Elevator apparatus with brake control device
In an elevator apparatus, a brake device is controlled by a brake control device. The brake control device has a first brake control portion for operating the brake device to stop a car as an emergency measure upon detection of an abnormality, and a second brake control portion for reducing a braking force of the brake device when a deceleration of the car becomes equal to or larger than a predetermined value during emergency braking operation of the first brake control portion. The second brake control portion controls the brake device independently of the first brake control portion.
1. An elevator apparatus comprising:
a car;
a brake device for stopping the car from running; and
a brake control device for controlling the brake device, wherein:
the brake control device has a first brake control portion for operating the brake device to stop the car as an emergency measure upon detection of an abnormality, and a second brake control portion for reducing a braking force of the brake device when a deceleration of the car becomes equal to or larger than a predetermined value during emergency braking operation of the first brake control portion; and
the second brake control portion controls the brake device independently of the first brake control portion.
2. The elevator apparatus according to claim 1 , wherein:
the second brake control portion is validated when a speed of the car becomes equal to or higher than a first threshold; and
the second brake control portion is invalidated when the speed of the car becomes equal to a second threshold lower than the first threshold while the second brake control portion is valid.
3. The elevator apparatus according to claim 1 , wherein the second brake control portion is invalidated when the car reaches a vicinity of each of terminal floors.
4. The elevator apparatus according to claim 1 , wherein the second brake control portion is invalidated upon a lapse of a predetermined time after the deceleration of the car becomes equal to or Larger than the predetermined value during emergency braking operation of the first brake control portion.
5. The elevator apparatus according to claim 1 , wherein the second brake control portion has a first deceleration monitoring portion and a second deceleration monitoring portion for monitoring the deceleration of the car independently of each other, and reduces the braking force of the brake device only when a deceleration detected by both the first deceleration monitoring portion and the second deceleration monitoring portion becomes equal to or larger than the predetermined value.
6. The elevator apparatus according to claim 1 , wherein:
the brake device has a brake release coil for generating an electromagnetic force for canceling a braking force; and
the second brake control portion has a current limiting resistor connected in series to the brake release coil to limit a magnitude of a current flowing through the brake release coil.