Carburation devices

Claim 1

A carburetion device for internal combustion engine comprising: a body formed with an induction passage for delivering an air/fuel mixture to an engine, operator operable throttle means in said induction passage, an idling duct connected to receive air from said induction passage and fuel from a float chamber through respective calibrated orifices and opening into said induction passage at a point which is located slightly upstream of the throttle means when the latter is in its minimum opening position, passageway means connected to receive air and fuel to form a primary air/fuel mixture and to receive dilution air from said induction passage, said passageway means having an outlet opening into said induction passage at a location which is continuously downstream of the throttle to deliver an air/fuel mixture to said induction passage and by passage said throttle means, said passageway means having a common downstream portion supplied by two parallel branches one of which comprises a first channel formed with a calibrated orifice having a fixed flow cross-sectional area and the other of which comprises a second channel controlled by the solenoid valve, said idling duct additionally having a downstream portion which opens into said passageway means through a calibrated port for delivery of an additional amount of primary air/fuel mixture into said passageway means, a solenoid valve having two positions and located on said passageway means at a location which is downstream of dilution air delivery into said passageway means and upstream of primary air/fuel mixture delivery into said passageway means, and a solenoid valve control circuit comprising engine speed sensing means and means for detecting deceleration of the engine, arranged and operating to supply the solenoid valve with energizing pulses having a variable duty cycle to prevent the engine speed from falling substantially below a set idling value and to give the solenoid valve a duty cycle which increases with the speed of the engine during engine deceleration above a preset speed (N O ).