Machine element or mechanism – Rotary member or shaft indexing – e.g. – tool or work turret – Preselected indexed position
Patent
1974-11-22
1978-04-04
Scott, Samuel
Machine element or mechanism
Rotary member or shaft indexing, e.g., tool or work turret
Preselected indexed position
60DIG2, 74740, 74859, 74860, B60K 4118, F16H 3700, F16D 3900
Patent
active
040820130
ABSTRACT:
An electronic control for a hydrostatic or hydromechanical transmission governs the transmission ratio as a primary function of a manual ratio request and as a secondary function of throttle setting, engine speed, pressure in the hydrostatic transmission and manual range selection. A ratio control signal is developed by comparing ratio request with the existing ratio control signal and integrating the difference to provide a smoothly changing ratio, and the rate of change is limited to a maximum value. Ratio change of the hydrostatic unit is carried out by varying the displacements of the hydrostatic pump and motor. The displacements are changed by servo motors electrically controlled by the electrical ratio signal. Synchronous range shifting in a gear set is accomplished by applying one torque transmitting device (e.g. brake or clutch) and releasing another torque transmitting device, each of which is fluid pressure operated. Pressure switches associated with each device determine whether it is applied or released. During range shifting, the hydrostatic unit is prevented from changing ratio until the shift is effected as indicated by the condition of the pressure switches. Engine speed is maintained within programmed limits by varying the ratio to prevent overspeed or underspeed. Shift logic and inhibit circuits responsive to manual range selection, transmission output speed, and the ratio control signal initiate range shifting only under desirable conditions.
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Analysis and Design of Feedback Control Systems, Thaler and Brown, McGraw-Hill and Co., 2nd Edition, pp. 82, 109 & 110.
Dornfeld Kenneth A.
Marlow Jerry R.
Sanders Robert K.
Chandler Lance W.
General Motors Corporation
Hill Warren D.
Scott Samuel
LandOfFree
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