Patent ID: 7316297

Claim:
An escape device of an elevator including a car, a motor including normal coils and backup coils, a backup power supply for activating the backup coils by closing a switch in the car, a sheave driven by the motor, hoist ropes run in a grooved rim of the sheave, the hoist ropes having one end connected to the car, a counterweight connected to the other end of the hoist ropes, and a brake, comprising: a slow movement assembly comprising a rotatable shaft, a plurality of detents of cam section on the shaft, a bar on the shaft, first and second ropes each having one end fixed at either end of the bar, and a plurality of electromagnetic contacts; a control assembly on a wall of the car and connected to the first rope, the control assembly comprising a hollow, rectangular member with the first rope passed through, a backup electromagnetic contact for pivoting the member, a handle for pivoting the member, the handle including a series of parallel projections at its end proximate the member and a spring loaded detent urged against one of the projections, a link having one end connected to the member, a sliding connecting rod having one end loosely connected to the other end of the link, a guide sleeve put on the connecting rod, and a roller disposed externally of the car and connected to the other end of the connecting rod; and a return assembly on a wall of a vertical opening for the elevator and comprising a plurality of raised plates disposed laterally for guiding the roller; wherein in response to a stop of the elevator in case of power outage, a person trapped in the car is able to press the switch to cause the motor to switch to the backup coils and activate the backup generator at the same time, either: (i) the backup electromagnetic contact is enabled to activate the slow movement assembly and cause a first one of the detents to contact and disable the brake for rotating the drive shaft if the backup generator functions normally, the car is adapted to lower due to different heights of the counterweight and the car or (ii) the person trapped in the car manipulates the handle to activate the slow movement assembly if the backup generator malfunctions, the brake is disabled by contacting a first one of the detents for rotating the drive shaft to lower the car, the return assembly operates to return the slow movement assembly to its nonoperating position via the control assembly wherein the electromagnetic contacts are short-circuited sequentially by causing each of the remaining ones of the detents to contact a corresponding one of the electromagnetic contacts with a predetermined phase difference therebetween, the car slowly arrives at a nearest correct floor, and the trapped person is able to open a door to escape.