US2088464A - Carburetor - Google Patents

Description

July 27, 1937.

M. E. CHANDLER ET AL CARBURETOR 4 Sheets-Sheet 1 Filed Feb. 5, 1935 INVENTOR ATTORNEY July 27, 1937.

M. E. CHANDLER ET AL 2,088,464

' CARBURETOR Filed Feb. 5, 1935 llll l M/L ro/v J A7 772 5/? MIL rozv E 6 1/4/10; 5?

INVENTORS ATTORN EY July 27, 1937. 7M. E. CHANDLER ET AL CARBURETOR 4 Sheets-Sheet 4 llll'llll(l :f

Filed Feb. 5, 1935 IW l MIL ro/v J/f/rn E7? Mu. 70M 6. 071mm 5/? INVENTORS ATTORNEY Patented July, 27, 1937 2.088.464 CARBURETOR Milton E'. Chandler and Milton J. Kittler, Detroit, Mich. said Kittler assignor to said Chandler Application February 5, 1935,, Serial No. 5,144

P TENT] reclaims. (01. 261-12) The object of thisinvention'is todesign a variable Venturi carburetor suitable for aircraft engines of the internal combustion type having external carburetor means.

The ordinary aircraft carburetor has been-designed as a modified automobile carburetor in which the production requirements have been a factor. By departing from the accepted design and placing the fuel nozzle on the engine side of m the throttle and utilizing the throttle means to provide a variable Venturi passage around the fuel nozzle the maximum degree of atomization is secured without the danger of freezing.

By making the carburetor of flat pieces bolted together the scrap loss'due to porous castings is reduced and the cost of manufacturing these large carburetor castings is greatlyreduced. A special problem has been given a specific solution.

Figure 1 shows a plan view of the preferred form of construction. V

Figure 2 shows a cross-section elevation taken on plane 22 of Figure 1-. I

Figure 3 shows the detail of clamping the heating manifolds to the throttles. 1

, ".tion to that shown inFigure 2. I

Figure 5 is a cross-section taken on plane 5'5 of Figure 4.

Figure 6 shows an automatic altitude control. Figure 7 shows a manual altitude control to be used as an alternative control withthe construction shown in Figure 6.

Figure 8 shows diagrammaticallythe method for providing hot air to the throttles.

Figure 9 shows another alternative method of heating the throttle. I

Figure 10 shows diagrammatically the arrangements of the throttles showing the outlets for the heated air.

Figure 11 'showsan alternative outlet for the.

heated air from the interior of the throttle.

Figures 12 and 13 show diagrammatically a. method for heating the fuel nozzle directly.

Figure 14 shows diagrammatically the heating 45 means and the throttle control.

55 hollow throttles 49 and 50. These two throttles,

Figure 4 shows in plan an alternatlve'construcare geared. together in a well known manner. The pitch-line of the gears are shown diagram-v matically 'by'the circles 90 and 9| Figure 2 and infulllin Figure 14, in which figure the throttles 49 and 50 are shown diagrammatically.

In Figures 1 and 2, 5! is a vertical fuel passage which leads to a second fuel passage 52. which extends transversely across the mixing chamber OFFICE REISSUED APR 22. 1941 as the throttles openrectangular'slots areopened between 52 and the throttles"'49 and 50.- Fuel outlets 53 and 54 are arranged to'discharge along the center of the twonarrow slots thus formed. The streamlined surfaces of 49 and 50 thus form a variable Venturi passage for the air. The wall ofxthe air entrance to the carburetorisnumberedl3.-

pGeared to the (Figure 14) whichmeshes with the gear 90. The gear 55 operates a cam 5fi-Figure 2which engages with .a roller- 51 mounted onalever 58pivotally anchored at 59to the maincasting 43.: This lever 58engages with a needle '60 which controls thefuel restriction 'GI in a'main fuel passage 62. This fuel is supplied from a fuel supply chamber 63which-is formed of two flexiblediaphragms 64 and 65. An automatic airpump is formed by means of two air chambers l5and1lsurrounding this fuel chamber63. This air pump also comprises a third flexible diaphragm 8'5 supported by a spring 61 which is seated against the casting 43. This diaphragm .66 encloses within the casting 43 a chamber .68, which'communicates through .a restricted passage 69 to the; back .of the throttle 49 and so'is in communication with the mixing chamber 44 so that the engine suction acts on the diaphragm 6'5. In order to insure that this is so, a wiper 10 engages with the circular cylindrical surface of the throttle 49.; Aslmilar wiper block H engageswith the throttle 50, thus throttles 49 and 50 is a gear'55 sealing the mixing chamber 44 from the air entrance 13. End leakage is limited by rectangu lar pieces shown in broken lines at IBII-l8l Figure 2) A restricted air vent ,14 communicates with the air chamber 15 formed between the diaphragm 66 and the diaphragm 55. .The restricted air passage l4 also communicates through.

a passage Him the other air chamber 11 formed between the diaphragm 64 and a. cover [8. Passage l6 therefore forms a communication between the two air chambers 11 and I5. In Figure 1- (upper left) 19 is a mixture control lever which air through the air entrance wall 18 through a pasage 8| and across a passage 82 which discharges air directly into the fuel passage 52 Figure 2.

In order to admit heat into the interior of the hollow throttles and 58 two manifolds are provided, 88 and 84. (See also Figure 14.) One of the following heating means may be used through.

these manifolds: hot air, exhaust gas, hot oil, or hot water. and are springs which impose a pressure on the manifolds 88 and.

Bridges 88 and 81 are provided so that the manifolds 88 and 84 may be held tightly against the throttles 49 and 58. This detail is shown in Figure 3. In Figure 1, (lower right) and also in Figure 14, lever 88 is the main throttle control bolted toa shaft 88 which operates the gear 55 which engages with a gear 98 and through the gear 88 with a gear 9| upon which the throttle 48 is mounted. By this means a cam-58, the throttles 48 and 58 and the needle 88 are all 7 moved in unison.

In Figures 7 and 6 a method of controlling the fuel pressure in the fuel supply chamber 88 is shown. I

' Figure 7 alternative manual means is'shown for controlling the pressure and Figure 6 shows diagrammatically thepreferred method of control which is by means of aneroidbellows II8.

In this figure a fuel pump III is shown which obtains fuel from a pipe 8 and discharges its fuel through a pipe |I9 past the two needle valves I28 and |2|. These needle valves are connected by levers I22 and I28 pivoted at I24 and I24. the diaphragms 84 and 55. Coil springs I25 and I25 are used to support the diaphragms 54 andv 8.5 and arelocated in chambers I5 and TI; The compression in these springs is controlled by the movement of the bellows H5 whichis responsive to atmospheric pressure. Linkage I28, I21" and I28 transmits the movement of the bellows 8 so that the compression in the springs I25 and I25 is varied as the altitude varies. In the fuel.

outlet 82 the restriction 8| and the needle valve 88 are as shown in Figure.2. We have discovered that the use of two diaphragms and two valves enables us to deliver seven hundred pounds ofgasoline per hour at three or four pounds pres-j sure per square inch and towithstand a pressure in the fuel pump of twenty pounds per square inch. The use of a single diaphragm and a single valve requires them both to beexcessively large.

Figure 7 shows a manually operated lever I18 adapted to be connected through linkage |28'-I2'|' with the spring I25. I

In Figure 8 an exhaust pipe I48 is shown passing through the center of a heat exchanger I in which. are located a large number of fins I42 mounted on the exhaust pipe I48. An air entrance |48 admits air to flow 'over these fins. An outlet I44 admits air to the hollow throttles 49 and 58 through-themanifold 88, the manifold 84 providing the outlet (see Figures 1 and 4). Means (not shown) are provided for drawing the air out of 84. I

In Figures 9, l0, and 11 the outletmanifold 84 is dispensed with and the hot :air escapes through openings I45 and. I45 formed in the hollow throttles 49 and 58 either on the up stream side (Figure 10) or the down stream side (Figure admitted'through a passage I41 located below These levers I22 and I28 engage with the fuel passage 52 out "w thefuel outlet 58 discharges;

Figures 14 and 15 show diagrammatically two hollow throttles '48 and 58, which are connected by the end manifolds 88 and 84, which admit the heating fluid to the interior of the throttles. Gear wheels 55, 88 and 8| are also shown whereby the throttle shaft 89 (see Figure 1) is connected so as to rotate thetwo hollow throttles 48 and 58. The cam 58 'is shown engaging with the roller 51 which in its ,turn is mounted on the lever 58, not shown. 1

Figures 4 and 5 show how the central portion 48 of Figure 2 can be divided in two parts,

, 48'-48", connected by a cross piece I88, which contains the fuel needle 58, fuel restriction 8| and fuelpassage 82. Bolted to this cross piece I88 is the casting|84 containing the fuel passages 5| and 52 out of which lead the fuel nomle 54. The-difference resulting from this construction' as compared with the construction shown in Figures 1 and 2 is that no cored castings are required and the production of solid castings free from blow holes is much easier to control with such solid castings than is the case when cored castings are used. g

Operation.

Whenthe carburetor is applied to an airplane engine its speed is regulated by the rectangular area between "and 5| and between 5| and 58,

whichis determined by the opening and closing of the throttles 49 and 58. In doingso the needle valve" is moved by the cam 58 to permit more or less fuel to flow past the restriction 8|, through the fuel openings 58 and 54, into the throat-of the variable venturi formed between the cylindrical throttles 48 and 58, and so into themixture outlet 44. When the throttle is opened suddenly the vacuum in 44 is broken. The pressure in88 therefore risesand the flexible wall 88 moves to the left under the influence of the spring 81. The flexible wall 85 then moves over to the left and the pressure in the constant pressure fuel supply chamber 88 is temporarily raised above the normal pressure which of course depends on the elastic flexibility of the wall 85.

The flow through 82 is thus temporarily increased during theacceleration period of the engine.

.By making 14 very small this action is prolonged for a definite-period of time and by making 14 very large this action-is negligible, hence I4 can be made .exactly the righ'tsize to give the I desired performance.

The operation of the other figures will be obvious from their description, except that in Figure 6 an increase in atmospheric pressure will compress the springs l25|25' and a decrease in atmospheric pressure will expand the bellows ||5 and thus relieve the springs |25|25' and thus decrease the pressure of the fuel delivered through 82. Hence, as the airplane climbs the mixture ratio is maintained constant. f

By means of the arrangement of diaphragms shown to the left of Figure 2 and diagramatically in Figure 6, the carburetor is rendered less sensitive to stunting. When the inertia effects move from right to left in Figure 6, for example, the

needle valve I2I is shut off, but the needle valve I28 is opened because if the inertia forces act on diaphragm 84, they also act on diaphragm 85 so that the supply of fuel to the fuel nozzle is not interrupted and the ability of the plane to maneuver is notinterfered with.

-Weclaim: Y

chamber having an entrance leading thereto and an exit leading therefrom,'flexible walls for said fuel supply chamber, an air chamber adjacent to said flexible walls, an automatic air pump for varying the pressure in said air chamber, comprising a chamber having a yieldable wall, spring means for moving said wall and a passage connecting said chamber to the mixture outlet whereby variations in pressure in said mixture outlet operates said automatic air pump.

2. In a carburetor having a variable fuel and air discharge, an air entrance, a mixture outlet, accelerating means comprising a" fuel supply chamber having an entrance leading thereto and an exit leading therefrom, a flexible wall for said fuel supply chamber, an air chamber adjacent to said flexible wall, an automatic air pump for varying the pressure in said air chamber, means responsive to the variation in pressure in said mixture outlet for operating said automatic air pump.

3. A fuel supply means for an aviation carburetor comprising a fuel pump, a fuel passage leading therefrom, a fuel supply chamber having a flexible wall, a fuel outlet from said chamber,

an inlet valve discharging into said chamber from said fuel passage, said valve being operated by said movable wall, spring means for supporting said wall, means responsive to variation in atmospheric pressure for varying the compres-.

charging into said chamber from said fuel pa'ssage, said valve being operated by said movable wall, spring means for supporting said wall, means responsive to variation in atmospheric pressure for varying said spring means.

.5. Heating means for a carburetor comprising two cylindrical hollow throttles adapted to roll together to form a variable venturi, a fuel nozzle discharging between said throttles, means for circulating a heating fluid through said hollow throttles, additional heating means comprising a heating passage having an axis parallel to that of the rollers and located centrally therebetween, said fuel nozzle being associated with said heating passage so as to be heated thereby.

6. Heating means as described in claim 5 in which the additional heating means is located on the down stream side of'said nozzle so as to form a stream-lining contour thereby.

- 7. Fuel supply means for an aviation carburetor comprising a source of fuel supply, a fuel passage leading therefrom, a fuel supply chamber having two similar flexible walls located opposite each other, two inlet passages discharging into said chamber from said fuel passage, a valve in each inlet passage, mechanism connecting each valve with one of said flexible walls, and a fuel outlet fromsaid fuel supply chamber.

8. Fuel supply means as in claim 7 in'which the two flexible walls are normally located in the vertical plane.

9. Fuel supply means as in claim 7 in which the two flexible walls are of equal area.

10. Fuel supply means as in 'claim 7 in which the two flexible walls are of equal area and normally located in parallel vertical planes.

MILTON E. CHANDLER. MILTON J. KIT'ILER.

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