US2278305A - Carburetor - Google Patents

Description

March 31, 1942.

J. 5. CULP I QARBURETOR Filed July 15, 1940 3 Sheets-Sheet 1 FIG.

K IO

ZZZ/$4 0 lllmlllll "nut/null, 1/1/1111. 1/1/11 9 INVENTOR ATTORNEY March 31, 1942. S ULP 2,278,305

CARBURETOR Filed July 15, 1940 3 Sheets-Sheet 2 F1651 I FIG.4

A'IT RNEY J. S. CULP March 31, 1942.

CARBURETQR Filed July 15, 1940 3 Sheets-Sheet 3 III INVENTOR ATTORNEY Patented- Mar. 31, 1942 Q-UNITED STATES PATENT OFFICE CARBURETOR Jay S. Culp, Detroit, Mich.

Application July 15, 1940, Serial No. 345,552

8 Claims.

This invention relates to carburetor and controls therefor.

It is an object of the present invention to provide for internal combustion engines a carburetor which will meter fuel properly at all pressures within the desired or usual pressure range.

Another object of the invention is to provide a carburetor in which delivery of fuel to a mixing chamber is substantially not affected or aided directly by engine created suction.

Another object of the invention is to provide a fuel metering device or carburetor which cannot be flooded or be supplied with excess fuel by operation of the accelerator.

Another object of the invention is to provide a new and improved carburetor of a character which will stop flow of fuel to the engine immediately upon stopping'of the engine.

Another object of the invention is to provide a new and improved carburetor which meters both fuel and air automatically in response to engine operation or engine created suction.

Another object of the invention resides in the provision of a control or choke for the carburetor by means of which the combustible mixture may be enriched. without adding fuel thereto.

Another object of the invention is to provide a new and improved carburetor having a control or choke operable to govern engine speed.

Other objects of-the invention will become apparent from the following description taken in connection with the accompanying drawings in which:

Figure 1 is a view shown in side elevation of a fuel delivery control system for internal combustion engines;

Fig. 2 is a view in section of part of my carburetor, taken along the line and in the direction of the arrows 2-2 of Fig. 4;

Fig. 3 is a view, partly in section and partly in elevation, of part of my carburetor and taken along the lines and in the direction of the arrows 3-3 of Figs. 4 and 5;

Fig. 4 is a view shown in section of the carburetor, taken along the lines and in the direc-I tion of the arrows 4-4 of Figs. 2 and 3;

Fig. 5 is a View in side elevation of the carburetor showing operating parts in certain positions they will assume under certain conditions of engine operation;

Figs. 6 and '7 are views similar to Fig. 5 showing the operating parts in other positions they will assume;

Fig. 8 is an enlarged view in elevation of the carburetor showing operating parts thereof in Fig. 9 is a vertical sectional View of the carburetor.

Referring to the drawings by characters of reference, my fuel delivery control system comprises in general a fuel and air metering device or carburetor ill, and it also comprises a fuel delivery pump l, which willnot be described herein because it does not, in and of itself, form a part of the present invention. The carburetor II! includes a casing l2 having a duct I3 extending therethrough, one end of which duct, as at M, may be connected and rigidly secured to a fuel intake manifold of an internal combustion engine (not shown). In communication with the other end of the carburetor duct I3, such as at 15, the usual air cleaner or filter is provided and includes a sheet metal casing It which is open at its top as is usual, and encloses and supports a felt filter ll which overlies the carburetor intake, as at it.

Referring more. particularly to the enlarged view of Fig. 9, the carburetor duct I3 is provided intermediate its ends with a transverse wall 2t having a bore extending longitudinally therethrough transversely to the direction of air flow to receive and in which is secured a tubular fitting 2! to the outer end of which is connected a fuel v supply line or conduit 22 leading from the outlet side of the fuel pump H. The tubular fitting 2! is provided internally thereof with a metering aperture and valve seat 23 which is controlled by a reciprocal valve 2 3 of the so-called needle type,

i this valve, as will later be seen, being actuated in accordance with the vacuum created by an engine controlled by my fuel delivery system.

intersecting the tubular fitting 2!, the transverse wall 26 is provided with a bore to receive a nozzle member 25 which communicates at one end thereof, posterior to the valve seat, with the I tubular inlet fitting 2| and extends longitudinally of the duct l3 to discharge the fuel into a mixture chamber 26 communicating with the engine intake manifold. Above the fitting 2!, the wall 29 is provided with an air passage 26a, parallel with the fuel passage, the air passage 260. being in communication With the interior of the casing l2 and being connected by a bore 2i with the interior of the fitting2l posterior and adjacent to the valve seat 23. At this point it should be noted that fuel is delivered to the mixing chamber 26 solely by the pump 1 I, that is, the suction created by the engine has substantially no drawing effect on the fuel untilthe fuel has passed through valve seat aperture 23. At its upper end the casing l2 communicates with the air filter casing I6 through the opening in the lower end thereof so that air will be drawn from the filter casing l6, carburetor casing l2 and passages 26a and 2'0 to meet with the fuel at the metering valve.

. Other air will be drawn through the duct l3 to intermingle and mix with the fuel at the discharge end of the nozzle which as shown in Fig. 2 is elongated and rounded at its upper end to reduce air flow and induce flow to the lower discharge end of the fuel nozzle 25 for flow of air therearound.

Within the carburetor casing I2, a chamber 28 is provided and communicates with the engine intake manifold, the chamber 28 being formed in part by a movable cup-shaped member or piston which is slidably mounted in the chamber 28. Within the mixing chamber 26 is secured a tubular sleeve 29 having its outer side Wall surface spaced from the inner side wall surface of the duct l3 provide an annular chamber 29a which communicates with the intake manifold, and the expansible chamber 28 is in communication with chamber 29a by connecting passages or bores 29b and 290. The cup-shaped piston 30 is provided with a concentric cylinder 3| therein to receive a pressure responsive member or piston 32 which is also movable in response to the sub-atmospheric pressure created by the engine and is operatively connected to the fuel metering valve 24. The piston 32 is cup-shaped, in the present instance, and is slidably mounted in and therefore carried by the piston 30, the piston 32 being movable with and also relative to the piston 30. The piston 30 is provided with an aperture 33 in an end wall 34 thereof establishing communication with the relatively large expansible chamber 28, and an opposite end wall 35 on piston 32 is provided with a tubular extension 36 which receives and to which is secured the stem 31 of the metering valve 24. Within the piston 32, a helical coil spring 38 urges the piston in a direction to seat the valve 24. Also a helical coil spring 39 within the expansible chamber 28 acts to urge the piston 30 in a direction to seat the metering valve. As previously mentioned the piston 32 is slidably movable relatively to the larger piston 30, the inner wall of the larger piston having an internal shoulder 54 providing a stop for limiting relative movement of the pistons.

It will be seen that variations in suction or in the pressure created by operation of an internal combustion engine will move the pistons which will in turn actuate the metering valve 24 to control delivery of fuel to the mixing chamber 26. That is, metering of the fuel will be in accordance with operation or need of fuel for the engine.

Above the conduit wall 29 and within the duct I3 there is a butterfly valve 33a, mounted on a shaft 340., for controlling intake of air and, as will later be seen, this valve is manually operable and also automatically operable in response to engine created suction. Opposite ends of the butterfly valve shaft 34a are journaled in the side wall of the duct l3 and secured to one end of the shaft 34a externally of the duct 13 is an operating lever 35a. This lever 35a is provided with an arcuate slot l9 wherein is slidably received a bearing member or pin 31a which is secured to one end of a link 38a, the other end of the link 38a being pivotally connected by a pivot pin 39a to the upper end of a lever 40.

This constitutes a loose or lost-motion connection between the lever 40 and the air throttle valve operating lever, the purpose of which is hereinafter fully described. The lever 40 is pivoted at its lower end by a pin 41 to an adjustably movable fulcrum member 42 which is screwthreaded onto a horizontally extending screw 43 by means of which the fulcrum member 42 may be readily and easily moved to adjust the ratio of fuel and air, as will later be seen. A laterally extending abutment 45, integral with the lever 40 intermediate the ends thereof, is loosely engaged by or in abutment with the free end of a lever-46 which is mounted on a shaft 41 having one end thereof extending externally of the casing l2 to which an operating lever 48 is secured, the operating lever 48 being connected by suitable linkage to the usual manual control or accelerator pedal (not shown). At its upper end, a lever 50 is pivoted to the casing l2, adjacent the top thereof, by a pin or small shaft 5| and this lever 50 is of the yoke type, having a pair of spaced depending arms 52 which straddle the piston 30, the arms 52 being. provided at their lower ends with opposed inwardly directed, extended portions 52a adapted to engage in a socket or external annular recess 53 of the piston 30. One of the lever arms 52 is pivotally connected adjacent its lower end to the air throttle operating lever 40 by thev pin 45 which, as previously mentioned, serves as an abutment for the lever 46. Thus, piston 30 operating in response to engine created vacuum is adapted to pivot the lever 50 and through lever 50 to pivot air throttle lever 40. During idling operation of an engine, the smaller piston 32 is free to move by suction, to the left, facing Fig. 9, and open the fuel metering port 23 sufiiciently to maintain combustion at idling speed operation, movement of the piston 32 to the left or in a valve opening direction being limited by the internal abutment flange 54 provided in the larger piston 30. The larger piston 30 is biased to the right, Fig. 9, by the usual accelerator pedal return spring (not shown) or the pump pressure spring acting on the lever 40 through the lever 46. It will be seen that when the operating lever 48 is pivoted by operation of the foot accelerator, in a counterclockwise direction, Figs. 5 and 6, the large piston 30 will be moved to the left, Fig. 4, by the engine suction permitting the smaller piston 32 to move to the left to further openthe fuel metering port 23. Also, the pivoting of lever 40 in a counterclockwise direction by the larger piston 30 moves the butterfly valve, through connecting link 38a toward open position. When the operating lever 48 is moved to its extreme open position, as shown in Fig. 8, the large piston 30, Fig. 9, will be stopped by abutment with its cylinder end wall cover or gasket, and further movement of the smaller piston 32 will be limited by the internal shoulder 54 of the larger piston so that with the parts in these positions the butterfly valve 33a and the metering valve 24 are in full open position.

A choke operating lever 55 is provided and pivoted, as at 56, to the duct i3 externally thereof, the lever 55 like lever 35a having an arcuate slot 51 to receive the bearing member or pin 31a of the connecting link 38a. The choke lever 55 may be operated by the usual choke Wire 58 and this lever is adapted to change the distance of lost-motion between levers 35a and 40 to change and determine movement of the air throttlevalve of the pump II, this pump control lever 6| being' operable, as is usual, to vary the pump pressure or rate of fuel delivery.

In Figs. 4 and 5 the movable operating parts of the carburetor are shown in the positions they will assume when an engine is at rest or idle,

whereas in Fig. 6, the throttle or butterfly valve 33a is slightly open and the choke wire 58 is pulled out for cold engine starting.

In Fig. '7, with the choke still pulled out for cold engine operation, the butterfly valve 33a under control of the piston 30 is moved further toward full open position, but the valve 24 is in its full open position with the result that the fuel mixture is enriched. In the present carburetor, the fuel mixture is enriched by decreasing air supply by the butterfly valve 33a. Finally in Figs. 8 and 9, the operating parts of the carburetor are shown in the positions they will assume when the choke 58 is entirely in or in the leanest mixture stage or wide open throttle position and theengine is operating at high speed, the butterfly valve 33a and the fuel valve 24 both being fully open.

When the engine is idle, or not operating, the springs 38 and 39 hold the valve 24 on its seat 23 and the air throttle or butterfly valve 33a closed. Assuming now that a cold engine is started and, as is usually the case, the operator has pulled out the choke wire 58. As illustrated in Fig. 6 the choke lever 55 has been pivoted in a clockwise direction and has pivoted the air throttle lever 35:; in a clockwise direction to slightly open the throttle lever 33a to increase air flow capacity. Also, pivoting of the choke lever 550., places it in a position in which it limits opening of the air throttle valve 33a. As va result, it will be seen that the engine could not be raced or accelerated because while additional fuel maybe added, the air throttle valve cannot be opened sufficiently to support combustion at any engine speed above the established limited speed. When an efiort is made to race the engine by operating the accelerator pedal, the excess fuel Will tend to stop the engine and the accompanying loss of engine vacuum or suction will permit the springs 338.1161 35-3 to move the valve 24 toward its seat, thus preventing complete stalling of the engine. It will be seen that pulling out of the choke wire serves as a speed governor. However, it is pointed out that engine power may be increased by pulling out the choke slightly for this moves the air throttle to decrease volume of air thus enriching the fuel mixture. Assuming that the temperature of the engine has now increased to normal operating temperature and the choke is pushed in, returning the choke lever 55 to the position shown in Fig. 5, the smaller piston 32 operating in response to engine createdsuction actuates the metering valve accordingly to admit the proper amount of fuel to the mixing chamber 25. As previously mentioned, the range of movement of the smaller piston 32 is variable andis determined by the position of the larger piston 30 which is in turn controlled by the operators accelerator. As is well known, accelerator pedals have return springs to return or move the throttle to closed position. When the throttle lever 48 is moved in the opposite direction or toward the position thereof illustrated in dot and dash lines, Fig. 8, the small piston 32 is free to move to the left, Fig. 9, in response to engine created suction and unseat or move the valve 24 further away from its port 23 to increase fuel supply to the engine. The air throttle lever 35a, being connected to the lever Allis-also actuated by the piston 32 in accordance with engine created suction. Upon stoppin of the engine, it will be seen that the springs 38 and 39 will act to move the valve 24 immediately to its seat as the vacuum is lost. I

I While I have shown and described my invention in detailit is to be understood that the same is to be limited only by the appended claims for many changes may be madewithout departing from the spirit and scope of the invention.

What I claim is:

1. In 'a carburetor for an internal combustion engine, means providing an air-fuel admixing chamber in communication with a source of suction and fed with air and fuel from supply sources thereof, means providing a cylinder in communication with said source of suction, a pair of pistons freely arranged one within the other and within said cylinder and movable in one direction under the influence of said suction and in the opposite direction in opposition to said suction, valve means carried by one of said pistons for movement therewith and operable for controlling the feeding of the fuel to said chamber, other movable valve means operable for controlling the feeding of the air to said chamber, lever means operatively connected to the other of said pistons for movement therewith, and other lever means opcratively 0on nected to said second-named valve means for movement therewith and to said first-named lever means for movement therewith.

2. In a carburetor for an internal combustion engine, means providing an air-fuel admixing chamber in communication with a source of suction andfed, with air and fuel from supply sources thereof, means providing a cylinder in communication with said source of suction, a pair of pistons freely arranged one within the other and within said cylinder and movable in one direction'under the influence of said suction, spring means operable for urging said pistons in the opposite direction in opposition to said suction, valve means carried by one of said pistons for movement therewith and operable for controlling the feeding of the fuel to saidchamber, other movable valve means operable for controlling the feeding of the air to said chamber, lever means operatively connected to the other of said pistons for movement therewith, and other lever means operatively connected to said second-named valve means for movement therewith and to said first-named lever means for movement therewith.

3. In a carburetor for an internal combustion engine, means providing an air-fuel admixing chamber in communication with a source of suc said pistons for movement therewith and operable for controlling the feeding of the fuel to said chamber, other movable valve means operable for controlling the feeding of the air to said chamber, lever means operatively connected to the other of said pistons for movement therewith, and other lever means operatively connected to said second-named valve means for movement therewith and to said first-named lever means for movement therewith.

4. In a carburetor for an internal combustion engine, means providing an air-fuel admixing chamber in communication with a source of suction and fed with air and fuel from supply sources thereof, means providing a cylinder in communication with said source of suction, a pair of hollow pistons slidably carried one within the other and within said cylinder and having their interiors in communication with each other and with said cylinder, said pistons being movable in one direction under the influence of said suction and in the opposite direction in opposition to said suction, valve means carried by one of said pistons for movement therewith and operable for controlling the feeding of the fuel to said chamber, other movable valve means operable for controlling the feeding of the air to said chamber, lever means operatively connected to the other of said pistons for movement therewith, and other lever means operatively connected to said second-named valve means for movement therewith and to said first-named lever means for movement therewith.

5. In a carburetor for an internal combustion engine, means providing an air-fuel admixing chamber in communication with a source of suction and fed with air and fuel from supply sources thereof, means providing a cylinder in communication with said source of suction, a pair of hollow pistons slidably carried one within the other and within said cylinder and having their interiors in communication with each other and with said cylinder, said pistons being movable in one direction under the influence of said suction, a pair of springs arranged one between said cylinder and one of said pistons and the other between said pistons for urging said pistons in the opposite direction in opposition to said suction, valve means carried by one of said pistons for movement therewith and operable for controlling the feeding of the fuel to said chamher, other movable valve means operable for controlling the feeding of the air to said chamber, lever means operatively connected to the other of said'pistons for movement therewith, and other lever means operatively connected to said secend-named valve means for movement therewith and to said first-named lever means for movement therewith,

6. In a carburetor for an internal combustion engine, means providing an air-fuel admixing chamber in communication with a source of suction and fed with air and fuel from supply sources thereof, means providing a cylinder in communication with said source of suction, a pair of pistons freely arranged one within the other and within said cylinder and movable in one direction under the influence of said suction and in the opposite direction in opposition to said suction, valve means carried by one of said pistons for movement therewith and operable for controlling thefeeding of the fuel to said chamber, other movable valve means operable for controlling the feeding of the air to said chamber, lever means operatively connected to the other of said pistons for movement therewith, other lever means operatively connected at one end to said second-named valve means andiintermediate its ends to said first-named lever means for movement with said second-named valve means and said first-named lever means about an axis, and means selectively operable for varying the location of said axis.

'7. In a carburetor for an internal combustion engine, means providing an air-fuel admixing chamber in communication with a source of suction and fed with air and fuel from supply sources thereof, means providing a cylinder in communication with said source of suction, a pair of pistons freely arranged one within the other and within said cylinder and movable in one direction under the influence of said suction and in the opposite direction in opposition to said suction, valve means carried by one of said pistons for movement therewith and'operable for controlling the feeding of the fuel to saidchamber, other movable valve means operable for controlling the feeding of the air to said chamber, a lever carried by said second-named valve means for movement therewith, a second lever supported at one end about an axis and carried at its opposite end by said first-named lever for movement therewith about said axis, and a third lever connected to the other of said pistons for movement therewith and to said second-named lever intermediate the ends of the latter for movement therewith.

8. In a carburetor for an internal combustion engine, means providing an air-fuel admixing chamber in communication with a source of suction and fed with air and 'fuel from supply sources thereof, means providing a cylinder in communication with said source of suction, a pair of pistons freely arranged one within the other and within said cylinder and movable in one direction under the influence of said suction and in the opposite direction in opposition to said suction, valve means carried by one of said pistons for movement therewith and operable for controlling the feeding of the fuel to said chamber, other movable valve means operable for controlling the feeding of the air to said chamber, a lever carried by said second-named valve means for movement therewith and formed with a slot, a second lever supported at one end about an axis and having a pin at its opposite end engaging said slot normally at one end of the latter to enable said second-named lever to move about said axis with said first-named lever, a third lever connected to the other of said pistons for movement therewith and to said second-named lever intermediate the ends of the latter for movement therewith, and means selectively operable for moving said first-named lever relatively to said second-named lever to space said pin and said slot end from each other.

JAY s. CULP.

Images