Hydraulic motors

Abstract

Claims

1. A HYDRAULIC MOTOR COMPRISING A STATIONARY CASING, RADIALLY EXTENDING CYLINDERS PROVIDED IN SAID CASING, A CENTRAL CHAMBER IN SAID CASING, SAID CYLINDERS BEING CLOSED OUTWARDLY AND COMMUNICATING INWARDLY WITH SAID CHAMBER, PISTONS FREELY SLIDING IN SAID CYLINDERS, A ROTOR MOUNTED IN SAID CENTRAL CHAMBER AND JOURNALLED IN SAID CASING, TWO STAGE PLANET GEARS REVOLUBLE IN SAID ROTOR, SAID GEARS INCLUDING A FIRST STAGE ADAPTED TO COOPERATE WITH SAID PISTONS AND A SECOND STAGE INCLUDING A PINION, AN INTERIORLY TOOTHED ANNULUS CARRIED BY SAID CASING AND MESHING WITH THE PINIONS CONSTITUTED BY THE SECOND STAGE OF SAID GEARS, AN OUTPUT SHAFT RIGID WITH THE ROTOR, A CHAMBER IN SAID CASING COAXIALLY TO THE ROTOR, A ROTARY VALVE UNIT DISTRIBUTOR HOUSED IN SAID LAST-NAMED CHAMBER AND FIXED TO THE ROTOR COAXIALLY THERETO, SEPARATE FLUID INLET AND OUTLET CHANNELS IN SAID VALVE UNIT, SAID CHANNELS TERMINATING ON THE PERIPHERY OF SAID VALVE UNIT, AND FURTHER CHANNELS FORMED IN THE CASING AND INTERCONNECTING SAID CHAMBER COAXIAL TO THE ROTOR WITH THE CLOSED ENDS OF THE CYLINDERS.
Dec. 13, 1966 P. E. MAYET ETAL. HYDRAULIC MOTORS 4 Sheets-Sheet 1 Filed June 50, 1964 /Nnfwmes Dec. 13, 1966 P. E. MAYET ETAL HYDRAULIC MOTORS 4 Sheets-Sheet 2 Filed June 50, 1964 HG. Z P/f/@ef E MA yer rry. P. E. MYET ETAL HYDRAULIC MO TORS Dec. 13, 1966 4 Sheets-Sheet 5 Filed June 30, 1964 United States Patent O 3,291,001 HYDRAUIC MOTORS Pierre Ernest Mayet, Urvault, and .lean Sylvain Bourdin, Nantes, France, assignors to Societe anonyme: Entreprise Bourdin & Chausse, Nantes, France Filed .lune 30, 1964, Ser. No. 379,320 Claims priority, application France, July 25, 1963, 942,633, Patent 1,371,345 6 Claims. (Cl. 91-180) The present invention relates generally to hydraulic motors and has more particular reference to a new or improved hydraulic motor of rugged and compact construction capable of providing a high torque for a low rotational speed. An object of the invention is to provide a hydraulic motor of the aforesaid type having such a small size as to enable it to be fitted for example into the rim of a wheel having a pneumatic tyre adapted to furnish a high torque, even with low operational pressures, irrespective of the speed of rotation of the motor and capable moreover of revolving in either the one or the other directions at an adjustable speed and progressively between zero and a unaximum value, said motor being adapted to be fed by a low rate of ow of liquid. As will be understood, such a motor may provide for example a driving action at the required speed and in the required direction owing to its combination with a variable output reversible pump without necessitating mechanism such as reducing gears, speed variators, gear boxes, diiierentials or the like. Such hydraulic motors are utilizable for example for imparting a translational stress to slow moving vehicles or public work craft which require high torques when they are set in motion or while they are running for small translational speeds, also in appliances or machine tools which may require high torques when they operate at low speeds. 4 A further object of the invention is to provide a hydraulic motor comprising a stationary casing having outwardly closed radially extending cylinders in which are mounted for sliding motion pistons which may freely project inwardly, said cylinders dening centrally of the casing a chamber in which is housed a rotor including at least a two stage planet gear mounted for rotation in said rotor, one stage comprising elements adpted to'cooperate with the pistons in the radial cylinders while the other stage comprises a pinion in mesh with an interiorly toothed annulus secured to .the casing, an output shaft being rigid with the rotor which also carries a driving shaft or equivalent member for a valve unit fitted coaxially to the assembly made up of the radial cylinders and rotor, said valve unit having separate fluid inlet and outlet, passages provided in the stationary casing successively connecting ports in the valve unit with the closed ends of the radial cylinders. A further object of the incention is to provide as a preferred constructional form of the improved hydraulic motor in which the planet gear or each planet gear comprises an axis journalled in the rotor webs, said axis constituting over a portion of its length the aforesaid pinion which meshes with the interiorly toothed annulus While being provided over another portion of its length with ICC ton slidable in the latter engages and repels the adjacent element of a planet gear and imparts rotation to it so that its pinion rolls along the inte-riorly toothed annulus and angularly moves the rotor while rotating the output shaft. Simultaneously, this rotational motion is transmitted t0 the valve unit for modifying the feed to and the exhaust from the cylinders. Actually during this rotatational motion that element of the planet gear which was previously engaged by a piston escapes therefrom while another element of the same gear is engaged by the adjacent piston in the rotational direction of the rotor. Advantageously the pistons are repelled through their 4accommodating cylinders by other elements of the planet gears while the latter rotate after the cylinders have been put into communication with the exhaust. The continuity of motion which is thus obtained may be improved and the resultant torque may be increased by arranging in the rotor several planet gears the angular settings of which are preferably slightly offset. Reversal of the intake and exhaust in the valve unit also permits a reversal of the rotation direction of the planet gears and consequently of the rotor and its output shaft. Furthermore a variation of the motor speed may be achieved by feeding the same from a pump having a varying rate of flow. V The provision of the valve unit outside the motor proper coaxially with respect thereto permits a relatively large size to be given to it, particularly a large diameter so as to provide between its inlet and outlet ports sullciently wide lands for avoiding any leakage due to hydraulic short circuits as may be liable to occur between two adjacent ports as they pass in front of the channel which connects them to one and the same cylinder. This construction also provides a satisfatcory balance of the valve unit. A still further object of the invention is to provide a motor as aforesaid wherein the root end of the pistons Ahas a disc valve adapted to stop each piston at the end of its intake stroke and afterwards to close the feed passage leading to its cylinder whereby at the end of the intake stage said disc valve prevents any fluid from penetrating into the cylinder even if the intake port of the valve unit is not yet closed. Likewise at the beginning of the exhaust stage, the piston is retained by its disc valve and is only repelled toward the bottom of its own cylinder when the planet gear element engages the same. Such a delay permits the port in the valve unit to become opened so that as the planet gear element engages the piston, said port is suiciently opened to permit a free flow of the fluid. Consequently the disc valve by retaining the piston at the end of its stroke while closing off the cylinder passage permits without any risk of leakage the opening of the exhaust port to be advanced while avoiding a resistant torque due to the incompressibility of the liquid. With these and such other objects in view as will incidentally appear hereafter, the invention comprises the novel construction land combination of parts that will now be described hereinafter Iwith reference t-o the accompanying diagrammatic drawings exemplifying the same and forming a part of the present disclosure. In lthe drawings: FIGURE l is a diametrical `sectional view along the line I-I in FIG. 2 of a hydraulic motor forming a suitable constructional form of the invention. FIGURE 2 is Ia sectional view `along the line II-II in FIG. l. FIGURE 3 is `a diametrical sectional View of the rot-or of the valve unit drawn to a larger scale. FIGURE 4 is a sectional view along the line IV-IV in FIG. 3. FIGURE is a sectional view along the line V-V in FIG. 3. FIGURE 6 is a sectional view of one of the radial cylinders in which a piston is mounted for sliding motion, said piston being provided with a disc valve adapted to stop its motion at the end of its intake stroke while closing the feed passage for its cylinder. The hydraulic motor as shown comprises a stationary casing designated `generally by 1 and closed by a blind cover 2 and a lid 3 through which the output shaft 4 of the motor passes, the side shell 5 of the casing 1 is provided with radially extending cylinders 6 which are closed outwardly by covers 7 and through which pistons 8 are arranged for sliding motion. These pist-ons may be fitted with annular gaskets or rings 9, and may freely project inwardly. The cylinders 6 define centrally of the casing 1 a chamber 10 in which is mounted a rotor 11 comprising a plurality of two stage planet gears (there are six gears in the illustrated example) which are designated -by the reference numeral 12. The rotor 11 is Irotatably mounted in the casing 1 owing Ito bearings 13, 14 and each planet gear 12 comprises an axis 15 journalled through bearings in web plates 18, 19 of the rotor 11 that are interconnected by a shaft 20. Each axis 15 carries the shank of a spool member having plates 22 between which are fitted rollers 23 providing between the plates 22 a bar assembly constituting circular teeth which cooperate with the radial pistons `8. Each pinion 21 constituting the second stage of the series of planet `gears 22 meshes with an interiorly toothed annulus 24 secured to the casing 1. The output shaft 4 of the motor is connected for joint motion to the rotor 11, the latter also carrying a shaft 25 for controlling a valve unit arranged coaxial-ly with respect to the assembly made up of the radial cylinders 6 and rotor 11. The valve unit shown lin detail in FIGS. 3 to 5 comprises pipes 26, 27 for t-he intake and the exhaust of the liquid. The functions of these pipes may be reversed for changing the direction of rotation of lthe motor as is described hereafter. Such pipes 26, 27 are constantly and respectively in communication with notches 28, 29 in the control shaft 25 for the valve unit through annular chambers 30, 31 and channels 32, 33. The casing 1 is provided with channels 34 which communicate at 35 with the radial cylinders 6. During yrotation of the shaft 25, its notches 28, 29 come into registration at appropriate times with the channels 34 formed in the casing 1, thereby providing communication between these notches :and the radial cylinders 6 through these channels 34. The lid 3 is provided with an annular gasket 36 for preventing any fluid leakage from fthe casing 1 to the outside. Annular gaskets 37 are provided in the casing 1 for preventing any leakage and any `hydraulic short circuit in the valve funit. Internal leakages from the motors are drained away through the passage 40 towards the reservoir. The operation of this improved hydraulic motor takes place as follows: When the valve unit receives fluid from a pump, for example through the pipe 36, said iluid reaches the notches 28 in the shaft 25 through the annular chamber 30 and the passages 32. Such notches 2S are connected at lsuitable moments with the radial cylinders 6 through the passages 34 and the ports 35 thereby permitting the fluid -to reach the cylinder 6a (see FIG. 2) for repelling the piston 8a toward the centre of the motor. The piston 8a toward the centre of the motor. The piston 8a then engages the roller 23a while causing rotation of the planet ygear 12a in the direction indicated by the arrow f so that the pinion of this gear rolls along the teeth of the interiorly toothed annulus 24, thereby ensuring angular motion of the rotor 11 and consequently rotation of lthe output shaft 4. At the same time, this rotation is transmitted t-o the valve unit for modifying feed and drainage of the cylinders. Actually during this rotation, the pist-on 8b which is in contact with the roller 23h is repelled by the latter toward the outer bottom wall of the cylinder 6a. One notch 29 in the shaft 25 situated in front of the channel 34 then permits the fluid to escape from the cylinder 6b through the port 35, said channel, the notch 29, the channels 33, the annular chamber 31 and the exhaust pipe 27. Ere to this, the piston 8b had, `responsive to the pressure of the fluid reaching the cylinder 6b repelled the roller 23a of the planet gear 12a while causing its rotation in the direction indicated by the arrow as above described. Continuity of the movement thus obtained may be further improved and the resultant torque may be increased by providing in the rotor 11 several planet gears whose angular positions are preferably slightly offset. In order to reverse the direction of rotation of the motor, it is only suilcient to tap the pipe 27 to the fluid intake and to tap the pipe 26 to the exhaust. Furthermore, lby combining the m-otor with a pump having a varying rate of delivery, a drive may be obtained at a speed varying in a continuous way from zero to a maximum value and even between a maximum value in one direction to a maximum value in the other direction. As will be easily understood from an inspection of FIGS. 4 and 5, the lands p provided between the notches 28 and 29 are broad enough to prevent hydraulic short `circuits between low pressure and high pressure. There may be further provided Vas shown by FIG. 6 at the root end of the pistons 8 a disc valve 38 adapted to stop each piston at the end of its intake stroke and then to close off the port 35 of the intake channel 34 provided in a bearing seat of the cylinder 6. Thus at the end of the intake step, the disc valve 38 prevents any fluid from entering the cylinder 6 even if the intake port for the valve unit is not yet closed. Likewise, at the beginning of the exhaust, the piston held by its disc valve is only repelled toward the end of its cylinder when one of the rollers 23 engages the same. This lag permits the port of the valve unit to become opened so that at the time when said roller 23 engages the piston, said port is sutilciently opened to permit a free flow of the fluid. Therefore the disc valve 38 permits, by locking the piston 8 at the end of its stroke while closing the channel 34 of the cylinder 6, an advanced opening of the exhaust to be achieved without any risk of leakage by staving olf a resistant torque due to incompressibility of the fluid. Minor constructional details may be varied without departing from the scope of the invention and the ambit of the appended claims. What we claim is: 1. A hydraulic motor comprising a stationary casing, radially extending cylinders provided in said casing, a central chamber in said casing, said cylinders being closed outwardly and communicating inwardly with said chamber, pistons freely sliding in said cylinders, a rotor mounted in said central chamber and journalled in said casing, two stage planet gears revoluble in said rotor, said gears including a first stage adapted to cooperate with said pistons and a second stage including a pinion, an interiorly toothed annulus carried by said casing and meshing with the pinions constituted by the second stage of said gears, an output shaft rigid with the rotor, a chamber in said casing coaxially to the rotor, a rotary valve unit distributor housed in said last-named chamber and llxed to the rotor coaxially thereto, separate fluid inlet and outlet channels in said valve unit, said channels terminating on the periphery of said valve unit, fand further channels formed in the casing and interconnecting said chamber coaxial to the rotor with the closed ends of the cylinders. 2. A hydraulic motor according to claim 1 combined with a fluid source having a varying rate of delivery providing for the motor a varying speed. 3. A hydraulic mot-or comprising a stationary casing, radially extending cylinders in said casing, a central chamand outlet channels in said distributor, said channels having their mouths on the periphery of said distributor, and further channels formed in the stationary casing and nterconnecting said last-named chamber with the closed ber in said casing, said cylinders being closed outwardly 5 ends of the cylinders. and communicating inwardly with said central chamber, pistons mounted for free sliding motion in said cylinders, a rotor having a pair of supporting side plates and mounted in said central chamber and being journalled in said casing, two stage planet gears revoluble in the rotor, each gear including an axis journalled in the rotor side plates, a pinion fast upon a portion of said axis, further plates secured to another portionk of said axis and elements adapted to cooperate wtih pistons, fitted between said iurther plates, a stationary toothed annulus carried by the casing and meshing with the planet gear pinions, an output shaft fast upon the rotor, a chamber provided in said casing coaxially to said rotor, 1a rotary valve unit distributor housed in said last-named chamber and fixed to the rotor coaxially thereto, separate fluid inlet and outlet channels formed in said Valve unit and terminating on the periphery of said valve unit, and further channels formed in the casing and interconnecting said chamber coaxial to the rotor with the closed ends of the cylinders. 4. A hydraulic motor according to claim 3 in which the elements mounted between said further plates of the planet gears are revoluble elements having a circular sectional shape providing circular teeth cooperating with the radial pistons. 5. A hydraulic motor comprising a stationary casing, radially extending cylinders provided in said casing, a central chamber defined by said casing, said cylinders being closed outwardly sand communicating inwardly with said central chamber, pist-ons mounted for free sliding motion in said cylinders, a rotor in said central chamber and having its trunnions journalled in the casing walls, two stage planet gears revoluble in the rotor, such gears occupying slightly offset mutual angular .positions and including a rst stage adapted to cooperate with said pistons and a second stage constituted by a pinion, a stationary toothed annulus carried by the casing and meshing with the pinions constituted by the second stage of said planet gears, an output shaft fast with the rotor, a chamber provided in the casing coaxially of the rotor, Aa rotary valve unit distributor housed in the last-named chamber and se- `cured to the 4rotor coaxially thereto, sepanate fluid inlet 6. A hydraulic motor comprising a Stationary casing, a central chamber in said casing, radially extending cylinders formed in said casing, said ycylinders being closed outwardly and having their mouths directed inwardly in communication with said central chamben, a bearing seat provided at an intermediate point of said cylinders, pistons fitted for free sliding motion in s-aid `respective cylinders, a disc valve head on each piston, said valve coming into abutting position against said seat at the end of the stroke of the pistons in one direction, a rotor in said central chamber and having trunnions journalled in the adjacent walls of the casing, two stage planet gears revolui ble in the rotor, said gears including a first stage Iadapted to cooperate with said pistons and a second stage cornprising a pinion, a stationary toothed annulus carried by the casing and meshing with the pinions constituted by the second stage of said gears, an output shaft fast with the rotor, a chamber formed in the casing in coaxial relation to the rotor, a rotary valve unit distributor housed in the last-cited chamber and Iixed to the rotor coaxially thereto, separate iiuid inlet and outlet channels formed in said valve unit iand having their mouths on the periphery of said valve unit, and further channels formed in the casing and interconnecting said last-cited chamber with the closed ends of the cylinders, the last-named channels ending adjacent said bearing seats so as to be blanked off when-the radial pistons reach the end of their stroke in said direction. References Cited by the Examiner UNITED STATES PATENTS 717,445 12/1902 Nestius 91-180 820,345 5/1906 Brousseau 91-180 1,455,443 5/1923 Mayer 91-180 1,804,921 5/1931 Ellyson 91-180 1,924,423 8/1933 Svenson 91-180 3,090,363 5/1963 Stuver 91-180 MARTIN P. SCHWADRON, Primary Examiner. PAUL E. MASLOUSKY, Examiner.

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Cited By (1)

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    US-6302659-B1October 16, 2001Stephen Michael Parker, Michael Peter Cooke, Peter Alban George Collingborn, Ian Roy ThornthwaiteMulti-chamber positive displacement pump