US2657634A - Hydraulic pump - Google Patents

Description

Nov. 3, 1953 L. s. GREENLAND ET AL 2,657,634

' HYDRAULIC PUMP Filed oct. 19,/ 195o 5 sheets-sheet 1 Filed Oct. 19, 1950` 5 Sheets-Sheet 2 1E l A 1V V m 50 T T .1 3646.142 -5249 47 .12 .sfz` 42 4o ,1- -HY 101\ 4i 7` l Y 26 64 62 y 102 20H 63 111 102* 17g 1 .fg

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- HYDRAULIC PUMP 5 shets-sheet s Filed Oct. 19. 1950 NOV 3, 1953 l.. s. GREENLAND E'T AL 2,657,634

HYDRAULIC PUMP Filed Oct. 19, 1950 NOV. 3, 1953 l.. s. GREENLAND ET Al; 2,657,634

' HYDRAULIC PUMP Filed Oct. 19,' 1950 5 Sheets-Sheet Patented Nov. 3, 1953 iUNITE) -USTTf'ES OFIF 2,657,634 iIYDRAULI'C""ILIP Leonard S. 'Greenland, Compton, lillalverhanipton, andflhomasEdwa-rds, Bjlbrogolggneanwglverhamvwn England, assigegrs ,tali- M-.Hlr son Limited, London, England, 'a company of Great'ritain comme. (otite-"sim nl This invention relates to variable-delivery hydraulic `pumps of the type comprising aplurality of pump barrels and 'associated plungers,

aca-m shaft, a cam mechanism operated by the cam shaft for effecting reciprocationof the pump z-plungers in their barrels, the pump barrels being coupled in pairs -to "delivery lines,A allocated `one ltoiea'ch pair of pumpfbarrels, and the cam mech- -anism being so designed that the two pump -plu-nge'rs of each pair vcooperate to produce, at

each'setting of the delivery control 'mechanism In U. S, Patent No.2,553,063 we -have described a pump of this type in which 'the 'plungers are operated from the cam mechanism through the agency of rocker arms pivoted to a regulating sleeve, Awhich is rotatable in relation tothe cam shaft so as to vary the effective length of the rocker arms and therefore the stroke of the -plungers In this form of pump springeloaded poppet-type inlet and discharge valves were as- Sociated with each pump barrel. We have found, however, that the use of valves of this kind results in some degree of non-uniformity in delivery from'the pump at low speeds. Apparently incorrect seating of the vvalves and variations in spring vcharacteristics prevent correct matching of the delivery from the pairsof connected barrels at low speed and small delivery. The object of this invention is to provide an improved form of valve gear.

The invention accordingly provides a hydraulic pum-p of the above type, in whichY the valves controlling the inlet ofliquid to and its discharge vfrom the pump barrels are operated mechanically from the camshaft. We find that by positively opening and closing the inlet and discharge ports associated with the pump barrels, undesirable pulsation in the flow from the pump is eliminated.

In the preferred form of the invention; v'as applied-to a pump of the kind described in U. S. Patent No. 2,553,0631,the pumpbarr'els are arranged radially in -relation to the cani shaft in a plurality of aligned groups, and a rotary valve is associated with each .group of barrels, the valves being positively oscillated to and fro by an eccentric or the equivalentA driven by the .Y cani shaft and being fome@ with inlet and c-hargc ports t`vhichareA4 brought alternatively intoe'gister with the pump barrels at the appropriate times in the cycle "of rotation of the camshaft. V

AYPatent No. 2,553,063, variation of the position :of adjustn'i'ent ofthe regulatingsleeve in relation to the cam shaftwill alter the 'moment gin f the cycle 'of rotation'of the cam shaft at which the delivery `stroke of any given plunger v"will cease. Provisin 'is therefore made for auto- 'matic "adjustment in phase of the eccentricin relation to the `cam shaft on rotation of the regulating sleeve, so as to effect corresponding change "in the timing of the movement'of the rotary valves..

Two 'embodiments of the pump according lto the invention, suitablev for supplying f1`1`el to a fg-as turbine engine, will now be described in detail, by way. of example, with reference 'to the accompanying drawings, in vvhich: Y

;Fg. 1 is a cross section throughthe rst form bfLpump taken on the line I-I in Fig.

Fig. 2 is a section on the line II-II'in Fig, 1, Figs.; 3:-7 arerespectively sections on the lines lII-IIL. IVeeIV, Vf'-V, vVIe'fVI and VII --.VII. .in Eig. 2, Figs. 3 and 4 being on 'a largerscale, and Fig. 5 showingthe eccentricin a position'dif- Y `ferent Afrom that shown in Fig. 2,

Figs. 8-'13 arexdiagrammatic views, Similar to Figs. 3 and 4 showing the positions v assumed '.by one'of the rotary valves at different points the Stroke of one of the associated pump plungers. Fig. l14 is,a part longitudinal section through thesecond form ofv pump, and

Fig. l5 is a fragmentary View of partof its mechanism for changing the phase of the ecf centric V in relationto the camshaft.

scribed in U. S. Patent No. 2,553,063. The pump has sixteen pump barrels 20 arranged radially,

in aligned groups of four, spaced apart in relation Ato a central cam shaft |2I. Fig. 1 shows one of .each of the four groups of pump Y barrels, while Fig. 2 shows the top group of four aligned pump barrels. The four pump barrels of each group are coupledin pairs', as later Vdescribed, to twojdelivery lines 2l, 22 (Figi `6) cor"n inunicatingv with two delivery outlets 2-3; 2'4. There are thus eight delivery outlets for the sixteen pump barrels and these fserve Yto supplyvfuel 3 to the eight injection nozzles (not shown) of a gas turbine.

The cam shaft |21 carries two cams 25, arranged in anti-phase i. e. 180 out of phase with one another, which actuate the pump plungers 25 on their delivery stroke through the agency of rocker arms 21 (Fig. 1), pivotally mounted on pins 28 carried by a regulating sleeve 29 surrounding the cam shaft |2|. The rocker arms 21 carry rollers 3i, rotatably mounted on the rocker arms by pins 32, and springs 30 hold the rollers 3i in contact with the cams 25. The plungers 20 are returned. by springs 33 on the suction stroke, the springs 33 bearing against tappets 35 attached to the inner ends of the plungers 23, Each rocker arm 21 coacts with the tappets 345 of a pair of adjoining pump plungers 23, as shown in Fig. 2, and alternate pump barrels in each group communicate with a common discharge passage 2|, 22. Thus the first barrel 20 of the group reading from the left hand side of Fig. 2, which is operated by the left hand cam 25, and the third barrel from the left of that group, which is operated by the other cam 25, discharge into the common discharge passage 2i. The second and fourth barrels of the group communicate with the other common delivery passage 22.

The one plunger of each coupled pair of barrels is thus executing a suction stroke while the other is executing a delivery stroke, and the cams 25 are so shaped that, when the discharge from one barrel of the pair is increasing, immediately following its suction stroke, that from the other barrel is correspondingly decreasing, while when the discharge from one barrel is decreasing, imrnediately following its delivery stroke, that from the other barrel is correspondingly increasing.

The regulating sleeve 29 is coupled to a boss carrying four servo vanes 35 (see Figs. 2 and 7). The servo Vanes 35 (see Fig. '7) are rotatable, for the purpose of rotating the sleeve 28 and thereby varying the delivery of the pump, in their respective sections of a housing defined by four radial walls 10| in the pump casing. In the boss |05 are formed four passages |02, and four passages 03, longitudinally oifset from the passages |02. to the boss |00 is a tubular insert |011 in which are formed a pair of peripheral grooves |05, |06 adapted to cooperate respectively with the passages |02, |03. Two radial ports |02 in the insert communicate with the groove |25 and two radial ports ||0 in the insert communicate with the groove |06.

Inside the insert 501i is mounted a sleeve valve 501, having a spigot |58 to which are fixed a manual operating lever (not shown) and also a pointer (likewise not shown) which coacts with a scale on the end wall of the pump housing to indicate the delivery for which the pump is set. In the outer surface of the valve |01 are provided two longitudinal ports which communicate, in all positions of adjustment of the valve, with an inlet |12 for oil under pressure and a pair of lands H3 on the valve normally seal the ports |09. Two other ports ||4 vin the valve communicate with the interior |20 of the valve, and thence with the interior of the pump casing, and lands |15 on the valve nor- ;nially seal the ports H0.

is supplied, from the ports and the ports |09 to the passages |02, while the passages |03 are connected, through the port |06 and the ports H4 to the interior of the valve |01. The vanes 35 therefore rotate anticlockwise as seen in Fig. 1, to eifect corresponding movement of the sleeve oil being expelled through the interior of the valve 01 to the pump casing where it serves to lubricate the pump. The movement ceases when the insert has been rotated suiciently for the ports |00, H0 to be again sealed by the lands H3, |15 on the valve |01.

Obviously, the reverse state of affairs will prevail when the valve |01 is rotated clockwise as seen in Fig. 7, oil under pressure then being supplied to the ports |03 and the ports |02 being connected to the interior of the valve i01, with the result that the vanes 35 will rotate clockwise.

In all positions of the servo vanes 35 the plungers 2Q are positively moved by the cams 25 to the outer ends of the barrels on the delivery stroke. the distance to which they may be returned by their springs 33, on the suction stroke, varying however with the eiective length of the rocker arms 21.

Associated with each group ci pump barrels is a rotary valve 35, carrying a crank pin 31 (Fig. 5) coupled, by a link 38, to an eccentric 30 driven by the cam shaft |21 and common to all the valves. Each crank pin 31 is supported by a member 40 (Fig. 2) coupled to the valve 36 by a key 4|, the outer end of the link 38 being accommodated in a cut-away portion 132 (Fig. 5) of the member 40. Each of the valves 30 is oscillated to and fro by the eccentric 3.2 to estab-lish corresponding inlet and discharge connections to and from the associated pump barrels. It will be suiiicient to describe but one of the valves 36, viz., that shown in Fig. 2.

Fuel from a fuel inlet passage it common to all the valves 36 passes, via an annulus 00,' an inlet conduit 45 and a port l5 in the valve into a central passage 41 in the interior of the valve. The passage i1 communicates with four radial inlet ports 48 in the valve, one for each pump barrel. These ports 48 are relatively staggered, having regard to the fact that two of the plungers will be executing suction strokes while the other two are executing delivery strokes. The suction ports d8 are brought, by movement of the rotary valve 35, into register with the ends of the pump barrels remote from the cam shaft at the appropriate times in the cycle of rotation of the cam shaft.

Surrounding the valve 36 is a fixed sleeve i3 having in it four arcuate grooves. Two of these grooves 50, namely those associated with the first and third pump barrels from the left of the group, communicate, as shown in Fig. 6, via ports 5| with the discharge passage 2|. The other two annular grooves 52, namely those associated with the second and fourth pump barrels from the left, communicate, via ports 53, with the other discharge passage 22. The valve 36 has four arcuate discharge ports 54 (Figs. 3 and 4) each of which cooperates with an associated port 55 in the sleeve 49. The sleeve 40 has four ports 50, one communicating with each of the pump barrels.

When any plunger 26 is in bottom dead centre position the valve 36, which is rotating clockwise as seen in Fig. 8, occupies the position shown' in that figure, in which it closes the port 56. As the plunger begins its delivery stroke, the valve 30 moves clockwise into the position shown in Fig. 9, in which the port 54 is brought into cooperation with the port 56, so allowing fuel to be rnunication with the port 54.

faesaesa @expelled from the'p'ump barreLthrough theports l2151i, 54, 55 to the anular lgroove -50 or 52 inthe :sleeve 49, and thence to lthe delivery passage ..2-1 v or 22. "Figure shows vthe `position ofthe valve -361at the completion of :its clockwisemovement,

the yplunger 26 having .performed abouthalf of its "delivery stroke. In Fig. ll, the plunger 26 has nearly Icompleted its deliveryY stroke and the valve 36 has begun its movement in the counter-clockwise direction, the port 56 still :being in com- In Fig. l2 the plunger 26 has reached its top dead centre position, and the valve 36 has moved into -positionto close the port 56. As'the plunger 26 ycommences .its suction stroke the -valve -36 moves 'counterclockwise into the position shown Ain Fig. 13, 1in

'which the suction port 48 'in vthe valve is in v'cooperation with the port 56. At the llimit-of the counter-clockwise movement of the valve "36, the

.suction port 48 is fully in register with 'the port 56. Then, as the valve 36 commencesits clockwise movement, the suction `port 48 is gradually brought out of register with the^portl56 until the -bottom dead centre position of the plunger is.

The above-described cycle of reached (Fig. 8). operations is then repeated.

The valve 36 is provided with "idle ports v1411, 154 which 'are respectively situated opposite each vof the inlet 48 and discharge ports 54. These idle ports ensure that the valve is hydraulically balanced and is not subject to side loads which might cause it to stick. As shown in Fig. 9, the

Aside load to which the valve 36 is subjected, during the discharge stroke, by the pressure ofthe fuel in the discharge port 54, is balanced bythe pressure of the fuel in the idle port 154 which is then open to the groove 50 through a port 51 in the sleeve 49.

As explained above, it necessary, when the regulating sleeve 29 is rotated relatively to the cam shaft 1.21 by the servo varies 35, for the eccentric 39 to receive a corresponding rotational vmovement to adjust its phase relation to the vcam shaft.

The eccentric 39 is rotatably mounted on the cam shaft 12| and carries one'sun Wheel 58 of a ing sleeve 29 is rotated, the bevelr wheelv 54 turns with it, thereby rotating the planet carrier V61 about the axis of the cam shaft and effecting a corresponding rotation of the sun wheel 58, and of the eccentric 39, about the axis of the cam shaft.

The pump shown in Figs. 14 and 15 is similar in all its essentials to that shown in Figs. 1-13, but has a different mechanism for adjusting the phase relationship of the eccentric to the cam shaft. In this case a boss 65, to which the servo vanes are attached, has an internal thread 66 engaging a helically threaded member 61 supported by a bearing 68 so that it may rotate on a rod 69 mounted in a cavity 10 in the cam shaft |21. Collars 11 on the rod 69 coact with the member 61 so that, as the boss 65 of the servo vanes rotates axial movement will be imparted to the rod 69. The rod 69 carries a key 12 having projections 13 passing through opposed axial slots 14 inv the cam andlrengaging .inclined :grooves 1.5 (seeFig.` 15) in the boss 'of the eccen- Itrici'ill. The key 12.*servesfto'couplelthe eccentric V39 and rodl69 to .the camshaft |21 vsoftlia'tithey rotate with it.' .As willreadilybe understood, the

Vaxialzmovement imparted totherod 69 when the l'servo :vanes .rotate to Vimpart rotational .adjustment to the regulating sleeve 29 will, through fthe coaction of 'the projections f13 with 'the helical slots .15,effect'rotational:adjustment of the eccentricf39 in relationtozthe cam shaft 121.

What We'claimras 'ourinvention `and desire to secureby Letters Patent is:

1. A hydraulic pump,fcomprising :a camshaft,

- pump barrels disposedfradially in relation to the vcam. shaft and arranged in a `plurality Vof groups,

lwith the barrels of each Vgroup having their axes y'disposed vparallel .to one another in a common :axial rplane of the'canrshaft,v ia plunger 'mounted to reciprocate in each pump barrel to perform suction and delivery strokes, ian inlet vfor liquid,

vthe `pump barrelsvbeing arranged in pairs and each pairrof pumpbarrels having 'a common rdeliveryoutlet, a cam mechanism on the cam shaft for reciprocating the plungers in 'their respective pump barrels, means for regulating the delivery strokes of saidplungers, said cam mecha- `nism being soshapedithat the flow of liquid in Veachdelivery outlet is constant and determined in magnitude by the setting Vof Asaid regulating means, an oscillatory valve associated with yeach group of pump barrels, and valve actuating meansdriven by the cani shaftifor oscillating all of said valves, said valves. havin-g inlet and dischargeports for connectingthe associated pump barrels to saidv inlet, Aduring the suction strokes of the plungers in said-barrels.

2. A hydraulic pump, ycomprising a vcam shaft,

pump' barrels disposed radially in relation to the Y cam. shaft and arrangedin a Aplurality'of groups,

withthe barrels of yeach group having their axes disposed parallel to one another in a |common axial. .plane of thecam shaft, a -plunger mounted -to reciprocate in each `pump barrel to perform .suction and .delivery strokes, van inlet for liquid, the pump barrels being arranged. in pairs and -each pair of pump barrels having a common de- 50 Ylivery outlet, a,- cam mechanism on the lcam shaft for reciprocating the plungers in their respective .pump barrels, a regulating sleeve surrounding cam shaft and. rotatable in relation thereto, rocker arms pivoted to said sleevefor imparting reciprocating movement from said cam mechanism to said plungers, said cam mechanisrn being so :shaped that the flow of liquid in. each delivery outlet is constant and deter- .niined in magnitude by the setting of said regulating sleeve, an oscillatory valve associated with each group of pump barrels, an eccentric driven by the cam shaft and arranged to impart oscillating movement to said valves, said valves having inlet and discharge ports for connecting the associated pump barrels to said inlet, during the suction strokes of the plungers in said barrels, and to the associated delivery outlet, during the delivery strokes of the plungers in said barrels, and mechanism linked to said regulating sleeve for effecting, on rotation of said regulating sleeve, rotational adjustment of said eccentric in relation to said cam shaft.

3. A hydraulic pump as claimed in claim 2, in which the mechanism for effecting rotational adjustment of said eccentric comprises a differential gear, including a sun wheel xed to the eccentric, a sun Wheel fixed to the cam shaft, a planet carrier coacting with said sun wheels, a pair of further sun Wheels, one of which is xed and the other attached to the regulating sleeve, and a toothed wheel mounted on said planet carrier and meshing with both of said further sun wheels.

4. A hydraulic pump as claimed in claim 2, in which the mechanism for effecting rotational adjustment of said eccentric comprises a rod mounted for axial displacement within the cam shaft, a projection on said rod engaging an axial slot in the cam shaft and an inclined slot in the eccentric, an externally threaded member mounted to turn on said rod, means holding said member against axial movement in relation to said rod, and an internally threaded boss on the regulating sleeve engaging said externally threaded member.

5. A hydraulic pump as claimed in claim 1, in Iwhich each group of aligned pump barrels comprises four pump barrels, in which the cam mechanism comprises two cams of the same shape but displaced 180o in phase, each cam being arranged to actuate the plungers in a pair of adjoining pump barrels in each group, and in which each valve controls communication between the pump barrels of the associated group and a pair of delivery passages, each delivery passage receiving the discharge from two pump barrels, one allotted to each cam.

6. A hydraulic pump as claimed in claim 5, comprising sleeves surrounding the valves, each valve having a central bore communicating with the inlet, four inlet ports and four delivery ports, the delivery ports communicating alternately with the two delivery passages through ports in the associated valve sleeve.

7. A hydraulic pump as claimed in claim 6, in which each valve is formed with idle ports opposite the inlet and discharge ports therein, said idle ports serving to provide hydraulic balance for said valve.

8. A hydraulic pump comprising a shaft, a i

pair of pumping units, each pumping unit comprising a barrel disposed radially in relation to the shaft and a plunger in said barrel, an inlet for liquid, a delivery outlet common to and arranged to receive the discharge from said pair of pumping units, a cam mechanism on the shaft for reciprocating the plungers in their respective barrels, a regulating sleeve surrounding the cam mechanism, rocker arms pivoted to the sleeve on axes parallel to that of the shaft for imparting movement from the cam mechanism to the plungers, means for rotating said sleeve in relation to the shaft so as to vary the effective length of the rocker arms and therefore the `delivery of the pump, saidcam mechanism being so shaped that the iiow of liquid in said delivery outlet is constant and determined in magnitude by the position of rotational adjustment of said sleeve in relation to said shaft, an oscillatory valve common to the barrels of said pumping units, an eccentric driven by said shaft for imparting rocking movement to said valve, said valve having inlet and discharge ports for connecting each of said barrels to said inlet, during the suction strokes of the plunger in said barrel, and to said delivery outlet, during the delivery strokes of the plunger in said barrel, and mechanism linked to said regulating sleeve for effecting, on rotation of said regulating sleeve, rotational adjustment of said eccentric in relation to said shaft.

9. A hydraulic pump comprising a shaft, a pair of pumping units, each pumping unit comprising a barrel disposed radially in relation to the shaft and a plunger in said barrel, an inlet for liquid, a delivery outlet common to and arranged to receive the discharge from said pair of pumping units, a cam mechanism on the shaft for reciprocating the plungers in their respective barrels, a regulating sleeve surrounding the cam mechanism, rocker arms pivoted to the sleeve on axes parallel to that of the shaft for imparting movement from the cam mechanism to the plungers, means for rotating said sleeve in relation to the shaft so as to vary the effective length of the rocker arms and therefore the delivery of the pump, said cam mechanism being so shaped that that flow of liquid in said delivery outlet is constant and determined in magnitude by the position of rotational adjustment of said sleeve in relation to said shaft, an oscillatory valve common to the barrels of said pumping units, valve actuating means on said shaft for imparting rocking movement to said Valve, said valve having inlet and discharge ports for connecting each of said barrels to said inlet, during the suction strokes of the plunger in said barrel, and to said delivery outlet, during the delivery strokes of the plunger in said barrel, and mechanism linked to said regulating sleeve for effecting, on rotation of said regulating sleeve, phase adjustment of said valve actuating means with respect to said shaft.

LEONARD S. GREENLAND. THOMAS EDWARDS.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,781,416 Sundstrand Nov. 11, 1930 1,990,263 Benedek Feb. 5, 1935 2,553,053 Simpson et al May 15, 1951

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