DE2751993C2 - Mixture-intake internal combustion engine with squish gaps - Google Patents

Description

The invention relates to a mixture-intake internal combustion engine having the features of the preambles of patent claims 1 and 5 respectively.

Such an internal combustion engine is described in DE-OS 15 26 338. At the upper turning point of the piston there is still a relatively large combustion chamber with the disadvantage of relatively high fuel consumption. GB-PS 5 52 758 describes an internal combustion engine combustion chamber with a roughly circular cross-section, which is formed by a corresponding profiling of the top of the piston or the cylinder end wall. The profiling is also designed in such a way that a deflection squish gap is created via a deflection nose, which together with an opposite squish gap forms a rotational mixture flow in the combustion chamber.

The older patent application P 27 41 121.8-13 describes a similar mixture-intake internal combustion engine, in which a rotary flow is also formed in the combustion chamber with the help of a squish gap with a deflection nose and an opposite squish gap. Here, however, the surface of the piston is not flat, but has a trough-shaped profile.

Starting from a mixture-intake internal combustion engine with the features of the preambles of patent claims 1 and 5, the invention is based on the object of designing it in such a way that, in particular, a noticeable reduction in consumption is achieved, combined with an improvement in engine performance and an improvement in exhaust gas values.

The characterising features of patent claims 1 and 5 respectively serve to solve this problem.

Preferred embodiments of the invention are specified in subclaims 2, 3 and 4 respectively.

The features of patent claims 1 and 5 therefore result in the specified increase in compression, due to a relatively flat, small-volume combustion chamber. While maintaining normal valve sizes, an elongated combustion chamber cross-section is achieved. With such a high compression, the desired low exhaust emissions are possible because the squish flows are guided past the underside of the valve or the piston by the specified measures. The increase in compression also results in the desired reduction in consumption and increase in performance.

The invention is explained in more detail below using exemplary embodiments.

It shows:

Fig. 1 is a longitudinal section through the upper part of a piston-cylinder arrangement of an internal combustion engine according to the invention in a first embodiment;

Fig. 2 is a longitudinal section corresponding to Fig. 1 in a modified embodiment;

Fig. 3 shows schematically a plan view of the situation of Fig. 1 or Fig. 2;

Fig. 4 is a longitudinal section corresponding to Fig. 1 in a further modified embodiment.

A piston 2 runs in a cylinder 1 (see Fig. 1-3). In a cylinder head 3 there is an inlet valve 4 and an exhaust valve 17. A combustion chamber 5 is formed between the valves and the area in between in the cylinder head as the upper wall and the piston surface as the lower wall. A side wall 6 forms a cylinder head surface 6 . The other side wall of the combustion chamber 5 is formed by a deflection nose 11 or 14. The side walls 6 and deflection noses 11, 14 lie close below the surface of the valves, so that the smallest possible combustion chamber is produced for this combustion chamber shape.

A lower edge 7 of the cylinder forms with an upper edge 8 of the piston a right squish gap 26 in the region of the top dead center of the piston.

A lower inclined surface 9 of the cylinder head 3 forms with an upper inclined surface 10 of the piston 2 a left deflection gap 25 according to Fig. 1.

In the embodiment according to Fig. 2, the deflection gap is formed by straight surfaces 9 and 18 and inclined surfaces 12 and 13 of the cylinder head and the piston, respectively.

The internal combustion engine works as follows:

The fuel-air mixture is sucked into the cylinder 1 via the open intake valve 4. During the compression process, the mixture is pressed into the combustion chamber 5 by the piston to the right and left of the combustion chamber in the upper area of the piston travel by a squeezing effect. While the right-hand flow runs along the surface of the piston 2 in the direction of arrow 16 in the lower part of the combustion chamber, the left-hand flow flows along the lower edge of the valves in the direction of arrow 15 into the upper part of the combustion chamber. The lower flow is diverted at the deflection nose 11 and the upper flow is diverted by the combustion chamber side wall 6. Both flows in the combustion chamber thus receive a rotation in the wall area of the combustion chamber.

Fig. 1 is a bowl combustion chamber with obliquely arranged valves. In the drawing, the piston is located shortly before top dead center

Fig. 2 is a bowl combustion chamber with vertically arranged valves. The left-hand deflection gap can also be designed as shown in Fig. 1, ie with an inclined surface without a kink. However, the drawing shows that the deflection gap initially runs straight between surfaces 9 and 18 and then bends upwards between surfaces 12 and 13. It is advantageous if the gap widens slightly towards the outlet towards the deflection nose 14 so that the resistance to the mixture flowing out of the gap into the combustion chamber is reduced. The nose must not form a large gap, otherwise larger amounts of mixture than necessary will remain, which will lead to poorer combustion and greater HC formation.

Fig. 4 shows an embodiment in which the combustion chamber 5 is located in the piston 2. From the right-hand deflection gap 26, the mixture is pressed into the flow in the direction of arrow 16 below the valve 4 in the upper part of the combustion chamber 5 and deflected at a deflection nose 19. From a left-hand squeeze gap 24 , the mixture is guided downwards in the direction of arrow 15 through the deflection nose 19 and the corresponding design of the piston 2 opposite the deflection nose 19. It then flows into the lower part of the combustion chamber up to the side wall 6 , where the flow is deflected by the right-hand combustion chamber wall in the piston.

The deflection lug 19 is located here on the cylinder head 3 .

• 1. Durch die vollkommene Homogenisierung des Gemisches verbunden mit dem Ausströmen von fetten oder mageren Zonen im Gemisch entsteht eine ganz gleichmäßige Verbrennung mit höherer Klopfgrenze. Die Verdichtung kann erhöht werden und zwar von 1 : 9,5 auf 1 : 11 bei Superkraftstoff - entsprechend einen Punkt niedriger bei Normalbenzin; dies bringt eine Senkung des Verbrauchs verbunden mit einer Leistungssteigerung.
• 2. Die Erhöhung der Verdichtung und die Homogenisierung des Gemisches erlauben einen einwandfreien Fahrbetrieb im Bereich von Lambda 1,3-1,4. Ohne die Durchwirbelung und Verdichtungserhöhung ist dieser Fahrbetrieb nur bis Lambda 1,2 möglich. Bei Lambda 1,2 liegt die NO-Bildung viermal höher als bei Lamda 1,35. Die durch rotierende Durchwirbelung mögliche Verdichtungserhöhung ist also notwendig, um die NO-Werte so weit senken zu können, wie es der Gesetzgeber verlangt.
• 3. Der Betrieb mit höherer Verdichtung mit Rotationswirbelkammer bringt die Voraussetzung für einen einwandfreien Fahrbetrieb bei Magergemischen, wodurch nicht nur der Verbrauch weiter gesenkt wird, sondern auch die CO-Anteile im Abgas so niedrig werden, wie es der Gesetzgeber verlangt.

The rotational turbulence of the mixture achieved in this way brings the following advantages, among others:

• 1. The complete homogenization of the mixture combined with the elimination of rich or lean zones in the mixture results in a completely uniform combustion with a higher knock limit. The compression can be increased from 1:9.5 to 1:11 for premium fuel - correspondingly one point lower for regular gasoline; this reduces consumption combined with an increase in performance.
• 2. Increasing the compression and homogenizing the mixture allow for trouble-free driving in the range of lambda 1.3-1.4. Without the turbulence and increase in compression, this driving is only possible up to lambda 1.2. At lambda 1.2, the NO formation is four times higher than at lambda 1.35. The increase in compression made possible by rotating turbulence is therefore necessary in order to be able to reduce the NO values as far as required by law.
• 3. Operation with higher compression with a rotating swirl chamber creates the conditions for flawless driving with lean mixtures, which not only further reduces consumption, but also ensures that the CO content in the exhaust gas is as low as required by law.

In the European test, type I (ECE), the following values were measured: °=c:90&udf54;&udf53;vu10&udf54;&udf53;vz8&udf54;&udf53;vu10&udf54;

Consumption was reduced by about 10% and the power of the test car with 1.6 liter engine was increased from 110 hp to 124 hp.

The 1.6 liter stratified charge engine had 68 hp. This is a comparison to other exhaust solutions, which are also expensive.

Claims (5)

1. Mixture-intake internal combustion engine with flat, oppositely arranged pairs of squish gaps between flat sections of the cylinder head surface and the piston surface at top dead center, with a trough-shaped combustion chamber formed at top dead center, the upper wall of which is formed by the valves and the cylinder head surface lying between the valves and the lower wall of which is limited by a part of the piston surface, with a rotational flow in the combustion chamber, the axis of rotation of which is transverse to the cylinder axis, characterized in that the combustion chamber volume is dimensioned for compression ratios increased by about 20%, that the piston surface is provided with a deflection nose ( 11, 14 ) which forms a deflection squish gap ( 25 ) with an inclined section ( 12 ) of the side wall of the cylinder head ( 3 ), that the deflection squish gap ( 25 ) is connected to one of the two opposite squish gaps ( 26 ), that its squish flow allows the mixture to flow past the lower edge of the valves ( 4 ), while the opposite squish gap ( 26 ) allows the mixture to flow along the flat surface of the piston ( 2 ) to the deflection nose ( 11, 14 ). 2. Internal combustion engine according to claim 1, characterized in that the piston ( 2 ) is provided with an inclined surface ( 10 ) and this forms one of the squish gaps ( 24, 26 ) with a corresponding inclined surface ( 9 ) on the cylinder head. 3. Internal combustion engine according to claim 1 or 2, characterized in that the inlet and outlet valves ( 4 ) are arranged at an angle of at least 120° to one another with respect to their valve plates. 4. Internal combustion engine according to one of claims 1-3, characterized in that the deflection nose ( 11, 14 ) of the piston ( 2 ) at its top dead center protrudes from the cylinder head surface ( 12 ) only by a small gap and that the gap runs without widening or with a small widening towards the combustion chamber. 5. Mixture-intake internal combustion engine with flat, opposite squish gaps between flat sections of the cylinder head surface and the piston surface at top dead center, with a trough-shaped combustion chamber formed at top dead center, the upper wall of which is formed by the valves and the cylinder head surface lying between the valves and the lower wall of which is delimited by a part of the piston surface, with a rotational flow in the combustion chamber, the axis of rotation of which is transverse to the cylinder axis, characterized in that the combustion chamber volume is dimensioned for compression ratios increased by approximately 20%, that a deflection nose ( 19 ) is provided on a section of the side wall of the cylinder head ( 3 ), which forms a deflection squish gap ( 21 ) with the piston surface, that the deflection squish gap ( 21 ) is connected to one of the two opposite squish gaps ( 26 ), that its squish flow pushes the mixture along the flat surface of the piston ( 2 ) flow, while the opposite squish gap ( 26 ) allows the mixture to flow past the lower edge of the valves ( 4 ) to the deflection nose ( 19 ).