Patent ID: 7762875

Claim:
An elevator system comprising: an elevator controller; a blower configured to supply air to or exhaust air from an elevator cage; a blower controller configured to control the blower through an inverter to adjust pressure inside the elevator cage according to alternative operation modes including an optimization mode in which the pressure changes at a constant rate during the movement of the elevator cage and a constant mode in which the pressure is kept constant during the movement of the elevator cage; a switch controller configured to switch on and off the blower to adjust pressure inside the elevator cage in a switching mode in which the blower is controlled by switching the blower on and off without using the inverter when the elevator controller determines that the blower does not have a problem and at least one of the blower controller and the inverter has a problem; and a mode switch configured to automatically select an alternative one of the optimization mode, the constant mode and the switching mode.