HK1091955B - Modular, transverse flux rotary electric machines and a method of providing the same - Google Patents

Description

Modular, transverse flux, rotary electric motor and method of manufacturing same

Technical Field

The present invention relates to a transverse flux motor in which the output torque can be adjusted by stacking rotor/stator modules to meet the needs of an application like an elevator and optionally provided with an integrated brake.

Background

As an example of the need for the inventive technique, elevator machines represent a major part of the material costs of elevators. Elevator machines require slow rotational speeds and must be able to provide service for several decades. In order to achieve low noise, smooth operation, low cost, compact drive systems, gears should be avoided as much as possible. An important factor in the choice of motor is the amount of torque output per unit of active material, which may be by mass or by volume, including core steel, wire, and permanent magnets. The maximum torque requirement of an elevator machine depends on its maximum imbalance, which is typically about half the rated load plus the maximum mismatch of rope mass with sheave diameter and rope traction devices (1: 1, 2: 1, etc.).

Conventional rotating field machines have a plurality of phase windings integrated in a core structure. To achieve greater torque capacity, it is necessary to stack a stack of a plurality of different phase windings into a longer core, each of which requires different winding jigs and other manufacturing equipment. In addition, the stator of the conventional motor has end coils that extend beyond the effective flux generating portion of the motor. These coil extensions make it difficult to make a compact motor/pulley combination and to integrate brakes or other auxiliary structures into the motor.

To reduce the number of motor modules required on a product line, some elevator modules sharing a motor pattern with other elevator modules must be oversized beyond their torque requirements. On the other hand, having multiple motors without common parts increases the cost of material production, preparation, manufacturing, and warehousing spare parts.

Disclosure of Invention

The object of the invention consists of various improved electric motors for elevators; a motor capable of providing high torque at low rotational speeds; a motor capable of increasing torque by adding only modular phase windings; a motor capable of increasing torque without overall change of windings; a motor having high efficiency and good power factor; an electric motor having a high bulk torque density; motors with shorter assemblies without protruding end coils and thus less losses; motors with simple stator windings; a motor that uses significantly less copper and requires less manufacturing man-hours than a brushless motor similar to a rated permanent magnet; and motors that can be constructed with the same modules so that the same modules can be used to adjust the torque to the rated value in a small number of steps.

According to the invention, the motor, which is suitable for driving the elevator pulleys, is constructed from identical rotor/stator modules, one or more for each phase of the drive current, in order to be able to select the appropriate torque rating of the motor.

Also in accordance with the invention, the brake may be integrally disposed on the same shaft and adjacent the rotor/stator module of the transverse flux motor.

The motor according to the present invention can provide a larger torque per unit volume than a conventional motor, has a practically constant efficiency with a constant torque and rotational speed of the stator, has an improved power factor (due to the absence of magnetic flux leakage from the end coils), and can have a power factor that increases with the number of poles. The motor according to the invention has a practically constant efficiency in the range from about 50% to about 120% of the rated shaft torque and at the rated operating speed. The present invention has a shorter ferromagnetic core and shaft and uses less than 30% copper in the wire, and also uses less ferromagnetic core volume and no protruding end coils than comparable permanent magnet brushless motors, thereby allowing a shorter and lighter motor with only one toroid per phase regardless of the number of poles.

The invention relates to a modular, transverse flux, rotating electrical machine, each machine having: a rotatable shaft; a plurality of identical cylindrical transverse flux rotor/stator modules disposed on said shaft, the flux lines between the rotor and stator of said modules being perpendicular to the torque, at least one of said modules being adjacent at least one other of said modules in the vicinity thereof, each of said modules providing the same torque rating to said shaft, whereby the torque rating of said motor is equal to the torque rating of each of said modules multiplied by the number of said modules; a rotary driven member arranged to rotate with said shaft; and a plurality of end plates, one for each of said modules not flanked by another of said modules; each of said motors including at least one brake assembly compatibly formed with said modules and disposed between one of said modules that is not adjacent to another of said modules and an end plate of said end plate corresponding to one of said modules; at least one of said motors having a different number of said modules than at least one other of said motors; and the length of said shaft is selected to accommodate at least said number of said modules, said brake assemblies, and said followers.

The invention also relates to a modular, transverse flux, rotating electrical machine comprising: a rotatable shaft; a plurality of identical cylindrical transverse flux rotor/stator modules disposed on said shaft, the flux lines between the rotor and stator of said modules being perpendicular to the torque, at least one of said modules being adjacent at least one other module in the vicinity, each of said modules being capable of providing the same torque rating to said shaft, whereby the torque rating of said motor is equal to the torque rating of each of said modules multiplied by the number of said modules; and a rotary follower arranged for co-rotation of said shafts; at least one of said motors having a different number of said modules than at least one other of said motors; the length of said shaft is selected to accommodate at least said number of said modules and said follower.

The invention further relates to a modular, transverse flux electrical machine having: a rotatable shaft; a plurality of identical cylindrical transverse flux rotor/stator modules disposed on said shaft, the flux lines between the rotor and stator of said modules being perpendicular to the torque, at least one of said modules being adjacent at least one other of said modules in the vicinity thereof, each of said modules being capable of providing the same torque rating to said shaft, whereby the torque rating of said motor is equal to the torque rating of each of said modules multiplied by the number of said modules; a rotary driven member arranged to rotate with said shaft; and a plurality of end plates, one for each of said modules that is not flanked by another of said modules, the motor comprising: a brake assembly integrally formed with said modules and disposed between one of said modules which is not adjacent to another of said modules and an end plate of one of said end plates corresponding to one of said modules.

The invention also relates to a method for providing a modular rotating electric machine, comprising the following steps: selecting a torque increment; designing a cylindrical, transverse flux rotor/stator module to provide a torque equal to said increment and to have flux lines between the rotor and stator of said module perpendicular to the axis of said module; for each motor to be manufactured: selecting a shaft for mounting a desired number N of modules to achieve or exceed the torque required by said motor and driven member in less than said increments; attaching said follower to said shaft and said modules to said shaft such that said modules abut each other, said modules being attached to one or more sides of said follower; and at least one of said motors has a different number of modules than at least one other of said motors.

Other objects, features and advantages of the present invention will become apparent in light of the following detailed description of exemplary embodiments thereof, as illustrated in the accompanying drawings.

Drawings

Fig. 1 is an external perspective view of a motor that may be attached to an elevator sheave in accordance with the present invention.

Fig. 2 is an exploded perspective view of a three-phase motor and an integrated brake according to the present invention.

Fig. 3 is a perspective view of an assembled rotor/stator module.

Fig. 4 is an exploded perspective view of the module of fig. 3.

Fig. 5 is a sectional elevation view taken along line 5-5 of fig. 3.

Fig. 6 is a partial perspective view of the interface between the rotor and stator of the rotor/stator module.

Fig. 7 is an enlarged elevation view of a portion of the cross-section of fig. 5.

Fig. 8 is a cross-sectional elevation view of the motor and integrated brake shown in fig. 1.

Fig. 9 is an enlarged view of a portion of the integrated brake shown in fig. 8 when released.

Fig. 10 is an enlarged view of the integrated brake shown in fig. 8 when engaged.

Fig. 11 and 12 are simplified side sectional views illustrating the modularity of the present invention.

Fig. 13 is a macro flow diagram of modular motor fabrication.

Detailed Description

Referring to fig. 1, the motor 12 with integrated brake of the present invention includes a left end plate 13 and a right end plate 14 which are secured to a housing 15 by suitable fasteners. In low torque applications, the fasteners may be radial screws, for example. Whereas in large motors, the end plate may be secured with axial bolts screwed into a thicker housing. Which rotates a driven member such as a sheave 17 of an elevator. The motor housing has a mounting base. In fig. 2, the housing 15 is omitted for clarity.

Referring to fig. 2, the end plates 13, 14 each have bearings therein, but only the bearing 41 of the right end plate is shown in fig. 2. Although not shown here, the bearing may have a cover to aid in lubrication and to prevent dust ingress. A slot 23 is formed in the shaft 21 to receive a key 24 for engaging a plurality of rotor/stator modules 28-30. Each of these modules has a corresponding slot 22 in its rotor to transmit torque from the rotor to the shaft. A washer 33 (see also fig. 8) is provided to prevent the rotor of the module 28 from engaging the outer race of the bearing 20. A spring clip 34 in a notch 35 in the shaft 21 engages the rotor of the module 30 to prevent relative axial movement between the modules 28-30 and the shaft 21, thereby maintaining the modules 28-30 in abutment with each other and in contact with the washer 33. Similarly, to prevent rightward movement of the shaft 21, a spring clip 36 (see also FIG. 8) is located in the notch 37 and contacts an inner race 40 of a right end bearing 41 of the shaft, which is shown only in FIGS. 8-10.

A brake disc 43 is slidably received by a pin 46 in an aperture 44 in the shaft 21 along an elongated slot 47. The brake assembly 49 includes an annular frame 50 having an annular groove 51 for the brake release coil and a wall 52 against which a stack of wave springs 53 will bear to engage the brake when the brake release coil is not energized. When the brake release coil is energized, a return spring 56 causes the brake disc to assume a neutral position in which it is in contact with neither the right end plate 14 nor the frame 50. This will be explained in detail later in connection with fig. 9 and 10.

Referring to fig. 3-7, each rotor/stator module includes a pair of flexible magnetic stator plates 60, 61 separated by a flexible magnetic ring 63 containing toroidal coils 64. The two stator plates 60, 61 have poles of opposite polarity, shown in fig. 6 as a north pole on the stator plate 61 (and a south pole on the stator plate 60), but the polarity changes when there is current in the coil 64. The poles 67 are separated by air gaps 68.

The rotors 28-30 of each rotor/stator module are formed by an annular flexible magnetic base 71 provided with a hole 72 for insertion of the shaft 21. On the surface of the base 71 are two rows of hard permanent magnets 74-77 (which may be NdFeB magnets) separated by a non-magnetic spacer 78 (although air may be present between the two rows of magnets 74-77). The south pole 74 in one row of magnets is axially aligned with the north pole 76 in the other row of magnets, and the north pole 75 in one row of magnets is axially aligned with the south pole 77 in the other row of magnets. Thus, there is a pair of magnets 74, 75 for each pole 67. Varying the arrangement, size and density of the magnets can be a variety of alternative designs. But requires an alternating magnetic field, multiple magnets, or an arc with multiple poles. The magnets 75-77 are shown in fig. 4 and 6 as being spaced from adjacent magnets, but they may be touching. In practice, they may be a solid ring of magnetic material or an extension of the magnetic material of the base 71 that is polarized to the appropriate polarity. The base 71 has a polarity induced therein that is opposite to the air gap polarity of each magnet 74-77 and provides an effective return path for the magnetic field.

Referring to fig. 7, the flux path shown by arrow 79 reverses with current flow. Pins (fig. 4) press fit within the ring 63 engage holes 82 in the stators 60, 61 to maintain alignment of the modules.

Referring to fig. 9 and 10, the frame 50 of the disc brake assembly 49 includes a pair of aligned holes 83 (fig. 10) in which aligned pins 84 are freely slidable, the pins 84 being press-fit into the holes of the stator 60 in the rotor/stator module 30. This pins the frame to the stationary part of the motor so that the frame 50 does not rotate against the force of the brake disc 43 when the brake is applied. Or the frame may be pinned to any suitable stationary part of the motor, such as the housing 15. A pair of brake coils 86, 87 are disposed within and proximate to the slot 51. Each coil is of sufficient strength and both coils are provided for extra safety when the brake is released. A shoulder 90 (fig. 9) engages the pin 46. The return spring 56 will move the brake disc 43 away from the end plate 14 when the brake is released and the pin 46 acting on the shoulder 90 (fig. 9) will prevent the spring 56 from allowing the brake disc 43 to pull the entire disc brake assembly 50.

The size and number of the wave springs 53 may be determined according to the required braking torque. They may be, for example, peak-to-peak springs as shown at website www.smalley.com/spring and supplied by Smalley Steel Ring company of Lake Zurich, Ill.

As can be seen from fig. 10, when the coils 86, 87 are not energized and the spring 53 is operated to engage the brake, a brake friction pad 92 on the brake disc will engage the end plate 14 of the motor. Similarly, the other brake friction pad 93 will engage the frame 50, which in turn is secured to the stator by the pin 84. In this way, the brake is integrated with the motor assembly with reduced space, mass and part count, thereby providing a more efficient and economical unit.

Instead of using the rotor/stator arrangement shown in fig. 1-7, the present invention is implemented using a transverse flux permanent magnet machine. Reference is now made to various topologies, such as those published in Harris m.r. paper "comparison of two designs of concentrated flux and surface magnets for VRPM (transverse flux) machines", the paper of the ICEM journal of turkey itenbul, 1998, volume 2, 1110-1122, which is incorporated herein by reference. The only critical requirement is that the direction of the torque must be perpendicular to the flux lines.

The manner in which a plurality of identical rotor/stator modules are combined into motors of various sizes using the modular design of the present invention is illustrated in fig. 8, 11 and 12. Each module contains one phase. The motor of fig. 1-10 has three modules and is operable by a four-phase AC power source provided, for example, by a well-known variety of variable voltage, variable frequency power converter (VVVF drive). Assuming that the torque provided by each module is sufficient to supply a 5 ton motor, the motor of fig. 1-10 would be a 20 ton motor.

In fig. 11, a three-phase 15-ton motor is shown. The VVVF driver supplies phase-dependent, separate drive currents to the respective modules 28 to 30 via the associated lines 104, 105, 106. Alternatively, each module may have its own separate drive for complete modularity.

In fig. 12, an elevator motor may have six modules operating on a common shaft; the modules may be separately driven by six different phases of AC power or the modules 28-30 and modules 28a-30a may be driven in parallel by the same three phase AC power. It is known that a six-phase power supply will provide smoother operation and lower losses.

Similarly, multiple modules, each capable of producing more or less torque, can be arranged as small as a pair of modules driven by a two-phase power supply, or as small as six or more phases driven by a three-phase or six or more phase power supply. For example, a three-phase drive can drive a motor consisting of 3N stator modules, where N can be 1-4 or some other small positive integer, where a plurality of similar modules share power from the three-phase drive.

Claims (9)

1. A modular, transverse flux, rotating electrical machine, wherein each machine (12) has:

a rotatable shaft (21);

a plurality of identical cylindrical transverse flux rotor/stator modules (28-30) disposed on said shaft, the flux lines (79) between the rotor and stator of said modules being perpendicular to the torque, at least one of said modules being adjacent at least one other of said modules in the vicinity thereof, each of said modules providing the same torque rating to said shaft, whereby the torque rating of said motor is equal to the torque rating of each of said modules multiplied by the number of said modules;

a rotary follower (17) arranged for rotation with said shaft; and

a plurality of end plates (13, 14), one for each of said modules (28, 30) that is not flanked by another of said modules;

it is characterized in that:

each of said motors including at least one brake assembly (49) compatibly formed with said modules and disposed between one of said modules not adjacent to another of said modules and an end plate of said end plate (14) corresponding to one of said modules;

at least one of said motors having a different number of said modules than at least one other of said motors; and

the length of said shaft is selected to accommodate at least said number of said modules, said brake assemblies, and said followers.

2. A modular, transverse flux, rotating electrical machine, said machine (12) having:

a rotatable shaft (21);

a plurality of identical cylindrical transverse flux rotor/stator modules (28-30) disposed on said shaft, the flux lines (79) between the rotor and stator of said modules being perpendicular to the torque, at least one of said modules being adjacent at least one other module in the vicinity, each of said modules being capable of providing the same torque rating to said shaft, whereby the torque rating of said motor is equal to the torque rating of each of said modules multiplied by the number of said modules; and

a rotary follower (17) arranged for co-rotation of said shafts;

it is characterized in that:

at least one of said motors having a different number of said modules than at least one other of said motors;

the length of said shaft is selected to accommodate at least said number of said modules and said follower.

3. The electrical machine of claim 2, wherein:

all of said modules of at least one of said motors are disposed on only one side of said driven member.

4. The electrical machine of claim 2, wherein:

two modules of at least one of said motors are arranged on each side of said driven member.

5. A modular, transverse flux electric machine (12) having:

a rotatable shaft (21);

a plurality of identical cylindrical transverse flux rotor/stator modules (28-30) disposed on said shaft, the flux lines (79) between the rotor and stator of said modules being perpendicular to the torque, at least one of said modules being adjacent at least one other of said modules in the vicinity thereof, each of said modules being capable of providing the same torque rating to said shaft, whereby the torque rating of said motor is equal to the torque rating of each of said modules multiplied by the number of said modules;

a rotary driven member arranged to rotate with said shaft; and

a plurality of end plates (13, 14), one for each of said modules (28, 30) that is not flanked by another of said modules, characterized in that the motor comprises:

a brake assembly (49) integrally formed with said modules and disposed between one of said modules which is not adjacent to another of said modules and an end plate of said end plate (14) corresponding to one of said modules.

6. The motor of claim 5, wherein said brake comprises: one or more coils (86, 87) which, when energized, release the brake;

a brake disc (43) having friction brake pads (92, 93), the brake disc (43) being arranged to rotate with the shaft and to slide axially on the shaft (46, 47);

a frame (50) provided with an annular groove for said coil or coils, which is pinned (84) to a stator plate (60) of said machine, but is axially slidable (83); and

at least one spring (53) urges said frame toward said end plate when said one or more coils are not energized, thereby engaging one of said pads with said end plate and said other pad with said frame, thereby providing a braking torque.

7. A method of providing a modular rotating machine (12) group, characterized by the steps of: selecting a torque increment; designing a cylindrical, transverse flux rotor/stator module to provide a torque equal to said increment and to have flux lines between the rotor and stator of said module perpendicular to the axis of said module; for each motor to be manufactured: selecting a shaft (21) for mounting a desired number N of modules to achieve or exceed the torque required by said motor and driven member (17) in less than said increments; attaching said follower to said shaft and said modules to said shaft such that said modules abut each other, said modules being attached to one or more sides of said follower; and at least one of said motors has a different number of modules than at least one other of said motors.

8. The method of claim 7, further comprising:

designing a brake assembly (49) having a cylindrical shape with a diameter no greater than that of said module; and

said brake assembly is mounted on said shaft adjacent one (30) of said rotor/stator modules (30).

9. The method of claim 7, further comprising:

selecting the number of phases P of the drive current of said module, where P is NX and X is a positive integer; and

said steps including mounting said modules with said number of phases oriented relative to each other.