Vaporizing carburetor

Abstract

An improved vaporizing carburetor including a liquid fuel reservoir having a wet vaporizing filter partially immersed in the liquid fuel in the reservoir, a baffle for directing primary air through the wet filter in the liquid reservoir and a vaporized fuel outlet tube within the baffle for conducting vaporized fuel from the carburetor. The improvement including a bubble break screen downstream from the wet vaporizing filter, a dry vaporizing filter downstream from the bubble break screen, a conically shaped bottom wall in said reservoir to reduce the amount of liquid stored in the fuel reservoir and a stand pipe on the liquid fuel inlet tube to maintain gravity level control of the fuel level in the reservoir.

Description

BACKGROUND OF THE INVENTION

A vaporizing carburetor of the type contemplated herein is shown in my U.S. Pat. No. 3,653,643, issued Apr. 4, 1972 and entitled, "Carburetor." The carburetor as disclosed therein provides for the deflection of primary air through a wet vaporizing filter to provide a dry vaporized gas in the mixing chamber of the carburetor. Secondary air is admitted to the mixing chamber prior to delivery of the vaporized fuel to the outlet tube. This type of carburetor has been proven to have an increase in the efficiency of combustion. However, it has been found that the liquid fuel level is affected by the vacuum of the engine and that wet gas can be drawn into the outlet tube during acceleration.

SUMMARY OF THE INVENTION

The vaporizing carburetor of the present invention has been modified to overcome the above problems. In this regard, the level of liquid fuel in the reservoir is maintained under gravity level control by imposing atmospheric pressure on the liquid fuel delivery tube at all times. The amount of liquid fuel in the carburetor under static and operating conditions has been reduced by providing an inclined bottom wall in the housing at an angle sufficient to maintain the liquid above the bottom of the baffle. Foaming or bubble carryover into the vaporized fuel outlet has been prevented by providing a bubble break screen and a dry vaporizing filter in the vaporized fuel flow path downstream from the wet vaporizing filter.

DRAWINGS

FIG. 1 is a cross section view in elevation of the carburetor of this invention; and

FIG. 2 is a perspective view of the bubble break screen provided between the wet vaporizing filter and the dry vaporizing filter.

DESCRIPTION OF THE INVENTION

The carburetor 10 of the present invention, as seen in the drawing, generally includes a housing 12 having a bottom wall 14 and a hood or cover 16. A wet vaporizing filter 18 is provided in the housing 12 and liquid fuel is admitted to the housing by means of a separate float valve assembly 20. A cylindrical baffle 22 is secured to the hood 16 and extends downwardly from the hood into the wet vaporizing filter 18. Primary air is admitted to the housing through an air inlet 24 and flows through the passage 26 between the baffle 22 and the housing 12 into the wet vaporizing filter 18. The vaporized fuel carried by the primary air flows into a mixing chamber 30 within the baffle 22 and prior to entering a vaporizing outlet tube 28. The admission of secondary air into the mixing chamber 30 is controlled by means of a secondary air inlet and filter assembly 32 mounted on a secondary air tube 33 on the hood or cover 16. The vaporizing carburetor 10 as described above operates substantially as described in my prior U.S. Pat. No. 3,653,643.

FUEL LEVEL CONTROL

In accordance with the invention, means are provided for maintaining gravity level control of the liquid fuel in the reservoir at the bottom of the housing 12. Such means is in the form of a stand pipe 34 provided at the end of the delivery tube 36 from the float valve assembly 20. The stand pipe 34 projects upwardly through the liquid fuel in the reservoir and through the filter 18 into the passage 26 between the baffle 22 and housing 12. The stand pipe 34 is subjected to inlet air pressure or atmospheric pressure in passage 26 which is imposed on the end of the delivery tube 36. Atmospheric pressure is thereby maintained on the float valve assembly 20 which is then unaffected by the vacuum existing in the mixing chamber.

Means are provided for reducing the amount of fuel retained in the reservoir in the housing 12 as well as to maintain the level of the liquid fuel above the lower edge of baffle 22. Such means is in the form of an inclined or conically shaped bottom wall 14 for the housing 12. The bottom wall 14 tapers upwardly into engagement with the outlet tube 28. The angle of inclination of the bottom wall has been selected to duplicate the angle of inclination of the liquid fuel in the reservoir under operating conditions. In this regard, it should be noted that under normal operating conditions, the vacuum demand of the engine in passage 30 will act on the surface of the liquid fuel in the reservoir. This force will cause the liquid fuel to rise at an angle in the space between the baffle 22 and outlet tube 28. The angle of inclination of the bottom wall provides sufficient depth of liquid below the baffle 22 to assure that the baffle is maintained below the level of fuel in the reservoir.

To insure that all of the primary air passes through the liquid fuel in the reservoir, means are provided on the baffle 22 for extending the air path through the reservoir. Such means is in the form of an annular flange or ring 23 which extends inwardly and upwardly from the bottom edge of the baffle 22 parallel to the bottom wall 14. The ring 23 extends substantially half way across the gap between the baffle 22 and the tube 28.

The air flow path through the mixing chamber has been further extended by providing a funnel shaped deflector 29 on the upper end of tube 28. The deflector 29 forces the fuel laden primary air to flow outwardly from tube 28 and around the end of the deflector 29 prior to entering the tube 28.

Final Dry Gas Filter

The flow of wet vaporized fuel into the mixing chamber 30 can be prevented by means of a bubble break screen 38 provided in the space between the baffle 22 and the outlet tube 28. The bubble break screen 38, as seen in FIG. 2, is in the form of a radially outwardly extending strip of No. 16 wire cloth or window screen which has been pleated or creased to form an accordian shape. More particularly and referring to FIG. 2, it will be noted that the screen 38 is in the form of a continuous strip of material which has been folded along lines 40 and 42 to form the corrugated or accordian shape. The screen 38 is designed to break the surface tension of the bubbles as they leave the wet vaporizing filter 18. Destruction of the surface tension of the bubbles will prevent the build up of bubbles and subsequent carryover of the liquid fuel (forming the skin of the bubble) from entering the outlet tube.

In my previous patent, a description of the capability of bubbles to carry fuel has been fully described. Briefly, this involves the ability of a certain size bubble to completely saturate the air within with liquid fuel during the time of travel through the filter.

A final dry vaporizing filter 44 is provided downstream of the bubble break screen 38. The dry vaporizing filter 44 is made from the same material as the wet vaporizing filter 18 as described in the patent 3,653,643. The filter has been provided to ensure that complete dry vaporized gas is delivered to the outlet tube 28 of the carburetor.

In the event the engine should choke, a pressure pulse can be directed through the tube 28 into the mixing chamber 30. This is prevented by means of a flap 35 pivotally mounted on a pin 37 on the open end of tube 33. The flap 35 is normally biased by a spring 39 to a closed position and is free to open in response to a pressure pulse in tube 28.

Means are provided for directing the pressure pulse into the tube 33. Such means is in the form of an inwardly directed flange 41 on tube 28 and an outwardly directed flange 43 on tube 33. The funnel shaped deflector 29 will also serve as a trap to confine any air pressure pulses to the area between the tubes 28 and 33.

Claims

I claim:

1. A carburetor comprising:

a housing having a liquid fuel reservoir at the bottom,

means for admitting liquid fuel into said reservoir,

a vaporized fuel outlet tube projecting above said liquid fuel in said reservoir,

a primary air inlet in said housing,

an open cell plastic wet vaporizing filter partially immersed in the liquid fuel in the bottom of said reservoir,

a baffle between said air inlet and said air outlet tube for directing primary air through said wet filter,

a bubble break screen downstream from said wet vaporizing filter,

a secondary air inlet in said housing for admitting secondary air into said vaporized fuel path downstream from said bubble break screen,

means on said outlet tube for directing air pulses from said outlet tube into said secondary air inlet, said secondary air inlet comprising a tube aligned with said outlet tube,

and means for controlling the flow of secondary air into said housing.

2. The carburetor according to claim 1 including an open cell plastic dry vaporizing filter downstream from said bubble break screen.

3. The carburetor according to claim 1 including means connected to said liquid fuel admitting means for maintaining inlet air pressure on said admitting means whereby the control of the liquid fuel level in said reservoir is not affected by the pressure of the fuel-air mixture in said housing.

4. The carburetor according to claim 1 wherein said secondary air control means includes means for relieving air pressure pulses in said outlet tube.

5. The carburetor according to claim 1 including means on the inlet end of said baffle for extending the primary air flow path through said reservoir.

6. The carburetor according to claim 1 wherein said bubble break screen comprises a strip of wire cloth.

7. The carburetor according to claim 6 wherein said wire cloth is folded to an accordian shape.

8. A carburetor comprising:

a housing having a liquid fuel reservoir at the bottom,

a float valve assembly connected to control the flow of liquid fuel to said reservoir,

a vaporized fuel outlet tube positioned in said housing above the liquid fuel in said reservoir,

a primary air inlet in said housing,

an open cell plastic wet vaporizing filter immersed in the liquid fuel in the bottom of said reservoir,

a baffle between said air inlet and said fuel outlet tube for deflecting primary air through said wet filter prior to flowing into said outlet tube,

means connected to said float valve assembly for applying inlet air pressure to said float valve assembly to maintain the level of liquid in said reservoir under gravity level control,

a secondary air inlet in said housing for admitting secondary air into said vaporized fuel stream prior to entry into said outlet tube,

a flange on said outlet tube for directing air pulses from said outlet tube into said secondary air inlet, said secondary air inlet comprising a tube aligned with said outlet,

and means for controlling the flow of secondary air into said housing.

9. The carburetor according to claim 8 wherein said gravity level control means includes a stand pipe connected to the float valve assembly and positioned to respond to the pressure of air upstream from said wet vaporizing filter.

10. The carburetor according to claim 8 wherein said secondary air inlet includes a pressure responsive flap.

11. The carburetor according to claim 8 including means on said baffle for extending the air flow path through said liquid reservoir.

12. The carburetor according to claim 8 including a bubble break screen downstream from said wet vaporizing filter.

13. The carburetor according to claim 12 wherein said bubble break screen comprises a strip of wire cloth folded to an accordian shape.