GB2350489A

GB2350489A - Alternator bearing arrangment

Info

Publication number: GB2350489A
Application number: GB9916191A
Authority: GB
Inventors: David Johnathan Harris
Original assignee: Individual
Current assignee: Individual
Priority date: 1999-05-25
Filing date: 1999-07-09
Publication date: 2000-11-29
Also published as: GB9916191D0

Abstract

An alternator comprising a housing, a rotor and a stator, and, in use, a drive shaft for the rotor, characterised in that it has no moveable bearings supporting the drive shaft for the rotor.

Description

2350489 IMPROVEMENTS TO ALTERNATORS

Field of the Inmention

The present invention relates to alternators whether with rectification, to provide direct current, or unrectified.

Background to the Invention

The alternator has its origins dating back as far as 1831 when Michael Faraday first performed experiments involving passing a magnet back and forth within a coil of wire to generate electrical current within the coil circuit by electromagnetic induction.

Over the many years since then a multitude of alternator designs have been developed for a range of different applications. Nevertheless, the basic design of the alternator has not changed substantially. The wiring configuration of the coil around the stator may take a number of different forms and the rotor may have any number of magnetic poles and varying shapes but is nevertheless consistently assembled as a substantially integral unit with the drive shaft. The positioning of the rotor drive shaft within the alternator housing is fixed and defined by moving bearings such as ball bearings or needle or cased bearings that support the drive shaft on each side of the rotor within the alternator housing.

During development of a new and improved type of rotary engine described in the present applicants' co-pending UK patent application 99120925.5, the substantial limitations of conventional alternator assembly became apparent. Not only can the conventional alternator assemblies not be disassembled with optimal ease and not only are they vulnerable to wear of the movable bearing components and associated parts but their overall construction delimited by the moveable bearings severely restricts the ability of the alternator unit to have anything other than a single rotor mounted to the alternator's ddve shaft.

These unaddressed limitations of existing alternator design may even have been partly responsible for the motor industry's failure to overcome the low efficiency of alternator re-charging of car batteries that has hampered development of viable electrically powered vehicles.

Summary Qf the Invention

According to a first aspect of the present invention there is provided an alternator comprising a housing, a rotor and a stator, and, in use, a drive shaft for the rotor, characterised in that it has no moveable bearings supporting the drive shaft for the rotor. - Suitably, the alternator has a rigid aligning plate arranged to centre the housing and stator rigidly over the drive shaft. A plurality of long bolts is suitably provided to rigidly bolt the housing and stator to the rigid aligning plate.

Preferably, the rigid aligning plate has a convex profile, suitably arching toward the front of the alternator, to enhance its strength and the rigidity, which it imparts to the alternator assembly.

The alternator housing suitably compdses a front casing plate and the stator is sandwiched between the front casing plate and the rear aligning plate forming a rigid box structure around the drive shaft.

Preferably, the alternator is without an integral drive shaft for the rotor, the alternator having a passageway therethrough, including through the rotor, to mount onto an existing drive shaft. Such existing drive shaft is suitably integral with or coupled to a motor such as, for example, the internal combustion engine of a car or other vehicle and the alternator housing is suitably adapted to be bolted to a rigid structure or 2 housing from which the existing drive shaft protrudes and by means of which the alternator is centred over the drive shaft. In principle, the motor may be any supplier of motive force and could, for example, be a wind-driven propeller or water- driven impeller or the engine of a large or small powered appliance of any type.

The alternator suitably has a plurality of rotors within the alternator housing which are mounted, in use, at spaced intervals along the ddve shaft. Suitably the housing of the alternator has a respective spacer element/plate to separate each rotor and stator from each adjacent rotor and stator. By having plural rotors and suitably also plural stators, the alternator has a much higher power output potential for the single drive shaft and for a minimal alternator size and weight.

In an alternative embodiment, the alternator may have an integrally assembled rotor drive shaft without moveable bearings supporting the drive shaft. Suitably the drive shaft is supported substantially wholly by a terminal bearing at one end of the shaft which is mounted to the rigid aligning plate. This embodiment is particularly suitable for use as a manually cranked charging device. For this purpose it may be provided with a crank handle.

Preferably, the device further has one or more charge storage devices accommodated in the alternator housing. Suitably the charge storage devices comprise battery cells. The battery cells are suitably further augmented by capacitors to provide optimal rapid controlled release of the charge.

In a second aspect of the present invention there is provided a charging device which compHses an alternator having a housing, a rotor and a stator and a drive shaft for the rotor and further having a crank handle mounted to the drive shaft for the rotor whereby the drive shaft may be manually rotated in order to generate an alternating current. This device is preferably further provided with one or more charge storage 3 means and particularly preferably has one or more baftery cells accommodated within the housing suitably together with one or more capacitors for controlled discharge of the stored charge.

This hand cranked charging device may have a multitude of different applications including not only charging of car batteries or jump starting of car engines, but also applications such as powering of medical cardiac resuscitation units or even pacemakers. This device of the present invention may prove invaluable in emergency situations where the level of charge status of the existing battery powered equipment cannot be relied upon.

Brief Description Qf the Drawings

Two preferred embodiments of the present invention will now be more particularly described, by way of example, with reference to the accompanying drawings, wherein:

Figure 1 is a transverse sectional view of the first preferred embodiment of alternator mounted on to the drive shaft of an engine; Figure 2 is a view of the components of the alternator separated to illustrate their assembly; Figure 3 is a transverse sectional view of the second preferred embodiment of alternator adapted as a stand alone unit for manual operation; Figure 4 is a view of the separated components of the second embodiment; and Figures 5 and 6 are respectively front and rear elevation views of the second preferred embodiment.

4 Description of the Preferred Embodiments

Referring firstly to the embodiment of Figures 1 and 2, this embodiment of the invention is adapted to be retrofitted onto a drive shaft 1 extending from and powered by an engine. The drive shaft I may suitably be directly coupled to the engine and projecting from the engine casing. The altemator mounts concentrically over the drive shaft 1 and is bolted to the engine casing 2.

The alternator comprises, in sequence of assembly from the front: a front casing plate 3 of the alternator housing; the stator 4; the rotor 5 having a hollow bore 5b to mount directly onto the engine drive shaft 1; a brush holder plate 6; a rear body plate 7 carrying a diode and rectifier 8 and multiplug for the generated electrical supply; and a rigid rear aligning plate 9; the whole assembly being fastened together by long bolts 10. The rigid rear aligning plate 9 provides the backbone for the assembly. It has a forwardly arching convex profile for added strength and rigidity. The front casing plate 3 and the rear aligning plate 9 each have an upstanding circumferential wall 3a, 9a, respectively which face towards each other and which sandwich the stator 4 and rear body plate 7 between them and collectively forming a rigid cylindrical box structure.

The bolts 10 extend through respective apertures in circumferential radially spaced apart turrets on each of the front casing plate 3, stator 4, rear body plate 7 and into the rear aligning plate 9 to give the assembled unit structural integrity. The rear aligning plate 9 is, in turn, secured by bolts 11 with spring washers to the engine casing 2 in a rigidly supportive manner, holding the alternator housing in a fixed concentric position around the drive shaft 1.

As will be seen, there are no moving bearings surrounding the drive shaft 1. This is in marked contrast to conventional alternator construction which generally entails provision of ballbearings or other moving bearings such as cased or needle 5 bearings between the rotor drive shaft and altemator housing to support and maintain the concentricity of the rotor drive shaft. In this first preferred embodiment there is no need for any form of bearing between the drive shaft 1 and the alternator housing comprising the components 3, 4 and 7. The only necessary contact is between the 5 brushes 18 on the brush holder 6 and the collector rings on the rotor 5.

Partly as a result of there being no moving bearings there is, furthermore, little substantive limitation on the number of rotors 5 that may be mounted onto the drive shaft 1 within the alternator housing. A number of such rotors 5 may be positioned along the drive shaft I at spaced intervals, suitably separated by spacer plates (not shown). The spacer plates may have a form similar to the rear body plate 7, for example, and serve to isolate each rotor 5 and stator 4 from each adjacent rotor 5 and stator 4. In such arrangement the front casing plate 3 may be strengthened like the rear aligning plate 9 by altering its shape to be similar to that of the rear aligning plate 9 or by augmenting it with a further plate. Furthermore, the diode and rectifier 8 and multiplug and any other electrical processing components are suitably repositioned to an end plate and may be located on a circumferential outer surface of the plate.

To assist mounting of any additional front plate to the front of the front casing plate 3, which may be used, for example, to carry a pointless ignition unit for a car engine or for strengthening, the long bolts 11 suitably have heads with threaded sockets to receive further bolts.

Turning now to the second of the two illustrated embodiments, as shown in Figures 3 to 6, this comprises a completely self-contained alternator unit. Here the alternator unit has its own rotor drive shaft 12. This alternator, furthermore, has its own charge storage units/batteries 13 built into the alternator housing to make the device wholly independent and suitable for use, for example, as a manually re- chargeable 6 power supply for jump starting a car where the cars battery is flat or for powering a cardiac resuscitation unit.

The general configuration of the components is substantially the same as for the first preferred embodiment and like parts carry like numbering.

The most notably differently shaped common component is the rear aligning plate 9' which, in its rear face, is flatter than the rear casing plate 9 of the first embodiment since it does not need to conform to the shape of a fixed structure for mounting. Instead, the relatively flat rear casing plate 9' of the second preferred embodiment is enclosed on its rear face by a covering plate 14 which, as illustrated in Figure 6, is suitably provided with the respective positive and negative output electrodes with crocodile clips housed in pockets on the rear face of the unit. This cover 14 may also suitably accommodate further electrical circuitry including capacitors etc.

The front face of the unit is provided with a front cover 15 that bolts to the front casing plate 3 by short bolts that screw into the threaded heads of the long bolts 11.

The front cover suitably further has side walls which extend therefrom to surround the componentry of the alternator and serve to extend the housing laterally to house the battery cells 13 and any other desired processing circuitry.

The rotor drive shaft 12, is pinned to the rotor 5 and is supported within the alternator housing substantially solely by a terminal support bearing 16 at the rear end of the shaft 12. This bearing 16 has a cup-shape and is suitably lined with gauze or other low friction lining with oil lubricant. The bearing 16 is a static bearing and because of its terminal positioning allows for the possibility of mounting a plurality of rotors 5 onto the drive shaft 12.

7 Rigid holding of the drive shaft 12 is assisted by the rear body plate 7 pressing down against the outer rim 21 of the cup-shaped bearing 16. Indeed, as will be seen from figure 3, the central aperture of the rear body plate 7 through which the shaft 12 extends has a stepped bore rim 22 which accommodates the outer rim of the bearing.

As with the first preferred embodiment, the rotor 5 has a hollow bore through which the drive shaft 12 extends. It may be held to the shaft 12 to rotate therewith either by a tight friction fit or by longitudinal splints along the outer circumference of the drive shaft 12 or, indeed, by use of pins 17 or screws.

Further in contrast to the first preferred embodiment, the drive shaft 12 is adapted to be rotated manually by use of a crank handle 20. A guide annulus 23 is provided in the front casing plate 3 through which the drive shaft 12 passes and which assists centring of the shaft 12.

Operation of the handle 20 enables generation of a current that may be fed directly to an electfically powered appliance, possibly via intermediacy of one or more capacitors. Electronic componentry including switch circuitry is suitably provided to enable selection between different modes of operation. For many purposes the ability to store high levels of charge in the in-built battery cells may be the most important facility. High efficiency batteries such as gel batteries are preferred.

This facility enables use of the device to power a portable cardiac resuscitation unit, for example. The performance of the unit may, for this and other purposes, be further enhanced by incorporating suitable gearing which may most conveniently be mounted to the front end of the device perhaps in a casing that is mounted to the front body casing 3. A step-up transformer is suitably also incorporated into the device.

8 Although it is particularly preferred to configure the device to have multiple rotors and stators within the alternator housing it is alternatively possible to use multiple separately housed alternators together mounted in series to a common drive shaft.

The device of the first embodiment of the present invention when used in series can 5 efficiently re-charge a car battery from one alternator while directly powering an electric car motor.

The system may lessen the need for large numbers of batteries and lead to electric powered vehicles becoming truly viable. This may apply not only to cars but potentially also to other vehicles such as electrically powered aircraft, for example.

The benefits of the present invention may be realised in powering or charging a wide variety of vehicles or appliances.

9

Claims

An alternator comprising a housing, a rotor and a stator, and, in use, a drive shaft for the rotor, characterised in that it has no moveable bearings supporting the 5 drive shaft for the rotor.
2. An alternator as claimed in claim 1, wherein the alternator has a rigid aligning plate arranged to centre the housing and stator rigidly over the drive shaft.
3. An alternator as claimed in claim 2, wherein a plurality of long bolts are provided to rigidly bolt the housing and stator to the rigid aligning plate.
4. An alternator as claimed in claim 2 or claim 3, wherein the rigid aligning plate has a convex profile, suitably arching toward the front of the alternator, to enhance its 15 strength and the rigidity which it imparts to the alternator assembly.
5. An alternator as claimed in claims 2 to 5, wherein the alternator housing comprises a front casing plate and the stator is sandwiched between the front casing plate and the rear aligning plate forming a rigid box structure around the drive shaft.
6. An alternator as claimed in any preceding claim, wherein the alternator is without an integral drive shaft for the rotor, the alternator having a passageway therethrough, including through the rotor, to mount onto an existing drive shaft.
7. An alternator as claimed in claim 6, wherein the existing drive shaft is integral with or coupled to a motor such as, for example, the internal combustion engine of a car or other vehicle and the alternator housing is adapted to be bolted to a rigid structure or housing from which the existing drive shaft protrudes and by means of which the 5 alternator is centred over the drive shaft.
8. An alternator as claimed in any preceding claim, wherein the alternator has a plurality of rotors within the alternator housing which are mounted, in use, at spaced intervals along the drive shaft.
9. An alternator as claimed in claim 8, wherein the housing of the alternator has a respective spacer element/plate to separate each rotor and stator from each adjacent rotor and stator.
10. An alternator as claimed in any of claims 1 to 5, wherein the alternator has an integrally assembled rotor drive shaft without moveable bearings supporting the drive shaft.
11, An alternator as claimed in claim 10, wherein the drive shaft is supported substantially wholly by a terminal bearing at one end of the shaft which is mounted to the rigid aligning plate.
12. An alternator as claimed in any preceding claim, wherein the device further has one or more charge storage devices accommodated in the alternator housing.

11
13. An alternator as claimed in calim 12, wherein the charge storage devices are further augmented by capacitors to provide optimal rapid controlled release of the charge.
14. A charging device which comprises an alternator having a housing, a rotor and a stator and a drive shaft for the rotor and further having a crank handle mounted to the drive shaft for the rotor whereby the drive shaft may be manually rotated in order to generate an alternating current.
15. An alternator or charging device substantially as hereinbefore described with reference to any suitable combination of the accompanying drawings.

12