GB2341731A

GB2341731A - Motor/gear drive arrangement of the planetary type

Info

Publication number: GB2341731A
Application number: GB9821834A
Authority: GB
Inventors: Michael John Flowerday
Original assignee: Individual
Current assignee: Individual
Priority date: 1998-09-16
Filing date: 1998-10-08
Publication date: 2000-03-22
Also published as: GB9821834D0; GB9820046D0

Abstract

An axial geared motor comprised of a stator and freely rotating rotor 4, such rotor being supported on a common output shaft by a suitable bearing(s), it being manufactured to incorporate an external sun gear 7 which in co-operation with cage mounted planetary gears 6 and a fixed internal ring gear 5 cause, by rotation of the cage directly fixed to the common output shaft 8, the rotation of this shaft, which is mounted in suitable bearings, providing an output drive, at full developed output torque, to either or each end of the motor. An arrangement having a fixed shaft and an output from the ring gear is disclosed. A freewheel action may be provided.

Description

-01 2341731 1.

PATENT APPLICATION In the name of Michael John Flowerday of 24 Kennedy Avenue, Gorleston, Great Yarmouth, Norfolk, England, a British Subject.

IMPROVEMENTS TO MOTORS WITH INTEGRAL PLANETARY GEAR BOXES Many forms of axial motors may be fitted with a gear box or may be manufactured to include a gear box. One common feature is that the motor shaft, turned by the rotor, rotates at a higher or lower speed than the gearbox output shaft. Many types of gearbox may be employed.

The planetary gearbox, incorporating a driven sun gear, a fixed internal ring gear and a number of 'cage' mounted planetary gears driving an output shaft, is one frequently chosen. It may be comprised of several stages. It is well known both in simple and compound planetary arrangements.

According to the present invention an axial motor and a planetary gearbox are incorporated within one housing in such a manner as to optimise the best features of each, to provide an improved, less expensive, more compact axial motor gearbox of the shortest length by eliminating a separate motor output shaft, enabling a single common motor/gearbox output shaft to extend at each end which will transmit the full gearbox output torque.

In the first arrangement shown a combined needle roller thrust bearing is employed to enable the rotor of the axial motor to rotate freely around a common output shaft whilst maintaining accurately the axial air gap. This freely rotating rotor is manufactured so that it incorporates the sun gear of the planetary gearbox arrangement. The ring gear of the arrangement is fixed to the case of the combined arrangement making full use of the relatively large diameter that an axial motor provides. The cage supporting the planetary gears which is caused to rotate within and around the ring gear is directly coupled to the common output shaft making the full gearbox output torque available at each end of the assembly.

In a second arrangement a freewheel is interposed between the cage and the output shaft enabling the assembly to be used to provide power for a cycle, wherein the shaft may be rotated in the forward direction either by the rotor or pedals fixed to the output shaft.

Other arrangements, not shown, may be provided employing additional stages of planetary or other gear arrangements mounted around and driving the common output shaft.

2.

The objects of the invention are to provide:

an axial geared motor of very short length comprised of a motor incorporating a stator, a rotor and a planetary gear arrangement with a single common output shaft available at each end.

an axial geared motor of very short length comprised of a motor incorporating a stator, a rotor and a planetary gear arrangement driving, via a freewheel or one way clutch, a single common output shaft available at each end.

Examples of the present invention will now be described with reference to the accompanying drawings listed below.

Fig. 1 A sectioned view of an axial geared motor incorporating planetary gear arrangement using an rotor mounted sun gear, a fixed ring gear and a rotating cage complete with planetary gears directly coupled to the output shaft. Fig. 2 A sectioned view of an axial geared motor incorporating planetary gear arrangement using an rotor mounted sun gear, a fixed ring gear and a rotating cage complete with planetary gears supported by and coupled to the output shaft by a free wheel or one way clutch.

Fig 1. Shows one example of electric axial geared motor, employing in this case a permanent magnet motor arrangement. Other stator rotor relationships may be envisaged, for example induction and switched reluctance motor types also other types of motor such as air or hydraulic may be employed. In this case the operation of such an axial permanent magnet motor is well known therefore it will not be discussed here.

The rotor 4 is supported by a combined needle roller thrust bearing 14 and may be made to freely rotate around the output shaft 8. The rotor 4 directly supports or is cut to provide an external sun gear 7. which meshes with a number of an external gears 6 which are mounted on a cage 10. These gears 6 are able to rotate without and around the sun gear 7 and within and around the ring gear 5. The rotation of the rotor 4 and the sun gear 7 causes the gears 6 supported on shafts 11 and bearings 13 to rotate thereby causing the cage 10 to rotate within and around the ring gear 5, it being fixed to the case.

The cage 10 being directly fixed to the output 8 shaft causes it to rotate at a reduced speed providing the associated increased torque.

3.

Fig 2. Shows a second example of an electric axial geared motor, employing in this case a permanent magnet motor arrangement to provide the power source for a motorised cycle.

The operation of the motor gearbox is as described for Fig 1 with the exception that the cage is supported on and around the common output shaft by the freewheel or one way clutch 18. In the forward direction of the rotor 4 the freewheel 18 is arrange to transmit the output torque developed to the common output shaft 8. If the rotor 4 were to be made to rotate in the reverse direction the output 8 shaft would not be rotated. The output shaft 8 can be rotated in the forward direction without rotating the cage 10 or rotor 4. When used to replace a bottom bracket assembly in a cycle, pedals and a chain wheel may be directly fixed to the common output shaft 8.

In both examples alternative bearing arrangements may be employed to support the common output shaft 8 and the rotor 4. The bearing spacer 17 used to accept the thrust of the rotor 4 and to accurately define the air gap between the rotor 4 and the stator 1 may be made in other forms, for example as a cast extension of the stator end plate 16, (not shown). Traditional and new materials as they become available may be employed in the construction. Various gear forms may be employed. The planetary gears may be simple or compound.

To those with knowledge of planetary gear arrangements it will be clear that such axial geared motors may be employed as the first stage of a compound motor gearbox wherein the common output shaft may be used as the input shaft of a second stage or maintained as a common shaft within a similar arrangement, the cage of the first stage supporting a second sun gear, ( not shown).

Also it will be clear that alternative examples employing the same principles may be arranged wherein the common shaft is fixed, ie. it is not allowed to rotate relative to the stator, the internal ring gear, suitably supported, becoming the output member connected directly or indirectly to the load, (not shown).

In each case the axial geared motors may be of very short length enabling them to be used in positions where combined axial motors with added gearboxes may not be used.

4.

Claims

Claims.

I An axial geared motor comprised of a stator and freely rotating rotor, such rotor being supported on a common shaft by a suitable bearing(s), it being manufactured to incorporate an external sun gear which in cooperation with cage mounted planetary gears and a fixed internal ring gear causes, by rotation of the cage directly fixed to the common shaft, the rotation of this shaft, which is mounted in suitable bearings, providing an output drive at ful I developed output torque, to either or each end of the motor.
2. An axial geared motor as in claim I wherein the cage is supported and coupled to the output shaft by a freewheel or a one way clutch to enable one direction of rotation of the rotor to rotate the output shaft whilst allowing the output shaft to be freely rotated in this same direction.
3. An axial geared motor as in claim 1 wherein the cage, incorporating a second sun gear is free to rotate around the common output shaft to provide the input drive to a second stage planetary gear box, the combined rotor/planetary gear arrangements rotating the common output shaft by directly or indirectly coupling the final cage to this shaft.
4. An axial geared motor as in claim I wherein multiple stages of planetary or other gear types may be arranged around the common output shaft.
5. An axial geared motor as in claim 1 wherein the common shaft and thereby the cage is fixed relative to the stator, the internal ring gear, suitably mounted being free to rotate providing the rotating output member,