Electricity: motive power systems – Constant motor current – load and/or torque control
Patent
1983-09-27
1985-12-31
Shoop, Jr., William M.
Electricity: motive power systems
Constant motor current, load and/or torque control
318314, 318566, 318635, 81 10, 81469, H02P 700
Patent
active
045623899
ABSTRACT:
To permit reliable turn-OFF of the motor when the torque of the motor is sufficient to provide for reliable seating of a screw or nut being driven thereby, start conditions of the motor are sensed, either in form of low-current condition or high power factor; high-torque conditions are sensed by low power factor, or high-current, in dependence on the desired torque level which results, respectively, in a comparatively steep phase angle-torque or current level-torque curve. A switch control is energized to turn-OFF the motor current if the phase angles, or the motor current, respectively, are beyond predetermined levels. To prevent in-rush current, or high power factors from affecting the operation of the turn-OFF system, timing circuits are provided to disable the turn-OFF system when the motor is first turned-ON or if the phase angle difference, as determined by time-comparator networks, between current and voltage, is below a predetermined value. Timing duration of at least one of the timing circuits can be controlled as a function of motor temperature to provide for linear response of the system, regardless of changes of motor operating parameter versus torque characteristics under varying motor temperature conditions.
REFERENCES:
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patent: 3477007 (1969-11-01), Ducommun et al.
patent: 3527991 (1970-09-01), Sackin
patent: 3892146 (1975-07-01), Yososhima
patent: 4056762 (1977-11-01), Schadlich
patent: 4066942 (1978-01-01), Bardwell et al.
patent: 4379986 (1983-04-01), Baxter et al.
patent: 4384243 (1983-05-01), Muskovac
patent: 4387329 (1983-06-01), Harlow
Jundt Wolfgang
Schaal Gunter
Schadlich Fritz
Vogt Hans-Joachim
Wunsch Steffen
Ro Bentsu
Robert & Bosch GmbH
Shoop Jr. William M.
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