Direct-injection spark ignition engine

A direct-injection spark ignition engine in which a spark plug is disposed in a cylinder at a ceiling of a combustion chamber opposed to a crown surface of a piston, a fuel injection nozzle is disposed in the combustion chamber to inject a fuel from a peripheral portion of the combustion chamber, and the fuel injected from the fuel injection nozzle is stratified around an electrode of the spark plug during stratified-charge combustion operation, wherein

• the spark plug is disposed so that the electrode thereof protrudes from the ceiling of the combustion chamber in a direction parallel to the center line of the cylinder and the distance e between the ceiling of the combustion chamber and the electrode thereof has a value satisfying the relationship of e≧0.4d where d is the distance on the center line of the cylinder between the ceiling of the combustion chamber and the crown surface of the piston when the cylinder is at the top dead center during the compression stroke thereof,
• the fuel injection nozzle is disposed so that the spray cone angle of fuel spray therefrom has a value within the range of approximately 20° to 60° and the center line of fuel spray therefrom has a tilt angle within the range of approximately 25° to 40° with respect to an assumed plane orthogonal to the center line of the cylinder, and
• the engine comprises:
• tumble generating means capable of generating a tumble which flows between the electrode of the spark plug and the crown surface of the piston toward the fuel injection nozzle during a compression stroke of the cylinder;
• and
• fuel injection control means for controlling penetration of fuel spray through the fuel injection nozzle in accordance with the flow rate of the tumble and causing the fuel injection nozzle to inject fuel against the tumble.

A direct-injection spark ignition engine in which a spark plug is disposed in a cylinder at a ceiling of a combustion chamber opposed to a crown surface of a piston, a fuel injection nozzle is disposed in the combustion chamber to inject a fuel from a peripheral portion of the combustion chamber, and the fuel injected from the fuel injection nozzle is stratified around an electrode of the spark plug during stratified-charge combustion operation, said engine comprising:

• tumble generating means capable of generating a tumble which flows between the electrode of the spark plug and the crown surface of the piston toward the fuel injection nozzle during a compression stroke of the cylinder;
• and
• fuel injection control means for causing the fuel injection nozzle to inject the fuel in correspondence with an ignition timing for the cylinder so that fuel spray from the fuel injection nozzle goes against the tumble and stays in the vicinity of the electrode of the spark plug in the form of a flammable mixture at the time of ignition of the spark plug;
• wherein the electrode of the spark plug protrudes from the ceiling of the combustion chamber in a direction parallel to the center line of the cylinder, and
• the distance e between the ceiling of the combustion chamber and the electrode of the spark plug is set at a value satisfying the relationship of e≧0.4d where d is the distance on the center line of the cylinder between the ceiling of the combustion chamber and the crown surface of the piston when the cylinder is at the top dead center during the compression stroke thereof.

A direct-injection spark ignition engine in which a spark plug is disposed in a cylinder at a ceiling of a combustion chamber opposed to a crown surface of a piston, a fuel injection nozzle is disposed in the combustion chamber to inject a fuel from a peripheral portion of the combustion chamber, and the fuel injected from the fuel injection nozzle is stratified around an electrode of the spark plug during stratified-charge combustion operation, said engine comprising:

• tumble generating means capable of generating a tumble which flows between the electrode of the spark plug and the crown surface of the piston toward the fuel injection nozzle during a compression stroke of the cylinder;
• and
• fuel injection control means for causing the fuel injection nozzle to inject the fuel in correspondence with an ignition timing for the cylinder so that fuel spray from the fuel injection nozzle goes against the tumble and stays in the vicinity of the electrode of the spark plug in the form of a flammable mixture at the time of ignition of the spark plug
• wherein the crown surface of the piston is formed with a cavity longer in a direction in which the center line of fuel spray extends when viewed along the center line of the cylinder with, the deepest portion of the cavity is positioned in correspondence with the center line of the cylinder and
• the cavity has such a form that maximizes the distance thereof along the center line of the cylinder from the ceiling of the combustion chamber at the position corresponding to the center line of the cylinder.

A direct-injection spark ignition engine in which a spark plug is disposed in a cylinder at a ceiling of a combustion chamber opposed to a crown surface of a piston, a fuel injection nozzle is disposed in the combustion chamber to inject a fuel from a peripheral portion of the combustion chamber, and the fuel injected from the fuel injection nozzle is stratified around an electrode of the spark plug during stratified-charge combustion operation, said engine comprising:

• tumble generating means capable of generating a tumble which flows between the electrode of the spark plug and the crown surface of the piston toward the fuel injection nozzle during a compression stroke of the cylinder;
• and
• fuel injection control means for causing the fuel injection nozzle to inject the fuel in correspondence with an ignition timing for the cylinder so that fuel spray from the fuel injection nozzle goes against the tumble and stays in the vicinity of the electrode of the spark plug in the form of a flammable mixture at the time of ignition of the spark plug
• wherein the crown surface of the piston is formed with a cavity longer in a direction in which the center line of fuel spray extends when viewed along the center line of the cylinder with the deepest portion of the cavity is positioned closer to an intake side than the position corresponding to the center line of the cylinder.

A direct-injection spark ignition engine in which a spark plug is disposed in a cylinder at a ceiling of a combustion chamber opposed to a crown surface of a piston, a fuel injection nozzle is disposed in the combustion chamber to inject a fuel from a peripheral portion of the combustion chamber, and the fuel injected from the fuel injection nozzle is stratified around an electrode of the spark plug during stratified-charge combustion operation, said engine comprising:

• tumble generating means capable of generating a tumble which flows between the electrode of the spark plug and the crown surface of the piston toward the fuel injection nozzle during a compression stroke of the cylinder;
• and
• fuel injection control means for causing the fuel injection nozzle to inject the fuel in correspondence with an ignition timing for the cylinder so that fuel spray from the fuel injection nozzle goes against the tumble and stays in the vicinity of the electrode of the spark plug in the form of a flammable mixture at the time of ignition of the spark plug;
• the crown surface of the piston is formed with a cavity that accommodates the electrode of the spark plug when viewed along the center line of the cylinder, and
• squish area sections each for generating a squish flowing toward the inside of the cavity in cooperation with the opposed ceiling of the combustion chamber are formed in an outer portion of the crown surface of the piston, located outside of the cavity, at least both lateral locations thereof from the electrode of the spark plug with respect to the center line of the fuel spray when viewed along the center line of the cylinder.

A direct-injection spark ignition engine in which a spark plug is disposed in a cylinder at a ceiling of a combustion chamber opposed to a crown surface of a piston, a fuel injection nozzle is disposed in the combustion chamber to inject a fuel from a peripheral portion of the combustion chamber, and the fuel injected from the fuel injection nozzle is stratified around an electrode of the spark plug during stratified-charge combustion operation, said engine comprising:

• tumble generating means capable of generating a tumble which flows between the electrode of the spark plug and the crown surface of the piston toward the fuel injection nozzle during a compression stroke of the cylinder;
• and
• fuel injection control means for causing the fuel injection nozzle to inject the fuel in correspondence with an ignition timing for the cylinder so that fuel spray from the fuel injection nozzle goes against the tumble and stays in the vicinity of the electrode of the spark plug in the form of a flammable mixture at the time of ignition of the spark plug;
• wherein the crown surface of the piston is formed with a squish area section for generating squishes in cooperation with the ceiling of the combustion chamber so that a layer of the flammable mixture residing in the vicinity of the electrode of the spark plug takes on a diametrically diminished form on the side closer to the ceiling of the combustion chamber when viewed along the center line of the fuel spray.

A direct-injection spark ignition engine in which a spark plug is disposed in a cylinder at a ceiling of a combustion chamber opposed to a crown surface of a piston, a fuel injection nozzle is disposed in the combustion chamber to inject a fuel from a peripheral portion of the combustion chamber, and the fuel injected from the fuel injection nozzle is stratified around an electrode of the spark plug during stratified-charge combustion operation, said engine comprising:

• tumble generating means capable of generating a tumble which flows between the electrode of the spark plug and the crown surface of the piston toward the fuel injection nozzle during a compression stroke of the cylinder;
• and
• fuel injection control means for causing the fuel injection nozzle to inject the fuel in correspondence with an ignition timing for the cylinder so that fuel spray from the fuel injection nozzle goes against the tumble and stays in the vicinity of the electrode of the spark plug in the form of a flammable mixture at the time of ignition of the spark plug;
• wherein the electrode of the spark plug is disposed at the midpoint between a first partial flow of the tumble flowing along the crown surface of the piston and a second partial flow of the tumble flowing along the ceiling of the combustion chamber at a certain point after the start timing of fuel injection during the compression stroke of the cylinder and before the ignition timing for the cylinder.