Fuel feed devices for internal combustion engines

Claim 1

For use with an internal combustion engine, a fuel feed device comprising in combination, in the induction pipe of the engine a main throttling member actuated by the driver; upstream of said main throttling member an auxiliary throttling member which opens automatically and progressively as the rate of air flow in the said pipe increases; injection means for injecting liquid fuel under pressure into that portion of the induction pipe downstream of the maiN throttling member; and a metering system adapted to respond to the position of the auxiliary throttling member and so to regulate the rate of flow of the fuel injected that the richness of the fuel-air mixture entering the induction pipe is substantially constant, at least for certain running conditions of the engine, said injection means being in the form of a source of fuel under pressure whose delivery circuit, leading into the said portion of the induction pipe, is controlled by at least one valve operated by an electromagnet, the metering system comprising a flat, opaque disc adapted to be rotated continuously by the internal combustion engine about a shaft perpendicular to its plane, said disc being placed between a radiation source and a radiation detector, a support connected to and displaceable by the auxiliary throttling member and bearing both said radiation source and said radiation detector; said disc containing at least one port adapted to admit the beam from the radiation source to the radiation detector; said detector being adapted to cause energization of the electromagnet, depending on whether or not it is irradiated, the assembly as a whole (more particularly the shape of the port and the rate of displacement of the support) being such that the electromagnet is energized during a fraction of each revolution of the disc which fraction varies in the same direction as the degree of opening of the auxiliary throttling member, a lever associated with each said port of said disc and mounted on the disc by means of a pivot substantially parallel to said shaft of the disc, a return spring arranged to bias said lever, the sites of the pivot and of the center of gravity of said lever, the shape of the lever and the force of the spring being so selected that, depending on whether the speed of the disc (and therefore of the engine) is above or below a given limit, the lever masks or exposes a portion of said port which, when the auxiliary throttling member is in the idling and deceleration positions, is swept by the radiation from said source directed towards the radiation detector, so that the lever comes into operation solely during deceleration periods to reduce or eliminate the total period of energization of the electromagnet and consequently the flow of fuel.