US2420164A

US2420164A - Pump

Info

Publication number: US2420164A
Application number: US549877A
Authority: US
Inventors: Albert T Bremser
Original assignee: Bendix Aviation Corp
Current assignee: Bendix Aviation Corp
Priority date: 1944-08-17
Filing date: 1944-08-17
Publication date: 1947-05-06
Anticipated expiration: 1964-05-06

Description

'Patented May, 1947 I PUMP Albert T.. Bremser,A Sidney, N. Y., assignor to Bendix Aviation Corporation, New York, N. Y., a corporation of Delaware l Application Augustl'l, 1944, Serial No. 549,877 (ol. 10s-41) Claims.

This invention relates to pumping means and more particularly to apparatus adapted for pump-` ing liquids, such as liquid fuel into the cylinders of internal combustion engines.

One of the objects of Ithe present invention is to providel a novel pump for pumping liquids wherein leakage of the liquid through the clearance space between the plunger and cylinder of the pump is reduced to a minimum.

Another object o1 the invention is to provide a pump of the above character wherein the liquid which leaks along the plunger is returned directly to the supply line of the pump or other region of low pressure in a novel manner.

Still another object is to provide a high pressure fuel injection pump, or the like, which embodies novel means for preventing leakage during the pressure stroke of the plunger thereof, said means :being particularly applicable to small compact pumps.

A further object is to provide novel means of the above character whlchmay be readily incor-y porated into pumps which are currently being manufactured in large quantities.

Still another object is to provide a novelly constructed fuel pump wherein fuel is conserved and more accurate metering is assured.

The above and further objects and novel features of the invention will more fully appear from the following detailed description when the same is read in connection with the accompanying drawings. It is to be expressly understood, however, that the drawings are for the purpose of illustration only and are not intended as a definition of the limits of the invention, reference for this latter purpose being had primarily to the appended claims.

In the drawings, wherein like reference character-s refer to like partsthroughout the several views, Y i

Fig. 1 is a side elevation partly in section showing one form of fuel injection pump embodying the present invention, the section being taken substantially on line I-I of Fig. 2;

Fig. 2 is a transverse sectional view takensubstantially on line 2 2 of Fig. 1 Fig. 3 is a detail sectional view withk parts broken away and with parts shown in fu`ll, they section being taken substantially on line 3-3 of Fig. 2; and, l

AFig. 4 is a diagrammatic view showing'the .z comprises a tubular casing l5 having laterally projecting ears 6 by means of which the same may be secured to an engine cylinder or other support, not shown. Mounted in the casing E intermediate the ends thereof` is a pump cylinder l which is supported on an internal shoulder 8 within the casing. Cylinder 1 may be heldA against rotary movement in casing 5 by any suitable means well known in the art, such as by means of a screw (not shown) which threadedly engages casing 5 and projects into any axially extending groove in the outer wall of the cylinder. An inlet port Il and a by-pass port I2 are provided in the wall of cylinder 1 near the upper end thereof, as viewed in the drawings, for directing the flow of fuel to and from the cylinder in a .manner to more fully appear hereafter.

Slidably extending into cylinder 1 `from the lower end'thereof is a pump plunger or piston I3 which also functions as a slide valve for controlyling Vthe yflow of fuel through ports II and I2.

determines the effective pumping stroke of theplunger. If desired, a groove or recess I Ba may be provided in the surface of plunger Iii-opposite groove I6 in communication with passage i5 to thereby balance or partially .balance the uid pressure acting on opposite sides of the lplunger during the presssure stroke thereof.

Any suitable means maybe provided for angularly adjusting piston I3 for the purpose of changing the relation between metering groove I6` and cut-off or by-pass port I2 to thereby vary theV effective pumping stroke of the piston in a manner well understood in the art. In the illustrated embodiment, the piston adjusting or con-iv trol means comprises a sleeve I8 which loosely surroundsv the lower end of cylinder- 1 in an enlarged bore of casing 5.1 Gear teeth I9 are provided on the upper end of sleeve I8 for cooperation with a rack 20 which is slidably mounted in casing 5 for movement'transversely thereof.

The lower end of sleeve I8 'is axially slotted, as at 22, for slidably receiving the ends of la crossbar 23 which is 'rigidly secured to or integral with plunger I3. Sleevels is held against axial movement relative to cylinder 1 by an internal shoulder or flange 2| which. engagesthe lower end of said cylinder andan external shoulder 2|' which rests upon the upper' surface of an inwardly extending flange on aring 2|. Said ring is posiappreciable lateral force or pressure which would sage 35.

anni

tioned against an shoulder in casing A and is held in place by any suitable means,` such as a snap ring 25. It will b'e seentherefore, that -upon reciprocation of rack 2l, sleeve I3 will be moved angularly in a direction depending upon the direction of movement of the rackand plunger I3 will be correspondingly angularly A usted through the connection 22, 23 with sleeve Il. Angular adjustment of plunger 3 may thus/.be effected without hindering the ongi jor' pumping movement thereof.

Suitable means are also provided for reciprocating piston I3 in cylinder 1 in such a manner that the piston will not be subjected to any cause any unnecessary friction or binding. In the form shown, said piston operating means includes a tappet cup 26 which is slidably posirtioned in the lower end of casing5 for engagement with an enlarged head' portion 21 at the lower end of piston I3. Said piston may be moved upwardly by means of a rotating cam, not shown, which operatively engages, either directly or indirectly, the closed end of tappet cup 23 inJ a manner well understood in the art. I'he return or downward movement of piston I3 which constitutes the suction stroke may be effected by a coil spring 23 which is interposed between the flange or ring 24 and a slotted washer 23 which `engages the upper shoulder of head 21.

Pressure chamber I1 of the pump may be con'-v nected by any suitable means to van injection nozzle (rapt/shown) in the cylinder of an internal combustion engine. Although there are many suitable structures known to-the prior art, the

means shown in thev drawings for the above purpose comprises an adaptor element 3l which constitutes a guide and seat for a delivery valve 3i. Adaptor 30 rests upon the/upper end of cylinder 1 and is held in fluid-tight engagement therewith by a combined nipple and sleeve nut 32 which engages internal threads in the upper end of casing 5. If desired, a packing washer may be interposed between the inner end of member 432 and an external flange 33 on adaptor 30 to further insure uid tightness. lThe upper end of member 32 terminates in a threaded portion or nipple 34 having a passage 35 therein whereby a delivery conduit (not shown) leading to the fuel injection nozzle may be attached for communication with the interior of member 32.

Valve guide or adaptor has an axial passage therein through which the iiow of fuel from pressure chamber I1 into the interior of member 32 is controlled by delivery valve 3| which has a hollow stem and a tapered head portion adapted to engage a valve seat. A seat for valve 3I J 4 ably but not' necessarily The interior of casing i has' two channel-shaped grooves 42 and 43 that communicate with supply port. 4| and substantially surround cylinder 1 so as to communicate with inlet and by-pass ports III and I2, respectively.J If desired, the grooves or channels 42 and 43 may be formed in a hard .metal insert which may be cast or otherwise'suitably instance in s' groove within casing' l in a 1` manner now known tothe art.

In order that plunger I3 may reciprocate freely in cylinder 1, it is necessary to provide a working clearance around the plunger. In pumps, such as fuel injection pumpawherein very high pressures are attainedin pressure chamber`I1 during the pressure or pumping stroke or the plunger, fuel or' other liquid from said chamber enters the clearance space between the walls ofthe plunger and the cylinder. A small .amount of leakage or ilow in this manner is desirable, particularly ,in fuel injection pumps, 'to provide proper lubrication for the plunger but, in prior pumps, such leakage has been excessive and wasteful and the means provided for reducing such leakage in prior pumps have been relatively complicated and ineiilcient. Novel simplified means are accordingly provided for returning the major portion of the fuel which leaks from chamber I1 to the supply line or other region o1' low pressure free of any contamination, said means o being adapted to reduce such leakage to a mum.

In the form shown, the novel means referred to above compriseaan annular groove 44 in the surface of plunger I3 and a relatively small diagonal port or passage 4 5 in the wall of cyliny der 1, the Aouter end of said port being in communication with by-pass channel 43, which in turn communicates with supply line 40, 4I. Ihe

inner end of port 45 is located approximately 90 degrees from ports II and I2 and is adapted to communicate with leakage return groove 44 only when plunger I3 approaches or reaches the top of its pumping stroke, as illustrated in Fig. 3. The circumferential and axial location of port 45 is determined primarily by metering groove I3 in the plunger, which groove also determines the uppermost position of leakage groove 44. Ihe v upper edge 46 of groove 44 must be a suiilcient axial distance from the lower end of metering groove I6 toprevent excessive leakage of fuel from the latter into groove 44. A safe distance between these grooves diiiers in pumps of dif.. ferent size and in pumps of the same size if the clearance spaces between the walls of the plunger and cylinder differ in any appreciable degree. It

- has been found satisfactory to separate the near- Yis provided in the adaptor and the upper end of the valve stem has a close sliding ilt in thev adaptor bore. The hollow center of the valve stem is open at the top, as viewed in the drawings, and is in constant communication with the interior of member 32 while the lower end of the bore in the valve is in constant communication with the interior of adaptor 30 through a plurality of radial passages 33. Valve 3i is normally yielda-bly held in closed position by suitable resillent means, such as a coil spring 3h which is centered by tubular member 38 mounted in nipple 32 and having communication `with pas- Fuel or other` liquid to be pumped may be supplied to pressure chamber I1 from a supply line 4II (Fig. 2) which enters casing 5 through a port The liquid within supply line 40 is preferest edges of grooves I6 and 44 a distance of about Vg inch in pumps having y inch and :V4 inch diameter plungers. In larger size pumps, a distance of inch has proved satisfactory. A satisfactoryl minimum distance in any given pump 4may be readily determined by test and if other factors permit, agreater distance between grooves I4 and 45 is desirable in all cases The same considerations apply to groove lia if such a groove is used.

The inner. end of port 45 must, of course, be axially positioned for communication with groove 44 at or near the end of the pressure stroke 'of the plunger and angularly positioned so that it will be an 4appreciable distance from grooves Il and Ita at all times during the effective pumping stroke of plunger-|3 for al1 angular adjustn; ments of the plunger from full speed to idling.

under slight pressure.

Y v 2,420,1e

when the munger is in its fun 10aa position and is Just beginning its effective pumping stroke, i. e., just closing inlet port II, there should be at least a distance of approximately inch in the above-mentioned smaller size pumps between port 45 and the nearestedge of groove I6. In larger pumps this distance should be correspondingly increased.

The volume of leakage return groove 44 and, hence, the width and depth thereof are important factors in the proper-'operation of the present pump. The volume 'of the groove should be sumciently large sovthat the compression-of the fuel or other liquid which takes place therein will absorb substantially all the fuel which leaks along the wall of the cylinder during each stroke of the plunger. The pressurefin the clearance space around the plunger is thus maintained sufficiently high above groove 44 to prevent excessive leakage of fuel. At or near the end of each pressure stroke of the plunger, groove 44 communicates with port 45 and the compressed fuel within the groove expands into channel 43 and, hence, into the'supply line. In pumps with plungers having diameters of 1/2 inch to inch, a, leakage groove which is 1% inch wide and .015 to .020 inch deep has proved satisfactory. In pumps of greater size, the volume should be correspondinglyincreased. In a pump having a plunger diameter greater than 3A inch, for example, groove 44 should be about A inch wide and the same depth as recited above. If a lapped plunger is used, care should be taken not to round off the corners of the grooves in plunger |3, particularly the edges of grooves I6 and liia which are nearestgroove 44, during the lapping process.

The relationship of parts and the grooves and ports therein isV best illustrated in Fig. 4, which shows the superposed developed circumferences of the pump plunger and cylinder, the plunger being shown in full load position with respect to the cylinder andrjust `closing the intake port Il on its upward stroke, i. e., at the beginning of its effective" pumping stroke for full load operation. As will be-clear from thedescription of the operation Ywhich follows, metering groove I6 moves to the right relative to port 45 when the Vplunger is adjusted from full load position toward idling position so that said groove and port will,

never overlap during an effective pumping stroke of the plunger. This' avoidsany undue leakage r by-passing ofthe fuel from chamber directly through port 45. v A

The pressure in the clearance space around the plunger/below groove 44 is'relieved or reduced by the presence of said groove but some fuel is permitted to flow past said groove in order to provide satisfactory lubrication for the plunger. If desired, one or more grooves 41 may be provided in plunger I3 below groove 44 so that fuel leakand nipple 32.' Continued upward ,movement of the plunger forces fuel past the tapered head of valve 3| through ports 36 in the walls of the valve,

f 6 the hollow valve stem and tubular member 38, and then through passage 35 to the injection nozzle. The pressure required to pump the fuel through the\injectlon nozzle into the compression chamber of an engine cylinder must in most instances be very substantial. When the desired quantity of fuel has been injected into the engine cylinder, as determined by the angular setting of piston I3, metering groove I8 moves into overlapping relation with cut-off or by-pass port I2, thereby permitting a free discharge of fuel fromchamber I1 through passages I 4 and I5 into the supply line. This relieves the pressure in the pressure chamber I and permits spring 31 to move delivery valve 3| to closed position.

It will thus be seen that during vthe effective pumping stroke of plunger I3, i. e., that portion of the upward movement of the plunger from.4 f

the time it closes port II until helical groove I6 overlaps by-pass port I2, the fuel within pressure chamber Il is under very high pressure. Because of this pressure, there is a tendency for the fuel to leak along the clearance space between the outer surface ofthe pump plunger and the inner surface of the pump cylinder. Since the pressure within groove 44 is relatively small during the initial upward movement of the pump plunger, the high pressure fuel which leaks into itis effective to compress the fuel already within the groove at the lower pressure. As pointed out above, the volume -of groove 44 is made sumciently large so that the compression which takes place in normal operation is sufficient to make room for substantially all the fuel which leaks into groovel 44 from the compression chamber during eachstroke `of the plunger. When the plunger nears the end of its upward or pressure stroke, the pressure in' groove 44 is relieved through port 45. This cycle is repeated during each stroke of the plunger.

To vary the effective pumping stroke and,

hence, the quantity 'of fuel pumped to the engine cylinder during each strokevof plunger I3, rack 20 is moved to theright or left, as viewed in the drawings, to thereby angularly adjust sleeve I 8 and, hence, plunger I3. It will be clear that angular movement of the plunger changes the point in the upward or pressure stroke thereof at which `helical groove I6 begins to overlap bypass port I2 and accordingly varies the effective pumping stroke of the plunger. For idling, piston I3 is turned sufficiently by rack 2li to carry .readily incorporated in a pump having a single port for controlling both the -by-pass and inlet of fuel or other liquid. Various` other changes A might also betmade, particularly in the design andy arrangement of parts illustrated without de.-

partng from the spirit andscope of the invention, as will now'bereadily apparent'to those skilled in the art.- For a denition ofthe limits of the invention reference is had primarily tothe appended claims. I 4

what is claimed is: Y 1. In apparatus of the class described, means forming a pressure chamber comprising a cylinder and areciprocating plunger audios cluding a helical groove in the surface thereof for connecting said port means to said pressure chamber for\terminatins the effective pumping stroke of said plunger, an annular groove in thesurface of said plunger immediately below the lower end of said helical groove and .a -port in said cylinder adapted to communicate continuously at its outer end with a region of low pres-y ,sureoutside sai'd cylinderand to communicate at `its inner end with said annular groove only when said plunger is near the end of its pumping stroke.

2. In apparatus of the class described, means forming a pressure chamber comprisinga cylinder and a reciprocating plunger therein, said cylinder having port means inthe wall thereof communicating with a source of supply, said` plunger having means thereon including a first g'roove in 1 the surface thereof for controlling the flow to and from said pressure chamber, a second groove in the surface of said plunger spaced below the lower end of said rst groove and aport in said cylinder for connecting said second groove with a lregion of low pressure outside the cylinder only when said plunger is near the end of its pressurestroke, said port being so located that it wlllnot overlap said first groove during the effective pumping stroke of said plunger. v

3. In a pump. means forming a pressure chamber including a cylinder having aninlet port and a by-pass port therein, and a piston reciprocable -in said cylinder for controlling flow through said inlet port and having passage neans for connecting said pressure chamber and said by-pass port at a predetermined point in the pressure stroke of the piston, a groove in said piston having communication with said pressure chamber only through the clearance space around said piston during at least the major portion of the effective pumping stroke of the latter and a port in said cylinder forconnecting said groove to a region of low pressure when said piston approaches the end of the pressure stroke thereof.

4. In a pump, means forming a pressure chamber including a .cylinder having port means therein and a piston reciprocable in said .cylinder for vcontrolling flow to and from said cylinder through said port means, a groove in said piston adapted to communicate with said pressure chamber only. through the clearance space around said piston during at least thel major portion of the effective pumping stroke of the latter, and a port in said cylinder for connecting said groove to a region of low pressure outside the cylinder when said piston approaches the end of the pressure stroke thereof, the inner end of said port being below d port means.

- 5. In a piston and cylinder pump of the type wherein the cylinder has inlet and by-pass port means controlled by said piston for determining the effective pumping stroke of the latter, an annular groove in the surface of said plunger, and

a port in said cylinder for connecting said groove to a region of low pressure outside said cylinder when the plunger approaches the end of its pressure stroke.

6. In a pump for pumping liquids, or the like,. means forming a pressure chamber including au l cylinder anda piston reciprocable therein, an annular groove in said piston having communication with said chamber only through the clear- 7. In a'pump of the class describedyhereina piston having a metering groove cooperates with port means in a lcylinder for controlling flow to and from the pressure chamber, a pressure relief groove in said piston below said metering groove, f and a port in the wall of said cylinder adapted -to communicate with said pressure relief groove when the piston approaches the end of its pressure stroke, said port being positioned to remain out of communication with said metering groove during substantially the entire eilective pumping stroke of said-piston.l v

8. In pumping apparatus, means forming pressure chamber including a cylinder and a piston reciprocable therein, said'. piston having a groove inthe surface thereof and said rcylinder having a port therein adapted to communicate with said grooveonly when the piston Iapproaches lthe end of its pressure stroke, said groove vbeing in communication. with said pressure chamber only through the clearance space between the piston and cylinder walls.

9. In pumping apparatus of the-class described,

'a casing, means in said casing forming a pressure space between the piston and cylinder, and a groove in said piston adapted to communicate with said port only whenthe piston approaches the end of its pressure stroke.

10. In pumping apparatus of the class described,`

lmeans forming a pressure chamber including a cylinder having inlet and by-pass port means and a port, the inner end of which is spaced below and approximately v degrees circumferentially from said portmeanaand a piston reciprocable in said cylinder adapted to control 4flow to and from said cylinder through said port means, said piston having a groove in the surface thereof adapted to communicate with said port whenever the piston approaches the end of its pressure stroke. e v

v ALBERT '1'. Bremsen.

anemona errno The following references are of record inthe'? ille of this patent:

UNITED STATES PATENTS Number Name n v Date 902,501 Machlet Oct. 27, 1908` 1,379,248 Carrey May 24, l92l 1,409,868 Kien Mar. 14, 1922 1,917,690 Beeh July 1l, 1933i 2,109,785 Starr Mar. l, 1938 Bremser Aug: 13, 1940'