WO1992021554A1

WO1992021554A1 - Motor-gear unit

Info

Publication number: WO1992021554A1
Application number: PCT/AT1992/000071
Authority: WO
Inventors: Manfred Wawra; Geza Beszedics; Werner Winkler; Franz Pavuza; Walter Toriser
Original assignee: Silent Motors, Elektrofahrzeuge Und -Antriebe, Entwicklung Und Beratung Gesellschaft M.B.H.
Priority date: 1991-05-29
Filing date: 1992-05-29
Publication date: 1992-12-10
Also published as: ATA109891A; AT400138B; AU1787892A

Abstract

A motor-gear unit (1) to provide electrical drive in vehicles, in particular bicycles. The unit has an iron-free disk armature (3) and a cycloidal gear unit, and a flange (2) incorporating a permanent pressure gate separates the motor (3) axially from the gears, the disk armature (3) being connected to a hollow shaft (9) and mounted with the shaft on the flange; the gear unit is mounted on the hollow shaft (9) at the driven end (22) and on a unit (23) which overlaps with the gear unit. This creates a compact motor-gear unit which can be accommodated near the axle or hub of a driven wheel, and makes possible a simple and space-saving mounting which can safely absorb all reaction forces.

Description

Motor-gear unit - 1 -

The invention relates to a motor-gear unit for the electrical drive of vehicles, in particular

Bicycles, with an ironless disc rotor and one

Cycloid gear. 5

Drive motors have become known in particular for the electric drive of bicycles, with a drive being carried out with the interposition of a transmission via parts of a transmission, such as chains or cardan shafts,

10, the dimensions of such drive motors and the associated gear mostly representing the essential limitation for the possible use. Correspondingly wide engines, which, however, were designed as carburetor engines, have already been proposed for the friction drive on the outside of a wheel near the tread. In such designs, the maximum width of the motor-gear unit is less critical than for use as a drive in the area of the axis of the wheel or a hub.

on ^• "Another previously known proposal for the formation of an electric drive in a hub of a vehicle saw the combination of a disc rotor in front of a cycloid gear, the proposed design in the axial direction relative large built and high in relation to load changes bean ^i" ^J sprucht was, which in turn required a great deal of effort for the storage.

The invention now aims to constructively reduce the size of a motor-gear unit of the type mentioned at the beginning

30 nern that with high drive torques and a correspondingly high reduction ratio, a powerful drive can be accommodated in the area of the axis of the driven wheel or in the area of the hub of such a wheel, furthermore with a simple and space-saving bearing design

35 all reaction forces, especially in the event of a load change, can be safely absorbed. To achieve this object, the motor-gear unit according to the invention essentially exists in the fact that a flange separating the motor from the transmission in the axial direction is designed with a permanent field yoke, that the disc rotor is connected in a manner known per se to a hollow shaft and is mounted on the flange with the latter, and that the transmission is driven .g is mounted on the hollow shaft and on a part spanning the gear. Due to the fact that the ironless disc rotor is connected directly to the gearbox with the interposition of a flange designed with a permanent field yoke, a relatively short axial length is achieved, while the required torque is made available on the output side by a correspondingly high reduction ratio can be. With such a construction, the axial overall length can be reduced to such an extent that such a motor / gear unit can be used directly as a hub of a bicycle without having to make significant structural changes to the frame parts of such a bicycle . Rather, the width can even be reduced to such an extent that installation in conventional forks or frame parts of a bicycle is made possible. At the same time, such a compact design of the motor and transmission as a hub-motor-transmission unit leads to a significantly improved weight distribution. The driving behavior of a bicycle equipped with such a motor hardly differs in this way from the driving behavior of a conventional bicycle without an additional motor arrangement. The fact that the disc rotor is connected to a hollow shaft enables simple mounting of the motor, the motor with the hollow shaft being mounted directly on the flange according to the invention. Due to the fact that the gear unit on the output side is mounted both radially inwards on the hollow shaft and radially outwards on a part spanning the gear unit, overall a greatly simplified bearing arrangement is created for the entire motor-gear unit, with provision of a Hollow shaft, which is mounted on the flange together with the motor on the one hand and on the other hand for supporting the transmission on the output side serves to create a balance. The motor is thus only supported on one side on the flange separating the motor from the gearbox, so that again a reduction in the overall width in the arrangement of the motor output and the ^* -

Storage is achievable. By providing a hollow shaft, which is both connected to the motor and supports the transmission on the output side, the bearings are provided in the interior of the motor-transmission unit and all reaction forces can be safely absorbed. Be at the same time

10 Static overdeterminations avoided due to the one-sided mounting of the motor.

The design of the gearbox as a cycloidal gear permits a relatively high reduction ratio with simultaneous ge

15 ring axial length, so that the combination of an ironless disc rotor with a cycloidal gear appears to give an optimum in the reduced space requirement of the motor / gear unit.

20 Advantageously, the design according to the invention is further developed such that a thru-axle is penetrated through the hollow shaft and that the transmission is mounted on the thru-axle on the output side. In this way, simple assembly is possible, while at the same time taking up force more favorably, the effort for

25 the storage of the engine can be significantly reduced. The storage of the hollow shaft relative to the gearbox encompassing this hollow shaft leads to a further reduction in the space requirement with simultaneously improved force absorption.

30 The design according to the invention is advantageously made such that the transmission output is formed by an output disk which, preferably elastically, is coupled to a hub encompassing the transmission. Such a design leads on the one hand to a particularly compact design and 35 on the other hand makes it possible to design the housing of the transmission directly as a hub encompassing the transmission, on the one hand making the tightness of the motor-transmission assembly easy can be achieved and on the other hand, a storage and absorption of the high reaction forces of the engine and transmission is much easier. The measure of elastically connecting the driven pulley to such a hub leads to an improvement in the absorption of acceleration and braking forces as well as dynamic impacts which act on the hub via the wheel and which in this way act on the gearbox and motor be decoupled.

In a particularly advantageous manner, the design is such that the flange separating the motor from the gearbox is sealingly connected to a pot-shaped motor housing, the end wall of which carries a field yoke facing the disc rotor and a commutation device, in particular a brush holder. Such a design permits simple sealing of the motor, only the annular gap between the rotating hub and the motor housing having to be provided with a separate sealing element for the complete sealing of the motor and gear unit.

To improve the introduction of force and to avoid tilting forces in the interior of the motor / gear unit, the design is advantageously such that a main wheel bearing for the wheel hub is located substantially centrally between the flange on the flange separating the motor from the gear unit the opposite end walls of the motor-gear unit is supported. In order to be able to absorb dynamic forces, as they are caused by the construction of the cycloidal gear, without eccentric loading of the hollow shaft or the plug-in axle, the design is advantageously made such that a balancing weight is attached to the hollow shaft in a rotationally fixed manner Eccentric of the gearbox is connected.

The further reduction of the dimensions in the axial direction is served by the advantageous embodiment, according to which the flange separating the motor from the gear is designed as a field yoke. By appropriate choice of material and shape here further space can be saved in the axial direction. In order to make a separate shielding unnecessary at the same time, the design can be made such that the wall thickness of the field yoke of the flange separating the gear from the motor is greater than or equal to the wall thickness of the field yoke on the front wall of the motor housing, with advantage that Motor housing, the gear cover and the hub are made of an aluminum alloy, in particular cast aluminum.

A particularly simple construction, in which expensive special components can be dispensed with, can be achieved in that the driven disk is glued in a rotationally fixed manner to a tubular gear part carrying the driven bolts of the transmission.

Also in the gear part of the motor-gear unit, further space-saving constructions can be realized in combination with the motor gear arrangement defined above. The design is advantageously made such that the tubular gear part is rotatably mounted on its inside on the hollow shaft and on its outside on a gear cover that overlaps the gear part and closes off the gear, thereby creating the possibility of the gear output within the axial Support the overall length of the gear in the radial direction outwards and inwards, thus ensuring a higher wear resistance of the bearing. The tubular gear part is supported on the outside on a fixed gear ring that supports the internal toothing of the gear, which in turn can itself be connected to the flange that separates the motor from the gear, so that the radial support is supported exactly Forces to the outside and a simple sealing encapsulation of the transmission is made possible. This design also enables simple lubrication of the gear unit since there is a sealing housing and a certain pumping action within this sealing housing on lubricant contained in the transmission by the balancing weights, which are non-rotatably connected to the eccentrically rotating carrier of the idler gears of the cycloidal transmission. The extensive necessary for this

Sealing of the gear housing can be improved even further by securing rings or cover disks being arranged on the side surfaces of the bearings for the tubular gear part which carries the output bolts of the cycloid gear, facing the interior of the gear, preferably with the main wheel bearing on the gear housing, in particular on one arranged between the flange and the gear cover and the ring housing which supports the internal toothing of the gearbox, is supported.

The design is advantageously made such that a sealing ring, in particular a Nilos ring, is provided on the side of the transmission facing the motor between the balancing weight and a bearing between the hollow shaft and the flange separating the transmission from the motor. In this way, a secure seal of the gearbox bearings is achieved.

The already mentioned elastic connection of the hub to the driven pulley can be realized in a particularly simple manner in such a way that the driven pulley is connected to the hub via a plurality of locking elements engaging on the circumference of the pulley, in particular silent rollers.

To improve the mechanical and electrical safety, the design according to the invention is such that bolt-shaped brushes which are guided in the radial direction and each acted upon by a spring are arranged in the disk-shaped commutation device, which brushes interact with the collector of the disk rotor which is connected to the hollow shaft in a rotationally fixed manner, the individual brushes are advantageously wired separately to the connection terminals of the commutation device. This last measure in particular helps to ensure that any electronic control Equipment for motor control cannot be affected by inductive effects.

A secure and sealing closure of the motor side of the motor / gear unit can be ensured in a simple manner by mounting the motor housing and the commutation device on the plug-in axle via a centering disk, as already mentioned, due to the preferred use a hollow shaft, which is connected to the disc rotor, the main bearing of the motor can take place at a distance from the commutation device and said centering disc.

The invention is explained in more detail below with the aid of an exemplary embodiment shown schematically in the drawing.

In the drawing, a hub motor 1 is shown, with an ironless disc rotor motor 3 on one side of a flange 2 and a cycloidal gear, which will be described in more detail below, on the other side of the flange 2.

The motor 3 is closed by a motor housing 5 which is connected to the flange 2 by means of screw connections 4, the housing 5 carrying field return elements on its inside facing the rotor 6, which are fixed to the housing by means of a screw connection 43. In the embodiment shown, the flange 2 separating the motor 3 from the transmission is itself designed as a field yoke, but it can also be provided that this flange 2 carries yoke elements 7 similar to the housing 5. Permanent magnets 8, in particular by gluing, are fixed to the return elements 7 or directly to the flange 2, NdFeB permanent magnets being used, for example, to generate a corresponding field. The rotor 6 is connected to a hollow shaft 9 which is penetrated by a thru-axle 10 which can be stored at the connection points 11 in the frame or the fork of a bicycle. Furthermore, a collector 12 is mounted on the hollow shaft 9, which cooperates with brushes 14 mounted in a commutation device 13 or a brush holder. The brush holder 13 is in a recess of the

Motor housing 5 fixed on the outside via screw connections 15, with a for centering the motor part 3

Centering disc 16 is used, which to the thru axle

10 is adjusted.

In the commutation device or the brush holder 13, for example, eight brushes 14 can be moved in the radial direction, evenly distributed over the entire ring surface, each brush being guided in a corresponding channel in the brush holder 13 and acted upon by a spring 17 in the direction of the collector. For the sake of simplicity, only a brush and an arrangement of permanent magnet pairs are shown in section in the drawing, and if they are arranged symmetrically, it must be assumed that the upper half of the picture is symmetrical to the lower half of the picture. The individual brushes 14 are separately wired directly to connection terminals, not shown, provided on the outside of the brush holder 13.

In the embodiment shown, in which the flange 2 itself forms the back yoke, the axial extent of the flange 2 is chosen such that it is greater than the axial extent of the yoke elements 7 fixed on the inner wall of the housing 5, so that no field lines emerge from the side of the flange 2 and additional shields on the side of the gearbox can thus be omitted.

On the side of the flange 2 facing away from the motor, a cycloidal gear immediately adjoins, such a cycloidal gear on the one hand providing a high reduction in the Order of magnitude of 1:20, for example, and at the same time enables a short axial construction. The hollow shaft 9 carries a first mounted eccentrically to the axis 18 of the thru axle

Gear wheel 19, which mesh with output bolts 20, which in turn interact with a bolt ring 21 of the cycloidal gear. For the output, the output bolts 20 are mounted on a further tubular gear part 22 which passes through the gear cover 23. The tubular gear part or output part 23 is coupled to an output ring 24 via plug pins 25. The further power transmission takes place via an adhesive connection 26 of the driven ring 24 with a driven disk 27, which in turn is elastically coupled, for example with the interposition of radially arranged silent rollers 28, to a hub 29 surrounding the gear part, into which spokes in openings 30 can be used and thus the movement can be transferred to a wheel, not shown.

The hub 29 is supported essentially in the center of the axial extent of the hub motor 1 via bearings 31, the bearings being provided on an annular housing 32 which is provided between the flange 2 separating the motor from the transmission and the transmission cover 23. The tubular gear part or driven part 22 is mounted on the one hand outwards on the inside of the gear cover 23 via bearings 33 and radially inwards on bearings 3 supported on the hollow shaft 9. The hollow shaft 9 is mounted with the ironless disc rotor 3 in the flange 2 itself via bearings 35. In the area of the driven disk 27, a further bearing 36 is provided for the tubular gear part 22 and a similar bearing 37 for the hub 29 is formed on the plug-in axle 10.

In addition to the one-sided mounting of the hollow shaft 9 with the iron-free disk rotor 3, a particularly space-saving mounting on the output side is also provided for the transmission by the bearings 33 and 34. When assembling the transmission, the individual components are pushed against each other, so that no axial play occurs for the bearings 33, 34 and 35. The ironless disc rotor and the gearbox as a whole balance the weight via the common hollow shaft.

Any minor radial play in the

Under certain circumstances, bearings could lead to a slight wobble movement of the rotor disk 6. Due to the fact that the flange 2 is formed directly with a permanent field yoke 7 or even as a permanent field yoke and the hollow shaft 9 is mounted together with the motor directly on the flange 2, the center plane of the rotor disk 6 is located in the immediate vicinity of the Bearing 35, so that any radial play that may occur only lead to negligible wobble movements. Due to the one-sided mounting of the hollow shaft 9 with the ironless disc rotor 3 it is avoided that additional bearings, as are provided in known designs in the area of the commutation device, which increases the width in known devices by overdetermining the Bearings additional reaction forces occur.

A seal 38 is provided between the hub 29 and the motor housing 5 or the flange 2 that separates the motor from the transmission, in order to seal the transmission area. For sealing the interior of the gearbox, sealing rings or locking rings, in particular Nilos rings, 39, 40 and 41, are provided on the bearings 33, 34 and 35.

The seal in the area of the bearing 35 is further improved by a balancing weight 42 which is offset accordingly to compensate for eccentric loads on the hollow shaft 9 by the eccentric 19 of the transmission.

For a correspondingly light design, the motor housing 5, the gear cover 23 and the hub 29 are made of an aluminum alloy, for example of cast aluminum. The design of the hub motor 1 is such that the width is matched to a fork or the frame of a conventional bicycle and that no specially made frame parts are required.

Overall, the use of an ironless disc rotor 3 with one-sided mounting of the hollow shaft 9 enables an exact and width-reducing arrangement of the motor output and the mounting, wherein in particular mounting in the area of the collector 12 can be dispensed with. Furthermore, through a suitable choice of the dimensions of the permanent magnets 8 as well as the inference 2 or 7 and the brushes 14 arranged in the brush holder 13, an extremely narrow construction is possible, which can be optimally adapted to the rotor disk 6. Due to an optimized design of the magnetic field, a slow runer is possible without changing the field geometry and the winding. By using an ironless runner, the formation of an inductive buffer of the energy present during electrical braking is made possible at the same time.

The essentially central mounting 31 of the hub 29 gives the possibility, with the bilaterally supported mounting of the thru axle 10 on a fork or on the frame, the forces occurring on the main axis on the one hand via the motor housing 5 to the wheel bearing and on the other hand via the centering bearing 37 Derive Guß¬ hub 29. In the case of one-sided mounting of the drive wheel, the central arrangement of the bearing 31 enables an optimally short mounting distance of the wheel level from the support point of the vehicle frame and thus a reduction in the side torques which may occur in the hub motor.

Due to the proposed housing division of the transmission into the flange 2 separating the motor from the transmission, the ring housing 32 and the cover 23, commercially available transmission kits can be obtained while maintaining the positive properties of a cheap, very narrow and easy-to-install design. As indicated above, the corresponding sealing enables the bearing has low-loss sump lubrication, which is supported in particular by the balance weight 42. This balancing weight is secured in its position relative to the eccentric carrier of the intermediate wheels by means of a corresponding locking device.

The cast hub can be provided with corresponding screwable supports, which enables the use of a wide variety of spoke shapes and drop center rims with a variable wheel diameter. Furthermore, by using a simple output toothing, which can only be detached from the quick-release axle 10 by means of a nut, the motor-transmission unit can be plugged in and thus can be exchanged in its entirety. As indicated above, the elastic coupling between the driven pulley 27 and the cast hub 29 via the silent rollers 28 dampens any mechanical vibrations that may occur between the fork and the driven gear.

Claims

Claims:

1. Motor-gear unit (1) for the electrical drive of vehicles, in particular bicycles, with an ironless disc rotor (3) and a cycloid gear, characterized in that a motor (3) separates the gear (3) in the axial direction Flange (2) is designed with a permanent field yoke (7) that the disc rotor (3) is connected in a manner known per se to a hollow shaft (9) and

10 is mounted with this on the flange (2), and that the transmission is mounted on the output side (22) on the hollow shaft (9) and on a part (23) which overlaps the transmission.

2. Motor-gear unit according to claim 1, characterized in that the hollow shaft (9) is penetrated by a thru-axle (10) and that the transmission is mounted on the output side of the thru-axle (10).

3. Motor-gear unit according to claim 1 or 2, characterized

20 characterized in that the transmission output is formed by an output disc (27) which, preferably elastically, is coupled to a hub (29) encompassing the transmission.

4. Motor-gear unit according to claim 1, 2 or 3, da¬

25 characterized in that the flange (2) separating the motor (3) from the transmission is sealingly connected to a cup-shaped motor housing (5), the end wall of which has a field yoke facing the disc rotor (3) and a commutation device, in particular a brush holder (13).

30

5. Motor-gearbox unit according to one of claims 1 to 4, characterized in that on the motor (3) from the gearbox separating flange (2) a main wheel bearing for the wheel hub substantially centrally between the opposite ^{■ ■} "the outer end walls the motor-gear unit is supported. - _« ,, _« „. PCT / AT92 / 00071 2/21554

- 14 -

6. Motor-gear unit according to one of claims 1 to 5, characterized in that a balancing weight (42) is rotatably connected to the on the hollow shaft (9) attached eccentric (19) of the gearbox Ge.

7. Motor-gear unit according to one of claims 1 to 6, characterized in that the motor (3) from the gear separating flange (2) is designed as a field yoke.

8. Motor-gear unit according to one of claims 1 to 7, characterized in that the driven disk (27) with a tubular gear bearing part (22) carrying the output bolts of the gearbox (22) is non-rotatably glued.

9. Motor-gear unit according to claim 8, characterized gekenn¬ characterized in that the tubular gear part (22) on its inside on the hollow shaft (9) and on its outside on a cross-section of the transmission part and the transmission ab¬ closing gear cover (23rd ) is rotatably mounted.

10. Motor-transmission assembly according to one of claims 1 to

9, characterized in that the main wheel bearing is supported on the gear housing, in particular on a ring housing which is arranged between the flange (2) and the gear cover (23) and which overlaps the gear ring carrying the internal gear of the gear.

11. Motor-gear unit according to one of claims 1 to

10, characterized in that securing rings or cover disks are arranged on the side faces of the bearings for the tubular gear part (22) which carries the drive bolts of the gearbox and which face the gearbox interior.

12. Motor-gear unit according to one of claims 1 to

11, characterized in that on the side of the transmission facing the motor (3) a between the balancing weight (42) and a bearing between the hollow shaft (9) and the Gearbox from the motor (3) separating flange (2) arranged sealing ring, in particular Nilos ring, is provided.

13. Motor-gear unit according to one of claims 1 to 12, characterized in that the driven disk (27) with the hub (29) via a plurality of locking elements (28) engaging on the periphery of the disk, in particular silent rollers, is connected.

14. Motor-gear unit according to one of claims 1 to 13, characterized in that in the disc-shaped commutation device (13) guided in the radial direction and each of a spring (17) acted upon bolt-shaped brushes (14) are arranged which brushes (14) with the one with the

Hollow shaft (9) rotatably connected collector (12) of the disc rotor (3) cooperate.

15. Motor-gear unit according to claim 14, characterized ge indicates that the individual brushes (14) are each wired separately to the terminals of the commutation device (13).

16. Motor-transmission unit according to one of claims 1 to

15, characterized in that the motor housing (5) and the commutation device (13) are mounted on the plug-in axle (10) via a centering disk (16).

17. Motor-gear unit according to one of claims 1 to

16, characterized in that the motor housing (5), the gear cover (23) and the hub (29) are made of an aluminum alloy, in particular cast AlTi.

18. Motor-gearbox assembly according to one of claims 1 to 17, characterized in that the wall thickness of the field back circuit of the gear from the motor (3) separating flange (2) is greater than or equal to the wall thickness of the field inference on the end wall of the motor housing (5) is.