METHOD OF STOPPING CONVEYING EQUIPMENT FOR PERSONS

METHODE D'ARRET DE TRANSPORTEUR DE PERSONNES

English Abstract

The invention relates to a method for stopping conveying equipment for
persons, which
comprises a holding brake (3), wherein on response of the safety element a
braking ramp
(1) determined by a frequency converter (2) co-operating with a drive motor
(4) is
activated, by means of which the conveying equipment for persons is brought to
a
standstill, wherein the holding brake (3) is activated shortly before
standstill. The
operational safety of the braking system is thus increased.

French Abstract

L'invention concerne une méthode permettant l'arrêt de transporteur de personnes, qui comprend un frein d'arrêt (3), où, en réaction à l'élément de sécurité d'une rampe de freinage(1) déterminé par un convertisseur de fréquence (2) qui coopère avec un moteur d'entraînement (4), est actionné par un dispositif qui immobilise le transporteur de personnes, où le frein d'arrêt (3) est actionné peu de temps avant l'immobilisation. La sécurité opérationnelle du système de freinage est ainsi augmentée.

Claims

4
We Claim:
1. A method for stopping conveying equipment for persons having a holding
brake, a
drive motor, a frequency converter controlling the operation of the drive
motor and
braking, and a holding brake, wherein on activation of a safety element the
frequency
converter decreases the speed of the drive motor according to a pre-
established braking
ramp, the holding brake being activated before standstill of the conveying
equipment for
persons, wherein the holding brake is activated when the conveying equipment
for
persons has decreased to a speed of at least 0.1 m/s; and
wherein the frequency converter is switched off at or subsequent to the time
when
the holding brake is activated.
2. The method according to claim 1, wherein the speed of the conveying
equipment
for persons is constantly measured while the speed of the drive motor is being
decreased.
3. The method according to claim 1 or claim 2, wherein the holding brake is
activated
when the speed of the conveying equipment for persons has decreased to about
20% of
the normal speed of the conveying equipment for persons.

Description

CA 02414998 2010-07-16
Method of stopping conveying equipment for persons
The invention relates to a method for stopping conveying equipment for persons
having a
holding brake, a drive motor, a frequency converter controlling the operation
of the drive
motor and braking.
By conveying equipment for persons there are to be understood in this
application not
only escalators, but also moving walkways.
A method for braking rolling stairs or rolling walkways has become known from
specification DE-19803899 C2, in which on response of the safety element a
braking
ramp is activated by way of which the speed of the step belt or plate belt is
brought to the
value 0 m/s. The holding brake is activated at the instant of standstill of
the rolling stairs
or the rolling walkway.
In this solution the holding brake does not have an ideal braking function.
This means
that no friction braking takes place, which can lead to an unpredictable
operational safety
of the holding brake.
The invention has the object of proposing a method of the kind stated in the
introduction
which does not have the aforesaid disadvantages and which increases the
operational
safety of the holding brake.
The activation of the holding brake shortly before standstill of the conveying
equipment
for persons means that the holding brake is activated when the conveying
equipment for
persons is, in the case of retardation, still in motion, i.e. when the drive
motor is not yet
completely stopped. The holding brake is preferably activated at a speed of
approximately 20% of the normal speed of the conveying equipment for persons
so that a
friction braking also takes place. This controlled activation of the holding
brake increases
the operational safety of the operating system.
Advantageously, the frequency converter is switched off only when the holding
brake
comes into effect. This has the advantage that there is no jerking of the
motor, which can

CA 02414998 2010-07-16
2
be an unpleasant acceleration and a disturbing noise for the passengers. A
stopping,
which is optimised in that the manner, of the conveying equipment for persons
increases
travel comfort.
Advantageously, the holding brake is activated when the conveying equipment
for
persons has reached a speed of 0.1 m/s in the braking ramp. This has the
advantage
that the speed of the conveying equipment for persons is constantly monitored
and the
holding brake engages at the correct speed.
The invention further has the following advantages:
Due to the jerk free stopping of the motor, the drive system does not produce
any
unnecessary noise and is free of wear, whereby the service life of the
components is
increased.
In one aspect, the present invention provides a method for stopping conveying
equipment
for persons having a holding brake, a drive motor, a frequency converter
controlling the
operation of the drive motor and braking, and a holding brake, wherein on
activation of a
safety element the frequency converter decreases the speed of the drive motor
according
to a pre-established braking ramp, the holding brake being activated before
standstill of
the conveying equipment for persons.
In another aspect, the present invention provides a method for stopping
conveying
equipment for persons having a holding brake, a drive motor, a frequency
converter
controlling the operation of the drive motor and braking, and a holding brake,
wherein on
activation of a safety element the frequency converter decreases the speed of
the drive
motor according to a pre-established braking ramp, the holding brake being
activated
before standstill of the conveying equipment for persons, wherein the holding
brake is
activated when the conveying equipment for persons has decreased to a speed of
at
least 0.1 m/s; and wherein the frequency converter is switched off at or
subsequent
to the time when the holding brake is activated.
All explained features are usable not only in the respectively indicated
combination, but
also in other combinations or by themselves without departing from the scope
of the
invention.

CA 02414998 2010-07-16
2a
Examples of embodiment of the invention are illustrated in schematic drawings
and
explained in more detail in the following description, in which:
Fig. 1 shows a graphical illustration of the speed behaviour during stopping
of conveying
equipment for persons and
Fig. 2 shows a basic illustration of the braking system according to the
invention.
Fig. 1 shows a graphical illustration of a load-independent braking of the
step belt or plate
belt of an escalator or a moving walkway. There are two kinds of braking,
namely an
electrical braking and a holding brake. Electrical braking is used for the
operational
braking wherein a drive motor 4 is braked by way of a frequency converter 2
over a set
braking ramp 1. If the electrical braking is interrupted, then there is
further braking by the
holding brake 3. The holding brake 3 is an electromechanical brake, which
preferably acts
on the motor shaft in the drive motor 4 in mechanically positive manner. In
the case of

CA 02414998 2010-07-16
3
sole action of the holding brake 3, the brake travels defined in the
applicable
standards/guidelines are maintained.
The activation of the braking can take place by reason of an emergency stop or
a fault
response of a safety element. The speed v is indicated as a function of time
t, wherein the
normal speed of the conveying equipment for persons is denoted by vM. The
braking
ramp 1, which is activated by the frequency converter 2, defines a
predetermined braking
travel over a predetermined time t. The speed v of the conveying equipment for
persons is
thus brought to the value 0 m/s with a defined retardation. At the instant t0,
the braking
ramp 1 of the frequency converter 2 is activated and braked with substantially
uniform
deceleration. At the instant tl shortly before the stopping of the conveying
equipment for
persons, the holding brake 3 engages. This preferably happens at a minimum
speed of
0.1 m/s, which corresponds with approximately 20% of the normal speed vN. The
frequency converter 2 is switched off only when the holding brake has already
initiated its
action. The frequency converter is thus switched off when the motor 4 is
already stopped.
This leads to significant advantages for operation of the motor. The switching-
off of the
frequency converter 2, in fact, usually does not take place linearly. Jerks
occur, which can
lead to undesired noise or damage to the gears or disturbance at the mains.
Figure 2 shows a basic illustration of a braking system according to one
embodiment of
the invention. The frequency converter 2 is connected with the motor 4 by way
of
switching elements 5. The energy supply 6 supplies the frequency converter 2,
which is
disposed in operative connection with a control unit 7. The control unit 7 is
also disposed
in operative connection with the switching elements 5 as well as with a brake
magnet 8.
The monitoring of the safety elements, such as, for example, the safety
circuit, takes place
in the region of the control unit 7. The triggering of a safety element is
detected by the
control unit 7, which signals to the frequency converter 2 to initiate an
electrical braking,
i.e. a controlled, gentle braking process. Although the safety circuit is
interrupted by the
triggering of a safety element, the contacts of the switching elements 5 are
kept closed, so
that the frequency converter 2 can always act on the motor 4 during electrical
braking.
The speed of the conveying equipment for persons is constantly measured. This
can take
place, for example, by a rotational speed pick-up of the motor 4. The holding
brake 3
engages shortly before standstill of the conveying equipment for persons,
preferably at a
speed of 0.1 m/s.

Representative Drawing