US2079306A - Carburetor - Google Patents

Description

May 1937. E E. SKRIWAN 2,079,306

NEEDLE FOR TAKING-UP DROPPED STITCHES Filed Aug. 6, 1956 j eufr Sir/wan @7 M ma WM Patented June 22, 1937 .UNITIED STATES PATENT OFFICE Application May 31, 1932, Serial No. 614,520

8 Claims.

This invention relates to carburetors and par ticularly to improved apparatus thereof, known as pick-up mechanism, for temporarily augmenting the supply of fuel to the fuel mixture passage of a carburetor.

Fuel feeding apparatus of this character is preferably operated in timed relation with the throttle of the carburetor so as to normally increase the supply of fuel to the fuel mixture passage 1 thereof as the throttle is opened. This may be conveniently accomplished by mechanically operating the piston of the pick-up pump by the throttle control mechanism, but with conventional pumps of this character the action of the throttle valve is seriously impeded and the force required of the operator to open the throttle valve is excessively increased by the resistance of the pump. Attempts to overcome this slowing down of the throttle action by merely interposing yieldable members between the piston of the pump and the throttle control mechanism have resulted in intolerable delay in the discharging of the pick-up fuel charge. When this occurs the fuel mixture becomes too lean to produce the power required for acceleration of an engine. If

the pick-up discharge is discontinued immediately upon opening of the throttle the fuel ratio of the mixture is also reduced below that required for acceleration.

The main objects of this invention are to provide a pick-up pump in a carburetor which can be operated by the throttle control mechanism thereof without either impeding the throttle action or excessively increasing the force required 35 to operate the throttle valve; to provide a pump of this character which immediately discharges fuel during the opening of the throttle and which continues to discharge fuel for a predetermined period after the throttle is at rest in an opened 40 position; to provide a fuel displacing member in the pump cylinder which occupies less than the full cross-sectional area thereof and which is adapted to move freely through the contents of the pump cylinder; and to provide positive act- 45 ing mechanism for actuating the free moving fuel displacing member in unison with the movement of the throttle control apparatus so as to initially discharge fuel from the pump cylinder simultaneously with the opening of the throttle valve.

Other objects of the invention are to provide a close-fitting fuel displacing member in the cylinder of a pick-up pump which is movable rel- 55 ative to the freely movable fuel displacing member and relative to the positive acting mechanism thereof; and to provide a yieldable member for moving the close-fitting member through its fuel discharging stroke which is operable by the positive acting actuating mechanism to impart to the close-fitting member a delayed action that continues after the throttle is at rest in an open position.

Further objects of the invention are to provide an improved liquid fuel conveying system in a carburetor having pick-up mechanism of the above character; to provide self-acting valves in a fuel system of this kind for cutting off the return flow of fuel to the fuel reservoir of the carburetor during the discharge strokes of the pistons in the pick-up pump and which also prevent the withdrawal of fuel from the normal fuel nozzle of the carburetor during the loading strokes of the pump; to provide a metering device in the fuel system which is calibrated to predetermine the period of duration of the pick-up discharge; and to provide a return branch passage in advance of the timed metering device which communicates with the fuel reservoir and which is calibrated to return to the latter that fuel admitted through the time metering device in excess of the quantity of fuel desired in the pick-up charge.

Still further objects of the invention are to provide means in the positive acting actuating mechanism for coupling the piston rod of the pump with the throttle control mechanism in different relations so as to vary the lengths of the strokes of the fuel displacing members; and to provide means of this character which hold the piston rod substantially within the same limits of parallelism with respect to the axis of the pump cylinder throughout the entire range of movement of the throttle control mechanism regardless of the relation in which the coupling elements are united.

An illustrative embodiment of the invention is shown in the accompanying drawing, in which:

Fig. I is a vertical sectional view of a carburetor embodying our invention showing for the purpose of illustration, many of the essential parts of the structure in a common plane.

Fig. II is a side elevation of a carburetor showing a vertical section of the improved pick-up pu p- Fig. III is a transverse sectional view taken on the line III-III of Fig. II.

In the form shown, the carburetor in which our improved pick-up mechanism is illustrated is of the up-draft type. The pick-up mechanism may, however, be incorporated in a downdraft carburetor with equal facility. The updraft carburetor disclosed for the purpose of illustration includes a body portion ID in which is formed a fuel mixture passage having an air inlet I2 and an outlet l3 for delivering fuel mixture to an intake manifold of an engine (not shown). The body portion III of the carburetor is provided with a fuel reservoir |4 having an inlet l5 which is controlled by a valve 5. The valve I6 is operated by conventional float mechanism I1 which predetermines the fuel level in the reservoir.

The inlet I5 includes a coupling plug which is externally threaded in an aperture in the body portion and which is provided at its outer end with internal threads for detachably connecting a fuel supply conduit (not shown) with the reservoir. The plug has a central passage for receiving the valve l6 which is provided with a valve seat l6 for coacting with the tapered end of the valve Hi. The valve may be removed and conveniently cleaned without disassembling the carburetor by merely disconnecting the fuel supply conduit and removing the coupling plug and valve simultaneously from the body portion of the carburetor.

Formed on one side of the carburetor is a pickup pump cylinder |8 having a cylindrical bore |9 in which a piston 20 is slidably mounted. The outer periphery of the piston 20 fits tightly against the inner peripheral wall of the bore 9 of the cylinder and it is provided at its central portion with an aperture 2| through which a reciprocating piston rod 22 extends. Fixed on the lower end of the piston rod 22 and located in advance of the piston 20 is a plunger 23 including a pair of discs having peripheries which extend to within close proximity of the: peripheral wall of the cylinder, sufficient space being provided between the peripheries of the discs and the inner periphery of the cylinder to permit the passage of some of the fuel content of the cylinder from one side to the other of the plunger during movement of the plunger in the cylinder. The piston 20 is urged toward the plunger 23 and yieldably held in contact with the plunger by a coil spring 24 which surrounds the piston rod 22 and which bears at its outermost end against a metal cup 25 located within the cylinder l8 and fixed to the piston rod by pin 26.

Integrally formed on the upper end of the piston rod 22 is a U-shape coupling element 21, between the sides of which is received an arm 28 of a throttle regulating lever 29. The lever 29 is fixed on a throttle shaft 38 journaled in apertures formed in the side walls of the fuel mixture passage II and carrying the throttle valve 3|. The throttle valve 3| is located at the discharge end of the fuel mixture passage and is adapted to control the flow of fuel mixture to the engine with which the carburetor is associated. The overlapping coupling element 21 and arm 28 of the throttle control lever are each provided with a pair of apertures 32 and 33, respectively, located at different distances from the axis of the throttle shaft 30. The pairs of apertures 32 and 33 are so located with respect to each other and with respect to the axis of the throttle shaft 30 that each aperture 32 of the element 21 will register withvits corresponding aperture 33 of the arm 28 throughout the entire range of movement of the lever 29 while the piston rod 22 is within the same relation of parallelism with respect to the axis of the cylinder l8. The overlapping coupling element 21 and arm 28 are pivotally secured together by a bolt 34 which is insertable through either set of registering apertures 32 and 33. The inner end of the bolt may be threaded in an aperture formed in the inner side of the U-shape coupling element 21 or provided with a nut (not shown). By selectively placing the bolt 34 in the innermost or outermost registering apertures 32 and 33 the length of stroke of the piston rod 22 may be varied so as to predetermine the stroke of the piston and plunger with respect to a fixed movement of the throttle control lever 29. Regardless of the position of the bolt 34, the piston rod is maintained within the same relation to the axis of the cylinder. In thissmanner excessive movement or deflection of the external end of the piston rod transversely of the length of the piston is effectively guarded against.

The fuel reservoir M has a thick lower wall 35 in which is formed a plurality of passageways that provide a liquid fuel conveying system.. A substantially horizontal passageway 36 communicates with the lower extremity of the pump cylinder 8 and has a vertical branch passage 31 which leads to a substantially horizontal branch passage 38. The horizontal branch passage 38 communicates with the interior of the fuel reservoir l4 through an outlet port 39 which is controlled by a check valve 40. The check valve 40 comprises a ball which is confined in a valve casing 4| and held against downward movement by a pin 42 extending transversely across the valve casing. When the pick-up pump is discharging fuel the valve 40 is held against a seat 43 formed in the valve casing so as to prevent the return of liquid fuel to the reservoir |4 through the outlet 39 thereof. During the loading stroke of the pick-up pump, the ball valve 40 rests upon the pin 42.

The horizontal branch passageway 38 also communicates with a chamber 44 in which a removable metering plug 45 is threaded. The plug 45 has a central passage 46 leading from the interior of the'reservoir M to the horizontal branch passage 38. This plug also has radially extending apertures 41 extending from the central passage 46 to the chamber 44. A valve seat 48 is formed in the central passage 46 for receiving a ball valve 49 which prevents the return flow of fuel through the passage 46 from the liquid fuel system to the fuel reservoir during the discharge stroke of the pick-up pump. The lower end of the plug 45 is provided with a metering device 50 which controls the flow of liquid fuel from the horizontal branch passageway 38 to the chamber 44. The orifice of this metering device is calibrated to predetermine the period of duration of the pickup discharge.

In the illustration shown, the pick-up discharge is admitted to the fuel mixture passage ll of the carburetor through a fuel nozzle 5| which also delivers the normal running fuel mixture to the fuel mixture passage. The nozzle 5| is threaded in a passage 52 which communicates with the chamber 44 through a branch passage 53. Threaded in the lower end of the nozzle receiving passage 52 is a plug 54 having an orifice 55 therein for metering the fuel content of the normal running fuel mixture.

In order to predetermine the duration of the fuel discharge it is generally necessary to provide the metering device 50 with an orifice havv in combination with a timed metering orifice it is possible to obtain a pick-up discharge of a desired duration and to also independently predetermine the quantity of fuel in the pick-up discharge.

In operation, as the throttle valve Si is rotated toward an open position by clockwise rotation of the throttle control lever 29, the piston rod 22 is urged downwardly together with the plunger 23. g

The piston rod and plunger are acted upon positively by the throttle control mechanism and therefore the plunger 23 simultaneously displaces fuel from the cylinder l8 with the opening of the throttle. The loose fitting relation between the plunger 23 and the provision forthe flow of some of the fuel around the plunger permits free movement of the plunger during opening of the throttle, and for this reason manipulation of the throttle control mechanism is opposed by only a slight amount of pump resistance, thereby enabling the operator to rotate the throttle from a completely closed to a partly open or fully open position in a short interval of time with'a slight degree of physical effort.

As the piston rod and plunger are moved downwardly the spring retaining cup 25 bears upon the upper end of the spring 25, tending to cause the piston 20 to follow the plunger 23. The movement of the piston 20 is in some instances, as for example when the throttle is opened rapidly, delayed by the pressure of the fuel which flows around the periphery of the plunger and which has access to the working face of the piston 20. Under this condition the spring 24 yields and is placed under compression. As the pressure under which the fuel is placed decreases by reason of the flow of the pick-up discharge through the fuel system, the spring 25 urges the piston 20 downwardly until it again engages the plunger 23. This delayed action of the piston 20 causes the pick-up discharge to continue after the throttle has come to rest in an open position and it also enables the employment of a metering device which has for its sole purpose the predetermining of the duration of the pick-up discharge. By the employment of the positively actuated fuel displacing member and the yieldably actuated fuel displacing member, we obtain an initial displacement of fuel from the pick-up system immediately upon opening of the throttle and an uninterruptedpick-up discharge which continues after the throttle is opened.

The fuel displaced from the pick-up pump cylinder flows through the passageways 36, 31, and 38 underpressure sufficient to lift the ball valves ill and 59 to closed positions so as to prevent the return flow of fuel to the reservoir I l, through the passages 39 and 45, respectively, during the discharge stroke of the pump. The fuel displaced from the cylinder l8 passes through the orifice of the time metering device 50, through the radial apertures 41 in the plug 45 and into the chamber 46 from which it is conveyed by the branch passage 53 to the lower end of the nozzle receiving passage 52. Some of the fuel which is delivered to the chamber M is returned through the metering passage 56 to the reservoir I 4 and the remainder, the quantity of which is determined by the size of the passage 56, is delivered to the fuel mixture passage ll of the carburetor by the nozzle 5|. When the pick-up pump mechanism is at rest and during the loading strokes of the pick-up pump'the ball valve 49 closes the orifice of the metering device 50 and prevents the withdrawal of fuel from the nozzle 5| during the loading strokes of the pump.

Although but one specific embodiment of the invention is herein shown and described, it will be understood that various changes in the size, shape, and arrangement of parts may be made without departing from the spirit of our invention, and it is not our intention to limit its scope other than by the terms of the appended claims.

What we claim is:

1. In a carburetor having a fuel mixture passage, a throttle valve for controlling the flow of fuel mixture from said passage having a shaft journaled in the wall of said carburetor, a lever fixed on said shaft for regulating said throttle valve, a cylinder having an outlet communicating with said fuel mixture passage, a piston in said cylinder closely fitting the inner periphery thereof, a plunger in said cylinder shiftable relative to said piston andhaving a stem pivotally attached to said lever, said plunger being located in advance of said piston and occupying less than the full cross-sectional area of said cylinder, and a spring having one end fixed against movement relative to said stem and its other end bearing upon said piston for yieldably urging the latter toward said plunger.

2. In a carburetor including a fuel mixture passage and a fuel reservoir, pick-up mechanism including a pump cylinder, a liquid fuel conducting system including passageways communicating with said cylinder, reservoir and fuel mixture passage, a fuel displacing member in said cylinder, means including a yieldable element for urging-said member toward the outlet of said cylinder, a metering device in the passageway leading from said cylinder to the passageway leading to said fuel mixture passage for predetermining the period of duration of the pick-up discharge, a metering device in the passageway leading to the fuel mixture passage for predetermining the quantity of fuel of the pick-up discharge, and a metering passageway communicating with said reservoir and with said fuel conducting system between said metering devices for returning to said reservoir the excess fuel admitted by said first metering device.

3. In a carburetor including a fuel mixture passage and a fuel reservoir, pick-up pump mechanism including a pump cylinder and piston, a liquid fuel conveying system including a chamber and having fuel passageways leading from said chamber and communicating with said cylinder, fuel mixture passage and reservoir respectively, said reservoir having an outlet port communicating with said cylinder, a metering device in the passageway leading from said cylinder to said chamber for predetennining the period of duration of the pick-up discharge, and a metering device in the passageway leading to said fuel mixture passage for metering the quantity of fuel of said pick-up discharge, the passage leading from said chamber to said reservoir being calibrated to return to said reservoir the excess fuel admitted to said chamber through the first mentioned metering device.

4. In a carburetor including a fuel mixture passage and a fuel reservoir, pick-up pump mechanism including a pump cylinder and a piston, a fuel nozzle communicating with said fuel mixture passage having a metering device therein for controlling the normal fuel mixture, a liquid fuel conveying system including a chamber and having fuel passageways leading from said chamber to said reservoir and cylinder, said reservoir having a normal fuel outlet port communicating with said chamber and an outlet port communicating with said cylinder respectively, a valve for closing the latter port during the discharge strokes of said piston, a metering device in the passageway leading from said cylinder to said chamber adjacent the normal outlet of said reservoir for predetermining the period of duration of the pick-up discharge, and a valve for alternately closing the normal fuel outlet of said reservoir and said metering device during the pickup discharge and normal operation of said carburetor respectively, the passageway leading from said chamber to said reservoir being calibrated to return to said reservoir the fuel admitted by said pick-up discharge period predetermining device which is in excess of the quantity of fuel desired in the pick-up discharge.

5. In a carburetor, pick-up mechanism including a pump cylinder, a reciprocating piston in said cylinder, a piston rod having an external end portion projecting beyond one end of said cylinder, a pivotally mounted actuating member, overlapping elements on the externalend of said piston rod and on said actuating member respecv tively each having a pair of spaced apertures therein located at different distances from the axis of said actuating member, each aperture of one pair being registerable with a corresponding aperture of the other pair throughout the range of movement of said actuating member and while said piston rod is within substantially the same relation of parallelism with respect to the axis of said cylinder, and a pin insertable through corresponding apertures of said overlapping elements for pivotally connecting said actuating member and piston rod in diverse relations so as to predetermine the length of stroke of said piston for a fixed angular movement of said actuating member.

6. In a carburetor, pick-up mechanism including a pump cylinder, a reciprocating piston in said cylinder, a piston rod having an external end portion projecting beyond one end of said cylinder, a throttle valve in said carburetor having a rotatable shaft, a throttle and pick-up pump actuating member on said shaft, overlapping elements on the external end of said piston rod and actuating member, each having a pair of spaced apertures therein located at different distances from the axis of said actuating member, each aperture of one pair being registerable with a corresponding aperture of the other pair throughout the range of movement of said actuating member and while said piston is within substantially the same relation of parallelism with respect to the axis of said cylinder, and means receivable in said apertures for pivotally connecting said actuating member and piston rod in diverse relations so as to predetermine the length of stroke of said piston for a fixed amplitude of movement of said throttle valve.

7. In a carburetor having a fuel mixture passage, a throttle valve in said passage, apparatus for regulating said throttle valve, pick-up pump mechanism including a pump cylinder, a pair of relatively movable fuel displacing members in said cylinder, rigid actuating elements pivotally attached to said throttle valve regulating apparatus and coacting positively with one of said fuel displacing members for reciprocating the latter positively in both directions, and a yield able actuating element co-acting between said rigid actuating elements and the'other fuel displacing member.

8. In a carburetor having a fuel mixture passage, pick-up mechanism including a pump cylin-- der having an outlet communicating with said fuel mixture passage, positive acting mechanism including a plunger in said cylinder for initially discharging fuel into said fuel mixture passage, said plunger permitting some leakage of fuel thereby during its discharge stroke, a close fitting piston in said cylinder between said plunger and the extremity of said cylinder opposite from its discharge end, and a spring bearing between said piston and said positive acting mechanism for causing the latter to follow said plunger and to discharge the fuel which passes by the latter from said cylinder.

FREDERICK 0. BALL. THOMAS M. BALL.

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