US2299872A - Carburetor pickup system - Google Patents

Description

'- Oct.r27, 1942. I i "r. MQBALL I 2,299,872

' CARBURETOR'PICK-UP' SYSTEM Filed June 4, 1940 ATTORNEYS.

Patented Oct. 27, 1942 CARBURETOR PICKUP SYSTEM Thomas M. Ball, Detroit, Mich., assignor to Ball 8; Ball Carburetor Company, Detroit, Mich, a

partnership Application June 4, 1940, SerialNo. 338,772

2 Claims. (Cl. 26134) This invention relates to improved carburetor pick-up pump mechanism.

More particularly, the invention pertains to improvements in the action of the mechanism for operating the piston of the pick-up system of a carburetor by which the supply of liquid fuel to the fuel mixture passage thereof is temporarily augmented during Opening movements of the carburetor throttle.

One of the main objects of the invention is the provision of improved means for so operating the pick-up system of the carburetor of a vehicle engine as to guard against overloading the engine during opening of the carburetor throttle when an increase in the liquid fuel supply is required to meet the load conditions in order to attain smooth engine operation without extreme precision of accelerator pedal control. v

' A further object of the invention is to provide a pick-up system of thiskindwhich has a delayed, limiting fuel displacing action during slight throttle opening movements uch as occur when the accelerator of a vehicle ngine control is vibrated by movement of an operators footas the vehicle is driven over rough roads.

Another object of the invention is to provide actuating mechanism for th fuel displacing element of a system of this kind which causesfuel to be discharged at relatively high pressure when the carburetor is initially opened beyond a predetermined position at a rapid rate and which produces a. low pressure fuel discharge during gradual throttle opening movements at substantially any position of the throttle.

A still further object of th invention is the provision of fuel displacing element operating mechanism which prevents overloading of the carburetor when the throttle is slightly opened from a fully closed position to produce slight acceleration of a vehicle from an intermediate coasting speed.

An additional object of the invention. is the provision in such piston operating mechanism of the combination of a relatively strong spring and a series related comparatively'weak spring. either of which may be caused to predominate in exerting the fuel displacing pressure on the piston.

Other objects and advantages of the invention will be more apparent from'the following description taken in connection with the accompanying drawing, in which: 1

Fig. 1 is a side elevational view of a carburetor showing in section a portion of the pick-up system embodying the invention. l t

Fig. 2 is mainly a sectional view taken centrally ofthe fuel mixture passage of the car-' buretor showing the communicating discharge passages of the pick-up system. i

Fig. 3 is a fragmentary sectional view taken on the line 3-3 of Fig. 1. 1

The invention is illustrated in the drawing as applied to a carburetor having a body portion. ID in which is provided a fuel mixture passage II; To the lower end of the body portion It isattached a throttle body l2 having a throttle blade i3 disposed therein and attached to a throttle shaft 14 which is journalled in apertures formed in the walls of the throttle body 22. Fixed to one end of the throttle shaft 54 is a bellcrank lever I5. A spring 16 has one end attached at ilto one'arm of the bellcrank i5 and its opposite end anchored at l8 as illustrated in Fig. 1. The other end of the throttle shaft M is provided with con trol mechanism, generally designated by th nu- ,meral 19, which is connected to the accelerator or other manual control (not shown) by which the throttle is selectively opened and closed to regulate the speed of the engine which is provided with fuel by the carburetor.

Formed in the body portion Id of the carburetor is a cylinder 2!] having an inlet opening 2 l, as shown in Figs. 1 and 2, at its lower extremity which is .cornmunicatively connected with the reservoir 22 of the carburetor by a passage 23. A check valve 24 in the inlet of the cylinder serves to close the inlet opening during the displacement of fuel from the cylinder. The cylinder 28 is also provided with an outlet orifice 25 which communicates with an upwardly extending fuel duct 26 leading to a discharge nozzle, generally designated bythe numeral 2! in Fig. by which fuelfrom the cylinder 2B is injected into the fuel mixture passage 1 I through a port 23 in the wall structure of the fuel mixture passage.

Reciprocably. mounted in the cylinder 20 is a piston 29 having a central passage 3!] in which is axially shiftably mounted. a piston rod 3!.

, Formed in the lower end portion of the piston rod 3| isa slot 32 through which extends: a pin 33 carried by the piston 29. The piston and piston rod are free to move axially relative to each other by an amount predetermined by the ends of the slot 32. A spring seat 3 is rigidly connected tothe piston rod 3! at a location slightly above the upper extremity of the slot 32. The seat serves as an abutment against which an actuating spring 35 bears. The upper end of the actuating spring 35 is seated against a shoulder 36 formed around the wall of the upper extremity of the cylinder 20. A second spring 31 which is relatively weak as compared to the actuating spring 35 bears between the upper extremity of the piston 29 and the lower surface of the spring seat 34 carried by the piston rod. The spring 31 normally tends to urge the piston and piston rod to their outer limiting positions but the strength of the spring is preferably predetermined as to accommodate its compression under the action of the actuating spring 35 in order to allow limited relative movement between the piston 29 and piston rod 3| until the upper extremity of the slot 32 engages pin 33.

The upper end portion of the piston rod 3| is operatively connected with the bellcrank I of the throttle control mechanism by an L-shaped lever 33 having a vertical arm 39 reciprocably mounted in a passage 40 of the carburetor body and connected at its lower end by a link 4| to the arm of the bellcrank opposite that to which the spring I6 is attached. The L-shaped bar 38 has a horizontal arm 42 provided with an aperture 43 in which the piston rod 3| is slidably received. A head 44 on the outer end of the piston rod abuts the upper surface of the horizontal arm 42 limiting upward'movement of the bar 38 relative to the piston rod but accommodating downward movement thereof.

In the operation of the foregoing carburetor pick-upsystem, the piston is retracted from the discharge end of its stroke by the bar 38 during throttle valve closing movements produced by the spring I6 or any other means by which the throttle is urged to a closed position. Closing movement of the throttle is accompanied by upward movement of the bar 33 which urges the piston rod 3| upwardly, thereby compressing the actuating spring 35. When the throttle valve is in its fully closed or idling position, the relatively weak spring 31 serves to hold the piston 29 at the outer end of its path of movement relative to the piston rod. As the throttle valve is opened, the bar 38 is moved downwardly so as to accommodate downward movement of the piston rod 3| under the action of the spring 35. Initial downward movement of the piston rod 3| causes the piston 29 to be yieldably urged in the direction of its fuel displacing movement by the relatively weak spring 31 until the upper extremity of the slot 32 engages the pin 33. Further downward movement of the piston rod 3| thereafter results in a positive actuation of the piston 23 in its fuel displacing stroke. If the throttle valve is opened only a slight amount, the spring 31 is compressed and thereafter expands producing a delayed fuel displacing action of the piston 29. The rate at which fuel is displaced by expansion of the relatively weak spring 31 is insufficient to overload the carburetor with fuel and thus the roughness of engine operation accompanying an overloaded condition does not occur. The same action takes place during gradual throttle opening movements of an amplitude greater than that corresponding to the length of the slot 32, for, as the throttle is gradually opened, the piston rod 3| is slowly moved downwardly while the spring 37 keeps the piston in advance of the upper extremity of its range of movement relative to the piston rod. When the throttle is suddenly opened an amount greater than that corresponding to the length of the slot 32, the upper extremity of the latter slot promptly contacts the pin 33 and the piston 29 is positively urged downwardly by the piston rod to produce that prompt discharge of fuel under relatively high pressure which is required during rapid acceleration of a vehicle.

The delayed action of the piston 29 in response to slight or low rate throttle movements prevents the discharge of repeated surges of fuel from the cylinder 20 when the accelerator of the vehicle is vibrated in that manner which frequently occurs as a result of movement of an operators foot as the vehicle is driven over rough roads. The lost motion connection provided by the slot 32 and pin 33 accommodates such movement of the piston rod 3| as results from this fluttering action of the accelerator pedal without discharging an excessive amount of fuel from the cylinder 20 and as a result, smooth engine operation is attainable in the absence of extreme precision control of the accelerator. When the throttle of the carburetor is slightly opened from an intermediate position while the vehicle is coasting, the relatively weak spring 3'! yields to accommodate relative movement between the piston rod 3| and the piston 29 and the spring thereafter expands, discharging that amount of fuel corresponding to the slight opening of the throttle at a relatively slow rate so that the fuel added to the mixture chamber of the carburetor is distributed over a period of time sun-lcient to guard against overloading of the carburetor.

Although but one 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 the invention.

I claim:

1. In a carburetor including a fuel mixture passage having a throttle valve therein and manually operable means for controlling the latter; a pick-up system comprising a liquid fuel chamber, a fuel displacing piston member in said chamber, mechanism operatively connected with said throttle control means for retracting said fuel displacing piston member after a discharge stroke thereof during closing of said throttle including an operating bar and a piston rod having a lost motion connection at one end with said fuel displacing piston member and a lost motion connection at its opposite end with said operating bar, a resilient member bearing between said fuel displacing piston member and an abutment fixed on said piston rod on opposite sides of said lost motion connection, and an actuating resilient member energizable during throttle closing movements bearing upon said abutment in a direction opposite to the action thereon of said first-mentioned resilient member and on the side of said lost motion connection opposite from said fuel displacing piston member for urging the latter through its fuel displacing stroke during throttle opening movements, said first mentioned resilient element being yieldable under the action of said actuating resilient element to accommodate initial relative movement of said fuel displacing member and said mechanism and subsequent unitary movement thereof during throttle opening movements.

2. In a carburetor including a fuel mixture passage having a throttle valve therein and manually operable means for controlling the latter; a pick-up system including a cylinder having an outlet communicating with said fuel mixture passage, a piston in said cylinder, a piston rod, means axially slidably connecting said piston and piston rod for relative movement between two predetermined limiting positions and including throttle opening movements, and a spring bearing between said piston rod and piston, said latter spring being so constructed and arranged as to yield and accommodate relative movement of said piston and piston rod in order to limit fuel discharge from said cylinder under slight and low rate throttle opening movements and being adapted to compress and establish a positive movement transmitting action from said piston rod to said piston under wide open and higher rate throttle movements.

THOMAS M. BALL.

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