US2585544A - Fuel pump - Google Patents

Description

1952 w. FRIEDLANDER FUEL PUMP 3 Sheets-Sheet 1 Filed Dec. 9, 1947 wwmmwh mw mm RIVEYS Feb. 12, 1952 wiFRlEDLANDER 2,585,544

FUEL PUMP Filed Dec. 9, 1947 3 Sheets-Sheet 2 1952 w. FRIEDLANDER FUEL PUMP 3 Sheds-Sheet 3 Filed Dec. 9, 1947 MEQ Patented Feb. 12, 1952 NT OFFICE FUEL PUMP.

William Friedlander, London, England, assignmto Mono-Cam Limited, London, England, a

company of Great Britain Application December 9, 1947; Serial N0. 590,666 In Great'Britain December 18, 1946 '5 Claims.

This invention relates to fuel-pumps and distributors for petrol-injection internal combustion engines in which an accurately measured small dose of petrol (or other volatile fuel bydrocarbon) is injected into each cylinder during the suction and/or partof the compression stroke of the piston working therein. v

It is one object of the present invention to provide an improved fuel pump for'such engines which shall be of a simple and robust construction effectively isolating the fuel from the work- .ing' parts which requires lubrication and which fuel pump for an engine of the kind referred to comprises a plurality of closed pumping chambers, a suction and a delivery valve for each chamber, a common petrol supply to all the suction valves, a common petrol delivery means leading from all the'delivery valves, a collapsible bellows located within each chamber, resilient means normally holding each bellows in expanded condition, reciprocable elements driven from the engine and adapted alternately to collapse the bellows against theaction of their resilient means and to permit the latter to expand the bellows, each reciprocable element having a lost motion connection to its associated bellows for permitting the latter to remain in a collapsed or partially collapsed condition when the delivery pressure tends to exceed that' capable of being produced by the resilient means, and means capable of operation for simultaneously varying the pressure exertedjb'y the resilient means during the reciprocation'of the engine-driven elements.

opening each valve in turn, and means for ad- Ill 2. justing the'cam'means along its axisof rotation to vary the period for which each valve is kept open at each operation thereof.

With advantage, the chamber is of annular shape and the valves are arranged around a common central cam. The latter preferably has'a single rise thelengthfof which in the direction of rotation varies throughout the axial length of the cam.

The nature of the invention will be clearly understood from the following description taken 'in conjunction with the accompanying drawings which'illustrate one example of the way in which it may be carried into efiect.

In the drawings:

Fig. 1 is a longitudinals'ection, taken substantially on theline I I of Fig. 2, sho im the complete assembly of fuel'pump and distributor,

Fig. 2 is a section taken substantially on the line II-II of "Fi 11, some parts being omitted,

Fig. 3 is a view taken from the right-hand end of Fig. 1, the upper part being in elevation with the valve block of the distributor removed and the lower part being a section taken substantially on the line III-III of Fig. 1, and i Fig 4 is a fragmentary perspective view showing a cam sleeve employed in the distributor.

In the example (see 'Fig. 1) a housing! is formed with three parallel open-ended pumping chambers 2 leading from one face la thereof into a common larger bore 3 disposed at rightangles and containing an axially disposedshaft 4. The parts disposed in any one of the chambers Zfbeing the same and functioning in the same manner as thep'arts in any other of the chambers '2, the following description will refer more particularly to one only of thechambers but the same reference numerals will be used for identical parts in the figures of the drawings. The shaft 4 is mounted in bearings 5, Band 1 and is formed with three eccentrics 8 each carrying a strap 9 which is connected by a short connecting rod [0 to one end of a reciprocable rod ti axially disposed in the appropriate pumping chamberZ. On each rod I I is slidable, as a close fit, a sleeve l2 having a flanged outer end l za and having its inner end also slidableas aclose fit in an annulus Hiwhich rests on an internal shoulder M in the chamber 2 The annulus I3 has secured thereto the one end of ametalbellows l5 and is held against the shoulder l4 by a liner It fitting into the chamber {and engaged at its other end by a plug I! screwed into the open end of the chamber. The otherend of the bellows i5 is secured to an annular member l8 which is slidable on the end of the appropriate reciprocable rod H and is permitted a limited degree of movement relative thereto (in the direction for collapsing the bellows i5) due to the fact that a compression spring i9 is interposed between an internal flange I80, of the member l8 and the head of a stud 29 screwed into the rod i I. In the normal position, the spring I9 is fully compressed and the top faces of both the rod H and the stud 20 are spaced by a distance equal to the full stroke of the rod H from, respectively, the under face of the flange l8a and the under face of a cap 2| which closes the free end of the annular member I8. The cap 2| in the expanded condition of the bellows i5, is disposed close to the plug ii at the end of the chamber 2. Encircling each reciprocable rod ll between the annulus l2 and the annular member l8 thereon, is a helical compression spring 22 tending to expand the bellows, this spring being stronger than the spring 19.

The wall of each pumping chamber 2 is formed with an annular groove 23 (see also Fig. 2) and the part of the corresponding liner l6 lying over the groove is apertured at one or more points as shown at 24 (Fig. 1). At diametrically opposite points of each groove (see Fig. 2) there open radial passages 25 and 26, the passage 25 containing a spring-pressed ball valve 27 opening towards the groove 23 and controlling communication between the latter and a petrol supply passage 28, and the passage 26 containing a spring-pressed ball valve 29 opening away from the groove 23 and controlling communication getween the latter and a petrol delivery passage Referring to Figs. 1 and 3, it will be seen that the flanged ends 12a of the annuli l2 supporting the one ends of the compression springs 22 are themselves each supported by a pair of arms 3i extending radially from a common rocking shaft 32. on one end of which is secured an adjusting arm 33 connected to suitable control means (not shown). v v p -In the operation of the pump thus far described, the rotation of the shaft 4 carrying the eccentrics 8 causes reciprocation of the rods H within'the pumping chambers 2, the outward stroke of a rod being transmitted through the fully compressed Spring I9 disposed between the stud 20 and the annular member [8 to displace the latter to collapse the bellows 85 against the action of the main spring 22. The free volume within the pumping chamber 2 is thereby increased and petrol is drawn in through the appropriate ball valve 21. The inward stroke of the rod I l permitsthe main spring 22 to expand the bellows I5, thereby decreasing the free volume within the pumping chamber 2 and expelling the petrol therefrom through the appropriate ball valve. 29. Should the pressure in the delivery passage 30 build up, due to consumption of petrol by the engine at a low rate, the main spring 22 will be insufficiently strong to cause full expansion of the bellows i5 and delivery ofpetrol will be reduced accordingly. The reciprocable rod H will however execute its f ull inchamber 2 to the same extent, thereby increasing or reducing the loading of the main springs 22 and correspondingly varying the pressure at which petrol is delivered by the pump.

It will be seen that the working parts requiring lubrication are effectively isolated from contact with the petrol by the bellows arrangement adopted.

In the example chosen, the fuel distributor for an engine equipped with a pump as described above has a valve block 34 fitted into a part lb of the pump housing I and arranged substantially concentrically with the pump shaft 4. The latter is extended through an axial bore 35 in the block 34 as a splined shaft 4a. upon which is slidable, but notrotatable, a sleeve member 36 which has some clearance in the bore 35 and is actuated by a forked arm 3'! on a rocking shaft 38. The latter may be rocked by actuation of an arm 38a secured thereon.

The sleeve member 35 has a cam rise 39 formed thereon which (see Fig. 4) would be of triangular shape when developed fiat, i. re. the width of which (considered in the direction of rotation of the sleeve shown by the arrow in Fig. 4) progressively increases from one end of the sleeve to the other.

Around the outer part of the distributor (see Fig. 1) is formed (partly in the housing part lb and partly in the block 34) an annular chamber 40 receiving petrol under pressure from the pump delivery passage 30, and a number of equiangularly spaced radial bores 4| is formed in the block 34 to lead from the chamber 49 to the central bore 35 accommodating the cam sleeve '36. Each bore 4| is stepped to three diameters,

the largest diameter part being adjacent the chamber 40 and accommodating an annular valve seat 42 held inposition by an apertured cap 43 screwed into the mouth of the bore. Within the capis located a valve member 44 normally held against the seat 42 by a spring 45 and formed with a stem 44a which bears at its inner endagainst a disc 46 forming the closure of one end ofa' metal bellows 4'! having its other end secured to an annular projection 42a on the valve 'seat'member 42. The latter has radial bores 48 leading from an axial bore 49 (through which the stem 44a passes with play) into an annular groove 59 with which registers a passage 5! leading to a pipe (not shown) con nected to a petrol injection device in the appropriate engine cylinder.

The portionof the radial bore 4| in the block 34 which is of intermediate diameter receives the bellows 4'! with some clearance and the smallest diameter portion of the bore 4i contains, as a close sliding fit,'a rod 52 which bears at its outer end on the closure disc 46 of the bellows and at its inner'end on the cam sleeve 35. The inner end is rounded ofi (as shown) so that it will ride up the leading edge of the cam rise 39 as the cam sleeve rotates.

It will be understood that the bringing of the cam rise 39 beneath one of the rods 52 will cause it to be movedioutwards to lift the corresponding valve 44 from its seat and thus establish communication between the annular petrol chamber 49 and the respective petrol injection device on the engine. The duration of the period for which the valve is open is dependent upon the speed of rotation of the cam sleeve 36 and the width of the cam rise 39 in the circumferential direction at the zone where the rod contacts therewith,

In the operation of the distributor, the cam sleeve 36 is rotated t cause the op of each "ateism-1'4 .6 valve 44 in succession and the axial position of spective' ch'"embers andto' permifthe' resilient the sleeve in relation to the valve-actuating rods means to expand-the bellows to decrease said 52 iswvariediby operation .ofthe arm 3.811 as. defree volume, each reciprocable element" 'b'eil-lg sired .in order to increase .theldurations of the connected to its associated-bellows by" spring :periods for which the-valves are open as the '5 means weaker than said resilient meansior per engine speed increases. mitting the bellowsto remain in-anat least par- The means (arm 38a) controlling the cam t'ially collapsed-"condition'when a pressure exsleeve 36 may be inter-connected with the means ceeding that capable of being produced by' t'h'e (arm 33) controlling the delivery pressur'eoi the I resilient means tends to arise in the common aepump so that the fuel pressure is also increased livery means, and means capable of operation for as the engine speed increases. Alternatively the simultaneously varying the pressures exerted by means controlling the delivery pressure of the the resilient means during the reciprocation of pump may be connected with pressure sensitive theengine-driven elements in order to vary the devices in the air intake manifold making the pressure at which petrol is-delivered' by the pump pressure and therefore delivery a function 16 pump. of the air intake. 2. A fuel pump according to claim 1, wherein Here, again, the parts requiring lubrication the means for varying the pressure at which are iso t o the p o passages by the petrol is delivered comprises a movable abutment bellows devices 41 interposed between the valve for each resilient means and mechanism for sistems 44a and the valve-actuating rods 52. 20 multaneously adjusting the movable abutments The cam rise 39 on the cam sleeve 36 may by equal amounts. have its leading and trailing edges shaped as 3. A fuel pump for an engine of the kind rerequired, for example, so that the points in the ferred to comprising a plurality of closed pumpsuction strokes of the engine pistons at which ing chambers, a suction and delivery valve for the respective distributor valves 44 open and each chamber, a common petrol supply to all the close may be varied as the sleeve is displaced suction valves, a common delivery means leadaxially. In the example shown in Fig. 4 the ing from all the delivery valves, a collapsible belleading edge 39a of the cam rise is inclined in lows located within each chamber, resilient means relation to the axis of the sleeve 36 so that the normally holding each bellows in an expanded valves 44 will be opened progressively earlier in condition, reciprocable elements driven from the the suction strokes as the sleeve is moved to engine and adapted alternately to collapse the the left in Figs. 1 and 4. Additionally, the trail-- bellows against the action of their resilient ing edge 39b of the cam rise is oppositely and means to increase the free volume of their remore steeply inclined so that the periods for spective chambers and to permit the resilient which the valves 44 are open will increase in 86 means to expand the bellows to decrease said free length as the sleeve 36 is so moved to the left. volume, a h re p a le elem nt bein con- It is preferred to provide a spring-loaded nected to its associated bellows by spring means needle-type valve 53 (Fig. 1) in the delivery Weaker than said resilient means for permitting passage 30 leading from the pump to the petrol the bellows to remain in an at least partially colchamber of the distributor and to arrange 40 apse condition W a pressure exceeding that that this valve will only open when a predeterp l f being pr u by h re ilien means mined delivery pressure is exceeded but will be tends to arise in the eflmmen delivery means, a held open by a lower pressure of the fuel. This movable bu a h resilient means. may be achieved by arranging that the area of mechanism for Simultaneously adju t the the valve acted upon by the fuel is increased by I movable abutments y equal a t t va y t the lifting of the valve from its seat, in a known pressures ed y the resilient means during manner s provision facilitate t Starting the-reciprocation of the engine-driven elements, f t engine from t 1 and a fuel distributor including a chamber for In t preceding description the elements receiving fuel under pressure, delivery pipes which are expanded and cohapsed within the in leading one to each engine cylinder, valves for pumping chambers 2 have been refer ed to controlling communication between the chamber throughout as bellows. It is to be understood, and T ve p rotary cam means for however, that they may also take the form of open-mg each Valve m turn 1 means for i a flexible diaphragm the periphery f which is justing the cam means along its axis of rotation secured to an axial extension of the annulus I 3 ll to Vary the penod f whlch each Valve 15 kept and the centre of which is secured to the annular open at each operatlon m f member l8 slidable on the appropriate rod ll. A,fue1 m and dlstnbutor combmatton The rods H and pumping chambers 2 may then according to claim 3, wherein the fuel-recelvlng be considerably shorter in axial length. In the chamber is of annular shape and e Valve? are appended claims, therefore, the term bellows around a common. m can} haYmg is to be understood as including a flexible single use the length of whlch 1n the direction of diaphragm gletatlon varies throughout the axial length of e cam.

l i g ilfel gil i l ig for an engine of the kind re- For an 'm of the kind refeyreq a fuel ferred to comprising a plurality of dosed palm? a pump comprlslnga fuelsupply, a distributor, and ing chambers, a suction and delivery valve for mieans for Pummpg Sam p to the dlstnbutor each chamber, a common petrol supply to all the means t t t i bellow? and suction valves, 2. common delivery means leading mg Parts requmng the from all the delivery valves, a collapsible bellows i i bellows constltutes an lmpermeible Wan located within each chamber. resilient means Isolating the fuel passages from the movmg parts normally holding each bellows in an expanded requiring lubrication and the distributor comcondition, reciprocable elements driven from the prises chamber for receiving fuel under Pres engine and adapted alternately to collapse the Sure from the pumping means bores leading from bellows against the action of their resilient the chamber to a central bore delivery Outlets means to increase the free volume of their 76 leading one to each of said bores, valves mounted together with the cam means require lubricating 5 and a collapsible bellows mounted within each bore between the valve and the respective moving parts to isolate the parts requiring lubrication from the fuel within the distributor.

- WILLIAM FRIEDLANDER.

REFERENCES CITED The following references are of record in the file of this patent:

- UNITED 'STATES PATENTS :Number Number Name Date Alden Mar. 12, 1940 Palumbo Apr. 25, 1944 Lownsberry Dec. 18, 1945 FOREIGN PATENTS Country Date Australia, 1935

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