Internal-combustion engines – Multiple cylinder – Cylinders in-line
Reexamination Certificate
1999-04-02
2001-04-03
McMahon, Marguerite (Department: 3747)
Internal-combustion engines
Multiple cylinder
Cylinders in-line
C123S197300, C123S197400
Reexamination Certificate
active
06209496
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a reciprocating combustion engine comprising at least one cylinder in which a piston is reciprocatingly moveable and is connected by connecting rods to two parallel crank shafts that are connected by a toothing to one another such that they rotate in opposite directions.
Such a reciprocating internal combustion engine is known from German Patent Application 32 38 030 A1 and is described in the following with the aid of FIG.
8
. The reciprocating internal combustion engine is shown in an exemplary fashion as a spark ignition engine (otto engine) and has a cylinder
2
in which a piston
4
is working. The intake manifold
6
opens into the cylinder head
8
whereby in the mouth of the intake manifold at the cylinder head an intake valve
10
is provided. Furthermore, an exhaust manifold
12
is represented having a mouth at the cylinder head
8
in which the exhaust valve
14
is positioned.
In the intake manifold a throttle
16
is positioned, and downstream of the throttle
16
the fuel injector
18
is positioned. In the cylinder head spark plugs
20
are also positioned which extend into the combustion chamber.
A control device
22
is provided for controlling the spark plugs
20
and the fuel injector
18
whereby the input terminals of the control device are supplied in a manner known to a person skilled in the art by signals of different sensors for detecting the operating parameters of the internal combustion engine. The control device
22
then computes control signals for controlling injection and ignition.
In the crankcase
28
of the internal combustion engine two parallel crankshafts
30
and
32
are arranged which, relative to the axis of piston movement, are symmetrically arranged and are connected to one another by a meshing toothing (gear wheel)
34
so that they rotate in opposite directions.
Each one of the crankshafts
30
and
32
is connected by a connecting rod
36
,
38
to the piston
4
. The underside of the piston has spaced apart bearings
40
and
42
for supporting the connecting rods
36
and
38
, whereby the bearings
40
and
42
are spaced in the direction of spacing between the crankshafts
30
and
32
. As an alternative, the connecting rods can also be coaxially connected to the piston.
A special feature of the double crankshaft drive will be explained with the aid of FIG.
9
. The ordinate of the diagram shows the piston stroke H and the abscissa shows the angle of rotation of the crankshafts, relative to the bottom dead center UT of the piston. This means that between the two bottom that center positions a 360° rotation of the crankshaft takes place.
The dashed line shows the behavior of a conventional crankshaft drive in which the crankshaft is arranged centrally below the piston. The top dead center OT
1
of the piston in the conventional crankshaft drive is located exactly between the two bottom UT positions, i.e., at 180° angle of rotation of the crankshaft.
For the double crankshaft drive according to
FIG. 8
, in which the two crankshafts
30
and
32
are symmetrically offset relative to the center of the piston
4
, a curve shown in solid lines results. Starting from the UT position of the piston the crankshafts
30
and
32
rotate in opposite directions whereby the left crankshaft of
FIG. 1
rotates in the clockwise direction by less that 180° until the top dead center OT
2
of the piston has been reached and, subsequently, upon rotation by more than 180°, will reach again the bottom dead center UT. In a four stroke method, the intake stroke and the working stroke, in comparison to conventional crankshaft drive have available, an increased angular range and thus a longer time period so that filling and load conversion are improved.
One special feature of the double crankshaft drive is that the connecting rods
36
and
38
are rotated outwardly from the axis of the piston. The wall of the cylinder
2
can thus be elongated in the direction toward the crankshaft drive only to a limited amount. This accordingly limits the stroke length that can be realized for the provided constructive space and thus determines the constructive height of the engine.
It is an object of the present invention to embody a reciprocating internal combustion engine of the aforementioned kind such that for a given constructive height an increased stroke is realized.
SUMMARY OF THE INVENTION
According to a first solution, the connecting rods are curved toward the cylinder axis.
In a preferred embodiment, the connecting eyes for the connecting rods are spaced at the piston in the direction of spacing of the crankshafts. The facing sides of the connecting rods are slanted such the connecting rods can move relative to one another with overlap.
In another solution of the inventive object, the piston is provided with two connecting rod bearings which are spaced in the direction of spacing between the crankshafts, and each connecting rod is respectively connected to the connecting rod bearing remote from the respective crankshaft to which the connecting rod is fastened.
In yet another embodiment of the invention, the piston is provided with a substantially disc-shaped piston bottom having a central area with a projection having an end portion for receiving the connecting rods whereby between the piston bottom and the end portion a constriction is provided.
In yet another embodiment of the invention the piston is in cross-section of a curved shape whereby the concave side faces the combustion chamber and the convex side is designed for receiving the connecting rods.
The inventive solutions presented above are especially useful when the ratio of connecting rod length to crankshaft spacing to crankshaft stroke is 2.2-1.8 to 1.85-1.55 to 1.1-0.9.
The invention thus provides a reciprocating internal combustion engine that, in comparison to conventional reciprocating combustion engines having only a single crankshaft, has a higher rpm level and thus an increased output. Relative to its output the inventive engine has a reduced weight and is of a small size. The invention allows, in particular, to embody reciprocating internal combustion engines to have a minimal constructive height for a given displacement.
REFERENCES:
patent: 2392921 (1946-01-01), Holman
patent: 4505239 (1985-03-01), Deland
patent: 4690113 (1987-09-01), Deland
patent: 5595147 (1997-01-01), Feuling
patent: 5682844 (1997-11-01), Wittner
patent: 5873333 (1999-02-01), Wittner
patent: 32 38 030 (1983-04-01), None
patent: 8902028 (1989-03-01), None
McMahon Marguerite
Robert W. Becker & Associates
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