Delayed safety braking apparatus for a servomotor control system

A servomotor control system comprising:

• a programmable control system;
• a servo amplifier connected for control by the programmable control system to effect a predetermined motion profile;
• a servomotor connected for control by the servo amplifier;
• a safety switch connected for detection by the programmable control system, the programmable control system controlling the servo amplifier to brake the servomotor upon detection of activation of the safety switch;
• and
• a delayed braking circuit disposed between the servo amplifier and the servomotor, the delayed braking circuit connected to detect activation of the safety switch, the delayed braking circuit acting to brake the servomotor upon failure of the programmable control system and the servo amplifier to brake the servomotor within a predetermined period of time after actuation of the safety switch.

A braking circuit for use in braking a servomotor that is connected for control by a servo amplifier, the braking circuit comprising:

• stop means for generating a stop signal having an active and an inactive state;
• a primary brake circuit for controlling the servo amplifier to brake the servomotor when the stop signal goes to the active state;
• at least one regenerative braking element;
• a relay disposed between the servo amplifier and the servomotor for through-connecting signals from the servo amplifier to the servomotor when the relay is in a first state and for disconnecting the signals from the servo amplifier from the servomotor when the relay is in a second state, the relay connecting the servomotor to the at least one regenerative braking element when the relay is in the second state;
• and
• actuation means for actuating the relay in response to the stop signal of the stop means to remain in its first state when the stop signal is in its inactive state and for actuating the relay to go to its second state a predetermined period of time after the stop signal goes to the active state.