Carburetor

Claim 2

For use with an internal combustion engine, a carburetor comprising a mixture conduit having an air inlet and a mixture outlet, a throttle disposed in said mixture outlet for controlling flow therethrough, an air valve disposed in said air inlet, means controlling said air valve to maintain a substantially constant subatmospheric pressure in said mixture conduit between said air valve and said throttle, a fuel bowl, a fuel passage receiving fuel from said fuel bowl and discharging fuel into said mixture conduit between said air valve and said throttle, an air bleed passage for discharging air at substantially atmospheric pressure into said mixture conduit between said air valve and said throttle, a valve seat formed in said bleed passage, a valve unit engageable with said valve seat to restrict air flow through said bleed pasage, and valve operating means for causing said valve unit to engage said valve seat during open throttle operation and during closed throttle operation at speed below a selected level and for moving said valve unit away from said valve seat during closed throttle operation at speeds above said selected level to thereby permit air to bleed into said mixture conduit between said air valve and said throttle to increase the pressure therein, whereby fuel flow to said mixture conduit is minimized during closed throttle operation at speeds above said selected level.

Claim 3

For use with an internal combustion engine having an ignition system energized when engine operation is desired and deenergized when engine operation is not desired, a carburetor comprising a mixture conduit having an air inlet and a mixture outlet, a throttle disposed in said outlet and rotatable betwen open and closed positions for controlling flow therethrough, an air valve disposed in said inlet, means controlling said air valve to maintain substantially constant subatmospheric pressure in the region of said mixture conduit between said air valve and said throttle, a fuel bowl, a fuel passage receiving fuel from said fuel bowl and discharging fuel into said mixture conduit region, an air bleed passage for discharging air at substantially atmospheric pressure into said mixture conduit region, an air bypass passage extending from said region to said mixture conduit downstream of said throttle, valve means for alternatively restricting air flow through said bleed and bypass passages, a diaphragm positioning said valve means, one side of said diaphragm being subjected to the pressure in said bypass passage, the opposite side of said diaphragm being subjected alternatively to the pressure at a first port in said mixture conduit disposed Downstream of said throttle and to the pressure at a second port in said mixture conduit disposed adjacent the upstream edge of said throttle when said throttle is in said closed position and traversed by the upstream edge of said throttle as said throttle is rotated from said closed position, and valve means for subjecting said opposite side of said diaphragm to the pressure at said second port when the ignition system is energized and the engine is running at speeds above a selected value and for subjecting said opposite side of said diaphragm to the pressure at said first port at other times, whereby when said ignition system is deenergized and said throttle is rotated to said closed position said diaphragm will position said valve means to restrict air flow through said bypass passage and to permit unrestricted air flow through said bleed passage and thereby reduce air and fuel flow sufficiently to prevent afterrunning of the engine, whereby when the engine is running at speeds above said selected valve and said throttle is rotated to said closed position said diaphragm will position said valve means to restrict air flow through said bypass passage and to permit unrestricted air flow through said bleed passage and thereby reduce air and fuel flow during engine deceleration, and whereby at other times said diaphragm will position said valve means to restrict air flow through said bleed passage and to permit unrestricted flow through said bypass passage.

Claim 4

For use with an internal combustion engine having an ignition system energized when engine operation is desired and deenergized when engine operation is not desired, a carburetor comprising a mixture conduit having an air inlet and a mixture outlet, a throttle disposed in said outlet and rotatable betwen open and closed positions for controlling flow therethrough, an air valve disposed in said inlet, means controlling said air valve to maintain substantially constant subatmospheric pressure in the region of said mixture conduit between said air valve and said throttle, a fuel bowl, a fuel passage receiving fuel from said fuel bowl and discharging fuel into said mixture conduit region, an air bleed passage for discharging air at substantially atmospheric pressure into said mixture conduit region, an air bypass passage extending from said region to said mixture conduit downstream of said throttle, valve means for alternatively restricting air flow through said bleed and bypass passages, a diaphragm positioning said valve means, one side of said diaphragm being subjected to the pressure in said bypass passage, the opposite side of said diaphragm being subjected alternatively to the pressure at a first port in said mixture conduit disposed Downstream of said throttle and to the pressure at a second port in said mixture conduit disposed adjacent the upstream edge of said throttle when said throttle is in said closed position and traversed by the upstream edge of said throttle as said throttle is rotated from said closed position, and valve means for subjecting said opposite side of said diaphragm to the pressure at said second port when the ignition system is energized and the engine is running at speeds above a selected value and for subjecting said opposite side of said diaphragm to the pressure at said first port at other times, whereby when said ignition system is deenergized and said throttle is rotated to said closed position said diaphragm will position said valve means to restrict air flow through said bypass passage and to permit unrestricted air flow through said bleed passage and thereby reduce air and fuel flow sufficiently to prevent afterrunning of the engine, whereby when the engine is running at speeds above said selected valve and said throttle is rotated to said closed position said diaphragm will position said valve means to restrict air flow through said bypass passage and to permit unrestricted air flow through said bleed passage and thereby reduce air and fuel flow during engine deceleration, and whereby at other times said diaphragm will position said valve means to restrict air flow through said bleed passage and to permit unrestricted flow through said bypass passage.

Claim 5

For use with an internal combustion engine having an ignition system energized when engine operation is desired and deenergized when engine operation is not desired, a carburetor comprising an air induction passage, a throttle disposed in said induction passage for controlling air flow therethrough, an air bypass passage extending from a location in said induction passage upstream of said throttle to a location in said induction passage downstream of said throttle, a valve seat formed in said bypass passage, a diaphragm valve unit engageable with said valve seat to restrict air flow through said bypass passage, said diaphragm valve unit including a diaphragm member having one side subjected to the pressure in said bypass passage and the opposite side alternatively subjected to pressures higher and lower than the pressure in said bypass passage, and means for subjecting said opposite side of said diaphragm to such lower pressure when said ignition system is energized whereby said diaphragm valve member is biased away from said valve seat to permit unrestricted air flow through said bypass passage and for subjecting said opposite side of said diaphragm to such higher pressure when said ignition system is deenergized whereby said diaphragm valve member is biased into engagement with said valve seat to restrict air flow through said bypass passage and thereby reduce the tendency toward afterrunning of the engine.

Claim 6

For use with an internal combustion engine having an ignition system energized when engine operation is desired and deenergized when engine operation is not desired, a carburetor comprising an air induction passage, a throttle disposed in said induction passage for controlling air flow therethrough, an air bypass passage extending from a location in said induction passage upstream of said throttle to a location in said induction passage downstream of said throttle, a valve seat formed in said bypass passage, a diaphragm valve unit engageable with said valve seat to restrict air flow through said bypass passage, said diaphragm valve unit including a diaphragm member having one side subjected to the pressure in said bypass passage and the opposite side alternatively subjected to pressures higher and lower than the pressure in said bypass passage, and means for subjecting said opposite side of said diaphragm to such lower pressure when said ignition system is energized whereby said diaphragm valve member is biased away from said valve seat to permit unrestricted air flow through said bypass passage and for subjecting said opposite side of said diaphragm to such higher pressure when said ignition system is deenergized whereby said diaphragm valve member is biased into engagement with said valve seat to restrict air flow through said bypass passage and thereby reduce the tendency toward afterrunning of the engine.