US2093205A - Carburetor - Google Patents

Description

Sept 14, 1937- v J. E. MULLEN, JR 2,093,205

CARBURETOR Filed Deo. 5, 1934 5 Sheets-Sheet 1 QD QB Sept. 14, 1937. J. FJMULLEN, JR

CARBURETOR 3 Sheets-Sheet 2 Filed Dec. 5, 1934 Sept. 14, 1937.

Filed Dec. 5, 1934 J. F. MULLENl JR cARBUREToR y 3 Sheets-Sheet 3 lglg Patented Sept. 14, 1937 UNITED STATES PATENT OFFICE 19 Claims.

This invention relates to carburetors, such as those employed on internal combustion engines, and more particularly to those in which the gasoline or other liquid fuel is automatically fed into the incoming stream of air by gravity, as well as by suction.

Generally stated, the object of the invention is to provide a novel and improved construction and arrangement whereby the combined gravity and suction feed is more efficiently employed in a carburetor of this general character, thereby to increase the-eiliclency of the engine or motor, and to increase the mileage per gallon of. fuel.

It is also an object to provide certain details and features of construction and combinations tending to increase the general eiiiciency and the desirability of a carburetor of this particular character.

To the foregoing and other useful ends, the invention consists in matters hereinafter set forth and claimed and shovm in the accompanying drawings, in which- Fig. 1 is a plan view of the carburetor embodying the principles of the invention.

Fig. 2 is a section on line 2 2 in Fig. 1 of the drawings.

Fig. 3 is a detail or fragmentary section on line 3 3 in Fig. 1 of the drawings.

Fig. 4 is a plan view showing a double-barrelled carburetor, instead of the single-barrelled carburetor previously described.

Fig. 5 is a vertical section on line 5 5 in Fig. 4 of the drawings.

Fig. 6 is a horizontal section on line 6 6 in Fig. 5 of the drawings.

Fig. l is a vertical section o`n line 'I 'I in Fig. 4 of the drawings.

Fig. 8 is a vertical section on line 8 8 in Fig. 4 of the drawings.

Fig. 9 is a fragmentary detail sectional view showing a different form of the invention.

Fig. 10 is a similar view showing another form of the invention.

Fig. 11 is a view similar to Fig. 2, showing a different form of the invention.

As thus illustrated, referring to Figs. 1, 2 and 3 of the drawings, the carburetor has a float chamber I provided with a float 2 of ordinary form, which maintains the level of the fuel at line 3, normally, in the manner shown in Fig. 2 of the drawings. 'I'he body 4 of the carburetor has an upper air intake chamber 5, provided with the ordinary choke valve 6, and this chamber is connected by the Venturi tube passage 'I with the lower chamber 8, containing the ordinary throttle valve 9, as shown. This is what is called a down draft carburetor, and the bottom portion I0 is bolted to the intake manifold of the engine or motor.

It will be seen that the walls of the float chamv5 ber I are provided with a passage II that connects at one end to the fuel inlet nozzle I 2, in the Venturi tube passage 1, and that connects at its upper end to the vertical passages I3 and I4, the latter having its inlet end slightly below 10 the level of the fuel, and the passage I3 having its lower inlet end I5 near the bottom of the float chamber. An auxiliary fuel nozzle I6 is also disposed in the Venturi tube passage, as shown, and is connected by passages I'I, I8 and I9 with 15 the outlet 20 near the bottom of the float chamber. It will also be seen that the oat chamber l has an air inlet passage 2I to maintain the required atmospheric pressure in the upper portion of the ioat chamber.

-20 In the other side of the carburetor body, there is a vertically disposed cylindrical chamber 22 in which the valve body 23 is movable up and,l

down, this valve body having an upper coneshaped valve 24for engagement with the tapered 25 valve vseat 25 at the top of the said chamber.

This valve seat 25 is connected by a passage 26 with the passages II and I8, as shown in dotted lines in Fig. 2 of the drawings. A coil spring 21, applied as shown, serves to hold the valve 24 in 30 normally raised or closed position. The lower end of the chamber 22 is connected by a passage 28 with the throttle valve passage 8, at a point below the valve 9, as shown in the drawings. An air vent 29 connects the upper portion of the 35 chamber 22, above the valve body 23, to the chamber 5 where the air enters the carburetor.

As shown in Fig. 3, the float 3 operates the ordinary or suitable inlet valve 30 to automatically admit fuel to the oat chamber, and to shut o. 40 the fuel at the right time, thereby to normally maintain the fuel level at the line 3, as shown in Fig. 2 of the drawings.

'I'he height of the fuel level 3 above the jet or nozzle I2 provides what is known as a positive 45 static head. I

Before the engine is started, the liquid fuel level is approximately at the line 3I, which is a slight distance below the inlet opening 32 of the passage I4, and the valve 24 is tightly against its seat 25, 50 so that no air can enter the passage 26 and the passage I1, but when the motor is started, then the liquid fuel from the pump, such as the ordinary feed pump on a motor vehicle, brings the level of the fuel in the float chamber a slight 55 2 distance above the opening 22, in the passages I2 and I4, and thereby seals these passages, in order that no air may gain an entrance through the opening 22, in a manner that will be readily understood. The suction caused by the pistons of the motor causes air to flow into the carburetor at the inlet passage 9, through the Venturi passage 1, past the throttle 9, and then to the intake manifold of the motor. This suction, operating through passage 29, causes the valve 24 to move downwardly away from its seat 25, and causes a suction action at the outlets of the jets and nozzles I2 and I6, and the suction causes the fuel to flow through passage II to jet I2 where it mixes with the air flowing through the carburetor. The suction which acts on jet I9 tends to cause the liquid fuel to flow through passages I1, I2 and I9, but this is prevented, for the reason that air is free to enter through the passage 29, and consequently the suction is not suiflcient to raise the fuel in passage I2 high enough to overflow through the passage I9 into the passage I1. When, however, the throttle 9 is suddenly opened,

or the suction of the intake manifold is decreased sufficiently, the spring 21 forces the valve 24 upwardly against its seat 29 and thereby closes the air passage 29, so that the suction is then effective to raise the fuel in passage I9 and cause it to overflow through the passage I 9 into the passage I1, and to cause it to discharge from the Jet I6 into the air flowing through the carburetor. In this way, the acceleration is automatic. so to speak, and the fuel is fed into the air stream by gravity, as well as by suction, for the passages I I and I1, it will be seen, are really parts of two siphons that would permit the feeding of the fuel by gravity until the level of t he fuel reaches the outlet openings I9 and 20 near the bottom of the oat chamber; but. of course, as shown in Fig. 2, the passage I1 cannot function as a gravity siphon if the passage 2l is open, and, of course, for the siphon passage II to drain the fuel in the carburetor down to the level of the opening Il would require that the opening 22 be closed: but, in effect, as stated, the passages II and I1, in combination with the passages I2 and I9, constitute siphons that operate by gravity to feed the fuel into the incoming current of air, and that also operate by suction.

And, in addition, it will be understood that in Fig. 2 of the drawings the valve 24 is shown nearly closed, inasmuch as at this time. with the throttle 9 in the position shown, or even in a somewhat more closed position, there is some suction exerted in the passage 2l, sufiicient to maintain the valve 24 slightly open, so that the lsiphon passage I1 will not function to feed fuel to the mixing chamber; but, when the engine is accelerated, by completely opening the throttle 9, suction on the passage 22, by the engine, will practically cease, and the valve 24 will close, thereby shutting oil' the emission of air to the passage 22, andv at such time the passages I1 and I2 and I9 will operate to feed fuel into the mixing chamber.

'I 'he carburetor shown and described is, in general principle, what is ordinarily called a down draft carburetor. However, it is obvious that the invention can be employed in an up draft or a side draft carburetor, equally well, inasmuch as the combination suction and gravity feed, with the positive `static head principle, is adapted to work or function on all of these different types of curburetor.

Obviously, when the motor stops, there will be a little discharge of fuel into the passages 1 and 2, from the jet I2, and perhaps from the Jet Il, but'this will simply serveto prime the engine when it is again started. In Figs. 4, 5, 6, 7 and 8, the construction is substantially the same as that previously described, but in this case the device is what is called a double-barrelled carburetor, instead of being single-barrelled like the one previously described. In this case, therefore, the carburetor has two downwardly extending mixing passages 22 and 22, arranged side by side, and with the fuel jets 24 and. 25 extending into the restricted or Venturi portions of these passages. these Jets being connected .to the float chamber 26 in the manner previously described, and the arrangement being substantially the same, except that the carburetor is double, so to speak, having twice as many fuel Jets and having a throttle valve 2l for the lower end of each passage 22, to throttle or vregulate the mixture passing from the carburetor into the intake manifold of the motor.

Referring to Fig. 9, the construction is similar to that shown in Fig. 2 o'f the drawings, but in this case the action is somewhat different, inasmuch as the float chamber has no siphon inlet 22, and has instead merely the one inlet 29, and a small air hole 29 communicating with the top or bend of the siphon.

In Fig. 10, the construction is similar to that shown in Fig. 2 of the drawings, except in this case there is no full opening 22, but instead there is a very small restricted opening 29 at the lower end of the upper ieg of the siphon.

Referring to Fig. 11, it will be seen that the construction here is similar to that previously described, but in this case the mixing chamber 42 is straight and has no Venturi portion where the jets 4I and 42 are located therein. Also, in this form of the invention, the float chamber has no siphon inlet 22, but has only the lower siphon opening 42, so that the jet 4I is only connected through the opening 42 with the fuel chamber. However, the top of the siphon has a passage 44 leading to the air chamber 49, into which air enters through the passage 49, when the valve 41 is in raised or normal position. 'Ihe upper end of the valve stem 49 has a plunger head 49 that fits the chamber 59 in which the coil spring 5I is located, which spring keeps the valve and the plunger in normally raised position. The top of the chamber 99, above the plunger 49, is provided with an air vent 92,- as shown. A passage I2 extends from an opening 94 in the side oi the passage 40, below the throttle 59, to an opening 56 at the bottom of the chamber 59, whereby, under the suction of the engine, exerted through the passage 52, the plunger 49 will be sucked downwardly, causing the valve 41 to close the passages 44 and 49, thereby shutting off the entrance of any air into the siphon passage which leads to the jet 4I previously mentioned.

In each form of the invention, therefore, except in Fig. 1l, it will be seen that the fuel has two levels in the float chamber, the normal level being. somewhat lower than the level at which the fuel is maintained during the-running of the engine or motor, as in each case some fuel drains out of the siphon passages when the motor stops, thus lowering the level of the fuel in the float cham-- ber. Also, therefore, in each form of the invention, there is a positive static head that characterizes the combined suction and gravity feed of the fuel. This, it is found, in actual practice, insures greater efficiency for the engine or motor,`

and better mileage per gallon in the consumption of the fuel.

With further reference to Fig. 9, it will be understood that the air inlet Il is preferably so small that the passage of air therethrough will not break the siphon action while the engine is running; but, `when the engine stops running, then the opening Il is sufllcient to admit enough air to break the siphon action, preventing the siphon passages from draining the fuel down to the level of the opening 38, as will be readily understood.

Furthermore, in connection with Fig. l of the drawings, it will be understood that the opening 39 is also so small that, should the automobile lurch to one side, and thereby cause the level of the fuel to momentarily go below this opening, the intake of air will not be sufficient to break the siphon action at such time; but, of course, when the engine stops running, and the level of the fuel then goes below the level of the opening 39, the

latter is then operative to admit enough air tov break the siphon action and stop the draining of the fuel into the mixing passage or chamber of the carburetor.

It will be seen, therefore, that in each ferm of the invention there are means forming in effect a siphon between the float chamber and the air passage, adapted to feed the fuel by suction of gravity into the air stream, forming the main fuel passage from the float chamber to the mixing chamber, all of the elements being co-ordinated to maintain the level of the fuel in the float chamber at a point high enough above the lower outlet `end of the siphon to maintain a positive static head, while the motor is in operation, and that this is true of each of the different forms of the invention shown and described.

In each form of the invention, it will be seen. 40 both gravity and the suction of a Venturi tube are employed, along with a main fuel passage that is normally open and free from direct manual control, for the main fuel passage in each form of the invention is without any manual 45 throttle control, and is normally open, and this also holds good for the power range, in each form of the invention. For acceleration, in each form of the invention, there is a vacuum operated valve, to increase the flow of fuel, but without 50 restricting the intake of air. lAlso, the flow at idling, in each form of the invention, is almost entirely by gravity because of the low velocity of air through the main barrel of the carburetor. Then, as the ow of air increases, the suction of 55 the venturi becomes stronger, and the gravity feed alone gets weaker, relatively, as the air flow increases, whereas the suction feed gets stronger, thus insuring more approximately the ideal combination of gravity and suction feed.

Thus, with the construction shown in Fig.- 2 of the drawings, when the throttle 9 is opened sufficiently to cause an appreciable drop in the intake manifold vacuum, the valve 23 automatically seats itself, thus cutting off the air supply to the 65 nozzle I6, which causes fuel to discharge from the nozzle I6, thus giving the needed increase in mixture strength for acceleration, or for carrying an increased load at about the same speed.

, Of course, the throttle 9 need not be opened wide- 70 to cause the appreciable drop in the intake manifold vacuum. In Fig. 1l of the drawings, the Vvalve 41 remains closed as long as the engine is running, or is being turned over by the starting motor or by hand, for as long as the engine is 75 being turned over there is always more or less vacuum at I4, which serves to keep thevaive l1 closed. Preferably, the spring II under the valve l1 is of such strength or tension that the valve 41 opens when an appreciable drop in the intake manifold vacuum occurs, and under such conditions fuel stops discharging from the nozzle- II and the engine runs on the discharge from nozzle 42 only. Therefore, the spring 21 under the valve 23 is preferably slightly stronger than the spring I under the valve 41, in order that fuel may flow out of the auxiliary siphon before the ilow in the main siphon is stopped, and will continue for a short time after the valve 41 is closed, to give the main passage time to start. This overlapping of flow, as between the two siphons, tends to prevent any stoppage of the flow of fuel to the engine or motor. Therefore, air is admitted to the main siphon, in Fig. 11, to stop the flow of fuel, so that the float bowl will not be drained ywhen the engine stops. Similarly, air is` admitted to the auxiliary siphon to prevent acceleration, when acceleration is not wanted, and to prevent the draining of the float bowl when, in starting the engine, the motor fails to respond promptly. The spring under the valve 2l may be sufficiently strong to hold this valve in seated position while the engine is being turned over by the starter or by hand. This causes fuel to flow out of the nozzle I6, as well as out of the nozzle I2, and then, if the motor fails to respond, and the starting is momentarily abandoned, the air inlet to the auxiliary siphon prevents draining of the float bowl.

It will be seen that, in each form of the invention, the passage 26 forms the sole air admission to the auxiliary fuel feed pe formed by the passages I1, I8, and Il, as there is no other way in which air can enter this siphon passage, and hence the suction opening at the lower end of the passage 28 has entire control over the admission of air to the auxiliary fuel feed passage.

In each form of the invention, therefore, the main siphon fuel passage has means for admitting air thereto, in one way or another, to prevent drainage of the iloat chamber. In Fig. 2 air is admitted at 32, when the level of the fuel is lowered, while in Fig. 9, air is admitted at 39, sufficiently to insure the desired result, and in Fig. 10 air is admitted at 39 to prevent drainage; and in Fig. l1, as explained, airis admitted to the main fuel passage at 44, in the manner explained; whereby, in each form of the invention, the main fuel passage is incapable of draining the iloat chamber, as for example when the engine stops running.

What I claim as my invention is:

1. In a throttle controlled carburetor for a motor, means providing a general air passage through which the air ows to the motor, providing a mixing chamber, means providing a float chamber for the liquid fuel, and means forming in effect a siphon between the float chamber and the air passage, with a fixed inlet and fixed outlet, adapted to feed the fuel by suction and gravity into the air stream, forming the main fuel passage from the float chamber to the mixing chamber, normally open, free at all times from any direct manual regulation or valve control, with means to admit air to said passage to prevent draining of the float chamber, all co-ordinated to maintain the level of the fuel in the float chamber at a point high enough above the outlet end of the siphon to maintain a positive static head, while the motor is running, to provide the same gravity and suction feed for both the power range and the economy range.

2. A structure as specified in` claim 1, comprising an auxiliary siphon passage for feeding fuel from the float chamber to the air passage, by suction and gravity, together with an automatic 5 valve and an air passage controlled thereby to the auxiliary siphon. for automatically feeding additional fuel to the air stream for acceleration.

3,. A structure as specified in claim l, said siphon having two inlets in the float chamber, one inlet a substantial distance below the other.

4. A structure as specified in claim l, said siphon having two inlet openings in said float chamber, one above the other, the upper opening being below the said level of the fuel when the engine is running, but above the level of the fuel when the engine is not in operation, and the other opening being near the bottom of the float chamber.

5. A structure as specified in claim 1, comprising auxiliary means for automatically feeding fuel from the float chamber to the air stream, by suction and gravity, for acceleration, and valve means controlling the air stream and thereby indirectly controlling the feeding of fuel to said stream.

6. In a carburetor for a motor, means providing a general air passage through which the air flows to the motor, means providing a float chamber for the liquid fuel, means forming in effect a siphon passage between the float chamber and the ali` passage, adapted to feed thefuel by suction and gravity into the air stream, cooperating with the float and the inlet controlled by the latter to maintain the level of the fuel in the float chamber at a point high enough above the lower outlet end of the siphon to maintain a 1 positive static head, while the motor is running,

said siphon having two inlets in the float chamber, one inlet a substantial distance below the 40 other.

7. In a carburetor for a motor, means providing a general air passage through which the air flows to the motor, means providing a float chamber for the liquid fuel, means forming in 45 effect a siphon passage between the float chamber and the air passage, adapted to feed the fuel by suction and gravity into the air stream, cooperating with the float and the inlet controlled by the latter to maintain the level of the fuel in 50 the iloat chamber at a point high enough above the lower outlet end of the siphon to maintain a positive static head, while the motor is running,

said siphon having two inlet openings in said float. chamber, one above the other, the upper 55 opening being below the said level of the fuel when the engine is running, but above the level of the fuel when the engine is not in operation, and the other opening being near the bottom of the float chamber.

8. In a carburetor for a motor, means providing a general air stream passage through which the air flows to the motor, means providing a float chamber for the liquid fuel, means forming in effect a siphon passage between the float G5 chamber and the air passage, adapted to feed the fuel by suction and gravity into the air stream, co-operating with the oat and the inlet controlled by the latter to maintain the level of the fuel in the float chamber at a point high 10 enough above the lower outlet end of the siphon to maintain a positive static. head. while the motor is running, van auxiliary siphon passage between the float chamber and the air stream passage, for feeding fuel from the float chamber to 75 the air passage, by suction and gravity, together with means including an automatic valve and an air passage controlled thereby, for automatically feeding additional fuel through the auxiliary siphon passage to the air stream for acceleration.

9. In a carburetor for a motor, having an air inlet control, suction and gravity siphon feed means providing' a main feed passage for feeding the fuel in the same way for both the economy range and the power range, and separato auxiliary suction and gravity siphon feed means to lincrease the flow of fuel for acceleration, operable independently of said air inlet control.

10. A structure as specified in claim 9, said siphon means having a plurality of fluid inlets.

1l. A structure as specified in claim 9, said auxiliary means comprising a siphon fuel feed passage having a plurality of fluid inlets one of which is an air inlet controlled by a suction operated valve. y

12. A structure as specified in claim 9, said siphon means having an air inlet.

13,'A structure as specified in claim 9, said auxiliary means having an air inlet.

14. A structure as specified in claim 9, said siphon means having a plurality of fuel inlets.

15. A structure as specified in claim 9, said main uell passage being free from direct manual con- 16. In a carburetor for a motor, a throttle valve, means forming a siphon fuel feed'passage, for feeding the fuel by suction and gravity to the interior of the carburetor, in the same way for both the power and the economy range, and valve means controlled by a suction passage leading to an opening between the throttle valve and the motor for at certain times preventing feeding of the fuel by admitting air to the top of the siphon. forming the sole air admission to said fuel passage, said siphon forming anauxiliary acceleration fuel feed passage, and another siphon forming the main fuel feed passage.

17. A structure as specified in claim 1, in which the carburetor is of the double-barrelled type, having two air passages with the said siphon fuel feed passage arrangement for each barrel or air passage, and with the said single float chamber common to both barrels of the carburetor.

18. In a carburetor for a motor, means providing a general air passage through which the air flows to the motor, means providing a float chamber for the liquid fuel, means forming in effect a siphon passage between the 'float chamber and the air passage, forming the main fuel passage to the mixing passage, normally open, free at all times from any direct manual regulav tion or valve control, adapted to feed the fuel by suction and gravity into the air stream, cooperating ,with the float and the inlet controlled by the latter to maintain the level of the fuel motor, means providing a general air passage 'through which the air flows to the motor, means the main fuel passage to the mixing pesage, normally open, free at all times from any direct manual valve control, adapted to feed the fuel by suction and gravity into the air stream, cooperating with the iioat and the inlet controlled by the latter to maintain a positive static head, while the motor is running, the said carburetor being of the double-barrelled type, having two air passages with the said siphon fuel passage arrangement for each barrel or air passage, and with the said single iioat chamber common to both barrels of the carburetor, a throttle for each barrel, and air admission control means having a suctioncontrol opening between each throttle and the engine.

JAMES F. MULLEN, JR;

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