EP2738132A1 - Lift assembly - Google Patents

Abstract

The lift system (100) has a cage (10) and a counterweight (12), where the cage and the counterweight are connected with each other via cables (14) that is guided by a drive pulley (16). The drive pulley is coupled with an electric machine (20) which is configured to operate as an electric motor for driving the drive pulley and for moving the cage and the counterweight. The electric machine is configured to operate as a generator for recovering the electrical energy as a result of rotation of the drive pulley.

Description

The invention relates to an elevator installation with a traction sheave drive.

In such an elevator system there is a counterweight to the car in which persons and / or loads are carried. The car and the counterweight are connected to each other via support cables, which are guided over a traction sheave. At the traction sheave engages an electric machine, the traction sheave is thus coupled to the electric machine. In addition to the function of the electric machine as an electric motor for the purpose of driving the traction sheave, so that the frictionally engaged with the traction sheave ropes are moved and thus the car and the counterweight are moved, the electric machine can also be operated as a generator. This is possible if the heavier element of car and counterweight is to be moved down. In this case, the traction sheave even prevents a too fast shutdown of the heavier element: As the traction sheave rotates, electrical energy is gained.

The energy can basically be fed back into a consumer network. For the operator of an elevator system, however, it is most efficient if the electrical energy obtained is supplied to an electrical energy store of the elevator installation in order to be later removed again for the operation of the electrical machine as an electric motor.

As an electrical energy storage, for example, a capacitor of particularly large capacity is previously provided.

A particularly suitable location at which the electrical capacitor is provided is a frequency control device (or frequency converter): such a frequency control device receives the three-phase mains voltage and has a rectifier stage to rectify this three-phase mains voltage. This DC voltage is stored in the so-called "DC link" of the frequency control device, which is usually formed by said capacitor of large capacity. This DC link is followed by an inverter stage, which converts the rectified voltage back into an AC voltage, but with a different frequency than the mains frequency. The frequency is variably generated by a microcontroller of the frequency control device, depending on the speed with which the elevator drive motor is about to turn. The current intensity of the current flowing through the drive motor, which is necessary to keep the frequency specified by frequency, is controlled by said microcontroller. The energy store may be connected to a first pole at a tap between the rectifier and the inverter with a second pole on a ground line.

Now it is desirable to be able to store energy to a particularly great extent. On the other hand, space-consuming energy storage devices take up little space, especially in the case of an elevator installation without an operating room.

It is the object of the present invention to improve the energy efficiency of an elevator system of the type described above and to take into account a limited space.

The object is achieved by an elevator system with the features according to claim 1.

According to the invention thus the electrical energy storage is provided as a counterweight or is at least part of the same.

The fact that the electrical energy storage forms the counterweight or is part of the same, no separate space outside the elevator shaft for this electrical energy storage must be created. A counterweight is to be provided anyway; typically, it weighs as much as the empty car plus half the rated load. Here there is enough scope for a complex energy storage.

In particular, the idea of the invention makes it possible to provide a plurality of rechargeable batteries, such as lead-acid batteries, as electrical energy store. Such accumulators are particularly heavy; compared to a conventional counterweight made of steel, for example, they do not occupy much more space than this counterweight. In particular, the lead and lead oxide present in lead-acid batteries has a high specific gravity.

In a preferred embodiment, the electrical energy store in this case comprises between thirty-six and forty-five, preferably forty-two 12 V accumulators. Conventional lead-acid batteries have a rated voltage of 12 V, and in series connection of said number of 12 V batteries to obtain such operating voltages, as they are conventionally used in elevator systems.

In a preferred embodiment of the invention, the electric machine and the counterweight are electrically connected to each other via a suspended electrical cable; then electrical current can flow between the energy storage as or in the counterweight and the electric machine. Alternatively or additionally, it is possible that the car and the counterweight are electrically connected to each other via a hanging electrical cable. In this way, electric energy can be supplied to consumers in the car from the counterweight.

In order to allow electric current to flow from the counterweight depending on the position of the elevator car to a consumer outside the counterweight, provision may also be made for the counterweight - as is known per se from the prior art - to be guided in rails , As a measure, it is then provided in this aspect of the invention that at least one rail is electrically coupled to a voltage pole of the electrical energy store.

As already mentioned, the electrical energy store is preferably contacted so that it is electrically connected between the rectifier and the inverter of a frequency control device and thus forms the DC intermediate circuit of the frequency control device.

• Der Mikrokontroller steuert drei Leistungshalbleiter an, die aus der Gleichspannung des Zwischenkreises wieder sinusförmigen 3-phasigen Drehstrom machen. Die Frequenz dieses Drehstroms ist dabei variabel und kann vom Mikrokontroller innerhalb gewisser Grenzen frei gewählt werden. Ziel dieser Vorgehensweise ist es, den Drehstrom-Antriebsmotor immer genau mit der Drehzahl drehen zu lassen, die von der Frequenz des Drehstroms vorgegeben wird. Dann ist nämlich der Wirkungsgrad des Motors am höchsten.
• Die Veränderung der Drehfrequenz ist für den Frequenzregler also das Mittel, um den Aufzug vom Stillstand bis zur Nenngeschwindigkeit, und wieder zurück zum Stillstand, lastunabhängig immer genau nach einer vorgegebenen Fahrkurve (Drehzahlkurve) stufenlos zu bewegen. Zusätzlich regelt der Mikrokontroller die Stromstärke des Stroms durch den Motor, sodass niemals mehr Strom fließt, als unbedingt nötig ist, damit die Drehzahl des Motors der vorgegebenen Drehfrequenz des Drehstroms gemäß der Drehzahlkurve folgt.
• Dazu wird durch den Mikrokontroller eine Pulsbreitenmodulation der drei Phasen des erzeugten Drehstroms verwendet. Jede Phase wird mit einer Periodizität von typisch 12kHz bis 16kHz (hängt von der Baugröße des Gerätes ab) andauernd ein- und ausgeschaltet, also "gepulst". Wenn das Regelgerät mehr Strom fließen lassen will, so lässt es die Einschaltdauer der Impulse länger, die Impulse also breiter werden, und umgekehrt. Um zu wissen, ob nun mehr oder weniger Strom nötig ist, hat der Motor einen Sensor (Inkrementaldrehgeber), den das Regelgerät auswertet. Das Regelgerät prüft also andauernd, ob die Drehzahl des Motors gegenüber der angesteuerten Drehfrequenz zu langsam ist, oder nicht. Ist der Motor zu langsam, wird die Stromstärke, die auf den Motor gegeben wird, erhöht. Ist der Motor zu schnell, so wird diese Stromstärke verringert. Dabei kann der Strom auch negativ werden, was bedeutet dass der Motor nun als Generator arbeitet und damit bremst. Auch dieser erzeugte Strom wird geregelt, und damit auch die Bremswirkung des Motors. Das Ganze immer mit dem Ziel, den Motor immer genau so schnell drehen zu lassen, wie es der vorgegebenen Fahrkurve (Drehzahlkurve) entspricht, die die Drehzahl in Abhängigkeit von der Zeit oder dem Weg angibt. Der erzeugte Strom gelangt über die Leistungshalbleiter wieder in den Gleichstromzwischenkreis und bewirkt, dass die Spannung in diesem ansteigt. Die Akkumulatoren in dem Zwischenkreis werden geladen.
• Bei einer bevorzugten Ausführungsform der Erfindung ist zumindest eine elektrische Verbrauchereinrichtung, die sich in oder an dem Fahrkorb befindet, elektrisch mit einem Akkumulator oder einer Reihenschaltung aus einer Mehrzahl von Akkumulatoren gekoppelt oder koppelbar, um einen Notstrombetrieb zu ermöglichen. Auf diese Weise wird der elektrische Energiespeicher gleichzeitig als Notstromvorrichtung einsetzbar.

To explain the operation of a frequency control device:

• The microcontroller controls three power semiconductors that make sinusoidal three-phase current from the DC voltage of the DC link. The frequency of this three-phase current is variable and can be freely selected by the microcontroller within certain limits. The aim of this procedure is always to let the three-phase drive motor rotate exactly with the speed, which is determined by the frequency of the three-phase current. Then the efficiency of the engine is highest.
• The change in the rotational frequency is therefore the means for the frequency controller to steplessly move the elevator from standstill to rated speed, and back again to standstill, exactly according to a given travel curve (speed curve). In addition, the microcontroller controls the current through the motor so that there is never more current than is absolutely necessary for the motor speed to follow the predetermined rotational frequency of the three phase current according to the speed curve.
• For this purpose, a pulse width modulation of the three phases of the generated three-phase current is used by the microcontroller. Each phase is constantly switched on and off with a periodicity of typically 12kHz to 16kHz (depends on the size of the device), ie "pulsed". If the control device wants to allow more current to flow, it makes the duty cycle of the pulses longer, ie the pulses become wider, and vice versa. To know whether more or less power is required, the motor has a sensor (incremental encoder), which the controller evaluates. The control unit checks So constantly, whether the speed of the motor is too slow compared to the selected rotational frequency, or not. If the engine is too slow, the current given to the motor will be increased. If the engine is too fast, this current is reduced. The current can also be negative, which means that the engine now works as a generator and thus brakes. Also, this generated power is regulated, and thus the braking effect of the engine. The aim is always to let the engine always rotate just as fast as it corresponds to the given travel curve (speed curve), which indicates the speed as a function of time or the way. The generated current passes through the power semiconductors back into the DC link and causes the voltage increases in this. The accumulators in the DC link are charged.
• In a preferred embodiment of the invention, at least one electrical load device located in or on the car is electrically coupled or couplable to an accumulator or a series circuit of a plurality of accumulators to enable emergency power operation. In this way, the electrical energy storage can be used simultaneously as an emergency power device.

In this case, it is provided in one embodiment that at least two electrical load devices, which have different values for a DC operating voltage, are coupled to a different number of one or more accumulators (which are then connected in series).

• Fig. 1 in einer halbschematischen Darstellung eine erfindungsgemäße Aufzugsanlage veranschaulicht,
• Fig. 2 ein bei der Aufzugsanlage aus Fig. 1 eingesetztes Frequenzregelgerät veranschaulicht,
• Fig. 3 zu einer Ausführungsform der erfindungsgemäßen Aufzugsanlage zeigt, wie eine elektrische Spannung an dem Gegengewicht abgegriffen werden kann, und
• Fig. 4 eine elektrische Verschaltung mehrerer Verbrauchereinheiten mit einer Reihenschaltung von Bleiakkumulatoren veranschaulicht.

Hereinafter, a preferred embodiment of the invention will be described with reference to the drawings, in which

• Fig. 1 illustrates in a semi-schematic representation of an elevator system according to the invention,
• Fig. 2 one at the elevator system Fig. 1 used frequency control device illustrates
• Fig. 3 to an embodiment of the elevator system according to the invention shows how an electrical voltage can be tapped on the counterweight, and
• Fig. 4 illustrates an electrical interconnection of multiple consumer units with a series circuit of lead-acid batteries.

A generally designated 100 elevator system comprises a car 10 and a counterweight 12, which are coupled to each other via support cables 14. The support cables 14 are guided over a traction sheave 16 and received there by frictional engagement. There may be provided a further deflection roller 18. The traction sheave 16 is coupled to an electric machine 20, which in conventional operation is powered by three-phase power, shown symbolically and designated 22. The three-phase alternating current from the public network is supplied to a frequency control device 24, which individually in Fig. 2 is shown. In the frequency control device, there is a rectifier 26, which rectifies the three-phase alternating current to a DC voltage of about 500 volts. Now, the speed of a rotor 30 of the electric machine and thus the speed of the traction sheave 16 is detected by means of a speed sensor 28 (which operates, for example, incrementally and at the same time detects the speed direction) and sends a corresponding measurement signal to a microcontroller 32 of the frequency control device 24. It is the task of the microcontroller 32 to drive three semiconductor switches 36, and this by pulse width modulation with a predetermined according to a speed curve parameterization. A sensor 28 on the rotor 30 of the motor is used in the context of a regulation of the speed to the value specified by the speed curve.

But it should also be given by the entire arrangement the opportunity to recover energy during operation of the elevator system. This is especially possible when the car 10 is loaded so heavily that it is heavier than the counterweight 12, and at the same time to be lowered. This is also the case when the car 10 is lightly loaded, so that the counterweight 12 is heavier than the car, and when the car 10 is driven up. In these two cases, the electric machine 20 can be operated as a generator: it then carries back electricity, whereby the inverter stage 34 of the frequency control device 24 can also be used here. So that the energy does not have to be fed back into the public grid 22, an electrical energy store 38 is connected between a tap 40 and a ground line N to form a DC intermediate circuit, the tap 40 being located exactly between the rectifier 26 and the inverter stage 34.

In the elevator installation 100 it is provided that the electrical energy store 38 is provided in the form of a total of forty-two lead-acid batteries B1, B2, B3,..., B42, which are connected in series and form or are part of the counterweight 12.

The lead of lead-acid batteries has a high specific gravity and is therefore particularly suitable for use in a counterweight. Here only the appropriate measure must be taken, as electric current can flow to the up and down moving counterweight and back again.

In one embodiment, the counterweight is provided via a hanging cable 42 having an electrical connection in the region of a wall 44 of the hoistway. Likewise, a hanging cable (alternatively or additionally) may also be routed to the car 10 (not shown in the drawing).

Based on Fig. 3 explains that in one embodiment, the counterweight 12 with the lead-acid batteries B1, B2, etc. in guide rails 46a, 46b is guided on two walls 44a, 44b of the elevator shaft. In this case, guide pins or guide plates 48a, 48b engage in recesses 50a, 50b of the guide rails 46a, 46b. Now, the guide rails 46a and 46b made of electrically conductive material, in particular metal, and electrically connected to the frequency control device 24 in a manner not shown in the figure. The guide pins or plates 48a, 48b are also made of metal and contact the guide rails 46a, 46b in areas 52a, 52b.

In one variant, both guide rails 46a, 46b are grounded. Then, the other pole of the lead-acid batteries B1, B2,... Is connected to the frequency control device 24 via a suspended cable. In another variant, different poles of the series connection of the lead-acid batteries B1, B2,... Are connected to the guide rail 46a on the one hand and the guide rail 46b on the other hand.

The use of 12 V lead-acid batteries B1, B2,..., B42 has the advantage that not only a single voltage tap is possible, but at one in Fig. 4 shown series connection of the individual lead-acid batteries B1, B2, B3, etc. different voltage taps can be done:
Based on Fig. 4 It can be seen that an electrical consumer device V1 is coupled to a tap between the first lead-acid battery B1 and the second lead-acid battery B2, so that a voltage of 12 V is available through the first lead-acid battery B1. The electrical consumption device V1 is in particular an emergency call device that is used in the car 10; then, of course, the taps must be guided to the car 10, in particular by hanging cables, in the case of Fig. 1 for example, by a hanging cable 54 from the car 10 to a port 56 on the wall 44 of the elevator shaft.

A second consumer device V2 receives voltage from a series connection of the lead-acid batteries B1 and B2, ie a DC voltage of +24 V. This second consumer device is, for example, a control device for the operation of the elevator installation. In Fig. 1 If this control device V2 is shown as part of the car 10, it may, however, also be arranged outside the car 10.

A third consumer device V3 receives electrical voltage through a series connection of the lead-acid batteries B1, B2 and B3, thus a potential of + 36 V. The third electrical consumer device V3 is, for example, electric motors for opening and closing car doors 58a, 58b of the car 10 ,

A fourth consumer device V4 receives the voltage from a series connection of 17 lead-acid batteries B1, B2, B3,..., B17, thus an electric potential of + 204 V. The fourth electrical consumer device is, for example, the two Electromagnets for opening the two holding brakes 60 on the drive motor for the purpose of driving the elevator. These holding brakes hold the elevator even without energy supply at a standstill (by guided compression springs) so that it does not set itself in motion in the most prevalent imbalance between the car and counterweight. For the elevator to drive, these brakes 60 must be opened by electromagnet. Also for emergency rescue trapped persons in case of power failure, the brakes 60 must be opened, which is why a battery-buffered auxiliary voltage is provided.

A fifth electrical load device V5 is fed by a series circuit of 19 lead-acid batteries B1, B2, B3,..., B17, B18, B19, so that a potential of + 128 V is applied. The fifth consumer device V5 is, for example, a lighting device for the car 10, in particular for the case of emergency operation thereof. The voltage mentioned depends on the type, the number and the interconnection of the lamps used. It can therefore vary in a very wide range.

A sixth consumer device V6 receives the voltage of the series connection of all 42 lead-acid batteries B1, B2, B3-B42. This is, inter alia, the intermediate circuit voltage of the frequency control device 24. This voltage is at the same time the voltage which is applied between the potential tap 40 and the ground line N.

LIST OF REFERENCE NUMBERS

10

car

12

counterweight

14

rope

16

traction sheave

20

electric machine

24

Frequency Control Unit

26

rectifier

28

sensor

30

rotor

32

microcontroller

34

inverter

36

Semiconductor switches

38

electrical energy storage

42, 54

hanging electrical cable

44, 44a, 44b

Wall of the elevator shaft

46a, 46b

guide rails

48a, 48b

Guide pins or plates

50a, 50b

Recesses in guide rails 48a, 48b

52a, 52b

areas

56

connection

58a, 58b

Car doors

60

holding brakes

100

elevator system

B1, B2, ..., B42

lead-acid batteries

V1, V2. V3, V4, V5, V6

consumer devices

Claims (8)

Elevator installation (100), comprising a car (10) and a counterweight (12) thereto, the car (10) and the counterweight (12) being connected to each other by cables (14) guided by a traction sheave (16) wherein the traction sheave (16) is coupled to an electric machine (20) and the electric machine (20) is both adapted to operate as an electric motor to drive the traction sheave (16) and thus to the car and the counterweight (12) move, and is designed to work as a generator to gain electrical energy due to rotation of the traction sheave (16), whereby electrical energy thus obtained is supplied to an electrical energy store (38) of the elevator installation (100) in order for the operation of the electric machine (20) as an electric motor to be removed later again, characterized in that the electrical energy store (38) forms the counterweight (12) or is part of the same. Lift installation (100) according to claim 1, characterized in that the electrical energy store (38) has a plurality of Accumulators comprises, preferably lead-acid batteries (B1, B2, B3, ..., B42). Lift installation (100) according to claim 2, characterized in that the electrical energy store (38) comprises between thirty-six and forty-five, preferably forty-two 12 V accumulators (B1, B2, B3, ..., B42). Lift installation (100) according to one of the preceding claims, characterized in that the electric machine (20) and the counterweight (38) are electrically connected to each other via a suspended electric cable (44) and / or that the car (10) and the counterweight (12) are electrically connected to each other via a suspended electrical cable (44, 46). Lift installation (100) according to one of the preceding claims, characterized in that the counterweight (12) is guided in rails (46a, 46b), of which at least one rail (46a, 46b) is electrically coupled to a voltage pole of the electrical energy store (38) is. Lift installation (100) according to one of the preceding claims, characterized by a frequency control device (24) having a rectifier (26) which converts a mains AC voltage into a DC voltage, and an inverter (34) which converts the DC voltage into an AC voltage, wherein in the frequency control device (24) a speed curve is parameterized, depending on the time or the way in the context of a Regulation to be set speed indicates, wherein the AC voltage receives a frequency for generating a rotational speed corresponding to this rotation speed of the traction sheave (16) and wherein between the rectifier (26) and the inverter (34) of the electrical energy store (38) is electrically coupled. Lift installation according to claim 2 or according to one of claims 3 to 6 in the back reference to claim 2, characterized in that at least one electrical consumer device (V1, V2, V3, ..., V6), in particular in or on the car (10) is electrically coupled or couplable to an accumulator (B1) or a series circuit of a plurality of accumulators (B1, B2, B3, ..., B42) to enable emergency power operation. Lift installation according to claim 7, characterized in that at least two electrical consumer devices (V1, V2), having different values for an operating DC voltage with a different number of one or more accumulators (B1, B2, B3, ..., B42 ) are coupled.

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