Method of improving performance in a motor-driven system

#The present invention relates to motor-driven systems, and more particularly to a method of improving performance in a single-motor-driven system by providing at least two smaller motors in place of the single, larger motor, each of the at least two motors being characterized by a peak rate of acceleration significantly greater than that of the single, larger motor, and wherein the at least two smaller motors are operatively coupled in parallel to a common output shaft, the operative coupling adapted to efficiently translate the second peak rate of acceleration to the motor-driven device. The inventive method has numerous applications, including motion control applications, factory automation, testing and evaluation of automobile systems, such as anti-lock braking systems and transmission systems, etc.

#When large values of torque and power are required in a motor-driven system, the conventional solution is to use one, large, and hence more powerful motor in place of a smaller and less powerful motor. Due to the physical constraints imposed on motor design and manufacture, however, the ratio of torque to inertia deteriorates as motor size increases, resulting in a lower peak acceleration rates with increased motor size. Thus, while the torque and power of the larger engine may be more suited to meet the requirements of the motor-driven system, the peak acceleration rate for the motor that may be unacceptable for the system. To overcome this undesired side effect, it has been conventional practice to modify motor design, for instance through the use of state-of-the-art materials and motor construction techniques, in order to maximize the performance achievable in a single motor. However, these practices are oftentimes limited in their ability to achieve the desired or lower equivalent inertia, with unsatisfactory results, particularly in motor-driven systems where there is a requirement for higher peak acceleration rates, such as systems demanding rapid changes in motion. There consequently remains a continuing need to improve the performance of motor-driven systems beyond that level presently attainable.

#The present invention addresses and solves the problems discussed above, and encompasses other features and advantages, by providing a method for improving the performance attainable in a motor-driven system of the type characterized by a single motor driving an output shaft operatively coupled to a motor-driven device, the single motor characterized by a first power and a first peak rate of acceleration, the method comprising:

#The description herein makes reference to the accompanying drawings, wherein like reference numerals refer to like parts throughout the several views, and wherein:

#FIG. 1 diagrammatically represents the rotor of a servo-motor;

#FIG. 2 shows one exemplary means for combining multiple motors in accordance with the present invention;

#Referring now to the drawings, the present invention will be seen to most generally comprise a method for improving the performance attainable in a motor-driven system of the type characterized by a single motor driving an output shaft operatively coupled to a motor-driven device, the single motor characterized by a first power and a first peak rate of acceleration, the method comprising: Providing at least two motors in place of the single motor, each of the at least two motors characterized by a second peak rate of acceleration significantly greater than the first peak rate of acceleration, and the at least two motors further characterized by a combined power that is at least equivalent to the first power of the single motor; and operatively coupling the at least two motors in parallel to a common output shaft that is, in turn, operatively coupled to the motor-driven device, the operative coupling adapted to efficiently translate the second peak rate of acceleration to the motor-driven device. Resultantly, as has been surprisingly and unexpectedly discovered, the single output shaft is characterized by a second peak rate of acceleration significantly greater than the first peak rate of acceleration; that is, by combining multiple smaller motors in parallel, the higher individual performance of the physically smaller units translates into improved performance of the larger combined unit, while still providing the required torque and power for the motor-driven system.

#The peak acceleration rate of a motor directly relates to the ratio of peak torque to rotor inertia by the following formula:

#Peak Acceleration Rate (radians/sec2)=peak torque/rotor inertia (in compatible units)