Fuel mixing device

June 7, 1960 j. r. l. middleton et al 2,939,775

FUEL MIXING DEVICE Filed March 28, 1957

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attorney

United States Patent Office _, ,. ,^2,929’™

Patented June 7, 1960 ' ; 1 '

2,939,775

FUEL MIXING DEVICE

John R. L. Middleton and John W. Harrison, Corsicana, Tex., assignors to Universal Carburetor Company, Corsicana, Tex., a corporation of Texas

Filed Mar. 28, 1957, Ser. No. «49,114

Claims. (Cl. 48—180)

This invention relates to new and useful improvements pertaining to fuel mixing devices,

It has formerly been the practice to mount air cleaners or filters on the air intake of the fuel mixing device or carburetor of internal combustion engines. When it is desired to convert the engine from one using gasoline as a fuel to one employing L.P.G. (liquified petroleum gas) as a fuel, it has often been the practice to either make a connection into the gasoline carburetor or to > place an adaptor or mixer including a venturi on top of the gasoline carburetor. Some of the difficulties inherent in either of these two practices are described in my copending application entitled Air Cleaner and Carburetor Device, filed April 9,, 1956, and bearing Serial No. 577,058, now abandoned. The above application relates to an improved air cleaner and fuel mixing device which will effectively serve as an adaptor to convert an internal combustion engine from one operating on gasoline to one capable of operating on L.P.G. fuel while minimizing the overall height of the unit. Since the ratio of the length to the diameter of the usual type venturi is indicative of the pressure drop due to turbulence or ‘‘drag” occasioned when mixing fuel with air streams, the overall height of such an adaptor may not be reduced below that required to provide an effective venturi.

Accordingly, it is an object of this invention to provide an improved mixing device which is relatively short or “squat” in nature and which will at the same time produce relatively little drag when being employed with high velocity air streams.

A further object of this invention is to provide a combination air cleaner and fuel mixing device which will reduce the drag normally produced by air passing through a fuel mixing device or venturi.

Another object of this invention is to provide a combination air cleaner and fuel mixing device which will serve as an adaptor for converting an internal combustion engine from gasoline operation to an engine capable of operating on L.P.G. fuel and which will conserve space by minimizing the overall height of the unit and at the f same time produce less drag than is occasioned by other devices in present use.

Another object of this invention is to provide an im4 proved air cleaner and fuel mixing device wherein ( the air cleaner is disposed in surrounding relationship to a fuel mixing device which is centrally positioned within the unit so that the overall height of the unit will be minimized and at the same time permit an effective fuel mixing operation with a minimum of drag to be carried out. ( '

Still another object of this invention is to provide a more efficient fuel mixing device which will· result in greater economy of operation due to better fuel distribution and more accurate measurement, especially at low air flows.

Yet another object of this invention is to provide a more efficient fuel mixing device which will provide more open throttle power because of less pressure drop being occasioned for extremely high air flows.

A still further object of the invention is the provision of a venturi in the form of an annulus having a constric5 tion of one end thereof which will have an effective length approximating that of a theoretically perfect old style long venturi in spite of a relatively squat nature.

A further object of this invention is to provide an improved combination air cleaner and fuel mixing device 10 having a venturi in the form of an annulus which is adjustable in size to accommodate desired conditions.

The construction designed to carry out the invention will be hereinafter described, together with other features thereof.

The invention will be more readily understood from a reading of the following specification and by reference to the accompanying drawings forming a part thereof, wherein an example of the invention is shown and wherein:

Figure 1 is an elevation showing a combination air cleaner and fuel mixing device, constructed in accordance with the present invention, operably associated with a carburetor of standard type.

Figure 2 is an enlarged transverse sectional view of a ²⁵ combination air cleaner and fuel mixing device, constructed in accordance with the invention, and

Figure 3 is a sectional view taken on the line 3—3 of Figure 2.

Referring more particularly to the drawing, the nu³⁰ meral 10 designates a combination air cleaner and fuel mixing device constructed in accordance with the present invention. The combination air cleaner and fuel mixing device 10 has a base plate 11 which is provided with an adaptor collar 12 which is integral therewith and extends ³⁵ downwardly from the medial portion of the base plate 11. The adaptor collar 12 has a stepped bore 13 for accommodating the upper collar or air inlet 14 of a standard carburetor C.

The fuel mixing device or carburetor portion 15 is posi⁴⁰ tioned above and in axial alignment with the bore 13 of the adaptor collar 12. The fuel mixing device 15 consists essentially of a downwardly converging truncated cone-shaped element 16 and a similar downwardly converging truncated cone-shaped element 17 which is posi46 tioned partially within the element 16 so . as to define a downwardly tapering annulus 18. The element .17 is closed at the bottom as at 17α so that air must pass through the annulus to reach the bore 13. It will be noted that the element 16 converges less sharply than the 60 element 17 so that the annulus 18 is constricted at its upper end.^- This annulus 18, which forms an important part of this invention, will be discussed in greater detail below.

The downwardly converging elementl6 is supported by 65 an outwardly projecting rim 16α and a downwardly projecting annular rim 16b which together with the element 16 define an annulus 19. The element 16 is secured in fixed relation to (the base plate 10 by a plurality , of spaced bolts 20 which pass through the outwardly project60 ing rim 16α as at 20α and are threadably secured to the base plate 11 as at 26b. The downwardly converging element 17 is provided with spaced projections 17/? Which, extend in alignment with the outwardly projecting rim 16α and are held in spaced relation (therewith by the 65 threaded elements 21 which pass through and are threadably carried by the projections 17b and the rim 16a. These threaded elements 21 are provided with lock nuts 22 which may be adjusted to vary the spacing between the projections 17b and the outwardly extending rim 16a and ⁷ hence the size of the annulus 18.

The base plate 11 has an enlarged portion 11α integral

2.939.775 therewith which is provided with a bore 23 therein which serves as a passageway to communicate between the annulus 19 and a source of fuel (not shown). The annulus 19 has communication with the annulus 18 through a plurality of spaced apertures 16c, which are shown as drilled 5 holes but which may be in the form of slots. Fuel may therefore be drawn into the annulus 18 from the annulus 19 through the apertures 16c where it is mixed with air entering the annulus 18.

An annular air filter 24 is supported by the base plate 10 11 in surrounding relation to the fuel mixing device 15. This air filter or air cleaning device may be of any suitable type but is preferably of the type which is constructed of pleated paper 24α and wire mesh 246 which serves to confine a pleated paper 24α. This filter portion I® 24 is provided with a suitable base 25 and an upper spacing plate 26 which has an offset portion 26α to confine the upper portion of the filter 24. The air filter 24 is further provided with a dome-shaped housing or casing 27 which is secured in its medial portion by a bolt 28 which is in 20 axial alignment with the bore 13 of the adaptor collar 12. The bolt 28 passes through a suitable spider or transverse bar 29, which is fixedly positioned within the bore 13: The dome-shaped housing 27 is secured to the bolt 28 by the nut 28α. 25

It will be noted that the lower edge of the dome-shaped housing 27 is provided with an outwardly flaring rim 27α so as to direct the flow of air into the annulus 27 b between the housing 27 and the air filter or cleaner 24. The usual “balance line” 30α has connection with a pas- ³® sage 306 which, in turn, communicates with an aperture 30 in the base plate 11. As is well known, the “balance line” is in communication with the back side of the low pressure diaphragm of the regulator (not shown) which regulates the pressure of the gas or fuel and maintains the ³⁸gas-air ratio, even though the air filter might become partially clogged.

In operation, air flows into the annulus 276 through the air filter 24 and into the tapering annulus 18. Fuel is , drawn through the bore 23 into the annulus 19 and ^Uthrough the apertures 16c into the constricted portion of the tapering annulus 18 where the fuel and air are initially mixed from whence the mixture of fuel and air flows downwardly into the enlarged lower portion of the an- ., nulus 18 and into the bore 13 of the adaptor collar 12 before being introduced into the carburetor C through the collar 14. Thus the annulus 18 has a constricted upper end portion to provide a pressure drop at that point so as to draw fuel into the annulus 18 through the apertures 16c. The annulus 18 becomes larger toward the bottom because the element 16 converges to a less extent than does the element 17 so that a mixing chamber is provided for the air and fuel mixture. Because of the shape of the annulus 18, a fuel mixing device or venturi is provided 55 which is short or squat in nature and yet the ratio of the length of the venturi to the diameter is relatively large so that the venturi of the present invention has an effective length approximating that a theoretically perfect old style long venturi. As has been mentioned above, the ®® element 17 may be raised or lowered so as to adjust the size of the annulus to accommodate desired conditions.

The various parts may be readily assembled and disassembled since the adaptor collar 12 may be easily removed from the carburetor collar 14. The air filter may ⁸⁵be removed by removing the nut 28α so that the air filter can be disassembled. The mixing device may be disassembled by removing the bolt 20, the lock nuts 22 and removing the threaded element 21. It is evident that al- 70 most any desired type air filter can be used and that a wide variety of equivalents could be substituted for the fastenings and various parts incidental to the positioning of the mixing device and surrounding air cleaner.

The device of the present invention results in greater M ⁴ economy of operation due to superior fuel distribution and more accurate measurement. Also, the relatively high pressure drop occasioned by the use of conventional short venturis has been eliminated because of the present venturi constructed in the form of an annulus, thus giving increased wide-open throttle performance. This makes possible a more efficient adaptor which is constructed of a novel combination of parts and which requires less overall height than has heretofore been possible for converting an internal combustion engine from operation on gasoline to one operated on L.P.G. fuel or the like.

The foregoing disclosure and description of the invention is illustrative and explanatory thereof, and various changes in the size, shape and materials, as well as in the details of the illustrated construction may be made, within the scope of the appended claims, without departing from the spirit of the invention.