Patent ID: 7240859
Filing Date: 2007-07-10
Classification: F02D,F02M,Y10S

Abstract:
1. A pressurized fuel-injection system for an internal-combustion engine, comprising at least one electroinjector ( 1 ) for fuel injection and an electroactuator device ( 8 ) for a metering valve ( 16 ), said electroinjector ( 1 ) comprising an injection nozzle ( 5 ) in communication with an injection chamber ( 6 ), and a needle ( 7 ) mobile for an opening stroke under the action of the pressure of the fuel of said injection chamber ( 6 ) against an active surface of said needle ( 7 ), said device ( 8 ) comprising a rod ( 14 ), which is engaged with said needle ( 7 ) and has a portion ( 14 a ) normally pushed by the pressure of said fuel in a control chamber ( 15 ) associated to said metering valve ( 16 ), said needle ( 7 ) being normally held in the position for closing said nozzle ( 5 ), said control chamber ( 15 ) being equipped with an inlet duct ( 18 ) having a pre-set diameter (D 4 ) and an outlet passage ( 24 ) having a diameter (D 5 ), said outlet passage ( 24 ) being controlled by said metering valve ( 16 ); said device ( 8 ) being actuated by an electrical control unit designed to issue at least one first electrical command (C 1 ; C 3 ; C 5 -C 7 ) and at least one second electrical command (C 2 ; C 4 ; C 8 ); said fuel-injection system being characterized in that a ratio (D 5 /D 4 ) between the diameter (D 5 ) of said outlet passage ( 24 ) and the diameter (D 4 ) of said inlet duct ( 18 ) is such as to determine a certain rate of displacement of said needle ( 7 ), said first electrical command (C 1 ; C 3 ; C 5 -C 7 ) and said second electrical command (C 2 ; C 4 ; C 8 ) being close to one another so as to cause a displacement of said needle ( 7 ) with a profile of motion (P) without any discontinuities in time.