US 6,267,102 B1 · Carburetor with displaced idle flow

Abstract

A single needle diaphragm type carburetor has a throttle valve in a mixing passage with a venturi, an idle fuel nozzle downstream of the throttle valve when in its idle position, a high speed fuel nozzle preferably disposed within the venturi upstream of the throttle valve and a supplemental air bleed passage opening into the mixing passage upstream of both the idle and high speed fuel nozzles. Both the idle and high speed fuel nozzles communicate with each other through a transfer passage and are fed from the same fuel circuit controlled by a single needle valve which limits the fuel flow to them. At idle or low speed and low load engine operation air supplied by the supplemental air bleed passage is mixed with fuel supplied to the idle fuel nozzle. At wide open throttle, air from the air bleed passage is routed near the idle fuel nozzle, and mixed with the fuel supplied to the high speed nozzle. The air routed adjacent to the idle nozzle dries out, reduces or eliminates the liquid fuel adjacent thereto such that upon come down of the engine from wide open throttle to idle, there is not an excessive amount of fuel available to the idle nozzle which would cause an over rich come down. Advantageously, the carburetor is readily adjustable with the single needle valve and provides improved performance of the engine throughout its operational range.

Claims16

Dependent claims

A carburetor, comprising:

a body;
a fuel and air mixing passage formed in the body and having a venturi portion;
a throttle valve in the fuel and air mixing passage movable between idle and wide open throttle positions;
at least one high speed fuel nozzle in the body opening into the mixing passage upstream of the throttle valve when in its idle position and in communication with the fuel and air mixing passage and the fuel chamber;
at least one low speed fuel nozzle in the body opening into the mixing passage downstream of the throttle valve when in its idle position and in communication with the fuel and air mixing passage and the fuel chamber;
a supplemental air passage open to the fuel air mixing passage at one end and communicated with both the low speed and high speed fuel nozzles through one or more passages, first with a passage generally adjacent to the low speed fuel nozzle and thereafter with a passage leading to the high speed nozzle whereby at least when the throttle valve is in its wide open throttle position air flowing through the supplemental air passage passes through said passage adjacent to the low speed fuel nozzle before being drawn through the high speed nozzle to reduce the liquid fuel adjacent to the low speed fuel nozzle which is not needed for engine operation at least when the throttle valve is rapidly moved from its wide open throttle position to its idle position.

3 more elements

A carburetor, comprising:

a body having a fuel chamber;
a fuel and air mixing passage through the body;
a throttle valve in the fuel and air mixing passage movable between idle and wide open throttle positions;
at least one high speed fuel nozzle in the body opening into the mixing passage upstream of the throttle valve when in its idle position and in communication with the fuel and air mixing passage and the fuel chamber;
at least one low speed fuel nozzle in the body opening into the mixing passage downstream of the throttle valve when in its idle position and in communication with the fuel and air mixing passage and the fuel chamber;
a single adjustable valve communicating with the fuel chamber and through which all fuel supplied to both the low and high speed fuel nozzles flows;
a transfer passage communicating with both the low and high speed fuel nozzles upstream of their respective openings into the mixing passage and downstream of the adjustable valve;
and
a supplemental air passage in the carburetor body communicating with the fuel air mixing passage upstream of the throttle valve when in its idle position and the low speed fuel nozzle upstream of its opening into the mixing passage to control the flow of air and fuel through the low speed fuel nozzle and high speed fuel nozzle to reduce the amount of liquid fuel immediately available to the low speed fuel nozzle when the throttle valve is wide open.

6 more elements

Dependencies are inferred from the claim text.

Carburetor with displaced idle flow

Life of this patent

Carburetor with displaced idle flow

Life of this patent

Abstract

Claims16