US2019172A - Carburetor - Google Patents

Description

Oct. 29, 1935. M. E. CHANDLER CARBURETOR Filed July 22, 1930 I N VEN TOR. Man/v 5 [HQ/V04 m Patented Get. 29, 1935 URETOE Milton a. Chandler, South Bend, ma, mor

1 to Bendix Stromberg Carburetor Company,

South Bend, Ind., a corporation of 015 Application July 22, 1930. Serial No. 469,721 comma. (or. 123-119) This invention relates to carburetors for automobile engines and more particularly has reference to throttle controlling devices therefor.

When an automobile engine is operated at wide open throttle, or very nearly so, and the clutch is thrown out and the carburetor returned to idle, the engine sometimes stalls because of the mixture being too rich. The reason for this trouble seems to be that during wide open throttle operation, there is nearly full atmospheric pressure in the intake manifold and usually a film of liquid fuel, amounting to several cylinder charges, adheres to the manifold walls. When the throttle-is then suddenly closed, the air pres- 5 sure in the manifold is suddenly reduced considerably and the liquid fuel film immediately flashes into a vapor; this at a time when very little air is being admitted through the idling throttle opening, so that the mixture is momentarily overenriched.

The object of this invention is to obviate the above difilculty by allowing the throttle to close at its normal speed to a point where the speed of the engine is properly decreased, and then retarding the further movement of the throttle to the idling position. Thus, I have found that if the throttle is returned at its normal rate to. say a twelve miles an. hour position, and then returned at a slow rate to extreme idle, stalling of the engine can be prevented.

with this and further objects in view which may be incident to my improvements, my invention consists in the combination and arrangement of elements hereinafter described and illustrated in the accompanying drawing, in which:

Figure 1 is a small scale side elevation of the accelerator pedal of an automobile and a larger scale section of a carburetor barrel and float chamber;

Figure 2 is a fragmentary section on an enlarged scale of a modified form of dash pot.

Referring particularly to Figure 1, the reference numeral I designates a carburetor having the usual barrel 2, in which is mounted a butterfly throttle valve 3 to control the flow through the carburetor. A shaft 5, carrying throttle valve 3, is journalled in the walls of barrel 2 and carries at one end outside said barrel fixed arms 6 and 1, the former connected by a rod 8 to a spring-retracted accelerator pedal 9, and the latter by a link I!) to a, piston ll operating in a dash pot l2 interposed between the carburetor barrel 2 and a liquid fuel supply chamber 13. Piston II has a slidable fit in dash-pot l2 and is provided with a p urality of channels it which the wall between dash-pot I2 and floatchamber 5 it, there is provided a by-p'ass channel Hi, the upper outlet of which is above the normal travel of piston ii and the lower outlet of which opens into -P t 82 at it point where it is desired to retard the piston on its downward strokeflq Dash-pot -12 communicates at its bottom with float chamber it through an interchangeable, calibrated metering restriction ll. This not only permits the supply of retarding fluid (gasoline) to enter the dash-pot at all times, but fixes the 15 rate of retardation of piston Ii and by substituting restrictions with difierent bores, this rate may be properly regulated.

In Figure 2, I have shown a modification in which the piston it carries no check valve, but 20 in lieu thereof is provided with a central bare. it which fits over and receives a stud i9 screwthreaded into the bottom of dash-pot l2 where the piston reaches the lower end of its stroke.

Stud it serves as a guide post for an annular 25 plate 2!) which reciprocates thereon and is normally held against the head of the stud l9 by an encircling spring M in a position in dashpot i2 corresponding to. the lower outlet of bypass it in Figure 1. When piston ll contacts so with plate 2d on its downward stroke, the circulation of liquid through channels it is cut oil and the piston then descends against the pressure of spring 25 and the inertia of liquid below plate 2d escaping through restriction ll.

The operation of my device is apparent from the foregoing description. When the throttle is fully open, the accelerator pedal 9 is fully depr and the piston H is at the top of its stroke. all as shown in full lines in Figure 1. If 40 now the pedal 9 is released, its spring quickly changes the throttle to the partially closed, slow speed position shown in dotted lines in Figure 1.

At the same time piston ll descends to its dotted position, where it just cuts on the lower outlet 45 of by-pass it. This position of the throttle corresponds to an engine speed somewhat above idling, or approximately twelve miles an hour. In descending to the position shown in dotted lines in Figure l, the piston does not appreciably retard the closing of the throttle because of the .free circulation of liquid through by-pass l6.

Any slight retarding caused by the piston to this point can be overcome by increasing the tension 55 on the accelerator pedal spring so that the rate of closing of the throttle is unaifected.

,After reaching the position shown in dotted lines in Figure 1, tarded by the restricted rate at which the liquid trapped below the piston escapes through calibrated orifice l1, and the further closing of the throttle 3 is correspondingly retarded until it reaches its most restricted or idling position. I By this arrangement the throttle can return rapidly up to a position of about 12 from the extreme restricted position (corresponding to a speed of about twelve miles per hour), and from this point on, will return slowly, depending on the adjustment of the dash pot. By thus retarding the last part of the throttle closing, I avoid the over-enrichment of the mixture and stalling of the engine.

While I have shown and described the preferred embodiments of my invention, 1 do not wish to be limited to the constructional forms shown by way of illustration, as changes in combination and arrangement of elements may be made by those skilled in the art without departing from the spirit of my invention or exceeding the scope of the appended claims.

I claim:

1. In a carburetor, a throttle, a liquid fuel supply chamber, a dash-pot communicating with and supplied with liquid from said chamber through a calibrated metering restriction, a piston adapted to reciprocate in said dash-pot, a by-pass in in said dash-pot around said piston operative during the major part of its stroke, and a connection the descent of piston II is rethe greater part of its stroke and obstructs the bybetween said piston and throttle so that when said throttle is closed, said piston travels freely during the operation of said by-pass and then at a retarded rate dependent upon said metering restriction whereby said throttle closes at a rapid 5 rate during the major part of its closing movement and thereafter at a retarded rate.

2. In a carburetor, a throttle, a liquid fuel supply chamber, a dashpot communicating with and supplied with liquid from said chamber through a removable metering restriction at the bottom of the dashpot, a piston reciprocably mounted in the dashpot and connected to the throttle, a conduit in the dashpot by-passing the piston and terminating adjacent the lowermost position of the throttle above the metering restriction in such relation that when the throttle is moved to its closed postion the piston travels freely through pass to force liquid fuel through the metering restriction.

3. In a carburetor, a throttle, a liquid fuel reservoir, a dashpot supplied with liquid from the fuel reservoir, a piston reciprocably mounted in the dashpot and connected to the throttle, and 5 liquid conduits associated with the dashpot and arranged to cause the piston to force fuel against a relatively low resistance during a part of the closing movement of the throttle and to cause it to force fuel through a relatively high resistance during the remainder of the closing movement of the throttle.

MILTON E. CHANDLER.

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