Internal combustion engine

An internal combustion engine comprising:

• a valve operating system connected to a pair of intake valves and arranged to selectively open one of said intake valves only a very small amount that places the one intake valve into a substantially inoperative state during a normal suction stroke mainly in a low speed operation region of the engine;
• a fuel injection valve capable of injecting fuel toward a pair of intake ports which independently correspond to said pair of intake valves;
• and
• a control means for controlling an operation of said fuel injection valve, a combustion of a dilute air-fuel mixture being possible at least in an engine operational region in which said one intake valve is in said substantially inoperative state, wherein
• a recess is provided in a surface of a piston which is exposed to a combustion chamber of the engine so as to form a portion of said combustion chamber, said valve operating system is arranged so as to cause an opening angle middle time for said one intake valve in said substantially inoperative state to come in a second half of a normal suction stroke, and said control means is arranged to establish a fuel injection completion time to come in a first half of the suction stroke and control said fuel injection valve when said one intake valve is in said substantially inoperative state.

An internal combustion engine comprising:

• a valve operating system connected to a pair of intake valves and a pair of exhaust valves and arranged to selectively open one of said intake valves only a very small amount that places said one intake valve into a substantially inoperative state during a normal suction stroke mainly in a low speed operation region of the engine;
• a fuel injection valve capable of injecting fuel toward a pair of intake ports which independently correspond to said pair of intake valves;
• and
• a control means for controlling an operation of said fuel injection valve, a combustion of a dilute air-fuel mixture being possible at least in an engine operation region in which said one intake valve is in said substantially inoperative state, wherein
• a recess is provided in an upper surface of a piston which is exposed to a combustion chamber of the engine so as to form a portion of said combustion chamber and a spark plug is disposed substantially at a central portion of a ceiling surface of the combustion chamber, and wherein
• said valve operating system includes a single cam shaft common to said intake valves and said exhaust valves and arranged so as to cause an opening angle middle time for said one intake valve in said substantially inoperative state to come in a second half of a normal suction stroke, and said control means is arranged to control said fuel injection valve to cause a completion of fuel injection to occur in a first half of the suction stroke when said one intake valve is in said substantially inoperative state.

An internal combustion engine having a pair of intake ports connected to a combustion chamber and a pair of intake valves for opening and closing the pair of intake ports, respectively, the engine comprising:

• a valve operating system for operating the pair of intake valves for opening and closing thereof in a plurality of modes including a first mode in which both the intake valves are opened and closed in a normal manner in a suction stroke and a second mode in which a first intake valve of the pair of intake valves is opened and closed in the normal manner and a second intake valve of the pair of intake valves is held in a substantially inoperative state during the suction stroke;
• a switchover means for establishing connection and disconnection between said pair of intake valves so as to selectively provide said first mode upon said connection and said second mode upon said disconnection mainly in a low speed operational region of the engine;
• a fuel injection valve associated with both the pair of intake ports and capable of injecting fuel toward the ports;
• a control means for controlling the fuel injection valve such that in said second mode the control means controls the fuel injection valve so as to complete fuel injection in a first half of the suction stroke;
• wherein in said second mode said second intake valve of the pair of intake valves has a slight amount of valve lift of which a maximum lift point comes later along a crank angle than a maximum lift point of an opening lift curve established by said first intake valve of the pair of intake valves in this second mode.

An internal combustion engine comprising:

• a valve operating system connected to a pair of intake valves and arranged to selectively open one of said intake valves only a very small amount that places said one intake valve into a substantially inoperative state during a normal suction stroke mainly in a low speed operation region of the engine;
• a fuel injection valve capable of injecting fuel toward a pair of intake ports which independently correspond to said pair of intake valves;
• and
• a control means for controlling an operation of said fuel injection valve, wherein
• said control means is arranged to establish a fuel injection completion time within a normal suction stroke and control said fuel injection valve when said one intake valve is in said substantially inoperative state,
• wherein said valve operating system comprises a cam shaft provided with a plurality of cams including an opening and closing cam for opening and closing the other intake valve of the pair of intake valves in the suction stroke, and a slightly operating cam for opening said one intake valve only a very small amount such that the said one intake valve is brought into its substantially inoperative state mainly in said low speed operation region of the engine, and a valve operational characteristic switchover means capable of switching-over the operational characteristics of the pair of intake valves in accordance with the operational condition of the engine, said slightly operating cam being formed to open said one intake valve in a slight lift curve having an opening angle middle time at a delayed angle from an opening angle middle time in an opening lift curve for said other intake valve opened by said opening and closing cam and further having a terminal end time in the vicinity of a buffer curve portion at a terminal end along the crank angle in said valve opening lift curve, and wherein
• a maximum lift point in the slight lift curve by the slightly operating cam is established at a later side along the crank angle from a maximum lift point in the opening lift curve by said opening and closing cam.

An internal combustion engine comprising:

• a valve operating system connected to a pair of intake valves and arranged to selectively open one of said intake valves only a very small amount that places said one intake valve into a substantially inoperative state during a normal suction stroke mainly in a low speed operation region of the engine;
• a fuel injection valve capable of injecting fuel toward a pair of intake ports which independently correspond to said pair of intake valves;
• and
• a control means for controlling an operation of said fuel injection valve, wherein
• said control means is arranged to establish a fuel injection completion time within a normal suction stroke and control said fuel injection valve when said one intake valve is in said substantially inoperative state,
• wherein said valve operating system comprises a cam shaft provided with a plurality of cams including an opening and closing cam for opening and closing the other intake valve of the pair of intake valves in the suction stroke, and a slightly operating cam for opening said one intake valve only a very small amount such that the said one intake valve is brought into its substantially inoperative state mainly in said low speed operation region of the engine, and a valve operational characteristic switchover means capable of switching-over the operational characteristics of the pair of intake valves in accordance with the operational condition of the engine, said slightly operating cam being formed to open said one intake valve in a slight lift curve having an opening angle middle time at a delayed angle said from an opening angle middle time in an opening lift curve for said other intake valve opened by said opening and closing cam and further having a terminal end time in the vicinity of a buffer curve portion at a terminal end along the crank angle in said valve opening lift curve, and wherein
• said valve operating system includes a plurality of valve operating members provided adjacent one another between the cams of the cam shaft and the pair of intake valves, said valve operational characteristic switchover means being arranged to be able to switch over the connection and disconnection of the adjacent valve operating members to and from each other.