US2159245A - Variable displacement pump or motor - Google Patents

Description

y 23, 3 E. K. BENEDEK 2,159,245

VARIABLE DISPLACEMENT PUMP 0R MOTOR Original Filed April 25, 1932 3 Sheets-Sheet 2 May 23, 1939. E. K. BENEDEK VARIABLE DISPLACEMENT PUMP 0R MOTOR Original Filed April 25, 1932 3 Sheets-Sheet 3 9 2 E 8 2 7 5 P L w w 1 M w a Patented May 23, 1939 UNITED STATES PATENT OFFICE Continuation of application Serial No. 607,409, April 25, 1932. This application July 23, 1934,

Serial No. 736,550

12 Claims.

This invention relates to improvements in hydraulic pumps or motors, and has for its particular object the provision of a simplified and more efiicient heavy duty hydraulic machine of the radial piston, sliding crosshead type.

Another object is to provide a large capacity mechanism of this type which will operate efliciently under increased pressures without vibration and without substantial wear.

This application is a continuation of my copending application Ser. No. 607,409, filed April 25, 1932 now Patent No. 2,000,271, granted May 7, 1935. In said copending application the radial pistons are formed with T-shaped crossheads,

comprising two parts which are reciprocably guided in separate one piece guide blocks which are clamped in fixed position ina rotary casing or. drum. Each crosshead has a cylindrical radially facing surface generated on an axis identical with that of the piston carrying block or rotor and a shoe with a complementary surface riding on: the cylindrical crosshead surface so that the shoe is slightly adjustable circumfercntially of the pump (or motor) casing to 2 relieve strain in the event of misalignment of the parts due to slight inaccuracies in machining the parts. The guide blocks have chordal T-shaped .slots open toward the pump or motor axis to receive the crossheads and connecting portions of 30 the pistons proper and are outwardly closed to provide an abutment for the crosshead to resist the hydraulic piston load during the pressure strokes of the pistons. However, the suction forces and the driving forces through the cross- 35 heads, during the suction strokes, are taken up by necessarily narrow ledges at opposite sides of the slots. This is one disadvantage of the said prior structure.

' There is always, of course, some clearance be- 40 tween the relatively sliding surfaces of the guide block and the crosshead unit, and the purpose of the twopart crosshead was to preserve full contact between the crosshead assembly and the relatively stationary guide block for the crosshead 45 whenever the crosshead parts become or tend to become tilted in the guide block due to the relative-reciprocation of the shoe and the guide block.

This tilting, first in one direction and then in another in the constant oil bath of the drum 50 results in maintaining wedge shaped oil films in the clearance spaces, which oil films become positive elements in taking the pressure forces both inwardly and outwardly (the pumping and suction forces) as well as the torque forces neces- 55 sary to drive the drum. The flexible shoes of (Cl. 10316l) the crossheads, however, had a tendency to wedge and waste power and were, moreover, difficult to machine and properly assemble. Furthermore, lubrication of the mating cylindrical surfaces of the crosshead parts was uncertain because none 5 of the operating forces ever tend to separate the two crosshead parts from each other but rather always press the mating surfaces more firmly together during the entire pressure stroke of each piston causing the mating surfaces to I tend to constantly lose lubricant.

Another object of the present invention is therefore the elimination of the flexible shoes of the two part crossheads, and the substitution of crossheads entirely integral with the pistons 15 while obtaining the necessary flexibility by reason of a new cooperative relationship between the crossheads and the individual guide blocks therefor, greatly adding to the strength of the piston actuating assemblies, insuring proper lu- 20 brication, reducing manufacturing cost and reducing the waste of power due to wedging or sticking of the parts in operation.

A further object is the provision of a two part guide block by way of supplanting the two part crosshead for flexibility, which guide block will greatly increase the bearing surface contact between the crosshead and guide, particularly during the suction strokes of the pistons without sacrifice of bearing contact during the pressure strokes.

A specific object is to provide a hydraulic pump or motor of the sliding crosshead type wherein the piston is simplified by having the entire crosshead integral or rigid with the piston proper and which nevertheless operates without noise, vibration or substantial wear on the pistons, crossheads or associated parts.

A still further specific object is to provide a novel crosshead guide block for a radial piston mechanism by which the assembling of the piston and crosshead therewith is facilitated, and

' in which the bearing surface contact between the relatively sliding parts may be increased in keeping with increase in pressures, without sacrifice of efliciency.

A further object is to avoid having to exert excessive clamping forces on the relatively stationary crosshead guide blocks for the piston crossheads to thus reduce distortion of the crosshead guiding surfaces such as would tend to re? duce efllciency and accurate operation of the machine.

A further object is to generally improve a hydraulic mechanism of the type above discussed as will hereinafter appear from the following description relating to the accompanying drawings; in which: a

- Fig. 1 is a substantially horizontal central longitudinal sectional view of one embodiment of the invention (planeindlcated by the line |1i on Fig. 2); Fig. 2 is a transverse sectional view as indicated by the line 2-2 on Fig. 1; Fig. 3 is a partial sectional view taken on the plane of Fig. 2 and showing diagrammatically the manner of operation of the crosshead and guide block arrangement thereof Fig. 4 is a partial sectional view showing one of the crosshead guides and a portion of the supporting adjustable rotary drum or housing therefor, this view being taken on a plane corresponding to that of the upper half of Fig. 1; Fig. 5 is a plan view of the relatively fixed part of the crosshead guide block assembly; Figs. 6 and 7 are sections thereof as indicated respectively by the lines 66 and 7-4 on Fig. 5;-

and Figs. 3 and 9 are diagrammatic side elevations of a complete piston and corresponding relatively movable crosshead guide elements therefor.

Referring particularly to Fig. 1, the principal parts of the mechanism comprise an impeller shaft i, a stationary valve pintle 3, cylinder barrel l4 with cylinder bores l, pistons 9 with crossheads IS, an adjustable rotary crosshead guide support casing or drum l'l surrounding the cylinder barrel, drum adjusting ring 38 with adjusting elements 42 connected therewith as at 4i, and a main housing comprising a central annular part 43 having sliding supports and 5| for the ring 38 and end closure plates 43 and 45 completing the casing. The end plates support the pintle and cylinder barrel in mutually concentric relation and the crosshead guide supporting drum may be shifted from concentric relation (as shown) with the cylinder barrel to eccentric positions at eachside of the cylinder barrel axis (maximum eccentricity determined by abutment of surfaces 39 and 40, Fig. 1) to determine the piston stroke of the mechanism in operation and the direction of flow of fluid through the valves and fluid passages of the machine.

The impeller shafti extends through a central bore 41 in the end plate 45 and is secured in driving relationship to the cylinder'barrel as by afeather key 2, a suitable locking nut 4 being carriedon the shaft abutting one end of the barrel and acting to force a head I of the shaft against a complementary shoulder in a central shaft receiving bore of the barrel. As an. alternative construction the impeller shaft and barrel may be forged from a single piece of metal.

g The cylinder barrel is supported on relatively large antifriction bearings l8 disposed in the end plates 44 and 45 and having inner races l9 shoul- I dered-against and embracing respective ends of the barrel and outer races 2!! shouldered against and fitting the respective end plates in'a manner to rigidly support the barrel for free rotation while preventing axial shifting of the barrel.

The valve pintle 5 has an enlarged diameter portion tightly fitted as at 48 into a central hub portion 49 of the end plate 44 and areduced di ameter portion hydraulically fitting a complementary bore 6 of the barrel. vThe barrel bore is slightly enlarged relative to the reduced diameter The base or web of each block 2| has an elongated opening 23, the, openings receiving the portion of the pintle at l3 so as to avoid contraction of the barrel onto the pintle in the -zone of The cylinder bores 1, through passages 3, communicate with main valve ports l0 and H in-the pintle, the ports having connecting passages in the pintle forming inlet and, outlet ducts for the operating fluid. These may be conventional and are illustrated only in Fig. 2. The pistons 9 may be forged with integral T crosshead formations atl6 these being preferably rectangular in cross section both transversely and longitudinally.

, The casing or drum l'i comprises a split rotary ring. member formed of joined substantially section. The bolts as showndo not clamp the sections together but nevertheless fully align the ,sections, partly by cooperation with the relatively fixed inner crosshead guide blocks 2! which have cylindrical end surfaces (see Figs. 3 and complementary to the cylindrical surfaces of the coupling bolts.

The support for the drum i'i comprises antifriction bearings 34, the inner races 33 of which embrace respective reduced hub portions of the drum, said races axially abutting the drum from opposite directions, the outer races 35 being seated .in'cylindrical recesses in respective retainer' rings 36 and having appropriate shoulders axially abutting the outer races. The retainers 38 are suitably held in axially fixed position in the adjuster ring 38, as by suitable set' screws, not

shown, so that axial separation of the drum sec tions is prevented by the above described abutment of hearing rings and associated parts, without assistance from the bolts 26.

Radial annular space 39 (see Fig. 2) for the crosshead guide elements is provided in the-enlarged central portion of the drum l'i which space also forms an outwardly closed centrifugal reservoir for retaining suflicient operating fluid escaping as slip from between the'pistons. and

The annular space 30 is substantially cylindrical and open toward the rotor as at 30a in Fig. 1, the opening partially embracing, with suitable clearance, a central. enlarged'annular portion of the cylinder barrel from which the pistons extend. Adjacent the inwardopening are cylindrical ledges 30b, coaxial with the bearings 34, the ledges supporting relatively fixed guide blocks 2i which will now be described.

The inner guide blocks 2| are in the form of 'annular' sectors (circular ring sectors) complementary to the space 30, and each is generally channel shaped in transverse cross section, having parallel flanges 25 fitting the side surfaces of the space 3|! and web" or base portions 22 seating on the cylindrical ledges 30b which constitute the outwardly directed working surfaces of the ring sections. The radial end surfaces of the several blocks 2| may abut each other or be slightly spaced (as shown) and the blocks are prevented from movement circumferentially by the bolts 28 as will be seen from Figs. 2 andg3'.

the drum is adjusted for rotation eccentrically of the cylinder barrel). The T-shaped crossheads of the pistons normally rest on the surfaces 24 of the guide blocks 2l as shown in Fig. 2; the side surfaces of the heads being in sliding fit with the inner surfaces of the flange portions 25 of the blocks.

Each crosshead guide assembly is completed by an outer guide block 26 which is substantially segmental in form and rectangular in cross section, the block 26 having its inner tangential surface in sliding abutment with the outer planar crosshead surface, and the annular outer and lateral surfaces of the block being complementary to the annular inwardly directed working surface and side surfaces respectively of the drum space 30 in the zone of thrust of the associated piston, so that the block is free to shift (rock) slightly endwise of itself in said space. Endwise shifting movement of the blocks 26 is limited by the bolts 28 positioned circumferentially between adjacent uide blocks 26 and which the rounded ends of the blocks actually clear by only a few thousandths of an inch, although the clearance shown in Fig. 3 is much greater (for illustration only).

It will be noted that the inner guide blocks 2| are interposed between and serve to space the rotary ring sections independently of the outer guide blocks 26. The inner guide blocks are of a thickness, axially of the pintle, such as to space the ring sections to an extent to provide clearance between the sections and the edges of the cross heads.

The amplitude of the surface 24 which supports the under side of each crosshead is apparent from Fig. 5, and comparison of this surface with the narrow crosshead supporting ledges of my above identified prior Patent No. 2,000,271 is invited.

Fig. 3 illustrates diagrammatically the operation of the mechanism, particularly the operation thereof as a pump. For such operation the drum I! is adjusted eccentrically of the cylinder barrel I4, the respective centers of the drum and cylinder being indicated on Fig. 3 at Ill-62. The drum is driven through the piston crossheads l6 as connecting elements in cooperation with the crosshead guide block elements 22 and 26. There is necessarily some clearance between the radially inwardly and outwardly facing surfaces of the crossheads and the adjacent guide block surfaces and, in taking up this clearance, the drum lags behind the cylinder barrel in rotation, the lag being actually through an angle so small that it could not be illustrated, wherefore it is greatly exaggerated in Fig. 3. Thus the crossheads become tilted in the guides, the tilting being such that the trailing under surfaces of the crossheads rise off the guiding surfaces 24 of the fixed guide blocks 22.

The radial hydraulic pressure forces P on the pistons, see Figs. 8 and 9, urge the radially outward surfaces of the crossheads into correspondingly forcible abutment with the'inner faces of the blocks 26 to thereby drive the drum, and the blocks 26. being free to travel slightly circumferentially are thereby tilted from normal position, indicated at 26' Fig. 3, to respective positions illustrated in full lines, maintaining substantially full facecontact between the crossheads and blocks 26. The perpendicular center lines of one of the blocks 26 in normal and in extreme positions at each'side of the normal position are indicated on Fig. 3 at 51 and 5l-5'I"" respectively, line 51 corresponding to the normal position of the block (26'), 57' corresponding to the position of the block illustrated in full lines, and 51" corresponding to 26".

The relatively forward, e. g., travel of all the blocks 26 on the adjacent circular drum surfaces is limited by abutment between the advancing ends of the blocks and the bolts 28. Rotation of the drum (neglecting the factor of manufacturing errors as to some of the blocks) occurs only after all the blocks have thus contacted with respective coupling bolts. Because there is substantially no tilting between the pistons and cylinders it will be seen that all the crossheads will become operative at once in transmitting the torque forces, notwithstanding the fact that there are no forces tending to urge the pistons below the horizontal center line of the pump outwardly. It will be further seen that as all clearance is taken up between the advancing ends of the blocks 26 and the coupling bolts, the outer crosshead surfaces will now tend to become tilted in the manner illustrated in Fig. 9 and this tilting will cause a wedge-shaped oil film to occur between the crossheads and blocks 26, the wedge spaces diverging in the forward direction of travel of the drum. In the meantime, wedge-shaped hydrodynamic oil films occur between the under or inner surfaces of the crossheads and the surfaces 24 which, as will be seen, are ample to support such film. The wedge-shaped oil films vary in magnitude upon each change of direction of movement of the crossheads relative to the guide block assembly, such changes in direction of travel being observable in Fig. 3. The piston center lines coincide with the centers of the openings 23 of the blocks 22 at the dead center positions of the pistons (on the horizontal line of the pump) and the crossheads travel first in an overunning direction in the guides and then back to initial position during the pressure cycle (from dead center to dead center above the horizontal line) and likewise move to and fro the same amount on the suction cycle but first in an underrunning direction and then an overrunning direction. Upon each change of direction of movement of the crosshead in its guide, tilting of the crosshead tends to occur and does, of course, occur to some extent, the tilting for each change of direction, indicated at 55 and 56, Figs. 8 and 9 being according to these figures, thus maintaining different volumes of oil in the wedge-shaped films for full and active lubrication of all surfaces.

I claim:

1. In a hydraulic mach ne of the class described, a casing, a rotatable cylinder barrel and pistons carried thereby, a relatively eccentric rotatable support surrounding the barrel, valve means for the barrel operatively associated with the piston cylinders, crossheads for the pistons rigid with respective pistons, each crosshead having a radially outwardly disposed planar face, a radially complementary guide block for each crosshead carried by said support and circumferentially adjustable therein and abutment means on the support and positioned circumfcrentially between adjacent guide blocks to be engaged by the guide blocks for limiting the cir- V ripheral surface and the guide blocks include segmental members mounted in face to face sliding contact with the said cylindrical surface.

3. In a hydraulic machine of 'the class described including radial pistons and rigid crossheads therefor, a rotary support, a two part guide block for each crosshead mounted in the support, one part being fixedly secured in the support and the other being circumferentially slidable therein within definite limits, the two cooperating to automatically maintain wedge shaped oil films between them and the crosshead radially inwardly and outwardly of the crosshead respectively.

4. In a hydraulic machine of the radial piston type, a primary and a relatively eccentric sec ondary rotor, a radial set of pistons carried by one rotor and having rigid T-shaped crossheads, an. annular recess in the other rotor, a two part crosshead guide associated with each crosshead and mounted in the annular recess of said other rotor, one part being circumferentially adjustable in the recess and the other being secured in fixed position in said recess.

5. In a machine according to claim 4, the combination wherein the relatively fixed guide part lies radially inwardly from the crossheads with which associated and has an elongated opening closed at each end, the opening receiving the outer end of the piston, said fixed guide part having flanges embracing and laterally guiding the adjustable part outwardly from the crosshead as well as laterally guiding the crosshead during circumferential adjustment of said other part and travel of the crosshead.

6. In a hydraulic pump or motor, a primary rotor having radial cylinders, radial pistons in the cylinders, said pistons having rigid IF-shaped crossheads,. a secondary rotor surrounding the primary rotor and having an annular recess receiving the crossheads, a series of crosshead guide block assemblies in the recess, one assembly for each crosshead, each assembly comprising an ancluding a plurality'of radial piston and cylinder assemblies, each including a piston element and a cylinder element,,the combination of a rotary ring member having an inwardly directed annular working surface; a cross head connected to one element of each of said assemblies; and guiding and force-transmitting means for each cross head comprising an outer guide block formed with an arcuate outer surface having a curvature corresponding to that of the inwardly directed annular working surface of said ring member and engaging said latter surface, the inner surface of said guide block engaging the outer face of said cross head, and inner guide block means connected to said ring member independently of said 1 outer guide block and engaging the inner face of nular sector part adapted. to support and guide I the inner and side faces of the respective crosshead, and a segment part the chordal face of which guides the outer face of the-crosshead, one of said parts being circumferentially fixed in said recess and the other being mounted to float circumferentially in the recess within definite limits for the purposes described.

7. In a hydraulic pump or motor of the type including a plurality of radial piston and cylinder assemblies, each including a piston element and a cylinder element, the combination of a split rotary ring member including two joined sections surrounding said piston and cylinder assemblies; a cross head connected to one element of each of said assemblies, and guiding and force-transmitting means for each cross head comprising outer and inner guide blocks, the outer-guide block engaging said ring member independently of said inner guide block and in the zone of thrust of ,the associated piston and engaging the outer face of said cross head, and

the inner guide block being interposed between and spacing said ring member sections independently of said outer guide block and engaging the inner face of said cross head, said inner guide block being of a thickness such as to space said ring member "sections to an extent to provide clearance between said sections and the edges of said cross heads, and means for clamping said ring member sections and said inner guide block means together.

' 8. In a hydraulic pump or motor of the type insaid cross head.

9. In a hydraulic pump or motor of the typ including a plurality of radial piston and cylinder assemblies, each including a piston element and a cylinder element, the combination of a rotary ring member having an annular working surface; a cross head connected to one element of each of said assemblies; and guiding and force-transmitting means for each cross head comprising outer and inner guide blocks, the outer guide block engaging said ring member independently of said inner guide block and in the zoneof thrust of the associated piston and engaging the outer face of said crosshead, and the inner guide block being arcuately formed to correspond inv curvature with the curvature of the annular working surface of said ring member and engaging the latter surface, said inner guide I block means being connected to said ring member independently of said outer guide blocks and having surfaces engaging the inner faces of said cross heads.

. 10. In a hydraulic pump or motor of the type including a plurality of radial piston and cylinder assemblies, each. including a piston element and a cylinder element, the combination of a rotary ring member having radially spaced inwardly directed and outwardly directed annular working surfaces; a cross head connected to one element of each of said assemblies; and guiding and force-transmitting means for each cross head comprising an outer guide block formed with an arcuate outer surface having a curvature corresponding to that of the inwardly directed annular working surface of saidring member and engaging said latter surface, the inner surface of said guide block engaging the outer face of and a cylinder element, the combination of a rotary ring member having radially spaced inwardly directed and outwardly directed curved working surfaces; atangentially extending cross head connected to one element of each of said assemblies; and guiding and force-transmitting means for each cross head comprising an outer guide block formed with an arcuate outersurface having a curvature corresponding to that of .said cross head, and inner guide block means 2,159,246 the inwardly directed annular working surface of said ring member and engaging said latter surface, and also having a tangential surface engaging the outer face of said cross head, and inner guide block means formed with inner and outer arcuate surfaces having curvatures corresponding respectively to the curvaturesof the inner and outer working surfaces of said ring member and engaging said latter surfaces respectively, said inner guide block means being connected to said ring member independently of said outer guide blocks and being formed with tangential surfaces engaging the inner faces of said cross heads.

12. In a hydraulic pump or motor of the type including a plurality of radial piston and cylinder assemblies, each including a piston element and a cylinder element, the combination of a rotary ring comprising two parts at least one of which is channel-shaped in cross section, the legs of the channel-shaped section providing radialiy spaced inner and outer annular surfaces: 8. cross head connected to one element of each of said assemblies; and guiding and force-transmitting means for each cross head comprising an outer guide block having an outer surface curved correspondingly to and engaging the outer annular surface of said channel-shaped ring part and having an inner surface engaging said cross head, and inner guide means separate from said outer guide block and fitted between and having arcuate surfaces arcuately engaging the legs of said channel-shaped ring part and also having a surface engaging said cross head.

ELIKK. BENEDEK.

Images