US2111855A - Automatic control for fuel mixing devices - Google Patents

Description

Marh22,193s.f W'GROH 2,111,855

AUTOMATIC CONTROL FOR FUL MIXING DEVICES Filed Dec. 3, 195e 7 11g/fred 5,04.

Patented Mar. 22, 1938 N UNlTEosTATEs PATENT OFFICE 2,111,855l AUTOMATIC CONTROL FOR FUEL MIXING DEVICES Wilfred Groh, Gravenhurst, Ontario, Canada Application December 3, 1936, Serial No. 113,967 Y,

' 12 claims.V (o1. 137-104) This invention'relates to improvements in carburetors or fuel mixing `devices and more particularly to means for thermostatically'controlling the ratio of fuel and `air in accordance with prevailing atmospheric temperatures.'

The principal object of vthis invention is to provide an improved form of mechanism which Vwill automatically control the level of the fuel `in theiioat chamber in relation to- "the fuel jet or jets in response to changes in atmospheric temperatures and to provide a formof device Afor this purpose which will function in a dependable manner and will not be subjected to detrimental hammering or vibratory actions whenl associated with a fuel feed supply of the widely used pulsating p-ump type. v

The principal feature of the invention resides inthe novel' construction andarrangement of parts Awherebythe valve means supplying fuel to the Vfloat bowl or chamber Vis Ythermostatically shifted in relation to the controlling float to regu- Alate the height at which the float willvclosevthe supply valve. Y i i Figure 1 is a mid-sectional elevational View of acontrolmechanism constructed in accordance with the present invention and incorporated -in a carburetor structure. f fr Figure 2 is a fragmentary sectional `view showing a modified arrangement of fuel circulating passages. I p Y Itis extremely desirable, particularly inthe operation of combustion engines of motor cars, to ensure 4a constant ratio of fuel and air being fedto' the engine irrespective of the wide-variations encountered in atmospheric temperatures.

This problem has been recognized for sometime 4and various means have been proposed in order to overcomethe diicultywith varying degrees of success. ,Y

It has been previously proposed toprovide thermostaticmeans forr automatically adjusting the choke to regulate the volume of air entering the engine and it has also been proposed to f thermostatically regulate the actual volume of fuel entering the jet of the-carburetor, but so far as I am aware I am the firstto propose a means whereby the actual levelof the fuel in the carburetor bowl or chamber is automatically regulated in accordance with prevailing temperatures asV a means of increasing or diminishing the amount of fuel drawn from the jet or jets in the operation of the engine. Y

While my invention is capable of Wide struc- `tural variation and adaptation, I have shown for purposes of illustration a simple form of apparatus constructed-in accordance with the present inventionandreferring to this illustrated construction, the float chamber I is shown provided with the usual fuel outlet 2 for conducting fuel to the jetor jets 3, which jet is shown disposed in lthe suction conduit 4 of the carburetor and encircled by a Venturi tube 5, the usual throttle being shown for controlling the volume of the `mixture passing tothe engine. Y

A cover member 'I is fitted to the upper end of the float chamber I and has a central opening in which a guide block 8 is seated and suitably secured in place, a vertical vguide bore 9J being provided therein for slidably receiving and'guiding a displaceable tube member IIJ.

The upper end of the block is provided with a'circular threaded flange I I to which an inverted cup-shaped housing I2 is threadedly secured, thereby forming a chamber above the block 8 into'.y which the upperend of the tube I0 extends.

"A `bellowsmember I3 here shown of deeply corrugatedform has .the upper end closed and :operatively secured to the upper extremity. of the tube I0 and the lower end of the bellows is suitably sealed to the flange II preferably by-being `soldered into a groove therein as shown at I4.

The space between the element I3` and the casing I2 forms a chamber I5, which, according to `the present invention, I propose to fill, with .mercury,valcoliol or any other suitable fluid medium `having the desired characteristics of eX- pansion and contraction in response to temperature changes' and this fluid medium may be introduced'through the opening I6 in the top 'which will then be sealed by a suitable screw'plug IT.

I preferably completelyll the chamber I5 to the exclusion of all air so that any expansion of the fluid'medium will effect a positive and non- 'yielding' downward displacement of the tube I0 `:and such lling preferably is accomplished with the fluid medium at a temperature*substantially corresponding to the temperature'V of the surrounding atmosphere and that ofthe structure.

The housing I2 is here shown provided with heat exchange finsadapted to contact extensively with the vatmosphere as a means of encour- [aging the conduction of heat to and from the atmosphere and the fluid medium in the chamber I5', and as a means of changing the actual volumetric capacity of the chamber I5, I have shown fa rubber or other resilient sealing ring I2 interposed between the flange II and bottom of the cylindrical housing I2 which will retain an effective seal at this point, while permitting threaded adjustingthe casing I2 to therebyeii'ect changes Yand. associated parts.

in the volume of the chamber I5 as a means of effecting an adjustment of the vertical positioning of the tube I0.

A fuel supply tube I8 directs fuel into a vertical passage I9 in the block 8, which passage leads upwardly into the interior of the bellows I3 and downwardly into the interior of a second and smaller bellows 2U, which is here shown sealed at its upper end to the lower flange II of the block, while The lower end of the bellows 20 has the tube I extending therethrough and sealed thereto as indicated at 2|.

The fuel thus entering the lower bellows 20 is allowed to pass into the tube I0 by way of the ports 22 therein and the fuel flows from the lower end of the tube I0 in a controlled manner as hereinafter defined.

'Ihe lower end of the tube I Il has mounted thereon a sleeve 23 having radially disposed toggle arms 24 pivotally connected therewith at 25.

A semi-circular stirrup 26 preferably of a resilient nature, is pivotally linked at its end to the toggle members 24 as indicated at 21 and this stirrup element extends down directly below the bottom extremity of the tube I0 and carries a needle valve 28 which cooperates directly with a valve seat 29 arranged in the lower extremity of the tube.

The outer ends of the toggle member 24 are adapted to rest directly on the float I so that as the fuel level rises in the float chamber the arms 24 will be swung upwardly on their pivots 25 so that the spring stirrup 26 will move the valve 28 to close the outlet from the tube Ill and with the parts in the position slown it is assumed that the fuel level is at a mean height indicated by the letter n and the prevailing temperature may be assumed to be say, 40 F.

Assuming now that a considerably lower tem- -perature is encountered, then there will be a resultant contraction of the fluid medium in the chamber I causing an upward lift on the tube I0 unsealing the lower end thereof from the valve 28 and allowing fuel to flow into the float chamber until the float again raises sufliciently to close the valve 28, thereby raising the fuel level, for example, to the line c.

If, on the other hand, an increase in temperature in the atmosphere is encountered above normal, then there will be a resultant expansion of the fluid medium in the chamber I5, thereby forcing the tube I0 downwardly to cause the valve 28 to close with a lower float position, so that the fuel level will approximate that indicated by the letter h.

After careful experimentation I have found that by controlling the actual fuel level in the float chamber a proportionate increase or decrease in the amount of fuel drawn from the jet 3 results, so that the fuel air mixture passing to the engine may be accurately regulated.

Moreover it will be observed that the pressure of the fuel supply entering the port or passage I9 will be impressed with somewhat greater upward force on the tube IU due to the greater end area presented by the upper bellows I3 relative to that presented by the lower bellows 20 and this effectively offsets the weight of the tube I0 When fuel is fed to the passage I9 in a pulsating manner it will be seen that this pressure will be distributed upwardly and downwardly into the respective bellows and this in conjunction with the weight of fuel resting in the lower bellows 20 will effect a substantially balanced condition and it is to be further observed that with the chamber I5 completely filled with a liquid expansion medium, this will effectively offset any inclination for the tube I0 to be vibrated or pulsated axially, so that detrimental vibration will not be imparted to the parts suspended on the lower end thereof, which would tend to interfere with the positive positioning and heating of the cooperating elements, producing wear and strain on the parts.

It will also be observed that any air or vapor trapped in the upper end of the bellows I3 and tube I0 will/act as a cushioning medium, effectively absorbing or damping out the pulsating surges of the fuel as it is fed to the carburetor.

The fuel entering the upper bellows I3 will have a heat exchange relation to the fiuid medium in the chamber I5 through the metallic bellows I3 and will therefore have a controlling effect on the positioning of the tube I0 as will be readily appreciated and in Figure 2 I have provided for a positive circulation of the fuel through the upper bellows I3 by way of the passage I9 and a passage I 9" conducts the fuel from the upper bellows I3 to the lower bellows 20. v

What I claim as my invention is:-

1. The combination with a fuel mixing device having a fuel supply chamber and a jet or jets supplied thereby and a fuel supply line through which fuel is adapted to be supplied under pressure, of means for automatically regulating the level of the fuel in said chamber supply relative to the jet or jets in accordance with changes in atmospheric temperatures, said means including an expansile chamber in pressure communication with the interior of said fuel line, and means for restricting displacement of said expansile chamber due to the fuel pressure thereon.

2. The combination with a fuel mixing device having a float chamber for supplying fuel thereto at a predetermined level and a fuel supply line through which fuel is adapted to be supplied under pressure, of means for automatically varying the effective fuel level in said float chamber in accordance with changes in atmospheric conditions, said means including a pair of pressureresponsive bellows arranged in opposition having their interiors connected together and to the interior of said fuel supply line.

3. Means as claimed in claim 2 in which said automatic means includes a float-controlled valve means for controlling entry of the fuel into said float chamber, said valve means having a common operative connection with said pressure-responsive bellows and adjustably supported thereby for positioning said valve means relative to the float.

4. In a fuel mixing device, a fuel supply chamber for feeding said device, a float in said chamber, a valve structure operatively associated with said float including a part displaceable to control the entry of fuel into said chamber, thermostatically responsive means for bodily shifting Isaid part of the valve structure relative to a second part thereof and to said float to regulate the effective level of the fuel in said chamber, said thermostatically responsive means comprising a pressure responsive member separate from said float and operatively connected with said displaceable valve part, a fuel supply line through which fuel is adapted to be supplied, under pressure, and pressure responsive means directly connected with the fuel line for pressure actuation by the fuel and operatively associated with said displaceable valve part to influence the thermo- 5. Means as claimed in claim 4 in which said displaceable valve part includes a fuel supply tube communicating with said fuel line and axially displaceable toward and away from said float and having the displaceable valve part mounted thereon for co-operation with said second valve part, said second valve part being operatively connected with said float.

6. In a fuel mixing device for combustion engines, a fuel supply chamber having a float therein, a fuel supply tube axially slidable toward and from said float, means forming a pressure chamber into which said tube extends, a pressure responsive bellows in said chamber operatively connected with said tube, an expansile fluid surrounding said bellows and filling `said pressure chamber, and fuel control means operatively interposed between the said tube and float for controlling the entry of fuel into saidfuel supply chamber.

'7. Means as claimed in claim 6 in which means is provided for adjusting the volumetric capacity of said pressure chamber to adjust the axial position of said tube.

8. Means as claimed in claim 6 in which the means forming said pressure chamber includes a cup-shaped housing having a threaded connection with a fixed part of the device, a compression seal being interposed between said housing and fixed part to maintain a seal therebetween while permitting threaded adjustment of the housing whereby adjustment of the said tube is provided for.

9. In a fuel mixing device, a float chamber, a float in said chamber, a tube axially slidable having a valve seat adjacent said float, means for directing a supply of fuel into said tube, a valve co-operating with said valve seat, toggle members mounted on said tube and operatively engaged by said float, means operatively connecting said toggle means with said valve member, and pressure responsive means operatively connected with said slidable tube for axially positioning the same, said tube being slidably mounted in a guide block and the means for conducting fuel to said tube including a bellows sealed at one end to the tube and at the other end to said guide block, said bellows formingV a receptacle for the fuel supply and said tube having ports leading therefrom to the oat chamber.

l0. In a fuel mixing device, a float chamber, a float in said chamber, a tube axially slidable having a valve seat adjacent said float, means for directing a supply of fuel into said tube, a valve co-operating with said valve seat, toggle members mounted on said tube and operatively engaged by said float, means operatively connecting said toggle means with said valve member, and pressure responsive means operatively connected with said slidable tube for axially positioning the same, said pressure responsive means comprising a bellows operatively connected with said tube and having its interior open to the fuel supply.

11. In a fuel mixing device, a float chamber, a float in said chamber, a tube axially slidable having a valve seat adjacent said float, means for directing a supply of fuel into said tube, a valve (zc-operating with said valve seat, toggle members mounted on said tube and operatively engaged by said float, means operatively connecting said toggle means with said valve member, and pressure responsive means operatively connected with said slidable tube for axially positioning the same, the means for operatively connecting the toggle arms with the valve member comprising a spring stirrup member of bowed form having the ends pivotally linked to the respective toggle arms.

12. In a fuel mixing device, a float chamber, a float in said chamber, a tube axially slidable having a valve seat adjacent said float, means for directing a supply of fuel into said tube, a valve co-operating with said valve seat, toggle members mounted on said tube and operatively engaged by said float, means operatively connecting said toggle means with said valve member, and pressure Y responsive means operatively connected with said slidable tube for axially positioning the same, said tube being slidably mounted in a guide block and the means for conducting fuel to said tube including a bellows sealed at one end to the tube and at the other end to said guide block, said bellows forming a receptacle for the fuel supply and said tube having ports leading therefrom, said pressure responsive means including a second bellows, means directing the fuel supply first into said second bellows in heat exchange contact therewith, and means conducting the fuel from said second bellows to the interior of said firstmentioned bellows.

WILFRED GROH.

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