US2101221A - Liquid fuel pump - Google Patents

Description

Dec. 7, 1937. R. LORANGE LIQUID FUEL 'PUMP Filed April 20, 1935 Inventor Ji 0 Patented Dec. 7, 1937 UNITED STATES- LIQUID FUEL PUMP Rudolf LOrange, Stuttgart, Germany, assignmof one-half to Frederick Richard Simms, London, England Application April 20, 1933, Serial No. 667,125 In Germany December 5, 1932 2 Claims.

This invention is for improvements in liquid fuel pumps of the reciprocating piston or plunger type in which a variable portion of the fuel in the pump cylinder is arranged to be discharged or by-passed from the cylinder under the control of the plunger through an outlet distinct from the normal delivery outlet, the fuel so by-passed being termed the spill and the variationinwhich is governed by rotation of the plunger in its cylinder so as to bring difierent portions of an inclined or oblique control edge for the spill? into the operative position. The invention relates more particularly to pumps of this type employed as injection pumps for compression ignition internal combustion engines.

- at all times a. maximum area forthe discharge It is the principal object of the invention to provide a fuel injection pump of an extremely simple construction in which not only is all interference avoided between 'the incoming' fuel in the suction passages of the pump leading to the cylinder space and the fuel discharges in the form of spill, by completely separating the suction and spill passages, but also wherein unbalanced eddy formations and partial vacuum effects in the working space of the pump cylinder are avoided.

A further object of the invention is to ensure passed fuel is employed to assist the discharge action and avoid unregulated swirling, frothing and heating of the spilled fuel.

A still further object is to provide a construction of pump in which the cylinder space can be automatically flushed through with fuel during that portion of each cycle of operations of the pump in which fuel is not being delivered by the pump; in this way the cylinder space is maintained full of fuel in a very reliable manner and is free from bubbles even when the pump opcrates at very high speeds.

It is to be observed that the avoidance of eddy eifects in the cylinder space and passages-of a fuel pump are of the greatest importance in con nection with modern compression ignition engines due to the fact that such engines operate at relatively high speeds particularly in the case of transport engines and the fuel pressures employed: amount to anything from 1500 to 5000 pounds per square inch involving enormous speeds of travel of the fuel in the pump passages and cylinder so that even small eddy eifects which would not be of material importance when op-' erating at relatively low speeds, assume a magnitude which can easily mar the action of the pump to a very serious, extent. Thus the construction of pumps forming the object of the present invention as specified in the appended claims is of the utmost importance as regards the avoidance or material reduction of the eddy efiects referred to. v

In order that the invention may be fully understood, reference is directed to the accompanying drawing, in which:

Figure 1 illustrates a fuel pump constructed in accordance with the invention;

Figure 2 illustrates a vertical section of the upper portionof a modified form ofv fuel pump constructed in accordance with the invention;

Figure 3 is a section on the line 3-3 of Figure 2, and

Figures 4, 5, 6 and 7 are diagrams illustrating methods of controlling the spill of pumps constructed in accordance with the invention in a manner hereinafter described.

Referring to Figure 1, a pump is illustrated which comprises a body member I within which a cylindrical sleeve or liner 2 is located and is locked in position by a cylinder head 3 which is screwed into the said body and within which a compression space .4 is provided. A reciprocatable plunger is slidably mounted within the cylindrical bore 6 of the liner 2 and is arranged to be moved in an upward direction for the delivery stroke by a rotatable cam 1 arranged to bear against a roller 8 mounted upon a cylindrical slide 9 to which the lower end of the plunger 5 is secured and which slides in a guideway formed in the body i; the downward or suction stroke of the plunger 5 is effected by a spring i0 and the plunger 5 is shown in its lower dead centre position in the drawing. The cam I is of The fuel inlet opening ii in the body I leads to an annular passage is formed between the said body and the liner 2 and radial passages It in the liner establish communication between the passage l3 and an annular recessi formed in the bore of the liner around the plunger 5. Passages lfi formed in the plunger 5 establish a permanent communication between the recess l5 and a bore ill formed axially of the plunger and which constitutes the suction passage to the compression space 3. The upper end of the bore ii is closed by a valve E8, the enlarged upper portion of which is arranged to slide within the compression space 41 and the valve is normally maintained upon its seating by a compression spring W-which reacts against the end wall of the compression chamber. Passages 88!: are provided in the bottom of the enlargement of the valve W to enable the fuel to flow from the bore E? into the space d upon the upper side of the enlargement. A fuel discharge opening 26 in the head 3 is normally closed by a spring controlled delivery valve 2! past which fuel is arranged to be discharged through an-outlet pipe 22.

The upper end of the liner 2 is provided with a recess or pocket 23, the lower edge 25 of which, constitutingthe control edge for the spill is inclined relatively to a plane extending transversely to the longitudinal axis of the liner. A groove 25 is formed in the periphery of the plunger 5 in the axial direction thereof, the lower end of which is in permanent communication with the recess l5 and the upper end of which is arranged to overlap the control edge 25 at a point .spill is discharged through the recess 23 and groove 25.

It will be appreciated that the suction passage l! in the plunger 5 is completely separate from the passages 23, 25 arranged exteriorly of the plunger and through which the spill is discharged, thus entirely avoiding interference between the spill and the fuel in the said suction passage.

Referring to Figures 2 and 3, the same reference numerals have been employed where possible for similar parts of the pump as those employed in connection with Figure 1. In this construction the plunger 5 is operated in a similar manner to that described with reference to Figure 1. The fuel enters the pump through a pipe 82 leading to an annular passage is formed between the body member I and the liner 2 in which the bore for the plunger 5 is formed. Passages Id place the passage is in communication with an annular recess is formed in the liner around the plunger and radial passages I 5 in the plunger establish communication between the recess l5 and the suction passage ll! formed axially of the plunger 5. The upper end of the passage ll is arranged to be closed by a suction valve l8, an upward enlarged extension of which is arranged to slide in the compression chamber i. The downward movement of the valve 18 under the inrluence of its spring ill is limited by a stop 26 carried by the liner 2 so.that during the movement of the plunger through the lower portion of the suction stroke and the commencement of the delivery stroke, 'the said valve is maintained 23 in the bore of the liner 2 is arranged to cooperate with the upper end of a groove 25a formed helically around the plunger 5 for the purpose of controlling the spill of the pump. The lower end of the groove 25a is in permanent communication with an annular groove 2! formed in the liner 2 around the plunger and passages 28 arranged tangentially with respect to the said annular groove (Figure 3) establish communication between the said groove and an annular passage 29 formed in the body member I. A passageway 3|! arranged tangentially with respect to the passage 29 establishes communica tion between the latter and an outlet pipe 3| arranged to discharge the spill into the fuel tank or other receiver.

In order that the operation of the pump illustrated in Figure 2 may be readily appreciated, reference is directed to Figure 5 in which the curve indicates the plunger movement effected under the control of the cam I; one complete cycle of operation from an initial position at bottom dead centre is indicated by the portion of the curve marked I30I3ila. Assuming the fuel is delivered to the pipe i2 under pressure it flows through the passages 13, iii, l5, l6 and i i into the compression space 6 during the upward move ment of the plunger until the upper end of the plunger is closed by the suction valve l8 at the point indicated at E3! in Figure 5, thereafter fuel is delivered past the valve 2i through the delivery pipe 22 until the upper end of the groove 25a meets the control edge 2d at a point, for example, which is indicated at I32 in Figure 5. Thereafter fuel is discharged into the recess 23 and passages 25a, 27, 28, 29 and 30 to the spill outlet 3! during the whole of the remainder of the upward stroke of the plunger. plunger reaches the top dead centre at the point indicated at K33 in Figure 5, the valve it opens under the pressure of the fuel supply and fuel flows through the suction passages past the said valve, through the compression space 6 and thence through the recess 23, passage 25a and so on out of the outlet 3| until the end of the groove 25a passes the control edge 26 at the point indicated at 835 in Figure 5 when the suction stroke proper commences and continues to the point 83011. Figure 4 shows the various positions of the end of the groove 25a in relation to the control edge 2d at the points corresponding to those indicated in Figure 5; thus bottom *dead centre corresponding to points I30 and i30a is indicated at I20, the point 63! is indicated at I25, the point i32-is indicated at I22 and the top dead centre I33 is indicated at 523.

The cylinder space above the plunger is thus flushed with fuel during more than half the period of each cycle of operation of the pump and the presence of bubbles in the cylinder is avoided. The valve i8 is maintained open during the downward stroke of the plunger due to the force of the opposing column of incoming oil and the inertia of the valve.

The discharge of the spill through the helical groove 25a causes the discharged fuel to circulate rapidly in the annular passage 21 so that it is discharged by centrifugal action through the tangentially arranged passages 28 into the annular passage 29 in which it again swirls and is"discharged through the passage 30 to the outlet pipe 3! the rapidity with which the cycles of operation of the pump follow one another maintains a constant swirling motion of the discharged fuel in the passages 21 and 29. The discharge of the As soon as the sufficient to convey the discharged fuel to the tank, especially where a number of pumps are embodied in one unit with a discharge opening common to all the pumps.

As shown in Figure 6, the edge of the helical groove 25a may be semi-circular, the groove being directed at right angles to thecontrol edge 24. Itis preferable, however, that the end of the groove should be straight and parallel to the control edge as shown in Figure 4.

A particularly large passage area is afiorded by the arrangement of the helical groove as shown in Figure 7, wherein the side of the groove is dis posed parallel to the control edge and the end of the groove'is curved so as to deflect the fuel easily into the groove.

In Figures 6 and 7, the various positions of the groove 25a for the different positions of the plunger have been indicated by the same reference numerals as in Figure 4.

It is to be understood that in any of the above described constructions the recess 23 having the control edge 24 may be provided upon the plunger and the groove 25 or 25a formed in the wall of the cylinder bore', the recess then being inverted and arranged to co-operate with the lower end of the groove in the cylinder wall.

It will be obvious that where necessary in order to obtain a more rapid discharge of the spill two or more recesses with inclined control edges and a corresponding number of grooves in the plunger may be provided evenly spaced around the periphery of the cylinder wall and the plunger.

If only one groove for the discharge of the spill" is provided in the plunger, an additional recess or pocket may be'provided in the cylinder wall opposite to that which co-operates with the said groove and in this case the said pocket need not have the inclined control edge although if such an edge is provided it enables the same to spill passages formed distinct from one another,-

the suction passage being disposed interiorly of said plunger and communicating with the exterior of said plunger through at least one lateral suction passage therein, means for closing said suction passage during-a portion of the stroke of said plunger, said spill passage being disposed wholly exteriorly of said plunger and being constituted by one part formed in the outer surface of said plunger and another part formed in the wall of said cylinder, one of said parts of said spill passage comprising a groove extending down to a discharge chamber for the spill fuel in.

said plunger and communicating to supply fuel to said suction passage formed interiorly of said plunger through said lateral suction passage therein, said discharge chamberfor the spill fuel being arranged in said cylinder wall above said inlet chamber for the fuel supply so as to maintain the spill fuel entirely separate from the suction fuel and so that any spill fuel leaking tion stroke,.the combination comprising a main pump body,--a cylinder disposed-within said pump body, a plunger reciprocable in said cylinder, suction and spill passages formed distinct from one another, the suction passage being disposed interiorly of said plunger and communicating with the exterior of said plunger through at least one lateral suction passage therein, means for closing said suction passage during a portion of the stroke of said plunger, saids'pill passage being disposed wholly exteriorly of said plunger and being constituted by one part formed in the outer surface of said plunger and another part formed in the wall of said cylinder, one of said parts of said spill passage comprising a groove extending down to an inner annular discharge chamber for the spill fuel in said cylinder wall, said groove having a closed end cooperating with said another part of the spill passage to control the spill, said another part ofthe spill passage being in constant communication with the pump chamher, an inner annular discharge chamber for the spill fuel in said cylinder wall into which said spill groove is arranged to discharge the spill fuel, an inner annular inlet chamber for the fuel supply also in said cylinder wall and communicating v to supply fuel to said suction passage formed interiorly of said plunger through said lateral suc tion passage therein, said inner annular discharge chamber for the spill fuel being arranged in saidcylinder wall above said inner annular inlet chamber for the fuel supply, and two outer annular chambers, at least a part of each of which is formed in said main pump body, said two outer annular chambers being superposed one.

above the other so as to be completely separate from one another and communicating the one through a suction passage with said inner annular inlet chamber for the fuel supply and the other through a discharge passage with said inner annular discharge chamber for the spill fuel, the sealing between the main pump body and the cylinder for the upper edge of the top quter annular spill discharge chamber being effected by the direct seating of an enlarged portion of the cylinder on a shoulder of the main pump body,

the sealing between the two outer annular chambers being effected by a close circumferential fit of the cylinder in the main pump body and the sealing-of the lower edge of the lower outer annular inlet chamber for the supply fuel being effected by means of a packing material compressed between a shoulder on the cylinder and the main pump body.

' RUDOLF I.{QRANGE.

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