US2208568A - Multistage dual shaft hydraulic pump or motor - Google Patents

Description

July 23, 1940. E. K. BENEDEK 5 (IULTISTAGE D jUAL SHAFT HYDRAULIC PUMP 0R MOTOR Filed July 10, 1935 4 Sheets-Sheet 1 INVENTOR :Fl.EKI .EIENEDEK ATTORNEY' July 23, 1940. r E. K. BENEDEK MULTISTAGE DUAL SHAFT HYDRAULIC PUMP 0R MOTOR Filed July 10, 1935 4 Sheets-Sheet 4 ATTORNEY 11E KKEIENEiJEK;

Patented July 23,

PATENT OFFICE -MULTISTAGE DUAL SHAFT HYDRAULIC PUMP OR MOTOR Elek K. Benedek, Bucyrus, Ohio Application July 10, 1935, Serial No. 30,608 3 Claims. 193-161) This invention relates to hydraulic pumps and motors and particularly to a new two stage reversible hydraulic engine which may be operated as a pump for generating hydraulic fluid pressure by separate independently controlled prime movers simultaneously and as a motor for utilization of pressure fluid from a given source for operating a single driven member at diflerent speeds or two separate driven members simultaneously or successively at greatly different and variable speeds.

One object is to provide a multistage motor for driving a given shaft or member at a wide range of speed while delivering the constant horsepower of a driving engine.

Another principal object of the present invention is to provide a multistage hydraulic machine in which each stage is reversible independently of the other when used as a motor and may ,be controlled independently of the other or in given as well as in any desirable variable relations thereto, and in which both units are reversible simultaneously as a pump so that the structure may be employed as a multistage pump, or as a multistage motor at high efliciency.

Another object is to hydraulically interconnect the stages of the pump for variable speed ratio of two independent prime movers in a manner assuring independent and flexible speed in each 0 prime mover with proper power ratio input and fluid pressure equalization of the powers of the prime movers.

Another object is to provide a hydraulic engine for this purpose which is highly emcient and 5 simple and compact in structure.

A more specific object is to provide a multistage pumpdriven by a high speed prime mover and a low speed prime mover simultaneously for generating pressure fluid in the common line of the stages. I

Another specific object is to mechanically counect the stages of the pumpfor a fixed speed ratio of high and low speed prime movers, so as to insure accuracy in synchronization thereof through the pressure and proper distribution of component powers therebetween.

Another object is to provide a multistage motor in which each stage is of different capacity and provided with a separate driven shaft for low and high speed respectively.

Another specific object is to separate and dampen the torsional oscillation of the prime mover and the driven shaft respectively.

A more specific object is to provide a hydraulic motor mechanism for use in connection with a power driven shaft by virtue of which the prime mover thereof can be operated at the speeds most suitable for highest efficiencies and economy of performance and, during the operation, the desired speeds of rotation of the shaft for given 5 operations can be effected by gradual continuous increments throughout the range of speeds required for such operation without operatively disconnecting the shaft from the prime mover while effecting the desired changes. 10

Other objects and advantages will become apparent from the following specification wherein reference is made to the drawings in which Fig. 1 is a horizontal sectional view through the axis of a pump of the present invention; 15

Fig. 2 is a cross sectional view taken on the lines 22 of Fig. 1 and 2a--2a of Fig. 3

Fig. 3 is a horizontal sectional view similar to Fig. 1, illustrating a modification of the invention;

Fig. 4 is a horizontal top plan view illustrating the use of the present structure as a hydraulic motor combination for driving a single shaft;

Fig. 5 is a fragmentary cross sectional view taken on a plane indicated by the line 5-5 in 25 Fig. 4; and

'Fig. 6 is a diagrammatic side elevation illustrating the use of the structure of. the present invention as a multistage pump.

Referring to the drawings, and particularly to 30 Fig. L'there is illustrated a dual stage hydraulic machine, comprising a rigid cylindrical casing I having a small diameter portion 2 at one end and a larger diameter portion 3 at the opposite end with a heavy rigid spider or radial wall 4 be- 35 tween said casing portions dividing the easing into a large diameter compartment and a small diameter compartment respectively. The ends of the casing portions Z and 3 are closed by rigid supporting end covers 6 and 1 respectively through which project the impeller shafts 8 and 9 respectively of the dual hydraulic engine.

For brevity in illustration, the structural details will be described as a pump, the uses as a motor being referred to generally. 45

Since the pump stage units are the same in structure, differing only in dimensions, the pump unit included in the housing portion 3 only will be described in detail.- With reference to Fig. 1, within the casing portion 3 is a rigid forged cyl- 5o inder barrel In which is mounted at its ends in combination antifriction radial load and thrust bearings for rotation about its longitudinal axis, the impeller shaft 9 preferably being formed integral with the barrel III. For supporting the V equivalent.

' means.

barrel within the casing portion 3, the wall 4 therein is provided with an axially extending annular flange I I within which is mounted the outer race l2 of a set of tapered roller bearings or their The barrel ID, in turn, is provided adjacent the wall 4 with an annular reduced diameterportion'l3 on which is mounted the inner race l5 of the roller bearings. Between the respective races are interposed the tapered rollers l6 arranged to resist both radial load and axial thrust, the races, in turn, engaging the radial portion of the wall 4 and the radially extending end wall of the barrel l0 adjacent the hub I3 for resisting axial displacement of the races. Correspondingly, the opposite end of the barrel is mounted in tapered rollers H, the outer race thereof being mounted in. the end plate I in a manner similar to the race l2 and being adjustable axially for compensating for wear and di-- v ametral slackness of the end plate I. Suitable shims may be-interposed between the outer margin of the plate I and end wall of the casing portion' 3 for effecting this adjustment. The barrel is sufliciently rigid to withstand deflection intermediate the bearings so as to reduce any tendency to bind on the valve. pintle to be described.

The barrel III has a plurality of circumferentially spaced radial cylinders l8 positioned midway between the rollers IG and l1 and each opening through suitable respective ports Illa into a central axial valve bore in the barrel Ill. The barrel II) has a radial flange l9 positioned in the zone of the cylinders l8 and in alignment with each cylinder there is provided in the flange a radial guideway 20, as better illustrated in Fig. 2. Mounted in the respective cylinders iii are reciprocable plungers 2|, each of which is provided with an enlarged head 22 which is reciprocable radially within the associated guideway 20. Each head 22 has a bore 23 which extends parallel to the barrel axis and in which is received an op.

erating crosspin 24 having reduced end portions 25. The central or enlarged portion of the crosspin is received in the bore 23 and mounted therein on capillary cageless n'eedle rollers 26 so as to be freely rotatable therein. The end portions 25 extend beyond the lateral faces of the heads 22 so as to cooperate with appropriate .reactance The lateral faces of the heads 22 are parallel to each other and present flat plane surfaces of smooth finish.

In order to actuate the plungers through the medium of the pins 24, apair of coaxial reactance rings 21 are provided at opposite sides of the plungers and ends of the flange. The flange likewise has flat parallel radial end walls which lie substantially in the planes of the side faces of the plunger heads, the flange being slightly narrower than the plunger heads. The rings 21 are provided with their adjacent walls flat and parallel so as to lie snugly adjacent the opposite faces of the flange l9 and lateral faces of the plunger heads 22, operating clearance only being provided therebetween. Each of the rings 21 is substantially square in cross section and is provided with annular grooves 28 opening through the radial walls adjacent the barrel flange and receiving the protruding ends 25 respectively of the crosspins 24 with sufllcient clearance to permit rolling engagement between each pin end and one wall only of the associated groove at any given instant, either the radial outward wall or the inward wall. 1

The rings 21 are mounted in an annularreactance member or stator 30, the stator comprovided with slide supporting bearing surfaces 32 at diametrically opposite portions. The casing 3 is provided with complementary flat parallel bearing surfaces 33 so that the stator may be supported within the casing 3 with its axis parallel to the axis of rotation of the barrel while being shiftable to change the eccentricity of the reactance .means relative to the barrel and its associated plungers. Control rods 34 are connected to the stator 30 and extend diametrically opposite from each other, through suitable bores in'the casing 3 so that the stator and consequently the stroke of the pump may be adjusted from the outside. The bores and the control rods '34 are provided with slight clearance space so that the stator 30 may be self-adjusting with the rollers 3| in order that the rollers 3| match their tapered grooves in rings 21 respectively.

As set forth above the barrel I0 is provided with anaxial bore with which the cylinders I8 are in communication, each through its individual port 180.. For efiecting the proper valveing relation 2. pintle 35 is provided, the pintle having an enlarged shank portion intermediate.

its ends by which it is fixedly secured in the partition wall 4. pintle is received in the valve bore of the barrel I0 and is provided with a valve portion 35a which lies in the zone of the cylinders l8 and terminates as closely as practicable axially beyond the ports 18a so that the entire valving portion 35a of the pintle may be maintained completely covered with hydraulic fluid and ahydraulic pressure oil fllm'provided thereabout for preventing elastic deflection and binding of the valve portion of the pintle as a result of hydrostatic unbalance. Beyond the valve portion remote from the wall 4 the pintle is provided with a reduced diameter race portion 35b on which operate capillary cageless needle rollers 36 which, in turn, are in rolling engagement with the walls of the barrel bore.

One protruding end of the The barrel bore is counterbored to a larger diameterat the end of the barrel adjacent the wall 4 so that a larger diameter portion of the pintle of thefllm between the pintle and barrel bore wall, the rollers preferably are of the capillary cageless combination or, if not true capillary rollers, are spaced preferably a capillary distance apart from each other. The pintle valve portion 35a is provided with a valve pressure port 38 and a diametrically opposite suction port 39, the ports being successively cooperable in valving relation with the cylinders consequent upon rotation of the barrel, and being reversible. The opposite end of the pintle is provided with a pressure port 44 and a suction port 45 corresponding to, the 7 ports 36 and 33 respectively and in valving cooperation with the cylinders of the smaller barrel 1 56 of the pump. These ports are reversible simultaneously with the ports 36 and 36 by reversing the main ports.

As illustrated in Fig. 2, the pressure port 36 is connected with longitudinal ducts 46 formed in the pintle and the suction port is connected with ducts 4| likewise formed in the valve pintle.

In the portion of the pintle by which it is mounted in the wall 4 is a main pressure port .42 and a diametrically opposite main suction or low pressure port 43. The main pressure port 42 is connected through the ducts 'with the individual ports 36 and 44 of .the stage units and Y the suction main port 43 is connected through the ducts 4| with the individual ports 35 and of the stage units. The ducts 40 consequently provide communication between the ports 36 and 44 and one of the main ports 42 of the two stage units. The suction ducts 4| provide communication between the main port 43 and the individual ports 39 and 45. Thus the ports 36 and 44 connect with one main port 42 and the ducts 39 and 45 connect with the other main port 43 of the pump. In this manner both the barrel ill and the barrel 56 may be operated independently by their respective shafts 5 and 6. As illustrated, the reactance of the smaller barrel 56 is also adjustable so that both the large and small units of the pump may be independently regulated for speed and torque and. independently reversed.

Referring. again to the barrel I, it is ofttimes desirable and even necessary that coupling means be provided between the barrel and the reactance for positively coupling the same for starting the reactance in synchronism with the barrel and.for maintaining the positive coupling engagement therebetween. For this purpose .a plurality of bores 5| positioned one bore between each pair of adjacent cylinders or guideway's 26 are provided in the flange [6, these bores extending parallel to the barrel axis. The bores are spaced preferably radially inwardly from the ,outer limits of the flange so that bridge portions 52 provide for retaining the strength of the flange at its outer periphery and for preventing deformation thereof under stress or during heat treating of the metal. In the reactance rings 21 are coaxial holes extending parallel to the barrel axis, the holes of one ring being aligned with those of the other and being positioned radially of the rings so as to lie within the radial limits of the grooves 26. Carried in each pair of aligned holes are coupling and clamping bolts '54.

These holes correspond in number and, in the center position of the pump, to the bores 5| so that they may be aligned therewith. Coupling bolts 54 are received in each pair of aligned holes and extend through the bores 5|, one end of each of the bolts 54 being in screw threaded engagement with one of the rings and the other end being provided with a head portion 54a so that the rings may be drawn toward each other.

Mounted on each bolt 54 is a sleeve 55 of proper diameter to snugly fit at its ends within the grooves 28 sothat the ends of the sleeves clearance at the ends so that they may come into rolling contact with the circumferential walls defining the holes 5| at the maximum stroke of the pump unit only, except that upon starting, the sleeves 56 may engage the walls of the bores 5| at any stroke so as to start rotation of the reactance by the barrel or, if the reactance is rotated, may start the barrel without undue racing of the pins 25 in the grooves 28. When operating at full eccentricity, however, the diameter of the sleeves 56 and bores 5| are such that the sleeves remain in rolling engagement and roll entirely around the circumferential walls of the bores, thus affording a positive coupling means between the barrel and reactance through the medium of the flange l5.

As will more fully appear hereinafter, it is sometimes desirable that the barrels ill and of the pump be mechanically connected and thereby constrained to a fixed speed relation with respect to each other, as more fully described in my opening application, Serial No. 7809, filed February 23, 1935. For this purpose the structure illustrated in Fig. 3 is highly desirable.v In Fig. 3, the parts corresponding to the parts illustrated in Fig. 1' are designated by corresponding primed numerals so that the parts and'operation thereof are clear without additional description However, in addition to the parts heretofore described, there is provided in the wall 4' a bore extending parallel to the barrel axis but disposed eccentrically thereto. Mounted within this bore is a sleeve 60 in which is rotatably mounted a shaft 62, the shaft 62 bein supported in the sleeve 66 in sets of capillary cagelessrollers 63 retained by suitable spacing washers. Keyed to the opposite ends of the shaft 62 are spiral gears 64 and 65 respectively. On the barrel l6 there is provided a spiral gear 66 complementary to the gear 64 on the corresponding end of the shaft 62 and in engagement therewith. A gear 61 complementary to the gear 65 and in engagement therewith at all times is provided on the barrel 56'. By this arrangement the barrels" are geared together and mechanically constrained thereby to a. fixed speed ratio with respect to each other at all times; The

size of the gears 64 and 66 and the gears 65 and effect a step-down speed relation from the small high speed barrel 56' to the larger slow speed barrel l6. Regardless of the speed ratio maintained between the barrels, however, by this mechanical connection, the reactances of the barrels may be separately adjusted, thereby adjusting the speed of the interconnected barrels when operated as a motor. Again, the stroke controlling means of both the large unit .and the small unit may be mechanically secured for operation in a fixed ratio to each other when desired. In the present application, however, as distinguished from my copending application, Serial. No. 7809, filed February 23, 1935, both units are provided with impeller shafts 8 and 9 respectively for driving connection with independent prime movers of fixed speed ratio to each other, when used as a pump and for connection to separate means, or selective gears of a train, to be driven by the structure when used as a motor. I

Referring next to Figs. 4 to 6 inclusive, some applications of the hydraulic machine herein for ,use as a motor. In this application of the machine, suitable brackets 68a and lila are secured to the casing portions 2' and 3' respectively and carry bearings 82a and 63a respectively, in which is mounted a rotatable driven shaft 64a. On the opposite ends of the shaft 64a are spiral gears 66a and 61a respectively, the gear 66a preferably being of smaller diameter than the gear 61a. These gears are connected to the shaft by suitable spline connections 68a and 69a respectively, so that the gears may be shifted along the shaft by a suitable shifting fork 18 to.

operative and idle positions. On the shafts 8' and 8' respectively of the machine are mounted gears 12 and 13, the gear 13 being smaller than the gear I2 and in mesh with gear 61a in one shifted position of the gear 61a. The gear 12 is in mesh with anidling gear ll positioned for cooperation with the gear 66a when the gear 66a is shifted by the fork ill to proper position. The fork I0 isoperable to shift both the gears 68a and 61a simultaneously so that one becomes operative and one idle concurrently.

In the form illustrated, the port 42' is considered the main pressure port and the port 43' is the main suction or low pressure port. As illustrated in Fig. 5, a return pipe line 16 is connected to the port 43' and communicates with a suitable sump 18. A working pressure pipe line 80 is connected with the port 42 and is provided with a valve 8| for purposes later to be described. The line 88 is connected to the pressure side of "a reversible, variable delivery pump A, whichsupplies the operating pressure fluid, the pump A being also. connected to the sump I8, as shown.

x The reactances or stroke controlling means of .the respective units are controlled independently by suitable hydraulic servo-motors through their pilot controls 82 and 83 which, in turn, operate control rods such as the rod 34 of Fig. 3. The

servo controls 82 and 83 are more fully. described in my copending application, Serial No. 749,746,

filed October 24, 1934 and may utilize the presstructure as a motor and to illustrate its advantages, the operation will be described in c'onnection with the driving of a spindle of a machine tool in which a lowspeed cycle of from 30 R. P. M.

to 300 R. P. 'Mris used at one time and a high speed cycle of about '1200'R. P. M. is used at another time. Only occasionally are speed cycles of 600 R. P. M., 800 R. P. M. and other speeds between 300 RP. M. and 1200 It P. M. required. Fluid under pressure is supplied from a constant delivery pump A through the line 80, the valve 8| being open. The pressure fluid flows to both units or stages of the motor so that the barrels l0 and 50 may be operated concurrently or selectively. The reactances of the units are independently adjusted for operation in the desired relation to each other. If it is required that the shaft 64a is to be driven in the same direction by both units, the small unit may be re ersed relout its most favorable speed range.

The slowest speed of 30 R. P. M. is obtained with a correspondinglylarge torque by setting both units at maximum eccentricity, thus utilizing the combined motor capacity for speed reduction. However, the large unit is so dominant in the capacity ratio, that no appreciable underspeed drive results from the addition of the capacity of the small unit.

If, now, speeds from 30 R. P. M. to 300 R. P. M. are required, it is only necessary to gradually reduce the stroke of the large unit and this may be done throughout this speed range without any appreciable change in efficiency 01' horsepower output. If the highest speed of the shaft 64a is required, the gears 61a and 13 are disassociated and the gears 12 and i4 and 16 associated. The capacity of the large unit is thereupon set at zero. This action, due to the much greater capacity of the large unit, will simultaneously increase the speed of the small unit to its critical speed at which the shaft is driven at 1200 R. P. M.

Due to the capacity ratio of the two units, the speed of the small unit will be controlled through a wide range by changes in the stroke or eccentricity of the large unit, as each unit is prevented from racing by the geared connection therebetween through gears 64, 65, 66 and 61 within the casing. If, therefore, the occasional intermediate speeds of 600 R. P. M., 800 R. P. M. etc. are required, these are obtained from the small unit by adjusting the roke of the larger unit so that only the required part of the pressure fluid passes to the small unit. The fluid passing to the largeunit is not wasted, but is added by the large unit to the same shaft 64a.

During these operations, the units are operated at high efliciency, since each dominates through- Thus the increase and decrease in speed is stepless and one unit is used as a valving means for controlling the volume of fluid passed to the other, thereby controlling the speed of the latter. Consequently, throughout their operating ranges, each unit may operate' at substantially its full stroke to insure efliciency in operation. If overspeed is required, obviously this can be obtained by reducing the stroke of the small unit after the large unit is idle and at zero stroke.

A contribution to the higher efliciency of the combination resides in the fact that a large and rigid iinit is necessary to deliver large torque at low speed efilciently, whereas a small unit is necessary to deliver low torque at high speed efliciently. In the structure shown, since the maximum fluid capacity of the large unit is several times that of the maximum fluid capacity of the small unit, low speed is obtained by the large unit and high speed by the small unit for the same total amount of pressure fluid. Each operates within a wide range of speeds and torque at substantially constant horsepower with relation to the speed of the pump A, both units being of economical design for the range in which they operate: Furthermore, both units have infinitely variable speeds with efficiency within their operating ranges.

.When the machine in connectionwith which the transmission is to be used and the operating range and characteristics are such. that a continuous rise in speed from the lowest to highest limit is required, the units are chosen with respect to each other so that when the capacity of the larger unit is reduced to the point where its efllciency begins to decrease appreciably and therefore this relatively large capacity has passed to the small unit, the small unit will be operating at the same speed as the larger unit and at high efliclency.

In many instances, such as in power lathes and the like, it is desirable that an extremely high torque at very slow speed be provided during the working cycle of the lathe tool and that very high speed and at low torque be provided for rapid traverse of the lathe tool to starting position. The connection illustrated in Fig. 4 is primarily for such operations. These are readily effected and a further range of efilcient operation provided du to the fact that the large unit is geared to the shaft 64 in step down speed relation, whereas the small unit is geared to the shaft 54 at substantially equal speed relation. Thus on the working cycle of the lathe, the fork 10 may be shifted to mesh the gears 61 and I3 and the large unit operated at full stroke. At the end of the working cycle, the fork 10 isshifted, disengaging the gears 61 and I3 and engaging the gear 66 and the idler gear 14, whereupomthe small unit being set at full stroke, the stroke of the large unit decreased to zero so that. the

rapid traverse of the lathe tool is completed and the working head is returned to starting position.

It might be pointed out, that by closing the valve 8i and driving either the large unit or the small unit as a pump, the other unit may be operated as a motor.

In Fig. 6 is illustrated the use of the structure as a pump, wherein two different prime movers are utilized and are to drive a common member, or as a motor driving two separate driven means. In the first instance, one prime mover B is connected to the large unit shaft 9 and another prime mover C is connected to the small unit shaft 8. Both units are then operated as pumps concurrently or independently and supply fluid through the common main pressure port 42, the fluid circuit being as illustrated by the arrows in Fig. 6. Such an application would be useful in integrating the power of two prime movers, one of which is high speed and one of which is low speed. In the example given, the prime mover B may be a low speed prime mover and the prime mover C a high speed prime mover so that the small unit may be operated at high speed and the large unit at low speed at which respective speeds they are most eflicient. Both may deliver the same pressure and even the same fluid capacity through the common port to a hydraulically driven means, such as the hydraulic motor D, thus providing efllcient synchronization of the output of the prime movers B and C, for driving the motor or for driving through the driving shaft of the motor, an engine E connected to the shaft of the motor.

Having thus described my invention, I claim:

1. A hydraulic pump mechanism comprising a large capacity rotary radial plunger, independently variable delivery pump unit, a smaller capacity rotary, radial plunger, independently variable delivery pump unit, independent driving means for the units respectively, and means connecting said units in a fluid circuit in parallel with each other.

2. A rotary, radial plunger pump ormotor comprising a casing, a plurality of coaxial barrel units mounted for rotation in the casing, plunger and cylinder assemblies carried by the barrel units respectively, reactance means for the assemblies, valve means for the assemblies'respectively, individual shafts on the units respectively operable at different rotative speeds and each shaft being connected to its associated unit for rotation together therewith and being coaxial therewith.

3. A rotary, radial plunger pump or motor comprising a casing, a large barrel and a small barrel rotatably mounted therein, shafts carried one by each barrel and respectively rotatable together with the associated barrel independently of the other barrel, plunger and cylinder assemblies carried by the barrels respectively, in dependently adjustable reactance means for the assemblies respectively, and valve means fitting the barrels and in valving cooperation with the assemblies of the associated barrels.

ELEK K. BENEDEK.

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