Injection devices for internal combustion engines

Claim 1

In an injection system for use in an internal combustion engine including in the induction pipe of the engine, a main throttle member actuated by the driver, an auxiliary throttle member positioned upstream of said main throttle member, spring biasing means normally urging said auxiliary throttle member closed and automatically and progressively, in proportion to the air-flow past said auxiliary throttle member in said pipe, allowing the opening of said auxiliary throttle member to increase against the spring bias, an injection orifice communicating with a zone of said induction pipe situated downstream of said main throttle member, a source of fuel under pressure connected to said injection orifice, a metering system disposed between the fuel source and the injection orifice and sensitive to the position of the auxiliary throttle member and comprising regulating means for the flow of fuel through said injection orifice so that the richness of the air-fuel mixture passing into the induction pipe downstream of said injection orifice is substantially constant, at least under certain conditions of operation of the engine, an auxiliary orifice opening into said zone and aligned with and separated by a space from said injection orifice, said space forming part of a chamber wherein the pressure is substantially independent of that existing in said zone and a passage communicating said chamber with an upstream portion of said induction pipe the improvement comprising the passage communicating said chamber with that portion of the induction pipe bounded on the downstream side by the upstream side of the main throttle member and on the upstream side by the auxiliary throttle member such that when the force exerted by said spring means on said auxiliary throttle member is nearly closing said auxiliary throttle member due to slight airflow passing through said induction pipe which under such circumstances, is exerted only a relatively small counterbalancing force on the auxiliary throttle member, said passage lies on the downstream side of said auxiliary throttle member so that the auxiliary throttle member will be exposed to the total air flowing through the induction pipe even though when greater air flows are present in said induction pipe and a greater counter-balancing force is imposed on said auxiliary throttle member forcing it to a greater opening against the influence of said spring means, the passage may lie on the upstream side of said auxiliary throttle member whereupon a portion of the total air flow may be diverted through said passage before reaching the auxiliary throttle member so that for at least conditions of slight air flow the sensitivity of the metering system and its correlation with the auxiliary throttle member is preserved.