US3460481A - Rotor-stator gear set in a hydraulic motor-pump device - Google Patents

Rotor-stator gear set in a hydraulic motor-pump device Download PDF

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Publication number
US3460481A
US3460481A US670915A US3460481DA US3460481A US 3460481 A US3460481 A US 3460481A US 670915 A US670915 A US 670915A US 3460481D A US3460481D A US 3460481DA US 3460481 A US3460481 A US 3460481A
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United States
Prior art keywords
rotor
stator
vanes
walls
ring
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Expired - Lifetime
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US670915A
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English (en)
Inventor
Hollis N White Jr
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Northrop Grumman Space and Mission Systems Corp
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TRW Inc
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C2/00—Rotary-piston machines or pumps
    • F04C2/08—Rotary-piston machines or pumps of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing
    • F04C2/082—Details specially related to intermeshing engagement type machines or pumps
    • F04C2/086—Carter
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C2/00—Rotary-piston machines or pumps
    • F04C2/08—Rotary-piston machines or pumps of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing
    • F04C2/10—Rotary-piston machines or pumps of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of internal-axis type with the outer member having more teeth or tooth-equivalents, e.g. rollers, than the inner member
    • F04C2/103—Rotary-piston machines or pumps of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of internal-axis type with the outer member having more teeth or tooth-equivalents, e.g. rollers, than the inner member one member having simultaneously a rotational movement about its own axis and an orbital movement
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S417/00—Pumps
    • Y10S417/01—Materials digest

Definitions

  • a rotor-stator gear set for a fluid pressure device of the gerotor type which can be used both as a motor and as a pump.
  • the stator includes a stator ring having a plurality of pockets and a corresponding plurality of cylindrical vanes rotatably carried in the pockets for working in gear relation with the rotor to provide alternately expanding and contracting fluid chambers between the stator and the rotor as the rotor moves hypocycloidally within the stator.
  • the diameters of the vanes to provide hydrodynamic oil film spaces between the vanes and the walls of the pockets.
  • the stator ring is made of sintered or cast iron and the walls of the pockets are lined with a thin layer it impervious or oil impenetrable material to ensure the hydro dynamic oil film.
  • the impervious material has a low coefficient of friction and is less hard than is the material of which the vanes are constructed so that high points on the impervious liner are worn off under load.
  • the liner may be made of a sprayed or baked-on fluorocarbon resin or may comprise a copper plate. It the stator ring is made of sintered iron it may be plastic impregnated to render it fluid impervious.
  • This invention pertains generally to the filed of fluid motor-pump units and more particularly to such units which employ stator-rotor gear sets generally referred to in the art as gerotors.
  • Motonpump hydrualic devices of the gerotor type are useful in a variety of applications where low speed, high torque rotary drives are required such as augers, conveyors, vehicle Wheel drives, etc., and comprise an internally toothed or lobed stator and an externally toothed rotor which is positioned eccentrically within the stator.
  • the stator has a greater number of teeth or lobes than does the rotor and as the stator and the rotor are rotated relative to one another the rotor moves through a hypocycloidal curve to form alternately expanding and contracting chambers between each pair of adjacent teeth of the internally toothed stator and each tooth of the rotor.
  • stator and the rotor because of the peculiar construction and operation of gerotor type gear sets the machining operations of the stator and the rotor heretofore required very close tolerances which, of course, increased the cost of production. Furthermore because of the substantial pressures to which the gerotor may be subjected the stator and the rotor were generally made of metal having high strength characteristics but also having relatively high coefficients of friction, thereby increasing the power losses within the gerotor as well as increasing the operating temperature and the heat transferred to the fluid operating or being pumped by the gerotor.
  • An object of the present invention is not only to improve the operating and performance characteristics of gerotors but also to reduce the production costs by minimizing difficult close-tolerance machining of the stator and by utilizing materials of construction which improve the manufacturing costs.
  • the present invention may be summarized as comprising a hydrostatic device of the gerotor type including a rotor and a stator wherein the stator comprises a stator ring having an inner peripheral wall, a plurality of fragmentally cylindrically shaped walls opening to the inner peripheral Wall and forming a corresponding plurality of radially spaced pockets and a corresponding plurality of cylindrically shaped vanes providing teeth or lobes carried in the pockets for cooperating in gear relation with the teeth of the rotor.
  • the diameters of the pocket walls are larger than the diameters of the vanes whereby the vanes are journalled for rotation within the pockets and whereby a hydrodynamic oil film space is provided between the walls of the pockets and the vanes as the rotor moves hypocycloidally within the stator.
  • the rotor engages and makes actual contact only with those vanes situated on one side of a diametrical line which intersects the axis of the rotor moves hypocycloidally in the stator.
  • the remaining vanes are engaged by the rotor and a torque applied by the rotor to the engaged vanes rotates these vanes within their respective pockets, thereby substantially reducing friction losses between the teeth of the rotor and the vanes.
  • the present invention also features novel combinations of materials of construction to further reduce friction losses, to increase performance, to reduce wear and to lengthen the useful life of the device.
  • the vanes are made of metal of a given hardness and the walls of the pockets which journal the vanes are lined with a thin layer of material which not only has a low coeificient of friction but which has a hardness less than the hardness of the vanes whereby high points formed on the pocket walls will wear off under load and the contours of the pocket Walls will conform to the contours of the vanes.
  • the pocket liner material may be metal such as copper or may be plastic such as fluorocarbon resin, both of which have a low coefiicient of friction and both of which are impervious to maintain the hydrodynamic oil film between the vanes and the walls of the pockets.
  • the stator ring may be formed in a molding operation using cast iron or may be sintered iron formed in a stamping and sintering operation as will be understood by those skilled in the art. In the latter construction the sintered iron may be plastic impregnated to render the stator ring impervious and to prevent dissipation of the hydrodynamic oil film between the pocket walls and the vanes.
  • FIGURE 1 is an elevational view of a gear set of the gerotor type for functioning as a fluid pump or as a fluid motor and constructed in accordance with the principles of the present invention.
  • FIGURE 2 is a greatly enlarged and fragmentary crosssectional view of one embodiment of a stator vane and an adjacent portion of the stator ring.
  • FIGURE 3 is similar to FIGURE 2 but illustrates another embodiment of the invention.
  • a fluid pressure device comprising a gear set of the gerotor type for functioning as a fluid pump and as a fluid motor and constructed in accordance with the principles 3 of the present invention is indicated generally at reference numeral in FIGURE 1.
  • the device 10 may be more particularly characterized as comprising an internally toothed stator 11 and an externally toothed rotor 12.
  • the teeth or lobes of the rotor 12 comprise convexlyshaped portions 13 angularly spaced about a central axis of the rotor and separated by concavely-shaped portions formed in an outer wall 16 of the rotor.
  • the teeth of the stator 11 comprise a plurality of angularly spaced cylindrically shaped members or vanes 17 which are housed in a corresponding plurality of fragmentally cylindrically shaped walls forming recesses or pockets 18 opening to an inner peripheral wall 19 of an annularly shaped stator ring member 20.
  • the number of teeth of the rotor 12 is preferably one less than the number of teeth of the stator 11. In the embodiment illustrated the rotor 12 has a total of six teeth while the stator 11 has one more than the rotor or seven teeth.
  • the axis of the rotor 12 is eccentrically disposed with respect to a central axis of the stator 11 and as the rotor 12 is rotated relative to the stator 11 the rotor teeth 13 mesh with the stator teeth or vanes 17 to impart a hypocycloidal path of movement to the rotor 12 whereby it orbits about the central axis of the stator six times, corresponding to the number of teeth of the rotor 12, for each revolution of the rotor 12.
  • the device 10 When the device 10 is being utilized as a fluid motor means are provided for communicating the expanding fluid chambers to a source of pressurized fluid and the contracting chambers are communicated with a discharge or an outlet opening.
  • the expanding chambers When the device 10 is being utilized as a pump the expanding chambers are placed in communication with a fluid inlet and the contracting chambers comprise the high pressure chambers and are placed in communication with a pump discharge or outlet opening.
  • Suitable means for communicating the fluid chambers alternately and successively with the fluid inlet and outlet openings are known in the art and are disclosed, for example, in Hollis N. White, Jr. et al. US. Patent No. 3,288,034.
  • the externally toothed rotor 12 is described herein as being rotatable within and orbitally movable relative to the internally toothed enveloping stator 11, either member can be fixedly arranged relative to the other. Furthermore, one member can be arranged to rotate only while the other member orbits only, as will be understood by those skilled in the art. Thus the rotor 12 may be a fixed member and the stator 11 a movable member as desired.
  • the teeth 13 and the interconnecting arcuately shaped surface 14 of the rotor 12 and the vanes 17 of the stator 11 are constructed and arranged so that the rotor 12 only contacts those of the vanes 17 which are disposed on one side of a diametrical line which intersects the central axis of the rotor 12 as well as that particular chamber, such as chamber 21a in the arrangement of parts shown in FIGURE 1, which has contracted to its minimum volume.
  • a diametrical line is indicated in broken lines at reference numeral 22.
  • the vane 17 will rotate counterclockwise due to the vane action. Vanes adjacent to chambers 21b, 21c and 21d will rotate if the device is being used as a motor. Vanes adjacent to the chambers 21g, 21 and He will rotate if the device is being used as a pump.
  • the diameters of the pocket or recess walls 18 are greater than the diameters of the vanes 17, as a consequence of which the vanes are capable of moving slightly not only toward the axis of the stator ring 20 but from side to side.
  • the teeth 13 of the rotor 12 are constructed and arranged to permit such movement of the vanes as the rotor 12 rotates and orbits within the stator 11 and as a consequence the peripheral surfaces of the vanes 17 are urged slightly away from the pocket walls 18 by the pressure of the operating fluid such as oil, thereby providing a hydrodynamic oil filrn between the vanes 17 and the pockets 18.
  • the film not only increases the performance characteristics of the device 10 by reducing the frictional forces between the vanes and the pockets and thus reducing the power losses of the rotor 12, but also by reducing wear and increasing the overall operating life of the device 10.
  • stator ring 20 is formed of cast iron in a casting operation or is formed of sintered iron in an operation involving the process of compacting powdered metal in a die under pressure and then heating the pressed powder in a sintering operation. Both of these manufacturing techniques are known and understood by those skilled in the art.
  • FIGURES 2 and 3 are greatly enlarged representations of that portion of a vane 17 and of the stator ring 20 encircled in the dot-dashed line indicated at reference numeral 26 in FIGURE 1.
  • FIGURE 2 illustrates an embodiment of the present invention utilizing a cast iron stator ring 20 whereas in FIGURE 3 the stator ring is made of sintered iron.
  • the pocket walls 18 are lined with a thin layer of another material such as plastic or copper.
  • the purposes of the liner are at least threefold: (1) to obviate close machining of the pocket walls 18 in order to have good bearing surfaces for the vanes 17; (2) to increase performance of the hydrostatic device 10 by reducing frictional losses between the vanes 17 and the stator ring 20 and (3) to maintain the hydrodynamic oil film between the adjacent peripheral walls of the vanes 17 and the pocket Walls 18.
  • the liner or coating of material applied to the pockets of the cast or sintered iron stator rings 20 is constructed of material having a hardness which is less than the hardness of the metal vanes 17 whereby irregular contours and high points of the liner are smoothed under the load of the vane to conform to the vane contour.
  • the liner material is also chosen because of its low coeflicient of friction, thereby reducing frictional forces and wear of the liner.
  • the liner material is impervious to fluid as a consequence of which the hydrodynamic oil film between the vanes 17 and the pocket walls 18 mentioned hereinabove is sustained.
  • FIGURE 2 the material of which the stator ring 20 is constructed is cast iron and the extremities of the pocket wall formed in the stator ring 20 and facing the metal vane 17 are indicated at reference numerals 18a.
  • the liner material which covers the cast iron and which forms the bearing surface for the vane 17 is indicated at reference numeral 27.
  • the liner material 27 is plastic fluorocarbon resin.
  • Fluorocarbon resins are classified as thermoset-plastics, and are chemically analogous to the polyolefins, but with some or all of the hydrogen atoms replaced by fluorine atoms.
  • Fluorine substitution generally contributes to: (1) chemical inertness; (2) resistance to high and low temperatures; (3) essentially zero moisture absorption; (4) low coeflicient of friction; (5) non-flammability and (6) weather and oxidation resistance.
  • polytetrafluoroethylene whose basic unit consists of two carbons with fluorine fully substituting for hydrogen, represents one class of fluorocarbon resin which is supplied by E. I. du Pont de Nemours & Co., Inc., under the trade name Teflon and by Allied Chemical Corporation under the trade name Halon.
  • Polymeric fluorinated ethylene propylene a copolymer of polytetrafluoroethylene and hexafluoropropylene, is also supplied by E. I. du Pont de Nemours & Co., Inc., under the trade name Teflon F -E P.”
  • Polymeric chlorotrifluoroethylene is another resin which, in a strict sense, might be referred to as a chlorofluorocarbon, however, typical of a material in this case is that supplied by Minnesota Mining and Manufacturing Co., under the trade name KEL-F8l. Copolymers of that type modified with small amounts of vinylidene fluoride and other fluorine containing monomers to improve processability are also available.
  • Such resins include the materials supplied by Allied Chemical Corporation under the trade name Plaskon as well as KEL- F82 supplied by Minnesota Mining and Manufacturing Co.
  • polyvinylidene fluoride is another resin supplied by Pennsalt Chemical Corp. under the trade name Kynar.
  • the liner material is indicated at reference numeral 27a and in this embodiment is made of copper which has been plated to the stator ring 20.
  • the material of which stator ring 20 is constructed in FIG- URE 3 is sintered iron but the principles of the present invention also contemplate the application of copper plate to cast iron.
  • the liner of plastic fluorocarbon resin indicated at reference numeral 27 in FIGURE 2 and the liner of copper plating indicated at reference 27a in FIGURE 3 can both be applied to either the cast iron stator ring indicated at 20a in FIGURE 2 v6 or the sintered iron stator ring indicated at 20a in FIG- URE 3.
  • the hardness of the vane 17 is greater than the hardness of the copper plate 27a the surface of the copper will smooth under load to conform to the contour of the vane 17.
  • one of the salient characteristics of copper is its low coefficient of friction and it is, of course, impervious to fluids whereby the hydrodynamic oil film between the liner 27a and the vane 17 is maintained.
  • stator ring 20 is constructed of cast iron, because of the imperviousness of cast iron the oil film is sustained between the walls of the vanes 17 and the pockets 18 since the oil cannot leak out of the chambers 21a-21g through the body of the stator ring 20.
  • the present invention contemplates an impregnation of the sintered iron stator ring 20a with plastic, thereby rendering the ring 20a, including peripheral wall 19 which partially forms the chambers 21a- 21g, impervious to the oil and ensuring the maintenance of oil in the chambers 21a-21g and of the hydrodynamic oil film between the vanes 17 and the pockets 18.
  • a fluid pressure device comprising a gear set having a pair of relatively movable internally and externally toothed members
  • said internally toothed member comprising a ring having an inner peripheral wall
  • vanes carried in said recesses and cooperating in gear relation with said externally toothed member, said vanes being slightly undersized with respect to said recesses for providing a hydrodynamic oil film between the walls thereof and being rotatable and slightly radially sbiftable in said recesses for movement in response to operation of said gear set, the walls of said recesses being lined with bearing material having a lower coeflicient of friction than said ring, having a hardness less than said vanes and being impervious to oil.
  • fluorocarbon resin is selected from a class consisting of polytetrafluoroethylene, polymeric fluorinated ethylene propylene, polymeric chlorotrifluoroethylene and polyvinylidene fluoride.
  • a fluid pressure device comprising a gear set having a pair of relatively rotatably and orbitally movable internally and externally toothed members
  • said internally toothed member comprising a ring having an inner peripheral wall
  • said ring being constructed of plastic impregnated oil impervious sintered iron, References Cited the walls of said recesses being lined with bearing mate- UNITED STATES PATENTS rial having a lower coefficient of friction than said 2 345 975 4/1944 Herman sintered iron ring.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Rotary Pumps (AREA)
  • Details And Applications Of Rotary Liquid Pumps (AREA)
  • Hydraulic Motors (AREA)
US670915A 1967-09-27 1967-09-27 Rotor-stator gear set in a hydraulic motor-pump device Expired - Lifetime US3460481A (en)

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US67091567A 1967-09-27 1967-09-27

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US670915A Expired - Lifetime US3460481A (en) 1967-09-27 1967-09-27 Rotor-stator gear set in a hydraulic motor-pump device

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US (1) US3460481A (enrdf_load_stackoverflow)
DE (1) DE1653922C3 (enrdf_load_stackoverflow)
FR (1) FR1554495A (enrdf_load_stackoverflow)
GB (1) GB1163490A (enrdf_load_stackoverflow)
SE (1) SE328776B (enrdf_load_stackoverflow)

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3591320A (en) * 1969-04-08 1971-07-06 George V Woodling Pressurized roller means in a fluid pressure device
US3614274A (en) * 1969-06-19 1971-10-19 Danfoss As Hydraulic rotary piston machine
US3622254A (en) * 1969-06-20 1971-11-23 Precision Scient Co Pump
US3687578A (en) * 1970-09-04 1972-08-29 Trw Inc Hydraulic pump motor
US3778201A (en) * 1972-03-23 1973-12-11 Davey Compressor Co Compressor blade
US3860367A (en) * 1973-08-24 1975-01-14 Ford Motor Co Controlled porous coating for rotary engine side housing
US3871798A (en) * 1972-12-02 1975-03-18 Danfoss As Rotary and orbiting piston machine with internal shaft
US4008015A (en) * 1975-11-03 1977-02-15 Eaton Corporation Rotor-stator gear set
US4456436A (en) * 1976-08-24 1984-06-26 Robert Bosch Gmbh Rotary fuel supply unit with matched materials for the rollers and running track
WO2000025974A1 (fr) 1998-10-29 2000-05-11 Sumitomo Heavy Industries, Ltd. Procede de fabrication d'une bague de retenue de goupilles pour$i( )roue interieure, structure engrenage planetaire engrenee interieurement, et moteur et pompe hydrauliques
US6619937B2 (en) 1999-12-20 2003-09-16 Sauer-Danfoss Holding A/S Hydraulic machine
US6802244B1 (en) 2003-04-25 2004-10-12 Sauer-Danfoss, Inc. Hydrostatic cylinder block and method of making the same
US20070253855A1 (en) * 2006-04-27 2007-11-01 Hitachi, Ltd. Pump Apparatus and Power Steering
DE102007015626A1 (de) 2007-03-27 2008-10-02 Sauer-Danfoss Aps Hydraulische Maschine
US20080247896A1 (en) * 2007-04-09 2008-10-09 United Technologies Corporation Fluoropolymer-containing films for use with positive-displacement fluid pumps
US20100028186A1 (en) * 2006-10-06 2010-02-04 Sauer-Danfoss Aps Hydraulic machine

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2345975A (en) * 1938-12-24 1944-04-04 Vickers Inc Power transmission pump or motor
US2586964A (en) * 1946-09-24 1952-02-26 Jr Frederick Kraissl Rotary pump
US2619040A (en) * 1949-03-15 1952-11-25 Maisch Oliver Liquid measuring and dispensing pump
US2815718A (en) * 1952-07-24 1957-12-10 Gen Electric Ball piston type fluid transmission
US3289602A (en) * 1965-09-03 1966-12-06 Trw Inc Fluid pressure device
US3389618A (en) * 1966-05-11 1968-06-25 Char Lynn Co Torque transmitting device

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB591143A (en) * 1944-07-20 1947-08-08 Robert Edison Edouard Jessop Improvements in or relating to rotary roller-vane pumps
DE1035415B (de) * 1953-01-23 1958-07-31 Glacier Co Ltd Gleitlager
GB795204A (en) * 1955-07-20 1958-05-21 Emi Ltd Improvements in or relating to rotary oil vacuum pumps
US3004333A (en) * 1957-06-18 1961-10-17 Clevite Corp Bearing and method of making same

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2345975A (en) * 1938-12-24 1944-04-04 Vickers Inc Power transmission pump or motor
US2586964A (en) * 1946-09-24 1952-02-26 Jr Frederick Kraissl Rotary pump
US2619040A (en) * 1949-03-15 1952-11-25 Maisch Oliver Liquid measuring and dispensing pump
US2815718A (en) * 1952-07-24 1957-12-10 Gen Electric Ball piston type fluid transmission
US3289602A (en) * 1965-09-03 1966-12-06 Trw Inc Fluid pressure device
US3389618A (en) * 1966-05-11 1968-06-25 Char Lynn Co Torque transmitting device

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3591320A (en) * 1969-04-08 1971-07-06 George V Woodling Pressurized roller means in a fluid pressure device
US3614274A (en) * 1969-06-19 1971-10-19 Danfoss As Hydraulic rotary piston machine
US3622254A (en) * 1969-06-20 1971-11-23 Precision Scient Co Pump
US3687578A (en) * 1970-09-04 1972-08-29 Trw Inc Hydraulic pump motor
US3778201A (en) * 1972-03-23 1973-12-11 Davey Compressor Co Compressor blade
US3871798A (en) * 1972-12-02 1975-03-18 Danfoss As Rotary and orbiting piston machine with internal shaft
US3860367A (en) * 1973-08-24 1975-01-14 Ford Motor Co Controlled porous coating for rotary engine side housing
US4008015A (en) * 1975-11-03 1977-02-15 Eaton Corporation Rotor-stator gear set
US4456436A (en) * 1976-08-24 1984-06-26 Robert Bosch Gmbh Rotary fuel supply unit with matched materials for the rollers and running track
EP1046456A4 (en) * 1998-10-29 2009-02-18 Sumitomo Heavy Industries METHOD FOR MANUFACTURING A PEN RETAINING RING FOR $ I () INTERNAL WHEEL, INTERNALLY ENHANCED PLANETARY GEAR STRUCTURE, AND HYDRAULIC MOTOR AND PUMP
WO2000025974A1 (fr) 1998-10-29 2000-05-11 Sumitomo Heavy Industries, Ltd. Procede de fabrication d'une bague de retenue de goupilles pour$i( )roue interieure, structure engrenage planetaire engrenee interieurement, et moteur et pompe hydrauliques
US6619937B2 (en) 1999-12-20 2003-09-16 Sauer-Danfoss Holding A/S Hydraulic machine
US6802244B1 (en) 2003-04-25 2004-10-12 Sauer-Danfoss, Inc. Hydrostatic cylinder block and method of making the same
US20070253855A1 (en) * 2006-04-27 2007-11-01 Hitachi, Ltd. Pump Apparatus and Power Steering
US7722342B2 (en) * 2006-04-27 2010-05-25 Hitachi, Ltd. Pump apparatus and power steering
US20100028186A1 (en) * 2006-10-06 2010-02-04 Sauer-Danfoss Aps Hydraulic machine
DE102007015626A1 (de) 2007-03-27 2008-10-02 Sauer-Danfoss Aps Hydraulische Maschine
US20080240966A1 (en) * 2007-03-27 2008-10-02 Sauer-Danfoss Aps Hydraulic machine
US20080247896A1 (en) * 2007-04-09 2008-10-09 United Technologies Corporation Fluoropolymer-containing films for use with positive-displacement fluid pumps
US8047825B2 (en) * 2007-04-09 2011-11-01 United Technologies Corporation Fluoropolymer-containing films for use with positive-displacement fluid pumps

Also Published As

Publication number Publication date
GB1163490A (en) 1969-09-04
DE1653922A1 (de) 1972-02-10
SE328776B (enrdf_load_stackoverflow) 1970-09-21
DE1653922B2 (de) 1980-11-20
DE1653922C3 (de) 1981-07-02
FR1554495A (enrdf_load_stackoverflow) 1969-01-17

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