Patent Application
20210403286
The present invention relates generally to an elevator safety device, and more particularly to a safety link of a safety device that automatically stops an elevator car from travelling when the descending speed of the elevator car exceeds a predetermined speed.
Most elevators have a safety device that works in conjunction with a governor to prevent the risk of the elevator car falling in the event of an unexpected situation such as a malfunction of the elevator drive motor, disconnection of elevator ropes, etc.
Specifically, a governor is arranged at a predetermined position such as in a machine room or in a hoistway of the elevator. The governor is equipped with an endless governor rope extending throughout the hoistway so as to move in conjunction with the elevator car moving upwardly or downwardly.
The governor is configured to detect the moving speed of the elevator car by detecting the moving speed of the governor rope connected to the elevator car. When the governor detects that the descending speed of the elevator car exceeds a predetermined speed, the governor grips the governor rope and pulls the governor rope upward with respect to the elevator car, causing a safety device to actuate via a safety link mounted on the elevator car.
When the safety device is actuated, free running time may be generated due to the delay of safety link operation, and in the worst case, descending speed of the elevator car may reach its maximum speed of 1G, which may delay the stop of the elevator car.
Therefore, there is a need for an improved safety link that prevents acceleration in descending speed of an elevator car due to the time lag between detection of a downward overspeed condition of the elevator car and the actuation of the safety device.
According to one aspect of the present invention, a safety link for an elevator traveling in an elevator hoistway is provided. The elevator includes a governor assembly and a governor rope extending throughout the hoistway. The safety link includes a hitch bracket slidably mounted to the elevator car frame so as to be movable in the moving directions of the elevator car and biased toward the downward movement direction of the elevator car in normal operating condition, the hitch bracket connected to the governor rope, a pulley rotatably mounted to the hitch bracket, and an actuation wire wrapped around the pulley. One end of the actuation wire is fixed to the elevator car frame so that the one end is directed downwardly relative to the pulley and the other end of the actuation wire is directed downwardly and connected to a safety device that stops the movement of the elevator car in the event of a downward overspeed condition.
In some embodiments, the safety link further includes a base bracket mounted to the elevator car frame to slidably hold the hitch bracket.
In some embodiments, the actuation of the governor rope in the event of a downward overspeed condition causes the hitch bracket to move upward, causing the pulley to pull upward relative to the base bracket, and thereby pulling the actuation wire to actuate the safety device.
In some embodiments, the movement of the actuation wire is twice as much as the corresponding movement of the governor rope.
In some embodiments, the actuation wire is wrapped 180° around the pulley.
In some embodiments, the actuation wire has a 2:1 roping configuration with the pulley.
In some embodiments, the hitch bracket is guided by a guide slot arranged in the hitch bracket and a guide bolt that slidably connects the hitch bracket through the guide slot to the elevator car frame.
In some embodiments, the safety link is arranged near the bottom of the side surface of the elevator car frame.
In some embodiments, the governor rope is connected to the hitch bracket by means of bolts.
In some embodiments, the safety device comprises a pair of safeties mounted on either side of the elevator car frame for applying a braking force to a pair of guide rails in response to the actuation of the governor rope.
In some embodiments, the pair of safeties are linked together through a second actuation wire.
According to another aspect of the present invention, a safety link for an elevator traveling in an elevator hoistway is provided. The elevator includes a governor assembly and a governor rope extending throughout the hoistway. The safety link includes a hitch bracket slidably mounted to the elevator car frame so as to be movable in the moving directions of the elevator car and biased toward the downward movement direction of the elevator car in normal operating condition, the hitch bracket connected to the governor rope, a pulley rotatably mounted to the hitch bracket, and an actuation wire wrapped around the pulley and connected to a safety device for actuation in response to the upward movement of the governor rope. The actuation wire has a 2:1 roping configuration with the pulley and the movement of the actuation wire is twice as much as the corresponding movement of the governor rope.
In some embodiments, the safety link further includes a base bracket mounted to the elevator car frame to slidably hold the hitch bracket.
In some embodiments, the actuation of the governor rope in the event of a downward overspeed condition causes the hitch bracket to move upward, causing the pulley to pull upward relative to the base bracket, and thereby pulling the actuation wire to actuate the safety device.
In some embodiments, the hitch bracket is guided by a guide slot arranged in the hitch bracket and a guide bolt that slidably connects the hitch bracket through the guide slot to the elevator car frame.
In some embodiment, the safety link is arranged near the bottom of the side surface of the elevator car frame.
In some embodiment, the safety device comprises a pair of safeties mounted on either side of the elevator car frame for applying a braking force to a pair of guide rails in response to the actuation of the governor rope.
In some embodiments, the pair of safeties are linked together through a second actuation wire.
These and other aspects of this disclosure will become more readily apparent from the following description and the accompanying drawings, which can be briefly described as follows.
The elevator system generally includes a governor 4 for limiting the speed of the elevator car 1 installed in the hoistway. The governor 4 includes a governor sheave (not shown) generally located at the top of the hoistway or in a machine room, a tension sheave (not shown) located at the bottom of the hoistway, and an endless governor rope 5 wrapped around the governor sheave and the tension sheave. The governor rope 5 extends along the hoistway between the governor sheave and the tension sheave in a looped manner. As shown in
As shown in
The hitch bracket 8 also comprises a rotatably mounted pulley 12 configured such that an actuation wire 13 with its one end 13a fixed to the base bracket 7 is directed upward to the pulley 12, wrapped 180° around the pulley 12 and then directed downward through the base bracket 7 for connection to a safety device 14 with the other end 13b of the actuation wire 13 as shown for example in
Referring now to
A safety device equipped with the safety link 2 of the present invention is operated as follows. In the event that the elevator car 1 moves downwardly at a speed higher than a predetermined speed, the governor 4 operates to exert a braking force on the governor sheave (not shown), which causes the governor rope 5 in
As shown in
Since the moving distance of the actuation wire 13 is converted to twice the upward movement of the governor rope 5, the activation time required by the safety device 14 will be half that of conventional models. It makes it possible to prevent an increase in elevator car downward movement speed due to a time lag between detection of the elevator car descending at extremely high speed and the actuation of the safety device 14. The present invention can provide a safety device that stops the movement of the elevator car at much faster rate than a conventional safety device.
In accordance with the present invention, the safety link 2 with an actuation wire 13 configured with 2:1 roping allows for a higher-speed response to the event of the elevator car to travel at an excessive speed and allows for faster operation of the safety device 14. Furthermore, since the load applied to the tension bracket 16 and the safeties 14a, b is halved by the 2:1 roping, the present invention can provide a simple and lightweight safety link mechanism while eliminating the risk of damaging the elevator equipment due to a large amount of load applied to the safety device in the event of a downward overspeed condition.
While the present invention has been particularly shown and described with reference to the exemplary embodiments as illustrated in the drawings, it will be recognized by those skilled in the art that various modifications may be made without departing from the spirit and scope of the invention as disclosed in the accompanying claims.
