GB2386479A

GB2386479A - Slow speed electrical machine of modulardesign

Info

Publication number: GB2386479A
Application number: GB0314546A
Authority: GB
Inventors: Branko Richard Babic
Original assignee: Individual
Current assignee: Individual
Priority date: 1998-07-07
Filing date: 1999-07-07
Publication date: 2003-09-17
Anticipated expiration: 2019-07-07
Also published as: GB2386479B; GB0314546D0

Abstract

A motor or generator comprises modular units including a rotor comprising an axially directed magnet having end mounted radially facing poles, the poles being circumferentially off-set and respective stator pole assemblies face the rotor poles, the stator poles carrying windings. Successive modules are arranged with like poles adjacent and poles offset between modules. End magnets, 22a, may be included to prevent flux leakage. The machine may have up to 48 rotor teeth and 48 windings per rotor pole allowing the machine in the generating mode to be driven by a slow speed power source eg spring or wind power. A design of the stator/rotor teeth is disclosed.

Description

t MEC=NICOELECTRICAL MACHINES

10 The present invention relates to electrical machines which are either generators of electricity or.motors.

The well known means of storing energy in mechanical springs has been established for many centuries The availability of modern metal and synthetic materials that lend 15 themselves to be made into units that can store energy has rekindled the interest in such systems for many different machines.

The basic principles of such machines is the energy contained in a material that is energised by being stressed by a variety of means and is then allowed to release the 20 potential energy, in a controlled way. Many such systems exist and the most common is the steel spring that powers very many devices. The spring is energised by being compressed. The release of energy contained in the coiled spring is usually controlled by a system of cogs that translate the energy output into motion by a variable arrangement of cog sizes that allows conversion of potential energy of an uncoiling 95 spring into directed motion. The cogs turn, the rate of turning is precisely calculated and the energy needed to achieve the required result is utilised by eg the moving hands of clock. This well established principal can be adapted to modern technology.

In many parts of the world there is a difficulty in delivering electricity to users. The 30 cost of the conventional systems for storing electricity are too high or not available. The need for a mechanical system for storage of energy is again proving useful. Modern technology has a large number of electrical circuits that lend themselves to being utilised with the mechanically stored energy systems.

l 5 The usefulness of these systems can be extended to providing mechanically operated machines that are particularly needed in situations where energy supply is limited However, the output of conventional mechanically powered generators is irregular if driven by a source with a slow rate of rotation. This problem is mitigated or overcome by a machine according to the present invention as defined in claim 1. Some preferred 10 aspects of this invention are defined by the dependent claims.

Of course, it is very well known that machines comprising a rotor/stator arrangement can function as either electrical generators (whereby mechanical energy to rotate the rotor is converted to an electrical output from the stator windings) or as motors 15 (whereby electrical energy applied to the stator windings causes the rotor to turn to produce a mechanical drive). Thus, a first class of electrical machine according to the present invention is an electrical generator. A second class of electrical machine according to the present invention is a motor.

20 Regarding the second class, a particularly preferred sub-class of motors comprises stepper motors. A machine according to the present invention lends itself exceptionally well to being used as a stepper hybrid motor. The advantage is that the performance of the machine is directly proportional to the number of elements. As an example only, if one staclc (i.e. rotor/stator combination) provides a mean of the stepper motor having a 25 design criterion of providing say, 400 steps per revolution then by such a design specification, one can double that performance by installing a second stack on the same

axis of such a motor. The double stack design would then have 800 hundred steps per revolution. By adding a further stack to such an assembly the total output of such a tree stack assembly will be 1200 steps per reevaluation. One can further add yet another 30 stack on the same axis and produce a stepper motor that will provide 1600 steps per revolution. The advantage of the multi stack design is that engineering facilities are about at the end of their practical, manufacturing limits. The capacity for the mass produces 35 tolerances limits the number of elements within existing designs.

go- The multi stack design allows relatively crude manufacturing methodology but the multiplicity of assembly of stacks, allows for hybrid stepper motor designs that can far surpass any of the lamest of high tech stepper motor designs currently available.

10 Hybrid stepper motors with double or quadruple the best number of steps currently available can be produced using our multi stack design.

The present invention will now be explained in more detail by way of the following description of preferred embodiments and with reference to the accompanying

15 drawings, in which: Figure I shows a schematic of a light generating system using an electrical generator according to the present invention; 20 Figure 2 shows a schematic of a mechanically driven microwave oven utilising an electrical generator according to the present invention; Figure 3 shows a mechanically powered fridge/freezer utilising an electrical generator according to the present invention; Figure 3A shows a block diagram of the fridge/freezer shown in Figure 3; Figure 4 shows a schematic of a torch utilising an electrical generator according to the present invention; Figure 5 shows a portable lighting unit powered by an electrical generator according to the present invention; Figure 6 shows an arrangement for supplying wind-derived mechanical energy 35 to an electrical generator according to the present invention;

s Figure 7 shows a schematic of a gearless mechanical drive for use with an electrical generator according to the present invention; Figure 8 shows a schematic cross-sectional representation of a viewed end-on of 10 a rotor and stator for use with an electrical generator according to the present invention; Figure 8A shows a cross section through respective rotor poles, and Figure 8B shows in side view a first embodiment of an electrical generator according to the present invention; Figure 9 shows in perspective, a second embodiment of an electrical generator according to the present invention, utilising a plurality of axially stacked units each comprising a combination of a permanent magnet rotor and a stator, each analogous to the generator of the first embodiment, the stators having been omitted in the drawing 20 for clarity; Figure 10 shows a CAD representation of the rotor of the kind used in the generator of the second embodiment; 25 Fig 11 shows the arrangements of casteilations of a stator for use in a generator according to the present invention; Fig 12 shows schematically, the arrangement of the various sections of a generator according to the present invention; Fig 13 shows the arrangements of stator castellations and rotor teeth of the arrangements shown in Fig 12; Fig 13a shows a modified design of tooth and casteilation sections which could be used instead of the arrangement in Figure 13,

l r Fig 14 shows a mechanical means for controlling the rate of off-load stored energy from the output of a generator according to the present invention; Fig 15 shows an alternative method of controlling the rate of off-load energy 1 0 storage; Fig 16 shows a large diameter stack arrangement for use in a generator according to the present invention; 15 Fig 17 shows another stator/rotor arrangement for use in the generator according to the present invention, demonstrating a second offset stack of 8 poles; Fig 18 shows a further castellation and tooth arrangement, wherein the castellations are pointed; Fig 19 shows a side view of a single stack comprising only two stator poles, for use in a generator according to the present invention and utilisin;, small permanent magnet end pieces to deviate magnetic leakage; 25 Fig 20 shows a four-stack arrangement for use in the generator according to the present invention; Figs 21 A, B and C show how the tip of a geometrical configuration of pointed tooth geometry can be adapted to optimise flux induction; and Figs 22 and 22a show the arrangement of small permanent magnets at the end of stacks of a generator according to the present invention.

With this in mind a light generating system that can supply a given amount of light is 35 specified in Figure 1. In this design a portable unit is described where a spring loaded

for, ') 5 system is attached to a transducer, here meaning, the means by which mechanical energy is translated into electrical energy, that is designed to deliver the required amount of energy to the light bulb. The energy delivered by the spring is delivered by means of a control system here, herein referred to as the "control elements" and is utilised by means of an on/off switch at the required site. The.control elements also 10 contain the controlling mechanism that stops the unwinding of a spring when the switch is in the off position.

A further useful system specifies a mechanically driven microwave useful for the preparation of food. In this case the energy stored in the spring I of Fig 2, is released I S via the transducer 2 to be optimised and controlled by circuitry contained in the control elements of 3. The energy emerging in a controlled way out of the control elements is used to generate microwaves in the generator 4.

A further useful system is the arrangement for kitchen appliances. Figure 3, shows a 0 system in which the energy of a coiled spring is released to provide power for example a fridge freezer. In this arrangement, the coiled spring I releases mechanical energy that is.transduced 2, into electrical energy and released into the arrangement. Typically the fridgelfreezer can have an arrangement whereby the current is made to flow via the necessary elements that control the energy usage to drive the motor that compresses the 25 freezing fluid contained in the condenser unit. the condenser unit is arranged so that the cooling arrangement or evaporator unit, is contained within the compartment 6 containing the contents. In this figure, the compartment containing the freezer is itemised as 7.

30 The refrigerator circuitry is further explained by Figure 3A in which the electrical energy emerging from the transducer is utilised to provide a number of services. The electrical energy provides a means of illuminating the inside of the compartment by means of the interior light 2 which is controlled by the on/off switch 3. The start relay 8, for the motor compressing the freezing fluid in 6 is controlled by the the thermostatic

5 control unit 4. The thermal overload and other essential components are controlled by the control elements 3 in Figure 3.

A further use of the above is specified in Figure 4 which is a smaller arrangement of the same system. In this case the distal end of a hand held torch containing the spring 1 is 10 attached to a transducer 2. By rotating the end piece the spring contained therein is energised and allowed to unwind as the switch 4 is connected. The control elements control the release of energy that flows through the element of the low energy bulb 5.

Light is produced for as long as energy is contained in the loaded spring.

15 All the elements needed to make the above systems work are available off the shelf and need to be optimised, to provide the level of service specified. Suitable springs are available that can provide the energy needed to drive the above arrangements. Springs of a few grams to 100 kilograms are available. The greater the amount of energy needed to be stored the larger the spring. For the limited domestic lighting system, a spring of 20 say 50 kg can provide sufficient quantity of energy to provide lighting to a small family unit. It is envisaged that a portable unit is situated in the area and tapped by means of extension cable providing a light bulb. Low energy light bulbs have become available that will provide the lighting requirement from the above assemblies (see Fig I).

25 The problem of constant energy output i f spying energy supply systems is resolved by the use of constant force springs Tensator,iLtd manufactures a large number of spring designs that can very usefully be applied to the above applications.

The usefulness of constant force spring systems is principally the length of the spring 30 that can be wound onto a drum. Extensive periods of constant force can be provided by extending the length of the spring. The basic mechanism is a two drum system which works in an antagonistic manner. The tensile stress induced by the manufacturing process, forces the drum to rotate so that the spring can resume its original curvature.

By reverse winding the spring on a second larger drum, the stresses induced, in the 35 stainless steel with about 17% chrome and 7% nickel material, during the

- N 5 manufacturing process, provide the energy of motion, The stretching of the curled spring in the opposite direction to the induced curb provides the force of motion by resuming its original position as it returns to its original shape. The provision of constant torque is induced in the larger of the two drum assembly (see Figure 7).

10 The two drum arrangement therefore consists of the tensor spring being wound on a storage drum Of a given diameter. These stainless steel or high carbon textured spring steel strips are pre stressed and thermally processed to assume a curled configuration so that the curled spring manifests a powerful tendency to remain in the curled position.

These springs will resist being unrolled and by designing arrangements where single or 15 in multiple arrangements the springs are unwound onto a larger drum in a reverse attitude, the tensile forces in the stretched spring induce potential energy. The potential energy is released- into kinetic energy. The unwinding process induces a constant torque at the shaft of the larger drum by means of localized release of tensile forces. The tensile strength of the spring induces-a constant force because as the spring material 20 recurls to resume its original position the release of the potential energy is exhausted and that part of the spring is not contributing to the overall movement of the motor shaft. This system provides powerful constant energy for long running motors for the entire length of the wound spring.

25 The assembly of the two drum spring system motors therefore consists of a storage drum and a tensor spring. In situations where a large torque is needed assemblies consisting of many springs wound on storage drums attached to one torque drum are possible. In this way the sum of the forces of the storage drum springs is available to drive the torque drum and transfer the kinetic energy to the shaft of the motor being 30 driven. Theoretically a large number of such assemblies are possible with the storage drum being a long shaft accommodating multiple spring assemblies along its plane or circumference. This system is basOically a general purpose unit that is intended to provide a base facility 35 from which a variety of systems can be tapped. Fig S illustrates a portable lighting

! I 5 system with a LOW ENERGY FLORESCENT BUI-B. We have developed with the help of a florescent bulb manufacturer, at our request a florescent light bulb that works off 5 Volts and 80- 180 milliamps of current. There are a number of permutations to these low voltage florescent light bulbs but by providing more current at 5 volts or by increasing the voltage and maintaining the current the total energy output from these 10 devices can be designed to order. We are therefore designing LOW VOLTAGE FLORESCENT LIGHT BULBS specifically to work off the spring stored energy systems. These systems are then further modified to work with rechargeable battery spring energy systems. The storage can be one of a number of available systems such as capacitors etc. The portable unit therefore can provide power for a number of different systems.

As a further example the terminal ends situated in this unit can be tapped at the suitably positioned terminals, be they AC or DC, to provide trickle charge for rechargeable 20 battery systems and the like.

In Fig 5, item 2 is a low energy florescent bulb or a specially designed diode light emitting device, 3 is the connecting conductors, 4 the terminals via which all outside utilities are to be connected, 5 the torque output drum, 6 the winding handle, 7 the 25 carrying handle.

Figure 6 shows a slow rotating generator design being used to generate electricity using wind power rather than spring stored energy. The advantage of this unit is that the slow rotating generator can be turned by even the slowest of wind speeds. The generation of 30 energy by this system provides large amounts of energy depending on the size of the unit Item l is the body of the generator, 2 the propeller that can vary in size depending on the amount of torque required by the generator, designed for a specific output, 3 is the generator axle connected to the propeller, 4 the mounting system and 5 the suspending attachment.

Rae \ 5 Stop mechanisms can be activated by mechanical or electrical means and are shown in Figure 7.

The fact that the torque exerted by these springs is very great and can be designed for a given job makes the constant spring technology very useful. Their long action facility 10 provides a means by which the spring use can be controlled to provide long unwinding time This means that in practice the spring can provide power over a long period of time. Given that the required torque can be induced in the spring then machines which provide power over a period of many days become possible.

15 In order to provide power output over an extended time alternators of a new design are required. Currently, no alternators which have an axial rotation of I rps or less exist.

For longevity of power output slow rotation speeds of alternators is essential if time of effective power output is to be increased. It is proposed that alternators with an increased number of fields is designed for use with the above systems. The design is to

20 be investigated in which an alternator proposed for generating current from springs rotates at a very slow speed. In this way it is proposed to reduce the rate at which the spring is uncoiled. The energy output is therefore extended by the reduction in the uncoiling rate. As the torque can be designed into the spring design, the reduced rate of uncoiling does not affect the total energy stored within the spring.

To generate the required number of cycles per second, required to power.. a currently available microwave, lighting, cooking, cooling and other technologies proposed, a multi-field alternator is proposed. In this design, the armature will have a

large number of independent coils producing fields as the armature rotates about its

30 axis. To produce SOc/s an armature has to rotate 3000 revolutions/mint In the spring technology this rate of revolution depletes the spring stored energy at a fast rate. The design of an armature which has 50 fields per armature will require 60 turns/min to

produce the 50c/sec output. The availability of such alternators will increase the length of time the spring generated appliances can continue to world, many fold. The multi

A/ - - - 5 pole alternators therefore will rotate at a slow rate to;, enerate the required output for the proposed variety of appliances (see Figure 8).

The extensive use of spring generated power extends not only to the third world requirements but also to the sophisticated markets of the industrialized countries Currently, battery power, provides much of the required energy in portable machines and appliances. The cost of batteries and the reliance on expensive chemical energy makes the spring technology very attractive to a very large market. The camping industry, the caravan home industry, the boating industry, the portable appliance 15 industry, the emergency lighting industry, the toys industry, and many other uses in which appliances require expensive batteries, can all benefit from the spring stored energy. In the camping industry for instance the spring generated small portable and large 20 portable and fixed microwave units can be manufactured to provide cooking and food heating facilities. One of the more difficult and at times dangerous problems of camping is the gas cylinders, which are normally used to provide cooking heating and lighting facilities. The use of spring powered appliances obviate the problem of replacing energy supplies for these appliances. Small units can be designed for 25 individual use or large portable units for family use.

In the caravan and boating industry a similar appliance can be installed in virtually any situation. On small or large family type caravans or maritime vessels, the availability of spring energised cooking and lighting systems will obviate the need to store and use 30 flammable gas units or battery stored chemical energy.

In the emergency lighting or portable lighting units, the availability of spring stored energy will obviate the need to have independent motorised generating power. A large number of appliances for emergency use such as hand carried torch type light units can 35 be designed to replace the current battery operated torches. The leakage of energy from

! - , 5 chemically stored energy in batteries is a major problem with long term storage of chemical power units The mechanical spring energy sources do not suffer from long term storage fatigue or loss of energy. The small portable lighting units can be used in many situations to replace existing chemical battery energy units. Torches with springs can take any form or shape, size or potential energy output and can be used as 10 emergency lighting in vehicles or static units which can be switched on in case of mains supply lighting failure.

The provision of the hot element type heating unit becomes possible with the above technology. Elements supplied by current from the above system can in the fixed unit 15 design cookers and heaters be made to work for suitably long periods to allow a family to prepare its food. In situations where the only cooking fuel is wood, a spring loaded cooking facility will reduce the damage done to the environment, Further to the above design criterion of multi-field generators. The concept of using

20 multi-field generators for the powering of the above mentioned designs has now been

found to be very viable. Detailed calculations and computer modelling designs have shown that multi-pole generators as envisaged in the above use are possible and will work off a very low number of axial turns.

5 The need to reduce the rate at which the spring powered electro mechanical machines deplete the spring tension is essential if such machines are to become useful in the public domain. All attempts to provide spring powered machines have to date failed because the rate of energy depletion of currently available springs is too high. Such designs have to be energised frequently and very quickly become user un-friendly. The 30 only way to overcome this problem is to reduce the number of times that users have to wind the mechanism in order to make the machines to do the required work. There is a limit to the sizes and multiple arrangement that springs can usefully be designed. The best way to overcome this problem of short life of usage is to reduce the rate at which springs are depleted.

5 The only way to reduce the depletion rate of springs in these applications is to use a slow axial rotating generator. Calculations show that multi field generators are possible

and in fact can give us more than the required criteria. As an example only, a 100 pole generator producing 500 watts of energy at a potential difference of 225 volts can power the above designs at only one turn of the armature per second. In effect by using 10 such a slow rotating generator we extend the time of the spring depletion by 50 times that of current.designs using generators that rotate at standard speeds.

In all cases therefore it is proposed that for our designs of portable or fixed spring driven electro mechanical machines, use slow rotating generators, as a means of 15 extending the length of time that a wound spring can release its energy, to power such designs. The design of portable or fixed electrical lighting systems, fridges, freezers, microwave or radiant heat cooking facilities, heating systems or the like and indeed the very many 20 other uses that such designs lend themselves. Such designs can be used for camping, boating mobile or permanent homes, emergency lighting situations etc. All electromechanical devices designed to convert spring, tension energy into electrical energy at a low rate of axial armature rotation are possible with the new designs.

25 The usefulness of the slow rotating transducer is proving to be the answer to the problem of fast depletion of spring energy spring stored energy systems. The fact that the central core, or peripheral core, or the direct current or alternating current, stator, generator, alte nator or whatever name is given to the transducing arrangement, rotates slowly, provides a means by which electrical energy can be provided to give the O required number of cycles of alternating current or direct current or magnetic field, over

a prolonged period. The provision of such transducers to spring loaded energising systems,extends the useful time during which the spring energy can gradually be released. is

J 5 The slow rotating transducer system combined with springs is therefore crucial to the longevity of energy release in the above systems The actual design of the transducers will vary depending on the performance requirements. Generally, the design of the multifields will require that the field

10 windings be so arranged that the permanent or induced magnets will rotate about the field windings: In a typical arrangement for the multifield slow rotating transducer the

field windings will be arranged about the periphery of a given radius. The windings

will be assembled to an arrangement which can be a printed circuit board or whatever arrangement is convenient for the given purpose. The circumventing magnetised 15 members rotate about the given central axis and by structural arrangement are rotated via cogs wheels, pulleys, chains or the like and are energised by the transfer of the kinetic energy released from the unwinding spring.

The multifield generator having two poles ie the "north" and the "south" poles will have

20 two poles per winding. As the wire winding moves through the held a current of moving electrons is created and this current of electrons is conducted via the wires to either move via high resistance wire or gas, or to create magnetic fields that generate

microwaves, sound, heat or move mechanical parts.

25 The slow rotation of the axial part of the transducer can be translated into a variety of moving parts. The speed of movement of distal parts can be modified by means of pulleys, gears levers or the like to translate the movement of the axial parts into the desired mode.

30 The generation of electrical current in the transducer by means of a moving magnet about a circumventing periphery has the advantage of being able to move along large distance inducing a current in many windings. As the field moves from one winding

on to the next a sequence of generated current is fed to the grid of the system being driven. The freque,ncy of the transducer Cutout therefore can be varied by means of 3 5 altering the number of windings which the moving field of the magnet intersects. For

( 5 our spring energised systems the 100 pole arrangement will produce 50 cycles per second for each complete rotation of the circumventing magnet arrangement. The slow rotation compiled with the use of spring energising systems provides a means whereby the energy of the spring can be released at a suitable slow rate to allow the use of springs in a multitude of differing energy requiring systems.

10: The use of springs ought to have a considerable advantages over battery driven systems and given that the potential energy release from the coiled spring can be controlled by the multifield design then it becomes advantageous to consider other ways of conserving the available potential energy in the coiled spring: Basically

the arrangement required for the constant force spring activity is that the metal tension is designed to fit a diameter chosen for the Torque. Output Drum (TOD), and the end of the wound spring is then fixed to the storage drum. In this way the tensed spring of whatever material is secured to two drums separated by a given 20 distance and arranged in a desired way to optimise the available space. The storage drum is generally the smaller one of the two because the spring tension is maximised The loose end of the coiled spring is attached to the larger drum, the TOD, which is the drum attached to the rewinding handle and "charges up" the energy prior to its controlled release.

In order to extend the time during which the spring can usefully release the stored energy a number of ways are available to the industry to conserve the potential energy and therefore extend the time of useful activity.

30 In any given system, the charged spring arrangement has a given amount of stored energy. The way that the available energy is tapped will determine the total useful life of spring and all accessories and non essential items or steps within the system will require a given amount of energy to work the parts. All mechanical devices which move require energy to create that motion.

5 The present invention is therefore intended to remove all unnecessary working parts and with the unique design of the multifield transducer no gears are required to step up the

rate of rotation. As an example only, the existing way of generating the required output from transducers is to rotate the generator at a relatively fast speed. In practice most of these devices work at about 1000 rpm to 3600 rpm. The gearing required to translate the 10 slow release of energy from the torque drum and the slow recoiling motion of the storage drum requires a step up gearing of about 1000 to 1 or more. very considerable quantity of energy is dissipated by these arrangements and drastically reduces the available energy for the driving of the transducer.

15 In our specified system, the storage drum is connected directly to the axle of the multifield generator. Each revolution of the storage drum therefore directly drives the

multifield transducer to generate the required output, although gearing arrangements

may be employed.

90 The output current is connected to a potential difference device that acts as a break on the rate of release of energy from the torque drum. Many different designs are available to act as a potential back pressure system but optimised designs will be determined by the system's requirements. It is therefore proposed to establish in these designs a system of baclc pressure devices that will electronically control the rate of spring 'off load". In 25 this way gears will become redundant and the available energy will be used to drive the transducer. Systems controlling the rate of a working machine are known as "governors". In embodiments of the present invention, mechanical and/or electrical governors can be used to control the rate of work.

30 As an example only, Figure 7 represents a schematic arrangement of the gearless system. Item I is the torque drum onto which the mechanical winding handle 8 is to be attached. The constant force spring 2 extends to the storage drum 3 and forces the drum to rewind. The storage drum is attached by a direct drive shaft to the axle of the multifield transducer 4. As the magnets traverse the coils the generated current pass via

3 j the circuitry 5 to the potential difference device 6. This device controls the rate of

- -hi S multifield transduced rotation and therefore the rate at which the spring rewinds onto

the storage drum 3. The system includes other arrangements which are incorporated to soak up surplice electrical energy 7 and release the stored energy as it builds up to allow controlled output. These devices are generally incorporated in the control elements of the specification, (see Figs I to 4).

In all these arrangements there is always surplice energy that cannot effectively be utilised and with this in mind it is proposed to "soak" up the surplice energy by designing a capacitor into the circuit. The surplice energy is stored in the capacitor and as the level of charge is depleted in the capacitor the potential difference gate reduces 15 the back pressure to allow the unwinding to resume. The process is repeated until the spring is completely rewound onto the storage drum.

Considerable saving of energy are achieved by this arrangement.

20 Research continues into ways of improving the control of the energy release of the constant force spring system.

In all cases with spring energy loaded systems the limiting factor is the total energy stored in the coiled spring. As the designed machine works it depletes the stored energy 25 and the problem of the rate of depletion of the storedqenergy is being reduced by the above generator design by reducing the rate at which the generator rotates to produce the required emf (electromotive force). In our design the coiled spring contains enough energy to provide the total requirement for the designed machine for many hours.

30 The multifield generator is a transducer, converting potential energy stored in the

reverse coiled spring, into mechanical energy by means of being allowed to re-coil into its energy.depleted shape and rotating the slow rotating generator to produce emf. In all cases the design is optimised to provide the most efficient use of the available stored energy at the slowest rate of spring depletion.

in\ - - 5 The induced angular motion rotates an axially assembled permanent magnet arrangement that interacts with the stator members circumventing the rotor. As the magnetised sections interact with the stator castellations emf is induced by the magnetic forces to induce an electric current in the windings of the stator. This electrical current is used to drive the various appliances and applications that are being considered.

10 Fig 8 represents the basic concept of the slow rotating generator design. The central rotor is situated about the axis of the generator and has projecting from the circumference of the rotor, teeth sections, via which is projected the magnetic field of

the permanent magnet. In less detail, Fig 8A demonstrates the magnetic field of the

rotor runs axially from the South pole to the north pole "C" to provide a South and 15 North pole at each end of the rotor "A" and "B". This toothed design of sections which has sandwiched between the sections the permanent magnets whose magnetic flux travelling from south to north leaves the section via the aligned teeth sections to enter the castellation of the stator. A south pole is induced in the stator poles aligned with the stator poles in the north end of the rotor. The flux travels axially through the stator back 90 metal to the front of the rotor where it enters the rotor teeth at right angles to the line of flux at the other end of the rotor. The magnetic flux induces an electrical current in the stator coils.

As the axle of the rotor is further turned by the motion of the uncoiling spring the rotor 25 teeth and stator castellations are moved from this position of minimum reluctance to a position of maximum reluctance ie a position where the teeth of the rotor stacks are misaligned or offset by the predetermined optimised degree, in relation to the castellations of the stator. As the rotor moves to a new position of maximum alignment of the rotor teeth and the stator castellations there is induced a phase current in the coils 30 of the stator, see Fig 8A.

The word "Stack" is in this application used to describe the arrangement of a single unit producing current in our slow rotating generator. The unit consists of an axis, a permanent magnet mounted on the axis and encased in a soft metal core that forms the 35 active member transferring magnetic flux into the stator core by means of teeth. The

5 stator neck is wrapped in a conductor wire that is the active component releasing electrons into the circuit as it is subjected to the induced magnetic flux. The stator arrangement can have one, two or many poles. Each pole can be an individual phase or all the stator poles can be wound by a continuous wire to produce a multi pole single phase. See Fig 8, which has 48 poles in a single phase or Fig 18 (see below), which has 10 8 poles in a single phase.

. The design of the multifield generator then is a system which has a permanent magnet

sandwiched between toothed members with a variable number of teeth on each member or section of the rotor. The teeth of this member are offset in relation to the axial 15 position of the teeth of the following member. Depending on how slowly the rotor is designed to rotate as to how many of such magnetised members are aligned and sandwiched between the permanent magnets along the rotor section. In Figure 9, four sets of sections are demonstrated each relating to one stack' as an example only, and show the sections assembled along the axis of the slow rotating, enerator.The greater 20 the number of sections on the axle, the slower the rotations The number of teeth per stack and the number of sections for specific applications can be optimised. The sections size the permanent magnet axle etc specifications are optimised in the x, y and

z directions.

25 Figure 10 illustrates an engineered set of two members mounted on a permanent magnet situated about the axis of the unit. In the slow rotating generator, rotating at a given rate, the frequency of the electrical current can be varied by increasing the number of stacks on the z axis of the rotor and by increasing the number of teeth on the member.

30 Each of the rotor teeth interacts with the casteiiations (teeth) of the stator. The castellations, of which five per pole is demonstrated in Figure 11, are so designed that they interact with, as an example only, the teeth of the rotor and are separated by a small air gap. The castellations converge into a central member of the stator which continues and expands to form the casing of the generator. Each member has a 35 conductor wire coiled around the entire section to form one pole. The number of poles

f - 5 per stack provides a means of specifying the frequency of the generator for a given rotor speed and the number of turns of the conductor wire of a given diameter about the pole, provides a means whereby the voltage can be specified and the total amount of conductor used per stack provides a means of controlling the magnitude of the current.

As the number of stacks on the rotor axle increases so the length of the generator in the 10 z direction increases. As an example only, the length of the generator for a two stack design will be say 50mm long and the length of the four stack generator will be 90mm long. The length of the stator will be complimentary to the length of the stacks.

Similarly for a stack of "n"th number, giving an "n"th length, the sum of the stack lengths in the z direction, will also be the "n"th length. Only the practical requirements l 5 will determine the number of stacks assembled in a given generator to give a generator of"n" length plus the end pieces Figure 12 illustrates schematically the arrangement of the various sections of these slow rotating generators. The outer casing A, of the generator forms the body from which 20 extend the stator poles, B. Each pole has a wire conductor winding C, that coils around the body of the stator. The stator terminates in the castellations D that are separated by an air gap from the rotor teeth. The size of the generator can be made to vary by altering the parameters in many ways including directions x, y and z. The stator castellations and the rotor teeth are shown in Figure 13. The characteristics of the design are that as the rotor teeth "A" move about the circumventional paths the permanent magnet's OF sets up a magnetic flux pattern that varies with the position of the rotor teeth. The position of the rotor affects the total reluctance of the magnetic 30 circuit. The minimum reluctance position is achieved when the rotor teeth "A" and the stator castellations "B" are directly in line (see E',E in Fig 13) and the maximum reluctance is achieved when the rotor teeth and the stator castellations are un-aligned (see F',F in Fig 13). Item C is the air gap between the rotor member and the stator..

(a - 5 The movement of the rotor from the maximum un-aligned position (F', F) to the aligned position (E',E) causes electrons to flow around the stator "C", windings (see Fig 12).

The design feature of these generators is that slow rotation of the axial member produces the required current, frequency and voltage because of the number of stacks 10 established along the axis of the rotor member. The intersection of the magnetic fields

induces current in the stator windings. The generated current is utilised to do worlc be it to produce light energy heat energy, mechanical movement of assembled technology, or produce electromagnetic wave radiation. Alternating current (AC)' direct current (DC) or other forms of energy can be created with this system.

In continuity of research the optimization of the tooth section on the stack assembly and the castellation section of the field winding member is evolving to provide a pointed

section across the air gap.

20 In an attempt to optimise the time span "t3' (see Figs 21A, B. C) of the tooth/castellation interaction a pointed configuration has been devised whereby the time interval during which the two members are at the minimum reluctance position is the shortest period possible. This is best achieved with a pointed tooth design and a pointed castellation design. The two members are suitable aligned and intersect for the shortest period of 25 time possible. These conditions provide for the best induction of the emf Other ways of improving speedy intersection between these members is to increase the size of the radius of the stack with a corresponding increase in the casing size. The advantage of a larger diameter unit is that more teeth can be cut into the stack members 30 and that more stator units can be arranged along the bigger circumference of the casings. For slow rotation of the axial armature the larger number of elements will reduce the torque and generate a better emf, higher voltage and produce a higher frequency output.

, 5 Fig 13a illustrates a modified design of the tooth and castellation sections across the air gap of the slow rotating generator. Sections A and B are in this case pointed.

The geometry of the tooth and castellation design need further explanation Because the slow rotating generator (SRG) intersects the axial member (AXM) and the stator 10 castellation (C) at a slow speed the total time the tooth and castellation interact is very long in comparison to the time conventional generators rotating at 3000rpm interact our design lends itself to new geometric interpretation.

The optimised version of the SRG will determine at say Irps, given the circumferential 15 parameters the time required for the axial member to traverse the stator (C). This time is exactly calculated to induce in the stator core the optimum magnetic flux to the value of the "Knee Point". The time interval required for this induction will determine the geometry of the axial member tooth and stator castellation.

20 The use of the spring generated energy systems presents a problem of controlling the rate of spring offload. As the machine is switched on to do world the spring starts to unwind releasing the stored energy thus rotating the generator to provide the electrical enery..The problem exists of providing a suitable system to provide the exact rate of off loading of stored energy. Systems that control the rate of working of a given 25 machine are called governors. A number of systems are available off the shelf for such control and the following are specified in addition Figure 14 represents a mechanical means of controlling the rate of off load of stored energy. In this design a solenoid 9 is used to mechanically stop the rotation of the 30 spring containing spool. The spring is allowed to release energy and turn the generator thus producing electrical current. This current is passed to a capacitor 'which when say, three quarters full will initiate a circuit 11 via which the generated energy will activate the solenoid to push the armature into contact with the active spool. In this case and as an example only, tithe armature is attached to a cog section that interacts with a suitable 3 5 toothed arrangement on the spool to physically interact with the cogs and prevent

r: I! 5 further rotation. When the capacitor charge has depleted to say and as a example only one quarter of its capacity, the available energy is channelled to a circuit de-activating the solenoid. The annature is withdrawn andthe spring containing spool is again allowed to unwind, turning the generator in the process.

10 The release of stored energy is thus controlled by mechanical interaction of the solenoid and the spring containing spool or by the interaction of any of the moving parts, whichever is the most suitable for the intended control of spring unwinding.

Figure 15 represents an alternative method of controlling the rate of spring off loading 15 In this case the rate of rotation of the generator is controlled by the necessary elements of circuitry designed to control the rate of the unwinding of the spring containing spool.

The generated current can in one mode be controlling circuitry that will allow a given quantity of generated electricity to be used to energise the end source of the unit and as the required amount to energy is achieved the controlling circuitry is then diverted to a 20 back electromotive force (emf), that will retard the rate of the generator rotation. The back emf is controlled by the control elements 10 and can be achieved in a number of different ways with standard technology and circuit design.

In a further embodiment of the back emf concept,the design can be worked off a 25 capacitor which is designed to have sensory circuitry with Supervisory IC's 11 (see Fig 14). These devices are basically a low power dual under/over voltage detectors. The trip points and the hysteresis ofthe two voltage detectors are individually programmed via external resistors to the desired voltage values. These programmable detectors can be used to control the rate of rotation of the generator by monitoring various parameters 30 to the designers requirements. The supervisory ICs can be used in a number of specific designs that can monitor and initiate back emf circuitry to provide a number of control parameters, directly or indirectly retarding the rotation of the generator or independently controlling the rate of rotation of the off loading spring spools.

- 5 A further controlling mechanism is a circuit controlled clutch motor that will retard the rate of off loading. These motors can be attached to any suitable assembly to control the rate of rotation of the spools or generator. These clutch motors can be controlled by independent circuitry, off the in line capacitor, or speed regulating monitors actuating the back emf in the motor, creating delays in spool off load or other suitable controlling 10 positions.

The design of the actual elements of the generator is open to a considerable number of interpretations and as an example only and in order to maintain the fast intersection between the permanent magnet field and the iron field core, a large diameter stack

15 arrangement is demonstrated in Figure 16.

Here, the teeth of the axial member are cut into the circumferential parameter allowing a large number of stator poles to be arranged about the circumference of the axial members. The larger the diameter of the stack the greater the number of stator poles 20 that can be assembled along its circumference. In Figure 16, eight stator poles are assembled about its circumference.

If this diameter dimension is fixed for practical reasons, the generator performance can be enhanced by extending the design in the z direction to extend the length of the 25 generator (see Fig 17), so that, the next stack arrangement can interact with the stator poles to induce further e m.f. Figure 17 demonstrates as an example only a 16 stator pole I & 2, arrangement, wherein the forward stator output 1 is doubled by a second 8 pole 2, arrangement, situated and offset at the required amount further along the z axes.

The arrangement can be further extended by additional stacks to provide any number of 30 field winding required. Each planar assembly of poles comprises one staclc.

The slow rotating generator design can therefore be extended in a number of ways be it by increasing the diameter of the unit and providing a slim but wide generator that can have a rate of axial rotation substantially lower than one revolution per second, 3 5 generally aimed at. The large circumference of such a design would facilitate a speedy

- 5 interaction between the castellations and teeth, in practice, having the same effect of field intersection that is achieved by rotating generators at a fast rate. The slow rotation

is achieved by increasing the various parameters to in effect replicate conditions achieved by generators at fast rates of rotation. Clearly, the extra engineering is costlier, but in situations where off load times are all important, the extra cost is justified.

Figure 18 demonstrates the pointed section castellation 1, and tooth 2, design, that can be assembled in the already described way, comprising an 8 pole, single phase, single stack assembly.

1 S All the described designs can of course be reversed. to provide motors by feeding current into the field windings, generating an electric Reid that in turn is made to rotate

the axle of the motor on which are situated the toothed permanent magnets The process of rectification causes a drop in the forward voltage, which is dependent on Z0 the nature of the elements used in the construction of diodes. When standard silicon diodes are used to rectify this current, there is fourth voltage drop of about 0.7 volts for each diode used.

AC generators need to be rectified if DC current devices are to be powered.

25 Alternatively, although much more complex, commutation arrangements can be incorporated into the armature of the generator, so as to produce a DC output.

Winding the handle will allow the directly linked generator (Fig. 7) to generate electricity that is channelled into the storage system 7. Rechargeable batteries can be 30 installed in versions of this embodiment. The advantage is that the user charges the storage system at the same time as the spring is being wound onto the TOD Fig 19, represents a side view of a single stack showing only the stator 1, it's winding 2, the permanent magnet fixed to the axle of the generator. In this example magnetic filed

() 5 4, is demonstrated to show how the soft metal core encasing the permanent magnet is subjected to the permanent magnet field. This unit comprises a single stack.

Fig 20 demonstrates a four stack arrangement. In this case Stack 1, 2, 3 and 4 form the generator, each stack being one phase. Stack 2 is activated and demonstrates the 10 magnetic field inducing stator flux. Note that the magnets are aligned in such a way

that the magnetic filed is opposed at the terminal ends of each magnet.

The provision of the multi stack arrangement allows the design of a feature in these generators which limits the loss of magnetic flux due to magnetic leakage at the 15 terminal end of the permanent magnet of each stack. To reduce this leakage, it is proposed to assemble the permanent magnets in such a way that the magnetic poles of adjacent stacks are the same (See Fig 20). In this way the same poles repel each other's fields thus concentrating the field within the stack Al. This arrangement

concentrates the available magnetic field directly into the AXM where it is used to

20 induce the maximum magnetic flux in the stator body (See Fig 20).

As already described, Fig 13a shows a point geometry for the (A<vI) and (C).

However, Fig 21 A, B and C demonstrate how the tip of the geometrical configuration can be adapted to facilitate the optimum flux induction. Depending on many 25 parameters than need to be considered as to the length of"D" see Fig 21 A, B and C. The principal one is that the time "t" required for the axial member and the stator castellation to interact for long enough to induce a magnetic flux in the stator to provide a flux density to the "Knee Point".

30 The SRG also allows the further improvement in the design of the magnetic flux induction by means of reducing the space between the AXM teeth and the stator. In this design it is intended to substantially reduce the air gap between the active members thus providing a means whereby the magnetic flux induced in the stator core is substantially improved. The smaller the air gap the stronger the field acting on the

35 stator core. It is proposed to provide an air gap of 10 and no more than 25 microns.

5 This size gap will provide an excellent induction of magnetic flux: Fig 13a demonstrates the pointed sections of the (Ah) and castellation geometry. It also demonstrates the air gap C, between the stator and axial section. The minimum reluctance point is demonstrated by the alignment E' and E and the maximum alignment position F' and F. See Fig 13a. The geometry of the point is assessed to l O prevent saturation of magnetic flux. See Fig 21 A, B and C. A most useful characteristic of the slow rotating generators is that because of the slow rotation the rate of heat generation is so low that the generator never suffers the reduction of flux induction found in conventional generators rotating at high rates of 1 5 revolution.

Loss of magnetised properties is well understood in generators that are subjected to heating effects. Magnetised materials loose their magnetic properties if subjected to high heat environments and for that reason many heat dissipating systems have to be 20 installed in electrical machines. Current motors and generators revolving at high speed have to have end pieces made from a good conductor of heat to dissipate heat from the machine. These metal members are expensive cast and tool engineering pieces that add hugely to the cost of the finished generator. With the obviation of heat build up it becomes possible to have extruded or pressed members made out of synthetic materials 25 such as thermoplastics. It is proposed therefore to manufacture the end pieces for these slow rotating generators out of composites, synthetics, thermoplastics and the like, substantially reducing the cost of manufacture.

The additional benefit to the SRG design with multi pole, poly phase, multi stack 30 design is that the torque ripple is minimised. The sequential power delivery provides for low torque transfer and allows the generator to deliver the output with minimised torque transfer from maximum reluctance position to minimum reluctance position fl

5 At the end of each axial arrangement of stacks small permanent magnets that are designed to deflect the magnetic field of the terminal magnetic poles are installed and

are calculated in size only to contain the terminal pole leakage (See Fig 22 and 22a).

Claims

ct CLAIMS:

1. An electrical generator comprising a plurality of units, each unit comprising a rotor and a stator, the rotor having a first end and a second end, an axis of rotation of the rotor passing through the first and second ends, wherein the rotor comprises a permanent magnet with a North pole at the first end and a South pole at the second end, the rotor being provided with a plurality of circumferential teeth at the first and second ends and is located within a stator having a plurality of windings disposed to co-operate with the teeth, the units being coaxially mounted on a common rotational shaft.

2. A generator according to claim 1, wherein the teeth of the first end of each rotor are circumferentially staggered with respect to those at the second end.

3. A generator according to either preceding claim, wherein each stator has respective sets of pole windings for co-operating with the teeth of the first end of the respective rotor and for co-operating with the teeth of the second end of the respective rotor.

4. A generator according to any preceding claims, wherein each stator surrounds the respective rotor and the pole windings of the stator are formed on respective projections radially extending inwardly towards the respective rotor.

5. A generator according to any preceding claim wherein each rotor comprises at least 4, preferably at least 12, more preferably at least 24, especially at least 48 teeth.

6. A generator according to any preceding claim, wherein each rotor comprises at least 4, preferably at least 12, more preferably at least 24, especially at least 48 teeth.

7. A generator according to any preceding claim, wherein the teeth of the rotor of each unit are angularly displaced with respect to the teeth of the rotors of each other unit.

f - j SO -

S. A generator according to any preceding claim, wherein the windings of a stator of a first unit are separate from the windings of a stator of each other unit.

9. A generator according to any preceding claim, wherein the facing poles of adjacent rotors are of opposite polarity.

10. A generator according to claim 7 wherein a respective permanent magnet is located at each end of the shaft, the permanent magnets being additional to those of the rotor.

11. A generator according to any preceding claim, further comprising mechanical means for storing energy for driving the rotor.

12. A generator according to any preceding claim further comprising electrical means for storing electrical energy output by the stator windings.

13. An electrical generator substantially as hereinbefore described with reference to any one or more of the accompanying drawings.

14. An electronic apparatus connected to be powered by a generator according to any of claims 1-13.

15. A lighting unit connected to be powered by a generator according to any of claims 1-13.

16. A domestic appliance connected to be powered by a generator according to any of claims 1-13.

( -7 Amendments to the claims have been filed as follows 3\ CLAIMS:

1. An electrical generator comprising a plurality of units, each unit comprising a rotor and a stator, the rotor having a first end and a second end, an axis of rotation of the rotor passing through the first and second ends, wherein the rotor comprises a permanent magnet with a North pole at the first end and a South pole at the second end, the rotor being provided with a plurality of circumferential teeth at the first and second ends and is located within a stator having a plurality of windings disposed to co-operate with Me teeth, the units being coaxially assembled in sequence win the rotors ofthe units coaxially mounted on a common rotational shaft.

3. A generator according to either preceding claim, wherein each stator has respective sets of pole windings for co-operating with the teeth of the first end of the respective rotor and for co-operating with the teeth of the second end of the respective rotor. 4. A generator according to any preceding claim, wherein each stator surrounds the respective rotor arid the pole windings ofthe stator are Conned on respective projections radially extending inwardly towards the respective rotor.

5. A generator according to any preceding claim, wherein the stator of each unit comprises a plurality of teeth for cooperating with the teeth of the respective rotor.

6 A generator according to any preceding claim wherein each rotor comprises at least 24, preferably at least 48 teeth.

7. A generator according to any preceding claim, wherein each rotor comprises at least 24, preferably at least 48 teeth.

j 8. A generator according to any preceding claim, wherein the teeth of the rotor of a first unit are angularly displaced win respect to the teem of the rotor of another unit.

9. A generator according to any preceding claim, wherein the windings of a stator of a first unit are separate from the windings of a stator of another unit.

10. A generator according to arty preceding claim, wherein Me facing poles of adjacent rotors are of opposite polanty.

11. A generator according to claim 1 wherein a respective permanent magnet is located at each end of the shah, the permanent magnets being additional to those of We rotor. 12. A generator according to any preceding claim, being for use at low rotational speed. 13. A generator according to any preceding claim, further comprising mechanical means for storing energy for driving the rotor.

14. A generator according to any preceding claim farther comprising electrical means for storing electrical energy ought by the stat.or windings.

15. A generator according to claim 14, wherein the mechanical means is for driving the rotor at low rotational speed.

16. An electronic apparatus connected to be powered by a generator according to any of claims 1-15.

17. A lighting unit connected to be powered by a generator according to any of claims 1-lS.

18. A domestic appliance connected to be powered by a generator according to any of claims 1-15.