US2079821A - Fuel injection pump - Google Patents

Description

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y 1937- w. SCRIBNER FUEL INJECTION PUMP Filed March 21, 1935 Patented May 11, 1937 FUEL INJECTION PUMP William L. Scribner, Canton, Ohio, assignor to The Timken Roller Bearing Company, Canton, Ohio, a corporation of Ohio Application March 21, 1935, Serial No. 12,160

5 Claims.

This invention relates to fuel injection pumps of the kind having a reciprocating piston of constant stroke that is angularly adjustable in its cylinder to regulate the quantity of fuel delivered. The invention has for its principal objects to provide a simple, economical, eflicient and compact arrangement for turning the reciprocating piston, to facilitate assembly of the parts and to obtain other advantages hereinafter appearing. The invention consists in the piston turning arrangement and in the construction, combinations and arrangements of parts hereinafter described and. claimed.

In the accompanying drawing, which formspart of this specification, and wherein like symbols refer to like parts wherever they occur,

Fig. 1 is a vertical central section through a fuel injection pump provided with a piston turning mechanism embodying my invention,

Fig. 2 is a horizontal section on the line 2--2 in Fig. 1,

Fig. 3 is a horizontal section on the line 3-3 in Fig. 1,

Fig. 4 is a view similar to Fig. 2, showing a modified construction,

Fig. 5 is a view similar to Fig. 1 illustrating a modified form of the invention; and

Fig. 6 is a horizontal section on thev line 6-6 in Fig. 5.

Referring to the accompanying drawing, my invention is shown in connection with a fuel injection pump for internal combustion engines of the Diesel type. Said pump comprises a housing I having an enlarged bottom chamber 2 enclosing a horizontal shaft 3 provided with a cam or tappet 4 for actuating a piston 5 that reciprocates in a cylinder 6 mounted in a vertical bore 1 in' said housing. The vertical bore 1 in the housing I has an enlarged lower end portion 1a adapted to slidably receive a tappet ,cup 8, which bears against the lower end of the piston 5 and is engaged on its underside by the cam or tappet 4 on the cam shaft 3.

The cylinder has an enlarged collar 611 that is held down on an annular seat in the bore 1 by means of a cylindrical shell 9 threaded into the upper end of said bore. A spring-loaded fuel discharge or outlet valve I is mounted on the upper end of the cylinder 6; and a fuel delivery pipe or line H is secured to the upper end of the shell 9 by meansof a cap nut l2 threaded thereon; Inlet and overflow passageways! and I4, respectively, are located in the housing I on oppo site sides of the cylinder 6. The inlet passageway I3 is supplied with liquid fuel by means of the usual feed pump (not shown) and communicates with an inlet port Kid in the wall of said cylinder; and the overflow or by-pass passageway l l communicates with an overflow port I la in said cylinder opposite said inlet port.

The piston is provided with an annular recess l6 having an inclined or helical wall ll communicating with a peripheral recess I8, whereby the effective delivery stroke of the piston may be regulated by turning said piston in its cylinder 6 to vary the point in the delivery stroke of the piston at which the overflow port Ma is placed in communication with the pressure space above said piston through the recesses l6 and I8. With this arrangement, delivery of the fuel begins as soon as the piston on its way up covers the ports I31: and Ma and ends as soon as the slanting wall I! of the annular groove 16 in said piston opens the overflow or by-pass port 14a and relieves the pressure in the space above said piston.

The mechanism for rotating the reciprocating piston, to vary the point at which the sloping edge I! of the groove l6 in the piston opens the overflow port I la, comprises a sleeve I9 rotatably mounted on the lower end of the cylinder 6 and provided at its upper end with a gear 20 that intermeshes with the teeth of a rack bar 2| mounted in a horizontal slideway in the pump housing I. The sleeve I9 is provided with a depending skirt portion 22 that extends below the lower end of the cylinder 6 and terminates in an angular end portion or plate 23 which is notched or bifurcated, as at 24, to straddle the piston 5. As shown in the drawing, the portion of the piston that works in the notch 24 of the sleeve 20 has flattened sides 25 that slidably engage the straight sides of said notch and thus insure rotation of the piston when the sleeve is rotated. In

.the modified construction shown in Fig. 4, a spring steel clip 26 is snapped over the flatsided portion of the piston and fits in the notch in the lower end of the piston turning sleeve. This spring steel clip provides increased wearing surfaces and' insures rotation of the piston.

The flat sides 25 of the piston 5 terminate short of the lower end thereof, leaving shoulders 2'! at the lower ends of said sides; and a C washer 28 is placed astraddle the flat portion of said piston and rests upon the shoulders 21. An annular keeper or washer 29 loosely surrounds the piston and has an axially ofiset or dished portion forming a circular recess 30 adapted to keeper to hold the c-shaped washer 28 in place. The washer 29 also serves as a seat or holder for a helical piston retracting spring 3| which surrounds the piston between said washer and the notched ,lower end of the piston rotating sleeve 20. A washer 32 has a pressflt in the upper end of the enlarged lower end portion la of the vertical bore 1; and the sleeve l9 projects through said opening and has an enlarged upper end portion that rests upon said washer.

The above described construction provides a simple, inexpensive and effective drive for rotating the piston, and the parts are adapted for ready assembly and disassembly. The sleeve, piston, spring and spring holder all rotate as a unit without slippage and thus prevent wear resulting from friction and twisting of the spring.

In the modified construction shown in Figs. 5 and 6, the sleeve supporting washer 32a is held against the shoulder provided therefor in the enlarged tappet cup receiving portion Ia. of the vertical bore I by means of a piston retracting spring 3ia, which surrounds the piston rotating sleeve with its upper end bearing against the underside of said washer.

What I claim is:

1. A fuel injection pump comprising a housing, a cylinder therein, a piston reciprocable in said cylinder and having a fiat-sided portion projecting therebelow, and a sleeve rotatably mounted in said housing concentric with said cylinder and terminating therebelow in an end wall hava cylinder therein, a piston reciprocable in said cylinder and having a fiat-sided portion projecting therebelow, a sleeve rotatably mounted in said housing concentric with said cylinder and provided with a depending skirt portion terminating in a plate portion having a notch therein adapted to embrace the fiatsided portion of said piston, a spring surrounding said piston for retracting the same, a seat for the lower end of said spring, said seat comprising a dished washer sleeved on said piston, and a. C washer straddling the flat-sided portion of said piston and seating within the dished portion of said washer, the fiat sides of said piston terminating short of the lower end thereof to form shoulders for preventing endwise removal of said c washer from the lower end of said piston.

3. A fuel injection pump comprising a housing, a cylinder therein, a piston reciprocable in said cylinder and having a flatsided portion projecting therebelow, and a sleeve journaled on said cylinder and terminating therebelow free of said housing in a bottom wall having a notch therein opening laterally through the side wall of said sleeve and adapted to slidably but nonrotatabiy receive the fiatsided portion of said piston.

4. A fuel injection pump comprising a housing, a cylinder therein, a piston reciprocable in said cylinder and having a flatsided portion projecting therebelow, a sleeve rotatably mounted in said housing concentric with said cylinder and terminating therebelow in an end wall having a notch therein adapted to slidably but nonrotatably receive the fiatsided portion of said piston, said sleeve having a portion of its side wall cut away between the end wall thereof and said cylinder, and said notch opening toward the cutaway portion of said sleeve, and a U-shaped clip embracing said flatsided portion of said piston and fitting said notch.

5. A fuel injection pump comprising a housing,

a cylinder therein, a piston reciprocable in said cylinder and projecting therebelow, a sleeve rotatably mounted in said housing concentric with said cylinder and terminating therebelow in an end wall having a notch therein adapted to receive said piston, said sleeve having a portion of its inner side wall cut away between .the end wall thereof and said cylinder, and said notch opening toward the cut-away portion of said sleeve, and a U-shaped spring clip nonrotatably mounted on said piston and having flatside faces adapted to prevent rotation of said clip in said notch. WILLIAM L. SCRIBNER

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