US1987981A - Carburetor level governing device - Google Patents

Description

P. s. TICE 1,987,981

CARBURETOR LEVEL GOVERNING DEVICE Filed April 7, 1930 Jan. 15, 1935.

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Patented Jan. 15, 1935 OABBURETOB LEVEL GOVERNING DEVICE Percival s. Tice, Chicago, 111., assignor to Stewart- Warner Corporwtion, Chicago, 111., a corporation of Virginia Application April 7, 1930, Serial No. 442,108

1 Claim.

The purpose of this invention is to provide an improved device for governing the level of the fuel in the fuel chamber of a carburetor of the type having a fuel chamber constituting immediate 5 source of fuel supply, and from which the fuel is taken by engine suction to the mixing chamber of the carburetor, as in familiar carburetor constructions.

In a carburetor of this type in which it is essential for maintenance of the fuel mixture proportions suitable to varying engine running condi tions, that the liquid head in the fuel chamber shall be substantially uniform, the wide variation in the instant demand for fuel which results from throttle changes and change of engine speed tends to defeat the maintenance'of uniform level and liquid head in the liquid chamber.

For example, upon sudden increase of suctiondue to opening of the throttle more widely after a period of idling, the quantity of fuel sucked out of the fuel chamber or float bowl, tending to lower the fuel level a substantial amount, is not replaced as fast as it is taken out, this delay being.

the liquid in the float chamber and the float, said inertia operating to delay the valve-operating movement in response to the suction impulse from the engine; and this delay occurs even though the pressure by which the fuel is supplied to the float bowl is suflicient to deliver the fuel as rapidly as it can be sucked out by the engme.

From these considerations it is evident that the defective operation cannot be avoided while the construction is such that the degree of opening of the valve corresponds to the movement of the float due to change of level. And this consideration points to the remedy consisting in providing means for giving the valve instant maximum operation (or increase of opening) when it is opened at al1,-or its opening is increased,-in response to increase .of engine demand.

Accordingly, for the accomplishment of the purpose of the present invention, it is directed to relieving the float of the direct duty of opening the valve by the float movement, and consists in adequate for maximum opening of the valve without sensible delay.

The float is relieved of this duty in the present construction by providing for the performance of that duty an electromagnetic means for operating the valve, which is rendered operative for that purpose by controlling the electric circuit in which the magnet element is energized, the float being utilized for this purpose, and accordingly having only the light duty of moving the circuit-opening-and-closing contact, which is of negligible weight and held normally in either position bythe negligible spring or gravity force, which requires to be moved for opening and closing the circuit an almost unappreciable distance, not exceeding for perfect certainty of operation .001 inch.

In the drawing:

Figure 1 is a partly diagrammatic sectional view of a carburetor equipped with this invention, in a plane axial with respect to the engine intake passage, and

- Figure 2 is a detail section at the line 2--2 on Figure 1.

Referring to the drawing in detail the engine intake is indicated at A; the carburetor body is indicated at B, having the main inflow passage seen at b. The fuel chamber or float bowl indicated in totality at C, has at 20 a pipe connection leading from the fuel source, and said fuel chamber formed widely open at the'bottom for convenience of introducing the structural elements here:

inaiter described, is closed at said bottom opening by a plug, 21, and the actual'bottom of the fuel containing cavity of the chamber is formed by a plug member, 22, entered through the opening closed by the plug, '21,.and screwed into the body at a point above the inlet, 20, said plug member, 22, having the inlet port, 23, controlled by the valve hereinafter described, said port, 23,1cading to a plurality of lateral discharge ports, 24, above the seat of the valve at the upper end of the rectly inleading port, 23. Mounted fixedly upon the plug member, 22, which has the inlet port as described, there is provided a solenoid structuie comprising the spool, 25, about which the circuit windings. 26, are coiled within the protecting sheath, 2?. in the'axial cavity of the solenoid spool, 25, which it in axial alignment with the inlet port, 23, there may be seen the movable core armature member, 28, occupying the lower part of the axial cavity of the spool, at the upper part of which may be seen a fixed core member, 29. The movable armature core member, 28, is axiaily bored from the upper end for a greater portion of its length to accommodate a spring, 31, reacting at its lower end on the movable armature and the valve, 30, attached rigidly to the latter; and said spring reacts at the upper end upon the fixed core member, 29; so that the spring operates for holding the valve, 30, normally seated at the inlet port, 23, subject to opening for the pressure of the fuel supply arriving through the pipe connection, 20, and inlet port, 23.

The solenoid structure described is only slightly less in diameter than the chamber, C, and the latter may therefore be of small diameter, and the fluid capacity of the chamber at the portion thereof at which the solenoid structure described is located, is very limited, the chamber being extended above the solenoid for fluid capacity suitable for buoying the float, 40, which is shown therein, having its stem, 41, connected at its lower end to a slender flat spring, 42,which forms part of an electric circuit comprising the binding post, 43, mounted insulatedly in the lateral wall of the chamber, C, and the circuit wire, 44, leading to a source of current, indicated conventionally at X, and shown grounded at X The remainder of the circuit comprises a contact button, 50, carried at the end of the light spring, 42, which is normally held in contact with a cooperating contact button, 51, mounted insulatedly at the upper end of the solenoid spool and connected, as shown at 53, with the inner end of the solenoid windings at the upper end of the spool, said windings being grounded by the connection of the outer lower end with the mounting structure, as indicated conventionally at 55.

Upon considering the construction described, it

a may be understood that the spring, 31, is conditioned for reacting on the valve, 30, with suflicient force to hold the valve seated against the pressure by which the fuel is supplied from the fuel source, and that when the chamber, C, is empty, the float being not buoyed, is holding the contact, 50, in circuit-closing contact with the contact, 51, so that the magnet element of the solenoid, comprising the movable armature member, 28, is energized and drawn into the solenoid spool, carrying the valve, 30, to open position, admitting the fuel which fills the chamber, C, eventually submer ing the float to a depth, causing it to be buoyed and lifted, breaking the contact between the contacts, 50, and 51, opening the circuit, de-energizing the magnet elements of the solenoid and permitting the valve, 30, to be seated by the reaction of the spring, 31.

. As above mentioned, the distance which the contacts, 50 and 51, are separated for opening the circuit is very small indeed, and the movement of the float for opening and closing the circuit is correspondingly slight; and the spring bar, 42, which carries the contact, 50, is very light because the stifiness required is only sufficient to sustain the weight of the contact, 50, and acmeager cordingly the float may be very small, since the duty required of it is only to lift the weight of the contact, 50, in which it is assisted by the reactionof the flat spring by which the contact, 50, is carried. The small size of the float, which permits it to be of small diameter permits the chamber, C, to be of correspondingly small diameter,--only enough greater than the diameter of the float to afiord clearance for the liquid around the float without undue friction,-and the very short movement required of the float permits the chamber to be of correspondingly limited vertical. dimension. The small size of the float reducing its inertia, and the small capacity of the chamber reducing the inertia of the liquid which is moved in the movement of the float, operates for promptness in the response of the moving parts to the fuel demand of the engine, so that the change oi level of the liquid due to sudden increase of demand as upon the opening of the throttle after a period of idling, is scarcely more than the movement of the contact, 50, for opening and closing the circuit; and accordingly upon the intake stroke of the engine occurring at the opening of the throttle the valve, 30, opening instantly, permits the fuel to be taken through the fuel discharge ports, 23 and 2%, directly from the supply line, fuel being drawn in through the port, 23,

rather than being withdrawn from the chamber, C, so that the liquid head in the chamber, C, which is the measure of the pressure on the discharge nozzle remains substantially unchanged throughout all varying running conditions and varying opening of the throttle.

It will be recognized upon consideration of the principle of this invention as embodied in a carburetor of the type shown in Figures 1 and 2 having float control, that the invention is applicable to a carburetor controlled by. any equivalent means.

I claim:

In an apparatus for supplying fuel to an internal combustion engine, a conduit through ,which the liquid is conducted for discharge, a

chamber constituting the immediate source of liquid having its liquid containing cavity leading to the levelcf the discharge of the conduit, a magnetically controlled inlet valve controlling the flow of liquid into said chamber arranged for opening in the direction of liquid inflow, means arranged for holding said valve normally seated against the inflow pressure, an electromagnet. mounted in the chamber for operating it in opposition to said means so that when the magnet is energized the valve may be opened, an electric circuit in which the magnet is energized comprising a contact movable for opening and closing the circuit, and a float in said chamber responsive by its movement to change of depth of the liquid content of the chamber, said float being operatively associated with said contact for holding the latter out of circuit-closing position when the liquid content of the chamber reaches a predetermined depth, said float being located above the electromagnet and having said contact located between the float and the electromagnet.

' PERCIVAL S. TICE.

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