Combustion space for a reciprocating piston internal combustion engine

A combustion space of a reciprocating piston internal combustion engine in which the combustion development of the internal combustion engine, as also the knock limit, is positively influenced by a defined configuration of the combustion space and arrangement of the ignition and injection devices, and more particularly in such a manner that the fuel necessary for the operation of the internal combustion engine can be characterized by a lower octane number.

BACKGROUND AND SUMMARY OF THE INVENTION 
The present invention relates to a combustion space for a reciprocating 
piston internal combustion engine which is provided between a cylinder 
head and a piston and is equipped with one or several ignition and 
injection devices, whereby the gas-exchange control in the combustion 
space takes place by two inlet valves and two exhaust valves of the 
cylinder head. 
A combustion space is disclosed in the U.S. Pat. No. 4,484,550 which is 
provided in the cylinder head and includes a spark plug arranged in the 
center longitudinal axis of the cylinder. Additionally, the cylinder head 
includes two inlet valves and two exhaust valves. 
It is the object of the present invention to favorably influence the 
combustion progress in the combustion space by geometric configuration 
measures as well as arrangement of the ignition and injection devices. 
The underlying problems are solved according to to the present invention in 
that the ignition device extends in a center longitudinal axis of the 
cylinder, the injection devices extend essentially at the same angle to 
the center longitudinal axis of the cylinder, the piston includes a 
spherically shaped recess on the side facing the cylinder head whose 
radius is located on the center longitudinal axis of the cylinder, and the 
piston is extended on the side facing the cylinder head up to a 
roof-shaped combustion space boundary of the cylinder head outside of the 
recess for the formation of a squeeze area. 
The principal advantages achieved with the present invention reside in that 
the progress of the flame-development phase and the heat release is 
improved by the arrangement of the ignition and injection devices as well 
as the configuration of the combustion space. In particular, it is assured 
that during the main combustion phase the flame expands uniformly in all 
directions, starting from the spark plug. It is additionally achieved with 
this construction that the knock limit of the internal combustion engine 
is such that the fuel required for the operation of the internal 
combustion engine can be characterized by a low octane number.

DETAILED DESCRIPTION OF THE DRAWINGS 
Referring now to the drawing wherein like reference numerals are used 
throughout the two views to designate like parts, of the multi-cylinder 
internal combustion engine generally designated by reference numeral 1, 
only one cylinder generally designated by reference numeral 2 is 
illustrated which is provided in a cylinder crankcase 3. The cylinder 
crankcase 3 combines on the side opposite the crank drive (not shown) a 
cylinder head 4 which includes two inlet valves 5 and 6 and two exhaust 
valves 7 and 8. The gas-exchange control in a combustion space 9 takes 
place by way of these valves which are actuated by one or two cam shafts 
(not shown); the combustion space 9 is provided between a piston 11 
installed into a bore 10 and the cylinder head 4. 
On the side of the cylinder head 4, the combustion space 9 includes a 
roof-shaped combustion space boundary 12 whereby the angular position A 
and B of the inlet and exhaust valves 4, 5, respectively, 6, 7, normally 
at right angle to the surface of the combustion space boundary, is defined 
by this combustion space boundary 12. An ignition device (spark plug) is 
designated by reference numeral 13 which extends in a center longitudinal 
axis C--C of the cylinder 2. Additionally, injection devices 14 and 15 are 
inserted into the cylinder head 4 which are each arranged between the 
inlet and the exhaust valves 5, 6, respectively, 7, 8, whereby they extend 
at a more inclined angle D and E than the inlet and exhaust valves. The 
injection valves 14 and 15--like the valves--, are arranged essentially 
under the same angle with respect to the center longitudinal axis C--C. 
The piston 11 is provided with a spherically shaped recess 16 which 
contributes to the formation of the combustion space 9 on the side of the 
piston. The size (the volume) of the recess is defined by the following 
relationship: 
EQU R=(0.25-0.45) D 
R is thereby the radius of the spherically shaped recess 16 and D the 
diameter of the piston 11 and/or of the bore 10 of the cylinder 2. 
It can be seen from FIG. 2 that the point of origin of the radius R lies 
approximately at the peak 20 of the roof-shaped combustion space boundary 
12. 
Outside of the recess 16, the piston 11 is extended close to the combustion 
space boundary 12 and forms a squeeze area 17 whereby its size amounts to 
at least 12% of the area of the Piston 11. Finally, the piston 11 is 
provided within the area of the injection devices 14 and 15 with recesses 
18 and 19. 
While I have shown and described only one embodiment in accordance with the 
present invention, it is understood that the same is not limited thereto 
but is susceptible of numerous changes and modifications as known to those 
skilled in the art, and I therefore do not wish to be limited to the 
details shown and described herein but intend to cover all such changes 
and modifications as are encompassed by the scope of the appended claims.