US3548715A - Compound hydraulic machine - Google Patents

Description

0 United States Patent 1111 3,548,715

[72] Inventor Gerhard Bobs! [56] References Cited w. Switzerland UNITED STATES PATENTS P 1,083,329 1/1914 Lancia.... 103/126 [221 med d 1970 1,870,192 8/1932 Butler..... 103/126 [453 v AG 1,927,395 9/1933 Edwards. 103/126 Asslgn g and 2,212,994 8/1940 Vrolix 103/126 3 2,218,406 10/1940 Orshansky. 103/162 2,312,417 3/1943 Jones 103/162 [321 Pmmy 1 2,817,953 12/1957 13 11111.. 103/162 [331 f'gs 2,936,716 5/1960 Looker 103/11 3,065,700 11/1962 Blelke 103/162 FOREIGN PATENTS 1,261,092 4/1961 France 103/162 Primary Examiner-William L. Freeh 541 COMPOUND HYDRAULIC MACHINE Y- & Fflshauf 6 Claims, 5 Drawing Figs. [52] US." l/6 ABSTRACT: An auxiliary low-pressure pump unit is con- 4 /206 (DiScl0S r L4l7/244: 9l/49Q 311g nected to a high-pressure pump, or hydraulic motor unit to 417/ 9? prevent cavitation effects at high speed; the auxiliary unit is a [51] Int. Cl. .,F04b 23/08, gear pump, both pump units are located in the same housing F04b 23/ l 2, F04b U07 and one of the gears of the gear pump is directly mounted on a [50] Field of Search l03/l02; rotating element of the high-pressure unit, for example on a rotating cylinder or other rotating element thereof.

PATENTEU 05622 I970 3.548 715 SHEETl or 2 Fig.1

16 I5 I4 /7 I312 27 28 INVENTOR GEZIIWBD 30557 BY We 14 ATTORNEY PATENTEU [15222 I976 SHEET 2 OF 2 COMPOUND HYDRAULIC MACHINE The present invention relates to hydraulic machines, which, for purposes of this application, are defined as hydraulic apparatus which can act both as a pump or as a hydraulic motor unit. In particular, the application is directed to hydraulic machines having a cylinder and piston assembly, in which a plurality of cylinder bores are located around an axial shaft, and the pistons are slidable therein and connected to a wobble plate. A low-pressure gear pump is in driving connection with the high-pressure hydraulic machine unit, so that a compound machine is obtained.

Rotary hydraulic machines, and in particular rotary hydraulic pumps of the multiple parallel piston type are frequently operated at-such speeds that the hydraulic fluid can no longer be completely sucked into the cylinders at the low-pressure side of the pump, to completely fill the cylinder. Additionally, upon interruption of flow, the well-known under-pressure effects and noise due to cavitation will result. Pumps of this type are usually, therefore, supplied with fluid at an initial pressure of a few atmospheres at their low pressure side. The pressure for this low-pressure supply is usually obtained by means of gear pumps or similar displacement pumps, combined in a suitable manner with the hydraulic apparatus. Usually, such an auxiliary pump, also referred to as a supply, or feed pump, is located outside of the housing of the main pump and secured thereto. Occasionally, the feed pump will be entirely separate of the hydraulic machine. The drive'to the feed pump is usually on the same power shaft as that of the main or highpressure hydraulic machine (operating either as a pump, or as a motor). It may be driven directly from the same shaft, or from a branch drive connected to the power shaft. Such additional drive arrangements require additional material and adjustment costs, thus making the entire unit more expensive.

It is an object of the present invention invention to provide an integrated compound unit not requiring specifically ar ranged separate drive elements for an auxiliary, or feed pump in connection with a hydraulic machine.

Subject matter of the present invention: Briefly, the auxiliary low-pressure unit is a gear pump, having at least one gear directly mounted, internally of the high-pressure machine, on a rotating element of the high-pressure unit, for example on a rotating element of the machine unit itself, or on the drive shaft therefor; both the gear pump unit and the high-pressure unit are located in the same housing to avoid additional special fluid conduit connections.

Embodiments of the invention will be described by way of example with reference to the accompanying drawings, wherein:

FIG. 1 is a longitudinal cross-sectional view through a compound hydraulic machine in accordance with the present invention;

FIG. 2 is a cross-sectional view at right angles to FIG. 1;

FIG. 3 is a longitudinal sectional view of a different embodiment;

FIG. 4 is a partial cross-sectional view, at right angles to the view of FIG. 3; and

FIG. 4a is a partial cross-sectional view of an auxiliary pump body using a hollowshaft to serve, simultaneously, as a duct and attachment of the body.

Referring now to the drawings, and more particularly to FIGS. 1 and 2: A pair of wobble plate type hydraulic machine units 1, 2, are located in a housing adjacent each other. The housing has a bottom part 3, an end plate 4 and a cover plate 5. Each one of the hydraulic machines 1, 2, which may operate as pumps or as hydraulic motors, are provided with a shaft 6, supported in the front portion of housing unit 3 in a roller bearing 7, and in the end plate 4 of the housing in sleeve bearing 8. The bore 9 in the front of housing 3 is closed off by means of a cover 10, supplied with the usual elastic seals to close off the shaft 6 from the interior of the housing. Such seals are not shown nor further described in detail since they are well known in the art.

Each one of the hydraulic machines, themselves, includes a control plate 11, having notches or grooves therein which communicate with control bores 12 of a rotating cylinder 13. Cylinder 13 has a group of parallel, axially extending bores arranged therein, circumferential around shaft 6 (as best seen in FIG. 2) in which pistons 14 are slidable. The pistons 14 engage, by means of a ball joint and glide track 15 a wobble plate 16. The track 15, or the entire wobble plate l 6 is inclined with respect to the axis of the shaft so that the pistons, upon rotation of the cylinder, will move back and forth in the cylinder bores.

Each of the two cylinders has a gear 17, 18,-secured thereto, the gears of the two cylinders being in meshing engagement. Gears i7, 18 are partly closed off by a pump body unit 19, located within the housing of the compound machine. As best seen in FIG. 1, housing 19 may either by a single unitary element or consist of a central part 20 and sidewalls 21, 22

secured together by screws-23. Body 19 is so made that one section thereof just covers the teeth of gears 17, 18, and a portion of the sidewalls 21,22 closes off the gears at their side faces (see FIG. 1). A space 24 is formed by the gears 17, 18 and housing 19, to which a duct 25 is connected which terminates in a duct formed in the end plate 4..

The two gears 17, 18 must be exactly aligned, and at least one of the hydraulic machine units therefore is preferably axially adjustable or the location of cover plate 10 is so arranged that the two gears mesh exactly and are in exact side alignment.

Body 19 itself is secured within the housing of the compound hydraulic machine by means of a bolt 26, and is slidable axially (that is, in FIG. 1 left and right) thereon for self-alignment with the gears.

In an alternative construction, bolt 26 may be replaced by a hollow bolt, and a connection formed from chamber 24 to the interior of the hollow bolt. in this case, the hollow bolt will supply, or conduct off fluid similar to duct 25.

FIG. 4a illustrates the alternative construction, wherein a hollow bolt 56, having a slit formed therein, communicates by means of a channel 55 with chamber 24. The other end of the bolt 56 may likewise be slit, or communicate directly with a duct in end plate 4 through the axial opening.

Gears l7 and l8,and body unit. 19 together form a gear pump. When the housing is filled with hydraulic fluid, the two hydraulic machines will rotate in the-direction of arrows 27, 28 (FIG. 2) and fluid will be conducted into the space formed by chamber 24, and from then on through duct 25 in the end plate 4. From end plate 4 the fluid, undersome pressure, can

be conducted to any utilization connection, or the end plate 4 may itself serve for interconnecting channels formed or cut therein to supply the various cylinders in the hydraulic machines.

If both gears are secured to the outside of the cylinders, then only one of the shafts 6 need operate as a power shaft, that is to supplypower to, or take power from the hydraulic machines. Gears 17, 18, then transfer power to the hydraulic machine unit which is not driven (or does not supply rotary power to a utilization device), so that gears l7, 18 will have a dual function of drive and hydraulic pump.

If the hydraulic machine units rotate in directions opposite to arrows 27, 28, then the interior of the housing itself will become the pressure unit for the feed pump, and the space 24 the supply, or inlet duct. In this case, the housing, and its seals must be so formed that the resulting pressure will not cause leaks.

The two units of the hydraulic machines may form a hydraulic drive, in which the speed of the unit operating as a pump may be different from the speed of the unit operating as a hydraulic motor. Thus, the two gears 17, 18 may no longer be fixed to the cylinder units and restrained from relative rotation with respect thereto. If, for example, gear 18 surrounds the cylinder unit which operates as a hydraulic motor, then gear 18 will be fixed over cylinder unit 13 so as to be rotatable therewith. When the pump unit, that is the unit with gear 17, is driven at a given speed, the gear 17 will drive gear 18 with the speed determined by the ratio of the gears themselves. The speed of the hydraulic motor, however, will depend on the volume of hydraulic fluid supplied by the unit forming the pump and, if the volume of supply is changeable (for example by changing the inclination of the slide track 15 or the wobble plate 16), then the speed of the motor may itself change correspondingly, for example between zero and a maximum value depending on design. The absolute speed between gear 18 and the cylinder element of the unit functioning as a hydraulic motor will then be the difference or, respectively, the sum (depending on direction of rotation) of the speed of the gear 18 as determined by the driving speed of the pump unit and the speed of the hydraulic unit functioning as a motor.

In the construction of H65. 1 and 2, the cylinder unit is driven, the wobble plate remaining stationary. FIGS. 3 and 4 illustrate a construction in which the cylinder unit is arranged with its central axis at an inclination with respect to the power shaft, with power driven pistons. The housing is formed of a central portion 31, a front cover 29 and a rear cover 30. Power shaft 32 is rotatably journaled in front cover 29 and further in an intermediate wall 33 located in central housing part 31. A drive disc 34 has pistons 36 connected thereto by piston rods 35, terminating in wall joints (not specially shown and well known). The rotating cylinder 37 is journaled in a swingable retainer 38 formed with the fluid supply grooves therein, cooperating with the bores of the cylinder unit 37. The ducts, the arrangement of which is also known in the art, are located coaxial with retaining unit 38, connection to the supply ducts (not shown) being over the duct 39 shown in broken lines.

The portion of the drive shaft 32 lying between walls 29 and 33 is utilized for the auxiliary or feed pump. Gear 40 is secured, in driving engagement, to shaft 32, to rotate therewith, and to mesh with a second gear 41, journaled within gear body 42. Gear body 42 (FIG. 4) comprises a central portion 43, as well as a pair of sidewalls 44, 45, snugly surrounding the faces of gears 40, 41. Body 42 is secured between walls 29 and 33 by a bolt 46, to be axially movable for self-alignment. Gears 4t), 41 together with body 42 form a space or chamber 47 (FIG. 4) to which a hydraulic line 48 is connected. Space 47 forms the pressure chamber of the gear pump formed by gears 40, 41 and body 42, when the gears rotate in the direction of the arrows 49, 50. Fluid under pressure is conducted over line 48 to the high-speed, high-pressure main hydraulic unit, or provides an additional, low-pressure removal of hydraulic fluid when the main unit is operating as a motor.

Various modifications may be made in the compound hydraulic machine of the present invention. For example, the unit as illustrated in FIGS. 1 and 2 can be so arranged that an intermediate gear is located between two adjacent hydraulic machine units. This will then result in a gear pump having three gear elements. A pair of gear pump bodies 19 must then be used, each one forming with a pair of gears a respective pressure and suction region. A pair of connecting conduits 25 must then also be used, which, for example, may be joined together in the bottom plate 4 of the housing. More than one additional intermediate gear can, of course, be used, each one pair of gears being furnished with its own housing to form a pressure and fluid supply region.

if individual high-pressure hydraulic machine units, located adjacent each other, are to be individually driven, then the gear rings of one of the units must be rotatable with respect thereto in order to enable individual drive of the separate hydraulic machine units.

Use of the hydraulic machine, in accordance with the present invention, as a pump causes reactions to the housing 19 (or, 42, respectively) due to the pressure of the hydraulic fluid and due to the torque of the gears themselves. Such reactive forces can readily be absorbed byimechanical reinforcements and hydraulic seals.

The present invention has been described with specific reference to rotary axially extending wobble plate type piston pumps, designed for high-speed operation; various changes and modifications may be made within the inventive concept to accommodate design requirements.

lclaim:

1. Compound hydraulic machine comprlsingan enclosed housing; v

at least a pair of rotary cylinder-wobble plate-type highpressure pump elements 13, 14, 15, 16 located within said housing; I

a gear 17 directly mounted on the outside circumference of the cylinder 13 of at least one of said pump elements;

a second gear 18 located within saidenclosed housing and in meshing engagement with said first gear 17;

a pump body 19; 20, 21, 22, 23 located within said enclosed pump housing and at least partly enclosing the gear 17 secured to said cylinder 13 of at least one of the pump elements, and said second gear, said pump body overlapping the side faces of said gears, at least in part;

duct means 25, 24 connected to said gear body 19 conducting fluid pumped from the space within the enclosed housing, under pressure, upon rotation of said cylinder and thus said gears; and

a power shaft 6 passing through said housing transmitting power to, or from said machine and connected to at least one of said pump elements.

2. Hydraulic machine according to claim 1, wherein said machine comprises at least two high-pressure units having their central axes located parallel to each other, one of said units, only, having an element in direct driving engagement with said shaft, each said units having a gear mounted on a corresponding element, said gears forming the gears of said gear pump and simultaneously providing for transfer of rotary power.

3. Hydraulic machine according to claim 2, wherein the gear on the unit not directly connected to said power shaft is rotatable with respect to the element on which it is mounted, whereby said element and said gear may operate at different speeds.

4. Hydraulic machine according to claim 1, wherein said machine comprises at least two high-pressure units located adjacent each other and having their central axes parallel to each other; the outside of each cylinder assembly element being formed with a gear ring meshing a gear ring of an adjacent unit, said gear rings forming the gears of said gear pump and simultaneously providing for transfer of rotary power between said units.

5. Hydraulic machine according to claim 1 wherein said pump body separates the suction side from-the pressure side of the gear pump formed by said meshing gears, said pump body being supported within the housing and being axially moveable with respect to said cylinder carrying said gear, to provide for self-alignment of said pump body with respect to the rotary cylinder of the high-pressure pump element.

6. Hydraulic machine according to claim 1 wherein said pump body separates the suction side from the pressure side of the gear pump formed by said meshing gears, said pump body being formed with a differential pressure chamber 24; a hollow shaft 56 supporting said pump within said housing, the interior of said 56 shaft being in fluid communication 57,56 with said chamber 24 whereby said shaft will simultaneously support said housing and serve as fluid conduit.

Images