Lean-burn variable compression ratio engine

Claim 3

The method of claim 1 further including the step of reducing the valve overlap period from the first period to a second period.

Claim 4

The method of claim 2 wherein the second valve overlap period is less than 25°.

Claim 5

The method of claim 2 wherein the first valve overlap period is greater than 25°.

Claim 6

The method of claim 1 wherein the variable compression ratio provides a second compression ratio greater than 13, and the adjustable fuel to air equivalence ratio provides a second fuel to air equivalence ratio within a radius of 0.125 index units from a compression ratio of 16.0 and a fuel to air equivalence ratio of 0.75.

Claim 7

The method of claim 1 wherein the variable compression ratio provides a second compression ratio greater than 13, and the adjustable fuel to air equivalence ratio provides a second fuel to air equivalence ratio less than 0.85.

Claim 8

The method of claim 1 wherein the variable compression ratio provides a first compression ratio less than 12.5, and provides a second compression ratio greater than 13, wherein the engine has an efficiency greater than 38% at the second engine setting.

Claim 9

The method of claim 1 wherein the variable compression ratio provides a second maximum combustion charge density greater than the first combustion charge density, and the adjustable fuel to air equivalence ratio reduces the first brake mean effective pressure from a value greater than 750 kilo-pascals to a second value less than 750 kilo-pascals.

Claim 10

The method of claim 8 wherein the variable compression ratio provides a second maximum combustion charge density that is at least 1.15 times greater than the first maximum combustion charge density.

Claim 11

The method of claim 1 wherein the variable compression ratio provides a second compression ratio greater than 13, and the adjustable fuel to air equivalence ratio provides a second fuel to air equivalence ratio within a radius of 0.075 index units from a compression ratio of 16.0 and a fuel to air equivalence ratio of 0.75.

Claim 12

In an internal-combustion engine having at least one piston, a displacement volume, a combustion chamber volume, means for adjusting the compression ratio comprising an adjustment mechanism to vary the combustion chamber volume, an intake and exhaust valve overlap period, a bulk mixed gas to fuel ratio having an air-to-fuel ratio, means for adjusting the bulk mixed gas to fuel ratio, and a first engine setting having a first bulk mixed gas to fuel ratio and a first compression ratio, a method of operating the engine at an elevated compression ratio and at an elevated bulk mixed gas to fuel ratio, to improve the fuel efficiency of the engine while avoiding detonation and misfire, comprising the steps of: increasing the compression ratio above the knock limit of the first engine setting to extend the stable combustion limit, and increasing the bulk mixed gas to fuel ratio to extend the knock limit, and prevent engine knock.

Claim 13

In an internal-combustion engine having at least one piston, a displacement volume, a combustion chamber volume, means for adjusting the compression ratio comprising an adjustment mechanism to vary the combustion chamber volume, an intake and exhaust valve overlap period, a bulk mixed gas to fuel ratio having an air-to-fuel ratio, means for adjusting the bulk mixed gas to fuel ratio, and a first engine setting having a first bulk mixed gas to fuel ratio and a first compression ratio, a method of operating the engine at an elevated compression ratio and at an elevated bulk mixed gas to fuel ratio, to improve the fuel efficiency of the engine while avoiding detonation and misfire, comprising the steps of: increasing the compression ratio above the knock limit of the first engine setting to extend the stable combustion limit, and increasing the bulk mixed gas to fuel ratio to extend the knock limit, and prevent engine knock.

Claim 14

The method of claim 11 wherein the step of increasing the compression ratio above the knock limit and the step of increasing the bulk mixed gas to fuel ratio are performed concurrently to prevent engine knock and misfire.

Claim 15

The method of claim 11 wherein the compression ratio is increased from a first setting having a compression ratio value less than 12.5 to a second setting having a compression ratio value greater than 13.

Claim 16

The method of claim 13 wherein the bulk mixed gas to fuel ratio is increased from a first value less than 17.3 to a second value greater than 17.3.

Claim 17

The method of claim 14 wherein the second bulk mixed gas to fuel ratio is greater than 18.5.

Claim 18

The method of claim 13 wherein the second setting has a combustion charge density of at least 9.0 kilograms per cubic meter.

Claim 19

The method of claim 16 wherein the second setting has a brake mean effective pressure less than 750 kilo pascals.

Claim 20

The method of claim 11 wherein the air-to-fuel ratio is held fixed approximately at a stoichiometric value to permit effective catalytic reduction of emissions, and the exhaust gas residual fraction is varied.

Claim 21

The method of claim 11 further including the step of applying external exhaust gas recirculation to increase the bulk mixed gas to fuel ratio.

Claim 22

The method of claim 11 further including the step of increasing the air-to-fuel ratio to increase the bulk mixed gas to fuel ratio.

Claim 23

The method of claim 11 further including the step of reducing the valve overlap period to reduce the clearance between the valves and the piston to provide and improved combustion chamber geometry.

Claim 24

The method of claim 11 further including the step of reducing the valve overlap period from a value greater than 25 crankshaft rotational degrees to a value less than crankshaft rotational 25 degrees, to reduce the clearance between the valves and the piston to provide and improved combustion chamber geometry.

Claim 25

The method of claim 22 further including the step of increasing the exhaust gas residual fraction present in the bulk mixed gas to fuel ratio.

Claim 26

The method of claim 11 further including the step of reducing the valve overlap period from the first valve overlap setting to a second valve overlap setting at least 5 crankshaft rotational degrees less than the first valve overlap setting.

Claim 27

The method of claim 11 wherein the engine has a peak brake thermal efficiency greater than 38%.

Claim 28

The method of claim 11 wherein the engine has a swirl ratio at the second engine setting of less than 1.4 at an engine speed greater than 1400 rotations per minute, wherein the low swirl rate provides low heat loss from the combustion charge.

Claim 31

The method of rapidly adjusting the power of spark-ignition internal combustion engines of claim 27, further including the step of adjusting the fuel to air equivalence ratio.

Claim 32

The method of rapidly adjusting the power of spark-ignition internal combustion engines of claim 27, wherein the fuel is injected directly into the combustion chamber volume.

Claim 33

The method of rapidly adjusting the power of spark-ignition internal combustion engines of claim 27, further including the steps of, adjusting the exhaust gas residual fraction, and maintaining approximately a stoichiometric fuel to air equivalence ratio, wherein the stoichiometric fuel to air equivalence ratio enables optimum catalytic reduction of exhaust emissions.

Claim 34

The method of rapidly adjusting the power of spark-ignition internal combustion engines of claim 27, further including the steps of, adjusting the exhaust gas residual fraction, and adjusting the fuel to air equivalence ratio, wherein adjusting the exhaust gas residual fraction and adjusting the fuel to air equivalence ratio provides high engine efficiency and stable combustion over a large range of power.

Claim 35

A high-efficiency low-emission vehicle having a curb weight less than 6500 pounds comprising: a body; and a reciprocating piston four-stroke spark-ignition internal combustion engine connected to said body to provide power for moving the vehicle, said engine having a displacement volume, a combustion chamber volume, means for adjusting the compression ratio comprising an adjustment mechanism to vary the combustion chamber volume, an intake and exhaust valve overlap period, and a bulk mixed gas to fuel ratio having an air-to-fuel ratio, said vehicle having a California State Low Emission Vehicle II oxides of nitrogen emission test value, wherein the engine has means for adjusting the bulk mixed gas to fuel ratio, and a first engine setting having a compression ratio less than 12.5, and a second engine setting, having a compression ratio greater than 13, and the bulk mixed gas to fuel ratio at the second engine setting is greater than the bulk mixed gas to fuel ratio at the first engine setting, wherein the vehicle has a California State Low Emission Vehicle II oxides of nitrogen emission test value less than 0.05 grams per mile.

Claim 36

A high-efficiency low-emission vehicle having a curb weight less than 6500 pounds comprising: a body; and a reciprocating piston four-stroke spark-ignition internal combustion engine connected to said body to provide power for moving the vehicle, said engine having a displacement volume, a combustion chamber volume, means for adjusting the compression ratio comprising an adjustment mechanism to vary the combustion chamber volume, an intake and exhaust valve overlap period, and a bulk mixed gas to fuel ratio having an air-to-fuel ratio, said vehicle having a California State Low Emission Vehicle II oxides of nitrogen emission test value, wherein the engine has means for adjusting the bulk mixed gas to fuel ratio, and a first engine setting having a compression ratio less than 12.5, and a second engine setting, having a compression ratio greater than 13, and the bulk mixed gas to fuel ratio at the second engine setting is greater than the bulk mixed gas to fuel ratio at the first engine setting, wherein the vehicle has a California State Low Emission Vehicle II oxides of nitrogen emission test value less than 0.05 grams per mile.

Claim 37

The high-efficiency low-emission vehicle of claim 32, wherein the second engine setting has a fuel to air equivalence ratio less than 0.85.

Claim 38

The high efficiency low-emission vehicle of claim 32, wherein the second engine setting has a bulk mixed gas to fuel ratio greater than 18.5.

Claim 39

The high-efficiency low-emission vehicle of claim 32 further including means for supercharging.