Fuel feed devices for internal combustion engines

Claim 1

In a fuel feed device for internal combustion engines, which comprises in the induction pipe, upstream of a main throttling member operated by the driver, an auxiliary throttling member which opens automatically and progressively as the rate of airflow in the said pipe increases; 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, the said injection means being in the form of a source of fuel under pressure of which the 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 member adapted to be rotated continuously and capable, by affecting energization of the electromagnet, of causing opening of the valve during only a fraction of each of its revolutions, this system being so arranged that it increases this fraction the further the auxiliary throttling member opens, and vice versa, the improvement comprising in the induction pipe, upstream of the auxiliary throttling member, an eccentric butterfly valve which opens under the influence of the flow of air and contrary to the variable resilient action of a member which responds to the engine temperature, and between the space defined in the pipe by the two main and auxiliary throttling members and that zone of the pipe downstream of the main throttling member a passage short circuiting the said main throttling member, means being provided for progressive throttling of the passage as the eccentric butterfly valve opens when the engine heats up.