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US RE31,107 EGranted
Feedback shaft extending between swashplate and displacement control valve
AssigneeDeere & Company
InventorsJohn J. Kass, Donald O. Johannsen
Life of this patent
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AssigneeDeere & Company
InventorsJohn J. Kass, Donald O. Johannsen
Estimating the term…
A hydrostatic pump unit is located within a housing which serves also as a hydraulic fluid sump. A displacement control valve for controlling actuators for adjusting the angular position of a swashplate of the pump unit is mounted on the exterior of the housing. Disposed along the axis about which the swashplate is adjustable and joining the swashplate to a shiftable sleeve of the control valve is a feedback shaft which acts to return the valve to a null condition when the swashplate arrives at a commanded new displacement effecting position. The feedback shaft has a passage extending therethrough which acts as a drain connection between the valve and the sump defined by the housing. A check valve is located in the passage for preventing fluid from draining from the housing when the valve is disconnected from the feedback shaft for service.
[1. In an axial piston pump or motor and controls therefor including a pump or motor housing containing a swashplate mounted for angular adjustment, about a fixed axis, between a neutral position for effecting a zero fluid displacement, and various positions at varying angular distances from the neutral position for effecting increasing fluid displacement as the angular distance from its neutral position increases, at least one hydraulic actuator coupled to the swashplate for selectively adjusting the latter in response to receiving control fluid pressure, a source of fluid pressure, a fluid sump, a pilot-operated displacement control valve located exteriorly of the housing and having separate fluid ports respectively coupled to the source of fluid pressure, the sump and the hydraulic actuator and including an axially shiftable spool member located within an axially shiftable sleeve member with the spool and sleeve members normally occupying a centered position relative to each other wherein they cooperate to block the flow of fluid to and from the actuator, a valve controller connected to the spool member for shifting the latter axially relative to the sleeve member a distance corresponding to an input command signal received by the valve controller and a feedback linkage connected between the swashplate and the sleeve member for shifting the latter axially to restore the centered relationship between it and the valve spool member in response to the swashplate moving to a new position corresponding to the input command signal, the improvement residing in the feedback linkage and comprising:
[2. The axial piston pump or motor and controls therefor defined in claim 1 wherein the housing serves as the sump and wherein a drain passage extends lengthwise through the feedback shaft and serves as the sole connection between the sump and the control valve.]
[3. The axial piston pump or motor and controls therefor defined in claim 2 wherein a check valve is located in said drain passage for preventing fluid from flowing from the case toward the control valve, whereby the control valve may be disconnected from the feedback shaft and removed for servicing without a substantial amount of fluid being lost from the case.]
[4. The axial pump or motor and controls therefor defined in claim 1 wherein the feedback shaft is connected to the swashplate by means of a spherical ball stud fixed to one of the sleeve members and feedback shaft and received in a hole provided in which ever one of the sleeve members and feedback shaft that does not have the stud fixed thereto.]
[5. The axial piston pump or motor and controls therefor defined in claim 4 wherein the control valve includes a valve housing;
[6. The axial piston pump or motor and controls therefor defined in claim 1 wherein the connection of the feedback shaft to the swashplate is an interference connection and includes at least one pair of diametrically opposite, resiliently deflectable, axial projections at an end of the feedback shaft and a receptacle shaped complementary to the end of the feedback shaft and including a pair of grooves respectively receiving the pair of projections in a resiliently deflected condition whereby a tight interference fit is established.]
[7. The axial piston pump or motor and controls therefor defined in claim 6 wherein each of the pair of axial projections is provided with an axial notch to enhance its resiliency.]
[8. In a control for selectively adjusting a swashplate of an axial piston pump or motor angularly about a first axis, and including a hydraulic actuator means coupled to the swashplate;
[9. The axial piston pump or motor and controls therefor defined in claim 8 wherein the connection of the feedback shaft to the swashplate is an interference connection and includes at least one pair of diametrically opposite, resiliently deflectable, axial projections at an end of the feedback shaft and a receptacle shaped complementary to the end of the feedback shaft and including a pair of grooves respectively receiving the pair of projections in a resiliently deflected condition whereby a tight interference fit is established.]
[10. The axial piston pump or motor and controls therefor defined in claim 9 wherein each of the pair of axial projections is provided with an axial notch to
In a control for selectively adjusting a swashplate, of an axial piston pump or motor, angularly about a first axis and including a hydraulic actuator means coupled to the swashplate;
In a control for selectively adjusting a swashplate, of an axial piston pump or motor, angularly about a first axis and including a hydraulic actuator means coupled to the swashplate and located together within a transmission housing;
Dependencies are inferred from the claim text.