US2234924A - Fuel pump - Google Patents

Description

FUEL PUMP 2 Sheets-Sheet 1 Filed May 25 1938 atented Mar. 11, 1941 NITED STATES PATENT OFFICE FUEL PUMP a corporation of Ohio Application May 25, 1938, Serial No. 209,866

3 Claims.

This invention relates to pumps, particularly fuel pumps of the kind operated by or in unison with an internal combustion engine for supplying fluid fuel to the charge forming device thereof. The invention has for its principal objects to provide a strong, compact and durable oil tight pump of simple and economical construction, to facilitate assembly and disassembly of the parts, to provide separate, readily accessible manually operable-means for priming and flushing the pump, to provide for by-passing or returning the fuel to the supply passageway of the pump when the discharge pressure in the pump cylinder rises abovea predetermined limit and to utiline the pump priming means of the pump to indicate when the pump is by-passing fuel. The invention consists in the pump and in the construction, combinations and arrangements of parts hereinafter described and claimed.

in the accompanying drawings, wherein like symbols refer to like parts wherever they occur-- Fig. l is a plan View of a fuel supply .pump em- ?bodying my invention,

Fig. 2 is a vertical section along the axis of the main pump cylinder on the line 2--2 in Fig. i,

Fig. 3 is a vertical section taken through the pump along the axes of the diametrically opposed inlet and discharge passageways on the line t-t in Fig. 1,

Fig. i is a vertical section along the axis of the cylinder of the manually operable priming device for the pump; and

Fig. 5 is an enlarged detail section through the combined inlet and relief valve portion of the pump.

The .pump shown in the accompanying drawings comprises a housing I having a central horizontal bore 2 extending from the back face of said housing and terminating short of the front face thereof. Press fitted in the bore 2 of the pump housing I is a hollow cylindrical sleeve or liner 3 which is open at both ends and has a collar 4 at its outer end that abuts against the back face of said pump housing. The inner end portion 5 of the liner 3 is of smaller diameter than the bore 2 and terminates short of the inner end thereof, thereby forming an annular passageway 6 around said portion of said sleeve and a space I opposite the inner end thereof that establishes communication betweensaid annular passageway and the interior of said sleeve.

Mounted in the liner 3 for reciprocating movement between the open inner end thereof and an annular shoulder 8 therein intermediate the ends thereof is a piston 9 having a rod Ill on its shoul I der opposing end that terminates at its outer end -in an enlarged head or collar I I. Sleeved on the piston rod ill between the internal shoulder 8 of the liner 3 and a horseshoe washer 12 that straddles said rod and abuts against the head it thereof is a coil compression spring l3 whose expansive effort produces the suction stroke of the piston 9. This arrangement of parts permits the liner 3, piston 9, rod Ill, washer l2 and spring it to be inserted in and removed from the pump as a complete preassembled unit. The pressure or delivery stroke of the piston 9 is produced by a power operated tappet or edge cam 14 which engages the bottom or closed end of a tappet cup I! that is mounted for reciprocating movement in the liner 3 between the internal shoulder 8 thereof and the outer end thereof. The open end of the tappet cup i5 faces the internal shoulder t of the liner 3 with its bottom; and the bottom of said cup has a convex exterior surface it that is held in engagement with the cam or tappet it by the head ll of the spring-pressed piston rod ill.

The pump housing i has horizontally disposed, diametrically opposed inlet and outlet passageways l'i and ill therein that communicate with the annular passageway ii between the pump housing bore 2 and the reduced inner end portion t of the liner 3.. The inlet passageway l! is provided with an outwardly open pressure relief or by-pass valve l9 and an inwardly opening suction or inlet valve 20. The relief valve l9 com- .prises a cylindrical sleeve that is axially slidable in a. cage 2| having its inner end supported in the inlet passageway and its outer end supported in the enlarged or counterbored inner end portion of the axial bore of a fitting 22 that is threaded into the outer end of said passageway. The relief valve! has a beveledinner end portion that is normally held against a seat 23 provided therefor near the inner end of the inlet passageway by means of a coil spring 24 interposed between the outer end of said valve and the shoulder formed by the counterbored portion of the bore in the fitting 22, which bore constitutes a part of said passageway. The cage 2| for the of a valve guide 28, which is mounted in said relief valve between the valve seat at the outer end thereof and a snap ring as at the inner end thereof. The inlet valve guide 20 is provided with a series of longitudinal notches N that lead inwardly from the outer end thereof and permit passage of the fuel around the inlet valve 20 when the latter is lifted off its seat 26.

The outlet passageway II is provided with an outwardly opening check valve ll in the form of a ball that is yieldably held against a. seat 32 provided therefor in said outlet passageway by means of a coil spring 33 interposed between said ball and the inner end of a fitting 34 which is threaded into the outer end of said outlet passageway and constitutes a portion thereof. The outlet valve 3| is supported in a guide sleeve 35 mounted in the outlet passageway ll between the seat 32 therein and the fitting I4 and is provided with a series of circumferentially spaced alongated notches 35a which permit the fuel .to pass around said outlet valve when the latter lifts off said seat. A branch passageway 36 leads upwardly from the discharge passageway outwardly of the outlet valve 3| and has its upper end closed by a hollow fitting 31. which forms an air chamher for partially dampening the impulses from the piston.

The hereinbefore described pump is also provided with a manually operable auxiliary pumping device for priming the pump and clearing the fuel system of air. This priming device comprises a piston 38 reciprocable in the axial bore 39a of an upright extension 39 of the pump housing I. They inner end of this bore communicates through a passageway 40 with the annular assageway 8 between the inner end portion of the liner 3 and the horizontal bore 2 provided therefor in the pump housing. The inner end of the auxiliary piston 3b is provided with a gasket 38a adapted in the innermost position of the piston to seat against an annular shoulder 4| provided therefor in the .bottom of the bore 39a and thus cut off communication between said bore and the main bore 2 of the housing during normal operating pressures of the pump. The piston 38 is provided with an upwardly extending rod 42 that terminates at its upper end in a head 42a. This rod. is slidably supported in the axial bore of a sleeve 43 that extends downwardly into the bore 39 and is slidably supported in a bushing 44 mounted in the upper end of said bore between a shoulder thereof and a snap ring 45. The exposed upper end of the sleeve 43 is shaped to provide a handle or knob 46; and the upper end of the piston rod receiving bore of said sleeve is counterbored to accommodate the head 42a of the piston rod. The knob 48 has a base flange 41 that. seats against the upper end of the upright housing extension 39 in the inoperative position of the sleeve 43 and is releasably held in such position by means of a spring clip 48 that is secured to said housing extension and terminates at its upper end in a hook 4! adapted to snap over said base flange of said knob. The lower end of the sleeve 43 terminates short of the piston 38, and a. coil compression spring ill is sleeved on the piston rod 42 between the opposing ends of said sleeve and said piston.

The operation of the pump is as follows: When the tappet cup I5 is in contact with the drop of the cam l4 the suction stroke is imparted to the piston 9 by the spring 33, thereby lifting the inlet valve 29 off its seat and drawing fuel through the annular passageway 6 and space ll into the chamber or cylinder formed between the opposed inner ends of said piston and the bore 2. When the tappet cup 55 is forced inwardly by the rise of the cam M, the piston 9 is forced inwardly in the supporting sleeve 3, thereby forcing the fuel admitted through the inlet valve 20 out through the outlet valve 3| into the outlet passageway l8 and thence to the fuel injection pump or other charge forming device (not shown). When the quantity of fuel drawn into the pump is greater than that required by the charge forming device, a back pressure is created in the pump cylinder and when such back pressure is sufficient to overcome the pressure of the relief valve spring 24, said pressure lifts the relief valve 15 off its seat and causes a return flow of the fuel to the inlet side of the inlet valve 20 through the by-pass formed by the relief valve cage notches 2 la and the annular chamber 25. This by-passing of the fuel continues until the pressure in the pump returns to normal, whereupon the relief valve l9 closes and the fuel is discharged through the discharge valve 3|.

When it is desired to flush or prime the pump, the hold down clip 48 is disengaged from the base flange All of the knob 46 and the auxiliary piston 38 is manually reciprocated by means of said knob to draw fuel through the inlet valve 20 into the main pump chamber and discharge said fuel through the outlet valve 3|. In the latched position of the auxiliary piston 38, the spring-pressed gasket 3811 at the lower end thereof serves to out off communication between the auxiliary and main cylinders of the pump. In this position of the auxiliary piston 38, the gasket seating spring 50 is not fully compressed during the normal operating pressures of the pump. When, however, the pump is operating against a back pressure suficient to cause bypassing of the fuel, the impulses from the main piston serve to further compress the spring 50 and impart a rapid reciprocatory or jiggling movement to the auxiliary piston and to the exposed head 42a of the rod 62 thereof, which movement of said head indicates to the operator that the pump is by-passing fuel.

While I have described my pump in connection with a supply pump for a fuel injection systern of an internal combustion engine, it is obviously adapted for other uses.

What I claim is:

1. A pump comprising a housing having a.

cylinder, inlet and outlet passageways communicating with said cylinder, a. piston in said cylinder, an inlet valve in said inlet passageway, means adapted upon a predetermined pressure in said cylinder to' permit fluid, after passing through the inlet valve to be returned by-passed to said inlet passageway on the inlet side of the last mentioned valve, said housin having a second cylinder communicating with said end of said first mentioned cylinder, a priming piston reciprocable in said second cylinder, and means located exteriorly of said housing for manually reciprocating said priming piston, said priming piston being reciprocable by the impulses from said first mentioned piston during such predetermined pressure to therebycontlnuously reciprocate said manually operable means and thus indicate that the pump is by-passing fluid.

2. A pump comprising a housing having a cylinder and inlet and outlet passageways comrained in'cating with said cylinder, a piston in said cylinder an inlet valve in said inlet passage- Way, means operable by a predetermined pressure in said cylinder to permit fluid admitted lav said inlet valve to be Icy-passed to said inlet passageway at a point therein in advance oi. said inlet valve, said housing having a second cylinder therein opening into said end of said first mentioned cylinder, a priming piston re ciprocahle in. said second cylinder and means located erteriorly of said housing for manually operating said priming piston, said priming piston being" adapted to he continuously recipro cated by the impulses from said first mentioned piston only during such lay-pass pressure, thereby imparting a continuous reciprocating movement to the enteriorly located operating means for said priming piston, whereby such continuous movement of said means indicates such bypassing of the fluid. v

d. d pump comprising a housing having a cylinder and inlet and outlet passageways communioating with said cylinder, 2. piston in said cylinder, an inlet valve in said inlet passageway, means for Icy-passing fluid around said inlet valve from. the discharge side thereoi! to the inlet side thereof upon a predeteed pres sure in said cylinder, said housing having a second cylinder therein opening into said end oi said first mentioned cylinder, a priming piston reciprocable in said second cylinder, a sleeve reciprocable in said second cylinder and having an operating hnoh located cirterlorly thereof, means for locking said sleeve in its ermost position, a rod fixed to said prg piston and extending through said sleeve and terminating at its outer end in a head seated in a recess pro vided therefor in said knob, and a spring sleeved on said rod hetween said sleeve and said prinr ing piston and adapted in the locked innermost position of said sleeve to hold said priming pis ton in its innermost position except under by passing pressure during which the impulses from said first mentioned piston will continuously reciprocate said priming piston against the press sure of said spring and thus impart a similar movement to said rod and the exposed head thereof to thereby indicate lay-passing of the fluid.

WALTER F. GREEN".

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