Multi-cylinder internal combustion engine

Details Multi-cylinder internal combustion engine Multi-cylinder internal combustion engine

1996-06-21

1997-04-22

McMahon, Marguerite

Internal-combustion engines

Multiple cylinder

Cylinders radiating

123 9227, 123 9217, F01L 104, F01L 126, F01L 1344

Patent

active

056221436

DESCRIPTION:

BRIEF SUMMARY
FIELD OF THE INVENTION

The invention relates to a multi-cylinder internal combustion engine whose cylinders are arranged in two rows, the cylinders of the first row being staggered relative to the cylinders of the second row.


BACKGROUND OF THE INVENTION

Inlet and outlet valve rows alternate in a state-of-the-art internal combustion engine, that is, in the direction transverse to the longitudinal, a row of outlet valves is followed by a row of inlet valves, a row of outlet valves again, and lastly a row of inlet valves. Two camshafts are provided, an inlet camshaft and an outlet camshaft, which are positioned above the outer valve rows, and each of which actuates the valves of the outer valve row and the valves of the nonadjacent inner valve row. The valves of the inner valve rows are inevitably inclined at a steep angle to the longitudinal axes of the pertinent cylinders, this resulting in an unfavorable shape for the combustion chamber. Moreover, since the length of the inlet and outlet channels of the two cylinder rows varies, there is no certainty that the same admission and combustion conditions are present in all cylinders.
In order to prevent these unfavorable conditions, DE-A 38 31 333 discloses the mounting of inlet valve rows on both sides and near the plane of symmetry extending between the cylinder rows, but the outlet valve rows on the outside of the inlet valves, and provision of a common inlet camshaft for the two inlet valve rows in the plane of symmetry between cylinder rows and provision of an outlet camshaft for each outlet valve row.
As a result, all cylinders have combustion chambers, as well as inlet and outlet valves, of identical design, so that uniform admission and an identical combustion process for all cylinders are ensured. It has been found, however, that cylinder-selective fuel injection, essential for good mixture preparation, cannot be achieved with this internal combustion engine. In addition, intense heating of the intake mixture and the resulting admission loss are unavoidable. Lastly, this design cannot be used for an internal combustion engine with more than two inlet valves, since there is no room on the inlet camshaft common to all the inlet valves for more than two cams per cylinder. Because of these cramped space conditions, the inlet valves can be actuated only by tappets, not by rocker arms.


SUMMARY OF THE INVENTION

An object of the invention is the development of a generic internal combustion engine in which the combustion chambers and the inlet and outlet valves of all cylinders may also be of identical design, but in which cylinder-selective fuel injection may be provided and heating of the mixture admitted kept low without any problem, and, lastly, in which more than two inlet valves may be provided per cylinder.
In the present invention, Since the inlet valve rows are mounted externally to the outlet valve rows, the inlet channels provided may extend obliquely inward from the outside.
This presents the option of providing an injection valve which injects into the appropriate inlet valve or valves. In that the inlet channels are positioned on the outside, heating of the mixture admitted is prevented or, at any rate, reduced. External positioning of the inlet valve rows yields the additional option of providing long inlet channels with little space required, so that torque is increased in the lower engine speed range. Lastly, since each inlet camshaft actuates the inlet valves of only one cylinder row, more than two cams per cylinder may be mounted on each inlet camshaft, so that, for example, an internal combustion engine with three inlet valves per cylinder can be developed without difficulty. Moreover, in the proposed arrangement of the inlet camshafts there is enough space for actuating the inlet valves even by way of rocker arms. This is a consideration of particular importance, in that the possibility is created of mounting a variable valve control unit, for example as is claimed in DE-A 42 05 230. The present invention also offers the possibility

REFERENCES:
patent: 4674452 (1987-06-01), Asanomi
patent: 4787342 (1988-11-01), Matsumori et al.
patent: 4953525 (1990-09-01), Sakurai et al.
patent: 5205248 (1993-04-01), Hara et al.
patent: 5533586 (1996-09-01), Koishikawa et al.

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