Elevator – industrial lift truck – or stationary lift for vehicle – Having specific load support drive-means or its control – Includes control for power source of drive-means
Reexamination Certificate
1999-06-25
2001-03-20
Salata, Jonathan (Department: 2837)
Elevator, industrial lift truck, or stationary lift for vehicle
Having specific load support drive-means or its control
Includes control for power source of drive-means
C187S287000
Reexamination Certificate
active
06202795
ABSTRACT:
BACKGROUND
The present invention concerns a system for the automatic braking of an elevator car designed to stop it when it reaches or exceeds a limit speed of movement within a lift shaft.
Such automatic braking systems are already known which generally consist of a stop mechanism comprising a stop pulley designed to be driven in rotation at the same time as said car moves. Said stop pulley is designed to rotate freely when its speed of rotation is less than a threshold speed of rotation and to lock when its speed of rotation is equal to or greater than said threshold speed of rotation. They also comprise a mechanism for controlling the action of said brakes when said stop pulley is locked.
FIG. 1
shows an elevator installation equipped with a braking system according to the known state of the art. This installation consists essentially of an elevator car
10
which is moved between the different floors of an elevator shaft (not shown), for example by means of a machinery
20
acting on a cable or a cluster of traction cables
21
and having a counterweight
22
. The elevator car
10
is guided in its movement by lateral rails extending vertically in the elevator shaft and on which the car
10
bears through guides
31
. For reasons of clarity, only one of these rails
30
has been depicted in FIG.
1
.
The elevator car
10
has a control mechanism
11
provided for controlling the action of the brakes
10
and
13
depicted here schematically in the form of simple wedges, The brakes
12
and
13
act generally on the rails
30
of the elevator car
10
. These brakes
12
and
13
are also known in the art as “safety stop clamps”. They act one in one direction of movement of the car
10
, the other in the other direction.
As for the automatic braking system, this includes a stop pulley
50
which is mounted on the masonry in the top part of the elevator shaft and an endless cable
60
wound between the stop pulley
50
and a return pulley
51
. The endless cable
60
is tensioned by means of a tension weight
52
acting on the return pulley
51
.
A control mechanism
53
is fixed on the one hand to the endless cable
60
and on the other hand to the car
53
. In normal operation, that is to say when the speed of movement of the car
10
is less than a limit speed, the car
10
drives the cable
60
. The mechanism
53
is not stressed and therefore does not act on the control mechanism
11
of the brakes
12
and
13
.
On the other hand, when the speed of the car
10
reaches or exceeds a limit speed, the stop pulley
50
locks and the cable
60
is immobilised. The mechanism
53
is stressed since it is on the one hand immobilised by the cable
60
and on the other hand fixed to the car
10
, which is still moving. The effect of this stressing of the mechanism
53
is to actuate the control mechanism
11
, which then acts on the brakes
12
and
13
. These in return act on the rails
30
, which has the effect of immobilising the car
10
.
One of the drawbacks of the braking system of the state of the art presented above is its relatively large bulk because notably of the use of an endless cable, which has two parallel lengths for which it is necessary to reserve space in the elevator shaft.
The other drawback of this braking system lies in the fact that the stop pulley is necessarily mounted in the top part of the elevator shaft, generally on the same piece of masonry as that on which the drive motor
20
rests. The risks of accident related to this piece are therefore not covered by the braking system.
SUMMARY OF THE INVENTION
The aim of the present invention is to propose a braking system which does not have the drawbacks of the braking systems of the prior art, notably those disclosed above, and which is consequently more compact compared with those of the state of the art and which is not mounted on the same piece of masonry as that on which the drive motor rests.
To do this, according to one characteristic of the present invention, said stop mechanism is mounted on said car, said stop mechanism or part thereof being designed so as, in reaction to the movement of said car when said stop pulley is locked, to move relatively to said car in a direction substantially parallel to the direction of said car. Said control mechanism then acts on said brakes when said stop mechanism or said part thereof moves relatively to said car.
Advantageously, said stop pulley is driven by a control cable suspended vertically in the elevator shaft and passing through its groove.
According to a first embodiment of the present invention, said stop mechanism comprises two pulleys, one of which is said stop pulley, said control cable having its top vertical length passing through the bottom part of a first groove in one of said pulleys, then passing through the groove in the second pulley and then passing once again through the top part of the second groove in said first pulley.
Said first pulley can then constitute the part of the stop mechanism which, in reaction to the movement of said car when said stop pulley is locked, moves relatively to said car.
According to a second embodiment of the present invention, said stop mechanism comprises at least two pulleys, one of which is said stop pulley, said control cable passing through each of said grooves in said pulleys.
Said upstream pulley and said downstream pulley constitute the part of the stop mechanism which, in reaction to the movement of said car when said stop pulley is locked, moves relatively to the car.
According to another characteristic of the present invention, said stop mechanism or said part of said stop mechanism are mounted at the end of a pivoting arm, said arm, when moving away from its idle position, stressing the control mechanism, which then acts on said brakes.
According to another characteristic of the present invention, said stop mechanism or said part of said stop mechanism are mounted on channels extending substantially in the direction of movement of said car, said channel, moving away from its idle position, stressing the control mechanism, which then acts on said brakes.
According to another characteristic of the present invention, said stop mechanism or said part of said stop mechanism are provided with a retractable rod which can, when it is not retractable, come into contact with stops provided in said elevator shaft, which has the effect of moving said stop mechanism or said part of said stop mechanism relative to said car and to stress the control mechanism, which then acts on said brakes.
REFERENCES:
patent: 601301 (1898-03-01), Ihlder
patent: 632651 (1899-09-01), Johnson
patent: 1182240 (1916-05-01), Bemis
patent: 2511697 (1950-06-01), Clift
patent: 4928796 (1990-05-01), Poon
patent: 404365771 (1992-12-01), None
Laff, Whitesel & Saret, Ltd.
Salata Jonathan
Thyssen Ascenseurs SAS
Whitesel J. Warren
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