DC motor mechanical shock protection system
AssigneeSquare D Company
InventorRodney B. Washington
Life of this patent
Estimating the term…
Abstract
A DC motor mechanical shock protection system monitors the motor current to determine the torque the motor is applying to the gearbox, and takes mitigating action if the torque approaches a level that can damage the driven device and/or the drive system. This protects the system from mechanical shock without limiting the available torque during normal operation. The change in motor current is monitored to detect the inertial torque before the elasticity between the motor and the driven device is fully compressed and the motor mounting or gearbox begin to be damaged.
Claims12
A method of controlling the torque produced by a DC motor having a rotor to protect a mechanical system driven by said motor, said mechanical system comprising a combination of gears, levers, cams and/or sliding components arranged for interactive movement and having a particular elasticity in that movement and a limit at which compression of said particular elasticity by said motor torque can damage said mechanical system, said method comprising:
- monitoring that portion of the motor torque produced by rotor inertia by sampling an electrical current supplied to said motor, filtering said sampled current to substantially remove commutation ripples, and establishing a first derivative of said filtered sample of said electrical current, said first derivative current representing an inertial torque applied to said system by said rotor;
- and
- adjusting said electrical current supplied to said motor to stop or reverse said motor in response to an increase in said rotor inertia torque that exceeds a preselected threshold value selected to protect said mechanical system from damage caused by compression of said mechanical system that exceeds said particular elasticity.
A method of protecting a mechanical system of gears, levers, cams and/or sliding components arranged for interactive movement when driven by a DC motor, said system having a particular elasticity in that movement and a limit at which compression of said particular elasticity by said motor can damage said mechanical system, said method comprising:
- sampling the electrical current supplied to said motor,
- filtering said sample to substantially remove commutation ripples,
- taking a first derivative of said sample,
- detecting increases in said first derivative sample in selected time intervals,
- comparing each of said detected increases with a preselected threshold, and
- stopping and/or reversing said motor in response to any said detected increase that exceeds said preselected threshold to protect said mechanical system.
A method of controlling the torque produced by a DC motor to protect a mechanical system of gears, levers, cams and/or sliding components arranged for interactive movement when driven by said motor, said system having a particular elasticity in that movement and a limit at which compression of said particular elasticity by said motor torque. can damage said mechanical system, said method comprising:
- monitoring the first derivative of the electrical current supplied to said motor, and
- adjusting the electrical current to stop and/or reverse said motor in response to a positive increase in said first derivative that exceeds a preselected threshold during a selected time interval to protect said mechanical system.
Dependencies are inferred from the claim text.