US2053027A - Pump - Google Patents

Description

Sept. 1, 1936. I E A NK 2,053,027

v PUMP Original Filed Jan. 11, 1935 5 Sheets-Sheet l S 1936- E. A. FRANks 2,053,027

PUMP

5 Sheets-Sheet 2 Original Filed Jan. 11, 1935 Sept. 1, 1936. E A, FRANKS 2,053,921

' PUMP Original Filed Jan. 11, 1955 5 Sheets-Sheet 3 Sept. 1, 1936. E. A. FRANKS PUMP 5 Sheets-Sheet 4 Original Filed Jan. 11, 1935 Spt. 1, 193a PUMP Original Filed Jan. 11, 1935 5 Sheets-Sheet 5 Patented Sept. 1, 1936 mm srsrs PUMP Ernest Arthur Franks, Whitchurch, Wales Original application January 11, 1935, Serial No. 1,400. Divided and this application September 9, 1935, Serial No. 39,851.

October 30, 1934 12 Claims.

This application is a division of my application No. 1,400, filed January 11th, 1935.

This invention relates to pumps and more especially to pumps for supplying fuel to Diesel and other compression ignition engines.

The invention is particularly concerned with an arrangement which comprises two pistons dis.- charging to a common discharge and operable through followers by rotary cams at least one of the followers being movable to advance or retard the follower with respect to its cam so as to vary the phase relationship of the two pistons. The main object of the present invention is to provide improved means whereby the fuel supplied by the two pistons can be regulated.

According to the present invention in a fuel pump which comprises two pistons discharging to a common discharge and operable, through followers by .rotary earns, a movable regulating member being provided for at least one of the followers to advance or retard the follower with respect to its cam and so to vary the phase relationship of the two pistons. The or each movable follower is so slidably mounted in the regulating member as to be constrained to move in the same direction as that of its associated piston while the regulating member is constrained to move in a plane which is transverse with respect to the said direction of movement of the piston. In Diesel or compression ignition engines,;it is necessary that the delivery be under control and capable of quick and definite regulation as between-maximum and no delivery, it being further. necessary that the point of commencement of delivery in relation to the engine cycle be under control so as to get the best firing point for different loads on the engine.

To effect this there is provided a pump element having two pistons (or a piston and slide valve) driven by mechanism which is adapted to reciprocate the pistons in an adjustable out-ofphase relationship. These two pistons open into a common delivery chamber so that while the pistons are operating in the same sense, both operate to deliver fuel, but when one piston operates in the reverse sense, the delivery of one is taken by the other so that no effective delivery is established: by alteration of the two phases simultaneously the timing of effective delivery is adjusted and by altering the phases relatively to one another, the efiective delivery is adjusted.

Where the total volume required to be delivered by the pump would be extremely small when divided-between two pistons, one of the pistons which may be larger thanthe other could act as In Great Britain the delivery pump and the other as a piston or spill valve. The construction of both pistons would be the same excepting that as the piston forming the piston valve was made smaller in area the stroke would be increased to give the e same volume as the delivery pump or the profile of a cam for operating this piston be so formed a torelea e t e p st n forming t e Spill valve at the required moment for the cessation of de livery of the fuel. .0

- .In any a e is de rab e t at t i o ing as the piston or spill valve should have a clearance volume somewhat in excess of the delivery piston proper so as to cause a partial vacuum in the chamber common tothe two pistons 1.5 at the instant of cut off. This can be effected either by a difference in pump diameter or in the stroke as allowed by the cam profile.

The invention is illustrated in the accompanying drawings as applied to a pump incorporating the invention described and claimed in the pending application Serial No. 1,400, filed January 11, 1935.

In the drawings, Figure 1 is a longitudinal section partly in elevation, Figure 2 a section on the line IIII Figure 1, Figure 3 a section on the line III-III Figure 1, Figure 4 a detail plan view, Figure 5 a section on the line V,-V Figure 1, Figure 6 a detail elevation and Figures '7 and 8 views similar to Figure 4 of a modification.

The arrangement illustrated in the accompanying drawings is a multi-unit pump arrangement (i. e. an arrangement comprising a plurality of pump units) and while for convenience reference has been made to the parts of one unit, 35 in the drawings corresponding parts of I the various units have been given corresponding numerals.

In the drawings each pump .element consists of two diameter rods-l, 3 and I, 3' working in two diameter cylinders 2, 2', 5, 5, the smaller diameter parts of the cylinders 2 and 2' opening into a common chamber .4 having a spring loaded outletvalve l2. The valve I2 is carried by a plug I2 having-a tapered lower face co-operating with a tapered washer 12 to provide an air-tight joint. The rods are formed of two diameters for the purpose described in the specification of the application Serial No. 1,400, but for the purposes ofthelpresent invention it is merely necessary to discuss the smaller diameter parts I and I" of the rods and to regard them as two pump elements discharging into a common chamber 4. The'pa-rts 2, 2 of the cylinders in which the pistons I and l operate communicate through a valve l3 and a passage H with a chamber [0, the various chambers being interconnected by a passage l6 and these chambers are supplied with fuel in the arrangement shown by the larger diameter parts 3, 3 of the rods l, I which feed fuel from a passage 1 and passage 6 to the chambers it through passages 8 and past non-return valves 9. v

The pumping effect is obtained by reciprocating the rods forming the pistons I, 3 and l, 3' by a cam 25 through intermediate members or followers 21, 2?.

The intermediate members or followers 21, 21"

are of square cross section and are mounted to reciprocate in the same direction asv the pistons I and l' in apertures formed between'the two opposed end walls of square aperturesformed in sliding plates or regulating members 28, 28 and two opposed side or filling pieces 28 28 which are interposed between the members 21, 21' and the side walls of the apertures in the plates 28, 28' lying tangentially with respect to the shaft 29 on which the cam 25 is mounted and at right angles with the axis of the pump rod. The plates 28, 28' are movable in a direction which is in a plane transverse with respect to the direction of movement of the pistons.

The 'tworods forming the piston I, and!" are I spring loaded so as tohold them against their intermediate members 2?, 2i and these members against their cam 26, this preferably being 'effected by 'a' single spring 30 which is coiled around a stationary'pin 3i and has its central portion 32 exte'nded to form areaction point and its two ends 33 received within apertures in the respective rods. 5

The movement of the sliding plates 28, 2B is regulated by a tongue or protuberance 34, 34 extending across the sliding plateat an inclination to the axis of the cam shaft, the tongues engaging grooves formed in a plane parallel with. the plane of movement ofthe plates 28, 28 but in a transverse direction with respect to the direction of movement of the plates 28, 28;

With the construction described it will be seen that by moving the sliding plates 28, 28 the intermediatemembers 21, 21' are moved to be advanced or retarded with respect to the cams and that this movement of the plates is effected by moving the control'b'ars 35, 35'.

'Any movement will, of course, cause an earlier or later movement (with respect to the cam) in a reciprocating motion of the piston associated with the cam.

'The-degree of sensitiveness of adjustment is a measure of the angle of the grooves or tongues. The smaller the angle formed between a line passing through the centre of the tongue and a line representing the direction of 'movement of the bars, the greater will be the length of travel of the associated bar 35 or 35' to effect a similar movement of the sliding plates 28, 28. And, further, the smaller the angle as mentioned the less will'be the reaction of the cam thrust on the sliding plates and with a very small angle and a long travel of the control bars 35, 35 the reaction is very small and the control takes place in a plane approaching right angles to the plane of reaction of the sliding plates. l

Any thrust imparted to the control bars in a horizontal direction may be taken up either by the walls of the casing of the apparatus, or where necessary by rollers or ball bearings 31, and the bar sliding in a direction at right angles to such thrust, is free from any reaction. The sliding able upon the quantity of fuel to be delivered, thus automatically ensuring the fuel injection meeting the load placed upon the engine. An arrangement employing a gear wheel 33 is shown in Figure 4 and the angles of the grooves in the two controLbars bear such a ratio that a movement impartedto one control bar 35 although transmitted equally to the other control bar 35' causes a smaller movement of one sliding plate 28 than of the other 28, and hence the change in position of one intermediate member 21 with respect to the cam 26 is less than the change of the other intermediate-member 21 with respect to the cam 25. Thus, suppose the period of delivery of the piston I. is to extendIover 'say'15 and it is desired to have control of 6' advance in injection, then the control bar 35 for the piston i will have to control over 21 whilst the control bar 35 for the piston I-will control over only 6. The ratio of the angle of the slots in the control bars 35, 35 would thus be 6:21.

Alternatively the arrangement shown in Figure '7 could be employed to give a similar result, the desired ratio in the movements of the plates 28, 28 being obtained by having a link 43 by which a movement of the control bar 35 is transmitted to the plate 28' in theratio of 21:6, the angles of the grooves in the plates being equal as is shown.

The regulation of delivery as described is effected by hand for quick operation but for regular running and the other conditions imposed on the fuel supply there is provided a governor.

The governorconsists of a liquid supply, preferably lubricating oil of low viscosity, to a cham-' her in which reciprocates a piston or the like on one control bar, this bar having a reaction spring. There is also provided in the liquid supply a controlled orifice such as a needle valve or the like.

It is known that with a constant volume delivcry pressure rises as the outlet is reduced and this variation in pressure is employed to cause reciprocation of the piston connected to the control bar.

' A corollary of thisis that with a fixed size orifice variations in quantity will cause variations in pressure and this also is made use of in causing the reciprocation of the control bars.

Liquid supply, which is effected at a ratio proportional to the speed of the engine, is obtained in the arrangement shown by two plungers 4|, 42 which are positively reciprocated by cam grooves 43, 44 in discs secured to the shaft 29 the plungers having pins 46 entering the cam grooves. These plungers when at one end of their stroke uncover passages 47 opening to a supply chamber 48 to allow liquid toflow into the plungers: this liquid is forced by the plungers 4t, 42 when mov ing on their delivery stroke past non-return valves 49, 50 to a chamber 5| which iscommon to the plungers and this chamber is provided with the regulatable orifice indicated at 52 and with a connection 53 to the cylinder 54 in which reciprocates the piston 55 connected to the control bar 35. The orifice is regulated by a valve 56 which has a screw threaded shank 51 so thatby rotating the shank, the orifice is covered or uncovered to a greater. or lesser extent, the orifice opening into thechamber48. w

It:wi1l now be ;seen:that if:fthe valve-56 be operated by closing .or. opening; the pressure .applied by liquid to the piston :willincrease or decrease and the control bars'willqbe caused to move, thus. increasing or decreasing the quantity of. fuel delivered to the engine;

,If the valve be set,- then increase or decrease inrthe speed of the engine: will. cause greater or lesser pressure to: be applied to the piston 55 and hence to the control bars and tending to cause-steadying of the engine running' Such a governor can be made extremely sensitive and quick'in control by the correct proportions of the components.

(2) By fixing one control bar and allowing the. other to be moved,a fixed moment for commencement of delivery and variable moment for cessation of delivery would be obtained. This can be obtained by an arrangement as shown in Figures 4 and '7 but omitting the gear wheel 39 or the link 40, the movable control bar being operated by hand by being coupled to some form of hand control, or worked by a governor such as that described. The object of providing the other (or normally fixed) control'bar in this case is to provide for adjustment from time to time and to meet the various conditions of different engines: .or an arrangement as shown in Figure 8 can be "employed inwhich case only one control bar 35is employed, the other control bar being omitted and the sliding pieces 28' are secured by pegs 28 (3) Both control bars free to moveindependently. This would give a variable moment for commencement of delivery and a variable moment for cessation of delivery.

The double piston arrangement described also possesses the further advantage of distributing the power required to operate the'pump.

As has been stated the drawings incorporate apparatus in accordance with the invention described and claimed in the co-pending application Serial No. 1,400 and to effect this the pistons l and I are made a slack fit in their cylinders and the pistons 3, 3"feed fuel not only to the chambers l0 but also to the clearance left by the slack it. In addition the chamber 10 is in communication with the passage lfi extending through a chamber l6 and passage I6 and tube 20 to a vent formed by a spring loaded valve I! which opens when the pressure of the fuel fed by the second piston 3 exceeds the spring loading: the opening of the valve places the passage l6 and hence the chamber l0 open :to a'low pressure'vent' passage l8 and the fuel displacement of the second piston 3 is arranged to be in excess of the requirements per cycle. Thus excess fuel, together with air, is allowed to pass through the vent II' which remains .open' until the second piston 3, ceases to displace fuel.

Furthermore, as is also described and claimed in the said application, Serial No. 1,400, the-tube 20 extends into a second tube 2! depending from a block 22 carrying the valve H the second tube 2| extending into a tubular casing 23 closed at .its upper end by the block 22 the casing being. closed at its lower end; the first tube 29 is spaced at its, upper. end fromthe block .22 and the lower end of the second tube 2] is spaced from the tubular casing; mercury or other liquid indicated at '24 and which will preventthe passage of air orother'gas, "and'will not react with the fuel is contained in the annulus between the second tubeZI and-the casing 23 and between the second tube 2l-. and the first tube 20 and it will be seen that air trapped above the mercury in the annulus between the second tube 2! and the casing 23 will be compressed when fuel pressure conditions rise and the air will react to maintain this pressure on the fuel. The interposition of mercury or other liquid between theairand the fuel prevents the air from passing to and mixing with the fuel. In order to prevent the spilling of mercury should the device become inverted, the first tube may have at its upper end a small orifice which, while allowing fuel to pass, will prevent or offer a large resistance to the passage of mercury.

58 is a reservoir from which lubricating oil is supplied to a passage 15 for supplying oil to grooves I4, M in the pistons 3, 3'. This is effected by a further plunger 59 which is held by. a spring 60 in engagement with a cam BI on the shaft 29. This plunger during its suction stroke draws oil from the chamber 58 past a nonreturn valve 62 and during its delivery stroke delivers the oil to the passage l5 past a nonreturn valve 63. In order to prevent the generation of unduly high pressure, a relief valve arrangement is provided. This relief valve is in the form of a piston 64 which carries the valve 62 and is urged by a spring 66, this spring being such as to allow the piston to be displaced against the spring 66 when the pressure generated by the plunger exceeds a predetermined value.

In order to prevent the pressure the passage l5 from dropping an excessive amount when the plunger 59 moves on its suction stroke a plug l5 closing the end of the passage 15 is arranged to form a housing vfor a springloade'd plunger l5 which reacts to maintain pressure in the passage l5. Alternatively a spring loaded diaphragm could be employed. Said plunger F provides resilience in the system so that the capacity of the system may vary,. the plunger being spring loaded for this purpose so as to give or yield when thecapacity of the system is required to increase. l

It is well known that the small pocket of air in a pumping system prevents a "snappy" cut-off in the delivery and it is further well known that air lodged in the system will prevent the functioning of a pump. I

To ensure any air in the pump system being expelled without the necessity for turning the engine supplied by the pump system a small hand operated piston pump 61 .is provided in communication ;through a non-return valve 6.8 with the fuel supply passage 1 and through a non-return valve 69- with the storage pressure side of the pumps (i. e. with the passage 15) this hand operated pump forces fuel through all the passages and drives air out through the spring loaded ventl'l. I

It is preferred to form the casing of the pump assembly. in two parts which are held together by dove-tailed recessed plates :70, the dove-tailed sides being slightly tapered, which engage projections H which are formed. coniointly by the two parts and are similarly .taperedz. thus, by forcing the plates 10 on to the projections 11, the two parts are drawn firmly together.

' It will be obvious that the invention isunot limited in its application to a multiple pump nor to a pump incorporating the; invention according to the'specificatiomserial No. 1,400.

What I'olaimis-: :1

'1'. .In'a fuel pump, two reciprocablepump elements, a conduit into -which both elements discharge, rotary cam mechanism reciprocating the pump elements, followers interposed-between the cam mechanism-and pump elements, guide members in which thefollowers are slidably guided and constrained-to movein the same direction as the respective pump elements m'eans mounting atleast'one of the 'guide'members for movement in a plane transverse with respect to the direction of ''movement of the follower guided thereby, and means to effect movement of the movable guide member tc vary the" position of the 'asso-. ciated follower with respect to the cam mecha 2. Ida fuel pump, two reciprocabl'e pump elements, at conduit into which both elements discharge, rotary cam'mechanism reciprocating the pump elements,'-followers interposed between the cammechanismand pump elements, guide members in which the-followers areis'lidably guided and constrained to move in the same direction as the respective pump elements, anti-friction means mounting at least one of the guide members for movement in a plane transverse with respect to ,the direction of movement of the follower guided thereby, and means to effect movement of the movable guide member tovary the position of the associated follower with respect to the cam mechanism.

3'. Ina fuel'purnp, tw'o reciprocable pump elements, a conduit into which both elements discharge, rotary cam mechanism reciprocating the pump elements, followers interposed between the cam mechanism and pump elements, guide'membersin which the followers are slidably guided and constrained to move in the same direction as the respective" pump elements, means mounting at least one of the guide members for'movement in aplanetransverse with respect tothe direction'of movement of the followerguided thereby, a control member for the movable guide member, me'ans' mounting the control member for movement in a plane parallel with that of the guide member and in a direction'atright angles to the direction of movement of the guide 'memher, and an inclined tongue and groove connection between the control member and the guide m emher so that movement of the control member effects movement of the guide memberto vary the position of the associated follower withrespect to the cammec'hanism;

4; In a'fuel pump, two reciprocable pump elements, a conduit into which both elements dis charge, rotary cam mechanism reciprocating the pump elements, followers interposed between the cam mechanism and pump elements, guide members in which the followers are slidably' guided and constrained to move in the same direction as the respective pump elements, anti-friction means mounting at least one of the guide members for movement in a plane transverse with respect to the direction of the movement of the follower guided thereby, a control member for the movable guide member, anti-friction means mounting the control member for movement in a plane parallel with that of the guide member and in a direction at right angles to the direction of movement of the guidemember, and an inclined tongue and groove connection between the control member, and the guide member so that movement of the control member efiects movement of the guide member to vary the position oftheassoci+ at'ed follower withlrespect to the cam mechanism. -45. In a fuel pump," two reciprocable' pumpv elements, a conduit into which both-elements dis-v charge, rotary eam mechanism reciprocating the pump elements, followers interposed betweenithe cam mechanism. and .the pump-elements, guide members'in-"which the followers are guided to move in the'same direction as the associated pump elements'means mounting the guide members for movement in atplane transverse with respect to the direction of :movement of the followers guid ed thereby, and means effecting movement of the guide members. in unison to.vary.the phase relationship between the two followers. '1

6. In a fuel pump, two reciprocablepump elements,-a conduit into, which both elements discharge, rotary cammechanism reciprocating the pump elements; followers interposed between the cam mechanism and .theipump. elements, guide members in which the followers areguided to move in the same direction'as the'associa'ted pump elements, means "mounting the guide members for movement. in a plane. transverse with respect to the direction of movement of thefollowers guided thereby, control'members one for each guide member; ..means guiding the control members for movement in a plane parallel with that'of the associated guide member and in adirection at right angles-to the direction of movementof the associated guide =member, and inclined tongue and groove connections between control members and the guide members and meanseifecting simul-v taneous movement ol thecontrcl members to vary the phaserelationship between the two followers.

7. In afuel pump, two reciprocab-le pump elements, a conduit intowhich bothelements dis-. charge, rotary cam mechanism reciprocating the pump elements, followers interposed between-the cam mechanism *and'the pump elements, guide members in which the; followers are guided to move in the same direction as the associated pump elements, anti-friction means mounting the guide members for movement in aplane transverse with respect tothe direction of movement .of the followersguided thereby, .control members one for each-guide member,anti-friction means guiding the control members for movement ina plane parallel with that of 'the'associated guide memher, and in adirection-at rightangies to the direction of movementof the associated guide member, and inclined tongue andgroove connections betweenicontrol members and the guide members and means effecting simultaneous movement of the control members to'vary the phase relationship between the two followers- 8. Two pistons, two, cylinders supported in parallel relationship and in which the two pistons are reciprocable, 'the cylinders openinginto a terposed'between the cam and the pistons, guide members in which the followers are constrained poevel ci n gs rsm ei t e control members into movement of the guide members to vary the setting of the followers relatively to the cam.

9. A plurality of pumps each comprising two pump elements discharging into a common discharge, rotary cam mechanism reciprocating the pump elements, followers interposed between the cam mechanism and the pump elements, guide members in which the followers are slidably guided and constrained to move in the same direction as the respective pump elements, means mounting at least one of the members for movement in a plane transverse with respect to the direction of movement of the follower guided thereby, a control member for corresponding movable guide members of all the pumps, means guiding the control member for movement in a plane parallel with that of the guide members and in a direction at right angles thereto, and

means converting movement of the control member into movement at right angles thereto of the said movable guide members to vary the setting of the corresponding followers of the plurality of pumps with respect to the cam mechanism.

10. A plurality of pumps each comprising two pump elements discharging into a common discharge, rotary cam mechanism reciprocating the pump elements, followers interposed between the cam mechanism and the pump elements, guide members in which the followers are guided to move in the same direction as the associated pump elements, means mounting the guide members for movement in a plane transverse with respect to the direction of movement of the followers guided thereby, two control members one each for the corresponding guide members of the plurality of pumps, means guiding the control members for movement in a plane parallel with that of the guide members and in a direction at right angles to the direction of movement of the guide members, means converting movement of the control members into movement at right angles thereto of the guide members to vary the setting of the corresponding followers simultaneously, and means transmitting movement from one control member to the other control member.

11. A plurality of pumps each comprising two pump elements discharging into a common discharge, rotary cam mechanism reciprocating the pump elements, followers interposed between the cam mechanism and the pump elements, guide members in which the followers are slidably guided and constrained to move in the same direction as the respective pump elements, means mounting at least one of the members for movement in a plane transverse with respect to the direction of movement of the follower guided thereby, a control member for corresponding movable guide members of all the pumps, means guiding the control member for movement in a plane parallel with that of the guide members and in a direction at right angles thereto, and inclined tongue and groove means converting movement of the control member into movement at right angles thereto of the said movable guide members to vary the setting of the corresponding followers of the plurality of pumps with respect to ity of pumps, means guiding the control members for movement in a plane parallel with that of the guide members and in a direction at right angles to the direction of movement of the guide members, inclined tongue and groove means converting movement of the control members into movement at right angles thereto of the guide members to vary the setting of the corresponding followers simultaneously, and means transmitting movement from one control member to the other control member.

ERNEST ARTHUR FRANKS.

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