions. This task is done with the procedure according to independent claim 1 and the device solved according to independent claim 4. Of the task of using petrol is also solved to use lower octane numbers than usual. This Task and other tasks and training of the process are solved or defined in the dependent claims.

Figur 1 zeigt schematisch den zeitlichen Ablauf des Einbringens von Teilmengen Benzin pro Arbeitstakt einer Zylindereinheit, und

Figur 2 zeigt in einem Benzinmotor schematisch einige für den erfinderischen Verbrennungsablauf wesentliche Komponenten.

The invention is explained below with reference to a drawing of an embodiment.

Figure 1 shows schematically the timing of the introduction of partial quantities of gasoline per work cycle of a cylinder unit, and

Figure 2 schematically shows in a gasoline engine some components essential for the inventive combustion process.

Gasoline engines, also Otto engines according to their inventor have been known for over 100 years. All Gasoline engines usually have one cylinder unit at least one spark plug, which the mixture at best time ignites, because petrol, in Contrary to diesel fuel, a less ignitable Is fuel. So far it was not possible operate a gasoline engine as a diesel, d. H. without To use spark plugs, as is the case with the diesel engine because with a compression ratio of over 12.5: 1 start uncontrolled autoignition that leads to knocking lead that are no longer tolerable in an engine.

The present invention is based on the knowledge that it is possible by appropriate timing of the Introducing and compacting an operation of a Bring gasoline engine that works without spark plugs and usually no throttle bodies for Power regulation needed.

Are from the 50s, for example from the two Articles "Some Factors Affecting Precombustion Reactions in Engines "by M.W. Corzilius et al., SAE Transactions, vol 61, 1952, pages 386 to 401 and "Engine Knock as Influenced by Precombustion Reactions "by J.M. Mason and H.E. Hesselberg, SAE Transactions, volume 62, 1954, pages 141 to 150, studies known that served the emergence and eliminating knock on gasoline engines to examine closely. Summarizing these studies can be said that it was recognized that under certain operating conditions pre-oxidation processes run off without external ignition means, only by acting of temperature and pressure, to create a so-called cool flame, which leads to further compression Auto ignition of the charge or mixture can lead to with uncontrolled further course to annoying knocking leads. In particular, on page 148 of the second Article referred to where the formation of active tapping material and on page 141 of this article where the cool flame and the formation of aldehydes and peroxides is explained. This also applies to page 386 of the first cited article.

The main goal of the studies mentioned was to knock this eliminate, according to the knowledge at the time the admixture of lead additives brought the best result.

As will become apparent from the following description of the method according to the invention, it has surprisingly been found that the occurrence of pre-combustion reactions can be used to carry out a knock-free combustion process even without the use of spark plugs. In other words, this means that a process which is annoying and harmful for conventional gasoline engines is used to bring about a substantial reduction in CO ₂ and to simplify engine control.

In the description below is known as provided that with the term petrol a usually volatile mixture, which generally consists of quite a number various hydrocarbon compounds and u. a. can also contain alcohol. Here are also inferior petrol or petrol mixtures with lower octane numbers than, for example, at petrol pumps considered available, that is, fuels using much less effort in the refinery can be and that without unwanted combustion processes, such as B. knocking can be used. That means with In other words, a reduction in the octane requirement of the Gasoline engine also within the scope of the present invention is realized.

The gasoline engine in the context of the present invention is is generally about a reciprocating piston internal combustion engine at least one cylinder unit in a known manner Crankshaft, crankcase, connecting rod, piston, cylinder, Cylinder head, intake and exhaust elements and Has fuel supply and metering. in the further this machine is simplified as a petrol engine designated.

The present invention can be summarized as Combustion process can be called that composed of the use of gasoline like this is known on the one hand in so-called Otto engines and on the other hand, from the self-ignition of the mixture, like this is used in so-called diesel engines, whereby the combustion processes for both the Otto engine and the Diesel engine can be assumed to be known.

It is for the sake of simplicity from an operating range of the Gasoline engine assumed that the z. B. in passenger cars with about 80% of the most used operating area and approximately in the range of half the nominal engine speed Maximum power and about halfway here possible maximum mean pressure is.

In Figure 1, this is greatly simplified and schematically Introduction of two subsets, TM1 and TM2, one each predetermined per work cycle of a cylinder unit Total amount of petrol MG above the piston position or Crankshaft position - shown in degrees crankshaft.

The first area is the subset TM1, which in this case already in the cylinder chamber during the output stroke is introduced. The larger area is the representation the second and usually larger subset TM2, which in the Area of the top dead center position of the piston introduced becomes.

Preferably the first subset is the same Injector introduced, with which the second subset TM2 is to be introduced. To further an undesirable To prevent cylinder wall wetting with gasoline mist the first subset directly in during the compression cycle injected into the bowl of a bowl piston, this Procedure in Figure 1 with the surface 1 is shown, see also Figure 2.

The subset TM1 can be known Introductory means such. B. intake manifold injection, Direct injection or constant pressure carburetor in at least part of that for the intended work cycle the amount of air sucked in the cylinder unit and are at least partially mixed with this. This means in other words, that the first subset is targeted to the sucked in air quantity must be introduced and not the cylinder wall should reach because it is not used there. This means that the subset should be as compact as possible Part of the combustion chamber are introduced. Generally speaking the air volume introduced without throttling.

The process of introducing the first subset TM1 is completed at the latest when a second predetermined Partial quantity TM2 by means of injection means and in the same way as is known in diesel engines, e.g. B. also by means of "common rail", in the combustion chamber of the petrol engine or the Cylinder unit is introduced. This will help sufficient early introduction of the first subset - e.g. B. already during the intake stroke or at the beginning of the Compression cycle - during and especially in the second Half of the compression stroke of the cylinder unit Subset TM1 with air pre-oxidation processes imposed, as mentioned in the two above Literature examples are described.

This creates so-called pre-combustion reactions, which without external ignition means and only by the action of Temperature and pressure the emergence of a so-called cool Cause flame and with further compression to Can cause the charge or the mixture to self-ignite, being the first subset of the total per work cycle the intended amount of fuel is so small that no knocking damage harmful to the cylinder unit can occur, but numerous in the combustion chamber Pre-combustion and partial combustion molecules are created. This creates the necessary conditions for that the injected by high pressure injection agent and in Combustion chamber atomized second predetermined subset TM2 of the Gasoline at least almost without unwanted ignition delay, so without unwanted pressure peaks and associated knocking noises, soot and solid formation in the area the top dead center position of the piston burns. Appropriately, in the area of top dead center, in a range from 6 ° before to 10 ° after top dead center injected.

This is particularly the case if the Cylinder unit a swirl flow of the charge was generated. A compression ratio of> 12: 1, in particular a compression ratio of 14: 1 to 20: 1, preferably used from 16: 1 to 19: 1 and due to TM1 only a lean fuel-air mixture processed, its fuel-air ratio, that so-called F: A ratio, e.g. B. at maximum Mean pressure is <0.03, preferably <0.025 and against the The idle operating range of the petrol engine accordingly gets even smaller.

In Figure 2 is a schematically shown combustion chamber configuration shown in the compression cycle. In cylinder 2 moves a piston 3, the piston crown 4 a Combustion chamber trough 5, from a lower Dead center position UT in the direction of the top dead center position OT. He approaches the cylinder head 6, in which at least one injection nozzle 7 and preferably also one Glow plug such as a glow plug 8 is arranged or are. On the representation of piston rings, oil control rings, Piston pin etc. as well as cylinder head gasket, Screw connection, inlet and outlet valves, channels, Cooling ducts, etc. has been used to emphasize the Essentially waived.

The injection nozzle 7 is comparatively small Beam opening angle α and can be a hollow jet cone, if necessary also form a full jet cone or also be designed as a multi-jet cone.

The first part of the petrol is in the middle piston position TM1 partly as a film on the trough surface shown and designated 9. Another part of the TM1 is due to the temperatures of the trough wall and the compressed air evaporating and still one Another part of the TM1 already forms the one according to the invention desired combustion products and later ignition cores 10 and are indicated by dots.

In the area of the TDC position, the second subset TM2 injected and atomized and burned according to the now numerous existing ignition cores without annoying ignition delay.

The supports especially in cold starts Glow plug 8 the pre-oxidation process, especially then if it is provided that in cooperation of the Beam angle α and the position of the glow plug Small amount of the amount of petrol TM1 touches it.

In the operating areas below and above the previous one described operating range, the respective provided total volume of gasoline in different Way in the first and second and if necessary, for the Afterburning, planned third subset divided.

It is particularly useful and inexpensive if also the first subset of the gasoline with the same Injectors are used for the introduction of the second Subset are provided, but preferably more time upstream than is customary in diesel engines, whereby also the injector with lower thermal load is exposed and therefore less possible Coking is exposed. It can be for example around known two-spring nozzles or around electronically controlled nozzles that work right into the Range of over 1,000 bar injection pressure can work.

It can also prove to be useful, but not or high pressure injectors not yet suitable for petrol for diesel engines such as injection pumps, injection nozzles or in "common rail" systems and the like the gasoline in add a small amount of lubricating oil, e.g. B. in the ratio 1: 100 or less to prevent feeding on the moving Avoid sharing. It is also beneficial to do so be careful, especially when feeding the first subset separate from the injector, which is the second subset brings in that the second subset is at least as large is that this nozzle doesn't overheat at its mouth.

It is appropriate for cold starts, per cylinder unit a glow plug, e.g. B. glow plug to provide as they is known in diesel engines, this glow plug preferably also during the warm-up process and / or can remain partially heated in the partial load range.

If you use the temperature of the glow plug with suitable regulates electronic control means depending on the load, can also lower compression ratios of 12: 1 be used.

The method according to the invention also allows gasolines with lower octane numbers, d. H. also so-called use inferior petrol or petrol mixtures, the ratio of the first to the second subset then also depends on the type of gasoline mixture. Of the Gasoline engine according to this invention usually needs no throttle valve on the carburetor because of the power regulation only by changing the respective total quantity MG. The total amount of gasoline is the present gasoline engine quantity-controlled and not filling-controlled like this is the case with Otto engines. Because the described Combustion process is not knock limited, it is suitable also for supercharged petrol engines, e.g. B. with Turbochargers or with pressure wave superchargers.

Claims (9)

Method for operating a gasoline engine with at least one cylinder unit and means for insertion of gasoline in the cylinder space, characterized that in an operable without spark plugs and a Compression ratio of over 12: 1 engine a first predetermined subset (TM1) of gasoline each total predetermined per work cycle and cylinder unit Total amount (MG) of gasoline with a means of introduction in at least a part of for each per work cycle and Total amount of air drawn into the cylinder unit Compression space of the cylinder to form Pre-combustion products are introduced, the first Subset (TM1) is kept so small that no knocking arises and then at least a second predetermined subset (TM2) of gasoline with high pressure introduction means into the combustion chamber in the area of the upper one Dead center position of the cylinder piston is introduced, wherein it burns with little ignition delay. A method according to claim 1, characterized in that for the gasoline engine a compression ratio of 12: 1 to 20: 1, preferably from 14: 1 to 20: 1, in particular 16: 1 to 19: 1, is used. A method according to claim 1 or 2, characterized characterized in that the second subset (TM2) gasoline in the Range from 6 ° before to 10 ° after top dead center is injected. Gasoline engine to carry out the process according to a of claims 1 to 3, with at least one cylinder unit and petrol introduction means, characterized in that the no spark plugs and a compression ratio of at least 12: 1 engine petrol feeder (7) contains, which are formed, at least two Parts of petrol (TM1, TM2) dosed and in a certain chronological order in the compression or combustion chamber (5) of the cylinder (2). Gasoline engine according to claim 4, characterized in that the introduction means injection pumps, injection nozzles or Common rail systems include. Gasoline engine according to claim 4 or 5, characterized characterized that the introduction means two-spring nozzles or electronically controlled nozzles. Gasoline engine according to one of claims 4 to 6, characterized characterized in that one glow plug per cylinder unit, in particular glow plug (8) is provided. Gasoline engine according to claim 7, characterized in that means are available to control the temperature of the Control glow plug (8) depending on engine load. Gasoline engine according to one of claims 4 to 8, characterized characterized that it is quantity-controlled and none Has throttle valve on the carburetor.

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