HK1022891B - Elevator drive machine - Google Patents

Description

Elevator drive machine

Technical Field

The invention relates to an elevator drive machine.

Background

The drive machine of a traction sheave elevator comprises a traction sheave with traction rope grooves for the elevator and an electric motor which drives the traction sheave either directly or via a transmission. Conventionally, the motor used to drive the elevator has been a dc motor, but the use of ac motors with electronic control, such as squirrel cage motors, has increased. One of the problems encountered with gearless elevator machines of conventional construction has been their large size and weight. Such motors take up considerable space and are difficult to transport to the site and to install. In an elevator group consisting of several large elevators, it is sometimes even necessary to install the hoisting machines of adjacent elevators on different floors to provide them with sufficient space above the elevator shafts disposed side by side. In larger elevator machines, the transmission of torque from the drive motor to the traction sheave can be problematic. For example, large gearless elevators with a conventional drive shaft between the motor and the traction sheave are particularly prone to considerable flexural vibrations due to the flexing of the shaft.

Recently, solutions have been proposed in which the elevator motor is a synchronous motor, in particular with permanent magnets. For example, specification WO95/00432 discloses a synchronous machine with permanent magnets, which has an axial air gap and in which the traction sheave is directly connected to the disc forming the rotor. This solution is advantageous in elevator drives where the required torque is relatively low, e.g. a hoisting load of about 1000 kg, and where the elevator speed is in the order of 1 m/s. Such a machine has particular advantages in elevator solutions designed to minimize the space required by the elevator drive machine, e.g. without a machine room.

Specification FI93340 discloses a solution in which the traction sheave is divided into two parts, on opposite sides of the rotor in the direction of its axis of rotation. Stators, which are shaped as ring sectors and are separated from the rotor by an air gap, are likewise arranged on both sides of the rotor.

In the machine disclosed in specification FI95687, the rotor and stator parts on both sides thereof with an air gap in between are located inside the traction sheave. In this way, the traction sheave is integrated with the motor, which is provided with a magnetizing element corresponding to each rotor portion.

Specification DE2115490A proposes a solution for driving a cable or rope hub or the like. This solution uses a separate linear motor arrangement for use on the hub flange edge.

None of the solutions presented in the above-mentioned specifications is able to produce a sufficiently large torque and rotational speed for elevators designed for loads of several thousand kilograms and speeds of several meters per second. Other problems are encountered in the control of axial forces. In machines with multiple air gaps, other problems arise from the non-periodic electrical and functional properties of the air gaps. Thus, to fully utilize the motor, special requirements for the electric drive of the motor are added, and the special requirements often result in a complex system and high cost.

Specification GB2116512A discloses a geared elevator machine having several relatively small motors driving a single traction sheave. In this way, a machine is achieved which requires a relatively small floor area. The machine disclosed in GB2116512A can be accommodated in a machine room space which is no larger than the cross-section of the elevator shaft below it. Such advantageous machine room solutions are not suitable for use in large gearless elevators, since they usually have a machine with a large motor extending laterally a long distance from the traction sheave. Specification EP565893a2 discloses a gearless elevator machine comprising more than one modular motor unit, which modular motor units are connected together to drive traction pulleys that are also connected together. In such a solution, the length of the machine is increased when its capacity is increased by adding an electric motor module. In this case the problem arises that the length of the machine increases on the side of the traction sheave, which is why the machine projects beyond the width of the elevator shaft below. Supporting and reinforcing such a long machine so that its own weight and the rope hanger do not deform detrimentally may result in an expensive and difficult solution. For example, a long mechanical bend requires special and expensive support solutions. If a bending or other form of load causes even a very slight crushing deformation of the traction sheave to become oval, it may cause vibrations that reduce the comfort of elevator operation.

Disclosure of Invention

The object of the present invention is to provide a new gearless elevator drive machine which can produce the torque, power and rotational speed required in large and fast elevators.

In order to achieve the above object, the invention provides a gearless elevator drive machine comprising a traction sheave and an electromechanical device comprising two electric motors for driving the traction sheave in rotation, each electric motor having a rotor and a stator, the traction sheave being disposed between the rotors of the two electric motors along the axis of rotation of the traction sheave, and the traction sheave and the weight exerted on it via elevator ropes attached to the elevator car and the counterweight being supported substantially in the radial direction of the drive machine by bearings between the stator and the rotor of the electric motors driving the traction sheave of the drive machine.

With the solution of the invention, the torque is generated by two motors or motor units, which is doubled compared to a single motor. The axial forces generated by the two motor units balance each other, thereby minimizing strain on the bearings and the motor shaft.

With the drive machine of the invention, a large traction sheave size is achieved, relative to the size, performance and weight of the drive machine, due to the good torque characteristics of the machine. For example, an axle load of 40000 kg can be handled by machines weighing less than 5000 kg, even at elevator speeds up to 9 m/s or quite high.

Since the construction of the drive machine allows the rotor and stator to have a large diameter relative to the diameter of the traction sheave, sufficient torque can easily be generated on the traction sheave. On the other hand, a shorter distance between the bearings in the direction of the axis of rotation automatically ensures a small radial deflection, so that no large structures are required to prevent such deflection.

Especially in the case of elevator drive machines with the highest requirements on load capacity, a single traction sheave driven by at least two motors avoids relatively high costs with respect to the load capacity of a large single motor. By arranging the traction sheave between two electric motors, a compact mechanical structure can be obtained and torque, power and various forces can be transmitted directly from the machine to the traction sheave without using a separate drive shaft. These advantages are fully achieved by mechanically coupling the rotors of two different motors together with a traction sheave.

The very close coupling of the rotor part of the motor to the traction sheave results in a machine in which the rotating parts are used as a single unit, enabling more accurate elevator motion control.

Since the frame of the drive machine serves as a carrier for the housing of the motor/motors and the bearings of the moving parts, the total weight and the required space of the machine are relatively low compared to conventional hoisting machines for corresponding applications.

In principle, only each rotor needs a bearing, and the bearing box is easy to seal. Any lubricant that may pass through the seal may be so conveniently directed away that it does not cause damage.

The torque generated by the motor is transmitted directly from the rotor to the traction sheave, either because the traction sheave is essentially mounted at the joint between the rotor units or because the traction sheave connects the rotor units together along a circle of considerable radius.

In the drive machine of the invention, the air gaps can be adjusted in pairs so that they have the same size, and the mutual air gap size of the two motor/motor units can even be adjusted so that the motors/motor units have the same electric drive. In this way it is possible to have two motor/motor units driven by a single electric drive without the difference in performance of the motor/motor units resulting from the machine being driven by a single electric drive.

The machine is easy to handle in terms of machine room layout and installation, since it is small in size and light in weight relative to its load capacity. Elevator machines with high load capacity are normally used in elevator groups comprising several elevators. This has great advantages in respect of the utilization of building space, since the hoisting machine can be accommodated in a machine room having a floor area smaller than the cross-sectional dimension of the elevator shaft below it.

Drawings

The invention is described below by way of example with reference to the accompanying drawings, which in themselves do not constitute a limitation of the scope of the invention.

Fig. 1 is an elevator drive machine provided by the present invention, viewed from the axial direction;

FIG. 2 is a side elevation view, partially in cross-section, of the drive machine of FIG. 1;

FIG. 3 is a detail view of FIG. 2;

FIG. 4 is a top view of the drive machine of FIG. 1;

FIG. 5 shows the mounting of the drive machine of the present invention;

FIG. 6 shows a cross-section of another drive machine of the present invention; and

fig. 7 is a detail view of fig. 6.

Detailed Description

Fig. 1 is a gearless drive machine 1 provided by the present invention as viewed from the axial direction. The figure shows the profile 2a of the traction sheave 2 of the drive machine 1 to indicate the arrangement of the traction sheave relative to the frame body 3 forming part of the machine frame. The frame body 3 is preferably made by casting, preferably in the form of an iron casting. The frame body can also be welded, for example, from sheet steel parts. However, the welded frame body may only be used in special situations 2, for example when it is necessary to manufacture very large machines as individual cases. Even a frame body of about 2m height can be conveniently cast by casting if a series of several machines is to be produced.

The frame body is reinforced by ribs. The ribs are partly annular, comprising one or more rings, partly radial. The radial parts of the ribs point from the central part of the frame body 3 to fixing points 4, 5, 6, 7, 8 provided along the frame body edge, as well as to the mounting 10 of the elevator operating brake 9 and to the fixing legs 11 of the drive machine, which is fixed to its base by means of the fixing legs 11. The fixing legs 11 are located close to the fixing portions 6, 7 located at the lower part of the frame body. The frame body has a seat for a fan 12 and a tachometer 13 with the required holes. The traction sheave bearing is located behind the cover 15. The cover is provided with a passage for the adjusting screw 16 of the means for axial positioning of the traction sheave. The cover 15 is further provided with an injection hole 42 for introducing lubricant into the bearing space, and an inspection hole or window 41 for inspecting the amount of lubricant.

Fig. 2 shows the drive machine 1 in a partially sectioned side view. Fig. 3 is a detail view of fig. 2, more clearly showing the support structure. In these figures, the right part of the machine centerline represents the section a-a of fig. 1, while the left part represents the section R-R of fig. 1. The figure shows a drive machine in which the traction sheave is arranged in an electric motor having a rotor and a stator divided into units, between and mounted on the two rotor units 17, 18 of the motor; or two motors between which the traction sheave 2 is mounted on the rotors 17, 18 of both motors, is mainly a matter of definition. Each stator/stator unit 19, 20 is fixed to the frame body 3, 3 a. Each air gap is formed between the stator and the rotor. The air gap in the machine shown in the figures is a so-called axial air gap, in which the flux direction is substantially parallel to the machine axis. The stator windings are preferably so-called slot windings. The rotor magnets 21 are preferably permanent magnets and are mounted to the rotors 17, 18 by any suitable means. The flux of the rotor passes through the rotor discs 17, 18. In this way, the part of the rotor disc located below the permanent magnets acts both as a part of the magnetic circuit and as a structural element of the rotor. The permanent magnets can have different shapes and they can be divided into magnet assemblies placed side by side or one after the other. The rotor disc is preferably cast from cast iron. Both the rotor disc and the frame body are preferably shaped such that they fit together with another identical piece, so that there is no need to produce one piece and its mating piece separately. The rotors 17, 18 are provided with roller bearings 22 supporting them on the respective frame bodies 3a, 3. The roller bearings 22 are subjected to radial forces. In very large elevators, the bearings have to carry a weight of several tens of tons, because in many cases almost all of the weight of the elevator car and counterweight is applied to the traction sheave by the elevator ropes. The elevator ropes and the compensating ropes or chains also add significant weight, the net axial force being taken up by an auxiliary bearing 40. With the axial adjustment associated with the auxiliary bearing 40, the rotors 17, 18 are centered so that each stator-rotor pair will have the same air gap.

The traction sheave and the rotor units are mounted to each other to form the rotating part of the machine, supported on the frame bodies by bearings. The auxiliary bearing 40, which is mounted to the rotor by its cover, and the screw 16, which engages the bearing sleeve and is supported by the cover 15, serve as an adjustment means in the bearing housing for moving the rotor unit in the axial direction. When the screw 16 is turned, it pushes or pulls the entire turning part depending on the direction of turning. Since the rotor magnets on each rotor unit tend to pull the rotating part towards the stator corresponding to the rotor, and since each rotor and stator are identical to each other, the central position can be found by rotating the adjustment screw until the pushing and pulling forces of the screw are practically zero. A more accurate way to find the centre position is to turn the rotating part and measure the electromotive force obtained from the stator. As the rotating portion rotates, the rotating portion is successfully centered when the electromotive force measured from the first stator unit is the same as the electromotive force measured from the second stator unit. In this way, the two stator-rotor pairs have very identical drive characteristics and they can be driven by a single electric drive, one of the stator-rotor pairs not being subjected to higher loads than the other stator-rotor pair.

The stators 19, 20 with their windings are mounted to the frame bodies 3a, 3 by means of fixing elements, which on the one hand serve as mounting elements for fixing the stators in place and on the other hand serve as housing structures for the motor and drive machine as a whole. The fixing is preferably a screw. Mounted on the rotors 17, 18 are rotor excitation devices disposed opposite the stators. The excitation device is formed by fixing permanent magnets to the rotor in a continuous manner, each permanent magnet forming a ring.

The stators 19, 20 are mounted to the frame bodies 3a, 3 with stator winding fixing members, the frame bodies serving as both a base for fixing the stators in place and a housing structure of the entire drive machine. The fixing is preferably a screw. The rotors 17 and 18 are provided with excitation devices disposed to face the stators. The excitation means is formed by fixing a series of permanent magnets 23, each forming a ring, to the rotor in a continuous manner.

An air gap is provided between the permanent magnet and the stator, which is substantially perpendicular to the rotational axis of the motor. The shape of the air gap may be slightly conical, in which case the centre line of the cone coincides with the axis of rotation. The traction sheave 2 and the stators 19, 20 are located on opposite sides of the rotors 17, 18, seen in the direction of the axis of rotation.

Between the frame bodies 3a, 3 and the rotors 17, 18, there is an annular cavity in which the stator and the permanent magnet are placed.

The outer edges of the rotors 17, 18 are provided with braking surfaces 23, 24 with which brake shoes 25 of the brake 9 engage.

The rotor units are provided with alignment members by means of which the permanent magnets of the first and second rotors can be positioned. Each permanent magnet is mounted in an arrow pattern. The permanent magnets can be aligned either directly opposite each other or slightly offset. Since the rotors have the same design, placing them in pairs opposite each other means that if the slot windings on the opposite stator are mounted in a mirror image, the second will rotate backwards when the first rotates forwards. This eliminates any possible structural dependence of the motor operating characteristics on the direction of rotation. The rotor magnet can also be implemented with a pointer structure pointing in the same direction as the direction of rotation. The alignment members are bolts, the number of which is preferably divisible by the number of poles and the pitch of which corresponds to the pole pitch or a multiple thereof.

Fig. 4 is a top view of the drive machine 1. The connecting elements 5b, 8b of the side of the drive machinery connecting the connecting points 5, 5a, 8, 8a of the opposite frame body are clearly visible, as is the connecting element 4b at the top side of the drive machinery connecting the connecting points 4, 4a arranged at the top of the frame body. The top connector 4b has a stronger structure than the other connectors. The top attachment 4b is provided with a loop 43 by means of which the drive machine is hoisted. In fig. 4 the outline of the wall of the elevator shaft 39 below the drive machine is indicated with a dashed line. The drive mechanism is clearly within this profile. This means that building space is saved. The machine room arrangement above the elevator bank is simplified in that the machine is accommodated completely in the space directly above the elevator shaft. Even if the cross-section of the machine room is of the same size and shape as that of the elevator shaft, there is still sufficient space left in the machine room around the drive machine to allow all normal service and maintenance operations to be carried out.

By arranging the legs 11 near the lower edge of the machine, the machine achieves maximum stability when mounted and fixed on its base. Preferably, each leg lies substantially out of the plane defined by the stator and rotor units.

Fig. 5 shows a method for mounting the drive machine 1 in the machine room 45. The drive machine is mounted on a support 46 made of steel beams. By using a diverting pulley 47 the distance between the part of the traction ropes 48 going to the elevator car and the part of the traction ropes 48 going to the counterweight is increased slightly more than the width corresponding to the diameter of the traction sheave 2.

The machine of fig. 6 is very similar to the machine shown in fig. 1-4. For a practical elevator, the most important difference is the way in which the traction sheave is mounted; the possibility of using traction sheaves of different widths (length; and in the arrangement of the bearings and the output end of the rotating shaft. Fig. 7 clearly shows the bearings and the output end of the rotating shaft.

In the drive machine of fig. 6, each end of the traction sheave 102 is fixed to a rotor 117, 118. In this way, the traction sheave is arranged between the two rotors. In the case of an axial motor as in the present embodiment, the most important part of the traction sheave, i.e. the cylinder formed with the rope grooves, together with the rotor magnet ring mounted to the traction sheave, is located entirely between the two planes defined by the two air gaps perpendicular to the axis of rotation. Even if the internal structure of the motor is different from the axial motor of the present example, it is advantageous to dispose the traction sheave between the torque-generating members. The rotors 117, 118 are rotatably mounted on the frame bodies 103, 103a by means of bearings, and each stator 119, 120 is fixed in position on the corresponding frame body 103, 103 a. The permanent magnets of the rotors are fixed to the rotors 117, 118 by a suitable method. The magnetic flux of the rotor passes via the rotor disc. The part of the rotor disc located below the permanent magnets thus serves both as a part of the magnetic circuit and as a structural part of the rotor. The rotor is supported on the frame body by a relatively large support 122. The large support size means that the support 122 can withstand radial forces well. The support, i.e. the roller bearing, has a structure that allows axial movement of the machine. Such bearings are generally less expensive than bearings that prevent axial movement, and they also allow for equalization of air gaps in the stator-rotor pairs on either side of the traction sheave. The equalization adjustment is performed using a relatively small auxiliary bearing 140 mounted on one of the frame bodies. The auxiliary bearing 140 also takes up axial forces between the traction sheave and the machine frame. The other frame body does not need to be provided with an auxiliary bearing. The auxiliary bearing 140 is mounted to a cover 191 installed on the frame body and covering the bearing space. Mounted on the cover 191 is an analyzer 190 or other device for measuring angle and/or velocity supported by the support 189. The end 188 of the shaft 199 that transmits the traction sheave motion passes through the central portion 192 of the cover 191 and the analyzer shaft is mounted to that shaft end. At the other end of the shaft of the machine, the shaft usually does not need to be output, so a simpler cover 187 closing the bearing space at that end is sufficient. On the side facing the traction sheave, the bearing space is closed with a cover 186.

The traction sheave and the rotor parts are mounted to each other to form the rotating part of the machine, supported on the frame body by bearings. Since the traction sheave is connected to the rotor parts 117, 118 by means of its edges or at least by means of a large-diameter fixing ring, the rotating parts can be regarded as forming the drive shaft of the machine themselves. For practical designs, the deflection of such a shaft is almost zero, so that the design of the drive shaft bearing and its support on the frame body is a rather simple task. The auxiliary bearing 140 and the larger bearing 122 that takes up radial forces are arranged axially one after the other, which is a different solution than the relative position of the auxiliary bearing 40 and the larger bearing 22 in the machine shown in fig. 1-4, in which the auxiliary bearing 40 is located inside the larger bearing 22. The sequential arrangement of bearings 122 and 140 allows for a greater radial clearance in the radial load bearing 122 than the radial clearance of the auxiliary bearing 140, since sufficient radial flexibility can be readily achieved in the connection between bearings 122 and 40. Flexibility may be increased by extending the auxiliary shaft 199 connecting the auxiliary bearing 140 to the rotor component 118 with a mounting collar 197 to move the auxiliary shaft support point 198 inward in the machine. Additional flexibility is achieved by providing a tapered portion to the auxiliary shaft 119 to facilitate bending of the shaft. In this way, the small play of the small auxiliary bearing 140 can be fully utilized. Thus, the auxiliary bearing makes it possible to achieve accurate axial position adjustment. Due to the small radial clearance, the shaft is accurately centered, which has a good effect on the accuracy of the analyzer signal.

The auxiliary bearing 140 is connected by its housing to the frame of the machine and by its centre via an auxiliary shaft 199 to the rotating part formed by the traction sheave and the rotors. By adjusting the mutual position of the auxiliary shaft and the auxiliary bearing in the axial direction of the machine, the position of each rotor relative to the frame can be adjusted. The axial adjustment can be performed, for example, by providing the auxiliary bearing and the auxiliary shaft with threads that engage with each other.

It would be advantageous to adjust the air gaps between the stator and the rotor of the drive machine to the same size. Alternatively, the air gaps can be adjusted until both motors/motor units have the same electrical drive. In this way, the two motor/motor units can be driven by a single electric drive without the motor/motor units differing in their operating conditions as a result of the drive machinery being driven by a single electric drive. The symmetry of the motors/motor units across the different air gaps may also be influenced by the mutual position of the stators and rotors, in particular the angle of rotation between the stators and rotors.

Several alternative methods may be used to match the motors of a dual motor drive machine. When operating in a drive machine in cooperation with an electric motor, optimization can be achieved by one of the following methods:

i) in the case of idle running of the motors, the standby supply voltage is measured and the supply voltages are adjusted to the same value by adjusting the air gaps and possibly the stator angle. In this regard, there are different criteria: the amplitude of the fundamental wave, its amplitude and phase, and in addition harmonics, and combinations thereof are adjusted.

ii) coupling the motors together without a load connected to them and adjusting the air gap and possibly also the angle of the stator packs (stator packs) to minimize the polyphase current. Here, too, the fundamental wave and the harmonic wave can be considered separately.

iii) in case a load is connected to each motor, the motors are measured and the air gaps and possibly also the stator angle are adjusted until the currents in both motors are equal. This is an advantageous alternative since any difference between the longitudinal impedances can be taken into account as well.

iv) the load is increased to a maximum and then the motor currents are equalized by adjusting the air gaps and possibly also the stator angle. Both motors will now output maximum torque and the combined load capacity is at a maximum.

In methods i) and ii), the above-mentioned measurements are carried out with the motor idling, thus also minimizing energy consumption and temperature rise.

i) The terms iv) may be suitably combined, for example, by deriving a cost function using suitable weighting coefficients that compensate for maximum load capacity, power consumption and harmonics.

It is obvious to the person skilled in the art that the embodiments of the invention are not limited to the examples described above, but that they may be varied within the scope of the invention.

Claims (14)

1. Gearless elevator drive machine comprising a traction sheave and an electromechanical device comprising two electric motors for driving the traction sheave in rotation, each electric motor having a rotor and a stator, characterized in that the traction sheave is disposed between the rotors of the two electric motors along the axis of rotation of the traction sheave and that the traction sheave and the weight exerted on it via the elevator ropes attached to the elevator car and to the counterweight are supported in the radial direction of the drive machine substantially by bearings between the stator and the rotor of the electric motors driving the traction sheave of the drive machine.

2. Drive machine as defined in claim 1, characterized in that the radial forces between the rotating part of the traction sheave and the frame of the drive machine and the axial forces in the drive machine are mainly supported by separate support elements.

3. Drive machine as defined in claim 1, characterized in that the traction sheave mechanically connects the rotors of the two electric motors.

4. Drive machine as defined in any one of the preceding claims, characterized in that the traction sheave is supported without a separate traction sheave shaft.

5. Drive machine as defined in any one of claims 1-3, characterized in that the traction sheave is substantially a hollow cylinder, the rotors of the two electric machines being located on opposite sides thereof.

6. Drive machine as defined in claim 5, characterized in that the mounting points for the motor are located at the ends of the traction sheave.

7. Drive machine as defined in claim 6, characterized in that each end of the traction sheave is provided with a flange, on which the motor mounting points are located.

8. Drive machine as defined in claim 5, characterized in that the traction sheave comprises at least one flange directed towards the inside of the traction sheave and provided with an attachment point for the motor driving the traction sheave.

9. Drive machine as defined in any one of claims 1-3, characterized in that the traction sheave has in its interior a hollow space surrounded by walls which transfer the load applied to the drive machine from the traction sheave to the bearings between the stators and rotors of the electric motors.

10. Drive machine as defined in claim 9, characterized in that the walls of the hollow space consist only of parts of the traction sheave or of parts of the electric motors driving the traction sheave, and in that the ends of the hollow space are parts of the electric motors.

11. Drive machine as defined in claim 1, characterized in that an air gap is formed between the rotor and the stator of each electric machine.

12. Drive machine as defined in claim 11, characterized in that the traction sheave is centered between the air gaps of the electric motors.

13. Drive machine as defined in claim 12, characterized in that the air gaps of the motors are of the same size.

14. Drive machine as defined in claim 1, characterized in that the two electric machines are subjected to the same load during operation.