US2711883A

US2711883A - Carburetor

Info

Publication number: US2711883A
Authority: US
Inventors: Reeves Edward
Original assignee: Individual
Current assignee: Individual
Priority date: 1952-10-09
Filing date: 1952-10-09
Publication date: 1955-06-28
Anticipated expiration: 1972-06-28

Description

Unite This invention relates to a down draft type carburetor for an internal combustion engine.

In the carburetor of an internal combustion engine, there is a barrel portion providing a conduit through which atomized fuel and air flow to the intake manifold. In this conduit or duct there is a throttle valve to control the passage of the gas therethrough.

Along the outside of the conduit of the barrel portion there is a channel for conducting fuel and air mixture to openings through the barrel wall for passage of the mixture from this channel to the barrel conduit during slow running of the engine. A solid adjusting screw is usually provided to control the passage of mixture into the barrel.

In the conventional type down draft carburetor, the fuel to air ratio is very high during slow running conditions, and it is very essential to have good atomization and a homogeneous mixture and to avoid a patchy wet mixture which causes excess wear on cylinders and pistons when starting a cold engine, also uneven running and waste of fuel under slow running conditions.

One of the objects of this invention is to provide a special screw which may be substituted for the usual adjusting screw for the slow running control of the engine to further reatomize the mixture which is being drawn from the slow running channel through the opening controlled by the adjusting screw.

Another object of the invention is to attain smoother running of the engine under slow running conditions due to having a better homogeneous mixture and also to prevent stalling of the engine, which could be very dangerous under road driving conditions.

Another object of the invention is to make starting of the engine easier under cold weather conditions by reason of further atomization of the fuel.

Another object of the invention is to make the engine States Patent l respond more sharply to a small movement of the adjusting screw when making idling adjustments to the carburetor.

With these and other objects in view, the invention consists of certain novel features of construction as will be more fully described and particularly pointed out in the appended claims.

In the accompanying drawing:

Figure l is a sectional view of the lower portion of a down draft carburetor;

Figure 2 is a side elevation of my device on a larger scale than that shown in Figure 1 and separate from installation;

Figure 3 is an end view of Figure 2.

In proceeding with thisinvention, I have provided a screw which may be substituted for the slow running adjusting screw, usually a part of the carburetor. I have provided an axial bore from the conical end of the adjusting screw, this axial bore being connected to a series of holes bored transversely through the adjusting screw in such a position as to connect a passage from the slow running channel to the bore in the adjusting screw when ice fitted in the carburetor. By this arrangement fuel mixture from the slow running channel will partially bypass the conical seating for the adjusting screw.

With reference to the drawing 10 designates the carburetor barrel through which there is a conduit 11 for air when the engine is running slow or for the air and gas mixture to the intake manifold of an internal combustion engine at high speed. A throttle valve 12 is 1ocated in this conduit pivoted on the spindle 13 by which a control of the conduit 11 may be provided for. Along the wall 14 of this barrel there is formed a channel 15 which supplies air and gas mixture, this channel having communication with the conduit 11 of the barrel by means of openings through the wall 14 at 16, 17, and

' 18. The opening 18 is provided with a conical seat 19 at the entrance end of the opening which is adjacent the channel 15.

A slow running adjusting screw 29 is threaded through a boss 21 of the barrel at a location where it will cross the channel 15 and is generally cylindrical at 22 but is provided with a tapered or conical end portion 23 to engage the seat 19 and close the passage or by reason of its being slightly open to control the volume of air and gas which may pass through the opening 18. This slow running adjusting screw is provided with a handle or head 24 at one end, while at the other end it has an axially extending bore 25 from its small end inwardly and is also provided with a plurality of radially extending bores 26 extending from the cylindrical diameter 22 of the screw inwardly to join the bore 25. The radially extending bores 26, although preferably at a point beyond the taper 23, may be at any location sufliciently so that the high point of one of these bores 26 will always be above the seat 19 of the opening 18.

A head 24 on the end of the screw provides a convenient handle for operating the screw, while a spring 27 provides sufiicient tension on the screw threads so that the adjusting screw will maintain the position to Which it is adjusted.

The air during slow running will pass as shown by the arrows inwardly through opening 16 to channel 15 and back to the conduit 11 through

openings

17 and 18 and more particularly the gases about the adjusting screw operate as further described below.

In the functioning of the adjusting screw, the mixture being drawn down the slow running channel 15 when coming in contact with the channel walls and conical seat 19 for the adjusting screw 29 has a tendency to liquefy and de-atomize due to the fuel being the heavier part of the mixture. During this movement of the mixture the air from the conduit passing through duct 16 and lighter mixture is partially drawn through the bore 25 in the adjusting screw 20. Owing to the orifice of the transverse holes 26 being at a higher level than the adjusting screw conical seating 19, this lighter mixture, or air, by-passes the conduit between the adjusting screw taper 23 and conical seating 19 and passes through the center bore 25 of the adjusting screw reatomizing the heavier mixture, or fuel, passing between the conical seatings 19 and cone of the screw 23 into the conduit 11 of the carburetor and ensuring a homogeneous mixture.

The opening between the conical seating 19 and the surface 23 of the adjusting screw is approximately .007 as compared to approximately .015 with the conventional type. This condition is due to the fine bore, which is approximately .010", in the adjusting screw which partially by-passes a quantity of the slow running mixture, or air and fuel. This condition enables the adjusting screw 20 to have a relatively closer position to its seating which gives an increased area ratio in relation to the same axial movement of the adjusting screw 20; that is, the area ratio between movements for any small movement of a cone when nearly closed is greater than succeeding area ratios for any equal additional movement.

This being accomplished, the engine in slow running conditions is much more sensitive and responds more quickly for a given movement of adjusting screw 20. When adjusting the conventional screw, there is a time lapse between movement of the screw to engine response owing to the movement and inertia of the mixture, the tendency when adjusting the carburetor being to overturn the screw due to delayed response of engine, making adjustment difiicult for the average individual. With my adjusting screw 20 having an increased ratio in relation to a given movement of the screw 20, adjustment is much easier and more accurate, for the adjustment of this screw plays a very important part regarding fuel consumption.

I claim:

1. In a carburetor of the downdraft type a barrel having a conduit therethrough, a throttle valve to control the passage of gases through said conduit, a slow running channel with a wall between it and the conduit having an opening therethrough from the channel to the conduit, an adjusting screw having a portion adjacent but spaced from the wall of said opening for controlling said opening and said adjusting screw having a passage therethrough communicating with said conduit and said channel at a location in said channel in advance of the portion of the opening controlled by the screw to by-pass some of the controlled gases.

2. In a carburetor as in claim 1 wherein the wall about said opening has a conical seat and said screw has a conical end to move toward and from said seat to control said opening.

3. In a carburetor as in claim 1 wherein said passage has an axial opening along said screw from the conical end and radial openings extending therefrom to said channel.

4. In a carburetor as in claim 2 wherein said passage has an axial opening along said screw and radial openings extending therefrom to said channel at a location inwardly of the conical seat.

5. In a carburetor as in claim 1 wherein a portion of the passage through said screw is at a height above the conical seat.

References Cited in the file of this patent UNITED STATES PATENTS 1,761,007 Claudel June 3, 1930 1,781,087 Stapelle Nov. 11, 1930 1,798,461 Fauser Mar. 31, 1931 2,341,694 Cofiey Feb. 15, 1944 2,590,217 Snyder et al. Mar. 25, 1952 FOREIGN PATENTS 363,969 Germany Nov. 16, 1922 454,698 Great Britain Oct. 6, 1936