Walbro Engine Management, L.l.c.

Walbro Corporation

Michael P Burns

George M Pattullo

Martin N Andersson

Gary U Gliniecki

Kevin P Born

James E VanAllen

David L Speirs

Dale P Kus

Paul S Learman

George M Parrullo

A carburetor including a body having a main bore through which a fuel and air mixture is discharged from the carburetor for use by an engine a priming passage communicated with the main bore, a pump that moves fluid into the priming passage, and a flow restrictor received within at least a portion of the priming passage to reduce the minimum effective flow area of the priming passage. The flow restrictor has a body received at least partially within the priming passage so that fluid flows around the flow restrictor and between the structure defining the priming passage and the flow restrictor.

Carburetor with low flow rate fluid passage

A purge and prime assembly for a carburetor includes a purge and prime pump that alternately takes in and discharges fluid, and a plurality of passages through which fluid is routed. The passages may include a purge passage through which fluid is drawn by the purge and prime pump, a return passage through which fluid is discharged from the purge and prime pump and discharged from the carburetor, and a priming passage through which a portion of the fluid discharged from the purge and prime pump is routed to a main bore of the carburetor. The assembly may also include a purge valve that prevents fluid from being discharged from the purge prime pump through the purge passage, and a return valve that prevents fluid in the return passage from being drawn into the purge and prime pump.

Carburetor fuel supply system

A control system for a low cost, light duty combustion engine, where the control system generally utilizes an engine speed input signal and independent operating sequences to determine a desired ignition timing. There are several independent operating sequences, each one of which is designed to optimally control the engine under certain conditions. These operating sequences include a Cranking sequence, a Warm Up sequence, a Normal Mode sequence, an Acceleration sequence, a Come Down sequence, a Recovery Bump sequence, and a Part Throttle sequence. During idling conditions, the Normal Mode sequence uses rapid changes in the ignition timing to maintain the engine speed in a small, idle engine speed range. By utilizing these operational sequences, the control system improves the performance of a low cost, light duty engine across a wide array of conditions.

Ignition timing control system for light duty combustion engines

A carburetor has an air intake passage, a fuel passage, a fuel nozzle in communication with the fuel passage and having an opening through which fuel flows, a first valve in communication with the air intake passage and being movable between first and second positions, and a second valve in communication with the fuel nozzle and also being movable between first and second positions to vary the effective flow area of the fuel nozzle. The fuel nozzle is preferably carried by a tube fitted sealably in a bore being in communication with the fuel passage. The opening is defined by the tube and is preferably elongated, extending axially with respect to the tube. A needle of the second valve moves axially within the tube to variably obstruct the opening to control fuel flow. Preferably, a method of manufacturing the tube utilizes a circular cutting tool which plunges into the tube cutting a slit as the opening having a sharp peripheral edge for atomizing the fuel.

Carburetor and method of manufacturing

An engine carburetor and a solenoid valve assembly therefor and methods of assembling the same. The carburetor has a body with a fuel and air mixing passage communicating with an air bleed passage. A cavity extends into the body for communication with the air bleed passage. A solenoid housing is received in the cavity and maintains a coil body for receipt of a valve body therein. The valve body moves between a retracted position to substantially open the air bleed passage and an extended position to substantially close the air bleed passage.

Carburetor and solenoid assemblies and methods of assembling the same

A priming and purging system and method for an internal combustion engine having a diaphragm carburetor includes a pump in fluid communication with the carburetor, a portion of the engine, and a fuel tank. The pump is manually actuatable to draw liquid fuel and any fuel vapors and gases from the carburetor and to deliver at least some liquid fuel into a portion of the engine to prime the engine and liquid fuel and any fuel vapor and gases toward and preferably into the fuel tank to facilitate purging the carburetor.

Priming and purging system and method for an internal combustion engine

A fuel needle valve assembly of a carburetor has a retainer which yieldingly restrains the rotational fuel flow setting capability of the needle valve. The retainer engages a shank of the needle valve and a parallel shaft, both of which project from the carburetor body. The retainer exerts a force which laterally displaces the projecting shank with respect to the shaft. The retainer has sufficient strength to ensure the factory set rotational setting of the fuel needle valve does not alter when a limiter cap is press fitted to a distal head of the needle. Furthermore, wherein the shaft is also a shank of a second needle valve, the same retainer laterally displaces the projecting shanks of both needle valves.

Carburetor valve rotational setting retainer assembly

A carburetor preferably of a diaphragm type for an internal combustion engine has a low speed circuit for starting and idling of a cold engine. An air bleed line of the low speed circuit communicates between an inlet of a fuel and air mixing passage of the carburetor and an emulsifying chamber of the low speed circuit. Fuel flows to the emulsifying chamber from a fuel metering chamber and is regulated by a low speed idling adjustment needle screw. The bleed air and the fuel mixes within the emulsifying chamber and flows into the mixing passage between the throttle valve and the outlet of the mixing passage. Promoting this flow is a high vacuum produced by cranking and idling of the engine and accentuated by the substantially closed throttle valve. The fuel-and-air mixture is rich during cold idling as a result of the closed air bleed line. When the engine warms up, the air bleed line is opened via the restrictor valve.

Carburetor vent control

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.

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Millington, MI, United States of America

Michael P Burns