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US 7,028,993 B2Granted
Charge forming apparatus
AssigneeWalbro Engine Management, L.L.C.
InventorMicahel P. Burns
Life of this patent
Estimating the term…
Abstract
A charge forming apparatus for delivering a controlled mixture of fuel-and-air to an engine has a butterfly-type throttle-choke valve disposed in a fuel-and-air mixing passage. Incoming air flowing through a downstream primary venturi of the mixing passage creates a strong negative pressure which induces fuel flow through a feed passage into the venturi from a fuel metering chamber held at near atmospheric pressure. When the engine is decelerating, substantial closure of the choke valve creates a secondary venturi having a vacuum which dynamically counters the effect of the primary venturi vacuum reducing fuel flow through the feed passage and causing the engine to run leaner and preventing egine stalls and reducing emmissions.
Claims22
A charge forming apparatus for a combustion engine comprising:
- a body;
- a fuel-and-air mixing passage defined by the body, the mixing passage having a venturi region disposed between an air inlet region and a mixture outlet region, wherein air flows from a near atmospheric air source through the air inlet region and into the engine from the mixture outlet region;
- a throttling choke valve disposed in the air inlet region of the mixing passage, the throttling choke valve having a closed position for starting of the engine, an idle position and a full open position;
- a flexible diaphragm having a first surface, an opposite second surface, and a peripheral edge;
- a fuel metering chamber defined between the body and the first surface;
- a fuel feed passage communicating between the fuel metering chamber and the venturi region of the mixing passage, wherein liquid fuel flows into the venturi region for mixing with air flowing from the air inlet region;
- a cover;
- a reference chamber defined between the second surface and the cover, wherein the peripheral edge is engaged sealably between the cover and the body;
- a reference passage communicating between the reference chamber and the air inlet region downstream of the throttling choke valve when in the idle position;
- an air bypass channel communicating between the near atmospheric air source and the mixing passage downstream of the choke valve;
- and
- wherein the air bypass channel is dry and communicates directly with the mixture outlet region of the mixing passage and wherein the charge forming apparatus does not have a fuel idle circuit at the outlet region.
9 more elements
A charge forming apparatus for an internal combustion engine comprising:
- a body;
- a fuel-and-air mixing passage defined by the body, the mixing passage having a venturi region disposed between an air inlet region and a mixture outlet region, wherein air flows from a near atmospheric air source through the air inlet region and into the engine from the mixture outlet region;
- a throttling choke valve disposed in the air inlet region of the mixing passage, the throttling choke valve having a closed position for starting of the engine, an idle position and a full open position;
- a flexible diaphragm having a first surface, an opposite second surface, and a peripheral edge;
- a fuel metering chamber defined between the body and the first surface;
- a fuel feed passage communicating between the fuel metering chamber and the venturi region of the mixing passage, wherein liquid fuel flows into the venturi region for mixing with air flowing from the air inlet region;
- a cover;
- a reference chamber defined between the second surface and the cover, wherein the peripheral edge is engaged sealably between the cover and the body;
- a reference passage communicating between the reference chamber and the air inlet region downstream of the throttling choke valve when in the idle position;
- and
- an isolation valve constructed and arranged to vent the reference chamber to the near atmospheric air source when the throttling choke valve is not in the idle position.
8 more elements
A carburetor for an internal combustion engine comprising:
- a body;
- a fuel-and-air mixing passage defined by the body, the mixing passage having a venturi region disposed between an air inlet region and a mixture outlet region, wherein air flows through the inlet region and into the engine from the outlet region;
- a throttling choke valve disposed in the inlet region of the mixing passage, the throttling choke valve having a closed position for starting of the engine, an idle position and a full open position;
- a fuel metering system for flowing liquid fuel via a fuel feed passage to the venturi region, said fuel metering system comprising a flexible diaphragm positioned between a fuel metering chamber and a dry reference chamber;
- a reference passage comprising a reference nozzle communicating between the fuel metering system and the air inlet region downstream of the throttling choke valve when in the idle position;
- and
- wherein fuel flow through the fuel feed passage is reduced, but not stopped, when said dry reference chamber of the fuel metering system is exposed to negative pressure via the reference passage by movement of said throttling choke valve toward said reference nozzle.
4 more elements
A The charge forming apparatus for a combustion engine comprising:
- a body;
- a fuel-and-air mixing passage defined by the body, the mixing passage having a venturi region disposed between an air inlet region and a mixture outlet region, wherein air flows through the inlet region and into the engine from the outlet region;
- a throttling choke valve disposed in the inlet region of the mixing passage, the throttling choke valve having a closed position for starting of the engine, an idle position and a full open position;
- a fuel metering system for flowing liquid fuel via a fuel feed passage to the venturi region;
- a reference passage communicating between the fuel metering system and the air inlet region downstream of the throttling choke valve when in the idle position;
- wherein fuel flow through the fuel feed passage is reduced, but not stopped, when a dry reference chamber of the fuel metering system is exposed to negative pressure via the reference passage;
- an air bypass channel communicating between the air inlet region upstream of the throttling choke valve and the mixture outlet region of the mixing passage;
- and
- an air bypass screw engaged threadably to the body and projecting adjustably into the air bypass channel for adjusting the air flow bypassing the throttling choke valve and the venturi region of the mixing passage.
6 more elements
A charge forming apparatus for a combustion engine comprising:
- a body;
- a fuel-and-air mixing passage having a venturi region disposed downstream of an air inlet region defined by a wall carried by the body;
- a throttling choke valve disposed pivotally in the air inlet region;
- a fuel metering system for flowing fuel via a fuel feed passage to the venturi region, wherein a negative pressure created in the venturi region promotes fuel flow through the fuel feed passage;
- a reference passage communicating between the fuel metering system and the air inlet region downstream of the throttling choke valve, said reference passage comprising a reference nozzle;
- a secondary venturi disposed upstream of the venturi region and defined by the throttling choke valve and the wall when said throttling choke valve moves toward said reference nozzle;
- and
- wherein a negative pressure created at the secondary venturi is transmitted to the fuel metering system via the reference passage for limiting fuel flow through the fuel feed passage.
5 more elements
A charge forming apparatus for an internal combustion engine comprising:
- a body
- a fuel-and-air mixing passage defined by the body, the mixing passage having a venturi region disposed between an air inlet region and a mixture outlet region;
- a throttling choke valve disposed in the air inlet region of the mixing passage, the throttling choke valve having a closed position for starting of the engine, an idle position and a full open position;
- a fuel metering system for flowing fuel via a fuel feed passage to the venturi region;
- a reference passage communicating between the fuel metering system and the air inlet region downstream of the throttling choke valve when in the idle position wherein a negative pressure is applied to the fuel metering system via the reference passage for limiting fuel flow through the fuel feed passage when the throttling choke valve is in the idle position;
- and
- a minimum cross sectional flow area of the fuel feed passage being substantially larger than a minimum cross sectional flow area of the reference passage for providing a rich mixture of fuel-and-air to the combustion engine during cold start conditions.
4 more elements
Dependencies are inferred from the claim text.