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
1999-12-15
2001-11-13
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
C187S293000
Reexamination Certificate
active
06315081
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a technique of operating an elevator in emergency by using a charged power supply in case that a power supply from a commercial main power source is shut down in an elevator system, and more particularly, to an apparatus for controlling an operation of an elevator in a power failure which is capable of minimizing discharge amount of a charged power supply when an elevator is operated on the charged power supply in emergency and of preventing an over current from flowing, and to its method.
2. Description of the Background Art
In case that an elevator car is unexpectedly stopped between floors during its operation due to a power failure, the car is supposed to perform an emergency operation toward nearest floor so as to have passengers get off therefrom.
In preparation for such a power failure, in order to supply a power to the elevator system, a power supply unit is additionally provided to a control board, and the power supply unit typically has a charger and a charging battery where tens of volt of direct current power supply is normally charged.
That is, when a power failure state that a main power is not supplied is detected by the power supply unit, a direct current power supply charged in the charging battery is converted to an alternate current power supply, which is then converted to an alternate current power supply having the same frequency as that of the main power supply via a step-up transformer and an inverter, and is supplied to an input terminal of a rectifier, according to which the elevator system is operated in emergency.
FIG. 1
is a schematic block diagram of an apparatus for controlling an operation of an elevator in a power failure in accordance with a conventional art.
As illustrated in the drawing, the apparatus for controlling an operation of an elevator in a power failure in accordance with a conventional art includes a main power supply inputting contactor
2
for supplying a main power supply
1
in normal state by being closed or for blocking a power input path from the main power supply
1
in power failure by being opened, a rectifier
3
and a smoothing condensor
4
for converting alternate current input from an main power source to a direct current and smoothing it, a discharging transistor
5
and a resistor
6
for limiting a charged voltage of the condensor
4
from rising to more than a predetermined level, an inverter
7
for inverting a direct current voltage outputted from the smoothing condensor
4
according to an output signal from a pulse width modulation signal generator
20
(to be described later) to an AC voltage, current detectors
8
A,
8
B and
8
C for detecting a current supplied from the inverter
7
to an AC motor
9
, the AC motor
9
driven by an output power supply of the inverter
7
, a rotary encoder
10
for detecting a rotational speed of the motor
9
and outputting a pulse, a sheave
11
for receiving a driving force from a driving shaft of the alternate current motor
9
and winding or releasing an elevator car
13
in a vertical direction, a balance weight
12
connected to the elevator car
13
, having a predetermined weight so as for the car to be balanced, and vertically operated in the opposite direction to the elevator car
13
, a hall call button unit
14
for being pushed by passengers waiting on the hall of each floor and calling the elevator car
13
, a car call button unit
15
for passengers in the elevator car
13
to select destination floors, a load detector
16
for detecting a load amount of the elevator car
13
a power supply unit
17
with a charger for emergency operation of the elevator in case of a power failure, an operation control unit
18
for controlling an operation of the elevator system according to a hall call from the hall call button unit
14
or car call from the car call button unit
15
, a speed control unit
19
for outputting a speed control signal upon receipt of a speed command from the operation control unit
18
, and a pulse width modulation signal generator
20
for outputting a pulse width modulating signal upon receipt of the speed control signal.
The operation of the apparatus for controlling an operation of an elevator in accordance with the conventional art constructed as described above will now be explained.
In a normal operation that the main power
1
is normally supplied to the elevator system, the operation control unit
18
generates a speed command b
1
to operate the elevator according to a call from the hall call button unit
14
and the car call button unit
15
, computes a weight difference between the balance weight
12
and the elevator car
13
on the basis of the load amount of the elevator car
13
detected by the load detector
16
, and accordingly outputs a load compensation signal b
2
.
When the speed control unit
19
outputs a predetermined speed control signal to the pulse width modulation (PWM) signal generator
20
according to the speed command b
1
outputted from the operation control unit
18
, the pulse width modulating signal generator
20
controls the width of the pulse signal and outputs it to the inverter
7
. Then, the inverter
7
accordingly controls a rotation speed of the alternate current motor
9
.
The operation of the power supply unit
17
will now be described with reference to FIG.
2
.
A main power supply failure detecting unit
17
A monitors whether the main power supply
1
is supplied to the elevator system. When the main power is normally supplied to the elevator system, a battery voltage detecting unit
17
G checks a voltage of the charging battery
17
F, and if the voltage is lowered down to below a pre-set voltage level, the battery voltage detecting unit
17
G drives a battery charging control unit
17
I.
Accordingly, a predetermined pulse width modulating signal is outputted from the pulse width modulation signal generator
17
K, and accordingly a voltage from the main power supply
1
is sequentially charged through a transformer
17
C and a power converting unit
17
D.
In case that the power failure detecting unit
17
A detects a power failure state that the main power is not supplied to the elevator system, the main power input contactor
2
is turned off by a turn-off signal from a contactor drive unit
17
B.
At this time, the AC power supply control unit
17
J is operated so that the DC power charged in the battery
17
F is converted to an AC power through the inverter
17
D. Thus, the DC voltage from the battery
17
F is inverted to an AC voltage having the same frequency as the voltage of the main power via inverter
17
D, coils L
1
,L
2
,L
3
and the transformer
17
C and is outputted to the rectifier
3
.
As the power failure detecting unit
17
A detects the power failure and outputs a power failure detecting signal al to the operation control unit
18
, the operation control unit
18
switches a normal operation mode to a power failure operation mode to perform an emergency operation. And, when the emergency operation is completed, the operation control unit
18
outputs an operation completion signal to the power supply unit
17
, and accordingly, the operation of the power supply unit
17
is stopped.
Meanwhile, when the power supply unit
17
detects the power-failure and outputs a signal that the main power is not supplied to the elevator system to the operation control unit
18
, the operation control unit
18
computes a weight difference between the balance weight
12
and the elevator car
13
on the basis of the load detect signal of the load detector
16
.
In case that a weight of the balance weight
12
is heavier than that of the car
13
, the operation control unit
18
determines that the running direction of the elevator car
13
is to be an upward direction, and in the opposite case, it determines that the operation direction of the elevator car
13
is to be a downward direction, and then outputs a speed command b
1
to control the speed of the motor
9
.
When the car
13
is started to be operate
LG Industrial Systems Co. Ltd.
Salata Jonathan
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