Single rope elevator governor

Details Single rope elevator governor Single rope elevator governor

2000-05-22

2001-11-20

Brahan, Thomas J. (Department: 3652)

Elevator, industrial lift truck, or stationary lift for vehicle

Having specific means contacting or on load support for...

Includes movable contact component on support for engaging...

C188S188000

Reexamination Certificate

active

06318506

ABSTRACT:

FIELD OF THE INVENTION
This invention relates generally to elevator safety systems, and in particular to a governor for sensing an over speed condition in an elevator system.
BACKGROUND OF THE INVENTION
A typical traction elevator system used in buildings includes a cab that is supported upon a hoist rope. The hoist rope, in turn, is passed over a motor driven drive sheave and the other end of the rope is connected to a counterweight. As the drive sheave is turned, the cab unit and the counterweight unit move vertically along guide rails in opposite directions. The counterweight generally has a weight equal to that of the cab unit plus some additional weight which is a percentage of the cab's rated load capacity.
Safety systems are installed to prevent potentially dangerous over speeding of the cab. To this end, safety units, generally referred to as “safeties”, are provided to bring the cab to a controlled halt any time an over speed condition is detected. Safeties generally employ clamps, wedges, rollers or combinations thereof that apply a holding force against the guide rails of the cab unit and/or the counterweight unit to bring the cab to a rapid, safe halt.
In most cases, a governor is used to sense the occurrence of an over speed condition and take some type of responsive action to activate the safeties on both the cab unit and the counterweight unit. As shown in
FIG. 1
, the governor unit
10
that is in wide use today, includes a pair of governor ropes
11
,
13
, one of which is connected to the elevator cab
12
and the other of which is attached to the counterweight unit
14
. Each governor rope passes over an upper sheave
15
,
16
and a lower sheave
17
,
18
to create a pair of endless loops. Weights
19
and
10
are suspended from the lower sheaves which serve to tension the associated governor rope and maintain the opposed runs of each governor rope in parallel alignment. The governor ropes are connected in a well known manner with safeties
22
associated with each of the units. A governor brake
24
is associated with each governor unit which is adapted to engage the governor rope when the speed of the rope exceeds a given velocity. An over speed condition may be detected by flyweights or electrical sensors which activate the governor brake slowing the governor rope down. This, in turn, trips the unit safeties bringing the elevator to a halt.
This type of prior art governor works extremely well in practice, as evidenced by the safety record of traction elevators. However, as should be evident from the disclosure above, the system requires a separate governor rope for both the cab unit and the counterweight unit. This, in turn, is space consuming, increases installation and maintenance time, and increases the overall cost of the system.
SUMMARY OF THE INVENTION
It is a primary object of the present invention to improve traction elevator systems.
It is a further object of the present invention to improve governors employed in elevator systems.
A still further object of the present invention is to reduce the number of component needed in as elevator governor.
Another object of the present invention is to provide an elevator governor that requires only a single governor rope for sensing an over speed condition and activating the safeties on both the cab unit and counter weight unit of the system.
Yet another object of the present invention is to reduce the amount of space an elevator governor requires within a hoist way.
These and other objects of the invention are attained in an elevator system having a cab unit that is movably suspended between a first pair of guide rails that is connected by a hoist rope to a counter weight unit that is movably suspended between a second pair of guide rails. Safeties are mounted upon both units which are adapted to brake against the guide rails when an over speed condition is detected. A single governor rope is trained in an endless loop over an upper sheave and a lower tensioning sheave so that two parallel vertically disposed runs of rope pass between the two units. The rope is attached to one of the units so that it travels of the same speed as the units. A bidirectional governor brake is operatively associated with the upper sheave of the governor rope for applying a braking force to the rope in the event an over speed condition is encountered. Safety actuators in the form of lever arms are connected to the governor rope which are arranged to trip the safeties when the governor rope is braked to bring the elevator cab to a rapid and safe halt.


REFERENCES:
patent: 1242394 (1917-10-01), Venn
patent: 5183979 (1993-02-01), Sheridan et al.
patent: 5458216 (1995-10-01), Tanaka et al.
patent: 5617933 (1997-04-01), Ericson

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