Hoisting machine with vibrating damping and an elevator assembly

A hoisting machine includes an axial flux motor including a rotor having rope grooves and arranged in rotor compartment between a body part and a protection plate, and a stator arranged against the rotor in such a manner that the rotor is separated by the stator by an air gap. The hoisting machine further includes a first cover plate and a second cover plate, arranged at opposite sides of the hoisting machine, and both being equipped with a damper. The tightness between the first cover plate and the second cover plate is adjustable. An elevator assembly and method of damping vibration of a hoisting machine are also disclosed.

FIELD OF THE INVENTION

The invention relates to design and construction of electric motors used in elevators.

BACKGROUND ART

The operation of a rotating electric machine, such as a synchronous and induction motor, is based on a magnetic field moving in a stator and rotor. This magnetic field is produced as a joint effect of stator and rotor magnetizations. The currents flowing in the stator windings produce in the air gap of the machine a rotating magnetic field, whose phase difference relative to the rotor magnetization creates a force effect in the direction of motion of the rotor. This force effect causes the rotor to rotate.

The rotor and stator magnetizations together also produce a force of attraction between stator and rotor. The attractive force is usually multiple times greater than the force causing the rotor to rotate. Since the attractive force appears in the zone where the magnetic field is transferred from rotor to stator and vice versa, the attraction vector rotates in accordance with the magnetic field. Therefore, local variations in the attractive force between stator and rotor may produce vibration in the electric machine.

Vibration of an electric machine often produces disturbing noise radiating into the environment, and, on the other hand, it may also shorten the service life of mechanical components of the electric machine. Vibration may also be transferred by transmission e.g. via the mounting interface to the environment, such as to the supporting structures surrounding the electric machine.

It is a general aim to utilize built space as efficiently as possible, for example, owing to space requirements. In the last decade, also the applicant has participated in the development of more compact hoisting machines of elevators. A compact hoisting machine of the applicant, and guide rail fixing arrangment for the same are disclosed in international patent application published under publication number WO 2011/154614 A1. Another compact elevator hoisting machine of the applicant has been disclosed in international patent application published under publication number WO 2011/036348 A1. Both hoisting machines comprise an axial flux motor.

Axial flux motors for hoisting machines are currently being designed to be as flat as possible in their dimensions in the direction of the axis of rotation or as small as possible in their dimensions in the direction of the radius, in which case the hoisting machines fit better in connection with, for instance, the wall part of the elevator hoistway or into some other narrow/shallow space.

However, the rigidity of the hoisting machine may form a problem e.g. when minimizing the length in the direction of the axis of rotation of a hoisting machine implemented with an axial flux motor. For example, rigidity is required of the hoisting machine of an elevator as well as of the support structure of the hoisting machine, because the hoisting machine must support the elevator mechanics suspended in the elevator hoistway. Also the noise level of the hoisting machine may increase to be disturbing when the rigidity of the hoisting machine weakens.

An arrangement for damping vibration in an electric machine, and a corresponding method, have been disclosed in international patent publication published under publication number WO 2010/063869 A1. In the arrangement, vibration dampers are fitted between the stator and the machine frame, or between the stator winding and machine frame.

OBJECTIVE OF THE INVENTION

Vibration damping and noise reduction remain challenges in the context of axial motors that are used in elevator hoisting machines. This follows partly from the fact that the suspension ropes are moved by the drive sheave having rope grooves, the drive sheave normally being integrated in the rotor, and therefore the rotor compartment has to be at least partly open to enable the movement of the ropes, partly from the cooling required for the motor brakes that usually need to directly engage the rotor or its shaft. It is clear that such an open rotor compartment is far from ideal from the design engineer's point of view who has the objective to reduce vibration and/or noise caused by the hoisting machine.

It is an objective of the invention to improve vibration damping of a hoisting machine and in an elevator assembly, and so to reduce noise and vibrations caused by the operation of the hoisting machine, at least over a frequency range.

This objective can be achieved according to the first aspect of the invention with a hoisting machine according to independent claim1and according to the second aspect of the invention with an elevator assembly according to independent claim12, and with the improvement in vibration damping of a hoisting machine and in an elevator assembly according to independent claim14.

The dependent claims describe further advantageous and inventive aspects of the hoisting machine and of the elevator assembly.

ADVANTAGES OF THE INVENTION

The hoisting machine according to the first aspect of the invention comprises an axial flux motor comprising a rotor having rope grooves arranged in rotor compartment between a body part and a protection plate, and a stator arranged against the rotor in such a manner that the rotor is separated by the stator by an air gap. The hoisting machine further comprises a first cover plate and a second cover plate that are arranged at opposide sides of the hoisting machine and both equipped with a damper. The tightness between the first cover plate and the second cover plate is adjustable. The cover plates with dampers and adjustable tightness help to suppress noise and form an efficient noise and vibration suppression arrangement. In this manner, the inventor has in simulations carried out by her been able to observe significant noise suppression over a frequency range.

The effect of the damper is that it tends to disperse any additional vibrations between the cover plates and the body part of the axial flux machine and the protection plate.

Advantageously, the first cover plate is located on the body part or in a recess in the body part, or the second cover plate is located on the protection plate or in a recess in the protection plate. Most advantageously, the first cover plate is located on the body part or in a recess in the body part, and the second cover plate is located on the protection plate or in a recess in the protection plate. The inventor has been able to make the unexpected observation that the body part and the protection plate of the axial flux motor are behaving like a loudspeaker. By arranging the first and/or second cover plates to the structure, the structure can be stiffened and the loudspeaker-like behaviour can be suppressed significantly over a frequency range.

Thanks to adjustable tightness, the frequency range over which the noise and vibration suppression is at strongest can be adjusted in such a manner that the desired frequency range is suppressed at most. This is very practical in the context of hoisting machines, since normally the acoustic system formed by the hoisting machine and its neighbouring elevator assembly parts, such as, guide rail, fixing arrangements, and wall parts, tends to have several different resonance frequencies. Since the attenuated frequency range can now be adjusted, the adjustment can be carried out in such a manner that the most disturbing frequency range of the acoustic system suppressed. Alternatively or in addition, with the adjustability it may become easier to suppress certain resonance frequencies in the acoustic system.

Preferably, the first cover plate and the second cover plate are interconnected through a tightness adjustion mechanism. This enables the use of the first and the second cover plate jointly to stiffen the structure of the axial flux motor. Then the tightness adjustion mechanism may penetrate the rotor and the stator. In this way, the tightness adjustion mechanism can be carried out in a manner that enables a compact size of the axial flux motor since otherwise the interconnection should be carried at least outside the rotor. In view of the limited space in the hoistway, making interconnection outside the rotor could easily increase the volume of the hoisting machine.

Preferably, the tightness adjustion mechanism is carried out by using at least one form-locking arrangement, preferably with a bolt and a nut. In this manner, the safety of testing, maintenance and using of the hoisting machine can be improved since the form-locking of the tightness adjustion mechanism reduces the risk of components of the tightness adjustion mechanism separating from the hoisting machine and falling in the hoistway.

Most preferably, the form-locking arrangement comprises a bolt and a nut. The bolt that has a bolt head, and the nut are so arranged that they are at opposite sides of respective cover plate than the dampers so that the dampers are tightenable or loosenable by rotating the bolt head and/or the nut. Most advantageously, the cover plates are easy to replace. The mass of the hoisting machine does not need to be increased signicicantly so that the cost of cast materials do not need to be increased.

Preferably, the first cover plate and the second cover plate are so configured that they form an external damper. This helps to avoid vibrations connecting from the body part of the axial flux motor and from the protection plate to the cover plates. Such connecting vibrations might increase vibrations and noise instead of suppressing them.

Most preferably, the first cover plate and the second cover plate that both serve as carrier for the respective damper are made of iron. Alternatively, they also may comprise iron. Iron is dense enough and so facilitates the passing of the acousting modes from the axial flux motor body part and protection plate to the noise and vibration suppression arrangement, and can therefore be used to efficiently suppress noise and vibrations.

Most advantageously, the damper is a layer of elastic material or comprises at least one layer of elastic material, such as but not limited to, rubber or elastomer.

Preferably, the hoisting machine further comprises at least one rail fixing arrangement for fixing the hoisting machine to a guide rail. The rail fixing arrangement can be integral to the axial flux motor body part. In this manner, the acoustic behaviour of the hoisting machine can be made better controllable.

The elevator assembly according to the second aspect of the invention comprises an elevator car that is movable in elevator hoistway by rotation of a hoisting machine causing movement of suspension ropes in rope grooves. The acoustic performance of the elevator assembly can in this manner be realized as adjustable in terms of the noise and vibration suppression frequency range.

Advantageously, the elevator assembly has a hoisting machine that comprises at least one rail fixing arrangement for fixing the hoisting machine to a guide rail, and the elevator car is movable along one, two or more guide rails in the elevator hoistway. The hoisting machine has been installed between between a wall part of the elevator hoistway and the guide rail in such a manner that suspension ropes of the elevator assembly are operable by the rotor via rope grooves in such a manner that the suspension ropes are located between the hoisting machine and the movable elevator car. The acoustic performance of the subsystem of the elevator assembly including the hoisting machine, the fixing arrangement and the guide rail can in this manner be realized as adjustable in terms of the noise and vibration suppression frequency range.

The improvement in vibration damping of a hoisting machine and in an elevator assembly is characterized by adjusting tightness between the first cover plate and the second cover plate of the hoisting machine according to the first aspect of the invention or any of its further aspects that is installed and/or operated in the elevator assembly according to the second aspect of the invention or any of its further aspects, to modify the operating noise caused by operation of the hoisting machine.

Same reference numerals refer to same parts in all FIG.

DETAILED DESCRIPTION

The concept of vibration damping method according to the present invention and the hoisting machine according to the present invention, and in particular the vibration concept emploeyed in the vibration damping between the drive-sheave protection plate and mounting frame are explained in more details within the context of the elevator assembly disclosed in certain applicants prior applications, namelyWO 2011/154614 A1, of which the structure of the elevator assembly, the operation mechanism of the hoisting machine and of the rotor, and the fixing arrangement and fixing points and optionally also its vibration damping, machinery brakes, brake drums and brake shoes;WO 2011/036348 A1, of which the rotor stucture, in particular also including the rotor bearings; andoptionally, also WO 2010/063869 A1, of which the details of the dampers arranged between the stator and the machine frame, or between the stator winding and machine frame

are incorporated in the present application by reference.

FIG. 1illustrates the concept of elevator assembly1including a hosting machine2, andFIG. 2shows certain details of the structure of a hosting machine2.FIG. 1and the respective part of the description can also be found in international patent application published under publication number WO 2011/154 614 A1.FIG. 2and the respective part of description can be seen inFIG. 2of international patent application published under publication number WO 2011/036348 A1, with slight modifications in the shape of the rotor. Also the sensor arrangement has been omitted for clarity.

FIG. 1is a block diagram an elevator assembly1, in which the elevator car15and the counterweight29are suspended in the elevator hoistway30with suspension ropes16. Elevator car15is movable with the hoisting machine2of the elevator assembly1. The hoisting machine2is disposed in the top part of the elevator hoistway30, along a guide rail9fixed to a wall part17of the elevator hoistway30by exerting a force effect on the elevator car15with suspension ropes16traveling via the traction sheave5of the hoisting machine2. On the surface of the traction sheave5are rope grooves6(see alsoFIG. 2), in which the suspension ropes16move along with the rotational movement of the traction sheave5such that the suspension ropes16are rotatably supported in the rope grooves6.

The power supply to the hoisting machine2most preferably takes place with a frequency converter (not shown inFIG. 1) connected between an electricity network and the hoisting machine2. The frequency converter and the hoisting machine2are most preferably disposed in the elevator hoistway30, in connection with wall part28of the elevator hoistway30outside the path of movement of the elevator car15.

The hoisting machine2may be fixed to a guide rail9, most preferably by using the fixing arrangement as disclosed in international patent application published under publication number WO 2011/154614 A1 in such a manner that the hoisting machine2is apart from the wall part17of the elevator hoistway30. The guide rail9bears the force exerted on the rope grooves6of the traction sheave5via the suspension ropes16. The guide rail9is fixed to the wall part17of the elevator hoistway with guide rail fixings31.

The hoisting machine2of the elevator is disposed in the space between the aforementioned wall part17and the guide rail9such that the axis of rotation19of the hoisting machine is situated essentially orthogonally with respect to the wall part17. Hoisting ropes16arriving at the rope grooves61of the traction sheave5as well as the hoisting ropes16leaving from the rope grooves6travel closer to the wall part17than the rear part of the guide rail9of the elevator car15. WO 2011/154614 A1 discloses in more detail the fixing arrangement7for a hoisting machine2used in the elevator assembly1. The hoisting machine2is fixed at its top part to the guide rail9from at least two points, which are at the same height and which are situated apart from each other in the width direction w of the guide rail9of the elevator car15, with the fixing arrangement7comprising rigid fixing means7which continues essentially as an integral piece between the fixing points3A,3B. Fixing points3A,3B of hoisting machine2comprise fixing pins/fixing bolts. The fixing arrangement is fixed rigidly to guide rail9e.g. with fixing pins, fixing bolts or fixing screws. Hoisting machine2is fixed at its bottom part to guide rail9from only one fixing point3C with a fixing arrangement10. The fixing pins of the fixing points3A,3B of the top part of the hoisting machine2as well as the fixing point3C of the bottom part are connected to the rigid fixing arrangements7,10with an elastomer, which damps the vibration caused by the operation of the hoisting machine2, e.g. from the effect of groove harmonics. The brake ring of the drum brake is formed as an extension of the rotating structure of the hoisting machine. Two drum brakes (omitted inFIG. 1) movably supported on the stationary structure of the hoisting machine2are the machinery brakes of the hoisting machine2, the brake shoes of which drum brakes engage, pressed by a spring pack, against the brake ring to brake the movement of the traction sheave5of the hoisting machine2. For example, in connection with an emergency stop the brake shoes of the machinery brakes engage to brake a traction sheave5that is moving rotationally; in this case, owing to the kinetic energy of the elevator car15, an essentially large force braking the movement of the traction sheave is formed between the rotating structure and the stationary structure of the hoisting machine2, which force tries to produce vibration of the hoisting machine. For damping the vibrations of the hoisting machine2, the distance s between the fixing points3A,3B of the top part of the hoisting machine is selected to be equal to, or even greater than the diameter D of the traction sheave5. The distance s between the fixing points3A,3B could also be selected e.g. such that the ratio of the distances to the diameter D1of the brake ring is greater, e.g. greater than 0.5. This type of fixing arrangement stiffens the structure of the hoisting machine2, reducing the vibration of the hoisting machine.

FIG. 2shows a sectional drawing of hoisting machine2. For detecting the position of a magnetic pole of the rotor31, or for measurement of position data and/or movement, the hoisting machine2may—but it does not need to—comprise an optical encoder or a resolver, or a magnetic band and reader (as the hoisting machine disclosed in WO 2011/036348 A1) comprising combinations of a magnetic band and a reader.

The hoisting machine2inFIG. 2is a permanent-magnet synchronous motor, in which the permanent magnets are mounted on the rotor31. The drive sheave5is integrated with the rotor31. The air gap33between the stator32and the rotor31is substantially parallel to the rotational axis19of the rotor31. The rotor31and the drive sheave5are rotatably supported by bearings27on the body part of the hoisting machine2. The bearing27is mounted in a bearing housing34, which is integrated in the same body with the traction sheave5.

The traction sheave5protection plate28secured to the body part35of the hoisting machine2extends to the side of the traction sheave5so that the traction sheave5is housed in the space remaining between the protection plate28and the body part33.

FIG. 3illustrates a hoisting machine2′ according to the invention as seen in perspective from the stator32side.FIG. 4illustrates the hoisting machine2′ as seen in perspective from the rotor31side.

FIG. 5is a top view of the hoisting machine2′ andFIG. 6is the section VI-VI. The hoisting machine2′ is shown in right-hand side inFIG. 7.

It should be understood that rotor31has been omitted fromFIGS. 3-7for the sake of clarity.

The hoisting machine2′ comprises an axial flux motor comprising a rotor31having rope grooves6and arranged in rotor compartment58between a body part35and a protection plate28, and a stator32arranged against the rotor31in such a manner that the rotor31is separated by the stator32by an air gap.

Body part35serves as a fixing for the stator32that most preferably is welded to the body part35. Alternatively of welding or in addition to it, also the fixing arrangement described in WO 2010/063869 A1 can be used to fix the stator to the body part.

The hoisting machine2′ further comprises at least one rail fixing arrangement60for fixing the hoisting machine2′ to guide rail9. The rail fixing arrangement60is most probably integral to the base part35and contains suitable protruding lips that can be mounted around the guide rail9, and also stiffening wing63and stiffening ribs64to increase the mechanical rigidity of the hoisting machine2′.

Furthermore, the hoisting machine2′ comprises lateral brake shoes55movably attached to brake shoulders57that are attached to the base part35in a form-locking manner, such as by using bolts56. Brake shoes55are used to brake the movement of the rotor31. They Additionally, the hoisting machine2′ comprises braking control system that ensures that the brake shoes55are normally in the locking position i.e. engage with the rotor31, and disengage from the rotor only when the braking control system is activated.

The hoisting machine2′ further comprising a first cover plate51and a second cover plate53, arranged at opposide sides of the hoisting machine2′, and both being equipped with a damper59. Preferably, the first cover plate51and the second cover plate53that both serve as carrier for the respective damper59are made of iron, or comprise iron,10. The damper59is a layer of elastic material, such as rubber or elastomer. The first cover plate51and the second cover plate53form an external damper to the axial flux motor.

The tightness between the first cover plate51and the second cover plate53is adjustable.

The first cover plate51can be located on the body part35or, as can be seen inFIG. 6, in a recess in the body part35. Respectively, the second cover plate53can be located on the protection plate28or as also can be seen inFIG. 6, in a recess in the protection plate28.

The first cover plate51and the second cover plate53are interconnected through a tightness adjustion mechanism that comprises a bolt50(with bolt head54) and a nut52. The tightness adjustion mechanism penetrates the rotor31and the stator32. Instead of bolt50and nut52, the tightness adjustion mechanism can be realized by using any other suitable form-locking arrangement.

The bolt head54and the nut52are so arranged that they are at opposite sides of respective cover plate51,53than the dampers59so that the dampers59are tightenable or loosenable by rotating the bolt head54and/or the nut52.

In the simulations carried out by the inventor, around the cover plates51,53vibration amplitudes |U|<0.25 (in arbitrary units) could be obtained (ref.FIG. 8). Vibration amplitudes generally depend on load, speed and certain other factors and in general are described as mobility (displacement/force). As can be seen, at noisiest (0.5<|U|<1.25) the hoisting machine2′ is around brakes. A respective simulation carried out by the inventor for hoisting machine2shows that vibration amplitudes 0.5<|U|<1.25 were present all over the hoisting machine2. The hoisting machines2′ and2compared with each other, it can readily be seen that the hoisting machine2′ according to the invention is from noise/vibration viewpoint superior to a hoisting machine2known from background art.

The invention is not to be understood to be limited in the attached patent claims but must be understood to encompass all their legal equivalents.

LIST OF REFERENCE NUMERALS USED

3A,3B,3C fixing point

17wall part of the elevator hoistway