DE2214400C3 - Mixture-compressing spark-ignited internal combustion engine with charge stratification - Google Patents

Description

The invention relates to a mixture-compressing, spark-ignited internal combustion engine with charge stratification for operation with liquid or gaseous fuels, preferably hydrocarbons, in which the combustion chamber is subdivided into zvA sub-chambers with a narrowed connecting duct, the first sub-chamber being a ^{K adjacent to a spark plug; >} Fuel-air mixture inlet valve and an outlet valve is assigned to the second compartment

For many years, proposals have become known that use charge stratification in the gasoline engine in order to also provide this engine with a larger air over- "" ' to be able to operate shot.

It is known that this has various advantages can be achieved such. B .:

(a) lower process temperatures (especially at part load), since the total air ratio can be higher than the ⁴ 'stoichiometric, whereby the heat losses to the combustion chamber wall are reduced;

(b) increased thermal and chemical efficiency, since on the one hand the thermodynamic process ^{comes closer to that with pure air V)} with a higher total air ratio, on the other hand the combustion is carried out with excess air;

(c) as a result of the excess air and the associated lower combustion temperatures, less or ^M no significant dissociation occurs in comparison with a gasoline engine;

(d) the pumping losses of the motor are lower, since there is little or no throttling of the Intake air is required;

(e) as a result of charge stratification, that is, the ^fuel-h "richer mixture at the spark plug, the

Engine operated as a multi-fuel engine;

(f) by using excess air and the associated lowering of the process temperature, the exhaust gas emissions can be ^{reduced to the M} low values required today.

In addition, there are mixture-compressing, alien

Ignited internal combustion engines with charge stratification become known, in which the combustion chamber is in two subspaces is divided, which are connected by a narrowed connecting channel.

For this purpose, US Pat. No. 33 04922 should be mentioned in particular, which describes the initially outlined Genus occupied and in which a stratified charge engine with the spark plug provided swirl chamber in which a Fuel injection valve or an additional mixture inlet valve is attached, it is described there is already mixture enrichment in the area of the spark plug.

Furthermore, a working method for four-stroke engines has become known from German patent specification 4,47,347, in which the air with the fuel in the Suction line is mixed and the mixture is stored in the cylinder between two air cushions, this "Stratification of the charge" is achieved by the fact that the Fuel is injected into the suction line by a pump. This should allow the passage of Non-atomized fuel after crankshaft bearings and oiling of the candles are avoided. In contrast to today's "stratified charge engine", a fuel-air mixture that is as lean as possible is deliberately generated at the spark plug

The present invention is based on the object of the charge stratification, i.e. mixture enrichment at the spark plug independent of the load and engine speed. This task is performed in the internal combustion engine of the generic type solved according to the invention in that the combustion chamber has only one inlet valve and that the fuel supply to the first subchamber only through introduction into the intake line takes place immediately upstream of the inlet valve and this occurs at the earliest with the beginning of the second Half of the intake cycle begins

A) The combustion chamber is therefore divided into two sub-chambers subdivided which are located at the inlet or outlet valve. These sub-spaces, referred to as "inlet part" and "outlet part", are constricted by a Cross-section connected. The spark plug is located in the intake part. The combustion process can therefore be described as a "two-chamber procedure".

B) The mixture formation, in particular the mixture enrichment at the spark plug, is carried out in the under A) described combustion chamber through the fuel supply in front of the inlet valve in the second half of the Intake stroke reached

These mentioned features of the invention also result in a clear differentiation from that The subject of DE-AS 10 91 378, in which a rule procedure for a four-stroke internal combustion engine is described in which at least part of the amount of fuel is injected directly into an auxiliary combustion chamber, the injection and the compression stroke are always divided over time, which is appropriate to the load

In particular, with an expedient embodiment of the invention according to the subclaims the following sequence of mixture formation and combustion:

By means of a low-pressure injection or metering, the fuel is injected into the shortly before the inlet valve Introduced air intake duct. Therefore a charge

stratification, that is, rich mixture, in the "inlet part" only to be achieved when the fuel supply begins in the second half of the suction cycle at the earliest and approximately ends at the end of the suction cycle,

Since the "outlet part" has its filling over the "Inlet part" is only for this time interval Fuel supply, filling of the outlet part with a lean mixture or pure air is possible.

On the other hand, the fuel supply ensures a filling of the in the second half of the intake stroke Inlet part with rich mixture.

If a certain lean, homogeneous mixture is to be achieved in the outlet part, then the fuel supply can be extended by a certain amount beyond the end of the intake cycle. Through this will a certain amount of fuel accumulated in front of the inlet valve, which in the subsequent intake stroke a lean forms a homogeneous mixture in the outlet part

The start of the fuel supply in the second half of the suction cycle depends on the load on the Engine. With increasing load, the start of the fuel supply is postponed voi * if z. Legs constant amount of fuel is supplied per unit of time. The mixture preparation takes place at the object of the invention during almost the entire compression stroke in the inlet part and can be achieved by preheating the chamber floor in the inlet part (e.g. through exhaust gas bypass).

The design of the combustion chamber described at the beginning now largely prevents the compression stroke the mixture exchange between the inlet part and the outlet part, thus receives the desired charge stratification upright

In the drawing, the subject matter of the invention is shown or explained using an exemplary embodiment
in Fig. 1 shows a section through an internal combustion engine with features according to the invention,

F i g. la a top view of the combustion chamber

Fig. 2 go valve lift and injection law emerged.

ι = In Fig. 1, the combustion chamber designed according to the invention in the cylinder head 1 with the spark plug 6 is in the Inlet part 2 can be seen.

Fig. La shows the plan view of the combustion chamber with the inlet part 2 and the outlet part 3. With 4 and 5 , " denotes the inlet and outlet valve

A Krafteioffzufuhrvorrichtung in the intake manifold is with 7 denoted by 8 is the channel Rn -a possible Preheating of the chamber floor in the inlet section

j5 In Fig. 2 fuel supply periods are dependent graphically represented by the cure position

For this purpose 2 sheets of drawings

Claims (3)

Patent claims: 1. mixture-compressing spark-ignition internal combustion engine with charge stratification for _r operation with liquid or gaseous fuels' preferably hydrocarbons, is wherein the combustion chamber into two partial chambers divided constricted connecting channel, wherein the first partial chamber a spark plug adjacent the fuel-air mixture inlet valve and the second '"partial space is assigned an outlet valve, characterized in that the combustion chamber has only one inlet valve (4) and that the fuel supply immediately ^ll upstream of the first compartment (2) only by the introduction into the intake pipe takes place the inlet valve (4), and this at the earliest with Beginning of the second half of the intake cycle begins 2. Internal combustion engine according to claim 1, characterized in that the fuel is introduced by ² " low-pressure injection. 3. Internal combustion engine according to claim 1 or 2, characterized in that the fuel supply is ended approximately at the end of the intake stroke