Fuel feed devices for internal combustion engines

Claim 1

Fuel feed device, for an internal combustion engine, which comprises, in its intake pipe, upstream of a main throtTle member actuated by the driver, an auxiliary throttle member which opens automatically and progressively in proportion as the air flow increases in the said pipe, means for injecting liquid fuel under pressure into the portion of said pipe situated downstream of the main throttle member, and a metering system sensitive to the position of the auxiliary throttle member and adapted to adjust the flow of fuel injected in such a way that the richness of the air/fuel mixture passing into the intake pipe is substantially constant, at least for certain operational conditions of the engine, said injection means being constituted by a source of fuel under pressure whose delivery circuit, opening into said portion of the intake pipe, is controlled by at least one injection valve actuated by an electromagnet, the metering system comprising a member driven in a continuous rotary movement and capable, by acting on the energization of the electromagnet, of determining over a fraction only of each of its revolutions the opening of the injection valve, said metering system being arranged so that it increases and decreases said fraction in proportion as the opening of the auxiliary throttle member increases and decreases respectively, said source of fuel under pressure being constituted by a fuel pump in the delivery pipe of which acts a pressure regulator which comprises a relief valve tending to open under the effect of the delivery pressure of the pump and to close under the effect of the suction existing in the section of the intake pipe comprised between said main and auxiliary throttle members, which suction is transmitted through a linking passage to a diaphragm to which the relief valve is coupled, a variable volume chamber being connected to said linking passage between a calibrated orifice and the diaphragm of the regulator and controlled by means adapted to increase its volume on the opening of the main throttle member.