Walbro Corporation

Walbro Engine Management, L.l.c.

Dale P Kus

David L Thomas

Martin N Andersson

William E Galka

Cyrus M Healy

Michael P Burns

Kevin L Williams

Paul S Learman

Anthony M Kueffner

In at least some implementations, a charge forming device includes a body having a main bore, a fuel metering assembly including a diaphragm that defines at least part of a fuel chamber from which fuel is provided to the main bore and a reference chamber separate from the fuel chamber, a passage communicated with a subatmospheric pressure source and with the reference chamber, and an electrically actuated valve having an open position and a closed position, and wherein the valve at least substantially prevents communication of the pressure source with the reference chamber when the valve is in the closed position and permits communication of the pressure source with the reference chamber when the valve is in the open position to vary the rate of fuel flow from the fuel chamber.

Fuel control system

In at least some implementations, a method of controlling a fuel-to-air ratio of a fuel and air mixture supplied to an engine, includes the steps of determining an engine deceleration event, determining the number of engine revolutions required for the engine speed to decrease from one speed threshold to another speed threshold, comparing the number of engine revolutions determined above against a revolution threshold, and making the fuel and air mixture richer if the number of engine revolutions determined above is greater than the revolution threshold. The method may also include determining if, before the engine stabilized at a stable engine speed (which may be an engine idle speed), the engine speed decreased below the stable engine speed as the engine decelerated to the stable engine speed from a speed above the stable engine speed, and making the fuel and air mixture leaner if the determination is affirmative.

Engine fuel supply control strategy

In at least some implementations, a solenoid valve includes a housing, a bobbin and an armature. The bobbin is received at least partially within the housing and has a body about which a coil is provided. A fluid flow path including an inlet and an outlet and a valve seat is defined by at least one of the housing or the bobbin, and the armature is moveable relative to the valve seat to control flow through the fluid flow path.

Solenoid valve

A solenoid valve includes a housing, a bobbin and an armature. The bobbin is received at least partially within the housing and has and internal passage and a body about which a coil is provided. The armature is moveable relative to a valve seat and the valve includes an armature stop received in the internal passage with a press-fit so that it is engaged by the armature in one position of the armature to limit movement of the armature away from the valve seat. The valve also has a biasing member located at least partially between the armature and the armature stop, the armature has a reduced diameter portion received at least partially within the biasing member, and wherein the reduced diameter portion engages the armature stop in the open position of the valve.

Solenoid valve with armature stop

A utility engine air-to-fuel ratio control method in which during an initial or early part of a period of engine continuous operation its stability of operation is determined and if sufficiently stable a test of the air-to-fuel ratio of the air-fuel mixture supplied to the engine is performed and if need be changed to a new air-to-fuel ratio supplied to the engine during the remainder of the period of engine continuous operation. If the engine operation is not sufficiently stable the test is not started or if started is aborted.

Engine self-adjustment system

A solenoid valve includes a housing, a bobbin and an armature. The bobbin is received at least partially within the housing and has a body about which a coil is provided. A fluid flow path including an inlet and an outlet and a valve seat is defined by at least one of the housing or the bobbin, and the armature is moveable relative to the valve seat to control flow through the fluid flow path.

Low cost solenoid valve

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

In at least some implementations a carburetor may include a main bore through which a fuel and air mixture is delivered from the carburetor, a fuel metering assembly, a supplemental fuel pump and a valve. The supplemental fuel pump includes a diaphragm that defines a fuel chamber on one side from which fuel may be discharged to at least temporarily increase the amount of fuel discharged from the carburetor and a reference chamber on the other side that is communicated with a reference pressure source. The valve is electrically actuated and moveable between first and second positions to at least substantially prevent communication of the reference pressure source with the supplemental fuel pump diaphragm when the valve is in its second position to thereby inhibit or prevent fuel being discharged from the fuel chamber.

A fuel injection system for a two-stroke small engine has a charge forming device with an injector mixing passage which forms a rich fuel and air mixture supplied to a tuned injector tube connected adjacent one end through a port to the engine cylinder and adjacent the other end to the engine crankcase. The charge forming device has a high speed fuel circuit which supplies at least a majority of the fuel to the mixing passage under wide open throttle operating conditions and preferably a minor portion of the fuel is also supplied by an idle fuel circuit which under engine idle conditions preferably supplies essentially all of the fuel to the engine. A separate inlet air flow passage of the charge forming device also supplies primarily air to the crankcase of the engine for transfer to the cylinder. Under engine wide open throttle conditions, preferably a very minor quantity of fuel with oil therein is supplied through the inlet air flow passage to the crankcase and transferred to the cylinder to provide lubrication of the moving parts in the crankcase and some cooling of the engine.

Small engine fuel injection system

A fuel mixture adjusting and limiting device for a carburetor has a body received in a bore of the carburetor and defining a fuel passage through which liquid fuel is supplied to the high and/or low speed system of the carburetor, an inlet opening in the body through which fuel enters the fuel passage from a metering chamber of the carburetor and a metering pin slidably carried by the body and capable of at least partially restricting the flow of fuel through the inlet opening to control the flow rate of fuel through the body. An adjustment screw threadably received in the bore of the carburetor is rotatable to axially displace the adjustment screw and during at least a portion of the axial range of movement of the adjustment screw, the adjustment screw bears on the metering pin to axially displace the metering pin and thereby control the flow area of the inlet opening. Preferably, the adjustment screw carries an adjustment pin which is axially displaceable relative to the adjustment screw and constructed to engage the metering pin to displace it. The axial location of the adjustment pin relative to the adjustment screw can be varied to alter the relationship between the adjustment screw and the metering pin.

Growing community of inventors

Cass City, MI, United States of America

Dale P Kus