Hydrostatic control unit

Abstract

A control unit for controlling fluid flow to a fluid motor and for producing a flow proportional to the rate of rotation of an input shaft and for applying a pressure to the fluid motor proportional to the applied torque on the input shaft. The control unit includes a valve means for directing fluid to a fluid motor in response to rotation of the input shaft. The valve means includes a fixed valve part and a movable valve part. The movable valve part is moved to effect actuation of the valve through a gerotor gearset mechanism which also functions to meter the flow of fluid which is directed to the fluid motor.

What is claimed is:  .[.1. A control unit comprising: metering means for metering fluid flow and including first and second toothed members disposed in meshing engagement with one another; input means for rotating said first member relative to said second member; a changeover valve means for directing fluid flow to one of alternative flow paths and movable between a neutral position and first and second oppositely disposed operating positions in response to torque applied thereto by said second member for directing the metered flow of fluid from said metering means to one of said alternative flow paths..]. .[.2. A control unit comprising a gerotor mechanism, said gerotor mechanism comprising an internally lobed gerotor rotor member drivingly connected with an input shaft, an externally lobed gerotor rotor member located within said internally lobed gerotor rotor member, the lobes on said gerotor rotor members defining pockets which expand and contract upon relative rotational and orbital movement of said gerotor rotor members, commutator valve means for directing fluid flow to said expanding pockets and from said contracting pockets, said commutator valve means comprising a sleeve-like commutator valve member having exterior axial grooves and generally radially extending passages extending from the outer periphery thereof into the bore thereof, a manifold member having a bore within which said commutator valve member is located, said manifold member having passages extending therethrough and which alternately communicate with said axially extending grooves and said generally radially extending passages in said commutator valve member on relative rotation therebetween, and means drivingly connecting said manifold member to said internally lobed gerotor member for rotation therewith..]. .[.3. A control unit comprising an input shaft, housing means having a inlet port and a pair of outlet ports, a directional control valve means for porting fluid from said inlet port selectively to one of said outlet ports, said directional control valve means comprising a fixed valve means and a controlling valve member movable through a predetermined limited distance relative to said fixed valve member to control fluid flow therethrough, and metering means in said housing interconnecting said input shaft and said controlling valve member for moving said controlling valve member said limited distance in response to initial rotation of said input shaft and for directing fluid flow to said directional control valve as said shaft rotates..]. .[.4. A control unit as defined in claim 1 further including biasing means for urging said controlling valve member to a netural position and effective to move said controlling valve member to said neutral position upon termination of rotation of the input shaft, said metering means overcoming said biasing means to effect movement of said controlling member..]. .[.5. A control unit as defined in claim 1 wherein said fixed valve member and said controlling valve member comprises plate valve members movable relative to each other upon rotation of said input shaft..]. .[.6. A control unit as defined in claim 1 wherein said metering means comprises a gerotor mechanism having an internally toothed gerotor member and an externally toothed gerotor member, means connecting said input shaft to one of said gerotor members for rotation with said shaft, and means connecting the other of said gerotor members with said controlling valve member to move said controlling valve member..]. .[.7. A control unit as defined in claim 6 further including means for limiting movement of said controlling valve member relative to said fixed valve means, and biasing means for returning said controlling valve member to a neutral position relative to said fixed valve means..]. .[.8. A control unit as defined in claim 6 wherein said fixed valve means comprises a sleeve valve member and said controlling valve member comprises an axially extending valve member located within said fixed valve means and which rotates relative to said fixed valve means and further including a drive link interconnecting said other rotor member of said gerotor mechanism to said controlling valve member to effect rotation thereof in response to torque applied thereto..]. .[.9. A control unit as set forth in claim 6 wherein said other gerotor member is rotatable about its central axis in response to initial rotation of said one gerotor member to effect movement of said controlling valve member and said valve members constrain said other gerotor member to then orbit only relative to said one gerotor member during continued rotation of said one gerotor member by rotation of said input shaft when the force applied to said controlling valve member is not sufficient to move same..]. .[.10. A control unit as set forth in claim 6 wherein said one gerotor member comprises an internally toothed gerotor rotor member supported for rotation about the axis or rotation of the shaft and said other gerotor member comprises an externally toothed gerotor rotor member supported for rotational movement about its own axis and for orbiting movement about the axis of said one gerotor member..]. .[.11. A control unit as set forth in claim 6 wherein said one gerotor member comprises an externally toothed gerotor rotor member and said other gerotor member comprises an internally toothed rotor member..]. .[.12. A control unit as defined in claim 6 wherein said one gerotor member comprises an internally toothed gerotor rotor member which is mounted for rotary and orbital movement and said other of said gerotor members comprises an externally toothed gerotor rotor member supported for limited rotational movement for moving said controlling valve member..]. .[.13. A control unit for controlling fluid flow to a fluid motor, said control unit comprising housing means having an inlet port and a pair of outlet ports for communication with the fluid motor, directional control valve means for directing fluid from said inlet port selectively to one of said outlet ports in response to the direction of rotation of an input shaft, said directional control valve means including a fixed valve part and a movable valve part movable in opposite directions to direct fluid to a selected one of said outlet ports and to said fluid motor, and means for transmitting torque from said input shaft to said movable valve part to effect movement thereof, said means for transmitting torque to said movable valve part comprising metering means for directing a metered flow of fluid upon rotation of said shaft to said directional control valve means and means for transmitting torque from said metering means to said movable valve part..]. .[.14. A control unit as defined in claim 13 wherein said metering means comprises a gerotor mechanism having one rotor member drivingly connected with the input shaft and a second rotor member drivingly connected with said movable valve part, said gerotor mechanism transmitting a torque to said valve part which is proportional to the torque applied to the input shaft and said valve means providing a fluid pressure flow to said fluid motor depending upon the amount of movement of said movable valve part..]. .[.15. A control unit as defined in claim 13 further including means for limiting movement of said movable valve part relative to said fixed valve part, and biasing means for returning said movable valve part to a neutral position relative to said fixed valve part when torque application thereto is removed..]. .[.16. A control unit as set forth in claim 14 wherein said one gerotor member comprises an internally toothed gerotor rotor member supported for rotation about the axis of rotation of the shaft and said outer gerotor member comprises an externally toothed gerotor rotor member supported for rotational movement about its own axis and for orbiting movement about the axis of said one gerotor member..]. .[.17. A control unit as set forth in claim 14 wherein said one gerotor member comprises an externally toothed gerotor rotor member and said other gerotor member comprises an internally toothed gerotor rotor member..]. .[.18. A control unit as defined in claim 14 wherein said one gerotor member comprises an internally toothed gerotor rotor member which is mounted for rotary and orbital movement and said other of said gerotor members comprises an externally toothed gerotor rotor member supported for limited rotational movement for moving said movable valve part..]. .[.19. A control unit for directing fluid to a fluid motor comprising: 
     
        first gerotor member..]. .[.20.  A control unit for directing fluid comprising: gerotor means for metering fluid flow therethrough and including an internally toothed gerotor member and an externally toothed gerotor member disposed within and in meshing engagement with said internally toothed gerotor member, said externally toothed gerotor member having fewer teeth than said internally toothed gerotor member for defining expanding and contracting chambers during rotation of a first of said gerotor members relative to the second gerotor member;   input means for rotating said first gerotor member relative to said second gerotor member;   commutator valve means operatively connected to said gerotor means for feeding fluid to and exhausting fluid from said expanding and contracting chambers;   changeover valve means for alternatively directing fluid exhausted from said commutator valve means to one of first and second outlets, said changeover valve means including a rotatable valve member having a neutral position and a first operating position for feeding fluid flow to said commutator valve means while directing fluid exhausted therefrom to said first outlet during rotation of said first gerotor member in one direction and a second operating position for feeding fluid flow to said commutator valve means while directing fluid exhausted therefrom to said second outlet during rotation of said first gerotor member in the opposite direction;   and means interconnecting said valve member and said second gerotor member and including stop means for limiting rotation of said valve member to define said first and second operating positions while limiting rotation of said second gerotor member whereby rotation of said first gerotor member applies a torque to said second gerotor member to effect a rotation   
     
     
        of said valve member..]. 21. A control unit for controlling fluid flow to a fluid motor, said control unit comprising valve means for directing fluid to said fluid motor in response to rotation of the input shaft, said valve means including a fixed valve part and a movable valve part movable to direct fluid to said fluid motor, and means for transmitting torque from said input member to said movable valve part to effect movement thereof, said means for transmitting torque to said movable valve part comprising metering means for directing a metered flow of fluid upon rotation of said shaft to said valve parts, means for transmitting torque from said metering means to said movable valve part, said metering means comprising a gerotor mechanism having one .[.rotor.]. .Iadd.gerotor .Iaddend.member drivingly connected with the input shaft and a second .[.rotor.]. .Iadd.gerotor .Iaddend. member drivingly connected with said movable valve part, said gerotor mechanism transmitting a torque to said valve part which is proportional to the torque applied to the input shaft and said valve means providing a fluid pressure flow to said fluid motor depending upon the amount of movement of said movable valve part, said one gerotor member comprising an internally toothed gerotor rotor member supported for rotation about the axis of rotation of the shaft and said .[.other.]. .Iadd.second .Iaddend.gerotor member comprising an externally toothed gerotor rotor member supported for rotational movement about its own axis and for orbiting movement about the axis of said one gerotor member, and including commutator valve means for providing fluid flow into and from the gerotor mechanism, said commutator valve means comprising a sleeve-like commutator valve member having exterior axial grooves and generally radially extending passages extending from the outer periphery thereof into the bore thereof, a manifold member having a bore within which said commutator valve member is located, said manifold member having passages extending therethrough and which alternately communicate with said axially extending grooves and said generally radially extending passages in said commutator valve member on relative rotation therebetween, and means drivingly connected said manifold member with said one .[.rotor.]. .Iadd.gerotor .Iaddend.member for rotation therewith upon rotation of said input shaft. .[.22. A control unit comprising a gerotor mechanism, said gerotor mechanism comprising an internally lobed gerotor rotor member drivingly connected with an input shaft, an externally lobed gerotor rotor member located within said internally lobed gerotor rotor member, the lobes on said gerotor rotor members defining pockets which expand and contract upon relative rotational and orbital movement of said gerotor members, commutator valve means for directing fluid flow to said expanding pockets and from said contracting pockets, said commutator valve means comprising a sleeve-like commutator valve member having exterior axial grooves and generally radially extending passages extending from the outer periphery thereof into the bore thereof, a manifold member having a bore within which said commutator valve member is located, said manifold member having passages extending therethrough and which alternately communicate with said axially extending grooves and said generally radially extending passages in said commutator valve member on relative rotation therebetween, means drivingly connecting said manifold member to said internally lobed gerotor member for rotation therewith, and including a fixed valve member and a controlling valve member movable through a predetermined limited angle relative to the fixed valve member to control fluid flow therethrough, and means connecting said externally lobed gerotor rotor member to said controlling valve member to transmit torque thereto to effect movement of said controlling valve member relative to said fixed valve member..]. .Iadd. 23. A control unit for controlling fluid flow to a fluid motor, said control unit comprising valve means for directing fluid to said fluid motor in response to rotation of a shaft about a central axis, said valve means including a fixed valve part and a movable valve part, said fixed and movable valve parts defining passages directing fluid to said fluid motor upon relative movement thereof, means for transmitting torque from said shaft to said movable valve part to effect movement thereof, said means for transmitting torque to said movable valve part comprising a metering mechanism for directing a metered flow of fluid through said valve parts to said motor upon rotation of said shaft, said metering mechanism comprising a gearset including relatively rotatable and orbital internally and externally toothed gear members, said internally toothed gear member having one more tooth than said externally toothed gear member and the teeth of said gear members defining axially extending fluid pockets which expand and contract on relative orbital and rotational movement of the gear members, commutator valve means for controlling flow to and from the fluid pockets formed by the gear members, one of said gear members being supported for limited rotational movement, a mechanical connection between said one gear member and said movable valve part for transmitting torque from said one gear member to said movable valve part upon limited rotational movement of said one gear member, means for transmitting torque from said shaft to said other of said gear members, a drive member disposed on one axial side of said gearset and sealingly closing one axial end of said fluid pockets, said commutator valve means including at least one commutator valve member disposed on the other axial side of said fluid pockets, and fastener means for clampingly engaging said drive member, said commutator valve member and one of said gear members together so as to resist relative axial movement therebetween. .Iaddend..Iadd. 24. A control unit as defined in claim 23 wherein said externally toothed gear member is supported for orbital motion and for said limited rotational movement, and wherein said internally toothed gear member is supported for rotational movement and said mechanical connection comprises a link angularly disposed with respect to said central axis, a portion of said link being drivingly connected to said externally toothed gear member and rockable relative thereto and a portion of said link being drivingly connected with said movable valve part and rockable relative thereto to impart movement thereto in response to rotational movement of said externally toothed gear member, said fastener means clampingly engaging said drive member, said first commutator valve member and said internally toothed gear member together. .Iaddend. .Iadd. 25. A control unit as defined in claim 23 wherein said second commutator valve member comprises a sleeve-like member having exterior axial grooves and generally radially extending passages extending from the outer periphery thereof into the bore thereof, said first commutator valve member comprising a manifold member having a bore within which said sleeve-like member is located, said manifold member having passages extending therethrough and which alternately communicate with said axially extending grooves and said generally radially extending passages in said sleeve-like member on relative rotation between said manifold member and said sleeve-like member. .Iaddend. .Iadd. 26. A control unit as defined in claim 25 wherein said mechanical connection includes a link having a first portion drivingly connected with said sleeve-like member and rockable relative thereto, said link being angularly disposed with respect to said central axis and having a second portion drivingly connected with said part and rockable relative thereto, said mechanical connection further including a part drivingly connecting said sleeve-like member with said movable valve part. .Iaddend..Iadd. 27. A control unit as defined in claim 25 wherein said drive member includes a drive plate member supported solely for rotation about said central axis, said drive plate member being fixedly connected with said shaft for rotation therewith, said drive plate member including a radial face engaging a radial face of said internally toothed member to seal the fluid pockets at said one axial end of said gearset. .Iaddend. .Iadd. 28. A control unit as defined in claim 27 including a plate member disposed between said manifold member and said other axial side of said gearset, said plate member having a radial face engaging another radial face of said internally toothed gear member, said fastener means clampingly connecting said plate member with said manifold member and with said internally toothed gear member. .Iaddend..Iadd. 29. A control unit as defined in claim 23 wherein said drive member, internally toothed gear member and said first commutator valve member are located in a first housing portion and are fastened together as a unit for simultaneous assembly within said first housing portion, and wherein said fixed and movable valve parts are located in a second housing portion. .Iaddend..Iadd. 30. A control unit as defined in claim 23 wherein said fixed and movable valve parts are disposed in a housing having first and second ports for fluid communication with said motor, said movable valve part being movable in opposite directions from a neutral position for communicating fluid between said commutator valve means and said first and second ports. .Iaddend. .Iadd. 31. A control unit for controlling fluid flow to a fluid motor, said control unit comprising valve means for directing fluid to said fluid motor in response to rotation of an input shaft about a central axis, said valve means comprising a fixed valve part and a movable valve part, said fixed and movable valve parts defining passages for directing fluid to said fluid motor upon relative movement of said valve parts, a metering mechanism including an externally toothed gear member supported for limited rotational movement and an internally toothed gear member supported for orbital and rotational movement relative to said externally toothed gear member, said internally toothed gear member having one more tooth than said externally toothed gear member and the teeth of said gear members defining fluid pockets which expand and contract on relative orbital and rotational movement of the gear members, commutator valve means for controlling fluid flow to and from the fluid pockets formed by the gear members, said metering mechanism directing a metered flow of fluid to said motor through said valve parts upon rotation of said input shaft, a drive sleeve having a portion drivingly connected with said drive shaft for joint rotation therewith about said central axis, said drive sleeve having internal gear teeth, said internally toothed gear member having external gear teeth around the periphery thereof in meshing engagement with said internal gear teeth of said drive sleeve, a mechanical connection for transmitting torque from said externally toothed gear member to said movable valve part to move same relative to said fixed valve part in response to rotation of said externally toothed gear member, the intermeshing gear teeth of said drive sleeve and said internally toothed gear member and of said internally toothed gear member and said externally toothed gear member being effective to rotate and orbit said internally toothed gear member and to rotate said externally toothed gear member to transmit torque to said movable valve part upon rotation of said input shaft. .Iaddend..Iadd. 32. A control unit as defined in claim 31 wherein said drive sleeve comprises a tubular member having integrally formed internal gear teeth and said drive shaft has a fixed drive plate drivingly connected therewith and which has external gear teeth in meshing engagement with internal gear teeth on said tubular member. .Iaddend..Iadd. 33. A control unit as defined in claim 31 wherein said fixed and movable valve members comprise plate valve members movable relative to each other upon transmission of torque from said externally toothed gear member to one of the plate valve members. .Iaddend..Iadd. 34. A control unit as defined in claim 31 wherein said externally toothed gear member is mounted for limited rotation about an axis coaxial with said central axis and the inner diameter of said drive sleeve is greater than the outer diameter of said internally toothed gear member to enable said relative orbital movement to occur while the meshing engagement of said drive sleeve gear teeth and said gear teeth on the outer periphery of said internally toothed member is maintained. .Iaddend. .Iadd. 35. A control unit as defined in claim 31 wherein the center of the internally toothed member is offset from the center of the drive sleeve, and wherein only a portion of the external gear teeth on the periphery thereof is in meshing engagement with the internal gear teeth of said drive teeth. .Iaddend. .Iadd. 36. A control unit comprising an input shaft, housing means having an inlet port and a pair of outlet ports, a directional control valve means for porting fluid from said inlet port selectively to one of said outlet ports, said directional control valve means comprising a fixed valve means and a controlling valve member movable through a predetermined limited distance relative to said fixed valve member to control fluid flow therethrough, and metering means in said housing interconnecting said input shaft and said controlling valve member for moving said controlling valve member said limited distance in response to initial rotation of said input shaft and for directing fluid flow to said directional control valve as said shaft rotates, said metering means comprising a gerotor mechanism having an internally toothed gerotor member and an externally toothed gerotor member, means connecting said input shaft to one of said gerotor members for rotation with said shaft, and means connecting the other of said gerotor members with said controlling valve member to move said controlling valve member, said other gerotor member being rotatable about its central axis in response to initial rotation of said one gerotor member to effect movement of said controlling valve member and said valve members constraining said other gerotor member to then orbit only relative to said one gerotor member during continued rotation of said one gerotor member by rotation of said input shaft when the force applied to said controlling valve member is not sufficient to move same. .Iaddend..Iadd. 37. A control unit comprising an input shaft, housing means having an inlet port and a pair of outlet ports, a directional control valve means for porting fluid from said inlet port selectively to one of said outlet ports, said directional control valve means comprising a fixed valve means and a controlling valve member movable through a predetermined limited distance relative to said fixed valve member to control fluid flow therethrough, and metering means in said housing interconnecting said input shaft and said controlling valve member for moving said controlling valve member said limited distance in response to initial rotation of said input shaft and for directing fluid flow to said directional control valve as said shaft rotates, said metering means comprising a gerotor mechanism having an internally toothed gerotor member and an externally toothed gerotor member, means connecting said input shaft to one of said gerotor members for rotation with said shaft, and means connecting the other of said gerotor members with said controlling valve member to move said controlling valve member, said one gerotor member comprising an internally toothed gerotor rotor member supported for rotation about the axis of rotation of the shaft and said other gerotor member comprising an externally toothed gerotor rotor member supported for rotational movement about its own axis and for orbiting movement about the axis of said one gerotor member. .Iaddend..Iadd. 38. A control unit comprising an input shaft, housing means having an inlet port and a pair of outlet ports, a directional control valve means for porting fluid from said inlet port selectively to one of said outlet ports, said directional control valve means comprising a fixed valve means and a controlling valve member movable through a predetermined limited distance relative to said fixed valve member to control fluid flow therethrough, and metering means in said housing interconnecting said input shaft and said controlling valve member for moving said controlling valve member said limited distance in response to initial rotation of said input shaft and for directing fluid flow to said directional control valve as said shaft rotates, said metering means comprising a gerotor mechanism having an internally toothed gerotor member and an externally toothed gerotor member, means connecting said input shaft to one of said gerotor members for rotation with said shaft, and means connecting the other of said gerotor members with said controlling valve member to move said controlling valve member, said one gerotor member comprising an externally toothed gerotor rotor member and said other gerotor member comprising an internally toothed gerotor member. .Iaddend..Iadd. 39. A control unit for controlling fluid flow to a fluid motor, said control unit comprising housing means having an inlet port and a pair of outlet ports for communicating with the fluid motor, directional control valve means for directing fluid from said inlet port selectively to one of said outlet ports in response to the direction of rotation of an input shaft, said directional control valve means including a fixed valve part and a movable valve part movable in opposite directions to direct fluid to a selected one of said outlet ports and to said fluid motor, and means for transmitting torque from said input shaft to said movable valve part to effect movement thereof, said means for transmitting torque to said movable valve part comprising metering means for directing a metered flow of fluid upon rotation of said shaft to said directional control valve means and means for transmitting torque from said metering means to said movable valve part, said metering means comprising a gerotor mechanism having one rotor member drivingly connected with the input shaft and a second rotor member drivingly connected with said movable valve part, said gerotor mechanism transmitting a torque to said valve part which is proportional to the torque applied to the input shaft and said valve means providing a fluid pressure flow to said fluid motor depending upon the amount of movement of said movable valve part, said one gerotor member comprising an internally toothed gerotor rotor member supported for rotation about the axis of rotation of the shaft and said second gerotor member comprising an externally toothed gerotor rotor member supported for rotational movement about its own axis and for orbiting movement about the axis of said one gerotor member. .Iaddend..Iadd. 40. A control unit for controlling fluid flow to a fluid motor, said control unit comprising housing means having an inlet port and a pair of outlet ports for communication with the fluid motor, directional control valve means for directing fluid from said inlet port selectively to one of said outlet ports in response to the direction of rotation of an input shaft, said directional control valve means including a fixed valve part and a movable valve part movable in opposite directions to direct fluid to a selected one of said outlet ports and to said fluid motor, and means for transmitting torque from said input shaft to said movable valve part to effect movement thereof, said means for transmitting torque to said movable valve part comprising metering means for directing a metered flow of fluid upon rotation of said shaft to said directional control valve means and means for transmitting torque from said metering means to said movable valve part, said metering means comprising a gerotor mechanism having one gerotor member drivingly connected with the input shaft and a second gerotor member drivingly connected with said movable valve part, said gerotor mechanism transmitting a torque to said valve part which is proportional to the torque applied to the input shaft and said valve means providing a fluid pressure flow to said fluid motor depending upon the amount of movement of said movable part, said one gerotor member comprising an externally toothed gerotor rotor member and said second gerotor member comprising an internally toothed gerotor rotor member. .Iaddend. .Iadd. 41. A control unit for vehicle powersteering mechanism comprising: a housing having an inlet for connection to a source of hydraulic fluid under pressure and an outlet for returning hydraulic fluid to said source;   a pair of ports for connection to a double chamber hydraulic servomotor the movement of which controls the steering of dirigible wheels of the vehicle;   a hydraulic motor provided with a rotatable element and a follower element;   a distributor valve means provided with at least one displaceable body, in the form of a sleeve, angularly displaceable with respect to a neutral position, said distributor valve means being operable on rotation of a control shaft connected thereto to divert hydraulic fluid flowing from said inlet through said housing to said outlet to one of said ports and thus to its associated chamber of said servomotor, via said hydraulic motor, the hydraulic fluid being exhausted from the other chamber of the servomotor to said outlet via said other port;   means adapted to form a direct connection of said rotatable element of the motor to said control shaft;   means adapted to form a mechanical connection of said follower element of the motor to the sleeve like displaceable body of said rotatable distributor valve means;   means adapted to limit the displacement of said sleeve like displaceable body with respect to the stationary part of said distributor valve means, and with respect to said neutral position;   a plurality of circumferentially spaced longitudinally extending passages provided in said sleeve like displaceable distributor body to feed hydraulic fluid from said inlet, via said motor, to one or the other of said ports when said sleeve like displaceable distributor body is in its displaced position with respect to the neutral position;   first passages in said housing communicating with said inlet and with said longitudinally extending passages; second passages in said housing emanating from each of said ports and communicating with said longitudinally extending passages; and   radially extending passages in said sleeve like displaceable distributor body communicating with said first passages in said housing, for feeding hydraulic fluid arriving from said inlet to said distributor valve means.   
     
     
        .Iaddend. .Iadd. 42.  A fluid control unit comprising an input shaft,   housing means having an inlet port and a pair of outlet ports,   a directional control valve means for porting fluid from said inlet port selectively to one of said outlet ports, said directional control valve means including a valve member fixed relative to said housing means,   a controlling valve member movable through a predetermined limited distance relative to said fixed valve member to control fluid flow therethrough,   said fixed valve member and said controlling valve member comprising plate valve members movable relative to each other upon rotation of said input shaft,     a metering mechanism in said housing means connecting said input shaft and said controlling valve member for transmitting torque to move said controlling valve member said limited distance in response to rotation of said input shaft,   said metering mechanism comprising a gearset including relatively rotatable and orbital internally and externally toothed gears, said externally toothed gear being located within said internally toothed gear, said internally toothed gear having one more tooth than said externally toothed gear, and the teeth of said internally and externally toothed gears defining fluid chambers which expand and contract on relative orbital and rotational movement of the gears,   means connecting one of said gears to said input shaft for movement in response to rotation of the input shaft, means connecting the other of said gears to said controlling valve member,   a commutator plate-valve connected to said externally toothed gear and having a first radial face slidably engaging one radial face of said internally toothed gear, said commutator plate-valve member including passages communicating with said directional control valve means to direct fluid received by said directional control valve from the inlet to the expanding fluid pockets and to direct fluid from the contracting fluid pockets to the directional control valve, and   stop means for limiting movement of said controlling valve member of said directional control valve relative to the housing means. .Iaddend..Iadd.   
     
     
          .  A control unit as defined in claim 42 wherein said controlling valve member comprises a pivotal plate-valve member movable from a neutral position to an operating position communicating said inlet port with said commutator valve for directing fluid from said inlet port to said metering mechanism through said commutator valve and communicating one of said outlet ports with said commutator valve for directing fluid from said metering mechanism to said one of said outlet ports. .Iaddend..Iadd. 44. A control unit as defined in claim 43 wherein said fixed plate-valve member and said controlling plate-valve member have adjacent radially extending faces which are slidable relative to each other upon pivotal movement of said controlling plate-valve member in response to the torque transmitted thereto by rotation of said other of said gears, adjacent radial faces of said fixed and controlling plate-valve members cooperating upon relative pivoting movement to form part of fluid passages directing flow from said inlet port to said commutator valve and from said commutator valve to said one of said outlet ports. .Iaddend..Iadd. 45. A control unit as defined in claim 44 wherein said one gear element comprises said internally toothed gerotor gear and said other gear comprises said externally toothed gerotor gear, said commutator plate-valve member being movable with said externally toothed gerotor gear relative to said internally toothed gerotor gear and having a first radial face engaging one radial face of said internally toothed gerotor gear. .Iaddend..Iadd. 46. A hydraulic control unit comprising means defining an inlet port and a pair of outlet ports,   an input shaft,   a metering mechanism operatively associated with said input shaft and allowing flow from the inlet port to an outlet port in a quantity which is proportional to the speed and extent of rotation of said input shaft, said metering mechanism including a first gear element connected to said input shaft for rotation therewith and   a second gear element which orbits in response to rotation of said first gear element,   said first and second gear elements defining fluid chambers therebetween which have changing volumes during relative movement of said first and second gear elements,     control valve means including a pivotal valve having a neutral position and pivotal to an operating position upon rotation of said input shaft for directing fluid from said inlet port to some chambers in said metering mechanism and directing fluid from other chambers in said metering mechanism to one of said outlet ports,   means connecting said pivotal valve and said second gear element of the metering mechanism for common pivoting movement,   resilient means biasing said pivotal valve to said neutral position, and   stop means for limiting pivoting movement of said pivotal valve.   
     
     
        .Iaddend..Iadd. 47.  A hydraulic control unit as defined in claim 46 wherein said means connecting said pivotal valve and said second gear element of said metering mechanism comprises a link drivingly connected to and disposed at an angle to the axis of rotation of said second gear element, and said resilient means biasing said pivotal valve to said neutral position acts directly on said pivotal valve. .Iaddend..Iadd. 48. A control unit as defined in claim 47 wherein said first gear element of said metering mechanism comprises an internally toothed gerotor gear and said second gear element of said metering mechanism comprises a complementary externally toothed gerotor gear, said pivotal valve including a directional control valve portion and a commutator valve portion having joint pivotal movement, a manifold member coupled with said internally toothed gerotor gear and rotatable therewith relative to said commutator valve portion of said pivotal valve. .Iaddend..Iadd. 49. A control unit as defined in claim 48 wherein said pivotal valve comprises a cylindrical member having a plurality of circumferentially spaced, axially extending slots on the outer periphery thereof, and said control unit further includes a second valve member encircling said cylindrical member and having fluid passages therein, and said slots in said cylindrical member communicate with said fluid passages in said second valve member upon pivotal movement of said cylindrical member away from said neutral position. .Iaddend. .Iadd. 50. A control unit as defined in claim 49 wherein said cylindrical member is hollow and certain of said axially extending slots includes openings communicating with the interior of said cylindrical member, and means defining a fluid passage communicating the interior of said cylindrical member with said metering mechanism through said commutator valve portion of said pivotal valve. .Iaddend..Iadd. 51. A control unit as defined in claim 50 including means defining an external housing, said resilient means for biasing said pivotal valve to the neutral position comprises a torsion spring located partially within said hollow cylindrical member, said torsion spring having a first portion releasably fixed against motion relative to said housing and an axially spaced portion connected with said pivotal valve for movement therewith and wherein said first portion of said torsion spring may be manually moved relative to said housing when said first portion of said torsion spring is released from said housing to allow pivotal movement of said pivotal valve to adjust the neutral position of said pivotal valve. .Iaddend..Iadd. 52. A control unit as defined in claim 46 wherein said control valve includes a commutator valve for directing fluid flow to and from the variable volume fluid chambers of said metering mechanism in timed relation to the changing volumes thereof during relative movement of said first and second gear elements, said pivotal valve comprising a first plate directional control valve member pivotal from a neutral position to an operating position communicating said inlet port with said commutator valve for directing fluid from said inlet port to said metering mechanism through said commutator valve and communicating said outlet port with said commutator valve for directing fluid from said metering mechanism to said outlet port. .Iaddend..Iadd. 53. A control unit as defined in claim 52 wherein said first plate directional control valve member cooperates with a second plate valve member adjacent thereto, said first plate valve member being pivotally movable with respect to said second plate valve member, said first plate valve member and said second plate valve member having adjacent radially extending faces which are slidable relative to each other upon pivotal movement of said first plate valve member in response to the torque transmitted thereto by rotation of said second gear element, adjacent radial faces of said first and second plate valve members cooperating upon relative rotation thereof to form part of fluid passages directing flow from said inlet port to said commutator valve and from said commutator valve to an outlet port. .Iaddend..Iadd. 54. A control unit as defined in claim 53 wherein said first gear element comprises an internally toothed gerotor gear and said second gear element comprises a complementary externally toothed gerotor gear, said commutator valve comprising a third plate valve member movable in timed relation to the movement of at least one of said gerotor gears and having a first radial face engaging one radial face of the internally toothed gerotor gear, said third plate valve member forming part of commutator passages for directing the flow of fluid to and from said fluid chambers of said metering mechanism. .Iaddend..Iadd. 55. A control unit as defined in claim 54 wherein said third plate valve member includes a second radial face engaging the other radial face of said first plate valve member and is connected to said externally toothed gear. .Iaddend..Iadd. 56. A control unit as defined in claim 46 further including a drive member connected with said input shaft and disposed on one axial side of said metering mechanism, said drive member sealingly closing one axial side of said metering mechanism, at least one commutator valve part disposed on the other axial side of the metering mechanism, and fastener means for clampingly engaging said drive member said second element of said metering mechanism and said one commutator valve part together to resist relative rotational and axial movement therebetween. .Iaddend..Iadd. 57. A control unit as defined in claim 46 wherein said stop means comprises a stop for limiting rotational movement of said pivotal valve, said stop being engageable with a part of said pivotal valve after limited pivotal movement thereof from said neutral position. .Iaddend..Iadd. 58. A hydraulic control unit comprising means defining an inlet port and an outlet port,   an input shaft,   a metering mechanism operatively associated with said input shaft and controlling flow from the inlet port to the outlet port in a quantity which is proportional to the speed and extent of rotation of said input shaft,   said metering mechanism including a first gear element rotatable with said input shaft and a second gear element which can rotate and orbit about the central axis of said first element in response to rotation of said first element,   said first and second gear elements defining fluid chambers therebetween which have changing volumes during relative movement of said first and second elements,   control valve means including a pivotal control valve having a neutral position preventing flow from said inlet port through said metering mechanism to said outlet port and pivotal to an operating position upon rotation of said input shaft whereat said control valve means directs flow from said inlet port to some chambers of said metering mechanism and flow from other chambers of said metering mechanism to said outlet port, means connecting said control valve and said second gear element including a pivotal link drivingly connected with and disposed at an angle to the axis of rotation of said second gear element and said control valve to effect pivoting movement of said control valve upon rotation of said second gear element,   biasing means acting directly on said control valve for biasing said control valve to said neutral position, and   stop means for limiting the rotation of said control valve. .Iaddend.