Injection devices for internal combustion engines

Claim 1

Injection device, for an internal combustion engine, which comprises an injection pump having a cylinder wherein a piston moves, and immediately downstream of said cylinder a delivery and reaspirating valve biased by a spring and adapted to open, on one hand, on the active portion of the delivery stroke of the piston to allow liquid fuel to arrive from the cylinder to an injector through a linking passage and, on the other hand, when the difference in pressures between the linking passage and the cylinder of the pump exceeds a given limit, to allow the fuel to flow back towards the cylinder, for which purpose said valve cooperates, on one hand, through a terminal sealing collar with a seat arranged between the cylinder and an annular chamber connected permanently to the linking passage, said collar and seat being in contact through an annular zone when the valve is closed, and, on the other hand, through a cylindrical portion of greater diameter than the maximum diameter of the said annular zone, with a cylindrical guide bore in which this cylindrical portion slides with fluid-tightness, the valve comprising, in addition, a second cylindrical portion which is arranged with slight spacing in the bore, which is closed beyond this second cylindrical portion to constitute a fuel chamber, connecting means being provided to connect said fuel chamber to the suction side of the pump as long as the spacing between the valve and its seat has not exceeded a predetermined value, wherein the connecting means are constituted by a groove, formed around the valve against its second cylindrical portion, which is connected permanently to the fuel chamber by a passage passing through the valve and which communicates, in the first part of the lifting stroke of this valve, with a channel permanently connected to the suction side of th pump.