Deceleration enrichment fuel system for an internal combustion engine

An internal combustion engine comprising a crankcase, a cylinder extending from said crankcase, a piston mounted in said cylinder for reciprocative movement therein and cooperating with said cylinder to define a combustion chamber, a carburetor having an air induction passage communicating with said combustion chamber, a venturi and a throttle valve mounted inside said induction passage downstream of said venturi for movement between an idling speed position and a range of high speed positions, said induction passage having a low pressure zone downstream of said throttle valve wherein sub-atmospheric pressure is created in response to reciprocative movement of said piston, a primary fuel delivery system including a fuel pump communicating with a source of fuel for supplying fuel from the fuel source to said carburetor during engine operation, and a secondary fuel delivery system including conduit means communicating with said fuel pump and with said combustion chamber at a point downstream of said throttle valve, valve means in said conduit means movable between a closed position to prevent delivery of fuel through said conduit means from said fuel pump into said combustion chamber and an open position to permit delivery of fuel through said conduit means from said fuel pump into said combustion chamber, and actuating means for selectively moving said valve means to the open position in response to the pressure in said low pressure zone decreasing to a predetermined level.

An internal combustion engine comprising a crankcase, a cylinder extending from said crankcase, a piston mounted in said cylinder for reciprocative movement therein and cooperating with said cylinder to define a combustion chamber, a carburetor having an air induction passage communicating with said combustion chamber, a venturi and a throttle valve mounted inside said induction passage downstream of said venturi for pivotal movement between an idling speed position and a range of high speed positions, said induction passage having a low pressure zone downstream of said throttle valve wherein sub-atmospheric pressure is created in response to reciprocative movement of said piston, a primary fuel delivery system including a fuel pump communicating with a source of fuel for supplying fuel from the fuel source to said carburetor during engine operation, and a secondary fuel delivery system including conduit means communicating with said fuel pump and with said combustion chamber at a point downstream of said throttle valve, a control valve in said conduit means including a valve member movable between a normally closed position to prevent delivery of fuel through said conduit means from said fuel pump into said combustion chamber and an open position to permit delivery of fuel through said conduit means from said fuel pump into said combustion chamber and an electrical solenoid operable, upon energization, to move said valve member to the open position, and electrical control circuit means connected to a source of electrical energy for supplying electrical energy to said solenoid and including a pressure-sensing switch means connected in communication with said low pressure zone and operable to energize said solenoid in response to the pressure in said low pressure zone decreasing below a predetermined level and to continue energizing said solenoid until the pressure in said low pressure zone subsequently exceeds said predetermined level.