Patent ID: 7404393
Filing Date: 2008-07-29
Classification: F02M

Abstract:
1. A fuel injection system comprising: an accumulator volume arranged to be charged with fuel by means of a high pressure fuel pump and for supplying fuel at a first injectable pressure level to a plurality of fuel injectors, and a non-return valve arranged within a high pressure supply passage through which fuel is supplied from the accumulator volume directly to a delivery passage of each fuel injector, wherein each fuel injector further includes a valve needle which is engageable with a seating to control fuel injection, and a control valve for controlling fuel pressure within a control chamber so as to control movement of the valve needle, the control valve having a first operating position in which the control chamber communicates with a low pressure drain and communication between the control chamber and the delivery passage is prevented, and a second operating position in which the control chamber communicates with the delivery passage and communication between the control chamber and the low pressure drain is prevented, and wherein each injector has an associated intensifier arrangement for increasing the pressure of fuel to be supplied to the injector to a second injectable pressure level, the intensifier arrangement including an intensifier control valve which is operable to determine whether fuel injected to the engine is at the first or second injectable pressure level, and an intensifier piston having a pressure control chamber and an intensifier chamber, wherein the intensifier control valve is operable to control fuel pressure within the pressure control chamber and, hence, to control fuel pressure within the intensifier chamber, the intensifier control valve having first operating position, in which the accumulator volume communicates with the pressure control chamber via the supply passage and the non-return valve such that operation of the intensifier arrangement is prevented and fuel is supplied to the injector, while bypassing said intensifier arrangement at the first injectable pressure level, and a second operating position, in which the pressure control chamber communicates with a low pressure drain, and communication between the accumulator volume and the pressure control chamber is prevented, such that the intensifier arrangement operates to supply fuel to the injector at the second injectable pressure level, and wherein the pressure control chamber is an intermediate chamber of the intensifier arrangement which is defined between opposing ends of the intensifier piston.