Carburetor apparatus and method

Claim 2

In an internal combustion engine carburetor having means for sensing air flow rate therethrough, a source of fluid fuel, a first restriction for metering fuel communicating with said fuel source, a second restriction, and a fuel flow passage between said restrictions, and means connected to said sensing means for proportioning fuel flow to said air flow; the combination with said carburetor of an air-fuel mixing chamber in said fuel flow passage, a variable source of bleed air, and bleed air passage means from said bleed air source to said mixing chamber for conducting a stream of bleed air into said mixing chamber wherein the bleed air becomes mixed with the fuel so that a mixture of fuel and bleed air passes through said second restriction, thereby superimposing the effect of the bleed air on the said proportioning means by altering the pressure differential across said first restriction, whereby the rate of fuel flow is modulated by variations in the bleed air flow.

Claim 3

Apparatus as defined in claim 1, wherein said bleed air source has a pressure generally inversely related to the rate of air flow through the carburetor so that the flow of bleed air into said mixing chamber tends to decrease with increased fuel flow and tends to increase with decreased fuel flow.

Claim 4

Apparatus as defined in claim 2, wherein said bleed air source comprises means defining an opening in the carburetor air intake throat which faces generally downstream with respect to the flow of intake air through said throat.

Claim 5

Apparatus as defined in claim 3, wherein said opening-defining means comprises tube means extending into the carburetor intake throat and terminating at an open end which faces generally downstream.

Claim 6

Apparatus as defined in claim 1, wherein said mixing chamber is defined within a sleeve disposed in said carburetor between said metering and atomizing orifices, said bleed air passage means including structure defining a clearance about said sleeve and perforation means through the wall of said sleeve.

Claim 7

Apparatus as defined in claim 1, which includes bleed air flow modulating means associated with said bleed air passage means.

Claim 8

Apparatus as defined in claim 6, wherein said modulating means is responsive to ambient temperature changes to tend to increase the flow of bleed air to said mixing chamber in response to a temperature increase and decrease the flow of bleed air to said mixing chamber in response to a temperature decrease.

Claim 9

Apparatus as defined in claim 7, wherein said modulating means includes vent tube means communicating with said bleed air passage means so as to vent a portion of the bleed air from said bleed air passage means and thereby decrease the flow of bleed air to said mixing chamber.

Claim 10

In an internal Combustion engine carburetor having a source of fluid fuel, a fuel metering orifice communicating with said fuel source, a fuel atomizing orifice, and a fuel flow passage between said orifices, the combination with said carburetor of an air-fuel mixing chamber in said fuel flow passage, a source of bleed air, bleed air passage means from said bleed air source to said mixing chamber for conducting a straem of bleed air into said mixing chamber wherein the bleed air becomes mixed with the fuel so that a mixture of fuel and bleed air passes through the atomizing orifice, and bleed air flow modulating means associated with said bleed air passage means, said modulating means being responsive to ambient temperature changes to tend to increase the flow of bleed air to said mixing chamber in response to a temperature increase and decrease the flow of bleed air to said mixing chamber in response to a temperature decrease, said modulating means including vent tube means communicating with said bleed air passage means so as to vent a portion of the bleed air from said bleed air passage means and thereby decrease the flow of bleed air to said mixing chamber, said vent tube means having a capillary tube section therein which tends to allow less vent air to pass therethrough with an increase in ambient temperature and more vent air to pass therethrough with a decrease in ambient temperature, said bleed air passage means including stove means upstream of the communication with said vent tube means and associated with the engine exhaust system, whereby the ambient temperature response of said modulating means is at least in part controlled by engine operating temperature as reflected by exhaust system temperature.

Claim 11

In an internal Combustion engine carburetor having a source of fluid fuel, a fuel metering orifice communicating with said fuel source, a fuel atomizing orifice, and a fuel flow passage between said orifices, the combination with said carburetor of an air-fuel mixing chamber in said fuel flow passage, a source of bleed air, bleed air passage means from said bleed air source to said mixing chamber for conducting a straem of bleed air into said mixing chamber wherein the bleed air becomes mixed with the fuel so that a mixture of fuel and bleed air passes through the atomizing orifice, and bleed air flow modulating means associated with said bleed air passage means, said modulating means being responsive to ambient temperature changes to tend to increase the flow of bleed air to said mixing chamber in response to a temperature increase and decrease the flow of bleed air to said mixing chamber in response to a temperature decrease, said modulating means including vent tube means communicating with said bleed air passage means so as to vent a portion of the bleed air from said bleed air passage means and thereby decrease the flow of bleed air to said mixing chamber, said vent tube means having a capillary tube section therein which tends to allow less vent air to pass therethrough with an increase in ambient temperature and more vent air to pass therethrough with a decrease in ambient temperature, said bleed air passage means including stove means upstream of the communication with said vent tube means and associated with the engine exhaust system, whereby the ambient temperature response of said modulating means is at least in part controlled by engine operating temperature as reflected by exhaust system temperature.

Claim 12

In an internal combustion engine carburetor having a source of fluid fuel, a fuel metering orifice communicating with said fuel source, a fuel atomizing orifice, and a fuel flow passage between said orifices, the combination with said carburetor of an air-fuel mixing chamber in said fuel flow passage, a source of bleed air, and bleed air passage means from said bleed air source to said mixing chamber for conducting a stream of bleed air into said mixing chamber wherein the bleed air becomes mixed with the fuel so that a mixture of fuel and bleed air passes through the atomizing orifice, and bleed air flow modulating means associated with said bleed air passage means, said modulating means being responsive to ambient temperature changes to tend to increase the flow of bleed air to said mixing chamber in response to a temperature increase and decrease the flow of bleed air to said mixing chamber in response to a temperature decrease, said modulating means including vent tube means communicating with said bleed air passage means so as to vent a portion of the bleed air from said bleed air passage means and thereby decrease the flow of bleed air to said mixing chamber, said bleed air passage means having a restricted orifice therein, upstream of the communication with said vent tube means so as to limit the total amount of bleed air flow.

Claim 13

In an internal combustion engine carburetor having a source of fluid fuel, a fuel metering orifice communicating with said fuel source, a fuel atomizing orifice, and a fuel flow passage between said orifices, the combination with said carburetor of an air-fuel mixing chamber in said fuel flow passage, a source of bleed air, and bleed air passage means from said bleed air source to said mixing chamber for conducting a stream of bleed air into said mixing chamber wherein the bleed air becomes mixed with the fuel so that a mixture of fuel and bleed air passes through the atomizing orifice, and bleed air flow modulating means associated with said bleed air passage means, said modulating means being responsive to ambient temperature changes to tend to increase the flow of bleed air to said mixing chamber in response to a temperature increase and decrease the flow of bleed air to said mixing chamber in response to a temperature decrease, said modulating means including vent tube means communicating with said bleed air passage means so as to vent a portion of the bleed air from said bleed air passage means and thereby decrease the flow of bleed air to said mixing chamber, said bleed air passage means having a restricted orifice therein, upstream of the communication with said vent tube means so as to limit the total amount of bleed air flow.

Claim 14

In an internal combustion engine carburetor having a source of fluid fuel, a fuel metering orifice communicating with said fuel source, a fuel atomizing orifice, and a fuel flow passage between said orifices, the combination with said carburetor of an air-fuel mixing chamber in said fuel flow passage, a source of bleed air, and bleed air passage means from said bleed air source to said mixing chamber for conducting a stream of bleed air into said mixing chamber wherein the bleed air becomes mixed with the fuel so that a mixture of fuel and bleed air passes through the atomizing orifice, and bleed air flow modulating means associated with said bleed air passage means, said modulating means comprising temperature responsive valve means.

Claim 15

In an internal combustion engine carburetor having a source of fluid fuel, a fuel metering orifice communicating with said fuel source, a fuel atomizing orifice, and a fuel flow passage between said orifices, the combination with said carburetor of an air-fuel mixing chamber in said fuel flow passage, a source of bleed air, and bleed air passage means from said bleed air source to said mixing chamber for conducting a stream of bleed air into said mixing chamber wherein the bleed air becomes mixed with the fuel so that a mixture of fuel and bleed air passes through the atomizing orifice, and bleed air flow modulating means associated with said bleed air passage means, said modulating means comprising temperature responsive valve means.

Claim 16

Apparatus as defined in claim 11, wherein said temperature responsive valve means is responsive, at least during cold start and warm-up engine operating conditions, to ambient temperature changes to increase the flow of bleed air to said mixing chamber in response to a temperature increase.

Claim 17

In an internal combustion engine carburetor having a source of fluid fuel, a fuel metering orifice communicating with said fuel source, a fuel atomizing orifice, and a fuel flow passage between said orifices, the combination with said carburetor of an air-fuel mixing chamber in said fuel flow passage, a source of bleed air, and bleed air passage means from said bleed air source to said mixing chamber for conducting a stream of bleed air into said mixing chamber wherein the bleed air becomes mixed with the fuel so that a mixture of fuel and bleed air passes through the atomizing orifice, and bleed air flow modulating means associated with said bleed air passage means, said modulating means being responsive to air-fuel ratio changes in the carburetor output to tend to increase the flow of bleed air to said mixing chamber in response to a decrease in said air-fuel ratio and decrease the flow of bleed air to said mixing chamber in response to an increase in said air-fuel ratio.

Claim 18

In an internal combustion engine carburetor having a source of fluid fuel, a fuel metering orifice communicating with said fuel source, a fuel atomizing orifice, and a fuel flow passage between said orifices, the combination with said carburetor of an air-fuel mixing chamber in said fuel flow passage, a source of bleed air, and bleed air passage means from said bleed air source to said mixing chamber for conducting a stream of bleed air into said mixing chamber wherein the bleed air becomes mixed with the fuel so that a mixture of fuel and bleed air passes through the atomizing orifice, and bleed air flow modulating means associated with said bleed air passage means, said modulating means being responsive to air-fuel ratio changes in the carburetor output to tend to increase the flow of bleed air to said mixing chamber in response to a decrease in said air-fuel ratio and decrease the flow of bleed air to said mixing chamber in response to an increase in said air-fuel ratio.

Claim 19

Apparatus as defined in claim 13, wherein said modulating means comprises thermally responsive valve means controlling the flow of bleed air to said mixing chamber, oxidation reaction means thermally related to said valve means to actuate the latter, and exhaust passage means connecting the engine exhaust system to said reaction means providing a flow sample of exhaust to said reaction means for oxidation of combustible ingredients therein to produce a thermal response corresponding to the richness of the carburetor mixture for actuating said valve means.

Claim 20

Apparatus as defined in claim 14, wherein said oxidation reaction means comprises first and second oxidation reaction units each of which receives a portion of said exhaust flow sample, and means for adding air to said portion received by said second unit, the oxidation reactions in said first and second units producing respective temperatures T and Ta, said thermal response for actuating said valve means generally corresponding to the temperature differential Ta - T.

Claim 21

Apparatus as defined in claim 15, wherein said oxidation reaction units comprise catalyst converters.

Claim 22

Apparatus as defined in claim 15, wherein said valve means is arranged to control the flow of bleed air to the mixing chamber by adjustably venting a portion of the bleed air from said bleed air passage means.

Claim 23

Apparatus as defined in claim 17, wherein said valve means is arranged to vent less bleed air causing more bleed air to flow to the mixing chamber in response to an increase in Ta - T which indicates a richening of the mixture, and to vent more bleed air causing less bleed air to flow to the mixing chamber in response to a decrease in Ta - T which indicates a leaning of the mixture.

Claim 24

Apparatus as defined in claim 17, wherein said valve means comprises first and second valves thermally associated with the respective first and second oxidation reaction units, each of said valves being arranged to adjustably vent a portion of the bleed air from said bleed air passage means, said first valve tending to open with an increase in T and close with a decrease in T, and said second valve tending to open with a decrease in Ta and close with an increase in Ta, whereby the effect of said valves on the flow of bleed air to the mixing chamber is cumulative, an increase in Ta and decrease in T corresponding to a richening of the mixture causing both valves to tend to close and thereby vent less bleed air and cause more bleed air to pass to the mixing chamber to tend to lean the mixture, and conversely a decrease in Ta and increase in T corresponding to a leaning of the mixture causing both valves to tend to open and thereby vent more bleed air and cause less bleed air to pass to the mixing chamber to tend to richen the mixture.

Claim 25

Apparatus as Defined in claim 19, wherein said first valve is arranged to be substantially completely closed in a low ambient temperature range corresponding to cold start and warm-up engine operating conditions, whereby said second valve will control the flow of bleed air to the mixing chamber in such temperature range, gradual closing of said second valve as ambient temperature increases through such range resulting in a corresponding gradual increase in the flow of bleed air to the mixing chamber to gradually lean the mixture.

Claim 28

The method of claim 21, wherein the rate of flow of said stream of bleed air is adjusted generally inversely according to the rate of air flow, being decreased with an increase in air flow and increased with a decrease in air flow, whereby to provide a substantial improvement in fuel atomization at low speed operating modes, while accommodating greater fuel flow during high speed operating modes when atomization is normally good.

Claim 29

The method of claim 22, wherein said adjustment of the rate of bleed air flow is accomplished by providing said bleed air from a source thereof which has a pressure generally inversely related to the rate of air flow through the carburetor.

Claim 30

The method of claim 23, wherein said source is a downstream facing pick-up opening in the carburetor air intake stream.

Claim 31

The method of claim 21, wherein said varying of the flow of bleed air is at least in part responsive to ambient temperature variations to increase the rate of bleed air flow with a temperature increase and decrease the rate of flow with a temperature decrease, to compensate at least in part for the natural tendency of a carburetor mixture to richen with a rise in ambient temperature.

Claim 34

The method of claim 26, which includes heating the stream of bleed air upstream of said venting in response to engine exhaust system temperature, so that said modulation is at least in part responsive to engine operating temperature variations.

Claim 35

The method of claim 27, wherein the stream of bleed air is passed through a restricted orifice upstream of said venting, so as to render the flow of bleed air upstream of said venting generally insensitive to aMbient temperature changes.

Claim 38

The method of claim 29, wherein the flow of bleed air is modulated by adjustably venting a portion of the bleed air from said stream thereof.