Abstract:
An automatic carburetor (20) enrichment system that controls the air-fuel mixture during cold start of an engine (10) having a carburetor including a fuel bowl (22) and an induction passage (23), includes a sensor (50) that provides a signal indicative of an engine temperature at engine start, a fuel line (30) connected between the fuel bowl (22) and the induction passage, a solenoid valve (40) disposed in the fuel line, and a controller (10) that receives the signal and sets a duty cycle of the solenoid valve associated with the engine temperature to increase the air-fuel ratio of the air-fuel mixture at engine start. The automatic carburetor enrichment system reduces cranking time during cold start, eliminates the need for driver input during cold start, prevents engine stalling without assistance from the operator during the warm up phase, provides a simpler, more cost effective and reliable carburetor enrichment, provides self-drowning protection without the use of an electronic idle switch and eliminates the risk of engine drowning when the engine is cranked with the choke ON and the ignition switches OFF.
Abstract:
A carburetor 1 includes: an intake passage 21 for allowing intake air to an engine to flow therethrough; a fuel storage section 22 for storing fuel from a fuel tank; a starting fuel supply passage 30 for supplying starting fuel from the fuel storage section 22 to the intake passage 21; and a solenoid valve 3 provided in the middle of the starting fuel supply passage 30. At least a part of the starting fuel supply passage 30 between a fuel intake portion 31 and the intake passage 21 is formed in a straight line. Thus, pressure loss of the fuel between the fuel intake portion 31 and the intake passage 21 is suppressed, so that the fuel can be easily extracted to the intake passage 21 by the negative pressure generated in the intake passage 21without stagnating. Accordingly, the optimal amount of the starting fuel can be supplied to the engine when the engine is cold, so that the startability of an engine can be secured.
Abstract:
This invention is characterized in that a starting fuel pump (49) for use in sucking a fuel from a fuel tank (25) and supplying the fuel to a starting nozzle port (41) of a carburetor (17) is driven by a fuel supplying electric motor (53). In order to start the engine, the motor (53) is rotated to suck the fuel from the fuel tank (25) by means of the pump (49) and supply the same to the starting nozzle (41), whereby the density of the gaseous mixture is increased to render the gaseous mixture easily ignitable. Thus, the engine can be started by either a starting electric motor or a recoil starter.