Nozzle check valve system

Claim 2

In a diaphragm carburetor having a mixing passage, a diaphragm chamber, a fuel inlet control valve controlled by the position of a diaphragm in that chamber, a main fuel duct to conduct fuel from the chamber to the mixing passage, and an idle fuel passage between the chamber and the mixing passage, that improvement which comprises a main fuel duct with a double branch portion at one portion thereof between a root opening into the chamber and a main fuel nozzle leading to the mixing passage, a fuel metering valve controlling the effective size of one of said branches, and a check valve at said root openiNg movable to a first position to block reverse flow from said mixing passage to said chamber and to a second position to block flow through the other of said branches, said valve in an intermediate position allowing flow through both said branches.

Claim 3

A device as defined in claim 1 in which a plate is mounted on one wall of said chamber having a hole to form the root opening of the main fuel duct and located to provide a flat recess surrounding the diaphragm end of said branch passage, and said check valve comprises a flat valve member in said recess overlying said plate movable to said first position to close said hole and to said second position to close said other branch passage.

Claim 4

A device as defined in claim 1 in which a carburetor body has a wall forming one wall of a diaphragm chamber, a plate positioned against said wall having a portion spaced from said wall adjacent said branch passages to provide a thin cavity, said plate having a hole to provide said root passage at said spaced portion, and said check valve comprises a flexible valve member positioned in said cavity to overlie said hole in said first position and movable in said cavity to said second position to close said other branch passage.

Claim 5

In a diaphragm carburetor, a carburetor body having a wall forming one wall of a diaphragm chamber, said wall having two branch passages originating at said wall and leading to a common fuel nozzle opening into a mixing passage, a manual control valve positioned to regulate one of said branch passages, a sheet of material on said one wall provided with an opening forming a shallow recess overlying openings to said branch passages, a sheet of flexible material having a flap valve formed therein positioned to overlie said recess, said valve overlying the opening into the other of said branch passages, and plate means overlying said sheets having an opening underlying said flap valve and connecting said chamber to said recess wherein said valve in one position in said recess closes said plate opening and in a second position closes said opening into said other branch passage and in an intermediate position permits flow from said plate opening to both said branch passages.

Claim 6

In a diaphragm carburetor, a carburetor body having a wall forming one wall of a diaphragm chamber, said wall having two branch passages originating at said wall and leading to a common fuel nozzle opening into a mixing passage, a manual control valve positioned to regulate one of said branch passages, a sheet of material on said one wall provided with an opening forming a shallow recess overlying openings to said branch passages, a sheet of flexible material having a flap valve formed therein positioned to overlie said recess, said valve overlying the opening into the other of said branch passages, and plate means overlying said sheets having an opening underlying said flap valve and connecting said chamber to said recess wherein said valve in one position in said recess closes said plate opening and in a second position closes said opening into said other branch passage and in an intermediate position permits flow from said plate opening to both said branch passages.