| 摘要 |
1484926 Automatic control of speed OWENS-ILLINOIS Inc 23 Oct 1974 [24 Oct 1973] 45811/74 Heading G3R In a speed control system for a plurality of electric motors operating in parallel, each motor is automatically regulated to a predetermined speed which is changed if the speed of one of the motors falls below a minimum value. In the embodiment, each motor 10 is controlled by a system as shown in which pulses from a motor driven encoder 14, having a frequency dependent upon the motor speed, are counted at 58 for a given time period determined by time base generator 56. The count, which is indicative of motor speed, is normally compared in a binary comparator 74 with a predetermined desired value 22. Any difference is used to vary the position of a servo potentiometer 40 to maintain the motor at the desired speed. However if the speed of one of the motors falls below a minimum value, an emergency logic system 62, that is common to all motor control systems, causes binary switch 76 to change state. This changes the reference to comparator 74 from the desired speed 22 to an emergency speed 23, which may be above or below the desired speed 22. The motor is thus regulated to run at the emergency speed. Details of the time base generator 56, count and hold circuit 58, comparator 74 and emergency logic 62 are given in Figs. 3 to 6 (not shown). The system may be used to control motors in glass container inspection machines that run in parallel from a single container making machine, and, if one of the inspection machines stalls or is stopped for repair, the other machines are speeded up to avoid build up of containers. |
