Method and apparatus for operating a spark-ignited reciprocating-piston internal combustion engine

Claim 3

A method according to claim 1 including adjusting the intake valve lift curve in the retarded crank angle direction together with the exhaust valve lift curve.

Claim 4

A method according to claim 1 including producing the swirling flow of exhaust gas by an exhaust duct configuration.

Claim 5

A method according to claim 3 wherein the exhaust duct has a flow cross-section controlled by the exhaust valve which is recessed relative to the combustion chamber and wherein the recirculated exhaust gas has the swirling flow imposed upon it by a chamfer which extends over only part of the circumference of the flow cross-section.

Claim 6

A method according to claim 4 wherein at least two exhaust valves and at least two inlet valves provide communication with the combustion chamber and both exhaust valve lift curves are shifted in parallel with and together with the intake valve lift curve in the direction of a retarded crank angle.

Claim 7

A method according to claim 5 wherein the flow cross-sections for the exhaust valves have chamfers which differ in direction to produce two swirling flows rotating in directions opposite to one another about parallel axes.

Claim 8

A method according to claim 1 wherein at least two exhaust valves provide communication with the combustion chamber and wherein, when one of the exhaust-valve lift curves is adjusted in the direction of a retarded crank angle for the recirculation of exhaust gas, at least one other exhaust valve is rendered inactive.

Claim 9

A method according to claim 7 including producing the swirling flow of exhaust gas by an exhaust duct configuration in only the exhaust gas flowing in through the exhaust valve which has not been deactivated.

Claim 10

A method according to claim 1 wherein a single intake valve communicates with the combustion chamber and including imposing a swirling flow upon the fresh gas.

Claim 11

A method according to claim 1 wherein a plurality of intake valves communicate with the combustion chamber and including imposing a flow motion on the fresh gas which is a tumbling flow rotating about an axis transverse to the cylinder axis.

Claim 12

A method according to claim 10 including adjusting the intensity of the tumbling flow.

Claim 13

Apparatus for reducing fuel consumption and exhaust gas emissions in a spark-ignited reciprocating-piston internal combustion engine having a combustion chamber comprising: intake and exhaust valves actuated periodically by at least one camshaft wherein the valve lift curves for the intake and exhaust valves have a valve overlap phase in which exhaust gas flows back out of the exhaust duct into the combustion chamber; an arrangement for changing the position of the exhaust valve lift curve relative to the crank angle; the exhaust duct having at least one flow cross-section in a combustion chamber land which is recessed relative to the combustion chamber; a chamfer extending along one side of the flow cross-section in the combustion chamber land with a direction, defined by the extent of the chamfer, which is tangential to an axis extending in the direction of motion of the reciprocating piston.

Claim 14

Apparatus for reducing fuel consumption and exhaust gas emissions in a spark-ignited reciprocating-piston internal combustion engine having a combustion chamber comprising: intake and exhaust valves actuated periodically by at least one camshaft wherein the valve lift curves for the intake and exhaust valves have a valve overlap phase in which exhaust gas flows back out of the exhaust duct into the combustion chamber; an arrangement for changing the position of the exhaust valve lift curve relative to the crank angle; the exhaust duct having at least one flow cross-section in a combustion chamber land which is recessed relative to the combustion chamber; a chamfer extending along one side of the flow cross-section in the combustion chamber land with a direction, defined by the extent of the chamfer, which is tangential to an axis extending in the direction of motion of the reciprocating piston.

Claim 15

Apparatus according to claim 12 wherein the arrangement for changing the position of the exhaust valve lift curve relative to the crank angle provides a synchronous change of the intake valve lift curve relative to the crank angle.

Claim 16

Apparatus according to claim 12 wherein the combustion chamber communicates with a plurality of exhaust valves each having a chamfer extending along one side of a corresponding flow section and wherein the directions defined by the extent of the chamfers for the flow sections differ from each other.

Claim 17

Apparatus according to claim 12 wherein a plurality of exhaust valves communicates with the combustion chamber and including a deactivation arrangement for decoupling at least one of the exhaust valves from the periodic drive by the camshaft.

Claim 18

Apparatus according to claim 12 wherein a plurality of exhaust valves communicates with the combustion chamber and at least one of the exhaust valves is driven by a camshaft cam having a flank which closes that valve prematurely relative to another exhaust valve.